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.

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.

Morphological, histological, and ultrastructural characterization of degenerating salivary glands in females of the cattle-tick Rhipicephalus (Boophilus) microplus (CANESTRINI, 1887) (Acari : Ixodidae)

The present study describes the morphology and ultrastructure of the salivary glands of semi-engorged females of the southern cattle-tick Rhipicephalus (Boophilus) microplus. The acini that compose these glands, at that specific feeding stage, show cells featuring degenerative process of the salivary glands, such as: vacuolated cytoplasm, condensed chromatin, fragmented nuclei, and presence of apoptotic bodies. In addition, the presence of microorganisms was detected, with morphology typical of protozoa, inside these organs. (c) 2005 Elsevier Ltd. All rights reserved.

Structural and cytochemical changes in the salivary glands of the Rhipicephalus (Boophilus) microplus (CANESTRINI, 1887) (Acari : Ixodidae) tick female during feeding

This study describes the morphology of salivary glands of Rhipicephalus (Boophilus) microplus female ticks at beginning of feeding (24-48 h of attachment) and semi-engorged (4-5 days of attachment) to verify the degenerative characteristics of these organs and the secretory phase in which the process begins. At the beginning of feeding, secretion granules had been observed only in the cytoplasm of cells b, c(1), c(2), c(4) (type II acinus) and d (type III acinus), as well as large nuclei with regular and preserved morphology. In the semi-engorged females the acini presented few normal cells, few partially preserved ones, and the remaining ones in several stages of degeneration, that is, with retraction and cytoplasmic vacuolization, and nuclei with chromatin in several stages of condensation, picnotic and/or in fragmentation. In type I acinus and in the excretory ducts of the studied glands, at both feeding stages, no degenerative characteristic was observed. In females of R. (B.) microplus, the salivary glands degenerate asynchronically and precociously when compared with those of others tick's species. (c) 2006 Elsevier B.V. All rights reserved.

Morphological, histological, and ultrastructural studies of the ovary of the cattle-tick Boophilus microplus (Canestrini, 1887) (Acari : Ixodidae)

This study presents the morphology of the ovary, as well as the dynamics of the vitellogenesis process in oocytes of the cattle-tick Boophilus microplus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a lumen delimitated by a wall of small epithelial cells with rounded nuclei. In this tick species, the oocytes were classified into six stages varying from I to VI and according to: cytoplasm appearance and presence of the germ vesicle, yolk granules, and chorion. Oocytes of various sizes and at different developmental stages remain attached to the ovary through a cellular pedicel until completing stage V. Afterwards, they are liberated into the lumen and from there to the exterior. Some oocytes (classified as type VI) showed an atypical appearance indicating that some of the cellular components would be undergoing a degenerative process and/or reabsorption. (c) 2004 Elsevier B.V. All rights reserved.

Occurrence and ultrastructural characterization of nuage during oogenesis and early spermatogenesis of Piaractus mesopotamicus Holmberg, 1887 (Teleostei)

Foi investigada a ocorrência e caracterizada ultra-estruturalmente a eliminação de material nuclear eletrondenso (nuage) para o citoplasma durante a ovogênese e durante os estágios iniciais da espermatogênese de Piaractus mesopotamicus, um peixe do Pantanal Matogrossense de ciclo reprodutivo sazonal. Constataram-se nas células germinativas femininas dois momentos de eliminação desse material, na ovogônia e no ovócito em fase perinucleolar. Nas células masculinas, material com morfologia e comportamento muito semelhante foi encontrado na espermatogônia. em todos os casos, o material associou-se a mitocôndrias. A possível função desse material foi discutida.

Morphological changes of Sertoli cells during the male reproductive cycle of the teleost Piaractus mesopotamicus (Holmberg, 1887)

Realizou-se uma investigação das mudanças histológicas e ultra-estruturais das células de Sertoli durante o ciclo reprodutivo de machos de Piaractus mesopotamicus. Os resultados mostraram que o desenvolvimento das células de Sertoli está estritamente relacionado à maturação das células gaméticas. Portanto, as células de Sertoli têm algum papel na maturação das células germinativas durante o ciclo reprodutivo dessa espécie, talvez formando um tecido de sustentação para os cistos espermatogênicos em desenvolvimento, ajudando a reorganização testicular para um novo ciclo reprodutivo, além de outras possíveis funções discutidas no texto.

Amphibia, Anura, Hylidae, Dendropsophus melanargyreus (Cope, 1887): distribution extension, new state record and geographic distribution map.

We present the first record of Dendropsophus melanargyreus for the state of São Paulo and a distribution map for this species. This new record represents the southeastern limit of distribution, which is 106 Km from the nearest locality previously recorded for this species and is the fourth new register of anuran to northwestern region of São Paulo in the last two years, increasing species list of the region from 33 to 36 species. This results evidence the importance of this region as priority area for inventory.

Hook selectivity of the pacu Piaractus mesopotamicus (Holmberg, 1887) in the Pantanal, the state of Mato Grosso do Sul, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Yield per recruit of the pacu Piaractus mesopotamicus (Holmberg, 1887) in the pantanal of Mato Grosso do Sul, Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ecology of the parasitic endohelminth community of Piaractus mesopotamicus (Holmberg, 1887) (Characiformes) from Aquidauana and Miranda Rivers, Pantanal, state of Mato Grosso do Sul, Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

EFFECT OF ASCORBIC-ACID DEFICIENCY ON THE GROWTH, GILL FILAMENT LESIONS AND BEHAVIOR OF PACU FRY (PIARACTUS-MESOPOTAMICUS HOLMBERG, 1887)

The effect of ascorbic acid deficiency was determined in Piaractus mesopotamicus Holmberg, 1887, fish (pacu) under laboratory conditions. A total of 120 fish with an average body weight of 8.64 +/- 1.62 g and measuring 6.15 +/- 0.33 cm in length at the beginning of the experiment were fed diets containing 0, 50, 100 or 200 mg palmitate-coated ascorbic acid/kg dry ration for a period of 24 weeks with measurements every 4 weeks. The experiment was conducted in 20 fiber-cement aquaria of 81-liter capacity. Each aquarium was supplied with dechlorinated water at a flow rate of 1 l/min. Water temperature was measured daily and pH, dissolved oxygen, alkalinity and water conductivity were determined weekly. A fully randomized experimental design was utilized, with 5 replicates of each treatment and 6 fish per aquarium. Ascorbic acid-supplemented fish presented significantly increased growth when compared to unsupplemented fish. Furthermore, unsupplemented fish presented a higher incidence of hyperplasia, hypertrophy and dysplasia of the bone cartilage of gill filaments. The gill lamellae of unsupplemented fish had twisted cartilage and an inflammatory infiltrate at the ends. Anorexia and increased handling stress were also observed in fish fed the unsupplemented diet. The present study suggests that 50 mg ascorbic acid/kg dry ration is sufficient to improve development of pacu fingerlings but the optimum level under aquarium conditions, determined by regression analysis, is 139 mg ascorbic acid/kg dry ration.