Características hematológicas, bioquímicas e biométricas de Piaractus mesopotamicus Holmberg, 1887 (Osteichthyes: Characidae) oriundos de cultivo intensivo

Hematological characteristics are important tools for diagnosis and prognostic features in fish population and they contribute to the comprehension of comparative physiology, phylogenetic relation, food habit and other ecological parameters. Red blood cell count (RBC), white blood cell count (WBC), thrombocytes counts, glucose, cortisol, hepatosomatic and splenosomatic relation were evaluated in Piaractus mesopotamicus. The values of hepatosomatic relation varied from 0.67% to 2.79% and splenosomatic relation from 0.011% to 0.108%. RBC 1.870 to 4.590 × 106/μL, hemoglobin concentration 5.7 to 12.1g/dL, haematocrit 24.0% to 40.0%, mean corpuscular volume 98.0 to 174.0 fL, mean corpuscular haemoglobin concentration 19.1 to 34.2g/dL, glucose 40.6 to 89.2mg/dL and cortisol 4.73 to 110.5ng/dL The number of total thrombocytes was 12,160.0 to 89,280.0/μL and WBC 2,019.0 to 47,473.0/μL. Differential count of leucocytes showed 54.1% limphocytes, 10.9% neutrophils, 10.3% monocytes, 9.9% PAS-positive granular leukocytes (PAS-GL), 6.7% eosinophils, 0.3% basophils and 7.8% immature leucocytes. Variation of these haematological characteristics in the same fish species was observed, being considered as the normal variation in the fish concerned. Hence it is incorrect to assume that biological characteristics in fishes are distributed normally.

Alien fishes in lakes of the Doce river basin (Brazil): Range, new occurrences and conservation of native communities

The present study shows the distribution of alien fish species in tropical lakes in the middle Doce river basin, southeastern Brazil, obtained from a rapid assessment program. The causes for their introductions were sport-fishing improvement in some specific lakes and aquaculture in the studied basin. Presently, these species have a wide distribution occurring in 41 of the 54 lakes studied, representing an actual threat to regional native fish community. The natural connection among lakes and streams during the rainy season and the dispersal mediated by local people are the main invasion agents for alien fishes. The success of these invaders is probably due to absence of pre-existing effective competitors or top-predators in the invaded communities. We consider that the eradication of alien fishes by means of the available management tools may be very difficult due to the large number of lakes invaded and to the wide spectrum of lake conditions and resources exploited by these alien species. We recommend the use of environmental education as a tool to stop the human-mediated dispersion of aliens and to improve conservation of native fish community in lakes where these alien species are not present yet. © 2004 Instituto de Ciências Biológicas - UFMG.

Genetic conservation of Brazilian fishes - Present state and perspectives

Natural environments have been worldwide affected by the growing impact of anthropogenic actions that promote the reduction or the extinction of several vertebrate species. Aquatic ecosystems represent one of the most affected environments and many fish species and/or populations have been increasingly fragmented distributed due to habitat degradation, predatory fishing, introduction of exotic species, river sedimentation, deforestation, pollution, reduction of food resource, and construction of hydroelectric dams. Actually, more than 150 Brazilian fish species, including freshwater, estuary and coastal species, can be considered threatened. Information on the diversity, conservation biology and population analysis on threatened species or populations, with several DNA markers, can be extremely useful for the success of fish species-recovery and maintenance programs. Although DNA analysis in Neotropical fish species are just beginning, they tend to increase with the widespread attention to the use of molecular approaches to minimize problems related to the risk of extinction. The accumulation of information on biology and pattern of genetic variation of fish species, associated with ecological and demographic data, and also education and respect to the nature, constitutes a crucial task to develop efficient conservation strategies in order to preserve the genetic diversity in aquatic environments.

The condition factor of fishes from two river basins in São Paulo state, Southeast of Brazil

This work describes the relative condition factor of the Hypostomus strigaticeps, Astyanax altiparanae, Astyanax scabripinnis, Astyanax fasciatus, Astyanax sp1., Characidium aff. zebra, Piabina argentea, Hypostomus ancistroides, Hypostomus sp1., Parodon tortuosus, Serrapinus heterodon, and Bryconamericus sp., of the APA of São Pedro and Analândia (22°-23°S and 47°30'-48°30'W). The condition factor provides information about the physical state of the animal in the environment. In order to compare different species, the relative condition factor was used. Variations in this factor were correlated with variations through the year and with subsequent alterations in the physiological state of the fishes. The relative condition factor was shown to be efficient in indicating changes in fish condition throughout the year.

