Growth performance and energetic metabolism of pacu, Piaractus mesopotamicus (Holmberg, 1887), fed diets supplemented with ammonium metavanadate

Vanadium compounds mimic most of the metabolic effects of insulin, suggesting that it might be useful to improve utilization of dietary carbohydrate. This work evaluated the effect of dietary ammonium metavanadate (H(4)NO(3)V) on the growth performance and energy metabolism of pacu, an omnivorous South America characin. Two hundred and eighty-eight fish were distributed into four blocks according to the body weight (21.8 +/- 1.7, 28.5 +/- 2.0, 28.4 +/- 1.9, 35.7 +/- 1.9 g), stocked in 24 plastic tanks and fed twice daily with isonitrogenous and isoenergetic diets containing six levels of H(4)NO(3)V (0, 10, 50, 100, 300 and 1000 mg kg(-1)) for 60 days. Increasing levels of dietary ammonium metavanadate did not improve growth (P > 0.05), and the highest level of inclusion (1000 mg kg(-1)) reduced performance (P < 0.05). Blood glucose levels decreased (P < 0.05) in fish fed 300 and 1000 mg kg(-1) H(4)NO(3)V, but no differences were observed in other blood metabolites. A slight increase in muscle lipid content was observed in fish fed a diet containing 300 mg kg(-1) H(4)NO(3)V. Based on the results of this study, there is no benefit in supplementing pacu diets with metavanadate.

Leukocytes respiratory burst and lysozyme level in pacu (Piaractus mesopotamicus Holmberg, 1887)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do crescimento e do custo da alimentação do pacu (Piaractus mesopotamicus Holmberg, 1887) submetido a ciclos alternados de restrição alimentar e realimentação

Avaliaram-se os efeitos da utilização de ciclos alternados de restrição alimentar e realimentação no crescimento do pacu, durante o período de engorda, e a viabilidade desta prática na produção comercial da espécie. Juvenis foram distribuídos em três tanques e submetidos a diferentes manejos alimentares, constituindo os tratamentos: A (alimentado ad libitum), B (restrição alimentar de 4 semanas, realimentado por 9 semanas) e C (6 semanas de restrição alimentar, realimentado por 7 semanas), em um total de 13 semanas por ciclo (4 ciclos experimentais). No final de cada ciclo alimentar, 20 peixes de cada tratamento foram amostrados e os dados biométricos registrados. Os valores obtidos para peso, comprimento total e fator de condição (K) foram submetidos a ANOVA e as médias comparadas pelo teste de Duncan. Os resultados mostraram que o tratamento C é o mais indicado somente para outono/inverno, promovendo maior crescimento, menor custo com ração, baixa conversão alimentar e maior receita líquida parcial. Entretanto, durante as estações mais quentes do ano (primavera/verão) outros programas de alimentação devem ser testados, utilizando-se períodos mais curtos de restrição alimentar. Quando se tratou da produção anual, o tratamento A respondeu melhor em termos de biomassa produzida, apesar do maior gasto com alimentação, visto que, com o aumento da temperatura, o crescimento dos peixes dos demais tratamentos ficou prejudicado.

Kinetics of cellular component in inflammatory response induced by different stimuli in the swim bladder of pacu, Piaractus mesopotamicus Holmberg 1887 (Characidae)

The present study assessed the kinetics of cell accumulation at the site of inflammation induced by thioglycolate, Escherichia coli lipopolysaccharide (LPS) and heat-inactivated Aeromonas hydrophila, in the pacu, Piaractus mesopotamicus (Characidae), swim bladder. A quantitative, as well as qualitative, assessment was done of all the cells present in the exudate at 6, 24, and 48 h (n = 8) after inoculation of inflammatory agents. The results show that the thioglycolate was the irritant to induce higher total inflammatory cell accumulation when compared to the control group, 6 h after insult (P < 0.05). Inoculation of heat-inactivated Aeromonas hydrophila induced progressive accumulation of total inflammatory cells, with cell number peaking after 24 h and being significantly higher than observed in the other groups (P < 0.05). Injection of LPS also induced greater cell accumulation when compared to the control group (P < 0.05), although in lower numbers than those induced by the other two irritants. All irritants injected induced significantly greater accumulation of lymphocytes and thrombocytes when compared to the control group (P < 0.05).

