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).

Alternative treatment for Anacanthorus penilabiatus (Monogenea : Dactylogyridae) infection in cultivated pacu, Piaractus mesopotamicus (Osteichthyes : Characidae) in Brazil and its haematological effects

The present work, studied the effect of 0, 1,000, 1,500 and 2,000 mg of garlic powder/kg dry ration for Piaractus mesopotamicus (Osteichthyes Characidae), weighting 73.6+/-39.4 9 and measuring 15.0+/-2.7 cm, fed for a period of 15, 30 and 45 days. Fifteen days after treatment with 1,000 and 2,000 Prig of garlic/kg dry ration, significant reduction of Anacanthorus penilabiatus (Monogenea: Dactylogyridae) in the gills was related. Nevertheless, the addition of garlic to the ration caused significant increase in the erythrocyte number and in the thrombocyte percentage in the circulating blood. However, a decrease in the lymphocyte percentage was also observed. After 45 days, fish fed with garlic showed significant increase in the erythrocyte number, leucocyte, haemoglobin rate, hematocrit and thrombocyte.

Performance and hematology of pacu fed diets supplemented with vitamins C and/or E

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

Controle biológico de Dolops carvalhoi (Crustacea: Branchiura) em juvenis de pacu (Piaractus mesopotamicus)

This work evaluated piaucu juveniles (Leporinus macrocephalus) efficiency on the control of Dolops carvalhoi in pacu (Piaractus mesopotamicus) under artificial infestation. 30 fish were equally distributed in six aquarium and acclimated for seven days. After this period the pacus were unnaturaly infested with 20 D. carvalhoi per fish to four days. on the fifth day, for aquaria were added with five uninfected piaucus each and the fish were checked eight times to evaluted the total number of parasites in fish body and aquarium wall. After 24 hours in the aquarium with piaucus the total number of Dolops was significant lower than only pacus suggesting that piaucu preyed the parasite. The parasite number was reduced 15 minutes after the addition of piaucus and after 24 hours, no parasites was found in pacu body and aquarium walls, suggesting that piaucu fingerling may be used to branchiurans infestations in other species of fish.

Estudo do potencial do pacu (Piaractus mesopotamicus) como agente de controle biológico de Egeria densa, E. najas e Ceratophyllum demersum

Visando fornecer subsídios para elaboração de sistema de manejo integrado das grandes massas de plantas daninhas aquáticas submersas em lagos e represas, o presente trabalho teve como objetivo verificar a eficiência do pacu (Piaractus mesopotamicus) como agente de controle biológico de Egeria densa, E. najas e Ceratophyllum demersum. As espécies de plantas daninhas foram oferecidas individualmente, duas a duas e as três espécies juntas. Verificou-se que este peixe tem uma eficiência média de controle dessas plantas daninhas variando entre 28 e 100%, podendo eliminar uma massa verde dessas plantas, com a mesma quantidade de seu peso, em sete dias. A eficiência de controle diária aumentou com o tempo de predação. O pacu é mais seletivo para E. densa ou E. najas quando na presença de C. demersum. Não ocorreu alteração na eficiência de controle do pacu sobre E. densa ou E. najas em todos os tratamentos e nos três períodos estudados (três, cinco e sete dias).

Dietary supplementation of lysine and/or methionine on performance, nitrogen retention and excretion in pacu Piaractus mesopotamicus reared in cages

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

Fontes e níveis de proteína bruta em dietas para juvenis de pacu (Piaractus mesopotamicus)

Este experimento foi conduzido, por um período de 100 dias, com o objetivo de estudar diferentes fontes e níveis de proteína bruta em dietas para juvenis de pacu. Foram utilizados 252 juvenis de pacu, distribuídos em 36 caixas de cimento amianto com volume de 150 litros, sendo estocados sete peixes em cada unidade. Durante o período experimental, a temperatura média da água permaneceu em 28ºC e os demais parâmetros limnológicos (oxigênio dissolvido, pH, alcalinidade e condutividade) apresentaram-se dentro dos níveis adequados para o desenvolvimento desta espécie. O delineamento experimental foi de blocos casualizados, no qual foram avaliados nove tratamentos em esquema fatorial 3 x 3, sendo três níveis de substituição da fonte protéica de origem animal (farinha de peixe), pela fonte de origem vegetal (farelo de soja), aos níveis de 0, 50 e 100% e três níveis de proteína bruta (18, 22 e 26%). Os resultados obtidos indicaram que o nível de 22% de proteína bruta foi mais adequado e a farinha de peixe pode ser substituída parcial ou totalmente pelo farelo de soja. A substituição da farinha de peixe por farelo de soja proporcionou os melhores coeficientes de digestibilidade, sem afetar ganho de peso, conversão alimentar, taxa de crescimento específico e taxa de eficiência protéica dos juvenis. Esta substituição também não afetou a composição corporal dos peixes, como a eficiência de retenção de nitrogênio, nitrogênio corporal, gordura corporal e nitrogênio e gordura no ganho de peso.

