Showing papers by "University of California, Davis published in 1970"
TL;DR: Studies of viscosity and circular dichroism and dialysis experiments indicate that the active glycoproteins are expanded molecules, a property which undoubtedly is of importance to their function.
432 citations
TL;DR: The taxonomic significance of production of hydroxamic acids is described in connection with the position of these yeast species in the subclass Heterobasidiomycetidae.
Abstract: An examination of 142 strains within 19 genera of yeasts and yeastlike organisms for formation of hydroxamic acids in low-iron culture showed production of hydroxamates by two unclassified strains and by 52 strains among the genera Aessosporon (3 of 3 strains), Cryptococcus (1 of 43), Leucosporidium (3 of 11), Rhodosporidium (4 of 4), Rhodotorula (27 of 39), Sporidiobolus (2 of 2), and Sporobolomyces (12 of 13). Crystalline rhodotorulic acid was isolated in amounts sufficient to account for most or all of the measured hydroxamate in culture supernatants of 16 strains representative of the five last-mentioned hydroxamate-producing genera. A new alanine-containing ferrichrome was isolated from one strain of Cryptococcus melibiosum. Rhodotorulic acid was a major metabolic product of many of the positive strains when grown in low-iron media, and iron was shown to repress its synthesis and excretion into the culture medium. The taxonomic significance of production of hydroxamic acids is described in connection with the position of these yeast species in the subclass Heterobasidiomycetidae.
282 citations
TL;DR: In this paper, the conditions of genetic selection that may have led some groups of men to have persistently high levels of intestinal lactase throughout life, and others not, are considered.
Abstract: The principal conclusion reached in Part I of this article (1) was that the group differences found in primary adult lactose intolerance among the world's peoples are largely genetic in origin. In this part, after a review of recent research that adds to Part I in important ways, we turn to a consideration of the conditions of genetic selection that may have led some groups of men to have persistently high levels of intestinal lactase throughout life, and others not. Low incidence of intolerance, it is held, would develop over time in a group that has an abundant milk supply, that has alternate foodstuffs inadequate in amount and quality, and that consumes milk in lactose-rich forms. Since such selection cannot have occurred among groups that did not use milk, areas of nonmilking in the modern world are first delimited. The origins and diffusion of dairying are then sketched to determine the length of time that milk was consumed in various regions. With the background thus gained, the present-day occurrence of various Old World groups with high and low incidences of intolerance is explained. All groups studied so far within the traditional areas of nonmilking are found to have high incidences of intolerance. Overseas groups, such as American Negroes, whose ancestors came from nonmilking regions also have high incidences of intolerance. Within the areas of milking in Africa and Europe, moreover, the known group differences in tolerance are found to be in accord with the hypothesis. Then, that the hypothesis may further be confirmed, specific additional research efforts are suggested.
263 citations
TL;DR: Isozyme variants were adopted as markers in this investigation because of their many advantages in studying such populational processes as the mating system and the results obtained when the method was applied to isozyme data from two open-pollinated populations of maize are presented.
Abstract: mating system by which a given population reproduces plays an imT g t a n t role in determining its genetic structure. In maize, random mating has usually been assumed. However, GUTTIEREZ and SPRAGUE (1959), in a shtdy of polycross plantings of ten stocks which were homozygous for recessive markers, found marked differences in the effectiveness of the stocks as male and female parents. They showed that these differences related to attributes of the mating system such as time of silking and time of pollen shedding. The investigation reported here was undertaken to determine whether such marked deviations from random mating occur in advanced generation open-pollinated populations of maize. Isozyme variants were adopted as markers in this investigation because of their many advantages in studying such populational processes as the mating system. However, isozymes are frequently expressed only at some specific stage in the life cycle and then only in materials grown under carefully controlled conditions. Further, sampling an individual for enzymatic assay may cause damage that upsets the growth pattern and ultimately affects mating behavior; this applies particularly when isozymes are expressed only in seedlings, as is often the case. These difficulties can be circumvented by collecting seeds from mature plants in the field, and inferring the genotype of the maternal parent from progeny tests of seedlings grown under controlled conditions. In this situation an appropriate statistical method for estimating the relevant mating system parameters is required. Such an estimation procedure is described and discussed in the first part of this paper. Following this the results obtained when the method was applied to isozyme data from two open-pollinated populations of maize are presented.
