Epidemiological Surveillance: Genetic Diversity of Rotavirus Group A in the Pearl River Delta, Guangdong, China in 2019

Objective This study aimed to understand the epidemic status and phylogenetic relationships of rotavirus group A(RVA)in the Pearl River Delta region of Guangdong Province,China.Methods This study included individuals aged 28 days–85 years.A total of 706 stool samples from patients with acute gastroenteritis collected between January 2019 and January 2020 were analyzed for 17 causative pathogens,including RVA,using a Gastrointestinal Pathogen Panel,followed by genotyping,virus isolation,and complete sequencing to assess the genetic diversity of RVA.Results The overall RVA infection rate was 14.59%(103/706),with an irregular epidemiological pattern.The proportion of co-infection with RVA and other pathogens was 39.81%(41/103).Acute gastroenteritis is highly prevalent in young children aged 0–1 year,and RVA is the key pathogen circulating in patients 6–10 months of age with diarrhea.G9P[8](58.25%,60/103)was found to be the predominant genotype in the RVA strains,and the 41 RVA-positive strains that were successfully sequenced belonged to three different RVA genotypes in the phylogenetic analysis.Recombination analysis showed that gene reassortment events,selection pressure,codon usage bias,gene polymorphism,and post-translational modifications(PTMs)occurred in the G9P[8]and G3P[8]strains.Conclusion This study provides molecular evidence of RVA prevalence in the Pearl River Delta region of China,further enriching the existing information on its genetics and evolutionary characteristics and suggesting the emergence of genetic diversity.Strengthening the surveillance of genotypic changes and gene reassortment in RVA strains is essential for further research and a better understanding of strain variations for further vaccine development.

Nematode Diversity of Qingdao Coast Inferred from the 18S Ribosomal RNA Gene Sequence Analysis

The 18S ribosomal DNA gene （18S rDNA） sequences （approxtmately 1300 bp in length） were amplified from the DNA extracted from the free-living marine nematodes collected from the inter-tidal sediment of Qingdao coast in bulk with nematode specific primers. The PCR products were cloned, re-amplified, digested with Rsa I and Hin61 restriction endonucleases and separated in agarose gel. Among 17 restriction fragment length types, types 1, 2 and 6 covered 61.2%, 14.4% and 9.3% of the clones analyzed, respectively, while the remaining 14 only covered 21 clones, which accounted for 15.1% of the total. Twenty-four representative clones were sequenced and phylogenetically analyzed by referring to those currently available in RDP and GenBank databases. Although it was hard to assign these sequences to known species or genera due to the lack of the 18S rDNA sequence data of known marine free-living nematodes, the obtained sequences were assigned to the nematodes of Adenophorea. Among them, twelve sequences were close to Pontonema vulgate and Adoncholaimus sp., four to Daptonema procerus and two （identical） to Enoplus brews. Our results showed that free-living marine nematode diversities could be determined by PCR retrieving and analysis of the 18S rDNA sequences and an 18S rDNA sequence could be assigned to a species or a genus only if the 18S rDNA sequences of the free-living marine nematodes were accumulated to some extent.

Cultural Diversity of Traditional Settlement Landscape Gene

As a crucial channel for understanding traditional settlements culture,traditional settlement landscape gene is of vital importance to figure out status quo of traditional Chinese culture,to protect cultural heritage of settlements,and to help residents establish cultural confidence.This paper adopts diversity index,schema analysis,and qualitative analysis methods to identify cultural diversity and construct diversity map of cultural landscape genes.It shows that cultural diversity of landscape genes refers to the various forms of cultural factors in architecture,environment,culture,and layout,including type diversity,combination diversity,and functional diversity.

