Isolation and characterization of bioactive fungi from shark <Emphasis Type="Italic">Carcharodon carcharias</Emphasis>’ gill with biopharmaceutical prospects

Until recently, little was known about the fungi found in shark gills and their biomedicinal potential. In this article, we described the isolation, bioactivity, diversity, and secondary metabolites of bioactive fungi from the gill of a shark (Carcharodon carcharias). A total of 115 isolates were obtained and grown in 12 culture media. Fifty-eight of these isolates demonstrated significant activity in four antimicrobial, pesticidal, and cytotoxic bioassay models. Four randomly selected bioactive isolates inhibited human cancer cell proliferation during re-screening. These active isolates were segregated into 6 genera using the internal transcribed spacer-large subunit (ITS-LSU) rDNA-sequence BLAST comparison. Four genera, Penicillium, Aspergillus, Mucor, and Chaetomium were the dominant taxa. A phylogenic tree illustrated their intergenera and intragenera genetic diversity. HPLC-DAD-HRMS analysis and subsequent database searching revealed that nine representative strains produced diverse bioactive compound profiles. These results detail the broad range of bioactive fungi found in a shark’s gills, revealing their biopharmaceutical potential. To the best of our knowledge, this is the first study characterizing shark gill fungi and their bioactivity.     

Phylogenetic diversity and bioactivity of culturable deep-sea-derived fungi from Okinawa Trough

Deep-sea sediments are now recognized as a home for rich and largely microbial community. Recently, it has been believed in an increasing number of studies that bacteria could be abundant in deepsea sediments of many types; however, fungi in deep-sea sediments remain relatively unknown. The phylogenetic diversity and bioactivity of culturable deep-sea-derived fungi from Okinawa Trough sediments were investigated in traditional method combined with fungal identification of molecular biology in this study. A total of 76 isolates belonged to 15 fungal taxa were recovered in a harsh condition of low nutrient and low temperature, indicating that the fungal communities in deep-sea sediments from Okinawa Trough were relatively abundant and diversified. Aspergillus, Cladosporium, and Penicillium were the dominant fungal genera, while Mycosphaerella, Purpureocillium, and Schizophyllum were relatively rare in the deep-sea sediments from Okinawa Trough. Among the six genera recovered, Mycosphaerella was firstly recovered from deep-sea sediments in this study. Moreover, about 75% of the extracts from the 15 fungal representative isolates displayed distinct bioactivity against at least one indicator bacterium or marine macrofouler, emphasizing the potentials of these deep-sea-derived fungi from Okinawa Trough as producers of bioactive metabolites. Notably, isolates Cladosporium oxysporum SCSIO z001 and Penicillium citrinum SCSIO z049 displayed a wide spectrum of bioactivities, isolates Cladosporium cladosporioides SCSIO z015, Cladosporium sphaerospermum SCSIO z030, and Penicillium verruculosum SCSIO z007 exhibited a strong anti-bacterial-growth activity, and isolate Penicillium chrysogenum SCSIO z062 displayed a strong anti-larval-settlement activity. These results suggest that these isolates deserved further study as potential sources of novel bioactive metabolites.     

Genotoxic Potential of Copper Oxide Nanoparticles in the Bivalve Mollusk Mytilus trossulus

Copper oxide nanoparticles(CuO-NPs) are among the most widely used metal oxide nanoparticles,which increases the chance of their being released into the marine environment.As the applications of these particles have increased in recent years,their potential impact on the health of marine biota has also increased.However,the toxicological effects of these NPs in the marine environment are poorly known.In the present study,the DNA damaging potential of CuO-NPs in the marine eastern mussel Mytilus trossulus was evaluated and compared to that of dissolved copper exposures.Genotoxicity was assessed by the single cell gel electrophoresis(comet) assay in mussel gill and digestive gland cells.The results showed that copper in both forms(CuO-NPs and dissolved copper) was accumulated to different extents in mussel tissues.The mussel exposed to the dissolved copper attained higher concentrations of copper in the gills than in the digestive gland.In contrast to these results,it was found that CuO-NPs could induce much higher copper accumulation in the digestive gland than in the gills.A clear and statistically significant increase in DNA damage was found in both tissues of the Cu-exposed group compared to the control mussels.Our results indicated that the CuO-NP exposure produced remarkable effects and increased DNA damage significantly in mussel gill cells only.It should be noted that the digestive gland cells were prone to accumulation following CuO-NPs when compared to the gill cells,while the gill cells were more sensitive to the genotoxic effects of CuO-NPs.These results also suggested the need for a complete risk assessment of engineered particles before its arrival in the consumer market.     

