This study presents a comprehensive phylogenetic analysis on Batrachospermaceae based on key taxonomic identifiers(rbcL,psaA,psbA,and COI-5P)from some genera.To systematically explore the phylogenetic relationships an...This study presents a comprehensive phylogenetic analysis on Batrachospermaceae based on key taxonomic identifiers(rbcL,psaA,psbA,and COI-5P)from some genera.To systematically explore the phylogenetic relationships and taxonomy within Batrachospermaceae,we integrated molecular and morphological data,and explored the phylogeny,character evolution,and ancestral geographical origin and provided a theoretical support for the classification and geographic origination of Batrachospermaceae.Our findings reveal distinct relationships within the phylogenetic tree.Notably,10 genera(Sirodotia,Batrachospermum,Tuomeya,Volatus,Lympha,Nothocladus,Torularia,Sheathia,Nocturama,and Petrohua)are closely associated in the rbcL phylogenetic tree.Additionally,four genera(Kumanoa,Hoefkenia,Notohesperus,and Virescentia)exhibit high support ratios,indicating their close interrelations.Other genera,including Paludicola,Visia,Acarposporophycos,Macrosporophycos,Visioidea,Balliopsis,and Psilosiphon,exhibit clustering traits.Furthermore,the multigene sequences provide a robust support for Montagnia that forms a monophyletic group.Ancestral reconstruction of morphological characters identifies nine primitive character states,including whorl,fascicle length,cortical cells,secondary fascicles,the shape of carpogonical branch,spermatangia,carposporophyte,carpogonium and trichogyne,with Visia likely representing ancestral traits in Batrachospermaceae.Furthermore,geographical origin maps suggest a potential common ancestral of Batrachospermaceae origin in the American continent.Additional to conventional analyses,including evolutionary and ancestral reconstruction investigations into key morphological characters,we attempt to reconstruct the biogeography within the Batrachospermaceae,thus contributing to a nuanced understanding of its origin.展开更多
Stephanodiscaceae is one of the most diverse family of the freshwater centric diatoms.However,the scarcity of whole plastome data poses a significant challenge to the undertaking of genomic studies on this taxonomic g...Stephanodiscaceae is one of the most diverse family of the freshwater centric diatoms.However,the scarcity of whole plastome data poses a significant challenge to the undertaking of genomic studies on this taxonomic group.We collected data on the plastid genomes from 33 members of the Stephanodiscaceae and its close relatives,including 12 newly-sequenced genomes and 21 deposited in National Center for Biotechnology Information(NCBI).Phylogenetic trees are yielded five major clades based on homologous genes.The features of the plastid genomes,including repeat sequences,codon usage,and selection pressure for each clade,are analyzed.The paper makes a contribution to the field of diatom genomics by describing the structural characteristics of the plastid genomes in the Stephanodiscaceae and its closely related species,complemented by related analyses.It provides crucial data that will serve as indispensable references for future research.展开更多
Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis...Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis from Ailao Mountain,Yunnan,China.It is closely related to Ottia and a new order Ottiales was proposed for these genera.Pauciramus has unique combination of morphological characteristics including the following:plants caespitose and densely pulvinate,slender uniseriate filaments with well-developed rhizoids,rarely branched,cylindrical vegetative cell with a single,ribbon-shaped and parietal chloroplast,reproduction by tetrasporangia,and dense sporangial branchlet only at the upper portion of filaments.Phylogenetic analysis of sequence data from the plastid ribulose-1,5-bisphosphate carboxylase-oxygenase large-subunit(rbc L),small subunit gene of the ribosomal cistron(SSU)and barcode region near the 5′end of the mitochondrial cytochrome oxidase subunit I(COI-5P)indicated that:the new taxon,P.yunnanensis,was in a well-supported clade with Ottia meiospora,and this clade was sister to order Palmariales and Acrochaetiales.To adhere to the principle of monophyly,a new freshwater order Ottiales including Ottia and Pauciramus is proposed.Despite the high sequence interspecific divergences and obvious morphological differences between genera Ottia and Pauciramus,seems impractical to establish a new family for a monospecific genus.Therefore,we temporarily classified Pauciramus into the family Ottiaceae,and made necessary revisions to the description to accommodate this genus.展开更多
We report on eight species of the freshwater diatom genus Gomphonema from aquatic habitats from the Yuntai Mountains of Henan Province,China.This work represents the first detailed descriptions of the freshwater diato...We report on eight species of the freshwater diatom genus Gomphonema from aquatic habitats from the Yuntai Mountains of Henan Province,China.This work represents the first detailed descriptions of the freshwater diatoms from this centrally-located province in China.Of the eight taxa considered,five are new to science and another is given a"cf."designation.Four of the eight species are similar in morphological features to other,"classical"species,with external areolar occlusions forming C-shaped openings.Another species is astigmate,and has distinct siliceous papillae located marginally on the exterior of the valves;this morphology has not been recognized previously for the genus.Two of the species have internal areolar and stigma occlusions.The diversity of morphological types of species in Gomphonema may relate to the ecosystems,with more diverse ecosystems harboring greater diversity of these morphological groups of Gomphonema.展开更多
The genus Selenastrum comprises common coccoid green algae found in diverse habitats worldwide.This genus has a complex taxonomic history,but recent applications of molecular phylogenetic methods have removed some mem...The genus Selenastrum comprises common coccoid green algae found in diverse habitats worldwide.This genus has a complex taxonomic history,but recent applications of molecular phylogenetic methods have removed some members with similar morphologies from Selenastrum and established new genera.However,due to the lack of available molecular sequences and isolates,the species diversity of the genus has not been fully explored.We conducted a detailed examination of the taxonomy of genus Selenastrum based on 11 new strains collected from China.The multi-disciplinary study utilized morphology,ultrastructure,and phylogeny based on multiple molecular markers,and ITS-2 secondary structure.All the included strains of genus Selenastrum were clustered into two distinct clades.The members of one clade were similar morphologically to the type species Selenastrum bibraianum,whereas the strains of the other clade had distinctly different colony structures.Based on the latter clade’s larger colony cell numbers and independent phylogenetic position,we proposed that it as a new species of the genus Selenastrum,namely Selenastrum densum sp.nov.Additional taxa sampling and molecular data will help to discover additional new species and clarify the validity of morphological taxonomic characteristics within the genus Selenastrum.展开更多
Salt stress is an abiotic stress to plants in especially saline lakes.Dunaliella,a halophilic microalga distributed throughout salt lakes and seas,can respond to different salinity stresses by regulating the expressio...Salt stress is an abiotic stress to plants in especially saline lakes.Dunaliella,a halophilic microalga distributed throughout salt lakes and seas,can respond to different salinity stresses by regulating the expression of some genes.However,these genes and their function and biological processes involved remain unclear.Profi ling these salt-stress-related genes in a high-salt-tolerant Dunaliella species will help clarify the salt tolerance machinery of Dunaliella.Three D.salina_YC salt-stress groups were tested under low(0.51 mol/L),moderate(1.03 mol/L),and high(3.42 mol/L)NaCl concentrations and one control group under very low(0.05 mol/L)NaCl concentration and 3 transcriptome results that were deep sequenced and de novo assembled were obtained per group.Twelve high-quality RNA-seq libraries with 46585 upregulated and 47805 downregulated unigenes were found.Relative to the control,188 common differentially expressed genes(DEGs)were screened and divided into four clusters in expression pattern.Fifteen of them annotated in the significant enriched Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)were validated via qPCR.Their qPCR-based relative expression patterns were similar to their RNA-seq-based patterns.Two significant DEGs,the geranylgeranyl diphosphate synthase coding gene(1876-bp cDNA)and diacylglycerol O-acyltransferase coding gene(2968-bp cDNA),were cloned and analyzed in silico.The total lipid content,superoxide dismutase specific activity,and betacarotene content of D.salina_YC increased gradually with increasing salinity.In addition,the expression of 11 validated genes involved in fatty acid biosynthesis/degradation,active oxygen or carotenoid metabolisms showed significant changes.In addition,algal photochemical efficiency was diminished with increasing salinity,as well as the expression of 4 photosynthesis-related genes.These results could help clarify the molecular mechanisms underlying D.salina responses to the Yuncheng Salt Lake environment and lay a foundation for further utilization of this algal resource.展开更多
