Morphogenesis is a process that shapes an object such as an organ or a tissue. In this study, C. elegans was employed as a model organism to reveal the molecular mechanisms of morphogenesis. Although nine ram mutant genes that lead to r̲a̲y m̲orphology abnormal (Ram) phenotype have been isolated and cloned, our understanding of ray morphogenesis remains obscure. In this thesis, I would isolate genes required for ray morphogenesis by cloning and characterizing them. Gene mapping using genetic and physical markers followed by the functional rescue of ram(wx66) and ram(wx72) have led to the identification of Y59A8B.6. Y59A8B.6 residing in the rescuing DNA fragment was found to phenocopy ram-6 mutant partially when it was knocked down. Also, two innexin-coding genes, inx-12 and inx-13, we...[ Read more ]

Morphogenesis is a process that shapes an object such as an organ or a tissue. In this study, C. elegans was employed as a model organism to reveal the molecular mechanisms of morphogenesis. Although nine ram mutant genes that lead to r̲a̲y m̲orphology abnormal (Ram) phenotype have been isolated and cloned, our understanding of ray morphogenesis remains obscure. In this thesis, I would isolate genes required for ray morphogenesis by cloning and characterizing them. Gene mapping using genetic and physical markers followed by the functional rescue of ram(wx66) and ram(wx72) have led to the identification of Y59A8B.6. Y59A8B.6 residing in the rescuing DNA fragment was found to phenocopy ram-6 mutant partially when it was knocked down. Also, two innexin-coding genes, inx-12 and inx-13, were identified in a genome-wide RNAi screen. Observations of the phenotypes of Y59A8B.6(RNAi), inx-12(RNAi) and inx-13(RNAi) animals reveal that the three genes are required for ray morphogenesis. Y59A8B.6 is expressed in the ray structural cell, and inx-12 and inx-13 are transcribed as an operon in both the ray structural cell and the hypodermis. Innexin fusion proteins with fluorescent proteins revealed that they are co-localized at the ray structural cell membrane in a punctate pattern. The localization data together with the expression data suggested that INX-12 and INX-13 may form gap junction plaques between the ray structural cells with the hypodermis. Y59A8B.6 is the third ram gene that has been identified to express in ray structural cell. Further research on this gene will provide more information on the role of structural cell in ray morphogenesis.