Genotoxic potential of copper oxide nanoparticles in the bivalve mollusk <Emphasis Type="Italic">Mytilus trossulus</Emphasis>

Copper oxide nanoparticles (CuO-NPs) are among the most widely used metal oxide nanoparticles, which increases the chance of their being released into the marine environment. As the applications of these particles have increased in recent years, their potential impact on the health of marine biota has also increased. However, the toxicological effects of these NPs in the marine environment are poorly known. In the present study, the DNA damaging potential of CuO-NPs in the marine eastern mussel Mytilus trossulus was evaluated and compared to that of dissolved copper exposures. Genotoxicity was assessed by the single cell gel electrophoresis (comet) assay in mussel gill and digestive gland cells. The results showed that copper in both forms (CuO-NPs and dissolved copper) was accumulated to different extents in mussel tissues. The mussel exposed to the dissolved copper attained higher concentrations of copper in the gills than in the digestive gland. In contrast to these results, it was found that CuO-NPs could induce much higher copper accumulation in the digestive gland than in the gills. A clear and statistically significant increase in DNA damage was found in both tissues of the Cu-exposed group compared to the control mussels. Our results indicated that the CuO-NP exposure produced remarkable effects and increased DNA damage significantly in mussel gill cells only. It should be noted that the digestive gland cells were prone to accumulation following CuO-NPs when compared to the gill cells, while the gill cells were more sensitive to the genotoxic effects of CuO-NPs. These results also suggested the need for a complete risk assessment of engineered particles before its arrival in the consumer market.     

MICROHABITAT DISTRIBUTION OF METAZOAN PARASITES ON GILLS OF SILURUS ASOTUS IN JIANGKOU RESERVOIR, JIANGXI PROVINCE, CHINA

ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｅｓｔｉｎａｌｐａｒａｓｉｔｅｃｏｍｍｕｎｉｔｉｅｓｉｎｆｉｓｈａｒｅｆｏｕｎｄｎｏｒｍａｌｌｙｔｏｂｅｐｏｏｒｉｎｔｅｒｍｓｏｆｓｐｅｃｉｅｓｃｏｍｐｏ ｓｉｔｉｏｎｓｗｈｅｎｃｏｍｐａｒｅｄｗｉｔｈｔｈｏｓｅｉｎｂｉｒｄｓａｎｄｓｏｍｅｏｔｈｅｒｈｉｇｈｅｒｖｅｒｔｅｂｒａｔｅｓ (Ｋｅｎｎｅｄｙｅｔａｌ.,1 986;Ｅｓｃｈｅｔａｌ.,1 990 ) .Ｈｏｗｅｖｅｒ,ｅｃｔｏｐａｒａｓｉｔｅｃｏｍｐｏｓｉｔｉｏｎｓｏｎｇｉｌｌｓｏｆｆｉｓｈａｒｅｃｏｎｓｉｄｅｒｅｄａｓｓｐｅｃ…     

