Virulence ofEscherichia coli strains isolated from urine of patients with acute cystitis and from faeces of healthy women

E. coli strains were isolated from the urine of patients with acute cystitis in general practice and from the faeces of a comparable reference group of healthy individuals. These strains were serotyped and tested for virulence in an experimental mouse model. Of 30 cystitis-strains 18 were virulent, and of 30 faeces-strains 15 were virulent. It is concluded that the cystitis-strains were not more often virulent than the faeces-strains. O antigens commonly found among urinaryE. coli isolates were present in 60% of the cystitis-strains and in 37% of the faeces-strains. K antigens commonly found in urinaryE. coli strains were present in 33% of the cystitis-strains and in 12% of the faeces-strains. Neither the presence of common urinary O-antigens, nor the presence of common urinary K antigens could be associated with virulence of the isolated strains. However, it is suggested that certain O and K antigens (O2, O6, K23) may be associated with virulence for the urinary tract.     

Fermentative Conversion of Cellulose to Acetic Acid and Cellulolytic Enzyme Production by a Bacterial Mixed Culture Obtained from Sewage Sludge

A simple procedure that uses a cellulose-enriched culture started from sewage sludge was developed for producing cellulolytic enzymes and converting cellulose to acetic acid rather than CH₄ and CO₂. In this procedure, the culture which converts cellulose to CH₄ and CO₂ was mixed with a synthetic medium and cellulose and heated to 80°C for 15 min before incubation. The end products formed were acetic acid, propionic acid, CO₂, and traces of ethanol and H₂. Supernatants from 6- to 10-day-old cultures contained 16 to 36 mM acetic acid. Cellulolytic enzymes in the supernatant were stable at 2°C under aerobic conditions for up to 4 weeks and had the ability to hydrolyze carboxymethyl cellulose, a microcystalline cellulose, cellobiose, xylan, and filter paper to reducing sugars.     

Phenotypic expression of mutations in a wide-host-range R plasmid in Escherichia coli and Rhizobium meliloti.

Eight different derivatives of R plasmid RP1 with thermosensitive mutations affecting maintenance in Escherichia coli and Pseudomonas aeruginosa were introduce into Rhizobium meliloti. None of the plasmids showed a thermosensitive character in R. meliloti. On the other hand, a certain deletion mutation in RP1 was found to cause plasmid instability in rhizobia and agrobacteria, but not in E. coli.     

Genetics of the peroxidase isoenzymes in Petunia

Summary Three electrophoretic variants of the peroxidase b isoenzymes in Petunia have been found. The encoding gene prxB is shown to be located on chromosome I by its linkage with the gene Hfl. Analysis of prxB heterozygotes showed a gradual increase of the electrophoretic mobility of all three PRXb allozymes during development and differential expression in enzyme activity of three prxB alleles. The location of prxB on chromosome I was confirmed by an allelic dosage effect in trisomies I, trisomie segregation and the construction of trisomies I with triple-banded PRXb phenotype. From telotrisomic analysis it was concluded that prxB and Hfl are located on the same arm of chromosome I. The unexpected linkage of prxB and Hfl with the gene Fl in one of the crosses was suggested to be caused by a translocation in line SI, involving the gene Fl.     

On the survival of populations in a heterogeneous and variable environment

Summary The survival time of small and isolated populations will often be relatively low, by which the survival of species living in such a way will depend on powers of dispersal sufficiently high to result in a rate of population foundings that about compensates the rate of population extinctions. The survival time of composite populations uninterruptedly inhabiting large and heterogeneous areas, highly depends on the extent to which the numbers fluctuate unequally in the different subpopulations. The importance of this spreading of the risk of extinction over differently fluctuating subpopulations is demonstrated by comparing over 19 years the fluctuation patterns of the composite populations of two carabid species, Pterostichus versicolor with unequally fluctuating subpopulations, and Calathus melanocephalus with subpopulations fluctuating in parallel, both uninterruptedly occupying the same large heath area. The conclusions from the field data are checked by simulating the fluctuation patterns of these populations, and thus directly estimating survival times. It thus appeared that the former species can be expected to survive more than ten times better than the latter (other things staying the same). These simulations could also be used to study the possible influence of various density restricting processes in populations already fluctuating according to some pattern. As could be expected, the survival time of a population, which shows a tendency towards an upward trend in numbers, will be favoured by some kind of density restriction, but the degree to which these restrictions are density-dependent appeared to be immaterial. Density reductions that are about adequate on the average need even not occur at high densities only, if only the chance of occurrence at very low densities is low. The density-level at which a population is generally fluctuating appeared to be less important for survival than the fluctuation pattern itself, except for very low density levels, of course. The different ways in which deterministic and stochastic processes may interact and thus determine the fluctuations of population numbers are discussed. It is concluded that some stochastic processes will operate everywhere and will thus necessarily result in density fluctuations; such an omnipresence is much less imperative, however, for density-dependent processes, by which population models should primarily be stochastic models. However, if density-dependent processes are added to model populations, that are already fluctuating stochastically the effects are taken up into the general, stochastic fluctuation pattern, without altering it fundamentally.Communication No. 228 of the Biological Station WijsterDedicated to Professor Michael Evenari     

The enzymes of the ammonia assimilation in Pseudomonas aeruginosa

Glutamine synthetase from Pseudomonas aeruginosa is regulated by repression/derepression of enzyme synthesis and by adenylylation/deadenylylation control. High levels of deadenylylated biosynthetically active glutamine synthetase were observed in cultures growing with limiting amounts of nitrogen while synthesis of the enzyme was repressed and that present was adenylylated in cultures with excess nitrogen.NADP-and NAD-dependent glutamate dehydrogenase could be separated by column chromatography and showed molecular weights of 110,000 and 220,000, respectively. Synthesis of the NADP-dependent glutamate dehydrogenase is repressed under nitrogen limitation and by growth on glutamate. In contrast, NAD-dependent glutamate dehydrogenase is derepressed by glutamate. Glutamate synthase is repressed by glutamate but not by excess nitrogen.     

Perinatal mortality and XY/XX mosaicism

Summary An XX/XY mosaicism was detected in two phenotypically male newborns with perinatal death. The importance of chromosome studies at the paediatric necropsy and the significance of the present findings are discussed.     

Molecular structure of the immunity gene and immunity protein of the bacteriocinogenic plasmid Clo DF13.

The nucleotide sequence of the Clo DF13 DNA region comprising the immunity gene has been determined. We also elucidated the aminoacid sequence of the 40 N-terminal and 7 C-terminal aminoacids of the purified immunity protein. From analysis of the data obtained we were able to locate the immunity gene between 11.7 and 14.5% on the Clo DF13 map, and to determine the complete aminoacid sequence of the immunity protein. It was observed that the Clo DF13 immunity gene encodes an 85 aminoacid protein and is transcribed in the same direction as the cloacin gene. These experimental data support our model, presented elsewhere, which implicates that the cloacin and immunity genes of Clo DF13 are coordinately transcribed from the cloacin promoter. We also present DNA sequence data indicating that an extra ribosome binding site precedes the immunity gene on the polycistronic mRNA. This ribosome binding site might explain the fact that in cloacinogenic cells more immunity protein than cloacin is synthesized. The comparison of the complete aminoacid sequence of the Clo DF13 immunity protein, with the aminoacid sequence data of the purified, comparable Col E3 immunity protein revealed that both proteins have extensive homologies in primary and secondary structure, although they are exchangeable only to a low extent in vivo and in vitro. It was also observed that a lysine residue was modified in immunity protein isolated from excreted bacteriocin complexes.