Alimentação de quatro espécies de Leporinus (Characiformes, Anostomidae) durante a formação de um reservatório no sudeste do Brasil

The study reports the changes ocurred in feeding ecology of fish species during a tropical river reservoir formation. It was analysed the stomachal contents of 399 individuals belonging to four species of genus Leporinus (L. elongatus Valenciennes, 1849, n=157; L.friderici (Bloch, 1794), n=87; L. octofasciatus Steindachner, 1917, n=107; L.amblyrhynchus Garavello & Britski, 1987, n=48) during formation of Nova Ponte reservoir, State of Minas Gerais, Brazil, in 1993 and 1994. Specimens were separated by sampling period, according with the rate of filling of the reservoir, and standard lenght classes. The species had included in diet vegetal and animal items of autochtone and alochtone origin in several proportions. L. amblyrhynchus fed on basically dipterans in all the sampling periods and length classes. L. elongatus had presented a diverse diet, with predominance of dipterans and vegetal items, and changed the consumed items proportions along the sampling periods and between lenght classes. L. friderici diet was composed mainly by terrestrial insects during the rapid filling period, that were later substituted by fishes and vegetal items. Ontogenetic trophic changes were observed in this species. L. octofasciatus presented a well characterized herbivorous diet, without trophic ontogeny, but with a opportunistic character. Just three pair-species, L. amblyrhynchus-L. elongatus, L. friderici-L. octofasciatus and L. elongatus-L. octofasciatus, have presented some high value of trophic overlap in at least one sampling period. In spite of the fishes of the genus Leporinus being classified like omnivorous in a general way, the differences found between diets of these four species suggest that there is structuration of trophic niches in the reservoir.

Reprodução de peixes (Osteichthyes) em afluentes do reservatório de Volta Grande, Rio Grande, Sudeste do Brasil

The most abundant species caught in the tributaries of the Volta Grande dam, Buriti, Divisa and Água Comprida streams were Plagioscion squamosissimus (Heckel, 1840), Pimelodus maculatus Lacépède 1803, Myleus tiete (Eigenmann & Norris, 1900), Astyanax bimaculatus (Linnaeus, 1758) and A. fasciatus (Cuvier, 1819). Plagioscion squamosissimus and Pimelodus maculatus do not have reproduction activity in the area, they just use the creeks to food and growth. Myleus tiete and Astyanax bimaculatus use the area to reproduction whereas A. fasciatus uses it to reproduction, food and growth.

Ultra-estrutura de glândulas abdominais tegumentares em Oxaea flavescens (Hymenoptera, Andrenidae, Oxaeinae)

The sternal glands of the abdomen of Oxaea flavescens (Klug, 1807) consist of class III glandular cells around a reservoir constituted by branched folds of the intersegmental membrane of segments III, IV and V. The gland cells are rich in rough endoplasmic reticulum and produce a secretion with mucous aspect. The treatment with oxidated osmium and ruthenium red showed numerous Golgi regions in the cell and carbohydrates absorption from the haemolymph, respectively. The high degree of development of the glands suggests an important function to the species, although still unknown.

Dieta de espécies de Anostomidae (Teleostei, Characiformes) na área de influência do reservatório de Manso, Mato Grosso, Brasil

The diet of four species of Anostomidae (Leporinus friderici Bloch, 1794, L. striatus Kner, 1858, L. elongatus Valenciennes, 1849 and Leporinus sp.) were investigated in the Manso Reservoir, Mato Grosso State, Brazil. Fish were sampled in three sites: upriver, in the main body of the reservoir, and below the dam. Were analized 276 stomachs. The diet was evaluated using the frequency of ocorrence and volumetric methods. Leporinus friderici showed tendency to herbivory, mainly in the upriver site. In the reservoir and below the dam, it consumed large quantities of fish; Isoptera only in the reservoir. Leporinus striatus and L. elongatus have similar diets, consuming Chironomidae larvae (Diptera), whereas Leporinus sp. was more generalist, feeding similar proportions of vegetable, detritus and insect (Chironomidae and Ephemeroptera). The mouths of the species have different positions: terminal in L. friderici, subterminal in L. elongatus and intermediate in L. striatus and Leporinus sp. The diet overlap values were low, except for L. friderici and Leporinus sp. (0.7) in the upriver, and L. striatus and L. elongatus (0.6) below the dam.

