Oxidative dealkylation of five phenylurea herbicides by the fungus CunninghamellaechinulataThaxter

Microorganisms isolated from soil degrade phenylurea herbicides via two major pathways: (i) direct hydrolysis by an amidase leading to N,O-dimethylhydroxylamine, CO₂ and aniline¹ and (ii) N-dealkylation, which has been described as the first step in urea herbicide degradation by a variety of organisms including mammals, plants and microbial systems (for a review see reference 2).Until now no attempts have been made to investigate the mechanism of N-demethylation of substituted ureas in soil microorganisms, due to the instability of the N-hydroxymethyl intermediates. This reaction mechanism has only been described in detail in green plants^3–5. As among soil fungi Phycomycetes are known to demethylate phenylurea herbicides^6,7 this study has been made to identify intermediate hydroxymethyl compounds from urea herbicides, when incubated with the fungus $\text{Cunninghamella echinulata Thaxter}$.     

Biotransformation of the fungicide pentachloronitrobenzene by Tetrahymenathermophila

The protozoan, $\text{Tetrahymena}$$\text{thermophila}$, metabolizes pentachloronitrobenzene to several products, including nitrite, pentachlorothioanisole and pentachloroaniline. The latter two metabolites were identified by gas chromatographymass spectrometry. Pentachlorothioanisole may be produced via a glutathione-dependent pathway, and two key enzymes of this pathway, glutathione transferase and thiol S-methyltransferase, have been detected in crude extracts of this microorganism.     

Biotransformation of N-phenyl-β-naphthylamine to β-naphthylamine in a laboratory sludge system

$\text{N}$-Phenyl-$\text{β}$-naphthylamine, a widely used rubber antioxidant and antiozonant, was biotransformed into $\text{β}$-naphthylamine, a potent carcinogen, in a laboratory sewage sludge system. $\text{β}$-Naphthylamine appeared to accumulate in the aqueous phase of the system while the undegraded parent compound appeared to be associated with the sludge solids.     

Uptake and bioaccumulation of three PCBs by Chlorellafusca

This paper reports the bioaccumulation of three PCBs (2,4′-dichlorobiphenyl, 2,4,6,2′-tetrachlorobiphenyl and 2,4,6,2′,4′-pentachlorobiphenyl) by the green alga $\text{Chlorella}$$\text{fusca}$ under various conditions. A probable pattern of the bioconcentration mechanism is suggested. No metabolites were extracted from algae or water 6 days after incubation with PCBs.     

Bioaccumulation of pentachlorophenol by killifish (Fundulussimilus)

Killifish ($\text{Fundulus}$$\text{similis}$) were exposed in the laboratory to pentachlorophenol (PCP) at concentrations of 57 to 610 μg PCP/L. Bioaccumulation reached a plateau value of about 53 by 168 hrs and remained at this level for at least 72 hrs. One-half the plateau value was reached in about 25 hrs. Following exposure, fish placed in PCP-free aquaria lost PCP rather slowly ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～ 4.7}\text{days}$). The depuration data were suggestive of a pool of PCP which was lost more rapidly ($\text{t}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{～ 4.2}\text{hrs}$). The results of this study are compared to similar studies in other species. The bioaccumulation factors measured in this study agree relatively well with those in other marine species, but are lower than reported for fresh water species. Possible reasons for this difference are discussed.     

Environmentally-induced cadmium tolerance in the grass Holcuslanatus L.

This paper reports results of a study on cadmium tolerance in the grass $\text{Holcus}$$\text{lanatus}$ which suggest that tolerance is inducible and can be lost in transplanting plants to uncontaminated soils.     

Historical record of polychlorinated dibenzo-p-dioxins and dibenzofurans in Swiss lake sediments

Polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) were found in annually laminated sediments from Lakes Zurich, Baldegg, and Lugano in Switzerland. Octachlorodibenzo-p-diox in (OCDD) predominated, averaging approximately 1.3 ppb. The congener distribution indicated that combustion was the source of PCDD and PCDF in these sediments. In these dated sediment cores, we found that PCDD and PCDF were absent from the sediments before about 1945, but increased thereafter.     

Biochemical alterations in Bubalusbubalis after repeated exposures to quinalphos

Oral administration of 0.7 mg/kg/day of quinalphos to mals buffalo calves for 28 consecutive days produced marked inhibition of erythrocyte acetylcholinesterase and elevation in serum levels of aminotransferases and phosphatases without inducing apparent toxicity. The enzymic alterations were more pronounced following 1.4 and 2.1 mg/kg/day doses of quinalphos, which were lethal within 4–17 days.     

