Olfactory receptor neurons select which odor receptors to express

May 28, 2008

It may appear difficult to reconcile the fact that almost every cell in the body of an animal has an identical dose of genes with the variety of different appearances and properties cells can display—bone, skin, hair, muscle, and many more. This may seem even more complex given that all of these tissue types derive originally from a single fertilized egg cell. Understanding the many regulatory mechanisms that create different cells from a single template is the work of developmental biology.

A new paper published this week in the open-access journal PLoS Biology looks at this problem in the olfactory system of the fruit fly, where the ability to discriminate odors depends on receptor cells expressing different patterns of receptor genes, despite each cell having the same set of genes to choose from. The paper, by Anandasankar Ray and colleagues at Yale University, shows that receptor patterns are controlled by DNA sequences upstream of the receptor genes.

In the fruit fly Drosophila, there are two organs involved in smell: the antennae and the maxillary palps—the latter being part of the mouth. In these palps, there are always six types of neurons, cells that transmit information from the sensing part to the brain. Each type of neuron has a different, predictable pattern of olfactory receptors. How a neuron knows which receptors to express was, until now, a mystery.

By comparing the recently published genetic sequences of 12 species of Drosophila, Ray and colleagues identified regions of DNA near the receptor genes that are almost identical in all species. They hypothesized that these represented control regions, which are important for determining how genes are expressed. By altering the control regions experimentally, they have shown that this is true; these highly conserved regions act like zip codes, determining where the receptors end up. Interestingly, some regions positively regulate gene expression: when they are damaged, the receptor fails to be expressed in neurons where it would normally appear. Other regions negatively regulate receptor expression (stopping receptors from appearing in the wrong neurons) so that when the regulator is experimentally blocked, the related receptor appears in more neurons than it should.

Interestingly, the regulatory sequences identified in this study may also have another role in the nervous system. These controlling elements might also be apparent in the process of axon guidance, which connects the olfactory neurons to neurons in the antennae. This complex connection suggests that the process goes beyond the expression of olfactory neurons, and also contributes to the design and development of the fruit fly’s greater nervous system.

Citation: Ray A, van der Goes van Naters W, Carlson JR (2008) A regulatory code for neuron-specific odor receptor expression. PLoS Biol 6(5): e125. doi:10.1371/journal.pbio.0060125

Source: Public Library of Science

Explore further: New research uncovers brain circuit in fruit fly that detects anti-aphrodisiac

Related Stories

A unique on-off switch for hormone production

February 23, 2012

Weizmann scientists have revealed a new kind of on-off switch in the brain for regulating the production of a main biochemical signal from the brain that stimulates cortisol release in the body.

Quantum Criticality in life's proteins (Update)

April 15, 2015

(Phys.org)—Stuart Kauffman, from the University of Calgary, and several of his colleagues have recently published a paper on the Arxiv server titled 'Quantum Criticality at the Origins of Life'. The idea of a quantum criticality, ...

The origins of polarized nervous systems

March 3, 2015

(Phys.org)—There is no mistaking the first action potential you ever fired. It was the one that blocked all the other sperm from stealing your egg. After that, your spikes only got more interesting. Waves of calcium flooding ...

Recommended for you

New Horizons team selects potential Kuiper Belt flyby target

August 29, 2015

NASA has selected the potential next destination for the New Horizons mission to visit after its historic July 14 flyby of the Pluto system. The destination is a small Kuiper Belt object (KBO) known as 2014 MU69 that orbits ...

Interactive tool lifts veil on the cost of nuclear energy

August 24, 2015

Despite the ever-changing landscape of energy economics, subject to the influence of new technologies and geopolitics, a new tool promises to root discussions about the cost of nuclear energy in hard evidence rather than ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.