The genus Salix is a common component of the Northern Hemisphere dendroflora with important ecological and economic value.However,taxonomy and systematics of Salix is extremely difficult and relationships between main...The genus Salix is a common component of the Northern Hemisphere dendroflora with important ecological and economic value.However,taxonomy and systematics of Salix is extremely difficult and relationships between main lineages,especially deep phylogenies,remain largely unresolved.In this study,we used genome-skimming,plastome assembly,and single-copy orthologs(SCOs)from 66 Salix accessions,along with publicly available plastome and sequence read archive(SRA)datasets to obtain a robust backbone phylogeny of Salix,clarify relationships between its main lineages,and gain a more precise understanding of the origin and diversification of this species-rich genus.The plastome and SCO datasets resolved Salix into two robust clades,with plastome-based phylogenies lacking inner resolution and SCO offering fully resolved phylogenies.Our results support the classification of Salix into five subgenera:Salix,Urbaniana,Triandrae,Longifoliae and Vetrix.We observed a significant acceleration in the diversification rate within the Chamaetia-Vetrix clade,while Salix exhibited increased rates of diversification spanning from the early Oligocene to the late Miocene.These changes coincided with contemporaneous tectonic and climate change events.Our results provide a foundation for future systematic and evolutionary studies of Salix.Additionally,we showed that genome skimming data is an efficient,rapid,and reliable approach for obtaining extensive genomic data for phylogenomic studies,enabling the comprehensive elucidation of Salix relationships.展开更多
Deep genome skimming(DGS)has emerged as a promising approach to recover orthologous nuclear genes for large-scale phylogenomic analyses.However,its reliability with low DNA quality and quantity typical of archival spe...Deep genome skimming(DGS)has emerged as a promising approach to recover orthologous nuclear genes for large-scale phylogenomic analyses.However,its reliability with low DNA quality and quantity typical of archival specimens,such as herbarium material,remains largely unexplored.We used Rhododendron as a case study to evaluate best practices for DGS in phylogenetic analyses at both deep and shallow scales.We first investigated locus recovery variation with sequencing depth,before evaluating the phylogenetic utility of different sets of loci,including Angiosperms353,target nuclear exons,and extended exon-flanking regions.We found DGS effectively recovered nuclear genes from herbarium specimens,with~15coverage performing similarly to deeper sequencing.The recovery of target exon and flanking regions was improved by using supercontigs as a reference,offering a potential solution to limited sequencing depth.The high-integrity nuclear sequences recovered robust phylogenetic relationships within Rhododendron.Notably,exon-flanking regions showed significant potential for resolving relationships at shallow scales.Genes recovered with taxon-specific references had less missing data than those recovered by Angiosperms353 and generated higher-resolution phylogenetic trees.This study demonstrates the utility of DGS data for obtaining numerous nuclear genes from herbarium specimens for phylogenetic studies,and makes recommendations for best practices regarding sequencing coverage,locus selection,and bioinformatic approaches.展开更多
This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teache...This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teacher's consideration when designing and preparing reading materials.展开更多
The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets o...The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics： genome skimming, transcriptome sequencing （RNA- seq）, restriction site associated DNA sequencing （RAD-Seq）, and targeted capture （Hyb-seq）. Of these four genome-partitioning approaches, targeted capture （especially Hyb-seq） shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.展开更多
Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bam...Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bamboo genus Shibataea,we performed genome-scale phylogenetic analysis of all seven species and one variety of the genus using double digest restriction-site associated DNA sequencing(dd RAD-seq)and whole plastid genomes generated using genome skimming.Our phylogenomic analyses based on dd RAD-seq and plastome data congruently recovered Shibataea as monophyletic.The nuclear data resolved S.hispida as the earliest diverged species,followed by S.chinensis,while the rest of Shibataea can be further divided into two clades.However,the plastid and nuclear topologies conflict significantly.By comparing the results of network analysis and topologies reconstructed from different datasets,we identify S.kumasasa as the most admixed species,which may be caused by incomplete lineage sorting(ILS)or interspecific gene flow with four sympatric species.This study highlights the power of dd RAD and plastome data in resolving complex relationships in the intractable bamboo genus.展开更多
