4 research outputs found

    Long-Term Potentiation of Exocytosis and Cell Membrane Repair in Fibroblasts

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    We previously found that a microdisruption of the plasma membrane evokes Ca(2+)-regulated exocytosis near the wound site, which is essential for membrane resealing. We demonstrate herein that repeated membrane disruption reveals long-term potentiation of Ca(2+)-regulated exocytosis in 3T3 fibroblasts, which is closely correlated with faster membrane resealing rates. This potentiation of exocytosis is cAMP-dependent protein kinase A dependent in the early stages (minutes), in the intermediate term (hours) requires protein synthesis, and for long term (24 h) depends on the activation of cAMP response element-binding protein (CREB). We were able to demonstrate that wounding cells activated CREB within 3.5 h. In all three phases, the increase in the amount of exocytosis was correlated with an increase in the rate of membrane resealing. However, a brief treatment with forskolin, which is effective for short-term potentiation and which could also activate CREB, was not sufficient to induce long-term potentiation of resealing. These results imply that long-term potentiation by CREB required activation by another, cAMP-independent pathway

    Sex-change and gonadal steroids in sequentially-hermaphroditic teleost fish

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    Sex-change is an intriguing phenomenon that is common among certain groups of teleost fishes. The process itself has a number of independent origins, although in each case it is initiated and (or) regulated by gonadal steroids. Despite the commercial importance of sex-change technology to fish culturists, our understanding of the relationship between steroids and sex-change is, at best, rudimentary. In this paper I review the current state of knowledge concerning (a) which steroids are involved, (b) how such steroids mediate sex-change, and (c) how steroidogenesis is regulated during gonadal transition. I conclude that the steroidal endocrinology of sex-change is multifarious and species specific – a result which challenges the relative stability of vertebrate endocrine axes, but one which probably reflects the independent evolution of this adaptation
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