258 citations
TL;DR: On uncontaminated specimens, no structures were found which resembled the particulate material of natural membranes and neither degree of saturation, degree of hydration, nor cholesterol admixture significantly affects the appearance of lamellar fracture faces which appear uniformly smooth.
247 citations
TL;DR: It is shown here how the diversity of marine fauna and fluctuations in sea level can be related to patterns of continental fragmentation and reassembly and the timing of major transgressions and regressions predicted from these patterns agrees well with the observed record.
Abstract: A GROWING body of evidence and theory supports the idea that processes of plate tectonics have been operating for the past 3 × 109 years1. The hypothesis of ocean-driven plates implies that certain mountain systems represent the remains of former large ocean basins. An important corollary of this notion is that the history of continental assembly and fragmentation can be inferred from the geological record of the various mountain systems. We show here how the diversity of marine fauna and fluctuations in sea level can be related to patterns of continental fragmentation and reassembly. It seems that changes in the diversity of fauna predicted from these patterns can account for a great deal of the variation in the diversification and extinction of marine biota that has long puzzled palaeontologists. The timing of major transgressions and regressions predicted from these patterns also agrees well with the observed record.
241 citations
TL;DR: As a guide to future experiments, the chief experiential effects of marijuana have been elucidated with the help of a detailed questionnaire given to seasoned marijuana users whose experiences, it seems, are almost entirely pleasant.
Abstract: As a guide to future experiments, the chief experiential effects of marijuana have been elucidated with the help of a detailed questionnaire given to seasoned marijuana users whose experiences, it seems, are almost entirely pleasant.
229 citations
TL;DR: The growth rate of rice coleoptiles is increased by low concentrations of ethylene, especially in oxygen concentrations lower than air; carbon dioxide enhanced this response.
Abstract: The growth rate of rice coleoptiles is increased by low concentrations of ethylene, especially in oxygen concentrations lower than air; carbon dioxide enhanced this response. C2H4 is produced by rice seedlings, and this production is also enhanced by carbon dioxide. Ethane and propane were produced in trace amounts but were inactive in growth stimulation as were also methane, propylene, and butane.
223 citations
TL;DR: Since VMAX is expressed in terms of muscle units and is free of variables of left ventricular loading and wall thickness, this method permits specific comparison of inotropic state among different patients and allowed determination of maximal VCE, the independent numerical measure of contractility.
Abstract: A new and easily applicable means based on force-velocity principles within the framework of muscle mechanics is presented for quantification of ventricular contractility, independent of loading, in conscious patients. In the intact heart during isovolumic contraction, alterations in ventricular geometry are small, and thus contractile element velocity (VCE) can be assumed to equal series elastic elongation. It was therefore considered in this study that VCE during isovolumic portion of ejecting beats could be determined entirely from isovolumic pressure (IP) and its rate of rise ( dP dt ) without requiring knowledge of tension; this provided the rational basis for accurate calculation of instantaneous isovolumic VCE in the spherical or ellipsoidal ventricle as ( dP dt )/( K × IP ) , where K is series elastic constant of 32 per muscle length (ML) at body temperature. Further, it was recognized that VCE at the ordinate is identical when derived from pressure-velocity or tension-velocity curves, and since the left ventricular pressure-velocity relation can be defined precisely, construction of the isovolumic IP to VCE curve and extrapolation to zero load allowed determination of maximal VCE (vmax), the independent numerical measure of contractility. High fidelity left ventricular pressures and corresponding dP dt were continuously recorded in 23 studies in 8 conscious patients without valvular regurgitation or ventricular segmental disease. Increasing contractility by leg exercise raised VMAX from 1.19 to 1.58 ML/sec and by isoproterenol to 2.03 ML/sec (P dP dt during isovolumic systole affords a new, practical, sensitive and valid means of quantifying left ventricular contractility Without influence of preload and afterload from beat to beat in individual patients. In addition, since VMAX is expressed in terms of muscle units and is free of variables of left ventricular loading and wall thickness, this method permits specific comparison of inotropic state among different patients.
