ABSTRACT
A indoleamina 2,3-dioxigenase (IDO) é uma enzima que cataboliza o aminoácido triptofano, levando à inibição da proliferação de linfócitos T, seja pela exaustão desse aminoácido no ambiente, ou pela indução via catabólitos induzindo-os a apoptose. Em mamíferos, esta enzima atua em diversas condições do organismo como a gestação, infecções, inflamações crônicas, transplantes e tumores, atuando na regulação imunológica. Estudos recentes identificaram a presença de moléculas homólogas a IDO em espécies filogeneticamente inferiores, cuja função parece estar restrita ao metabolismo do triptofano como fonte de energia. Este estudo teve por objetivo averiguar a expressão da IDO em células sanguíneas e órgãos hematopoiéticos de truta arco-íris pela imuno-histoquímica, buscando evidências de que a mesma poderia, nesta espécie, estar relacionada ao sistema imune. A expressão de IDO foi observada nos órgãos hematopoiéticos estudados incluindo o rim cefálico que apresentou marcação em células interrenais e leucócitos; baço, na qual a marcação restringiu à alguns leucócitos; no fígado a marcação ficou limitada à apenas algumas células dentro dos vasos sanguíneos e nas extensões sanguíneas pode-se visualizar a marcação de alguns leucócitos como os monócitos, linfócitos e neutrófilos. A predominância da marcação da IDO nesses tecidos pode constituir uma evidência de que a IDO identificada na O. mykiss esteja relacionada ao sistema imunológico nessa espécie...
Indoleamine 2,3-dioxygenase (IDO) is an enzyme that catabolizes the amino acid tryptophan, leading to inhibition of T lymphocyte proliferation, whether by depletion of this amino acid in the environment, or by induction via the catabolites inducing apoptosis. In mammals, this enzyme acts on various conditions of the body such as pregnancy, infections, chronic inflammation, transplantation and tumors, acting in immune regulation. Recent studies have identified the presence of homologous molecules IDO lower phylogenetically related species, whose function appears to be confined to the tryptophan metabolism as an energy source. This study aimed to investigate the expression of IDO in blood cells and hematopoietic organs of rainbow trout by immunohistochemistry, seeking evidence that it could, this species is related to the immune system. The expression of IDO was observed in hematopoietic organs studied including head kidney that show labeling in interrenal cells and leukocytes; spleen, in which the marking restricted to a few leukocytes in the liver;, labeling was restricted to only certain cells within the blood vessels and the blood extensions can view the marking of some leukocytes including monocytes, lymphocytes and neutrophils. The predominance of IDO marking these tissues may constitute evidence that IDO identified in O. mykiss is related to the immune system in this species...
Subject(s)
Animals , Female , /analysis , /blood , Oncorhynchus mykiss/physiology , Interrenal Gland/chemistry , Hematinics/chemistry , Immunohistochemistry/veterinary , Leukocytes/chemistry , Blotting, Western/veterinaryABSTRACT
Benthic macroinvertebrates constitute the link between organic matter input in streams and fishes. However, the possibility of influence of predators on the invertebrates is still a controversial issue. The possibility of alteration of the benthic community by the modification in predation in a stream in the South of Brazil was studied by means of an exclusion experiment under semi-natural conditions. The exclusion showed an increase in the abundance of Plecoptera in the river where the rainbow trout was introduced, the larvae of Trichoptera also increased in abundance in the units of fish exclusion. This difference does not confirm the pressure applied by the trout on the benthic macro fauna due to differences in ichthyofauna and in the habitat of both rivers. Nevertheless, it points to the need for the development of studies concerning the trophic relations and the possible effects of this introduction in the aquatic biota.
Os macroinvertebrados bentônicos exercem a ligação entre a entrada de matéria orgânica nos rios e os peixes. Porém, a possibilidade de influência dos predadores sobre os invertebrados é uma questão ainda controversa. A possibilidade de alteração da comunidade bentônica, pela modificação na predação em um rio no sul do Brasil, foi estudada através de um experimento de exclusão em condições seminaturais. A exclusão resultou no aumento na abundância de Plecoptera no rio onde é feita a introdução de truta arco-íris; as larvas de Trichoptera também aumentaram em abundância nas unidades onde se efetuou a exclusão. Essa diferença não pode ser atribuída à presença das trutas, devido às diferenças na ictiofauna e de habitat dos dois rios. Entretanto mostra a necessidade de desenvolvimento de estudos acerca das relações tróficas e possíveis efeitos desta introdução sobre a biota aquática
Subject(s)
Animals , Ecosystem , Fishes/physiology , Invertebrates/physiology , Predatory Behavior/physiology , Brazil , Oncorhynchus mykiss/physiology , Population Dynamics , RiversABSTRACT
Electro-olfactogram recording was used to determine whether the olfactory epithelium of adult rainbow trout is specifically sensitive to bile acids, some of which have been hypothesized to function as pheromones. Of 38 bile acids that had been pre-screened for olfactory activity, 6 were selected. The rainbow trout-specific bile acids, taurocholic acid (TCA), and taurolithocholic acid 3-sulfate (TLS) were the most potent compounds tested. TLS had a distinctive dose-response curve. Cross-adaptation experiments demonstrated that sensitivity to bile acids is attributable to at least 3 independent classes of olfactory receptor sites. Our data suggest that bile acids are discriminated by olfaction in rainbow trout, supporting the possibility that these compounds function as pheromones.
Subject(s)
Animals , Bile Acids and Salts , Olfactory Mucosa/physiology , Oncorhynchus mykiss/physiology , Pheromones , Smell/physiology , Adaptation, Physiological/physiology , ElectrophysiologyABSTRACT
Monthly stomach context samples of rainbow trout from Mucunután stream (Mérida, Venezuela), were collected from, March 1987 to February 1988 (n = 306). The major dietary components were Ephemeroptera, Trichoptera and Diptera. Baetodes sp. was the most important food item based on numerical composition (43 per cent) and frequency of occurrence (88 per cent). When the gravimetric method was used Leptonema sp. was the major dietary component. The diet was not a function of sex. The consumed fauna was more similar to the drift invertebrate fauna than to that of benthos (p < 0.01). The fluctuations on the stomach content paralleled changes of food availability in the environment
Subject(s)
Animals , Male , Female , Feeding Behavior , Oncorhynchus mykiss/physiology , Diet , Fresh Water , Sex Factors , Time Factors , VenezuelaABSTRACT
From January 1987 to February 1988, a total of 393 rainbow trout were captured in a high mountain stream of the Venezuelan Andes (8 degrees 40'N; 71 degrees 5'W). Gonadal development was measured using the Nikolsky method. The mean size for sexual maturation was analyzed with the method of relative frequency of adults and young for each size class. Males reproduced throughout the year, while ripe females were observed only in January (11 per cent). A half of the males was sexually mature at the minimum size of 13.40 cm SL (16.25 for females). All individuals were sexually mature at 26.40 cm (males) and 26.80 cm (females)