徐闻8种珊瑚共附生真菌的分离及初步鉴定

从徐闻珊瑚保护区的8种珊瑚中分离共附生真菌,以获得珊瑚共附生可培养真菌的多样性信息。选用5种培养基,采用平板涂布法培养分离共附生真菌,并进行形态鉴定。8种珊瑚共分离121株真菌,鉴定了其中97株真菌,分属于14个属,青霉属和枝孢霉为优势种属,其次是曲霉属和木霉属。二异角孔珊瑚上分离出22株,数量最多;盔型珊瑚上分离菌株数量最少仅8株。除优势种属外,不同珊瑚样品上真菌种类分布有较大差异,炭角菌属和葡萄穗霉菌属均来源于盔形珊瑚,镰刀菌属在盔形珊瑚和角孔珊瑚上较为常见,盔形珊瑚样品上还分离出2株散囊菌属,1株节菱孢属,因此盔形珊瑚的种群最为丰富;不同培养基分离真菌的能力不同,淀粉培养基分离的菌株最多占所有分离菌株的30.6%,CDA培养基最少,但种类特异。     

Distinct influence of trimethylamine N-oxide and high hydrostatic pressure on community structure and culturable deep-sea bacteria

Trimethylamine N-oxide(TMAO) is one of the most important nutrients for bacteria in the deep-sea environment and is capable of improving pressure tolerance of certain bacterial strains.To assess the impact of TMAO on marine microorganisms,especially those dwelling in the deep-sea environment,we analyzed the bacterial community structure of deep-sea sediments after incubated under different conditions.Enrichments at 50 MPa and 0.1 MPa revealed that TMAO imposed a greater influence on bacterial diversity and community composition at atmospheric pressure condition than that under high hydrostatic pressure(HHP).We found that pressure was the primary factor that determines the bacterial community.Meanwhile,in total,238 bacterial strains were isolated from the enrichments,including 112 strains a ffiliated to 16 genera of 4 phyla from the Yap Trench and 126 strains a ffiliated to 11 genera of 2 phyla from the Mariana Trench.Treatment of HHP reduced both abundance and diversity of isolates,while the presence of TMAO mainly af fected the diversity of isolates obtained.In addition,certain genera were isolated only when TMAO was supplemented.Taken together,we demonstrated that pressure primarily defines the bacterial community and culturable bacterial isolates.Furthermore,we showed for the first time that TMAO had distinct influences on bacterial community depending on the pressure condition.The results enriched the understanding of the significance of TMAO in bacterial adaptation to the deep-sea environment.     

广东水稻纹枯病菌RAPD基因型与致病型关系

分析了广东水稻纹枯病菌(Rhizoctonia solani AG-1IA)致病型多样性和RAPD多态性之间的相互关系。结果表明,供试水稻纹枯病菌表现出较为丰富的致病型多样性(H=3.485)和遗传多样性,55个菌株接种9个水稻品种表现出39种致病类型。11条RAPD随机引物共扩增出91条谱带,其中多态性条带86条,多态率为94.51%。扩增出的22个选择性RAPD位点中,每个菌株都存在特有的RAPD分子指纹图谱。55个菌株在毒力数据、RAPD数据以及两者结合的数据聚类分析UPGMA树形图上形成几个不同的聚类类群,其中一个类群包括了大部分的菌株。毒力数据与RAPD分子数据的Jacarrd相似性距阵间的相关性系数比较低(r=0.0137),说明致病型与RAPD基因型性之间为相互独立的关系。     

Biomarker responses in the bivalve Chlamys farreri to the water-soluble fraction of crude oil

To investigate the effect of the water soluble fraction of crude oil(WSF) on marine bivalves, the scallop C hlamys farreri was exposed to three WSF concentrations(0.18 mg/L, 0.32 mg/L, and 0.51 mg/L, respectively) in seawater. Petroleum hydrocarbon contents in scallops and a suite of enzymes [7-Ethoxyresorufin-O-deethylase(EROD), aryl hydrocarbon hydroxylase(AHH), glutathione S-transferase(GST), and glutathione peroxidase(GPx)] in gills and digestive glands were monitored over 10 days. The results revealed that WSF affected the activity of the four enzymes in the gills and digestive glands. EROD activity in the gills was significantly induced in most individuals of the three test groups, while in the digestive gland it was significantly induced in the low-concentration group within 4 days but was inhibited in the middle- and high-concentration groups on days 1, 4, and 10. AHH activity in the gills of all treatment groups was significantly induced on day 1. In the digestive gland, AHH activity was induced in most individuals from the treatment groups. In all treatment groups, GST activity was significantly inhibited from days 2 to 10 in the gills and was induced after day 4 in the digestive gland. GPx activity in the gills was significantly inhibited throughout the exposure period in all treatment groups. There was no overall significant difference in GPx activity in the digestive gland between the control and treatment groups. Our results also revealed that petroleum hydrocarbon concentrations in the tissues increased linearly with exposure time. EROD activity in the digestive gland and GST and GPx activity in the gill tissue were negatively correlated with petroleum hydrocarbon body burden. These enzymes play important roles in detoxification and can act as potential biomarkers for monitoring petroleum hydrocarbon contaminants in the marine environment.     

