The influence of creosote compounds on the aerobic degradation of toluene

The inhibiting effect of 14 typical creosote compounds on the aerobic degradation of toluene was studied in batch experiments. Four NSO-compounds (pyrrole, 1-methylpyrrole, thiophene, and benzofuran) strongly inhibited the degradation of toluene. When the NSO-compounds were present together with toluene, little or no degradation of toluene was observed during 16 days of incubation, compared with a total removal of toluene within 4 days when the four compounds were absent. Indole (an N-compound) and three phenolic compounds (phenol, o-cresol, and 2,4-dimethylphenol) also inhibited the degradation of toluene, though the effect was much weaker that of the four NSO-compounds. O-xylene, p-xylene, naphthalene and 1-methylnaphthalene seemed to stimulate the degradation even though the influence was very weak. No effects of benzothiophene (an S-compound) and quinoline (an N-compound) were observed. Benzofuran (an O-compound) was identified as the compound that most inhibited the degradation of toluene. An effect could be detected even at low concentrations (40 g/l).Abbreviations bf benzofuran - bt benzothiophene - dmp 2,4-dimethylphenol - GC gas chromatograph - ind indole - mnap 1-methylnaphthalene - MAH monoaromatic hydrocarbons - mpyr 1-methylpyrrole - nap naphthalene - o-cre o-cresol - o-xyl o-xylene - phe phenol - pyr pyrrole - p-xyl p-xylene - tol toluene - thi thiophene - qui quinoline     

On possible different mechanisms subserving the release of arachidonic and di-homo-gamma-linolenic acids for the formation of monoenoic and bisenoic prostaglandins in uteri from ovariectomized rats

The uptake of arachidonic acid (AA) and of di-homo-gamma-linolenic acid (DGLA) and their incorporations into phospholipids (PLs) and into neutral lipids (NLs) of uteri isolated from spayed rats and the effect of inhibiting triglyceride (TG) metabolism with 4-pentenoic acid (4-PEA) on tissue TG levels and the output of prostaglandins (PGs), were explored. Attempts were also made to determine whether the acylation of labelled AA and of labelled DGLA into PLs and TGs is different and to confirm possible correlations between the synthesis of PGE1 and the degradation of TGs. Uterine PLs incorporated significantly less DGLA than AA (P less than 0.05). AA was acylated mainly into the phosphatidylinositol (PI) and into phosphatidylcholine (PC) subfractions of rat uteri, whereas the incorporation of DGLA into these two subfractions was significantly smaller than that of AA. The acylation of labelled DGLA into NL fractions, mainly into triacylglycerol, almost doubled that of labelled AA. The levels of TGs in isolated rat uteri suspended in glucose-free medium during a period of 60 minutes were significantly less than immediately after isolation (P less than 0.001). PGE1 released from uteri into the incubating solution, was significantly higher than that of PGE2. Moreover, the presence of 4-PEA (1.0 mM), added after tissue isolation, prevented the decrement of TGs observed following 60 minutes of incubation and simultaneously diminished significantly (P less than 0.001) the enhanced output of PGE1, without altering that of PGE2. Results presented herein suggest that PLs are not normal precursors for the synthesis of PGE1.(ABSTRACT TRUNCATED AT 250 WORDS)     

Opsonizing properties of natural antibodies of rainbow trout, Oncorhynchus mykiss (Walbaum)

In order to confirm previous observations in which a protective effect of rainbow trout natural antibodies against furunculosis was suspected, phagocytosis studies wereconducted in vitro , using combinations of rainbow trout sera with high or low levels of natural antibodies and active or inactivated complement as opsonizing factors. Opsonization was observed in all the cases where complement was present, and to a lesser degree with sera containing only natural antibodies. The results confirm the prime importance of the complement system and provide additional evidence for a possible role of natural antibodies in antimicrobial defences.     

