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Infra slow oscillations (ISO) are low frequency (<0.1Hz) fluctuations detected at the various levels of the brain organisation. In the urethane model of sleep at least a few ISOs can be detected in the rat brain: (1) urethane sleep structure – cyclic alternation of brain state between activated and deactivated EEG patterns; (2) rhythmic, neuronal bursting in the the subcortical visual system – e.g., olivary pretectal nuclei (OPN). Our preliminary observation has revealed that, under constant illumination, the pupil size of the anaesthetised rat oscillates with the period in the range of ISO. The present study was aimed to: (1) determine the relationship between the changes in the pupil size and the ISOs observed in the brain; (2) elucidate the neuronal mechanism of observed pupil size changes. The following signals were simultaneously recorded from urethane anaesthetised rats: multisite ECoG, neuronal firing in left and right OPN, video of the left and right eye. Results revealed that changes of the size of the pupils are synchronised with each other and characterized by two dominant ISO frequencies (~0.01Hz and <0.001Hz). A simple mathematical model of iris smooth muscle constriction and relaxation was proposed to verify the hypothesis that observed changes of the size of the pupils are result of the interference of the three ISOs. The model is governed by the linear first order Ordinary Differential Equation that expresses the muscle relaxation and integration of three ISOs. The parameters of the model were fit to the measured area changes using nonlinear least squares algorithm. It is shown that the area changes predicted from the model correlate well with the observed values. Moreover the analysis revealed that taking all three ISOs into account produces significantly better fit of the model to observed data than any one or two signals, which means that observed pupillary oscillations are result of the interference of all three ISOs recorded in the brain.
Background. Our previous study has shown that four aquatic weeds viz. Asian watermoss, Salvinia cucullata; water spinach Ipomoea reptans; water chestnut, Trapa natans; and lesser duckweed, Lemna minor from north-east India are important sources of proteins, vitamins and minerals, suitable for incorporation in fish diet. The aim of the present study was to compare the efficacy of these aquatic weeds based formulated diets on growth, feed utilization and nutrient turnover from feed to fish flesh of fingerlings of two species of Indian major carps: catla, Catla catla (Hamilton, 1822), and mrigal, Cirrhinus mrigala (Bloch, 1795). Materials and Methods. The fingerlings were hand-sorted and distributed in 15 glass aquaria (each having 50 l capacity) at a stocking density of 5 fishes per aquarium. Five formulated diets (containing 26%–28% of crude protein approximately) were prepared and analyzed for proximate composition. The diets were fed to catla and mrigal fingerlings in triplicate treatments at the rate 3% of body weight for 60 days and fish performance in terms of growth, feed utilization and carcass composition was evaluated. Results. The whole body composition and energy content of C. catla fingerlings before and at the end of feeding trials did not differ significantly (P > 0.05), however, the proportion of crude lipid content was high when fed with diet F2 (P < 0.05). In case of C. mrigala, crude protein, as well as lipid contents, were significantly higher in all the groups of fish at the end of experiment as compared to the initial fish. The hepatic- as well as the muscle tissues of catla and mrigal fingerlings fed the diet F2 (containing I. reptans) displayed high contents of crude protein and vitamin E (P < 0.01). Interestingly, although no difference in muscle glycogen level in C. mrigala was observed irrespective of the diet fed however, muscle and liver glycogen contents in Catla catla fingerlings fed F2 diet was significantly higher compared to glycogen contents of these tissues of initial fish or fish fed with control diet. Conclusion. Presently reported study suggests that I. reptans, being a rich source of nutrients, is suitable for incorporation in fish diet for C. catla and C. mrigala fingerlings.
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