Universidade Federal de Minas Gerais

About: Universidade Federal de Minas Gerais is a education organization based out in Belo Horizonte, Minas Gerais, Brazil. It is known for research contribution in the topics: Population & Context (language use). The organization has 41631 authors who have published 75688 publications receiving 1249905 citations.

Histological and Stereological Evaluation of Zebrafish (Danio rerio) Spermatogenesis with an Emphasis on Spermatogonial Generations

Abstract: The zebrafish has become an important vertebrate model for basic and biomedical research, including the research field of the biology of reproduction. However, very few morphological and stereological data are available regarding zebrafish testis structure and spermatogenesis. In this careful histomorphometric evaluation of the testis, we studied spermatogonial cells using molecular markers, determined the combined duration of meiotic and spermiogenic phases, and examined the formation of the Sertoli cell barrier (tight junctions). We found at least nine spermatogonial generations and propose a morphology-based nomenclature for spermatogonial generations that is compatible with the one used in higher vertebrates. The number of germ cells per cyst increased dramatically (1 to approximately 1360 cells) from undifferentiated spermatogonia type A to early spermatids. The combined duration of meiotic and spermiogenic phases is approximately 6 days, one of the shorter periods among the teleost fish investigated to date. The number of Sertoli cells per cyst increased 9-fold during the maturational cycle of spermatogenic cysts and stabilized in the meiotic phase at a ratio of approximately 100 early spermatids per Sertoli cell (Sertoli cell efficiency). Similarly to mammals, Sertoli cell proliferation ceased in the meiotic phase, coinciding with the formation of tight junctions between Sertoli cells. Hence, the events taking place during puberty in the germinal epithelium of mammals seem to recapitulate the "life history" of each individual spermatogenic cyst in zebrafish.

Malaria risk on the Amazon frontier

Abstract: Frontier malaria is a biological, ecological, and sociodemographic phenomenon operating over time at three spatial scales (micro/individual, community, and state and national). We explicate these linkages by integrating data from remote sensing surveys, ground-level surveys and ethnographic appraisal, focusing on the Machadinho settlement project in Rondonia, Brazil. Spatially explicit analyses reveal that the early stages of frontier settlement are dominated by environmental risks, consequential to ecosystem transformations that promote larval habitats of Anopheles darlingi. With the advance of forest clearance and the establishment of agriculture, ranching, and urban development, malaria transmission is substantially reduced, and risks of new infection are largely driven by human behavioral factors. Malaria mitigation strategies for frontier settlements require a combination of preventive and curative methods and close collaboration between the health and agricultural sectors. Of fundamental importance is matching the agricultural potential of specific plots to the economic and technical capacities of new migrants. Equally important is providing an effective agricultural extension service.

O rápido processo de envelhecimento populacional do Brasil: sérios desafios para as políticas públicas

Abstract: The positive effects of the recent age structure transition (AST) in Brazil can be seen in children’s health services, education and other areas. The higher growth rate estimated for the economically active population in coming decades constitutes a new area of opportunities. The combination of the older segment of the labor force (ages 25 to 64), which is showing high growth, with the junior segment (ages 15 to 24), which is showing very low or even negative growth rates, indicates a trend toward reducing the demographic pressure for new jobs. The training of the future labor force has become an indispensable component for a more just intergenerational, social and economic balance. Due to the age structure transition, new challenges are emerging related to the expansion of the older population. If the present per capita transfer of funds from the government is maintained constant, the difference between revenue and expenses will increase, causing an unsustainable fiscal deficit. The expected crisis brought about by the aging of the population and the current irrational social security system must be urgently discussed in Brazilian society. The best must be made of the opportunities generated by age structure transition in order to prepare to face the new resulting challenges.

Malassezia nana sp. nov., a novel lipid-dependent yeast species isolated from animals.

Abstract: Five isolates of a novel species of the yeast genus Malassezia were isolated from animals in Japan and Brazil. Phylogenetic trees based on the D1/D2 domains of the large-subunit (26S) rDNA sequences and nucleotide sequences of the internal transcribed spacer 1 region showed that the isolates were conspecific and belonged to the genus Malassezia. They were related closely to Malassezia dermatis and Malassezia sympodialis, but were clearly distinct from these two species and the other six species of Malassezia that have been reported, indicating that they should be classified as a novel species, Malassezia nana sp. nov. Morphologically and physiologically, M. nana resembles M. dermatis and M. sympodialis, but can be distinguished from these species by its inability to use Cremophor EL (Sigma) as the sole lipid source and to hydrolyse aesculin. The type strain of M. nana is NUSV 1003T (=CBS 9557T=JCM 12085T).