Search

Genetic triggers for sex determination are frequently co-inherited with other linked genes that may also influence one or more sex-specific phenotypes. To better understand how sex-limited regions evolve and function, we studied a small W chromosome-specific region of the frog Xenopus laevis that contains only three genes (dm-w, scan-w, ccdc69-w) and that drives female differentiation. Using gene editing, we found that the sex-determining function of this region requires dm-w but that scan-w and ccdc69-w are not essential for viability, female development, or fertility. Analysis of mesonephros+gonad transcriptomes during sexual differentiation illustrates masculinization of the dm-w knockout transcriptome, and identifies mostly non-overlapping sets of differentially expressed genes in separate knockout lines for each of these three W-specific gene compared to wildtype sisters. Capture sequencing of almost all Xenopus species and PCR surveys indicate that the female-determining function of dm-w is present in only a subset of species that carry this gene. These findings map out a dynamic evolutionary history of a newly evolved W chromosome-specific genomic region, whose components have distinctive functions that frequently degraded during Xenopus diversification, and evidence the evolutionary consequences of recombination suppression., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Cauret et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Abnormal spontaneous activity is a hallmark of acute or subacute denervation of skeletal muscle, particularly in patients with uremic neuropathy. We report 5 patients in whom such activity was unexpectedly minimal or absent.

Injuries to the lumbosacral plexus during labor and delivery have been reported in the literature for years, but have lacked electrophysiologic testing to substantiate the location of the nerve injury. We report 2 cases with comprehensive electrophysiologic testing which localizes the site of this obstetrical paralysis to the lumbosacral trunk (L4-5) and S-1 root where they join and pass over the pelvic rim. The paralysis may be mild or severe. Small maternal size, a large fetus, midforceps rotation, and fetal malposition may place the mother at risk for this nerve injury.

Although nuclear magnetic resonance has existed since the 1940s and was used extensively in chemistry labs for molecular structural determination, it was not until the 1970s that the possibility for magnetic resonance imaging (MRI) was realized. It is only in the last few years that the great potential of MRI to visualize the brain, joints and several other structures has been recognized. This article discusses some basic pathophysiology of cerebral ischemia as it relates to MRI and focuses on some of the advantages and disadvantages of MRI in visualizing and studying many of the resulting lesions.

Bilateral hip and femoral fractures are rare. A 26-year-old male with multiple injuries including such fractures was successfully treated with a variety of internal fixation techniques, allowing early mobilization. It is important to consider the possibility of this fracture pattern in high-energy trauma.