Aspectos reprodutivos de três espécies de Curimatidae (Characiformes) em um reservatório do Rio Mogi Guaçu, bacia do Alto Rio Paraná, São Paulo, Brasil

Os curimatídeos são espécies comuns em ambientes lênticos represados, artificialmente construídos. Estudar o ciclo reprodutivo de uma espécie é fundamental para a compreensão da biologia reprodutiva da população em seu ambiente. Por isso, o presente estudo analisou os aspectos da biologia reprodutiva dos sagüirus Cyphocharax modestus, C. cf. nagelii e Steindachnerina insculpta (Curimatidae), no reservatório da pequena central hidrelétrica Mogi Guaçu, município de Mogi Guaçu, estado de São Paulo. Os exemplares foram coletados bimensalmente entre agosto de 2005 e julho de 2006 com o auxílio de redes de emalhar (malhas 1,0 a 5,0 cm entre nós adjacentes), totalizando seis amostras. No total, foram analisados 777 exemplares, sendo 525 de C. modestus, 82 de C.cf. nagelii e 170 de S. insculpta. A dinâmica reprodutiva foi analisada considerando-se os períodos seco e chuvoso. A fecundidade foi estimada de acordo com o método volumétrico a partir da análise de 168 pares de ovários maduros, sendo 121 de C. modestus, 18 de C. cf nagelii e 29 de S. insculpta. Também foram estimadas as relações gonadossomáticas médias e as correlações do número total de ovócitos em relação ao peso e ao comprimento para cada uma das três espécies. Os resultados encontrados apontaram para desova total (sincrônica em dois grupos) para as três espécies. O número médio de ovócitos foi de 15.309 a 28.825 para C. modestus, 29.031 para C. cf. nagelii e 27.206 para S. insculpta

Impacts of urbanization on fish assemblage in streams of the upper Paranapanema river basin (SP), Brazil