A FAST (fluorescence of advanced Maillard products and Soluble Tryptophan) method for identification of recon- stituted milk made from skim milk powder in the fresh milk was developed. Considering milk and skim milk p...A FAST (fluorescence of advanced Maillard products and Soluble Tryptophan) method for identification of recon- stituted milk made from skim milk powder in the fresh milk was developed. Considering milk and skim milk powders variations from different seasons and countries, milk was collected from different dairy farms in different seasons and skim milk powders were collected from different countries to measure the Tryptophan (Trp), advanced Maillard products (AMP) fluorescence values. The results showed that there were differences (P<0.01) between raw and reconstituted milk. The plot of values in each mixed level of raw and reconstituted milk had a correlation coefficient >0.97. The FAST method is a simple, rapid, low-cost and sensitive method enabling the detection of 5% reconstituted milk in fresh milk. The measurement of the Trp, AMP fluorescence values and calculation of the FAST index is a suitable method for large-scale monitoring of fresh milk samples.展开更多
Based on the effects of skim components on ammonium removal as well as the current processing technology, a new process-intensified technology of removing ammonia from skim by air stripping on rotating packed bed was ...Based on the effects of skim components on ammonium removal as well as the current processing technology, a new process-intensified technology of removing ammonia from skim by air stripping on rotating packed bed was proposed. The experiments were conducted on a wave-thread packed Rotating Packed Bed(RPB) under atmospheric pressure, suggesting that, in terms of order of importance, the ammonium concentration of feed-stock(x_w), the average ultra-gravity factor(β), feed-stock flux(L), and gas flux(G) had significant impact on ammonium removal rate(η) and the ammonium concentration of products(x_D). In the experiment, mass-transfer coefficient in gas phase(k_ya_e) increases with the increase of β, G/L, and L. The ammonium concentration of products decreases with the increase of β, G/L and the increase of L. The ammonium concentration of products would be as low as ~0.10% and the ammonia removal rate would be 63.21% when skim temperature was 25 °C, x_w0.28%, β 133.2, and G/L 15.0 m^3·L^(-1). Experiment results indicated that the proposed technology for removing ammonium from skim on a rotating packed bed would be a new process-intensified technique compared with traditional aeration process and centrifugal atomization method.展开更多
In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron fr...In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS,meanwhile to apply the remaining slag tailings as cement admixture.From this process,three iron-rich products were recovered in stages by clean gravity-magnetic separation,slag tailings were left.Slag powder was prepared by ultrafine grinding of slag tailings.The stability,setting time and cement mortar strength of the slag tailings cements(STC)which were mixed with Portland cement and slag powder were studied respectively.The results showed that a proper overall performance still could be obtained at the slag powder content of 30%.Chemical composition analysis,X-ray diffraction(XRD)analysis,metallographic microscope and scanning electron microscope(SEM)analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process.The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate(C_(2)S)and tricalcium silicate(C_(3)S)in the slag tailings make the addition of slag powder into the Portland cement feasible.展开更多
[Objective] The aim of this study was to investigate the decolorization ef- fects of activated carbon and macroporous resin on Periplaneta americana L. skimmed cream and compare the advantages and disadvantages of the...[Objective] The aim of this study was to investigate the decolorization ef- fects of activated carbon and macroporous resin on Periplaneta americana L. skimmed cream and compare the advantages and disadvantages of the two decolorization technologies. [Method] Periplaneta americana L. skimmed cream was decolored with activated carbon and macroporous resin, and freeze-dried to collect solid decolorization products. By investigating the yield, decolorization rate, protein retention rate and decolorization operation process, the advantages and disadvantages of the two decolorization technologies were compared. [Result] Both activated carbon and macroporous resin can be used for decolorization. To be specific, macroporous resin-decolorization is superior in the yield and protein retention rate, while activated carbon-decolorization is superior in decolorization rate and decolorization operation process. [Conclusion] Macroporous resin-decolorization can be used if protein is the main ingredient required in the experiment, while activated carbon-decolorization can be used if protein is not the main ingredient required.展开更多
