This web page was produced as an assignment for an undergraduate course at Davidson College.

The "Sweet Tooth" Gene

Should you blame it on your sweet tooth or your sweet gene?

Introduction:

Recent studies have shown that a gene present in humans and mice helps people detect "sweetness" in food and beverages.  The function of the gene is not conclusively proven, but the evidence is pretty strong.

In 2001, two teams of researchers associated with the Howard Hughes Medical Institute (HHMI) independently identified a gene that acts as a likely receptor for sweet compounds. Discovery of the candidate sweet receptor gene was reported in two articles:

Both groups named the candidate sweet receptor gene T1R3 or TAS1R3, for "taste receptor family 1, number 3."   This gene is selectively expressed in the membranes of taste cells and not in other cells in the tongue or anywhere else in the body. 

The Popular Press:

BBC News Online: Sweet Tooth Gene Found

The article begins with the line "Craving sweets has a genetic basis, scientists have revealed."  This opening statement is likely to engage the attention of several readers.  The article goes to say that a gene has been found that enables the taste receptors in the tongue to identify things as sweet.  I particularly like how the article explains in layman's terms, albeit briefly, the methods used by two independent teams of researchers to track down the gene.  No claims are made about the significance of the discovery, other than the possibility that it might potentially lead to the development of new sweeteners and a better knowledge of why some individuals have a sweet tooth.

The Scientific Article:

 Nature Genetics: Taslr3, encoding a new candidate taste receptor, is allelic to the sweet responsiveness locus, Sac.

The research group worked with the Sac locus in the mouse genome as a starting point. This is a region of the mouse chromosome 4 which has been known to govern the preference for sweets.  Studies were conducted on two strains of lab mice -- one liked drinking water laced with saccharin or sugar ("taster" strain) and the other preferred plain water ("non-taster" strain).  There were differences between the gene sequences of the two strains.  To identify the human Sac locus, the team searched for candidate genes within a region of approximately one million base pairs of the sequenced human genome to the region of Sac in mice.  From this search they identified a likely candidate -- TAS1R3.

Links:

References:

Briggs, Helen. Sweet Tooth Gene Found. BBC News Online: April 23, 2001.

Max, M. et al. Taslr3, encoding a new candidate taste receptor, is allelic to the sweet responsiveness locus, Sac. Nature Genetics (2001).

 


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