Repositório RCAAP

The present study investigated lead effects on gill morphology, hematocrit, blood sodium, glucose, lipids, protein, and cholesterol of Prochilodus lineatus exposed to two sublethal lead concentrations for 96 h. Preliminary series of short-term static toxicity tests were run to determine LC50 (96 h) of lead in P. lineatus, which was 95 mg Pb.L-1. Therefore, lead concentrations tested in the sublethal experiments were 24 and 71 mg Pb.L-1, which correspond to 25% and 75% of the LC50 (96 h), respectively. Gills of P. lineatus exposed to both lead concentrations during 96 h presented a higher occurrence of histopathological lesions such as epithelial lifting, hyperplasia, and lamellar aneurism. P. lineatus did not show significant alterations in hematocrit during exposure to both lead concentrations. Fish exposed to the highest lead concentration showed a significant decrease in Na+ plasma concentration after 48 h, possibly reflecting a sodium influx rate decrease. P. lineatus exposed to both lead concentrations presented a "classical general adaptation syndrome to stress", as hyperglycemia associated with lowered lipids and proteins was reported. Stress-response magnitude was dose-dependent. While the response to the lowest lead concentration might represent adaptation, the highest concentration seems to characterize exhaustion.

The diet and trophic groups of an assemblage of aquatic insects were studied in a tropical stream. Genera of the orders Ephemeroptera, Odonata, Plecoptera, Lepidoptera, and Hemiptera showed feeding specialization. Others, such as Trichoptera, Coleoptera, and Diptera, showed great diet variation with genera of different trophic groups. Seasonal variation of insect diet, evident only for some genera of the orders Trichoptera, Lepidoptera, Coleoptera, and Diptera, was due to the differences observed in community composition and to generalist habits of these genera. However, the seasonal comparison of trophic groups showed no significant statistical differences. The great importance of organic matter, a non-limited resource, in the diet of Ribeirão do Atalho aquatic insects may be the explanation for the trophic stability in this community organization.

Short-term fluctuations and structure of phytoplankton were examined for two months in the dry season (August-September/1997) in a eutrophic reservoir of central Brazil. Algicide treatment for the control of Microcystis aeruginosa bloom influenced the short-term variation pattern of the phytoplankton community. Algicide treatment was effective in controlling M. aeruginosa bloom, but it also influenced the Cylindrospermopsis raciborskii population. These species retained low densities, showing small colonies and trichomes, respectively. Drops in Cyanobacteria populations following algicide treatment were succeeded by progressive increase in Chlorophyta. The shifts in environmental conditions may have allowed the development of this group. In this study correspondence analysis of abundance data for phytoplankton assemblage in lake Paranoá revealed that available light, rather than chlorophyll-a, total suspended material, and water temperature, accounted for most of the short-term fluctuation in phytoplankton structure during algicide application. Canonical correspondance analysis (CCA) showed the primary importance of water transparency changes in abundance of taxa in the community. Algicide treatment for the control of nuisance blooms is discussed as a contribution to improved efficiency in reservoir management.

The first recorded electroantennographic preliminary studies on stingless bees have been performed using two species of Frieseomelitta from Brazil. Experiments with F. silvestrii and F. varia showed that antennae respond to hexane extracts of heads and abdomens of both species and posterior tibia of F. silvestrii (which carry plant resin), as well as to the pure compounds 2-heptanol and 2-nonanol, which occur in the mandibular glands of both species, and to the terpenes alpha-cubebene, humulene, and beta-caryophyllene found on their tibia and in the cerumen of their nests.

The Porthole Shovelnose Catfish, Hemisorubim platyrhynchos, is the sixth largest pimelodidae of the Pantanal. Its age and growth were studied using pectoral fin-spines from fish collected in the Cuiabá river basin, Pantanal. The fish, which came from commercial and experimental fisheries, were all caught with hook and line. Growth-ring formation time could not be defined through the Kruskal-Wallis test on marginal increment (H = 4.142; p = 0.247). Nevertheless, decrease in the marginal increment index occurring as waters recede suggests this as the probable time when growth rings form. Estimation of the parameters of von Bertalanffy growth curve, adjusted through nonlinear regression to observed fork lengths, with L<FONT FACE=Symbol>¥</FONT> fixed at 64 cm, were: k = 0.222 year-1; t o = -2.149 years. Individual life span was estimated at 11.4 years. The results suggest that fork length is a good predictor of age for individuals of this species.