Microorganisms play a key role in aquatic ecosystems.Recent studies show that keystone taxa in microbial community could change the community structure and function.However,most previous studies focus on abundant taxa...Microorganisms play a key role in aquatic ecosystems.Recent studies show that keystone taxa in microbial community could change the community structure and function.However,most previous studies focus on abundant taxa but neglected low abundant ones.To clarify the seasonal variation of bacterial and microalgal communities and understand their synergistic adaptation to diff erent environmental factors,we studied the bacterial and eukaryotic phytoplankton communities in Fenhe River that runs through Taiyuan City,central China,and their seasonal co-occurrence patterns using 16S and 18S rDNA sequencing.Results indicate that positive interaction of eukaryotic phytoplankton network was more active than negative one except winter,indicating that the cooperation(symbiotic phenomenon in which phytoplankton are interdependent and mutually benefi cial)among them could improve the adaption of microbial community to the local environmental changes and maintain the stability of microbial network.The main genera that identifi ed as keystone taxa in bacterial network were Salinivibrio and Sphingopyxis of Proteobacteria and they could respond to the variation of nitrite and make use of it,while those that identifi ed as keystone taxa in eukaryotic phytoplankton network were Pseudoschroederia and Nannochloris,and they were more susceptible to nitrate and phosphate.Mychonastes and Cryptomonas were closely related to water temperature.However,the loss of the co-occurrence by environmental factor changes aff ected the stability of network structure.This study provided a reference for analyzing relationship between bacteria and eukaryotic phytoplankton and revealing potential importance of keystone taxa in similar ecological domains in carbon,nitrogen,and phosphorus dynamics.展开更多
Batrachospermaceae is an important group of freshwater red algae.Available data of the latitude,longitude,and environmental factors on Batrachospermaceae distribution in Asia were analyzed to understand the geographic...Batrachospermaceae is an important group of freshwater red algae.Available data of the latitude,longitude,and environmental factors on Batrachospermaceae distribution in Asia were analyzed to understand the geographical distribution of Batrachospermaceae genera in Asia.Statistical analyses,including one-way ANOVA,correlation analysis,stepwise regression analysis,principal component analysis,and linear discriminant analysis were conducted to characterize variation in geographical distribution and growth environment.Results reveal high variation in geographical distribution and growth environment among different Batrachospermaceae genera in Asia.Specifically,correlations between latitude and all environmental factors exclusive of altitude are significant,and longitude is significantly correlated with all environmental factors except for average relative humidity.The geographical distribution and growth environment of different Batrachospermaceae genera significantly differed.Altitude,maximum temperature,average temperature,minimum temperature,average relative humidity,average wind speed,maximum wind speed,and atmospheric pressure all contributed to explaining differences in the geographical distribution of Batrachospermaceae genera.Combining the results of correlation analysis,stepwise regression analysis,and principal component analysis,all environmental factors contributed to the different geographical distribution of Batrachospermum,Paludicola,Sheathia,Sirodotia,and Remainder(the rest),all environmental factors but atmospheric pressure contributed to the different geographical distribution of Kumanoa,and all environmental factors but average wind speed and maximum wind speed contributed to the different geographical distribution of Virescentia.However,the correlation between these significantly related environmental factors and taxa is not necessarily causative,and many other environmental factors,such as temperature,pH,conductivity,shading,current velocity,dissolved oxygen,hardness,substrata types,and nutrients etc.,are likely to have an important impact on the geographical distribution of taxa,which is an important topic for future research.展开更多
The most prominent biological characteristic of Porphyridium purpureum is their unique extracellular sulfated polysaccharides that plays an important protective role against salt stress.Adaptation to stress is associa...The most prominent biological characteristic of Porphyridium purpureum is their unique extracellular sulfated polysaccharides that plays an important protective role against salt stress.Adaptation to stress is associated with metabolic adjustments.However,the molecular mechanisms underlying such metabolic changes remain elusive.This study presents the fi rst transcriptome profi ling of P.purpureum.A total of 8019 assembled transcripts were identifi ed,annotated,and classifi ed into diff erent biological categories and pathways based on a BLAST analysis against various databases.The in-depth analysis revealed that many of the diff erentially expressed genes in P.purpureum under salinities of 68 and 0 involved polysaccharide metabolism.A comparison of the gene expression levels under diff erent salinities revealed that the polysaccharide synthetic pathway was signifi cantly upregulated under the 68 salinity condition.The increased expression of the FBP,pfkA,CS,pgm,USP,UGP2,galE,and MPI transcripts in the polysaccharide synthetic pathway and the increase in ATP2 and ATP6 transcripts in the energy metabolic pathway revealed the molecular mechanism of high-salt adaptation.This sequencing dataset and analysis could serve as a valuable resource to study the mechanisms involved in abiotic stress tolerance in Rhodophyta.展开更多
Phytoplankton are not only the main bearer of the nitrogen cycle,but also a key link driving nitrogen cycle.However,most phytoplankton cannot directly use N_(2),and they must uptake nitrogenous nutrients(ammonium,nitr...Phytoplankton are not only the main bearer of the nitrogen cycle,but also a key link driving nitrogen cycle.However,most phytoplankton cannot directly use N_(2),and they must uptake nitrogenous nutrients(ammonium,nitrate,and urea)to meet their photosynthesis needs.We examined the uptake characteristics of several nitrogenous substrates using stable isotope technique and identifi ed the potential nitrogen transformations in the Fenhe River.Results revealed that spring phytoplankton community composed of mainly Fragilaria,Ulothrix,Microcystis,and Synedra.Urea can meet the spring partial nitrogen requirement of phytoplankton.The large uptake rate of urea depended on urease,chlorophyll a,and nitrate concentrations as shown in random forest models.Cyanobacteria explained more than 42.8%of the total abundance at all sites in summer.Upstream was dominated by Actinastrum,and Chlorella was relevant in the downstream section.The uptake rates of ammonium were higher than those of nitrate and urea.In addition,the random forest model demonstrated that ammonium,urease,and dissolved oxygen(DO)were the major contributors to the ammonium uptake rates.Ammonium was taken up preferentially in autumn and phytoplankton(Cyclotella,Chlorella,and Pseudanabaena)appeared to be able to respond to changes in nitrogen forms by adjusting their community composition.Structural equation models demonstrated that temperature-induced changes in DO directly affected the transformations of different forms of nitrogen.At the same time,dissolved organic carbon can directly act on nutrients and then indirectly affect enzyme activity.There were great diff erences in the positive and negative effects of different paths in the process of nitrate reduction to nitrite and then reduction to ammonium in time and space.These findings provide a better understanding of the underlying mechanism of nitrogen uptake and the influences of interaction between environmental variables on nitrogen transformations in urban river ecosystems.展开更多
