Linkage relationship between the genes for adenosine deaminase and S-adenosyl-homocysteine hydrolase on human chromosome 20

Summary The genes for adenosine deaminase (ADA) and Sadenosyl homocysteine hydrolase (AHCY or SAHH) are known to be syntenic and within measurable distance from each other, on chromosome 20 in man. In the present study an informative family is described in which the recombination fraction (θ) between the respective genes is estimated to be about 0.18. Together with the published finding of θ=0.15 (Eiberg and Mohr 1985) in informative Danish families, the recombination fraction for the pooled data is calculated to be θ=0.14 (in men), (in women) and (both sexes taken together).     

On the stabilization of animal numbers. Problems of testing

Summary When testing for regulation of population numbers, rather than using Bulmer's second test in cases where population numbers are estimated instead of measured, we prefer to correct Bulmer's first test for estimation error. A correction method is expounded, discussed, and applied to two series of census data: the pine looper of Klomp and the garden chafer of Milne. In neither case the tentative conclusion from using the uncorrected test was changed after correction. Therefore, in practice Bulmer's first test without correction can be used well as a first orientation. Twelve long series (more than 10 years) of census data of both univoltine and semelparous (a necessary condition) insects were tested for significant density dependence in the fluctuations of numbers with the randomization test of Pollard et al. None of the series, all we could find to meet the necessary condition as well as being longer than 10 years, showed significant density dependence at the 0.05 level, though the pine looper of Klomp did so at the 0.1 level. Next, the same series were tested for regulation in the sense of keeping density within limits with both the first test of Bulmer and the permutation test of Reddingius and Den Boer. Onky Klomp's pine looper population at Hoge Veluwe scored significantly. In a following paper this population will be considered more closely, in order to enable understanding of this test result.Communication No. 362 of the Biological Station, Wijster     

Survival of Vibrio anguillarum and Vibrio salmonicida at different salinities

The fish pathogenic bacteria Vibrio anguillarum and V. salmonicida showed the capacity to survive for more than 50 and 14 months, respectively, in seawater microcosms. A salinity of 5% proved lethal to V. anguillarum harvested in the late-exponential growth phase, whereas a salinity of 9% was lethal to the bacterium after it had been starved at a salinity of 30% for 67 days. The lethal salinity for V. salmonicida harvested in the late-exponential growth phase was probably in the vicinity of 10%. V. anguillarum and V. salmonicida were very sensitive to nalidixic acid. Direct determination of viable cells after incubation with nalidixic acid was not possible, since the cells did not elongate. Samples of V. salmonicida were double stained with fluorescein isothiocyanate-labeled antibodies and 4',6-diamidino-2-phenylindole. After 3 or 4 days of starvation, there was a discrepancy between the total numbers of cells as determined by immunofluorescence versus by staining with 4',6-diamidino-2-phenylindole. The immunofluorescence counts remained high, which indicated the presence of intact cell envelopes but leakage of DNA and other cytoplasm components. After 2 weeks of starvation, for some of the cells, the region stained with 4',6-diamidino-2-phenylindole (i.e., DNA) was markedly smaller than the cell envelope. I attributed this to a shrinkage of the cytoplasm or a confined nucleoid or both. V. anguillarum lost its exoproteolytic activity before 11 days of starvation.     

Virulence studies based on plasmid profiles of the fish pathogen Vibrio salmonicida

Strains of Vibrio salmonicida isolated from Atlantic salmon (Salmo salar) and rainbow trout (Salmo gairdneri) suffering from cold-water vibriosis could be divided on the basis of plasmid profiles into four different categories. Of 32 strains, 19% harbored three plasmids of 24, 3.4, and 26 megadaltons (MDa), 69% harbored the 24- and 3.4-MDa plasmids but not the 2.6-MDA plasmid, and 9% harbored only the 24-MDA plasmid. The fourth category, which consisted of only one strain, harbored a plasmid of 10 MDa. In spite of different plasmid patterns, the strains of V. salmonicida were very similar with respect to biochemical reactions. The one-third of the V. salmonicida strains which were serotyped were of the same type. The 50% lethal doses, which were determined by intraperitoneal injection, ranged from 4 x 106 to 1 x 108 CFU per fish.     

Transformation of Claviceps purpurea using a bleomycin resistance gene

Summary To develop a DNA-mediated transformation system for Claviceps purpurea a vector was constructed using a bleomycin-resistance gene (bleo ^R) fused in frame to the Aspergillus nidulans trp C promoter as a dominant selection marker. The construct was shown to be functional in Aspergillus nidulans and Aspergillus niger and used to transform a wild strain of Claviceps purpurea. Transformats were obtained at low frequencies; they were shown to contain transforming DNA integrated into the chromosomal DNA, probably in multimeric copies and at multiple sites. Combined Southern, Northern and resistance level analysis indicate that the A. nidulans promoter is functional in C. purpurea.Dedicated to Professor Dr. Dr. h. c. K. Esser on the occasion of his 65^th birthday     

Isolation and partial characterization of heparan sulphate proteoglycan from the human glomerular basement membrane.

Heparan sulphate proteoglycan was solubilized from human glomerular basement membranes by guanidine extraction and purified by ion-exchange chromatography and gel filtration. The yield of proteoglycan was approx. 2 mg/g of basement membrane. The glycoconjugate had an apparent molecular mass of 200-400 kDa and consisted of about 75% protein and 25% heparan sulphate. The amino acid composition was characterized by a high content of glycine, proline, alanine and glutamic acid. Hydrolysis with trifluoromethanesulphonic acid yielded core proteins of 160 and 110 kDa (and minor bands of 90 and 60 kDa). Alkaline NaBH4 treatment of the proteoglycan released heparan sulphate chains with an average molecular mass of 18 kDa. HNO2 oxidation of these chains yielded oligosaccharides of about 5 kDa, whereas heparitinase digestion resulted in a more complete degradation. The data suggest a clustering of N-sulphate groups in the peripheral regions of the glycosaminoglycan chains. A polyclonal antiserum raised against the intact proteoglycan showed reactivity against the core protein. It stained all basement membranes in an intense linear fashion in immunohistochemical studies on frozen kidney sections from man and various mammalian species.