Williams J L, Bownes M
Eur J Biochem. 1986 Nov 17;161(1):95-101. doi: 10.1111/j.1432-1033.1986.tb10128.x.
In Drosophila three yolk polypeptides (YP1, YP2 and YP3) are synthesized at two sites in the adult female: in the fat body tissue, from which they are transported via the haemolymph to the ovary, and in the ovarian follicle cells which surround the developing oocytes. All three yolk polypeptides are synthesized at equal levels in the fat body. In this paper we show that the steady-state level of YP3 RNA is significantly reduced in the ovary in comparison with the fat body, and that none of the yolk protein genes is amplified either in the fat body or the follicle cells. In order to determine the basis of the reduced level of YP3 RNA in the ovary, which could result from a lower rate of transcription or through a decreased stability of the RNA, we have devised an in vivo method of determining relative rates of gene transcription. In both the fat body and the ovary all three yolk proteins are transcribed at similar rates. Thus we infer that YP3 RNA is destabilised in the ovary, accounting for the reduction in its steady-state level.
在果蝇中，三种卵黄多肽（YP1、YP2和YP3）在成年雌性体内的两个部位合成：在脂肪体组织中，它们通过血淋巴运输到卵巢；在围绕发育中卵母细胞的卵巢滤泡细胞中。所有三种卵黄多肽在脂肪体中的合成水平相等。在本文中，我们表明，与脂肪体相比，卵巢中YP3 RNA的稳态水平显著降低，并且卵黄蛋白基因在脂肪体或滤泡细胞中均未扩增。为了确定卵巢中YP3 RNA水平降低的原因，这可能是由于转录速率较低或RNA稳定性降低所致，我们设计了一种体内方法来确定基因转录的相对速率。在脂肪体和卵巢中，所有三种卵黄蛋白的转录速率相似。因此，我们推断YP3 RNA在卵巢中不稳定，这解释了其稳态水平的降低。