In this paper we examine the precision of six diversity indices, four of them empirical when including in their formulae climax adaptation numbers. These numbers define the succession position of the plant species in five forest areas in São Paulo State. We simulated hypothetical forests and compared the results with a list of species in the five areas. Low agreement was found among the indices in succession stages. Including the climax adaptation numbers increased precision for only some indices.

Acid phosphatase (AcP) activity was investigated in the testes of two species of teleosts in two seasons: summer and winter. AcP activity was detected in Sertoli cells from tilapia (Oreochromis niloticus) only during the nonreproductive period of its annual cycle, corresponding to the winter months. In kingfish (Odonthestes perugiae), the enzymatic reaction was identified during the non-reproductive period (summer) in epithelial cells of the efferent ducts but not in Sertoli cells. These data suggest that the enzyme is involved in the absorption of residual spermatid cytoplasm and as well as in the removal of spermatozoa remaining after the reproductive period. In kingfish, this heterophagous function is carried out by the efferent duct cells and not by Sertoli cells.

The Pantanal comprises a number of landscape units, submitted to a flood pulse with variable intensity or regularity. One of these units, the flooded plains, is important in cattle raising. This study was carried out in the northern portion of the Pantanal and presents data related to the productive dynamics of the flooded native pastures both protected from and exposed to cattle. The greatest total biomass values were for the protected pasture due to accumulated dead biomass. Net primary production presented smaller values at the flood-season start and increasing gradually beginning in the subsequent rainy season. However, consumption by cattle was also more intense during the months of greater precipitation. The effect of cattle in pastures is of fundamental importance to management since it prevents the dead biomass excess that increases fire risks.

Parakeets usually forage for massive and ephemeral plant resources at forest canopies. Fruit pulp is widely cited as a major food resource for these birds, which often eat seeds and nectar. In this study, I assessed flower and fruit production at a gallery forest in the Pantanal flood plain (Brazil) in order to evaluate the relationship between food resource production and abundance of a common parakeet, Brotogeris chiriri. Also, I evaluated the relationship between food resource production and foraging activity. Parakeet abundance varied markedly along the year, coinciding with massive episodes of flower and fleshy fruit availability. Inga vera nectar, intensely used during the latter part of dry season, was by far the most exploited food item by parakeets when they were very abundant. The nectar comprised 34% of the parakeets' diet (N = 131 feeding records) at the gallery forest, while fleshy fruits made up the rest. Parakeets principally exploited fruits of Cecropia pachystachya and Ficus luschnathiana, besides palm fruits and Inga vera arils. The consistent relationship between foraging activity and parakeet abundance, as well as the coincidence between fluctuations of these parameters and availability of major food resources, suggests that food availability mostly influenced B. chiriri occurrence in the gallery forest. Furthermore, I found no evidence for gallery forest use for roosting and/or breeding, in spite of the fact that such factors usually influence local parakeet abundance.

Studies on anurans in restinga habitats are few and, as a result, there is little information on which methods are more efficient for sampling them in this environment. Ten methods are usually used for sampling anuran communities in tropical and sub-tropical areas. In this study we evaluate which methods are more appropriate for this purpose in the restinga environment of Parque Nacional da Restinga de Jurubatiba. We analyzed six methods among those usually used for anuran samplings. For each method, we recorded the total amount of time spent (in min.), the number of researchers involved, and the number of species captured. We calculated a capture efficiency index (time necessary for a researcher to capture an individual frog) in order to make comparable the data obtained. Of the methods analyzed, the species inventory (9.7 min/searcher /ind.- MSI; richness = 6; abundance = 23) and the breeding site survey (9.5 MSI; richness = 4; abundance = 22) were the most efficient. The visual encounter inventory (45.0 MSI) and patch sampling (65.0 MSI) methods were of comparatively lower efficiency restinga, whereas the plot sampling and the pit-fall traps with drift-fence methods resulted in no frog capture. We conclude that there is a considerable difference in efficiency of methods used in the restinga environment and that the complete species inventory method is highly efficient for sampling frogs in the restinga studied and may be so in other restinga environments. Methods that are usually efficient in forested areas seem to be of little value in open restinga habitats.

