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11.
P L Cedraz-Mercez A C Almeida C M Thomaz R H Costa-e-Sousa E L Olivares W S C?rtes M A Medeiros L C Reis 《Revista brasleira de biologia》2007,67(4):771-776
The purpose of this study was to explore the role of L-5-hydroxytryptophan (L-HTP) and its relationship with the renin-angiotensin system (RAS) on the drinking behavior in Japanese quails. Normally-hydrated quails that received injections of L-HTP (12.5; 25 and 50 mg.kg-1) by the intracoelomic route (ic) expressed an increase in water intake, which was inhibited by captopril, an angiotensin converting enzyme (ACE) inhibitor. In addition, captopril also induced such a response in birds under previous fluid deprivation. High doses of captopril (35-70 mg.kg-1, sc) in normally-hydrated quails decreased the spontaneous water intake while low doses of captopril (2-5 mg.kg-1, sc) did not prompt water intake after L-HTP administration. Losartan, an AT1 receptor antagonist in mammals, did not change the water intake levels in normally-hydrated or water-deprivated birds. Serotonin (5-HT) injections did not provoke its known dipsogenic response. 相似文献
12.
Moreira TS Sato MA Takakura AC Menani JV Colombari E 《American journal of physiology. Regulatory, integrative and comparative physiology》2005,289(5):R1416-R1425
In the present study, we investigated the effects of inhibition of the caudal ventrolateral medulla (CVLM) with the GABA(A) agonist muscimol combined with the blockade of glutamatergic mechanism in the nucleus of the solitary tract (NTS) with kynurenic acid (kyn) on mean arterial pressure (MAP), heart rate (HR), and regional vascular resistances. In male Holtzman rats anesthetized intravenously with urethane/chloralose, bilateral injections of muscimol (120 pmol) into the CVLM or bilateral injections of kyn (2.7 nmol) into the NTS alone increased MAP to 186 +/- 11 and to 142 +/- 6 mmHg, respectively, vs. control: 105 +/- 4 mmHg; HR to 407 +/- 15 and to 412 +/- 18 beats per minute (bpm), respectively, vs. control: 352 +/- 12 bpm; and renal, mesenteric and hindquarter vascular resistances. However, in rats with the CVLM bilaterally blocked by muscimol, additional injections of kyn into the NTS reduced MAP to 88 +/- 5 mmHg and mesenteric and hindquarter vascular resistances below control baseline levels. Moreover, in rats with the glutamatergic mechanisms of the NTS blocked by bilateral injections of kyn, additional injections of muscimol into the CVLM also reduced MAP to 92 +/- 2 mmHg and mesenteric and hindquarter vascular resistances below control baseline levels. Simultaneous blockade of NTS and CVLM did not modify the increase in HR but also abolished the increase in renal vascular resistance produced by each treatment alone. The results suggest that important pressor mechanisms arise from the NTS and CVLM to control vascular resistance and arterial pressure under the conditions of the present study. 相似文献
13.
da Silva RB Lima Neto AF Soares Dos Santos LS de Oliveira Lima JR Chaves MH Dos Santos JR de Lima GM de Moura EM de Moura CV 《Bioresource technology》2008,99(15):6793-6798
Catalysts of Cu(II) and Co(II) adsorbed in chitosan was used in transesterification of soy bean and babassu oils. The catalysts were characterized by infrared, atomic absorption and TG, and biodiesels was characterized by infrared, NMR, CG, TG, physic chemistry analysis. The maximum adsorption values found for copper and cobalt cations were 1.584 and 1.260mgg(-1), respectively, in 180min. However, conversion of oils in biodiesel was better when used Co(II) adsorbed in chitosan. 相似文献
14.
Senescent, naturally dried leaves of Typha domingensis were incubated inthe littoral region of a coastal lagoon and epiphytic bacterial volume,abundance, biomass and secondary productivity were measured during 127 daysof decomposition. The peak of cell abundance was registered at t =127 days when expressed per leaf surface area (10.07×107cells cm-2; 7.26 µgC cm-2), and at t= 26 days when expressed per biofilm dry mass (38.10 ×107 cells (mgDM biofilm)-1, 30.52 µgC(mgDM biofilm)-1). The highest values of bacterial biovolumesand lower turnover time were usually obtained in the beginning of thecolonization. Leu:Tdr ratios were also higher in the beginning of thecolonization, when bacterial community presented unbalanced metabolism.Consequently, the highest discrepancies between the bacterial secondaryproduction estimated by leu and Tdr incorporation were observed in the first2 days of decomposition. On average, the bacterial secondary productivityestimated by leu incorporation was 2.1 times higher than the valuesestimated by Tdr incorporation when the empirical factor for Tdr wasobtained from the relationship between Tdr and biomass increment. Thisdifference increased to 4.2 when the empirical factor was obtained from therelationship between Tdr and cell numbers increment. An average of bothmethods (0.0037 to 0.1397 µgC cm-2 h-1)produced results that fall within the range reported in the literature forepiphytic bacteria of freshwater ecosystems. 相似文献
15.
