bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth‐rate variation in brown trout in small neighbouring streams: evidence for density‐dependence?
Authors: Vøllestad L. A. , Olsen E. M. , Forseth T.
Published: April 2005

The within‐ and among‐population variation in individual growth rate of brown trout Salmo trutta L. was studied in five small neighbouring streams (seven isolated populations) within a distance of 70 km in east Norway. Observed growth rate was only weakly correlated with predicted maximum growth rate based on laboratory models, and there was a significant interaction with site. A generalized linear model showed that growth rate was positively correlated with temperature, but also that growth rate decreased as the summer season progressed. This might indicate either a seasonal decline in food availability or appetite, or a change in energy allocation strategy. Growth rate decreased with increasing fish age, probably as an effect of sexual maturation of older fish, and differential allocation of protein and lipid among different size‐groups of brown trout. After adjusting for variation in temperature, season, and fish mass, there was still significant among‐site variation in growth rate. A significant part of this variation was due to variation in brown trout density and the presence or absence of Alpine bullhead Cottus poecilopus. Growth rate decreased with increasing brown trout density, and was lower in the presence than in the absence of Alpine bullhead after correcting for variation in brown trout density. This last result may indicate the presence of interspecific competition.
Interaction between the introduced eastern mosquitofish and two autochthonous Spanish toothcarps
Authors: Rincón P. A. , Correas A. M. , Morcillo F. , Risueño P. , Lobón‐Cerviá J.
Published: April 2005

In aquaria, adults and young‐of‐the‐year (YOY) of both Spanish toothcarp Aphanius iberus and Valencia toothcarp Valencia hispanica received more aggression in the presence of eastern mosquitofish Gambusia holbrooki. YOY of both species also showed decreased feeding rates, as did V. hispanica adults. Adult V. hispanica also were more aggressive themselves and had their reproductive behaviour disrupted. Cases of eastern mosquitofish predation on small A. iberus were also observed. The occurrence and intensity of these potentially harmful effects, however, seemed to be modulated by water temperature, reproductive condition, relative size of the interacting fishes and species‐specific habitat preferences. Thus, aggression almost disappeared at low water temperatures. Valencia hispanica and eastern mosquitofish used similar vertical positions in the water column and this apparently increased the frequency of their interactions. In contrast, A. iberus preferred positions closer to the bottom than the other two species and this vertical segregation appeared to lead to less direct interaction with eastern mosquitofish. In an outdoor mesocosm experiment, under semi‐natural conditions, the presence of eastern mosquitofish resulted in an almost 70% reduction in the number of offspring produced by A. iberus. The addition of extra, non‐breeding males of A. iberus had no significant effect. YOY A. iberus from cages with eastern mosquitofish or extra males were significantly smaller (c. 1 mm, or 8% shorter) than those from cages without additional fish. Results for V. hispanica were not conclusive, as very few YOY were recovered. In contrast, eastern mosquitofish did not affect the survivorship of breeding adults of both native species.
Environmentally related life history variations in Geophagus brasiliensis
Authors: Mazzoni R. , Iglesias‐Rios R.
Published: April 2005

The hypothesis of environmentally related life history variations between two Geophagus brasiliensis populations was investigated by comparing riverine and lacustrine populations. Mean standard length and length at maturity were higher in the lagoon population. Higher fecundity and gonado‐somatic indices reflected higher reproductive investment in the river population. In the river, reproduction took place throughout the year, whereas in the lagoon spawning was restricted to spring and summer. Both populations presented synchronous oocyte development, indicating total spawning. Nevertheless, the variation in traits suggests that both populations exhibit environmentally related variations in their life history patterns.
Morphological variation between lake‐ and stream‐dwelling rock bass and pumpkinseed populations
Authors: Brinsmead J. , Fox M. G.
Published: April 2005

Pumpkinseed Lepomis gibbosus and rock bass Ambloplites rupestris stream populations of both sexes were significantly different in external morphology from lake populations in a central Ontario, Canada, watershed. The predictions that stream fishes would be more slender‐bodied, and have a more anterior placement of lateral fins than lake fishes were generally supported. The prediction that stream fishes would have a more robust caudal peduncle was partially supported. The prediction that fin size would be larger in stream fishes was not supported, as lake rock bass generally had longer and wider fins than those from stream sites. The results suggest that in some species, smaller fins may be favoured in stream‐dwelling individuals because the reduction of drag during swimming more than compensates for their reduced power and propulsion efficiency in a current. Smaller fin size in stream‐dwelling centrarchids may be related to their body shape, or to their low usage of fast‐moving water within the streams they inhabit.
Unexpected large numbers of Mullus surmuletus juveniles in open waters of the Mediterranean sampled with light attraction devices
Authors: Deudero S.
Published: April 2005

Experimental night hauls with a purse‐seine were performed using two light devices in waters off Majorca in the western Mediterranean to investigate light attraction of juvenile fishes in epipelagic waters over the continental slope. Large numbers of Mullus surmuletus were caught indicating that light devices are suitable for sampling juveniles (2–6 cm) of this species. The data obtained can be used to provide valuable information on geographic distribution and spatial aggregation patterns of this mullid, altogether with the acquisition of biological samples for growth or stomach contents analyses of juveniles stages.
First records of the North American catfish Ameiurus melas in Portugal
Authors: Gante H. F. , Santos C. D.
Published: April 2005