Responses of marine-derived Trichoderma fungi to seawater and their potential antagonistic behaviour

To explore the metabolic responses of marine-derived Trichoderma fungi to environmental stresses, the survivability, metabolism, and antagonism of ten marine isolates have been examined. Their survival in both freshwater and seawater indicates them to be facultative marine fungi, but they are more adaptable to marine environment. Most of them feature strain-specific and positive metabolic responses to seawater, which also usually result in the higher proportions of heteroatom-bearing and unsaturated units in mycelial constituents. Seawater factors can promote many strains to produce bioactive metabolites,including plant pathogen-and marine phytoplankton-inhibitory and marine animal-toxic ones, but the ef fects of NaCl are often weak or negative. The inhibition of marine phytoplankton corresponds to the intracellular accumulation of heteroatom-bearing and unsaturated units under seawater condition, and the varied toxicities to marine animals further signify the divergences of lipophilic exudates under dif ferent conditions. The results may contribute to further understanding and mining the structural diversity and biological activity of secondary metabolites from marine-derived Trichoderma fungi.     

Antimicrobial activities of novel cultivable bacteria isolated from marine sponge Tedania anhelans

Marine sponge Tedania anhelans distributes throughout the intertidal zone of Fujian, southeastern China, and is a potential source of natural bioactive products. The sponge harbors a large number of bacterial groups that have been identified using various techniques, including fluorescent in situ hybridization (FISH). Fractionation of dissociated sponge allowed isolation of 25 bacterial species. Based on 16S rRNA gene sequencing, phylogenetic analysis attributed most of these eubacteria to α-Proteobacteria, γ-Proteobacteria, Cytophaga/Flavobacterium/Bacteroidetes (CFB group), and the family Bacillaceae of Gram-positive bacteria. In sequence similarity, five putatively novel species were identified with less than 98% similarity to other strains in the NCBI database. Tests for antimicrobial activities were performed against Gram-positive bacteria, Gram-negative bacteria, fungi, antitumor indicators Escherichia coli 343/591 (with DNA repair deficiency), regular E. coli 343/636 (with different DNA repair capacity), and 10 bacterial isolates exhibited inhibitory bioactivities. Among these strains, three isolates were detected involving function gene NRPS-A domains, which were most closely related to the amino acid sequences of linear gramicidin synthetase and pyoverdine synthetase. These results contribute to our knowledge of the microbes associated with marine sponges and further reveal novel bacterial resources for the screening of bioactive marine natural products.     

Spatio-temporal variability of periphytic protozoa related to environment in the Niyang River,Tibet, China

