Disciplinary attitudes and cigarette smoking: a comparison of two schools.

Two British boarding schools for boys with different disciplinary policies in respect of cigarette smoking were identified. Questionnaires were sent to the young "old boys" of each school to determine their present smoking habit and most were returned (school A 81%, school B 83%). Significantly more responders smoked who had been to the less strict school (school A 39%, school B 30%, p less than 0.05). These figures probably underestimate the smoking prevalence in the two complete groups. The results suggest that measures that reduce the exposure of an uncommitted adolescent to peer group smoking decrease the chances of tobacco dependence in adulthood.     

Immunochemical identity of peroxisomal enoyl-CoA hydratase with the peroxisome-proliferation -associated 80,000 mol wt polypeptide in rat liver

Peroxisome proliferators, which induce proliferation of hepatic peroxisomes, have been shown previously to cause a marked increase in an 80,000 mol wt polypeptide predominantly in the light mitochondrial and microsomal fractions of liver of rodents. We now present evidence to show that this hepatic peroxisome-proliferation-associated polypeptide, referred to as polypeptide PPA-80, is immunochemically identical with the multifunctional peroxisome protein displaying heat-labile enoyl-CoA hydratase activity. This conclusion is based on the following observations: (a) the purified polypeptide PPA-80 and the heat- labile enoyl-CoA hydratase from livers of rats treated with the peroxisome proliferators Wy-14,643 {[4-chloro-6(2,3-xylidino)-2-pyrimidinylthio]acetic acid} exhibit identical minimum molecular weights of approximately 80,000 on SDS polyacrylamide gel electrophoresis; (b) these two proteins are immunochemically identical on the basis of ouchterlony double diffusion, immunotitration, rocket immunoelectrophoresis, and crossed immunoelectrophoresis analysis; and (c) the immunoprecipitates formed by antibodies to polypeptide PPA-80 when dissociated on a sephadex G-200 column yield enoyl-CoA hydratase activity. Whether the polypeptide PPA-80 exhibits the activity of other enzyme(s) of the peroxisomal β-oxidation system such as fatty acyl-CoA oxidase activity or displays immunochemical identity with such enzymes remains to be determined. The availability of antibodies to polypeptide PPA-80 and enoyl-CoA hydratase facilitated immunofluorescent and immunocytochemical localization of the polypeptide PPA- 80 and enoyl-CoA hydratase in the rat liver. The indirect immunofluorescent studies with these antibodies provided direct visual evidence for the marked induction of polypeptide PPA-80 and enoyl-CoA hydratase in the livers of rats treated with Wy-14,643. The present studies also provide immunocytochemical evidence for the localization of polypeptide PPA- 80 and the heat-labile enoyl-CoA hydratase in the peroxisome, but not in the mitochondria, of hepatic parenchymal cells. These studies, therefore, provide morphological evidence for the existence of fatty acyl-CoA oxidizing system in peroxisomes. An increase of polypeptide PPA-80 on SDS polyacrylamide gel electrophoretic analysis of the subcellular fractions of liver of rodents treated with lipid-lowering drugs should serve as a reliable and sensitive indicator of enhanced peroxisomal β- oxidation system.     

l-Phenylalanine stereospecifically inhibits the renaturation of muscle pyruvate kinase

Bovine type M pyruvate kinase can be reversibly denatured by solutions of guanidine HCl. Subsequent dilution of the enzyme into buffer containing β-mercaptoethanol or dithiothreitol results in recovery of enzymatic activity with an average half-time of 17 min at 16 °C. The addition of 1 mm l-phenylalanine increases the average half-time for recovery of enzymatic activity to 26 min, while 8 mm l-phenylalanine further increases this value to 46 min. Tyrosine and tryptophan also inhibit the reactivation but to a lesser extent than phenylalanine. Neither l-alanine, l-valine, d-phenylalanine, phosphoenolpyruvate, nor fructose 1,6-bisphosphate have any appreciable effect on activity recovery rates, either in the presence or absence of l-phenylalanine. Phenylpyruvate is a very potent inhibitor of reactivation. The addition of 5 mm phenylpyruvate increases the half-time to 57 min. The evidence presented in this paper supports the hypothesis that an l-phenylalanine-binding site which probably is distinct from the catalytic site is formed early in the renaturation process. l-Phenylalanine binds to this site and inhibits two first-order relaxations that are rate limiting for the reactivation and that have the following rate constants: 8.76 × 10^?2 and 1.24 × 10^?2 min^?1, respectively, in the absence of phenylalanine and 3.04 × 10^?2 and 7.63 × 10^?3min^?1, respectively, in the presence of 8.0 mm phenylalanine. We presume these first-order processes to be transconformational steps in the reactivation process.     

