Properties of the regulatory subunit of cAMP-dependent protein kinase type II from human brain

The regulatory subunit type II (RII) of cAMP-dependent protein kinase purified from human brain was represented by two proteins with apparent molecular masses of 51-52 kD and 54 kD. Dephosphorylation of human RII containing 3 mol phosphate/mol protein did not change the electrophoretic pattern. One-dimensional peptide mapping of 51-52 kD and 54 kD proteins after digestion with St. aureus V8 protease evidenced to their being distinct proteins. The data obtained permit to assume that human RII of neural type is represented by two isoforms.     

Kinetochores distinguish GTP from GDP forms of the microtubule lattice

During prometaphase in mitotic cell division, chromosomes attach to the walls of microtubules and subsequently move to microtubule ends, where they stay throughout mitosis. This end-attachment seems to be essential for correct chromosome segregating. However, the mechanism by which kinetochores, the multiprotein complexes that link chromosomes to the microtubules of the mitotic spindle, recognize and stay attached to microtubule ends is not understood. One clue comes from the hydrolysis of GTP that occurs during microtubule polymerization. Although tubulin dimers must contain GTP to polymerize, this GTP is rapidly hydrolysed following the addition of dimers to a growing polymer. This creates a microtubule consisting largely of GDP-tubulin, with a small cap of GTP-tubulin at the end. It is possible that kinetochores distinguish the different structural states of a GTP- versus a GDP-microtubule lattice. We have examined this question in vitro using reconstituted kinetochores from the yeast Saccharomyces cerevisiae. We found that kinetochores in vitro bind preferentially to GTP- rather than GDP-microtubules, and to the plus-end preferentially over the lattice. Our results could explain how kinetochores stay at microtubule ends and thus segregate chromosomes correctly during mitosis in vivo. This result demonstrates that proteins exist that can distinguish the GTP conformation of the microtubule lattice.     

Fertilizer determination for yield and quality improvement of vegetable crops by mathematical optimization techniques

Techniques of Operations Research were introduced into the modelling work for determining optimal NPK-fertilizer requirements for vegetable crops which lead not only to a maximal yield but also to a special crop quality. In the model applied, 26 plant parameters were adopted to described yield and quality responses of Chinese cabbage to different NPK-nutrition. An integrative and comprehensive analysis about relationships between plant growth and nutrient supply can be carried out by using this model. Examples of model calculation for practical use, the validity of the model and a comparison of methods for fertilizer determination were demonstrated and discussed.     

Movement of axoplasmic organelles on actin filaments from skeletal muscle

It was recently shown that, in addition to the well-established microtubule-dependent mechanism, fast transport of organelles in squid giant axons also occurs in the presence of actin filaments [Kuznetsov et al., 1992, Nature 356:722-725]. The objectives of this study were to obtain direct evidence of axoplasmic organelle movement on actin filaments and to demonstrate that these organelles are able to move on skeletal muscle actin filaments. Organelles and actin filaments were visualized by video-enhanced contrast differential interference contrast (AVEC-DIC) microscopy and by video intensified fluorescence microscopy. Actin filaments, prepared by polymerization of monomeric actin purified from rabbit skeletal muscle, were stabilized with rhodamine-phalloidin and adsorbed to cover slips. When axoplasm was extruded on these cover slips in the buffer containing cytochalasin B that prevents the formation of endogenous axonal actin filaments, organelles were observed to move at the fast transport rate. Also, axoplasmic organelles were observed to move on bundles of actin filaments that were of sufficient thickness to be detected directly by AVEC-DIC microscopy. The range of average velocities of movement on the muscle actin filaments was not statistically different from that on axonal filaments. The level of motile activity (number of organelles moving/min/field) on the exogenous filaments was less than on endogenous filaments probably due to the entanglement of filaments on the cover slip surface. We also found that calmodulin (CaM) increased the level of motile activity of organelles on actin filaments. In addition, CaM stimulated the movement of elongated membranous organelles that appeared to be tubular elements of smooth endoplasmic reticulum or extensions of prelysosomes. These studies provide the first direct evidence that organelles from higher animal cells such as neurons move on biochemically defined actin filaments.     

Maillard reactions of dextrins and starch

When dextrins or starch are heated with propyl-amine in neutral aqueous solution at 100–130° C a brown colouration is observed. From the reaction mixture 3-hydroxy-2-methyl-1-propyl-4(1H)-pyridone11, 1,4-dihy-dro-2-methyl-1-propyl-4-propylimino-3-pyridinol12 and 5-hydroxymethyl-1-propyl-pyrrol-2-aldehyde13 can be extracted with organic solvents and separated by HPLC. Enzymatic hydrolysis effects the release of 1(3-hydroxy-1-propyl-2-pyrrolyl)-1-ethanone10 from a glycosidically bound precursor.

