Effects of chemical smokes on flora and fauna under field and laboratory exposures.

Various types of obscurant smokes are used routinely in training by the U.S. Army. Because continued routine use of the smokes could be detrimental to the native flora and fauna at training sites, a preliminary biological and chemical field study of fogoil, hexachloroethane, and tank diesel smokes was conducted. Smoke plumes were sampled and chemically analyzed at distances of 15-150 m from the smoke source where Tradescantia clones 4430 and 03 and the native plant Ambrosia dumosa and the native rodent Dipodomys merriami were exposed for 30 min. In addition, Tradescantia clone 4430 was exposed to tank diesel in the laboratory at concentration levels equivalent to exposure at 15 and 50 m. Tradescantia clones were examined for mutagenic effects indicated by micronuclei induction in developing pollen and pink somatic mutations in stamen hairs. Photosynthetic perturbations were measured in Tradescantia and A. dumosa using variable fluorescence induction. Animals were examined for sister chromatid exchanges and chromosome aberrations. It was found that all of the smokes tested exerted varying degrees of physiological and mutagenic effects in one or more assay system at one or more exposure distance. The studies reported here indicate that exposed ecological systems, or at least components of these systems, are at a higher risk than are unexposed components (e.g., organisms) for several types of damage attributed to obscurant smoke exposure.

Mutagenicity in the vicinity of a lead smelter.

The mutagenicity of the environment in the vicinity of a lead smelter was examined for 3 years by studies of changes in the frequencies of male germinal mutations of the waxy-C system of Zea mays and somatic mutations of the stamen hair system of Tradescantia. A transect was run at 0.3, 1.7, 3.2, 7.4, and 11.4 km predominantly downwind from the smelter. The mutagenic responses vary between years, within a year, and with distance. Mutation frequencies are both directional and nondirectional with distance. Concentrations of Pb, Cd, Cu, and Zn measured in soil samples show directional changes with distance each of the 3 years, and joint monotonicity is observed in some cases between mutation frequency with distance and metal concentrations with distance. Of a total of ten experiments with both Zea mays and Tradescantia, eight show significantly higher mutation frequencies at one or more locations close to the smelter than at locations more distant or at other controls.

Multiple meiotic drive systems in the Drosophila melanogaster male.

The behaviour of two "meiotic drive" systems, Segregation-Distorter (SD) and the sex chromosome sc(4)sc(8) has been examined in the same meiocyte. It has been found that the two systems interact in a specific way. When the distorting effects of SD and sc(4)sc(8) are against each other, there is no detectable interaction. Each system is apparently oblivious to the presence of the other, gametes being produced according to independence expectations. However when the affected chromosomes are at the same meiotic pole an interaction occurs; the survival probability of the gamete containing both distorted chromosomal products is increased, rather than being decreased by the combined action of two systems.