Centre of Excellence in Evolutionary Research, Department of Biological and Environmental Science, P.O. Box 35, 40014 University of Jyväskylä, Finland.
BMC Ecol. 2010 Feb 1;10:3. doi: 10.1186/1472-6785-10-3.
Insect diapause is an important biological process which involves many life-history parameters important for survival and reproductive fitness at both individual and population level. Drosophila montana, a species of D. virilis group, has a profound photoperiodic reproductive diapause that enables the adult flies to survive through the harsh winter conditions of high latitudes and altitudes. We created a custom-made microarray for D. montana with 101 genes known to affect traits important in diapause, photoperiodism, reproductive behaviour, circadian clock and stress tolerance in model Drosophila species. This array gave us a chance to filter out genes showing expression changes during photoperiodic reproductive diapause in a species adapted to live in northern latitudes with high seasonal changes in environmental conditions.
Comparisons among diapausing, reproducing and young D. montana females revealed expression changes in 24 genes on microarray; for example in comparison between diapausing and reproducing females one gene (Drosophila cold acclimation gene, Dca) showed up-regulation and 15 genes showed down-regulation in diapausing females. Down-regulation of seven of these genes was specific to diapause state while in five genes the expression changes were linked with the age of the females rather than with their reproductive status. Also, qRT-PCR experiments confirmed couch potato (cpo) gene to be involved in diapause of D. montana.
A candidate gene microarray proved to offer a practical and cost-effective way to trace genes that are likely to play an important role in photoperiodic reproductive diapause and further in adaptation to seasonally varying environmental conditions. The present study revealed two genes, Dca and cpo, whose role in photoperiodic diapause in D. montana is worth of studying in more details. Also, further studies using the candidate gene microarray with more specific experimental designs and target tissues may reveal additional genes with more restricted expression patterns.
昆虫休眠是一个重要的生物学过程，涉及到许多个体和种群水平上生存和生殖适应性的重要生命史参数。山地果蝇（Drosophila montana）是 D. virilis 组的一个物种，具有深刻的光周期生殖休眠，使成年果蝇能够在高纬度和高海拔地区恶劣的冬季条件下生存。我们为山地果蝇创建了一个定制的微阵列，其中包含 101 个已知影响休眠、光周期、生殖行为、生物钟和应激耐受性等特征的基因。这个微阵列让我们有机会筛选出在适应高纬度地区季节性环境变化的物种中，在光周期生殖休眠期间表现出表达变化的基因。
在休眠、生殖和年轻的山地果蝇雌性个体之间的比较中，微阵列显示了 24 个基因的表达变化；例如，与生殖雌性相比，休眠雌性中一个基因（果蝇冷适应基因，Dca）上调表达，15 个基因下调表达。这 7 个基因的下调表达是休眠状态特异性的，而在 5 个基因中，表达变化与雌性的年龄而不是生殖状态有关。此外，qRT-PCR 实验证实 couch potato (cpo) 基因参与了山地果蝇的休眠。
候选基因微阵列证明是一种实用且具有成本效益的方法，可以追踪那些可能在光周期生殖休眠以及进一步适应季节性变化的环境条件中发挥重要作用的基因。本研究揭示了两个基因，Dca 和 cpo，它们在山地果蝇光周期休眠中的作用值得更详细的研究。此外，使用候选基因微阵列进行更具体的实验设计和靶组织的进一步研究可能会揭示具有更受限表达模式的其他基因。
