Erk1/2 signaling mediates the HGF-induced protection against ethanol and acetaldehyde-induced toxicity in the pancreatic RINm5F cell line

Alcohol-induced pancreas damage remains as one of the main risk factors for pancreatitis development. This disorder is poorly understood, particularly the effect of acetaldehyde, the primary alcohol metabolite, in the endocrine pancreas. Hepatocyte growth factor (HGF) is a protective protein in many tissues, displaying antioxidant, antiapoptotic, and proliferative responses. In the present work, we were focused on characterizing the response induced by HGF and its protective mechanism in the RINm5F pancreatic cell line treated with ethanol and acetaldehyde. RINm5F cells were treated with ethanol or acetaldehyde for 12 h in the presence or not of HGF (50 ng/ml). Cells under HGF treatment decreased the content of reactive oxygen species and lipid peroxidation induced by both toxics, improving cell viability. This effect was correlated to an improvement in insulin expression impaired by ethanol and acetaldehyde. Using a specific inhibitor of Erk1/2 abrogated the effects elicited by the growth factor. In conclusion, the work provides mechanistic evidence of the HGF-induced-protective response to the alcohol-induced damage in the main cellular component of the endocrine pancreas.     

Isolation of anti-fungal phenolic compounds from petioles of two Hevea brasiliensis (rubber) genotypes and their effect on Phytophthora meadii

Phenolic compounds were present in greater amounts in non‐infected petioles of genotypes of Hevea brasiliensis that are resistant to Phytophthora leaf disease than in genotypes that are susceptible. Phenolic compounds extracted from petioles of either susceptible (PB86) or resistant (RRIC100) genotypes, before or after infection with Phytophthora meadii, had anti‐fungal properties. Artificially infected petioles of PB86 had phenolic acids, triterpenoids or flavonoids, whereas healthy petioles contained only triterpenoids or flavonoids. However, healthy or infected petioles of RRIC100 contained only trace amounts of the above compounds and of vanillin (3‐methoxy‐4‐hydroxybenzaldehyde). Vanillin and umbelliferone (7‐hydroxycoumarin) were shown to suppress zoospore germination of P. meadii on glass slides and to inhibit its growth in pea broth and V‐8 juice agar. Vanillin was slightly more active than umbelliferone. Resistance of RRIC100 to Phytophthora was suspected as being related to the polymerisation of phenolic compounds to form lignin, which may suppress further spread of the pathogen's mycelium into healthy tissues. Formation of lignin from phenolic aldehydes as a barrier to disease spread may be a critical factor in resistance.     

Improved ethanol tolerance and production in strains of Clostridium thermocellum

Two Clostridium thermocellum strains were improved for ethanol tolerance, to 5% (v/v), by gradual adaptation and mutation. The best mutant gave an ethanol yield of 0.37 g/g substrate, with a growth yield 1.5 times more than its parent. Accumulation of acids and reducing sugars by the mutant strain with 5% (v/v) ethanol was lower than that of the parent strain with 1.5% (v/v) ethanol.     

Increase in cellular pool of low-molecular-weight iron during ethanol metabolism in rat hepatocyte cultures

Ethanol-induced lipid peroxidation was studied in primary rat hepatocyte cultures supplemented with ethanol at the concentration of 50 mM. Lipid peroxidation was assessed by two indices: (1) conjugated dienes by second-derivative UV spectroscopy in lipid extract of hepatocytes (intracellular content), and (2) free malondialdehyde (MDA) by HPLC-UV detection and quantitation for the incubation medium (extracellular content). In cultures supplemented with ethanol, free MDA increased significantly in culture media, whereas no elevation of conjugated diene level was observed in the corresponding hepatocytes. The cellular pool of low-mol-wt (LMW) iron was also evaluated in the hepatocytes using an electron spin resonance procedure. An early increase of intracellular LMW iron (≤1 hr) was observed in ethanol-supplemented cultures; it was inhibited by 4-methylpyrazole, an inhibitor of alcohol dehydrogenase, whereas α-tocopherol, which prevented lipid peroxidation, did not inhibit the increase of LMW iron. Therefore, the LMW iron elevation was the result of ethanol metabolism and was not secondarily induced by lipid hydroperoxides. Thus, ethanol caused lipid peroxidation in rat hepatocytes as shown by the increase of free MDA, although no conjugated diene elevation was detected. During ethanol metabolism, an increase in cellular LMW iron was observed that could enhance conjugated diene degradation.     