---

Maillard Reaktionen von Dextrinen und Stärke

Zusammenfassung Erhitzt man Dextrine oder Stärke mit Propylamin in neutraler wäßriger Lösung auf 100–130 °C, so beobachtet man eine braune Färbung. Aus der Reaktionsmischung lassen sich 3-Hydroxy-2-methyl-1-propyl-4(1H)-pyridon11, 1,4-Dihydro-2-methyl-1-pro-pyl-4-propylimino-3-pyridinol12 und 5-Hydroxymethyl-1-propyl-pyrrol-2-aldehyd13 mit organischen Lösungsmitteln extrahieren und durch HPLC trennen. Nach enzymatischer Hydrolyse der wasserlöslichen Fraktion ist 1(3-Hydroxy-1-propyl-2-pyrrolyl)-1-ethanon10 isolierbar.

     

Untersuchungen zur Maillard-Reaktion XX. Nachweis von Glycerinaldehyd, Dihydroxyaceton und anderen hydrophilen Zuckerabbauprodukten in Caramellisierungsgemischen

Zusammenfassung Zuckerabbauprodukte lassen sich durch Umsetzung mit O-Methylhydroxylamin und anschließende Acetylierung zu gaschromatographisch gut trennbaren Verbindungen umsetzen. In Zucker-caramellisierungsgemischen konnten so Glycerinaldehyd, Dihydroxyaceton, Erythrose, 3-Deoxyhexosulose und Methylglyoxal nachgewiesen werden. Auch in der Kruste von Brezen entstehen Glycerinaldehyd und Dihydroxyaceton.

---

Investigations relating to the maillard reaction XX. Identification of glyceraldehyd dihydroxyacetone and other hydrophilic sugar degradation products in caramel mixtures

Summary Sugar degradation products can be determined by g.l.c. after reaction with O-Methylhydroxylamine and subsequent acetylation. Thus dihydroxyacetone, glyceraldehyde, erythrose, 3-deoxyhexosulose and methylglyoxale have been detected in caramelisation mixtures. Dihydroxy-acetone and glyceraldehyde could also be identified in the crust of a special bakery product.

---

---

XIX. Mitteilung: Ledl F, Hiebl J, Severin Th (1983) 177:353–355     

Vertical transfer of137Cs in peat soils fallen out as a consequence of the chernobyl accident

On the basis of measurements of the specific radioactivity of soil specimens sampled with a small step along their deposition, depth profiles are plotted for the curves of the vertical change in ¹³⁷ Cs in peat soils not treated since the Chernobyl accident. A theoretical analysis is provided for the plotted profiles that shows that the vertical transfer of ¹³⁷ Cs in these soils is described adequately within the framework of a model that accounts for the processes of diffusion and convection of the radionuclide in the soil solution and its sorption by the solid phase of the soil. The parameters of the model are determined and a prediction is given for the migration character of ¹³⁷ Cs.Institute of Solid State Physics, Academy of Sciences of Belarus, Minsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 68, No. 1, pp. 33–38, January–February, 1995.     

The influence of substrate chemistry on the adhesion of electrolessly deposited Ni(P) on metal oxide coated ceramics

The adhesion of electrolessly deposited Ni(P) on alumina ceramic substrates which were coated with thin SiO₂, SnO₂, TiO₂, Al₂O₃, Y₂O₃, ZrO₂ and (In,Sn)O_x (ITO) films was studied. The adhesion was measured with the aid of the 90° peel test. Strong adhesion of Ni(P) was found for the substrates with ZrO₂ and Al₂O₃ coatings and weak adhesion for the substrates with SiO₂, TiO₂, SnO₂, Y₂O₃ and ITO coatings. The fracture path and the type of interfacial bonding were analysed using scanning electron microscopy, energy-dispersive analysis of X-rays and X-ray photoelectron spectroscopy. In the case of the strongly adhering samples, fracture took place through the metal layer and along the interface. In the case of the weakly adhering samples only interfacial failure was observed between the Ni(P) layer and the metal oxide coating. Cross-section transmission electron microscopy studies of the interfaces suggested that the differences in peel energy values are caused by differences in micromechanical interlocking at the metal oxide-Ni(P) interface. In addition, a weak boundary layer which was found to be present at the Ni(P)-alumina interface was absent in the case of the strongly adhering samples with the ZrO₂ substrate coating.