Growth and home range size of the gracile mouse opossum Gracilinanus microtarsus (Marsupialia: Didelphidae) in Brazilian cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Anti-genotoxic effect of aqueous extracts of sun mushroom (Agaricus blazei Murill lineage 99/26) in mammalian cells in vitro

The sun mushroom is the popular name for the Agaricus blazei Murill fungus, a mushroom native to south-eastern Brazil, which has been frequently used in popular medicine mainly in the form of tea to treat various ailments (stress, diabetes, etc.). In the present study, the genotoxic and/or anti-genotoxic effects ofA. blazei on mammalian cells in culture was assessed by checking the increase or reduction of micronucleus (MN) frequency and comets. The sun mushroom (lineage 99/26) was used as aqueous extracts prepared (2.5%) at three different temperatures (60, 25 and 4°C). The in vitro micronucleus (MN) test in binucleated cells and comet assay were used in V79 cells cultivated in HAM-F10+DMEM medium (1:1), supplemented with 10% of fetal bovine serum. The experiments were divided into four treatment types: 1. Negative control; 2. Positive control with MMS; 3. Treatments with the three forms of extracts (60, 25 and 4°C); and 4. Treatments with the extracts in different associations (simultaneous, pre-treatment, post-treatment and simultaneous after pre-incubation for 1 h) with MMS. None of the A. blazei extracts show genotoxic activity. In the comet assay no protecting effect was found. The results obtained in the MN test showed that the three forms of extracts used had protective activity, suggesting that the compound or active ingredients of A. blazei are always present in these extracts. The greater protective efficiency of the simultaneous treatment and simultaneous treatment with pre-incubation mixture with MMS suggests that the extracts have an antimutagenic action of the desmutagenic type. © 2002 Elsevier Science Ltd. All rights reserved.

Reproductive ecology of the freshwater red alga Batrachospermum delicatulum (Batrachospermales, Rhodophyta) in three tropical streams

Batrachospermum delicatulum specimens from three stream segments were analyzed from a tropical region in south-eastern Brazil (20°18′- 20°49′S, 49°13′-49°46′W). Physical and chemical parameters and the spatial placement of thalli were investigated along with the reproductive characteristics of the gametophytic phase. Sequence data of the cox 2-3 spacer region was also utilized to evaluate genetic variation in individuals within and among stream segments. Gametophyte occurred under relatively diverse environmental conditions, whereas thalli abundance was weakly or not correlated to environmental variables within the stream segments. All specimens examined were dioecious. The ratio of male/female plants was relatively low (0.5 to 1.3) and male plants tended to occur as clumps (two or three plants together). High reproductive success was observed, as indicated by the occurrence of 100% fertilized (carposporophytic) female plants. This is similar to previous reports for this and other dioecious species, which is remarkable considering the relatively low proportion of male/female plants. Results support the two hypotheses to explain the high reproductive success in dioecious species. The occurrence of male plants in clumps was evidence for a strict spatial relationship (i.e. male plants located in upstream position of female plants in order to release spermatia, which would be carried by eddies through female plants). In contrast, the occurrence of male and female plants adjacent to each other allowed outcrossing among neighboring plants with intermingled male and female branches, which seemed more applicable to some situations (low turbulence habitats). The cox 2-3 spacer region from the 18 individuals sequenced was 376 bp and the DNA sequence was identical with no base pair substitutions. Likewise, a previous study of another Batrachospermum species showed that the same haplotypes were present in all stream segments from the same drainage basin, even though the stream segments were a considerable distance apart. Short distance dispersal either by small birds or waterway connectivity might explain these findings.