The North American catfish Ameiurus melas is recorded for the first time in Portugal. Its presence in the Tagus River Basin is probably due to natural spread of individuals from Spanish populations, while episodic translocation could explain its occurence in the previously non‐invaded Guadiana and Sado River basins.
Newly discovered reproductive isolation reveals sympatric populations of Esox lucius in the Baltic
Authors: Westin L. , Limburg K. E.
Published: April 2005

Two populations of pike Esox lucius have been identified on the eastern coast of Sweden, in the Baltic Sea. These live together, but separate into two different populations during the spawning season. One is an obligate freshwater spawner and the other not only reproduces in ambient Baltic salinities, but appears not to enter fresh water at all.
Electrical Properties of Nonconventional Bi‐Ba‐Cu‐O Glasses
Authors: Miyaji Fumiaki , Fujimine Satoshi , Yoko Toshinobu , Sakka Sumio
Published: April 2005

Electrical properties of Bi‐Ba‐Cu‐O glasses have been systematically investigated, and possible conduction mechanisms are discussed. Conductivity behavior is described by a small‐polaron hopping mechanism. log σo, the slope of the log σ‐W straight line, and the magnitude of the polaron bandwidth reveal that adiabatic hopping is dominant in the glasses. The Seebeck coefficient, S, of the Bi16BaCu3Oy glass is positive, indicating that the glass is a p‐type hole conductor. The positive deviation of the observed S value from the theoretical S value is explained by assuming that the only oxygens bonded to both Cu2+ and Cu+ ions mediate indirect Cu+‐O‐Cu2+ hopping.
Electrochemical Corrosion and Protection of Molybdenum and Molybdenum Disilicide in a Molten Soda‐Lime Silicate Glass Environment
Authors: Sundaram S. Kamakshi , Speyer Robert F.
Published: April 2005

Electrochemical corrosion of Mo and MoSi2 in a molten soda‐lime silicate glass environment was studied using a two‐electrode cell with Pt as the counterelectrode. XRD, SEM, and EDS were used to characterize the corroded specimens. When Mo was cathodically polarized (‐1 V), no corrosion and a Mo surface were observed after 12 h of electrochemical corrosion. Under anodic polarization (+1 V), higher corrosion (0.42 mm) was observed due to formation of MoO2, which did not form a coherent passive layer. Cathodic protection occurred by electrostatic repulsion of oxygen ions, thus discouraging oxidation of Mo. Anodically polarized (+1 V) MoSi2 showed a significant decrease in recession at the glass line due to formation of SiO2 product which attenuated convective flow currents. Accelerated corrosion was observed under cathodic polarization (‐1 V), where streams of Mo particles were observed flowing downward in the melt. MoSi2 was interpreted to decompose into neutral molybdenum and silicon anions, which were rejected into the melt.
Effect of Nucleating Agents on the Crystallization of Calcium Phosphate Glasses
Authors: Reaney Ian M. , James Peter F. , Lee William E.
Published: April 2005

Phase evolution in calcium phosphate‐based glass ceramics has been examined. Pure CaO:P2O5 readily formed a glass which surface nucleated upon annealing, but volume nucleation at 680°C was observed only after the addition of the nucleating agents, TiO2 and A12O3. Phase separation of Ti and Al occurred along with the nucleation and growth of a calcium phosphate phase, similar to β‐Ca2P2O7. Heat treatments at higher temperatures and/or for longer times resulted in crystallization of A1‐ and Ti‐rich, phase‐separated regions. A glass with a higher CaO:P2O5 ratio (approximately 2:1) could be prepared only when a total of 25‐35 mol% of TiO2, A12O3, and SiO2 were present in the batch. The glass phase‐separated into respective SiO2‐ and CaO/P2O5‐rich regions on cooling. The SiO2‐rich regions did not influence crystallization and remained amorphous throughout the heat treatments. In the CaO/P2O5‐rich regions, homogeneous volume nucleation of a Ti‐rich phase readily occurred followed by the heterogeneous nucleation and growth on these nuclei of a calcium phosphate phase. Although this phase was macroscopically composed of spherulites, TEM revealed that they consisted of intertwined nanodendrites whose individual arms were approximately 20 nm wide and 50 nm long.
An investigation of the effect of privatization of retail sales of alcohol on consumption and traffic accidents in Alberta, Canada
Authors: Trolldal Björn
Published: April 2005

Aims  Privatization of the retail sale of alcohol in Alberta took place primarily between the end of the 1980s and the beginning of the 1990s. The aim of this study was to evaluate the effects of this privatization on alcohol sales and on the incidence of fatal motor vehicle traffic accidents in the province.

Data and method  Interrupted time‐series analysis (ARIMA) with a quasi‐experimental control area design was used, and all series were differenced to remove long‐term trends. Canada, with the exception of Alberta, was the control area. The effects of privatization were measured by means of created privatization variables. In the analyses of the effects of privatization on alcohol sales, the inhabitants’ disposable income and alcohol prices were used as control variables. The study period was 1950–2000. When effects on the number of fatal motor vehicle traffic accidents were analysed the number of road motor vehicle registrations was used as a control variable, and the study period was 1950–98.

Findings  Privatization had a significant permanent effect on the sale of spirits, but the effect was not large enough to affect total sales. The effect on wine and beer sales was not significant. There was no significant effect on the number of fatal motor vehicle traffic accidents.

Conclusion  The fact that sales on the wholesale level continued to be monopolized, along with the fact that alcohol sales were never allowed in ordinary grocery stores, may explain the lack of any larger effects of privatization on alcohol sales in Alberta.
Age of onset of drinking and the use of alcohol in adulthood: a follow‐up study from age 8–42 for females and males
Authors: Pitkänen Tuuli , Lyyra Anna‐Liisa , Pulkkinen Lea
Published: April 2005

Aim  To investigate longitudinally for both genders the relation between the age of onset of drinking and several indicators of alcohol use.

