Wang Zhenshan, Farmer Kristy, Hill Geoffrey E, Edwards Scott V
Department of Biology, University of Washington, Seattle, WA 98195, USA.
Mol Ecol. 2006 Apr;15(5):1263-73. doi: 10.1111/j.1365-294X.2005.02753.x.
In 1994, the bacterial parasite Mycoplasma gallisepticum expanded its host range and swept through populations of a novel host--eastern US populations of the house finch (Carpodacus mexicanus). This epizootic caused a dramatic decline in finch population numbers, has been shown to have caused strong selection on house finch morphology, and presumably caused evolutionary change at the molecular level as finches evolved enhanced resistance. As a first step toward identifying finch genes that respond to infection by Mycoplasma and which may have experienced natural selection by this parasite, we used suppression subtractive hybridization (SSH) and cDNA macroarray approaches to identify differentially expressed genes regulated by the Mycoplasma parasite. Two subtractive cDNA libraries consisting of 16,512 clones were developed from spleen using an experimentally uninfected bird as the 'tester' and an infected bird as 'driver', and vice versa. Two hundred and twenty cDNA clones corresponding 34 genes with known vertebrate homologues and a large number of novel transcripts were found to be qualitatively up- or down-regulated genes by high-density filter hybridization. These gene expression changes were further confirmed by a high throughout reverse Northern blot approach and in specific cases by targeted Northern analysis. blast searches show that heat shock protein (HSP) 90, MHC II-associated invariant chain (CD74), T-cell immunoglobulin mucin 1 (TIM1), as well as numerous novel expressed genes not found in the databases were up- or down-regulated by the host in response to this parasite. Our results and macroarray resources provide a foundation for molecular co-evolutionary studies of the Mycoplasma parasite and its recently colonized avian host.
1994年，细菌寄生虫鸡败血支原体扩大了其宿主范围，席卷了一种新宿主——美国东部地区的家朱雀（Carpodacus mexicanus）种群。这场动物疫病导致朱雀种群数量急剧下降，已被证明对家朱雀的形态产生了强烈的选择作用，并且随着朱雀进化出更强的抵抗力，推测在分子水平上也引起了进化变化。作为识别对鸡败血支原体感染有反应且可能经历了这种寄生虫自然选择的朱雀基因的第一步，我们使用抑制性消减杂交（SSH）和cDNA宏阵列方法来鉴定受该支原体寄生虫调控的差异表达基因。以一只实验未感染的鸟作为“测试者”，一只感染的鸟作为“驱动者”，从脾脏构建了两个包含16,512个克隆的消减cDNA文库，反之亦然。通过高密度滤膜杂交发现，220个对应34个具有已知脊椎动物同源物的基因的cDNA克隆以及大量新转录本在定性上是上调或下调基因。这些基因表达变化通过高通量反向Northern印迹法进一步得到证实，在特定情况下通过靶向Northern分析得到证实。Blast搜索表明，热休克蛋白（HSP）90、MHC II相关恒定链（CD74）、T细胞免疫球蛋白粘蛋白1（TIM1），以及数据库中未发现的许多新表达基因在宿主对这种寄生虫的反应中上调或下调。我们的结果和宏阵列资源为支原体寄生虫及其最近定殖的鸟类宿主的分子协同进化研究提供了基础。
