The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis.
The entomopathogenic nematode Steinernema hermaphroditum is a self-fertilizing hermaphrodite and a genetically tractable system for the study of parasitic and mutualistic symbiosis.
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昆虫病原线虫斯氏线虫雌雄同体是一种自体受精的雌雄同体，也是研究寄生和互利共生的遗传易驯化系统。
DOI：
10.1093/genetics/iyab170
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发表时间：
2022
期刊：
影响因子：
3.3
通讯作者：
Sternberg,PaulW
中科院分区：
文献类型：
--
作者：
Cao,Mengyi;Schwartz,HillelT;Tan,Chieh-Hsiang;Sternberg,PaulW
昆虫病原线虫（Entomopathogenicnematodes，EPN）包括异小杆线虫（Heterorhabditis）和斯氏线虫（Steinernema），它们寄生于昆虫体内，肠道内含有互利共生的细菌（分别为光小杆线虫（Photorhabdus）和黄小杆线虫（Xanthorhabdus）），因此提供了研究互利共生和寄生共生的机会。在EPN中建立遗传工具受到有限的遗传易处理性、体外不一致的生长、可变的冷冻保存和低交配效率的阻碍。我们获得了最近描述的Steinernema hermaphroditum菌株CS34，并优化了其体外生长，在其原生共生细菌Xellobhabdus griffiniae的草坪上快速繁殖。我们开发了一种简单有效的冷冻保存方法。此前，S。从昆虫宿主中分离的两性体（hermaphroditum）被描述为在第一代产生两性体。我们发现，CS34在体外生长时，产生连续几代的自主繁殖的雌雄同体伴随着罕见的男性。我们在S.hermaphroditum中进行了诱变筛选，产生了具有可见和可遗传表型的突变株系。对突变体的遗传分析表明，该物种通过自花受精而不是孤雌生殖繁殖，其性别由染色体决定。迄今为止，遗传图谱已经确定了X染色体和四个常染色体中的三个上的标记。我们报告说，S。hermaphroditumCS34是第一个一致的两性EPN，适用于研究自然发生的互惠共生和昆虫寄生的遗传模型开发。
Entomopathogenic nematodes (EPNs), includingHeterorhabditisandSteinernema, are parasitic to insects and contain mutualistically symbiotic bacteria in their intestines (PhotorhabdusandXenorhabdus, respectively) and therefore offer opportunities to study both mutualistic and parasitic symbiosis. The establishment of genetic tools in EPNs has been impeded by limited genetic tractability, inconsistent growthin vitro, variable cryopreservation, and low mating efficiency. We obtained the recently describedSteinernema hermaphroditumstrain CS34 and optimized itsin vitrogrowth, with a rapid generation time on a lawn of its native symbiotic bacteriaXenorhabdus griffiniae. We developed a simple and efficient cryopreservation method. Previously,S. hermaphroditumisolated from insect hosts was described as producing hermaphrodites in the first generation. We discovered that CS34, when grownin vitro, produced consecutive generations of autonomously reproducing hermaphrodites accompanied by rare males. We performed mutagenesis screens inS. hermaphroditumthat produced mutant lines with visible and heritable phenotypes. Genetic analysis of the mutants demonstrated that this species reproduces by self-fertilization rather than parthenogenesis and that its sex is determined chromosomally. Genetic mapping has thus far identified markers on the X chromosome and three of four autosomes. We report thatS. hermaphroditumCS34 is the first consistently hermaphroditic EPN and is suitable for genetic model development to study naturally occurring mutualistic symbiosis and insect parasitism.