The Niyang River, a main tributary of the Yarlung Zangbo River, is an important and typical plateau river ecosystem in Tibet, China. At present, few studies have focused on its aquatic living resources and river ecology. In this study, the composition, abundance, and diversity of periphytic protozoa were investigated across four seasons from 2008 to 2009 to better understand their spatio-temporal patterns and relationship to the environment. Our investigation shows that periphytic protozoa in the Niyang River contained 15 genera, belonged to Tubulinea, Alveolata, Discosea and Rhizaria, Alveolata possessed most genera, up to nine, with highest share in abundance, exceeding 50%, Difflugia and Glaucoma were dominant genera. Moreover, four diversity indices of periphytic protozoa, including species richness, total abundance, Shannon-Wiener diversity index and Pielou's evenness index, displayed a significant descending trend as the seasons continued, in the order of winter, spring, summer and autumn; with a significant difference existing between winter and summer(or autumn) for Shannon-Wiener diversity index and species richness( P 0.05). Four of these diversity indices also presented a V-shaped pattern between the upper middle course of the Niyang River and the confluence of the Niyang River and Yarlung Zangbo River, with the lowest value occurred in the middle course of the Niyang River. However, no significant variation was found through the Niyang River( P 0.05). In addition, canonical correlation analysis(CCA) shows that the densities of Difflugia, Glaucoma is, Enchelydium, Cyphoderia, and Enchelys correlate with water temperature, alkalinity, hardness, pH, and dissolved oxygen, respectively. Lastly, the relationship between periphytic protozoa diversity and the environmental factors of the Niyang River can be predicted using classification and regression trees(CART) annalysis, which suggests that the total abundance and Shannon-Wiener diversity index would be higher when the elevation is above 3 308 m. On the other hand, the Shannon-Wiener diversity index and Pielou's evenness index would be lower when pH and ammoniacal nitrogen have lower or higher values. Finally yet importantly, close attention should be paid to periphytic protozoa and its environment to ensure sustainable development of the Niyang River ecosystem.     

Comparison of fungal community composition within different intestinal segments of tilapia and bighead carp

Although intestinal fungi play important roles in host health and disease,the composition and diversity of fungal communities remain poorly reported in fish.In this study,fungi in the fore-,mid-,and hindintestine of tilapia(Oreochromis mossambicus) and bighead carp(Aristichthys nobilis) from Hongchaojiang Reservoir in Guangxi,China were investigated by ITS sequencing.Based on this,we obtained 1 763 478 high-quality tags,which clustered into 1 089 operational taxonomic units(OTUs).In total,404 OTUs were annotated,of which 310,68,and 26 belonged to Ascomycota,Basidiomycota,and other,respectively.Results show significant differences in the community composition of intestinal fungi between tilapia and bighead carp but not within their different intestinal segments.Furthermore,154 of the 404 annotated OTUs were considered reliable and were classified into three trophic modes and nine guilds.The three trophic modes consisted of 108 OTUs of saprotrophic fungi,41 OTUs of pathotrophic fungi,and five OTUs of symbiotrophic fungi.The top three most abundant OTUs overall(i.e.,Otu000002,Scopulariopsis acremonium; Otu000018,Alternaria palandui; Otu000034,Aureobasidium pullulans) showed lower abundance in the hind-intestinal segments of bighead carp,suggesting uneven distribution of these fungi in this species.In addition,saprotrophic and pathotrophic fungi were markedly decreased in the hindintestine.It is indicated that the fungal community was not only related to host species specificity but also to the respective physiological functions of different intestinal segments.These findings provide valuable information on the composition,structure,and potential function of the intestinal fungi community associated with different intestinal segments in tilapia and bighead carp under natural conditions,thus highlighting the importance of fungi as an integral part of the inte stinal microbiota in maintaining host health.     

Mechanism on bipolar distribution of Permian brachiopods

By reasearch on geographic distribution, nine genera in bipolar distribution are selected from Permian brachiopods. These taxa originated from middle-high latitude areas in the boreal realm, of which five genera were derived from Late Carboniferous, and other four genera originated from Permian. They were all in bipolar distribution during some different stages in Permian. Specific diversity for each genus was high in the boreal realm, whereas in the Gondwana realm was very low. Perdurability was long in the boreal realm, and short in the Gondwana realm. It was the time when these nine genera came to their maximum diversity that these genera appeared in the Gondwana and formed bipolar distribution; while they also migrated to the low latitude from high latitude. This shows very close relationship between several main cooling events in Permian and the migration of genera from the boreal realm to the Gondwana realm through the Tethys. Therefore, the cooling events might be the main drive which caused these cold-water-type brachiopods migrated to the Gondwana realm and being bipolar distribution. In this process, the planula tolerance to warm water would be another important factor.     

