Simon G. Welch

Thermus oshimai sp. nov., isolated from hot springs in Portugal, Iceland, and the Azores, and comment on the concept of a limited geographical distribution of Thermus species

We examined aerobic, thermophilic, gram-negative bacteria that were isolated from hot springs in Portugal and were identified as Thermus strains and placed in phenetic groups on the basis of their phenotypic characteristics. We determined the composition of the peptidoglycan, identified the respiratory quinones, and determined the mean base composition of the DNA, and the levels of DNA-DNA homology were determined by both the filter hybridization and reassociation rate methods. Thermus aquaticus, Thermus brockianus, and Thermus filiformis were not detected in this collection of organisms, although three Thermus thermophilus strains were identified. We propose that the isolates that belonged to phenetic clusters E and F are members of a new species, Thermus oshimai; the type strain of T. oshimai is strain SPS17.

Progesterone 6-hydroxylation is catalysed by cytochrome P-450 in the moderate thermophile Bacillus thermoglucosidasius strain 12060

The moderate thermophile, Bacillus thermoglucosidasius, transforms progesterone into four metabolites. These are 6alpha- and 6beta-hydroxyprogesterone, androstenedione and testosterone. This is the first report of bacterial 6alpha-hydroxylation of steroids. The identity of the progesterone metabolites shows that there are three major types of transforming activity in this organism; C-17-C-20 lyase that cleaves the pregnane side chain of the substrate, C-17 oxidoreductase that interconverts the metabolites androstenedione and testosterone, and 6-hydroxylation. 6-hydroxylation activity was purified virtually to homogeneity and was shown to be catalysed by a cytochrome P-450 monooxygenase enzyme. This is the first report of a thermostable cytochrome P-450.

A comparison of the structure and properties of serum transferrin from 17 animal species

1. A comparison of the chemical and physical properties of the iron transport protein transferrin, purified from the following seventeen animal sera, is reported; human, rhesus monkey, dog, cat, rabbit, guinea pig, mouse, rat, cow, sheep, goat, horse, pig, turkey, duck, turtle and rattlesnake. 2. Similarities and differences in molecular weight, isoelectric point, antibody specificity, effect of pH on iron release, number of sialic acid residues, amino acid composition and the N-terminal amino acid residue, are discussed. 3. The results are compared with the commonly accepted evolutionary origins of the 17 species.

A comparison of the structure and properties of human, rat and rabbit serum transferrin.

1. The chemical and physical properties of human, rat and rabbit serum transferrins were compared. 2. The proteins were found to differ in heat stability, iron release, their behaviour during electrophoresis in SDS polyacrylamide gels, and their sulphur amino acid content. 3. The results are discussed in relation to the possible role of disulphide bridges in maintaining the shape and flexibility of the three transferrins, and in their appearance during the evolution of the transferrin family.

Distribution of human kappa locus IGKV2-29 and IGKV2D-29 alleles in Swedish Caucasians and Hong Kong Chinese

Abstract. Polymorphism in the IGKV2-29 gene was shown to decrease the recombination frequency in B cells and to be important for immune responses to Haemophilus influenzae type b polysaccharide. By using the combination of PCR and restriction enzyme mapping, the distribution of IGKV2D-29 and IGKV2-29 gene alleles was estimated in two geographically and ethnically different groups. We found that V2D-29*01 homozygous individuals were most common in Swedish Caucasians (82%), but less common in the Chinese population of Hong Kong (28%). The homozygous V2D-29*02 genotype was found in 19% Chinese, but only in one Caucasian (1%). The frequency of the heterozygous V2D-29*01/V2D-29*02 genotype was also higher in the Chinese population (46%) compared with the Caucasians (7%). V2-29*01 homozygosity was more frequent among Caucasians (85%) than among Chinese (19%). In contrast, homozygous V2-29*02 individuals were over-represented in the Chinese population (18%), whereas only one was found among Caucasians (1%). Heterozygous V2-29*01/V2-29*02 individuals were also more common in the Chinese (63%) than the Caucasian (15%) population. Most Caucasians had the combination of V2D-29*01/V2D-29*01+V2-29*01/V2-29*01 (74%), while the most common genotype for Chinese was V2D-29*01/V2D-29*02+V2-29*01/V2-29*02 (41%). Analysis of the association of V2D-29*02 and V2-29*02 alleles demonstrated a high degree of linkage, as for V2D-29*01 with V2-29*01. These data show a significant difference in the distribution of IGKV2D-29 and IGKV2-29 alleles among Swedish Caucasians and Hong Kong Chinese. This may help to explain differences in the occurrence of H. influenzae type b infection in the two populations. Evaluated methods for IGKV2D-29 and IGKV2-29 allele detection can be used for the screening allele polymorphisms in other particular patient groups.

Isoschizomers of the restriction endonuclease Taql (T/CGA) requiring different metal ion concentrations and having a range of thermal stabilities from Thermus species from different continents

One-hundred-and-fifty-two isolates of the genus Thermus, collected from hot springs on four continents, were screened for evidence of the presence of the thermophilic Type II restriction endonuclease TaqI (T/CGA). The presence of isoschizomers of TaqI in 27 of the isolates, originating from hot springs in New Zealand, Iceland, USA, Japan, mainland Portugal and the island of São Miguel in the Azores, is reported. Six of the TaqI-containing isolates from diverse geographical locations, identified by means of DNA/DNA homology and 16S rRNA sequence alignment as belonging to the Thermus species T. aquaticus, T. filiformis, T. thermophilus, T. scotoductus and T. brockianus, were selected for comparative studies. The TaqI isoschizomers from each of the six isolates were partially purified. They differed in their magnesium ion requirements, isoelectric points, subunit molecular masses and thermal stability.