The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of th...The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of the larvae of Byasa daemonius,a vulnerable butterfly.In this study,15 pairs of polymorphic microsatellite primers of A.delavayi were designed and screened based on the Simple Sequence Repeats(SSR)loci found by using the results of genome skimming.Based on these 15 SSR markers,the genetic diversity and structure of 193 individuals from ten natural populations were analyzed in detail.In comparison to other endemic and endangered plants in the region,the population of A.delavayi possess a relatively high genetic diversity(He=0.550,I=1.112).AMOVA analysis showed that 68.4%of the total genetic diversity was within populations and 31.6%of the variation occurred among populations.There was a significant genetic differentiation among natural populations of A.delavayi detectable,with low gene flow(Nm=0.591).This might be attributed to geographical barriers and limited seed dispersal.To test the isolation by distance(IBD),we performed Mantel test,which showed a significant correlation between the geographic and genetic distances.In order to cope with the possible biases caused by IBD,we additionally performed Bayesian genetic cluster analyses and principal coordinate analysis(PCoA).The final cluster analysis revealed three groups with distinct geographical distribution.Habitat fragmentation and limited gene flow between these populations may be the main reasons for the current genetic structure.For conservation of this species,we suggest to divide its populations into three protection management units,with subsequent focus on the Yongsheng and Luquan populations which experienced a genetic bottleneck event in the past.展开更多
Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mam...Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mammals.Although previous studies have identified its phylogenetic position,interspecific relationships within Celtis remain unclear.In this study,we generated genome skimming data from five Celtis species to analyze phylogenetic relationships within the genus and develop genome resources.The plastomes of Celtis ranged in length from 158,989 bp to 159,082 bp,with a typical angiosperm quadripartite structure,and encoded a total of 132 genes with 20 duplicated in the IRs.Comparative analyses showed that plastome content and structure were relatively conserved.Whole plastomes showed no signs of gene loss,translocations,inversions,or genome rearrangement.Six plastid hotspot regions(trnH-psbA,psbA-trnK,trnG-trnR,psbC-trnS,cemA-petA and rps8-rpl14),4097 polymorphic nuclear SSRs,as well as 62 low or single-copy gene fragments were identified within Celtis.Moreover,the phylogenetic relationships based on the complete plastome sequences strongly endorse the placement of C.biondii as sister to the((((C.koraiensis,C.sinensis),C.tetrandra),C.julianae),C.cerasifera)clade.These findings and the genetic resources developed here will be conducive to further studies on the genus Celtis involving phylogeny,population genetics,and conservation biology.展开更多
How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering re...How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.展开更多
This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. ...This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.展开更多
基金supported by NSFC(32070226,32360065)the Key Projects of the Joint Fund of the National Natural Science Foundation of China(U23A20149)+3 种基金the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2024QZKK0200)Yunnan Fundamental Research Projects(202101AS070032)the CAS“Light ofWest China”Program(xbzg-zdsys-202110)the Yunnan Innovation Team Project(202305AS350004,with LD/NY/SB/CJG/CJH as the core member).
文摘The genus Salix is a common component of the Northern Hemisphere dendroflora with important ecological and economic value.However,taxonomy and systematics of Salix is extremely difficult and relationships between main lineages,especially deep phylogenies,remain largely unresolved.In this study,we used genome-skimming,plastome assembly,and single-copy orthologs(SCOs)from 66 Salix accessions,along with publicly available plastome and sequence read archive(SRA)datasets to obtain a robust backbone phylogeny of Salix,clarify relationships between its main lineages,and gain a more precise understanding of the origin and diversification of this species-rich genus.The plastome and SCO datasets resolved Salix into two robust clades,with plastome-based phylogenies lacking inner resolution and SCO offering fully resolved phylogenies.Our results support the classification of Salix into five subgenera:Salix,Urbaniana,Triandrae,Longifoliae and Vetrix.We observed a significant acceleration in the diversification rate within the Chamaetia-Vetrix clade,while Salix exhibited increased rates of diversification spanning from the early Oligocene to the late Miocene.These changes coincided with contemporaneous tectonic and climate change events.Our results provide a foundation for future systematic and evolutionary studies of Salix.Additionally,we showed that genome skimming data is an efficient,rapid,and reliable approach for obtaining extensive genomic data for phylogenomic studies,enabling the comprehensive elucidation of Salix relationships.