Somatic recombination in heterozygous diploid cells may be a promotional agent of neoplasms by inducing homozygosity of defective genes. Tumor suppressor genes may in this way be completely suppressed in recombinant cells. In this work, the genotoxic effects of detergent derived from the castor oil plant (Ricinus communis) in heterozygous diploid cells of Aspergillus nidulans are evaluated. Previous studies have evaluated the application of this substance in endodontic treatments as an irrigating solution. The recombinogenic potential of the compound has been studied through the production of homozygous cells for nutritional markers riboA1, pabaA124, biA1, methA17, and pyroA4. Detergent was diluted to 1:10, 1:20, and 1:40, and morphologic alterations, delay in conidiophore development, and mitotic recombination occurrence were reported for the three dilutions. Although past studies have demonstrated the antimicrobial action of the detergent under analysis, our results revealed its cytotoxic effects and recombinogenic potential.

Development time of embryos in the brood pouch of the cladoceran Penilia avirostris Dana, 1852, was estimated by collecting zooplankton daily for 15 days in surface water of Guanabara Bay, Brazil. Each day the maturity stage of embryos of 90 parthenogenic females was noted. Total development time (egg to birth) varied from 2 to 3 days, the immature phase (stages I to IV) being generally longer (2 days) than intermediate and mature phases (1 day, stages V to XII). Similar results were obtained from Bottrell's equation, which takes water temperature into account.

We compared the trappability of marked and unmarked individuals in species of marsupials and rodents of three tropical assemblages of small mammals in Brazil. Two studies used trapping grids, one in cerrado and the other in an Atlantic forest reserve, whereas the study in a rural area used transects. In the two studies using trapping grids, marked animals were frequently more trappable than unmarked ones, but in some species this difference was not significant. In the rural area, marked and unmarked animals did not differ significantly. The number of recaptures per resident animal was higher in the two studies using trapping grids than in the rural area where transects were used. Differences in trappability between the three studies might have been caused by differences not only in trapping design (grids vs. transects), but also in the type of trap used, bait, and habitat. Although differential trappability tends to be considered the rule in small mammals, these results suggest that trappability of marked and unmarked animals may be specific for the particular combination of sampling design, field methods, and habitat under study.

Some 231 birds were recorded on a sandy plateau in central São Paulo, in an area forming a natural "habitat spectrum", from dry or wet grasslands to bushy ones (campo-cerrado) plus gallery scrub, marshes, and low woods. Subtracting 12 species that mostly flew over, and 56 species that seemed to be vagrants or accidental visitors, 163 species were regular (including 14 that center in nearby anthropogenically-modified zones). The 69 in gallery areas are mostly regionally common woodland species, but one southeastern species has disappeared over the years and three northwestern dry-forest species have entered. The 81 grassland species include several rare birds, and hence are important despite exhibiting lower biodiversity than in regional forest areas. Seven rare species disappeared over the years, some due to lack of fires, others because of either recent "greenhouse" dry years or protected vegetation growing to taller campo-cerrado. Several other species are becoming rare. Low vegetation forms a spectrum of temporally unstable habitats that change rapidly; one needs actively managed large areas and corridors even though many open-area birds can fly long distances to varying habitat patches.

We assessed spatial and seasonal changes in the diet of Oligosarcus hepsetus in order to describe the strategy developed by this species that allows their very high abundance in Lajes reservoir, Rio de Janeiro, Brazil. Fish samplings were carried out using gill nets, deployed during ca. 12 and 24 hours, between April 2001 and May 2002. A total of 289 individuals were examined, of which 97 showed gut contents. We used the index of relative importance (IRI) to compare probable dietary shifts, and the frequency of occurrence (% OC) to analyze possible ontogenetic influences on feeding. O. hepsetus showed carnivorous habits, feeding preferably on fish and insects, the latter of which occurred in 71.0% of the guts presenting contents. O. hepsetus consumed different items along the three reservoir zones: insects (61.0% IRI) and Cichla monoculus (38.9% IRI) in the lower zone; Lepidoptera (57.0% IRI) in the middle zone; and C. monoculus (77.0% IRI) in the upper zone. Food items changed seasonally with C. monoculus predominating in autumn 2001, and Hymenoptera and Lepidoptera in the winter. In spring almost all food was Lepidoptera (99.8% IRI), while in the summer Hemiptera dominated in the diet. In autumn 2002 Hemiptera (97.0% IRI) was dominant, in significant contrast with the previous autumn. Individuals smaller than 190 mm SL fed heavily on insects, while fishes predominated in the diet of individuals larger than 190 mm SL. Shifts in prey-capture ability among length classes suggest decreasing intraspecific competition. A higher food plasticity seems to be the strategy employed by this opportunist species, which used food resources available in the reservoir.