Metabolites of diisopropylnaphthalene in carp Part 2. Invitro experiment

This study described an $\text{in}$$\text{vitro}$ experiment on biotransformation of 2,6-DIPN in carp hepatopancreas. It has already been revealed by the previous $\text{in}$$\text{vivo}$ studies to be metabolized with enzymatic oxidation in the liver and been postulated a metabolic pathway. These results were confirmed by means of incubation with 2,6-DIPN in carp hepatic microsome preparation with NADPH, and G-6-P as co-factor. It was suggested that DIPN may be mainly metabolized in the hepatic cytochrome P-450 in the microsomes system. The kinetic parameters i.e. apparent Michaelis constant (Km) and maximum velocity (Vmax), in the metabolites formation were also calculated.     

Aqueous solubility of polychlorinated dibenzo-p-dioxins determined by high pressure liquid chromatography

Water solubilities (S_W) determined by the HPLC generator column method are reported for a series of chlorinated dibenzo-$\text{p}$-dioxins (PCDDs) with S_W ranging from 0.4 ng/L (ppt) for octa-chlorodibenzo-$\text{p}$-dioxin to 430 ng/L for 1,2,3,7-tetrachlorodibenzo-$\text{p}$-dioxin at 20°C. A correlation is demonstrated between S_W and HPLC capacity factors (k′) for these extremely hydrophobic compounds, allowing calculation of S_W of PCDDs from k′ and melting point data.     

Effect of fungicidal seed treatments on alfalfa growth and nodulation by Rhizobiummeliloti

A study of the effect of 5 fungicide seed treatments on alfalfa ($\text{Medicago}$$\text{sativa}$ L. var. Vernal) growth and nodulation by $\text{Rhizobium}$$\text{meliloti}$ 102F66 was conducted in a growth chamber. Captan, maneb and thiram exhibited greater toxicity to $\text{R}$. $\text{meliloti}$ and alfalfa plants than that of benomyl and zineb. Recovery of the inhibitory effect was rapid.     

Toxicity of mixtures of phosphamidon and methidathion to lobsters (Homarusamericanus)

The joint toxicity of mixtures of phosphamidon and methidathion to adult lobsters ($\text{Homarus}$$\text{americanus}$) is greater than additive in tests with the combined 48-h toxicity unit of the mixtures totalling 0.25, 0.5 and 1.0 units. The largest magnification factor for greater than additive toxicity occurred where phosphamidon and methidathion contributed to the total toxicity unit in a ratio of 1:1.5 and was progressively smaller for ratios of 1:4.4 and 2:1.     

Chlordane compounds residues in Weddell seals (Leptonychotesweddelli) from the Antarctic

Weddell seal samples taken from the Antarctic have been found to be contaminated with chlordane compounds. ΣChlordane ($\text{cis}\text{-chlordane}\text{+}\text{cis}\text{-nonachlor}\text{+}\text{trans}\text{-nonachlor}\text{+}\text{oxychlordane}$) was present in blubber of seals at the range of 12 - 62 ng/g fresh weight. The order of chlordane compound concentrations was $\text{trans}\text{-nonachlor}\text{>}\text{oxychlordane}\text{>}\text{cis}\text{-nonachlor}\text{>}\text{cis}\text{-chlordane}$. Relative aboundance of $\text{cis}$-chlordane in Σchlordane is higher than that in humans. A probable explanation for their occurrence in the Antarctic is an airborne transport.     

Accumulation of bis(tributyltin) oxide by the mud crab, Rhithropanopeusharrisii

Accumulation of ¹⁴C labelled bis(tributyltin) oxide (TBTO) by the mud crab, $\text{Rhithropanopeus}$$\text{harrisii}$, was determined through short-term exposure to labelled water and food. The potential for trophic accumulation during chronic low level exposure is emphasized.     

Chemical transformation and flux of different forms of arsenic in the carb Carcinusmaenas

The amount of ingested arsenic assimilated and eliminated by the crab appeared to depend on chemical form of arsenic present in the food. Arsenic-74 was translocated rapidly with a high percentage located in hepatopancreas and exoskeleton. The speciation of radioarsenic determined by sequential extraction of experimental food, feces, muscle and hepatopancreas showed that there is no efficient mechanism within the crab which can covert lipid and water soluble arsenic to arsenite and residual arsenic or vice-versa. The biological mechanism in crab selectively and effectively excretes soluble form of arsenite and residual arsenic much more readily than organic arsenic.     

Heavy metal pollution from a point source demonstrated by means of mussels, Mytilusedulis

Heavy metal pollution from a point source has been demonstrated by the levels of mercury in flesh of mussels, $\text{Mytilus}$$\text{edulis}$.