PDF(Pubmed)
Abstract：
Analyses of the contributions of genetic variants in wild strains to phenotypic differences have led to a more complete description of the pathways underlying cellular functions. Causal loci are typically identified via interbreeding of strains with distinct phenotypes in order to establish recombinant inbred lines (RILs). Since the generation of RILs requires growth for multiple generations, their genomes may contain not only different combinations of parental alleles but also genetic changes that arose de novo during the establishment of these lines. Here, we report that in the course of generating RILs between Caenorhabditis elegans strains that exhibit distinct thermotaxis behavioral phenotypes, we identified spontaneously arising variants in the ttx-1 locus. ttx-1 encodes the terminal selector factor for the AFD thermosensory neurons, and loss-of-function mutations in ttx-1 abolish thermotaxis behaviors. The identified genetic changes in ttx-1 in the RIL are predicted to decrease ttx-1 function in part via specifically affecting a subset of AFD-expressed ttx-1 isoforms. Introduction of the relevant missense mutation in the laboratory C. elegans strain via gene editing recapitulates the thermotaxis behavioral defects of the RIL. Our results suggest that spontaneously occurring genomic changes in RILs may complicate identification of loci contributing to phenotypic variation, but that these mutations may nevertheless lead to the identification of important causal molecules and mechanisms.
摘要：
对野生菌株中遗传变异体对表型差异的贡献的分析已导致对细胞功能基础途径的更完整描述。通常通过具有不同表型的菌株的杂交鉴定因果基因座，以建立重组自交系（RIL）。由于RIL的产生需要多代的增长，它们的基因组可能不仅包含亲本等位基因的不同组合，还包含在这些系建立过程中从头出现的遗传变化。在这里，我们报道了在秀丽隐杆线虫菌株之间产生RIL的过程中，这些菌株表现出不同的热适性行为表型，我们在ttx-1基因座中鉴定了自发产生的变体。ttx-1编码AFD热感神经元的末端选择因子，ttx-1中的功能丧失突变消除了热迁移行为。预测RIL中ttx-1的鉴定的遗传变化部分地通过特异性影响AFD表达的ttx-1同种型的子集来降低ttx-1功能。通过基因编辑在实验室秀丽隐杆线虫菌株中引入相关的错义突变概括了RIL的热适性行为缺陷。我们的结果表明，RIL中自发发生的基因组变化可能会使鉴定导致表型变异的基因座复杂化。但是这些突变仍然可能导致重要的因果分子和机制的鉴定。
