Exposure of Drosophila melanogaster embryonic cell cultures to 60-Hz sinusoidal magnetic fields: assessment of potential teratogenic effects.

There is considerable concern about potential detrimental health effects associated with exposure to environmentally relevant magnetic fields. One specific concern relates to potential effects of magnetic field (MF) exposure on reproduction and development. Consequently, an in vitro teratogenesis (developmental toxicity) assay employing embryonic Drosophila cells has been used to determine whether exposure to a 60-Hz MF of 100 microT for 16-18 hr is itself teratogenic and whether such an exposure could potentiate the teratogenic response induced by a chemical teratogen (developmental toxicant).

Differential expression of heat shock proteins in Drosophila embryonic cells following metal ion exposure.

Drosophila embryonic cells were exposed to a number of metal ions that have been previously reported to act as teratogens in mammalian systems, including some known to induce heat shock (stress) proteins in a variety of model systems. This study examined the effects of these ions both on differentiation of muscles and neurons and on the induction of heat shock proteins. Metals such as arsenate, cadmium, and mercury all inhibited neuron and/or muscle differentiation in Drosophila embryonic cultures, while they also induced the entire set of heat shock proteins.

In vitro neuronal differentiation of Drosophila embryo cells.

Early gastrula-stage Drosophila embryo cells will differentiate in vitro to form several cell types, including neurons. We report here the morphological appearance of cultured embryo cells, the pattern of DNA synthesis, and the expression of neurotransmitter-metabolizing macromolecules. The cells initially exhibit no overt morphological differentiation, and all cells incorporate 3H-thymidine following a 1 hr pulse-labeling period.

Response of Drosophila embryonic cells to tumor promoters.

Several recent observations on tumor promoters point to the many developmental and embryonic characteristics associated with their mode of action. These observations have led us to investigate the effects of a series of tumor promoters on Drosophila embryonic cultures at both the morphological and molecular levels. The cultures have been used with some success by us to assess the teratogenic potential of a large number of molecules, including drugs, chemicals, and environmental pollutants.

Developmental effects of chemicals and the heat shock response in Drosophila cells.

Exposure of prokaryotic and eukaryotic cells to heat shock (hyperthermia) or to a number of diverse environmental stresses such as teratogens, anoxia, and inhibitors of oxidative phosphorylation results in the enhanced synthesis of a number of proteins which have been previously referred to as heat shock proteins (hsps). More recently, in view of the diverse types of agents that can induce these proteins, they have also been referred to as stress proteins. This phenomenon is one of the most basic regulatory mechanisms in living organisms.

Teratogens induce a subset of small heat shock proteins in Drosophila primary embryonic cell cultures.

Drosophila embryonic cells placed into culture just after gastrulation differentiate in vitro over the next 24 hr. A number of drugs that are teratogenic in mammalian systems have been found to inhibit muscle or neuron differentiation (or both) in these developing cultures. We have examined, by two-dimensional gel electrophoresis, the effects of these drugs on protein synthesis in embryonic cells.

The effect of 5-azacytidine and cytidine analogs onDrosophila melanogaster cells in culture.

The effects of cytidine and cytidine analogs were studied inDrosophila embryonic cell cultures and two wild-type established cell lines, Oregon-R and Schneider line 2. Primary embryonic cultures have been shown to be an excellent system for the study of embryonic development; a number of cell types undergo normal differentiation in vitro. Treatment of these cultures with putative teratogens resulted in an inhibition of muscle and/or neuron differentiation in our study.

Detection of teratogens in the Drosophila embryonic cell culture test: assay of 100 chemicals.

An in vitro assay of teratogenesis has been developed that utilizes Drosophila embryonic cell cultures. The endpoint selected in assessing the teratogenic potential of any substance involves detection of interference with normal muscle and/or neuron differentiation. In the validation phase of this project, 100 chemicals were tested.

Drug metabolizing enzymes in Drosophila melanogaster: teratogenicity of cyclophosphamide in vitro.

This report concerns the attempt to demonstrate the practicability of using microsomal fractions (rat or Drosophila) for activating proteratogens in a Drosophila in vitro teratogen screening assay. Accordingly, a typical proteratogen (cyclophosphamide) was tested before and after microsomal activation and results compared with the drug directly on the in vitro assay. The effects of microsomal activation on known teratogens (thalidomide) and nonteratogens (acetaminophen) were also assayed in order to determine the specificity of the activation process.

Use of Drosophila embryo cell cultures as an in vitro teratogen assay.

An in vitro assay has been developed for detecting teratogens by adding them to primary cultures of embryonic Drosophila cells and analyzing the degree of change in cell differentiation and tissue formation. Cultures are scored by an automated image analysis system that counts the number of myotubes and ganglia in culture. A decrease in their number compared to controls is taken as an indication of teratogenicity.

Characterisation of a new tumorous-head mutant of Drosophila melanogaster.

A new homoeotic mutant, I127, showing abnormal growths in the head region including homoeotic transformation of eye to genitalia and antenna to leg, was isolated in a screen designed to find new alleles of the tumourous head (tuh-3), mutation. Similarities in the phenotype and genetics of the mutant, and complementation studies with tuh-I; tuh-3, suggest that I127 is indeed an allele of tuh-3. In combination with the first chromosome modifier tuh-1, the mutant is temperature-sensitive during the third larval instar, giving an increased penetrance of the tumorous head phenotype when reared at 25 degrees C as opposed to 18 degrees C.

Temperature sensitivity ofTumorous head, a homoeotic mutant ofDrosophila melanogaster.

A temperature-sensitive period during early embryogenesis for three stocks carrying thetuh-3 gene suggests that it is a homoeotic mutation involved in the initial determination of the eye-antennal disc rather in maintenance of the determination.

Developmental analysis of the tumorous head mutation in Drosophila melanogaster.

The extent and type of adult transformations in the tumorous head (tuh) mutation of Drosophila melanogaster were studied. The observations indicate homeotic transformations, duplications and deficiencies of eye antennal disc derivatives. Contrary to previous observations there is no transformation of eye to abdomen and the only homeotic transformations identifiable are antenna to leg and rostralhaut to genitalia.