The Drosophila Nucleoplasmin-like protein (Nlp) is essential for germline development

Abstract

The life cycle of sexually reproducing organisms relies on the distinct development of germ cells. Specialized ribonucleoprotein assemblies called germline granules are essential for this development across the animal kingdom, as they facilitate the inheritance, storage, and regulation of RNAs to establish a unique gene expression profile. In Drosophila, different types of germline granules have been described at various stages of development, from gametogenesis through specification of the primordial germ cells (PGCs) in early embryogenesis. While granules are known to exist throughout embryogenesis, their role during the late stages remains unclear. I investigate this function by knocking down several transcripts that have localization patterns consistent with late-stage embryonic granules. I show that Nucleoplasmin-like protein (Nlp) is essential for germline development, beginning with PGC migration and gonad formation and persisting through gamete production. Ultimately, disrupting Nlp function results in sex-independent infertility. I also find that Nlp localizes in puncta in the gonadal germ cells that are distinct from previously described germline granules. These results suggest that new, Nlp-containing germline granules are critical for germline development during the late stages of embryogenesis, establishing a continuum of germline granules throughout the Drosophila life cycle.