Variation of nicotinamide adenine dinucleotide phosphate level in bean hypocotyls in relation to o(2) concentration

Slices of hypocotyls from 3-day-old seedlings of Vigna sesquipedalis (L.) Fruwirth in the germination stage were incubated under various gaseous conditions. The NADP+NADPH level in the hypocotyl slices changed with the oxygen tension. A high NADP+NADPH level was observed under aerobic conditions and a low NADP+NADPH level under anaerobic conditions.

The 100 × NADH/NAD+NADH ratio increased greatly under anaerobic conditions. In general a low NADP + NADPH level corresponded with a high 100 × NADH/NAD+NADH ratio. On the basis of the results given in the following paper, it was discussed that the slowness of NADH oxidation in hypocotyl tissue due to anaerobic conditions results in the inhibition of NADP formation.

The variation of the NADP+NADPH level was considered to produce a modification of the carbohydrate metabolism.

The NADP+NADPH level in E. coli cells suspended in glucose solution also changed with the oxygen tension.

     

Batch cultures of Escherichia coli with added substrate under various aeration conditions

The growth parameters (Xmax, Y, mu) of Escherichia coli batch cultures were studied when a substrate was added under different aeration conditions. If the pH was not adjusted, the bacterial growth stopped at pH 4.5 under the aerobic conditions or at pH 5.8 under the anaerobic conditions. When the pH 7.0 was constantly maintained, the accumulation of acid products in the aerobic culture was 3 times as high as in the anaerobic culture by the time the growth ceased. The anaerobic culture resumed its growth upon aeration. A hypothesis is proposed to explain the data.     

Enhanced biodegradation of methoxychlor in soil under sequential environmental conditions.

Ring-U-[14C]methoxychlor [1,1-bis(p-methoxyphenyl)-2,2,2-trichloroethane] was incubated in soil under aerobic and anaerobic conditions. Primary degradation of methoxychlor occurred under anaerobic conditions, but not under aerobic conditions, after 3 months of incubation. Analysis of soil extracts, using gas chromatography, demonstrated that only 10% of the compound remained at initial concentrations of 10 and 100 ppm (wt/wt) of methoxychlor. Evidence is presented that a dechlorination reaction was responsible for primary degradation of methoxychlor. Analysis of soils treated with 100 ppm of methoxychlor in the presence of 2% HgCl2 showed that 100% of the compound remained after 3 months, indicating that degradation in the unpoisoned flasks was biologically mediated. Methanogenic organisms, however, are probably not involved, as strong inhibition of methane production was observed in all soils treated with methoxychlor. During the 3-month incubation period, little or no evaluation of 14CO2 or 14CH4 occurred under either aerobic or anaerobic conditions. Cometabolic processes may be responsible for the extensive molecular changes which occurred with methoxychlor because the rate of its disappearance from soil was observed to level off after exhaustion of soil organic matter. After this incubation period, soils previously incubated under anaerobic conditions were converted to aerobic conditions. The rates of 14CO2 evolution from soils exposed to anaerobic and aerobic sequences of environments ranged from 10- to 70-fold greater than that observed for soils exposed solely to an aerobic environment.     

Mineralization of biuret nitrogen in soil

Summary Study of the mineralization of biuret N under aerobic and anaerobic conditions in a sandy loam showed that higher amounts of mineral N accumulated under anaerobic incubation than under aerobic conditions. Under waterlogged incubation, 46.8% of the 100 ppm biuret N was mineralized while under aerobic conditions only 18.3% of biuret-N was converted into mineral N during 5 weeks at 30°C. The results of the study bring out slow-release nature of biuret-N.     

