Jowett T, Rizki T M, Rizki R M
Dev Biol. 1986 Jul;116(1):23-30. doi: 10.1016/0012-1606(86)90039-4.
The larval serum proteins, LSP1 and LSP2, of Drosophila melanogaster are synthesized by the fat body during the third instar. We examined the potential for LSP synthesis by fat body implants in adult flies. Fat body from third instar donors will continue to synthesize LSPs in both males and females. Implants from late second instar larvae will start synthesizing LSP1 and LSP2 in females but only LSP1 in males, suggesting that regulation of these proteins is not the same and that the physiological milieu in the two sexes differs. The newly synthesized LSPs are secreted into the hemolymph for approximately 48 hr when secretion stops but synthesis continues. This sequence follows the pattern for LSP secretion in situ. Fat body from mid second instar larvae is variable in its ability to synthesize LSPs. LSPs are not detected in implants from first instar larvae despite there being a high level of protein synthesis in the implant and considerable growth of the fat body cells. We conclude that there is a critical stage of differentiation during the latter half of the second instar when the fat body becomes independent of the larval milieu and can synthesize LSPs in the adult.
黑腹果蝇的幼虫血清蛋白LSP1和LSP2是在三龄幼虫期由脂肪体合成的。我们研究了成年果蝇中脂肪体植入物合成LSP的潜力。来自三龄幼虫供体的脂肪体在雄性和雌性果蝇中都会继续合成LSP。来自二龄晚期幼虫的植入物在雌性中会开始合成LSP1和LSP2，但在雄性中只会合成LSP1，这表明这些蛋白质的调控方式不同，且两性的生理环境也有所差异。新合成的LSP会分泌到血淋巴中约48小时，之后分泌停止但合成继续。这个顺序与原位LSP分泌模式一致。来自二龄中期幼虫的脂肪体合成LSP的能力各不相同。尽管植入物中有高水平的蛋白质合成且脂肪体细胞有显著生长，但在一龄幼虫的植入物中未检测到LSP。我们得出结论，在二龄幼虫后半期存在一个关键的分化阶段，此时脂肪体变得独立于幼虫环境，并且能够在成虫中合成LSP。
