Exogenous Ethanol Research Articles

Physiological model of the stimulative effects of alcohol in low-to-moderate doses.

A physiological model of alcohol use is proposed, based on the observation that ethanol is a natural intracellular metabolite. It is suggested that ethanol synthesis is an intermediate step in the metabolic pathway of elimination of the excess of energy-releasing substrates from mitochondria and the cytosol when the cell does not require additional energy. The process is first of all important for elimination of acetyl-CoA from mitochondria. Ingested alcohol passes across plasma and mitochondrial membranes by diffusion and follows the endogenous ethanol pathway but in the reverse direction. This pathway is used when the cell needs additional energy. In that case, exogenous ethanol supplies the respiratory chain with electrons via NADH on the path of oxidation to acetaldehyde and then to acetate by alcohol and aldehyde dehydrogenases. After conversion to acetyl-CoA, it goes into the citrate cycle and is thus used for energy production entirely. If citrate cycle activity is decreased constitutionally, acetyl-CoA enters into citrate cycle too slowly and energy deficit arises, ethanol compensates for the energy deficit. Acetate then diffuses out of mitochondria. The less energy production in mitochondria, the more the cell is ready to accept alcohol as an energy source. Citrate cycle activity can be depressed as a result of single-nucleotide polymorphisms of genes controlling some enzymes involved in the cycle, which influences the alcohol requirement.

Ilex paraguariensis cell suspension culture characterization and response against ethanol

Cell suspension cultures of Ilex paraguariensis, a South American native tree known as the mate plant, were initiated in order to investigate plant defense. Cultures were characterized for their cell growth, chemical composition and sugar consumption. The present work quantified some effects of salicylic acid, methyl jasmonate, cellulase and ethanol on cell growth and sugar metabolism. Results suggest that salicylic acid and methyl jasmonate play a role in Ilex paraguariensis response against exogenous ethanol by enhancing its glucosylation by 50% if compared to addition of ethanol alone.

Changes in enzymatic activity and behavioural responses during Drosophila melanogaster development: effects of environmental ethanol and acetic acid

Summary The effects of exogenous ethanol and acetic acid were compared in a highly tolerant French population and in a very sensitive Congolese population of Drosophila melanogaster. Changes during development stages were investigated for ADH activity, survival and for two behavioural traits: pupation site choice and olfactory behavior. The French population presented a higher ADH activity and a more important acceptance of alcoholic substrates than the African one. For both populations, enzyme activity assays showed that, after exposure to ethanol, the ADH level increased considerably in larvae while it did not change in adults. Such an increase in larval ADH activity on ethanol-containing medium was not observed when the medium was enriched with acetic acid. These results indicated that the larval period is the most sensitive in the life history of D. melanogaster. This also appeared in survival studies since a more important decrease was noted in the percentage of larvae-to-pupae survival than pupa-to-adult one. Besides, our data showed a strong parallelism between ADH activity and larval behaviour (olfactory response and pupation site choice) since larvae accept or avoid resources according to their capacity to use them. Contrarily, adult olfactory response did not correlate with their ADH activity. Thus, reduction in avoidance to chemicals was observed in adults even if their level of enzymatic activity remains constant in this period. These observations taken together suggested that ADH activity was not primarily implicated in olfactory behaviour. Several other genetic or physiological processes could also be involved in behavioural responses.

Effects of ethanol on growth of rice seedlings

Effects of ethanol, the end product of ethanolic fermentation, on the growth of rice (Oryza sativa L.) seedlings were determined as a means of evaluating growth responses under anoxia. The ethanol concentrations in roots and coleoptiles of the seedlings subjected to 48 h-anoxia, and in their culture medium were 23 and 32 µmol g−1 fresh weight, and 19 µmol ml−1, respectively. The growth of the roots and coleoptiles of the seedlings was restricted by exogenous ethanol at concentrations above 50 mM and 100 mM, respectively, suggesting that the roots are more sensitive to ethanol than the coleoptiles.

Loss of expression of alcohol dehydrogenase in adult males of Drosophila pachea.

