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41.
Sousa FL Veríssimo AF Baptista AM Soulimane T Teixeira M Pereira MM 《Biophysical journal》2008,94(6):2434-2441
A comprehensive study of the thermodynamic redox behavior of the hemes of the ba3 enzyme from Thermus thermophilus, a B-type heme-copper oxygen reductase, is presented. This enzyme, in contrast to those having a single type of heme, allows the B- and A-type hemes to be monitored separately by visible spectroscopy and the reduction potential of each heme to be determined unequivocally. The relative order of the midpoint reduction potentials of each center changed in the pH range from 6 to 8.4, and both hemes present a significant redox-Bohr effect. For instance, at pH 7, the midpoint reduction potentials of the hemes B and A3 are 213 mV and 285 mV, respectively, whereas at pH 8.4, the order is reversed: 246 mV for heme B and 199 mV for heme A3. The existence of redox anticooperativity was established by introducing a redox interaction parameter in a model of pairwise interacting redox centers. 相似文献
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43.
Substrate specificity,environmental degradation and disturbance structuring macroinvertebrate assemblages in neotropical streams 总被引:1,自引:0,他引:1
Buss Daniel F. Baptista Darcílio F. Nessimian Jorge L. Egler Mariana 《Hydrobiologia》2004,518(1-3):179-188
Structure and composition of benthic macroinvertebrate assemblages were investigated in seven sampling sites with a gradient of environmental integrity and water quality conditions. Composite samples of the four most representative substrates were collected in order to characterize the riffle-pool dynamic in each sampling site. Spatial and temporal variability of macroinvertebrate assemblages were analyzed at two scales: using substrates and grouping samples for comparing sampling sites. Distribution of macroinvertebrates was influenced primarily by substrate type, but also by environmental integrity, water quality and sampling period. Species occurrence was highly dependent on substrate type. At local spatial scale, environmental degradation measured by the Riparian Channel Environmental Inventory and water chemistry were the determinants of assemblage patterns. We evaluated to which extent the substrates were influenced by environmental integrity and water chemistry, and we found that degradation influenced significantly the macroinvertebrate fauna on the four substrate types, although they were not responding to the same variables. Our results show that qualitatively communities were not influenced by seasonal changes, but abundance was stochastically dependent on rainfall. 相似文献
44.
J. R. Poortmans E. Blommaert M. Baptista M. E. De Broe E. J. Nouwen 《European journal of applied physiology and occupational physiology》1997,76(1):88-91
Post-exercise proteinuria is a common phenomenon in healthy subjects. Previous studies have used albumin (Alb) and β2-microglobulin (β2-m) molecules as representatives of high- and low-molecular-weight proteins. Recently, more specific markers of the human
kidney proximal tubule have been used to identify the precise site of alterations. Active male subjects underwent two strenuous
runs, one 400-m run and one 3000-m run. Urine was collected from the subjects before and after each event. Total protein (TP),
Alb, α1-microglobulin (α1-m), β2-m, intestinal alkaline phosphatase (IAP), tissue-nonspecific alkaline phosphatase (TNAP) and N-acetyl-β-d-glucosaminidase (NAG) were determined for each sample. The short-distance run (400 m) resulted in the largest increases (P ≤ 0.05) in TP (31-fold), Alb (100-fold) and β2-m (164-fold) as compared to the long-distance run (3000-m). The α1-m excretion rates were increased to a lesser extent by the exercises. The IAP activity was slightly increased (+90%) by the
400-m run while the TNAP and NAG activities showed a 6.8-fold and a 3.6-fold increase, respectively, after this event. Smaller
increases were recorded for the long-distance run (P = 0.05). To conclude, the present investigation showed that: (1) post-exercise proteinuria is related to the absolute intensity
of exercise; (2) the impairment of protein reabsorption is revealed better by changes in Alb and β2-m; (3) changes in TNAP and NAG activities could reveal biochemical modifications that occur in the proximal tubule, particularly
at the S1-S2 segment.
Accepted: 31 January 1997 相似文献
45.
