Hodgkin J, Kuwabara P E, Corneliussen B
MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK.
Curr Biol. 2000;10(24):1615-8. doi: 10.1016/s0960-9822(00)00867-8.
The Dar (deformed anal region) phenotype, characterized by a distinctive swollen tail, was first detected in a variant strain of Caenorhabditis elegans which appeared spontaneously in 1986 during routine genetic crosses [1,2]. Dar isolates were initially analysed as morphological mutants, but we report here that two independent isolates carry an unusual bacterial infection different from those previously described [3], which is the cause of the Dar phenotype. The infectious agent is a new species of coryneform bacterium, named Microbacterium nematophilum n. sp., which fortuitously contaminated cultures of C. elegans. The bacteria adhere to the rectal and post-anal cuticle of susceptible nematodes, and induce substantial local swelling of the underlying hypodermal tissue. The swelling leads to constipation and slowed growth in the infected worms, but the infection is otherwise non-lethal. Certain mutants of C. elegans with altered surface antigenicity are resistant to infection. The induced deformation appears to be part of a survival strategy for the bacteria, as C. elegans are potentially their predators.
Dar（肛门变形区域）表型的特征是尾部明显肿胀，于1986年在秀丽隐杆线虫的一个变异株中首次发现，该变异株在常规遗传杂交过程中自发出现[1,2]。最初，Dar分离株被分析为形态突变体，但我们在此报告，两个独立的分离株携带一种与先前描述的不同的异常细菌感染[3]，这就是Dar表型的原因。感染因子是一种新的棒状细菌，名为嗜线虫微杆菌（Microbacterium nematophilum n. sp.），它偶然污染了秀丽隐杆线虫的培养物。这些细菌附着在易感线虫的直肠和肛门后角质层上，并导致其下方皮下组织出现明显的局部肿胀。肿胀导致受感染蠕虫便秘和生长缓慢，但这种感染在其他方面并不致命。某些表面抗原性改变的秀丽隐杆线虫突变体对感染具有抗性。诱导的变形似乎是细菌生存策略的一部分，因为秀丽隐杆线虫可能是它们的捕食者。
