Sentences with word «haltere»

Reduced morphogen availability causes a reduction in haltere size relative to the wing.

My first insight came from removing Ubx function from random clusters of haltere cells (2).

This means that Ubx does not control haltere size cell - autonomously by, for example, acting directly on cell cycle or apoptotic checkpoints.

Drosophila has two true wings that develop from imaginal discs of 50,000 cells and two smaller balancing organs called halteres that form from imaginal discs of 10,000 cells.

While studying how Ubx levels are controlled in wild - type halteres, I found that when Ubx protein levels rise, subsets of overlapping transcriptional input into the Ubx promoter become silenced (8).

To determine how halteres work, Leif Ristroph of Cornell University in Ithaca, New York, placed tiny magnetic rods on the backs of fruit flies and released them.

But while Greek Olympians had the help of stone or metal hand weights known as halteres, gibbons leap up to 10 meters without assistance.

The mosquito is a member of the family Culicidae; these insects have a pair of scaled wings, a pair of halteres, a slender body, and long legs.

In lieu of hind wings, they have two tiny sensors, called halteres, that measure changes in direction.

It is thought that the halteres are wired directly to the wing - control system, allowing them to recover quickly.

In the haltere, the same is true of the regulator of the size regulators: Heterozygous Ubx mutant flies have enlarged halteres (1), and flies with extra copies of the Ubx locus have shrunken halteres (7).

Indeed, transcription of decapentaplegic (dpp), a growth - promoting morphogen of the BMP family, is reduced in the haltere in comparison with the wing (2).

Ubx reduces the size of the haltere imaginal disc relative to that of the wing by decreasing the production and mobility of growth - promoting morphogens (for example, Dpp).

Thus I was able to ask how the expression of this single gene limits the size of the haltere.

For example, the Wnt and Hedgehog morphogen pathways are also altered in the haltere relative to the wing (4, 5).

As expected, the resulting Ubx mosaic halteres are larger than wild - type halteres.

In the haltere, I found Dpp signaling to be largely restricted to the cells in which it is produced (2).

We know that all differences between these appendages are specified by the expression of the Hox gene Ultrabithoax (Ubx) in the haltere and its absence from the wing (1).

Despite (or perhaps because of) the silencing of subsets of Ubx enhancers, Ubx protein levels remain normal in the outcrossed progeny, and their halteres develop perfectly.

Ubx converts one tkv repressor into a repressor of a second tkv repressor, thereby upregulating tkv levels in all haltere cells.

Ubx impedes morphogen mobility in the haltere by up - regulating the receptor throughout the haltere and repressing an HSPG in the posterior half of the haltere.

In the haltere, I found that Ubx works with the posterior transcription factor engrailed to selectively repress the HSPG dally in the posterior compartment.

Because receptor binding impedes morphogen mobility, I examined the expression pattern of the Dpp receptor thickveins (tkv) and found it to be strongly up - regulated in the haltere compared with the wing.

The mechanism by which Ubx orchestrates these changes in the haltere is a telling example of selector gene function.

Furthermore, the pattern of Dpp pathway activation is altered between the haltere and the wing, not just quantitatively but also qualitatively (see the figure).

As a consequence, morphogen mobility is severely impaired in the posterior side of the tissue, causing the posterior of the haltere to be smaller than the anterior (5)(see the figure).

I was able to show that the Dpp mobility restriction in the haltere is due in large part to transcriptional up - regulation of tkv.

The alterations in transcription of dpp and tkv account for much of the reduced size of the haltere relative to the wing (2).

Figure 5: The regulation of some genes differs between the wing (left) and haltere (right) imaginal discs of Drosophila and is under the control of the Ultrabithorax Hox gene.