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PubMed1995

Contingent drug tolerance: differential tolerance to the anticonvulsant, hypothermic, and ataxic effects of ethanol.

The kindled-convulsion model of epilepsy was used to study contingent tolerance to ethanol's (1.5 g/kg; IP) anticonvulsant, hypothermic, and ataxic effects in adult male rats. In the present experiments, three groups of amygdala-kindled rats received a series of bidaily (one every 48 h) convulsive stimulations: one group received ethanol 1 h before each stimulation; one group received ethanol 1 h after each stimulation; and another group served as the saline control. Tolerance to ethanol's anticonvulsant effect (Experiments 1 and 2) was greatest in those rats that received ethanol before each convulsive stimulation; whereas, tolerance to ethanol's hypothermic (Experiments 1 and 2) and ataxic (Experiments 2) effects developed in both groups that received ethanol. These results were predicted on the basis of the drug-effect theory of drug tolerance: the theory that functional drug tolerance is an adaptation to the disruptive effects of drugs on concurrent patterns of neural activity, not to drug exposure per se.

Amygdala↗
PubMed2026

Genomic exploration of Bacillus paralicheniformis TB197: an agrobiotechnological tool from the Sonoran Desert.

Climate change and the harmful effects of extensive agrochemical use for plant nutrition and pest control on soils, the environment, and human health are driving the search for sustainable alternatives that reduce their use while increasing plant resilience. In regenerative agriculture, microorganisms have become valuable tools, acting as biological control agents or biostimulants, such as plant growth-promoting rhizobacteria, and/or to enhance plant performance under abiotic stress. The genus Bacillus is well known for its versatile interactions with plants. Specifically, Bacillus paralicheniformis TB197 has demonstrated high efficacy in controlling phytopathogenic nematodes and adapting to diverse soil and crop conditions. Based on these traits, we explored the agricultural potential of this strain through genomic analysis and in vitro and in vivo assays. Gene analysis identified functions related to three main areas: (i) stress resistance and plant colonization, (ii) plant growth promotion, and (iii) phytopathogen control. The strain showed high tolerance to salinity and temperature, promoted plant growth, and exhibited strong antifungal activity. These findings highlight the potential of the TB197 strain as a promising candidate for developing next-generation bioinoculants.IMPORTANCEThe use of beneficial microorganisms is a pivotal strategy for mitigating the environmental impacts of intensive agriculture while preserving crop productivity. Bacillus paralicheniformis TB197 is a native desert soil bacterium with genetic traits associated with stress tolerance, plant growth promotion, and suppression of plant pathogens. In this study, we employed a multifaceted approach integrating genomic analysis and functional assays to demonstrate the strain's multifunctional potential as an agricultural bioinoculant. The results of the study demonstrate that a singular bacterial strain can integrate multiple beneficial functions relevant to sustainable agriculture. This work contributes to the field of applied microbiology by expanding the understanding of how environmentally adapted bacteria can serve as biological alternatives to chemical inputs in agroecosystems.

Bacillus↗
PubMed2000

Re-assignment of the Affinities of the Fossil Pollen Type Tricolpites trioblatus Mildenhall and Pocknall to Wilsonia (Convolvulaceae) and a reassessment of the ecological interpretations.

Tricolpites trioblatus Mildenhall and Pocknall was described from Upper Miocene-Pliocene sediments of New Zealand and attributed to the Hebe complex (Scrophulariaceae), which is common in the New Zealand vegetation, especially in montane and subalpine habitats. Pollen in Miocene-Pliocene sediments in central Australia is identified with T. trioblatus, and the depositional situations included shallow lakes, with fresh or brackish waters, sometimes becoming saline. The affinities of T. trioblatus are re-examined in the light of these disparate environments in Australia and New Zealand. It has been found that all the fossil grains examined are more comparable to pollen of Wilsonia, and perhaps Cressa (Convolvulaceae), than to those of the Hebe complex. Wilsonia and Cressa are found in salt marshes, hence affinities with them are ecologically more credible for central Australia. T. trioblatus is found in late Eocene sediments deposited under episodic marine transgressions; an environment likely to stimulate the evolution of new species tolerant to saline conditions.

