We report two new three-dimensionally phosphatized microfossils, Cambrolongispina reticulata gen. et sp. nov. and Cambrolongispina glabra gen. et sp. nov., from the middle Cambrian （Series 3, Drumian Stage） at Wangc...We report two new three-dimensionally phosphatized microfossils, Cambrolongispina reticulata gen. et sp. nov. and Cambrolongispina glabra gen. et sp. nov., from the middle Cambrian （Series 3, Drumian Stage） at Wangcun, Yongshun County, western Hunan, South China. They are bivalved arthropods, with thin, pliable, originally chitinous or chitin-calcareous shields （c. 350-517 I1 m long）. The shields are equipped with a pair of antero-dorsal spines. The spines are internally hollow, varying in length from 1/2 of to as long as the shield length in C. reticulata, and uniformly longer than the shield length in C. glabra. The spines of C. reticulata are ornamented with a longitudinal row of conical or blade-shaped denticles along the posterior edge. Cambrolongispina lacks marginal rims, valve lobation and sulci which are diagnostic of the Bradoriida sensu stricto. It also lacks a donblure/duplicature characteristic of phosphatocopids and some bradoriids. It could be related to the Monasteriidae （which may belong to Bradoriida sensu lato）, both characterized by a pair of antero-dorsal spines. Cambrolongispina may have been meiofaunai detritus feeders that lived on or within sediments. The antero-dorsal spines may have been sensory organs to detect nearby predators. The posterior denticles on these spines might have facilitated the sensory function of the spines.展开更多
Benthic bivalves,the most widely distributed mollusks since the Mesozoic era,often inhabited environments where their fossilized remains are found adjacent to or intermingled with organic-rich shale.Recent Jurassic sh...Benthic bivalves,the most widely distributed mollusks since the Mesozoic era,often inhabited environments where their fossilized remains are found adjacent to or intermingled with organic-rich shale.Recent Jurassic shale oil exploration in the Sichuan Basin has revealed that bioclastic layers,composed of abundant fossil bivalves and closely associated with shales and,exhibit significant hydrocarbon potentials.However,the microscopic structures of these bivalve fossils and their role in hydrocarbon storage and migration remain poorly understood.In this study,we characterized the microporosity of bivalve shells within the Middle-Lower Jurassic bioclastic shale in the northeastern Sichuan Basin using a combination of 2D imaging(thin section,SEM),3D reconstruction(FIB-SEM),and permeability simulation.The micropores within the shell fossils range from 100 to 1000 nm in radius and are uniformly distributed in a grid-like pattern within the shell interior,where they host liquid hydrocarbons.The bioclastic carbonate layers exhibit an overall porosity of approximately 0.8%.Comparative analysis with extant bivalve shells suggests that these micropores represent residual pores from the nacreous brick wall structure.Due to the regular orientation of the shells and their microporous nacres,permeability coefficients along the long bivalve fossil axes are three to five times higher than those along the short axes.These residual micropores within the bioclastic fossil shells have a positive influence on both the storage and migration of shale oil and gas,making bioclastic fossil-bearing shalespromising sweet spots for shale oil and gas exploration in similar sedimentary environments.展开更多
Rapid industrial growth,urbanization,and agricultural activities have led to the discharge of large volumes of pollutants into coastal environments,raising levels of metals such as arsenic(As),cadmium(Cd),and mercury(...Rapid industrial growth,urbanization,and agricultural activities have led to the discharge of large volumes of pollutants into coastal environments,raising levels of metals such as arsenic(As),cadmium(Cd),and mercury(Hg)in water and sediments.Bivalve molluscs,such as Meretrix lyrata and Saccostrea glomerata can accumulate high amounts of toxic heavy metals in their tissues that pose potential risks to human health.They are frequently used as bioindicators due to their filter-feeding behavior and high accumulation potential.This study evaluates heavy metal accumulation in bivalve molluscs from Northeastern Vietnam,including Quang Ninh Province and Hai Phong City.In this study,a systematic literature review was conducted,combined with a bibliometric analysis,to synthesize and evaluate data on heavy metal accumulation in bivalve molluscs from Northeastern Vietnam.The analysis results showed bio-concentration factors exceeding 1,000 for As,Cd,and Hg in certain species,particularly in samples from Quang Ninh Province.Meanwhile,sediment accumulation factors(BSAF)were lower,suggesting that waterborne pathways predominantly contribute to heavy metal uptake.These findings highlight significant food safety risks due to toxic metal accumulation in seafood resources,emphasizing the urgent need for continuous monitoring and the establishment of local safety standards.The study provides important scientific evidence to support marine environmental management and public health protection.展开更多
Waptia-like euarthropods existed for rather a long time in the Early Cambrian of eastern Yunnan;well preserved representatives come mainly from three Burgess Shale-type biotas:Chengjiang,Xiaoshiba and Guanshan.Here,we...Waptia-like euarthropods existed for rather a long time in the Early Cambrian of eastern Yunnan;well preserved representatives come mainly from three Burgess Shale-type biotas:Chengjiang,Xiaoshiba and Guanshan.Here,we introduce a newly-discovered bivalved euarthropod from the Guanshan biota,the specific identity of which cannot be confirmed due to the absence of soft parts and poor preservation of the specimen,but its general morphology allows it be attributed to Waptia.Two representatives from the Chengjiang and Xiaoshiba biotas are also reconsidered:the preservation mode and length of specimens of Clypecaris pteroidea are variable;Clypecaris serrate has limbs beneath the carapace,which can number up to at least 4 pairs.The fossil sections bearing Waptia-like euarthropods occur over a wide area around Dianchi Lake.展开更多
Although pharmaceuticals have beendetected in the environment only in the range from ng/L to μg/L, it has beendemonstrated that they can adversely affect the health status of aquatic organisms. Lysosomal membrane sta...Although pharmaceuticals have beendetected in the environment only in the range from ng/L to μg/L, it has beendemonstrated that they can adversely affect the health status of aquatic organisms. Lysosomal membrane stability （LMS） has previously been applied as an indicator of cellularwell-being todetermine health status in bivalve mussels. The objective of this study is to evaluate LMS in Ruditapes philippinarum haemolymph using the neutral red retention assay （NRRA）. Clamswere exposed in laboratory conditions to caffeine （0.1, 5, 15, 50 μg/L）, ibuprofen （0.1, 5, 10, 50 μg/L）, carbamazepine and novobiocin （both at 0.1, 1, 10, 50 μg/L） for35days. Results show adose-dependent effect of the pharmaceuticals. The neutral red retention time measured at the end of the bioassaywas significantly reduced by 50% after exposure to environmental concentrations （p 〈 0.05） （caffeine = 15 μg/L; ibuprofen = 10 μg/L; carbamazepine = 1 μg/L and novobiocin = 1 μg/L）, compared to controls. Clams exposed to these pharmaceuticalswere considered to present adiminished health status （retention time 〈45 min）, significantlyworse than controls （96 min） （p 〈 0.05）. The predicted no environmental effect concentration （PNEC） results showed that these pharmaceuticals are very toxic at the environmental concentrations tested. Measurement of the alteration of LMS has been found to be a sensitive technique that enables evaluation of the health status of clams after exposure to pharmaceuticals under laboratory conditions, thus representing a robust Tier-1 screening biomarker.展开更多