基金the National Key Research and Development Program of China(2023YFA0915800)the Science and Technology Basic Resources Investigation Program(2021FY100200)+3 种基金the Key Basic Research program of Yunnan Province,China(202101BC070003)the Large-scale Scientific Facilities of the Chinese Academy of Sciences(2017-LSFGBOWS-02)the Chinese Academy of Sciences President's International Fellowship Initiative(2025PD0021)We are grateful to curator of KUN to access the herbarium specimens,and Jiayun Zou,Zhirong Zhang,Jing Yang,Hongtao Li and Chunxia Zeng,for their help with sample collection,laboratory work and data analysis.Molecular experiments and data analysis were performed at the Laboratory of Molecular Biology and iFlora High-Performance Computing Center of Germplasm Bank of Wild Species,Kunming Institute of Botany,CAS.
文摘Deep genome skimming(DGS)has emerged as a promising approach to recover orthologous nuclear genes for large-scale phylogenomic analyses.However,its reliability with low DNA quality and quantity typical of archival specimens,such as herbarium material,remains largely unexplored.We used Rhododendron as a case study to evaluate best practices for DGS in phylogenetic analyses at both deep and shallow scales.We first investigated locus recovery variation with sequencing depth,before evaluating the phylogenetic utility of different sets of loci,including Angiosperms353,target nuclear exons,and extended exon-flanking regions.We found DGS effectively recovered nuclear genes from herbarium specimens,with~15coverage performing similarly to deeper sequencing.The recovery of target exon and flanking regions was improved by using supercontigs as a reference,offering a potential solution to limited sequencing depth.The high-integrity nuclear sequences recovered robust phylogenetic relationships within Rhododendron.Notably,exon-flanking regions showed significant potential for resolving relationships at shallow scales.Genes recovered with taxon-specific references had less missing data than those recovered by Angiosperms353 and generated higher-resolution phylogenetic trees.This study demonstrates the utility of DGS data for obtaining numerous nuclear genes from herbarium specimens for phylogenetic studies,and makes recommendations for best practices regarding sequencing coverage,locus selection,and bioinformatic approaches.
文摘This article intends to shed some light on effective use of three reading strategies: skimming,scanning and studying for non-English-speaking middle school students.The article also presents some advice for the teacher's consideration when designing and preparing reading materials.
基金supported by the Large-scale Scientific Facilities of the Chinese Academy of Sciences (Grant No: 2017-LSFGBOWS-01)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB31000000)the Program of Science and Technology Talents Training of Yunnan Province (2017HA014)
文摘The rapid expansion of next-generation sequencing （NGS） has generated a powerful array of approaches to address fundamental questions in biology. Several genome-partitioning strategies to sequence selected subsets of the genome have emerged in the fields of phylogenomics and evolutionary genomics. In this review, we summarize the applications, advantages and limitations of four NGS-based genome- partitioning approaches in plant phylogenomics： genome skimming, transcriptome sequencing （RNA- seq）, restriction site associated DNA sequencing （RAD-Seq）, and targeted capture （Hyb-seq）. Of these four genome-partitioning approaches, targeted capture （especially Hyb-seq） shows the greatest promise for plant phy^ogenetics over the next fex~ years. This reviex~ wi~ aid ~esea^chers in their selection of appropriate genome-partitioning approaches to address questions of evolutionary scale, where we anticipate continued development and expansion ofwhole-genome sequencing strategies in the fields of plant phylogenomics and evolutionary biology research.
基金supported by the National Natural Science Foundation of China (Grant No. 31470322 and 31430011)
文摘Shibataea is a genus of temperate bamboos(Poaceae:Bambusoideae)endemic to China,but little is known about its phylogenetic position and interspecific relationships.To elucidate the phylogenetic relationship of the bamboo genus Shibataea,we performed genome-scale phylogenetic analysis of all seven species and one variety of the genus using double digest restriction-site associated DNA sequencing(dd RAD-seq)and whole plastid genomes generated using genome skimming.Our phylogenomic analyses based on dd RAD-seq and plastome data congruently recovered Shibataea as monophyletic.The nuclear data resolved S.hispida as the earliest diverged species,followed by S.chinensis,while the rest of Shibataea can be further divided into two clades.However,the plastid and nuclear topologies conflict significantly.By comparing the results of network analysis and topologies reconstructed from different datasets,we identify S.kumasasa as the most admixed species,which may be caused by incomplete lineage sorting(ILS)or interspecific gene flow with four sympatric species.This study highlights the power of dd RAD and plastome data in resolving complex relationships in the intractable bamboo genus.