Drosophila pachea, a member of the nannoptera species group, is a cactophilic species endemic to the Sonoran Desert of North America (Heed, 1978). Drosophila pachea breeds and feeds in necrotic tissue of a specific host cactus, senita (Lophocereus schottii), which produces phytosterols necessary for its normal development (Heed and Kircher, 1965; Fogleman et al.,1986). During the course of a study on the population genetics of Sonoran Desert Drosophila we noticed that the enzyme alcohol dehydrogenase (ADH; EC 1.1.1.1) was not expressed in mature adult males of D. pachea, although high activity was seen in females. The pattern was consistent in flies collected from widely separated localities. In the present Note we describe the relative expression of ADH in different life history stages of D. pachea and the time course of suppression of enzyme activity in adult males. We also show that the sex-specific suppression in ADH activity is not a characteristic of the other members of the nannoptera species group, D. nannoptera, D. acanthoptera, and D. wassermani. Finally, we demonstrate that expression of ADH activity in adult females of D. pachea is not localized in the ovaries and, in addition, show that enzyme activity in adult males can be induced with short-term exposure to exogenous ethanol.

Ethanol metabolism in calluses of several selected plant species on two typical plant-growth-regulator balanced media

For investigation on the characteristics of ethanol metabolism in tissues of different plant species, calluses from eight selected plant species were cultured on medium supplemented with ethanol in tightly sealed culture flasks. Changes of the ethanol level were detected by gas chromatography. During the culture period, the calluses of tobacco, potato and petunia were, able to catabolize exogenous ethanol, resulting in the prominent decline of the ethanol level in the medium. The calluses of melon and peanut were also able to catabolize thanol but with lower efficiency. The other three calluses of carrot, soybean and rice did not catabolize ethanol but instead produced small to large amount of ethanol, resulting in the increase of the ethanol level in the media. It was also found that changing the balance between auxin and cytokinin could influence only the ethanol metabolism efficiency but could not change the metabolism patterns on ethanol of the cultured calluses. It can be concluded that, ethanol metabolism pattern of calluses in cultures is an innate physiological characteristic of the respective plant species.

Evolution of Volatiles During Seed Aging

ABSTRACT Acetaldehyde, ethanol and methanol evolution was studied from soybean (Glycine max L. Merrill) and snap bean (Phaseolus vulgaris L.) seeds held at 12, 53 or 75% RH. Exogenous acetaldehyde or ethanol was applied in a gaseous phase at known concentrations to seeds in a closed container. The volatile compounds evolved were quantified by gas chromatography from the headspace or thermally derived from seed tissues. Exogenous application of acetaldehyde or ethanol resulted in enhanced ethanol or acetaldehyde evolution, respectively, at all relative humidity levels tested. The greatest conversion of acetaldehyde to ethanol was at 75% RH, while maximal conversion of ethanol to acetaldehyde occurred at 53% RH. Ethanol evolution was greater than acetaldehyde evolution from treated seeds, supporting the contention that alcohol dehydrogenase (ADH) was responsible for the conversion, and that ADH favors ethanol production. Methanol evolution was enhanced only in the headspace by application of either acetal-d...

Alcohol dehydrogenase activity in cultured cells from different tobacco (Nicotiana tabacum L.) varieties

The activity of alcohol dehydrogenase (ADH) in cultured cells of various tobacco was determined. It was found that significant differences existed in cells of different varieties cultured under normal conditions and as well after treated with exogenous ethanol. The ADH activity had positive relation with the ability of the cells to catabolize exogenous ethanol, indicating that the main function of the ADH in tobacco cells was in the direction of converting ethanol to acetaldehyde.

Combined effects of ethanol, high homogenization pressure, and temperature on cell fatty acid composition in Saccharomyces cerevisiae.

The specific aims of this research were to evaluate the combined effects of ethanol and high-pressure homogenization at different temperatures on cell viability in Saccharomyces cerevisiae and to study the induced modification of fatty acid composition. The decrease in viability was weak at 10 degrees C while a homogenization pressure over 1000 bar (1 bar = 100 kPa) induced a significant reduction in viability when the cells were incubated at 20 and 30 degrees C. The cell tolerance to pressure decreased with an increase in ethanol concentration and temperature. Ethanol, particularly intracellular ethanol accumulated by S. cerevisiae, played an important role in the response to homogenization pressure and in modification of the cell fatty acid composition. In fact, an unusually elevated accumulation of ethyl esters in lipid extracts of yeast cells subjected to high homogenization pressure, especially in the presence of exogenous ethanol and at 30 degrees C, was observed. Moreover, only unsaturated and traces of short chain fatty acids were esterified with ethanol.

