Comparative ecological dynamics of Permian-Triassic communities from the Karoo, Luangwa, and Ruhuhu Basins of southern Africa

<p>The Permian-Triassic mass extinction (PTME) was one of the transformative events of the Phanerozoic, marked by extinction, post-Permian transformation of surviving ecosystems, and the formation of new communities. The South African Karoo Basin has served as the primary source of data on the terrestrial component of these events, but its global applicability remains poorly known. Here, we compare Permian-Triassic communities of the Karoo Basin with those from the Luangwa and Ruhuhu basins of Zambia and Tanzania, respectively, analyzing their functional structures and simulating dynamic responses to environmental perturbation. Results show that compositional similarities of late Permian communities among the basins underlie similarities in their dynamics and resistance to secondary extinction. The Karoo Basin ecosystem also displays evidence of a transformation to increased resistance during the late Permian. Although the Karoo Basin ecosystem was reduced significantly by the PTME, structural features of that resistance persisted into the Early Triassic, facilitated by a greater susceptibility to extinction of small-body-sized amniotes and large carnivorous amniotes. It was undone by the initial stages of postextinction restructuring. Continued evolution of the Triassic ecosystem led to a recovery of resistance, but in a community compositionally dissimilar from its Permian antecedents. Likewise, the upper part of the Lifua Member of the Manda Beds (Middle Triassic) of Tanzania was structurally distinct from the Karoo Basin communities but displayed similar dynamics. The recurrence and convergence of communities with different histories toward similar dynamics suggest that there are taxon-independent norms of community assembly and function operating on geological timescales.</p> <p>SUPPLEMENTAL DATA—Supplemental materials are available for this article for free at <a href="http://www.tandfonline.com/UJVP" target="_blank">www.tandfonline.com/UJVP</a></p> <p>Citation for this article: Roopnarine, P. D., K. D. Angielczyk, S. Olroyd, S. J. Nesbitt, J. Botha-Brink, B. R. Peecook, M. O. Day, and R. M. H. Smith. 2018. Comparative ecological dynamics of Permian-Triassic communities from the Karoo, Luangwa, and Ruhuhu basins of southern Africa; pp. 254–272 in C. A. Sidor and S. J. Nesbitt (eds.), Vertebrate and Climatic Evolution in the Triassic Rift Basins of Tanzania and Zambia. Society of Vertebrate Paleontology Memoir 17. Journal of Vertebrate Paleontology 37(6, Supplement).</p

Hypoimmune induced pluripotent stem cells survive long term in fully immunocompetent, allogeneic rhesus macaques

Genetic engineering of allogeneic cell therapeutics that fully prevents rejection by a recipient's immune system would abolish the requirement for immunosuppressive drugs or encapsulation and support large-scale manufacturing of off-the-shelf cell products. Previously, we generated mouse and human hypoimmune pluripotent (HIP) stem cells by depleting HLA class I and II molecules and overexpressing CD47 (B2M-/-CIITA-/-CD47+). To determine whether this strategy is successful in non-human primates, we engineered rhesus macaque HIP cells and transplanted them intramuscularly into four allogeneic rhesus macaques. The HIP cells survived unrestricted for 16 weeks in fully immunocompetent allogeneic recipients and differentiated into several lineages, whereas allogeneic wild-type cells were vigorously rejected. We also differentiated human HIP cells into endocrinologically active pancreatic islet cells and showed that they survived in immunocompetent, allogeneic diabetic humanized mice for 4 weeks and ameliorated diabetes. HIP-edited primary rhesus macaque islets survived for 40 weeks in an allogeneic rhesus macaque recipient without immunosuppression, whereas unedited islets were quickly rejected

Active learning narrows achievement gaps for underrepresented students in undergraduate science, technology, engineering, and math.

We tested the hypothesis that underrepresented students in active-learning classrooms experience narrower achievement gaps than underrepresented students in traditional lecturing classrooms, averaged across all science, technology, engineering, and mathematics (STEM) fields and courses. We conducted a comprehensive search for both published and unpublished studies that compared the performance of underrepresented students to their overrepresented classmates in active-learning and traditional-lecturing treatments. This search resulted in data on student examination scores from 15 studies (9,238 total students) and data on student failure rates from 26 studies (44,606 total students). Bayesian regression analyses showed that on average, active learning reduced achievement gaps in examination scores by 33% and narrowed gaps in passing rates by 45%. The reported proportion of time that students spend on in-class activities was important, as only classes that implemented high-intensity active learning narrowed achievement gaps. Sensitivity analyses showed that the conclusions are robust to sampling bias and other issues. To explain the extensive variation in efficacy observed among studies, we propose the heads-and-hearts hypothesis, which holds that meaningful reductions in achievement gaps only occur when course designs combine deliberate practice with inclusive teaching. Our results support calls to replace traditional lecturing with evidence-based, active-learning course designs across the STEM disciplines and suggest that innovations in instructional strategies can increase equity in higher education