Comparative Study on Genetic Diversity of Beauveria bassiana in Different Forest Ecosystems

ISSR molecular marker technology was adopted to conduct comparison analysis on genetic diversity level and population genetic structure of Beauveria bassiana population in natural secondary forest （Langyashan national forest park） in Chuzhou City of Anhui Province and artificial pure pine forest （Magushan forest farm） in Xuancheng City of Anhui Province.Seven primers were selected to conduct PCR amplification on total 222 strains of B.bassiana in two populations,a total of 58 unique amplified loci were obtained through amplification,the number of polymorphic loci was 56,the percentage of polymorphic loci was 96.55%,Nei＇s genetic diversity was 0.299 3,Shannon information index was 0.459 3,genetic differentiation coefficient among populations （Gst） was 0.128 3,gene flow Nm=3.398 4;the gene flow between the two populations was small,genetic differentiation was relatively large,being 12.83%,this may be caused by human selective pressures and barrier of gene flow;the genetic variation level of B.bassiana populations in Langyashan was relatively high（PPL=96.55%,H=0.278 1,I= 0.429 9）;the genetic variation level of B.bassiana populations in Magushan was relatively low（PPL=93.10%,H=0.255 2,I= 0.382 5）.The genetic diversity of B.bassiana from the primary forest in Dabieshan was studied（PPL=81.00%,H=0.318 7,I= 0.478 2）,indicating that the genetic diversity of B.bassiana populations in Dabieshan with complex ecological environment was the highest,followed by the populations in natural secondary forest,and the genetic diversity in artificial pure pine forest was the lowest.Nei＇s genetic distance was adopted to construct the genetic relationship dendrogram of B.bassiana individuals collected from Langyashan and Magushan,from the cluster analysis of UPGMA,the strains from the same collection places clustered together.

Analysis on Genetic Diversity of Mitochondria from Venerupis philippinarum in the Coasts of Yantai and Weihai

[Objective] The aim was to understand genetic diversity and genetic differ- entiation situation of wild V. philippinarum population in the coast of China. [Methed] Based on PCR technology, CO I gene fragments of the mitochondria were amplified from two populations of Yantai and Weihai for sequence analysis. [Result] Fifty sam- ples all obtained CO I gene fragment sequence of 684 bp. A total of 42 haplotypes were defined, and 62 variation loci were detected. The haplotypes diversity of two populations was both high, while the nucleotide diversity was low. The phylogenetic tree of haplotypes established by maximum likelihood （ML） method showed that the samples of two geographic populations presented diffused distribution and had no obvious population differentiation. [Conclusion] The result indicated that the gene ex- change of marine animal is easy, and the separation among different seas is weak.

The arms race between Magnaporthe oryzae and rice: Diversity and interaction of Avr and R genes

Rice blast disease, caused by Magnaporthe oryzae, threatens global food security. The rice blast pathosystem is a longstanding model system for understanding plant-microbe interactions. In order to elucidate the coevolution of the host and pathogen, and provide the appropriate methods for preventing or controlling rice blast disease, researchers have focused on the evolution of virulence factors and resistance genes. Thus far, more than 30 rice blast resistance（R） genes and 12 avirulence（Avr） genes have been cloned. This review summarizes the cloned rice blast R genes, cloned Avr genes of M. oryzae and the interaction between them. This discussion also considers some of the major unanswered questions concerning this pathosystem and the opportunities for future investigations.

Diversity of bacterial lactase genes in intestinal contents of mice with antibiotics-induced diarrhea