Acquisition of avoidance reaction in rats with different social experience in youth

The acquisition of both active and passive avoidance response, the extinction of the former and the retention of the long-term memory trace of the latter were studied in 30- and 90-day-old male rats of the Wistar strain. The rats were in 3 groups which had had a different history between 15 and 30 days of age: (1) normally weaned rats lived from birth in a cage together with mother and siblings, i.e. under usual laboratory breeding conditions; (2) prematurely weaned rats lived under the same conditions for the first 15 days; after this period, their mother was removed from the cage; (3) community-reared rats had the same history up to 15 days of age; then they began to live in a community (5 connected cages) in contact with both young and adult rats from other cages. Ninety- day-old male rats acquired an active avoidance response at the same rate irrespective of their history in youth but 30-day-old rats were relatively slower if they had been prematurely weaned. Among both normally and prematurely weaned 30-day-old rats, the extinction was slower than in community-reared rats of the same age. Passive avoidance response was acquired by all rats at the same rate irrespective of their history and age. The long- term memory trace was always more stable in adult rats than in young ones.     

Influence of age and starvation on pO2, pCO2 and haematocrit values in the rat.

The author determined the effect of acute starvation on the arterial pO2 and pCO2 value (analysed on a micro-Astrup apparatus) in rats of different ages; in infant rats, this was done by separating them from the female and the nest for 24 hours. Arterial blood was obtained by incising the tail artery. It was found that the pO2 value in rat arterial blood rose signficantly during ontogenesis. At 10 and 14 days the mean pO2 value was 68 torr, while at 25 days and in adult rats it was 92-95 torr. No marked changes were found in CO2 during ontogenesis (the mild drop was not statistically significant). In 10- and 14-day-old rats, 24 hours' starvation caused a significant decrease in pO2. In older rats, deprivation of food and water did not significantly affect the pO2; in the arterial blood. The arterial blood pCO2 was not influenced by starvation. The development of the haematocrit values in mixed blood (obtained by decapitation) during ontogenesis was in agreement with findings in the literature, i.e. a drors' complete starvation produced no change in the haematocrit values in 5- and 10-day-old rats, but a marked increase was recorded in older rats.     

Aerobic versus anaerobic metabolism of halogenated anilines by aParacoccus sp.

AParacoccus sp. which transforms aniline and different halogen-substituted derivatives under aerobic and anaerobic conditions was isolated from the soil. In experiments with¹⁴C-ring-labeled 4-chloroaniline, approximately 60% of the radioactive material disappeared from the growth medium after incubation under anaerobiosis within 48 hr, but under aerobic conditions no decrease of radioactivity in the growth medium was observed, although 4-chloroaniline was completely metabolized. Acetylation appears to constitute, especially under aerobic conditions, a major transformation mechanism by the bacterium, since almost 50% of the acetylated compound could be detected and identified if aniline, 2-, 3-, and 4-chloroaniline served as substrate. The formation of different metabolites under aerobic and anaerobic conditions clearly indicates the existence of two separate pathways in the metabolism of aniline compounds depending on the oxygen status of the environment.     

Different degrees of lipid peroxidation in the CNS of young and adult rats exposed to short-term hypobaric hypoxia.

The authors studied the effect of short-term (20 min) hypobaric hypoxia at simulated altitudes of 7000 and 9000 m on the peroxidation of lipids in the cerebral cortex, subcortical formations, medulla oblongata and cerebellum of the laboratory rat. In 5- and 21-day-old rats, increased lipoperoxidation was recorded in all the studied regions of the brain. Differences were observed in sensitivity to the degree of hypoxia. In 5-day-old rats the response to both exposures was the same, but in 21-day-old animals exposure at 7000 m stimulated peroxidation in the cerebral cortex only (at 9000 m in all the parts of the CNS examined). In 35-day-old and adult rats, changes in the malondialdehyde concentration were likewise found after exposure at 9000 m, but not in every compartment (in 35-day-old rats in the cerebral cortex and subcortical formations and in adult rats in the cerebral cortex). In young rats, 30 and 60 min after exposure to hypoxia the malondialdehyde concentration was still higher than in older animals.     

Protoporphyrin formation in Rhizobium japonicum.

