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1.
2.
Valérie Toulon Hervé Sentenac Jean-Baptiste Thibaud André Soler David Clarkson Claude Grignon 《Planta》1989,179(2):235-241
The effect of HCO
3
-
on ion absorption by young corn roots was studied in conditions allowing the independent control of both the pH of uptake solution and the CO2 partial pressure in air bubbled through the solution. The surface pH shift in the vicinity of the outer surface of the plasmalemma induced by active H+ excretion was estimated using the initial uptake rate of acetic acid as a pH probe (Sentenac and Grignon (1987) Plant Physiol. 84, 1367). Acetic acid and orthophosphate uptake rates and NO
3
-
accumulation were slowed down, while 86Rb+ uptake and K+ accumulation rates were increased by HCO
3
-
. These effects were similar to those induced by 4-(2-hydroxyethyl)-1-piperazineethane sulfonic acid/2-amino-2-(hydroxymethyl)-1,3-propanediol (Hepes-Tris). They were more pronounced when the H+ excretion was strong, were rapidly reversible and were not additive to those of Hepes-Tris. The hypothesis is advanced that the buffering system CO2/H2CO3/HCO
3
-
accelerated the diffusion of equivalent H+ inside the cell wall towards the medium. This attenuated the surface pH shift in the vicinity the plasma membrane and affected the coupling between the proton pump and cotransport systems.Abbreviations FW
fresh weight
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- Jaa
acetic acid influx
- JK
+
K+ influx
- JPi
orthophosphate influx
- Mes
2-(N-morpholino)ethanesulfonic acid
- pCO2
CO2 partial pressure
- Tris
2-amino-2-(hydroxymethyl)-1,3-propanediol 相似文献
3.
Valérie Maxime Jean-Pierre Pennec Claude Peyraud 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1991,161(6):557-568
Summary The effects of increased ambient salinity (35 mg · ml-1) were studied at 1, 6, and 24 h after direct transfer of rainbow trout from freshwater to seawater. Two series of experiments were carried out successively. The first series was designed to simultaneously study all the respiratory (except Hb affinity for O2), circulatory, and acid-base variables in each fish. In this series, fish were fitted with catheters chronically inserted into the cardiac bulbus, the dorsal aorta, and the opercular and buccal cavities. In the second series, designed to study haemoglobin O2 affinity, fish were fitted with only a dorsal aorta catheter. The ventilatory flow (
) was markedly increased just after transfer (by 55% at 1 h), then more moderately (by 20% at 6 h and 32% at 24 h). The initial hyperventilation peak was associated with frequent couphing motions. These ventilatory changes resulted essentially from increase in ventilatory amplitude. Initially, standard oxygen consumption (MM}O2) decreased slightly, the moderately increased (by 12% at 24 h), so that the oxygen convection requirement (
) increased substantially. In spite of an increased ventilation, the partial pressure of oxygen in arterial blood (P
aO2) decreased slightly at 1 h, prior to returning to control levels, while partial pressure of carbon dioxide in arterial blood (P
aCO2) was not significantly decreased. Gill oxygen transfer factor decreased substantially at 1 h (by 35%) then more moderately (by 7% at 1 h and 12% at 24 h). These results suggest a decrease in gas diffusing capacity of the gills. As P
aCO2 remained approximatively unchanged, the gradual decrease in arterial pH (pHa) from 7.94 to 7.67 at 24 h must therefore be regarded as a metabolic acidosis. The strong ion difference decreased markedly because the concentration of plasma chloride increased more than that of sodium. Arterial O2 content (C
aO2) gradually decreased (by 38% at 24 h) simultaneously with the decrease in pHa, while the ratio P
aO2/C
aO2 increased. In parallel, seawater exposure induced a marked decrease in affinity of haemoglobin for O2, so that at 24 h, P50 was increased by 26% above the value obtained in freshwater-adapted trout. The increase in
could be ascribed initially (at 1 h) to the decrease of P
aO2 and later to a stimulation of respiratory neurons resulting from the lowered medullary interstitial pH. The decrease in C
aO2 could be interpreted mainly as a consequence of a decreased affinity of haemoglobin for O2, likely to be due to the blood acidosis and a predictable increase in chloride concentration within erythrocytes. Cardiac output (
) slightly decreased at 1 h, then progressively increased by 30% at 24 h. Branchial vascular resistance increased at 1 h by 28%, then decreased by 18% of the control value at 24 h. Systemic vascular resistance decreased markedly by 40% at 24 h. As heart rate (HR) remained significantly unchanged, the cardiac stroke volume initially decreased then increased in relation to the changes in
. The increase of
, allowing compensation for the effect of decreased C
aO2 in tissue O2 supply, was interpreted as a passive consequence of the decrease in total vascular resistance occurring during seawater exposure.Abbreviations a.u.
