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Abstract: Regulation of ovarian steroidogenesis in vitro by recombinant human insulin-like growth factor-I (IGF-I) and bovine insulin (b-insulin) was investigated in intact follicles and isolated follicular cells of carp, Cyprinus carpio at vitellogenic stage of oocyte maturation. In intact follicles, IGF-I and b-insulin stimulated testosterone and 17β-estradiol production in vitro. In isolated theca cells, IGF-I and b-insulin stimulated testosterone production, whereas in granulosa cells, they stimulated 17β-estradiol production when testosterone was added in the incubation medium as precursor substrate. In intact follicles and in theca cells, IGF-I and b-insulin had no effect on HCG-stimulated testosterone production. HCG-stimulated 17β-estradiol production, however, was significantly increased by IGF-I and b-insulin. To clarify the mechanism of 17β-estradiol production by the ovarian follicles during vitellogenic stage of carp, effects of IGF-I and b-insulin either alone or in combination with HCG on aromatase activity (conversion of testosterone to 17β-estradiol) and cytochrome P450 aromatase (P450arom) gene expression were investigated in vitro. IGF-I and b-insulin alone stimulated aromatase activity and P450arom gene expression and significantly enhanced HCG-induced enzyme activity and P450arom gene expression. Our results thus indicate that IGF-I and b-insulin alone can stimulate testosterone and 17β-estradiol production in vitellogenic follicles of C. carpio by stimulating aromatase activity and P450arom gene expression. Evidence also provided for the modulation of HCG-induced aromatase activity and P450arom gene expression by IGF-I and b-insulin in such follicles. [Copyright &y& Elsevier]

Abstract: Previously, we observed that in vitro germinal vesicle breakdown (GVBD) in Cyprinus carpio oocytes was induced by recombinant human insulin-like growth factor-I (IGF-I) and bovine insulin (b-insulin) and this induction was steroid-independent. To investigate further the early signal transduction components involved in this process, the possible role of phosphatidylinositol 3-kinase (PI3 kinase) during oocyte maturation was examined. IGF-I- and b-insulin-induced oocyte maturation was significantly inhibited by Wortmannin and LY294002, two mechanistically different specific inhibitors of PI3 kinase. IGF-I and b-insulin were shown to activate PI3 kinase after 90min of their treatment. Both IGF-I and b-insulin were found to activate cdc2 kinase at 21h of treatment. We examined the relative involvement of PI3 kinase, MAP kinase and cdc2 kinase in IGF-I- and b-insulin-induced oocyte maturation in C. carpio. MAP kinase was rapidly phosphorylated and activated (30–150min) in response to exposure of the oocytes with IGF-I and b-insulin. This response preceded the phosphorylation and activation of cdc2 by several hours (almost 19h). A potent and selective inhibitor of MEK, PD98059, the protein kinase that phosphorylates and activate MAP kinase, blocked the phosphorylation and activation of MAP kinase and cdc2 kinase and GVBD induction. Likewise, PI3 kinase inhibitors strongly inhibited phosphorylation and activation of MAP kinase, which was increased during oocyte maturation. Taken together, these results suggest that PI3 kinase is an initial component of the signal transduction pathway which precedes MAP kinase, and MPF activation during IGF-I- and b-insulin-induced oocyte maturation in C. carpio. [Copyright &y& Elsevier]