Inhibition of HIV replication by naphthalenemonosulfonic acid derivatives and a bis naphthalenedisulfonic acid compound

Several naphthalenemonosulfonic acid analogs and a bis naphthalenedisulfonic acid have been evaluated for anti-HIV activity in assays using H9 and MOLT-3 cells. Among the naphthalenemonosulfonic acids, a 4-amino-5-hydroxy compound and a 4,5-diamino compound showed low anti-HIV activity (upto 50% inhibition) at non-toxic doses. The bis naphthalenedisulfonic acid compound demonstrated significant suppression of HIV-1 antigen expression as measured by monoclonal antibodies to p17 (95%), p24 (94%) and syncytia inhibition (82%) at a dose of 20 micrograms/ml that was non-toxic to the host cells. The bis naphthalenedisulfonic acid analog represents a new class of compounds which may be effective in the treatment of HIV infected patients. The structure activity relationship and a probable mode of action of these compounds is discussed.     

Selective suppression of the catalytic activity of cDNA-expressed cytochrome P4502B1 toward polycyclic hydrocarbons in the microsomal membrane: modification of this effect by specific amino acid substitutions.

Human hepatoma HEPG2 cells were infected with recombinant vaccinia virus vectors containing cDNAs encoding both known and variant rat cytochromes P450 (CYP). CYP2B1 and CYP2B2 cytochromes were equally well expressed (110-140 pmol/mg of microsomal protein) and catalyzed metabolism of 7,12-dimethylbenz[a]anthracene (DMBA). Their regioselectivity for DMBA metabolism paralleled that of the respective purified rat liver enzymes and reproduced previously reported regioselective differences between CYP2B1 and CYP2B2 [Wilson et al. (1984) Carcinogenesis 5, 1475-1483]. CYP2A1 and CYP2A2 expressed in HEPG2 microsomes exhibited nearly equal DMBA-metabolizing activities that closely matched that of purified CYP2A1. Although purified rat liver CYP2B1 was 3 times more active than purified rat liver CYP2B2, the expressed recombinant microsomal CYP2B1 (rCYP2B1) was 20 times less active than rCYP2B2, where activity matched that of the purified cytochrome. Microsomal suppression of rCYP2B1 catalytic activity was also observed for benzo[a]pyrene. Specific amino acid substitutions at equivalent positions of the completely homologous NH2-terminal halves of rCYP2B1 and rCYP2B2 changed this suppression effect. Thus, a L58----F, I114----F double mutant exhibited 3 times the normal activity for rCYP2B1 while remaining inhibitory for rCYP2B2. The single substitutions produced very different effects. The L58----F substitution prevented expression of rCYP2B1, while the I114----F substitution was inhibitory for both rCYP2B1 and rCYP2B2 (40 and 70%). A single E282----V mutation produced a stimulation of rCYP2B1 activity comparable to that of the L58----F, I114----F double substitution.(ABSTRACT TRUNCATED AT 250 WORDS)     

Compensation of respiratory alkalosis induced after acclimation to simulated altitude

Conscious intact rats previously acclimated for 3 wk to barometric pressure of 370-380 Torr (3WHx) were made alkalotic for 3 h by a decrease in inspired O2 fraction from 0.10 to 0.075 at ambient barometric pressure (730-740 Torr). Controls were normoxic littermates (Nx) in which inspired O2 fraction was lowered from approximately 0.21 to 0.10 for 3 h. Arterial PCO2 decreased progressively and similarly in both groups (65-70% of control at 15 min). Initially, arterial pH increased less in 3WHx (0.09 +/- 0.004 vs. 0.15 +/- 0.008). As hypocapnia continued, delta[HCO3-]/delta pH (mmol.l-1.pH) became more negative in Nx, from -15.2 +/- 2.5 at 15 min to -37.0 +/- 2.9 at 3 h, indicating nonrespiratory compensation of alkalosis. In 3WHx, delta[HCO3-]/delta pH did not change during alkalosis. Cumulative renal excretion of base (mueq/100 g) during alkalosis increased by 73.2 +/- 11.1 in Nx and 25.4 +/- 7.3 in 3WHx. This difference was mainly due to a larger increase in HCO3- excretion in Nx. The data suggest that the smaller compensation of hypocapnic alkalosis in 3WHx is partly due to the smaller increase in renal base excretion. Because base availability limits renal base excretion, the smaller renal response of 3WHx may be secondary to the low plasma HCO3- concentration that accompanies altitude acclimation.     