AIM To investigate the diversity of bacterial lactase genes in the intestinal contents of mice with antibiotics-induced diarrhea.METHODS Following 2 d of adaptive feeding, 12 specific pathogenfree Kunming mice were randomly divided into the control group and model group. The mouse model of antibiotics-induced diarrhea was established by gastric perfusion with mixed antibiotics(23.33 m L·kg^(-1)·d^(-1)) composed of gentamicin sulfate and cephradine capsules administered for 5 days, and the control group was treated with an equal amount of sterile water. Contents of the jejunum and ileum were then collected and metagenomic DNA was extracted, after which analysis of bacterial lactase genes using operational taxonomic units(OTUs) was carried outafter amplification and sequencing.RESULTS OTUs were 871 and 963 in the model group and control group, respectively, and 690 of these were identical. There were significant differences in Chao1 and ACE indices between the two groups(P < 0.05). Principal component analysis, principal coordination analysis and nonmetric multidimensional scaling analyses showed that OTUs distribution in the control group was relatively intensive, and differences among individuals were small, while in the model group, they were widely dispersed and more diversified. Bacterial lactase genes from the intestinal contents of the control group were related to Proteobacteria, Actinobacteria, Firmicutes and unclassified bacteria. Of these, Proteobacteria was the most abundant phylum. In contrast, the bacterial population was less diverse and abundant in the model group, as the abundance of Bradyrhizobium sp. BTAi1, Agrobacterium sp. H13-3, Acidovorax sp. KKS102, Azoarcus sp. KH32 C and Aeromonas caviae was lower than that in the control group. In addition, of the known species, the control group and model group had their own unique genera, respectively.CONCLUSION Antibiotics reduce the diversity of bacterial lactase genes in the intestinal contents, decrease the abundance of lactase gene, change the lactase gene strains, and transform their structures.

The genetic diversity analysis in the donkey myostatin gene

Myostatin（MSTN）gene negatively controls skeletal muscle development and growth,variations of which play an important role in the regulation of skeletal muscle growth in mammals.However,study on genetic polymorphism of MSTN gene in donkey is limited.In this study,we screened the single nucleotide polymorphsims（SNPs）of MSTN gene in 13 Chinese donkey breeds.Four novel SNPs（g.229T〉C,g.872A〉G,g.2014G〉A,and g.2395C〉G）were detected and genotyped by sequencing and polymerase chain reaction-restriction fragment length polymorphism（PCR-RFLP）methods.Six haplotypes（H1–H6）were analyzed,which indicated abundant haplotype diversities in Chinese donkeys.The haplotype H1 was the most dominant and ancient in all breeds.Xinjiang donkey displayed the highest haplotype diversity.The Neighbour-Joining（NJ）tree of MSTN gene among different species was constructed.The clustering result of nine species was consistent with the fact of species differentiation.Our results will provide a reliable theoretical basis for the preservation,exploration and utilization of Chinese donkey genetic resources.

Identification and Analysis of Genetic Diversity Structure Within Pisum Genus Based on Microsatellite Markers