Journal Article↗
PubMed2005

Influence of temperature, salinity and pH on the growth of environmental Aeromonas and Vibrio species isolated from Mai Po and the Inner Deep Bay Nature Reserve Ramsar Site of Hong Kong.

Four environmental bacterial isolates including Aeromonas hydrophila MP-3, A. salmonicida MP-4, Vibrio vulnificus MP-2 and V. cholerae MP-1 isolated from sediment and water of Mai Po Nature Reserve of Hong Kong were examined for their responses to temperature, pH and salinity under laboratory conditions in this study. V. cholerae MP-1 was found to resist vibriostatic agent O/129 at concentration of 10 microg/ml. In addition, bacterial growth under test conditions was measured and the results were fitted into the Gompertz model to obtain important parameters related to bacterial growth, lag time (lambda), specific growth rate (mu(m)), and maximum biomass (A) for comparison. V. cholerae MP-1 did not show any apparent growth at 15 degrees C, but was adapted to a much wider environmental pH from 5.2 to 9.2 for growth while V. vulnificus MP-2 was more sensitive to pH changes yielding the highest biomass at pH 6.2. A. salmonicida MP-4 was surprisingly tolerant to salinity as high as 60.0 per thousand NaCl and grew almost equally well as under conditions of other treatments. All four bacterial isolates showed a wide spectrum of plasticity to the environmental conditions and they pose a potential threat to public health and animal health.

Aeromonas↗
PubMed1993

Cerebral catecholamine depletion in mice withdrawn from repeated morphine treatment and development of tolerance to the enhancing effect of morphine on noradrenaline depletion.

The effect of repeated morphine administration on the alpha-methyl-rho-tyrosine (alpha M rho T)-induced depletion of catecholamines was investigated in various brain areas of mice withdrawn for 1, 2, 3 and 7 days from 5-day morphine treatment. In addition, to clarify the development of tolerance, the effect of acute morphine administration on alpha M rho T-induced depletion of catecholamines was studied in these selected brain areas of mice withdrawn from repeated morphine treatment. Dopamine depletion was significantly (P < .01) retarded in the striatum and "rest of forebrain + midbrain" of mice withdrawn for 1 day from morphine treatment. Withdrawal from morphine treatment did not alter alpha M rho T-induced noradrenaline depletion in the lower brain stem, rest of forebrain + midbrain or hypothalamus. The 10-mg/kg test dose of morphine significantly enhanced alpha M rho T-induced dopamine depletion in the rest of forebrain + midbrain of control mice withdrawn for 2 days, but did not clearly enhance it in mice withdrawn from morphine. The test dose significantly enhanced noradrenaline depletion in all selected brain areas of control mice withdrawn for 1 to 3 days from saline, but tolerance to the test dose developed in morphine-withdrawn mice. These results suggest that dopamine depletion is retarded in the striatum and rest of forebrain + midbrain of mice withdrawn for 1 day from repeated morphine treatment. However, noradrenaline depletion remains unchanged in all selected brain areas of mice withdrawn from morphine, and tolerance develops to the enhancing effect of morphine on the depletion of noradrenaline in mice withdrawn for 1 to 2 days from morphine.

Animals↗
PubMed1993

Postirradiation exposure to hypotonic saline shows normal damage processing in radiation-sensitive cell lines.

Three pairs of cell lines (one human and two Chinese hamster ovary (CHO) cell lines) each comprising a cell line with a normal radiation response and a radiation-sensitive mutant, were evaluated for recovery of potentially lethal damage (PLDR) and recovery of sublethal damage (SLDR). In all cases, the normal cell lines (GM1522, human; AA8-4 and K1, CHO) exhibited capacity for PLDR and SLDR was also normal in the two CHO lines. For the mutants (GM3395, human AT; V3 and 5-11, CHO) there was no ability for PLDR and SLDR was also absent in the two CHO cell lines. Postirradiation exposure to hypotonic NaCl solutions resulted in fixation of radiation damage in all the cell lines. This form of damage is repaired if left unperturbed after irradiation. This shows that cells have a large capacity for repair of this form of damage which accounts for much greater changes in survival than those observed in conventional PLDR experiments. These data show that the mutant cell lines retained their capacity to repair the damage which was susceptible to postirradiation fixation by anisotonic salt solutions. In addition, initial (i.e. preirradiation) DNA polymerase activities were measured in the four CHO cell lines; they were not correlated to radiation sensitivity.

