Regulation of vitellogenin gene expression under the negative modulator, gonad-inhibiting hormone in Penaeus monodon

Eyestalk neuropeptide identification in the female red deep-sea crab, Chaceon quinquedens

Eyestalk-derived neuropeptides, primarily the crustacean hyperglycemic hormone (CHH) neuropeptide family, regulate vitellogenesis in decapod crustaceans. The red deep-sea crab, Chaceon quinquedens, a cold-water species inhabiting depths between 200 and 1800 m, has supported a small fishery, mainly harvesting adult males in the eastern US for over 40 years. This study aimed to understand the role of eyestalk-neuropeptides in vitellogenesis in C. quinquedens with an extended intermolt stage. Chromatography shows two CHH and one MIH peak in the sinus gland, with a CHH2 peak area four times larger than CHH1. The cDNA sequence of MIH and CHH of C. quinquedens is isolated from the eyestalk ganglia, and the qPCR assay shows MIH is significantly higher only at ovarian stages 3 than 4 and 5. However, MIH transcript and its neuropeptides do differ between stages 1 and 3. While CHH transcripts remain constant, its neuropeptide levels are higher at stages 3 than 1. Additionally, transcriptomic analysis of the de novo eyestalk ganglia assembly at ovarian stages 1 and 3 found 28 eyestalk neuropeptides. A GIH/VIH or GSH/VSH belonging to the CHH family is absent in the transcriptome. Transcripts per million (TPM) values of ten neuropeptides increase by 1.3 to 2.0-fold at stage 3 compared to stage 1: twofold for Bursicon α, followed by CHH, AKH/corazonin-like, Pyrokinin, CCAP, Glycoprotein B, PDH1, and IDLSRF-like peptide, and 1.3-fold of allatostatin A and short NP-F. WXXXRamide, the only downregulated neuropeptide, decreases TPM by ∼ 2-fold at stage 3, compared to stage 1. Interestingly, neuroparsin with the highest TPM values remains the same in stages 1 and 3. The mandibular organ-inhibiting hormone is not found in de novo assembly. We report that CHH, MIH, and eight other neuropeptides may play a role in vitellogenesis in this species.

Cloning, functional and regulation analysis of a novel male reproduction-related protein gene from the oriental river prawn Macrobrachium nipponense

Gonadogenesis processes in crustaceans are complex. There, however, has been a large amount of research focused on regulation of female gonad (ovary) development in crustaceans, however, there has been little focus on the male gonad (testis). In the current study, a novel male reproduction-related protein gene (Mn-MRP) was identified from Macrobrachium nipponense. The relative abundance of Mn-MRP mRNA transcript in tissues and at different developmental stages were investigated. The relative abundance of Mn-MRP mRNA transcript was larger in the testis than other tissues, and during the testis maturation stage than at other developmental stages, suggesting Mn-MRP may have important functions in reproduction processes. The RNA interference (RNAi) was used to further investigate the Mn-MRP biological function. Silencing of the Mn-MRP gene effectively decreased the abundance of the sperm gelatinase (Mn-SG) mRNA transcript, implying the protein encoded by this gene may have functions in sperm activity during the fertilization process. Further studies with RNAi and eyestalk ablation confirmed that gonad inhibiting hormone gene (Mn-GIH) is a negative regulator of Mn-MRP, and that the insulin-like androgenic gland hormone gene (Mn-IAG) is a positive regulator. There, therefore, was cloning of the Mn-MRP gene, and investigation of its potential biological function, as well as elucidation of the positive/negative regulators in current study. The results from this study provide for a greater understanding of regulatory mechanisms of male reproduction in crustaceans.