The genus Sheathia consists of over 20 species primarily distributed in Asia,Europe,Oceania,North America,and Africa.However,the origin and evolution of this genus remain unclear.Two gametophyte stage specimens(SAS180...The genus Sheathia consists of over 20 species primarily distributed in Asia,Europe,Oceania,North America,and Africa.However,the origin and evolution of this genus remain unclear.Two gametophyte stage specimens(SAS18052 and SAS18523)and two“Chantransia”stage specimens(YTS19161 and YTS19017)were collected from Shanxi and Henan Provinces in China,respectively.Based on morphological data,isolates YTS19161 and YTS19017 were similar to Audouinella pygmaea,whereas the morphological characteristics of SAS18052 and SAS18523 were in good agreement with the circumscription description of S.longipedicellata.Molecular sequences of rbc L,COI-5P,and psb A were used to investigate the phylogenetic,evolutionary,and biogeographic origin of the genus Sheathia.The three molecular markers supported that the two gametophyte stage specimens belong to S.longipedicellata,while the isolates YTS19161 and YTS19017 were the“Chantransia”of S.longipedicellata.Ancestral area reconstruction and divergence time estimation speculated that Sheathia originated in North America,a portion of the Pangaea at approximately 328.07-184.73 million years ago(Ma).Our relaxed molecular clock analysis suggests that the Florideophyceae diverged approximately 741.04(894.36-631.70)Ma.The major divergences in this class involved the emergence of Nemaliophycidae[ca.662.01(779.83-580.51)Ma],and the split of orders Batrachospermales and Thoreales[ca.456.10(552.80-367.88)Ma].展开更多
Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarc...Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates.The morphological data revealed that isolate HN31(called group"MALL")was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia(>20μm in diameter).The 11 other isolates were grouped into three clusters,corresponding to the species Audouinella tenella,A.hermannii,and A.pygmaea.The morphological"Chantransia"stage of the species,reportedly belonging to the orders Batrachospermales,Thoreales,and the phylogenetically distant genus Audouinella,are very similar,resulting in the di fficulty to distinguish them based just on morphology.Therefore,molecular analysis of rbc L,UPA,and COI-5 P was conducted to infer the phylogenetic position of all isolates in this study.All"A.tenella"and"A.hermannii"sequences belong to order Batrachospermales,while the isolate HN31 was the"Chantransia"of Thorea hispida.The six other specimens varied morphologically,but they were within the circumscription of"A.pygmaea".All three molecular markers show that all"pygmaea"isolates also represent the"Chantransia"of T.hispida.Furthermore,results from this investigation proposed a new species—Sheathia qinyuanensis,corresponding to the isolates QY1 and QY2.展开更多
We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a r...We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin.Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae.Both morphological characters and the concatenated data of rbc L and SSU rDNA indicate that Discostella guiyangensis is a unique and new species.According to divergence time estimation analysis,Discostella guiyangensis is the oldest species among the Discostella species sequenced currently.In addition,we complement molecular data of Discostella asterocostata and Discostella stelligera.展开更多
Makinoella Okada is a genus of coccoid green algae belonging to the family Oocystaceae with typical morphological characteristics.Reports to date included only one type species.Since the genus is rarely reported,there...Makinoella Okada is a genus of coccoid green algae belonging to the family Oocystaceae with typical morphological characteristics.Reports to date included only one type species.Since the genus is rarely reported,there is a lack of taxonomic research.In this study,17 strains of this genus were collected from several different places in China,and their taxonomic studies were conducted based on morphological and molecular phylogenetic analysis.The phylogenetic results based on the analysis of ITS,chloroplast genes rbc L and tuf A showed that the genus was divided into two branches.One of the branches comprised newly collected algae.Compensatory base changes(CBCs)and hemi-compensatory base changes(hemi-CBCs)within the secondary structure of the ITS-2 confirmed the branches as two species.Compared with the type species of Makinoella tosaensis,the cell size of this new branch was only about 50%,and included 2-4 colonial cells.Therefore,based on the smaller cell size,simpler colony composition,independent phylogenetic position and CBCs and hemi-CBCs,we suggest that the new clade should be designated as a new taxon of Makinoella,namely Makinoella parva.Among the four molecular markers using in this study,the rbc L and newly introduced ITS are recommended for species separation,which can help further studies to revise the species and generic concepts of the family.展开更多
Virescentia guangxiensis,a new species of Virescentia from Guangxi,South China,is described and illustrated based on morphological observations and phylogenetic analysis.This species was distinguished morphologically ...Virescentia guangxiensis,a new species of Virescentia from Guangxi,South China,is described and illustrated based on morphological observations and phylogenetic analysis.This species was distinguished morphologically from other species by the presence of special expansion cells with a variable shape,obovoid,spherical,pear-shaped,located in the penultimate cells of primary or secondary fascicles,rarely terminal on primary fascicles,as well as by small whorls(250-350-μm wide)and short primary fascicles(5-7 cell stories).Phylogenetic analysis of molecular data from the rbc L and COI-5P loci supported the separation of the proposed new species from other species in the genus Virescentia.This is the first species of the order Batrachospermales reported in Guangxi and the second species of the genus Virescentia reported in China.This study expands the known species diversity and geographical distribution of freshwater Rhodophyta in China.展开更多
The newly described chrysophyte,Mallomonas vietnamica,is reported for the first time in China from specimens collected in Guizhou Province,SW China.The morphological characteristics were studied using light and scanni...The newly described chrysophyte,Mallomonas vietnamica,is reported for the first time in China from specimens collected in Guizhou Province,SW China.The morphological characteristics were studied using light and scanning electron microscopy.The species was described based on morphological characteristics,including cell size,scale size,dome,V-rib,and bristles.Subsequently,molecular sequencing of M.vietnamica was conducted and a phylogenetic tree was constructed based on concatenated SSU,LSU,and rbc L sequences.The phylogenetic tree led us to suggest raising a new section named Uncatusipedae for this species.This study provides new molecular data from the genus Mallomonas and enriches our understanding of the species diversity and geographical distribution of the genus Mallomonas in China.展开更多