The obligately aerobic soybean root nodule bacterium Rhizobium japonicum produces large amounts of heme (iron protoporphyrin) only under low oxygen tensions, such as exist in the symbiotic root nodule. Aerobically incubated suspensions of both laboratory-cultured and symbiotic bacteria (bacteroids) metabolize delta-aminolevulinic acid to uroporphyrin, coproporphyrin, and protoporphyrin. Under anaerobic conditions, suspensions of laboratory-cultured bacteria form greatly reduced amounts of protoporphyrin from delta-aminolevulinic acid, whereas protoporphyrin formation by bacteroid suspensions is unaffected by anaerobiosis, suggesting that bacteroids form protoporphyrin under anaerobic conditions more readily than do free-living bacteria. Oxygen is the major terminal electron acceptor for coproporphyrinogen oxidation in cell-free extracts of both bacteroids and free-living bacteria. In the absence of oxygen, ATP, NADP, Mg2+, and L-methionine are required for protoporphyrin formation in vitro. In the presence of these supplements, coproporphyrinogenase activity under anaerobic conditions is 5 to 10% of that observed under aerobic conditions. Two mechanisms for coproporphyrinogen oxidation exist in R. japonicum: an oxygen-dependent process and an anaerobic oxidation in which electrons are transferred to NADP. The significance of these findings with regard to heme biosynthesis in the microaerophilic soybean root nodule is discussed.     

Nitrite as a candidate substrate in microbial fuel cells

Current generation using nitrite as substrate (pH 6.9, 40 mgN l(-1)) in a nitrite-fed microbial fuel cell was investigated under anaerobic and aerobic anodic conditions as an alternative to the biological nitrite oxidation process. Cell current, coulombic efficiency (CE) and power generation of 0.04 mA, 30 ± 2 % and 19.3 ± 3.3 μW m(-2), respectively, were observed under anaerobic conditions while complete nitrite degradation (no current) was obtained under aerobic conditions. Switching from aerobic to anaerobic anode enhanced the CE and power generation (39 ± 1 % and 29 ± 4.3 μW m(-2)).     

Studies on the regulation of yeast phosphofructo-1-kinase: its role in aerobic and anaerobic glycolysis

The kinetics of yeast phosphofructo-1-kinase has been studied in vitro. Effector concentrations (Fru-6-P, ATP, ADP, AMP, Pi, Fru-1,6-P2, and Fru-2,6-P2) and pH were adjusted so as to mimic intracellular concentrations in yeast. Under these conditions we were able to reproduce the measured in vivo rate of PFK. In addition, by reconstituting the intracellular conditions existing during aerobic and anaerobic glycolysis, we were able to reproduce in vitro the changes in the rate of PFK observed under these conditions. Without the addition of the newly discovered effector Fru-2,6-P2, in vitro rates of PFK are much lower than its in vivo rate. Changes in Fru-2,6-P2, Fru-1,6-P2, ATP, AMP, Pi, and pH in going from aerobic to anaerobic conditions all contributed somewhat to the change in the rate of PFK observed during the Pasteur effect, with no contribution coming from ADP. These studies show that the control of PFK under the condition of the Pasteur effect cannot be ascribed to changes in any one particular effector but rather to contributions from a variety of effectors. Also, the net change in the rate of PFK in the switch from anaerobic to aerobic glycolysis is small compared with the change in its dependence upon its substrate Fru-6-P, indicating a compensation mechanism.     

Lithium/pilocarpine status epilepticus-induced neuropathology of piriform cortex and adjoining structures in rats is age-dependent

Distribution of LiCl/pilocarpine status epilepticus-induced neuronal damage was studied in the piriform cortex and in adjoining structures in 12-day-old, 25-day-old and adult rats. No distinct structural and neuronal alterations were detected in the basal telencephalon in 12-day-old rats surviving status epilepticus (SE) for one week or two months. In 25-day-old rats a decrease in Nissl staining was evident. There was also cell loss and gliosis in the caudal 2/3 of the piriform cortex, in the superficial amygdaloid nuclei, in the dorsal and ventral endopiriform nucleus and in the rostrolateral part of the entorhinal cortical area. In adult animals, the topography of neuropathological changes in the basal telencephalon was comparable to those in 25-day-old rats. The damage in the caudal 2/3 or caudal half of the piriform cortex in adult rats with survival times one week or two months was characterized by a marked loss of neurons and striking glial infiltration. The thickness of the piriform cortex and superficial amygdaloid nuclei was significantly reduced. In 25-day-old and in adult animals the sublayer IIb and layer III of the piriform cortex was more affected, while sublayer IIa was less damaged. Parvalbumin (PV) immunocytochemistry revealed a significant decrease in the number of PV-immunoreactive neurons in the rostral piriform cortex and in the dorsal claustrum in animals surviving for two months.     