Animals↗
PubMed1986

Naloxone and the ventilatory response to exercise in man.

Endogenous opiate peptides are known to exert a depressant action on ventilation (VE), and their plasma levels have been shown to be elevated during a variety of exercise protocols. We investigated whether they might modulate the control of the hyperpnea of short-term constant-load (CLE) and incremental (IE) cycle-ergometer exercise. Four healthy subjects performed CLE tests at ca. 80% of the anaerobic threshold (theta an) for 5 min following a period of unloaded pedaling, and IE tests (10 or 20 W min-1) to the limit of tolerance. Normal saline (3 ml) or the opiate antagonist naloxone (1.2 mg in 3 ml) were administered intravenously prior to each test. Naloxone elicited no discernible effect on VE, alveolar gas tensions, or heart rate throughout the entire range of work rates; neither were theta an nor the maximum work rate affected. It is concluded that, for short-term exercise ranging in intensity from moderate to severe, the role played by endogenous opiate peptides in the control of the exercise hyperpnea appears to be negligible in man.

Adult↗
PubMed1985

Evidence for the induction of two types of potentially lethal damage after exposure of plateau phase Chinese hamster V79 cells to gamma-rays.

The fixation of gamma-rays induced potentially damage (PLD) caused after treatment either with beta-araA or in medium made hypertonic by the addition of sodium chloride was studied in plateau phase Chinese hamster V79 cells. Treatment with beta-araA was found to affect a sector of PLD, the fixation of which specifically reduced the shoulder width of the survival curve. The effect was maximized when cell survival reached levels corresponding to an exponential line, with a slope similar to the final slope of the survival curve of untreated cells. This effect was achieved by a four hour treatment with beta-araA at concentrations above 150 microM. Longer treatment times or incubation at higher beta-araA concentrations did not significantly enhance the effect. Treatment in hypertonic medium, on the other hand, enhanced cell killing in a concentration dependent (NaCl-concentration) way and the survival reached values much lower than those corresponding to an exponential line. No indication for a plateau in the effect, indicating complete fixation of the sector of PLD that reacts sensitively to this treatment, was obtained. Both the slope and the shoulder width of the survival curve were affected, the slope first being increased after short treatment times (up to 10 min), followed by a decrease in the shoulder width after longer treatment times (longer than 10 min). Lesions fixed after treatment with beta-araA were repaired within four hours, whereas the repair of lesions fixed after treatment in hypertonic medium (460 mM NaCl, 30 min) appeared to be biphasic, with a fast component (completed in about one hour) correlated with a decrease in the slope and a slow component (completed in four hours) correlated with restoration of the shoulder width. Based on these results, we suggest that two types of PLD may be induced in plateau phase V79 cells after exposure to gamma-rays. One, the repair of which is completed within about one hour and which affects the slope of the survival curve, and a second, the repair of which takes place in a few hours and which specifically affects the survival curve shoulder width. The terms beta-PLD and alpha-PLD are suggested for the first and second component, respectively. Comparison of the repair rates of alpha-PLD as measured with the help of beta-araA and of sublethal damage as measured in split-dose experiments indicated that these two cellular repair processes have very similar kinetics when measured under the same experimental conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2004

Morphofunctional ontogeny of the urinary system of the European sea bass Dicentrarchus labrax.

