Aminoacid composition and hydrophobicity index of mitochondrial polypeptides

The aminoacid composition of protein stained bands in polyacrylamide gels, after electrophoresis of proteins from inner mitochondrial membranes, was investigated hydrolyzing directly the gel slices. The Hydrophobicity Index of 18 prominent polypeptide bands was calculated after their aminoacid analysis. The polypeptides less related to the membrane have low hydrophobicity as inferred from their Hydrophobicity Indexes.     

Modified oscillation behavior and decreased D-3-hydroxybutyrate dehydrogenase activity in diabetic rat liver mitochondria

One month after induction of diabetes in adult white rats with streptozotocin or 4–10 months after its induction by pancreatectomy (in every case glycemia was over 3 g/liter), the following alterations were observed in liver mitochondria: (a) a decrease of amplitude and an increase of the damping factor of volume oscillations induced by potassium ions and valinomycin; (b) a 50% decrease of d-3-hydroxybutyrate dehydrogenase (HBD) activity in mitochondria disrupted by repeated freeze-thawing; (c) a similar decrease in the rate of d-3-hydroxybutyrate oxidation by intact mitochondria; (d) a significant increase of cytochrome oxidase activity and cytochrome aa₃ content. Measurement of succinate dehydrogenase and NADH dehydrogenase activity, the cytochrome b, c₁, and c content, and the P:O ratio for mitochondria oxidizing d-3-hydroxybutyrate did not reveal significant differences between control and diabetic rat mitochondria. In the streptozotocin-injected rats, the variation of HBD activity and the modification of the mitochondrial oscillation pattern were time-dependent phenomena, both effects reaching their maximal expression about 1 month after the onset of diabetes. The variation of HBD activity followed a biphasic course, since it rose to above the control level during the first 2 weeks of diabetes, then fell progressively to about half the control value after the third week. Treatment of diabetic rats with NPH insulin (5 IU twice daily, for 3 days, reinforced by the same dose 45 min before sacrifice) restored the mitochondrial oscillation pattern, HBD activity, and rate of d-3-hydroxybutyrate oxidation by intact mitochondria to their normal values.     

Partial intercalation with DNA of peptides containing two aromatic amino acids

The interactions with DNA of tetrapeptide amides containing lysine at the N-terminal position and aromatic amino acids at the second and fourth positions (Ala at position three), 1-6, have been investigated by nmr, CD, and viscometric methods. Tetrapeptides with N-terminal lysine and a single aromatic amino acid, 7-10, were investigated as controls. Significant decreases in DNA viscosity occurred on addition of 7, with the aromatic group at the second position, but not with any of the other single aromatic amino acid peptides. All of the tetrapeptides with two aromatic groups caused DNA viscosity decreases which were two to three times larger than with 7. Peptides with p-nitrophenylalanine (p-NO2Phe) as the aromatic group were synthesized for nmr studies because of its simpler aromatic nmr spectrum relative to Phe. Large upfield shifts of the aromatic proton signals were obtained when the amino acid in the second position was L-p-NO2Phe, and the fourth position contained either p-NO2Phe or Phe. Such peptides also caused the largest DNA viscosity decreases on complex formation. Smaller upfield shifts of the aromatic signals were obtained when the amino acid in the second position was L-Phe or a D isomer of Phe or p-NO2Phe. With all peptides, larger upfield nmr shifts were obtained with heat-denatured, recooled DNA than with native DNA under the same conditions. As with nmr, CD results are quite different for the peptides with L and D amino acids at the second position. All of the results can be interpreted in terms of a model in which lysine interacts stereospecifically with the backbone in a DNA double helix and the aromatic group at the second position stacks strongly with the base pairs when the amino acid is an L isomer. The aromatic group at the fourth position can also interact with the base pairs, but primarily through a sideways stacking of the aromatic group with base pairs for either L or D isomers. Because of covalent constraints on the separation distance for the two aromatic groups in the tetrapeptides, they must stack on opposite sides of the same base pair in violation of the neighbor exclusion principle observed with classical intercalators. This stacking at the same base pair no doubt accounts for the larger viscosity decreases in DNA with the peptides containing two aromatic groups relative to those with a single aromatic group.(ABSTRACT TRUNCATED AT 400 WORDS)     

