Repositório RCAAP

Nascent procollagen peptides and other secretory proteins are transported across the endoplasmic reticulum (RE) membrane through a protein-conducting channel called the translocon. Sec61alpha, a multispanning membrane translocon protein, has been implicated as essential for translocation of polypeptides chains into the cisterns of the ER. However, it is not known whether Sec61alpha is ubiquitously expressed in collagen producing teratocarcinoma cells. Furthermore, the production, expression, and utilization of Sec61alpha may depend on the cell differentiation stage. Stem cells from many cultured teratocarcinoma cell lines such as F9 and P19 cells are capable of differentiation in response to low retinoic acid concentrations. This differentiation of the tumorigenic stem cells results in tumorigenicity loss. For this study, mouse F9 and P19 teratocarcinoma cells were grown in culture medium treated with or without retinoic acid. Expression of Sec61alpha was determined by reverse trancriptase polimerase chain reaction (RT-PCR). In untreated conditions, F9 cells expressed undetected Sec61alpha amounts. It was also demonstrated that Sec61alpha expression is stimulated in F9 cells after retinoic acid treatment for 72 hours. No changes were found in Sec61alpha expression in P19 cells after retinoic acid treatment. These data indicate that the expression of Sec61alpha is enhanced with retinoic acid induced differentiation of F9 teratocarcinoma cells.

Parotocinclus planicauda, a new species from a tributary of the Doce River drainage in Minas Gerais State, Brazil, is distinguished from all other species of the genus by the presence of a caudal peduncle almost quadrangular in cross section; the anterior position of the adipose fin, close to the dorsal fin insertion; and very small orbits. A key to the Parotocinclus species of eastern Brazilian coastal rivers south of the São Francisco River is provided.

Parasites of 136 specimens of Hemisorubim platyrhynchos, popularly called jurupoca, were analyzed. Fourteen parasite species were recorded: four digeneans (Crocodilicola pseudostoma, one Gorgoderidae species, Sanguinicola platyrhynchi, and Sphincterodiplostomum sp.); three cestodes (Goezeella paranaensis, Spatulifer maringaensis, and Mariauxiella piscatorum); five nematodes (Contracaecum Type 1 larvae of Moravec, Kohn, & Fernandes, 1993; Contracaecum Type 2 larvae of Moravec, Kohn, & Fernandes, 1993; Cucullanus (Cucullanus) zungaro; Eustrongylides ignotus; and Goezia sp.); one acanthocephalan (Quadrigyrus machadoi), and one pentastomid (Sebekia sp.). Most of the helminth specimens were found in larval stages, confirming that H. platyrhynchos is a significant source of their transmission. No dominance was reported. With the exception of Contracaecum Type 2 (featuring random dispersion), the species had a clumped pattern of dispersion in the host sample. Evidence of competition among parasite species was not reported. Several species of parasites were correlated with host size and sex. This fact may be explained by increase in food content and possible behavioral modifications of male and female hosts. Infracommunity diversity was not related to host size or sex.

Chironomids larvae are frequently one of the most abundant and diverse groups of insects in several kinds of aquatic environments. Also, they play a major role in the aquatic food webs, representing a major link among producers and secondary consumers. This work investigates the feeding behavior of the chironomid larvae present in the Rio da Fazenda, situated in the Parque Nacional da Tijuca, Rio de Janeiro, Brazil, between August 1994 and May 1995. Algae, fungi, pollen, leaf and wood fragments, animal remains, detritus and silt were the main gut contents found in the larvae studied. The main food item ingested by the larvae was detritus, except for the Stenochironomus whose main food source was leaf and wood fragments. Tanypodinae exhibited a large quantity of animal remains of several kinds in the diet. During the period studied it was observed that the diet of 16 genera (out of 24 studied) varied. Tanypodinae had mainly coarse particulate organic matter (> 1 mm) in the gut contents, while Chironominae and Orthocladiinae had fine particulate organic matter (< 1 mm).