Synchaeta jollyae (Shiel & Koste) (Rotifera, Synchaetidae): an overlooked species or a newcomer in Neotropical freshwaters?

Populations of Synchaeta jollyae (Shiel & Koste, 1993) (Rotifera), a species recently recorded for the first time in Brazil and South America, were analyzed in reservoirs in Southeast Brazil. Sampling was carried out monthly from August 2006 to July 2007 at Furnas Reservoir in the Rio Grande basin, state of Minas Gerais, and in four cascade reservoirs in the Tietê River basin (Barra Bonita, Bariri, Ibitinga and Nova Avanhandava) state of São Paulo, in June and September 2008 and in January and May 2009. Synchaeta jollyae occurred in most samples and periods. From the results obtained it is evident that S. jollyae occurs in water bodies of varied trophic status but reaches larger populations in eutrophic water bodies and during lower temperature periods. The greatest densities of S. jollyae were found in the eutrophic Bariri Reservoir, on the Tietê River, during the winter. Mann-Whitney test confirmed the significant difference between the population densities in periods of high and low temperatures, with populations reaching higher densities at lower temperatures. It is not yet possible to tell whether S. jollyae is a widely distributed species that has been overlooked in previous plankton studies in South America. Wherever these populations of S. jollyae might have originated, it appears to be a species well established and adapted to a wide range of conditions in the Neotropics.

Trophic ecology of Lontra longicaudis (Carnivora, Mustelidae) in lotic and semilotic environments in southeastern Brazil

Lontra longicaudis (Olfers, 1818) (Carnivora, Mustelidae) is a semi-aquatic animal spread through the Central and South America, except in Chile. The implantation of a hydroelectric power plant along a river alters the dynamics of the watercourse, transforming a lotic environment into a lentic or semilotic one, what can damage the otter's feeding. From April 2008 to March 2009 we analysed the otter's food habits in lotic (streamlet) and semilotic (hydroelectric reservoir) environments of Paranapanema Valley, in southeastern Brazil. Aiming to compare the otter's diet of these two environments, we analyzed statistically the frequency of occurrence of main items in the scats. Fishes represent the base of the diet both in the reservoir and in the streamlet and, despite of the total otter's diet showing up similarities in the two environments, the results evidenced modifications on the fish species consumed between them. In the reservoir the otters ate more exotic fish Oreochromis niloticus (Linnaeus, 1758) probably because it is an easy capture prey in this place. The fact that the otters get established and feed in the reservoir doesn't mean that this structure is benefic to the species because the food supplied for it consists mainly of exotic fish species.

Taxonomy, distribution and population structure of invasive Corbiculidae (Mollusca, Bivalvia) in the Suquía River basin, Córdoba, Argentina

Invasive species are one of the most significant causes of biodiversity loss and changes in ecosystem services, which underlines the importance of their detection and their study. The Asian clams (Corbiculidae) are invasive organisms that accidentally entered the La Plata River, Argentina, presumably in the 1960s. The objectives of the present study were to identify the corbiculid species and to determine their distribution at several locations along the Suquía River basin, an extended area in central Argentina. In addition, population structure was evaluated monthly during one year, at a site in the city of Córdoba that is characterized by high human influence. The presence of Corbicula fluminea (Müller, 1774) and Corbicula largillierti (Philippi, 1844) in the Suquía River basin is reported for the first time. The former species was found only in a lentic environment (San Roque reservoir), while the latter was also found along the tributary rivers and brooks of the basin. Corbicula largillierti showed variations in average density between the different sites and also in biomass and size classes throughout the study period at the site at Córdoba city. The relative composition of the sediments, flow fluctuation and human pollution may be responsible for the observed differences.

