Voluntary lithium intake, antidotal thirst' and concurrent behavior of rats.

1 Voluntary intake of various pair combinations of fluids (100 mM, 10 mM LiC1, 10 mM NaC1, water) and body weight was measured daily in rats. 2 More lithium was consumed when water was available. 3 When offered a lithium-sodium choice the rats did not consume significantly more saline than water on the previous trial. While saline consumption increased over the two days, lithium decreased slightly. 4 Following the lithium-only trial, water and saline were provided. Marked polydipsia was observed on the first day and the rats drank more water than saline. On the second day there was a significant drop in saline intake while water consumption returned to baseline levels. 5 Behavioural measurements overall confirmed the depressant effect of lithium: decreased ambulation and rearing and increased time spent immobile/grooming. 6 These findings are discussed with reference to lithium toxicity, which may be a comfounding variable in studies concerned with the effects of this salt on the behavior of laboratory rodents. Behavioural irritability such as aggression reported in situations using long-term lithium treatment may be reduced by provision for voluntary saline consumption.

Mutator transposase is widespread in the grasses.

Although the Mutator (Mu) system is well characterized in maize (Zea mays), very little is known about this highly mutagenic system of transposons in other grasses. Mutator is regulated by the MuDR class of elements, which encodes two genes, one of which, mudrA, has similarity to a number of bacterial transposases. Experiments in our laboratory, as well as database searches, demonstrate that mudrA sequences are ubiquitous and diverse in the grasses. In several species it is clear that multiple paralogous elements can be present in a single genome. In some species such as wheat (Triticum aestivum) and rice (Oryza sativa), mudrA-similar sequences are represented in cDNA databases, suggesting the presence of active Mu transposon systems in these species. Further, in rice and in sorghum, mudrA-like genes are flanked by long terminal inverted repeats, as well as the short host sequence direct repeats diagnostic of insertion. Thus, there is ample evidence that systems related to Mu in maize are at least potentially active in a wide variety of grasses. However, the mudrB gene, though important for Mu activity in maize, is not necessarily a component of Mu elements in other grasses.