Showing papers by "University of California, Davis published in 1971"

The Troodos Massif, Cyprus and other Ophiolites as Oceanic Crust: Evaluation and Implications

Abstract: Many Alpine ophiolite complexes characteristically display a pseudostratiform sequence of ultramafics, gabbro, diabase, pillow lava and deep-sea sediments. These masses resemble the known rock suite from the ocean floor. They are either fragments of old oceanic crust and mantle caught up in deformed belts, or results of diapiric emplacement of partly molten mantle material on or near the sea bottom. Such complexes are widespread in the Tethyan mountain system and have been recognized also from the circumPacific region. The Troodos Massif, Cyprus, consists of a pseudostratiform mass of harzburgite, dunite, pyroxenite, gabbro, quartz diorite, diabase and pillow lava arranged in a dome-like manner. The diabase forms a remarkable dyke swarm, trending mostly north-south in which 100 km of extension is indicated over 100 km of exposure. Such a feature suggests formation by sea-floor spreading. Layering of pyroxenite, harzburgite and dunite generally is perpendicular to subhorizontal rock unit contacts. The harzburgite and dunite are tectonites and probably represent uppermost mantle. Pyroxenite, gabbro, quartz diorite and diabase may represent the products of partial fusion of mantle material or of fractional crystallization of such partial fusion products. Chemical compositions of mafic intrusive and extrusive rocks do not fit well with oceanic tholeiite compositions, but resemble greenstones and associated rocks recently reported from the oceans. The massif probably formed about an old Tethyan ridge. Some pillow lavas may be crust added after the main spreading episode. A fault zone active during emplacement of the lower units of the complex may represent a fossil transform fault. Complex chilled margins in the dyke swarms and mutually contradictory cross-cutting relations between dykes and plutonic mafic rock suggest formation of ocean crust by multiple intrusion of small portions of liquid. Uneven top surface of the dyke swarm and some conjugate dyke systems suggest independently varying rates of magma supply and extension. Other Tethyan ophiolites, particularly in Greece and Italy, exhibit internal structure parallel to, rather than perpendicular to, major rock units, and some show much less diversity in mafic rock type. If these masses are fragments of ocean floor and mantle, such differences in internal structure may be due to differences in spreading processes—perhaps differences in spreading rate.

Metachromatic Agar-Diffusion Methods for Detecting Staphylococcal Nuclease Activity

Abstract: Based on the metachromatic property of Toluidine Blue O, three, convenient agar-diffusion methods have been developed that enable detection of the nuclease of Staphylococcus aureus at concentrations as low as 0.005 mug/ml in agar and broth cultures. The interactions of agar and deoxyribonucleic acid with Toluidine Blue O are discussed.

Immediate and subsequent growth responses of maize leaves to changes in water status.

Abstract: Elongation of intact young leaves of maize was found to be dynamically dependent on soil water supply. With adequate water, elongation was remarkably constant but slowed when the water potential of the soil in pots dropped from -0.1 to -0.2 bar and stopped when it dropped to -2.5 bars. The corresponding range of leaf water potential was -2.8 to -7 bars. Elongation resumed in less than a few seconds after a mildly water-stressed plant was rewatered.The effects on leaf elongation of step-wise changes in water potential of the root solution were determined. When the water potential of the root medium suddenly decreased below 0 bar, growth stopped initially and then resumed at a lower rate. When the water potential was suddenly increased back to 0 bar, growth accelerated transitorily to a high rate before slowing to the steady state rate. These results suggest an increase in cell extensibility during water stress.Leaves stressed for 1 or more days attained after rewatering almost the length of the control leaves. Growth rate after rewatering did not exceed that of the control at the corresponding developmental stage except during the short transitory rapid phase lasting only a fraction of an hour.As stress developed, growth stopped before carbon dioxide assimilation decreased noticeably. Upon the release of mild and short stress, the transitory rapid growth completely made up for the reduced elongation during stress, suggesting that metabolic processes for cell expansion might have proceeded unchecked during the stress period.The sensitivity and rapidity of response to changes in water status all point to the direct role of water in growth; its uptake provides the physical force for cell enlargement.