Octopus minor is widely distributed along the northern coast of China. To date, there is little information on the prey selection process of this species. To understand this process, several experiments were carried o...Octopus minor is widely distributed along the northern coast of China. To date, there is little information on the prey selection process of this species. To understand this process, several experiments were carried out. Three types of bivalves, namely, Ruditapes philippinarum , Mactra chinensis , and Mytilus galloprovincialis , were used to observe the prey selection of O . minor and to analyze the potential causes of prey selection from three aspects: prey profi tability, adductor muscle tension and handling time. Under single-prey conditions, we found that the average (±SD) predation rates of O . minor on R . philippinarum , M . chinensis , and M . galloprovincialis were 1.73±0.50, 1.27±0.42, and 0.8±0.2/d, respectively. Under diff erent prey combinations, octopods actively selected one type of prey over the other(s), and the order of prey preference was R . philippinarum , followed by M . chinensis and lastly M. galloprovincialis . Furthermore, the shells of the consumed prey showed that O . minor only consumed bivalves by pulling them apart since there was no evidence of drill holes on the shells. The prey selection of O . minor was related to the prey profi tability and handling time;O . minor appeared to select preys with a higher profi tability and a shorter handling time. However, the diffi culty in opening the bivalve was not consistent with the prey preference of the octopods. These results suggest that O . minor prefers to consume R . philippinarum possibly due to a high profi tability and a short handling time that supports the optimum Foraging Theory.展开更多
The Triassic-Jurassic （Tr-J） boundary marks a major extinction event, which （～200 Ma）resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in ...The Triassic-Jurassic （Tr-J） boundary marks a major extinction event, which （～200 Ma）resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr-J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected： the Late Triassic （Rhaetian） Aratrisporites-Alisporites Assemblage, the Early Jurassic （Hettangian） Perinopollenites-Pinuspollenites Assemblage, and the Sinemurian Perinopollenites-Cycadopites Assemblage. The Tr-J boundary is placed between bed 44and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha （？）, Unio-Ferganoconcha and Waagenoperna-Yananoconcha bivalve assemblages are recognized. The Ferganoconcha （？） bed is limited to the upper Haojiagou Formation,Unio- Ferganoconcha and Waagenoperna- Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine-littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.展开更多
To understand nonylphenol （NP） contamination in the northeast coastal environment in China, NP was determined in 19 sediment and 20 bivalve samples collected during November 2005. NP was identified in all sediment s...To understand nonylphenol （NP） contamination in the northeast coastal environment in China, NP was determined in 19 sediment and 20 bivalve samples collected during November 2005. NP was identified in all sediment samples in the range of 8.8 to 1.0 × 10^3 ng/g dw （dry weight）, with an average of 0.12 × 10^3 ng/g dw. Most of the bivalve samples （oysters and mussels） contained detectable amounts of NP that ranged from ND （not detected） to 7.6 × 10^3 ng/g dw, with an average value of 0.79 × 10^3 ng/g dw. These results indicated that NP is ubiquitous in sediments and bivalves from the northeast coast of China, and are even present in bivalves sold as seafood. Serious contamination with NP was recorded off the coast of Bohai Strait and in semi-enclosed coastal environment such as Jiaozhou Bay and Liaodong Bay. Possible environmental and human health implications were understood in this study.展开更多
Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture （IMTA） systems. A beneficial relationship between seaweed and bivalve in the seaweed- based IMTA system has b...Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture （IMTA） systems. A beneficial relationship between seaweed and bivalve in the seaweed- based IMTA system has been confirmed, but the trophic importance of seaweed-derived particulate organic materials to the co-cultured bivalve is still unclear. We evaluated the trophic importance of the kelp Saccharinajaponica to the co-cultured scallop Chlamysfarreri in a typical IMTA farm in Sungo Bay （Weihai, North China）. The dynamics of detritus carbon in the water were monitored during the culturing period. The proportion of kelp-derived organic matter in the diet of the co-cultured scallop was assessed via the stable carbon isotope method. Results showed that the detritus carbon in the water ranged from 75.52 to 265.19 ~tg/L, which was 25.6% to 73.8% of total particulate organic carbon （TPOC） during the study period. The amount of detritus carbon and its proportion in the TPOC changed throughout the culture cycle of the kelp. Stable carbon isotope analysis showed that the cultured scallop obtained 14.1% to 42.8% of its tissue carbon from the kelp, and that the percentages were closely correlated with the proportion of detritus carbon in the water （F=0.993, P=0.003）. Evaluation showed that for 17 000 tons （wet weight） of annual scallop production, the kelp contributed about 139.3 tons of carbon （535.8 tons of dry mass）. This confirms that cultured kelp plays a similar trophic role in IMTA systems as it does in a natural kelp bed. It is a major contributor to the detritus pool and supplies a vital food source to filter-feeding scallops in the IMTA system, especially during winter and early spring when phytoplankton are scarce.展开更多
The effects of a PSP producing dinoflagellate Alexandrium tamarense on marine bivalvesat their several important life stages: egg, D- shape larva, eyespot larva, juvenile and adult, were studied. The results show that...The effects of a PSP producing dinoflagellate Alexandrium tamarense on marine bivalvesat their several important life stages: egg, D- shape larva, eyespot larva, juvenile and adult, were studied. The results show that the hatching, survival, activity, filtration and growth were adversely affected by the alga and the impact was significantly increased with the increase of algal density. The inhibitory effect on egg hatching was most significant, which the hatching rate was only 30% of the control when exposed to the alga at 100 cell/cm3 after 36 h. Further experiments show that the algal culture, re-suspended cells and cell fragments had the inhibitory effect, while no such effect was from the cell-free medium, cell contents and standard STX. The results indicate that the alga could produce unknown toxins, rather than PSP, associated with the cell surface.展开更多
As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we i...As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we investigated the microplastic pollution in wild and farmed oysters(Crassostrea gigas)and clams(Ruditapes philippinarum)in the Jiaozhou Bay,China,for the fi rst time.We found the microplastic pollution in shellfi sh in Jiaozhou Bay was at a moderate level.The abundance of microplastics in shellfi sh ranged from 0.16 to 12.09 items/g(wet weight,ww)or 1 to 9 items/ind.The average abundance of the ingested microplastics was 1.21 items/g(or 2.17 items/ind.)in all shellfi sh,1.51 items/g(or 2.00 items/ind.)in clams and 0.92 items/g(or 2.34 items/ind.)in oysters.The abundance of microplastics in clams was signifi cantly higher than that in oysters.Most microplastics(92.97%)were fi bers,followed by fragments.The predominant color of the microplastics was black(42.97%),followed by blue,transparent,and red.Cellophane and polyethylene terephthalate(PET)dominated the microplastic composition.According to shellfi sh consumption,it can be inferred that the average microplastic consumption through Chinese diet is 1.27×10^(3)items per capita per year.展开更多