Acetaldehyde induces histamine release from purified rat peritoneal mast cells

Acetaldehyde is a widely distributed compound in the human environment and it is also formed in the human body from various endogenous and exogenous sources, exogenous ethanol being the most important one. Many alcohol-associated hypersensitivity reactions, e.g. Oriental flushing reaction, appear to be attributable to acetaldehyde rather than to ethanol itself. The pathogenetic mechanism behind such hypersensitivity reactions has been suggested to be histamine release from mast cells or blood basophils. However, the direct effects of acetaldehyde on mast cells, the main source of histamine in a mammalian body, have not been studied. The aim of the present study was, thus, to evaluate whether physiological concentrations of acetaldehyde could release histamine from purified rat peritoneal mast cells. The effects of ethanol were studied similarly. The results show that acetaldehyde, already at a concentration of 50 μM, significantly increases the release of histamine from mast cells. Ethanol has a similar effect but only at molar concentrations. These results indicate that acetaldehyde may contribute to the development of various hypersensitivity reactions by directly increasing histamine release from mast cells.

Acetaldehyde alters proliferation, differentiation and adhesion properties of human colon adenocarcinoma cell line Caco-2.

Studies with experimental animals indicate that acetaldehyde, the first metabolite of ethanol that is microbially formed in the colonic lumen, may play a role in ethanol-associated colorectal co-carcinogenesis. Although intracoIonic acetaldehyde concentrations are highest during the metabolism of exogenous ethanol, some individuals may also possess marked amounts of endogenous acetaldehyde. Since no information is available concerning the possible effects of acetaldehyde on human colonic epithelial cells, this study was aimed to assess whether this compound, either alone or in combination with ethanol, affects such properties of human neoplastic colonocytes that are considered relevant with regard to cancer development. Human colon adenocarcinoma cell line Caco-2 was used as a model of transformed colonocytes, and effects of acetaldehyde and/or ethanol on the proliferation and differentiation of these cells as well as on their adhesion to collagens I and IV, the most important extracellular matrix proteins in the colon, were studied. The results of this study show that acetaldehyde markedly affects the phenotype of Caco-2 cells without having direct cytotoxic effects. Like many carcinogens, it was found to have a dual effect on cell proliferation rate, acute exposure being inhibitory and chronic exposure stimulating. Acetaldehyde also considerably decreased both sucrase activity and nuclear content of protein kinase A catalytic subunit in Caco-2 cells, which indicate that the differentiation of the cells was disturbed. Moreover, the adhesion of Caco-2 cells to collagens I and IV was dose-dependently reduced by acetaldehyde treatment. All these changes, i.e. enhanced cell proliferation rate (by chronic treatment), decreased differentiation, and reduced adhesion to extracellular matrix proteins, would in vivo predict more aggressive and invasive tumour behaviour. The possibility that colonic intraluminal acetaldehyde, either ethanol-derived or endogenous, might enhance the development of colorectal tumours should therefore be considered.

Prostaglandin E2 inhibition of fetal breathing movements is not sustained during prolonged reduced uterine blood flow in sheep