Hildenbrandia is an early diverged lineage in Florideophyceae,Rhodophyta.The species diversity of this genus is still unresolved due to the simple morphology and limited molecular information.The mitochondrial genome ...Hildenbrandia is an early diverged lineage in Florideophyceae,Rhodophyta.The species diversity of this genus is still unresolved due to the simple morphology and limited molecular information.The mitochondrial genome of freshwater H.jigongshanensis was determined in this study.The freshwater H.jigongshanensis had a larger mitochondrial genome than the marine H.rubra and GC content was higher.Collinear alignment structure was observed between the mitochondrial genomes of H.jigongshanensis and H.rubra,except for one block that was encoded on the complement strand.More introns were found in mitochondrial genome of H.jigongshanensis than in H.rubra,and H.jigongshanensis shares the common feature with Bangiophyceae that two introns were distributed in cox1.Comparison of mitochondrial genome organization suggests that H.jigongshanensis preserves characters that could be hypothetically more similar to the ancestor of Bangiophyceae and Florideophyceae,which differ with previous studies based on chloroplast,and nuclear markers.More mitochondrial genomes and phylogenetic analyses combing nuclear,chloroplast and mitochondrial genomes are needed to clarify this discrepancy.Mitochondrion-based phylogeny in this study resulted in better solution at both the deep and recent derived nodes than single-gene phylogenies.Most protein-coding genes between H.jigongshanensis and H.rubra were identical except atp8,which was present in H.jigongshanensis while absent from H.rubra.This finding follows the trend that high Ka/Ks ratio genes are more frequently lost than low Ka/Ks ratio ones in red algae.展开更多
Dunaliella salina is a classic halophilic alga.However,its molecular mechanisms in response to high salinity at the post transcriptional level remain unknown.A unique halophilic alga strain,DS-CN1,was screened from fo...Dunaliella salina is a classic halophilic alga.However,its molecular mechanisms in response to high salinity at the post transcriptional level remain unknown.A unique halophilic alga strain,DS-CN1,was screened from four D.salina strains via cell biological,physiological,and biochemical methods.High-throughput sequencing of small RNAs(sRNAs)of DS-CN1 in culture medium containing 3.42-mol/L NaCl(SS group)or 0.05-mol/L NaCl(CO group)was performed on the BGISEQ-500 platform.The annotation and sequences of D.salina sRNAs were profiled.Altogether,44 novel salt stress-responsive microRNAs(miRNAs)with a relatively high C content,with the majority of them being 24 nt in length,were identified and characterized in DS-CN1.Twenty-one differentially expressed miRNAs(DEMs)in SS and CO were screened via bioinformatic analysis.A total of 319 putative salt stress-related genes targeted(104 overlapping genes)by novel miRNAs in this alga were screened based on our previous transcriptome sequencing research.Furthermore,these target genes were classified and enriched by GO and KEGG pathway analysis.Moreover,5 novel DEMs(dsa-mir3,dsa-mir16,dsa-mir17,and dsa-mir26 were significantly upregulated,and dsa-mir40 was significantly downregulated)and their corresponding 10 target genes involved in the 6 significantly enriched metabolic pathways were verified by quantitative real-time PCR.Next,their regulatory relationships were comprehensively analyzed.Lastly,a unique salt stress response metabolic network was constructed based on the novel DEM-target gene pairs.Taken together,our results suggest that 44 novel salt stress-responsive microRNAs were identified,and 4 of them might play important roles in D.salina upon salinity stress and contribute to clarify its distinctive halophilic feature.Our study will shed light on the regulatory mechanisms of salt stress responses.展开更多
Understanding the relative impact of nutrients and related environmental variables on phytoplankton biomass changes in urban rivers is important for river management.In this study,we explored the long-term dynamic cha...Understanding the relative impact of nutrients and related environmental variables on phytoplankton biomass changes in urban rivers is important for river management.In this study,we explored the long-term dynamic changes and driving factors of phytoplankton biomass in the process of urbanization from the perspective of time and space,and provided a scientific support to water ecological health assessment and management of urban rivers.From 2012 to 2021,the phytoplankton community composition in Taiyuan section of Fenhe River was found to be dominated by Cyanophyta,Chlorophyta,and Bacillariophyta.Among them,cyanobacteria were the main contributors to the total abundance,green algae ranked second,and diatoms were the least.The biomass of phytoplankton in different groups showed different decreasing trends.Based on 10 environmental factors to explain the changes of three main phytoplankton groups(cyanobacteria,green algae,diatoms),we found that chemical oxygen demand and water temperature had a high explanation rate for the abundance changes of the three main phytoplankton groups,which were important environmental factors affecting their biomass changes.The random forest model was used to analyze the changes in the total biomass of phytoplankton.It was found that the permanganate index had a higher contribution to the total biomass of phytoplankton in time.The contribution of air temperature to the total biomass of phytoplankton was higher in space.展开更多
Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morpho...Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morphological characterization and phylogenetic tree based on the rbcL gene confirmed its attribution to Heribaudiella fluviatilis. The complete organelle genomes of H. fluviatilis were determined and assembled from high-throughput sequencing. A circular tetrad structure of 128,880 bp was identified for the chloroplast, and the mitochondrial genome was assembled as a circle with 43,657 bp in length. This study provides the first and only record of organelle genomic information of the freshwater Phaeophyceae, which are important for understanding the endosymbiosis theories. Concatenated (Bayesian inference, maximum likelihood under MFP and GHOST models) and coalescent methods were used to construct the phylogenetic relationship among secondary plastid-bearing lineages based on organelle genomes. Obvious conflicts were observed in grouping relationships of chloroplast and mitochondrial genomes, even among different evolutionary models and tree-constructing methods. The transcriptome of H. fluviatilis was sequenced and used to construct the phylogenetic relationship among secondary plastid-bearing lineages. The phylogenetic relationships in nuclear and mitochondrial genomes were consistent in grouping CHSR taxa (cryptophytes, haptophytes, stramenopiles and rhizarians) in an independent branch. The phylogenetic relationship constructed from nuclear transcriptomes was highly reliable by owning robust supporting values on each node and was consistent with the serial endosymbiosis theory on evolution of red secondary plastid-derived lineages.展开更多
基金Supported by the National Natural Science Foundation of China(No.32170204)。
文摘This study presents a comprehensive phylogenetic analysis on Batrachospermaceae based on key taxonomic identifiers(rbcL,psaA,psbA,and COI-5P)from some genera.To systematically explore the phylogenetic relationships and taxonomy within Batrachospermaceae,we integrated molecular and morphological data,and explored the phylogeny,character evolution,and ancestral geographical origin and provided a theoretical support for the classification and geographic origination of Batrachospermaceae.Our findings reveal distinct relationships within the phylogenetic tree.Notably,10 genera(Sirodotia,Batrachospermum,Tuomeya,Volatus,Lympha,Nothocladus,Torularia,Sheathia,Nocturama,and Petrohua)are closely associated in the rbcL phylogenetic tree.Additionally,four genera(Kumanoa,Hoefkenia,Notohesperus,and Virescentia)exhibit high support ratios,indicating their close interrelations.Other genera,including Paludicola,Visia,Acarposporophycos,Macrosporophycos,Visioidea,Balliopsis,and Psilosiphon,exhibit clustering traits.Furthermore,the multigene sequences provide a robust support for Montagnia that forms a monophyletic group.Ancestral reconstruction of morphological characters identifies nine primitive character states,including whorl,fascicle length,cortical cells,secondary fascicles,the shape of carpogonical branch,spermatangia,carposporophyte,carpogonium and trichogyne,with Visia likely representing ancestral traits in Batrachospermaceae.Furthermore,geographical origin maps suggest a potential common ancestral of Batrachospermaceae origin in the American continent.Additional to conventional analyses,including evolutionary and ancestral reconstruction investigations into key morphological characters,we attempt to reconstruct the biogeography within the Batrachospermaceae,thus contributing to a nuanced understanding of its origin.
