Efficient epoxidation of unsaturated fatty acids by a hydroperoxide-dependent oxygenase

Detergent-solubilized and partially purified soybean peroxygenase was shown to actively catalyze, in the presence of alkylhydroperoxides as co-substrates, the epoxidation of mono- and polyunsaturated fatty acids such as oleic and linoleic acids. Octadecenoic acids were found to be better substrates than shorter mono-unsaturated fatty acids (C16:1 or C14:1), but the position of their double bond (at positions 6, 9, or 11) had little effect on the rates of epoxidation. The peroxygenase exhibits a strong stereospecificity since octadecenoic acids with double bonds in trans-configuration were not epoxidized at detectable rates. Oxidation of linoleic acid yielded the two positional monoepoxide isomers and, as the minor product, the diepoxide. An important regioselectivity was, however, observed in this case; i.e. the unsaturation at position 9,10 was epoxidized preferentially to that at 12, 13. Oxidation of oleic acid in the presence of 18O-labeled hydroperoxy-linoleic acid revealed an incorporation of about 80% of the label into the epoxide ring. Products similar to those formed by the peroxygenase by epoxidation of unsaturated free fatty acids such as linoleic acid have been described as important metabolites (leukotoxins) in the defense of plants, e.g. in fungal agressions. This aspect underlines the physiological relevance of this new and potent catalytic activity of the peroxygenase.     

r14 syndrome without major dysmorphism

An 8-year-old boy, mentally retarded and epileptic since the age of six months, was found carrier of ring 14 chromosome. A dystrophy of the eye fundi was observed (whitish puncta of the macula); except for the "almond shaped eyes", there was no obvious dismorphism.     

Duplication 16q12----qter arising from 3:1 segregation in a 46,XX,t(13;16) (q12;q12) mother

A congenitally abnormal female baby was found to have the karyotype 46, XX, +der (16) t (13; 16) (q12;q12) mat. GTG, QFQ, CBG, THA and Ag-NOR banding techniques allowed the identification of the abnormal chromosomes in the proposita and in the translocation carriers through three generations. Duplication 16q resulted from 3:1 segregation in the carrier mother. The hypothesis of a specific meiotic segregation for this translocation is discussed. The phenotypic effects of proximal 16q duplications are analysed together with other four reported cases, which have similar duplicated segment and no other relevant chromosomal abnormality.     

Bacterial degradation of styrene involving a novel flavin adenine dinucleotide-dependent styrene monooxygenase.

By using styrene as the sole source of carbon and energy in concentrations of 10 to 500 microM, 14 strains of aerobic bacteria and two strains of fungi were isolated from various soil and water samples. In cell extracts of 11 of the bacterial isolates, a novel flavin adenine dinucleotide-requiring styrene monooxygenase activity that oxidized styrene to styrene oxide (phenyl oxirane) was detected. In one bacterial strain (S5), styrene metabolism was studied in more detail. In addition to styrene monooxygenase, cell extracts from strain S5 contained styrene oxide isomerase and phenylacetaldehyde dehydrogenase activities. A pathway for styrene degradation via styrene oxide and phenylacetaldehyde to phenylacetic acid is proposed.     

Influence of hormone concentration and time factor on development of receptor memory in a unicellular (Tetrahymena) model system

1. Treatment of Tetrahymena pyriformis cells with diiodotyrosine (T2) gave rise to a considerable, concentration-dependent increase of the growth rate within the range of 10(-15) and 10(-9) M, but did not influence it at the level of 10(-18) M. 2. Re-exposure of the cells 1, 2 and 4 weeks later to the hormone concentrations originally used accounted for a marked increase of growth rate at all hormone levels tested, indicating that the extremely low concentration of 10(-18) M, which failed to stimulate growth on first exposure, did nevertheless give rise to hormonal imprinting, which caused the cells to "remember" the hormone, as judged from their increased responsiveness to it on re-exposure. 3. The degree of growth response was concentration-dependent on both first and second exposure: higher levels of treatment gave rise to firmer imprinting, and to greater response on re-exposure. 4. The length of exposure time proved to be more decisive than the level of treatment in respect of the development of hormonal imprinting. 5. Short-term exposures up to 60 min, although they stimulated cell growth by direct effect, gave rise to lasting inhibition of cellular response to re-exposure(s) rather than to hormonal imprinting.     

Virulence ofEscherichia coli strains isolated from urine of patients with acute cystitis and from faeces of healthy women

E. coli strains were isolated from the urine of patients with acute cystitis in general practice and from the faeces of a comparable reference group of healthy individuals. These strains were serotyped and tested for virulence in an experimental mouse model. Of 30 cystitis-strains 18 were virulent, and of 30 faeces-strains 15 were virulent. It is concluded that the cystitis-strains were not more often virulent than the faeces-strains. O antigens commonly found among urinaryE. coli isolates were present in 60% of the cystitis-strains and in 37% of the faeces-strains. K antigens commonly found in urinaryE. coli strains were present in 33% of the cystitis-strains and in 12% of the faeces-strains. Neither the presence of common urinary O-antigens, nor the presence of common urinary K antigens could be associated with virulence of the isolated strains. However, it is suggested that certain O and K antigens (O2, O6, K23) may be associated with virulence for the urinary tract.     

Effect of the natural ATPase inhibitor on the binding of adenine nucleotides and inorganic phosphate to mitochondrial F1-ATPase

(1) Incubation of the beef heart mitochondrial ATPase, F₁ with Mg-ATP was required for the binding of the natural inhibitor, IF₁, to F₁ to form the inactive F₁-IF₁ complex. When F₁ was incubated in the presence of [¹⁴C]ATP and MgCl₂, about 2 mol ¹⁴C-labeled adenine nucleotides were found to bind per mol of F₁; the bound ¹⁴C-labeled nucleotides consisted of [¹⁴C]ADP arising from [¹⁴C]ATP hydrolysis and [¹⁴C]ATP. The ¹⁴C-labeled nucleotide binding was not prevented by IF₁. These data are in agreement with the idea that the formation of the F₁-IF₁ complex requires an appropriate conformation of F₁. (2) The ¹⁴C-labeled adenine nucleotides bound to F₁ following preincubation of F₁ with Mg-[¹⁴C]ATP could be exchanged with added [³H]ADP or [³H]ATP. No exchange occurred between added [³H]ADP or [³H]ATP and the ¹⁴C-labeled adenine nucleotides bound to the F₁-IF₁ complex. These data suggest that the conformation of F₁ in the isolated F₁-IF₁ complex is further modified in such a way that the bound ¹⁴C-labeled nucleotides are no longer available for exchange. (3) ³²P_i was able to bind to isolated F₁ with a stoichiometry of about 1 mol of P_i per mol of F₁ (Penefsky, H.S. (1977) J. Biol. Chem. 252, 2891–2899). There was no binding of ³²P_i to the F₁-IF₁ complex. Thus, not only the nucleotides sites, but also the P_i site, are masked from interaction with external ligands in the isolated F₁-IF₁ complex.     

Le Crocodilien Diplocynodon (Eusuchia,Alligatoridae) dans la«série du gypse d'Aix à Venelles (Bouches-du-Rhône,France)

A crocodilian skeleton from the «série du gypse d'Aix (basal Aquitanian) at Venelles (Bouches-du-Rhône) is described and referred to Diplocynodon cf. rateli. The specimen seems to have been mutilated by scavengers before burial. The occurrence of the freshwater crocodilian Diplocynodon in the «série du gypse d'Aix is in agreement with recent reconstructions of the depositional environment, which suggest a basin with a fluctuating, but usually low, salinity.