After the end-Permian mass extinction, genus Claraia （Bivalvia） was the most abundant and most noticeable fossil during the survival and recovery stage. However, the reasons for the proliferation of Claraia are stil...After the end-Permian mass extinction, genus Claraia （Bivalvia） was the most abundant and most noticeable fossil during the survival and recovery stage. However, the reasons for the proliferation of Claraia are still debated. This paper describes a new Griesbachian （Early Triassic） mollusc fauna from deep-water settings in South China in the aftermath of end-Permian mass extinction. This fauna yielded five bivalve species in two genera （Claraia griesbachi, C. wangi, C. stachei, C. radialis, and Promyalina putiatinensis） and two ammonoid species （Ophiceras sp. and Ussuridiscus sp.） and could be assigned to the Claraia wangi-C, griesbachi assemblage zone, indicating a Middle-Late Griesbachian Age. The bivalves were dominated by Claraia griesbachi and were featured by articulated Claraia fossils. As Claraia was epibyssate, it was an excellent autochthonous fauna. While the shallow and deep marine water became dysoxic to anoxic globally, as indicated by recent studies of the early Early Triassic, we suggest the genus Claraia could tolerate dysoxic and/or anoxic conditions and its proliferation could be attributed to its physiological features which were adapted to the stressed environment. The wide distribution of Claraia was probably related to its planktonic larval stage. Where the larva of Claraia could have been transported by ocean flow and increased its potential for long-distance dispersal. In addition, Claraia was a significant disaster and opportunistic taxon during the Early Triassic based on observations in South China.展开更多
Bivalve farming plays a dominant role in mariculture in China.Paralytic shellfish toxins(PSTs)can be accumulated in bivalves and cause poisoning the consumers.A sensitive detection of PSTs can provide early warning to...Bivalve farming plays a dominant role in mariculture in China.Paralytic shellfish toxins(PSTs)can be accumulated in bivalves and cause poisoning the consumers.A sensitive detection of PSTs can provide early warning to decrease poisoning events in bivalve consuming.PSTs are traditionally examined using the whole soft-tissues.However,PSTs accumulation varies dramatically in different tissues of bivalves.Some tough tissues/organs(such as mantle),which account for a large proportion of the total soft body,exhibit a lower accumulation of PSTs and make the toxin extraction time-and reagent-consuming,potentially decreasing the accuracy and sensitivity of PSTs monitoring in bivalves.To develop a sensitive and cost-effective approach for PSTs examination in massively farmed bivalves,we fed three commercially important bivalves,Yesso scallop Patinopecten yessoensis,Pacific oyster Crassostrea gigas,and blue mussel Mytilus edulis with PSTs-producing dinoflagellate Alexandrium catenella,and detected PSTs concentration in different tissues.For all three bivalve species,the digestive gland accumulated much more PSTs than other tissues,and the digestive gland’s toxicity was significantly correlated with the PSTs toxicity of the whole soft-tissues,with r^(2)=0.94,0.92,and 0.94 for Yesso scallop,Pacific oyster,and blue mussel,respectively.When the toxicity of the whole soft-tissues reached 80μgSTXeq(100g)^(−1),the regulatory limit for commercial shellfish,the digestive gland’s toxicity reached 571.48,498.90,and 859.20μgSTXeq(100g)^(−1) in Yesso scallop,Pacific oyster,and blue mussel,respectively.Our results indicate that digestive gland can be used for the sensitive and cost-effective monitoring of PSTs in bivalves.展开更多
Since the beginning of the 21 st century,the increasing production and application of nano-TiO_(2)in consumer products have inevitably led to its release into aquatic systems and therefore caused the exposure of aquat...Since the beginning of the 21 st century,the increasing production and application of nano-TiO_(2)in consumer products have inevitably led to its release into aquatic systems and therefore caused the exposure of aquatic organisms,resulting in growing environmental concerns.However,the safety of nano-TiO_(2)in aquatic environments has not been systematically assessed,especially in coastal and estuary waters where a large number of filterfeeding animals live.Bivalves are considered around the world to be a unique target group for nanoparticle toxicity,and numerous studies have been conducted to test the toxic effects of nano-TiO_(2)on bivalves.The aim of this review was to systematically summarize and analyze published data concerning the toxicological effects of nano-TiO_(2)in bivalves.In particular,the toxicity of nano-TiO_(2)to the antioxidant system and cell physiology was subjected to meta-analysis to reveal the mechanism of the toxicological effects of nano-TiO_(2)and the factors affecting its toxicological effects.To reveal the cooperation,hot keywords and cocitations in this field,bibliometric analysis was conducted,and the results showed that the toxicological molecular mechanisms of nano-TiO_(2)and the combined effects of nano-TiO_(2)and other environmental factors are two major hot spots.Finally,some perspectives and insights were provided in this review for future research on nano-TiO_(2)toxicology in bivalves.展开更多
We report the present knowledge about RPHM21, a novel male-specific mitochondrial protein with a putative role in the paternal inheritance of sperm mitochondria in the Manila clam Ruditapes philippinarum, a species wi...We report the present knowledge about RPHM21, a novel male-specific mitochondrial protein with a putative role in the paternal inheritance of sperm mitochondria in the Manila clam Ruditapes philippinarum, a species with doubly uniparental inheritance of mitochondria （DUI）. We review all the available data on rphm21 transcription and translation, analyze in detail its female counterpart, RPHF22, discuss the homology with RPHM21, the putative function and origin, and analyze their polymorphism. The available evidence is compatible with a viral origin of RPHM21 and supports its activity during spermatogenesis. RPHM21 is progressively accumulated in mitochondria and nuclei of spermatogenic cells, and we hypothesize it can influence mitochondrial inheritance and sex- ual differentiation. We propose a testable model that describes how the acquisition of selfish fea- tures by a mitochondrial lineage might have been responsible for the emergence of DUI, and for the evolution of separate sexes （gonochorism） from hermaphroditism. The appearance of DUI most likely entailed the invasion of at least 1 selfish element, and the extant DUI systems can be seen as resolved conflicts. It was proposed that hermaphroditism was the ancestral condition of bivalves, and a correlation between DUI and gonochorism was documented. We hypothesize that DUI might have driven the shift from hermaphroditism to gonochorism, with androdioecy as transi- tion state. The invasion of sex-ratio distorters and the evolution of suppressors can prompt rapid changes among sex-determination mechanisms, and DUI might have been responsible for one of such changes in some bivalve species. If true, DUI would represent the first animal sex-determination system involving mtDNA-encoded proteins.展开更多
Concern over health risk from consumption of bivalves originating from Marudu Bay is escalating due to the rapid agricultural development surrounding the bay. This has motivated us to estimate the health risk index (H...Concern over health risk from consumption of bivalves originating from Marudu Bay is escalating due to the rapid agricultural development surrounding the bay. This has motivated us to estimate the health risk index (HRI) of heavy metals from four commercially important and highly exploited bivalve species which are abundant in the bay. Samples (n = 30) of green mussel (Perna viridis), Asiatic hard clam (Meretrix meretrix), Pacific oyster (Crassosstrea gigas) and marsh clam (Polymesoda expans) were acquired from fishermen in Kg. Teritipan, Marudu Bay. These bivalves were analyzed for heavy metals content using the Inductively Couples Plasma-Optical Emission Spectroscopy (ICP-OES). The study found that the mean contents of Arsenic (As) and Manganese (Mn) in all analyzed bivalves exceeded the permissible limits as well as copper (Cu), lead (Pb) and zinc (Zn) in Pacific oyster, and Zn in marsh clam. It was also noticed that consumption of different bivalve species may bring about health risk from different metals as indicated by varied Total Hazard Index (THI) values. Consumption of the four bivalves was noticed to promote high health risk from As intoxication. Although metal pollution index (MPI) analysis revealed that the bivalves from the bay are currently not seriously impacted by heavy metal pollution, vigorous efforts should be taken to preserve the natural condition of the bay for years to come. There are several ways to minimize health issues from bivalve consumption which include keeping the bivalve natural habitat away from heavy metals pollution by strictly enforcing environmental laws and policies, establishing zones for bivalve fisheries, monitoring heavy metals concentration in bivalve on a regular basis and making depuration process a compulsory requirement in every seafood restaurant throughout the country.展开更多
