Celja Uebel

All Publications

• <i>Caenorhabditis</i><i> elegans</i> germ granules are present in distinct and assemble in a hierarchical manner DEVELOPMENT Uebel, C. J., Rajeev, S., Phillips, C. M. 2023; 150 (24)

  Abstract

  RNA silencing pathways are complex, highly conserved, and perform crucial regulatory roles. In Caenorhabditis elegans germlines, RNA surveillance occurs through a series of perinuclear germ granule compartments - P granules, Z granules, SIMR foci, and Mutator foci - multiple of which form via phase separation. Although the functions of individual germ granule proteins have been extensively studied, the relationships between germ granule compartments (collectively, 'nuage') are less understood. We find that key germ granule proteins assemble into separate but adjacent condensates, and that boundaries between germ granule compartments re-establish after perturbation. We discover a toroidal P granule morphology, which encircles the other germ granule compartments in a consistent exterior-to-interior spatial organization, providing broad implications for the trajectory of an RNA as it exits the nucleus. Moreover, we quantify the stoichiometric relationships between germ granule compartments and RNA to reveal discrete populations of nuage that assemble in a hierarchical manner and differentially associate with RNAi-targeted transcripts, possibly suggesting functional differences between nuage configurations. Our work creates a more accurate model of C. elegans nuage and informs the conceptualization of RNA silencing through the germ granule compartments.

  View details for DOI 10.1242/dev.202284

  View details for Web of Science ID 001165385300004

  View details for PubMedID 38009921

  View details for PubMedCentralID PMC10753583

• Caenorhabditis elegans germ granules are present in distinct configurations that differentially associate with RNAi-targeted RNAs. bioRxiv : the preprint server for biology Uebel, C. J., Rajeev, S., Phillips, C. M. 2023

  Abstract

  RNA silencing pathways are complex, highly conserved, and perform widespread, critical regulatory roles. In C. elegans germlines, RNA surveillance occurs through a series of perinuclear germ granule compartments-P granules, Z granules, SIMR foci, and Mutator foci-multiple of which form via phase separation and exhibit liquid-like properties. The functions of individual proteins within germ granules are well-studied, but the spatial organization, physical interaction, and coordination of biomolecule exchange between compartments within germ granule "nuage" is less understood. Here we find that key proteins are sufficient for compartment separation, and that the boundary between compartments can be reestablished after perturbation. Using super-resolution microscopy, we discover a toroidal P granule morphology which encircles the other germ granule compartments in a consistent exterior-to-interior spatial organization. Combined with findings that nuclear pores primarily interact with P granules, this nuage compartment organization has broad implications for the trajectory of an RNA as it exits the nucleus and enters small RNA pathway compartments. Furthermore, we quantify the stoichiometric relationships between germ granule compartments and RNA to reveal discrete populations of nuage that differentially associate with RNAi-targeted transcripts, possibly suggesting functional differences between nuage configurations. Together, our work creates a more spatially and compositionally accurate model of C. elegans nuage which informs the conceptualization of RNA silencing through different germ granule compartments.

  View details for DOI 10.1101/2023.05.25.542330

  View details for PubMedID 37292702

  View details for PubMedCentralID PMC10246010

• Epitope tag-specific differences in the detection of COSA-1 marked crossover sites in C. elegans spermatocytes. microPublication biology Cahoon, C. K., Uebel, C. J., Villeneuve, A. M., Libuda, D. E. 2023; 2023

  Abstract

  Nascent crossover sites in C. elegans meiocytes can be cytologically detected using epitope-tagged versions of the pro-crossover protein COSA-1. In spermatocytes, differences exist between cytologically-detected and genetically-detected double crossover rates. Here, we examine nascent crossovers using both GFP- and OLLAS-tagged COSA-1. Similar to previous work, we find that most late pachytene spermatocytes display 5 COSA-1 foci, indicating one crossover per autosome bivalent. However, we detected more nuclei with >5 COSA-1 foci using OLLAS::COSA-1, reflecting some bivalents having 2 COSA-1 foci. These results demonstrate tag-specific differences in the detection of COSA-1 marked nascent crossovers in spermatocytes.

  View details for DOI 10.17912/micropub.biology.000724

  View details for PubMedID 36660421