Histopathology of gills of Piaractus mesopotamicus (Holmberg, 1887) and Prochilodus lineatus (Valenciennes, 1836) infested by monogenean and myxosporea, caugth in Aquidauana River, State of Mato Grosso do Sul, Brazil

Realizou-se análise histológica de brânquias de 15 espécimes de Piaractus mesopotamicus e 19 Prochilodus lineatus coletados de abril a novembro de 2004, no Rio Aquidauana, MS, com intuito de contribuir com achados anatomopatológicos em brânquias dessas espécies de peixes de água doce. Amostras de brânquias foram fixadas em formalina 10%, tamponadas e processadas conforme rotina histológica. em P. mesopotamicus observou-se presença de monogênea e cistos de mixosporídio da espécie Henneguya piaractus, com localização intralamelar em vários estágios de desenvolvimento, localizados em todas as regiões (basal, mediana ou distal) das lamelas. Cistos intraepiteliais causaram dilatação e deformação das lamelas vizinhas. em brânquias de P. lineatus, observou-se presença de monogênea. Nas duas espécies de hospedeiro foram registradas hiperplasia do epitélio branquial e desorganização estrutural das lamelas em extensas regiões, alterações que causaram a fusão lamelar. em poucos casos registrou-se presença de células inflamatórias mononucleares e focos hemorrágicos na região distal das lamelas.

Cell Death in Salivary Glands of Rhipicephalus (Boophilus) microplus (Canestrini, 1887) (Acari: Ixodidae) Females at Semi-engorged Feeding Stage

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

Structural analysis of the Pimelodus maculatus (Lacépède, 1803) embryogenesis (Siluriformes: Pimelodidae)

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

Morphological and histochemical study of the myotomal muscle in pacu (Piaractus mesopotamicus Holmberg, 1887) during the initial growth phases

Morphological and histochemical methods were used to evaluate the myotomal muscle characteristics of pacu (Piaractus mesopotamicus) from hatching to 40 days old. During the larval period, the musculature consisted predominantly of white muscle. White and red muscle mass increased at 10, 20, 30 and 40 days after hatching. The larvae had round muscle fibers with a moderate degree of maturation and central nuclei. In subsequent phases, small and immature fibers were visible near larger and more differentiated fibers. Undifferentiated cells or presumptive myoblasts located in embryogenic zones were visible in the dorsal and ventral regions, and were more evident at 30 and 40 days. The red muscle fibers located in the subdermal region, had oxidative metabolism and slow contraction, whereas the more predominant white muscle fibers had glycolytic metabolism and fast contraction. Our findings indicate that during the initial phases, myotomal muscle growth in pacu occurs by both, muscle fiber hypertrophy and hyperplasia. The analysis of frequency of red and white muscle fibers shows that hyperplastic growth is intense in this period. As the growth rate in adult fish is related to the number of muscle fibers in young fish, extrinsic factors could change the muscle fiber phenotype and influence their ultimate size.

Ultrastructural features of the glandular region of the stomach of Piaractus mesopotamicus (Holmberg, 1887) with emphasis on the oxyntopeptic cell

The characteristics of the lining and glandular epithelial types of the wall of the stomach of pacu (Piaractus mesopotamicus Holmberg, 1887) were studied by transmission electron microscopy. Columnar mucous cells were observed in the lining epithelial surface and the glandular epithelium that invaginated in the lamina propria showed secretory cells or oxyntopeptic cells as called by some authors in the literature. The columnar epithelial cells are narrow and show a basal nucleus. They are rich in organelles and contain secretory granules of round or rectangular shape heterogeneously electron dense in the apical portion. In the basal region of the glands there are secretory cells. The luminal half of these cells has abundant tubules (tubulo-vesicular system) that communicate with the external medium. Deeper basally in the cytoplasm there are the nucleus, mitochondria of various shapes and other scattered organelles.

Differential expression of myogenic regulatory factor MyoD in pacu skeletal muscle (Piaractus mesopotamicus Holmberg 1887: Serrasalminae, Characidae, Teleostei) during juvenile and adult growth phases

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

Stable carbon (delta(13)C) and nitrogen (delta(15)N) isotopes as natural indicators of live and dry food in Piaractus mesopotamicus (Holmberg, 1887) larval tissue