Aquatic ecosystems have suffered strong anthropogenic pressure, through the construction of dams, water exploitation, chemical pollution, destruction of the surrounding environment, especially riparian vegetation, and structural changes such as channeling and siltation. Fish assemblages may respond in different ways to these environmental changes, because species exhibit different constraints, e.g., habitat demands, physiological tolerance. Thus, some species may be favored in detriment of others. Aware of the need to understand and identify the patterns response of fish assemblages and individual organisms to impact factors, this study aimed to investigate how fish biodiversity (i.e., assemblages and population-scale) respond to urbanization. Fish samples were collected in four stretches located in urban areas and six located in non-urban areas of the upper Paranapanema river basin. Chapter I focused on detecting changes in physical habitat variables, structure and composition of the fish assemblage. Multivariate analyses ordered stretches in a urbanized non urbanized gradient. Non urbanized stretches exhibited greater values of shading, vegetated surronding and coarser substrate. Assemblage structure, i.e., Shannon diversity index, Pielou evenness and Margalef richness, did not change in response to urbanization, as well as the relationship between abundance and biomass. In contrast, assemblages composition was different, as well as richness estimates based on rare species, which was lower in urban stretches. The patterns herein obtained illustrate the process of species replacement, already demonstrated in disturbed environments, in which species pre-adapted to the new conditions increase in abundance, while otherspreviously absent establish successfully. Therefore, diversity values maintain, but composition varies. In general, midwater omnivorous species were more abundant in urban areas, while loricarids and benthic invertivores presented higher average abundance in nonurban stretches. Chapter II aimed to identify changes in the trophic structure, substrate composition and its influence on trophic structure and body condition. For this, species diet was quantified according to the Degree of Food Preference (DFP) method, based on six items: plant material, algae, detritus, invertebrates, insects and fish. According to the items consumed, species were classified in trophic groups. Fourteen species were considered invertivorous/detritivorous, seven herbivorous/detritivorous, seven omnivorous and one piscivorous. Four invertivores/insectivores were exclusive of nonurban stretches and one species exclusive of urban stretches. Three herbivores/detritivores were exclusive of the nonurban stretches, whereas three omnivores were exclusive to urban stretches. Trophic structure richness, abundance and biomass were compared between urban and nonurban stretches. Abundance was not affected by urbanization, whereas richness and biomass varied between stretch groups. Substrate composition differed according to stretch type, and was positively related to invertivores/insectivores and herbivore/detritivores richness, whereas negatively related to omnivore biomass. These results suggest complex relationships between food availability, trophic plasticity and species foraging habits. It is known that coarser substrates such as rocks, branches and trunks are useful as surface for periphyton algae growth as well as shelters for aquatic macroinvertebrates. Thus, changes in substrate may alter resources availability for certain species. Omnivores, in turn, can find other sources of food items due to its trophic plasticity. In general, almost all species absent from urban stretches exhibit some trophic specialization and often depend on heterogeneous substrate for foraging. Moreover, species exclusive to urban stretches are mid-water foragers that do not depend on substrate and present high trophic plasticity. Our conclusions were supported by Astyanax fasciatus body condition analysis, an omnivorous nektonic species which demonstrated higher mean weight in urban stretches, when discounted length.Universidade Federal de Minas GeraisEcossistemas aquáticos têm sofrido forte pressão antropogênica, que se manifesta na construção de barragens, captação de água, poluição química, destruição do ambiente de entorno, principalmente mata ripária, e alterações estruturais como canalizações e aporte de sedimentos. A assembleia de peixes pode responder de diversas formas a estas alterações ambientais, dado que as espécies possuem diferentes exigências fisiológicas e de habitats. Com isso, algumas espécies podem ser eliminadas e outras favorecidas. Cientes da necessidade de compreender e identificar o padrão das respostas da assembleia e organismos aos vetores de impacto, neste trabalho buscamos investigar como a ictiofauna responde à urbanização. Para isso, os peixes foram coletados em quatro trechos localizados em áreas urbanas e cinco localizados em áreas não urbanas, sempre em riachos da parte superior da bacia do alto rio Paranapanema. O capítulo I buscou detectar alterações nas variáveis físicas do hábitat, na estrutura e na composição da assembléia de peixes. Utilizando as variáveis ambientais, os trechos foram ordenados no sentido urbanizado-não urbanizado, sendo que estes últimos apresentaram valores maiores de sombreamento, área, substrato e vegetação de entorno. Verificamos que a estrutura da assembleia, representada pelos índices de diversidade de Shannon, equabilidade de Pielou e riqueza de Margalef, não sofreu alterações em resposta à urbanização, bem como a relação entre abundância e biomassa. No entanto, a composição da assembleia foi diferente e a riqueza estimada com base nas espécies raras foi menor nos trechos urbanos. Simultaneamente, a variação nos componentes ambientais explicou a variação na composição da assembleia. Estes resultados evidenciam um processo de substituição de espécies descrito para ambientes alterados, no qual espécies pré-adaptadas às novas condições aumentam em abundância e outras antes ausentes se estabelecem. Assim, a diversidade é mantida, porém, alterando a composição. Em geral, espécie onívoras forrageadoras de meia água foram mais abundantes em áreas urbanas, ao passo que loricarídeos e invertívoros bentônicos apresentaram maior abundancia média em trechos não urbanos. No Capítulo II, o objetivo foi identificar alterações na estrutura trófica, composição do substratro, influência deste na estrutura trófica e condição corporal. Para isso, a dieta das espécies foi quantificada de acordo com o método do Grau de Preferência Alimentar (GPA) para seis itens: material vegetal, algas, detrito, invertebrados, insetos e peixe. De acordo com os itens consumidos, as espécies foram classificadas em categorias tróficas. Quatorze espécies foram consideradas invertivoras/detritívoras, sete herbívoras/detritívoras, sete onívoras e uma piscívora. Quatro espécies de invertívoros/insetívoros foram exclusivas de trechos não urbanos e uma dos urbanos. Três espécies herbívoras/detritívoras foram exclusivas de riachos do tipo não urbano, o inverso dos onívoros, com 3 espécies exclusivas de riachos do tipo urbano. A partir da classificação trófica, os trechos urbanos e não urbanos foram comparados quanto à estrutura trófica em relação à riqueza, abundância e biomassa. A abundância não foi alterada pela urbanização, no entanto a riqueza e a biomassa diferiram entre os tipos de riacho. A composição do substrato, que foi diferente entre os tipos de riacho, esteve positivamente relacionada com a riqueza de invertívoros/insetívoros, de herbívoros/detritívoros e negativamente relacionada com a biomassa de onívoros. Estes resultados ilustram um processo intrincado de relações entre a disponibilidade de alimentos, plasticidade trófica e hábitos de forrageamento das espécies. Sabe-se que substratos como rochas, galhos e troncos são úteis como superfície de crescimento de algas do perifíton e também como abrigos para macroinvertebrados aquáticos. Desse modo, alterações na composição do substrato podem modificar a disponibilidade de recursos para determinadas espécies, dependentes de algas e invertebrados aquáticos, especialmente insetos imaturos. Os onívoros, por sua vez, podem encontrar outras fontes de recurso devido a sua conhecida plasticidade trófica. De maneira geral, praticamente todas as espécies ausentes dos trechos urbanos possuem alguma especialização trófica e costumam ser dependentes do substrato para o forrageamento. Por outro lado, as espécies que ocorreram apenas nos trechos urbanos são forrageadoras de meia água, não depedentes do substrato e com alta plasticidade na dieta. Esta conclusão foi amparada pela análise da condição corporal de Astyanax fasciatus, um onívoro nectônico que, quando teve descontado o comprimento do corpo, apresentou maior peso médio nos trechos urbanos

