Molecular cloning and characterization of a novel Y-box gene from Sepiella maindroni.

Y-box proteins are a family of highly conserved nucleic acid binding proteins that interact with genome and transcription product to modulate the transcriptional and translational processes. In the present study, a complete mRNA of Y-box binding protein (designated SmYB) was obtained from Sepiella maindroni by amplification of flanking sequences. The full size of SmYB cDNA was 1502 bp, including 99 bp at the 5ꞌ untranslated region (UTR), a 3ꞌ UTR of 821 bp with a poly (A) tail, and an open reading frame of 582 bp, encoding a polypeptide of 193 amino acids with the predicted molecular weight of 16.48 kDa. The conserved cold-shock domain and two known RNA binding motifs identified in SmYB strongly suggested that SmYB was a new member of Y-box proteins. Quantitative real-time PCR was performed to examine the expression of SmYB mRNA in various tissues, embryos, and its temporal expression in liver after cold shock. The mRNA transcript of SmYB was detected in all examined tissues, with the highest expression level in testis and ovary. SmYB was abundant in early developmental stages of S. maindroni embryos but diminished in the late post-embryonic development. In addition, cold-shock treatment upregulated the transcription of SmYB mRNA in liver. These results demonstrated that SmYB is involved in embryonic development of S. maindroni and its tolerance to acute low temperatures.

Screening of genes related to ovarian development in the swimming crab, Portunus trituberculatus, by suppression subtractive hybridization.

The swimming crab, Portunus trituberculatus, is an important marine animal and is widely cultured in China. In the present study, suppression subtractive hybridization was applied to identify the differentially expressed genes in the ovaries of mature and immature P. trituberculatus. One hundred and seventy six expressed sequence tag (ESTs) were identified, of which 100 were down-regulated, and 76 up-regulated. BLAST analysis identified 51 unigenes, of which 27 were down-regulated, and 24 up-regulated. Quantitative real-time reverse transcriptase polymerase chain reaction results indicated that the SSH technique is valuable in screening genes related to ovarian development. Genes identified in this study encoded proteins corresponding to a wide range of functions and included immune response protein, transcription initiation factor, metabolic proteins, chromosome, histone h3, ovarian development-related protein, and vitellogenin. In addition, 64 metabolic pathways were annotated in differentially expressed ESTs by using the Kyoto Encyclopedia of Genes and Genomes pathway. Four annotated pathways (oxidative phosphorylation, carbon metabolism, fatty acid degradation, and protein digestion and absorption) appeared to be involved in ovarian development. In ontology analysis, 5.83% of the cellular process genes in reverse subtraction cDNA library are involved in reproduction, and 5.88% involved in developmental process. In up-regulated genes, myosin II-expressed polehole-like protein; histone h3; ovigerous-hair stripping substance; peritrophin 48; and ovarian development-related protein appeared to be involved in ovarian development. Identification of differentially expressed genes in the mature and immature ovary of the swimming crab provides new insights for further studies on the mechanism underlying ovarian development in this species.

mRNA expression profiles of heat shock proteins of wild and salinity-tolerant swimming crabs, Portunus trituberculatus, subjected to low salinity stress.

Challenged by the low salinity, 4 parts per thousand (4 ppt), for 72h, the survivals of swimming crabs (Portunus trituberculatus) were collected as the screened group (SG, tolerant to low salinity). Aiming at identifying the mechanism of low salinity tolerance, quantitative real-time PCR was employed to investigate the expression profiles of 4 HSP genes (HSP60, HSP70, HSP90-1, HSP90-2) in the hepatopancreas of wild (WG) and screened (SG) groups of P. trituberculatus exposed to low salinity (4 ppt). The results showed that 3 of the candidate genes (HSP60, HSP70, HSP90-1) exhibited similarly downregulated expression profiles in the first 3 h (P < 0.05), which became upregulated from 3 h to 72 h after being subjected to low salinity conditions. In contrast, the expression profile of the HSP90-2 gene was upregulated during the first 6 h for the WG, and during the first 12 h for the SG, after which it became downregulated. HSP90-1 and HSP90-2 were highly expressed at 12 h after low salinity challenge in the SG, but not the WG. The response of these 2 genes to salinity stress indicates their suitability as biomarkers to differentiate SG from WG crabs. The results indicate that HSP genes are involved in the adaptation of crabs to low salinity exposure, and that different HSPs have diverse functions in response to low salinity stress in P. trituberculatus. In addition, HSP expression in SG indicates that this group is more tolerant to low salinity conditions compared to WG.

Development of polymorphic expressed sequence tag-single sequence repeat markers in the common Chinese cuttlefish, Sepiella maindroni.

The common Chinese cuttlefish (Sepiella maindroni) is one of the popular edible cephalopod consumed across Asia. To facilitate the population genetic investigation of this species, we developed fourteen polymorphic microsatellite makers from expressed sequence tags of S. maindroni. The number of alleles at each locus ranged from 6 to 10 with an average of 7.9 alleles per locus. The ranges of observed and expected heterozygosity were from 0.615 to 0.962 and 0.685 to 0.888, respectively. Four loci were found deviated significantly from Hardy-Weinberg equilibrium. The polymorphism information content ranged from 0.638 to 0.833. These polymorphic microsatellite loci will be helpful for the population genetic, genetic linkage map, and other genetic studies of S. maindroni.