Assessment of the environmental factors that control species richness (S) is a central issue in ecology. In this study, aquatic macrophyte S was estimated in 235 sampling sites distributed in 8 arms of a large (1350 km2) subtropical reservoir (Itaipu Reservoir, Brazil). Morphometric variables (area, shoreline development and length of shoreline, all measured for each arm; n= 8) and environmental variables measured at each sampling site (extinction coefficient of light (k), electrical conductivity, fetch, distance from the main reservoir body; n = 235) were used to predict aquatic macrophyte S at two spatial scales. At arm scale, linear regression analysis indicated that length of shoreline was a better predictor of S than area. At sampling site scale, multiple regression analysis indicated that S was significantly predicted by electrical conductivity, fetch and distance from the main body. However, other relationships with predictive interest was demonstrated by using non-traditional regression approaches. This analysis started by the visual inspection of scatter plots. The bivariate relationship between S and fetch, for example, showed an envelope or a `left triangle' pattern. The relationship between the number of submerged species and k showed an asymmetrical left triangle pattern. Using randomization procedures, it was demonstrated that these patterns were not generated by chance alone. Beta diversity (estimated within the arms) was significantly and positively correlated with spatial environmental variability. Overall, these results indicate that the prediction of aquatic macrophytes assemblage variables in large waterbodies, specially S, is more complex than previous studies have suggested. 相似文献
16.
L C Reis A C Almeida P L Cedraz-Mercez E L Olivares A Marinho Jr C M Thomaz 《Revista brasleira de biologia》2005,65(2):353-361
We investigated participation of the brain serotonergic system in food intake control by using oral and systemic administration of serotonin precursors in quails (Coturnix japonica). Dietary supplemental tryptophan (0.1-50.0 g/kg) provoked a dose-dependent inhibition of food intake during a 5-h observation period, which persisted up to 24 h for doses of 30.0 and 50.0 g/kg. Normally fed and fasted animals treated with hydroxytryptophan (12.5-50.0 mg/kg) by the intracoelomic route showed an acute inhibition of food intake. Hypophagia in fasted birds was only effective when the precursor was administered immediately before food presentation. A similar response was obtained by administering serotonin (0.125-2.5 mg/kg, sc), with animals showing a hypnogenic response within the first ten minutes after administration, suggesting that, in contrast to mammals, the amine crosses the blood-brain barrier in quails. Administration of hydroxytryptophan at all doses tested induced significant dipsogenic behavior despite the concomitant hypnogenic response. The results suggest the involvement of serotonergic pathways in food intake control in quails and also show, for the first time, hypnogenic action induced by serotonin and a hyperdipsic effect elicited by hydroxytryptophan. 相似文献
17.
The architecture of river networks can drive the evolutionary dynamics of aquatic populations
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Andréa T. Thomaz Mark R. Christie L. Lacey Knowles 《Evolution; international journal of organic evolution》2016,70(3):731-739
It is widely recognized that physical landscapes can shape genetic variation within and between populations. However, it is not well understood how riverscapes, with their complex architectures, affect patterns of neutral genetic diversity. Using a spatially explicit agent‐based modeling (ABM) approach, we evaluate the genetic consequences of dendritic river shapes on local population structure. We disentangle the relative contribution of specific river properties to observed patterns of genetic variation by evaluating how different branching architectures and downstream flow regimes affect the genetic structure of populations situated within river networks. Irrespective of the river length, our results illustrate that the extent of river branching, confluence position, and levels of asymmetric downstream migration dictate patterns of genetic variation in riverine populations. Comparisons between simple and highly branched rivers show a 20‐fold increase in the overall genetic diversity and a sevenfold increase in the genetic differentiation between local populations. Given that most rivers have complex architectures, these results highlight the importance of incorporating riverscape information into evolutionary models of aquatic species and could help explain why riverine fishes represent a disproportionately large amount of global vertebrate diversity per unit of habitable area. 相似文献
18.
