Corticosterone and testosterone treatment influence expression of gene pathways linked to meiotic segregation in preovulatory follicles of the domestic hen.

Decades of work indicate that female birds can control their offspring sex ratios in response to environmental and social cues. In laying hens, hormones administered immediately prior to sex chromosome segregation can exert sex ratio skews, indicating that these hormones may act directly on the germinal disc to influence which sex chromosome is retained in the oocyte and which is discarded into an unfertilizable polar body. We aimed to uncover the gene pathways involved in this process by testing whether treatments with testosterone or corticosterone that were previously shown to influence sex ratios elicit changes in the expression of genes and/or gene pathways involved in the process of meiotic segregation. We injected laying hens with testosterone, corticosterone, or control oil 5h prior to ovulation and collected germinal discs from the F1 preovulatory follicle in each hen 1.5h after injection. We used RNA-sequencing (RNA-seq) followed by DESeq2 and gene set enrichment analyses to identify genes and gene pathways that were differentially expressed between germinal discs of control and hormone-treated hens. Corticosterone treatment triggered downregulation of 13 individual genes, as well as enrichment of gene sets related to meiotic spindle organization and chromosome segregation, and additional gene sets that function in ion transport. Testosterone treatment triggered upregulation of one gene, and enrichment of one gene set that functions in nuclear chromosome segregation. This work indicates that corticosterone can be a potent regulator of meiotic processes and provides potential gene targets on which corticosterone and/or testosterone may act to influence offspring sex ratios in birds.

Incidence, Positional Distribution, Severity, and Time Missed in Medial Collateral Ligament Injuries of the Knee in NCAA Division I Football Athletes.

INTRODUCTION: We studied injury to the medial collateral ligament (MCL) in National Collegiate Athletic Association (NCAA) Division I football players, their incidence, magnitude of injury, distribution by position, and missed time, which has not previously been described in a consecutive series. METHODS: The knee injuries sustained in 163 consecutive NCAA Division I collegiate football players at our institution were evaluated over a span of 6 years. RESULTS: The incidence of MCL injuries with any knee injury was 29% (47 of 163). Of 47 MCL injuries, 34% occurred in defensive linemen and 29% in offensive linemen. The average days missed by linemen were 14.65 compared with 4.5 by nonlinemen (P = 0.07). The MCL injuries in linemen were more severe than nonlinemen (0.018). DISCUSSION: MCL injuries occur most commonly in linemen in whom the magnitude of injury is also more significant than nonlinemen. Linemen miss more days than do nonlinemen to MCL injury. STUDY DESIGN: Descriptive Epidemiology Study.