Protection of Mice against Lethal Coxsackievirus B3 Infection by Using DNA Immunization

Vaccination with DNA and recombinant vaccinia viruses (rec.VV) has been studied with the coxsackievirus B3 (CVB3) model system. Plasmids encoding all structural proteins of CVB3, when injected intramuscularly, induced only low levels of virus-specific antibodies. However, DNA vaccination with the major structural protein VP1 protected 72.2% of mice from lethal challenge, whereas VP1 expressed by rec.VV was much less efficient.     

Monthly variations in drug-induced gastric ulcers in rats

Clinical evidence suggests that there may be some relationship between the occurrence of peptic ulcers and the season of the year. As little experimental work has been carried out on this subject, three drugs commonly used to induce experimental ulcers in rats (acetylsalicylic acid, 300 mg/kg; phenylbutazone, 200 mg/kg; reserpine, 10 mg/kg) were tested every month for one year under standardised experimental conditions (T_a, RH, LD 12:12). In rats given phenylbutazone the maximum area of ulceration was found in October and December, and in rats given acetylsalicylic acid in February and March. In rats given reserpine, there were no significant monthly variations. An influence of climatic factors on ulcer induction cannot be completely excluded. Endogenous conditions might also account for the monthly differences in ulceration.     

Migration and proliferation of primordial germ cells in the rat

Information about early primordial germ cell (PGC) formation and migration in rats is lacking. In utero developed and in vitro cultivated whole rat embryos were studied on days 10-13 postcoitum (p.c.). The development of the PGCs was investigated in serial sections stained for alkaline phosphatase activity. On postcoital day 10, PGCs were found in the invaginating visceral yolk sac endoderm and at the base of the allantois. At day 11 p.c. PGCs were mostly found in the ventral and lateral gut wall or in the mesenchyme between the gut and the future genital ridges. At day 12 p.c. most of the PGCs (94%) could be localised in the mesenchyme or in the future genital ridges. On postcoital day 13 almost all PGCs had reached the now-well-developed genital ridges. Quantitative measurements showed an increase in the number of PGCs from 84 at day 10 p.c. up to 2,768 at day 13 p.c. Only slight differences were found between in vivo and in vitro embryos with respect to the number of PGCs and their developmental pattern. The in vitro culture of whole rat embryos enables the discrimination between the effects of indirect (maternal) and direct action of PGC-toxic agents.     

Differentiation of vocalizations in bushbabies (Galaginae, Prosimiae, Primates) and the significance for assessing phylogenetic relationships

A comparative bioacustic analysis of vocalizations of the prosimian subfamily Galaginae revealed that morphologically similar sibling taxa within the main groups of the lesser galagos and the greater galagos can be reliably identified phenotypically on the basis of the acoustic structure of their loud call or advertisement call. Results confirm the separation of two distinct species of greater galagos, Galago crassicaudatus and Galago garnettii, and strongly suggest the discrimination of three distinct species from the senegalensis lesser bushbaby group, Galago senegalensis, Galago moholi and Galao zanzibaricus. An investigation of the ontogenetic development of the loud call indicated that it is derived from the infant's isolation call, displaying in all studied bushbaby taxa a fairly similar acoustic pattern. Shared acoustic characters of the loud call among the different taxa as well as the infant's isolation call were used to propose a hypothesis about the phylogenetic affinities in bushbabies. The results seem to be supported by recent fossil records.     

Limited Tryptic Proteolysis of the Benzodiazepine Binding Proteins in Different Species Reveals Structural Homologies

Peptide mapping can be used to elucidate further the structural similarities of the benzodiazepine binding proteins in different vertebrate species. Crude synaptic membrane preparations were photoaffinity-labeled with [3H]flunitrazepam and subsequently degraded with various concentrations of trypsin. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by fluorography allowed a comparison of the molecular weights of photolabeled peptides in different species. Tryptic degradation led to a common peptide of 40K in all species investigated, a finding indicating that the benzodiazepine binding proteins are structurally homologous in higher bony fishes and tetrapods.     

