Jingfeng Yang

Genetic analysis of gynogenetic and common populations of Verasper moseri using SSR markers

The genetic structure and variation of the artificial meio- gynogenetic population and common population of barfin flounder (Verasper moseri) were analyzed using eight microsatellite markers. A total of 29 alleles were detected, of which 23 alleles were in the artificial gynogenetic population while 29 alleles were in the control group. The average observed heterozygosity (HO) of eight loci in the control group (0.526 8) was several times higher than that (0.185 8) in the gynogenetic population. The results indicate that the genetic diversity of the control group was much higher than that of the gynogenetic population of barfin flounder (Verasper moseri). Most loci significantly deviated from Hardy-Weinberg equilibrium (HWE) after Bonferroni correction (p < 0.005 56) in the gynogenetic population, while four loci deviated from HWE in the control group. The coefficient of gene differentiation (GST) was 0.131 0, and the genetic distance was 0.171 8 between the two populations, suggesting a significant genetic differentiation between the two populations.

Growth differences and differential expression analysis of pituitary adenylate cyclase activating polypeptide (PACAP) and growth hormone-releasing hormone (GHRH) between the sexes in half-smooth tongue sole Cynoglossus semilaevis

Pituitary adenylate cyclase activating polypeptide (PACAP) and growth hormone-releasing hormone (GHRH) are regulators of growth hormone secretion. In this article, we examined the difference in growth and mRNA expression of PACAP and GHRH between the sexes in half-smooth tongue sole, an important cultured fish species indicating sexually growth dimorphism in China. Firstly, a significant body weight difference between females and males was first observed at 7 months (P<0.05) and at 18 onths the mean body weight of the females (771.0±44.3 g) was as much as 4.9 times higher than that of males (130.6±6.0 g). As a result, half-smooth tongue sole, Cynoglossus semilaevis, is a good model to investigate the effects of growth-related genes expression on sexual growth dimorphism. Secondly, the cDNAs encoding PRP/PACAP and GHRH were isolated. Two differently processed mRNA transcripts of PRP/PACAP (PRP-encoding and PRP splice variant) were found. PACAP and GHRH mRNA was highly abundant in brain and less abundant in other tissues. However, PACAP mRNA was expressed in most brain regions, and was lower in the cerebellum. GHRH mRNA was predominantly expressed in the hypothalamus and weakly expressed in all areas of the brain examined. Ontogenetic expression analysis indicated that PACAP and GHRH mRNA was detected in the early stages of embryogenesis. Finally, differential expression showed that there was no significant difference of the expression level of PACAP or GHRH between the sexes before 8 months of age. However, between 9 and 12 months of age, the GHRH mRNA expression level in males was significantly higher than in females (P<0.05), which might be associated with GH deficiency in males. In contrast, the male PACAP mRNA expression level was not significantly higher than that in females even at 9 and 12 months of age. The present results provide important clues for understanding the sexual growth dimorphism mechanisms in half-smooth tongue sole.

MHC polymorphism and disease resistance to Vibrio anguillarum in 8 families of half-smooth tongue sole (Cynoglossus semilaevis).

BackgroundGenes in the major histocompatibility complex (MHC) have a critical role in both the innate and adaptive immune responses because of their involvement in presenting foreign peptides to T cells. However, the nature has remained largely unknown.ResultsWe examined the genetic variation in MHC class IIB in half-smooth tongue sole (Cynoglossus semilaevis) after challenge with vibrio anguillarum. Two thousand and four hundred fry from 12 half-smooth tongue sole families were challenged with Vibrio anguillarum. To determine any association between alleles and resistance or susceptibility to V. anguillarum, 160 individuals from four high-resistance (HR, < 40.55% mortality) families and four low-resistance (LR, > 73.27% mortality) families were selected for MHC IIB exon2 gene sequence analysis. The MHC IIB exon2 genes of tongue sole displayed a high level of polymorphism and were discovered at least four loci. Meanwhile, the dN/dS [the ratio of non-synonymous (dN) substitutions to synonymous (dS) substitutions] in the peptide-binding region (PBR) was higher than that in the non-peptide-binding region (non-PBR). Eighty-eight alleles were discovered among 160 individuals, and 13 out of 88 alleles were used to analyze the distribution pattern between the resistant and susceptible families. Certain alleles presented in HR and LR with a different frequency, while other alleles were discovered in only the HR or LR families, not both. Five alleles, Cyse-DBB*6501, Cyse-DBB*4002, Cyse-DBB*6102, Cyse-DBB*5601 and Cyse-DBB*2801, were found to be associated with susceptibility to V. anguillarum with a frequency of 1.25%, 1.25%, 1.25%, 1.25% and 2.5% in the HR families, and 35%, 33.75%, 27.5%, 16.25%, 15% in the LR families (p < 0.01, 0.01, 0.01, 0.01, 0.01), respectively. Four alleles, Cyse-DBB*3301, Cyse-DBB*4701, Cyse-DBB*6801 and Cyse-DBB*5901, were found to be associated with resistance to V. anguillarum, with a frequency of 13.75%, 11.25%, 11.25%, 8.75% in the HR families and 1.25%, 1.25%, 1.25%, 1.25% and 1.25% in the LR families (p < 0.01, 0.05, 0.05 and p = 0.064), respectively.ConclusionsElucidation of the role of MHC II B genes in half-smooth tongue sole should prove to be helpful to the in-depth development of marker-assisted selective breeding in half-smooth tongue sole.

Microsatellite-centromere mapping in Cynoglossus semilaevis using gynogenetic diploid families produced by the use of homologous and non-homologous sperm.

Twenty-one microsatellite markers were studied in three meiogynogenetic families of Cynoglossus semilaevis gunther for centromere mapping using half-tetrad analysis. Among the 13 mapped loci, 10 were estimated to be located in the telomeric region, one in the centromeric region, and two in the intermediate region of the chromosome. This study provides a basis for constructing a linkage map of C. semilaevis.

Isolation and characterization of 10 polymorphic microsatellite loci from small yellow croaker (Pseudosciaena polyactis)

Small yellow croaker (Pseudosciaena polyactis) is an economically important marine fish species. About 43 microsatellite loci were isolated from two enriched genomic library of Pseudosciaena polyactis. Ten of these loci were polymorphic in a test population with alleles per locus ranging from two to six, and observed and expected heterozygosities per locus from 0.3750 to 0.8750 and from 0.3112 to 0.8121, respectively. No loci significantly deviated from Hardy–Weinberg equilibrium after Bonferroni correction and no significant linkage disequilibrium was found between pairs of loci. These polymorphic microsatellite loci would be useful for investigating genetic diversity of Pseudosciaena polyactis.

Isolation and characterization of polymorphic microsatellite loci from black snapper Sebastodes fuscescens (Houttuyn)

Black snapper Sebastodes fuscescens (Houttuyn) is an economocally important species. Fourty-five microsatellite loci were isolated from an enriched genomic library of S. fuscescens. Ten of these loci were polymorphic in a test population with alleles per locus ranging from 2 to 5, and observed and expected heterozygosities per locus from 0.21 to 1.00 and from 0.19 to 0.86, respectively. Three loci significantly deviated from Hardy–Weinberg equilibrium after Bonferroni correction and no significant linkage disequilibrium was found between pairs of loci. These polymorphic microsatellite loci would be useful for investigating genetic diversity of S. fuscescens and other related species.