Genetic variation was examined in bluehead wrasse, Thalassoma bifasciatum, populations along the Florida Keys. Interpretion of mean heterozygosity (H), percent polymorphic loci per population (P), genetic similarity, and F and G statistics demonstrated a clear division of wrasse populations into "northern" and "southern" groups. Correlation and cluster analyses indicated the six reefs can be grouped in a similar fashion based on genetic and environmental data. The conclusion from this analysis of wrasse populations in the Florida Keys is that substantial population subdivision occurs in response to differing selective pressures created by heterogeneous environments.

The effects of external electric fields (EEF) on brain activity in anesthetized rats were studied. The field strengths used, 9 kV/m and 5 kV/m, both D.C. and A.C. (60Hz) were in the range of those measured beneath current overhead transmission lines. Brain activity was monitored from surface electrodes and from electrodes stereotaxically implanted in the posterior-lateral portion of the hypothalamus. It was found that 9 kV/m and 5 kV/m EEF's both D.C. and A.C. brought about statistically significant changes in hypothalamic activity, however, the effects were bi-directional, (i.e. increases and decreases). Only seven of the 60 animals exposed showed changes in the EEG recorded with surface electrodes. The data clearly indicate that (1) anesthetized animals do respond to a change in the external electric field around them, (2) the hypothalamus may contain special electro-receptors that, in turn, may alter various other physiological processes, and (3) the data indicates the need for further research to help government agencies to establish more adequate safety guidelines.

The phospholipase B activity was assayed in the small intestines, spleen and liver/bile duct of nonsensitized and sensitized mice infected with Fasciola hepatica. The primary infection resulted in a significant increase in phospholipase B activity in the small intestine, spleen and liver/bile duct over that of uninfected control animals. The response to the challenge infection was characterized by an earlier increase in enzyme activity with values significantly above those found for the primary infection in the same tissues. These data demonstrate that one response of mice to infection with F. hepatica is characterized by an increased phospholipase B activity. Thus, the enzyme response is not unique to cestode and nematode infections, but also is part of or associated with the inflammatory mechanisms against trematode infections. In addition, phospholipase B was demonstrated in leukocytes using electron microscopic histochemical techniques. Leukocytes were harvested from peritoneal exudates of mice. Cells were fixed in 4% calcium-forol fixative for 30 minutes at roan temperature for electron microscopy, after which they were incubated at 370C in medium at pH 6.6 containing 2 aM lysolecithin and Cal2 . The fatty acids released during the hydrolytic reaction were trapped as a calcium precipitate and were converted to a …