BACKGROUND Drosophila subobscura exhibits a rich inversion polymorphism, with some adaptive inversions showing repeatable spatiotemporal patterns in frequencies related to temperature. Previous studies reported increased basal HSP70 protein levels in homokaryotypic strains for a warm-climate arrangement compared to a cold-climate one. These findings do not match the similar hsp70 genomic organization between arrangements, where gene expression levels are expected to be similar. In order to test this hypothesis and understand the molecular basis for hsp70 expression, we compared basal hsp70 mRNA levels in males and females, and analysed the 5' and 3' regulatory regions of hsp70 genes in warm- and cold-climate isochromosomal O3 + 4 + 7 and OST lines of D. subobscura. RESULTS We observed comparable mRNA levels between the two arrangements and a sex-biased hsp70 gene expression. The number of heat-shock elements (HSEs) and GAGA sites on the promoters were identical amongst the OST and O3 + 4 + 7 lines analysed. This is also true for 3' AU-rich elements where most A and B copies of hsp70 have, respectively, two and one element in both arrangements. Beyond the regulatory elements, the only notable difference between both arrangements is the presence in 3' UTR of a 14 bp additional fragment after the stop codon in the hsp70A copy in five O3 + 4 + 7 lines, which was not found in any of the six OST lines. CONCLUSIONS The equivalent hsp70 mRNA amounts in OST and O3 + 4 + 7 arrangements provide the first evidence of a parallelism between gene expression and genetic organization in D. subobscura lines having these arrangements. This is reinforced by the lack of important differential features in the number and structure of regulatory elements between both arrangements, despite the genetic differentiation observed when the complete 5' and 3' regulatory regions were considered. Therefore, the basal levels of hsp70 mRNA cannot account, in principle, for the adaptive variation of the two arrangements studied. Consequently, further studies are necessary to understand the intricate molecular mechanisms of hsp70 gene regulation in D. subobscura.

中文翻译：

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基础hsp70表达水平不能解释果蝇亚果蝇的O3 + 4 + 7和OST基因排列的适应性变化。

背景技术果蝇亚黑斑病（Drosophila subobscura）表现出丰富的反转多态性，其中一些适应性反转在与温度有关的频率上显示出可重复的时空模式。先前的研究报道，与冷气候相比，同核型菌株中基础HSP70蛋白水平升高。这些发现与安排之间的相似的hsp70基因组组织不匹配，在这些地方预期基因表达水平是相似的。为了检验该假设并了解hsp70表达的分子基础，我们比较了男性和女性的基础hsp70 mRNA水平，并分析了冷热和等温O3 + 4染色体中hsp70基因的5'和3'调控区。 + 7和OST线的D. subobscura 结果我们观察到两种安排之间的可比的mRNA水平和性别偏向的hsp70基因表达。在分析的OST和O3 + 4 + 7品系中，启动子上的热休克元件（HSE）和GAGA位点的数量相同。对于富含3'AU的元件也是如此，其中大多数hsp70的A和B拷贝在两种排列中分别具有两个和一个元件。除调控元件外，这两种排列之间的唯一显着区别是，在5个O3 + 4 + 7行中，hsp70A拷贝的终止密码子后在3'UTR中存在一个14 bp的额外片段。六个OST线。结论OST和O3 + 4 + 7排列中等效的hsp70 mRNA量为D中基因表达与遗传组织之间的平行性提供了第一个证据。具有这些布置的近暗线。尽管在考虑完整的5'和3'调控区时观察到遗传分化，但由于两种排列之间的调控元件在数量和结构上缺乏重要的差异性特征，这一点得到了加强。因此，原则上，hsp70 mRNA的基础水平不能解释所研究的两种排列的适应性变异。因此，进一步的研究是必要的，以了解隐孢子虫中hsp70基因调控的复杂分子机制。因此，hsp70 mRNA的基础水平原则上不能解释所研究的两种排列的适应性变异。因此，进一步的研究是必要的，以了解隐孢子虫中hsp70基因调控的复杂分子机制。因此，hsp70 mRNA的基础水平原则上不能解释所研究的两种排列的适应性变异。因此，进一步的研究是必要的，以了解隐孢子虫中hsp70基因调控的复杂分子机制。