Identification and characterization of yeast mutants and the gene for a cruciform cutting endonuclease.

An assay was developed that detected DNA cruciform cutting endonuclease activity in crude extracts of Saccharomyces cerevisiae. A collection of temperature-sensitive strains was screened using this assay, and a mutant lacking the activity was found. The mutation leading to the enzymatic defect was mapped to the left arm of chromosome XI within 3 cM of the centromere. Cloning of the gene for this endonuclease was achieved by chromosome walking from the nearby PUT3 locus. The gene, called CCE1 (cruciform cutting endonuclease), was sequenced and found to have an open reading frame encoding a 41 kDa protein. The amino acid sequence of this eukaryotic endonuclease shows homology neither to its prokaryotic counterparts nor to other proteins in available databases. A cce1 null mutant has no obvious growth defect, and despite the ability of the CCE1 enzyme to cleave Holliday junction analogs, the mutant shows no defect in meiotic or mitotic recombination. A second cruciform cutting activity was detected in extracts from a cce1 null mutant, indicating that yeast has at least two such enzymes. The only phenotype observed for cce1 mutants is a higher than normal frequency of appearance of petite cells, suggesting that the CCE1 protein is important for the maintenance of mitochondrial DNA.     

Endonuclease VII resolves Y-junctions in branched DNA in vitro.

Endonuclease VII (gp 49 of phage T4) resolves four-way junctions in branched DNAs. We have extended our investigations of the specificity of endo VII and tested its activity with three-way junctions (Y-structures) constructed in vitro. Both 'closed' and 'open' Y-structures were made, absolutely identical in sequence but differing from each other by a single nick in one of the three arms. Pure Y-structures were obtained on a preparative scale by annealing plus and minus strands from two M13mp strains. One strain has an inverted repeat of 2 X 31 nucleotides cloned into the single EcoRI site while in the other strain this repeat is absent. The structures were used in reactions with endo VII, which recognizes the branch point of both structures and introduces a characteristic number of nicks, 3' to the junction in each arm of the structure. Strong and weak sites could be distinguished and the cleavage pattern differed significantly between the two structures. The observed resolution of Y-junctions by endo VII in vitro is compatible with a model for the resolution of recombinant Y-branches in DNA.     

Evolution of a New Gene Substituting for the leuD Gene of Salmonella typhimurium: Characterization of supQ Mutations

Alpha-isopropylmalate isomerase, the second specific enzyme in the biosynthesis of leucine, is coded for by two genes, leuC and leuD. Leucine auxotrophs, harboring leuD mutations including a deletion of the entire leuD gene, revert to leucine prototrophy owing to mutations at a locus, supQ, substantially distant to the leucine operon. A large number of independently isolated supQ mutations were characterized. A significant increase in the spontaneous frequency of supQ mutations was found after mutagenesis with 2-aminopurine, N-methyl-N′-nitro-N-nitrosoguanidine, diethyl sulfate, and nitrous acid. The supQ function in most of these strains is temperature sensitive, resulting in more efficient suppression with decreasing temperature. At higher temperatures, the supQ limits the growth rate of leuD supQ mutant strains. All supQ mutations are co-transducible with proA and proB, with co-transduction frequencies ranging from 5.4 to 99.9% for different supQ mutations. Many supQ mutations were isolated, especially after nitrous acid mutagenesis, that had acquired a simultaneous proline requirement. The data support the idea of two genes, supQ and newD, whose protein products form a complex. The newD gene product, without any genetic alteration, is capable of substituting for the missing leuD protein. However, mutations in the supQ gene (point mutations or deletions) are necessary to make the newD protein available, which is normally tied up in a complex with the supQ protein.     

High activity of choline acetyltransferase induced in neuroblastoma X glia hybrid cells

Hybrids were made between rat glioma X mouse neuroblastoma cell lines and were examined for the specific activities of choline acetyltransferase and acetylcholinesterase. The specific activities of choline acetyltransferase of the hybrids were as high as those in normal brain, whereas neither parent line showed appreciable activities. The electrical excitability of the neuroblastoma cells was retained in the hybrids.