212 citations
TL;DR: It is concluded that nonmethanogenic microbes metabolize intercellular formate in the rumen, and CO(2) and H( 2) are the principal substrates for rumen methanogenesis.
Abstract: An average of 11 (range, 2 to 47) mumoles of formate per g per hr was produced and used in whole bovine rumen contents incubated in vitro, as calculated from the product of the specific turnover rate constant, k, times the concentration of intercellular formate. The latter varied between 5 and 26 (average, 12) nmoles/g. The concentration of formate in the total rumen contents was as much as 1,000 times greater, presumably owing to formate within the microbial cells. The concentration of formate in rumen contents minus most of the plant solids was varied, and from the rates of methanogenesis the Michaelis constant, K(m), for formate conversion to CH(4) was estimated at 30 nmoles/g. Also, the dissolved H(2) was measured in relation to methane production, and a K(m) of 1 nmole/g was obtained. A pure culture of Methanobacterium ruminantium showed a K(m) of 1 nmole of H(2)/g, but the K(m) for formate was much higher than the 30 nmoles for the rumen contents. It is concluded that nonmethanogenic microbes metabolize intercellular formate in the rumen. CO(2) and H(2) are the principal substrates for rumen methanogenesis. Eighteen per cent of the rumen methane is derived from formate, as calculated from the intercellular concentration of hydrogen and formate in the rumen, the Michaelis constants for conversion of these substrates by rumen liquid, and the relative capacities of whole rumen contents to ferment these substrates.
206 citations
TL;DR: A purified rabbit skeletal muscle adenosine 3',5'-monophosphate (cyclic AMP)-stimulated protein kinase enhanced lipolytic activity in adipose tissue homogenates and it is inferred that this effect is due to the phosphorylation and activation of a lipase in a system analogous to that involved in the activation of muscle glycogen phosphorylase.
TL;DR: A protein kinase that is stimulated by cyclic 3′,5′-AMP has been purified 250-fold from beef heart and could be partially restored with mercaptoethanol.
TL;DR: An attempt to synthesize regional and structural geology, particularly in the Alpine and Cordilleran systems, during the whole of Phanerozoic time.
Abstract: An attempt to synthesize regional and structural geology, particularly in the Alpine and Cordilleran systems, during the whole of Phanerozoic time.
TL;DR: Penicillium chrysogenum will grow on methylamine (methylammonium chloride) as its sole nitrogen source and the permease is subject to feedback inhibition by intracellular glutamine and asparagine, and the original development of transport activity could result from derepression.
TL;DR: Results indicated that the reduced polyribosomal level was not an artifact caused by ribonuclease during isolation, and it appears possible that stress-effected loss inpolyribosomes occurs only if polypeptides can be terminated and released.
Abstract: Sucrose gradient profiles of polyribosomes from the coleoptilar node region of seedlings of Zea mays L. were obtained without pelleting and redispersion of the particles. Water stress caused a shift of ribosomes from the polymeric to the monomeric form, starting about 30 minutes after stress initiation and when the water potential of the tissue began to decrease measurably. After about 4 hours of stress (a decrease in tissue water potential of about 5 bars), most of the higher polymers of ribosomes had shifted to monoribosomes. Release of stress caused the ribosomes to revert from monomeric to polymeric form after a lag period apparently determined by the extent of prior stress. Use of bentonite and isolation of polyribosomes from combined stressed and control tissue gave results indicating that the reduced polyribosomal level was not an artifact caused by ribonuclease during isolation.Incubating roots in cycloheximide (2 micrograms per milliliter) had no effect on the proportion of polyribosomes in control roots, but it prevented the loss of polyribosomes caused by stress. Since cycloheximide inhibits the release of nascent polypeptide from polyribosomes, it appears possible that stress-effected loss in polyribosomes occurs only if polypeptides can be terminated and released.
