Mechanisms of action and medicinal applications of abscisic Acid.

Since its discovery in the early 1960's, abscisic acid (ABA) has received considerable attention as an important phytohormone, and more recently, as a candidate medicinal in humans. In plants it has been shown to regulate important physiological processes such as response to drought stress, and dormancy. The discovery of ABA synthesis in animal cells has generated interest in the possible parallels between its role in plant and animal systems. The importance of this molecule has prompted the development of several methods for the chemical synthesis of ABA, which differ significantly from the biosynthesis of ABA in plants through the mevalonic acid pathway. ABA recognition in plants has been shown to occur at both the intra- and extracellularly but little is known about the perception of ABA by animal cells. A few ABA molecular targets have been identified in vitro (e.g., calcium signaling, G protein-coupled receptors) in both plant and animal systems. A unique finding in mammalian systems, however, is that the peroxisome proliferator-activated receptor, PPAR gamma, is upregulated by ABA in both in vitro and in vivo studies. Comparison of the human PPAR gamma gene network with Arabidopsis ABA-related genes reveal important orthologs between these groups. Also, ABA can ameliorate the symptoms of type II diabetes, targeting PPAR gamma in a similar manner as the thiazolidinediones class of anti-diabetic drugs. The use of ABA in the treatment of type II diabetes, offers encouragement for further studies concerning the biomedical applications of ABA.

Biological and immunological properties of crystalline proteins from B. thuringiensis var. galleriae and var. insectus.

The antigenic and toxic properties of the crystalline proteins from two varieties of B. thuringiensis (var. galleriae and var. insectus) were studied. Methods of double diffusion in agar and two-dimensional disc immunoelectrophoresis revealed four antigens in the crystalline protein from var. galleriae and three in that from var. insectus. A definite correlation was found between the toxicity of the crystalline protein and its capacity to interact with antiserum in a precipitation reaction in agar. It was established that the total protein content cannot be used as the criterion for an evaluation of the activity of preparations from B. thuringiensis. Immunodiffusion methods are recommended for an evaluation of the quality of these preparations.