Divergent nonlinear responses of the boreal forest field layer along an experimental gradient of deer densities.

The early responses of the field layer to changes in biotic and abiotic conditions are key determinants of the future composition and structure of forests where sustained heavy browsing pressure has depauperated the shrub understory. We investigated the relationships between white-tailed deer density and field layer plant community dynamics in boreal forests managed for wildlife and timber production. We hypothesized that the growth and reproduction of field layer plants are either: (H(1)) directly proportional to deer density, or (H(2)) related to deer density through nonlinear relationships or (H(3)) through nonlinear relationships with thresholds.

Suppression of valid inferences and knowledge structures: the curious effect of producing alternative antecedents on reasoning with causal conditionals.

These studies looked at the difficulty that reasoners have in accepting conditional ("If P then Q") major premises that are not necessarily true empirically, as a basis for deductive reasoning. Preliminary results have shown that when reasoners are asked to produce possible alternate antecedents to the major premise ("If A then Q"), they paradoxically tend to deny the modus ponens (MP) inference ("If P is true, then Q is true"). Three studies further explored these results.

Mechanisms of action of antimalarials in inflammation: induction of apoptosis in human endothelial cells.

Antimalarials are beneficial therapeutic agents in systemic lupus and rheumatoid arthritis. These autoimmune diseases have abnormally low apoptosis of inflammatory cells. Both disorders have an abnormal angiogenesis.

Equilibrium model in an in vitro poly(ADP-ribose) turnover system.

Poly(ADP-ribose) metabolism plays an important role in numerous DNA-related functions. This homopolymer is synthesized by poly(ADP-ribose) polymerase and is degraded mainly by the poly(ADP-ribose) glycohydrolase. The activities of these two enzymes in the nucleus are closely coordinated.

The US-1 element from the gene encoding rat poly(ADP-ribose) polymerase binds the transcription factor Sp1.

By comparing the upstream DNA sequence of the rat and human genes encoding poly(ADP-ribose) polymerase (PARP), we have defined a 16-bp conserved region and designated it as US-1 for 'upstream sequence 1'. This element is homologous to the recently described binding site for the transcription factor Sp1 in the promoter sequence of the mouse p12 gene which encodes a protease inhibitor. Analyses in gel mobility shift assays revealed that a nuclear protein, produced by all tissue-culture cells tested, specifically binds the US-1 element.