Less effort but equal result: Introducing the daily run-size estimation method for quantifying fish passage in fishways.

Determining the number of fish that use a fishway is essential to fisheries management but counting all fish can be impracticable due to labor and cost. We present the daily run-size estimation (DARSE) method, which uses systematic sampling to estimate the number of fish per species that pass through a fishway daily (daily run size, D). The DARSE method makes it possible to determine the minimum fraction of each hour (or hourly samples) of the day necessary to estimate D with known accuracy. We apply DARSE to each of the seven most abundant fish species (other species grouped under 'Others') recorded in video images taken during 46 days of one year at the Igarapava Fish Ladder, Brazil. Accuracy in estimating D was influenced by the fraction of the hour sampled and the temporal pattern of fish passage through the fishway. For species with a more uniform temporal pattern of passage, the DARSE method reduced the time spent on sampling by up to 96%, depending on the accuracy used to estimate D. Some of these species required counts of fish that pass in a fraction of an hour for all hours of the day while counts for other species can be done every 2 hours or, more rarely, every 3 hours. For species with a more aggregated temporal pattern of passage, it was possible to estimate D by sampling a fraction of an hour but with reduced accuracy in the estimation of D and little reduction in sampling time

First adult record of Misgurnus anguillicaudatus, Cantor 1842 from Ribeira de Iguape River Basin, Brazil

AIM: This work aimed to describe a first record of Misgurnus anguilicaudatus, Cantor 1842 in São Paulo state, as well as your potential impacts on native populations. METHODS: The specimen was caught by eletro-fishing device, in Itaguapeva river, Ribeira do Iguape river basin, Ibiuna (SP), Brazil. Later, it was fixed in 10% formalin and taken to laboratory for species identification, morphometric data evaluation, diet analysis and stage of gondal maturity. RESULTS: The individual was an adult female, without parasites and with gonads in maturity stage B, which indicates vascularized ovaries and presence of oocytes in vitellogenesis process. The dietary analysis showed that 95.3% of the stomach was occupied by insect larvae. CONCLUSIONS: The diet analysis may suggest food overlap and consequent competition for food with native species of the genera Trichomycterus e Characidium, which consume essentially the same items. Still, the great morphological similarity with native species, especially Siluriformes, could generate competition for shelters. Additionally, the stage of gonadal maturity and a recorded ability of the species on establish invasive populations in different environments raise concerns about the possibility of Misgurnus anguillicaudatus reproduction on the studied site

Dendritic Cell-Lymphocyte Crosstalk Downregulates Host Restriction Factor SAMHD1 and Stimulates HIV-1 Replication in Dendritic Cells