On the basis of a worldwide review of Claraia , Pseudoclaraia and Eumorphotis , especially their important species , two range zones are recognized:the Pseudoclaraia wangi range zone —— Upper Griesbachian——and the...On the basis of a worldwide review of Claraia , Pseudoclaraia and Eumorphotis , especially their important species , two range zones are recognized:the Pseudoclaraia wangi range zone —— Upper Griesbachian——and the Claraia stachei- C. aurita - Eumorphotis multiformis acme zone——Upper Griesbachian to Lower Smithian This result revises both the tradition-al Chinese concept regarding these fossils as limited in Lower Scythian and the viewpoint of some Eurasian researchers who hold Eumorphotis multiformis to be Upper Scythian .The paleogeographical distribution of the three genera is controlled primarily by temperature (latitude) and secondarily by physiographic separations .Distribution of these fossils is subdivided into four realms and five provinces . The Eastern Asia province of the Tethys realm is suggested as the source area of these fossils .The striking contrast between the composition of the species along the southern and northern margins of the Tethys , together with other distributional characters ,supports the plate tectonic theory .展开更多
Chlamys farreri is an economically important mollusk that can accumulate excessive amounts of cadmium(Cd). Studying the molecular mechanism of Cd accumulation in bivalves is difficult because of the lack of genome bac...Chlamys farreri is an economically important mollusk that can accumulate excessive amounts of cadmium(Cd). Studying the molecular mechanism of Cd accumulation in bivalves is difficult because of the lack of genome background. Transcriptomic analysis based on high-throughput RNA sequencing has been shown to be an efficient and powerful method for the discovery of relevant genes in non-model and genome reference-free organisms. Here, we constructed two c DNA libraries(control and Cd exposure groups) from the digestive gland of C. farreri and compared the transcriptomic data between them. A total of 227 673 transcripts were assembled into 105 071 unigenes, most of which shared high similarity with sequences in the NCBI non-redundant protein database. For functional classification, 24 493 unigenes were assigned to Gene Ontology terms. Additionally, Eu Karyotic Ortholog Groups and Kyoto Encyclopedia of Genes and Genomes analyses assigned 12 028 unigenes to 26 categories and 7 849 unigenes to five pathways, respectively. Comparative transcriptomics analysis identified 3 800 unigenes that were differentially expressed in the Cd-treated group compared with the control group. Among them, genes associated with heavy metal accumulation were screened, including metallothionein, divalent metal transporter, and metal tolerance protein. The functional genes and predicted pathways identified in our study will contribute to a better understanding of the metabolic and immune system in the digestive gland of C. farreri. In addition, the transcriptomic data will provide a comprehensive resource that may contribute to the understanding of molecular mechanisms that respond to marine pollutants in bivalves.展开更多
Pollution of the aquatic environment is an ever-growing problem, as waters are the ultimate sink for the large number of xenobiotics from multiple sources. DNA damaging agents have a significant ecological relevance s...Pollution of the aquatic environment is an ever-growing problem, as waters are the ultimate sink for the large number of xenobiotics from multiple sources. DNA damaging agents have a significant ecological relevance since they are implicated in many pathological processes and exert effects beyond that of individual being active through following generations. A large number of methods have been applied to evaluate genotoxic damage in different aquatic species. Comet assay, as method for de- tecting DNA alterations, and micronucleus test, as an index of chromosomal damage are the most widely applied and validated methods in field studies. These methods were applied in different vertebrate and invertebrate aquatic species, but only mollusk and fish species have been employed in routine biomonitoring programs. Mussels, due to their widely geographical distribution and the suitability for caging represent the bioindicator of choice in field studies. Mytilus species is the most used marine mussel. The use of fish is limited to specific geographic areas. The present review mainly focuses on the application of comet assay and micronucleus test in mussels. A number of biomonitoring studies in mussels, using comet assay or micronucleus test, revealed exposure to different classes of genotoxic compounds with a good discrimination power. The different evidence from the two as- says, reflects different biological mechanisms for the two genetic endpoints, DNA damage and chromosomal damage, suggesting their combined application in the field. Different endogenous and exogenous factors have been shown to modulate the genotoxic responses in mussels, acting as confounding factors in environmental monitoring. The use of standardized protocol for caging, sampling and genotoxity evaluation is critical in biomonitoring studies. The use of a multimarker approach coupling genotoxicity biomarkers with physiological and biochemical factors allows to have a complete picture of the environmental pollution [Current Zoology 60 （2）： 273-284, 2014].展开更多
基金supported by the National Natural Science Foundation of China (41102003 and J1210006 to ZH41272011 to XS+3 种基金41372015 to DXP)State Key Laboratory of Palaeobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology,Chinese Academy of Sciences (20132107 to ZH103102 to DXP)the Research Fund for Doctoral Program of High Education (20060001059 to DXP)
文摘We report two new three-dimensionally phosphatized microfossils, Cambrolongispina reticulata gen. et sp. nov. and Cambrolongispina glabra gen. et sp. nov., from the middle Cambrian （Series 3, Drumian Stage） at Wangcun, Yongshun County, western Hunan, South China. They are bivalved arthropods, with thin, pliable, originally chitinous or chitin-calcareous shields （c. 350-517 I1 m long）. The shields are equipped with a pair of antero-dorsal spines. The spines are internally hollow, varying in length from 1/2 of to as long as the shield length in C. reticulata, and uniformly longer than the shield length in C. glabra. The spines of C. reticulata are ornamented with a longitudinal row of conical or blade-shaped denticles along the posterior edge. Cambrolongispina lacks marginal rims, valve lobation and sulci which are diagnostic of the Bradoriida sensu stricto. It also lacks a donblure/duplicature characteristic of phosphatocopids and some bradoriids. It could be related to the Monasteriidae （which may belong to Bradoriida sensu lato）, both characterized by a pair of antero-dorsal spines. Cambrolongispina may have been meiofaunai detritus feeders that lived on or within sediments. The antero-dorsal spines may have been sensory organs to detect nearby predators. The posterior denticles on these spines might have facilitated the sensory function of the spines.