In order to verify the carbon source and trophic position of the main species of fishes, of the Paraná River floodplain, we analysed the proportion of stable carbon (delta13C) and nitrogen (delta15N) isotopes in muscle of fishes sampled in the rainy season. We analyzed adult individuals of Loricariichthys platymetopon, Schizodon borellii, Leporinus lacustris, Auchenipterus osteomystax, Iheringichthys labrosus, Leporinus friderici, and Serrasalmus marginatus. These data were compared with the results obtained by the analyzing stomach contents. The primary producers found in the Baía River were the C3 plants (riparian vegetation, macrophytes, periphyton, and phytoplankton) and the C4 plants (macrophytes). The results of the contribution analysis revealed that the carbon used by the species was derived from C3 plants. According to the trophic position estimates (diet and delta15N), the species primarily consumed Loricariichthys platymetopon, Schizodon borellii, Leporinus lacustris, and Leporinus friderici and, secondarily Auchenipterus osteomystax, Iheringichthys labrosus, and Serrasalmus marginatus. There was no significant difference between the two methods utilized.

Starch gel electrophoresis with L-leucyl-beta-naphthylamide as substrate revealed five aminopeptidases in extracts of Polistes versicolor. These enzymes are presumably products of five structural gene loci. All but Lap¹ aminopeptidases exhibited differential distribution in the developmental stages and in the tissues. Five dipeptidases were revealed with different dipeptides. These enzymes exhibited significant differences in their substrate preferences, but a more homogeneous distribution throughout ontogenetic developmental stages than did aminopeptidases. Electrophoretic variants of Lap4 and PepA² were detected and although a low intralocus heterozygosity was found due to the low frequency of these variants, phenotypical segregation observed at these loci in pupae extracts of some colonies points to the occurrence of more than one egg-laying female. Otherwise, the detection of Lap4 allozyme restricted to nests of one area suggests low dispersion ability of the adults of Polistes versicolor.

The control of Acromyrmex leaf-cutting ants is necessary due to the severe damage they cause to diverse crops. A possibility was to control them using the bacterium Bacillus thuringiensis (Bt) that characteristically produces insecticidal crystal proteins (ICPs). The ICPs have been effective in controlling lepidopterans, dipterans, and coleopterans, but their action against hymenopterans is unknown. This paper describes an attempt to isolate Bt from ants of two Acromyrmex species, to evaluate its pathogenicity towards these ants, and to test isolates by PCR. Bacterial isolates of Bt obtained from A. crassispinus and A. lundi have been assayed against A. lundi in the laboratory. The bioassays were carried out in BOD at 25°C, with a 12-hour photoperiod, until the seventh day after treatment. The Bt isolates obtained were submitted to total DNA extraction and tested by PCR with primers specific to cry genes. The results showed Bt presence in 40% of the assessed samples. The data from the in vivo assays showed a mortality rate higher than 50% in the target population, with the Bt HA48 isolate causing 100% of corrected mortality. The PCR results of Bt isolates showed a magnification of DNA fragments relative to cry1 genes in 22% of the isolates, and cry9 in 67%. Cry2, cry3, cry7, and cry8 genes were not detected in the tested samples, and 22% had no magnified DNA fragments corresponding to the assessed cry genes. The results are promising not only regarding allele identification in new isolates, but also fort the assays aimed at determining the Bt HA48 LC50's, which can eventually be applied in controlling of Acromyrmex leaf-cutting ants.

A quali-quantitative survey was done in two fragments (75 and 100 ha) of semideciduous forest in rural São Paulo State. The aim was to characterize the bird community according to richness, abundance, and occurrence frequency in these areas. The qualitative survey showed 145 species in the Estação Ecológica de São Carlos - EESCar (Brotas) - and 173 in the Fazenda Santa Cecília - FSC (Patrocínio Paulista), while the quantitative survey showed the presence of 60 and 72 species in EESCar and FSC respectively. The isolation and the lower environmental quality of the EESCar fragment may be responsible for the lower number of species in this area compared to that of FSC. Abundance index value analysis (IPA) showed that both areas have a large number of species with low IPA and few species with intermediate or high IPA compared to the pattern observed in other surveys. At FSC, a larger number of occurrences of species in danger of extinction in São Paulo State was also observed. Apparently, the FSC fragment had better environmental quality for sheltering a larger number of species, including the endangered ones. The study of the community of birds is important in planning management and conservation of natural areas.