Design and setting  In the Finnish Jyväskylä Longitudinal Study of Personality and Social Development, data have been collected by interviews, inventories, and questionnaires. Data on alcohol consumption was gathered at ages 14, 20, 27, 36 and 42 years; behavioural data at age 8.

Participants  A total of 155 women and 176 men; 90.4% of the original sample consisting of 12 complete school classes in 1968.

Measurements  The age of onset of drinking was determined based on participants’ responses that were closest to the actual age of onset of drinking. Four indicators of the adult use of alcohol were used: frequency of drinking, binge drinking, Cut‐down, Annoyed, Guilt, Eye‐opener (CAGE) and Malmö modified Michigan Alcoholism Screening Test (Mm‐MAST). Socio‐emotional behaviour at age 8 was assessed using teacher ratings and peer nominations.

Findings  Early onset of drinking was related to the four indicators of the use of alcohol in adulthood both in men and women. The level of adult alcohol use and alcohol problems was significantly higher in men. The risk for heavy drinking was highest in men and women if drinking was started at less than age 16 years. Socio‐emotional behaviour and school success at age 8 did not predict the age of onset of drinking.

Conclusions  Delaying the initiation of drinking from early adolescence to late adolescence is an important goal for prevention efforts. No clear risk group for early initiators of drinking could be identified on the basis of preceding behaviour among 8‐year‐olds.
Iatrogenic effects of psychosocial interventions for substance use disorders: prevalence, predictors, prevention
Authors: Moos Rudolf H.
Published: April 2005

Aims  To examine the prevalence and personal and intervention‐related predictors of potential iatrogenic effects associated with psychosocial interventions for substance use disorders and provide a conceptual framework to guide further research on such effects.

Method  A review of relevant studies focuses on the prevalence and predictors of potential iatrogenic effects of psychosocial treatment and prevention programs for substance use disorders.

Results  Between 7% and 15% of patients who participate in psychosocial treatment for substance use disorders may be worse off subsequent to treatment than before. In addition, several controlled trials of substance use prevention have shown some apparent iatrogenic effects, including more positive expectations about substance use and a rise in alcohol use and alcohol‐related problems. Probable person‐related predictors of deterioration associated with treatment include younger age and unmarried status, more serious current diagnoses and substance use problems and more psychiatric and interpersonal problems. Probable intervention‐related predictors of deterioration include lack of bonding; lack of monitoring; confrontation, criticism and high emotional arousal; deviancy modeling; and stigma, low or inappropriate expectations and lack of challenge.

Conclusion  A significant minority of individuals with substance use problems appear to deteriorate during or shortly after participation in treatment or prevention programs. Safety standards and monitoring procedures are needed to routinely identify potential adverse consequences of intervention programs; research is needed to clarify whether deterioration is due to iatrogenic effects of interventions and to identify new approaches to counteract any such effects.
Randomized controlled trial of a web‐based computer‐tailored smoking cessation program as a supplement to nicotine patch therapy
Authors: Strecher Victor J. , Shiffman Saul , West Robert
Published: April 2005

Aim  To assess the efficacy of World Wide Web‐based tailored behavioral smoking cessation materials among nicotine patch users.

Design  Two‐group randomized controlled trial.

Setting  World Wide Web in England and Republic of Ireland.

Participants  A total of 3971 subjects who purchased a particular brand of nicotine patch and logged‐on to use a free web‐based behavioral support program.

Intervention  Web‐based tailored behavioral smoking cessation materials or web‐based non‐tailored materials.

Measurements  Twenty‐eight‐day continuous abstinence rates were assessed by internet‐based survey at 6‐week follow‐up and 10‐week continuous rates at 12‐week follow‐up.

Findings  Using three approaches to the analyses of 6‐ and 12‐week outcomes, participants in the tailored condition reported clinically and statistically significantly higher continuous abstinence rates than participants in the non‐tailored condition. In our primary analyses using as a denominator all subjects who logged‐on to the treatment site at least once, continuous abstinence rates at 6 weeks were 29.0% in the tailored condition versus 23.9% in the non‐tailored condition (OR = 1.30; P = 0.0006); at 12 weeks continuous abstinence rates were 22.8% versus 18.1%, respectively (OR = 1.34; P = 0.0006). Moreover, satisfaction with the program was significantly higher in the tailored than in the non‐tailored condition.

Conclusions  The results of this study demonstrate a benefit of the web‐based tailored behavioral support materials used in conjunction with nicotine replacement therapy. A web‐based program that collects relevant information from users and tailors the intervention to their specific needs had significant advantages over a web‐based non‐tailored cessation program.
Gamma‐glutamyltransferase in fine‐needle liver biopsies of subjects with chronic hepatitis C
Authors: Paolicchi A. , Marchi S. , Petruccelli S. , Ciancia E. , Malvaldi G. , Pompella A.
Published: April 2005

Summary.  Serum gamma‐glutamyltransferase (GGT) is considered as a sensitive but rather nonspecific marker of hepatobiliary disease, including chronic hepatitis C virus (HCV) infection. Although its increase in HCV infection is associated with poor response to interferon‐α (IFN‐α) and poor prognosis, there is little knowledge of the reasons of its increase during disease.