Arachidonic acid-induced inhibition of (Na+K+)-stimulated ATPase in the cerebral cortex and medulla oblongata of young and adult rats

The effect of arachidonic acid in 5.10(-4) and 5.10(-5) mol.l-1 concentration (as the Na salt, SIGMA) on ouabain-sensitive ATPase (E. C. 3.6.1.3) activity was studied in the cerebral cortex and medulla oblongata of 5-day-old and adult rats. In adult rats, arachidonic acid significantly inhibited ouabain-sensitive ATPase activity in both the cerebral cortex and the medulla oblongata. In 5-day-old rats, only the higher concentration (5.10(-4) mol.l-1) inhibited the enzyme statistically significantly; use of the lower concentration was not followed by any significant changes in Na+-K+-ATPase activity.     

TRANSFER RNA AND THE REGULATION OF PROTEIN SYNTHESIS IN RAT CEREBRAL CORTEX DURING NEURAL DEVELOPMENT

Protein synthesis was measured in ribosomal systems derived from the cerebral cortex of 5-and 35-day-old rats. Under optimal conditions incorporation of radioactive leucine per mg ribosomal protein was four times higher with ribosomes from the younger animals than with ribosomes from the 35-day-old rats. This suggests that a decrease in the rate of protein synthesis occurs during neural development. Both ribosomes and the pH enzyme fraction from the cerebral cortex of 35-day-old rats had lower activities than preparations from the younger rats. Cerebral cortical ribosomes from 35-day-old animals had a lower polyribosome content than similar preparations from 5-day-old rats. A three-fold higher requirement for the pH 5 enzyme fraction was observed with the ribosomal system from 5-day-old rats, an observation which correlated with the yields of pH 5 enzyme and ribosomal protein from the younger tissue. The nature of the changes in the composition of the pH 5 enzyme fraction was investigated. Methylated albumin kiesselguhr (MAK) and Sephadex G-75 column chromatography showed that RNA from the pH 5 enzyme fraction was heterogeneous, containing tRNA, rRNA, and a small molecular weight RNA. This latter RNA, perhaps a degradation product of rRNA, comprised the greatest portion of RNA from the pH 5 enzyme fraction of cerebral cortex. The data obtained with MAK chromatography were used to estimate the total tRNA content of the cerebral cortex, with no age-related differences being observed. Since evidence of RNA degradation was seen, tRNA was also isolated by phenol extraction of whole cerebral cortex in the presence of bentonite. Purification of tRNA by NaCl and isopropanol fractionation gave preparations with no detectable rRNA or small molecular weight RNA. With this purification method, the tRNA yield was greater than estimated by the MAK method, demonstrating that losses of tRNA occurred during the cell fractionation steps. With the purification method 1.6 times more tRNA was obtained from the cerebral cortex of 5-day-old animals than from the older tissue. This higher level of tRNA in the younger, more active tissue appeared to involve all tRNA species, since in vitro aminoacyiation studies revealed nearly identical acceptance values for 18 individual amino acids. These results suggest that the rate of protein synthesis in cerebral cortex is regulated in part by the total amount of tRNA present to translate the higher level of polysome-bound mRNA.     

The effect of a protein on the radiolysis of DNA studied by HPLC and pulse radiolysis

Double-stranded DNA from calf thymus was irradiated in the presence of bovine serum albumin (BSA) with a ratio of 1:10 in weight, at pH7 and pH5, under aerobic and under anaerobic conditions. The irradiated biomolecules were separated by high-performance liquid-gel permeation chromatography. At pH 7, in the presence of the protein, degradation of DNA was enhanced by oxygen, while under anaerobic conditions formation of protein-DNA crosslinks was observed. At pH5, crosslinking of BSA to DNA occurred under anaerobic as well as under aerobic conditions, while fragmentation of DNA could not be detected with this method with doses up to 1600 Gy. Under nitrogen, the degradation of BSA was not altered by the addition of DNA, but in the presence of oxygen less BSA was lost for a given dose when DNA was present.     