Spatial distribution of characidiin fishes (Teleostei, Crenuchidae) in the Ribeirão Grande system, a tributary of Paraíba do Sul river basin, Brazil

This study analyses the spatial distribution of characidiin fishes Characidium lauroi and Characidium alipioi (Crenuchidae) in a forest stream system located in southeastern Brazil. Fish were sampled from Jury 2001 to April 2002. Collections were made with an electro-fishing device in five stream reaches of the Ribeirão Grande system. Conductivity, pH, water temperature and dissolved oxygen were measured at each site. The species have different distributions in Ribeirão Grande system. Characidium lauroi is abundant in montane-piedmont zones and Characidium alipioi occurs mainly in piedmont-plain zones. Streams' different features contribute to these species' distribution in the system.

Length structure of fishes from a protected area in the State of São Paulo, Southeastern Brazil

The aim of this work was to study the length distribution of some fish species from the Protected Area of São Pedro and Analândia, State of São Paulo, Southeastern Brazil. Length distributions were correlated to environmental conditions at each sample site. For the most abundant species, length structure was compared among the streams of each basin and between basins. Differences in length structure were related to differences in growth, habitats, and even population.

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.

The influence of dietary vitamin C and E supplementation on the physiological response of pirarucu, Arapaima gigas, in net culture

This study evaluated the efficacy of dietary vitamin C (ascorbic acid or AA), vitamin E (α-tocopherol or α-T), and C + E supplementation on the blood parameters of Arapaima gigas grown in net cages for 45 days. Four treatments were tested: control (commercial feed); C800; E500 and C + E (800 + 500) with supplementation of 800 mg AA kg- 1, 500 mg α-T kg- 1 and 800 + 500 mg AA + α-T kg- 1, respectively. Hematocrit (Ht), red blood cells (RBC), and hemoglobin concentration (Hb) (oxidative status indicators), thrombocytes and leukocytes (immunological indicators), plasma protein and glucose were evaluated. Fish fed vitamin C and C + E supplemented diets showed greater weight gain and survival. Dietary vitamin C and C + E diet supplementation resulted in increased Ht, Hb, RBC, MCHC, total leukocytes, total proteins, thrombocytes and eosinophils compared to the control and α-T. The α-tocopherol-supplemented diet reduced the number of total thrombocytes, lymphocytes and neutrophils and increased glucose and eosinophils relatively to the control. In general, leukocytes and thrombocytes were good indicators of the efficiency of vitamin on the defense mechanism of the A. gigas reared in cages. Results indicate that high α-T diet supplementation provides no benefit for the maintenance of the oxidative or the immunological status of A. gigas. However, it was demonstrated that high dietary AA improves A. gigas immunological status. Red blood cell indices and immune system indicators showed no synergistic effect between the vitamins after supplementing the A. gigas diet with α-T + AA. © 2006 Elsevier Inc. All rights reserved.

α-Lipoic acid-enrichment partially reverses tissue ascorbic acid depletion in pacu (Piaractus mesopotamicus) fed vitamin C-devoid diets

Effects of dietary α-lipoic acid (LA) and ascorbic acid (AA) on the growth, tissue vitamin C and tocopherol (vitamin E) levels, and malondialdehyde levels were examined in the tropical fish pacu, Piaractus mesopotamicus. Pacu juveniles were fed one of four casein-gelatin-based diets for 8 weeks: with 0.05% AA and 0.1% LA (+AA+LA), with AA and without LA (+AA-LA), without AA and with LA (-AA+LA), and without AA and LA (-AA-LA). When the fish received quantities of feed equal to 1.9-2.5% of its body weight, growth was not influenced, regardless of the presence of AA or LA throughout most of the experimental period. Growth was, however, slightly but significantly lower at week 8 in the AA-deficient/LA-supplemented group. An AA-deficient diet caused a highly significant reduction in both total AA and dehydroascorbic acid content in the liver and gill tissues. This reduction of tissue AA concentrations was reversed in a significant manner by LA (antioxidant-sparing effect). The 8-week-long vitamin C deprivation was sufficient to initiate the reduction in tissue ascorbic acid; however, total ascorbate in the liver of fish in the (-)AA/(+)LA group was 127.7±54.3 nmol g-1 tissue, whereas it was 28.6±26.3 nmol g-1 in the (-)AA/(-)LA group, a 4.4-fold difference. This mitigating effect of the addition of the endogenous antioxidant LA to the diet indicates that LA exerts a vitamin C-sparing effect in teleost fish that by far exceeds the phenomena demonstrated in non-scurvy-prone mammals. There was no difference among the different diet groups for vitamin E and malondialdehyde levels in the liver. These results suggest that LA is a potent substance for the prevention of AA deficiency in cultured fishes. The optimal dietary level of LA needs to be determined in the light of the slight reduction in body weight gain after 8 weeks of feeding in the absence of AA. © Springer Science+Business Media, Inc. 2006.

