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Take me to the water
530
News & Comment
TRENDS in Microbiology Vol.9 No.11 November 2001
communities living below the earth’s surface might also ‘follow the water’, and could have implications for investigators searching for evidence of life on Mars. AV http://clasdean.la.asu.edu/news/ cyanobac.htm
Take me to the water
Yersinia pestis sequence
Microbiologists have discovered their very own desert rose. Filaments of cyanobacteria lying in the desert sand migrate to the surface when it rains. It was previously thought that the microorganisms behaviour could be explained by their attraction to light, but the new finding complicates matters. Ferran Garcia-Pichel of Arizona State University and Olivier Pringault of the University of Bordeaux observed the phenomenon in the field. The researchers then repeated the results in the lab, revealing that the tendency of the bacteria to track water surpassed the bugs’ tendency to track light. The discovery implies that bacterial
The genome of Yersinia pestis has been sequenced and published in Nature, revealing genes with an unusually fluid structure, readily rearranging themselves and picking up new genes from other microorganisms. It appears to have picked up genes directly from baculoviruses that infect insects, including one for a toxin that damages the midgut. It has also acquired pathogenicity islands, assemblies of genes from other bacteria that can cause human disease. All this means that more virulent strains of plague could emerge but, more ominously, it suggests that enhanced strains could be relatively easy to develop as biological weapons. Pneumonic plague is the form feared as a potential weapon, as it can be released as an aerosol and can spread directly among humans, without the intervention of fleas. Disturbingly, the former Soviet Union did develop such an agent of bacteriological warfare. CK http://www.nature.com
Viral evolution Is the structure of a common bacteriophage conserved from ancient times? Researchers have synthesized information gleaned from electron microscopy and X-ray crystallography to create a ‘quasi-atomic’ structure of bacteriophage PRD1. The findings confirm that PRD1 shares a striking structural resemblance to human adenovirus. The similarity invites questions about the evolutionary relationship between the two genetically distinct viruses. The international research team (led by investigators at the Wistar Institute) speculates that the shared icosahedran structure could have provided an evolutionary advantage. The new findings also have a practical application: it is hoped that knowledge of PDR1’s structure will aid in the development of phage therapies against antibiotic-resistant bacteria. AV http://www.eurekalert.org/pub_releases/ 2001-10/wi-sov100201.php
In Brief compiled by Cathel Kerr ([email protected]) and Alexandra Venter ([email protected])
Letters
The interactions of Bartonella with endothelial cells and erythrocytes The recent review on Bartonella by Christoph Dehio presented a fascinating insight into these unique pathogens1. As Dr Dehio points out, most members of the genus Bartonella can parasitize erythrocytes of their animal reservoir – a mechanism shared by only a few other bacteria. Bartonella bacilliformis invades and destroys human erythrocytes, leading to hemolytic anemia. However, it is the interaction of some Bartonella species with the human endothelium that is the most fascinating. Three Bartonella species (B. bacilliformis, Bartonella henselae and Bartonella quintana) attach, invade and cause proliferation of http://tim.trends.com
human endothelial cells in vitro and can cause angiogenic lesions in infected humans. In most areas of the world, B. henselae and B. quintana account for the vast majority of Bartonella infections in humans that result in clinical disease. To date, the ability to model human disease resulting from infection with either B. henselae or B. quintana has been limited to transient infection and an immunological response similar to cat-scratch disease2,3. Historically, the angiogenesis observed on infection with B. bacilliformis has relied upon nonhuman primates. Thus, there is currently no practical model of Bartonella-induced angiogenesis. The intraerythrocytic bacteremia Dr Dehio observed in rats using Bartonella tribocorum is important in understanding infection in animal reservoirs but is of limited value in modeling human disease. In the rat model, the periodic infection of
erythrocytes by B. tribocorum bears little resemblance to trench fever in humans as B. quintana is not thought to invade human erythrocytes. It is for these reasons that most pathogenesis studies have relied on in vitro endothelial cell systems. Such studies have yielded contradictory results regarding the bacterial cell localization of the angiogenic factor. Conley et al. concluded that the angiogenic factor is in an insoluble membrane fraction and Dehio associates the proliferative activity with the outer membrane1,4. However, Maeno et al. report that the angiogenic factor is exported into the culture supernatant5. Although it might be possible for an exported protein to be transiently associated with the outer membrane, these reports seem contradictory. In our own laboratory, B. henselaeinduced proliferation of primary
0966-842X/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S0966-842X(01)02177-1
