Remodeling of the endoplasmic reticulum in Caenorhabditis elegans oocytes is regulated by CGH-1.

A key aspect of development in all metazoans is remodeling at the cellular level. During the development of gametes, remodeling occurs throughout the germ line. When Caenorhabditis elegans hermaphrodites become depleted of sperm after 4 days of adulthood, significant cellular remodeling occurs within the meiotically-arrested oocytes, including the formation of ribonucleoprotein granules.

Biphasic adaptation to osmotic stress in the germ line.

Cells respond to environmental stress in multiple ways. In the germ line, heat shock and nutritive stress trigger the assembly of large ribonucleoprotein (RNP) granules via liquid-liquid phase separation (LLPS). The RNP granules are hypothesized to maintain the quality of oocytes during stress.

RNAi Screen Identifies Novel Regulators of RNP Granules in the Caenorhabditis elegans Germ Line.

Complexes of RNA and RNA binding proteins form large-scale supramolecular structures under many cellular contexts. In Caenorhabditis elegans, small germ granules are present in the germ line that share characteristics with liquid droplets that undergo phase transitions. In meiotically-arrested oocytes of middle-aged hermaphrodites, the germ granules appear to aggregate or condense into large assemblies of RNA-binding proteins and maternal mRNAs.

Assembly of RNP granules in stressed and aging oocytes requires nucleoporins and is coordinated with nuclear membrane blebbing.

Protective cellular responses to stress and aging in the germline are essential for perpetuation of a species; however, relatively few studies have focused on how germ cells respond to stress and aging. We have previously shown that large ribonucleoprotein (RNP) complexes assemble in oocytes of Caenorhabditis during extended meiotic arrest or after environmental stress. Here we explore the regulation of these dynamic RNPs and demonstrate their assembly is coordinated with dramatic, nuclear membrane blebbing in oocytes.

Large P body-like RNPs form in C. elegans oocytes in response to arrested ovulation, heat shock, osmotic stress, and anoxia and are regulated by the major sperm protein pathway.

As Caenorhabditis elegans hermaphrodites age, sperm become depleted, ovulation arrests, and oocytes accumulate in the gonad arm. Large ribonucleoprotein (RNP) foci form in these arrested oocytes that contain RNA-binding proteins and translationally masked maternal mRNAs. Within 65 min of mating, the RNP foci dissociate and fertilization proceeds.