English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

20,6’-Hydroxysteroid dehydrogenase (2073-HSD) is a major enzyme involved in the gonadotropin-induced production of maturation-inducing hormone of oocytes, l70:,20,6-dihydroxy-4-pregnen-3-one (l7a,20,6’-diOHprog), by salmonid ovarian follicles. The present study was conducted to determine the effects of extracellular pH on gonadotropin-induced activation of 20,6-HSD using in virro incubation of isolated granulosa cell layers of rainbow trout, Salmo gairdneri, and amago salmon, Oncorhynclius rhodurus, at the late vitellogenic and the early migratory nucleus stages. 20,8-HSD activity was deduced by measuring levels of l7o:,20[5’-diOHprog derived from exogenous precursor 170:-hydroxyprogesterone (170:-OHprog) at various pH (6.5—8.5). Activity of 20,6’-HSD at both stages was dramatically enhanced by the addition of chum salmon gonadotropin (SGA), forskolin, or dibutyryl cAMP (dbcAMP) at higher pH (27.5). In contrast, the activation was suppressed by more than 60% at pH 7.0, and almost 100% at pH 6.5. A lower pH did not, however, influence the enzymatic conversion of 170:-OHprog to l7a,20fl-diOHprog in granulosa cell layers in which 20,6’-HSD had already been activated by pretreatment with SGA at pH 7.5. Even without SGA, a higher pH (28.0) itself partially activated 20,6’-HSD at the early migratory nucleus stage. The higher pH-induced 20,6’-HSD activation was totally inhibited by cycloheximide, a protein synthesis inhibitor. Granulosa cell layers showed no SGA-, forskolin-, or dbcAMP-induced 20,6’-HSD activation in sodium-deficient media. Amiloride, a Na+/H+ exchanger inhibitor, also blocked 20,6-HSD activation in a dose-dependent manner. These results suggest that fluctuations of intracellular pH play an important role in gonadotropin-induced 20,6HSD activation in granulosa cell layers of salmonid ovarian follicles. Oocyte maturation in teleosts is regulated by production in salmonid ovarian follicles are a follicular steroidal mediator, maturationthe stimulation of 17a-hydroxyprogesterone inducing steroid (MIS), under the control of (I70:-OHprog) production by thecal cell layers gonadotropin (7, 18). l7ci,20,B-Dihydroxy-4and the enhancement of the activity of 205pregnen-3-one (l7a,20,8-diOHprog) wasidenhydroxysteroid dehydrogenase (2046-HSD), tified as the natural MIS in amago salmon the key enzyme involved in the conversion of (19) The major roles of gonadotropin in MIS 17a-OHprog to l7a,20,6’-diOHprog, in granu-

biomedical research

&lt;b&gt;INVOLVEMENT OF pH IN THE ENHANCEMENT OF 20β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN ISOLATED GRANULOSA CELL LAYERS FROM OVARIAN FOLLICLES OF SALMONID &lt;/b&gt;&lt;b&gt;FISHES &lt;/b&gt;