Nmel, a restriction endonuclease from Neisseria meningitidis

A restriction endonuclease, Nmel, present in Neisseria meningitidis was partially purified by passing through a blue 2-cross linked agarose column; no contaminating nucleases remained detectable. This enzyme cleaved phage lambda, adenovirus type 2 and phi x 174 DNA but did not cleave SV40 DNA. It had an absolute requirement for Mg2+ for its activity and was inhibited by high concentrations of NaCl or MgCl2. Nmel activity was completely abolished after 1 h of incubation at 65 degrees C. S-adenosyl-L-methionine and ATP had no effect on its activity suggesting that Nmel is a type II restriction endonuclease enzyme. It is the first report of a restriction enzyme present in N. meningitidis.     

Species-specific uptake of DNA by gonococci is mediated by a 10-base-pair sequence.

Piliated Neisseria gonorrhoeae are known to be transformed less readily if transforming DNA competes with DNA containing the 10-bp sequence GCCGTCTGAA. It has been postulated that the 10-bp sequence is a recognition sequence which is required for efficient DNA uptake. We show that the presence of various forms of this 10-bp sequence results in increased uptake of double-stranded DNA into a DNase-resistant state and allows genetic transformation by an otherwise nontransformable plasmid.     

Ectopic Pregnancy: A Statistical Review of 360 Cases

In a statistical analysis of 360 cases of ectopic pregnancy admitted to the Montreal General Hospital over a 20-year period ending December 1964, ectopic gestation occurred once in every 83 admissions to the gynecological service. This incidence has remained constant over the years. Only one out of four patients had had more than one child and 30% of the patients had absolute or relative infertility. Diagnosis was delayed or not made in 58 patients. There was evidence that neurogenic factors play a role in the etiology of ectopic gestation. Ten per cent of the patients had had a previous operation for the same condition. Symptomatology is variable and the possibility of ectopic pregnancy must never be overlooked in a woman of child-bearing age. Once the diagnosis is made the treatment is early operation. The morbidity rate in this series was 28% and there was one death.     

The production of hydrogen sulphide in peats

The levels of sulphide ions in several peatlands have been shown to vary from low on the surface to values deeper in the peat in excess of 7.0 mg S/100 g fresh weight of peat. Highest levels of sulphide were recorded in early summer falling to close to zero in August and November. Rates of hydrogen sulphide production in peats are greatest between 10 and 15 cm from the surface and are associated with water table position. Reduced rates towards the surface are related to aeration and those below 15 cm attributed to higher sulphide levels causing autoinhibition or to the absence of suitable carbon sources.     

Analysis of mixed lipid extracts using 1H NMR spectra

A method has been developed for rapid analysis of lipid protonNMR spectra. Identification of lipid content is possible becauseof the presence of unique peaks or ratios of peaks for individuallipids. Spectra can be subdivided into regions where peaks representcertain chemical groups held in common, or uniquely by the variouslipids. Vectors (B) are made up of the areas of these subdivisionsof peaks from spectra of unknown components. A new FORTRAN algorithm,LIPICK, tests for the presence of unique peaks or combinationsof peaks to determine which lipids may be present. The spectravectors of known identified lipids are then placed in the (A)matrix of possible solution candidates. Quantitation of lipidsin an H NMR spectrum (B) of an unknown mixture then proceedsby solving the equation AX = B for X (the concentrations ofthe individual lipids present) by singular value analysis. Atthis time, it is possible to test 1 mg of total lipid for thepresence and relative concentration of 15 common lipids: cholesteroland its esters; phosphatidyl-ethanolamine, -choline, -serine,-inositol, -glycerol; tri- or di-glycerides; fatty acid; lysophosphatidylcholine; sphingomyelin; cerebrosides and sulfatides; dolicholand dolichol P; and phosphatidic acid. This procedure is suitablefor membrane lipid analysis and has been evaluated using knownmixtures of purified standard lipids. Received on July 24, 1989; accepted on August 1, 1989