This study proposed the use of the stable isotope technique to track the type of food utilized by pacu Piaractus mesopotamicus larvae during their development, and to identify the moment when the larvae start using nutrients from the dry diet by retaining its carbon and nitrogen atoms in their body tissues. Five-day-old pacu larvae at the onset of exogenous feeding were fed Artemia nauplii or formulated diet exclusively; nauplii+formulated diet during the entire period; or were weaned from nauplii to a dry diet after 3, 6 or 12 days after the first feeding. delta(13)C and delta(15)N values for Artemia nauplii were -15.1 parts per thousand and 4.7 parts per thousand, respectively, and -25.0 parts per thousand and 7.4 parts per thousand for the dry diet. The initial isotopic composition of the larval tissue was -20.2 parts per thousand and 9.5 parts per thousand for delta(13)C and delta(15)N respectively. Later, at the end of a 42-day feeding period, larvae fed Artemia nauplii alone reached values of -12.7 parts per thousand and 7.0 parts per thousand for delta(13)C and delta(15)N respectively. Larvae that received the formulated diet alone showed values of -22.7 parts per thousand for delta(13)C and 9.6 parts per thousand for delta(15)N. The stable isotope technique was precise, and the time at which the larvae utilized Artemia nauplii, and later dry diet as a food source could be clearly defined.

Morphological, histochemical and morphometric study of the myotomal muscle tissue of the pacu (Piaractus mesopotamicus Holmberg 1887: Serrasalminae, Characidae, Teleostei)

Histochemical, ultrastructural and morphometric methods were used to study growth patterns of red, pink and white muscle fibres and their relation to body weight and total length in the fast-growing freshwater fish Piaractus mesopotamicus Holmberg. The correlations amongst body weight, body length and diameter of red, pink and white fibres were low. From 10-15 to 40 50 cm, body weight increased 102.7 times, while the diameter of each type of fibro increased by factors of 0.94, 0.74 and 0.70, respectively. Muscle fibres revealed different morphological and histochemical stages of maturation. The frequencies of < 20 mu-m fibres of red, pink and white muscle tissue in the youngest and oldest classes were 64.5 and 11.0, 38.2 and 7.7 and 24.0 and 1.4%, respectively. In 30-40 cm fish, the frequency of < 20 mu-m fibres in the red and pink tissue was 24.5 and 25.5%, while in the white tissue it was 11.5%. During sexual maturity (40-50 cm), the recruitment of < 20 pm fibres in white muscle was 1.4%. Muscle fibres of this species showed continuous growth by both hyperplastic and hypertrophic mechanisms, and hyperplasia was particularly active in the juvenile phase.

Feeding behaviour and ecosystem role of the red mangrove crab Goniopsis cruentata (Latreille, 1803) (Decapoda, Grapsoidea) in a subtropical estuary on the brazilian coast

This study provides information concerning the feeding behaviour of Goniopsis cruentata (Latreille, 1803), through analysis of stomach contents according to demographic categories. Collections were carried out monthly from May 2005 through April 2006 in a subtropical estuary on the southeastern Brazilian coast (23 degrees 29'24 '' S 45 degrees 10'12 '' W). The crabs were collected by hand, with a 2-hour sampling effort by three people. In the laboratory, the crabs were sexed and measured for greatest carapace width, and grouped into demographic categories: adult males, juvenile males, adult females, juvenile females, and ovigerous females. For the fullness analysis, the stomachs were grouped into two categories: (1) E = Empty, with no food; and (2) F = Full, whether partially filled or totally. The frequency-of-occurrence method was used to characterize feeding behaviour, and the demographic categories recognired were compared. We obtained stomachs from 171 adult males, 69 juvenile males, 136 adult females, 72 juvenile females, and 41 ovigerous females, of which 85.6% were full. of the eight food items recorded, sediment was the most frequent, and unidentified material was the least. Goniopsis cruentata can be characterized as a generalist feeder, exploiting most of the food items available in the mangrove swamps. In spite of this generalist behaviour, the dominant presence of sediment suggests that G. cruentata is primarily a detritivore that exploits particulate organic matter from microbial biodegradation, one of the most important mangrove functions. The trophic role of this crab in the ecosystem showed no significant differences among the demographic categories, and seems to be wider than those observed for sesarmid and ocypodid mangrove crabs. These ecosystem engineers may occupy different positions in the trophic chains of estuarine environments.

Morphometric study of the ghost crab Ocypode quadrata (Fabricius, 1887) (brachyura, ocypodidae) from Ubatuba, São Paulo, Brazil

A morphometric study of the ghost crab Ocypode quadrata from Ubatuba, São Paulo, Brazil, focusing on the relationships between carapace width and carapace length, abdomen width, gonopod length and propodus length and height of the major cheliped is presented. An allometric positive growth was found for most of the analyzed relationships; however, important changes in the gonopod and abdomen were observed at the size at which sexual maturity is attained. Morphological (external) sexual maturity for both sexes is achieved at a smaller size than that at which gonad maturity is reached. Concerning heterochely, 53.3% of the analyzed specimens exhibited a longer propodus length in the right cheliped.