News & Comment
TRENDS in Microbiology Vol.9 No.11 November 2001
communities living below the earth’s surface might also ‘follow the water’, and could have implications for investigators searching for evidence of life on Mars. AV http://clasdean.la.asu.edu/news/ cyanobac.htm
Take me to the water
Yersinia pestis sequence
Microbiologists have discovered their very own desert rose. Filaments of cyanobacteria lying in the desert sand migrate to the surface when it rains. It was previously thought that the microorganisms behaviour could be explained by their attraction to light, but the new finding complicates matters. Ferran Garcia-Pichel of Arizona State University and Olivier Pringault of the University of Bordeaux observed the phenomenon in the field. The researchers then repeated the results in the lab, revealing that the tendency of the bacteria to track water surpassed the bugs’ tendency to track light. The discovery implies that bacterial
The genome of Yersinia pestis has been sequenced and published in Nature, revealing genes with an unusually fluid structure, readily rearranging themselves and picking up new genes from other microorganisms. It appears to have picked up genes directly from baculoviruses that infect insects, including one for a toxin that damages the midgut. It has also acquired pathogenicity islands, assemblies of genes from other bacteria that can cause human disease. All this means that more virulent strains of plague could emerge but, more ominously, it suggests that enhanced strains could be relatively easy to develop as biological weapons. Pneumonic plague is the form feared as a potential weapon, as it can be released as an aerosol and can spread directly among humans, without the intervention of fleas. Disturbingly, the former Soviet Union did develop such an agent of bacteriological warfare. CK http://www.nature.com
Viral evolution Is the structure of a common bacteriophage conserved from ancient times? Researchers have synthesized information gleaned from electron microscopy and X-ray crystallography to create a ‘quasi-atomic’ structure of bacteriophage PRD1. The findings confirm that PRD1 shares a striking structural resemblance to human adenovirus. The similarity invites questions about the evolutionary relationship between the two genetically distinct viruses. The international research team (led by investigators at the Wistar Institute) speculates that the shared icosahedran structure could have provided an evolutionary advantage. The new findings also have a practical application: it is hoped that knowledge of PDR1’s structure will aid in the development of phage therapies against antibiotic-resistant bacteria. AV http://www.eurekalert.org/pub_releases/ 2001-10/wi-sov100201.php
In Brief compiled by Cathel Kerr ([email protected]) and Alexandra Venter ([email protected])
Letters
The interactions of Bartonella with endothelial cells and erythrocytes The recent review on Bartonella by Christoph Dehio presented a fascinating insight into these unique pathogens1. As Dr Dehio points out, most members of the genus Bartonella can parasitize erythrocytes of their animal reservoir – a mechanism shared by only a few other bacteria. Bartonella bacilliformis invades and destroys human erythrocytes, leading to hemolytic anemia. However, it is the interaction of some Bartonella species with the human endothelium that is the most fascinating. Three Bartonella species (B. bacilliformis, Bartonella henselae and Bartonella quintana) attach, invade and cause proliferation of http://tim.trends.com
human endothelial cells in vitro and can cause angiogenic lesions in infected humans. In most areas of the world, B. henselae and B. quintana account for the vast majority of Bartonella infections in humans that result in clinical disease. To date, the ability to model human disease resulting from infection with either B. henselae or B. quintana has been limited to transient infection and an immunological response similar to cat-scratch disease2,3. Historically, the angiogenesis observed on infection with B. bacilliformis has relied upon nonhuman primates. Thus, there is currently no practical model of Bartonella-induced angiogenesis. The intraerythrocytic bacteremia Dr Dehio observed in rats using Bartonella tribocorum is important in understanding infection in animal reservoirs but is of limited value in modeling human disease. In the rat model, the periodic infection of
erythrocytes by B. tribocorum bears little resemblance to trench fever in humans as B. quintana is not thought to invade human erythrocytes. It is for these reasons that most pathogenesis studies have relied on in vitro endothelial cell systems. Such studies have yielded contradictory results regarding the bacterial cell localization of the angiogenic factor. Conley et al. concluded that the angiogenic factor is in an insoluble membrane fraction and Dehio associates the proliferative activity with the outer membrane1,4. However, Maeno et al. report that the angiogenic factor is exported into the culture supernatant5. Although it might be possible for an exported protein to be transiently associated with the outer membrane, these reports seem contradictory. In our own laboratory, B. henselaeinduced proliferation of primary
0966-842X/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved. PII: S0966-842X(01)02177-1