Induction of Closely Linked Multiple Mutations by Nitrosoguanidine

Abstract: N-methyl-N-nitro-N-nitrosoguanidine (nitrosoguanidine) is a powerful and widely used mutagen. Using synchronized populations of Escherichia coliwe have shown that large numbers of mutations occur at specific loci when these loci are replicated1. This specificity makes it possible to use nitrosoguanidine to direct mutagenesis, to study the mode of replication of the chromosome and to map the chromosome1–4.

Effect of Nutrient Concentration on the Growth of Escherichia coli

Abstract: The relationship between specific growth rate of Escherichia coli and the concentration of limiting nutrient (glucose or phosphate or tryptophan) has been determined for populations in a steady state. At high concentrations the specific growth rate is independent of the concentration of nutrient, but at low concentrations the specific growth rate is a strong function of the nutrient concentration. Such a relationship was predicted by Monod; however, Monod's equation does not predict the relationship over the entire range of nutrient concentration. If parameters of the equation are estimated from the results obtained at low concentrations, then at high concentrations of nutrient, the specific growth rate is significantly higher than that predicted by Monod's equation. These results were interpreted on the basis that the rate of growth is controlled by at least two parallel reactions and that the affinities of the enzymes catalyzing these reactions are different. The relationship between specific growth rate and mean cell volume was also measured, and the results indicate that mean cell volume depends not only on the specific growth rate but also on the nature of the limiting nutrient. There are different mean cell volumes at the same specific growth rate established by different limiting nutrients. Therefore, the mean cell volume is not uniquely determined by the specific growth rate.

Fluorescent products of lipid peroxidation of mitochondria and microsomes.

Abstract: Liver microsomes and mitochondria and heart sarcosomes from rats fed diets with varying α-tocopherol concentrations and lipid contents were peroxidized over a 6 hr time period. Lipid peroxidation was measured by absorption of oxygen, production of thiobarbituric acid (TBA) reactants and by development of fluorescence. The spectral characteristics of the fluorescent compounds were the same for all peroxidizing systems; the excitation maximum was 360 nm and the emission maximum was 430 nm. As time of peroxidation increased, uptake of oxygen and production of fluorescent compounds increased. These two parameters as well as production of TBA reactants were dependent upon dietary antioxidant and all three had an inverse relationship with the amount of dietary α-tocopherol. The relationship between absorption of oxygen and development of fluorescent compounds was also dependent upon dietary polyunsaturated fats (PUFA). Subcellular particles from animals fed higher levels of PUFA produced more fluorescent products per mole of oxygen absorbed than did those from animals on a diet with lower PUFA content. TBA reacting products increased with time during the initial phase of peroxidation: in the microsomal systems their production stabilized or decreased by 4–6 hr of peroxidation. Using the synthetic 1-amino-3-iminopropene derivative of glycine as standard for quantitation of fluorescence, the molar ratios of oxygen absorbed per fluorescent compound produced were calculated. This ratio for subcellular particles isolated from rats fed diets with PUFA ratios similar to those in the average American human diet was 393∶1. The fluorescent compounds had the same spectral characteristics as the lipofuscin pigment that accumulates in animal tissues as a function of age, oxidative stress or antioxidant deficiency. The fluorescent molecular damage represented by that accumulated in human heart age pigment by 50 years of age was calculated to have been caused by approximately 0.6 μmole of free radicals per gram of heart tissue.

Calcium and Salt Toleration by Bean Plants

Abstract: The role of calcium in the salt relations of the bean plant, Phaseolus vulgaris, was examined. Brittle wax bush bean plants were cultured in nutrient solutions containing 50 mM NaCl. In the absence of added calcium the plants showed a general breakdown of the roots. A low concentration of calcium in the nutrient solution (0.1 mM) prevented this. Without added calcium the plants absorbed and translocated sodium at such a rate that high concentrations of it built up in the leaves within two days. With increasing concentrations of calcium in the nutrient solution the leaves contained progressively less sodium, and at 3 mM CaSO4 the concentrations of sodium in the leaves was equal to that of the control plants grown without addition of salt. Even after both roots and stems had reached a high concentration of sodium, the leaves of plants grown in the presence of adequate concentrations of calcium contained little sodium.