Survival of a Salmonella typhimurium poultry isolate in the presence of propionic acid under aerobic and anaerobic conditions

Propionic acid is commonly found as a fermentation product in the gastrointestinal tracts of food animals and has also been used to limit the microbial contaminants in animal feeds. Because propionic acid is known to have antibacterial activity, the propionic acid encountered by foodborne pathogens during their life cycles may play an important role in inhibiting the survival of the pathogens. The survival patterns of Salmonella typhimurium poultry isolate were determined both in aerobic and anaerobic tryptic soy broth (TSB; pH 5.0 or 7.0) containing various concentrations of propionic acid (0-200 mM). The levels of recovered cells were consistently greater at pH 7.0 compared to those at pH 5.0. For the first 4 days, the levels were significantly decreased by incubation under anaerobic conditions as compared to aerobic condition at pH 7.0 (P<0.05). However, there were fluctuations of cell populations with different patterns depending on both concentrations and growth conditions. To characterize the nature of the capability which allowed the cell multiplication following decreases in cell population during incubation at pH 7.0, the cells isolated from the outgrowth cultures were tested for survival in aerobic or anaerobic TSB (pH 5.0 or pH 7.0) containing propionic acid (50 mM). The outgrowth isolates did not show significant differences in the level of recovered cells in the presence of propionic acid when compared to the wild type strain (P>0.05), suggesting that the cells in the outgrowth cultures did not harbour mutation(s) conferring increased resistance to propionic acid. In addition, the level of recovered cells of isogenic rpoS mutant strain of S. typhimurium was not significantly different from that of the wild type strain in the same assay conditions (P<0.05). The results of this study show that the bactericidal activity of propionic acid on S. typhimurium can be affected by environmental conditions such as acidic pH levels and anaerobiosis in food materials and gastrointestinal tracts. However, S. typhimurium is also able to multiply in the presence of sublethal concentrations of propionic acid at neutral pH during prolonged incubation under both aerobic and anaerobic conditions.     

Effect of the activity of primary proton pumps on the growth of Escherichia coli in the presence of acetate

Escherichia coli batch cultures were grown under aerobic and anaerobic conditions on glucose with the substrate addition at pH 7.0. The cultures accumulated acetate in the medium at concentrations sufficient to inhibit the growth. This inhibitory effect of acetate was mediated apparently via its action on the intracellular pH. The inhibition of E. coli growth by acetate increased when the redox proton pump was switched off in the course of transition from aerobiosis to anaerobiosis and when the regulation of K+ fluxes was disordered in the presence of valinomycin. H+-ATPase was not essentially involved in maintaining the high rate of E. coli growth in the presence of acetate under aerobic conditions. If the activity of H+-ATPase was inhibited under anaerobic conditions at pH 7.0, the growth ceased after the dissipation of ionic gradients on the membrane. When CCCP was added under aerobic conditions, the growth did not stop at once if the medium had a pH of 7.6, but ceased immediately at pHout 7.0 in the glucose-salt medium.     

Hyperosmotic stress and elevated pCO2 alter monoclonal antibody charge distribution and monosaccharide content