Comparison of carbohydrate utilization and energy charge in the yellow flag iris (Iris pseudacorus) and garden iris (Iris germanica) under anoxia

Carbohydrate and energy metabolism of the flooding- and anoxia-tolerant Iris pseudacorus and the intolerant Iris germanica rhizomes were investigated under experimental anoxic conditions. Rhizomes of I. pseudacorus and I. Germanica were incubated in the absence of oxygen from 0 to 60 and 16 days, respectively. Amounts of glucose, total reducing sugars and non-reducing sugars (starch, fructan and oligosaccharides) in the rhizomes were measured. Ethanol concentration and adenylate energy charge were determined enzymatically. Glucose content of I. pseudacorus rhizomes decreased gradually during the first 30 days under anoxia and then increased at the same time as adenylate energy charge values started to decline. In I. germanica rhizomes the changes were more dramatic and the time scale was much shorter than in I. pseudacorus but the changes were similar. Non-reducing sugar content of I. pseudacorus rhizomes decreased rapidly during the first 15 days under oxygen deprivation and then increased again, to near starting levels at 35 days. In I. germanica the amount of non-reducing sugars decreased gradually during the anoxic incubation. Under aerobic control conditions, adenylate energy charge (AEC) of I. pseudacorus and I. germanica rhizome tissue was 0.87±0.01 and 0.81±0.01, respectively. In I. pseudacorus AEC remained high until 30 days under anoxia. In contrast, the energy charge of I. germanica rhizome tissue remained above 0.6 for 4 days only. Large amounts of ethanol were found in anoxic rhizome tissues of I. pseudacorus (up to 0.21 M ) and I. germanica (0.06 M ) after 45 days and 8 days, respectively. The results are discussed in relation to flooding tolerance of these species.     

The influence of macrophytes on a phytoplankton community in experimental conditions

The impact of submerged macrophytes or their extracts on planktonic algae was studied under experimental conditions. Live Ceratophyllum demersum L., its extract, and extracts of four other plant species induced modifications in the phytoplankton dominance structure. These modifications were: a decline in the number of Oscillatoria limnetica Lemm., which was the most numerous cyanobacterian species, and a decline in biomass and percentage contribution of all cyanobacteria to total algal biomass. This was accompanied by an increase in biomass and percentage contribution of green algae, especially Chlorella sp. and Chlamydomonas sp. Also, there was an increase in biomass and percentage contribution of nanoplankton (under 50 µm) to total phytoplankton biomass.The isolation of planktonic algae from direct influence of C. demersum by means of dialysis membranes caused an increase in number, biomass and percentage contribution of cyanobacteria. Release of organic compounds of over 3000 daltons by macrophytes apparently contributed to a decline of cyanobacteria by changing the phytoplankton dominance structure.     

Ethanol utilization regulatory protein: profile alignments give no evidence of origin through aldehyde and alcohol dehydrogenase gene fusion.

The suggestion that the ethanol regulatory protein from Aspergillus has its evolutionary origin in a gene fusion between aldehyde and alcohol dehydrogenase genes (Hawkins AR, Lamb HK, Radford A, Moore JD, 1994, Gene 146:145-158) has been tested by profile analysis with aldehyde and alcohol dehydrogenase family profiles. We show that the degree and kind of similarity observed between these profiles and the ethanol regulatory protein sequence is that expected from random sequences of the same composition. This level of similarity fails to support the suggested gene fusion.     

The fluidity of plasma membranes from ethanol-treated rat liver

Summary Male Wistar rats were maintained for 35–40 days on a liquid diet containing 36% of calories as ethanol. Ethanol was replaced by carbohydrates in the isocaloric diet fed to control animals. The effect of ethanol consumption has been studied on the fluorescence polarization of rat liver plasma membranes and artificial lipid vesicles and on the lipid composition of the membranes. Fluorescence polarization in both membranes and vesicles was determined using DPH and TMA-DPH as fluorescence markers; from these data, the polarization term (r_o/r–1)^–1 and flow activation energy (E) were calculated. The ethanol consumption induces a more fluid environment within the membrane core of liver plasma membranes; the ethanol-fed rat membranes are more resistant to the in vitro effect of ethanol disordering the membrane structure. Vesicles obtained with lipids from either control membranes or ethanol-fed rat membranes were treated with ethanol and the changes in polarization paralleled to those exhibited by the membranes. The absence of phase transitions and of E changes was also shown in temperature-dependence studies. The lower cholesterol content found in ethanol-fed rat plasma membranes might be responsible for observed variations in the microviscosity.Abbreviation OG octyl -D-glucopyranoside     

Estimating the maintenance energy and biomass concentration of Saccharomyces cerevisiae by continuous calorimetry

Continuous calorimetry has been applied to monitoring the heat evolution of Saccharomyces cerevisiae grown on d-glucose. The heat evolution, together with the energy and carbon balances, was used to evaluate the energetic efficiency of biomass, by-product biosynthesis, fermentative heat evolution as well as the maintenance energy of S. cerevisiae in ‘aerobic fermentation’ and ‘aerobic respiration’. In aerobic fermentation, under catabolite repression, the fraction of substrate energy converted to heat evolution, maintenance requirement, and biomass decreased with the increase of d-glucose concentration. The fraction of substrate energy converted to ethanol is the highest value and it could contribute up to 70% of the total substrate energy. In aerobic respiration, 43% of the total substrate energy was evolved as heat. While 50% of the total substrate energy was converted into biomass, only 7% of the total substrate energy was used for maintenance functions. The maintenance energy coefficient of S. cerevisiae was determined to be 0.427 MJ kg^?1 cell h^?1 (0.102 kcal g^?1 cell h^?1). For the first time, heat evolution together with yield-maintenance energy was used to predict biomass concentration during the fed-batch cultivation of S. cerevisiae.     

