| Follistatin is a single-chain glycoprotein that was first purified from mammalian ovarianfollicular fluid and characterized as a potent inhibitor of follicle stimulating hormone (FSH) dueto its high binding affinity to activin. Follistatin can not only antagonizes the action of activin,but also many other members of TGF-β superfamily, including myostatin, GDF-9and the bonemorphogenetic proteins (BMPs). By interfering with functions of these molecules, follistatin isinvolved in numerous physiological activities including reproduction, development, neuralinduction, osmoregulation, myogenesis and immunoregulation.As a gene encoding a multifunctional regulatory protein, follistatin is cloned andcharacterized in many species of higher vertebrates and found to be distributed in almost all thetissues. However, information such as molecular structure, expression and function of follistatinin fish is still limited. To better understand its functions in teleosts, the transcript abundance offollistatin in Larimichthys crocea (L. crocea) was measured at different development stages andin different gender. A fasting-refeeding protocol was also performed to correlate follistatin tissueexpression pattern with nutritional status in the juvenile stage of L. crocea.The results showed that follistatin transcripts were weakly detected before gastrula stage (9hpost-fertilization; hpf). Level of follistatin transcript at myogenesis stage (15hpf) and30days afterhatching (30dah) reached the peak and was higher than that at the fertilized egg stage (0hpf) by2-3orders of magnitude. In adult large yellow croaker, follistatin expression was detected in all theten tissues examined and most abundant in brain, muscle, gill, eye and intestine. The abundance offollistatin transcripts in most tissues was influenced by the age and gender. In the female largeyellow croaker of12months old, the highest level of follistatin mRNA was found in gill and thelowest in ovarium, expression of follistatin in gill was3orders of magnitude higher than that inovarium. In the male large yellow croaker of12months old, the highest level of follistatin mRNAwas found in gill and the lowest in spleen, expression of follistatin in gill was3orders ofmagnitude higher than that in spleen. In the female large yellow croaker of24months old, thehighest level of follistatin mRNA was found in inteatine and the lowest in heart, expression of follistatin in intestine was2orders of magnitude higher than that in heart. In the male large yellowcroaker of24months old, the highest level of follistatin mRNA was found in gill and the lowest inkidney, expression of follistatin in gill was2orders of magnitude higher than that in kidney. At thefasting and refeeding period, the regulatory response of follistatin in all the examined tissues of L.crocea varied greatly. In some tissues such as kidney, spleen, eye and intestine, expression level offollistatin changed distinctly. In kidney, follistatin expression was upregulated during fasting andrefeeding, the highest expression level was2orders of magnitude higher compared with controlgroup. In spleen, follistatin expression remained relatively stable during shor-term fasting and wasupregulated during long-term fasting and refeeding, the highest expression level was3orders ofmagnitude higher compared with control group. In eye, follistatin expression fluctuated drasticallyduring short-term fasting and remained relatively stable during long-term fasting and refeeding,the lowest expression level was3orders of magnitude lower compared with control group. Inintestine, follistatin expression was upregulated during fasting and downregulated to the controllevel during refeeding, the highest expression level was3orders of magnitude higher comparedwith control group. Altogether, these findings support the evidence that follistatin plays a profoundrole in the teleost development and that it is an indispensable factor for the survival of teleostswhen challenged with environmental stresses like fasting. |
PDF Full Text Request