The absence of introns within a human fibroblast interferon gene.

Experiments in which immobilised restriction fragments of genomic DNA were hybridised with a cloned human fibroblast interferon cDNA indicate that the homologous chromosomal genes exist in only one basic arrangement. This is in marked contrast to recent studies by Nagata et al. (1) showing that there are at least eight gene arrangements for human leukocyte interferon. Having isolated a chromosomal human fibroblast interferon gene from a gene bank, we conclude from nucleotide sequencing studies that there is a complete absence of introns within the RNA-coding region. In view of a similar observation recently made for a human leukocyte interferon gene (1), it would appear as if interferon genes in general are unlike the vast majority of eukaryote genes in this respect.     

Isolation of thioesterase and acyl carrier protein activities liberated by elastase digestion of pigeon liver fatty acid synthetase

Proteolysis of pigeon liver fatty acid synthetase with elastase cleaves the thioesterase component and an acyl carrier protein-containing peptide from the multienzyme complex. These proteins are then separated in one step by gel filtration on a Sephadex G-75 column. Each of the eluted proteins is homogeneous, as determined by polyacrylamide gel electrophoresis. The molecular weight of each has been estimated to be 36,000 and 12,000 daltons, respectively.     

Specialized transduction with lambda plac5: dependence on recB.

Genetically disabled lambda plac5 transducing phage derivatives were used to study the recB dependence of recombination during specialized transduction. The frequency of transduction was normalized to colony-forming units, and the end product of recombination was monitored by scoring for addition and substitution transductants. When a chromosomal lac gene was the recipient DNA substrate molecule, both the normalized transduction frequency and the proportion of addition and substitution transductants showed essentially no recB dependence. There was a pronounced recB dependence for both normalized transduction frequency and recombination end product formation when F42 lac was the recipient DNA substrate. recB appears to have no significant role in the recombination that occurs between the two lac regions in an addition transductant. UV irradiation of the transducing phages increased the absolute level of both addition and substitution transductants obtained with a chromosomal lac gene but resulted in a considerable change in the relative frequency of addition versus substitution transductants.     

A test for the intermediacy of 11-hydroperoxyeicosa-5,8,12,14-tetraenoic acid [11-HPETE] in prostaglandin biosynthesis

11-Hydroperoxy-eicosa-5,8,12,14-tetraenoic acid [11-HPETE] was prepared by chromatographic separation of the hydroperoxides formed from the singlet oxygen oxidation of arachidonic acid [20:4]. 1-[¹⁴C]-HPETE was incubated with prostaglandin endoperoxide synthetase preparations from ram seminal vesicles. No prostaglandins products deriving from 11-HPETE were detected in any of the incubations. 11-Hydroxy-eicosa-5,8,12,14-tetraenoic acid [11-HETE], formed by the action of the hydroperoxidase component of prostaglandin endoperoxidase synthetase was the major product formed. The peroxidase activity was absolutely dependent on epinephrine and was stimulated by hematin. 11-HPETE does not appreciably effect the extent of conversion of arachidonic acid into prostaglandin.     