We investigated the feeding habits of the teiid lizard Cnemidophorus littoralis in the markedly seasonal habitat of Restinga da Barra de Maricá (22º57'S, 43º50'W), Rio de Janeiro State, Brazil, to evaluate to what extent its diet is ontogenetically, sexually, and/or seasonally conservative. Lizard stomach contents were analyzed, identified, counted, estimated for volume (in mm³), and grouped in four classes (active, sedentary, and clumped preys, and plant material). The relative contribution of each food class to the total prey volume consumed by adult males and females and juveniles was compared in three ways: between juveniles and adults, sexes, and seasons (wet and dry). Sexual dimorphism in head size was tested by comparing head width and jaw length using analysis of covariance (ANCOVA). Isopterans were the most important prey item, occurring in 93% of the lizard stomachs examined and corresponding to 96.4% of total prey content and 69.7% of total prey volume. They occurred in high frequencies in the stomachs of C. littoralis throughout all study months. We found no sexual, ontogenetic, or seasonal differences in C. littoralis diet although the sexes differed significantly in head width. We concluded that isopterans are the main item in the diet of C. littoralis in Restinga da Barra de Maricá, both for juveniles and adults. The lack of seasonal, sexual, or ontogenetic variation in its diet results from the massive consumption of these insects. Isopterans are small, occur in clumps, and are available year-round, and thus are an advantageous food item for the active forager C. littoralis. We also found sexual dimorphism in the head size of C. littoralis: males have wider heads than females. This dimorphism, however, does not seem to be related with the diet of the species, and is probably a result of sexual selection.

In the present study, two small lakes on the margins of the River Cuiabá were analyzed regarding taxonomic composition and population densities of the zooplankton. Diversity was evaluated for two groups, Rotifera and Cladocera; sampling was carried out on two dates: 2 March 1999, in the rainy season, and 25 August 1999, in the dry season. Seventy-nine rotifer taxa, 30 cladoceran taxa, and 6 copepod taxa were found. Comparing the species identified in the present study with those recorded by other authors for several water bodies in Mato Grosso and Mato Grosso do Sul states, it was found that 9 species of Cladocera, 2 of Copepoda, and 14 of Rotifera are new records for the region. The most abundant rotifer species were Keratella cochlearis, Brachionus angularis, Polyarthra vulgaris, and Keratella americana. Moina minuta and Bosminopsis deitersi were dominant among the cladocerans, and Notodiaptomus transitans and N. devoyorum among the copepods. Comparing both lakes, the greatest species richness of both Rotifera and Cladocera was observed in Lake Souza Lima, during the rainy season. This is probably linked to the fact that the littoral region of this lake is densely colonized by macrophytes. The lake also has better environmental conditions since it does not receive domestic sewage inputs, as does Lake Parque Atalaia. The diversity of the Rotifera was markedly low in Lake Parque Atalaia, during the dry season, again perhaps linked domestic sewage input found in this water body.

High water temperatures and low water quality may negatively influence wound healing, growth and transmitter retention in radio-tagged fish of tropical and subtropical water bodies which in turn may hamper radio tracking studies. For a period of 90 days, we compared growth of an experimental group of ten Rhamdia quelen, which were submitted to intraperitoneal dummy transmitter implantation, with that of a control group. Additionally, wound healing and transmitter expulsion were observed in the experimental group. Water temperature varied between 24°C and 30°C during the study. Experimental group and control fish decreased in body weight during the investigation period, but the differences between the mean individual weight loss in both groups were not significant (Student t-test, p = 0.64). Wound healing in experiment group fish was advanced after 14 days, while after 70 days eight out of ten incision wounds were closed and cicatrized. One fish had its dummy transmitter expulsed through the ventral body wall. After 90 days two more fish had the dummies expulsed, one through the ventral body wall and the other through the antenna exit. One experimental group fish died with visible signs of infection. The results encourage the use of surgically implanted radio transmitters for long-term tagging studies at high water temperatures.

