More than a billion people are at risk for infection with filarial nematodes, parasites that cause elephantiasis, African river blindness, and other debilitating diseases in more than 150 million people worldwide. The nematodes themselves play host to bacteria that live within their cells, but in this case, the relationship is classic mutualism, with each benefiting from the other. Indeed, the Wolbachia bacterium is so crucial to its host nematode that apparently eradicating it with antibiotics severely compromises the nematode's ability to complete its life cycle within its human host. Thus, understanding the details of this relationship may help identify new strategies for controlling diseases caused by filarial nematodes. In a new study published in the freely-available online journal PLoS Biology, Barton Slatko and colleagues present the complete DNA sequence of the Wolbachia pipientis strain within Brugia malayi, a parasitic nematode responsible for lymphatic filariasis.
This Wolbachia genome is small, only about a million base pairs, and many metabolically critical genes have degraded through mutation to the point of uselessness. This phenomenon, called reductive evolution, is typical of long-term symbioses, as the two partners increasingly complement one another's biochemical activities.
Slatko and colleagues enumerate a variety of pathways that have either been degraded or preserved, and highlight patterns in the genome structure through comparisons with other bacteria. For example, Wolbachia can manufacture some essential metabolic coenzymes, which do not appear to be made by its host. Conversely, it cannot synthesize amino acids and a variety of other vitamins and cofactors, and probably depends on the nematode to supply them.
One discovery of possible significance is the presence in the bacterium of the synthetic pathway for heme - the oxygen-carrying iron component of hemoglobin. The nematode may require heme for synthesis of develPage: 1 2 Related biology news :1
. Anti-bacterial additive widespread in U.S. waterways2
. Discovery of key proteins shape could lead to improved bacterial pneumonia vaccine3
. Scientists discover that host cell lipids facilitate bacterial movement4
. Protein prevents detrimental immune effects of bacterial sepsis5
. Researchers develop new method for facile identification of proteins in bacterial cells6
. A virus-like hitchhiker may trigger bacterial meningitis7
. Using the genomic shortcut to predict bacterial behavior8
. Eliminating bacterial infections out of thin air9
. Student scientists create living bacterial photographs10
. Researchers identify molecular anchor that allows bacterial invasion of central nervous system11
. Scientists determine structure of enzyme that disrupts bacterial virulence