In their experiments with rodents, French scientists identified a receptor on the tongue that appears to detect dietary fat.

This goes against the traditional view that the taste buds pick up only five basic flavors: sweet, sour, salty, bitter and "umami," - a flavor associated with the food additive monosodium glutamate (MSG).

According to the researchers, led by Philippe Besnard of the University of Bourgogne, the fact that the tongue harbours receptors for fatty acids could have some impact on appetite control and obesity.

In the past scientists have suggested that the tongue may have a receptor designed to detect fat, but this study is the first to pinpoint one.

According to Besnard and his colleagues, the receptor, a protein called CD36, is already known to exist in many tissues and one of it's roles is involved in fat storage.

It is also called a fatty acid transporter, or FAT.

Rats and mice, along with many humans, have a natural preference for fatty food, and rats have already been shown to have CD36 proteins in their taste buds.

In order to see whether CD36 might be the tongue's fat detector, Besnard and his colleagues studied rats and mice that were either normal or had the gene for CD36 "knocked out," inactivating the protein.

They found that while the genetically normal animals naturally opted for fattier fare when given the choice, the CD36-deficient mice had no such preference.

When the researchers put fatty acids on the tongues of the normal animals, this alone triggered a release of fat-processing substances from the digestive organs.

The same was not true of mice lacking CD36 activity.

Besnard says that though the body's regulation of fat intake is complex, these findings point to the importance of CD36 receptors on the tongue.

The report is published in the November issue of the Journal of Clinical Investigation.

Fredricks and colleagues postulated that one reason for BV's persistent mystery is that scientists haven't identified the total community of bacteria that causes it. Indeed, the study found that most of the bacterial species detected in vaginal fluid are missed with conventional cultivation methods. The researchers catalogued a total of 35 bacterial species associated with BV, doubling the known species. Nineteen appear to be novel species, the study reported. The study identified three new strains, members of the Clostridium phylum, which researchers named BV-associative bacterium # 1, 2 and 3. They had specificities of 95 percent to 98 percent, meaning their detection in vaginal fluid reliably predicted the presence of BV. On the other hand, not all women with BV harbored these novel Clostridium-like bacteria.

"Numerous bacterial genera identified in this study have not, to our knowledge, been previously detected in the vaginal milieu with the use of cultivation methods," researchers said.

Rather than grow bacteria in a Petri dish -the standard identification method -Fredericks harvested DNA from bacteria, cloned segments of the DNA and used polymerase chain reaction (PCR) assays to analyze and sequence the segments. PCR analysis has a high degree of sensitivity and specificity. What made this possible is that every bacterium has the 16S ribosomal RNA gene, the gene that codes for ribosomes, which are the protein synthesizing machinery of cells.

"The 16S ribosomal RNA gene is unique for each different species of bacterium," said Fredricks. "By knowing the sequence of the gene you can identify the bacterium. We get a sort of molecular bar code." With these read outs, researchers went online to the GenBank database operated by the National Institutes of Health and looked for matches among the bacterial strains catalogued there.

Now that a more complete catalogue of bacterial strains has been assembled, Fredricks said work can begin looking for specific associations between individual species and the more adverse health problems linked to BV.

Fredricks said the larger lesson from PCR analysis is just how complex the human microbial ecosystem is. Other syndromes being investigated using PCR include ulcerative colitis, Crohn's disease, pneumonia and meningitis.

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