基金supported by the National Natural Science Foundation of China(No.42173030)the Open Project from the Key Laboratory of Shale Gas Exploration,Ministry of Natural Resources(KLSGE-202406).
文摘Benthic bivalves,the most widely distributed mollusks since the Mesozoic era,often inhabited environments where their fossilized remains are found adjacent to or intermingled with organic-rich shale.Recent Jurassic shale oil exploration in the Sichuan Basin has revealed that bioclastic layers,composed of abundant fossil bivalves and closely associated with shales and,exhibit significant hydrocarbon potentials.However,the microscopic structures of these bivalve fossils and their role in hydrocarbon storage and migration remain poorly understood.In this study,we characterized the microporosity of bivalve shells within the Middle-Lower Jurassic bioclastic shale in the northeastern Sichuan Basin using a combination of 2D imaging(thin section,SEM),3D reconstruction(FIB-SEM),and permeability simulation.The micropores within the shell fossils range from 100 to 1000 nm in radius and are uniformly distributed in a grid-like pattern within the shell interior,where they host liquid hydrocarbons.The bioclastic carbonate layers exhibit an overall porosity of approximately 0.8%.Comparative analysis with extant bivalve shells suggests that these micropores represent residual pores from the nacreous brick wall structure.Due to the regular orientation of the shells and their microporous nacres,permeability coefficients along the long bivalve fossil axes are three to five times higher than those along the short axes.These residual micropores within the bioclastic fossil shells have a positive influence on both the storage and migration of shale oil and gas,making bioclastic fossil-bearing shalespromising sweet spots for shale oil and gas exploration in similar sedimentary environments.
文摘Rapid industrial growth,urbanization,and agricultural activities have led to the discharge of large volumes of pollutants into coastal environments,raising levels of metals such as arsenic(As),cadmium(Cd),and mercury(Hg)in water and sediments.Bivalve molluscs,such as Meretrix lyrata and Saccostrea glomerata can accumulate high amounts of toxic heavy metals in their tissues that pose potential risks to human health.They are frequently used as bioindicators due to their filter-feeding behavior and high accumulation potential.This study evaluates heavy metal accumulation in bivalve molluscs from Northeastern Vietnam,including Quang Ninh Province and Hai Phong City.In this study,a systematic literature review was conducted,combined with a bibliometric analysis,to synthesize and evaluate data on heavy metal accumulation in bivalve molluscs from Northeastern Vietnam.The analysis results showed bio-concentration factors exceeding 1,000 for As,Cd,and Hg in certain species,particularly in samples from Quang Ninh Province.Meanwhile,sediment accumulation factors(BSAF)were lower,suggesting that waterborne pathways predominantly contribute to heavy metal uptake.These findings highlight significant food safety risks due to toxic metal accumulation in seafood resources,emphasizing the urgent need for continuous monitoring and the establishment of local safety standards.The study provides important scientific evidence to support marine environmental management and public health protection.
文摘Waptia-like euarthropods existed for rather a long time in the Early Cambrian of eastern Yunnan;well preserved representatives come mainly from three Burgess Shale-type biotas:Chengjiang,Xiaoshiba and Guanshan.Here,we introduce a newly-discovered bivalved euarthropod from the Guanshan biota,the specific identity of which cannot be confirmed due to the absence of soft parts and poor preservation of the specimen,but its general morphology allows it be attributed to Waptia.Two representatives from the Chengjiang and Xiaoshiba biotas are also reconsidered:the preservation mode and length of specimens of Clypecaris pteroidea are variable;Clypecaris serrate has limbs beneath the carapace,which can number up to at least 4 pairs.The fossil sections bearing Waptia-like euarthropods occur over a wide area around Dianchi Lake.
基金conducted under the framework of the project P09-RNM-5136(Government of Andalu-sia,Spain)partially financed by the UN-ESCO/UNITWIN/WiCop as part of the research activities of the Erasmus Mundus Master's degree in Water and Coastal Managementthe financial support from MAEC-AECID(Government of Spain),Becas Chile(Government of Chile),and Junta de Andaluc'a(Government of Andalusia,Spain)
文摘Although pharmaceuticals have beendetected in the environment only in the range from ng/L to μg/L, it has beendemonstrated that they can adversely affect the health status of aquatic organisms. Lysosomal membrane stability （LMS） has previously been applied as an indicator of cellularwell-being todetermine health status in bivalve mussels. The objective of this study is to evaluate LMS in Ruditapes philippinarum haemolymph using the neutral red retention assay （NRRA）. Clamswere exposed in laboratory conditions to caffeine （0.1, 5, 15, 50 μg/L）, ibuprofen （0.1, 5, 10, 50 μg/L）, carbamazepine and novobiocin （both at 0.1, 1, 10, 50 μg/L） for35days. Results show adose-dependent effect of the pharmaceuticals. The neutral red retention time measured at the end of the bioassaywas significantly reduced by 50% after exposure to environmental concentrations （p 〈 0.05） （caffeine = 15 μg/L; ibuprofen = 10 μg/L; carbamazepine = 1 μg/L and novobiocin = 1 μg/L）, compared to controls. Clams exposed to these pharmaceuticalswere considered to present adiminished health status （retention time 〈45 min）, significantlyworse than controls （96 min） （p 〈 0.05）. The predicted no environmental effect concentration （PNEC） results showed that these pharmaceuticals are very toxic at the environmental concentrations tested. Measurement of the alteration of LMS has been found to be a sensitive technique that enables evaluation of the health status of clams after exposure to pharmaceuticals under laboratory conditions, thus representing a robust Tier-1 screening biomarker.
