Dominant lethal studies in male mice after exposure to 2.45 GHz microwave radiation

Adult male mice had the lower halves of their bodies exposed in a waveguide system to 2.45 GHz microwave radiation for 30 min. The half body dose-rate of 43 W kg-1 had been shown in a previous study [7] to deplete severely the heat-sensitive stages of sperm production. The males were mated at intervals to adult hybrid females over the following 8-10 weeks. There was no significant reduction in post-implantation survival, suggesting that the microwave exposure did not have a mutagenic effect on the male germ cells. However, pregnancy rate was significantly reduced in weeks 3, 4, 5 and 6; reaching a minimum of about 10% of the control value in weeks 4 and 5. The occurrence of low values in weeks 4 and 5 correlated well with the expected reductions in sperm count due to the pattern of depletion of the spermatogenic epithelium of the testes. Thus it was concluded that the reduced pregnancy rate resulted from reduced male fertility. Pre-implantation survival can also be affected by reduced sperm count [8] and was significantly reduced in this study but it correlated less well with the anticipated heat response. A further study is in progress looking at the contribution of sperm count and sperm abnormality to the results.     

Exclusion of linkage of loci on chromosome 19 with multiple endocrine neoplasia, type 2

Linkage between seven loci on chromosome 19 and multiple endocrine neoplasia type 2a (MEN2A) was examined in a single large Swedish pedigree. A total of 50 cM was excluded from the male genetic map by pairwise analysis and an estimated 63 cM by multipoint analysis. Using existing data on the likelihood of different marker-marker distances and taking into account current exclusions on other chromosomes, the probability that the gene for MEN2A segregating in this pedigree could still be located on chromosome 19 is approximately 0.28%.     

Effect of inhalation of insecticide spray on learning and memory in rats

Acute exposure to insecticide (Baygon-spray; 5 ml/animal/5 min) inhalation in rats did not affect the learning process but produced a significant loss of memory (P less than 0.01 less than 0.001) whereas chronic exposure (one exposure per day for three weeks) produced a significant delay in learning (P less than 0.05) and memory (P less than 0.01). Acetylcholinesterase activity in brain after acute and chronic exposure declined significantly (P less than 0.01) during the learning process but returned to normal after 24 hr.