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The aim of this study was to clarify the pathway of electron transfer between the inner membrane components and the periplasmic chlorate reductase. Several soluble c-type cytochromes were found in the periplasm. The optical difference spectrum of dithionite-reduced periplasmic extract shows that at least one of these components is capable of acting as an electron donor to the enzyme chlorate reductase. The cytochromes were partially separated, and the fractions were analyzed by UV/visible spectroscopy to determine the ability of donating electrons to chlorate reductase. Our results show that one of the c cytochromes (6 kDa) is able to donate electrons, both to chlorate reductase and to the membrane-bound cytochrome c oxidase, whereas the roles of the remaining c cytochromes still remain to be elucidated. Peptide extracts of the c cytochromes were obtained by tryptic in-gel digestion for matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis. Peptide sequences obtained indicate that the 6-kDa cytochrome c protein is similar to c cytochromes from the chlorate-reducing bacterium Dechloromonas aromatica.

Oligonucleotide usage in archaeal and bacterial genomes can be linked to a number of properties, including codon usage (trinucleotides), DNA base-stacking energy (dinucleotides), and DNA structural conformation (di- to tetranucleotides). We wanted to assess the statistical information potential of different DNA 'word-sizes' and explore how oligonucleotide frequencies differ in coding and non-coding regions. In addition, we used oligonucleotide frequencies to investigate DNA composition and how DNA sequence patterns change within and between prokaryotic organisms. Among the results found was that prokaryotic chromosomes can be described by hexanucleotide frequencies, suggesting that prokaryotic DNA is predominantly short range correlated, i.e., information in prokaryotic genomes is encoded in short oligonucleotides. Oligonucleotide usage varied more within AT-rich and host-associated genomes than in GC-rich and free-living genomes, and this variation was mainly located in non-coding regions. Bias (selectional pressure) in tetranucleotide usage correlated with GC content, and coding regions were more biased than non-coding regions. Non-coding regions were also found to be approximately 5.5% more AT-rich than coding regions, on average, in the 402 chromosomes examined. Pronounced DNA compositional differences were found both within and between AT-rich and GC-rich genomes. GC-rich genomes were more similar and biased in terms of tetranucleotide usage in non-coding regions than AT-rich genomes. The differences found between AT-rich and GC-rich genomes may possibly be attributed to lifestyle, since tetranucleotide usage within host-associated bacteria was, on average, more dissimilar and less biased than free-living archaea and bacteria.

Background: The increasing number of sequenced prokaryotic genomes contains a wealth of genomic data that needs to be effectively analysed. A set of statistical tools exists for such analysis, but their strengths and weaknesses have not been fully explored. The statistical methods we are concerned with here are mainly used to examine similarities between archaeal and bacterial DNA from different genomes. These methods compare observed genomic frequencies of fixed-sized oligonucleotides with expected values, which can be determined by genomic nucleotide content, smaller oligonucleotide frequencies, or be based on specific statistical distributions. Advantages with these statistical methods include measurements of phylogenetic relationship with relatively small pieces of DNA sampled from almost anywhere within genomes, detection of foreign/conserved DNA, and homology searches. Our aim was to explore the reliability and best suited applications for some popular methods, which include relative oligonucleotide frequencies (ROF), di- to hexanucleotide zero'th order Markov methods (ZOM) and 2.order Markov chain Method (MCM). Tests were performed on distant homology searches with large DNA sequences, detection of foreign/conserved DNA, and plasmid-host similarity comparisons. Additionally, the reliability of the methods was tested by comparing both real and random genomic DNA., Results: Our findings show that the optimal method is context dependent. ROFs were best suited for distant homology searches, whilst the hexanucleotide ZOM and MCM measures were more reliable measures in terms of phylogeny. The dinucleotide ZOM method produced high correlation values when used to compare real genomes to an artificially constructed random genome with similar %GC, and should therefore be used with care. The tetranucleotide ZOM measure was a good measure to detect horizontally transferred regions, and when used to compare the phylogenetic relationships between plasmids and hosts, significant correlation (R2 = 0.4) was found with genomic GC content and intra-chromosomal homogeneity., Conclusion: The statistical methods examined are fast, easy to implement, and powerful for a number of different applications involving genomic sequence comparisons. However, none of the measures examined were superior in all tests, and therefore the choice of the statistical method should depend on the task at hand.

Background: Treating hypertension with drugs is so far the most cost-effective way to reduce this important risk factor for cardiovascular disease (CVD). It is, however, important to determine absolute risk, and thereby estimate indication for drug treatment, in order to maintain a cost-effective drug treatment. WHO/ISH Hypertension Guidelines from 1999 propose a risk stratification for estimating absolute risk for CVD based on blood pressure and additional risk factors, target organ damage (TOD) and CVD., Objectives: We studied the consequences of applying the recent WHO/ISH risk stratification scheme to a MONICA sample of 6000 subjects from a geographically defined population in northern Sweden, regarding indications for treatment, target blood pressure and risk distribution., Methods: We have risk-classified each of these patients using a computer program, according to the WHO/ISH scheme. Data on TOD were not available., Results: In all, 917 (15%) had drug-treated hypertension. Three-quarters (n = 737) were inadequately treated, with blood pressure levels at or above 140 or 90 mmHg. 1773 (30% of 5997) untreated subjects had a blood pressure of 140/90 or above; 16% in the low-, 62% in the medium-, 8% in the high-, and 14% in the very-high-risk group. The corresponding risk-group pattern for the inadequately treated hypertensives (n = 737) was 5.5, 48.3, 11.1 and 35.2%, respectively. If we shifted the target blood pressure from below 140/90 to below 130/85 for drug-treated subjects under 60 (n = 278) the number of inadequately treated subjects increased by 34 (12.2% of 278); 14 in the low-risk group, 15 in the medium-risk group, and only five in the high- or very-high-risk groups., Conclusions: Only one-fifth of the drug-treated hypertensives were well controlled. Moreover, the incidence of newly detected blood pressure elevation was high. The majority of younger subjects with high blood pressure had low risk, but in those aged 45-54 this had already risen to a medium risk. Changing the target blood pressure to below 130/85, for subjects aged below 60, as recommended by WHO/ISH, affects predominantly low- and medium-risk groups.