Larval cells

Larva Trigger workers to cap larval cells Methyl linoleate 82, linolenate 84, oleate 56, palmitate 78 [147]... 

Developmental changes - Much of what is known about development comes from study of the fruit fly Drosophila melanogaster. As the larva of this insect develops, groups of cells are set apart as disklike structures called imaginal disks (Figure 28.45). These groups of cells will form specific parts of the adult fly. As the larva metamorphoses, larval cells are destroyed by autolysis, and each imaginal disk develops into a different portion of the adult. 

Bacillus thuringiensis produces a variety of organic compounds which are toxic to the larvae of certain susceptible insect hosts. Among the toxic entities are proteinaceous crystals, probably three soluble toxins, and certain enzymes. The protein material is the major toxin active in killing lepidopterous larvae. The protein is formed by the cells apparently in close synchrony with sporulation, and its nature is a constant function of bacterial strain. The mode of action of the protein is under study. The sequence of events in the pathology observed is probably solubilization of the crystal (enzymatic or physical)—>liberation of toxic unit—>alteration of permeability of larval gut wall— change in hemolymph pH—>invasion of hemolymph by spores or vegetative cells of the bacterium. 

As mentioned above, Ddc is expressed in only about 150 cells within the Drosophila larval CNS. Figure 3 shows a cartoon illustrating these cells,... 

Figure 3. Sketch of DDC-expressing neurons in the Drosophila larval CNS. The CNS consists of brain lobes and a segmented ventral ganglion. Filled circles represent dopamine cells open circles represent serotonin cells grayed circles represent DDC cells that contain no detectable tyrosine hydroxylase or serotonin immunoreactivity, indicating that these cells may produce neither transmitter (Lundell and Hirsh, 1994). M, medial dopamine neurons VL, ventrolateral serotonin neurons DL, dorsolateral dopamine neurons. The hatched rectangle shows the region of the ventral ganglion that is shown in Figures 4 and 6.

Figure 8. Colocalization of DDC and ZFH-2 in larval CNS. This figure shows abdominal segments 4-7 of a third instar larval CNS. DDC im-munoreactivity is cytoplasmic and is shown in red, whereas ZFH-2 im-munoreactivity is nuclear and is shown in green. Only the outside cell of each pair of serotonin neurons expresses ZFH-2. One medial dopamine cell shown at the top also shows ZFH-2 expression. This projection does not include the dorsolateral cells, which also express ZFH-2. A similar projection has been published in Lundell and Hirsh (1992).

Larval endocycles regulation at G/S by cell growth and nutrition... 

This mode of regulation seems appropriate to the ERTs since their cells are already terminally differentiated, and their primary function is to grow and provide a nutrient rich incubator for the undifferentiated neuroblasts and imaginal cells that eventually produce the reproductive adult. The response of these undifferentiated progenitor cells to food withdrawal is quite unlike that of the ERTs. Larval neuroblasts and imaginal disc cells continue to proliferate for many days after a larva is starved, and seem to complete their normal proliferation programs. In this instance the ERTs lose mass, presumably as they transfer stored nutrients to the developing nervous system and the discs. 

Leevers It is unnecessary most larval (polyploid) cells are going to lyse during metamorphosis. 

Chia I can t think of a good way of mislocalizing Pins. With Inscuteable, early on in embryogenesis it is expressed in a single domain and nowhere else. The cells give rise to some of the cells that become the larval brain. The spindle in this region forms parallel to the surface and reorients at 90°, perpendicular to the surface of the embryo. These cells which don t express Insc set up their spindle parallel and divide parallel to the surface. If you force Insc expression in these cells they will reorient. 

Bryant From what we have done with the genetics, it looks like they are required for larval growth in general. At least two other cell lines have been shown to condition the medium in this way. 

Amhros In the cki mutant, where the cells divide in the middle of the second larval stage, they seem to divide without losing their tri-potent capacity. In the cki mutant we just double the number of cells. 

Several parameters of the larval niche have been evaluated in this in vitro model. Results indicate that T. spiralis establishes its niche in cell cultures. First, the broad host range of T. spiralis has been reproduced in cultured cells. The nematode is known to infect a diversity of vertebrate... 

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