Jonathan?Fernando?Teixeira Pedro?Henrique?de?Oliveira Neto Wiliam?Ferreira?da?CunhaEmail author Luiz?Antonio?RibeiroJr. Geraldo?Magela?e?Silva 《Journal of molecular modeling》2017,23(10):293
The geometry configuration of charged armchair graphene nanoribbons (AGNRs) is theoretically investigated in the framework of a two-dimensional tight-binding model that includes lattice relaxation. Our findings show that the charge distribution and, consequently, the bond length pattern is dependent on the parity of the nanoribbon width. In this sense, the lattice distortions decrease smoothly for increasingly wider GNRs. As should be expected, AGNRs belonging to a particular family present similar patterns for the bond lengths. The interplay between the electron-phonon coupling and band gap is also investigated. The results show that the electron-phonon coupling strength is fundamental to promote the transition from metallic towards semiconducting-like behavior for the band gap. Most important, such strength is crucial on defining the degree of lattice distortions in AGNRs. 相似文献
19.
André Andrian Padial Sidinei Magela Thomaz Angelo Antonio Agostinho 《Hydrobiologia》2009,624(1):161-170
Macrophytes have a fundamental structuring role in aquatic environments. Several authors have suggested that trophic interactions
are particularly mediated by aquatic plants. In the current article, we evaluated the effects of the structural heterogeneity
provided by Eichhornia azurea (Kunth) roots on predation and habitat use by the small fish Moenkhausia sanctaefilomenae (Steindachner). We tested the hypotheses that (i) high structural heterogeneity protects macroinvertebrates against predation
by M. sanctaefilomenae; (ii) distinct prey types are differently protected by the refuge provided by roots; and (iii) the behavior of M. sanctaefilomenae is affected by the structural heterogeneity provided by macrophyte roots. To test these hypotheses, we performed an experiment
in 20 l aquaria in which macroinvertebrates (Cypricercus sp. and Chironomus sp.) were exposed to M. sanctaefilomenae predation for 4 h under three structural heterogeneities, represented by different root densities. High structural heterogeneity
protected macroinvertebrates against predation. Additionally, E. azurea roots similarly protected different prey species. The macrophyte spatial structure substantially changed the habitat use
of M. sanctaefilomenae. In general, our results corroborated the hypothesis that the structural heterogeneity provided by E. azurea roots significantly affects predation and habitat use by M.
sanctaefilomenae.
Handling editor: S. Declerck 相似文献
20.
W. T. Z. Sousa S. M. Thomaz K. J. Murphy M. J. Silveira R. P. Mormul 《Hydrobiologia》2009,632(1):65-78
The Upper River Paraná Floodplain System comprises the rivers Ivinheima, Baía and Paraná, which with their associated waterbodies form three subsystems, each showing individual characteristics. Hydrilla verticillata recently invaded the Upper Paraná Floodplain, while Egeria najas is the native most abundant submersed macrophyte. A large flood-pulse, during January–March 2007, abruptly reduced macrophyte stands in many areas to near-zero and dispersed propagules over the entire floodplain. From April 2007 to April 2008, we conducted three surveys sampling for the presence–absence of H. verticillata and E. najas and environmental variables aiming to answer: (1) How rapid is the colonization–regeneration process for both species? (2) Which habitats seem to be more susceptible to their colonization? (3) Which environmental factors can best predict their occurrence? Neither H. verticillata nor E. najas colonized the Ivinheima subsystem. In the Baía subsystem, E. najas had only two occurrences while H. verticillata was not present. In the Paraná subsystem, E. najas predominantly occurred in river channels, but it was also common in floodplain lakes. In April 2007, it was found in 13% of the sites in the Paraná subsystem, increasing to 30% in November 2007 and reaching 34% in April 2008. H. verticillata did not successfully colonize floodplain lakes of the Paraná subsystem. In channels, it had 34% occurrence in April 2007, increasing to 62% in November 2007 and remaining at 62% in April 2008. The role of environmental variables in predicting species occurrence changed depending upon the scale of the analysis. Considering the whole Upper Paraná floodplain, water transparency followed by electrical conductivity were the strongest predictors for both species. Colonization by submersed plants seems improbable in the Ivinheima subsystem owing to its low water transparency besides frequent localized floods; in the Baía subsystem, it seems inhibited by transparency and low alkalinity. Considering just the Paraná subsystem, the proportion of organic matter in sediment, ten times higher in floodplain lakes than in channels, was the best predictor for H. verticillata occurrence (also related to water pH and transparency), while E. najas was only significantly explained by transparency. 相似文献