基金Supported by the Fundamental Research Funds for the Central Universities(No.201822022)the Key Development Plan of Shandong Province(No.2016GSF115014)
文摘Octopus minor is widely distributed along the northern coast of China. To date, there is little information on the prey selection process of this species. To understand this process, several experiments were carried out. Three types of bivalves, namely, Ruditapes philippinarum , Mactra chinensis , and Mytilus galloprovincialis , were used to observe the prey selection of O . minor and to analyze the potential causes of prey selection from three aspects: prey profi tability, adductor muscle tension and handling time. Under single-prey conditions, we found that the average (±SD) predation rates of O . minor on R . philippinarum , M . chinensis , and M . galloprovincialis were 1.73±0.50, 1.27±0.42, and 0.8±0.2/d, respectively. Under diff erent prey combinations, octopods actively selected one type of prey over the other(s), and the order of prey preference was R . philippinarum , followed by M . chinensis and lastly M. galloprovincialis . Furthermore, the shells of the consumed prey showed that O . minor only consumed bivalves by pulling them apart since there was no evidence of drill holes on the shells. The prey selection of O . minor was related to the prey profi tability and handling time;O . minor appeared to select preys with a higher profi tability and a shorter handling time. However, the diffi culty in opening the bivalve was not consistent with the prey preference of the octopods. These results suggest that O . minor prefers to consume R . philippinarum possibly due to a high profi tability and a short handling time that supports the optimum Foraging Theory.
基金supported by Special Basic Research Program of Ministry of Science and Technology of China (Grant No. 2006FY120300)National Committee of Stratigraphy of China. V. Vajda acknowledges the financial support provided by Swedish Research Council (VR, Grant No. 2007-4509)+1 种基金V. Vajda is a Swedish Royal Academy of Sciences Research Fellow founded through the Knut and Alice Wallenbergs Foundationa contribution to UNESCO-IUGS IGCP Project 506
文摘The Triassic-Jurassic （Tr-J） boundary marks a major extinction event, which （～200 Ma）resulted in global extinctions of fauna and flora both in the marine and terrestrial realms. There prevail great challenges in determining the exact location of the terrestrial Tr-J boundary, because of endemism of taxa and the scarcity of fossils in terrestrial settings leading to difficulties in linking marine and terrestrial sedimentary successions. Investigation based on palynology and bivalves has been carried out over a 1113 m thick section, which is subdivided into 132 beds, along the Haojiagou valley on the southern margin of the Junggar Basin of the northern Xinjiang, northwestern China. The terrestrial Lower Jurassic is conformably resting on the Upper Triassic strata. The Upper Triassic covers the Huangshanjie Formation overlaid by the Haojiagou Formation, while the Lower Jurassic comprises the Badaowan Formation followed by the Sangonghe Formation. Fifty six pollen and spore taxa and one algal taxon were identified from the sediments. Based on the key-species and abundance of spores and pollen, three zones were erected： the Late Triassic （Rhaetian） Aratrisporites-Alisporites Assemblage, the Early Jurassic （Hettangian） Perinopollenites-Pinuspollenites Assemblage, and the Sinemurian Perinopollenites-Cycadopites Assemblage. The Tr-J boundary is placed between bed 44and 45 coincident with the boundary between the Haojiagou and Badaowan formations. Beds with Ferganoconcha （？）, Unio-Ferganoconcha and Waagenoperna-Yananoconcha bivalve assemblages are recognized. The Ferganoconcha （？） bed is limited to the upper Haojiagou Formation,Unio- Ferganoconcha and Waagenoperna- Yananoconcha assemblages are present in the middle and upper members of the Badaowan Formation. The sedimentary succession is interpreted as terrestrial with two mainly lake deposit intervals within Haojiagou and Badaowan formations, yielding fresh water algae and bivalves. However, the presence of brackish water algae Tasmanites and the marine-littoral facies bivalve Waagenoperna from the Badaowan Formation indicate that the Junggar Basin was influenced by sea water caused by transgressions from the northern Tethys, during the Sinemurian.
基金supported by the National Natural Science Foundation of China(No.20767006)the National High Technology Research and Development Program(863) of China(No.2006AA09Z175)
文摘To understand nonylphenol （NP） contamination in the northeast coastal environment in China, NP was determined in 19 sediment and 20 bivalve samples collected during November 2005. NP was identified in all sediment samples in the range of 8.8 to 1.0 × 10^3 ng/g dw （dry weight）, with an average of 0.12 × 10^3 ng/g dw. Most of the bivalve samples （oysters and mussels） contained detectable amounts of NP that ranged from ND （not detected） to 7.6 × 10^3 ng/g dw, with an average value of 0.79 × 10^3 ng/g dw. These results indicated that NP is ubiquitous in sediments and bivalves from the northeast coast of China, and are even present in bivalves sold as seafood. Serious contamination with NP was recorded off the coast of Bohai Strait and in semi-enclosed coastal environment such as Jiaozhou Bay and Liaodong Bay. Possible environmental and human health implications were understood in this study.
基金Supported by the National Key Technologies R&D Program of China(No.2011BAD13B02)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406403)the Marine Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA11020704)
文摘Bivalves and seaweeds are important cleaners that are widely used in integrated multi-trophic aquaculture （IMTA） systems. A beneficial relationship between seaweed and bivalve in the seaweed- based IMTA system has been confirmed, but the trophic importance of seaweed-derived particulate organic materials to the co-cultured bivalve is still unclear. We evaluated the trophic importance of the kelp Saccharinajaponica to the co-cultured scallop Chlamysfarreri in a typical IMTA farm in Sungo Bay （Weihai, North China）. The dynamics of detritus carbon in the water were monitored during the culturing period. The proportion of kelp-derived organic matter in the diet of the co-cultured scallop was assessed via the stable carbon isotope method. Results showed that the detritus carbon in the water ranged from 75.52 to 265.19 ~tg/L, which was 25.6% to 73.8% of total particulate organic carbon （TPOC） during the study period. The amount of detritus carbon and its proportion in the TPOC changed throughout the culture cycle of the kelp. Stable carbon isotope analysis showed that the cultured scallop obtained 14.1% to 42.8% of its tissue carbon from the kelp, and that the percentages were closely correlated with the proportion of detritus carbon in the water （F=0.993, P=0.003）. Evaluation showed that for 17 000 tons （wet weight） of annual scallop production, the kelp contributed about 139.3 tons of carbon （535.8 tons of dry mass）. This confirms that cultured kelp plays a similar trophic role in IMTA systems as it does in a natural kelp bed. It is a major contributor to the detritus pool and supplies a vital food source to filter-feeding scallops in the IMTA system, especially during winter and early spring when phytoplankton are scarce.
基金This study was supported by the National Basic Research Project under contract No.2001CB409709,National Natural Science Foundation of China under contract Nos 49906007,39950001,20177023 and 40076030,CAS Innovation Program under contract No.KZCX2-206,Dire
文摘The effects of a PSP producing dinoflagellate Alexandrium tamarense on marine bivalvesat their several important life stages: egg, D- shape larva, eyespot larva, juvenile and adult, were studied. The results show that the hatching, survival, activity, filtration and growth were adversely affected by the alga and the impact was significantly increased with the increase of algal density. The inhibitory effect on egg hatching was most significant, which the hatching rate was only 30% of the control when exposed to the alga at 100 cell/cm3 after 36 h. Further experiments show that the algal culture, re-suspended cells and cell fragments had the inhibitory effect, while no such effect was from the cell-free medium, cell contents and standard STX. The results indicate that the alga could produce unknown toxins, rather than PSP, associated with the cell surface.
