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Chen Y.,Xiamen University | Hong W.S.,Xiamen University | Hong W.S.,Fujian Collaborative Innovation Center | Wang Q.,Xiamen University | And 2 more authors.
Animal Reproduction Science | Year: 2016

Gonadal soma-derived factor (gsdf) is a teleost- and gonad-specific growth factor involved in early germ cell development. The red spotted grouper, Epinephelus akaara, as a protogynous hermaphrodite, provides a novel model for understanding the mechanisms of sex determination and differentiation in teleosts. In the present study, a 2307-bp long gsdf gene was cloned from E. akaara and there was further analysis of its tissue distribution and gonadal patterns of gene expression during the female phase and sex change developmental stages. The cellular localization of gsdf at the late transitional developmental stage was also analyzed. In addition, the concentrations of serum sex steroid hormones (E2, 11-KT and DHP) were determined. The gsdf transcripts were exclusively localized in the gonad. During the female phase at an early developmental stage, when the ovotestis contained mainly oogonia and primary growth oocytes, the gsdf mRNA was relatively more abundant. The relative abundance of gsdf decreased, however, and the lesser amount was sustained with the advancement of oocyte development. During the transitional phase, the relative abundance of gsdf mRNA increased slightly at the early developmental stage and there were further increases in relative abundance in the late developmental stage, and the gsdf transcripts were observed in the Sertoli cells surrounding early developing spermatogonia. Among the sex steroids, 11-KT concentrations were positively correlated with amount of gsdf mRNA during sex change. These results suggest that gsdf could have roles in regulating pre-meiotic germ cell proliferation and be involved in sex change in E. akaara. © 2015 Elsevier B.V.

Xu C.,Jimei University | Wang C.,Jimei University | Cai Q.-F.,Jimei University | Cai Q.-F.,Fujian Collaborative Innovation Center | And 10 more authors.
Journal of Agricultural and Food Chemistry | Year: 2015

Matrix metalloproteinases (MMPs) are proposed to play important roles in the degradation of collagens, thus causing the post-mortem softening of fish muscle, although the specific mechanism remains largely unresolved. Previously, we reported the existence of gelatinase-like proteinases in common carp (Cyprinus carpio) muscle. The primary structures of these proteinases, however, have never been investigated. In the present study, two MMPs with molecular masses of 66 and 65 kDa were purified to homogeneity from common carp muscle by ammonium sulfate fractionation and a series of column chromatographies. Matrix-assisted laser desorption/ionization-tandem time-of-flight mass spectrometry (MALDI-TOF/TOF-MS/MS) analysis indicated that they are completely identical to MMP-2 from common carp. During chilled storage of common carp at 4 °C, the enzymatic activity of MMP-2 increased to 212% in 12 h while the texture profile increased over the first 2 h and gradually decreased. On the other hand, type V collagen was purified to homogeneity and a specific polyclonal antibody against this protein was prepared. Both type I and V collagens were effectively hydrolyzed by MMP-2 at 30 °C and even at 4 °C. Furthermore, injection of metalloproteinase proteinase inhibitor EDTA into the blood vessel of live common carp suppressed post-mortem tenderization significantly. All of these results confirmed that MMP-2 is a major proteinase responsible for the degradation of collagens, resulting in the softening of fish muscle during chilled storage. © 2015 American Chemical Society.

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