To assesse the genetic diversity among wild and cultivated accessions of 8 taxonomic groups in 2 species, and 5 subspecies under Pisum genus, and to analyze population structure and their genetic relationships among various groups of taxonomy, the study tried to verify the fitness of traditionally botanical taxonomic system under Pisum genus and to provide essential information for the exploration and utilization of wild relatives of pea genetic resources. 197 Pisum accessions from 62 counties of 5 continents were employed for SSR analysis using 21 polymorphic primer pairs in this study. Except for cultivated field pea Pisum sativum ssp. sativum var. sativum （94 genotypes）, also included were wild relative genotypes that were classified as belonging to P. fulvum, P. sativum ssp.abyssinicum, P. sativum ssp. asiaticum, P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. elatius, P. sativum ssp. elatius var. pumilio and P. sativum ssp. sativum var. arvense （103 genotypes）. The PCA analyses and 3-dimension PCA graphs were conducted and drawn by NTSYSpc 2.2d statistical package. Nei78 genetic distances among groups of genetic resources were calculated, and cluster analysis using UPGMA method was carried out by using Popgene V1.32 statistical package, the dendrogram was drawn by MEGA3.1 statistical package. Allelic statistics were carried out by Popgene V1.32. The significance test between groups of genotypes was carried out by Fstat V2.9.3.2 statistical package. 104 polymorphic bands were amplified using 21 SSR primer pairs with unambiguous unique polymorphic bands. 4.95 alleles were detected by each SSR primer pair in average, of which 65.56% were effective alleles for diversity. PSAD270, PSAC58, PSAA18, PSAC75, PSAA175 and PSAB72 were the most effective SSR pairs. SSR alleles were uniformly distributed among botanical taxon units under Pisum genus, but significant difference appeared in most pairwise comparisons for genetic diversity between taxon unit based groups of genetic resources. Genetic diversity level of wild species P. fulvum was much lower than the cultivated species P. sativum. Under species P. sativum, P. sativum ssp. sativum var. sativum and P. sativum ssp. asiaticum were the highest in gentic diversity, followed by P. sativum ssp. elatius var. elatius and P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. pumilio, P. sativum ssp. sativum vat. arvense and P. sativum ssp. abyssinicum were the lowest. Four gene pool clusters were detected under Pisum genus by using PCA analysis. Gene pool ＂fulvum＂ mainly consisted of wild species Pisum fulvum, gene pool ＂abyssinicum＂ mainly consisted of P. sativum ssp. abyssinicum, and gene pool ＂arvense＂ mainly consisted of P. sativum ssp. sativum var. arvense. While gene pool ＂sativum＂ were composed by 5 botanical taxon units, they are P. sativum ssp. asiaticum, P. sativum ssp. elatius var. elatius, P. sativum ssp. transcaucasicum, P. sativum ssp. elatius var. pumilio and P. sativum ssp. sativum var. sativum. ＂sativum＂ gene pool constructed the primary gene pool of cultivated genetic resources; ＂fulvum＂ gene pool, ＂abyssinicum＂ gene pool and ＂arvense＂ gene pool together constructed the secondary gene pool of cultivated genetic resources. Pairwise Nei78 genetic distance among botanical taxon based groups of pea genetic resources ranged from 7.531 to 35.956, 3 large cluster groups were identified based on the UPGMA dendrogram. Group Ⅰ equals to ＂sativum＂ and ＂arvense＂ gene pools, Group Ⅱ equals to ＂abyssinicum＂ gene pool, and Group Ⅲ equals to ＂fulvum＂ gene pool. The UPGMA clustering results generally supporting the PCA clusting results. There were significant differences among most botanical groups under Pisum genus, with clear separation of four gene pools for genetic diversity structure. The research results partially support the traditional botanical taxonomy under Pisum genus, and pointed out its advantage and shortcoming. In order to broaden the genetic bases of pea varieties, the genetic potentials in the four gene pools should be thoroughly exploited.

Microbial community structure and nitrogenase gene diversity of sediment from a deep-sea hydrothermal vent field on the Southwest Indian Ridge

A sediment sample was collected from a deep-sea hydrothermal vent field located at a depth of 2 951 m on the Southwest Indian Ridge. Phylogenetic analyses were performed on the prokaryotic community using polymerase chain reaction（PCR） amplification of the 16 S rRNA and nifH genes. Within the Archaea, the dominant clones were from marine benthic group E（MBGE） and marine group I（MGI） belonging to the phyla Euryarchaeota and Thaumarchaeota, respectively. More than half of the bacterial clones belonged to the Proteobacteria, and most fell within the Gammaproteobacteria. No epsilonproteobacterial sequence was observed. Additional phyla were detected including the Actinobacteria, Bacteroidetes, Planctomycetes, Acidobacteria, Nitrospirae, Chloroflexi, Chlorobi, Chlamydiae, Verrucomicrobia, and candidate divisions OD1, OP11, WS3 and TM6, confirming their existence in hydrothermal vent environments. The detection of nifH gene suggests that biological nitrogen fixation may occur in the hydrothermal vent field of the Southwest Indian Ridge. Phylogenetic analysis indicated that only Clusters I and III NifH were present. This is consistent with the phylogenetic analysis of the microbial 16 S rRNA genes, indicating that Bacteria play the main role in nitrogen fixation in this hydrothermal vent environment.

Genetic Diversity and Genetic Changes in the Introgression Lines Derived from Oryza sativa L. Mating with O. rufipogon Griff.

