Showing papers by "University of Maryland, Baltimore County published in 1973"

The effects of inhibitors of RNA and DNA synthesis on protein synthesis and polysome levels in mouse L-cells.

Abstract: Metabolic inhibitors of RNA synthesis, such as actinomycin D and MPB (2-mercapto-1-(β-4-pyridethyl) benzimidazole) have often been used to test the possibility that transcription is required for some cellular process or to measure the „half-life” of messenger RNA (mRNA). The basic assumption of this work has been that the primary effect of these inhibitors is on transcription alone, and that any effect on translation is secondary to the inhibition of mRNA synthesis. This assumption has been tested by examining the effects of these inhibitors at different doses on various parameters of the transcriptional and translation processes in mouse L-cells in culture, i.e., the rates of RNA, DNA, and protein synthesis; the level and size of cytoplasmic polysomes; the rates of polypeptide elongation and termination, and the role of peptide chain initiation in protein synthesis. The results indicate that the basic assumption is not correct since these inhibitors affect protein synthesis by inhibiting the rate of initiation and not the level of mRNA. Another implication of the experiments is that the average mRNA in L-cells has a half-life of at least one cell generation (16–18 hours), and that earlier values from experiments using actinomycin are underestimates. Cordycepin (3′-deoxyadenosine) which inhibits the production of ribosomal and messenger RNA also affects protein synthesis at the level of initiation. In contrast, two inhibitors of DNA synthesis (hydroxyurea and cytosine arabinoside) inhibit protein synthesis and the level of polysomes by some other mechanism.

Segmental aneuploidy as a probe for structural genes in Drosophila: mitochondrial membrane enzymes.

Abstract: A method for detecting possible structural genes in D. melanogaster based on gene dosage dependency is presented. By making thirty crosses between Y-autosome translocations, and an attached-4 cross, it is possible to produce large duplications (approximately 150 salivary gland chromosome bands in length) for every autosomal region with the exception of 83DE. The usefulness of the technique was demonstrated by dosage dependency of three known gene-enzyme systems: α- glycerophosphate dehydrogenase-1, alcohol dehydrogenase and malate dehydrogenase . A screen for genes affecting two enzymes localized on the inner membrane of the mitochondrion, α-glycerophosphate oxidase (αGPO) and succinic dehydrogenase (SHD), produced a dosage-sensitive region in each case. Region 50C-52E affected αGPO activity and region 28D-29F affected SDH activity. The latter region apparently includes the malic dehydrogenase-1 gene. The methodology and limitations of the technique are discussed.

Flower Formation in Excised Tobacco Stem Segments: III. Deoxyribonucleic Acid Content in Stem Tissue of Vegetative and Flowering Tobacco Plants.

Abstract: A method has been developed that extracts DNA from stem tissue of flowering tobacco plants, Nicotiana tabacum cv. Wis. 38. The DNA content of stem tissue from a flowering tobacco plant is correlated with its capacity to flower in vitro. Stem segments known to form 100% floral buds contain 10 times more DNA per gram fresh weight than segments that form 5% floral buds and 95% vegetative buds, and in the uppermost 28 centimeters of flowering tobacco plant stems the DNA content decreases roughly in parallel with the floral gradient.((3)H)-Thymidine incorporation into DNA in the internodes is inhibited by attached leaves in flowering tobacco plants but promoted in vegetative plants. Low indoleacetic acid concentrations (2.8 and 5.7 mum) inhibit DNA synthesis in internodes of defoliated stems of flowering tobacco plants to the same extent as attached leaves, whereas the same concentrations of indoleacetic acid promote DNA synthesis in internodes of defoliated stems of vegetative plants. The optimal concentration (11.4 mum) of indoleacetic acid supplied to defoliated stems of vegetative plants increased the rate of DNA synthesis to 4 times the rate in defoliated stems without indoleacetic acid treatment. This increase more than compensates for the promotion of DNA synthesis by the young leaves. Thus, the opposite effects of young leaves on DNA synthesis in internodes of flowering and vegetative tobacco plants may be related to their auxin content.

The Analysis of Regional International Politics: The Integration Versus the Empirical Systems Approach

Abstract: It is argued that the study of regional international politics is important (1) for empirical reasons having to do with the real world saliency of the region as a factor in international politics; (2) for theoretical reasons having to do with the subordinate system as being relatively neglected in scholarship with the exception of the integrationist approach; and (3) for policy reasons having to do with the importance of accurately understanding the dynamics of the region as part of the objective of stabilizing the international system. The dominant approach to regional international politics of the integrationists (neo–functionalists and transactionalists) is then discussed and criticized in terms of the two approaches' normative concerns, the nature of the model utilized, and the theoretical issues that are raised. A major conclusion is that the integrative model used is inappropriate as a vestige of the level of analysis problem, and such theoretical issues as the nature of the dependent variable remain unspecified. It is then argued that the authors' formulation of an empirical systems approach begins to meet these criticisms.

EEG, heart rate and mood change (“high”) after Cannabis

Abstract: Fourteen experienced marijuana users smoked marijuana, hashish, δ 9-THC, and placebo. EEG, ECG and ratings of subjective feelings of “high” and pleasantness were recorded. EEGs were processed by period analysis. In EEG, marijuana and δ 9-THC increased the amount of alpha activity, and the three Cannabis preparations decreased the amount of beta activity. The average frequency of alpha activity was decreased by 0.15–0.20 c/sec after marijuana, hashish and δ 9-THC. The peak EEG effect occurred during the first 10 min after smoking; most of the changes disappeared after 40 min. Heart rate was increased by all the three drugs, and the effect persisted for the entire observation period (50 min). Feelings of “high” were elicited by each Cannabis preparation. This was not true of the pleasantness of the experience: only marijuana and hashish were perceived as more pleasant than placebo. Intensity of “high” increased with the amount of alpha activity, and decreased with the average alpha frequency. Pleasantness was unrelated to the EEG. The “high” showed a linear increase with heart rate, whereas pleasantness of the experience was an inverted U-function of heart rate.