In adult Hirudo medicinalis, the segmental ganglia (SG) of the fifth and sixth body segments contain a few hundred more cells than the other segmental ganglia of the body (Macagno, 1980). These ganglia innervate the sex organs and are known as the sex SG. As shown here, these cells are stained by neuron-specific antibodies. Cell counts at several developmental stages reveal that the extra cells are added exclusively to the sex SG, and that this addition occurs gradually and almost entirely postembryonically (embryogenesis ends at 30 days of development). Hence, we refer to them as PE cells. Until 16 days of development, deleting the male genitalia or disconnecting them from the sex ganglia results in a complete absence of the PE cells. From 16 days onward, the generation of the PE cells is independent of the male genitalia. No PE cells appear in non-sex SG that innervate male genitalia transplanted to ectopic locations at 10 days or later, indicating that as early as about 10 days of development sex SG are different from other SG in their ability to acquire PE cells. These data suggest that the PE cells are generated within the sex SG, in a process that is triggered by an interaction with the male genitalia and mediated through the innervation of the organs by these ganglia. 相似文献
46.
Murilo S. Baptista Rero M. Rubinger Emilson R. Viana José C. Sartorelli Ulrich Parlitz Celso Grebogi 《PloS one》2012,7(10)
The amount of information exchanged per unit of time between two nodes in a dynamical network or between two data sets is a powerful concept for analysing complex systems. This quantity, known as the mutual information rate (MIR), is calculated from the mutual information, which is rigorously defined only for random systems. Moreover, the definition of mutual information is based on probabilities of significant events. This work offers a simple alternative way to calculate the MIR in dynamical (deterministic) networks or between two time series (not fully deterministic), and to calculate its upper and lower bounds without having to calculate probabilities, but rather in terms of well known and well defined quantities in dynamical systems. As possible applications of our bounds, we study the relationship between synchronisation and the exchange of information in a system of two coupled maps and in experimental networks of coupled oscillators. 相似文献
47.
48.
A multimetric index based on benthic macroinvertebrates for evaluation of Atlantic Forest streams at Rio de Janeiro State, Brazil 总被引:3,自引:0,他引:3
Darcilio F. Baptista Daniel F. Buss Mariana Egler Alexandre Giovanelli Mariana P. Silveira Jorge L. Nessimian 《Hydrobiologia》2007,575(1):83-94
This study describes the application of a protocol for biological assessment of water quality at first to third order streams
at Serra dos órg?os, an area covered by Atlantic Forest in Rio de Janeiro State, Brazil. Major impacts in the region are domestic
effluents and deforestation. Our main objective is to establish biocriteria for the establishment of the Serra dos órg?os
Multimetric Index (SOMI) based on benthic macroinvertebrates. We used data from previous studies, sampled by experienced biologists,
from 1999 through 2002. The benthic macroinvertebrate community was sampled in 12 reference sites and seven impaired sites
in three river basins: Guapimirim, Macaé and Grande, all from the same bioregion. From the 22 tested metrics, 6 were included
in the SOMI (% Diptera, % Coleoptera, Family Taxa, EPT Taxa, BMWP-CETEC and % Shredders). Scores (5, 3 or 1) were developed
for these metrics to allow for aggregation into the index. Seven intermediately impaired sites were used for evaluating the
applicability of the multimetric index. We concluded that the SOMI is a robust easy-to-apply tool for biomonitoring programs
in the Serra dos órg?os region, south-east Brazil.
Electronic Supplementary Material Supplementary material is available for this article at and is accessible for authorised users.
Handling editor: D. Dudgeon 相似文献
49.
Predicting the partition coefficients of a recombinant cutinase in polyethylene glycol/phosphate aqueous two-phase systems 总被引:1,自引:0,他引:1
Sebastião MJ Martel P Baptista A Petersen SB Cabral JM Aires-Barros MR 《Biotechnology and bioengineering》1997,56(3):248-257
A model for the prediction of protein partition coefficients in aqueous two-phase systems has been developed. This model accounts for both charge-independent and electrostatic effects. The determination of nonelectrostatic effects was based on the model of Eiteman and Gainer for uncharged solutes while the electrostatic contribution was computed using TITRA, a program that uses a continuum electrostatic model to treat charge interactions in proteins and considers the effect of pH and ionic strength. The partition coefficients of Fusarium solani pisi recombinant cutinase have been satisfactorily predicted in polyethylene glycol (PEG) 1000 and phosphate aqueous two-phase systems at a pH range of 6.0-9.0. The model failed to predict the enzyme partitioning behavior at pH 4.5. (c) 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 56: 248-257, 1997. 相似文献
50.