The objectives of the present study were to estimate genetic diversity and genetic changes of introgression lines （ILs） which derived from cultivated rice （Oryza sativa L. cv. Xieqingzao B, XB） mating with common wild rice （O. rufipogon Griff., CWR）. The genetic data of 239 ILs were based on a total of 131 polymorphic microsatellite （SSR） markers distributed across the 12 chromosomes of rice. On average, these ILs possessed 77.1 and 14.31% homozygous bands from XB and CWR, respectively. Most of the ILs were clustered together with XB individual, which was revealed by principal coordinate analysis （PCA） and the program STRUCTURE analysis. The result from PCA demonstrated that some intermediate genotypes between XB and CWR were also found. Moreover, there were some genomic sequence changes including parental bands elimination and novel bands emergence in the ILs. The average Nei＇s gene diversity （He） was 0.296, which was higher than that of cultivated rice. It suggested that interspecific hybridization and gene introgression could broaden the base of genetic variation and lay an important foundation for rice genetic improvement. These different genotypic ILs would provide a better experimental system for understanding the evolution of rice species and the mechanism of alien gene introgression.

Study on Genetic Diversity of Some Cattle Breeds

Four microsatellites IDG VA-11, IDG VA-27, IDG VA-44 and IDG VA-46 were used to analyze genetic diversity of five cattle breeds. The average gene diversity of the four loci was 0.57, of which IDG VA-11 was 0.66. Genetic diversity of five cattle breeds was 0. 57, Nanyang was the highest 0. 66, Yanbian and Korea cattle were 0.51 and 0. 53, respectively. The fact that the observed diversity was lower than expected in Simmental and Piemontese crossbred showed existing selection and inbreeding impacts. The gene flow between Yanbian and Korea cattle, and that between Simmental and Piemontese crossbred were as high as 23. 79 and 7.15 for each pairs of them, which showed their closer origins.

Genetic Diversity in Populations of Sepiella maindroni Using 16S rRNA Gene Sequence Analysis

Part of the 16S rRNA gene is amplified with PCR and sequenced for 5 populations of com-mon Chinese cuttlefish Sepiella maindroni: three from the South China Sea, one from East China Sea and one from Japan. The result shows that a total of 5 nucleotide positions are found to have gaps or insertions of base pairs among these individuals, and 13 positions are examined to be variable in all the sequences, which range from 494 to 509 base pairs. All of the individuals are grouped into 7 haplotypes (h1-h7). No marked genetic difference is observed among those populations. All of the individuals from Nagasaki belong to hl and the h3 haplotype is found only in the coastal waters of China. A(?)G transition in Nucleotide 255 is suggested to be taken as a kind of genetic marker to identify the populations distributed in East-South China Sea and the Nagasaki waters of Japan.

Genetic Diversity of Recurrent Selection Populations with Ms2 Gene Assessed by Gliadins in Common Wheat (Triticum aestivum L.)

The male-sterile lines with Ms2 gene were highly evaluated in recurrent selection in wheat （Triticum aestivum L.）. Three populations C6 （population after six cycles of selection）, C7 （population after seven cycles of selection）, and C8 （population after eight cycles of selection） were constructed through recurrent selection with 12 parental materials （P）. Acid polyacrymide gel electrophoresis （A-PAGE） analysis was used to identify gliadin patterns and evaluate the genetic diversity in 12 parents and three populations. A total of 63 bands were identified, of which 17 polymorphic bands and 7 unique bands were present in populations and seven polymorphic bands and four unique bands were present in parents. The number of polymorphic and unique bands decreased gradually from C6 to C8, especially for to- and y-gliadins. The genetic distances in C6, C7, and C8 were calculated. The distributions of genetic distance were different in three recurrent selection populations. From C6 to C8, the genetic distance was 0.2687, 0.2652 and 0.1987, respectively. Statistically significant differences were detected between C7 and C8 with the T value of 37.9718. The result of cluster analysis based on genetic similarity matrix of three populations fitted well to those of principle coordinates analysis （PCoA）. Compared with 12 parents, almost all individuals of three populations are new genotypes. Most of the individuals from C6 and C7 could be divided into two groups, while most individuals of C8 were in one cluster. In conclusion, the results indicated that the genetic diversity was decreased severely according to the information revealed by A-PAGE, although some variations could be created in the recurrent selection. It was necessary to introduce diverse germplasm based on the genetic database of recurrent population to maintain and improve the breeding efficiency in the further program.

