Velenovsky Joseph F, Kalisch Jessica, Bulmer Mark S
Department of Biological Sciences, Towson University, 341 Smith Hall, 8000 York Rd., Towson, MD, 21252, USA.
Genetica. 2016 Oct;144(5):547-552. doi: 10.1007/s10709-016-9923-0. Epub 2016 Sep 13.
We identified the antifungal gene termicin in three species of Cryptocercus woodroaches. Cryptocercus represents the closest living cockroach lineage of termites, which suggests that the antifungal role of termicin evolved prior to the divergence of termites from other cockroaches. An analysis of Cryptocercus termicin and two β-1,3-glucanase genes (GNBP1 and GNBP2), which appear to work synergistically with termicin in termites, revealed evidence of selection in these proteins. We identified the signature of past selective sweeps within GNBP2 from Cryptocercus punctulatus and Cryptocercus wrighti. The signature of past selective sweeps was also found within termicin from Cryptocercus punctulatus and Cryptocercus darwini. Our analysis further suggests a phenotypically identical variant of GNBP2 was maintained within Cryptocercus punctulatus, Cryptocercus wrighti, and Cryptocercus darwini while synonymous sites diverged. Cryptocercus termicin and GNBP2 appear to have experienced similar selective pressure to that of their termite orthologues in Reticulitermes. This selective pressure may be a result of ubiquitous entomopathogenic fungal pathogens such as Metarhizium. This study further reveals the similarities between Cryptocercus woodroaches and termites.
我们在三种隐尾蠊中鉴定出了抗真菌基因termicin。隐尾蠊是现存与白蚁亲缘关系最近的蟑螂谱系，这表明termicin的抗真菌作用在白蚁与其他蟑螂分化之前就已进化。对隐尾蠊termicin和两个β-1,3-葡聚糖酶基因（GNBP1和GNBP2）的分析显示，在白蚁中它们似乎与termicin协同发挥作用，这些蛋白质存在选择的证据。我们在斑点隐尾蠊和赖氏隐尾蠊的GNBP2中鉴定出了过去选择性清除的特征。在斑点隐尾蠊和达尔文隐尾蠊的termicin中也发现了过去选择性清除的特征。我们的分析进一步表明，在斑点隐尾蠊、赖氏隐尾蠊和达尔文隐尾蠊中，GNBP2的一个表型相同的变体得以保留，而同义位点发生了分化。隐尾蠊termicin和GNBP2似乎经历了与它们在网翅白蚁中的直系同源物相似的选择压力。这种选择压力可能是由普遍存在的昆虫病原真菌病原体如绿僵菌导致的。这项研究进一步揭示了隐尾蠊与白蚁之间的相似性。