Fetal breathing movements (FBM) are inhibited by both exogenous prostaglandin E2 (PGE2) and ethanol in sheep. Maternal ethanol exposure in late-gestation sheep also increases fetal [PGE2]. However, during prolonged reduced uterine blood flow (RUBF) when [PGE2] in fetal plasma is already elevated, FBM are not inhibited by ethanol. These experiments were designed, therefore, to test the hypothesis that the FBM response to PGE2 is also diminished during RUBF. PGE2 (594 ± 19 ng·min-1·kg-1 fetal body weight) was infused for 6 h into the jugular vein of RUBF (PO2 = 14 ± 1 mmHg (1 mmHg = 133.3 Pa); n = 7) and control (PO2 = 22 ± 1 mmHg (p < 0.01); n = 7) ovine fetuses, and the effect on FBM, electrocortical (ECoG), and electroocular activities was determined. The infusion of PGE2 increased plasma [PGE2] from 881 ± 162 to 1189 ± 114 pg·mL-1 in RUBF fetuses and from 334 ± 72 to 616 ± 118 pg·mL-1 (p < 0.05) in control fetuses. FBM were initially inhibited by PGE2 from 22.5 ± 9.4 and 17.9 ± 6.5% of the time to 6.9 ± 2.4 and 0.5 ± 0.4% (p < 0.01) in RUBF and control fetuses, respectively. FBM remained inhibited in control fetuses throughout the infusion but returned to baseline incidence in RUBF fetuses in the last 2 h of the infusion. These results are consistent with the hypothesis that one component of the adaptative mechanisms of the fetus to prolonged RUBF is an altered response of FBM to exogenous PGE2. We speculate that the lack of a sustained inhibition in FBM during RUBF with infusion of PGE2 may be a result of an alteration in brainstem receptor function or number or local PGE2 removal.Key words: fetal breathing movements, prostaglandin E2, hypoxia, reduced uterine blood flow, ethanol, fetal behaviour.

Interaction between the Adh and Odh loci in response to ethanol in Drosophila melanogaster.

Six Drosophila melanogaster strains were constructed from two isofemale lines. The strains had four allele combinations at the alcohol dehydrogenase (Adh) and octanol dehydrogenase (Odh) loci, while all alpha-glycerophosphate dehydrogenase (alpha Gpdh), malate dehydrogenase (Mdh), and aldehyde oxidase (Aldox) alleles were identical. Second-instar and early and late third-instar larvae were exposed to different concentrations of ethanol (0, 5, and 7.5%) and 3 days later fresh weights and the activities of ADH, ODH, alpha GPDH, and MDH were measured. Activity differences were observed between the two Adh genotypes: ADHF allozyme had considerably higher activity than ADHS. Exogenous ethanol resulted in the highest increase in ADH activity in the second- and early third-instar stages. This ADH induction depended on the allele combination at the Adh and Odh loci; e.g., in the strain having the AdhS-OdhS allele combination, increased ADH activity was observed only after exposure to 7.5% ethanol. ODH activities differed according to the Odh genotypes, in that the ODHS allozyme had a higher activity than ODHF. ODH activities did not appreciably respond to different ethanol treatments. All six strains had identical alleles at the Mdh and alpha Gpdh loci, but nevertheless, the responses of these enzymes to ethanol depended on the allele combinations at the Adh and Odh loci. alpha GPDH activity followed that of ADH in all experiments. MDH activities were not influenced by exogenous ethanol in the strains homozygous for the AdhS allele. In AdhF strains, however, exposure to 7.5% ethanol resulted in a considerable decrease in MDH activity in the second-instar larvae. Correlations among the response variables showed that ODH activities were strongly associated with fresh weight and the activities of all other enzymes, except for ADH. ADH activity, however, showed a significant correlation only with alpha GPDH activity throughout the larval life. Both MDH and ODH activities were found to be in strong negative correlation with ADH activity in the second-instar larvae. At this most sensitive life stage, the metabolic response to ethanol is highly correlated.

Prostaglandin E2 inhibition of fetal breathing movements is not sustained during prolonged reduced uterine blood flow in sheep.

