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The Aurora Kinases (AURKs) are a family of serine-threonine protein kinases critical for cell division. Somatic cells express only AURKA and AURKB. However, mammalian germ cells and some cancer cells express all three isoforms. A major question in the field has been determining the molecular and cellular changes when cells express three instead of two aurora kinases. Using a systematic genetic approach involving different Aurora kinase oocyte-specific knockout combinations, we completed an oocyte-AURK genetic interaction map and show that one genomic copy of Aurka is necessary and sufficient to support female fertility and oocyte meiosis. We further confirm that AURKB and AURKC alone cannot compensate for AURKA. These results highlight the importance of AURKA in mouse oocytes, demonstrating that it is required for spindle formation and proper chromosome segregation. Surprisingly, a percentage of oocytes that lack AURKB can complete meiosis I, but the quality of those eggs is compromised, suggesting a role in AURKB to regulate spindle assembly checkpoint or control the cell cycle. Together with our previous studies, we wholly define the genetic interplay among the Aurora kinases and reinforce the importance of AURKA expression in oocyte meiosis. [ABSTRACT FROM AUTHOR]

Understanding pre- and post-copulatory mechanisms of sexual selection can provide insights into the evolution of male reproductive strategies. The phenotype-linked fertility hypothesis postulates that male sperm quality and secondary sexual characteristics will positively co-vary, whereas the sperm competition hypothesis predicts a negative association between those traits. Male reproductive traits often show variation throughout the reproductive period, suggesting that the relationship between pre- and post-copulatory sexual selection may vary temporally. Here, we evaluated the relationship between secondary sexual character and sperm traits and its temporal variation in Salvator rufescens, a south American lizard. We observed a negative relationship between jaw muscle and principal piece length of sperm and a variation in the relationship between pre- and post-copulatory traits throughout the reproductive period. Collectively, our results evidenced a trade-off between pre- and post-copulatory traits and a strong seasonal flexibility of male reproductive strategies in this lizard species. [ABSTRACT FROM AUTHOR]

The reproductive traits of males are under influence of sexual pressures before and after copulation. The strength of sexual selection varies across populations because they undergo varying competition for mating opportunities. Besides intraspecific pressures, individuals seem to be subjected to pressures driven by interspecific interactions in sympatry. Lizards may vary their reproductive strategies through varying sexual characters, body size, gonadal investment, and sperm traits. We evaluated the reproductive traits, involved in pre- and postcopulatory competition, in allopatric and sympatric populations of Salvator lizards. We observed a spatial gradient of male competition among populations, with the following order: allopatric zone of S. rufescens; sympatric zone; and allopatric zone of S. merianae. Accordingly, variation in secondary sexual character, the relative testis mass, and the length of sperm component was observed between allopatry and sympatry in each species, suggesting differences in the investment of reproductive traits. However, we found that these two Salvator species did not differ in secondary sexual characters in sympatry. Interestingly, the trade-off between testes and muscle varied differently from allopatry to sympatry between these Salvator species, suggesting that the influence of social context on reproductive traits investment would affect lizard species differently. [ABSTRACT FROM AUTHOR]

The human genome contains 24 gag -like capsid genes derived from deactivated retrotransposons conserved among eutherians. Although some of their encoded proteins retain the ability to form capsids and even transfer cargo, their fitness benefit has remained elusive. Here we show that the gag -like genes PNMA1 and PNMA4 support reproductive capacity during aging. Analysis of donated human ovaries shows that expression of both genes declines normally with age, while several PNMA1 and PNMA4 variants identified in genome-wide association studies are causally associated with low testosterone, altered puberty onset, or obesity. Six-week-old mice lacking either Pnma1 or Pnma4 are indistinguishable from wild-type littermates, but by six months the mutant mice become prematurely subfertile, with precipitous drops in sex hormone levels, gonadal atrophy, and abdominal obesity; overall they produce markedly fewer offspring than controls. These findings expand our understanding of factors that maintain human reproductive health and lend insight into the domestication of retrotransposon-derived genes., Competing Interests: DECLARATION OF INTERESTS T.W.P.W., H.B.C, and L.E.B. are co-inventors on a US provisional patent application filed by the Columbia University related to this work. (U.S. Provisional Patent Application no. 63/546,397). B.W. is the founder of SurGene LLC and inventor on patent applications related to CRISPR–Cas systems and applications thereof. All other authors declare no competing interests.

Immunofluorescence is a useful technique for analysis of protein expression and localization, thereby providing information regarding protein function, regulation, and protein-protein interactions. It is a standard approach to determine the temporal and spatial location of gene products that function in oocyte meiotic maturation. Fixation is one of the critical steps in the immunofluorescence protocol. Here, we describe the use of antibodies that are widely utilized in oocytes studies: anti-centromeric antigen (ACA), anti-Aurora kinase A (AURKA) and anti-alpha and gamma-tubulin antibodies that require different technical approaches for successful visualization, and we provide protocols for these conditions that are amenable to mouse oocyte studies. Detection of these proteins provides phenotypic information about spindle morphology, chromosome alignment, and microtubule attachments to kinetochores critical to assessing oocyte quality.