Kiwifruit micropropagation through callus shoot-bud induction

Summary A profitable system for the establishment of morphogenic callus cultures and indirect shoot induction and development was accomplished from nodal shoot segments obtained from adult and micropropagated plants of kiwifruit (Actinidia deliciosa [Chev.] Liang and Ferguson, var.deliciosa) cv. “Hayward”. The effects of medium composition, cytokinin levels, dilution of salts, and type of callus derived from the cultured primary explants were studied. Medium composition as well as type of callus greatly affected organogenic responses.     

Vanadate,alcohol or both increase passive membrane permeability of neuro-2a cells; Lesser sensitivity of Hep-2 cells

Neuro-2a cells incubated for 1 hour with 0.1 mM vanadate showed an increase in cell membrane permeability. This effect is dose dependent, e.g. with 0.01 mM, 0.1 mM and 1 mM vanadate, there was {20, 30 and 40% increase. In contrast, no alteration in permeability was observed in HEp-2 cells under the same conditions.Ethanol (3%, 1 h incubation) also enhanced membrane permeability. The increase was also greater with Neuro-2a cells ({80%) than with HEp-2 cells (～30%). When the cells were incubated with ethanol plus vanadate (0.1 mM), there was a marked potentiation ({200%) in cell membrane permeability in Neuro-2a cells, and again a lesser increase in permeability ({50%) with HEp-2 cells.These results seem to be due to a preferential effect of vanadate on passive permeability of Neuro-2a cells because parallel measurements demonstrate equal inhibition of (Na⁺K) ATPase with both Neuro-2a and HEp-2 cells.     

Boron,copper, iron,manganese and zinc contents in leaves of flowering sunflower plants (Helianthus annuus,L.), grown with different boron supplies

Summary Boron, copper, iron, manganese and zinc concentrations were measured in sunflower leaves from plants grown hydroponically in a closed continuous flow system and with boron concentrations ranging from deficient to toxic. Leaves were analyzed at the stage of flower development. There was a highly significant inverse correlation between B concentration in solution and Mn concentration in leaves. Cu, Fe and Zn concentrations in the leaves were not changed by the different B levels, although the B concentration in leaves increased with an increasing concentration in solution, showing a close correlation each other.     

Isolation of a mitochondrial factor from rat liver which potentiates the inactivation of glutamate dehydrogenase by lysosomes

Rat liver glutamate dehydrogenase (L-glutamate: NAD(P) oxidoreductase, deaminating) E.C. 1.4.1.3.) is inactivated by the mitochondrial matrix in combination with lysosomal preparations. Neither lysosomal or mitochondrial matrix extracts per se inactivate the enzyme appreciably under the conditions used. Fractionation of the matrix indicates that a low molecular weight factor is responsible for the potentiation of inactivation of glutamate dehydrogenase by lysosomes. Its absorption spectrum and chromatographic behaviour suggest that this factor is NADP.     

Activated T lymphocytes within human solid tumors

Summary The majority of lymphocytes separated from tumor cell suspensions were T cells. Conjugates of T lymphocytes and tumor cells were often seen. Variable numbers of T cells exhibited signs of activation such as the ability to form stable E rosettes and attachment to normal and malignant cells (a phenomenon designated natural attachment: NA). A proportion of T cells activated in vitro by allogeneic stimulation regularly exhibit these properties. The T cell-tumor conjugates in the suspensions may represent the NA phenomenon, but they could also be the product of T cells that adhere on the basis of specific recognition of cell surface antigens.Abbreviations BBS balanced salt solution - E rosettes rosettes formed with sheep erythrocytes - EA rosettes rosettes formed with ox erythrocytes coated with anti-ox IgG - FCS fetal calf serum - MLC mixed lymphocyte cultures - NA natural attachment - PBL peripheral blood lymphocytes - SRBC sheep erythrocytes - T lymphocytes thymusderived lymphocytes