A Nightmare for Males? A Maternally Transmitted Male-Killing Bacterium and Strong Female Bias in a Green Lacewing Population.
A Nightmare for Males? A Maternally Transmitted Male-Killing Bacterium and Strong Female Bias in a Green Lacewing Population.
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DOI：
10.1371/journal.pone.0155794
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Kageyama D
中科院分区：
文献类型：
--
作者：
Hayashi M;Watanabe M;Yukuhiro F;Nomura M;Kageyama D
对于母系传播的微生物，雌性偏向的宿主性别比具有繁殖优势。在这里，我们发现了一个强大的女性偏见在外地人口的绿色草蛉，Mallada desjardinsi（昆虫纲;脉翅目）。这种偏见是由于个体的优势窝藏母系遗传的男性杀死细菌，是植物病原性螺旋体phoeniceum和Spiroplasma kunkelii的基因密切相关。在35个实验室饲养的育雏野生捕获的女性，21个育雏（60%）-所有感染螺旋体-仅由女性（940人）。在14个由雄性和雌性组成的窝（分别为516和635个体）中，4个窝被螺旋体和立克次体双重感染，6个窝被立克次体单独感染，3个窝未被感染（剩余一个窝未知）。在胚胎和幼虫发育过程中的死亡率是突出的所有女性育雏，但不是在正常的性别比例育雏。对所有雌性育雏进行抗生素治疗后，死亡率显着降低，性别比恢复到1：1。考虑到其低密度（基于定量PCR，每个宿主线粒体基因拷贝约10−5-10−4个细胞），这种雄性杀手的强表达和高流行率是显著的。此外，与贝氏立克次体密切相关的细菌存在于34窝中的25窝（73.5%）中，无论性别比例如何，其感染密度与其他内共生病例相当（每个线粒体基因拷贝约10−2-10−1个细胞）。电子显微镜下可见卵巢细胞内外的螺原体样细胞和立克次体样细胞，立克次体密度高于螺原体。
For maternally transmitted microbes, a female-biased host sex ratio is of reproductive advantage. Here we found a strong female bias in a field population of the green lacewing, Mallada desjardinsi (Insecta; Neuroptera). This bias was attributed to the predominance of individuals harboring a maternally inherited male-killing bacterium that was phylogenetically closely related to the plant-pathogenic Spiroplasma phoeniceum and Spiroplasma kunkelii. Among 35 laboratory-reared broods produced by wild-caught females, 21 broods (60%)—all infected with Spiroplasma—consisted of only females (940 individuals). Among 14 broods consisting of both males and females (516 and 635 individuals, respectively), 4 broods were doubly infected with Spiroplasma and Rickettsia, 6 broods were singly infected with Rickettsia, and 3 broods were uninfected (remaining one brood was unknown). Mortality during embryonic and larval development was prominent in all-female broods but not in normal sex ratio broods. Following antibiotic treatment on all-female broods, mortality was significantly reduced and the sex ratio was restored to 1:1. Strong expression and high prevalence of this male-killer is remarkable considering its low density (~10−5–10−4 cells per host mitochondrial gene copy based on quantitative PCR). In addition, a bacterium closely related to Rickettsia bellii was present in 25 of 34 broods (73.5%), irrespective of the sex ratio, with the infection density comparable to other cases of endosymbiosis (~10−2–10−1 cells per mitochondrial gene copy). Higher density of Rickettsia than Spiroplasma was also demonstrated by electron microscopy which visualized both Spiroplasma-like cells and Rickettsia-like cells inside and outside the ovarian cells.