The relative growth and sexual maturity of the freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae) in the northwestern region of the state of São Paulo

The aim of the present study was to determine the size at sexual maturity in the freshwater crab Dilocarcinus pagei Stimpson, 1861, from a population located in Mendonça, state of São Paulo, Brazil. The crabs were sampled monthly (July 2005 to June 2007), at Barra Mansa reservoir. The specimens were captured manually or in sieves passed through the aquatic vegetation. The crabs were captured and separated by sex based on morphology of the pleon and on the number of pleopods. The following dimensions were measured: carapace width (CW); carapace length (CL); propodus length (PL); and abdomen width (AW). The morphological analysis of the gonads was used to identify and categorize individuals according to their stage of development. The morphological maturity was estimated based on the analysis of relative growth based on the allometric equation y = ax b. The gonadal maturity was based on the morphology of the gonads by the method CW50 which indicates the size at which 50% of the individuals in the population showed gonads morphologically mature to reproduction. The biometric relationships that best demonstrated the different patterns of growth for the juvenile and adult stages were CW vs. PL for males and CW vs. AW for females (p<0.001). Based on these relationships, the estimated value to morphological sexual maturity was 21.5 mm (CW) in males and 19.7 mm (CW) in females. The determination of the size at sexual maturity and the adjustment of the data based on the logistic curve (CW50) resulted in a size of 38.2 mm for males and 39.4 mm for females (CW). Based on the data obtained for sexual maturity for D. pagei, we can estimate a minimum size for capture of 40 mm (CW). This minimum size allows at least half of the population to reproduce and retains the juveniles and a portion of the adults in the population.

Subsídio ao melhor conhecimento do tifo exantemático neotrópico no Brasil: presença do virus no leite

In articles, already published, we have proved that the strain V. B. of Brazilian virus, goes through the placenta (Macacus rhesus) (1) and the apparently normal gastro-intestinal tube (1934-1937) (Canis familiaris) (2). Today we present the idea that the Brazilian virus can reach the milk of an animal even when the latter has only the unapparent disease. In former articles (**), we have shown that the goat (Capra hircus) can be an excellent reservoir of Brazilian virus, having the strain V. B. in its blood and presenting a Weil Felix reaction high and in “group”, with the disease unapparent. When the goats are bred in the laboratory, and even in some foci of the disease, they give a negative Weil Felix, being zero for all the nine strains of Proteus. In the interior of Brazil, in many localities, goats substitute cows, in supplying milk for children and adults, and in some districts goat’s milk is considered superior to cow’s milk, possessing marvellous qualities for men, women an children. Having proved, now, that goat’s milk can contain the virus even when the animal presents nothing clinically, and having also shown that this virus goes through the digestive tube apparently sound, it is easy to understand how infants-in-arms, that is, only a few months old, living in strictly domestic surroundings, can contract the disease; we have many such cases on record. Protocol of the experiments: Goat nº 2, white, January 1948. This animal had been inoculated with the V. B. strain of the Brazilian virus in June 1947, via intra-peritoneal, presenting nothing then, not even a feverish reaction. On that occasion it was not possible to isolate the virus of the blood, although the Weil Felix reaction was positive, high and in “group”. Now January 17, 1948, seven months later, the same animal was reinoculated with a semple of virus V. B. in the same manner (intra-peritoneal) two days after bringing forth two sturdy kids. The virus V. B. was obtained from guinea-pig n. 7170 whose thermic graph was as follows: Temperatura – 38,8 – 39,1 – 39,5 – 39,4 –39,8 – 40,4 – 40,2 – 40,1 - + Necropsy – Typical lesions. The spleen weighed 5 grammes. With 3c.c. of emulsion from the nervous system of this guinea-pig, we inoculated not only the goat, as also two guineapigs, number 14 and number 5. The following is the thermic graph of one: - Guinea-pig n. 14 – 38,9 – 39,1 – 39,2 – 39.2 – 40,7 – 41,0 – 40,5 – 40,4 – 40,1 - + Typical lesions. Guinea-pig n. 2 presented the following thermic graph after the infective inoculation: - 39,5 – 39,7 – 39,7 – 39,7 – 39,5 – 39,3 – 39,5 – 39,5 – 39,5 – etc. Clinically, this animal presented nothing unusual, feeding well and suckling the kids normally. The Weil Felix reaction was positive, in “group” high very similar to the reaction obtained in June 1947, with the first infective inoculation. On the third, fourth, fifth, sixth and seventh day after the infective inoculation, we took milk from the goat and inoculated male guinea-pigs via intra-celular and via intra-peritoneal, giving 5 c.c. to each animal. Guinea-pig n. 4663, inoculated with 5 c.c. of milk, via intra-muscular, taken on the third day of the infectaive inoculation, presented the following thermic graph: - 38.8 (*) – 39,1 – 39,0 – 39,1 – 40,1 – 40,1 – 40,8 (**) – 40,8 – Killed – Typical deisions (***). The virus V. B. of this goat, circulated naturally in the blood up to the third day, having passed into the milk, producing nothing in the kids, on account of the natural resistance of these animals to the disease. The Weil Felix reaction and that of Widal for the Burcellas suis, abortus and militensis were negative for the goat and the kids. It is remarkable that, even with inoculation of the living virus after a period of seven months we cannot get a real and absolute immunity of sensitive animals. We shall return to this subject later. The hart Mazama simplicicornis may be a carrier of the virus in Brasil. The experimental serum against the virus of Exanthematic neotropical typhus has not protected guinea-pigs.