European sea bass (Dicentrarchus labrax) are euryhaline fish that tolerate wide salinity fluctuations owing to several morphofunctional adaptations. Among the osmoregulatory sites (tegument, branchial chambers, digestive tract, urinary system), little is known about the kidney and the urinary bladder. The present study describes the ontogeny of the urinary system (kidney and urinary bladder) and focuses on the progressive expression of the Na(+)/K(+)-ATPase in the cells of these ion-transporting epithelia. A structural approach has shown that two pronephric urinary tubules are already present at hatching while the urinary bladder starts to differentiate. The glomus, an ultrafiltration site, occurs at day 5 (D5). The opisthonephros differentiates at D19/25 from the pronephric collecting tubules, then it rapidly grows longer and becomes folded. Na(+)/K(+)-ATPase immunolocalization and transmission electron microscopy show that ionocyte-like cells line the urinary tubules and the dorsal wall of the urinary bladder from D2/D5 on. Tubule ionocytes present a basolateral-localized fluorescence. Ionocytes of the collecting ducts and of the dorsal wall of the bladder present a fluorescence distributed in the whole cytoplasm. Fluorescence becomes stronger in later stages, suggesting a progressively increasing functionality of the urinary system in active ion transports. This observation is closely correlated with the ontogeny of osmoregulatory abilities. In juvenile and preadult fish kept in seawater, osmolality measurements demonstrate that urine is isotonic to blood. At low salinity, urine is hypotonic to blood in both stages. The capacity to produce hypotonic urine increases during ontogeny, a fact that suggests an increasing involvement of the urinary system in osmoregulation. The occurrence and the progressive functionality of the urinary system during the ontogeny, along with those of other osmoregulatory sites, are major adaptations allowing the sea bass to live in habitats of variable salinity such as lagoons and estuaries.

Aging↗
PubMed2006

Chromosome endoreduplication as a factor of salt adaptation in Sorghum bicolor.

Nuclear DNA amounts were measured by Feulgen cytophotometry in Sorghum bicolor cv. 610 plants early exposed to 150 mM NaCl, a treatment known to induce an increased tolerance to salinity in plants carrying this genotype. In salt-treated plants, the percentages of 8C, 16C, and 32C nuclei in roots in the primary state of growth were 21.9%, 13.3%, and 4.3%, respectively. By contrast, in nonsalinized plants, only 3.5% of the nuclei had an 8C content and no higher DNA contents were observed. The salt treatment induced chromosome endoreduplication during the differentiation of cells in the root cortex, where 41.2% of the cells displayed a DNA content higher than 4C (versus 1.3% in control plants). No enhancement of endopolyploidy was observed in cells of the root vascular cylinder or the leaves of the salt-treated plants. In another S. bicolor genotype (DK 34-Alabama), noncompetent for salt adaptation, the same NaCl treatment did not induce chromosome endoreduplication in root cortex cells. Endopolyploidy may be considered as a part of the adaptive response of S. bicolor competent genotypes to salinity.

Adaptation, Physiological↗
PubMed1993

Increased dose-rate effect in V79-multicellular aggregates (spheroids). Relation to initial DNA lesions and repair.

Survival of exponentially growing V79 monolayer cells was measured after irradiation at low dose-rate (up to 1.1 Gy/h) and at high dose-rate (2.5 Gy/min) and compared to corresponding survival data of V79 spheroid cells. The so-called contact effect, the increased radioresistance of cells irradiated in spheroids, was expressed to a greater extent with low dose-rate exposure. Lesion fixation by hypertonic treatment was more pronounced in spheroid versus monolayer cells and abolished the contact effect. The reduced radiosensitivity of V79 spheroid cells could not be related to a reduced number of initial DNA lesions or a higher capacity to rejoin DNA breaks (measured by neutral elution). These findings suggest that the ratio of lesion repair to fixation/misrepair may differ between cells from spheroids and monolayer culture thus influencing the response of cells to dose-rate changes differentially.

Animals↗
PubMed2005

Enhanced tolerance to salt stress in transgenic loblolly pine simultaneously expressing two genes encoding mannitol-1-phosphate dehydrogenase and glucitol-6-phosphate dehydrogenase.