Genetic polymorphisms in varied environments.

Abstract: Thirteen experimenital populationis of Drosophila willistoni were maintained in cages, in some of which the environments were relatively constant and in others varied. After 45 weeks, the populations were assayed by gel electrophoresis for polymorphisms at 22 protein loci. The average heterozygosity per individual and the average unmber of alleles per locus were higher in populations maintained in heterogeneous environments than in populations in more constant enviroments.

Isolation and characterization of polyphenol oxidase isozymes of clingstone peach.

Abstract: The polyphenol oxidase system in clingstone peach (Prunus persica) was investigated. Polyacrylamide disc-gel electrophoresis indicated four bands with polyphenol oxidase activity in extracts from acetone powder of clingstone peach. These four isozymes were then isolated from a buffer extract of peach acetone powder by cold acetone precipitation, followed by diethylaminoethyl cellulose column chromatography. All isozymes had different heat stabilities. At 55 C, polyphenol oxidases A, B, and D had half-lives of 5.4, 14.6, and 14.1 minutes, respectively. Polyphenol oxidase C was stable over a period of 50 minutes of incubation at 55 C, but had a half-life of 2.2 minutes at 76 C. None of the isozymes had monophenolase activity, and they varied in their specificity for several diphenols. The following values were found for polyphenol oxidases A, B, C, and D, respectively, with catechol as substrate: optimal pH: 6.8, 6.5, 7.2, and 7.0; Michaelis constant: 6.6, 4.2, 7.0, and 36 mm; Vmax/(E0): 4.95, 39.4, 2.16, and 80.0 (ΔA min−1 mg−1). Each isozyme showed a different amount of inhibition by NaHSO3, NaCl, NaCN, l-ascorbic acid, glutathione, ethylenediaminetetraacetate, and sodium diethyldithiocarbamate.

Anhydrobiosis : an unsolved problem

Abstract: The reversible cessation of metabolism and growth is a unique biological state. There are two types of organisms which are normally capable of of entering this state (cryptobiosis): (1) propagules of certain organisms and (2) certain rotifers, tardigrades, and nematodes. The latter group of organisms offer a unique opportunity to study the discontinuity of life processes, uncomplicated by simultaneous developmental processes and complex endogenous factors such as those responsible for the maintenance of dormancy. Working hypotheses and lines of research are pointed out in the areas of (1) metabolism during anhydrobiosis, (2) biochemical adaptations to desiccation, (3) morphological adaptations to desiccation.

Teratogenic effects of short-term and transitory zinc deficiency in rats†

Abstract: Female rats fed a zinc-deficient diet during pregnancy (days 0 to 21) had impaired reproduction and a high incidence of congenitally malformed young even though they had been fed a normal diet adequate in zinc until the beginning of gestation. With a deficiency from days 0 to 21 of pregnancy 41% of the implantation sites were resorbed, full-term young weighed about half that of controls, and 90% of the fetuses showed gross malformations affecting every organ system. These results were similar to those found previously with females fed a zinc-low diet from weaning. The fetal malformations were specifically due to a maternal dietary deficiency of zinc rather than to reduced food intake since females fed restricted amounts of a zinc-supplemented diet had normal young. Shorter periods of deficiency were also teratogenic. With a deficiency from days 0 to 10 of pregnancy 22% of the young were malformed, and from days 0 to 12, 56% were malformed. When the zinc-deficient regime was imposed from days 6 to 14 of pregnancy almost half of the young were abnormal. Transitory periods of deficiency altered the incidences of the anomalies observed in accordance with the developmental events occurring at the time the deficiency was imposed. The rapid and severe effects of even relatively short periods of zinc deficiency on fetal development suggest that the pregnant rat cannot mobilize zinc from body stores in amounts sufficient to supply the needs of developing fetuses.