Human immunodeficiency virus type 1 (HIV-1) replication in dendritic cells (DCs) is restricted by SAMHD1. This factor is counteracted by the viral protein Vpx; Vpx is found in HIV-2 and simian immunodeficiency virus (SIV) from sooty mangabeys (SIVsm) or from macaques (SIVmac) but is absent from HIV-1. We previously observed that HIV-1 replication in immature DCs is stimulated by cocultivation with primary T and B lymphocytes, suggesting that HIV-1 restriction in DCs may be overcome under coculture conditions. Here, we aimed to decipher the mechanism of SAMHD1-mediated restriction in DC-lymphocyte coculture. We found that coculture with lymphocytes downregulated SAMHD1 expression and was associated with increased HIV-1 replication in DCs. Moreover, in infected DC-T lymphocyte cocultures, DCs acquired maturation status and secreted type 1 interferon (alpha interferon [IFN-α]). The blockade of DC-lymphocyte cross talk by anti-ICAM-1 antibody markedly inhibited the stimulation of HIV-1 replication and prevented the downregulation of SAMHD1 expression in cocultured DCs. These results demonstrate that, in contrast to purified DCs, cross talk with lymphocytes downregulates SAMHD1 expression in DCs, triggering HIV-1 replication and an antiviral immune response. Therefore, HIV-1 replication and immune sensing by DCs should be investigated in more physiologically relevant models of DC/lymphocyte coculture.Fil: Su, Bin. Inserm; FranciaFil: Biedma, Marina Elizabeth. Inserm; Francia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lederle, Alexandre. Inserm; FranciaFil: Peressin, Maryse. Inserm; FranciaFil: Lambotin, Mélanie. Inserm; FranciaFil: Proust, Alizé. Inserm; FranciaFil: Decoville, Thomas. Inserm; FranciaFil: Schmidt, Sylvie. Inserm; FranciaFil: Laumond, Géraldine. Inserm; FranciaFil: Moog, Christiane. Inserm; Franci

Variation in the diet of a small characin according to the riparian zone coverage in an Atlantic Forest stream, northeastern Brazil

AIM: in this study we present data from the diet of Astyanax vermilion which were used as a tool to compare two sites of streams with different vegetation cover in Ribeirão Limoeiro, Cachoeira River Basin, BA. METHODS: Four samples were taken (March, June, September and December) using electrofishing as the collection method in two contiguous sites of the headwaters: stretch without riparian vegetation and with riparian vegetation. RESULTS: The qualitative composition of the diet was analyzed by the method of frequency of occurrence. The allochthonous resources of vegetal origin made up the bulk of the diet in the stretch without riparian vegetation with a frequency of occurrence of 64%. In the section with riparian vegetation allochthonous resources of animal origin made up the bulk of the diet with a frequency of 62%, which emphasizes the importance of food items from the surrounding environment. The mean Shannon diversity index, calculated from the frequency of occurrence of food items was significantly different (p = 0.04) when comparing reach deforested (H'= 1.44) with reach forested (H'= 1.80). The average weight of stomachs in the deforested reach (WS D = 0.18g) was significantly higher than that of the forested reach (WS F = 0.14g). CONCLUSIONS: in the stretch with riparian vegetation, the food diversity was greater and the fish that are in the riparian stretch do not need as much food to satisfy their physiological needs. These results underscore the importance of the type of riparian vegetation as a food source for fis

Life-history strategies associated to reproduction of three Hyphessobrycon species (Characidae) in lentic environments of upper Paraná River basin

AIM: Life-history strategies in fish include essential parameters related to offspring survivorship, fecundity and time of reproduction, which represent adaptive traits that enable a species to deal with spatial and temporal variability of abiotic conditions. This study aimed to compare reproductive traits associated to life-history theory for three Hyphessobrycon species from two lentic environments (four natural oxbow lakes and a man-made reservoir) of Mogi Guaçu River, upper Paraná River basin. METHODS: Specimens were collected with four minnow traps between August 2005 and July 2006 to cover dry and wet seasons (three samples in each season, and three samples in each environment). RESULTS: Reproductive strategy of H. bifasciatus and H. eques, which predominated in the oxbow lakes, differed from H. anisitsi in the reservoir. Hyphessobrycon bifasciatus and H. eques were single spawners with lower fecundity and size at sexual maturity, but invested more in number of eggs per body gram, while H. anisitsi was a multiple spawner species with higher fecundity, larger size at sexual maturity and body size. CONCLUSIONS: In seasonal environments, single spawners are synchronized with the floods to maximize juvenile survivorship, while reservoirs harbors multiple spawners’ fish due to the reduced fluctuation between high and low floods resulting from dam operation. Therefore, the seasonal condition in the oxbow lakes due to the flood pulse favored single spawners’ tactic, as showed by H. bifasciatus and H. eques. In contrast, the multiple spawning of H. anisitsi seems to be related to the more stable environmental condition throughout the year provided by the dam. Life-histories reported herein to Hyphessobrycon species must be common to other characid fishes inhabiting similar environments