Comparative Study of the Genetic Diversity, Antimicrobial Resistance, and Pathogenicity of Aeromonas Isolates from Clinical Patients and Healthy Individuals

Objective This study was performed to compare the genetic diversity,virulence,and antimicrobial resistance of Aeromonas strains isolated from patients and healthy individuals.Methods A total of 38 clinical strains and 19 strains from healthy individuals were isolated from the samples collected in Ma’anshan City,Anhui Province.Their taxonomy was investigated using concatenated gyrB-cpn60 sequences,and their resistance to 12 antibiotics was evaluated.The pathogenicity of these strains was examined through beta-hemolysis,protease activity,and virulence gene assays.Results The 57 Aeromonas strains were divided into 55 sequence types.Of these types,21 were novel,suggesting that their genetic diversity was high.These Aeromonas isolates could be divided into 7 species,and the positive rates of beta-hemolysis and protease activity were 49.1%and 73.7%,respectively.The detection rate of clinical patients in terms of beta-hemolysis and protease activity was higher than that of healthy individuals.Among the four most common Aeromonas strains,A.dhakensis had the highest detection rate of virulence genes.The multidrug resistance rate of the clinical isolates was much higher than that of the strains isolated from healthy individuals.Conclusions The taxonomy,virulence properties,and antibiotic resistance of Aeromonas isolates from patients differ from those of the isolates from healthy individuals.

Phylogenetic diversity of planktonic bacteria in the Chukchi Borderland region in summer

Planktonic bacteria are abundant in the Chukchi Borderland region. However, little is known about their di- versity and the roles of various bacteria in the ocean. Seawater samples were collected from two stations K2S and K4S where sea ice was melting obviously. The analysis of water samples with fluorescence in situ hybridization （FISH） showed that DMSP-degrading bacteria accounted for 13% of the total bacteria at the station K2S. No aerobic anoxygenic phototrophic （AAP） bacteria were detected in both samples. The bacterial communities were characterized by two 16S rRNA gene clone libraries. Sequences fell into four major lineages of the domain Bacteria, including Proteobacteria （Alpha, Beta and Gamma subclasses）, Bac- teroidetes, Actinobacteria and Firmicutes. No significant difference was found between the two clone li- braries. SAR11 and Rhodobacteraceae clades of Alphaproteobacteria and Pseudoalteromonas of Gammapro- teobacteria constituted three dominant fractions in the clone libraries. A total of 191 heterotrophic bacterial strains were isolated and 76% showed extracellular proteolytic activity. Phylogenetic analysis reveals that the isolates fell into Gammaproteobacteria, Bacteroidetes, Actinobacteria and Firmicutes. The most common genus in both the bacterial isolates and protease-producing bacteria was Pseudoalteromonas. UniFrac data showed suggestive differences in bacterial communities between the Chukchi Borderland and the northern Bering Sea.

Molecular Genetic Diversity in Iranian Populations of <i>Puccinia triticina</i>, the Causal Agent of Wheat Leaf Rust

Wheat leaf rust caused by Puccinia triticina, is the most common and widely distributed wheat rust in the world. In order to study the genetic structure of leaf rust population 14 pairs of AFLP and 6 pairs of FAFLP primers evaluated on 86 isolates samples collected in Iran during spring of 2009. Results showed that almost all investigated isolates were genetically different and special pattern of AFLP allele’s that confirm high genetic diversity within leaf rust population was observed. Analyses showed, all provinces were classified into three major groups particularly similar clusters were found between then neighboring provinces. Rust spore can follow the migration pattern in short and long distances to neighbor in provinces. Results indicated that the greatest variability was revealed by 97% of genetic differentiation within leaf rust populations and the lesser variation of 3% was observed between the rust populations. These results suggested that each population was not completely identical and high gene flow has occurred among the leaf rust population of different provinces. The highest differentiation and genetic distance among the Iranian leaf rust populations was detected between leaf rust population in Sistan and Baluchistan and highest similarity was observed between in Ardabil provinces. The high pathogenic variability of leaf rust races in Ardabil and Northern Khorasan may be an indication that these two regions are the center of origin of pathogenic arability. Present study shows that leaf rust population in Iran is highly dynamic and variable.

