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)

Spermatogonia and spermatocyte ultrastructure in Hoplias malabaricus (Teleostei, Characiformes : Erythrinidae)

The Hoplias malabaricus primary spermatogonium shows a large nucleus, central nucleolus, and low electron-dense cytoplasm containing nuages. In cysts, they undergo several mitotic divisions with incomplete cytokinesis, giving rise to secondary spermatogonia. These are smaller than the primary spermatogonia and their nuclei have one or two eccentric nucleoli. Spermatocytes I can be identified by the presence of synaptonemal complexes. Spermatocytes II are smaller than spermatocytes 1, displaying roughly compacted chromatin. All these cell types remain interconnected by thick-walled intercellular bridges, which have membranous reinforcements during mitosis and meiosis. These cell types show a well-developed endomembranous system, one of the centrioles anchored to the plasma membrane and small nuages. Their mitochondria are large and circular, with few cristae. In the last generations of spermatogonia, the mitochondria are smaller, elongate and have more cristae. In the spermatocytes, the mitochondria are small and round. Similarities found in relation to germ cells of other teleosts are discussed.

Genomic organization of repetitive DNAs in the cichlid fish Astronotus ocellatus

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

The 5S rDNA family evolves through concerted and birth-and-death evolution in fish genomes: an example from freshwater stingrays

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

Crystallographic studies of fish hemoglobins

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

Stomach contents and notes on the reproduction of the Onefin Skate Gurgesiella dorsalifera (Chondrichthyes: Rajidae) off Southern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrolocation-communication discharges of the fish Gymnotus carapo L. (Gymnotidae: Gymnotiformes) during behavioral sleep

Technical problems have hampered the study of sleep in teleosts. The electrical discharges of Gymnotus carapo L. (Gymnotidae: Gymnotiformes) were monitored to evaluate their ease and reliability as parameters to study sleep. The discharges were detected by electrodes immersed in a glass aquarium and were recorded on a conventional polygraph. G. carapo showed conspicuous signs of behavioral sleep. During these periods, opercular beat rates were counted, electric discharges recorded, and the sharp discharge increase (SDI) of the orienting reflex was investigated. All 20 animals monitored maintained electrical discharges during behavioral sleep. The discharge frequencies during sleep (50.3 ± 10.4 Hz) were not significantly different from those observed when the fish was awake and inactive (57.2 ± 12.1 Hz) (Wilcoxon matched-pairs signed-ranks test, P>0.05). However, the SDI, which was prevalent in the awake fish, was not observed during periods of behavioral sleep. Additional observations showed that the species had cannibalistic habits. When presented with electrical discharges from a conspecific, the sleeping fish showed an initial decrease or pause in discharge frequency, while the awake fish did not have this response. We conclude that the electrical discharges of G. carapo were not conspicuous indicators of behavioral sleep. Discharges may have been maintained during sleep for sensory purposes, i.e., conspecific detection and avoidance of cannibalistic attacks.

Características hematológicas do tambaqui Colossoma macropomum Cuvier (Osteichthyes, Characidae) em sistema de monocultivo intensivo: II. Leucócitos

The leukocytes parameters in approximately one-year-old freshwater fish Colossoma macropomum Cuvier, 1818 (tambaqui) kept in an intensive monobreeding system as well as the correlation among these parameters and the biometric data (total weight and standard length) were investigated. The mean value of the white blood cell count (WBC) in the peripheral blood of tambaqui was 2663.3±1288µl and in the differential count, the following means were observed: neutrophils (1566.2±754µl); lymphocytes (973.6±447µl); monocytes (86.7±123µl) and special granulocitic cells (7.8±144µl). The blood parameters studied were positively correlated among one another, but were negatively correlated with the standard length. However, no correlation was with the weigth of the animals was shown. The leukocytes in Colossoma macropomum kept in an intensive monobreeding system were morphologically similar to those of other Brazilian teleosts described in literature.

