Identification and functional analysis of chemoreceptor in the nematode

重要的是要了解动物的感觉和区分大量的气味。气味物质的受体通过鞭毛内转运分子转运到感觉神经元的顶端。因此，鞭毛内转运（IFT）是许多真核和原核细胞中纤毛生物发生和维持的基本机制。已知大量多肽参与IFT，但各组分的生理作用尚未完全阐明。我们确定了一个秀丽隐杆线虫直系同源的衣原体reinhardtii IFT组件，IFT-81，并发现其功能丧失的突变体显示出不寻常的行为特性和小的身体尺寸。IFT-81在感觉神经元中表达，并定位于纤毛基部。在几个IFT突变体中也观察到与IFT-81突变体相似的表型，表明这些缺陷是由于IFT不能引起的。我们还证明了IFT-81与IFT-74相互作用并共定位，IFT-74是IFT的另一个推定组分。我们分离了ift-74基因的缺失突变等位基因。IFT-74功能丧失突变体显示出与IFT-81突变体的表型相似性，表明IFT-81和IFT-74发挥相当的功能。此外，ift-81和ift-74突变体同样表现出纤毛形成的弱异常和成熟纤毛运输的明显中断。因此，我们得出结论，IFT-81和IFT-74协调作用于秀丽隐杆线虫感觉纤毛中的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.