Environmentally induced development defects in Drosophila.
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Animals↗
Biomedical subjects
H K Mitchell
Publications and source records attributed to H K Mitchell.
Stages of cell hair construction in Drosophila.
The construction of cell hairs (trichomes) on the wings of Drosophila occurs in synchrony on 30,000 cells over a period of about 20 hr. Changes in both morphology and patterns of protein synthesis occur rapidly during this time period. In this report we describe the use of stress-induced (heat shock) abnormalities in morphogenesis to provide further details on the stepwise processes of differentiation within single wing cells. A cartoon summary of the overall process and a discussion of some possible mechanisms is included.
Animals↗
Epithelial differentiation in Drosophila pupae.
The construction of cell hairs on the wings in developing pupae of Drosophila provides a unique system for studies of the regulation of differentiation in the absence of cell division. Early steps in hair construction are the extrusion of cell hairs and the deposition of the external impervious layer called "cuticulin." Some properties of six of the most abundant proteins that are present during the early stages of hair construction are described. These proteins make up about 40% of the total protein of the preparation.
Animals↗
Genetic mapping of the coding regions for three heat-shock proteins in Drosophila melanogaster.
We describe variants of three heat-shock proteins of Drosophila melanogaster and their use to map the chromosome regions that contain the coding sequences for these proteins. All three map to a region on chromosome 3L that includes only one heat-shock puff, designated as 67B. The results imply that the genes coding for at least three heat-shock proteins are included within the 67B region.
Animals↗
Heat shock and phenocopy induction in Drosophila.
Differentiation of the single cells that yield bristles and hairs in Drosophila has been examined by studies of phenocopies induced by heat shock. Phenocopies that resemble the mutants hook and javelin are produced by application of the stress within narrow and specific time ranges during metamorphosis. Double phenocopies can be induced by successive heat shocks at appropriate time intervals. Phenocopy production may be related to heat shock effects on RNA synthesis through a feedback inhibition of transcription by heat shock proteins.
Animals↗
The prepupal salivary glands of Drosophila melanogaster.
Evidence is presented in support of the concept that the larval salivary gland of Drosophila melanogaster continues to function as an important secretory organ throughout prepupal stages and after pupation. Just after puparium formation, and at other later periods, the glands appear to be in the process of disintegration, but each time they recover until after pupation. Nuclear blebbing occurs through the time of survival of the glands, but is shown not to involve transport of RNA out of the nucleus. Transport in and out of the nucleus is clearly rapid and in a steady state as compared to the massive and intermittent export of cytoplasmic substance into the lumen of the gland.
Animals↗
Transcriptional changes in pupal hypoderm in Drosophia melanogaster.
Transcriptional changes with development of the imaginal thoracic hypoderm of Drosophila melanogaster were evaluated by studies on pulse labeling and total composition with respect to protein. Evidence presented indicates that certain glycoproteins produced by prepupal salivary glands are important for bristle development long after the salivary gland is histolyzed. Striking changes in protein synthesis with development can be correlated with major hypodermal functions such as bristle formation, chitin deposition, and a moltlike process which occurs around 52 hr after puparium formation.
Animals↗
Necrotizing encephalitis in skunks caused by Herpes simplex virus.
Herpes simplex virus was isolated from the brain of a wild skunk (Mephitis mephitis) which had clinical neurological disease. In the brain of this skunk and in brain of skunks inoculated intracerebrally, there were areas of necrosis in the grey matter of the cerebral cortex and to a lesser extent in the brain stem. Intranuclear inclusions occurred in neurons and glial cells with vascular cuffing by mononuclear cells and a few neutrophils. Skunks inoculated intravenously had extensive focal necrosis in the liver and adrenal glands.
Adrenal Glands↗
Bee venom phospholipase A2; effects on Drosophila larvae, HeLa cells and membranes.
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Animals↗
A new method of in situ hybridization.
A new method for gene mapping at the chromosome level using in situ hybridization and scanning electron microscopy is described and has been applied to mapping the rRNA genes of Drosophila melanogaster. Biotin is covalently attached to Drosophila rRNA via a cytochrome c bridge at a ratio of one cytochrome-biotin per 130 nucleotides by a chemical procedure. Polymethacrylate spheres with a diameter of ca. 60 nm are prepared by emulsion polymerization and are covalently attached to the protein avidin at a ratio of 5-20 avidins per sphere. The biotin-labeled rRNA is hybridized to denatured DNA in a chromosome squash. Upon incubation with a sphere solution, some of the biotin sites become labeled with spheres because of the strong non-covalent interaction between biotin and avidin. The chromosome squash is examined in the scanning electron microscope (SEM). Polymer spheres, which are visible in the SEM, are observed to label the nucleolus, where the rRNA genes are located.
Animals↗
Rapidly labeled proteins on the salivary gland chromosomes of Drosophila melanogaster.
Experiments on short-term and pulse-chase labeling of chromosome proteins of the salivary glands of Drosophila melanogaster show unique patterns of label in the vicinity of chromosome puffs. A high turnover rate is indicated for these nonhistone proteins, which appear to form a fibrous sheath around the chromosomes. Acrylamide gel analyses of the chromosomal proteins that are quickly labeled, comparing compositions at different stages of development with compositions after heat shock, show that all are different and dependent on which chromosomal puffs are active and producing messenger RNA. The necessity for a continuous and rapid interchange of protein between the nucleus and cytoplasm is indicated, and it appears that regulation of gene activity must be related to this dynamic state of protein exchange. From the technical standpoint, it has been found that scanning electron microscopy (SEM) is especially useful for observing silver grains on opaque autoradiographs. It appears also that SEM will prove useful in a variety of studies of chromosome structure.
Animals↗
Phenol oxidase activation in Drosophila: a cascase of reactions.
Our earlier evidence concerning the complexity of the activation process for Drosophila phenol oxidase has been confirmed by separation and purification of six proteins involved. This is a minimal number required in a reaction series or cascade to yield active enzyme, and at least two more proteins are known to be involved. A simpler system involving only the last step with one precursor and one activation as has been reported in the literature is consistent with the cascade picture, but the whole complex system must be considered when dealing with genetic and developmental regulation of pigmentation and sclerotization. Details are given for partial or complete purification of six of the proteins involved and evidence for their modes of interaction is presented.
Animals↗