Fetal breathing movements (FBM) are inhibited by both exogenous prostaglandin E2 (PGE2) and ethanol in sheep. Maternal ethanol exposure in late-gestation sheep also increases fetal [PGE2]. However, during prolonged reduced uterine blood flow (RUBF) when [PGE2] in fetal plasma is already elevated, FBM are not inhibited by ethanol. These experiments were designed, therefore, to test the hypothesis that the FBM response to PGE2 is also diminished during RUBF. PGE2 (594+/-19 ng.min(-1).kg(-1) fetal body weight) was infused for 6 h into the jugular vein of RUBF (PO2 = 14+/-1 mmHg (1 mmHg = 133.3 Pa); n = 7) and control (PO2 = 22+/-1 mmHg (p < 0.01); n = 7) ovine fetuses, and the effect on FBM, electrocortical (ECoG), and electroocular activities was determined. The infusion of PGE2 increased plasma [PGE2] from 881+/-162 to 1189+/-114 pg.mL(-1) in RUBF fetuses and from 334+/-72 to 616+/-118 pg.mL(-1) (p < 0.05) in control fetuses. FBM were initially inhibited by PGE2 from 22.5+/-9.4 and 17.9+/-6.5% of the time to 6.9+/-2.4 and 0.5+/-0.4% (p < 0.01) in RUBF and control fetuses, respectively. FBM remained inhibited in control fetuses throughout the infusion but returned to baseline incidence in RUBF fetuses in the last 2 h of the infusion. These results are consistent with the hypothesis that one component of the adaptative mechanisms of the fetus to prolonged RUBF is an altered response of FBM to exogenous PGE2. We speculate that the lack of a sustained inhibition in FBM during RUBF with infusion of PGE2 may be a result of an alteration in brainstem receptor function or number or local PGE2 removal.

Experimental investigation and modeling of oscillatory behavior in the continuous culture ofZymomonas mobilis

The mechanism causing oscillation in continuous ethanol fermentation by Zymomonas mobilis under certain operating conditions has been examined. A new term, "dynamic specific growth rate," which considers inhibitory culture conditions in the recent past affecting subsequent cell behavior, is proposed in this article. Based on this concept, a model was formulated to simulate the oscillatory behavior in continuous fermentation of Zymomonas mobilis. Forced oscillation fermentation experiments, in which exogenous ethanol was added at a controlled rate to generate oscillatory behavior, were performed in order to obtain estimates for the model parameters and to validate the proposed model. In addition, data from a literature example of a sustained oscillation were analyzed by means of the model, and excellent agreement between the model simulation and experimental results was obtained. The lag in the cells' response to a changing environment, i.e., ethanol concentration change rate experienced by the cells, was shown to be the major factor contributing to the oscillatory behavior in continuous fermentation of Zymomonas mobilis under certain operating conditions.

Cross-talk Between Receptor-mediated Phospholipase C-βand D via Protein Kinase C as Intracellular Signal Possibly Leading to Hypertrophy in Serum-free Cultured Cardiomyocytes

Phospholipase C-β(PLC-β) signalling via protein kinase C (PKC) has been recognized as a major route by which stimuli such asα1-adrenergic agonists, endothelin-1 (ET-1) and angiotensin II (Ang II) induce hypertrophy of myocytes. The goal of this study was to evaluate the role of phospholipase D (PLD) in contributing to the formation of the PKC activator 1,2-diacylglycerol (1,2-DAG) and to study the mechanism(s) of PLD activation by agonists. Stimulation of serum-free cultured neonatal rat cardiomyocytes with ET-1 (10−8m), phenylephrine (PHE, 10−5m) or Ang II (10−7m) resulted in a rapid (0–10 min) activation of PLC-βto an extent (ET-1>PHE>Ang II) that correlated with the magnitude of stimulation of protein synthesis ([3H]leucine incorporation into protein) measured after 24 h. Phorbol 12-myristate 13-acetate (PMA, 10−6m) and ET-1 were equipotent in stimulating protein synthesis. ET-1 and PMA, but not PHE and Ang II stimulated [3H]choline formation from labelled PtdCho after a lag-phase of about 10 min. That this [3H]choline formation was due to the action of PLD was confirmed by measurement of phosphatidylgroup-transfer from cellular [14C]palmitoyl-phosphatidylcholine to exogenous ethanol. ET-1 and PHE, to much lesser extent, produced a rapid (0–5 min) translocation of PKC-εimmunoreactivity from the cytosol to the membrane fraction, whereas no intracellular redistribution of PKC-α, -δand -ξimmunoreactivities was observed. PMA caused translocation of PKC-α, PKC-εas well as PKC-δ. Cellular redistribution of PKC activity measured by [32P]-incorporation into histone III-S was not observed with ET-1 and PHE, but only with PMA stimulation. Down-regulation of PKC isozymes by 24 h pretreatment of cells with PMA or blockade of PKC by chelerythrine (10−4m) inhibited ET-1 and PMA stimulated [3H]choline production. Staurosporine (10−6m) had, however, no effect. In conclusion, the results indicate that in serum-free cultured cardiomyocytes, ET-1 initially activates PLC-βand after a lag-phase PLD, whereas PHE and Ang II activate only PLC-β. PLC-βstimulated by ET-1, may cross-talk with PLD via translocation of PKC-ε. These signals are possibly linked to the hypertrophic response.