基金Supported by the International Science Partnership Program of the Chinese Academy of Sciences(Nos.121311KYSB20190029,133137KYSB20200002)the Joint Funds of the National Natural Science Foundation of China(No.U2006206)the Strategic Priority Research Program of the Chinese Academy of Sciences(Nos.XDA19060204,XDA23050303),and the Project from Shandong Academy for Environmental Planning:Research on the Prevention and Control of Marine Microplastic Pollution in Key Industries in Shandong Province。
文摘As an emerging pollutant,the presence of microplastics in marine organisms has been concerned increasingly.Shellfi sh,which are both economically and ecologically important,are of particular concern.In this study,we investigated the microplastic pollution in wild and farmed oysters(Crassostrea gigas)and clams(Ruditapes philippinarum)in the Jiaozhou Bay,China,for the fi rst time.We found the microplastic pollution in shellfi sh in Jiaozhou Bay was at a moderate level.The abundance of microplastics in shellfi sh ranged from 0.16 to 12.09 items/g(wet weight,ww)or 1 to 9 items/ind.The average abundance of the ingested microplastics was 1.21 items/g(or 2.17 items/ind.)in all shellfi sh,1.51 items/g(or 2.00 items/ind.)in clams and 0.92 items/g(or 2.34 items/ind.)in oysters.The abundance of microplastics in clams was signifi cantly higher than that in oysters.Most microplastics(92.97%)were fi bers,followed by fragments.The predominant color of the microplastics was black(42.97%),followed by blue,transparent,and red.Cellophane and polyethylene terephthalate(PET)dominated the microplastic composition.According to shellfi sh consumption,it can be inferred that the average microplastic consumption through Chinese diet is 1.27×10^(3)items per capita per year.
基金supported by the National Natural Science Foundation of China (No. 41502012)the Yangtze Youth Fund of Yangtze University China (No. 2015cqn27)
文摘After the end-Permian mass extinction, genus Claraia （Bivalvia） was the most abundant and most noticeable fossil during the survival and recovery stage. However, the reasons for the proliferation of Claraia are still debated. This paper describes a new Griesbachian （Early Triassic） mollusc fauna from deep-water settings in South China in the aftermath of end-Permian mass extinction. This fauna yielded five bivalve species in two genera （Claraia griesbachi, C. wangi, C. stachei, C. radialis, and Promyalina putiatinensis） and two ammonoid species （Ophiceras sp. and Ussuridiscus sp.） and could be assigned to the Claraia wangi-C, griesbachi assemblage zone, indicating a Middle-Late Griesbachian Age. The bivalves were dominated by Claraia griesbachi and were featured by articulated Claraia fossils. As Claraia was epibyssate, it was an excellent autochthonous fauna. While the shallow and deep marine water became dysoxic to anoxic globally, as indicated by recent studies of the early Early Triassic, we suggest the genus Claraia could tolerate dysoxic and/or anoxic conditions and its proliferation could be attributed to its physiological features which were adapted to the stressed environment. The wide distribution of Claraia was probably related to its planktonic larval stage. Where the larva of Claraia could have been transported by ocean flow and increased its potential for long-distance dispersal. In addition, Claraia was a significant disaster and opportunistic taxon during the Early Triassic based on observations in South China.
基金funded by the National Key R&D Project(No.2019YFC1605704)the Taishan Industry Leading Talent Project(No.LJNY201816)supported by Sanya Yazhou Bay Science and Technology City(No.SKJCKJ-2019KY01).
文摘Bivalve farming plays a dominant role in mariculture in China.Paralytic shellfish toxins(PSTs)can be accumulated in bivalves and cause poisoning the consumers.A sensitive detection of PSTs can provide early warning to decrease poisoning events in bivalve consuming.PSTs are traditionally examined using the whole soft-tissues.However,PSTs accumulation varies dramatically in different tissues of bivalves.Some tough tissues/organs(such as mantle),which account for a large proportion of the total soft body,exhibit a lower accumulation of PSTs and make the toxin extraction time-and reagent-consuming,potentially decreasing the accuracy and sensitivity of PSTs monitoring in bivalves.To develop a sensitive and cost-effective approach for PSTs examination in massively farmed bivalves,we fed three commercially important bivalves,Yesso scallop Patinopecten yessoensis,Pacific oyster Crassostrea gigas,and blue mussel Mytilus edulis with PSTs-producing dinoflagellate Alexandrium catenella,and detected PSTs concentration in different tissues.For all three bivalve species,the digestive gland accumulated much more PSTs than other tissues,and the digestive gland’s toxicity was significantly correlated with the PSTs toxicity of the whole soft-tissues,with r^(2)=0.94,0.92,and 0.94 for Yesso scallop,Pacific oyster,and blue mussel,respectively.When the toxicity of the whole soft-tissues reached 80μgSTXeq(100g)^(−1),the regulatory limit for commercial shellfish,the digestive gland’s toxicity reached 571.48,498.90,and 859.20μgSTXeq(100g)^(−1) in Yesso scallop,Pacific oyster,and blue mussel,respectively.Our results indicate that digestive gland can be used for the sensitive and cost-effective monitoring of PSTs in bivalves.
基金supported by the Natural Science Foundation of China(No.31872587)the Shanghai Pujiang Talent Program(No.18PJ1404000)+1 种基金Shanghai Municipal Natural Science Foundation(No.17ZR1412900)the National Key Research and Development Program of China(No.2017YFA0207003)。
文摘Since the beginning of the 21 st century,the increasing production and application of nano-TiO_(2)in consumer products have inevitably led to its release into aquatic systems and therefore caused the exposure of aquatic organisms,resulting in growing environmental concerns.However,the safety of nano-TiO_(2)in aquatic environments has not been systematically assessed,especially in coastal and estuary waters where a large number of filterfeeding animals live.Bivalves are considered around the world to be a unique target group for nanoparticle toxicity,and numerous studies have been conducted to test the toxic effects of nano-TiO_(2)on bivalves.The aim of this review was to systematically summarize and analyze published data concerning the toxicological effects of nano-TiO_(2)in bivalves.In particular,the toxicity of nano-TiO_(2)to the antioxidant system and cell physiology was subjected to meta-analysis to reveal the mechanism of the toxicological effects of nano-TiO_(2)and the factors affecting its toxicological effects.To reveal the cooperation,hot keywords and cocitations in this field,bibliometric analysis was conducted,and the results showed that the toxicological molecular mechanisms of nano-TiO_(2)and the combined effects of nano-TiO_(2)and other environmental factors are two major hot spots.Finally,some perspectives and insights were provided in this review for future research on nano-TiO_(2)toxicology in bivalves.