Cladocera communities were studied in lotic and lentic environments of the Upper Paraná River floodplain, State of Mato Grosso do Sul, Brazil. A total of 63 species of Cladocera were identified in 108 samples. Of these, 24 species are considered new records for that floodplain, and one is a new record for Brazil. Chydoridae was the most representative family with 19 genera and 39 species.

The objective of this study was to appraise the occurrence of parasitoids of the family Chalcididae in Itumbiara County, State of Goiás, central Brazil. Insect samples were collected in pastures and native forest areas using pan traps, from January to December 1998. The traps consisted of circular yellow plastic containers (30 cm in diameter and 12 cm in height) containing a mixture of 2 L of water, 2 ml of detergent, and 2 ml of formaldehyde. Samplings were performed weekly by placing 10 traps at soil level (5 traps in the pasture and 5 in the woods). During 1998, 121 specimens of Chalcididae were collected. Haltichella sp.4 was the most abundant species collected (15.7%).

This paper reports the first occurrence of the parasitoid Spalangia endius collected in pupae of Zaprionus indianus using traps with fruit bait. The experiment was carried out at the University of Lavras in Lavras, Minas Gerais, Brazil, from November to December, 2001. A total of 4 Spalangia endius specimens were obtained from 105 Zaprionus indianus pupae. The overall prevalence of parasitism was 3.8%.

ABSTRACT Most information on catfishes of the genus Aspidoras has focused species kept in aquaria, in non-natural conditions. Biotic and abiotic parameters of environment inhabited by Aspidoras fuscoguttatus, associated ichthyofauna, as well as strategies involved in the successful occupation of different microhabitats in a first order stream, located in São José do Rio Preto, São Paulo State, were investigated. Data collection was monthly performed at three segments (headwaters, middle course, and mouth) from August 1999 to July 2000. The greatest values of water temperature, conductivity, turbidity, alkalinity, width, depth, and current velocity were obtained in the rainy season. Dissolved oxygen levels showed significant differences among three segments in all sampling months, except for September. Substrate composition was predominantly sandy, followed by silt and clay in middle course and mouth in rainy as much as in dry seasons. In headwaters a large increase of the sandy fraction occurred in the rainy season. In the marginal and aquatic vegetation 30 species of macrophytes and 5 of macroalgae were identified. The fauna included tadpoles of Anura and macroinvertebrates (Mollusca, Crustacea, Arachnida, and 8 orders of Insecta). A. fuscoguttatus was found throughout the entire stream in sympatry with 6 fish species. In middle course, cluster analysis revealed an association between A. fuscoguttatus immatures and low depth, suggesting a probable function of depth in that stage of ontogenetic development of catfishes. The results indicate that A. fuscoguttatus present plasticity in terms of microhabitat, including air breathing behavior in hypoxic conditions, previously unknown in genus Aspidoras.

Experiments in glucose mineralization were carried out to investigate the effects caused by natural forcing functions on both the decomposition rates and heterotrophy capacity of aquatic ecosystems. In addition, the methodology used could show connections between mineralization rates measured in both laboratory and field work with those measured in aquatic ecosystems. Water samples from Infernão lagoon (21º35'S and 47º51'W) were collected, filtered, enriched with glucose, and incubated under aerobic and anaerobic conditions. The glucose concentration variation, dissolved oxygen (DO) consumption, pH, electric conductivity, and total CO2 amount in the water were determined for sixteen days. In the period with intense oxygen consumption there was also an evident glucose demand and the dissolved oxygen consumption rate was approximately the same as that for glucose mineralization. The process in the aerobic chambers was 2.2 times faster than that in the anaerobic chambers. An initial acidification of the water samples, probably due to microbial carbonic acid liberation, was noted. A rise in pH values was also observed at the end of the process. The electric conductivity was low for both aerobic and anaerobic chambers, indicating a probable ion uptake by microbial organisms due to the presence of carbon sources. The glucose content variations corresponded to both CO2 formation and dissolved oxygen consumption. It was estimated that 19.4% of the initial glucose content turned into CO2 and the remaining 80.6% into humic compounds and microbial biomass. This experiment showed that glucose can be used as a substrate indicating the heterotrophy of a given aquatic ecosystem.