TL;DR: Two mixed-sex groups of subadult M. mulatta, maintained under chronic crowding stress, were characterized re adrenal responsiveness to ACTH (via urinary 17-hydroxycorticosteroids) and intragroup social behavior over a 2-year period which included a series of changes in social environment.
TL;DR: In this paper, the general one-dimensional Saint-Venant equations are presented for a rigid open channel of arbitrary form, not necessarily prismatic, containing a flow that may be spatially varied.
Abstract: The general, one-dimensional Saint-Venant equations are presented for a rigid open channel of arbitrary form, not necessarily prismatic, containing a flow that may be spatially varied. The theoretical basis for the method of characteristics is reviewed and used to show that, in the general case, the speed of long-wave disturbances is given by the slope of the characteristic curves. Finite-difference schemes on a rectangular net in the x - t plane and based on the characteristic forms of the Saint-Venant equations, as well as on the direct forms, are given and examined for their stability. The von Neumann technique for stability analysis is presented in detail. Explicit numerical schemes, which are simple, but require small steps in time because of stability problems, are contrasted with implicit schemes that permit numerical solution over large time steps but require the solution of large sets of simultaneous algebraic equations at each step. The double-sweep or progonka method, an exact time- and space-saving technique for solving these (locally linearized) equations, is also given in detail.
TL;DR: Injury caused by Lygus hesperus Knight is due principally to the enzymatic digestion of the plant’s tissue by polygalacturonase secreted during feeding.
Abstract: Injury caused by Lygus hesperus Knight is due principally to the enzymatic digestion of the plant’s tissue by polygalacturonase secreted during feeding. A limited amount of mechanical injury may result from feeding. L. hesperus is unable to synthesize indoleacetic acid and is also unable to secrete plant hormones in its saliva after having ingested these hormones in its diet. The type of damage associated with feeding, i.e., necrosis, abscission of reproductive organs, “blasting,” “cat facing,” or reduction of vegetative growth, depends upon the size of the organ fed upon and the specific site of feeding. If feeding results in the destruction of specific hormone producing sites, the resultant damage is in accord with the known physiological responses of plants to hormonal manipulation.
TL;DR: In the early Cretaceous, ocean-floor spreading gradually opened up the tropical Atlantic and the Indian Ocean basin widened as the eastern segments of Gondwanaland were conveyed farther apart as discussed by the authors.
Abstract: During the Early Cretaceous, ocean-floor spreading gradually opened up the tropical Atlantic and the Indian Ocean basin widened as the eastern segments of Gondwanaland were conveyed farther apart. At the same time, epeiric seas were advancing on all continents, reaching maximum extent during the Cenomanian. The resultant trend to widespread, more equable climate favored the invasion into the lowlands of angiosperms whose postulated origin was in mild uplands at low latitudes during pre-Cretaceous times. As tropical and subtropical lands were rafted farther apart by ocean-floor spreading following Albian-Cenomanian times, new taxa (species, genera, tribes, families) evolved in isolation. This accounts in part for the increasing richness of the three major tropical floras following the Cretaceous. Changes in Mesozoic paleogeography also appear to clarify several other puzzling aspects of early angiosperm history and distribution, including their early appearance at middle latitudes.
TL;DR: Stomata in epidermal strips of Vicia faba opened in light and closed in darkness when floated on dilute K(+) solutions, suggesting that photosystem I and cyclic electron flow can supply the necessary energy for K(+ uptake and stomatal opening.
