Perturbations of MicroRNA Function in Mouse Dicer Mutants Produce Retinal Defects and Lead to Aberrant Axon Pathfinding at the Optic Chiasm

During development axons encounter a variety of choice points where they have to make appropriate pathfinding decisions. The optic chiasm is a major decision point for retinal ganglion cell (RGC) axons en route to their target in order to ensure the correct wiring of the visual system. MicroRNAs (miRNAs) belong to the class of small non-coding RNA molecules and have been identified as important regulators of a variety of processes during embryonic development. However, their involvement in axon guidance decisions is less clear.We report here that the early loss of Dicer, an essential protein for the maturation of miRNAs, in all cells of the forming retina and optic chiasm leads to severe phenotypes of RGC axon pathfinding at the midline. Using a conditional deletion approach in mice, we find in homozygous Dicer mutants a marked increase of ipsilateral projections, RGC axons extending outside the optic chiasm, the formation of a secondary optic tract and a substantial number of RGC axons projecting aberrantly into the contralateral eye. In addition, the mutant mice display a microphthalmia phenotype.Our work demonstrates an important role of Dicer controlling the extension of RGC axons to the brain proper. It indicates that miRNAs are essential regulatory elements for mechanisms that ensure correct axon guidance decisions at the midline and thus have a central function in the establishment of circuitry during the development of the nervous system

A neuroscientist's guide to lipidomics

Nerve cells mould the lipid fabric of their membranes to ease vesicle fusion, regulate ion fluxes and create specialized microenvironments that contribute to cellular communication. The chemical diversity of membrane lipids controls protein traffic, facilitates recognition between cells and leads to the production of hundreds of molecules that carry information both within and across cells. With so many roles, it is no wonder that lipids make up half of the human brain in dry weight. The objective of neural lipidomics is to understand how these molecules work together; this difficult task will greatly benefit from technical advances that might enable the testing of emerging hypotheses

Síndrome da apneia obstrutiva do sono em motoristas de caminhão Obstructive sleep apnea syndrome in truck drivers

OBJETIVO: Estimar a prevalência da síndrome da apneia obstrutiva do sono (SAOS) e verificar os fatores associados à chance de desenvolver SAOS em motoristas de caminhão. MÉTODOS: A população desse estudo constituiu-se de motoristas de caminhão de duas filiais de uma empresa transportadora (n = 209), com idade média de 38,8 anos, sendo 98,5% do sexo masculino. O índice de massa corpórea médio foi de 26,5 ± 4,4 kg/m². Os participantes responderam questionários sobre dados sociodemográficos, atividade física e SAOS. A prevalência de SAOS foi estimada por meio do Questionário de Berlim e sua associação com os fatores estudados foi verificada pela análise de regressão univariada e multivariada. RESULTADOS: A prevalência de SAOS na população foi de 11,5%. Dos 209 motoristas, 72 (34,5%) referiram dormir ao volante enquanto dirigiam ao menos uma vez e 81 (38,7%) referiram roncar durante o sono. As variáveis estatisticamente significativas associadas à SAOS foram vínculo empregatício informal (OR = 0,27; p = 0,01), índice de massa corpórea > 25 kg/m² (OR = 13,64; p = 0,01) e qualidade do sono ruim (OR = 3,00; p = 0,02). CONCLUSÕES: Apesar de a prevalência de SAOS ter sido inferior à observada em outros estudos com motoristas, essa prevalência é superior à da população em geral. Os resultados ainda sugerem que as características do trabalho, entre as quais o vínculo de trabalho, estão associadas à SAOS. Esses dados evidenciam a relevância de se levar em consideração a atividade de trabalho em estudos que investiguem fatores associados à SAOS.<br>OBJECTIVE: To determine the prevalence of obstructive sleep apnea syndrome (OSAS), as well as to identify factors associated with a greater risk of developing OSAS, among truck drivers. METHODS: The study population comprised 209 truck drivers (mean age, 38.8 years; 98.5% males) at two branches of a transportation company. The mean body mass index was 26.5 ± 4.4 kg/m². The participants completed questionnaires regarding sociodemographic data, physical activity and OSAS. The prevalence of OSAS was estimated using the Berlin Questionnaire, associations between OSAS and the factors studied being assessed through univariate and multivariate regression analysis. RESULTS: The prevalence of OSAS in the population was 11.5%. Of the 209 truck drivers, 72 (34.5%) reported having fallen asleep while driving and 81 (38.7%) reported snoring. The following variables were found to present statistically significant associations with OSAS: informal employment (OR = 0.27; p = 0.01); body mass index > 25 kg/m² (OR = 13.64; p = 0.01); and poor sleep quality (OR = 3.00; p = 0.02). CONCLUSIONS: The prevalence of OSAS in this study was lower than that reported in other studies of truck drivers and yet higher that that observed for the general population. In addition, our results suggest that work characteristics, such as employment status, are associated with OSAS. These data show the relevance of considering work activity in studies of factors associated with OSAS