Optimisation of fermentation conditions for the production of a novel GABA-benzodiazepine receptor agonist byAcremonium strictum

The production of XR368, a novel GABA-benzodiazepine receptor agonist, has been optimised through manipulation of the medium composition and fermentation conditions leading to an increase in product titre from 1 to 100 mg L^–1. Key steps in the optimisation process were the selection of carbon and nitrogen sources, and the optimisation of the CN ratio and medium concentration. Furthermore, downstream processing has been facilitated through the introduction of a detergent treatment step which results in the release of over 90% of the desired product into the extracellular environment, avoiding the need to process both biomass and liquor fractions.     

Brucella abortus conjugated with a gp120 or V3 loop peptide derived from human immunodeficiency virus (HIV) type 1 induces neutralizing anti-HIV antibodies, and the V3-B. abortus conjugate is effective even after CD4+ T-cell depletion.

Human immunodeficiency virus type 1 (HIV-1) infection is associated with loss of function and numbers of CD4+ T-helper cells. In order to bypass the requirement for CD4+ cells in antibody responses, we have utilized heat-inactivated Brucella abortus as a carrier. In this study we coupled a 14-mer V3 loop peptide (V3), which is homologous to 9 of 11 amino acids from the V3 loop of HIV-1 MN, and gp120 from HIV-1 SF2 to B. abortus [gp120(SF2)-B. abortus]. Our results showed that specific antibody responses, dominated by immunoglobulin G2a in BALB/c mice, were induced by these conjugates. Sera from the immunized mice bound native gp120 expressed on the surfaces of cells infected with a recombinant vaccinia virus gp160 vector (VPE16). Sera from mice immunized with gp120(SF2)-B. abortus inhibited binding of soluble CD4 to gp120, whereas sera from mice immunized with V3-B. abortus were ineffective. Sera from mice immunized with either conjugate were capable of blocking syncytium formation between CD4+ CEM cells and H9 cells chronically infected with the homologous virus. Sera from mice immunized with gp120(SF2)-B. abortus were more potent than sera from mice immunized with V3-B. abortus in inhibiting syncytia from heterologous HIV-1 laboratory strains. Importantly, in primary and secondary responses, V3-B. abortus evoked anti-HIV MN antibodies in mice depleted of CD4+ cells, and sera from these mice were able to inhibit syncytia. These findings indicate that B. abortus can provide carrier function for peptides and proteins from HIV-1 and suggest that they could be used for immunization of individuals with compromised CD4+ T-cell function.     

Survival of Campylobacter jejuni in foods and comparison with a predictive model

Campylobacter jejuni was inoculated into a range of raw and cooked foods and survival determined during storage at 20°, 10° and 20°C for up to 56 d. To facilitate easy enumeration, two antibiotic-resistant strains of Camp. jejuni , which had similar survival characteristics to the parent strain, were used. Campylobacter jejuni survived for longer at lower temperatures in all foods and inactivation was most rapid in pâté. There was generally good agreement between the survival data and predictions from a Camp. jejuni survival model (Food MicroModel).     

Probing the molecular mechanism of action of co-repressor in the E. coli methionine repressor-operator complex using surface plasmon resonance (SPR).

We have studied quantitatively the effect of the corepressor, S-adenosylmethionine (SAM), on the interaction between the E. coli methionine repressor, MetJ, and an idealised operator fragment, by recording measurements of surface plasmon resonance using a BIAcore instrument. We have recorded kinetic binding data in the presence of SAM, which carries a net positive charge, and two corepressor analogues, adenosylornithine (AO) and aza-SAM, which differ in the location of the atom carrying the positive charge. Our data support the hypothesis that the effect of the corepressor is electrostatic in origin. The difference in electrostatic interaction energy between the SAM- and AO-repressor-operator complexes of approximately 3.5 kJ/mol calculated from the known three-dimensional structure is within the range of our experimentally determined values of 2.8-4.3 kJ/mol. These results illustrate the potential of SPR measurements for studying protein-nucleic acid interactions.     