基金Supported by the National Natural Science Foundation of China(No.31970217)the Scientific and Technological Innovation Programs of Higher Education Institution in Shanxi(No.2019L0070)。
文摘Stephanodiscaceae is one of the most diverse family of the freshwater centric diatoms.However,the scarcity of whole plastome data poses a significant challenge to the undertaking of genomic studies on this taxonomic group.We collected data on the plastid genomes from 33 members of the Stephanodiscaceae and its close relatives,including 12 newly-sequenced genomes and 21 deposited in National Center for Biotechnology Information(NCBI).Phylogenetic trees are yielded five major clades based on homologous genes.The features of the plastid genomes,including repeat sequences,codon usage,and selection pressure for each clade,are analyzed.The paper makes a contribution to the field of diatom genomics by describing the structural characteristics of the plastid genomes in the Stephanodiscaceae and its closely related species,complemented by related analyses.It provides crucial data that will serve as indispensable references for future research.
基金Supported by the National Natural Science Foundation of China (No.41871037 to Shulian XIE and No.31800172 to Fangru NAN)the Fund for Shanxi"1331 Project"
文摘Species of the red algal order Acrochaetiales mostly inhabit marine environments,with only two freshwater taxa Audouinella and Ottia.A new genus and species are described for freshwater red alga Pauciramus yunnanensis from Ailao Mountain,Yunnan,China.It is closely related to Ottia and a new order Ottiales was proposed for these genera.Pauciramus has unique combination of morphological characteristics including the following:plants caespitose and densely pulvinate,slender uniseriate filaments with well-developed rhizoids,rarely branched,cylindrical vegetative cell with a single,ribbon-shaped and parietal chloroplast,reproduction by tetrasporangia,and dense sporangial branchlet only at the upper portion of filaments.Phylogenetic analysis of sequence data from the plastid ribulose-1,5-bisphosphate carboxylase-oxygenase large-subunit(rbc L),small subunit gene of the ribosomal cistron(SSU)and barcode region near the 5′end of the mitochondrial cytochrome oxidase subunit I(COI-5P)indicated that:the new taxon,P.yunnanensis,was in a well-supported clade with Ottia meiospora,and this clade was sister to order Palmariales and Acrochaetiales.To adhere to the principle of monophyly,a new freshwater order Ottiales including Ottia and Pauciramus is proposed.Despite the high sequence interspecific divergences and obvious morphological differences between genera Ottia and Pauciramus,seems impractical to establish a new family for a monospecific genus.Therefore,we temporarily classified Pauciramus into the family Ottiaceae,and made necessary revisions to the description to accommodate this genus.
基金Supported by the National Natural Science Foundation of China(No.31970217)the One-hundred Talent Program of Shanxi Province and the Key Research and the Development(R&D)Projects of Shanxi Province(No.201903D421038)。
文摘We report on eight species of the freshwater diatom genus Gomphonema from aquatic habitats from the Yuntai Mountains of Henan Province,China.This work represents the first detailed descriptions of the freshwater diatoms from this centrally-located province in China.Of the eight taxa considered,five are new to science and another is given a"cf."designation.Four of the eight species are similar in morphological features to other,"classical"species,with external areolar occlusions forming C-shaped openings.Another species is astigmate,and has distinct siliceous papillae located marginally on the exterior of the valves;this morphology has not been recognized previously for the genus.Two of the species have internal areolar and stigma occlusions.The diversity of morphological types of species in Gomphonema may relate to the ecosystems,with more diverse ecosystems harboring greater diversity of these morphological groups of Gomphonema.
基金Supported by the National Natural Science Foundation of China(Nos.32370219,32270220,U22A20445)the Fundamental Research Program of Shanxi Province(No.202303021221082)+2 种基金the Open Project Program of Xinghuacun College of Shanxi University(Shanxi Institute of Brewing Technology and Industry)(No.XCSXU-KF-202320)the Yuncheng Salt Lake Protection and Utilization Research Institute of Shanxi,China(No.YHYJ-2023003)the Program for Young Scholar Talents of Wenying in Shanxi University。
文摘The genus Selenastrum comprises common coccoid green algae found in diverse habitats worldwide.This genus has a complex taxonomic history,but recent applications of molecular phylogenetic methods have removed some members with similar morphologies from Selenastrum and established new genera.However,due to the lack of available molecular sequences and isolates,the species diversity of the genus has not been fully explored.We conducted a detailed examination of the taxonomy of genus Selenastrum based on 11 new strains collected from China.The multi-disciplinary study utilized morphology,ultrastructure,and phylogeny based on multiple molecular markers,and ITS-2 secondary structure.All the included strains of genus Selenastrum were clustered into two distinct clades.The members of one clade were similar morphologically to the type species Selenastrum bibraianum,whereas the strains of the other clade had distinctly different colony structures.Based on the latter clade’s larger colony cell numbers and independent phylogenetic position,we proposed that it as a new species of the genus Selenastrum,namely Selenastrum densum sp.nov.Additional taxa sampling and molecular data will help to discover additional new species and clarify the validity of morphological taxonomic characteristics within the genus Selenastrum.
基金Supported by the National Natural Science Foundation of China(No.31670208)the Applied Basic Research Programs of Shanxi Province of China(No.201801D221242)+1 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi of China(No.2019L0041)the Shanxi“Project 1331”.
文摘Salt stress is an abiotic stress to plants in especially saline lakes.Dunaliella,a halophilic microalga distributed throughout salt lakes and seas,can respond to different salinity stresses by regulating the expression of some genes.However,these genes and their function and biological processes involved remain unclear.Profi ling these salt-stress-related genes in a high-salt-tolerant Dunaliella species will help clarify the salt tolerance machinery of Dunaliella.Three D.salina_YC salt-stress groups were tested under low(0.51 mol/L),moderate(1.03 mol/L),and high(3.42 mol/L)NaCl concentrations and one control group under very low(0.05 mol/L)NaCl concentration and 3 transcriptome results that were deep sequenced and de novo assembled were obtained per group.Twelve high-quality RNA-seq libraries with 46585 upregulated and 47805 downregulated unigenes were found.Relative to the control,188 common differentially expressed genes(DEGs)were screened and divided into four clusters in expression pattern.Fifteen of them annotated in the significant enriched Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)were validated via qPCR.Their qPCR-based relative expression patterns were similar to their RNA-seq-based patterns.Two significant DEGs,the geranylgeranyl diphosphate synthase coding gene(1876-bp cDNA)and diacylglycerol O-acyltransferase coding gene(2968-bp cDNA),were cloned and analyzed in silico.The total lipid content,superoxide dismutase specific activity,and betacarotene content of D.salina_YC increased gradually with increasing salinity.In addition,the expression of 11 validated genes involved in fatty acid biosynthesis/degradation,active oxygen or carotenoid metabolisms showed significant changes.In addition,algal photochemical efficiency was diminished with increasing salinity,as well as the expression of 4 photosynthesis-related genes.These results could help clarify the molecular mechanisms underlying D.salina responses to the Yuncheng Salt Lake environment and lay a foundation for further utilization of this algal resource.
