Showing papers by "University of California, Davis published in 1972"

Forced convection heat transfer correlations for flow in pipes, past flat plates, single cylinders, single spheres, and for flow in packed beds and tube bundles

Abstract: Previously obtained experimental heat transfer data have been collected and are illustrated along with minor variations of the standard correlations. Analysis of data for heat transfer in randomly packed beds and compact (void fraction less than 0.65) staggered tube bundles indicates that the Nusselt number for a wide range of packing materials and tube arrangements is given by provided NRe ≥ 50. The correlations presented in this paper are not necessarily the most accurate available; however, they have wide application, are easy to use, and are quite satisfactory for most design calculations.

Enzyme variability in the drosophila willistoni group. iv. genic variation in natural populations of drosophila willistoni

Abstract: We describe allelic variation at 28 gene loci in natural populations of D. willistoni. Seventy samples were studied from localities extending from Mexico and Florida, through Central America, the West Indies, and tropical South America, down to South Brazil. At least several hundred, and often several thousand, genomes were sampled for each locus. We have discovered a great deal of genetic variation. On the average, 58% loci are polymorphic in a given population. (A locus is considered polymorphic when the frequency of the most common allele is no greater than 0.95). An individual fly is heterozygous, on the average, at 18.4% loci.—Concerning the pattern of the variation, the most remarkable finding is the similarity of the configuration of allelic frequencies from locality to locality throughout the distribution of the species. Our observations support the conclusion that balancing natural selection is the major factor responsible for the considerable genetic variation observed in D. willistoni.

Vitamin e and free radical peroxidation of lipids

Abstract: Several broad lines of scientific evidence showing that vitamin E functions as a lipid antioxidant, inhibiting the destructive peroxidation of polyunsaturated lipids, have been presented in recent reviews.'-Q Further, the function of vitamin E is a very broad topic, study of which can be based in part on knowledge of other lipid antioxidant reactions and interrelationships. Also, the reactions of and the damage caused by free radical peroxidation of lipids are complex topics, and in a relative sense the mechanisms of damage are not well understood, although they appear to have counterparts in radiation biochemistry. In view of the breadth of this topic, it is appropriate in the first section of this paper to direct attention to the major review sources in which information on the subject is summarized, and to some recently published papers. TABLE 1 lists some of the major factors in the suppression of lipid peroxidation. On the basis of the chemical properties of a-tocopherol and the mechanisms of antioxidation, a-tocopherol would be expected to react as a chain-breaking antioxidant in the inhibition of the free radical peroxidation of lipids. The propagation reaction in which the polyunsaturated lipid LH is peroxidized, L' + OZ'LOZ' LOZ. + LH+ LOOH + L' 1

Microgeographical Variation in Allozyme Frequencies in Avena barbata

Abstract: Microgeographical distribution of alleles of five enzyme loci and one morphological variant has been determined within populations of A. barbata occupying sites that are transitional between different vegetational zones. The results show that the spatial distribution of alleles is nonrandom and highly correlated with habitat in patterns that parallel the distribution of the same alleles in major climatic zones in California. It is concluded that the observed patterns of variation are best explained by Neo-Darwinian evolutionary models, in which selection plays a predominant role.

C-Type Virus associated with Gibbon Lymphosarcoma

Abstract: C-TYPE viruses have been established as the causal agents of leukaemia in murine and feline species and have been characterized1,2. C-type virus is also probably associated with fibrosarcoma in non-human primates3–6. To determine whether viruses with identical characteristics are associated with other neoplasms in simian species, we looked for C-type viruses in cases of leukaemia. A gibbon (Hylobates lar) with a disseminated tumour (later confirmed as lymphosarcoma) was made available to the Comparative Oncology Laboratory by Dr Malcolm Jones of the University of California, San Francisco Medical Center. The principal sites of involvement (lymph node, liver and bone marrow) were extensively overrun with massive neoplastic cells, which were predominantly prolymphocytic forms. Electron microscopy revealed C-type particles identical to those observed in vitro in sections from lymph nodes, liver, spleen and bone marrow.

Patterns of Genetic Differentiation in the Slender Wild Oat Species Avena barbata

Abstract: Allozyme frequencies at five enzyme loci were determined for 14 California populations of Avena barbata, a species introduced to California from the Mediterranean Basin during the colonization of North America. Allelic frequencies at these loci were also determined in Mediterranean collections of this species. The pattern of divergence of the California populations from the ancestral gene pool was not random and was strongly correlated with environment; thus, the pattern is not in accord with the hypothesis that most electrophoretically detectable variants are adaptively neutral. Rates of gene substitution in California were also not in accord with the neutrality hypothesis. The observations are, however, compatible with predictions of Neo-Darwinian evolutionary theory. We interpret these observations to indicate that natural selection plays a major role in determining the unique patterns of distribution of genetic variability in the slender wild oat in California.

Abandoned Larvacean Houses: A Unique Food Source in the Pelagic Environment

Abstract: Observations made by using conventional scuba techniques reveal that abandoned larvacean houses serve as food sources for marine, planktonic copepods. Techniques have been developed for photographing these houses in the field for the first time. The abundance of larvacean houses in the open ocean indicates that they are important in pelagic food webs and as a source of particulate organic matter.

Trends in general systems theory

Abstract: easily the most intensive and carefully documented commentary upon Weber's methodological writings to appear in English; it contains some useful material upon the philosophical background to Weber's essays-a background which has generally been only poorly known by English-speaking writers; it refers in detail to essays which have remained untranslated, notably the critiques of Roscher and Knies; and, finally, it can serve as a helpful interpretative aid for the reader who may be at times-or frequently-baffled by the turgid density and the less than elegant literary style of the originals. But I also have some reservations about the usefulness of the author's endeavours.