High copy number of highly similar mariner-like transposons in planarian (Platyhelminthe): evidence for a trans-phyla horizontal transfer

Several DNA sequences similar to the mariner element were isolated and characterized in the platyhelminthe Dugesia (Girardia) tigrina. They were 1,288 bp long, flanked by two 32 bp-inverted repeats, and contained a single 339 amino acid open-reading frame (ORF) encoding the transposase. The number of copies of this element is approximately 8,000 per haploid genome, constituting a member of the middle- repetitive DNA of Dugesia tigrina. Sequence analysis of several elements showed a high percentage of conservation between the different copies. Most of them presented an intact ORF and the standard signals of actively expressed genes, which suggests that some of them are or have recently been functional transposons. The high degree of similarity shared with other mariner elements from some arthropods, together with the fact that this element is undetectable in other planarian species, strongly suggests a case of horizontal transfer between these two distant phyla.      

Assessing horizontal transfer of nifHDK genes in eubacteria: nucleotide sequence of nifK from Frankia strain HFPCcI3

The structural genes for nitrogenase, nifK, nifD, and nifH, are crucial for nitrogen fixation. Previous phylogenetic analysis of the amino acid sequence of nifH suggested that this gene had been horizontally transferred from a proteobacterium to the gram-positive/cyanobacterial clade, although the confounding effects of paralogous comparisons made interpretation of the data difficult. An additional test of nif gene horizontal transfer using nifD was made, but the NifD phylogeny lacked resolution. Here nif gene phylogeny is addressed with a phylogenetic analysis of a third and longer nif gene, nifK. As part of the study, the nifK gene of the key taxon Frankia was sequenced. Parsimony and some distance analyses of the nifK amino acid sequences provide support for vertical descent of nifK, but other distance trees provide support for the lateral transfer of the gene. Bootstrap support was found for both hypotheses in all trees; the nifK data do not definitively favor one or the other hypothesis. A parsimony analysis of NifH provides support for horizontal transfer in accord with previous reports, although bootstrap analysis also shows some support for vertical descent of the orthologous nifH genes. A wider sampling of taxa and more sophisticated methods of phylogenetic inference are needed to understand the evolution of nif genes. The nif genes may also be powerful phylogenetic tools. If nifK evolved by vertical descent, it provides strong evidence that the cyanobacteria and proteobacteria are sister groups to the exclusion of the firmicutes, whereas 16S rRNA sequences are unable to resolve the relationships of these three major eubacterial lineages.      

Saskatchewan dial-access drug information service.

In September 1974 the colleges of pharmacy and medicine of the University of Saskatchewan began offering a drug information service to the pharmacists and physicians of Saskatchewan without charge. With the help of a radio-page system, calls are taken immediately by experienced pharmacists and pharmacologists. The cost of long-distance phone calls is borne by grants from the Saskatchewan medical and pharmaceutical associations. During the 1st year of operation 415 requests for information were received. Of 93 persons who called up to Feb. 28, 1975, 76% responded to an evaluation questionnaire; virtually all described the service as very valuable. The information received resulted in the alteration of drug therapy in one third of calls requesting information to assist in current treatment of a patient.     

The Biology of Gregarina fernandoi n. sp. in the Cockroach Pysnoscelus surinamensis with Observations on its Development and Cytochemical Nature

SYNOPSIS. Gregarina fernandoi n. sp. is a eugregarine. Its structure, development and life history in the gut of the cockroach Pycnoscelus surinamensis are described. It is named as a new species on the basis of its size, nuclear structure, structure and form of the gametocyst and oocyst. Observations were made on the different stages of the parasite and related to the pH of the gut. In the ceca, pH 4.5–5, the parasite was in its early stages of development, in the midgut, pH 6.5–7, it was in syzygy and in the rectum, pH 7.5–8, gametocysts were found.