Immunohistochemistry and enzyme histochemistry were performed on fine‐needle biopsies of subjects with HCV infection. GGT was detected in the lumen of bile ducts and in bile canaliculi. Furthermore, in subjects with elevated serum GGT, immunoreactive and catalytically active GGT was also detected on the sinusoidal surface of hepatocytes and diffuse cytoplasmic positivity appeared in isolated hepatocytes and hepatocellular foci. Antigen unmasking procedures showed the presence of GGT in the cytoplasm of mature and immature bile cells and of inflammatory cells. These results suggest that during chronic HCV infection there is a general enhancement of GGT activity within the liver. As the activity of several inflammatory mediators, such as leukotrienes, nitric oxide, and interleukins is modulated by GGT activity, the present findings suggest a direct relationship between serum GGT, enhanced intrahepatic GGT activity and prognosis and therapeutic outcome of chronic HCV infection.
HBsAg‐negative hepatitis B virus infections in hepatitis C virus‐associated hepatocellular carcinoma
Authors: Momosaki S. , Nakashima Y. , Kojiro M. , Tabor E.
Published: April 2005

Summary.  This study was conducted to evaluate reports that hepatitis B virus (HBV) DNA sequences can be found in the serum and/or tumour tissue from some hepatocellular carcinoma (HCC) patients who have no detectable hepatitis B surface antigen (HBsAg) in their sera. Such HBV infections would be highly atypical, because prospective studies have shown a clear succession of specific serologic markers during and after most HBV infections. As most HBsAg‐negative HCC patients in Japan have hepatitis C virus (HCV) infections, the present study was conducted to determine whether some of these patients actually have unrecognized HBV infections. Thirty newly diagnosed HCC patients from Kurume, Japan, with antibody to the hepatitis C virus (anti‐HCV) were studied. None of the 30 had HBsAg detectable in their serum. Of 22 for whom test results for antibodies to the hepatitis B core antigen (anti‐HBc) and antibodies to HBsAg (anti‐HBs) were available, 14 (64%) had anti‐HBc and anti‐HBs, four (18%) had anti‐HBc alone, and four (18%) had no HBV markers. Nested polymerase chain reaction was used to detect the HBV surface (S), core (C), polymerase (P) and core promoter gene sequences in the HCC tissues and in the adjacent nontumorous liver tissues. HBV DNA was detected in HCC and/or adjacent nontumorous liver in 22 of 30 (73%) patients [detected in both HCC and nontumorous liver in 19/30 patients (63%)]. Among the 22 patients with detectable HBV DNA, more than one HBV gene was detected in 10 (46%). Among the four patients whose sera were negative for all HBV markers, three had HBV DNA in either HCC and nontumorous liver (two cases) or only in the nontumorous liver (one case); HBV DNA could not be detected in tissues from the fourth patient. In 18 of 21 (86%) patients with detectable HBV core promoter sequences, mutations at both nucleotides 1762 (A–GT) and 1764 (G–A) in the core promoter region were found. No deletions were detected in the core promoter gene region of the type reported to be associated with some cases of HBsAg‐negative HBV infection. Thus, HBV DNA was detectable in 22 (73%) HBsAg‐negative, anti‐HCV‐positive HCCs, including three (10%) who were also negative for anti‐HBc and anti‐HBs. HBV mutations at both nucleotides 1762 (A–GT) and 1764 (G–A) in the core promoter region were found in the majority of cases, mutations that have previously been reported in HBV that is integrated in HCC DNA. In serologic surveys to determine etiologic associations of HCC, patients such as those in this study would have been incorrectly designated as having ‘HCV‐associated HCC,’ whereas the data in this study suggest that HBV could have played a role in the development of their HCCs.
The efficacy and safety of thymosin alpha‐1 in Japanese patients with chronic hepatitis B; results from a randomized clinical trial
Authors: Iino S. , Toyota J. , Kumada H. , Kiyosawa K. , Kakumu S. , Sata M. , Suzuki H. , Martins E. B.
Published: April 2005

Summary.  Thymalfasin (thymosin alpha‐1; Tα1) is a 28‐amino acid polypeptide that has shown efficacy in the treatment of chronic hepatitis B virus (HBV) infection. The objective of this study was to evaluate the long‐term, dose‐related efficacy and safety of Tα1 treatment in chronic hepatitis B patients with positive HBV‐DNA and abnormally high alanine aminotransferase (ALT) levels. A total of 316 patients were randomized to receive either 0.8 or 1.6 mg of Tα1 monotherapy for 24 weeks. At the end of the 72‐week observation period (12 months after cessation of therapy), 36.4% of patients in the 1.6‐mg treatment group achieved normalization of ALT, 30% achieved clearance of HBV‐DNA by branched DNA vs 15% by transcription‐mediated amplification, and 22.8% achieved clearance of HBe‐antigen. Patients in the 0.8‐mg treatment group achieved similar efficacy rates, although patients with advanced fibrosis demonstrated a significantly better response rate when treated with 1.6 mg of Tα1 monotherapy vs 0.8 mg (as determined by intragroup analysis; patients were not stratified by liver biopsy). All adverse drug reactions were mild and most involved the fluctuation of liver enzymes, which was most likely related to the positive immune effects caused by the response to Tα1 treatment. Adverse event incidence was similar in the 1.6‐ and 0.8‐mg treatment groups. In conclusion, Tα1 at doses of 0.8 and 1.6 mg exhibits long‐term efficacy against hepatitis B with a good safety profile.
Evidence of selection for low cognate amino acid bias in amino acid biosynthetic enzymes
Authors: Alves Rui , Savageau Michael A.
Published: April 2005