Cortisol response to acute stress in jundiá Rhamdia quelen acutely exposed to sub-lethal concentrations of agrichemicals

Exposure to agrichemicals can have deleterious effects on fish, such as disruption of the hypothalamus-pituitary-inter-renal axis (HPI) that could impair the ability of fish to respond to stressors. In this study, fingerlings of the teleost jundiá (Rhamdia quelen) were used to investigate the effects of the commonly used agrichemicals on the fish response to stress. Five common agrichemicals were tested: the fungicide - tebuconazole, the insecticide - methyl-parathion, and the herbicides - atrazine, atrazine + simazine, and glyphosate. Control fishes were not exposed to agrichemicals and standard stressors. In treatments 2-4, the fishes were exposed to sub-lethal concentrations (16.6%, 33.3%, and 50% of the LC50) of each agrichemical for 96 h, and at the end of this period, were subjected to an acute stress-handling stimulus by chasing them with a pen net. In treatments 5-7 (16.6%, 33.3%, and 50% of the LC50), the fishes were exposed to the same concentrations of the agrichemicals without stress stimulus. Treatment 8 consisted of jundiás not exposed to agrichemicals, but was subjected to an acute stress-handling stimulus. Jundiás exposed to methyl-parathion, atrazine + simazine, and glyphosate presented a decreased capacity in exhibiting an adequate response to cope with stress and in maintaining the homeostasis, with cortisol level lower than that in the control fish (P < 0.01). In conclusion, the results of this study clearly demonstrate that the acute exposure to sub-lethal concentrations of methyl-parathion, atrazine + simazine, and glyphosate exert a deleterious effect on the cortisol response to an additional acute stressor in the jundiá fingerlings. © 2008 Elsevier Inc. All rights reserved.

An overview of functional and stereological evaluation of spermatogenesis and germ cell transplantation in fish

Although there are almost thirty-thousand species of fish living in a great variety of habitats and utilizing vast reproductive strategies, our knowledge of morphofunctional and quantitative aspects of testis structure and spermatogenesis is still incipient for this group of vertebrates. In this review, we discuss aspects that are important to better understanding of testis structure and function, and of the development of germ cells (GC) during spermatogenesis. To achieve this, we have recently completed a number of studies presenting morphometric and functional data related to the numbers of GC and Sertoli cells (SC) per each type of spermatogenic cyst, the number of spermatogonial generations, the SC efficiency, and the magnitude of GC loss that normally occurs during spermatogenesis. We also investigated SC proliferation and the relationship of this important event to early spermatogenic cysts. The available data strongly suggest that SC proliferation in sexually mature tilapia is the primary factor responsible for the increase in testis size and for determination of the magnitude of sperm production. The influence of temperature on the duration of spermatogenesis in tilapia was also evaluated and we have used this knowledge to deplete endogenous spermatogenesis in this teleost, in order to develop an experimental system for GC transplantation. This exciting technique results in new possibilities for investigation of spermatogenesis and spermatogonial stem cell biology, creating also an entirely new and promising scenario in biotechnology - transgenic animal production and the preservation of the genetic stocks of valuable animals or endangered species. © Springer Science+Business Media B.V. 2008.

