Morphogenesis is an important and complicated process in controlling the final shape of different structures in an organism. To uncover the general molecular mechanism in this developmental process, the male sensory ray of C. elegans is chosen as a model for study. Nine ram (R̲A̲y M̲orphology abnormal) genes required for normal ray morphogenesis have so far been identified. The tapered rays turn into lumpy rays when any of these genes is mutated. Among these ram genes, ram-5 encodes a novel transmembrane protein while mab-7 encodes a novel protein with a hydrophobic region (HR) at its N-terminus. The property of HR of MAB-7 was shown to be a type II transmembrane domain by domain swapping analysis and protein localization examination. Ectopic expression of mab-7 in a subset of neurons i...[ Read more ]

Morphogenesis is an important and complicated process in controlling the final shape of different structures in an organism. To uncover the general molecular mechanism in this developmental process, the male sensory ray of C. elegans is chosen as a model for study. Nine ram (R̲A̲y M̲orphology abnormal) genes required for normal ray morphogenesis have so far been identified. The tapered rays turn into lumpy rays when any of these genes is mutated. Among these ram genes, ram-5 encodes a novel transmembrane protein while mab-7 encodes a novel protein with a hydrophobic region (HR) at its N-terminus. The property of HR of MAB-7 was shown to be a type II transmembrane domain by domain swapping analysis and protein localization examination. Ectopic expression of mab-7 in a subset of neurons in the male tail could rescue Mab-7 phenotype suggesting that mab-7 is acting non-autonomously during ray morphogenesis.

Although the identities of the nine ram genes were known, the details of the mechanism guiding ray morphogenesis have not been worked out. To identify the missing components, three approaches were initiated including an EMS screen, a yeast two-hybrid screen and a target specific RNAi knock down screen. Twelve new ram alleles and newly defined loci were isolated in our EMS screen. GFI-1 was identified to be a MAB-7 interacting partner from the yeast two-hybrid screen. Expression pattern and RNAi analyses of this gfi-1 gene were performed to determine its biological relevance with mab-7 function. Target specific RNAi treatment had uncovered noah-2 to be a new ram component. The requirement of this gene in ray morphogenesis was studied by dominant negative approach. Furthermore, ram-5 was shown to genetically interact with the three RAM collagen-encoding genes, suggesting that the gene product of these genes might associate together during ray morphogenesis.