If the enzymes responsible for biosynthesis of a given amino acid are repressed and the cognate amino acid pool suddenly depleted, then derepression of these enzymes and replenishment of the pool would be problematic, if the enzymes were largely composed of the cognate amino acid. In the proverbial ‘Catch 22’, cells would lack the necessary enzymes to make the amino acid, and they would lack the necessary amino acid to make the needed enzymes. Based on this scenario, we hypothesize that evolution would lead to the selection of amino acid biosynthetic enzymes that have a relatively low content of their cognate amino acid. We call this the ‘cognate bias hypothesis’. Here we test several implications of this hypothesis directly using data from the proteome of Escherichia coli. Several lines of evidence show that low cognate bias is evident in 15 of the 20 amino acid biosynthetic pathways. Comparison with closely related Salmonella typhimurium shows similar results. Comparison with more distantly related Bacillus subtilis shows general similarities as well as significant differences in the detailed profiles of cognate bias. Thus, selection for low cognate bias plays a significant role in shaping the amino acid composition for a large class of cellular proteins.
The McbR repressor modulated by the effector substanceS‐adenosylhomocysteine controls directly the transcription of a regulon involved in sulphur metabolism ofCorynebacterium glutamicumATCC 13032
Authors: Rey Daniel A. , Nentwich Svenja S. , Koch Daniel J. , Rückert Christian , Pühler Alfred , Tauch Andreas , Kalinowski Jörn
Published: April 2005

In a recent proteomics study we have shown that themcbRgene ofCorynebacterium glutamicumATCC 13032 most probably encodes a transcriptional repressor of the TetR type, which regulates the expression of at least six genes involved in the synthesis of sulphur‐containing amino acids. By means of DNA microarray hybridizations we detected 86 genes with enhanced transcription in anmcbRmutant when compared with the wild‐type strain. Bioinformatic analysis identified the inverted repeat 5′‐TAGAC‐N6‐GTCTA‐3′ as a consensus sequence within the upstream region of 22 genes and operons, suggesting that the transcription of at least 45  genes is directly controlled by the McbR repressor. These 45 genes encode a variety of functions in  (S‐adenosyl)methionine  and  cysteine  biosynthesis, in sulphate reduction, in uptake and utilization of sulphur‐containing  compounds  and  in  transcriptional regulation. The function of the inverted repeat motif as potential McbR binding site in front of the geneshom,cysI,cysK,metKandmcbRwas verified experimentally by competitive electrophoretic mobility shift analysis. A systematic search for the potential effector substance modulating the function of McbR revealed that onlyS‐adenosylhomocysteine prevented the binding of McbR to its target sequence. These results indicate that the transcriptional repressor McbR directly regulates a set of genes comprising all aspects of transport and metabolism of the macroelement sulphur inC. glutamicum. As the activity of McbR is modulated byS‐adenosylhomocysteine, a major product of transmethylation reactions, the results point also to a novel regulatory mechanism in bacteria to control the biosynthesis ofS‐adenosylmethionine.
Bacillus subtilis antibiotics: structures, syntheses and specific functions
Authors: Stein Torsten
Published: April 2005

The endospore‐forming rhizobacterium Bacillus subtilis– the model system for Gram‐positive organisms, is able to produce more than two dozen antibiotics with an amazing variety of structures. The produced anti‐microbial active compounds include predominantly peptides that are either ribosomally synthesized and post‐translationally modified (lantibiotics and lantibiotic‐like peptides) or non‐ribosomally generated, as well as a couple of non‐peptidic compounds such as polyketides, an aminosugar, and a phospholipid. Here I summarize the structures of all known B. subtilis antibiotics, their biochemistry and genetic analysis of their biosyntheses. An updated summary of well‐studied antibiotic regulation pathways is given. Furthermore, current findings are resumed that show roles for distinct B. subtilis antibiotics beyond the ‘pure’ anti‐microbial action: Non‐ribosomally produced lipopeptides are involved in biofilm and swarming development, lantibiotics function as pheromones in quorum‐sensing, and a ‘killing factor’ effectuates programmed cell death in sister cells. A discussion of how these antibiotics may contribute to the survival of B. subtilis in its natural environment is given.
Measuring chromosome dynamics on different time scales using resolvases with varying half‐lives
Authors: Stein Richard A. , Deng Shuang , Higgins N. Patrick
Published: April 2005

The bacterial chromosome is organized into multiple independent domains, each capable of constraining the plectonemic negative supercoil energy introduced by DNA gyrase. Different experimental approaches have estimated the number of domains to be between 40 and 150. The site‐specific resolution systems of closely related transposons Tn3 and γδ are valuable tools for measuring supercoil diffusion and analysing bacterial chromosome dynamics in vivo. Once made, the wild‐type resolvase persists in cells for time periods greater than the cell doubling time. To examine chromosome dynamics over shorter time frames that are more closely tuned to processes like inducible transcription, we constructed a set of resolvases with cellular half‐lives ranging from less than 5 min to 30 min. Analysing chromosomes on different time scales shows domain structure to be dynamic. Rather than the 150 domains detected with the Tn3 resolvase, wild‐type cells measured over a 10 min time span have more than 400 domains per genome equivalent, and some gyrase mutants exceed 1000.
A yeast genetic system for the identification and characterization of substrate proteins transferred into host cells by the Legionella pneumophila Dot/Icm system
Authors: Campodonico Eva M. , Chesnel Laurent , Roy Craig R.
Published: April 2005