基金Supported by the National Natural Science Foundation of China(No.31770223)the Excellent Achievement Cultivation Project of Higher Education in Shanxi(No.2020KJ029)the Scientifi c and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0778)。
文摘Microorganisms play a key role in aquatic ecosystems.Recent studies show that keystone taxa in microbial community could change the community structure and function.However,most previous studies focus on abundant taxa but neglected low abundant ones.To clarify the seasonal variation of bacterial and microalgal communities and understand their synergistic adaptation to diff erent environmental factors,we studied the bacterial and eukaryotic phytoplankton communities in Fenhe River that runs through Taiyuan City,central China,and their seasonal co-occurrence patterns using 16S and 18S rDNA sequencing.Results indicate that positive interaction of eukaryotic phytoplankton network was more active than negative one except winter,indicating that the cooperation(symbiotic phenomenon in which phytoplankton are interdependent and mutually benefi cial)among them could improve the adaption of microbial community to the local environmental changes and maintain the stability of microbial network.The main genera that identifi ed as keystone taxa in bacterial network were Salinivibrio and Sphingopyxis of Proteobacteria and they could respond to the variation of nitrite and make use of it,while those that identifi ed as keystone taxa in eukaryotic phytoplankton network were Pseudoschroederia and Nannochloris,and they were more susceptible to nitrate and phosphate.Mychonastes and Cryptomonas were closely related to water temperature.However,the loss of the co-occurrence by environmental factor changes aff ected the stability of network structure.This study provided a reference for analyzing relationship between bacteria and eukaryotic phytoplankton and revealing potential importance of keystone taxa in similar ecological domains in carbon,nitrogen,and phosphorus dynamics.
基金Supported by the National Natural Science Foundation of China(Nos.32170204,41871037 to Shulian XIE and No.31800172 to Fangru NAN)。
文摘Batrachospermaceae is an important group of freshwater red algae.Available data of the latitude,longitude,and environmental factors on Batrachospermaceae distribution in Asia were analyzed to understand the geographical distribution of Batrachospermaceae genera in Asia.Statistical analyses,including one-way ANOVA,correlation analysis,stepwise regression analysis,principal component analysis,and linear discriminant analysis were conducted to characterize variation in geographical distribution and growth environment.Results reveal high variation in geographical distribution and growth environment among different Batrachospermaceae genera in Asia.Specifically,correlations between latitude and all environmental factors exclusive of altitude are significant,and longitude is significantly correlated with all environmental factors except for average relative humidity.The geographical distribution and growth environment of different Batrachospermaceae genera significantly differed.Altitude,maximum temperature,average temperature,minimum temperature,average relative humidity,average wind speed,maximum wind speed,and atmospheric pressure all contributed to explaining differences in the geographical distribution of Batrachospermaceae genera.Combining the results of correlation analysis,stepwise regression analysis,and principal component analysis,all environmental factors contributed to the different geographical distribution of Batrachospermum,Paludicola,Sheathia,Sirodotia,and Remainder(the rest),all environmental factors but atmospheric pressure contributed to the different geographical distribution of Kumanoa,and all environmental factors but average wind speed and maximum wind speed contributed to the different geographical distribution of Virescentia.However,the correlation between these significantly related environmental factors and taxa is not necessarily causative,and many other environmental factors,such as temperature,pH,conductivity,shading,current velocity,dissolved oxygen,hardness,substrata types,and nutrients etc.,are likely to have an important impact on the geographical distribution of taxa,which is an important topic for future research.
基金Supported by the National Natural Science Foundation of China(Nos.31670208 and 41871037 to Shulian XIE and 31800172 to Fangru NAN)the Applied Basic Research Project of Shanxi,China(No.201801D221245)+1 种基金the Scientifi c and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0078)the Fund for Shanxi“1331 Project”Key Innovative Research Team。
文摘The most prominent biological characteristic of Porphyridium purpureum is their unique extracellular sulfated polysaccharides that plays an important protective role against salt stress.Adaptation to stress is associated with metabolic adjustments.However,the molecular mechanisms underlying such metabolic changes remain elusive.This study presents the fi rst transcriptome profi ling of P.purpureum.A total of 8019 assembled transcripts were identifi ed,annotated,and classifi ed into diff erent biological categories and pathways based on a BLAST analysis against various databases.The in-depth analysis revealed that many of the diff erentially expressed genes in P.purpureum under salinities of 68 and 0 involved polysaccharide metabolism.A comparison of the gene expression levels under diff erent salinities revealed that the polysaccharide synthetic pathway was signifi cantly upregulated under the 68 salinity condition.The increased expression of the FBP,pfkA,CS,pgm,USP,UGP2,galE,and MPI transcripts in the polysaccharide synthetic pathway and the increase in ATP2 and ATP6 transcripts in the energy metabolic pathway revealed the molecular mechanism of high-salt adaptation.This sequencing dataset and analysis could serve as a valuable resource to study the mechanisms involved in abiotic stress tolerance in Rhodophyta.
基金Supported by the National Natural Science Foundation of China(No.31770223)the Excellent Achievement Cultivation Project of Higher Education in Shanxi(No.2020KJ029)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0778)。
文摘Phytoplankton are not only the main bearer of the nitrogen cycle,but also a key link driving nitrogen cycle.However,most phytoplankton cannot directly use N_(2),and they must uptake nitrogenous nutrients(ammonium,nitrate,and urea)to meet their photosynthesis needs.We examined the uptake characteristics of several nitrogenous substrates using stable isotope technique and identifi ed the potential nitrogen transformations in the Fenhe River.Results revealed that spring phytoplankton community composed of mainly Fragilaria,Ulothrix,Microcystis,and Synedra.Urea can meet the spring partial nitrogen requirement of phytoplankton.The large uptake rate of urea depended on urease,chlorophyll a,and nitrate concentrations as shown in random forest models.Cyanobacteria explained more than 42.8%of the total abundance at all sites in summer.Upstream was dominated by Actinastrum,and Chlorella was relevant in the downstream section.The uptake rates of ammonium were higher than those of nitrate and urea.In addition,the random forest model demonstrated that ammonium,urease,and dissolved oxygen(DO)were the major contributors to the ammonium uptake rates.Ammonium was taken up preferentially in autumn and phytoplankton(Cyclotella,Chlorella,and Pseudanabaena)appeared to be able to respond to changes in nitrogen forms by adjusting their community composition.Structural equation models demonstrated that temperature-induced changes in DO directly affected the transformations of different forms of nitrogen.At the same time,dissolved organic carbon can directly act on nutrients and then indirectly affect enzyme activity.There were great diff erences in the positive and negative effects of different paths in the process of nitrate reduction to nitrite and then reduction to ammonium in time and space.These findings provide a better understanding of the underlying mechanism of nitrogen uptake and the influences of interaction between environmental variables on nitrogen transformations in urban river ecosystems.