Flower mites decrease nectar availability in the rain-forest bromeliad Neoregelia johannis

Nectarivorous flower mites can reduce the volume of nectar available to pollinators. The effects of the flower mite Proctolaelaps sp. on nectar availability in flowers of a melittophilous bromeliad Neoregelia johannis (Bromeliaceae) was evaluated in a coastal rain forest in south-eastern Brazil. In a randomized block experiment utilizing 18 flower pairs, one per bromeliad ramet, pollinators (Bombus morio) and mites were excluded, and then nectar volume, sugar concentration and sugar mass were quantified over the anthesis period. Mites significantly reduced nectar volume early in the morning (6h00-8h00), but not later (10h00-12h00). Mites decreased total volume of nectar available up to 22%. Sugar concentration in nectar was higher earlier in the morning, and decreased between 10h00-12h00. The pronounced consumption of nectar by mites during the period of higher sugar concentration reduced the total amount of sugar available to pollinators by 31%. This is the first study showing that flower mites decrease nectar rewards in a melittophilous plant. Because nectar volume by itself incompletely describes nectar production rates and the effects of nectar removal by flower mites on the availability of sugar, our study highlights the inclusion of sugar content in future studies assessing the effects of thieves on nectar production rates. Copyright © 2010 Cambridge University Press.

Molecular phylogenies, chromosomes and dispersion in Brazilian akodontines (Rodentia, Sigmodontinae)

Uma nova filogenia molecular para roedores akodontinos do Brasil é proposta. A árvore filogenética foi enriquecida com a área de ocorrência e com informações sobre o cariótipo das amostras. Baseado nisto, e com a metodologia descrita, foram propostas hipóteses sobre as características do cariótipo e sobre a área de ocorrência dos ancestrais de cada clado. Assim, foi possível discutir hipóteses sobre evolução cromossômica do grupo, e sobre eventos de dispersão a partir da área de diferenciação original dos akodontinos nos Andes. A evolução cromossômica começou com números diplóides altos (2n=52) e mostrou uma tendência a redução (até 2n=14 em clados mais recentes). Ramos independentes da árvore mostraram redução do 2n e num caso aumentou o numero diplóide. Foram propostos pelo menos quatro eventos de dispersão dos Andes até o Brasil Sul-Oriental. Os resultados indicam a direção de novos estudos em cariologia comparada.

Traços de história de vida de três espécies de peixes em riachos da bacia do rio Corumbataí-SP

Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

Systematics of Pseudotothyris (Loricariidae: Hypoptopomatinae)

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

Population differentiation and speciation in the genus Characidium (Characiformes: Crenuchidae): effects of reproductive and chromosomal barriers

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Non-alcoholic fatty liver disease and its associated risk factors in Brazilian postmenopausal women

Objective To evaluate the prevalence and risk factors of non-alcoholic fatty liver disease (NAFLD) in postmenopausal women.Methods A cross-sectional study was carried involving 188 women (age >= 45 years and amenorrhea >= 12 months) attending the outpatient unit in south-eastern Brazil. Exclusion criteria were liver disease (hepatitis B and C, cholestatic disease, liver insufficiency), use of drugs that affect liver metabolism; alcoholics; AIDS or cancer history; and morbid obesity. NAFLD was diagnosed by abdominal ultrasound. Clinical, anthropometric (body mass index, waist circumference) and biochemical variables were measured.Results Of the 188 women, 73 (38.8%) had NAFLD. Blood pressure, waist circumference, body mass index, LDL cholesterol, triglycerides and glucose were significantly higher in NAFLD patients when compared with women without NAFLD (control group) (p < 0.05). HOMA-IR values indicated insulin resistance only in the NAFLD group (6.1 +/- 4.6 vs. 2.4 +/- 1.4 in control group, p < 0.05). Metabolic syndrome was detected in 93.1% of the women affected by NAFLD, and 46.1% of the control group (p < 0.05). In multivariate analysis, adjusted for age and weight, the variables considered at risk for the development of NAFLD, were: high waist circumference (odds ratio (OR) 1.07, 95% confidence interval (CI) 1.01-1.13), insulin resistance (OR 3.81, 95% CI 2.01-7.13), and presence of metabolic syndrome (OR 8.68, 95% CI 3.3-24.1).Conclusion NAFLD showed a high prevalence among postmenopausal women. The presence of metabolic syndrome, abdominal obesity and IR were indicators of risk for the development of NAFLD.