Genetic diversity in two Japanese flounder populations from China seas inferred using microsatellite markers and COI sequences

Japanese flounder is one of the most important commercial species in China; however, information on the genetic background of natural populations in China seas is scarce. The lack of genetic data has hampered fishery management and aquaculture development programs for this species. In the present study, we have analyzed the genetic diversity in natural populations of Japanese flounder sampled from the Yellow Sea （Qingdao population, QD） and East China Sea （Zhoushan population, ZS） using 10 polymorphic mierosatellite loci and cytochrome c oxidase subunit I （COI） sequencing data. A total of 68 different alleles were observed over 10 microsatellite loci. The total number of alleles per locus ranged from 2 to 9, and the number of genotypes per locus ranged from 3 to 45. The observed heterozygosity and expected heterozygosity in QD were 0.733 and 0.779, respectively, and in ZS the heterozygosity values were 0.708 and 0.783, respectively. Significant departures from Hardy-Weinberg equilibrium were observed in 7 of the 10 microsatellite loci in each of the two populations. The COI sequencing analysis revealed 25 polymorphic sites and 15 haplotypes in the two populations. The haplotype diversity and nucleotide diversity in the QD population were 0.746±0.072 8 and 0.003 34±0.001 03 respectively, and in ZS population the genetic diversity values were 0.712±0.047 0 and 0.003 18±0.000 49, respectively. The microsatellite data （Fst=0.048 7, P〈0.001） and mitochondrial DNA data （Fst=0.128, P〈0.001） both revealed significant genetic differentiation between the two populations. The information on the genetic variation and differentiation in Japanese flounder obtained in this study could be used to set up suitable guidelines for the management and conservation of this species, as well as for managing artificial selection programs. In future studies, more geographically diverse stocks should be used to obtain a deeper understanding of the population structure of Japanese flounder in the China seas and adjacent regions.

Phylogenetic Diversity of Microorganisms from Chemocline of the Meromictic Soda Lake Doroninskoe(Zabaikalie,Russia)

1 Introduction Many soda and salt lakes are characterized by the formation of the meromictic conditions under which a part of the water column is not involved in the annual process of mixing(Mac Intyre,Melack,1982).This creates an

Genetic diversity and conservation of two threatened dipterocarps(Dipterocarpaceae) in southeast Vietnam

Two threatened dipterocarp species,Dipterocarpus costatus and Dipterocarpus alatus are well-known endangered species in lowland forests of southeastern Vietnam,primarily from habitat loss and over-exploitation of their wood.To develop conservation strategies for these species,we analyzed 242 samples using nine microsatellite markers to determine the genetic variability within and among five populations of D.alatus and three of D.costatus,representing the natural range of dipterocarps in Southeast Vietnam.Results indicated low levels of genetic variability within populations with an average gene diversity of 0.223 for D.alatus and 0.152 for D.costatus.Results of bottleneck tests indicated a reduction in population size of both species(P>0.05).Genetic differentiation among populations was high(FST=0.347 for D.costatus and 0.274 for D.alatus),indicating limited gene flow(Nm=0.662 for D.costatus and 0.47 for D.alatus)and isolated populations related to geographical distances.Analysis of molecular variance showed high genetic variation within populations(72.92%for D.alatus and 60.81%for D.costatus)compared to among populations.Bayesian analysis and UPGMA tree also indicated the two optimal genetic clusters related to geographical distances.These results will provide a platform for the conservation,management and restoration of these species.