A reproducible approach to improve salt tolerance of conifers has been established by using the technology of plant genetic transformation and using loblolly pine (Pinus taeda L.) as a model plant. Mature zygotic embryos of three genotypes of loblolly pine were infected with Agrobacterium tumefaciens strain LBA 4404 harboring the plasmid pBIGM which carrying two bacterial genes encoding the mannitol-1-phosphate dehydrogenase (Mt1D, EC 1.1.1.17) and glucitol-6-phosphate dehydrogenase (GutD) (EC 1.1.1.140), respectively. Transgenic plantlets were produced on selection medium containing 15 mg l(-1) kanamycin and confirmed by polymerase chain reaction (PCR) and Southern blot analysis of genomic DNA. The Mt1D and GutD genes were expressed and translated into functional enzymes that resulted in the synthesis and accumulation of mannitol and glucitol in transgenic plants. Salt tolerance assays demonstrated that transgenic plantlets producing mannitol and glucitol had an increased ability to tolerate high salinity. These results suggested that an efficient A. tumefaciens-mediated transformation protocol for stable integration of bacterial Mt1D and GutD genes into loblolly pine has been developed and this could be useful for the future studies on engineering breeding of conifers.

Agrobacterium tumefaciens↗
PubMed2002

Phenotypic and molecular characterization of chickpea rhizobia isolated from different areas of Morocco.

AIMS: To determine the biodiversity of rhizobial strains nodulating Cicer arietinum L. in representative soils from various areas of Morocco. METHODS AND RESULTS: Symbiotic traits, utilization of 49 carbohydrate sources, resistance to antibiotics and heavy metals, tolerance to salinity, to extreme temperatures and pH were studied as phenotypic markers. In addition, restriction fragment length polymorphism (RFLP) of PCR-amplified 16S rDNAs were compared with those of reference strains. Numerical analysis of the phenotypic characteristics showed that the 48 strains studied fell into three distinct groups. RFLP analysis of 16S rRNA genes revealed an additional heterogeneity and four ribotypes were identified. CONCLUSIONS: Chickpea rhizobia isolated from Moroccan soils are both phenotypically and genetically diverse. Most of these rhizobia belong to the Mesorhizobium genus. However, some strains originating from a particular soil appeared to have 16S rRNA genes similar to Sinorhizobium as well as very distinct auxanographic characteristics compared with Mesorhizo- bium isolates. SIGNIFICANCE AND IMPACT OF THE STUDY: A well characterized collection of chickpea-nodulating rhizobia in representative soils of Morocco has been generated, which can be used to develop efficient inoculants for this crop. This is the first report evidencing that chickpeas may be nodulated by bacteria from the Sinorhizobium genus.

Alphaproteobacteria↗
PubMed2006

Ectopic expression of ABSCISIC ACID 2/GLUCOSE INSENSITIVE 1 in Arabidopsis promotes seed dormancy and stress tolerance.

Abscisic acid (ABA) is an important phytohormone that plays a critical role in seed development, dormancy, and stress tolerance. 9-cis-Epoxycarotenoid dioxygenase is the key enzyme controlling ABA biosynthesis and stress tolerance. In this study, we investigated the effect of ectopic expression of another ABA biosynthesis gene, ABA2 (or GLUCOSE INSENSITIVE 1 [GIN1]) encoding a short-chain dehydrogenase/reductase in Arabidopsis (Arabidopsis thaliana). We show that ABA2-overexpressing transgenic plants with elevated ABA levels exhibited seed germination delay and more tolerance to salinity than wild type when grown on agar plates and/or in soil. However, the germination delay was abolished in transgenic plants showing ABA levels over 2-fold higher than that of wild type grown on 250 mm NaCl. The data suggest that there are distinct mechanisms underlying ABA-mediated inhibition of seed germination under diverse stress. The ABA-deficient mutant aba2, with a shorter primary root, can be restored to normal root growth by exogenous application of ABA, whereas transgenic plants overexpressing ABA2 showed normal root growth. The data reflect that the basal levels of ABA are essential for maintaining normal primary root elongation. Furthermore, analysis of ABA2 promoter activity with ABA2::beta-glucuronidase transgenic plants revealed that the promoter activity was enhanced by multiple prolonged stresses, such as drought, salinity, cold, and flooding, but not by short-term stress treatments. Coincidently, prolonged drought stress treatment led to the up-regulation of ABA biosynthetic and sugar-related genes. Thus, the data support ABA2 as a late expression gene that might have a fine-tuning function in mediating ABA biosynthesis through primary metabolic changes in response to stress.

