Evolution of the electron Langmuir oscillations in an inhomogeneous magnetized plasma

The conditions under which the energy of the electron Langmuir oscillations can escape from the plasma into vacuum are determined in the simplest model of a plane slab of an inhomogeneous cold magnetized plasma in a uniform magnetic field.     

TTX displacement of [H3]-nitrendipine binding in developing spinal cord neurons

[3H] Nitrendipine binding was partially blocked by the presence of tetrodotoxin in developing spinal cord neurons. In young cultures, 1 micron tetrodotoxin displaced 29% and 26% of [3H] nitrendipine binding from the high and low affinity binding sites, respectively. In one month old cultures, tetrodotoxin had no effect on [3H] nitrendipine binding. The interaction between tetrodotoxin and nitrendipine in young cultures suggests ligand binding site similarities during development.     

Effect of testosterone on the rate of total protein synthesis in the reproductive tract of guinea pig embryos in vitro

The influence of testosterone on the rate of total protein synthesis in the reproductive tract tissues and muscles was studied in the guinea pig male embryos from 26 days of development until birth. The rate of protein synthesis was estimated by the intensity of 3H-leucine incorporation per 1 mg protein for 30 min. Testosterone increased the rate of protein synthesis at all studies stages. A higher rate of protein synthesis was revealed at the stages of active morphogenesis and growth of rudiments and organs of genital system and correlated with their ability of 3H-testosterone uptake (Ivanova, 1982).     

Binding of ADP to beef-heart mitochondrial ATPase (F1)

1. ADP binding to beef-heart mitochondrial ATPase (F1), in the absence of Mg2+, has been determined by separating the free ligand by ultrafiltration and determining it in the filtrate by a specially modified isotachophoretic procedure. 2. Since during the binding experiments the 'tightly' bound ADP (but not the ATP) dissociates, it is necessary to take this into account in calculating the binding parameters. 3. The binding data show that only one tight binding site (Kd about 0.5 microM) for ADP is present. 4. It is not possible to calculate from the binding data alone the number of or the dissociation constants for the weak binding sites. It can be concluded, however, that the latter is not less than about 50 microM.     

Isolation and characterization of an insulin-degrading enzyme from Drosophila melanogaster

An insulin-degrading enzyme (IDE) from the cytoplasm of Drosophila Kc cells has been purified and characterized. The purified enzyme is a monomer with an s value of 7.2 S, an apparent Km for porcine insulin of 3 microM, and a specific activity of 3.3 nmol of porcine insulin degraded/(min.mg). N-Terminal sequence analysis of the gel-purified enzyme gave a single, serine-rich sequence. The Drosophila IDE shares a number of properties in common with its mammalian counterpart. The enzyme could be specifically affinity-labeled with [125I]insulin, has a molecular weight of 110K, and has a pI of 5.3. Although Drosophila Kc cells grow at room temperature, the optimal enzyme activity assay conditions parallel those of the mammalian IDE: 37 degrees C and a pH range of 7-8. The Drosophila IDE activity, like the mammalian enzymes, is inhibited by bacitracin and sulfhydryl-specific reagents. Similarly, the Drosophila IDE activity is insensitive to glutathione as well as protease inhibitors such as aprotinin and leupeptin. Insulin-like growth factor II, equine insulin, and porcine insulin compete for degradation of [125I]insulin at comparable concentrations (approximately 10(-6) M), whereas insulin-like growth factor I and the individual A and B chains of insulin are less effective. The high degree of evolutionary conservation between the Drosophila and mammalian IDE suggests an important role for this enzyme in the metabolism of insulin and also provides further evidence for the existence of a complete insulin-like system in invertebrate organisms such as Drosophila.     

An immunological comparison of several novel calcium-binding proteins

Polyclonal antibodies prepared against each of the calcimedins were utilized to determine their tissue distribution. The immunological survey of rat tissues revealed that the levels of the 35-kDa calcimedin varied, while the amount of the 67-kDa calcimedin was relatively constant in the tissues examined. A new immunoreactive species, 52 kDa, was detected with the antibody to the 35-kDa calcimedin; this protein appears to be the predominant immunoreactive species in the tissues examined. Antibodies to the 35-kDa calcimedin were also used to compare many other calcium-binding proteins in order to determine immunological relationships. These comparisons demonstrate that the epidermal growth factor receptor/kinase substrate (p35), the src kinase substrate (pp36), and calregulin are immunologically unrelated to the calcimedins. However, it was found that the 67-kDa calcimedin and the p70 calelectrin are identical, as are the 35-kDa calcimedin and the p32.5 calelectrin. The calimedins are a subset of the chromobindins. In addition, the antibody to the 35-kDa calcimedin also cross-reacts with synexin, which may be related to the new 52-kDa immunoreactive protein identified.     

Differential anaphase-I behaviour between wheat and rye univalents in triticale-wheat hybrid plants

The chromosomes of the D genome of wheat and the genome R of rye can be distinguished at meiosis by C-banding in triticale-wheat hybrid plants. All members of both genomes almost exclusively formed univalents at metaphase I. However, at anaphase I the frequencies of equationally dividing chromosomes were higher for rye than for wheat chromosomes. The differential centromere behaviour at anaphase I is ascribed to differences in the time at which wheat and rye univalents are formed during the first meiotic prophase.