Comparison between RT-PCR and the mouse inoculation test for detection of rabies virus in samples kept for long periods under different conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

The toxic effects of Coleus barbatus B. on the different periods of pregnancy in rats

Extracts of Coleus bal barbatus B. have been used in folk medicine to interrupt pregnancy. In order to evaluate if this plant interferes with embryo implantation or with the normal development of the concepts, pregnant Wistar rats were treated with increasing doses (220, 440 and 880 mg/kg per day) of a hydroalcoholic extract of C. barbatus. The rats received the extract by gavage from days 0 to 5 of pregnancy (preimplantation period) or 6 to 15 (organogenic period). Control groups received distilled water during the same periods: the animals were killed at term for the evaluation of maternal and fetal parameters. The results showed that the treatment with 880 mg/kg per day of the extract of C. barbatus before embryo implantation caused delayed fetal development and an anti-implantation effect, which justifies the popular use of this extract with abortive purposes. After embryo implantation delayed development associated with maternal toxicity was observed in the fetuses of the group which received 880 mg/kg per day. (C) 2000 Elsevier B.V. Ireland Ltd. All rights reserved.

Semen and reproductive parameters during some abstinence periods after cigarette smoke exposure in male rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The ultrastructure of Sorubim lima (Teleostei, Siluriformes, Pimelodidae) spermatogenesis: premeiotic and meiotic periods

The ultrastructure of Sorubim lima spermatogenesis during the premeiotic and meiotic periods was studied. Our observations showed that the germ cells in the cysts are connected by cytoplasmic bridges and the mitotic and meiotic divisions are slightly asynchronous, the first and the last spermatogonial generations differ in the cellular and nuclear volume, nucleolus, chromatin condensation, distribution, size, density, and shape of the mitochondria, presence of 'lamellae anulata', amount and dimension of the 'nuages', and movement of the centrioles. In addition to the nuclear prophase structures, the spermatocyte I shows changes in all other cellular organelles and elongated vesicles appear in the cytoplasm. The accentuated cytoplasmic density and thickened walled vesicles are morphological characteristics that differentiate spermatocytes II from the other germ cells in the cysts of Sorubim lima testis. (C) 1999 Harcourt Publishers Ltd.

Competition and phylogeny determine community structure in Mullerian co-mimics

Until recently, the study of negative and antagonistic interactions (for example, competition and predation) has dominated our understanding of community structure, maintenance and assembly(1). Nevertheless, a recent theoretical model suggests that positive interactions (for example, mutualisms) may counterbalance competition, facilitating long-term coexistence even among ecologically undifferentiated species(2). Mullerian mimics are mutualists that share the costs of predator education(3) and are therefore ideally suited for the investigation of positive and negative interactions in community dynamics. The sole empirical test of this model in a Mullerian mimetic community supports the prediction that positive interactions outweigh the negative effects of spatial overlap(4) (without quantifying resource acquisition). Understanding the role of trophic niche partitioning in facilitating the evolution and stability of Mullerian mimetic communities is now of critical importance, but has yet to be formally investigated. Here we show that resource partitioning and phylogeny determine community structure and outweigh the positive effects of Mullerian mimicry in a species-rich group of neotropical catfishes. From multiple, independent reproductively isolated allopatric communities displaying convergently evolved colour patterns, 92% consist of species that do not compete for resources. Significant differences in phylogenetically conserved traits (snout morphology and body size) were consistently linked to trait-specific resource acquisition. Thus, we report the first evidence, to our knowledge, that competition for trophic resources and phylogeny are pivotal factors in the stable evolution of Mullerian mimicry rings. More generally, our work demonstrates that competition for resources is likely to have a dominant role in the structuring of communities that are simultaneously subject to the effects of both positive and negative interactions.

A comparative tunnelling network approach to assess interspecific competition effects in termites

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estimativa do grau de infestação numa pastagem de Panicum maximum Jacq

Um piquete de capim-colonião (Panicum maximum Jacq) submetido a pastoreio contínuo e a roçadas periódicas revelou, seis anos após o plantio, elevado grau de infestação por outras plantas, destacando-se entre elas a grama-batatais (Paspalum notatum Flügge) que apresentou 85% de frequência e 20,9% de biomassa epígea seca relativa. As dicotiledóneas, em conjunto, apresentaram frequência de 95% e biomassa relativa de 38,7% mas a sua contribuição específica foi muito reduzida. O capim-colonião, por sua vez, apesar da frequência de 95%, apresentou apenas 32,2% de biomassa relativa (diminuição de 67,8%). Estas profundas alterações da flora e da vegetação podem ser atribuidas, em grande parte, a dois fatores: a) ação seletiva da roçadeira; b) preferências alimentares e disseminação endozoócora da gramabatatais pelos bovinos.