• Shifting cultivation based livelihoods in Northeast India are hardly sustainable. • Sustainability of such livelihood options vary significantly across Northeastern states. • Social and financial capitals are pivotal to shifting cultivation based sustainable livelihood. • Livelihood diversification, market access and extension services enhance sustainability. Rural livelihood has long been discussed in scientific literature, although livelihood sustainability of fringe communities in far-flung and disadvantageous areas is very scarcely researched. Jhumias of the hilly and remote Northeastern (NE) region of India represent such a fringe community which is dependent upon shifting cultivation and forest resources for livelihood. The present study examines livelihood sustainability of these underprivileged forest peasants within the scope of sustainable livelihood framework. An indicator based approach helped in developing a composite measure, called the sustainable livelihood index (SLI) which gives a fair idea about the extent of livelihood sustainability of the shifting cultivator households in the study area. The study was carried out with randomly drawn six hundred and twenty one shifting cultivator households (n = 621) from the 'seven sister' states of NE India, namely Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland and Tripura. The findings of the study brings into light an immense vulnerable picture of shifting cultivation based livelihood in the region. Except for Mizoram, the other states had a minimum of 39.22 percent (in Manipur) and up to as high as 86.67 percent (in Assam) shifting cultivator households belonging to the very bottom stratum of livelihood sustainability. Social and financial capitals were the most important to bring sustainability in the livelihoods of shifting cultivators. The study specifically highlights the importance of livelihood diversification, improving market access and strengthening extension contacts for livelihood sustainability of these ethnic groups of peasants. In light of the findings, we suggest some policy measures within the scope of prevailing socio-cultural beliefs of the shifting cultivators for sustainable livelihood, environmental conservation and harmonic co-existence. [ABSTRACT FROM AUTHOR]

Highlights: [•] In vitro oocyte maturation (OM) in Tenualosa ilisha was induced by 17,20β-P. [•] 17,20β-P induction of OM was dose- and time-dependent. [•] PI3 kinase shown to be the initial signal molecule for 17,20β-P induced OM. [•] MAP kinase although was activated during 17,20β-P induced OM. [•] MAP kinase activation is not involved in induction of OM. [ABSTRACT FROM AUTHOR]

Abstract: In vitro germinal vesicle breakdown (GVBD) in Cyprinus carpio oocytes was induced by recombinant human insulin-like growth factor-I and -II (IGF-I and IGF-II) and bovine insulin (b-insulin). Treatment of postvitellogenic ovarian follicles with IGF-I and b-insulin increased concentration of maturation-inducing hormone (MIH), 17α,20β-dihydroxy-4-pregnane-3-one (DHP) in the medium. IGF-I and IGF-II both and b-insulin induced GVBD in denuded oocytes. IGF-I analogue R3 IGF-I was more potent than IGF-I in inducing GVBD of postvitellogenic follicles suggesting that ovarian IGF binding proteins may inhibit IGF-I action. Vitellogenic follicles, which were immature for oocytes to complete GVBD in response to DHP or HCG, underwent GVBD by IGF-I, not by b-insulin. IGF-I was also able to stimulate DHP production in such follicles. Addition of DHP and HCG to the culture of vitellogenic follicles containing IGF-I or b-insulin did neither potentiate the stimulation of GVBD induced by IGF-I nor initiate the same in response to b-insulin. Incubation of postvitellogenic follicles with trilostane (3β-HSD inhibitor) had no inhibitory effects on IGF-I- and b-insulin-induced GVBD but attenuated the same under HCG stimulation. Trilostane, however, strongly inhibited DHP production induced by all these effectors. Induction of GVBD by IGF-I and b-insulin was not altered in the presence of actinomycin D. However, it significantly blocked the HCG-induced GVBD. Cycloheximide was shown to inhibit the induction of GVBD and DHP production by IGF-I, b-insulin and HCG. Both actinomycin D and cycloheximide were found to inhibit DHP production stimulated by all the three effectors. Collectively, these observations indicate that IGF-I and b-insulin can induce GVBD via MIH- and transcription-independent pathway. Incubation of the follicles with gap junction uncouplers, 1-heptanol or 1-octanol, had no effect on IGF-I- and b-insulin-induced GVBD, but attenuated the same induced by HCG. These uncouplers, however, inhibited DHP production induced by IGF-I, b-insulin and HCG. This result suggests that both IGF-I and b-insulin can induce oocyte maturation without coupled gap junction between oocytes and granulosa cells, while homologous gap junctions are required for DHP production. Inhibitors of phosphatidylinositol-3 kinase (PI-3 kinase), wortmannin and LY294002 inhibited GVBD by IGF-I and b-insulin. These two inhibitors also attenuated HCG-induced GVBD. These data suggest that PI-3 kinase activity is required for IGF-I, b-insulin and HCG induction of GVBD in C. carpio. [Copyright &y& Elsevier]