Liposome-mediated transfer of integral membrane glycoproteins into the plasma membrane of cultured cells

Cultured mouse 3T3 cells treated with phosphatidylserine or phosphatidylserine/phosphatidylcholine (3: 7 mole ratio) liposomes containing ortho- and paramyxovirus envelope glycoproteins become susceptible to killing by virus-specific cytotoxic T lymphocytes indicating that the liposome-derived glycoproteins have been inserted into the cellular plasma membrane. Cells incubated with liposomes of similar lipid composition containing viral antigens plus a dinitrophenylated lipid hapten were killed by both virus- and hapten-specific T lymphocytes indicating that both protein and lipid components are inserted into the plasma membrane. We consider that assimilation of liposome-derived antigens into the plasma membrane results from fusion of liposomes with the plasma membrane. Cells incubated with phosphatidylcholine liposomes containing lipid haptens and viral glycoproteins were not killed by cytotoxic lymphocytes indicating that liposomes of this composition do not fuse with the plasma membrane. Liposome-derived paramyxovirus glycoproteins inserted into the plasma membrane retain their functional activity as shown by their ability to induce cell fusion. These experiments demonstrate the feasibility of using liposomes as carriers for introducing integral membrane (glyco)proteins into the plasma membrane of cultured cells and establish a new approach for studying the role of individual (glyco)proteins in the expression of specific cell surface properties.     

The Golgi apparatus in epidermal mucoid and ellipsoid-vacuolate cells ofAeolidia papillosa andCoryphella rufibranchialis (Nudibranchia)

Summary The epidermal cell layer of the apical end of the ceras was investigated in two species of aeolid nudibranchs. Based on cellular inclusions, mostly two cell types were found: mucoid and ellipsoid-vacuolate cells. Mucoid cells ofCoryphella rufibranchialis have large heterogeneous and fibrillar secretory granules whereas inAeolidia papillosa, the granules are homogeneous, but vary in electron density from one cell to another. Ellipsoid-vacuolate cells contained large quantities of small vacuoles with an included ellipsoidal structure. Both species contained very numerous ellipsoid-vacuolate cells. Secretory granules and ellipsoid-vacuoles appear to arise from the Golgi apparatus and these contents stain with PAS, suggesting a polysaccharide composition. Mucoid cells contained both secretory granules and ellipsoid-vacuoles which may arise from the same Golgi apparatus.     

A critical stage in the formation of acid mine drainage: Colonization of pyrite by Acidithiobacillus ferrooxidans under pH-neutral conditions

A dominant Acidithiobacillus ferrooxidans ssp. was isolated from the supergene copper deposit in Morenci, Arizona, USA. Washed bacterial suspensions (10⁸ MPN per treatment), in pH‐neutral buffer, were inoculated onto pyrite cubes for 24 h. Heterogeneous bacterial absorption onto the pyrite removed approximately 90% of the viable bacteria from the inoculum. At T = 0, the bacteria were observed primarily in regions enriched in phosphorus. Over 30 days, the bacterial population on the pyrite cubes increased from 1.3 × 10⁷ to 2.9 × 10⁸ bacteria cm^?2. During this growth stage, low levels of thiobacilli (228 ± 167 MPN mL^?1) were also recovered from the fluid phase; however, this population decreased to zero within 30 days. Growth on pyrite occurred as micrometre‐scale planar microcolonies, a biofilm, coating the mineral surfaces. These microcolonies possessed viable thiobacilli, even after 4 months at ‘circumneutral pH’. Imaging the pyrite cubes using SEM‐EDS and scanning force microscopy demonstrated that the thiobacilli grew as iron oxy‐hydroxide‐cemented cells, leading to the formation of mineralized microcolonies. Removing the iron oxy‐hydroxides with oxalic acid did not dislodge the bacteria, demonstrating that the secondary minerals were not responsible for ‘gluing’ the bacteria to the pyrite surface. Removing organic material, i.e. the cells, by an oxygen plasma treatment revealed the presence of corrosion pits the size and shape of bacteria. Because of the inherent geochemical constraints on pyrite oxidation at neutral pH, the colonization of pyrite under circumneutral pH conditions must be facilitated by the development of an acidic nanoenvironment between the bacteria and the pyrite mineral surface.