N-Cadherin Expression Level Distinguishes Reserved versus Primed States of Hematopoietic Stem Cells

SummaryOsteoblasts expressing the homophilic adhesion molecule N-cadherin form a hematopoietic stem cell (HSC) niche. Therefore, we examined how N-cadherin expression in HSCs relates to their function. We found that bone marrow (BM) cells highly expressing N-cadherin (N-cadherinhi) are not stem cells, being largely devoid of a Lineage−Sca1+cKit+ population and unable to reconstitute hematopoietic lineages in irradiated recipient mice. Instead, long-term HSCs form distinct populations expressing N-cadherin at intermediate (N-cadherinint) or low (N-cadherinlo) levels. The minority N-cadherinlo population can robustly reconstitute the hematopoietic system, express genes that may prime them to mobilize, and predominate among HSCs mobilized from BM to spleen. The larger N-cadherinint population performs poorly in reconstitution assays when freshly isolated but improves in response to overnight in vitro culture. Their expression profile and lower cell-cycle entry rate suggest N-cadherinint cells are being held in reserve. Thus, differential N-cadherin expression reflects functional distinctions between two HSC subpopulations

DNA cleavage site selection by Type III restriction enzymes provides evidence for head-on protein collisions following 1D bidirectional motion

DNA cleavage by the Type III Restriction–Modification enzymes requires communication in 1D between two distant indirectly-repeated recognitions sites, yet results in non-specific dsDNA cleavage close to only one of the two sites. To test a recently proposed ATP-triggered DNA sliding model, we addressed why one site is selected over another during cleavage. We examined the relative cleavage of a pair of identical sites on DNA substrates with different distances to a free or protein blocked end, and on a DNA substrate using different relative concentrations of protein. Under these conditions a bias can be induced in the cleavage of one site over the other. Monte-Carlo simulations based on the sliding model reproduce the experimentally observed behaviour. This suggests that cleavage site selection simply reflects the dynamics of the preceding stochastic enzyme events that are consistent with bidirectional motion in 1D and DNA cleavage following head-on protein collision

Assessment of cognitive biases in Augmented Reality: Beyond eye tracking.

We study an individual’s propensity for rational thinking; the avoidance of cognitive biases (unconscious errors generated by our mental simplification methods) using a novel augmented reality (AR) platform. Specifically, we developed an odd-one-out game-like task in AR designed to try to induce and assess confirmatory biases. Forty students completed the AR task in the laboratory, and the short form of the comprehensive assessment of rational thinking (CART) online via the Qualtrics platform. We used distance correlation approaches and stepwise regression to identify objective markers (based on eye, hand and head movements) associated with the psychometric measures of propensity for rational thinking. We show that the proposed markers are associated with the short CART score – more rational thinkers have slower head and hand movements, faster gaze movements and more consistent hand-eye-head coordination patterns across conditions

Anthropogenic pressure on large carnivores and their prey in the highly threatened forests of Tanintharyi, southern Myanmar

The Tanintharyi Region in southern Myanmar is rich in biodiversity yet is facing threats from varying degrees of anthropogenic pressure. In this research we examine how anthropogenic pressures are influencing large carnivores (tiger Panthera tigris, leopard Panthera pardus and dhole Cuon alpinus) and their major prey species (wild pig Sus scrofa, muntjac Muntiacus spp., sambar Rusa unicolor, gaur Bos gaurus and banteng Bos javanicus) in the Lenya Reserved Forest and adjacent areas of Sundaic forest. We used data from camera-trap surveys during May – March and logistic regression to analyse the relationships between the presence of large carnivores and explanatory variables such as human disturbance, landscape variability and changes in prey distribution. Tiger presence was positively associated with the occurrence of gaur and distance to villages. The occurrence of prey did not explain the detection of leopards in the study area. We suspect this was because leopards have a broad diet, including arboreal primates, and their prey was not fully recorded in our cameratrap survey. Dholes were positively associated with wild pigs and the total number of prey but not associated with forest type and landscape variables. To restore the carnivore population and conserve the biodiversity of this area, effective protection of predators and habitat management for large ungulates are crucial. Camera trap, dhole, human disturbance, hunting, leopard, Myanmar, palm oil, tigerpublishedVersio

Rapid forest clearing in a Myanmar proposed national park threatens two newly discovered species of geckos (Gekkonidae: Cyrtodactylus).

Myanmar's recent transition from military rule towards a more democratic government has largely ended decades of political and economic isolation. Although Myanmar remains heavily forested, increased development in recent years has been accompanied by exceptionally high rates of forest loss. In this study, we document the rapid progression of deforestation in and around the proposed Lenya National Park, which includes some of the largest remaining areas of lowland evergreen rainforest in mainland Southeast Asia. The globally unique forests in this area are rich in biodiversity and remain a critical stronghold for many threatened and endangered species, including large charismatic fauna such as tiger and Asian elephant. We also conducted a rapid assessment survey of the herpetofauna of the proposed national park, which resulted in the discovery of two new species of bent-toed geckos, genus Cyrtodactylus. We describe these new species, C. lenya sp. nov. and C. payarhtanensis sp. nov., which were found in association with karst (i.e., limestone) rock formations within mature lowland wet evergreen forest. The two species were discovered less than 35 km apart and are each known from only a single locality. Because of the isolated nature of the karst formations in the proposed Lenya National Park, these geckos likely have geographical ranges restricted to the proposed protected area and are threatened by approaching deforestation. Although lowland evergreen rainforest has vanished from most of continental Southeast Asia, Myanmar can still take decisive action to preserve one of the most biodiverse places on Earth

Birds of Mondulkiri, Cambodia: distribution, status and conservation

Volume: 30Start Page: 66End Page: 7

Photo of <i>Cyrtodactylus lenya</i> sp. nov., USNM 587789 paratype (photo by Daniel G. Mulcahy).

<p>Photo of <i>Cyrtodactylus lenya</i> sp. nov., USNM 587789 paratype (photo by Daniel G. Mulcahy).</p