Células sangüíneas, eletrólitos séricos, relação hepato e esplenossomáca de carpa-comum, Cyprinus carpio (Cyprinidae) na primeira maturação gonadal

This research studied the condition (Kn) relative factor, the hepatosomatic (HSR), the splenosomatic (SSR) relation, the erythrocytes, thrombocytes and leukocytes number, the glicogen locality by PAS method in thrombocytes and leucocytes and the total protein and electrolytes serices levels in both Cyprinus carpio L. sex. The female Kn showed higher value than the males. The female HSR average values were lower than the ones observed in males, while the leukocytes, lymphocytes and neutrophils percentage number were the highest. However, the males magnesium and choride serices levels were higher than the females. The HRS average values, hematocrit, haemoglobin concentration, average corspucular volume (ACV), average corpuscular haemoglobin concentration (ACHC), erythocytes number, trombocytes, monocytes, oesinophils, positive PAS leukocyte granular (PAS-LG), and total protein, sodium, potassium and calcium serices levels did not show significant statistics difference (p> 0.05) between males and females. The PAS method showed glicogen granules into the thronbocytes, eosinophils and neutrophils cytoplasm. Nevertheless, in the PAS-LG cytoplasm, neutral glicoprotein granules were also observed. Monocytes and lynfocytes showed negative reaction to PAS. In the teleosts, the gonodas matureness presents higher relation with the factor of condition. During the reprodution period it is unlikely to find the sexual effects isolated in the hemogram, because most of the time that is not the only factor to cause dimorphism.

Morphological, cytochemical, and ultrastructural study of thrombocytes and leukocytes in neotropical fish, Brycon orbignyanus Valenciennes, 1850 (Characidae, Bryconinae)

Morphological, cytochemical and ultrastructural studies are important to demonstrate the function of the blood cells, which is very little understood in teleosts. In peripheral blood of piracanjuba' Brycon orbignyanus, thrombocytes, lymphocytes, monocytes, neutrophils and heterophils were studied and characterized. Thrombocytes had a fusiform or oval shape with PAS-positive granules. Lymphocytes presented small size with sparse basophilic cytoplasm. Monocytes were large in size, presented basophilic cytoplasm that may be foamy or vacuolated, with non-specific esterase staining. The neutrophils presented lightly neutrophilic granule cytoplasm, with positivity for PAS and peroxidase. The heterophils were large in size, with eosinophilic and basophilic granules cytoplasm and PAS-positive. Transmission electron microscopy study demonstrated that the thrombocytes, lymphocytes and monocytes features were similar to other teleosts. In ultrastructural study only one type of neutrophils was observed. Cytochemical findings indicated that neutrophils and monocytes of B. orbignyanus may be involved in phagocytosis, and neutrophils play an important microbicidal role.

Hemoparasite and hematological parameters in Nile tilapia

The accelerated growth of finfish aquaculture has resulted in a series of health problems, including blood disorders by hemoparasites; there are scarce studies about these agents and their impact in actual intensive farming. The aim of this study was to identify and quantify the hemoparasites present in monocytes and erythrocytes in the blood of tilapia and their correlation with the hematological profile. Blood samples were collected from caudal vessels of 15 cage-reared Nile tilapia (Oreochromis niloticus), with 70 ± 10 g weight on average, from Itambaracá Municipality, Parana State, Brazil. The total red blood cells, mean corpuscular volume, hematocrit, total and differential white blood cells counts, and the number of thrombocytes were determined in blood smears stained with May-Grünwald-Giemsa-Wright and Quick Panoptic. The results showed the presence of pleomorphic cytoplasmic inclusions with corrugated appearance and basophilic staining, mainly in monocytes, suggesting Anaplasmataceae parasitemia and inclusions with the same morphological characteristics in erythrocytes of one Nile tilapia. The hematological analysis showed no significant difference (P < 0.05) between infected and not infected fish, and therefore, there was no correlation between parasitemia and hematological profile. These observations allow us to infer that the intracytoplasmic inclusions in monocytes and erythrocytes are compatible with the family Anaplasmataceae. There was no correlation between the blood profile and low level of parasitemia. © 2012 Springer-Verlag London.

The discovery of Foxl2 paralogs in chondrichthyan, coelacanth and tetrapod genomes reveals an ancient duplication in vertebrates

The Foxl2 (forkhead box L2) gene is an important member of the forkhead domain family, primarily responsible for the development of ovaries during female sex differentiation. The evolutionary studies conducted previously considered the presence of paralog Foxl2 copies only in teleosts. However, to search for possible paralog copies in other groups of vertebrates and ensure that all predicted copies were homolog to the Foxl2 gene, a broad evolutionary analysis was performed, based on the forkhead domain family. A total of 2464 sequences for the forkhead domain were recovered, and subsequently, 64 representative sequences for Foxl2 were used in the evolutionary analysis of this gene. The most important contribution of this study was the discovery of a new subgroup of Foxl2 copies (ortholog to Foxl2B) present in the chondrichthyan Callorhinchus milii, in the coelacanth Latimeria chalumnae, in the avian Taeniopygia guttata and in the marsupial Monodelphis domestica. This new scenario indicates a gene duplication event in an ancestor of gnathostomes. Furthermore, based on the analysis of the syntenic regions of both Foxl2 copies, the duplication event was not exclusive to Foxl2. Moreover, the duplicated copy distribution was shown to be complex across vertebrates, especially in tetrapods, and the results strongly support a loss of this copy in eutherian species. Finally, the scenario observed in this study suggests an update for Foxl2 gene nomenclature, extending the actual suggested teleost naming of Foxl2A and Foxl2B to all vertebrate sequences and contributing to the establishment of a new evolutionary context for the Foxl2 gene. © 2013 Macmillan Publishers Limited All rights reserved.