In this study we analyzed the impact of physical barriers of Spodoptera frugiperda (J. E. Smith) egg-masses on the behavior of Trichogramma atopovirilia Oatman &amp; Platner and Trichogramma pretiosum Riley. The duration of drumming, drilling, oviposition, period spent over the egg-mass, and interval between parasitized eggs were timed, and the number of parasitized eggs were recorded. The presence of scales on the egg-masses caused a significant increase in the time spent by both parasitoids on each process and a decrease in the residence time over the egg-mass and in the number of parasitized eggs, with an increase in the number of egg layers. There was a significant decrease in the number of parasitized eggs in relation to egg-masses with one layer and no scales. We observed that the physical barriers in fall armyworm egg-masses changed the behavior of T. atopovirilia and T. pretiosum, affecting their parasitization capacity.

The relationship between the aquatic macrophyte cover in upper segments of tributaries and this cover in these tributaries but near the reservoir's main body was tested. Sixteen taxa belonging to 12 families of aquatic macrophytes were recorded in Cachoeira Dourada Reservoir. The most frequent species were Eichhornia azurea (frequency of occurrence = 92%; n = 37 sites) and E. crassipes (44%). Upper segments of the tributaries were the main areas colonized by these aquatic macrophytes. The positive relationship between the aquatic macrophyte cover between the upper and lower segments of tributaries indicates the importance of dispersion in the colonization of the arms and the reservoir's main body.

The aim of this study was to investigate the mite fauna present in 33 living room and 22 bedroom curtain dust samples from 41 different homes in the southern Brazilian city of Campinas, SP. A total of 148 mite bodies were found. Of these, 83 were found in living-room curtain samples (56.1% of total) and 65 were in bedroom curtain dust samples (43.9%). The most frequently observed mite suborders were: Acaridida (n = 79; 53.4%), Actinedida (n = 53; 35.8%), Oribatida (n = 14; 9.5%), and Gamasida (n = 2; 1.3%). The most frequent families were Pyroglyphidae (n = 61; 41.2%), Eriophyidae (n = 25; 16.9%), Tarsonemidae (n = 15; 10.1%), and Glycyphagidae (n = 13; 8.8%). No statistical difference was observed between the number of mites found in the samples from living room and bedroom curtains.

The reproductive biology of Palythoa caribaeorum (Duchassaing &amp; Michelotti 1860) and Protopalythoa variabilis (Duerden 1898) was studied through monthly samples from tagged colonies from June 1996 to June 1997, in São Sebastião channel, São Paulo, Brazil (45º26'W, 23º50'S). The gametogenesis was similar to that of other zoanthids as shown by histological preparations. Oocyte diameters and maturation stages of testis vesicles were evaluated on squash preparations. Both species showed sequential protogynic hermaphroditism, with high frequency of fertile polyps (83% in P. variabilis and 72% in P. caribaeorum), high frequency of colonies in female sex condition (65.3% of P. variabilis and 41.7% of P. caribaeorum), and apparently continuous gametogenesis. In P. caribaeorum, egg release was continuous and sperm release took place during half of the analyzed period. In P. variabilis, egg and sperm release occurred in April-May and February-March 1997, respectively.

The development of cercariae from Schistosoma mansoni strains BH and SJ in Biomphalaria glabrata and Biomphalaria tenagophila treated with saccharose was studied. The molluscs were maintained in dechlorinated tap water containing 0.01% saccharose. After one week of treatment with saccharose, B. glabrata and B. tenagophila were exposed to ten S. mansoni miracidia, from BH and SJ strains respectively. Control snails of both species were maintained in dechlorinated tap water without saccharose and exposed to the same number of miracidia. There was no significant difference between the infection rates of snails treated or not with saccharose. However, the two groups of B. glabrata had significantly greater infection rates than the corresponding B. tenagophila groups. Molluscs treated with saccharose had a lower survival rate, with the greatest mortality occurring immediately before and at the beginning of cercariae release. Treatment with saccharose did not result in the release of more cercariae, but larvae from molluscs so treated showed a greater capacity to penetrate mouse skin, which was attributed to the greater energy supply during larval development in the mollusc.