Host fruit chemical stimuli eliciting distinct ovipositional responses from sibling species of Rhagoletis fruit flies

Laboratory experiments tested whether two economically-important sibling species of tephritid fruit flies have evolved distinct egg-laying responses to chemical stimuli on the fruits of their respective hostplants. The egg-laying preferences displayed by apple maggot flies, R. pomonella, and blueberry maggot flies, R. mendax, on artificial fruits treated with apple and blueberry extract paralleled their egg-laying responses to whole apples and blueberries. R. pomonella flies laid more eggs than R. mendax flies in artificial fruits treated with extract from ripe McIntosh apples, and vice versa for artificial fruits treated with extract from ripe Bluehaven blueberries. Furthermore, both species laid more eggs in artificial fruits treated with extract from their respective host fruits than control artificial fruits which were not treated with fruit extract. Prior electroantennogram recordings from R. mendax and R. pomonella flies exposed to volatiles from pentane extracts of apples and blueberries indicate that the antennal sensitivity of both species is selectively tuned to their respective host fruit odors. This differentiation in their olfactory responses to fruit odors could be important in mediating their distinct ovipositional responses to blueberry and apple fruits. Extract from unripe McIntosh apples also elicited egg laying by R. pomonella flies, however, artificial fruits treated with unripe apple extract received 1.9 times fewer eggs than those treated with ripe apple extract. Moreover, the numbers of R. pomonella ovipositor punctures and eggs placed in wax artificial fruits were increased when the artificial fruits were treated with a blend of 7 identified apple esters. Black coloration on these artificial fruits and the presence of apple esters had a synergistic effect on the egg-laying behavior of R. pomonella flies, which caused them to lay substantially more eggs per black fruit than white fruit treated with the same concentration of apple esters. In summary, our results indicate that the egg-laying responses of R. pomonella flies are mediated by the integration of information from fruit chemical and visual cues, and that R. mendax and R. pomonella flies have evolved divergent egg-laying responses to chemical stimuli on the fruits of their respective hostplants. These findings are discussed in the context of other studies on plant compounds which influence the ovipositional behavior of phytophagous Diptera.

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Stimuli chimiques des pommes et des myrtilles induisant la ponte des espèces jumelles, Rhagoletis pomonella et R. mendax

Résumé Des fruits artificiels en cire traités avec des extraits de fruits ont provoqué chez les espèces jumelles de R. mendax (Curran) et R. pomonella (Walsh) des réactions de ponte différentes suivant les stimulations chimiques par les fruits. Le comportement de ponte sur des fruits artificiels traités avec des extraits au pentane des myrtilles mûres (Vaccinium corymbosum L.) et de pommes mûres (Malus pumila Miller = Pyrus malus L.), est le même que sur des fruits naturels, ce qui montre que la réponse aux stimulations chimiques provenant du fruit constitue un aspect important de la reconnaissance de l'hôte. R. pomonella pond plus d'ufs que R. mendax sur les fruits artificiels traités à l'extrait de pommes mûres; c'est l'inverse pour les fruits traités aux extraits de myrtille. Les fruits artificiels traités avec des pommes ou des myrtilles provoquent la ponte de R. pomonella, tandis que les myrtilles mûres seules provoquent la ponte de R. mendax. Les extraits de pommes vertes stimulent la ponte de R. pomonella mais elle est alors 2 fois plus faible qu'avec des extraits de pommes mûres. Un mélange de 7 esters identifiés dans l'extrait de pomme induit aussi la ponte de R. pomonella. Le nombre de piqûres de tarièresfli dans les fruits artificiels en cire et le nombre d'ufs par fruit ont été augmentés par addition d'esters de pommes à des fruits blancs ou noirs. La couleur des fruits artificiels influence aussi la réaction de ponte de R. pomonella; la fréquence des piqûres de tarière contenant un uf et le nombre d'ufs par fruit étaient significativement plus élevés sur les fruits noirs que sur les fruits blancs traités avec la même concentration d'esters de pomme. Les fruits artificiels noirs traités avec la concentration la plus stimulante d'esters de pommes ont reçu 2, 3 fois plus d'ufs que les fruits blancs avec les mêmes concentrations en esters. Ces résultats montrent que les esters de pomme et la couleur noire stimulent synergiquement la ponte de R. pomonella sur des fruits artificiels.