基金Supported by the National Natural Science Foundation of China(Nos.31670208,41871037,31800172)the Fund for Shanxi“1331 Project”。
文摘The genus Sheathia consists of over 20 species primarily distributed in Asia,Europe,Oceania,North America,and Africa.However,the origin and evolution of this genus remain unclear.Two gametophyte stage specimens(SAS18052 and SAS18523)and two“Chantransia”stage specimens(YTS19161 and YTS19017)were collected from Shanxi and Henan Provinces in China,respectively.Based on morphological data,isolates YTS19161 and YTS19017 were similar to Audouinella pygmaea,whereas the morphological characteristics of SAS18052 and SAS18523 were in good agreement with the circumscription description of S.longipedicellata.Molecular sequences of rbc L,COI-5P,and psb A were used to investigate the phylogenetic,evolutionary,and biogeographic origin of the genus Sheathia.The three molecular markers supported that the two gametophyte stage specimens belong to S.longipedicellata,while the isolates YTS19161 and YTS19017 were the“Chantransia”of S.longipedicellata.Ancestral area reconstruction and divergence time estimation speculated that Sheathia originated in North America,a portion of the Pangaea at approximately 328.07-184.73 million years ago(Ma).Our relaxed molecular clock analysis suggests that the Florideophyceae diverged approximately 741.04(894.36-631.70)Ma.The major divergences in this class involved the emergence of Nemaliophycidae[ca.662.01(779.83-580.51)Ma],and the split of orders Batrachospermales and Thoreales[ca.456.10(552.80-367.88)Ma].
基金Supported by the National Natural Science Foundation of China(Nos.31670208,41871037 to Shulian XIE,and No.31800172 to Fangru NAN)the Fund for Shanxi“1331 Project”Key Innovative Research Team。
文摘Twelve putative"Chantransia"isolates were collected from six locations across Hubei,Shanxi,Guizhou,and Henan Provinces in China.Their morphological characters were evaluated via the Ward’s method of hierarchical cluster analysis in SPSS software to classify phylogenetic relationships among the isolates.The morphological data revealed that isolate HN31(called group"MALL")was distinct from the other specimens being macroscopic with large vegetative cells and monosporangia(>20μm in diameter).The 11 other isolates were grouped into three clusters,corresponding to the species Audouinella tenella,A.hermannii,and A.pygmaea.The morphological"Chantransia"stage of the species,reportedly belonging to the orders Batrachospermales,Thoreales,and the phylogenetically distant genus Audouinella,are very similar,resulting in the di fficulty to distinguish them based just on morphology.Therefore,molecular analysis of rbc L,UPA,and COI-5 P was conducted to infer the phylogenetic position of all isolates in this study.All"A.tenella"and"A.hermannii"sequences belong to order Batrachospermales,while the isolate HN31 was the"Chantransia"of Thorea hispida.The six other specimens varied morphologically,but they were within the circumscription of"A.pygmaea".All three molecular markers show that all"pygmaea"isolates also represent the"Chantransia"of T.hispida.Furthermore,results from this investigation proposed a new species—Sheathia qinyuanensis,corresponding to the isolates QY1 and QY2.
基金Supported by the National Natural Science Foundation of China(No.31970217)the Scientific and Technological Innovation Programs of Higher Education Institution in Shanxi(No.2019L0070)。
文摘We describe a new species of Discostella from Guiyang based on light and scanning electron microscopic observations,as well as molecular analysis.This species is morphologically distinguished from other species by a relatively smooth and slightly recessed central area with marginal striae of unequal lengths forked near the margin.Marginal fultoportulae and a single rimoportula are situated between every two costae or on the costae.Both morphological characters and the concatenated data of rbc L and SSU rDNA indicate that Discostella guiyangensis is a unique and new species.According to divergence time estimation analysis,Discostella guiyangensis is the oldest species among the Discostella species sequenced currently.In addition,we complement molecular data of Discostella asterocostata and Discostella stelligera.
基金Supported by the National Natural Science Foundation of China(Nos.32370219,31900187,32000167)the Shanxi Province Science Foundation for Youths(Nos.201901D211132,201901D211421)+4 种基金the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(Nos.2019L0073,2020L0524)the Key Laboratory of Algal BiologyInstitute of HydrobiologyChinese Academy of Sciences(No.2018-002)the Shanxi“1331 Project”。
文摘Makinoella Okada is a genus of coccoid green algae belonging to the family Oocystaceae with typical morphological characteristics.Reports to date included only one type species.Since the genus is rarely reported,there is a lack of taxonomic research.In this study,17 strains of this genus were collected from several different places in China,and their taxonomic studies were conducted based on morphological and molecular phylogenetic analysis.The phylogenetic results based on the analysis of ITS,chloroplast genes rbc L and tuf A showed that the genus was divided into two branches.One of the branches comprised newly collected algae.Compensatory base changes(CBCs)and hemi-compensatory base changes(hemi-CBCs)within the secondary structure of the ITS-2 confirmed the branches as two species.Compared with the type species of Makinoella tosaensis,the cell size of this new branch was only about 50%,and included 2-4 colonial cells.Therefore,based on the smaller cell size,simpler colony composition,independent phylogenetic position and CBCs and hemi-CBCs,we suggest that the new clade should be designated as a new taxon of Makinoella,namely Makinoella parva.Among the four molecular markers using in this study,the rbc L and newly introduced ITS are recommended for species separation,which can help further studies to revise the species and generic concepts of the family.
基金Supported by the National Natural Science Foundation of China(Nos.31670208,41871037,31800172)the Fund for Shanxi“1331 Project”。
文摘Virescentia guangxiensis,a new species of Virescentia from Guangxi,South China,is described and illustrated based on morphological observations and phylogenetic analysis.This species was distinguished morphologically from other species by the presence of special expansion cells with a variable shape,obovoid,spherical,pear-shaped,located in the penultimate cells of primary or secondary fascicles,rarely terminal on primary fascicles,as well as by small whorls(250-350-μm wide)and short primary fascicles(5-7 cell stories).Phylogenetic analysis of molecular data from the rbc L and COI-5P loci supported the separation of the proposed new species from other species in the genus Virescentia.This is the first species of the order Batrachospermales reported in Guangxi and the second species of the genus Virescentia reported in China.This study expands the known species diversity and geographical distribution of freshwater Rhodophyta in China.
基金Supported by the National Natural Science Foundation of China(Nos.32270220,U22A20445 to Jia FENG)the Excellent Achievement Cultivation Project of Higher Education in Shanxi(No.2020KJ029)。
文摘The newly described chrysophyte,Mallomonas vietnamica,is reported for the first time in China from specimens collected in Guizhou Province,SW China.The morphological characteristics were studied using light and scanning electron microscopy.The species was described based on morphological characteristics,including cell size,scale size,dome,V-rib,and bristles.Subsequently,molecular sequencing of M.vietnamica was conducted and a phylogenetic tree was constructed based on concatenated SSU,LSU,and rbc L sequences.The phylogenetic tree led us to suggest raising a new section named Uncatusipedae for this species.This study provides new molecular data from the genus Mallomonas and enriches our understanding of the species diversity and geographical distribution of the genus Mallomonas in China.
