RESUMEN
This study evaluated the hematological characteristics and erythrocyte morphometry in Auchenipterus nuchalis, Psectrogaster amazonica and Squaliforma emarginata captured in Tocantins river. The samples were taken in the Tocantins river, where blood was collected by puncturing the caudal vein of the animals. The complete hemogram and morphometry of the erythrocytes were determined. Auchenipterus nuchalis (n = 15) showed the largest number of erythrocytes, hemoglobin and hematocrit, followed by P. amazonica (n = 26) and S. emarginata (n = 26). Squaliforma emarginata showed the largest erythrocytes and the smallest number of circulating cells. Squaliforma emarginata also showed the highest number of circulating blast cells (orthochromatic and polychromatophil erythrocytes) in the peripheral blood. These differences can be attributed to respiratory adaptations of a behavioral or physiological nature related to the environment. The highest percentage of lymphocytes was observed in P. amazonica, and of monocytes and neutrophils in A. nuchalis. The variation among the species in the percentages of leucocytes can also be attributed to the niche occupied, favored by exposure to different microorganisms.
Neste estudo, foram avaliadas as características hematológicas e a morfometria de Auchenipterus nuchalis, Psectrogaster amazônica e Squaliforma emarginata, capturados no rio Tocantins. As amostragens foram realizadas no rio Tocantins, onde o sangue foi coletado por punção caudal dos animais, determinando-se hemograma completo e morfometria dos eritrócitos. Auchenipterus nuchalis (n = 15) apresentou maior número de eritrócitos, hemoglobina e hematócrito, seguido de P. amazônica (n = 26) e S. emarginata (n = 26). O tamanho dos eritrócitos foi maior para S. emarginata, mostrando que quanto maior o tamanho dos eritrócitos, menor o número de células circulantes. Squaliforma emarginata também apresentou maior número de blastos (eritrócitos ortocromáticos e policromatófilos) no sangue periférico. Estas diferenças podem ser atribuídas a adaptações respiratórias de natureza comportamental e/ou fisiológicas, relacionadas ao meio ambiente. O maior percentual de linfócitos foi observado em P. amazônica; o de monócitos e neutrófilos, na espécie A. nuchalis. A variação nos percentuais de leucócitos entre as espécies pode estar relacionada ao nicho ocupado, favorecido pela exposição a diferentes microrganismos.
RESUMEN
To evaluate circadian changes in thyroid hormones of piau, Leporinus obtusidens Valenciennes, 1847, (Osteichthyes, Anostomidae) after feeding were determined the plasma levels of thyroid hormones (TH) of 128 fishes, same age, immature, both sexes, distributed into four classes of weight. They were kept in 16 aquaria (100 L), with artificial aeration and 2 L min. -1 water flow, from March to August, 1996, in Aquaculture Station of the Universidade Federal de Lavras (UFLA). Daily, feed was supplied at 5% body weight. For blood samples, the fishes were anesthetized with benzocaine 10%, and plasmatic levels of TH were determined at 1, 4, 7, 10, 13, 16 and 22h after food supply during 4 consecutive days in June and in August, period of lowest temperature. The classes of weight 63, 75, 82 and 91 g were considered homogeneous, showing that plasmatic concentrations of T3 and T4 were body weight independent for this fish species. The daily cycle of plasma TH were correlated with feed intake, reaching the highest levels 7 h after feeding supply (T3 = 1.75 ± 0.07 ng mL-1 and T4 = 14.9 ± 1.59 ng mL-1). It was also possible to verify that the daily intake is directly correlated with water temperature which is affected by day-light cycle