A spatio-temporal analysis of a New Zealand flatworn (Arthurdendyus triangulatus) population in western Scotland

The New Zealand flatworm (Arthurdendyus triangulatus), which is an obligate predator of native earthworms, is an alien species to the British Isles and is widely distributed in Scotland. What little is known about its biology under field conditions is mainly from Northern Ireland. Samples taken from single sampling dates have shown A. triangulatus to have an aggregated distribution. To determine the spatio‐temporal distribution of A. triangulatus, a grass field in western Scotland was intensively sampled over a 16‐month period. Data indicate an increase in flatworm numbers and seasonal trends in body weight, the appearance of egg capsules and hatchlings. Results also showed that spatially, the flatworms were aggregated, but this was a transient phenomenon over the period of the experiment. The distribution of egg capsules in the study area was strongly aggregated and related to the appearance of hatchlings. Flatworms may aggregate in areas where soil moisture is optimal for the survival of the New Zealand flatworm.     

Cloning and complete sequence of an HLA-A2 gene: analysis of two HLA-A alleles at the nucleotide level

The gene for the HLA-A2 antigen has been cloned from the human lymphoblastoid cell line 721. Comparison of this sequence with the published sequence for HLA-A3 permits the examination of two alleles at the extremely polymorphic HLA-A locus. A high degree of sequence conservation was seen in both coding and noncoding DNA, 97.2% and 94.5%, respectively. Interestingly, the 3' untranslated region was the most conserved, with 99.5% homology. The polymorphism of the HLA-A antigens results from a high proportion of amino acid substitutions relative to the total nucleotide changes in exons 2 and 3. Unlike the clustered differences seen in this region on comparison of two H-2K alleles of mouse, nucleotide substitutions between the HLA-A2 and A3 alleles are evenly distributed. Substitutions at silent sites and within introns were used to calculate an intra-allelic divergence time of at least 10 to 15 million years for these two HLA-A alleles.     

Dinitropyrene-resistant Salmonella typhimurium are deficient in an acetyl-CoA acetyltransferase

Salmonella typhimurium strain TA98NR which is sensitive to 1,8-dinitropyrene mutagenesis possesses acetyl-CoA dependent acetyltransferase activity, while a strain selected for resistance to 1,8-dinitropyrene (TA98/1, 8-DNP6) is deficient in this activity. Acetyltransferase competent strains can acetylate 1,8-diaminopyrene, forming 1-N-acetylamino-8-aminopyrene and 1,8-N,N'-diacetyldiaminopyrene. The coincidence of dinitropyrene resistance and acetyltransferase deficiency implicates acetylation as an important process in the metabolic activation of dinitropyrene to a mutagenic intermediate.     

Mutagenic repair in Escherichia coli. VIII. Effect of gyrB mutations on ultraviolet light mutagenesis

Introduction into Escherichia coli WP2 bacteria of a mutation in the gyrB locus previously shown to reduce the degree of chromosomal superhelicity caused a small decrease in the frequency of UV-induced mutations to streptomycin resistance (but not significantly) and to tryptophan independence (mostly ochre suppressors) in excision repair-proficient bacteria. It did not influence the 'broth effect' or the rate or extent of 'mutation frequency decline' of suppressor mutations. In an excision-deficient (uvrA 155) background the yield of UV-induced streptomycin-resistant mutations was lower in gyrB bacteria at all doses; the yield of tryptophan-independent mutations was slightly lower at low doses and slightly higher at high doses. In both excision-proficient and -deficient bacteria the yield of UV-induced mutations to rifampicin resistance was apparently lower in gyrB mutants but this could be due at least in part to a hypersensitivity of some Rifr gyrB bacteria to UV. The number of spontaneous tryptophan-independent mutations was lower in gyrB bacteria but this was almost certainly due to their poorer viability on tryptophan-limiting plates and not to a lower spontaneous mutation rate. In a temperature-sensitive presumed gyrase-deficient strain a small decrease in mutant yield at low doses was observed following incubation at restrictive temperature before UV. This was ascribed to an enhancement of excision repair. Our failure to find any significant effect of gyrB mutations does not support the hypothesis that hairpin formation (which should be dependent on a high degree of superhelicity) is involved in determining the 'broth effect', 'mutation frequency decline' or the probability that a mutation will occur spontaneously. Dramatic effects of superhelicity on UV mutagenesis also seem to be unlikely.     

Synthesis and rapid purification of UDP-[6-3H]galactose

UDP[6-3H]galactose of high specificity can be obtained by oxidation of the C-6 hydroxymethyl group of UDP-galactose by galactose oxidase and subsequent reduction by sodium borotritide. One-step purification of the nucleotide sugar involves anion-exchange chromatography on a Pharmacia Mono Q column. Radiolabeled UDP-N-acetylgalactosamine can also be synthesized and purified by this procedure. Both nucleotide sugars can be used for sugar incorporation studies using the appropriate glycosyltransferase.     

