Male-killing Spiroplasma induces sex-specific cell death via host apoptotic pathway.
Male-killing Spiroplasma induces sex-specific cell death via host apoptotic pathway.
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DOI：
10.1371/journal.ppat.1003956
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发表时间：
2014-02
期刊：
影响因子：
6.7
通讯作者：
Fukatsu T
中科院分区：
文献类型：
--
作者：
Harumoto T;Anbutsu H;Fukatsu T
一些共生细菌在其寄主昆虫中引起显著的生殖表型，如细胞质不相容性和杀雄。这些共生体诱导的生殖病理的分子和细胞机制是非常感兴趣的，但知之甚少。本研究以黑腹果蝇和其原生螺原体共生株MSRO为材料，探讨了宿主的分子、细胞和形态发生途径是如何参与共生体诱导的雄性致死的。TUNEL（末端脱氧核苷酸转移酶dUTP缺口末端标记）染色，抗-切割-Caspase-3抗体染色，和凋亡缺陷突变体分析明确表明，宿主的凋亡途径参与螺旋体诱导的男性特异性胚胎细胞死亡。TUNEL和识别表皮标志物的抗体的双重染色表明，胚胎上皮是螺旋体诱导的男性特异性凋亡的主要靶点。免疫染色与分化和前体神经细胞的标记物的抗体可视化严重的神经缺陷，特别是在螺旋体感染的男性胚胎在以前的研究报告。然而，在雄性胚胎的退化神经组织中检测到很少的TUNEL信号，并且在螺旋体病缺陷宿主突变体中，螺旋体引起的雄性胚胎神经缺陷没有被抑制。这些结果表明，寄生虫依赖的表皮细胞死亡和寄生虫不依赖的神经畸形可能代表不同的机制螺旋体诱导的男性杀死。尽管存在雄性特异性进行性胚胎异常，但在整个观察到的胚胎发育阶段以及雄性和雌性胚胎中，螺原体滴度几乎保持恒定。引人注目的是，一些螺原体感染的胚胎表现出雌雄同体，其中凋亡细胞死亡仅限于雄性细胞。这些观察结果表明，螺原体细胞的数量和增殖都不是雄性杀伤表型表达的原因，而是一些螺原体衍生因子。共生细菌普遍存在于各种昆虫中，并以各种方式影响其宿主生物学。在果蝇中，感染螺旋体共生体通常会导致雄性特异性胚胎死亡，导致产生全雌性后代。这种引人注目的表型被称为“雄性杀戮”，其潜在机制引起了极大的兴趣。在这里，我们调查了果蝇和它的原生螺原体共生菌株，以了解宿主的分子，细胞和形态发生途径参与共生体诱导的雄性杀伤。特别是在螺原体感染的雄性胚胎中，观察到致病性表型，包括全身大量细胞死亡和神经畸形。我们明确地确定，男性特异性细胞死亡优先发生在胚胎上皮细胞通过主机的凋亡途径。同时，我们发现，出乎意料的是，雄性特异性神经缺陷的发生独立于宿主的细胞凋亡，这表明至少有两种不同的机制可能参与了螺旋体诱导的雄性杀伤。同样出乎意料的是，尽管存在雄性特异性严重细胞凋亡，但螺原体滴度在整个胚胎发生过程中几乎恒定，与性别无关。我们偶然发现了螺原体感染的性嵌合体胚胎，其中凋亡与雄性细胞有关，这表明一些螺原体衍生因子可能选择性地作用于雄性细胞并导致雄性杀伤。
Some symbiotic bacteria cause remarkable reproductive phenotypes like cytoplasmic incompatibility and male-killing in their host insects. Molecular and cellular mechanisms underlying these symbiont-induced reproductive pathologies are of great interest but poorly understood. In this study, Drosophila melanogaster and its native Spiroplasma symbiont strain MSRO were investigated as to how the host's molecular, cellular and morphogenetic pathways are involved in the symbiont-induced male-killing during embryogenesis. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) staining, anti-cleaved-Caspase-3 antibody staining, and apoptosis-deficient mutant analysis unequivocally demonstrated that the host's apoptotic pathway is involved in Spiroplasma-induced male-specific embryonic cell death. Double-staining with TUNEL and an antibody recognizing epidermal marker showed that embryonic epithelium is the main target of Spiroplasma-induced male-specific apoptosis. Immunostaining with antibodies against markers of differentiated and precursor neural cells visualized severe neural defects specifically in Spiroplasma-infected male embryos as reported in previous studies. However, few TUNEL signals were detected in the degenerate nervous tissues of male embryos, and the Spiroplasma-induced neural defects in male embryos were not suppressed in an apoptosis-deficient host mutant. These results suggest the possibility that the apoptosis-dependent epidermal cell death and the apoptosis-independent neural malformation may represent different mechanisms underlying the Spiroplasma-induced male-killing. Despite the male-specific progressive embryonic abnormality, Spiroplasma titers remained almost constant throughout the observed stages of embryonic development and across male and female embryos. Strikingly, a few Spiroplasma-infected embryos exhibited gynandromorphism, wherein apoptotic cell death was restricted to male cells. These observations suggest that neither quantity nor proliferation of Spiroplasma cells but some Spiroplasma-derived factor(s) may be responsible for the expression of the male-killing phenotype. Symbiotic bacteria are ubiquitously associated with diverse insects, and affect their host biology in a variety of ways. In Drosophila fruit flies, infection with Spiroplasma symbionts often causes male-specific embryonic mortality, resulting in the production of all-female offspring. This striking phenotype is called “male-killing”, whose underlying mechanisms are of great interest. Here we investigated Drosophila melanogaster and its native Spiroplasma symbiont strain to understand how the host's molecular, cellular and morphogenetic pathways are involved in the symbiont-induced male-killing. Specifically in Spiroplasma-infected male embryos, pathogenic phenotypes including massive cell death throughout the body and neural malformation were observed. We unequivocally identified that the male-specific cell death preferentially occurs in the embryonic epithelium via the host's apoptotic pathway. Meanwhile, we found that, unexpectedly, the male-specific neural defects occur independently of host's apoptosis, suggesting that at least two different mechanisms may be involved in the Spiroplasma-induced male-killing. Also unexpected was the finding that Spiroplasma titers are almost constant throughout embryogenesis irrespective of sex despite the male-specific severe apoptosis. We serendipitously found Spiroplasma-infected sexual mosaic embryos, wherein apoptosis was associated with male cells, which suggests that some Spiroplasma-derived factor(s) may selectively act on male cells and cause male-killing.
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影响因子：
12.4
作者：
Fan, Y.;Bergmann, A.
通讯作者：
Bergmann, A.
影响因子：
10.5
作者：
BOPP, D;BELL, LR;SCHEDL, P
通讯作者：
SCHEDL, P
DOI：
10.1098/rspb.1998.0402
发表时间：
1998-06-22
影响因子：
4.7
作者：
Bouchon, D;Rigaud, T;Juchault, P
通讯作者：
Juchault, P
影响因子：
10.5
作者：
Chen, P;Nordstrom, W;Abrams, JM
通讯作者：
Abrams, JM
影响因子：
4.2
作者：
Anbutsu, Hisashi;Fukatsu, Takema
通讯作者：
Fukatsu, Takema