Localization of the human myelin basic protein gene (MBP) to region 18q22----qter by in situ hybridization

A restriction endonuclease fragment derived from a cloned portion of human genomic DNA corresponding to the myelin basic protein gene has been used to map the position of this gene by in situ hybridization to human metaphase chromosomes. Ten percent of the radioactively labeled sites observed were on chromosome 18. Eighty-four percent of the grains on chromosome 18 were located within the region corresponding to 18q22----qter. This represents a greater than 10-fold increase in labeling at this position over the background grain distribution found along all of the other chromosomes.     

Tetrameric repeat units associated with virulence factor phase variation in Haemophilus also occur in Netsseria spp. and Moraxella catarrhalis

Abstract The tetrameric repeat units 5'-CAAT-3' and 5'-GCAA-3' are associated with phase variable expression of lipopolysaccharide biosynthetic genes in Haemophilus influenzae . Four other tetrameric repeat units have also been reported from H. influenzae strain Rd, 5'-CAAC-3', 5'-GACA-3', 5'-AGCT-3', and 5'-TTTA-3', which are also associated with putative virulence factors. Using oligonucleotide probes corresponding to five tandem copies of each of these tetramers, we have screened three strains of Neisseria meningitidis and one each of Neisseria gonorrhoeae, Neisseria lactamica, Haemophilus parainfluenzae, Bordetella pertussis, Bordetella parapertussis, Bordetella bronchiceptica and Moraxella catarrhalis for the presence of these motifs. We have demonstrated the presence of multiple copies of the 5'-GCAA-3' motif in all the Neisseria strains tested, and also the repeated motif 5'-CAAC-3' in M. catarrhalis . We have further demonstrated by Southern blot analysis that the 5'-CAAC-3' repeats detected in M. catarrhalis are probably associated with the same genes as in H. influenzae , but that the 5'-GCAA-3' motifs in N. meningitidis are not. The use of characterised tetrameric DNA sequences as hybridisation probes may prove useful in the identification of novel phase variable virulence determinants in organisms other than H. influenzae .     

Effect of nutrient deprivation on lipid, carbohydrate, DNA, RNA, and protein levels in Vibrio cholerae

The response of Vibrio cholerae to low nutrient levels was determined by measuring the concentrations of lipids, carbohydrates, DNA, RNA, and proteins over a 30-day starvation period. Ultrastructural integrity was observed by transmission electron microscopy. Total lipids and carbohydrates declined rapidly within the first 7 days, while DNA and protein exhibited a more constant decline over the 30 days of starvation. In contrast, RNA showed little decrease upon starvation. Although neutral lipids were lost, the percentage of neutral lipids did not decline as rapidly as the phospholipids. Detectable levels of poly-beta-hydroxybutyrate disappeared completely by 7 days. Carbohydrate profiles revealed the relative loss of the five-carbon sugar ribose and N-acetylglucosamine and a relative increase in the total six-carbon sugars, especially glucose. Morphologically, ribosomes appeared to exhibit no structural change, while inclusion bodies and mesosomelike structures disappeared completely, and cell wall and membrane integrity was lost. The data suggest that V. cholerae differs somewhat from other marine vibrios in its response to low nutrients but shares some characteristics in common with them. The data also suggest that certain lipids and carbohydrates may provide the endogenous energy sources needed for dormancy preparation and cell maintenance under nutrient starvation.     

Model genomes: the benefits of analysing homologous human and mouse sequences.

The human genome initiative has provided the motivating force for launching sequencing projects suitable for testing various DNA-sequencing strategies, as well as motivating the development of mapping and sequencing technologies. In addition to projects targeting selected regions of the human genome, other projects are based on model organisms such as yeast, nematode and mouse. The sequencing of homologous regions of human and mouse genomes is a new approach to genome analysis, and is providing insights into gene evolution, function and regulation which could not be determined so easily from the analysis of just one species.     

Urinary excretion of prostaglandin E2 and prostaglandin F2α in potassium-deficient rats

Potassium-deficiency was induced in rats by dietary deprivation of potassium. The animals became polyuric and urine osmolality decreased more then three-fold compared to controls. Urinary excretion of prostaglandin E₂ (PGE₂) and prostaglandin F_2α (PGF_2α) did not increase during 2 weeks of potassium depletion. Partial inhibition of renal prostaglandin synthesis by meclofenamate did not increase the urine osmolality after water deprivation. These results make unlikely the hypothesis that the polyuria of potassium-deficiency, is the result of enhanced renal synthesis of prostaglandins with subsequent antagonism of the hydro-osmotic effect of vasopressin. Male animals consistently excreted less PGE₂ than female animals.     

Optimization of asymmetric polymerase chain reaction for rapid fluorescent DNA sequencing

A high-throughput method for the preparation of single-stranded template DNA, which is suitable for sequence analysis using fluorescent labeling chemistry, is described here. In this procedure, the asymmetric polymerase chain reaction is employed to amplify recombinant plasmid or bacteriophage DNA directly from colonies or plaques. The use of amplification primers located at least 200 base pairs 5' to the site of sequencing primer annealing removes the need for extensive purification of the asymmetric polymerase chain reaction product. Instead, the single-stranded product DNA is purified by a simple isopropanol precipitation step and then directly sequenced using fluorescent dye-labeled oligonucleotides. This method significantly reduces the time and labor required for template preparation and improves fluorescent DNA sequencing strategies by providing a much more uniform yield of single-stranded DNA.     

The Molecular Evolution of the Vertebrate Trypsinogens

We expand the already large number of known trypsinogen nucleotide and amino acid sequences by presenting additional trypsinogen sequences from the tunicate (Boltenia villosa), the lamprey (Petromyzon marinus), the pufferfish (Fugu rubripes), and the frog (Xenopus laevis). The current array of known trypsinogen sequences now spans the entire vertebrate phylogeny. Phylogenetic analysis is made difficult by the presence of multiple isozymes within species and rates of evolution that vary highly between both species and isozymes. We nevertheless present a Fitch-Margoliash phylogeny constructed from pairwise distances. We employ this phylogeny as a vehicle for speculation on the evolution of the trypsinogen gene family as well as the general modes of evolution of multigene families. Unique attributes of the lamprey and tunicate trypsinogens are noted. Received: 12 July 1997