Identification of the gene encoding the 65-kilodalton DNA-binding protein of herpes simplex virus type 1.

Hybrid arrest of in vitro translation was used to localize the region of the herpes simplex virus type 1 genome encoding the 65-kilodalton DNA-binding protein (65KDBP) to between genome coordinates 0.592 and 0.649. Knowledge of the DNA sequence of this region allowed us to identify three open reading frames as likely candidates for the gene encoding 65KDBP. Two independent approaches were used to determine which of these three open reading frames encoded the protein. For the first approach a monoclonal antibody, MAb 6898, which reacted specifically with 65KDBP, was isolated. This antibody was used, with the techniques of hybrid arrest of in vitro translation and in vitro translation of selected mRNA, to identify the gene encoding 65KDBP. The second approach involved preparation of antisera directed against oligopeptides corresponding to regions of the predicted amino acid sequence of this gene. These antisera reacted specifically with 65KDBP, thus confirming the gene assignment.     

Compositional and Thermal Properties of Thylakoid Polar Lipids of Nerium oleander L. in Relation to Chilling Sensitivity

The polar lipid classes from thylakoids of Nerium oleander L. were studied with the aim of relating changes in their composition and thermal behavior with reported changes in the transition temperature of their polar lipids and chilling sensitivity of their leaves. With an increase in growth temperature, the transition temperature of phosphatidylglycerol increased from 16°C to 26°C, and for sulfoquinovosyldiacylglycerol from 19°C to 24°C. Transitions in the other lipid classes were below −10°C for plants grown at both growth temperature. The major changes in the molecular species of phosphatidylglycerol, with increasing growth temperature, were an increase in 1-oleoyl-2-palmitoyl phosphatidylglycerol from 21 to 39% and a decrease in 1-oleoyl-2-trans-3-hexadecanoic phosphatidylglycerol from 51 to 25%. Although the disaturated species increased from 8 to 23%, the maximum was less than that reported for chilling-sensitive plants. There was no change in the sum of the palmitic, hexadeca-trans-3-enoic and stearic acids. Dipalmitoyl sulfoquinovosyldiacylglycerol increased from 12 to 20% and 1-linolenoyl-2-palmitoyl sulfoquinovosyldiacylglycerol decreased from 40 to 30%. It is concluded that the increase in the transition temperature of the polar lipids and the sensitivity of acclimated oleander plants to chilling could not be predicted by the absolute sum of the saturated fatty acids or disaturated molecular species in phosphatidylglycerol. The polar lipid transition appears to be a product of mixing of both high and low melting-point lipids.     

Genetics of Male and Female Sterility in Hybrids of Drosophila pseudoobscura and D. persimilis

The genetic basis of male and female sterility in hybrids of Drosophila pseudoobscura-Drosophila persimilis was studied using backcross analysis. Previous studies indirectly assessed male fertility by measuring testis size; these studies concluded that male sterility results from an X chromosome-autosome imbalance. By directly scoring for the production of motile sperm, male sterility is shown to be largely due to an incompatibility between genes on the X and Y chromosomes of these two species. These species have diverged at a minimum of nine loci affecting hybrid male fertility. Semisterility of hybrid females appears to result from an X chromosome-cytoplasm interaction; the X chromosome thus has the largest effect on sterility in both male and female hybrids. This is apparently the first analysis of the genetic basis of female sterility, or of sterility/inviability affecting both sexes, in an animal hybridization.     

Biosynthesis of dehydrodiconiferyl alcohol glucosides: implications for the control of tobacco cell growth

The dehydrodiconiferyl alcohol glucosides A and B are factors isolated from transformed Vinca rosea tumor cells that can replace the cytokinin requirement for growth of tobacco (Nicotiana tabacum) pith and callus cells in culture. These factors, present in tobacco pith cells, have their concentrations elevated approximately 2 orders of magnitude after cytokinin exposure. Biosynthesis experiments showed that these compounds are not cell wall fragments, as previously suggested, but are produced directly from coniferyl alcohol. Their synthesis is probably associated with the existing pathway for cell wall biosynthesis in both Vinca tumors and tobacco pith explants. The pathway requires only two steps, the dimerization of coniferyl alcohol by a soluble intracellular peroxidase and subsequent glycosylation. Biosynthetic experiments suggested that dehydrodiconiferyl alcohol glucoside breakdown was very slow and control of its concentration was exerted through restricted availability of coniferyl alcohol.