Hydrocarbon uptake in hydrocarbon fermentations

Candida lipolytica (strain ATCC 8662) was grown on a simple defined medium with n-hexadecane as the main carbon Source under batch fermentation conditions. The relative importance of the cells growing in the aqueous phase on the overall kinetics was studied. The effect of interfacial tension, unoccupied interfacial area, and pseudosolubility on the specific growth was also studied. Results are presented and discussed here.     

Identification and design of a novel series of MGAT2 inhibitors

[Acyl CoA]monoacylglycerol acyltransferase 2 (MGAT2) is of interest as a target for therapeutic treatment of diabetes, obesity and other diseases which together constitute the metabolic syndrome. In this Letter we report our discovery and optimisation of a novel series of MGAT2 inhibitors. The development of the SAR of the series and a detailed discussion around some key parameters monitored and addressed during the lead generation phase will be given. The in vivo results from an oral lipid tolerance test (OLTT) using the MGAT2 inhibitor (S)-10, shows a significant reduction (68% inhibition relative to na?ve, p <0.01) in plasma triacylglycerol (TAG) concentration.     

Post-translational processing of p21ras is two-step and involves carboxyl-methylation and carboxy-terminal proteolysis.

We have studied the post-translational processing of p21ras proteins. The primary translation product pro-p21 is cytosolic and is rapidly converted to a cytosolic form (c-p21) of higher mobility on SDS-PAGE. c-p21 is converted in turn to the membrane-bound mature palmitoylated form (m-p21) of slightly higher mobility. These processing steps are accompanied by increases in isoelectric point and in hydrophobicity as judged by Triton X-114 partitioning. Although the increases in electrophoretic mobility and hydrophobicity precede acylation we show that mutation of Cys186, which has been shown to block acylation, also abolishes the pro-p21 to c-p21 conversion. Thus the Cys186 residue is involved in the processing steps prior to acylation. We have identified two processing events which contribute to the pro-p21 conversion. Site-directed mutagenesis to insert tryptophan, which is not present in the wild type, followed by metabolic labelling with [3H]tryptophan has allowed us to map a proteolytic processing event which removes the three C-terminal residues. In addition, both the c-p21 and m-p21 forms are carboxyl-methylated. Approximately one methyl group is incorporated per molecule of p21 at steady state, which can partially account for the increase in isoelectric point. Unlike palmitate, methyl group turnover is not observed.     

Characterization of a DNA binding protein of bacteriophage PRD1 involved in DNA replication.

Escherichia coli phage PRD1 protein P12, involved in PRD1 DNA replication in vivo, has been highly purified from E. coli cells harbouring a gene XII-containing plasmid. Protein P12 binds to single-stranded DNA as shown by gel retardation assays and nuclease protection experiments. Binding of protein P12 to single-stranded DNA increases about 14% the contour length of the DNA as revealed by electron microscopy. Binding to single-stranded DNA seems to be cooperative, and it is not sequence specific. Protein P12 also binds to double-stranded DNA although with an affinity 10 times lower than to single-stranded DNA. Using the in vitro phage phi 29 DNA replication system, it is shown that protein P12 stimulates the overall phi 29 DNA replication.     

Isolation and characterization of phage F9-11 from a lysogenicDeleya halophila strain

Thirty-eight strains ofDeleya halophila species were examined for production of phage after mitomycin C induction. Thirty-two of them were able to inhibit growth of some other strains. Phage F9-11, isolated fromD. halophila strain F9-11, showed an isometric head and a noncontractile tail. The effects of salt concentrations variation on the stability and replication of this phage were established. Its replication was possible at a wide range of marine salt concentrations, from 2.5% to 15% (wt/vol). Stability seems to be influenced by osmolarity of medium rather than by NaCl level. The euryhaline character showed by F9-11 phage is evoked as an important factor for the survival of this phage in its environment.     

Successional pathways of Mediterranean evergreen vegetation on Sicily

The Mediterranean evergreen vegetation of Sicily, comprised in the belt of the Quercetea ilicis, occupies a large part of the island. Human intervention (cutting, fire, pasture) has brought about a degradation of the natural vegetation. This study is based on our phytosociological research of the Quercetea ilicis belt on Sicily.