Correlation of 30S ribosomal proteins of Escherichia coli isolated in different laboratories.

Abstract: Ribosomal proteins isolated from 30S subunits ofE. coli in four laboratories have been correlated by using two-dimensional gel electrophoresis, immunological techniques, amino acid compositions and molecular weights. The results are given in the Table. A common nomenclature for naming 30 S ribosomal proteins and their genetic loci is proposed.

Organizational Crisis and Change.

Abstract: This article presents a conceptual framework for describing organizational crises. Based upon the assumption that a human system passes through several phases as it adapts to a crisis situation, the article describes a four-stage model, beginning with an initial period of Shock, then a period of Defensive Retreat, followed by Acknowledgment, and finally, by a process of Adaptation and Change. The four phases are presented as they apply to the individual in crisis and then are extended to incorporate organizational parameters. This is followed by a discussion of the model's relationship to other known concepts in the areas of behavior under stress, the processes of change, small-group behavior, leadership style, and organizational structure. The article concludes with some implications about the potential use of this conceptual framework as a guide to the organizational consultant.

Photodecomposition of Chlorinated Dibenzo-p-Dioxins

Abstract: The toxic herbicide impurity 2,3,7,8-tetrachlorodibenzo-p-dioxin and its homologs decomposed rapidly in alcohol solution under artificial light and natural sunlight, the rate of decomposition depending upon the degree of chlorination. However, photodecomposition was negligible in aqueous suspensions and on wet or dry soil.

The Heterocysts of Blue-Green Algae. II. Details of Ultrastructure

Abstract: Heterocysts of Anabaena cylindrica in intact filaments or separated from vegetative cells were examined using improved methods of fixation with glutaraldehyde followed by potassium permanganate or osmium tetroxide. The heterocyst envelope, formed external to the outer layer (L$_{\text{IV}}$) of the pre-existing cell wall, is composed of three distinct layers, i.e. the inner laminated, the middle homogeneous and the outermost fibrous layers. These layers are absent at the narrow point of contact between heterocyst and vegetative cell. Here the septum appears to be traversed by microplasmodesmata interconnecting the plasmalemmas of the heterocyst and adjacent vegetative cell. In addition to the characteristic reorganization of thylakoids an extensive membrane elaboration was observed in the heterocysts. This takes the form of dense layering and, frequently, coiling and leads to a marked increase of the membrane surface area within the cell. The heavily contorted membranes beneath the pore channel undergo some change in structure resulting in an appearance of membrane disintegration and in the gradual accumulation of an electron opaque material within the pore channel. The possible significance of the observed structural changes is discussed in relation to the suggested role of heterocysts in nitrogen fixation and to the interrelations between heterocysts and vegetative cells.

Microorganisms of the San Francisco Sour Dough Bread Process: I. Yeasts Responsible for the Leavening Action

Abstract: Two hundred isolates from San Francisco sour dough French bread fermentations (40 from each of five different bakeries) were screened by fermentation tests and for their ability to grow in the presence of cycloheximide (Actidione). All of the isolates from four of the bakeries and 70% of those from the fifth were unable to utilize maltose but grew well on other sugars, even in the presence of cycloheximide. The remaining few isolates from the fifth bakery utilized maltose but not galactose and were inhibited by cycloheximide. No bakers' yeast types were found. Sixteen of the maltose-negative and five of the galactose-negative isolates were subjected to more rigorous taxonomic procedures. All of the maltose-negative isolates were identified as asporogenous strains of Saccharomyces exiguus (Torulopsis holmii) and the galactose-negative ones, as S. inusitatus. The predominance of S. exiguus, its vigor in the particular acidic environment of the sour dough, and the correlation of its numbers with the leavening function constitute strong evidence on the role of this organism in the sour dough system.