Identification and functional analysis of chemoreceptor in the nematode

了解动物如何感知和区分大量的气味是很重要的。嗅觉感受器通过鞭毛内转运分子转运到感觉神经元的尖端。因此，在许多真核和原核细胞中，鞭毛内运输（IFT）是纤毛生物发生和维持的重要机制。已知有大量多肽参与IFT，但每种成分的生理作用尚未完全阐明。我们鉴定了秀丽隐杆线虫与莱茵衣单胞菌IFT组分的同源物IFT-81，并发现其功能丧失突变体表现出不寻常的行为特性和较小的体型。与野生型动物相比，突变体的活动区域被限制在狭窄的范围内。IFT-81在感觉神经元中表达，定位于纤毛基部。在一些IFT突变体中也观察到与IFT -81突变体相似的表型，表明这些缺陷是由IFT无法引起的。我们还证明了IFT-81与IFT-74相互作用并共定位，IFT-74是IFT的另一个假定成分。我们分离了ift-74基因的缺失突变等位基因。功能缺失突变体ift-74表现出与ift-81突变体相同的表型，表明ift-81和ift-74具有相似的功能。此外，ift-81和ift-74突变体在纤毛形成方面同样表现出微弱的异常，在成熟纤毛中也表现出明显的运输中断。因此，我们认为IFT-81和IFT-74协同作用于秀丽隐杆线虫感觉纤毛的IFT。

It is important to understand how animals feel and distinguish a large number of odorants. The receptors for odorants are transported to the tips of the sensory neurons by intraflagellar transport molecules. Thus, intraflagellar transport (IFT) is essential machinery for biogenesis and maintenance of cilia in many eukaryotic and prokaryotic cells. A large number of polypeptides are known to be involved in IFT, but the physiological role of each component is not fully elucidated. We identified a C.elegans orthologue of a Chlamydomonas reinhardtii IFT component, IFT-81, and found that its loss-of-function mutants show an unusual behavioral property and small body size. The moving area of the mutants is restricted to narrow compared to that of wild-type animals.IFT-81 is expressed in sensory neurons, and localized at the base of cilia. The similar phenotypes with ift-81 mutants were also observed in several IFT mutants, suggesting these defects are caused by inability of IFT. We also demonstrated that IFT-81 interacts and co-localizes with IFT-74, which is another putative component of IFT. We isolated deletion mutant alleles for the ift-74 gene. The ift-74 loss-of-function mutants showed phenocopies with ift-81 mutants, suggesting IFT-81 and IFT-74 play comparable functions. Moreover, ift-81 and ift-74 mutants similarly exhibited weak anomalies in cilia formation and obvious disruptions of transport in mature cilia. Thus, we conclude that IFT-81 and IFT-74 coordinately act in IFT in C.elegans sensory cilia.