Sensory rays in C. elegans male tail are specialized for mating. Temperature sensitive mutation in mab-22 results in missing ray phenotype at non-permissive temperature. At 25°C. the papillae formation is normal with all the ray cells developed. Cell specific promoters driving cell specific gfp markers revealed the presence of ray cells while extended rays were lost. However. the ray formation process is defective in the ray retraction period. Therefore, mab-22 is required primarily for the ray assembly process but does not impact on ray cell lineage. Larvae gown at 25°C present anteriorly shortened alae and detachment of seam cells from the tail seam. mab-22 is also required for viability with mutant embryos cultured at 25°C often arrested at late embryonic or early L1 stage. Animals d...[ Read more ]

Sensory rays in C. elegans male tail are specialized for mating. Temperature sensitive mutation in mab-22 results in missing ray phenotype at non-permissive temperature. At 25°C. the papillae formation is normal with all the ray cells developed. Cell specific promoters driving cell specific gfp markers revealed the presence of ray cells while extended rays were lost. However. the ray formation process is defective in the ray retraction period. Therefore, mab-22 is required primarily for the ray assembly process but does not impact on ray cell lineage. Larvae gown at 25°C present anteriorly shortened alae and detachment of seam cells from the tail seam. mab-22 is also required for viability with mutant embryos cultured at 25°C often arrested at late embryonic or early L1 stage. Animals developed at 16°C or 20°C often have their brood size reduced by one third. mab-22 mutants exhibit a mild Him (High Incidence of Male) phenotype and present three percents of males in the progeny.

mab-22 was previously mapped on the left arm of chromosome III. Positional cloning identified a genomic fragment containing the gene tbx-2 to be able to restore wild type phenotype in mab-22 animals at 25°C. RNA interference of tbx-2 in wild type males gave a mild ray-missing phenotype. Finally. mutation mapping confirmed that mab-22 gene indeed encodes the nematode TBX-2. We attempted to study the expsession of tbx-2 and demonstsated that tbx-2 gene may expsess in the male tail. Previous studies on tbx-2 gene showed that tbx-2 is expressed in the embryos and in the sensory neusons in the pharynx. This study of mab-22 provides us insight on how the ray cells are assembled together during organogenesis. Moreover, it offers a platform for studying functional specificity of T-box transcription factors.