Soil profile, relief features and their relation to structure and distribution of Brazilian Atlantic rain forest trees

In tropical forests, the environmental heterogeneity can provide niche partitioning at local scales and determine the diversity and plant species distribution. Thus, this study aimed to investigate the variations of tree species structure and distribution in response to relief and soil profile features in a portion of the largest remnant of Brazilian Atlantic rain forest. All trees >= 5 cm diameter at breast height were recorded in two 0.99 ha plots. Topographic survey and a soil characterization were accomplished in both plots. Topsoil samples (0-20 cm) were taken from 88 quadrats and analyzed for chemical and particle size properties. Differences for both diversity and tree density were identified among three kinds of soils. A canonical correspondence analysis (CCA) indicated that the specific abundance varied among the three kinds of soils mapped: a shallow Udept - Orthent / Aquent gradient, probably due to differences in soil drainage. Nutrient content was less likely to affect tree species composition and distribution than relief, pH, Al3+, and soil texture. Some species were randomly distributed and did not show restriction to relief and soil properties. However, preferences in niche occupation detected in this study, derived from the catenary environments found, rise up as an important explanation for the high tree species diversity in tropical forests.

Plasticity of stomatal distribution pattern and stem tracheid dimensions in Podocarpus lambertii: an ecological study

Leaf and wood plasticity are key elements in the survival of widely distributed plant species. Little is known, however, about variation in stomatal distribution in the leaf epidermis and its correlation with the dimensions of conducting cells in wood. This study aimed at testing the hypothesis that Podocarpus lambertii, a conifer tree, possesses a well-defined pattern of stomatal distribution, and that this pattern can vary together with the dimensions of stem tracheids as a possible strategy to survive in climatically different sites. Leaves and wood were sampled from trees growing in a cold, wet site in south-eastern Brazil and in a warm, dry site in north-eastern Brazil. Stomata were thoroughly mapped in leaves from each study site to determine a spatial sampling strategy. Stomatal density, stomatal index and guard cell length were then sampled in three regions of the leaf: near the midrib, near the leaf margin and in between the two. This sampling strategy was used to test for a pattern and its possible variation between study sites. Wood and stomata data were analysed together via principal component analysis. The following distribution pattern was found in the south-eastern leaves: the stomatal index was up to 25 higher in the central leaf region, between the midrib and the leaf margin, than in the adjacent regions. The inverse pattern was found in the north-eastern leaves, in which the stomatal index was 10 higher near the midrib and the leaf margin. This change in pattern was accompanied by smaller tracheid lumen diameter and length. Podocarpus lambertii individuals in sites with higher temperature and lower water availability jointly regulate stomatal distribution in leaves and tracheid dimensions in wood. The observed stomatal distribution pattern and variation appear to be closely related to the placement of conducting tissue in the mesophyll.

Can Roads Be Used as Transects for Primate Population Surveys?

Line transect distance sampling (LTDS) can be applied to either trails or roads. However, it is likely that sampling along roads might result in biased density estimates. In this paper, we compared the results obtained with LTDS applied on trails and roads for two primate species (Callithrix penicillata and Callicebus nigrifrons) to clarify whether roads are appropriate transects to estimate densities. We performed standard LTDS surveys in two nature reserves in south-eastern Brazil. Effective strip width and population density were different between trails and roads for C. penicillata, but not for C. nigrifrons. The results suggest that roads are not appropriate for use as transects in primate surveys, at least for some species. Further work is required to fully understand this issue, but in the meantime we recommend that researchers avoid using roads as transects or treat roads and trails as covariates when sampling on roads is unavoidable. Copyright (C) 2012 S. Karger AG, Basel

The importance of landscape structure for seed dispersal in rain forest fragments