The Dot/Icm system is a type IVb secretion system used by Legionella pneumophila to modulate vesicular transport in both protozoan and mammalian host cells. It has been shown that proteins and processes that are highly conserved in all eukaryotic cells are targets for some of the proteins injected by the Dot/Icm system. For example, the Legionella protein RalF was shown previously to be a Dot/Icm substrate that functions as a guanine nucleotide exchange factor (GEF) for the Arf family of eukaryotic small GTP‐binding proteins. Here we show that ectopic production of the RalF protein in Saccharomyces cerevisiae interferes with yeast growth. Inhibition of yeast growth was found to be dependent on the ability of RalF to function as an Arf‐GEF in vivo. The possibility that other Dot/Icm substrate proteins would have the capacity to interfere with yeast growth was used as a rationale to screen plasmid libraries containing random fragments of Legionella chromosomal DNA positioned downstream of a galactose‐inducible promoter. This screen identified Legionella proteins that conferred a conditional growth defect when overproduced by yeast cultured in the presence of galactose. Most of the Legionella proteins identified were determined to be substrates of the Dot/Icm system. This screen led to the identification of a new Dot/Icm substrate protein that was called YlfA, for yeast lethal factor A. A paralogue of YlfA was identified on an unlinked region of the Legionella chromosome and this protein was also translocated by the Dot/Icm system. It was determined that a hydrophobic region near the N‐terminus of the YlfA protein and an adjacent region predicted to form a coiled‐coil domain were necessary for a biological activity that interfered with yeast growth. The YlfA protein did not decorate the Legionella‐containing vacuole during the first 7 h of infection but could be observed on the endoplasmic reticulum (ER)‐derived replicative vacuole and on punctate structures throughout the host cell at later stages. Ectopic production of YlfA in mammalian cells revealed that the N‐terminal hydrophobic domain in YlfA was able to localize the protein to early secretory organelles, including endoplasmic reticulum. These studies show that yeast genetics can be exploited to identify and characterize proteins that are injected into host cells by bacterial pathogens that utilize type IV secretion systems for pathogenesis.
Silkworm pathogenic bacteria infection model for identification of novel virulence genes
Authors: Kaito Chikara , Kurokawa Kenji , Matsumoto Yasuhiko , Terao Yutaka , Kawabata Shigetada , Hamada Shigeyuki , Sekimizu Kazuhisa
Published: April 2005

Silkworms are killed by injection of pathogenic bacteria, such as Staphylococcus aureus and Streptococcus pyogenes, into the haemolymph. Gene disruption mutants of S. aureus whose open reading frames were previously uncharacterized and that are conserved among bacteria were examined for their virulence in silkworms. Of these 100 genes, three genes named cvfA, cvfB, and cvfC were required for full virulence of S. aureus in silkworms. Haemolysin production was decreased in these mutants. The cvfA and cvfC mutants also had attenuated virulence in mice. S. pyogenes cvfA‐disrupted mutants produced less exotoxin and had attenuated virulence in both silkworms and mice. These results indicate that the silkworm‐infection model is useful for identifying bacterial virulence genes.
DksA represses ribosomal gene transcription in Pseudomonas aeruginosa by interacting with RNA polymerase on ribosomal promoters
Authors: Perron Karl , Comte Rachel , Van Delden Christian
Published: April 2005

In Escherichia coli transcription of ribosomal RNA (rRNA) is regulated by the H‐NS and Fis proteins, as well as by the small signal molecule ppGpp and the initiating nucleotides. During amino acid starvation, the concentration of ppGpp increases, and binding of this alarmone to RNA polymerase (RNAP) leads to inhibition of rRNA transcription, a regulatory event called stringent response. Here we show that in Pseudomonas aeruginosa DksA, a protein with pleiotropic effects, is a negative regulator of rRNA transcription both during exponential growth and stringent conditions. A dksA mutant overexpresses rRNA, without being affected in the production of ppGpp. Cell‐fractionation and chromosome immunoprecipitation experiments demonstrate that DksA is associated with DNA, in particular with promoters of ribosomal genes in vivo. The binding to rRNA promoters specifically increases during stringent response, and correlates with the binding of RNAP to these regions. Moreover DksA can be copurified with RNAP subunits in vivo. DNA band shift experiments show that DksA, in synergy with ppGpp, increases the binding of RNAP to ribosomal promoters. Therefore DksA might be a new regulator of rRNA transcription in P. aeruginosa.
The role of nucleoid‐associated proteins in the organization and compaction of bacterial chromatin
Authors: Dame Remus T.
Published: April 2005

The bacterial chromosomal DNA is folded into a compact structure called nucleoid. The shape and size of this ‘body’ is determined by a number of factors. Major players are DNA supercoiling, macromolecular crowding and architectural proteins, associated with the nucleoid, which are the topic of this MicroReview. Although many of these proteins were identified more than 25 years ago, the molecular mechanisms involved in the organization and compaction of DNA have only started to become clear in recent years. Many of these new insights can be attributed to the use of recently developed biophysical techniques.
Biosynthesis of the red antibiotic, prodigiosin, in Serratia: identification of a novel 2‐methyl‐3‐n‐amyl‐pyrrole (MAP) assembly pathway, definition of the terminal condensing enzyme, and implications for undecylprodigiosin biosynthesis in Streptomyces
Authors: Williamson Neil R. , Simonsen Henrik T. , Ahmed Raef A. A. , Goldet Gabrielle , Slater Holly , Woodley Louise , Leeper Finian J. , Salmond George P. C.
Published: April 2005

