Purification of human leucocyte DNA: proteinase K is not necessary.

A rapid nontoxic method for the purification of DNA from human leucocytes is described. Preliminary experiments which tested different methods of DNA purification indicated that digestion of proteins with proteinase K was unnecessary. This led to the development of a simple procedure involving lysis of the cells in SDS followed by extraction with 6 M NaCl. The method described overcomes the requirement for lengthy incubations in the presence of expensive proteinase K and subsequent extraction with toxic chemicals.     

Avoidance response of Midge Larvae (Chironomus Tentans) to sediments containing heavy metals

Avoidance reactions of chironomid larvae to contaminated sediment taken from a heavy metal impacted lake were studied. Heavy metal levels in the test sediment ranged from background of 0.6 parts per million (ppm) cadmium, 77 ppm zinc and 17 ppm chromium to a maximum of 1,029 ppm cadmium, 17,262 ppm zinc and 2,106 ppm chromium. A linear relationship was established between cadmium and zinc levels in the sediment and avoidance by chironomids.An approximate threshold avoidance of metals in the sediment was determined to be between 213–422 ppm cadmium, 4385–8330 ppm zinc and 799–1513 ppm chromium.Supported by NIH Training Grant Number 5T01-ES00071 from National Institute of Environmental Health Sciences and in part by an NSF (RANN) Grant Number GI-35106.Purdue University Agricultural Experiment Station, Jour. No. 6474.     

Behavioral changes in bluegill (Lepomis macrochirus) as indicators of sublethal effects of metals

Synopsis The development of rapid, yet sensitive toxicity testing methods is needed for the establishment of water quality standards to protect aquatic life. A technique using changes in the behavior of bluegill (Lepomis macrochirus) was utilized to evaluate the impact of five sublethal levels of a cadmium (Cd) and zinc (Zn) mixture. The technique proved very sensitive and various changes in behavior occurred at the lowest metal levels used; 21 ug Cd per liter and 99 ug Zn per liter. Coughs, yawns, partial jerks and jerk swimming were especially sensitive indicators of elevated metal levels. The frequency, but not the form, of eight of the nine behaviors quantified changed significantly with increasing metal levels.