基金Project (No. 2002BA518A06) supported by the Hi-Tech Researchand Development Program (863) of China
文摘A FAST (fluorescence of advanced Maillard products and Soluble Tryptophan) method for identification of recon- stituted milk made from skim milk powder in the fresh milk was developed. Considering milk and skim milk powders variations from different seasons and countries, milk was collected from different dairy farms in different seasons and skim milk powders were collected from different countries to measure the Tryptophan (Trp), advanced Maillard products (AMP) fluorescence values. The results showed that there were differences (P<0.01) between raw and reconstituted milk. The plot of values in each mixed level of raw and reconstituted milk had a correlation coefficient >0.97. The FAST method is a simple, rapid, low-cost and sensitive method enabling the detection of 5% reconstituted milk in fresh milk. The measurement of the Trp, AMP fluorescence values and calculation of the FAST index is a suitable method for large-scale monitoring of fresh milk samples.
基金Supported by the Opening Project Fund of Key Laboratory of Danzhou Investigation&Experiment Station of Tropical Crops,Ministry of Agriculture(RRI-KLOF201701)
文摘Based on the effects of skim components on ammonium removal as well as the current processing technology, a new process-intensified technology of removing ammonia from skim by air stripping on rotating packed bed was proposed. The experiments were conducted on a wave-thread packed Rotating Packed Bed(RPB) under atmospheric pressure, suggesting that, in terms of order of importance, the ammonium concentration of feed-stock(x_w), the average ultra-gravity factor(β), feed-stock flux(L), and gas flux(G) had significant impact on ammonium removal rate(η) and the ammonium concentration of products(x_D). In the experiment, mass-transfer coefficient in gas phase(k_ya_e) increases with the increase of β, G/L, and L. The ammonium concentration of products decreases with the increase of β, G/L and the increase of L. The ammonium concentration of products would be as low as ~0.10% and the ammonia removal rate would be 63.21% when skim temperature was 25 °C, x_w0.28%, β 133.2, and G/L 15.0 m^3·L^(-1). Experiment results indicated that the proposed technology for removing ammonium from skim on a rotating packed bed would be a new process-intensified technique compared with traditional aeration process and centrifugal atomization method.
基金The authors gratefully acknowledge the National Key Research and Development Program of China(No.2018YFC1901902)the Liao Ning Revitalization Talents Program(No.XLYC1907162).
文摘In order to make the slag from desulphurization and slag skimming(SDSS)to be comprehensively recycled and utilized,a combined process of beneficiation and building materials preparation was proposed to recover iron from SDSS,meanwhile to apply the remaining slag tailings as cement admixture.From this process,three iron-rich products were recovered in stages by clean gravity-magnetic separation,slag tailings were left.Slag powder was prepared by ultrafine grinding of slag tailings.The stability,setting time and cement mortar strength of the slag tailings cements(STC)which were mixed with Portland cement and slag powder were studied respectively.The results showed that a proper overall performance still could be obtained at the slag powder content of 30%.Chemical composition analysis,X-ray diffraction(XRD)analysis,metallographic microscope and scanning electron microscope(SEM)analysis were employed to assess the characteristics of the SDSS and the products obtained from the whole process.The results indicated that the three iron-rich products could be used as a raw material for steelmaking and ironmaking and the relatively large amount of calcium silicate(C_(2)S)and tricalcium silicate(C_(3)S)in the slag tailings make the addition of slag powder into the Portland cement feasible.
基金Supported by National Natural Science Foundation of China(30560181)~~
文摘[Objective] The aim of this study was to investigate the decolorization ef- fects of activated carbon and macroporous resin on Periplaneta americana L. skimmed cream and compare the advantages and disadvantages of the two decolorization technologies. [Method] Periplaneta americana L. skimmed cream was decolored with activated carbon and macroporous resin, and freeze-dried to collect solid decolorization products. By investigating the yield, decolorization rate, protein retention rate and decolorization operation process, the advantages and disadvantages of the two decolorization technologies were compared. [Result] Both activated carbon and macroporous resin can be used for decolorization. To be specific, macroporous resin-decolorization is superior in the yield and protein retention rate, while activated carbon-decolorization is superior in decolorization rate and decolorization operation process. [Conclusion] Macroporous resin-decolorization can be used if protein is the main ingredient required in the experiment, while activated carbon-decolorization can be used if protein is not the main ingredient required.
