Comparative Microsatellite Analysis of Grass Carp Genomes of Two Gynogenetic Groups and the Xiangjiang River Group

The genomes of three groups of grass carp, namely the Xiangjiang River grass carp group （Xiangjiang group）, a one-generation artificially induced meio-gynogenetic grass carp group （meio-gynogenetic-1 group）, and a two-generation artificially induced meio-gynogenetic grass carp group （meio-gynogenetic-2 group）, were comparatively analyzed with microsatellite markers. Genetic polymorphism had been observed in the Xiangjiang group and most of the examined loci had more than two alleles. But the degree of genetic diversity was not very high. Although all the examined genetic loci in the analyzed individuals were in homozygous state, the genotypes of different individuals of the group were not identical in the meio-gynogenetic-1 group. In the meio-gynogenetic-2 group, not only the examined genetic loci of each individual were homozygous but also the genotypes of all the analyzed individuals of the group were the same. These results suggested that the examined meio-gynogenetic-2 group is a homozygous group and homozygous clone could be produced by continuous artificial induction of gynogenesis for two generations. It was found that the polymorphism existed not only at the allele level but also at the locus level; many alleles of the microsatellite loci and some of the microsatellite loci had been lost during the process of artificial gynogenesis. Therefore, both protection of the diversity of natural grass carp resource and selection of homozygous traits with desired economic genotypes are very important aspects for grass carp breeding.

Genetic Diversity of Microsatellite DNA Loci of Tibetan Antelope(Chiru,Pantholops hodgsonii)in Hoh Xil National Nature Reserve,Qinghai,China

The Tibetan antelope （Pantholops hodgsonii）, indigenous to China, became an endangered species because of considerable reduction both in number and distribution during the 20th century. Presently, it is listed as an Appendix Ⅰ species by CITES and as Category I by the Key Protected Wildlife List of China. Understanding the genetic diversity and population structure of the Tibetan antelope is significant for the development of effective conservation plans that will ensure the recovery and future persistence of this species. Twenty-five microsatellites were selected to obtain loci with sufficient levels of polymorphism that can provide information for the analysis of population structure. Among the 25 loci that were examined, nine of them showed high levels of genetic diversity. The nine variable loci （MCM38, MNS64, IOBT395, MCMAL TGLA68, BM1329, BMSI341, BM3501, and MB066） were used to examine the genetic diversity of the Tibetan antelope （n = 75） in Hoh Xil National Nature Reserve（HXNNR）, Qinghai, China. The results obtained by estimating the number of population suggested that all the 75 Tibetan antelope samples were from the same population. The mean number of alleles per locus was 9.4 ± 0.5300 （range, 7-12） and the mean effective number of alleles was 6.519± 0.5271 （range, 4.676-9.169）. The observed mean and expected heterozygosity were 0.844 ± 0.0133 （range, 0.791-0.897） and 0.838 ± 0.0132 （range, 0.786-0.891）, respectively. Mean Polymorphism Information Content （PIC） was 0.818 ± 0.0158 （range, 0.753-0.881）. The value of Fixation index （Fis） ranged from -0.269 to -0.097 with the mean of -0.163 ± 0.0197. Mean Shannon＇s information index was 1.990 ± 0.0719 among nine loci （range, 1.660-2.315）. These results provide baseline data for the evaluation of the level of genetic variation in Tibetan antelope, which will be important for the development of conservation strategies in future.

Microsatellite Variation Within Three Populations of Inbred C57BL/6J Strain

The goal of this study was to investigate the genetic stability of the C57BL/6J （B6） inbred mouse strain maintained in different breeders. Three populations of B6, Popl and Pop2 purchased from Beijing and Pop3 purchased from Shanghai, were examined. Fifteen microsatellite loci reported to be polymorphic among inbred strains were amplified using FAM labeled primers and genotyped with ABI Prism 377 automated sequencer. Seven loci were found polymorphic, and all the loci were homozygous in all the three populations. The present study indicates that genetic variation occurs in different B6 populations although they are still inbred in each breeder. The mechanism of genetic variation is not well understood now, but it is very important to know the precise content of the B6 genome before use of this strain in research.

Location of Vibrio anguillarum resistance-associated trait loci in half-smooth tongue sole Cynoglossus semilaevis at its microsatellite linkage map

A cultured female half-smooth tongue sole(C ynoglossus semilaevis) was crossed with a wild male, yielding the fi rst fi lial generation of pseudo-testcrossing from which 200 fi sh were randomly selected to locate the V ibrio anguillarum resistance trait in half-smooth tongue sole at its microsatellite linkage map. In total, 129 microsatellites were arrayed into 18 linkage groups, ≥4 each. The map reconstructed was 852.85 c M in length with an average spacing of 7.68 c M, covering 72.07% of that expected(1 183.35 cM). The V. anguillarum resistance trait was a composite rather than a unit trait, which was tentatively partitioned into Survival time in Hours After V. anguillarum Infection(SHAVI) and Immunity of V. A nguillarum Infection(IVAI). Above a logarithm of the odds(LOD) threshold of 2.5, 18 loci relative to SHAVI and 3 relative to IVAI were identifi ed. The 3 loci relative to IVAI explained 18.78%, 5.87% and 6.50% of the total phenotypic variation in immunity. The microsatellites bounding the 3 quantitative trait loci(QTLs) of IVAI may in future aid to the selection of V. anguillarum-immune half-smooth tongue sole varieties, and facilitate cloning the gene(s) controlling such immunity.

Isolation and Characterization of Nine Microsatellite Markers for Red-backed Ratsnake,Elaphe rufodorsata

The red-backed ratsnake（Elaphe rufodorsata） is widely distributed in East Asia, especially China. This species is a common snake in plain river network region. In the past several decades, E. rufodorsata has dramatically declined due to the effect of human activities and over hunting for traditional Chinese medicine. We developed nine species-specific microsatellite loci in 190 individuals collected from Huzhou, Zhejiang province in China. These markers revealed a high degree of genetic diversity（13–41 alleles per locus） and heterozygosity（H O ranged from 0.266 to 0.941, and H E ranged from 0.851 to 0.937）. No locus exhibited significant deviations from Hardy–Weinberg equilibrium. There was no evidence of linkage disequilibrium among pairs of loci. These microsatellite markers were described in our study will be valuable tools for the long term management and population-level studies（e.g. the population structure, genetic diversity and variation, individual paternity and evolutionary history） of the species.