Nitrogen fixation in clear lake, california. i. seasonal variation and the role of heterocysts1

Abstract: The annual contribution of N2 fixation to Clear Lake in 1970 was about 550 tonnes, 500 Mg (megagrams) or 18 kg ha−1, 43% of the lake’s yearly nitrogen inflow. Biological N2 fixation can provide the nitrogen for almost half the blue-green algal standing crop during blooms and is implicated as the main cause of large algal nuisance blooms on this lake. The large quantity of nitrogen fixed may be typical for large, shallow, cyanophyceandominated lakes. A sustained spring peak of fixation was associated with a simultaneous bloom of Aphanizomenon flos-aquae in all three basins, an autumn peak with an ephemeral bloom of Anabaena circinalis occurring at a different time in each basin. A stepwise multiple regression analysis showed that fluctuations in N2 fixation were best described by variations in heterocysts, quantities of blue-green algae, PO4-P, NO3-N, and temperature. Annual rates of N2 fixation were correlated with the proportion of heteroeysts to vegetative cells in Aphanizomenon and with total number of heterocysts in Anabaena. Previous nitrogen budgets for Clear Lake have shown a large excess of nitrogen in outflow over inflow, which is accounted for by the levels of N2 fixation measured.

Obfuscation of the Activity of Antifungal Antimicrobics by Culture Media

Abstract: The potential of six culture media in current use for antagonism of the antifungal activity of amphotericin B, 5-fluorocytosine, and clotrimazole was assessed by comparison with a totally defined, nutritionally adequate, well-buffered, synthetic amino-acid medium, SAAMF. Of the six conventional media, only one was a synthetic formulation; although it was nutritionally adequate, it was essentially unbuffered. The remaining five media were complex, undefined, and undefinable. All five undefined media were nutritionally adequate, two were modestly well buffered, but all nullified the activity of one or more of the three antimicrobics studied. The obfuscatory capacity of each medium was quantitated by determination of the absolute minimal inhibitory concentration (M'IC) of each antimicrobic for a strain of Candida albicans. With 5-fluorocytosine and clotrimazole, but not with amphotericin B, there was significant increase in M'IC values as incubation was continued. By adding (individually) pyrimidines and pyrimidine ribosides to SAAMF, it was shown that cytosine and uridine blocked expression of the anticandidal activity of 5-fluorocytosine. Meaningful data cannot be obtained from susceptibility testing of fungi in vitro unless the potential for interaction between antimicrobic and culture medium is recognized and compensated for, most expeditiously, through use of a totally defined culture medium.

Purification and site of synthesis of Aedes aegypti yolk proteins.

Abstract: The identity and site of synthesis of the yolk proteins of the mosquito Aedes aegypti were studied. Disc gel electrophoresis of freshly prepared egg yolk revealed a predominant protein (YP-1) which stained for bound lipid and carbohydrate. The molecular weight of the protein complex was estimated to be 2.7 × 105. It was present in vitellogenic females and absent in males and unfed females. Yolk Protein-1 was purified by Sepharose and DEAE column chromatography and represented 75% of the protein extractable from the egg. The lipids conjugated to YP-1 were identified as phosphatidyl choline, phosphatidyl ethanolamine and several steroids. The carbohydrate content was estimated as 10.5% with a phenol-sulfuric acid method, and 5.8% with an orcinol method. The site of yolk protein synthesis was determined using antibody to purified yolk to precipitate labeled yolk proteins from organ culture media. Only the fat body synthesized antibody precipitable material. Synthesis began five to six hours after the blood meal, reached a peak of activity by 20 hours and declined to low levels of synthesis by 72 hours. These data correlate well with endocrino-logical evidence indicating that egg development requires a hormonal factor from the head from four to eight hours after the blood meal.

Metabolism of Pyrimidines and Pyrimidine Nucleosides by Salmonella typhimurium

Abstract: The pathways by which uracil, cytosine, uridine, cytidine, deoxyuridine, and deoxycytidine are metabolized by Salmonella typhimurium are established. The various 5-fluoropyrimidine analogues are shown to exert their toxic effects only after having been converted to the nucleotide level, and these conversions are shown to be catalyzed by the same enzymes which similarly convert the natural substrates. Methods for isolating mutant strains blocked in various steps of metabolism of pyrimidine bases and nucleosides are described.

Studies on Agrobacterium tumefaciens: characterization of strains 1D135 and B6, and analysis of the bacterial chromosome, transfer RNA and ribosomes for tumor-inducing ability

Abstract: Agrobacterium tumefaciens strains 1D135 and B6 were characterized. Both strains formed circular, smooth, creamy, shiny colonies on rich medium. In the scanning electron microscope their morphologies were bacilliform rods which possessed 1 to 6 peritrichous flagella. The optimum growth temperature was 31·8±0·5 °C for strain 1D135 and 32·1±0·5 °C for strain B6. Generation times at 32 °C were 62 and 61 min for strains 1D135 and B6 respectively. Both strains possessed activities of d -glucoside-3-dehydrogenase, catalase, oxidase, urease, nitrate reductase and β-galactosidase. Both strains produced acid on basal medium with arabinose, cellobiose, fructose, galactose, lactose or salicin. The 70s ribosomal proteins of these two strains were identical in electrophoretic mobilities in 7·5% acrylamide-urea gels at pH 4·3. Crown-gall tumor-inducing activity was not found in preparations of 70 s ribosomes, and messenger, ribosomal or transfer RNA. Nor was tumor-initiating activity in the case of strain 1D135 associated with circular satellite DNA molecules. Furthermore, almost all preparations of the bacterial chromosome lacked tumor inducing activity. A few preparations of high molecular weight DNA induced crown-gall-like tumors. The implications of this finding are discussed.