With the objective of studying the spatial and temporal distribution of ''curvina'' Plagioscion squamosissimus larvae and verifying respective spawning sites, monthly sampling was carried out from March 1993 to February 1994 on the Upper Paraná River floodplain. Using a conical-cylindrical plankton net (0.5 mm mesh), samples were taken from the surface of the water bodies, and in the marginal vegetation a strainer and a dragnet (''picaré'') were used. Water samples were collected for environmental variable analysis (temperature, dissolved oxygen, water pH, and electrical conductivity). Water level data were obtained from hydrometric stations. High average density of larvae was found from December 1993 to February 1994 due to high temperature and water level. The Baía sub-area was shown to be the most important in the larvae catch, probably due to its semi-lotic characteristics. Larvae size distribution was shown to be more frequent in the 4.0 mm standard length class, indicating that the sampling stations were next to the spawning sites.

We studied the parasitism by larvae of the chigger mite Eutrombicula alfreddugesi on the lizard community of Restinga de Jurubatiba, Rio de Janeiro State, Southeastern Brazil. We investigated the patterns of infestation (prevalence and intensity) of chigger mites in four sympatric lizards: Tropidurus torquatus, Mabuya agilis, M. macrorhyncha and Cnemidophorus littoralis. All lizards collected were checked for the presence of mites, which were counted under stereomicroscope. We tested the relationship between intensity of infestation and lizard body size for each species using regression analysis. The prevalences and mean intensities (+ one standard deviation) of infestation on each host species were, respectively: 100%; 86.4 + 94.6 in T. torquatus (n = 62); 100%; 20.9 + 9.3 in M. agilis (n = 7); 100%; 11.1 + 13.1 in M. macrorhyncha (n = 12); and 95.2%; 19.1 + 16.8 in C. littoralis (n = 21). Only for C. littoralis did body size significantly affect the intensity of infestation (r = 0.27, p = 0.02). For all lizard species, the body parts where chiggers occurred with the highest intensity were those of skin folds and joint regions.

We studied the distribution of sandflies (Diptera: Phlebotominae) - insect vectors of several diseases, including leishmaniasis - at the interface between primary forest and cattle pasture and between primary forest and secondary forest (< 15 yr old) in Southern Brazilian Amazonia. Sandflies were collected by using a combination of light traps and traps having vertebrates as baits. Strong differences in abundance and species richness were found between primary forests and pastures. Very few sandfly species were found in the pastures, and those that were found generally occurred at lower densities when compared to the adjacent forest. At least one species (Lutzomyia lainsoni), however, can become extremely abundant in pastures, possibly depending on the presence of cattle and water bodies. Differences between primary forests and secondary forests were not so strong, although the latter usually had fewer species and lower population abundances. No species were exclusively found in pastures or secondary forests; the species present in these two habitats were a subset of those found in primary forests. The distance to the edge did not affect the abundance, richness and composition of sandfly species in primary forests. The abundance and richness of sandflies, however, was greater in forest edges facing pastures than those facing secondary forests. This pattern could not be explained by an influx of species and individuals from the adjacent pasture, suggesting the existence of in situ differences between the different types of forest edges studied.

A study of the diatoms Eupodiscus radiatus Bailey and Fryxelliella floridana Prasad, mainly focussing on the mantle and cingulum, provided new morphological information. In E. radiatus dendritic structures and two types of a palisade-like structure fixed to silica rings were found on the lower valve mantle. Cingulum presented 1-3 bands with areolae arranged in decussate rows. Furthermore, the pars interior of the valvocopula is fimbriate; and the external openings of the rimoportulae are located along the rim of the scalloped extension. The valvocopula of F. floridana is open and its copula is ligulate. Both bands possess poroid areolae similar in size to the cribral pores on the valve face. The genus Eupodiscus is compared to Fryxelliella, based on material sampled in estuaries of Southern Brazil.