基金Support for this study was provided by grants from the NSFC(National Natural Science Foundation of China)-Yunnan Joint fund to support key projects(No.U1602264)Yunnan Ten Thousand Talents Plan Young&Elite Talent Project to G.Chen(YNWR-QNBJ-2018-017)+2 种基金NSFC(National Natural Science Foundation of China)(No.31660057)Y.P.GengScience&Technology Basic Resources Investigation Program of China for Survey and Germplasm Conservation of PSESP in Southwest China(2017FY100100)to W.B.Sun.
文摘The traditional medicinal plant,and endangered species Aristolochia delavayi(Aristolochiaceae)is an endemic species in China and occurs in the warm and dry areas along the Jinsha river.It is also a specific host of the larvae of Byasa daemonius,a vulnerable butterfly.In this study,15 pairs of polymorphic microsatellite primers of A.delavayi were designed and screened based on the Simple Sequence Repeats(SSR)loci found by using the results of genome skimming.Based on these 15 SSR markers,the genetic diversity and structure of 193 individuals from ten natural populations were analyzed in detail.In comparison to other endemic and endangered plants in the region,the population of A.delavayi possess a relatively high genetic diversity(He=0.550,I=1.112).AMOVA analysis showed that 68.4%of the total genetic diversity was within populations and 31.6%of the variation occurred among populations.There was a significant genetic differentiation among natural populations of A.delavayi detectable,with low gene flow(Nm=0.591).This might be attributed to geographical barriers and limited seed dispersal.To test the isolation by distance(IBD),we performed Mantel test,which showed a significant correlation between the geographic and genetic distances.In order to cope with the possible biases caused by IBD,we additionally performed Bayesian genetic cluster analyses and principal coordinate analysis(PCoA).The final cluster analysis revealed three groups with distinct geographical distribution.Habitat fragmentation and limited gene flow between these populations may be the main reasons for the current genetic structure.For conservation of this species,we suggest to divide its populations into three protection management units,with subsequent focus on the Yongsheng and Luquan populations which experienced a genetic bottleneck event in the past.
基金supported by the National Natural Science Foundation of China(Grant Nos.31900188,31970225)Natural Science Foundation of Zhejiang Province(Grant No.LY19C030007).
文摘Celtis is a Cannabaceae genus of 60e70 species of trees,or rarely shrubs,commonly known as hackberries.This woody genus consists of very valuable forest plants that provide important wildlife habitat for birds and mammals.Although previous studies have identified its phylogenetic position,interspecific relationships within Celtis remain unclear.In this study,we generated genome skimming data from five Celtis species to analyze phylogenetic relationships within the genus and develop genome resources.The plastomes of Celtis ranged in length from 158,989 bp to 159,082 bp,with a typical angiosperm quadripartite structure,and encoded a total of 132 genes with 20 duplicated in the IRs.Comparative analyses showed that plastome content and structure were relatively conserved.Whole plastomes showed no signs of gene loss,translocations,inversions,or genome rearrangement.Six plastid hotspot regions(trnH-psbA,psbA-trnK,trnG-trnR,psbC-trnS,cemA-petA and rps8-rpl14),4097 polymorphic nuclear SSRs,as well as 62 low or single-copy gene fragments were identified within Celtis.Moreover,the phylogenetic relationships based on the complete plastome sequences strongly endorse the placement of C.biondii as sister to the((((C.koraiensis,C.sinensis),C.tetrandra),C.julianae),C.cerasifera)clade.These findings and the genetic resources developed here will be conducive to further studies on the genus Celtis involving phylogeny,population genetics,and conservation biology.
文摘How do you get information from an article as much and fast as possible while you are reading? It is a very important thing for us——Chinese readers. Reading is an important element in our English study. Mastering reading skills will help increase our reading speed and comprehend what we read. Now several reading skills are to be discussed in this paper.
文摘This paper has proposed a new modelling and simulating technique for the echo of the semi-active radar seeker against the sea skimming target. The echo modelling is based on the electromagnetic scattering mechanisms. A modified Four-path model based on the radar detection scene is used to describe the multipath scattering between the target and rough sea surface. A Facet-based Small Slope Approximation (FBSSA) method is employed to calculate the scattering from the sea surface. The Physical Optics (PO) and the Equivalent Edge Current (EEC) Method is used to calculate the target scattering. In the echo simulations. The results present the original echo and the echo processed by the signal processing procedures, where the clutter and multipath effect can be observed.