Medium osmolality increases with pCO2 at constant pH. Elevated pCO2 and osmolality inhibit hybridoma growth to similar extents in both serum-containing and serum-free media. The combination of osmolality and elevated pCO2 synergizes to negatively impact cell growth. IgG2a glycosylation by hybridoma cells was evaluated under elevated pCO2 (to 250 mmHg pCO2) and/or osmolality (to 476 mOsm/kg). IgG2a site occupancy did not change significantly under any of the conditions studied, which is consistent with the robust glycosylation of other antibodies produced under various environmental stresses. However, changes were observed in the IgG2a charge distribution. Changes in the isoelectric point (pI) were greater under hyperosmotic stress, increasing by 0.32 and 0.41 pH units at 435 mOsm/kg in serum-containing and serum-free medium, respectively. Hyperosmotic stress also resulted in a concomitant increase in the heterogeneity of the charge distribution. The mean pI in serum-containing medium decreased by 0.16 pH units at 250 mmHg pCO2 when osmolality was controlled at 320 mOsm/kg but increased by 0.20 pH units when the osmolality increased with pCO2 (195 mmHg pCO2-435 mOsm/kg). In serum-free medium, elevated pCO2 did not alter pI, regardless of medium osmolality. In contrast to elevated osmolality at control pCO2, elevated pCO2 did not significantly alter the IgG2a charge heterogeneity under any of the conditions studied. The IgG2a was not sialylated, so sialylation changes were not responsible for changes in the charge distribution. IgG2a galactose content decreased with elevated osmolality, as a result of either elevated NaHCO3 or NaCl. However, when osmolality was controlled at elevated pCO2, the galactose content tended to increase. The mannose content decreased with increasing stress, while the fucose content remained relatively unchanged. It is likely that the observed increases in the pI of murine IgG2a were due to increased organellar pH, which is reflected by increased specific beta-galactosidase activity in the supernatant.     

Ontogenesis of oxidative reaction of 17beta-hydroxysteroid dehydrogenase and 11beta-hydroxysteroid dehydrogenase in rat Leydig cells,a histochemical study

The enzyme 17beta-hydroxysteroid dehydrogenase is required for the synthesis and 11beta-hydroxysteroid dehydrogenase for the regulation of androgens in rat Leydig cells. This histochemical study describes ontogenetic changes in distribution and intensity of these enzymes in Leydig cells from postnatal day (pnd) 1-90. Using NAD or NADP as the cofactor, 17beta-hydroxysteroid dehydrogenase (substrate: 5-androstene-3beta,17beta-diol) peaks were observed on pnd 16 for fetal Leydig cells and on pnd 19 and 37 for adult Leydig cells. Between pnd 13 and 25 the fetal cells showed a higher intensity for the 17beta-enzyme than the adult cells; more fetal Leydig cells were stained with NADP, whereas more adult cells were positive with NAD on pnd 13 and 16. A nearly identical distribution of 11beta-hydroxysteroid dehydrogenase (substrate: corticosterone) was observed with NAD or NADP as the cofactor; the reaction was present from pnd 31 onwards, first in a few adult Leydig cells and later in almost all these cells homogeneously. The ontogenetic curves of the two enzymes show an inverse relationship. To conclude: (1) Generally, a stronger reaction for 17beta-hydroxysteroid dehydrogenase is shown with NAD as cofactor than with NADP; using NADP, fetal Leydig cells show a stronger staining than adult Leydig cells. (2) The data possibly support the notion of a new isoform of 11beta-hydroxysteroid dehydrogenase in addition to types 1 and 2.     

Nitrification and nitrate dissimilation in soil

Summary 1. Studies were made on the decomposition of a substrate containing glucose, ammonia, and nitrate in soil held under differing aeration conditions.2. When water slurries were incubated with substrate, the loss of total-N equalled the loss of nitrate plus nitrite nitrogen.3. Under percolation conditions, with small amounts of substrate and an oxygen partial pressure of 15.2 cm of mercury, there was little change in nitrate or nitrite concentrations. Loss of nitrate only occurred under conditions of reduced aeration but, when it did occur, the sum of nitrate plus atmospheric oxygen utilized by the soil was approximately the same, irrespective of the loss of nitrate. Under an atmosphere of oxygen-free nitrogen, gas output was proportional to loss of nitrate plus nitrite nitrogen. In all cases immobilisation of ammonia was similar.4. Soils which had been percolated under anaerobic conditions with substrate, when put under aerobic conditions and with fresh substrate added, did not lose nitrate. Soils that had been percolated under aerobic conditions, when put under anaerobic conditions and with fresh substrate added, lost nitrate after a lag phase. The period of the phase was decreased by using small amounts of substrate for the aerobic percolation.5. It is concluded that analyses for nitrate and nitrite, or measurements of oxygen uptake, can be used to give approximate measures of nitrate dissimilation.