A review of achievements of the national schistosomiasis control program in middle and upper Egypt areas

In Egypt the "national schistosomiasis control program" was formulated to control transmission by reduction of prevalence and intensity of current infections, and thereby achieve an acceptable level of schistosomiasis disease control. The program was implemented foremost in Middle Egypt (1977) and Upper Egypt (1980), collectively extending 800 km alongside of the River Nile and accommodate about 10.5 million people. Schistosoma haematobium has been essentially the prevailing species infection in both areas. The strategy of control entailed both area-wide mollusciciding with niclosamide, and selective population chemotherapy with metrifonate. Evaluation in 1986 showed that prevalence dropped from pre-control 29.4% in Middle Egypt and 26.3% in Upper Egypt to 6% and 7.8% respectively, together with a remarkable drop of infections among children. Also mean intensity attained low levels consistent of low grade infections. It is evident therefore that in these areas where an enhancement of schistosomiasis infections had been anticipated the employment of the twofold strategy effected a state of low-prevalence/low-intensity signifying a lowered reservoir of infection and a substantial interference with the potentials of transmission.

A potential vector of Schistosoma mansoni in Uruguay

Susceptibily experiments were carried out with a Biomphalaria straminea-like planorbid snail (Biomphalaria aff. straminea, species inquirenda) from Espinillar, near Salto (Uruguay), in the area of the Salto Grande reservoir, exposed individually to 5 miracidia of Schistosoma mansoni (SJ2 and BH2 strains). Of 130 snails exposed to the SJ2 strain, originally infective to Biomphalaria tenagophila, 30 became infected (23%). The prepatent (precercaria) period ranged from 35 to 65 days. The cercarial output was irregular, following no definite pattern, varying from 138 to 76,075 per snail (daily average 4.3 to 447.5 and ending up with death. Three specimens that died, without having shed cercarie, on days 69 (2) and 80 after exposure to miracidia, had developing secondary sporocysts in their tissues, justifying the prospect of a longer precercarial period in these cases. In a control group of 120 B. teangophila, exposed to the SJ2 strain, 40 became infected, showing an infection rate (33.3%) not significantly different from that of the Espinillar snail (X [raised to the power of] 2 = 3.26). No cercarie were produced by any of the Espinilar snails exposed to miracidia of the BH2 strain, originally infective to Biomphalaria glabrata. Four specimens showed each a primary sporocyst in one tentacle, which disappeared between 15 and 25 days post-exposure, and two others died with immature, very slender sporocysts in their tissues on days 36 and 54. In a control group of 100 B. glabrata exposed to BH2 miracidia, 94 shed cercariae (94%) and 6 remained negative. Calculation of Frandsen's (1979a, b) TCP/100 index shows that "Espinillar Biomphalaria-SJ2 S. mansoni" is a vector-parasite "compatible" combination. Seeing that tenagophila-borne schistosomiasis is prevalent in Rio de Janeiro and São Paulo states and has recently spread sothwards to Santa Catarina state, and the range of B. tenagophila overlaps taht of the Espinillar Biomphalaria, the possibility of schistosomiais establishing itself in Uruguay, although not imminent, is not to be disregarded.