arbitrary units
-
C
aO2
arterial oxygen content
- pH50
arterial pH at P50
-
C
vO2
venous oxygen content
- Hb
haemoglobin
- HR
heart rate
- Hct
hematocrit
- nHill
Hill coefficient
- O2
standard oxygen consumption
-
P
aCO2
arterial partial pressure of carbon dioxide
-
P
aO2
arterial partial pressure of oxygen
-
P
vO2
oxygen partial pressure in mixed venous blood
- P50
oxygen tension at half saturation of haemoglobin
-
P
VA, P
DA
blood pressure in ventral and dorsal aorta
- pHa
arterial pH
-
PIO2, PEO2
oxygen partial pressure of inspired and expired water
-
PO2
oxygen partial pressure
-
cardiac output
- SEM
standard error of mean
- S.I.D.
strong ion difference
- SV
cardiac stroke volume
- TO2
gill oxygen transfer factor
- U
oxygen extraction coefficient
- VA
ventilatory amplitude
- VF
ventilatory frequency
- VRG, VRS
branchial and systemic vascular resistances
-
ventilatory flow
-
ventilatory oxygen convection requirement 相似文献
4.
Gwenola Gandon Anne Marie Jouanolle Bruno Chauvel Valérie Mauvieux André Le Treut Josué Feingold Jean Yves Le Gall Véronique David Jacqueline Yaouanq 《Human genetics》1996,97(1):103-113
The hemochromatosis gene (HFE) maps to 6p21.3, in close linkage with the HLA Class I genes. Linkage disequilibrium (LD) studies were designed to narrow down the most likely candidate region for HFE, as an alternative to traditional linkage analysis. However, both the HLA-A and D6S105 subregions, which are situated 2–3 cM and approximately 3 Mb apart, have been suggested to contain HFE. The present report extends our previous study based upon the analysis of a large number of HFE and normal chromosomes from 66families of Breton ancestry. In addition to the previously used RFLP markers spanning the 400-kb surrounding HLA-A, we examined three microsatellites: D6S510, HLA-F, and D6S105. Our combined data not only confirm a peak of LD at D6S105, but also reveal a complex pattern of LD over the i82 to D6S105 interval. Within our ethnically well-defined population of Brittany, the association of HFE with D6S105 is as great as that with HLA-A, while the internal markers display a lower LD. Fine haplotype analysis enabled us to identify two categories of haplotypes segregating with HFE. In contrast to the vast majority of normal haplotypes, 50% of HFE haplotypes are completely conserved over the HLA-A to D6S105 interval. These haplotypes could have been conserved through recombination suppression, selective forces and/or other evolutionary factors. This particular haplotypic configuration might account for the apparent inconsistencies between genetic linkage and LD data, and additionally greatly complicates positional cloning of HFE through disequilibrium mapping.The authors contributed equally to this work 相似文献
5.
J. L. Marco L. A. Bataus F. F. Valência C. J. Ulhoa S. Astolfi-Filho C. R. Felix 《Applied microbiology and biotechnology》1996,44(6):746-752
ABacillus subtilis amylase gene was inserted into a plasmid which transferred toEscherichia coli. During cloning, a 3 region encoding 171 carboxyterminal amino acids was replaced by a nucleotide sequence that encoded 33 amino acid residues not present in the indigenous protein. The transformed cells produced substantial amylolytic activity. The active protein was purified to apparent homogeneity. Its molecular mass (48 kDa), as estimated in sodium dodecyl sulfate/polyacrylamide gel electrophoresis, was lower than the molecular mass values calculated from the derived amino acid sequences of theB. subtilis complete -amylase (57.7 kDa) and the truncated protein (54.1 kDa). This truncated enzyme form hydrolysed starch with aK
m of 3.845 mg/ml. Activity was optimal at pH 6.5 and 50°C, and the purified enzyme was stable at temperatures up to 50°C. While Hg2+, Fe3+ and Al3+ were effective in inhibiting the truncated enzyme Mn2+ and Co2+ considerably enhanced the activity. 相似文献
6.
