Human TUBB3 mutations perturb microtubule dynamics, kinesin interations, and axon guidance

We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific β-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals. © 2010 Elsevier Inc. All rights reserved

The ecology of environmental DNA and implications for conservation genetics

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.Environmental DNA (eDNA) refers to the genetic material that can be extracted from bulk environmental samples such as soil, water, and even air. The rapidly expanding study of eDNA has generated unprecedented ability to detect species and conduct genetic analyses for conservation, management, and research, particularly in scenarios where collection of whole organisms is impractical or impossible. While the number of studies demonstrating successful eDNA detection has increased rapidly in recent years, less research has explored the “ecology” of eDNA—myriad interactions between extraorganismal genetic material and its environment—and its influence on eDNA detection, quantification, analysis, and application to conservation and research. Here, we outline a framework for understanding the ecology of eDNA, including the origin, state, transport, and fate of extraorganismal genetic material. Using this framework, we review and synthesize the findings of eDNA studies from diverse environments, taxa, and fields of study to highlight important concepts and knowledge gaps in eDNA study and application. Additionally, we identify frontiers of conservation-focused eDNA application where we see the most potential for growth, including the use of eDNA for estimating population size, population genetic and genomic analyses via eDNA, inclusion of other indicator biomolecules such as environmental RNA or proteins, automated sample collection and analysis, and consideration of an expanded array of creative environmental samples. We discuss how a more complete understanding of the ecology of eDNA is integral to advancing these frontiers and maximizing the potential of future eDNA applications in conservation and research

The Early Treatment for Retinopathy Of Prematurity Study: structural findings at age 2 years

OBJECTIVE: To determine whether earlier treatment of high‐risk, prethreshold retinopathy of prematurity (ROP) improves retinal structural outcome at 2 years of age. METHODS: Infants with bilateral high‐risk prethreshold ROP had one eye randomly assigned to treatment with peripheral retinal ablation. The fellow eye was managed conventionally, and either treated at threshold ROP or observed if threshold was never reached. In patients with asymmetrical disease, the high‐risk, prethreshold eye was randomised to earlier treatment or to conventional management. At 2 years of age, children were examined comprehensively by certified ophthalmologists to determine structural outcomes for their eyes. For the purposes of this study, an unfavourable structural outcome was defined as (1) a posterior retinal fold involving the macula, (2) a retinal detachment involving the macula or (3) retrolental tissue or “mass” obscuring the view of the posterior pole. Results of the 2‐year examination were compared with those from the 9 months examination. RESULTS: Data were available on 339 of 374 (90.6%) surviving children. Unfavourable structural outcomes were reduced from 15.4% in conventionally managed eyes to 9.1% in earlier‐treated eyes (p = 0.002) at 2 years of age. Ophthalmic side effects (excluding retinal structure) from the ROP or its treatment were similar in the earlier‐treated eyes and the conventionally managed eyes. CONCLUSION: The benefit of earlier treatment of high‐risk prethreshold ROP on retinal structure endures to 2 years of age, and is not counterbalanced by any known side effect caused by earlier intervention. Earlier treatment improves the chance for long‐term favourable retinal structural outcome in eyes with high‐risk prethreshold ROP. Long‐term follow‐up is planned to determine structural and functional outcomes at 6 years of age