Questions What are the main features of the seed rain in a fragmented Atlantic forest landscape? Can seed rain species attributes (life form, dispersal mode, successional status) relate to the spatial arrangement (size and number of fragments, edge density and presence of corridor) of forest fragments in the landscape? How does the rain forest landscape structure affect the seed rain? Location Atlantic rainforest, Sao Paulo State, Southeastern Brazil. Methods Seed rain samples were collected monthly throughout 1yr, counted, identified and classified according to species dispersal mode, successional status and life form. Seed rain composition was compared with woody species near the seed traps. Relationships between seed rain composition and landscape spatial arrangement (fragment area, presence of corridor, number of fragments in the surroundings, proximity of fragments, and edge density) were tested using canonical correspondence analysis (CCA). Results We collected 20142 seeds belonging to 115 taxa, most of them early successional and anemochorous trees. In general, the seed rain had a species composition distinct from that of the nearby forest tree community. Small isolated fragments contained more seeds, mainly of anemochorous, epiphytic and early-successional species; large fragments showed higher association with zoochorous and late-successional species compared to small fragments. The CCA significantly distinguished the species dispersal mode according to fragment size and isolation, anemochorous species being associated to small and isolated fragments, and zoochorous species to larger areas and fragment aggregation. Nevertheless, a gradient driven by proximity (PROX) and edge density (ED) segregated lianas (in the positive extremity), early successional and epiphyte species (in the negative end); large fragments were positively associated to PROX and ED. Conclusions The results highlight the importance of the size and spatial arrangement of forest patches to promote habitat connectivity and improve the flux of animal-dispersed seeds. Landscape structure controls seed fluxes and affects plant dispersal capacity, potentially influencing the composition and structure of forest fragments. The seed rain composition may be used to assess the effects of landscape spatial structure on plant assemblages, and provide relevant information for biodiversity conservation.

Comparing the establishment of an invasive and an endemic palm species in the Atlantic rainforest

Background: Biological invasions are one of the major causes of biodiversity loss, yet remain rather understudied in tropical environments. The Australian palm tree Archontophoenix cunninghamiana was introduced into Brazil for ornamental purposes, but has become an invasive species in urban and suburban forest patches. The substitution of A. cunninghamiana by the native palm Euterpe edulis has been proposed as a management action. Aims: We aimed to evaluate the regeneration potential of these two palm species in an Atlantic forest remnant in south-eastern Brazil where both species occur. Methods: We compared seedling establishment and seed longevity of both species through seed sowing, and also measured the contribution of A. cunninghamiana to the local seed rain and seed bank. Results: Nearly half of the non-anemochoric diaspores collected from the seed rain belonged to A. cunninghamiana, which represented a high propagule pressure in the community. The distribution of the alien palm seeds in the seed rain correlated with the distribution of nearby young and adult individuals inside the forest. Neither A. cunninghamiana nor E. edulis appeared to have a persistent seed bank in a burial experiment; seedling survival experiments suggested a much better performance for A. cunninghamiana, which had a survival rate of ca. 30% compared with a rate of only 3.5% for E. edulis. Conclusions: The results suggest a higher regeneration capacity for the alien palm over the native species when co-occurring in a forest fragment. Management actions are thus proposed to reduce a potential biological invasion process.

Suitability of distance metrics as indexes of home-range size in tropical rodent species

Estimators of home-range size require a large number of observations for estimation and sparse data typical of tropical studies often prohibit the use of such estimators. An alternative may be use of distance metrics as indexes of home range. However, tests of correlation between distance metrics and home-range estimators only exist for North American rodents. We evaluated the suitability of 3 distance metrics (mean distance between successive captures [SD], observed range length [ORL], and mean distance between all capture points [AD]) as indexes for home range for 2 Brazilian Atlantic forest rodents, Akodon montensis (montane grass mouse) and Delomys sublineatus (pallid Atlantic forest rat). Further, we investigated the robustness of distance metrics to low numbers of individuals and captures per individual. We observed a strong correlation between distance metrics and the home-range estimator. None of the metrics was influenced by the number of individuals. ORL presented a strong dependence on the number of captures per individual. Accuracy of SD and AD was not dependent on number of captures per individual, but precision of both metrics was low with numbers of captures below 10. We recommend the use of SD and AD instead of ORL and use of caution in interpretation of results based on trapping data with low captures per individual.