文摘We report the present knowledge about RPHM21, a novel male-specific mitochondrial protein with a putative role in the paternal inheritance of sperm mitochondria in the Manila clam Ruditapes philippinarum, a species with doubly uniparental inheritance of mitochondria （DUI）. We review all the available data on rphm21 transcription and translation, analyze in detail its female counterpart, RPHF22, discuss the homology with RPHM21, the putative function and origin, and analyze their polymorphism. The available evidence is compatible with a viral origin of RPHM21 and supports its activity during spermatogenesis. RPHM21 is progressively accumulated in mitochondria and nuclei of spermatogenic cells, and we hypothesize it can influence mitochondrial inheritance and sex- ual differentiation. We propose a testable model that describes how the acquisition of selfish fea- tures by a mitochondrial lineage might have been responsible for the emergence of DUI, and for the evolution of separate sexes （gonochorism） from hermaphroditism. The appearance of DUI most likely entailed the invasion of at least 1 selfish element, and the extant DUI systems can be seen as resolved conflicts. It was proposed that hermaphroditism was the ancestral condition of bivalves, and a correlation between DUI and gonochorism was documented. We hypothesize that DUI might have driven the shift from hermaphroditism to gonochorism, with androdioecy as transi- tion state. The invasion of sex-ratio distorters and the evolution of suppressors can prompt rapid changes among sex-determination mechanisms, and DUI might have been responsible for one of such changes in some bivalve species. If true, DUI would represent the first animal sex-determination system involving mtDNA-encoded proteins.
文摘Concern over health risk from consumption of bivalves originating from Marudu Bay is escalating due to the rapid agricultural development surrounding the bay. This has motivated us to estimate the health risk index (HRI) of heavy metals from four commercially important and highly exploited bivalve species which are abundant in the bay. Samples (n = 30) of green mussel (Perna viridis), Asiatic hard clam (Meretrix meretrix), Pacific oyster (Crassosstrea gigas) and marsh clam (Polymesoda expans) were acquired from fishermen in Kg. Teritipan, Marudu Bay. These bivalves were analyzed for heavy metals content using the Inductively Couples Plasma-Optical Emission Spectroscopy (ICP-OES). The study found that the mean contents of Arsenic (As) and Manganese (Mn) in all analyzed bivalves exceeded the permissible limits as well as copper (Cu), lead (Pb) and zinc (Zn) in Pacific oyster, and Zn in marsh clam. It was also noticed that consumption of different bivalve species may bring about health risk from different metals as indicated by varied Total Hazard Index (THI) values. Consumption of the four bivalves was noticed to promote high health risk from As intoxication. Although metal pollution index (MPI) analysis revealed that the bivalves from the bay are currently not seriously impacted by heavy metal pollution, vigorous efforts should be taken to preserve the natural condition of the bay for years to come. There are several ways to minimize health issues from bivalve consumption which include keeping the bivalve natural habitat away from heavy metals pollution by strictly enforcing environmental laws and policies, establishing zones for bivalve fisheries, monitoring heavy metals concentration in bivalve on a regular basis and making depuration process a compulsory requirement in every seafood restaurant throughout the country.
文摘On the basis of a worldwide review of Claraia , Pseudoclaraia and Eumorphotis , especially their important species , two range zones are recognized:the Pseudoclaraia wangi range zone —— Upper Griesbachian——and the Claraia stachei- C. aurita - Eumorphotis multiformis acme zone——Upper Griesbachian to Lower Smithian This result revises both the tradition-al Chinese concept regarding these fossils as limited in Lower Scythian and the viewpoint of some Eurasian researchers who hold Eumorphotis multiformis to be Upper Scythian .The paleogeographical distribution of the three genera is controlled primarily by temperature (latitude) and secondarily by physiographic separations .Distribution of these fossils is subdivided into four realms and five provinces . The Eastern Asia province of the Tethys realm is suggested as the source area of these fossils .The striking contrast between the composition of the species along the southern and northern margins of the Tethys , together with other distributional characters ,supports the plate tectonic theory .
基金Supported by the Shandong Provincial Post-Doctoral Special Fund Innovative Project(No.S43201403)the Post-Doctoral Applied Research Project of Qingdao City(No.Q51201413)the Shandong Provincial Natural Science Foundation,China(No.ZR2015PD004)
文摘Chlamys farreri is an economically important mollusk that can accumulate excessive amounts of cadmium(Cd). Studying the molecular mechanism of Cd accumulation in bivalves is difficult because of the lack of genome background. Transcriptomic analysis based on high-throughput RNA sequencing has been shown to be an efficient and powerful method for the discovery of relevant genes in non-model and genome reference-free organisms. Here, we constructed two c DNA libraries(control and Cd exposure groups) from the digestive gland of C. farreri and compared the transcriptomic data between them. A total of 227 673 transcripts were assembled into 105 071 unigenes, most of which shared high similarity with sequences in the NCBI non-redundant protein database. For functional classification, 24 493 unigenes were assigned to Gene Ontology terms. Additionally, Eu Karyotic Ortholog Groups and Kyoto Encyclopedia of Genes and Genomes analyses assigned 12 028 unigenes to 26 categories and 7 849 unigenes to five pathways, respectively. Comparative transcriptomics analysis identified 3 800 unigenes that were differentially expressed in the Cd-treated group compared with the control group. Among them, genes associated with heavy metal accumulation were screened, including metallothionein, divalent metal transporter, and metal tolerance protein. The functional genes and predicted pathways identified in our study will contribute to a better understanding of the metabolic and immune system in the digestive gland of C. farreri. In addition, the transcriptomic data will provide a comprehensive resource that may contribute to the understanding of molecular mechanisms that respond to marine pollutants in bivalves.
文摘Pollution of the aquatic environment is an ever-growing problem, as waters are the ultimate sink for the large number of xenobiotics from multiple sources. DNA damaging agents have a significant ecological relevance since they are implicated in many pathological processes and exert effects beyond that of individual being active through following generations. A large number of methods have been applied to evaluate genotoxic damage in different aquatic species. Comet assay, as method for de- tecting DNA alterations, and micronucleus test, as an index of chromosomal damage are the most widely applied and validated methods in field studies. These methods were applied in different vertebrate and invertebrate aquatic species, but only mollusk and fish species have been employed in routine biomonitoring programs. Mussels, due to their widely geographical distribution and the suitability for caging represent the bioindicator of choice in field studies. Mytilus species is the most used marine mussel. The use of fish is limited to specific geographic areas. The present review mainly focuses on the application of comet assay and micronucleus test in mussels. A number of biomonitoring studies in mussels, using comet assay or micronucleus test, revealed exposure to different classes of genotoxic compounds with a good discrimination power. The different evidence from the two as- says, reflects different biological mechanisms for the two genetic endpoints, DNA damage and chromosomal damage, suggesting their combined application in the field. Different endogenous and exogenous factors have been shown to modulate the genotoxic responses in mussels, acting as confounding factors in environmental monitoring. The use of standardized protocol for caging, sampling and genotoxity evaluation is critical in biomonitoring studies. The use of a multimarker approach coupling genotoxicity biomarkers with physiological and biochemical factors allows to have a complete picture of the environmental pollution [Current Zoology 60 （2）： 273-284, 2014].
