Allen, A. K. | Search bioRxiv

bioRxiv2020

The SOD-2 protein is the single active SOD enzyme in C. elegans

The nematode C. elegans has a contingent of five sod genes, one of the largest among aerobic organism. Earlier studies revealed each of the five sod genes is capable of making perfectly active SOD proteins in heterologous expressions systems therefore none appears to be a pseudogene. Yet deletion of the entire contingent of sod genes fails to impose any effect on the survival of C. elegans except these animals appear more sensitive to extraneously applied oxidative stress condition. We asked how many of the five sod genes are actually active in C. elegans through an in-gel SOD activity analysis. Here we provide evidence that out of the five genes only the mitochondrial SOD gene is active in C. elegans, albeit at a much lesser amount compared to D. melanogaster and E. coli. Mutant analysis further confirmed that among the mitochondrial forms, SOD-2 is the only naturally active SOD in C. elegans.

genetics↗

bioRxiv2020

The C. elegans proteasome subunit RPN-12 is required for hermaphrodite germline sex determination and oocyte quality

BackgroundThe proteasome is a multi-subunit complex and a major proteolytic machinery in cells. Most subunits are essential for proteasome function, and depletion of individual subunits normally results in lethality. RPN-12/Rpn12/PSMD8 is a lid subunit of the 19S regulatory particle (RP) of the 26S proteasome. Studies in Caenorhabditis elegans demonstrated that RNAi depletion of RPN-12 does not result in lethality. RPN-12 has not been well studied in higher eukaryotes. In this study we investigate the biological significance of RPN-12 in C. elegans. ResultsWe found that the null mutant rpn-12(av93) did not cause major impairment of the proteolytic activity of the proteasome. Most rpn-12(av93) hermaphrodites lack sperm leading to feminization of the germ line that can be partially rescued by mating to males. The lack of sperm phenotype can be suppressed by downregulation of TRA-1, a player in the hermaphrodite germline sex determination pathway. Also, rpn-12(av93) animals show significant nuclear accumulation of the meiotic kinase WEE-1.3, a protein predominantly localized to the perinuclear region. Interestingly, chemical inhibition of the proteasome did not cause nuclear accumulation of WEE-1.3. ConclusionsRPN-12 plays a previously unknown role in oogenesis and the germline sex determination pathway in C. elegans hermaphrodites.

developmental biology↗