With the ‘habitat comparison’ method, the dynamical relations between the different vegetation units have been defined.

We distinguish the following stages, with reference to their vegetation structure:

• a herbaceous stage formed by steppic vegetation, preceded by various types of nitrophilous-ruderal vegetation on abandoned fields;

• a garrigue stage dominated by half-shrubs;

• a macquis stage with various distinct plant communities, four communities being important in regressive successions, and three in progressive ones;

• a woodland and shrub-woodland stage with three different substages: pre-existent forests, present woodlands, and woodlands which tend towards the final, stable stage of vegetation (potential natural vegetation).

The dynamic relationships both in progressive and regressive successions have been synthesized in a scheme. In this scheme we have shown the main stages of the vegetation in their dynamics and we have constructed different series of vegetation types in two altitudinal belts, which are determined by varying environmental conditions of today.

The results also show that in some cases the progressive series follow different pathways than the regressive series, and the final stage of the progressive series is different from the original vegetation.

     

Autolysis of cell walls in pea epicotyls during growth. Enzymatic activities involved

Pisum sativum L. (cv. Lincoln) epicotyl cell walls show autohydrolysis and release into the incubation medium up to 120 μg of sugar per mg of cell wall dry weight in 30 h. Cell walls from younger epicotyls with high growth capacity showed higher auto-lytic capacity than older epicotyls. This suggests that both processes, growth and au-tolysis, are related. The proteins responsible for autolysis were extracted from the wall fraction with high saline solution (3 M LiCl) and enzymatic activities associated with the proteins were studied. The highest activity corresponded to α-galactosidase; lower activities were found for β-galactosidase, a-arabinosidase and exoglucanase. Changes in enzymatic activities and changes in the proportion of sugars released in autolysis by cell walls during the growth of epicotyls support the notion that α-galac-tosidase is one of the enzymes involved in the process of autolysis, and that the liberation of arabinose and galactose in this process occurs as arabinogalactan.     

Some cytochemical studies on the cell surface ofAmphidinium carterae (Dinophyceae)

Summary The surface coat of the dinoflagellateAmphidinium carterae Hulburt was examined by fluorescence and transmission electron microscopy, using various fluorochromes and cationic dyes. The overall results showed cell-surface reactions typical of acid mucopolysaccharides. The cationic dye staining revealed an outer fine fibrillar layer (15–70 nm thick) overlying a dense anionic coat (40–60 nm thick) which appeared to thicken progressively with age. In general, the structure of the amphiesmal vesicles was similar to that previously described by other investigators. However, an acidic mucopolysaccharide layer was observed on the inner surface of these vesicles. Each of these structures is traversed by 1–3 pores and at least 2 types of extrusomes are formed, the spindle trichocysts and the mucocysts. Cell to cell adhesion through the surface coat was frequently observed. Evidence was also obtained for internalization of all the surface-coat markers used.This investigation forms part of a doctoral thesis submitted by the first author to the University of British Columbia, Vancouver, B.C.     

Multiple Molecular Forms of Enkephalins in the Guinea Pig Hippocampus

Abstract: The combined techniques of HPLC and radioimmunoassay were used to identify and quantitate enkephalin-related peptides in the guinea pig hippocampus. Both met- and leu-enkephalin were identified, in approximately a 2:1 ratio, as well as a third enkephalin-like molecule that is neither met- nor leu-enkephalin. The third enkephalin elutes earlier than met- or leu-enkephalin from a reversed-phase column, has a molecular weight similar to the other enkephalins, and is as active as these enkephalins are in inhibiting binding of labeled opiates to rat brain membranes. All regions of the hippocampus (dentate gyrus, CA1–2, CA3–4, and subiculum) contain all three immunoreactive peptides. Immunocytochemical techniques, using antisera raised against met-enkephalin, show with one antiserum immunoreactivity in the granule cell-mossy fiber system, and with the other scattered immunoreactive cells mostly in the CA2 region. Enkephalins are not confined to the mossy fiber system, as previously suggested, but may be a component of another hippocampal innervation.