A new gene coding for an antigen recognized by autologous cytolytic T lymphocytes on a human renal carcinoma 总被引:7,自引:0,他引:7
Béatrice Gaugler Nathalie Brouwenstijn Valérie Vantomme Jean-Pierre Szikora Corry W. Van der Spek Jean-Jacques Patard Thierry Boon Peter Schrier Benoît J. Van den Eynde 《Immunogenetics》1996,44(5):323-330
Previous reports have described antigens that are recognized on human melanoma cells by autologous cytolytic T lymphocytes
(CTL). The genes coding for a number of these antigens have been identified. Here we report the cloning of a gene that codes
for an antigen recognized by autologous CTL on a human renal carcinoma cell line. This antigen is presented byHLA-B7 and is encoded by a new gene that we have namedRAGE1. No expression ofRAGE1 was found in normal tissues other than retina. RAGE1 expression was found in only one of 57 renal cell carcinoma samples,
and also in some sarcomas, infiltrating bladder carcinomas, and melanomas. This represents the first identification of an
antigen recognized by autologous CTL on a renal tumor. 相似文献
7.
Growth and fecundity of Daphnia after diapause and their impact on the development of a population 总被引:1,自引:1,他引:0
Laboratory and field investigations revealed that the life history traits of exephippial and parthenogenetic generations of Daphnia differ substantially. Daphniids hatching from resting eggs grow faster and their definitive body sizes are bigger than of hatchlings from subitaneous eggs. Size at maturity for exephippial animals is significantly larger. In spite of this, they mature a few days earlier than parthenogenetic females. In this study, the difference was 3–4 days for the laboratory experiments and 1–3 days for the field. Fecundity of the exephippial generation is markedly higher. Here, the clutch size for this generation was up to 3.5–4.0 times as large as for the parthenogenetic generation. Moreover, obtained results suggest that the relationship between clutch size and body length for both generations differ significantly.Estimates of the intrinsic rate of increase for field Daphnia populations demonstrated that life history traits of exephippial animals lead to a two or threefold higher rate of increase in the conditions of invertebrate predation pressure. Under moderate fish pressure, obtained r values for the daphniids hatching from resting eggs were larger than those from subitaneous. High growth rate of exephippial females is disadvantageous only under the conditions of severe pressure by fish. Obtained results suggest that hatchlings from diapausing eggs an acceleration of population increase by several times during the beginning of the development of a population with periodical re-establishment from resting eggs. 相似文献
8.
J. Del Val Pérez J. E. Fa J. Castroviejo F. J. Purroy 《Biodiversity and Conservation》1994,3(9):868-892
The status of 50 taxonomically unique bird taxa found in Bioko is described. A complete updated species list for birds in Bioko is also given. Notes on habitat occupied and altitudinal distribution of each species as well as information on their general abundance is also included. Species distributions may have been affected by habitat modifications brought about by humans but most taxonomically unique forms are found in the montane areas. Comparisons are made with the neighbouring Mount Cameroon area. 相似文献
9.
Martine Crasnier Valérie Dumay Antoine Danchin 《Molecular genetics and genomics : MGG》1994,243(4):409-416
In Escherichia coli, adenylate cyclase activity is regulated by phosphorylated EnzymeIIAGlc, a component of the phosphotransferase system for glucose transport. In strains deficient in EnzymeIIAGlc, CAMP levels are very low. Adenylate cyclase containing the D414N substitution produces a low level of cAMP and it has been proposed that D414 may be involved in the process leading to activation by EnzymeIIAGlc. In this work, spontaneous secondary mutants producing large amounts of cAMP in strains deficient in EnzymeIIAGlc were obtained. The secondary mutations were all deletions located in the cya gene around the D414N mutation, generating adenylate cyclases truncated at the carboxyl end. Among them, a 48 kDa protein (half the size of wild-type adenylate cyclase) was shown to produce ten times more cAMP than wild-type adenylate cyclase in strains deficient in EnzymeIIAGlc. In addition, this protein was not regulated in strains grown on glucose and diauxic growth was abolished. This allowed the definition of a catalytic domain that is not regulated by the phosphotransferase system and produces levels of cAMP similar to that of regulated wild-type adenylate cyclase in wild-type strains grown in the absence of glucose. Further analysis allowed the characterization of the COOH-terminal regulatory domain, which is proposed to be inhibitory to the activity of the catalytic domain. 相似文献
10.
John S. Beck Anne E. Kwitek Phillip H. Cogen Andrew K. Metzger Geoffrey M. Duyk Val C. Sheffield 《Human genetics》1993,91(1):25-30
p53 is a tumor suppressor gene located on 17p, a region of the human genome frequently deleted in tumors. Mutation of the p53 gene is an important step leading to development of many forms of human cancer. To simplify the analysis of tumors for p53 point mutations, we describe a GC-clamped denaturing gradient gel assay for detecting single-base substitutions within highly conserved regions of the p53 gene. This assay alows for efficient screening of tumors for single-base substitutions within the p53 gene and can be used to facilitate sequence analysis of p53 point mutations. 相似文献