Human leptospirosis in a slum area in the city of Rio de Janeiro, Brazil: a serological and epidemiological study

A serologic survey was carried out on slum dwellers in the city of Rio de Janeiro. A total of 259 serum samples from male and female individuals of different age groups were tested for the presence of antileptospire antibodies by microagglutination. Prevalence data were analyzed in relation to the major risk factors present at the site, mainly represented by the presence of carrier animals and the occurence of frequent floods. Of the samples tested, 25% reacted with antigens of different serogroups at titres ranging from 1:100 to 1:6400, with a predominance of titres <= 1:400; 35% of positive sera reacted with leptospirae of the Icterohaemorrhagiae serogroup. Reactions with Djasiman, Panama, Javanica, Canicola, Pyrogenes, Australis, Ballum, Sejroe, Bataviae, Grippotyphosa, Autumnalis and Cynopteri were also detected, though at lower frequencies. There was no statistically significant difference between sexes, but higher prevalence rates were found to be associated with increasing age. A focus of infection was characterized, in which social and economic factors contribute to the persistance of leptospirae by favoring the proliferation of the main reservoir.

Trypanosoma nupelianus sp. n. (Protozoa, Kinetoplastida) parasitizing rhinelepis aspera (Osteichthyes, Loricariidae) from Paraná river, Brazil

It is described Trypanosoma nupelianus sp. n. parasitizing Rhinelepis aspera taken from Paraná river (Itaipu reservoir, Brazil). Morphometric characters such as body length, width of the body and nucleus dimensions show that T. nupelianus sp. n. is different from other trypanosomes described for fishes from tropical regions.

Macrophage activation and histopathological findings in Calomys callosus and Swiss mice infected with several strains of Trypanosoma cruzi

Peritoneal macrophage activation as measured by H2O2 release and histopathology was compared between Swiss mice and Calomys callosus, a wild rodent, reservoir of Trypanosoma cruzi, during the course of infection with four strains of this parasite. In mice F and Y strain infections result in high parasitemia and mortality while with silvatic strains Costalimai and M226 parasitemia is sub-patent, with very low mortality. H2O2 release peaked at 33,6 and 59 nM/2 x 10(elevado a sexta potência) cells for strains Y and F, respectively, 48 and 50 nM/2 x 10 (elevado a sexta potência) for strains Costalimai and M226, at different days after infection. Histopathological findings of myositis, myocarditis, necrotizing artheritis and abscence of macrophage parasitism were foud for strains F and Costalimai. Y strain infection presented moderate myocarditis and myositis, with parasites multiplying within macrophages. In C. callosus all four strains resulted in patent parasitemia wich was eventually overcome, with scarce mortality. H2O2 release for strains Y or F was comparable to that of mice-peaks of 27 and 53 nM/2 x 10 (elevado a sexta potência) cells, with lower values for strains Costalimai and M226 - 16.5 and 4.6 nM/2 x 10(elevado a sexta potência)cells, respectively. Histopathological lesions with Y and F strain injected animals were comparable to those of mice at the onset of infections; they subsided completely at the later stages with Y strain and partially with F strain infected C. callosus. In Costalimai infected C. callosus practically no histopathological alterations were observed.

Megathylacus travassosi sp. n. e Nomimoscolex sudobim Woodland, 1935 (Cestoda - Proteocephalidea) parasitos de Pseudoplatystoma corruscans (Agassiz, 1829) (Siluriformes - Pimelodidae ) do reservatório de Itaipu e Rio Paraná, PR, Brasil)

It is described Megathylacus travassosi sp. n., parasite of Pseudoplatystoma corrusccans (Agassiz,1829), a pimelodid fish caught in Itaipu reservoir and Paraná river, Brazil. Nomimoscolex sudobim Woodland, 1935 is redescribed and for the first time referred parasitising P. corruscans. The list of proteocephalid cestodes of genus Pseudoplatystoma Bleeker, 1862, with its geographic distribution is given.