Microhabitat distribution of metazoan parasites on gills ofSilurus asotus in Jiangkou Reservoir, Jiangxi Province, China

This paper deals with the proportional distribution, niche breadth and niche overlap of two metazoan parasites (copepods species,Ergasilus anchoratus Markewitsch, 1946 andPseudergasilus parasiluri Yamaguti, 1936) and monogeneans (in the genusSilurodiscoides Gussev, 1976) found on gills of the fish,Silurus asotus L. from Jiangkou Reservoir in Jiangxi Province, China.E. anchoratus was the common and dominant metazoan parasite on gills of the fish in this locality as indicated by the higher infection levels, and distributed almost evenly on gill arches without any observed gill-arch preference, as shown by the wide proportional distribution and broad niche breadth.P. parasiluri and monogeneans inSilurodiscoides were found also without any significant gill-arch preference although they had a rather narrow niche breadth. The observed significant overlap betweenP. parasiluri andSilurodiscoides spp. may be simply due to the lower infection levels of the parasites. The observed pattern of unrestricted distributions of the parasitic copepods on gills of the fish may be accounted for, at least in part, by the moving ability of the copepods, and may also indicate that the parasite does not exhibit any feature of gill-arch preference. However, further experimental research is needed to verify the microhabitat distribution of the parasites. Project 39370122 supported by NSFC.     

Spatial distribution of Dactylogyrus wunderi Bychowsky on gills of Abramis brama orientalis Berg (Leuciscinae) in Irtysh River, China

The spatial distribution of the monogenean Dactylogyrus wunderi Bychowsky,1931 on the gill filaments of the bream Abramis brama orientalis Berg(Leuciscinae) inhabiting the Irtysh River of Xinjiang,China was investigated from June to July 2012.D.wunderi was identified by sequencing a fragment of its ITS rDNA region.Sixty-five fish were examined,with 55% testing positive for monogenean infection.The prevalence of the parasite in the left and right gill arches was 46% and 48%,respectively.In fish with a large body length,the prevalence of the parasite and the infection intensity did not significantly differ between the right and left gill arches but both were slightly higher in the former.Among the three size groups of fish(small,medium and large) the prevalence and the intensity of infection were lowest in fish with small body lengths.The distribution of the monogenean population in the host gills showed an aggregate distribution,with little change in the degree of aggregation,suggesting that most hosts were either not or only slightly infected by D.wunderi and that the parasite infected only a few hosts.In addition,differences in D.wunderi infections between gill arches of A.brama orientalis were not significant(P>0.05).     

Molecular Grouping of Grateloupia Tissues Collected Along Chinese Coast and Microsatellite Diversity Analysis of G. asiatica

Genus Grateloupia is one of the most speciose genera in family Halymeniales. It is also one of the sources for natural materials, food and medicine. With different environments, Grateloupia change their morphological characteristics, making their morphological identification very difficult. In addition, few of the species diversity in this genus has been described before. In this study, phylogenetic analysis based on rbc L gene sequence was employed to group Grateloupia collected from three locations along Chinese coast. The microsatellites were also used to evaluate their genetic diversity. In total, the tissue parts of 6 putative species were collected from G. asiatica, G. livida, G. lanceolate, G. catenata, G. turuturu and G. filicina. In order to evaluate their genetic diversity and then conserve them better, 40 microsatellites available for Grateloupia were used to evaluate their genetic diversity, and 11 microsatellites were found to be applicable to determine the genetic diversity of G. asiatica. It was found that the genetic diversity of G. asiatica around Qingdao was very rich. We suggested that the species of genus Grateloupia should be identified based on rbc L phylogenetic analysis before the diversity evaluation with microsatellites. The microsatellites should be developed for each species of Grateloupia so that their genetic diversity can be evaluated appropriately.     

