Gcn5-Mediated Histone Acetylation Governs Nucleosome Dynamics in Spermiogenesis.

During mammalian spermatogenesis, germ cell chromatin undergoes dramatic histone acetylation-mediated reorganization, whereby 90%-99% of histones are evicted. Given the potential role of retained histones in fertility and embryonic development, the genomic location of retained nucleosomes is of great interest. However, the ultimate position and mechanisms underlying nucleosome eviction or retention are poorly understood, including several studies utilizing micrococcal-nuclease sequencing (MNase-seq) methodologies reporting remarkably dissimilar locations. We utilized assay for transposase accessible chromatin sequencing (ATAC-seq) in mouse sperm and found nucleosome enrichment at promoters but also retention at inter- and intragenic regions and repetitive elements. We further generated germ-cell-specific, conditional knockout mice for the key histone acetyltransferase Gcn5, which resulted in abnormal chromatin dynamics leading to increased sperm histone retention and severe reproductive phenotypes. Our findings demonstrate that Gcn5-mediated histone acetylation promotes chromatin accessibility and nucleosome eviction in spermiogenesis and that loss of histone acetylation leads to defects that disrupt male fertility and potentially early embryogenesis.

Riesgos laborales en trabajadores de barberías y peluquerías de economía informal: Caracas, Venezuela / Occupational hazards in barbershops and hairdressers workers of informal economy: Caracas, Venezuela

En Venezuela el sector informal de barberías y peluquerías constituye una fuente de absorción de mano de obra desocupada, que tiene algunas ventajas respecto a ingresos y flexibilización laboral, pero por otro lado es un sector desprotegido y con accesos limitados o nulos a servicios de seguridad y salud laboral, lo que dificulta la inclusión en programas de prevención de accidentes de trabajo y enfermedades ocupacionales. En este estudio observacional transversal y descriptivo se aplicó "la encuesta de las condiciones de trabajo y salud en América Latina del Center for International Health" y se analizaron las actividades de 40 trabajadores de barberías y peluquerías: 50% del género masculino y 50% femenino, 85% con edades comprendidas entre 20-49 años. De ellos, 65% manipulaban productos químicos, 62,5% utilizaban el secador y/o máquina de afeitar, 87,5% habían sufrido al menos una lesión en su área de trabajo y 100% refirió adoptar bipedestación prolongada, hacer movimientos repetitivos y presentar algún tipo de trastorno músculo-esquelético, cuyos síntomas más frecuentes fueron dorsalgias y lumbalgias con 37,5% y 32,5% respectivamente. Por otro lado, las várices en miembros inferiores fueron la segunda causa de morbilidad reportada.

Some of the barbershops and hair saloons -belonging to the informal sector- are a source of employment which takes in unoccupied work force. This workers have some advantages concerning to income and work flexibility, but in the other hand it is an unprotected sector with limited or nonexistent access to Occupational, Safety and Health services. This situation makes difficult to include them in labor accident occupational disease prevention programs. A cross-sectional and descriptive study was carried out in which 40 barbershop and hair saloon workers were surveyed. Their activities were analyzed, employing the "survey of work and health conditions in Latin America of the Center for International Health". Of these workers, 50% were male and 50% female, and 85% were between 20 to 49 years old. 65% used chemical products, 62,5% used hair dryers and/or shaving machines, 87,5% had suffered some form of workplace injury, and all of them admitted to have adopted prolonged standing postures, to make repetitive movements, suffering at least from any musculoskeletal disorder. The second disease reported were varicose veins.