Laboratório de Drosophila, Departamento de Genética, Programa de Pós Graduação em Genética e Biologia Molecular (PPGBM), Instituto de Biociências, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil.
Infect Genet Evol. 2013 Oct;19:232-9. doi: 10.1016/j.meegid.2013.07.022. Epub 2013 Jul 29.
Infections by the endosymbiotic bacterium Wolbachia developed a rapid global expansion within Old World Drosophila species, ultimately infecting also Neotropical species. In this sense, screenings are necessary to characterize new variants of Wolbachia or new hosts, and also in order to map the dynamics of already known infections. In this paper, we performed a double screening approach that combined Dot-blot and PCR techniques in order to reevaluate the infection status by Wolbachia in species from the willistoni subgroup of Drosophila. Genomic DNA from isofemale lines descendent from females collected in the Amazonian Rainforest (n=91) were submitted to Dot-blot, and were positive for Wolbachia, producing a gradient of hybridization signals, suggesting different infection levels, which was further confirmed through quantitative PCR. Samples with a strong signal in the Dot-blot easily amplified in the wsp-PCR, unlike most of the samples with a medium to weak signal. It was possible to molecularly characterize three Drosophila equinoxialis isofemale lines that were found to be infected in a low density by a wMel-like Wolbachia strain, which was also verified in a laboratory line of Drosophila paulistorum Amazonian. We also found Drosophila tropicalis to be infected with the wAu strain and a Drosophila paulistorum Andean-Brazilian semispecies laboratory line to be infected with a wAu-like Wolbachia. Moreover, we observed that all Drosophila willistoni samples tested with the VNTR-141 marker harbor the same Wolbachia variant, wWil, either in populations from the South or the North of Brazil. Horizontal transfer events involving species of Old World immigrants and Neotropical species of the willistoni subgroup are discussed.
内共生菌沃尔巴克氏体在旧世界果蝇种内迅速全球扩张，最终也感染了新热带种。在这种情况下，有必要进行筛选，以鉴定新的沃尔巴克氏体变体或新宿主，并且还需要对已经存在的感染进行动态监测。在本文中，我们采用了双重筛选方法，将斑点印迹和 PCR 技术相结合，以重新评估亚马逊雨林采集的威斯塔尼亚亚组果蝇种的沃尔巴克氏体感染状况。从亚马逊雨林采集的雌性后代的同性别系的基因组 DNA（n=91）进行斑点印迹分析，结果显示沃尔巴克氏体呈阳性，产生杂交信号梯度，表明存在不同的感染水平，这进一步通过定量 PCR 得到了证实。斑点印迹中信号较强的样本很容易在 wsp-PCR 中扩增，而信号中等至较弱的样本则不然。通过分子特征鉴定，发现了三个感染密度较低的果蝇 equinoxialis 同性别系，它们被一种类似于 wMel 的沃尔巴克氏体菌株感染，这在亚马逊地区的 Drosophila paulistorum 实验室系中也得到了验证。我们还发现 Drosophila tropicalis 感染了 wAu 菌株，Drosophila paulistorum 安第斯-巴西半种实验室系感染了类似于 wAu 的沃尔巴克氏体。此外，我们观察到所有用 VNTR-141 标记测试的 Drosophila willistoni 样本都携带相同的沃尔巴克氏体变体 wWil，无论它们来自巴西的南部还是北部。还讨论了涉及旧世界移民物种和威斯塔尼亚亚组新热带物种的水平转移事件。
