Online Courses Provide Robust Learning Gains and Improve Learner Confidence in the Foundational Biomedical Sciences.

The early stages of medical school involve education in a number of foundational biomedical sciences including genetics, immunology, and physiology. However, students entering medical school may have widely varying levels of background in these areas due to differences in the availability and quality of prior education on these topics. Even students who have recently taken formal courses in these subjects may not feel confident in their level of preparation, leading to anxiety for early-stage medical students. These differences can make it difficult for instructors to create meaningful learning experiences that are appropriate for all students. Additionally, actual or perceived differences in preparation may lead fewer students from diverse backgrounds to apply to medical school. Therefore, creating an efficient and scalable way to increase students' knowledge and confidence in these topics addresses an important need for many medical schools. We recorded pre- and post-course quiz scores for 9790 individuals who completed HMX online courses, developed in accordance with evidence-based learning practices and covering the fundamentals of biochemistry, genetics, immunology, pharmacology, and physiology. Each question was accompanied by a Likert scale question to assess the learner's confidence in their answer. Learners' median post-course quiz performance and self-assessed confidence significantly increased relative to pre-course quiz performance for each course. Improvements were consistent across US-based medical schools, non-US medical schools, and course runs open to the public. This indicates that online courses created using evidence-based learning practices can lead to significant increases in knowledge and confidence for many learners, helping prepare them for further medical education. Supplementary Information: The online version contains supplementary material available at 10.1007/s40670-022-01660-4.

Identifying Metabolic Subpopulations from Population Level Mass Spectrometry.

Metabolism underlies many important cellular decisions, such as the decisions to proliferate and differentiate, and defects in metabolic signaling can lead to disease and aging. In addition, metabolic heterogeneity can have biological consequences, such as differences in outcomes and drug susceptibilities in cancer and antibiotic treatments. Many approaches exist for characterizing the metabolic state of a population of cells, but technologies for measuring metabolism at the single cell level are in the preliminary stages and are limited. Here, we describe novel analysis methodologies that can be applied to established experimental methods to measure metabolic variability within a population. We use mass spectrometry to analyze amino acid composition in cells grown in a mixture of (12)C- and (13)C-labeled sugars; these measurements allow us to quantify the variability in sugar usage and thereby infer information about the behavior of cells within the population. The methodologies described here can be applied to a large range of metabolites and macromolecules and therefore have the potential for broad applications.

Spt6 regulates intragenic and antisense transcription, nucleosome positioning, and histone modifications genome-wide in fission yeast.

Spt6 is a highly conserved histone chaperone that interacts directly with both RNA polymerase II and histones to regulate gene expression. To gain a comprehensive understanding of the roles of Spt6, we performed genome-wide analyses of transcription, chromatin structure, and histone modifications in a Schizosaccharomyces pombe spt6 mutant. Our results demonstrate dramatic changes to transcription and chromatin structure in the mutant, including elevated antisense transcripts at >70% of all genes and general loss of the +1 nucleosome. Furthermore, Spt6 is required for marks associated with active transcription, including trimethylation of histone H3 on lysine 4, previously observed in humans but not Saccharomyces cerevisiae, and lysine 36. Taken together, our results indicate that Spt6 is critical for the accuracy of transcription and the integrity of chromatin, likely via its direct interactions with RNA polymerase II and histones.

Mutations in LYRM4, encoding iron-sulfur cluster biogenesis factor ISD11, cause deficiency of multiple respiratory chain complexes.

Iron-sulfur clusters (ISCs) are important prosthetic groups that define the functions of many proteins. Proteins with ISCs (called iron-sulfur or Fe-S proteins) are present in mitochondria, the cytosol, the endoplasmic reticulum and the nucleus. They participate in various biological pathways including oxidative phosphorylation (OXPHOS), the citric acid cycle, iron homeostasis, heme biosynthesis and DNA repair. Here, we report a homozygous mutation in LYRM4 in two patients with combined OXPHOS deficiency. LYRM4 encodes the ISD11 protein, which forms a complex with, and stabilizes, the sulfur donor NFS1. The homozygous mutation (c.203G>T, p.R68L) was identified via massively parallel sequencing of >1000 mitochondrial genes (MitoExome sequencing) in a patient with deficiency of complexes I, II and III in muscle and liver. These three complexes contain ISCs. Sanger sequencing identified the same mutation in his similarly affected cousin, who had a more severe phenotype and died while a neonate. Complex IV was also deficient in her skeletal muscle. Several other Fe-S proteins were also affected in both patients, including the aconitases and ferrochelatase. Mutant ISD11 only partially complemented for an ISD11 deletion in yeast. Our in vitro studies showed that the l-cysteine desulfurase activity of NFS1 was barely present when co-expressed with mutant ISD11. Our findings are consistent with a defect in the early step of ISC assembly affecting a broad variety of Fe-S proteins. The differences in biochemical and clinical features between the two patients may relate to limited availability of cysteine in the newborn period and suggest a potential approach to therapy.