Desempenho produtivo, composição corporal e parâmetros fisiológicos de pacu alimentado com níveis crescentes de fibra

O objetivo deste trabalho foi avaliar os efeitos de teores de fibra bruta na dieta sobre o desempenho produtivo, composição centesimal da carcaça e parâmetros fisiológicos de juvenis de pacu. O experimento teve duração de 84 dias, e foram utilizados 360 juvenis de pacu, com peso médio de 23,97±0,59 g, distribuídos aleatóriamente em 30 tanques com 180 L de água, em delineamento inteiramente casualizado, com seis tratamentos (5, 7, 9, 11, 13 e 15% de fibra bruta) e cinco repetições. Dietas com altos teores de fibra (11, 13 e 15%) resultaram em piores taxas de ganho de peso, conversão alimentar e crescimento específico, além de menor eficiência proteica e consumo de ração. A composição da carcaça dos animais foi alterada pelo aumento do teor de fibra das dietas. Os teores de proteína e cinza tiveram aumento com o incremento nos teores de fibra. O metabolismo foi alterado com o emprego de teores crescentes de fibra, o que resultou em pequena elevação do colesterol plasmático. Teores de fibra bruta de até 9% não tiveram efeitos negativos no metabolismo; entretanto, teores acima de 11% reduziram o crescimento dos peixes.

Effects of incubation temperature on muscle morphology and growth in the pacu (Piaractus mesopotamicus)

This study describes the influence of incubation temperature during initial development phase on the morphology and muscle growth characteristics in the pacu (Piaractus mesopotamicus). Pacu eggs were incubated at 25, 27, and 29 degreesC until hatching. After day 5, fish from each temperature were transferred to 5001 tanks. At hatching and after 5, 25, and 60 days, muscle samples were collected, some were frozen in liquid nitrogen and others fixed in 4% paraformaldehyde or 2.5% glutaraldehyde. These samples were used for morphological, histochemical, immunohistochemical, and morphometric analysis. At hatching, we observed a superficial monolayer of small diameter fibers, lying just beneath the skin surrounding several round cells. From day 5, we observed two distinct populations of muscle fibers distributed in two layers: (1) red-in a superficial region with aerobic activity, and following acid preincubation, high mATPase activity, and 2) white-with anaerobic activity, and following alkaline preincubation, high mATPase activity. Twenty-five days after hatching, an intermediate layer and cell proliferating zones could be seen in the dorsal fin muscle region, with intermediate characteristics. Throughout the experimental period, there was an increase in muscle mass due to new fiber recruitment in the cell proliferating zones and between the more differentiated fibers in red, intermediate, and white muscles. This was more obvious from day 25, and at 29 degreesC than at 25 and 27 degreesC. Fiber hypertrophy occurred from hatching to 60 days and was more evident from 5 to 25 days. The number of proliferating nuclei (PCNA-labelling) increased from hatching to 60 days, and was more obvious in the 29 degreesC group at 60 days. Our results show that at incubation temperatures of 25, 27 and 29 degreesC, hypertrophy was predominantly from hatching to 25 days, after that muscle growth by hyperplastic mechanism increased. The interaction of muscle hypertrophic and hyperplastic growth processes in the 29 degreesC group produced the largest fish at the end of the experiment. (C) 2004 Elsevier B.V. All rights reserved.

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.

Differential MMP-2 and MMP-9 Activity and Collagen Distribution in Skeletal Muscle from pacu (Piaractus mesopotamicus) During Juvenile and Adult Growth Phases

Here, we evaluated collagen distribution and matrix metalloproteinases (MMPs) MMP-2 and MMP-9 activities in skeletal muscle of pacu (Piaractus mesopotamicus) during juvenile and adult growth phases. Muscle samples from juvenile and adult fishes were processed by histochemistry for collagen system fibers and for gelatin-zymography for MMP-2 and MMP-9 activities analysis. Picrosirius staining revealed a myosept, endomysium, and perimysium-like structures in both growth phases and muscle types, with increased areas of collagen fibers in adults, mainly in red muscle. Reticulin staining showed that reticular fibers in the endomysium-like structure were thinner and discontinuous in the red muscle fibers. The zymography revealed clear bands of the pro-MMP-9, active-MMP-9, intermediate-MMP-2, and active-MMP-2 forms in red and white muscle in both growth phases. MMP-2 activity was more intense in juvenile than adult muscle fibers. Comparing the red and white muscle types, MMP-2 activity was significantly higher in red muscle in adult phase only. The activity of MMP-9 forms was similar in juvenile red and white muscles and in the adult red muscle, without any activity in adult white muscle. In conclusion, our results show that, in pacu, the higher activities of MMP-2 and -9 are associated with the rapid muscle growth in juvenile age and in adult fish, these activities are related with a different red and white muscle physiology. This study may contribute to the understanding muscle growth mechanisms and may also contribute to analyse red and the white muscle parameters of firmness and softness, respectively, of the commercial product. Anat Rec, 292:387-395, 2009. (C) 2009 Wiley-Liss, Inc.

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)

Quantitative expression of myogenic regulatory factors MyoD and myogenin in pacu (Piaractus mesopotamicus) skeletal muscle during growth

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

Localization of 5-methylcytosine in metaphase chromosomes of diploid and triploid pacu fish, Piaractus mesopotamicus (Pisces, Characiformes)

The distribution of 5-methylcytosine (5-MeC) was investigated in fish chromosomes by indirect immunofluorescence using a highly specific 5-MeC monoclonal antibody. Diploid and artificially produced triploid specimens of the pacu fish, Piaractus mesopotamicus, were analyzed. The strong immunofluorescent signals were coincident with the heterochromatic regions of both diploids and triploids in a pattern that matched the C-banding pattern. In the euchromatin, heterogeneous labeling was observed along the chromatids. The weakness of this labeling hindered comparison of the fluorescence labeling of homologous chromosomes from diploid and triploid individuals. However, no striking differences were observed. The possibility that the euchromatin labeling by the 5-MeC antibody is related to the occurrence of mildly repetitive sequences in the genome of Piaractus is discussed.