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Germ cells are the cells that give rise to the reproductive cells of sexually reproducing organisms – known as gametes – through a process called gametogenesis. In animals, the reproductive male gametes are sperm cells and the female gametes the oocytes.
The Nanos family protein, NANOS2, is required for sexual differentiation of male germ cells in mice, however, the molecular RNA targets are unknown. Here, Kato et al. identify Dazl, a germ cell-specific gene, as being a target of NANOS, with stabilized Dazl mRNA causing abnormal resumption of the cell cycle.
Recent studies in different species have increased our understanding of the factors and molecular mechanisms that underlie the specification of germ cells, which are the specialized cells that generate gametes. Moreover, studies are elucidating how these cells ensure that only germline-appropriate transcripts are translated to protect germ cell identity.
Damage to maternal DNA during meosis can lead to birth defects, abortion or infertility. Here, the authors show that the spindle assembly checkpoint can respond to DNA damage in oocytes by blocking anaphase promoting complex activity and arresting oocytes in meiosis I.
The E3 ubiquitin ligase CRL4 regulates oocyte survival through hydroxymethylation of genomic DNA. Here Yu et al. show that CRL4 is also required for oocytes to complete meiosis I by mediating the poly-ubiquitination and proteasomal degradation of the cell cycle regulator protein phosphatase 2A-A subunit.
What regulates mRNAs transcript localization in the germ granules in Drosophila is unclear. Here Trcek et al. identify that germ plasm proteins are homogeneously distributed in germ granules but once localized, individual mRNAs form homotypic clusters, contributing structure to the germ granules.
As oocytes age the frequency of chromosome segregation errors during meiosis I increases. Here the authors use live imaging of oocytes from naturally aged mice to provide direct evidence that bivalent separation into univalents is the primary defect responsible for age-related aneuploidy.
Daniel Gerlich discusses how a study by the Hyman laboratory introduced the theory of liquid phase separation to cell biology and its implications for the understanding of cell organization and function.