Aspectos relacionados com a otimização do treinamento aeróbio para o alto rendimento

The objective of this work was to present recommendations aiming the aerobic training optimization, from the knowledge of the indexes of functional fitness and their physiological mechanisms. Concerning highly trained athletes, the accuracy in training elaboration can be the safest way to improve aerobic performance, since for these individuals, it is normal that the training load is changeable between an insufficient stimulus and the overtraining syndrome symptoms onset. Therefore, there are several factors that should be taken into account for the elaboration of a training program. The knowledge on fatigue mechanisms and physiological responses at different exercise intensities and durations is essential for the correct training session elaboration. Moreover, high-intensity interval training is indispensable to improve performance in highly trained athletes; however, it should be performed only after adequate recovery period. Thus, a good relationship between coach and athlete is also important for planning suitable recovery periods prior to excessive fatigue. The coach should keep accurate records of training loads and recovery times, learning hence the kinds of loads that can be individually tolerated. Among the important factors that can affect aerobic performance during competition and should be considered, we can name appropriate warm-up planning and adverse environmental conditions. After collecting all this information, it is possible to elaborate the training bases (frequency, volume, intensity and recovery) aiming at progressive improvement of aerobic performance.

Larval competition for patchy resources in Chrysomya megacephala (Dipt., Calliphoridae): implications of the spatial distribution of immatures

In the present study, a single procedure was established to investigate the effect of the spatial distribution of immatures in patchy resources, on the outcome of larval competition for food. in experimental populations of Chrysomya megacephala. A theoretical model of intraspecific competition was extended and applied to experimental data on survival to adulthood for 20 larval densities, to obtain the theoretical mean number of individuals that will survive, considering a hypothetical previous random adult oviposition in a system of homogeneous patches. The survival curve obtained suggests that the larval competition for food in C. megacephala is of the scramble/exploitative type, which corroborates results from previous studies, although the latter did not consider the correlation between local and global abundances. The present model allows that experimental data could be perfectly applicable, and it incorporates fundamental assumptions about the spatial context of competition for patchy resources in blowflies, and may be applied to the optimization of mass rearing techniques and to the maintenance of insect colonies under experimental conditions.

Feeding dynamics of Cichla kelberi Kullander & Ferreira, 2006 introduced into an artificial lake in southeastern Brazil

O objetivo desse estudo foi caracterizar sazonalmente a dieta de Cichla kelberi em um lago artificial em Leme-SP, determinando os itens alimentares e as relações com os sexos e com a maturação gonadal dos exemplares amostrados. A dieta de C. kelberi apresenta uma dinâmica em três diferentes períodos: os meses de inverno foram caracterizados por baixa atividade alimentar e alta concentração de peixes indeterminados, durante a primavera ocorreu um aumento na atividade alimentar, sendo Tilapia sp. o item alimentar dominante e durante o verão e início do outono foi evidenciada alta taxa de canibalismo. A plasticidade na composição da dieta foi marcada pela quantidade de presas disponíveis durante os períodos do ano e pelo período reprodutivo.

Intraspecific and interspecific pre-adult competition on the neotropical region colonizer Zaprionus indianus (Diptera: Drosophilidae) under laboratory conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Oxidative stress and antioxidant capacity in sickle cell anaemia patients receiving different treatments and medications for different periods of time

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Particle Competition and Cooperation in Networks for Semi-Supervised Learning

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Competition between suppression and production of Fermi acceleration

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

U-ages in soils and groundwater evidencing wet periods 400-600 kyr ago in southeast Brazil

U-238 and its radiogenic daughter U-234 have been utilized for dating soil formation and groundwater residence time during the last 1.5 million years, in this case based on the U-clissolution/precipitation occurring during modifications of the oxidation-reduction conditions. In this paper, we report a 400-600 kyr proxy of wet periods from sediments occurring in a soil profile developed over rocks outcropping at the Parana sedimentary basin in Brazil, and from groundwater exploited of Guarani aquifer at the same basin. The approaches indicated successful use of the U-modeled ages for suggesting wet periods exceeding the past 116-210 kyr from previous studies. (C) 2007 Elsevier Ltd. All rights reserved.