Cell junctions in fish seminiferous epithelium

Similar to mammals, in fish the cellular interactions between Sertoli cells (SC) and germ cells (GC) in the seminiferous epithelium have important structural and functional roles. In this review, we give a brief summary of these interactions, in particular those on the cell junctions. Despite the scarcity of detailed empirical data, it appears that both basic types of adhesive junctions (actin- and intermediate filaments-related) are present between SC. However, the actin-related multifunctional junction known as the ectoplasmic specialization is seemingly present only in some cartilaginous fish. Conversely, SC in other fish species are joined by actin-related junctions similar to typical zonulae or puncta adherens found in other epithelia. Adhesive junctions are also found between SC and GC and between GC and GC, and due to their particular characteristics these junctions are known as desmosome-like junctions. In terms of intercellular communication, connexins and gap junctions have been shown to occur between SC in fish, and they may be involved in the coordination of the synchronous development of GC within the cysts. It is also possible that gap junctions may form an interconnected network between SC and GC within a cyst. Concerning the SC barrier, tight junctions between fish SC apparently form a functional barrier only in cysts containing haploid GC, and different from mammals, meiotic GC in fish are not shielded from the vascular system. In summary, although still not well investigated, cell-cell interactions in the seminiferous epithelium of fish seem to be crucial for GC development, and their disturbance, for example by changing environmental conditions, will probably affect GC survival and fertility. © Springer Science+Business Media B.V. 2008.

Metabolic, ventilatory, and hygric physiology of the gracile mouse opossum (Gracilinanus agilis)

We present the first complete study of basic laboratory-measured physiological variables (metabolism, thermoregulation, evaporative water loss, and ventilation) for a South American marsupial, the gracile mouse opossum (Gracilinanus agilis). Body temperature (Tb) was thermolabile below thermoneutrality (Tb = 33.5°C), but a substantial gradient between Tb and ambient temperature (Ta) was sustained even at Ta = 12°C (Tb = 30.6°C). Basal metabolic rate of 1.00 mL O2 g-1 h-1 at Ta = 30°C conformed to the general allometric relationship for marsupials, as did wet thermal conductance (5.7 mL O2 g-1 h-1 °C-1). Respiratory rate, tidal volume, and minute volume at thermoneutrality matched metabolic demand such that O2 extraction was 12.4%, and ventilation increased in proportion to metabolic rate at low T a. Ventilatory accommodation of increased metabolic rate at low Ta was by an increase in respiratory rate rather than by tidal volume or O2 extraction. Evaporative water loss at the lower limit of thermoneutrality conformed to that of other marsupials. Relative water economy was negative at thermoneutrality but positive below Ta = 12°C. Interestingly, the Neotropical gracile mouse opossums have a more positive water economy at low Ta than an Australian arid-zone marsupial, perhaps reflecting seasonal variation in water availability for the mouse opossum. Torpor occurred at low Ta, with spontaneous arousal when . T b > 20°C. Torpor resulted in absolute energy and water savings but lower relative water economy. We found no evidence that gracile mouse opossums differ physiologically from other marsupials, despite their Neotropical distribution, sympatry with placental mammals, and long period of separation from Australian marsupials. © 2009 by The University of Chicago. All rights reserved.

Recent advances in brain physiology and cognitive processing

The discovery of participation of astrocytes as active elements in glutamatergic tripartite synapses (composed by functional units of two neurons and one astrocyte) has led to the construction of models of cognitive functioning in the human brain, focusing on associative learning, sensory integration, conscious processing and memory formation/retrieval. We have modelled human cognitive functions by means of an ensemble of functional units (tripartite synapses) connected by gap junctions that link distributed astrocytes, allowing the formation of intra- and intercellular calcium waves that putatively mediate large-scale cognitive information processing. The model contains a diagram of molecular mechanisms present in tripartite synapses and contributes to explain the physiological bases of cognitive functions. It can be potentially expanded to explain emotional functions and psychiatric phenomena. © MSM 2011.

FTMOntology: An ontology to fill the semantic gap between music, mood, personality, and human physiology

This paper presents a domain ontology, the FeelingTheMusic Ontology - FTMOntology. FTMOntology is designed to represent the complex domain of music and how it relates to other domains like mood, personality and physiology. This includes representing the main concepts and relations of music domain with each of the above-mentioned domains. The concepts and relations between music, mood, personality and physiology. The main contribution of this work is to model and relate these different domains in a consistent ontology. © 2011 Springer-Verlag.