The DEAD-box protein MEL-46 is required in the germ line of the nematode Caenorhabditis elegans.
BACKGROUND
In the hermaphrodite of the nematode Caenorhabditis elegans, the first germ cells differentiate as sperm. Later the germ line switches to the production of oocytes. This process requires the activity of a genetic regulatory network that includes among others the fem, fog and mog genes. The function of some of these genes is germline specific while others also act in somatic tissues. DEAD box proteins have been shown to be involved in the control of gene expression at different steps such as transcription and pre-mRNA processing.


RESULTS
We show that the Caenorhabditis elegans gene mel-46 (maternal effect lethal) encodes a DEAD box protein that is related to the mammalian DDX20/Gemin3/DP103 genes. mel-46 is expressed throughout development and mutations in mel-46 display defects at multiple developmental stages. Here we focus on the role of mel-46 in the hermaphrodite germ line. mel-46(yt5) mutant hermaphrodites are partially penetrant sterile and fully penetrant maternal effect lethal. The germ line of mutants shows variable defects in oogenesis. Further, mel-46(yt5) suppresses the complete feminization caused by mutations in fog-2 and fem-3, two genes that are at the top and the center, respectively, of the genetic germline sex determining cascade, but not fog-1 that is at the bottom of this cascade.


CONCLUSIONS
The C. elegans gene mel-46 encodes a DEAD box protein that is required maternally for early embryogenesis and zygotically for postembryonic development. In the germ line, it is required for proper oogenesis. Although it interacts genetically with genes of the germline sex determination machinery its primary function appears to be in oocyte differentiation rather than sex determination.
Minasaki
Ryuji
R
Max Planck Institute for Developmental Biology, Tübingen, Germany. minasaki@mpi-cbg.de
Puoti
Alessandro
A
Streit
Adrian
A
D000818:Animals; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005816:Genetic Complementation Test; D005854:Germ Cells / Q000378:metabolism* / Q000502:physiology; D008853:Microscopy; D008954:Models, Biological; D034622:RNA Interference; D019849:Sex Determination Processes
D029742:Caenorhabditis elegans Proteins; D053487:DEAD-box RNA Helicases