Paranotal lobe theory - think
Direct flight: muscles attached to wings. Large insects only The Odonata dragonflies and damselflies have direct flight musculature, as do mayflies. Direct flight[ edit ] Unlike other insects, the wing muscles of the Ephemeroptera mayflies and Odonata dragonflies and damselflies insert directly at the wing bases, which are hinged so that a small movement of the wing base downward, lifts the wing itself upward, very much like rowing through the air. Dragonflies and damselflies have fore and hind wings similar in shape and size. Each operates independently, which gives a degree of fine control and mobility in terms of the abruptness with which they can change direction and speed, not seen in other flying insects. This is not surprising, given that odonates are all aerial predators, and they have always hunted other airborne insects. The Neoptera , including butterflies and most other insects, have indirect flight musculature. paranotal lobe theoryInduction of gene expression by Egfr in the ventral-most rows of cells occurs for the argos, orthodenticle, and tartan genes. To test if induction of vein by Egfr is also mediated by Pointed P1, vein expression was examined in pointed mutant embryos. Traces of expression are observed in the midline in stage 10 embryos only, whereas no expression is displayed by the ventral-most and lateral ectodermal cell rows at stage 11, thus showing that vein paranotal lobe theory is defective in pointed mutants. Elimination of Pointed activity can also be obtained in the following manner: paranotal lobe theory activated form of Yan, in which the inactivating MAP kinase phosphorylation sites have been mutated, blocks the activity of Pointed by competing for the same DNA-binding sites.
Indeed, when activated, Yan is ectopically expressed in the Kruppel domain the endogenous expression of vein is abolished in that region. To examine if Pointed P1 is sufficient for induction, vein expression was examined in embryos in which Pointed P1 was expressed in the Kruppel domain.
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Indeed, expression of vein in the same domain is observed. These results demonstrate that under conditions of ectopic expression, Pointed P1 is necessary and sufficient for vein expression Golembo, During oogenesisdorsal follicle cells differentiate into either appendage-producing or midline cells, resulting in patterning in the dorsal follicle cell layer. Pointed, an ETS transcription factor, is required in dorsal follicle cells paranotal lobe theory this patterning.
Loss of pointed results in the loss of midline cells and an excess of appendage-forming cells, a phenotype associated with overactivation of the EGF receptor pathway paranoal the dorsal region. Overexpression of pointed leads to a phenotype similar to that generated by loss of the EGF receptor pathway. This suggests that Pointed normally down-regulates EGF receptor signaling in the midline to generate patterning in the dorsal paranotal lobe theory.
By stage 8, expression is restricted to posterior follicle cells. During stageP1 is detected in dorsal-anterior and posterior follicle paranotal lobe theory. During later stages, both these expression patterns refine into two areas: two dorsal patches and two posterior half-circles. P2 transcript expression is also detected during oogenesis, both in the germ line and follicle cells. Follicle cell expression is observed in meme economist egg chambers in a pattern resembling the early P1 expression pattern in dorsal-anterior follicle cells.
During later stages, P2 expression is restricted to two groups of anterior dorsolateral follicle cells that flank the oocyte nucleus. Whereas two dorsolateral dorsal appendages are detected in paranotal lobe theory eggs, pointed mutant appendages are four times wider than a single wild type appendage, suggesting that the phenotype does not result from two appendages fusing together, but rather fromcells in the middle region taking on an appendage-producing cell fate.
These data indicate a novel antagonistic function for Pointed in oogenesis; in response to activation of the EGF receptor, pointed is expressed and negatively regulates the EGF receptor pathway Morimoto, The specific tracheal branching defects observed in unplugged mutant embryos prompted an examination of the relationship between unpg and pointed pnt ; pnt is expressed in tracheal placodes and in the developing tracheal branches. In the absence of pnt gene function, tracheal cells fail to migrate and paranotal lobe theory do not extend to target tissues.
In particular, stalling of the ganglionic branches at the paranotal lobe theory oblique musculature in hypomorphic pnt embryos is reminiscent of the most extreme phenotype observed in unpg embryos. To determine the regulatory relationship between pnt and unpg genes, pnt homozygous embryos were immunostained with Unplugged-specific antibody, in order to follow the fate of the ganglionic branches.
At stage In pnt mutant embryos, no migratory cells that are expressing Unpg protein can be detected; however, a few precursor cells accumulating low levels of Unpg protein occasionally can be identified. By stage 14, the ganglionic paranotal lobe theory of normal embryos are well developed, as is evident from a group of 8 to 9 unpg-expressing cells along the ventrolateral region of each hemisegment. In pnt mutant embryos, only 3 to 4 unpg-expressing cells can be detected; these unpg-expressing cells are clustered in a group suggesting that the precursor cells remain immobile and fail to extend from the tracheal pits. These results suggest that the ganglionic branch phenotype in pointed embryos may be in part due to a loss or reduction of unpg gene expression and failure of learn more here cells to extend into the CNS Chiang, It would be of interest to determine if unpg functions downstream of pnt in the ventral midline of the CNS.]
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