Covalent bonding of protein to polyamine in the cyst coat of the protozoan Colpoda steinii

Analysis of fruiting body development in the aggregative ciliate Sorogena stoianovitchae (Ciliophora, Colpodea)

The fruiting body-forming ciliate Sorogena stoianovitchae is a protist that is multicellular in one stage of its life cycle. When nutrient levels are depleted, a number of Sorogena cells aggregate beneath the water surface to form an aerial fruiting body. Based on morphologies and the inhibition of protein synthesis, fruiting body development is divided into five distinct stages: (1) aggregation before sunrise, (2) compact aggregation after sunrise, (3) secretion of mucous matrix, (4) stalk-elongation, and (5) completion of the fruiting-body. In the aggregation stage, the cells were trapped in a matrix material that stained orange with 4',6-diamino-2-phenylindole (DAPI), but differed from the mucous matrix in the later stage. A short interruption of the dark period, at 6-8 h after the onset of dark, inhibited fruiting body development. Irrespective of the length of the dark period (10-16 h), the cells remained in the aggregation stage until the beginning of the light period. Therefore, an uninterrupted dark period of more than 8 h is critical for the initial aggregation of cells, but subsequent development is triggered by light.

Transglutaminases

This paper is intended as a background to the topic of transglutaminases, while focusing on current ideas regarding the biological roles of these enzymes. Specifically, the following topics are discussed: geometry of forming gamma-glutamyl-epsilon-lysine cross-linked structures; energetic considerations; the gamma-glutamyl-epsilon-lysine cross-link; amine incorporation assays; artefactual incorporation of amines in cells and tissue homogenates; synthetic substrate systems; regulation of transglutaminase activities; strategies for probing transglutaminase-mediated events in biological systems; the blood clotting paradigm; transglutaminase and cell aging: the Ca2+-enriched human erythrocyte; transglutaminase and cell activation: the thrombin-stimulated human platelet and the fertilized sea urchin egg.