Shechter Asaf, Aflalo Eliahu D, Davis Claytus, Sagi Amir
Departments of Life Sciences, Faculty of Health Sciences, Ben-Gurion, University of the Negev, Beer-Sheva, Israel.
Biol Reprod. 2005 Jul;73(1):72-9. doi: 10.1095/biolreprod.104.038554. Epub 2005 Mar 2.
In oviparous females, the synthesis of the yolk precursor vitellogenin is an important step in ovarian maturation and oocyte development. In decapod Crustacea, including the red-claw crayfish (Cherax quadricarinatus), this reproductive process is regulated by inhibitory neurohormones secreted by the endocrine X-organ-sinus gland (XO-SG) complex. In males, the C. quadricarinatus vitellogenin gene (CqVg), although present, is not expressed under normal conditions. We show here that endocrine manipulation by removal of the XO-SG complex from male animals induced CqVg transcription. The CqVg gene was expressed differentially during the molt cycle in these induced males: no expression was seen in the intermolt stages, but expression was occasionally detected in the premolt stages and always detected in the early postmolt stages. Relative quantitation with a real-time reverse transcriptase-polymerase chain reaction showed that expression of CqVg in induced early postmolt males was an order of magnitude lower than that in reproductive females, a finding that was consistent with RNA in situ hybridization results. The SDS-PAGE of high-density lipoproteins from the hemolymph of endocrinologically induced early postmolt males did not show the typical vitellogenin-related polypeptide profile found in reproductive females. On the other hand, removal of the XO-SG complex from intersex individuals, which are chromosomally female but functionally male and possess an arrested female reproductive system, induced the expression, translation, and release of CqVg products into the hemolymph, as was the case for vitellogenic females. The expression of CqVg in endocrinologically manipulated molting males and intersex animals provides an inducible model for the investigation and understanding of the endocrine regulation of CqVg expression and translation in Crustacea as well as the relationship between the endocrine axes regulating molt and reproduction.
在卵生雌性动物中，卵黄前体卵黄蛋白原的合成是卵巢成熟和卵母细胞发育的重要步骤。在包括红螯螯虾（Cherax quadricarinatus）在内的十足目甲壳动物中，这种生殖过程受内分泌X器官 - 窦腺（XO - SG）复合体分泌的抑制性神经激素调节。在雄性中，红螯螯虾卵黄蛋白原基因（CqVg）虽然存在，但在正常条件下不表达。我们在此表明，通过从雄性动物中去除XO - SG复合体进行内分泌操纵可诱导CqVg转录。在这些诱导的雄性动物的蜕皮周期中，CqVg基因表达存在差异：在蜕皮间期未见表达，但在蜕皮前期偶尔检测到表达，且在蜕皮后早期总是能检测到表达。实时逆转录 - 聚合酶链反应的相对定量显示，诱导的蜕皮后早期雄性中CqVg的表达比生殖雌性低一个数量级，这一发现与RNA原位杂交结果一致。对内分泌诱导的蜕皮后早期雄性血淋巴中的高密度脂蛋白进行SDS - PAGE分析，未显示出生殖雌性中典型的与卵黄蛋白原相关的多肽谱。另一方面，从间性个体（染色体为雌性但功能为雄性且具有停滞的雌性生殖系统）中去除XO - SG复合体，会诱导CqVg产物的表达、翻译并释放到血淋巴中，就像卵黄发生期雌性那样。CqVg在经内分泌操纵的蜕皮雄性和间性动物中的表达为研究和理解甲壳动物中CqVg表达和翻译的内分泌调节以及调节蜕皮和生殖的内分泌轴之间的关系提供了一个可诱导的模型。