Differences in environmental temperature, ethanol and sucrose associated with enzyme activity and weight changes in Drosophila melanogaster

Activity changes of three enzymes (ADH, ODH and AOX) of Drosophila melanogaster were followed under different environmental conditions. The influences of ethanol, starvation (no carbohydrates in the medium) and ethanol stress during starvation were studied at both 18 and 26°C. Two strains that were monomorphic for different alleles at the Odh and Aldox loci but otherwise identical were used. The investigated environmental conditions affected ADH induction by exogenous ethanol differently in the two strains. The different allozymes of ODH and AOX also responded differently to the treatments. We observed that the sucrose content of the medium on which ethanol exposure took place and the temperature strongly affected the responses within any single strain. Correlations were estimated among the three enzymes in the larval and adult stages of each strain separately. At both temperatures, differences between strains were observed in the patterns of associations of the response variables, in the larval, but not in the adult stages.

Application of the Melle-Boinot process to the fermentation of xylose by Pachysolen tannophilus

The Melle-Boinot process (cell-recycle batch fermentation) was applied to the fermentation of xylose by two strains of the yeast Pachysolen tannophilus for periods of 31 days. This resulted in a significant increase in the ethanol yield and productivity from xylose by P. tannophilus NCYC 614 but not by strain CBS 4045. Analysis of cells of strain NCYC 614 at the end of the process revealed an increased ability to tolerate exogenous ethanol, a characteristic that was lost in the absence of selection pressure. It is postulated that the increased yield of ethanol from xylose by P. tannophilus NCYC 614 is a product of enhanced ethanol tolerance together with increased efficiency of the fermentation process associated with the Melle-Boinot system.

Application of the Melle-Boinot process to the fermentation of xylose by Pachysolen tannophilus

The Melle-Boinot process (cell-recycle batch fermentation) was applied to the fermentation of xylose by two strains of the yeast Pachysolen tannophilus for periods of 31 days. This resulted in a significant increase in the ethanol yield and productivity from xylose by P. tannophilus NCYC 614 but not by strain CBS 4045. Analysis of cells of strain NCYC 614 at the end of the process revealed an increased ability to tolerate exogenous ethanol, a characteristic that was lost in the absence of selection pressure. It is postulated that the increased yield of ethanol from xylose by P. tannophilus NCYC 614 is a product of enhanced ethanol tolerance together with increased efficiency of the fermentation process associated with the Melle-Boinot system.

Identification of a defect in the phospholipase D/diacylglycerol pathway in cellular senescence

Normal cells become senescent in culture after a limited number of population doublings becoming unable to respond to mitogens. This raises the possibility of defects in mitogenic signaling pathways in cellular senescence. In contrast to young human diploid fibroblasts (HDF), their senescent counterparts failed to undergo protein kinase C translocation in response to serum stimulation. On the other hand, phorbol 12-myristate 13-acetate was equally active in inducing protein kinase C translocation in young and senescent HDF. This suggested a defect in generation of the endogenous activator of protein kinase C, diacylglycerol. Stimulation of young HDF with serum resulted in 3-4-fold generation of diacylglycerol (DAG). In contrast, senescent cells displayed insignificant DAG formation in response to serum. The mechanism of DAG generation was investigated next. In young HDF, serum induced a 5-fold activation of the phospholipase D (PLD) pathway as measured by the incorporation of exogenous ethanol into phosphatidylethanol, which is a measure of the transphosphatidylation reaction of PLD. In contrast, PLD in senescent cells was not activated by serum. Since senescent cells demonstrate significant elevations in the level of endogenous ceramide, the impact of ceramide on the PLD/DAG pathway was also investigated. A soluble analog of ceramide, C6-ceramide, was found to inhibit serum-stimulated DAG accumulation and PLD activation in young cells. These data demonstrate for the first time a defect in PLD activation in cellular senescence and suggest that ceramide may be responsible for the inhibition of this pathway.