Abstract: Stomata in epidermal strips of Vicia faba opened in light and closed in darkness when floated on dilute K(+) solutions. Opening and closing, respectively, paralleled the fluxes of labeled K(+) into and out of the strips. The gain and loss of K(+) by the strips were shown by colbaltinitrite stain to be centered at guard cells. Intact epidermal cells, however, appeared to take up K(+), complicating interpretation of the data.The specific requirement of K(+) for stomatal opening in light appeared to be related to the specific uptake of K(+). There was little or no light stimulation of opening in strips on Na(+), nor was there stimulation of Na(+) uptake. The marked light stimulation of opening on K(+) was generally matched by stimulation of K(+) uptake.Anaerobiosis markedly reduced opening in leaf discs but not in strips. Under anaerobic conditions, opening in strips was not appreciably affected by 3(3,4-dichlorophenyl)-1,1-dimethylurea (diuron) but was completely inhibited by carbonyl cyanide m-chlorophenylhydrazone plus diuron. Inhibition of opening was generally correlated with inhibition of K(+) uptake by the strips. Also stomata in strips opened well under far red light (>700 nanometers). These data suggest that photosystem I and cyclic electron flow can supply the necessary energy for K(+) uptake and stomatal opening.
TL;DR: In this article, a step-by-step derivation of the Marquardt's algorithm is given in terms that require only a knowledge of elementary calculus and matrix algebra, and the method is used to fit the logistic equation to a set of data.
Abstract: Equations describing biological phenomena frequently have parameters entering nonlinearly. A highly efficient method for determining the values of parameters in such equations that will give the best least—squares fit to a set of data is Marquardt's algorithm. A step—by—step derivation of the algorithm is given in terms that require only a knowledge of elementary calculus and matrix algebra. As an example, the method is used to fit the logistic equation to a set of data. See full-text article at JSTOR
TL;DR: In this article, the authors present an approach to solve the problem of how to find the minimum number of nodes for a node in order to obtain the maximum number of vertices.
Abstract: s, XZth Znt. Bot. Congr. Seattle, U.S.A. Lancaster 41, 826-30. Physiol., Lancaster 26, 189-91.
TL;DR: The ADP-glucose-protected site CNBr [3H]pyridoxyl peptide was purified to homogeneity by Sephadex G-50 and DEAE-cellulose chromatography and the sequence of this peptide has been elucidated.
TL;DR: The structure and properties of the freezing point-depressing glycoproteins from a cold-adapted Antarctic fish were examined by means of chemical modifications and enzymatic and chemical degradations and revealed that galactose is in the external position and that N-acetylgalactosamine is linked to threonine.
TL;DR: Chloramphenicol specifically inhibited the synthesis of the large subunit of ribulosediphosphate carboxylase and influenced production of the larger subunit by rapidly inhibiting total protein synthesis.
TL;DR: Thirty-five Ss were asked to scale their depth of hypnosis on a 10-point scale after each suggestibility test item on the Stanford Hypnotic Susceptibility Scale, Form C and these self-reports were highly correlated with measures of hypnotic behavior and experience.
Abstract: Hypnotic “depthyy is a complex theoretical concept, for which no direct measures exist at present, but which is reflected in various experiential and behavioral responses to hypnosis. Thirty-five Ss were asked to scale their depth of hypnosis on a 10-point scale after each suggestibility test item on the Stanford Hypnotic Susceptibility Scale, Form C (Weitzenhoffer & Hilgard, 1962). These self-reports were highly correlated with measures of hypnotic behavior and experience. Instructions to report depth immediately and without thinking produced reports which correlated somewhat better with the other measures than instructions to consciously make a best estimate. This self-report scale promises to be highly useful in studies of hypnosis.
TL;DR: A retrospective study of canine mammary neoplasms derived from 3 different populations of dogs found that more carcinomas were seen among neutered than intact females except in the closed beagle colony where carcinoma was the most frequent neoplasm in the exclusively intact female population.
Abstract: lo%, I