Jost Wolfgang, Yu Yan, Pick Leslie, Preiss Anette, Maier Dieter
Biozentrum der Universität Basel, Abt. Zellbiologie, Klingelbergstraße 70, CH-4056, Basel, Switzerland.
Bookdale Center for Molecular Biology, Mount Sinai School of Medicine, One Gustave L. Levy Place, BOX 1126, 10029, New York, NY, USA.
Rouxs Arch Dev Biol. 1995 Nov;205(3-4):160-170. doi: 10.1007/BF00357762.
The Drosophila melanogaster segmentation gene fushi tarazu (ftz) encodes a homeodomain-type transcription factor involved in the control of larval pattern formation. Loss of function mutations cause an embryonic lethal, pair-rule phenotype. The segmentation defects, but not the lethality, can be partially rescued by the ftz orthologue from Drosophila hydei. In this work, the primary structure, expression and regulation of the D. hydei ftz gene was characterized. Sequence comparisons classify ftz as a rather fast evolving gene. However, since the homeodomain of the D. hydei FTZ protein is highly similar to that of D. melanogaster, proper regulation of D. melanogaster ftz downstream genes would be expected. In D. melanogaster embryos, a D. hydei ftz transgene is expressed normally, independent of endogenous ftz gene activity, suggesting that D. hydei ftz regulatory sequences are correctly recognized by D. melanogaster transcription factors. Accordingly, lacZ fusion constructs driven by the D. hydei ftz upstream element are expressed normally in D. melanogaster embryos. Altogether, the similarities between the two ftz orthologues by far outweigh the differences. The limited success of the trans-species rescue might be, therefore, a consequence of the accumulation of too many subtle changes in gene function, exceeding the limits of developmental plasticity during fly embryogenesis.
果蝇的分节基因腹节缺失（ftz）编码一种同源异型域型转录因子，参与幼虫模式形成的调控。功能丧失突变会导致胚胎致死的成对规则表型。分节缺陷而非致死性，可以通过果蝇海德氏种的ftz直系同源基因得到部分挽救。在这项研究中，对果蝇海德氏种ftz基因的一级结构、表达和调控进行了表征。序列比较将ftz归类为一个进化相当快的基因。然而，由于果蝇海德氏种FTZ蛋白的同源异型域与果蝇黑腹种的高度相似，预计果蝇黑腹种ftz下游基因会得到适当调控。在果蝇黑腹种胚胎中，一个果蝇海德氏种ftz转基因正常表达，独立于内源性ftz基因活性，这表明果蝇海德氏种ftz调控序列能被果蝇黑腹种转录因子正确识别。因此，由果蝇海德氏种ftz上游元件驱动的lacZ融合构建体在果蝇黑腹种胚胎中正常表达。总之，这两个ftz直系同源基因之间的相似性远远超过差异。因此，跨物种挽救的有限成功可能是基因功能中积累了太多细微变化的结果，这些变化超出了果蝇胚胎发育过程中发育可塑性的极限。
