Morphometric ultrastructural study of the adreno- and noradrenocytes of the rat adrenal during immobilization stress of varying duration

The ultrastructural organization of secretory granules, containing adrenaline (A) or noradrenaline (NA) was studied in chromaffin cells of the rat adrenal gland after 3-, 24- and 48-hour immobilization stress. Using cytochemical electron microscopic Tranzer's method and the method of morphometry, the number of normal dense cores, "empty" and "semiempty" vesicles was calculated. It was shown that the total content of vesicles and the ratio of investigated types of both adrenaline- and noradrenaline-accumulating granules were markedly changed during stress. The degree of such stress-induced reorganization depended on the stage of stress reaction and involved first A-cells and then NA-cells.     

Conditions of the biosynthesis of an extracellular subtilisin-like proteinase by <Emphasis Type="Italic">Bacillus pumilus</Emphasis> KMM 62

The influence of the cultivation conditions on Bacillus pumilus KMM 62 growth and effectiveness of the production of a subtilisin-like serine proteinase were investigated. Enzyme accumulation in the culture fluid reached the maximum value after 32 and 46–48 h of growth; it depends on the composition of the nutrient medium. The ratio of the concentrations of two main components of the medium, peptone and inorganic phosphate, which was optimal for enzyme biosynthesis was determined by multifactor experiments. Ammonium salts, when introduced as an additional nitrogen source, had different effects on the proteinase biosynthesis at different growth stages: they suppress enzyme production at the early stationary growth phase and stimulate the biosynthesis of the enzyme after 46–48 h of growth. Complex organic substrates (albumin, casein, hemoglobin, and gelatin) have a repressive effect on the biosynthesis of the enzyme. The effect of amino acids on culture growth and enzyme biosynthesis during the early and late stationary growth phase is different. Hydrophilic amino acids, glutamine, and glutamic acid exhibit the most pronounced repressive action on biosynthesis. The involvement of different regulatory mechanisms of the synthesis of this proteinase is assumed in the early and late stationary phases of growth.     

Phosphorylation of the Protein Encoded by the First Open Reading Frame of the MDG4 Transposable Element (gypsy) by Homologous and Heterologous Casein Kinases Type 2

Homogeneous casein kinase type 2 (CK2) was obtained from oocytes of Rana temporaria and cells of Drosophila melanogaster by chromatography on heparin-Sepharose, phosphocellulose, and Mono Q columns using a Pharmacia FPLC system. The procedure was first successfully used for the purification of CK2 from the Drosophila melanogaster cell culture. It has been shown that the protein encoded by the first open reading frame (ORF) of the gypsy transposable element (MDG4) is an effective protein substrate both for homologous and heterologous CK2 from the oocytes of Rana temporaria in vitro. Both enzymes catalyze the incorporation of two moles of phosphate per mole of protein. The K_m and V_max values for the reaction catalyzed by CK2 from the Drosophila cell culture were 32.5 ± 2.1 nM and 70.97 ± 1.89 nmol/min per µg, respectively, and for CK2 from oocytes, these values were 37.6 ± 2.8 nM and 66.02 ± 2.15 nmol/min per µg, respectively.     

Apoptosis regulates notochord development in Xenopus

The notochord is the defining characteristic of the chordate embryo and plays critical roles as a signaling center and as the primitive skeleton. In this study we show that early notochord development in Xenopus embryos is regulated by apoptosis. We find apoptotic cells in the notochord beginning at the neural groove stage and increasing in number as the embryo develops. These dying cells are distributed in an anterior to posterior pattern that is correlated with notochord extension through vacuolization. In axial mesoderm explants, inhibition of this apoptosis causes the length of the notochord to approximately double compared to controls. In embryos, however, inhibition of apoptosis decreases the length of the notochord and it is severely kinked. This kinking also spreads from the anterior with developmental stage such that, by the tadpole stage, the notochord lacks any recognizable structure, although notochord markers are expressed in a normal temporal pattern. Extension of the somites and neural plate mirrors that of the notochord in these embryos, and the somites are severely disorganized. These data indicate that apoptosis is required for normal notochord development during the formation of the anterior-posterior axis, and its role in this process is discussed.