Morfologia testicular e estrutura da espermatogênese em peixes ornamentais Tetra Negro, Gymnocorymbus ternetzi; Tetra Amarelo, Hyphessobrycon bifasciatus e Mato Grosso, Hyphessobrycon eques (Teleostei, Characiformes)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Sciaenidae fish of the Caeté River estuary, Northern Brazil: mitochondrial DNA suggests explosive radiation for the Western Atlantic assemblage

Sciaenids are fish which are normally abundant in tropical estuaries of the western Atlantic. Studies on the Caeté river estuary in the northern Brazilian state of Pará have revealed that in this area Sciaenidae is the dominant family, comprising almost 50% of all teleosts sampled. In this paper we present the results of the first phylogenetic study on South American estuarine sciaenids, during which we obtained mitochondrial gene 16S sequences from 15 species belonging to eight genera occurring in the Caeté estuary. Intergeneric nucleotide divergences varied from 5 to 15%, Lonchurus and Menticirrhus being the most divergent lineages. Nucleotide divergences were quite variable amongst species of the same genus, ranging from 1.2% (Stellifer microps x Stellifer naso) to 8.4% (Menticirrhus americanus x Menticirrhus littoralis). Cladograms based on maximum parsimony, minimum evolution and maximum likelihood depicted an explosive diversification pattern for the western Atlantic sciaenid assemblage. Our analysis further reveals a very close relationship between Bairdiella and Stellifer, a monophyletic clade which emerged during the more recent diversification events of the Sciaenidae family. The phylogenetic reconstruction suggests the need for a revision of the taxonomy and nomenclature of the Bairdiella/Stellifer group.

A ictiologia na Amazônia brasileira de Diogo Nunes (1538) a Landi (1772): a visão dos viajantes e naturalistas que trataram de sua ictiofauna durante este período

Este trabalho visou reunir e disponibilizar informações sobre a ictiofauna da Amazônia segundo vários escritos do século XVI ao XVII. Consultaram-se, fontes documentais de várias bibliotecas e arquivos, e dos documentos selecionados procedeu-se à identificação taxonômica das espécies neles referidas. Também se fizeram observações com base nas referências textuais e iconográficas disponíveis, de forma a acrescentar informações consideradas de relevância zoológica. Constatou-se que, devido à definição então vigente do conceito de "peixe", um estudo da ictiologia do período precisaria incluir também informações sobre espécies de outros táxons aquáticos que não agnatos, elasmobrânquios e teleósteos. No início do período colonial, a idéia de peixe era generalizada simplesmente como pescado, e não havia muita preocupação em inventariar a ictiofauna do Novo Mundo. Mais tarde, alguns dos visitantes da região puseram-se a descrever e ilustrar a ictiofauna de maneira mais específica: nessa fase em que se dava mais detalhamento às espécies de peixes destacavam-se o texto atribuído ao Fr. Cristóvão de Lisboa (1625- 1631), o códice do arquiteto Antonio Giuseppe Landi (1772) e principalmente o manuscrito do Pe. João Daniel (1758-1776) — o qual se revelou um pioneiro do movimento conservacionista da Amazônia. Os visitantes que vieram à região careciam, no geral, de formação acadêmica específica e, servindo a funções várias alheias à Ciência, não seguiam uma metodologia que se pudesse chamar de científica. Devido ao fato de seus manuscritos não terem sido divulgados ou sequer impressos, por vários motivos, o conhecimento neles produzido não foi cumulativo ou analítico, e não teve influência significativa no desenvolvimento da Ictiologia. Por outro lado, os naturalistas que efetivamente não estiveram na Amazônia puderam trazer uma contribuição de maior impacto, consolidando o conhecimento obtido através principalmente da obra de Georg Marcgrave (1648) e de exemplares coletados nas possessões holandesas da América do Sul, e incluindo-o num grande sistema classificatório que mais tarde despertaria o interesse de outros cientistas em conhecer a ictiofauna amazônica.