盐度突变对青蛤(Cyclinasinensis)鳃Na~+/K~+-ATPase活性的影响

研究了盐度23下青蛤(Cyclina sinensis)鳃、斧足、外套膜和内脏团中Na+/K+-ATPase的活性差异,并以活性高的鳃组织为对象,对青蛤实施了低盐(23→16)和高盐(23→36)突变的胁迫,监测了鳃组织中Na+/K+-ATPase活性的动态变化。结果表明,盐度23下青蛤鳃组织中Na+/K+-ATPase的活性显著高于其他组织;在盐度突降胁迫下,鳃组织中Na+/K+-ATPase的活性于前16 d逐渐升高,第17d起显著升高(p<0.05),第18 d达到峰值,于第20 d回落,但仍高于起始水平;在盐度骤升胁迫下,鳃组织中Na+/K+-ATPase的活性于前13d逐渐降低,第14 d起显著降低(p<0.05),于第15 d达到最低值,继而回升至平稳水平,但仍低于起始水平。青蛤不同盐度胁迫下其鳃组织中Na+/K+-ATPase活性的响应方式不同,低盐时活性增加,而高盐时活性下降;此外,青蛤在盐度胁迫下对自身渗透压的调节则需较长时间。     

Effect of Salinity on Hemolymph Osmotic Pressure, Sodium Concentration and Na^＋-K^＋-ATPase Activity of Gill of Chinese Crab, Eriocheir sinensis

The effects of salinity on hemolymph osmotic pressure, Na^＋ concentration and Na^＋-K^＋-ATPase activity of gill of Chinese crab Eriocheir sinensis were studied. The results showed that hemolymph osmotic pressure and Na^＋ concentration increased significantly （P〈0.05）, and the Na^＋-K^＋-ATPase activity of gills decreased significantly （P〈0.05） when salinity increased from 0 to 16. The hemolymph osmotic pressure and Na^＋ concentration in each treatment group rose remarkably at 0.125 d or 0.25 d, while the Na^＋-K^＋-ATPase activity of gill reduced gradually with increased experiment time in 3 d. Then the three parameters remained at a constant level after 0.25 d, 0.125 d and 3 d, respectively, and higher hemolymph osmotic pressure, higher Na^＋ concentration and lower Na^＋-K^＋-ATPase activity of gill occurred at higher salinity. The effect of salinity change on protein concentration of hemolymph was indistinct （P〉0.05）; However, the protein concentration decreased gradually with the increase of salinity from 0.25 d to 1d, and then tended to be stable from day 1 to day 15.     

Characterization of Bacterial Community Associated with Four Organs of the Yesso Scallop (Patinopecten yessoensis) by High-Throughput Sequencing

We used Illumina high-throughput sequencing of PCR-amplified V3-V4 16 S rRNA gene regions to characterize bacterial communities associated with the adductor muscles, gills, gonads and intestines of the Yesso scallop(Patinopecten yessoensis) from waters around Zhangzidao, Dalian, China. Overall, 421,276 optimized reads were classified as 25 described bacterial phyla and 308 genera. Firmicutes, Proteobacteria, Tenericutes, Bacteroidetes, Chlamydiae and Spirochaetae accounted for > 97% of the total reads in the four organs. The bacterial 16 S rDNA sequences assigned to Firmicutes and Proteobacteria were abundant in the adductor muscles, gills and gonads; while reads from Tenericutes were dominant in the intestines, followed by those from Firmicutes, Chlamydiae, Proteobacteria and Bacteroidetes. At the genus level, the dominant genera in the adductor muscles, gills and gonads appeared to be Bacillus, Enterococcus and Lactococcus, whereas Mycoplasma was dominant in the intestines. The relative abundances of Bacillus, Enterococcus, Lactococcus, Alkaliphilus, Raoultella, Paenibacillus and Oceanobacillus were significantly lower in the intestine than in the other three organs. Cluster analysis and principal coordinates analysis of the operational taxonomy units profile revealed significant differences in the bacterial community structure between the intestine and the other three organs. Taken together, these results suggest that scallops have intestine-specific bacterial communities and the adductor muscles, gills and gonads harbor similar communities. The difference in the bacterial community between organs may relate to unique habitats, surroundings, diet and their respective physiological functions.