ALBERT

Description: Extracelluar matrix undergoes constant remodeling, cell–cell, and cell–matrix interactions during chicken ovarian follicle growth, which is coordinated by matrix metalloproteinases (MMPs), and their associated endogenous inhibitors (TIMPs). Transcriptome analysis revealed upregulation of MMP13 in sexually mature chicken ovaries. In this study, we found that the expression of MMP13 in chicken ovary was stably elevated from 60 d to 159 d, and was significantly higher at 159 d than at the other three developmental stages ( P  〈 0.05). The expression of MMP13 mRNA increased from SW (small white follicles) to F5 (fifth largest follicles), then decreased to F1 (first largest follicles), and dramatically increased again in POF1 (newly postovulatory follicles) follicles ( P  〈 0.05). The MMP13 protein was localized in stroma cells and primordial follicles of sexually immature chicken ovaries, in the theca cell layers of all sized follicles of sexually mature chicken ovaries. Furthermore, we identified a positive element (positions –1863 to –1036) controlling chicken MMP13 transcription, and, in this region, six single nucleotide polymorphisms were found and genotyped in chicken populations. In the White Recessive Rock population, hens with A –1356 -C –1079 / A –1356 -C –1079 genotype had earlier "age at first laying" than those with G –1356 -T –1079 / G –1356 -T –1079 genotype ( P  〈 0.05), and exhibited significantly lower transcriptional activity ( P  〈 0.01). Collectively, chicken MMP13 plays an important role in ovarian follicle growth and regression, and polymorphisms in its promoter region could be used as molecular markers for improving the trait "age at first laying" in chicken breeding.

Description: The Caenorhabditis elegans DEG/ENaC proteins MEC-4 and MEC-10 transduce gentle touch in the six touch receptor neurons . Gain-of-function mutations of mec-4 and mec-4 (d) result in a hyperactive channel and neurodegeneration in vivo . Loss of MEC-6 , a putative DEG/ENaC-specific chaperone, and of the similar protein POML-1 suppresses the neurodegeneration caused by a mec-4 (d) mutation. We find that mutation of two genes, mec-10 and a new gene mec-19 (previously named C49G9.1 ), prevents this action of POML-1 , allowing the touch receptor neurons to die in poml-1 mec-4 (d) animals. The proteins encoded by these genes normally inhibit mec-4 (d) neurotoxicity through different mechanisms. MEC-10 , a subunit of the mechanosensory transduction channel with MEC-4 , inhibits MEC-4 (d) activity without affecting MEC-4 expression. In contrast, MEC-19 , a membrane protein specific to nematodes, inhibits MEC-4 (d) activity and reduces MEC-4 surface expression.