The biosynthetic pathway of the red‐pigmented antibiotic, prodigiosin, produced by Serratia sp. is known to involve separate pathways for the production of the monopyrrole, 2‐methyl‐3‐n‐amyl‐pyrrole (MAP) and the bipyrrole, 4‐methoxy‐2,2′‐bipyrrole‐5‐carbaldehyde (MBC) which are then coupled in the final condensation step. We have previously reported the cloning, sequencing and heterologous expression of the pig cluster responsible for prodigiosin biosynthesis in two Serratia sp. In this article we report the creation of in‐frame deletions or insertions in every biosynthetic gene in the cluster from Serratia sp. ATCC 39006. The biosynthetic intermediates accumulating in each mutant have been analysed by LC‐MS, cross‐feeding and genetic complementation studies. Based on these results we assign specific roles in the biosynthesis of MBC to the following Pig proteins: PigI, PigG, PigA, PigJ, PigH, PigM, PigF and PigN. We report a novel pathway for the biosynthesis of MAP, involving PigD, PigE and PigB. We also report a new chemical synthesis of MAP and one of its precursors, 3‐acetyloctanal. Finally, we identify the condensing enzyme as PigC. We reassess the existing literature and discuss the significance of the results for the biosynthesis of undecylprodigiosin by the Red cluster in Streptomyces coelicolor A3(2).
Candida albicans Cell‐Wall Fraction Exacerbates Collagen‐Induced Arthritis in Mice
Authors: Yordanov M. , Tchorbanov A. , Ivanovska N.
Published: April 2005

The immune system generates a specific response against most pathogens, while developing tolerance to self‐antigens. Commensal micro‐organisms can express molecular structures that mimic self‐epitopes. During acute infection, such pathogen may activate self‐reactive T‐cell clones promoting autoimmunity. In the present study, a β‐mercaptoethanol cell‐wall fraction (MF) from Candida albicans was injected into the paw of naïve ICR and BALB/c mice and into the paw of ICR mice with bovine collagen type II‐induced arthritis (CIA). Development of inflammation was monitored for 6 weeks. MF provoked a stable swelling and histopathologic changes in the injected joint, with a predominance of T‐helper 1 cytokines in ICR mice. In BALB/c strain, a swelling was observed only in the early period, with no evidence of joint pathology. Injection of the MF fraction exacerbated the disease in ICR mice with CIA, and this was associated with the elevation of interferon‐gamma and anti‐bovine type II collagen (bCII) immunoglobulin G2a antibodies. These results indicate that component(s) in the MF fraction cross‐react with bCII‐specific cells.
Reduced Release of Intact and Cleaved Urokinase Receptor in Stimulated Whole‐Blood Cultures from Human Immunodeficiency Virus‐1‐Infected Patients
Authors: Ostrowski S. R. , Piironen T. , Høyer‐Hansen G. , Gerstoft J. , Pedersen B. K. , Ullum H.
Published: April 2005

The blood levels of the soluble forms of the urokinase receptor (suPAR) are increased in human immunodeficiency virus (HIV)‐1‐infected patients. This study investigated whether the release of urokinase‐type plasminogen activator receptor (uPAR) in whole‐blood cultures was affected by HIV infection. The release of different uPAR forms in whole‐blood cultures incubated 24 h with or without phytohemagglutinin and lipopolysaccharide was analysed in 47 HIV patients and 19 controls. suPAR was measured by enzyme‐linked immunosorbent assay (ELISA) (bulk‐suPAR) and three different time‐resolved fluorescence immunoassays measuring three‐domain suPAR [suPAR(I–III)], three‐ and two‐domain suPAR [suPAR(I–III) + suPAR(II–III)] and one‐domain suPAR [suPAR(I)]. The uPAR release was correlated to leucocyte subpopulations and plasma levels of suPAR. The stimulated net whole‐blood culture release of bulk‐uPAR, uPAR(I–III), uPAR(II–III) and uPAR(I) was reduced in HIV patients (all P < 0.01), whereas the spontaneous bulk‐uPAR and uPAR(I–III) release was increased in HIV patients (both P < 0.05). The stimulated uPAR release in whole‐blood cultures correlated well to leucocytes and circulating suPAR levels in controls, whereas the correlation was weaker to leucocytes and nonexisting to circulating suPAR levels in HIV patients. These findings demonstrate that HIV infection affects stimulated and spontaneous uPAR release in whole‐blood cultures. Given that high blood levels of suPAR in HIV patients are linked to immune activation, the perturbations in uPAR release in whole‐blood cultures from HIV patients may also reflect immune activation.
Association of Interferon‐gamma +874(T/A) Single Nucleotide Polymorphism with the Rate of Tryptophan Catabolism in Healthy Individuals
Authors: Raitala A. , Pertovaara M. , Karjalainen J. , Oja S. S. , Hurme M.
Published: April 2005