基金Supported by the National Natural Science Foundation of China(No.31800172 to F.R.NAN,No.32170204 to S.L.XIE)。
文摘Hildenbrandia is an early diverged lineage in Florideophyceae,Rhodophyta.The species diversity of this genus is still unresolved due to the simple morphology and limited molecular information.The mitochondrial genome of freshwater H.jigongshanensis was determined in this study.The freshwater H.jigongshanensis had a larger mitochondrial genome than the marine H.rubra and GC content was higher.Collinear alignment structure was observed between the mitochondrial genomes of H.jigongshanensis and H.rubra,except for one block that was encoded on the complement strand.More introns were found in mitochondrial genome of H.jigongshanensis than in H.rubra,and H.jigongshanensis shares the common feature with Bangiophyceae that two introns were distributed in cox1.Comparison of mitochondrial genome organization suggests that H.jigongshanensis preserves characters that could be hypothetically more similar to the ancestor of Bangiophyceae and Florideophyceae,which differ with previous studies based on chloroplast,and nuclear markers.More mitochondrial genomes and phylogenetic analyses combing nuclear,chloroplast and mitochondrial genomes are needed to clarify this discrepancy.Mitochondrion-based phylogeny in this study resulted in better solution at both the deep and recent derived nodes than single-gene phylogenies.Most protein-coding genes between H.jigongshanensis and H.rubra were identical except atp8,which was present in H.jigongshanensis while absent from H.rubra.This finding follows the trend that high Ka/Ks ratio genes are more frequently lost than low Ka/Ks ratio ones in red algae.
基金Supported by the National Natural Science Foundation of China(No.32170204)Science and Technology Strategy Research Special Project of Shanxi Province of China(No.202204031401051)+2 种基金the Basic Research Programs of Shanxi Province of China(No.202103021224009)the Teaching Reform and Innovation Project of Colleges and Universities in Shanxi of China(No.J20220046)the Shanxi“1331 Project”.
文摘Dunaliella salina is a classic halophilic alga.However,its molecular mechanisms in response to high salinity at the post transcriptional level remain unknown.A unique halophilic alga strain,DS-CN1,was screened from four D.salina strains via cell biological,physiological,and biochemical methods.High-throughput sequencing of small RNAs(sRNAs)of DS-CN1 in culture medium containing 3.42-mol/L NaCl(SS group)or 0.05-mol/L NaCl(CO group)was performed on the BGISEQ-500 platform.The annotation and sequences of D.salina sRNAs were profiled.Altogether,44 novel salt stress-responsive microRNAs(miRNAs)with a relatively high C content,with the majority of them being 24 nt in length,were identified and characterized in DS-CN1.Twenty-one differentially expressed miRNAs(DEMs)in SS and CO were screened via bioinformatic analysis.A total of 319 putative salt stress-related genes targeted(104 overlapping genes)by novel miRNAs in this alga were screened based on our previous transcriptome sequencing research.Furthermore,these target genes were classified and enriched by GO and KEGG pathway analysis.Moreover,5 novel DEMs(dsa-mir3,dsa-mir16,dsa-mir17,and dsa-mir26 were significantly upregulated,and dsa-mir40 was significantly downregulated)and their corresponding 10 target genes involved in the 6 significantly enriched metabolic pathways were verified by quantitative real-time PCR.Next,their regulatory relationships were comprehensively analyzed.Lastly,a unique salt stress response metabolic network was constructed based on the novel DEM-target gene pairs.Taken together,our results suggest that 44 novel salt stress-responsive microRNAs were identified,and 4 of them might play important roles in D.salina upon salinity stress and contribute to clarify its distinctive halophilic feature.Our study will shed light on the regulatory mechanisms of salt stress responses.
基金Supported by the National Natural Science Foundation of China(Nos.32270220,U22A20445 to Jia FENG)the Excellent Achievement Cultivation Project of Higher Education in Shanxi(No.2020KJ029)the Natural Science Foundation of Shanxi Province(No.202203021211313)。
文摘Understanding the relative impact of nutrients and related environmental variables on phytoplankton biomass changes in urban rivers is important for river management.In this study,we explored the long-term dynamic changes and driving factors of phytoplankton biomass in the process of urbanization from the perspective of time and space,and provided a scientific support to water ecological health assessment and management of urban rivers.From 2012 to 2021,the phytoplankton community composition in Taiyuan section of Fenhe River was found to be dominated by Cyanophyta,Chlorophyta,and Bacillariophyta.Among them,cyanobacteria were the main contributors to the total abundance,green algae ranked second,and diatoms were the least.The biomass of phytoplankton in different groups showed different decreasing trends.Based on 10 environmental factors to explain the changes of three main phytoplankton groups(cyanobacteria,green algae,diatoms),we found that chemical oxygen demand and water temperature had a high explanation rate for the abundance changes of the three main phytoplankton groups,which were important environmental factors affecting their biomass changes.The random forest model was used to analyze the changes in the total biomass of phytoplankton.It was found that the permanganate index had a higher contribution to the total biomass of phytoplankton in time.The contribution of air temperature to the total biomass of phytoplankton was higher in space.
基金funded by the National Natural Science Foundation of China(No.31800172 to F.R.Nan,No.32170204 to S.L.Xie,No.32270220 and U22A20445 to J.Feng)the Excellent Achievement Cultivation Project of Higher education in Shanxi(No.2020KJ029).
文摘Freshwater brown algae have been acknowledged as the least diverse of all groups of freshwater algae. Morphological and molecular investigation were conducted on a freshwater brown alga collected in this study. Morphological characterization and phylogenetic tree based on the rbcL gene confirmed its attribution to Heribaudiella fluviatilis. The complete organelle genomes of H. fluviatilis were determined and assembled from high-throughput sequencing. A circular tetrad structure of 128,880 bp was identified for the chloroplast, and the mitochondrial genome was assembled as a circle with 43,657 bp in length. This study provides the first and only record of organelle genomic information of the freshwater Phaeophyceae, which are important for understanding the endosymbiosis theories. Concatenated (Bayesian inference, maximum likelihood under MFP and GHOST models) and coalescent methods were used to construct the phylogenetic relationship among secondary plastid-bearing lineages based on organelle genomes. Obvious conflicts were observed in grouping relationships of chloroplast and mitochondrial genomes, even among different evolutionary models and tree-constructing methods. The transcriptome of H. fluviatilis was sequenced and used to construct the phylogenetic relationship among secondary plastid-bearing lineages. The phylogenetic relationships in nuclear and mitochondrial genomes were consistent in grouping CHSR taxa (cryptophytes, haptophytes, stramenopiles and rhizarians) in an independent branch. The phylogenetic relationship constructed from nuclear transcriptomes was highly reliable by owning robust supporting values on each node and was consistent with the serial endosymbiosis theory on evolution of red secondary plastid-derived lineages.