Clean technology in aquaculture — a production without waste products?

A method has been developed for the determination of H₂S and FeS in sediments. FeS is converted into H₂S which is flushed from the samples directly into an excess of chlorine bleach, NaC1O or KClO with some Zn²⁺ added. Either the excess can be titrated back potentiometrically with As₂O₃, or the sulphate formed can be measured colorimetrically. The precision is primarily controlled by the homogeneity of the sediment suspensions and can be better than 99%.     

Daphnids respond to algae-associated odours

Using a Y-tube olfactometer, it was found that Daphnia galeatax hyalina moves to the arm with odour from either of two ediblealgal species (Scenedesmus acuminatus and Oscillatoria limnetica)rather than to the alternative arm with clean water. However,no differential response was observed when odours of the toxiccyanobacterium (Oscillatoria agardhu) were tested. We suggestthat odours associated with edible algae attract Daphnia whereasnon-edible algae do not elicit attraction of Daphnia.     

Grain yield, symbiotic N2 fixation and interspecific competition for inorganic N in pea-barley intercrops

The effect of mixed intercropping of field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.), compared to monocrop cultivation, on the yield and crop-N dynamics was studied in a 4-yr field experiment using ¹⁵N-isotope dilution technique. Crops were grown with or without the supply of 5 g ¹⁵N-labeled N m^-2. The effect of intercropping on the dry matter and N yields, competition for inorganic N among the intercrop components, symbiotic fixation in pea and N transfer from pea to barley were determined. As an average of four years the grain yields were similar in monocropped pea, monocropped and fertilized barley and the intercrop without N fertilizer supply. Nitrogen fertilization did not influence the intercrop yield, but decreased the proportion of pea in the yield. Relative yield totals (RYT) showed that the environmental sources for plant growth were used from 12 to 31% more efficiently by the intercrop than by the monocrops, and N fertilization decreased RYT-values. Intercrop yields were less stable than monocrop barley yields, but more stable than the yield of monocropped pea. Barley competed strongly for soil and fertilizer N in the intercrop, and was up to 30 times more competitive than pea for inorganic N. Consequently, barley obtained a more than proportionate share of the inorganic N in the intercrop. At maturity the total recovery of fertilizer N was not significantly different between crops, averaging 65% of the supplied N. The fertilizer N recovered in pea constituted only 9% of total fertilizer-N recovery in the intercrop. The amount of symbiotic N₂ fixation in the intercrop was less than expected from its composition and the fixation in monocrop. This indicates that the competition from barley had a negative effect on the fixation, perhaps via shading. At maturity, the average amount of N₂ fixation was 17.7 g N m^-2 in the monocrop and 5.1 g N m^-2 in the intercropped pea. A higher proportion of total N in pea was derived from N₂ fixation in the intercrop than in the monocrop, on average 82% and 62%, respectively. The ¹⁵N enrichment of intercropped barley tended to be slightly lower than of monocropped barley, although not significantly. Consequently, there was no evidence for pea N being transferred to barley. The intercropping advantage in the pea-barley intercrop is mainly due to the complimentary use of soil inorganic and atmospheric N sources by the intercrop components, resulting in reduced competition for inorganic N, rather than a facilitative effect, in which symbiotically fixed N₂ is made available to barley.Abbreviations MC monocrop - IC intercrop - PMC pea monocrop - BMC barley monocrop - PIC pea in intercrop - BIC barley in intercrop