Molecular cloning and characteristics analysis of Pmtgfbr1 from Pinctada fucata martensii

Cloning and Expression Analysis of TGF-β Type I Receptor Gene in Hyriopsis cumingii

The TGF-β signaling pathway plays an important role in wound healing and immune response. In this study, a TGF-β type I receptor (TGF-βRI) homolog was cloned and characterized from freshwater mussel Hyriopsis cumingii. The full-length cDNA of the TGF-β RI gene was 2017 bp, with a 1554 bp open reading frame (ORF), and encoded 517 amino acids. The predictive analysis further identified distinct regions within the TGF-βRI protein: a signal peptide, a membrane outer region, a transmembrane region, and an intracellular region. Real-time quantitative PCR results showed that the TGF-β RI gene was expressed in all tissues of healthy mussels. The transcripts of TGF-β RI in hemocytes and hepatopancreas were significantly up-regulated at different periods after stimulation with Aeromonas hydrophila and peptidoglycan (PGN) (P < 0.05). The mRNA expression of TGF-β RI progressively increased from day 1 to day 10 after trauma (P < 0.05), and it returned to the initial level by day 15. The expression levels of TGF-β , Smad5, MMP1/19, and TIMP1/2, but not Smad3/4, were significantly up-regulated at different time points after trauma. However, the expression levels of TGF-β , MMP1/19, and TIMP2 were decreased after treatment with the inhibitor SB431542. Furthermore, the recombinant TGF-βRI proteins were expressed in vitro and existed in the form of inclusion bodies. Western blotting results showed that TGF-βRI proteins were expressed constitutively in various tissues of mussels, and their expression was up-regulated after trauma, which was consistent with the mRNA expression trend. These results indicate that TGF-β RI is involved in the process of wound repair and immune response.

Molecular Cloning, Characterization, and Function of Insulin-Related Peptide 1 (IRP1) in the Haliotis discus hanna

Abalone is a popular mollusk in the marine aquaculture industry of China. However, existing challenges, like slow growth, individual miniaturization, and the absence of abundant abalone, have emerged as significant obstacles impeding its long-term progress in aquaculture. Studies have demonstrated that insulin-related peptide (IRP) is a crucial factor in the growth of marine organisms. However, limited studies have been conducted on IRP in abalone. This study indicated that the hdh-MIRP1 open reading frame (ORF) was composed of 456 base pairs, which encoded 151 amino acids. Based on the gene expression and immunofluorescence analyses, the cerebral ganglion of Haliotis discus hannai (H. discus hannai) was the primary site of hdh-MIRP1 mRNA expression. Moreover, hdh-MIRP1 expression was observed to be higher in the larger group than in the smaller group abalones. Only single nucleotide polymorphism (SNP) was related to their growth characteristics. However, approximately 82 proteins that may interact with hdh-MIRP1 were identified. The functional enrichment analysis of the 82 genes indicated that hdh-MIRP1 may be involved in the regulation of glucose metabolism and the process of growth. This study established a benchwork for further investigating the role of IRP in the growth of abalone.

Mantle Transcriptome Provides Insights into Biomineralization and Growth Regulation in the Eastern Oyster (Crassostrea virginica)

Growth of the eastern oyster Crassostrea virginica, a major aquaculture species in the USA, is highly variable and not well understood at molecular levels. As growth of mollusks is confined in shells constructed by the mantle, mantle transcriptomes of large (fast-growing) and small (slow-growing) eastern oysters were sequenced and compared in this study. Transcription was observed for 31,186 genes, among which 104 genes were differentially expressed between the large and small oysters, including 48 upregulated and 56 downregulated in large oysters. Differentially expressed genes (DEGs) included genes from diverse pathways highlighting the complexity of shell formation and growth regulations. Seventeen of the 48 upregulated DEGs were related to shell matrix formation, most of which were upregulated in large oysters, indicating that large oysters are more active in biomineralization and shell formation. Genomic and transcriptomic analyses identified 22 genes encoding novel polyalanine containing proteins (Pacps) with characteristic motifs for matrix function that are tandemly duplicated on one chromosome, all specifically expressed in mantle and at higher levels in large oysters, suggesting that these expanded Pacps play important roles in shell formation and growth. Analysis of sequence variation identified 244,964 SNPs with 328 associated with growth. This study provides novel candidate genes and markers for shell formation and growth, and suggests that genes related to shell formation are important for the complex regulation of growth in the eastern oyster and possibly other bivalve mollusks. Results of this study show that both transcriptional modulation and functional polymorphism are important in determining growth.