Comparison of two self-administered field dependency measures

Abstract: Summary.-The present study examined the correlations between the recently developed group embedded-figures test (GEFT) , the hidden-figures test Form-V, and the rod-and-frame test (RFT). 30 college males randomly selected from introductory and experimental psychology courses were administered the three measures of field dependency within a 2-wk. period. Intercorrelations among the three tests were significant (~~E'T/BPT = -.691, p < .005; rrlmtnm = -.476, p < .005; T~EET/ABT = -.749, p < ,005). A t test for related correlations indicated that the two correlations with the rod-and-frame test were significanrly different (t = 2.19, 9 < ,025). The validity of the hidden-figures test as a measure of field dependency is questioned.

Surface structure of gliding bacteria after freeze-etching

Abstract: Ultrastructural studies of gliding bacteria demonstrate 10- to 11-nm beads on the inner surface of the outer bilayer of Cytophaga columnaris These were not found in Myxococcus xanthus On treatment with glutaraldehyde and ethanol, the beads appear in linear arrays

American Manufacturers and Foreign Markets, 1870-1900: Business Historians and the "New Economic Determinists"

Abstract: C Recent diplomatic historians have explained much of American expansionism at the end of the nineteenth century as the product of domestic industrial overcapacity and the resulting need to seek foreign markets. Evidence of business behavior, however, indicates that overseas expansion and exports were not a very important avenue through which U.S. businessmen sought to control prices and output. Indeed, in most of the industries which did engage in significant foreign activities, their expansion was usually the result of genuine competitive advantages rather than a sign of economic ill health. William Appleman Williams' The Tragedy of American Diplomacy is one of the most influential and popular interpretations of the sources of American expansionism. Williams argues that American industry turned out such an oversupply of goods in the late nineteenth century that America was impelled to develop foreign markets to relieve the glutted domestic economy. Manufacturers sought exports, and government policy makers facilitated that search, in order to employ workers periodically idled by economic crises brought on by overproduction and underconsumption.' In his more recent work, The Roots of the Modern American Empire, Williams explored the role of farmers in America's outward thrust "toward overseas markets as a crucial element in the nation's well being." While concentrating on agriculturalists, however, he still maintains that "various elements of the industrial part of the economy . . produced increasing surpluses. They had to be exported if they were to be sold at all." 2

Oxidant for Trapping Atmospheric Radiokrypton

Abstract: RECENTLY, Stein1 presented a chemical method of removing radioactive xenon from the effluent gases of nuclear power plants and fuel reprocessing plants. His chemical oxidant, O2+SbF6−, successfully trapped xenon and radon, but not krypton. This result is reasonable if the initial reaction is electron transfer from the noble gas, Ng, to the O2+ cation. Multistep fluorine (F and F−) transfer then produces NgF+. More quantitatively, the experimental ionization potentials for Rn and Xe, 10.748 eV and 12.130 eV (ref. 2) are, respectively, less than and commensurate with that of O2, 12.07 eV (ref. 3). Accordingly, electron transfer may be expected. Because the ionization potential of Kr is2 13.999 eV, however, no reaction is expected between O2+ and Kr.

Signal Detection on Lie Groups

Abstract: In a series of recent papers (e.g., [1] through [6]), control, estimation, and detection problems in which the natural state space is a Lie group have been studied. Among practical problems of this kind are frequency modulation and demodulation, frequency stability, gyroscopic analysis, satellite attitude control, power conversion, etc. It is the purpose of this paper to formulate and study a class of detection problems on an arbitrary matrix Lie group.

Psychological differentiation and the response of opiate addicts to pharmacological treatment.

Abstract: Summary The degrees of psychological differentiation of 21 opiate dependent males, as measured by the Embedded Figures Test, were found to be unrelated to their scores on a self-report questionnaire (HAQ) which a previous study had shown capable of distinguishing between addicts who do and do not respond well to an heroin antagonist. The HAQ, however, Has sufficiently high internal consistency to warrant further exploration of its usefulness.

Regions of response transition of color-coded retinal units and an attempted, analogy to behavioral response transition

Abstract: Electrophysiological responses obtained from single color-coded red-green ganglion ceils of the goldfish retina were analyzed in terms of the spectral region within which response transitions occur. The data showed that criteria for response transitions can be characterized by a frequency change with the stipulation that the same number of “on” and “off” spikes occur to the same wavelength(s). The overall spectral band within which response transition occurs is 570–620 nm. The physiological response ranges were compared to psychophysical unique-yellow responses and other “yellow” judgments. The former were displaced towards the longer wavelengths as predicted by the different pigment peaks. The response characteristics of sharp boundaries and relative invariance with intensity changes provided the basis of an analogy of the two response systems.

Enzymatic defects in three genetic classes of serine-requiring mutants of Bacillus pumilus.

Abstract: Serine-requiring mutants of Bacillus pumilus NRRL B-3275 have been divided into three groups based on the position of the mutant loci on the linkage map of this organism. Representatives of each group were found deficient in enzymatic activities that constitute the phosphorylated pathway for serine biosynthesis. The evidence suggests that the genes coding for the enzymes of the phosphorylated pathway of serine biosynthesis are not clustered in B. pumilus.