Mechanisms induced by tryptophan (trp) catabolism are important in the regulation of both normal and pathogenetic immune responses. The key enzyme is indoleamine‐pyrrole 2,3‐dioxygenase (EC 1.13.11.42) (IDO) which converts trp to kynurenine (kyn), the main toxic metabolite. It is known that interferon‐gamma (IFN‐γ) is able to activate IDO. We wanted to analyse whether the strength of this mechanism would be under genetic control. To this end, we analysed the IFN‐γ+874(T/A) genotypes, which are known to have an effect on IFN‐γ production, of 309 healthy blood donors and correlated these to the levels of trp and kyn in their blood. The data obtained demonstrate that the presence of the high producer T allele was associated with increased IDO activity (i.e. elevated kyn and kyn/trp levels), but this effect was observed only in females. These data show that trp catabolism is genetically controlled by the IFN‐γ gene and may thus be operative in those disease conditions associated with the polymorphisms of the IFN‐γ gene.
A Sero‐Epidemiological Survey of Gelatin Sensitization in Young Japanese Children During the 1979–1996 Period
Authors: Saito A. , Kumagai T. , Kojima H. , Terai I. , Yamanaka T. , Wataya Y. , Umetsu M. , Umetsu A. , Yano S.
Published: April 2005

Recently, an increasing number of adverse reactions in children inoculated with live attenuated virus vaccines containing gelatin have been reported. However, the distribution, magnitude and rate of gelatin sensitization in the Japanese population have not been established. Here, the purpose was to investigate the distribution of children with positive gelatin immunoglobulin G (IgG) and/or IgE in Japan and to ascertain whether the incidence of positive antigelatin antibody cases among the general population, as reflected in the sample employed here, has been increasing during the period in question. The presence of IgE and IgG antibodies were measured against gelatin in 1600 panel sera collected from different age groups of Japanese children in Hokkaido/Sapporo from 1979 through 1996. Among the subjects, 39 had gelatin IgG‐ and/or IgE‐positive sera, and these were correlated with the time of obtaining the sera as well as with the age of the subjects. The older the subject and the later the period, the higher the sero‐incidence. Japanese children have become increasingly sensitized to gelatin, especially since the mid‐1990s.
Interactions of the antimicrobial peptide Ac‐FRWWHR‐NH2 with model membrane systems and bacterial cells
Authors: Rezansoff A.J. , Hunter H.N. , Jing W. , Park I.Y. , Kim S.C. , Vogel H.J.
Published: April 2005

Abstract:  The acetylated and amidated hexapeptide FRWWHR (combi‐2), previously identified by combinatorial chemistry methods, shows strong antimicrobial activity. The binding of the peptide to 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐[(phospho‐rac‐(1‐glycerol)] (POPG) and 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) vesicles was studied using fluorescence spectroscopy and isothermal titration calorimetry (ITC). Differential scanning calorimetry (DSC) with dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) multilamellar vesicles was performed to determine changes in the lipid phase behaviour upon binding the peptide. Two‐dimensional proton nuclear magnetic resonance (NMR) spectroscopy, to solve the bound peptide structure, was performed in the presence of dodecylphosphatidylcholine (DPC) and sodium dodecyl sulphate (SDS) micelles. The fluorescence, ITC and DSC studies indicate that the peptide interacts preferentially with lipid vesicles containing negatively charged head groups. Conformational information determined using NMR indicate that the combi‐2 peptide adopts a coiled amphipathic conformation when bound to SDS and DPC micelles. Leakage assays indicate that the peptide is not very efficient at causing leakage from calcein‐filled large unilamellar vesicles comprised of POPG/POPC (1 : 1). The rapid passage of either the fluorescent‐tagged peptides combi‐2 or the previously studied peptide Ac‐RRWWRF‐NH2 (combi‐1) into Escherichia coli and Staphylococcus aureus suggests that instead of membrane disruption, the main bactericidal site of action of these peptides might be located inside bacteria.
PRETREATMENT WITH INTRAVENOUS ASCORBIC ACID PRESERVES ENDOTHELIAL FUNCTION DURING ACUTE HYPERGLYCAEMIA (R1)
Authors: Mullan Brian A , Ennis Ciaran N , Fee Howard JP , Young Ian S , McCance David R
Published: April 2005

1. Acute hyperglycaemia may impair endothelial function. Ascorbic acid (AA), administered intra‐arterially, has been reported to improve endothelium‐dependent vasodilatation during a forearm hyperglycaemic clamp. Using a randomized, double‐blind, placebo‐controlled, cross‐over study, we investigated the potential for intravenous ascorbic acid to modify the endothelial response to acute systemic hyperglycaemia in humans.

2. Nine healthy male volunteers were recruited from the hospital staff. Endothelial function was determined by measuring the forearm blood flow responses to intrabrachial infusions of endothelium‐dependent (ED) and endothelium‐independent (EID) vasodilators. The endothelial function index (EFI) was derived from the ratio of ED and EID vasodilatation. Haemodynamic and endothelial function measurements were performed at baseline and then repeated 2 h after a systemic hyperglycaemic clamp (14 mmol/L). The subjects, studied on two separate occasions, were randomized to placebo or 2 g intravenous ascorbic acid prior to the initiation of hyperglycaemia.

3. After systemic hyperglycaemia with placebo pretreatment, the EFI fell from 1.08 ± 0.21 to 0.74 ± 0.13 (difference (95% confidence interval): 0.34 (0.20, 0.47); P < 0.001). When subjects were pretreated with ascorbic acid, the EFI was not affected by hyperglycaemia (1.11 ± 0.21 to 1.12 ± 0.17; P = 0.938). This difference between placebo and ascorbic acid was significant (P < 0.001). Plasma ascorbate concentrations decreased during hyperglycaemia and correlated directly with the reduction in the EFI (r = 0.798; P < 0.001).

4. Pretreatment with an intravenous bolus of ascorbic acid can prevent endothelial dysfunction during acute systemic hyperglycaemia. Therefore, ascorbic acid may have potential therapeutic use in clinical situations where acute hyperglycaemia may be a complication.