Abscisic Acid↗
PubMed2001

beta-Alanine betaine synthesis in the Plumbaginaceae. Purification and characterization of a trifunctional, S-adenosyl-L-methionine-dependent N-methyltransferase from Limonium latifolium leaves.

beta-Alanine (beta-Ala) betaine is an osmoprotective compound accumulated by most members of the highly stress-tolerant family Plumbaginaceae. Its potential role in plant tolerance to salinity and hypoxia makes its synthetic pathway an interesting target for metabolic engineering. In the Plumbaginaceae, beta-Ala betaine is synthesized by S-adenosyl-L-methionine-dependent N-methylation of beta-Ala via N-methyl beta-Ala and N,N-dimethyl beta-Ala. It was not known how many N-methyltransferases (NMTases) participate in the three N-methylations of beta-Ala. An NMTase was purified about 1,890-fold, from Limonium latifolium leaves, using a protocol consisting of polyethylene glycol precipitation, heat treatment, anion-exchange chromatography, gel filtration, native polyacrylamide gel electrophoresis, and two substrate affinity chromatography steps. The purified NMTase was trifunctional, methylating beta-Ala, N-methyl beta-Ala, and N,N-dimethyl beta-Ala. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses indicated that the native NMTase is a dimer of 43-kD subunits. The NMTase had an apparent K(m) of 45 microM S-adenosyl-l-methionine and substrate inhibition was observed above 200 microM. The apparent K(m) values for the methyl acceptor substrates were 5.3, 5.7, and 5.9 mM for beta-Ala, N-methyl beta-Ala, and N,N-dimethyl beta-Ala, respectively. The NMTase had an isoelectric point of 5.15 and was reversibly inhibited by the thiol reagent p-hydroxymercuribenzoic acid.

Magnoliopsida↗
PubMed2006

Overexpression of putative topoisomerase 6 genes from rice confers stress tolerance in transgenic Arabidopsis plants.

DNA topoisomerase 6 (TOP6) belongs to a novel family of type II DNA topoisomerases present, other than in archaebacteria, only in plants. Here we report the isolation of full-length cDNAs encoding putative TOP6 subunits A and B from rice (Oryza sativa ssp. indica), preserving all the structural domains conserved among archaebacterial TOP6 homologs and eukaryotic meiotic recombination factor SPO11. OsTOP6A1 was predominantly expressed in prepollinated flowers. The transcript abundance of OsTOP6A2, OsTOP6A3 and OsTOP6B was also higher in prepollinated flowers and callus. The expression of OsTOP6A2, OsTOP6A3 and OsTOP6B was differentially regulated by the plant hormones, auxin, cytokinin, and abscisic acid. Yeast two-hybrid analysis revealed that the full-length OsTOP6B protein interacts with both OsTOP6A2 and OsTOP6A3, but not with OsTOP6A1. The nuclear localization of OsTOP6A3 and OsTOP6B was established by the transient expression of their beta-glucuronidase fusion proteins in onion epidermal cells. Overexpression of OsTOP6A3 and OsTOP6B in transgenic Arabidopsis plants conferred reduced sensitivity to the stress hormone, abscisic acid, and tolerance to high salinity and dehydration. Moreover, the stress tolerance coincided with enhanced induction of many stress-responsive genes in transgenic Arabidopsis plants. In addition, microarray analysis revealed that a large number of genes are expressed differentially in transgenic plants. Taken together, our results demonstrate that TOP6 genes play a crucial role in stress adaptation of plants by altering gene expression.

Arabidopsis↗