Yuying He

Cloning of a heat shock protein 90 (HSP90) gene and expression analysis in the ridgetail white prawn Exopalaemon carinicauda.

Heat shock protein 90 (HSP90) is a highly conserved molecular chaperone contributing to the folding, maintenance of structural integrity and proper regulation of a subset of cytosolic proteins. In this study, a heat shock protein 90 cDNA named EcHSP90 was cloned from the hepatopancreas of ridgetail white prawn Exopalaemon carinicauda by reverse transcription polymerase chain reaction (RT-PCR) coupled with rapid amplification of cDNA ends (RACE) approaches. The full-length cDNA of EcHSP90 was of 2695 bp, including an open reading frame (ORF) of 2163 bp encoding a polypeptide of 720 amino acids with an estimated molecular mass of 82.73 kDa and an estimated isoelectric point of 4.83. BLAST analysis revealed that the EcHSP90 shared high similarity (87.6%-75.24%) with other known HSP90s. The five conserved amino acid blocks defined as HSP90 protein family signatures were also identified in EcHSP90, which indicated that EcHSP90 should be a cytosolic member of the HSP90 family. Quantitative real-time RT-PCR analysis revealed that EcHSP90 transcript could be detected in all the tested tissues, and strongly expressed in ovary of E. carinicauda. The transcript of EcHSP90 in hepatopancreas of E. carinicauda showed different expression profiles after pH and ammonia-N stresses. The results indicated that EcHSP90 was a constitutive and inducible expressed protein and could be induced by various stresses from environment.

Analysis of DNA methylation in different tissues of Fenneropenaeus chinensis from the wild population and Huanghai No. 1

DNA methylation plays an important role in the regulation of gene expression during biological development and tissue differentiation in eukaryotes. A methylation sensitive amplification polymorphism (MSAP) including digestion, pre-selective amplification and selective amplification was optimized to compare the levels of DNA cytosine methylation at CCGG sites in muscle, gill and hemocyte from the wild populations and the selective breeding of Huanghai No. 1 of Fenneropenaeus chinensis, respectively. Significant differences in cytosine methylation levels among three tissues in two populations were detected. The average DNA methylation ratios in muscle, gill and hemocyte of the wild population were 23.1%, 22.3% and 19.7%, while those were 21.4%, 19.6%, and 18.9% in Huanghai No. 1, respectively. The DNA methylation levels of gill from the two populations were highly significant (P<0.01), the difference of muscle was significant (P<0.05), while in hemocyte, there were no significant differences (P>0.05). DNA polymorphic methylation of gill and hemocyte between the wild population and Huanghai No. 1 varies to some extent, while those of muscle kept in a balanced degree. Furthermore, polymorphic methylation was associated with demethylation and methylation of CCGG loci.

Expression profiles of the p38 MAPK signaling pathway from Chinese shrimp Fenneropenaeus chinensis in response to viral and bacterial infections

Mitogen-activated protein kinase (MAPK) signaling pathway plays an important role in cellular response to inflammatory cytokines, environmental stress and pathogenic infection, However, compared with mammals and insects, the potential function of p38 MAPK from Chinese shrimp (Fenneropenaeus chinensis) in response to viruses and bacterial infection is limited. In the study, the immune responses of four genes MKK3, MKK4, p38 and ATF-2 from F. chinensis were investigated in defending against white spot syndrome virus (WSSV), Vibrio anguillarum (V. anguillarum) and Staphylococcus aureus (S. aureus) infection. Results demonstrated that the expression levels of these four genes were apparently modulated in hemocytes and gills when shrimp were stimulated by WSSV or bacteria, particularly at 3-24h after infection. MKK3, p38 and ATF-2 were most sensitive to V. anguillarum (Gram-negative bacteria), followed by WSSV and S. aureus (Gram-positive bacteria), while MKK4 gene was most sensitive to S. aureus, followed by WSSV and V. anguillarum. Knockdown of Fcp38 by RNA interference (RNAi) resulted in a reduction in the expression of FcMKK3 and FcATF-2. The results indicate that p38MAPK signaling pathway plays a role in defending against viral and bacterial infections in F. chinensis.