Showing papers by "University of Georgia published in 1973"

The Osmotic Potential of Polyethylene Glycol 6000

Abstract: Osmotic potential (ψs) of aqueous solutions of polyethylene glycol 6000 (PEG-6000) was curvilinearly related to concentration. At given concentrations, ψs increased linearly with temperature. The effects of concentration and temperature on ψs of PEG-6000 solutions differ from those for most salts and sugars and apparently are related to structural changes in the PEG polymer. Measurements of ψs with thermocouple psychrometers are more negative than those with a vapor pressure osmometer, with the psychrometer probably giving the more nearly correct ψs for bulk solutions. An empirical equation permits calculation of ψs from known concentrations of PEG-6000 over a temperature range of 15 to 35 C. Viscometery and gravimetric analysis are convenient methods by which the concentrations of PEG-6000 solutions may be measured.

Improved Microtechnique for the Leptospiral Microscopic Agglutination Test

Abstract: A method for improving the original Galton microtechnique for detecting leptospiral antibodies has been developed. Simultaneous titrations were performed on 281 animal and human sera and 17 hyperimmune sera with the microscopic agglutination (MA) test and the improved microtechnique. Reproducibility of the improved microtechnique was determined independently on 65 animal sera by two laboratory sections. The results obtained by comparing positive test data from human and animal sera indicated that agreement between the original MA test and this new method exceeded 94%, whereas the original Galton microtechnique and the original MA test agreed in a maximum of 77% of the tests. This study indicates that the results obtained with the improved microtechnique are much more comparable to results obtained with the original MA test than are those obtained with the original Galton microtechnique.

Formate Dehydrogenase of Clostridium thermoaceticum: Incorporation of Selenium-75, and the Effects of Selenite, Molybdate, and Tungstate on the Enzyme

Abstract: The formation of the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase in Clostridium thermoaceticum is stimulated by the presence of molybdate and selenite in the growth medium. The highest formate dehydrogenase activity was obtained with 2.5 x 10(-4) M Na(2)MoO(4) and 5 x 10(-5) Na(2)SeO(3). Tungstate but not vanadate could replace molybdate and stimulate the formation of formate dehydrogenase. Tungstate stimulated activity more than molybdate, and in combination with molybdate the stimulation of formation of formate dehydrogenase was additive. Formate dehydrogenase was isolated from cells grown in the presence of Na(2) (75)SeO(2), and a correlation was observed between bound (75)Se and enzyme activity.

Fermentation of glucose, fructose, and xylose by Clostridium thermoaceticum: effect of metals on growth yield, enzymes, and the synthesis of acetate from CO 2

Abstract: Clostridium thermoaceticum ferments xylose, fructose, and glucose with acetate as the only product. In fermentations with mixtures of the sugars, xylose is first fermented, then fructose, and last, glucose. Fructose inhibits the fermentation of glucose, and this inhibition appears to be due to a repression of the synthesis of an enzyme needed for glucose utilization. Addition of metals to the culture medium increases the cell yield drastically from about 7 to 18 g per liter, and Y(glucose) values between 40 and 50 are obtained. According to the postulated pathways of the fermentation of glucose and synthesis of acetate from CO(2) by C. thermoaceticum, 3 mol of ATP are available as energy for growth. Thus a Y(adenosine 5'-triphosphate) of 13 to 16 is obtained. Because the normal Y(ATP) value is 10.5, this could mean that an additional source of ATP is available by an unknown mechanism. The addition of metals also increases the nicotinamide adenine dinucleotide phosphate-dependent formate dehydrogenase activity, the overall reaction ((14)CO(2) --> acetate), and the incorporation of the methyl group of 5-methyltetrahydrofolate into acetate. These reactions are catalyzed very efficiently by cells harvested in early growth, whereas cells obtained at the end of a fermentation have very low formate dehydrogenase activity and capacity to incorporate CO(2) into acetate. The following enzymes involved in the synthesis of acetate from CO(2) and in the metabolism of pyruvate are present in extracts of C. thermoaceticum: 10-formyltetrahydrofolate synthetase, 5,10-methenyltetrahydrofolate cyclohydrolase, 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methylenetetrahydrofolate reductase, phosphate acetyltransferase, and acetate kinase. These enzymes are not or are very little affected by the addition of metals to the growth medium. The amount of corrinoids in cells from early growth is low, whereas it is high in cells harvested late in growth. The opposite is found for the activity of delta-aminolevulinate dehydratase, which is high at the beginning of growth and low at the end.

13C/12C Ratio Changes in Crassulacean Acid Metabolism Plants

Abstract: 13C/12C ratios have been found in totally combusted leaves of Crassulacean acid metabolism plants to range from −14 to −33 δ 13C‰ compared with a limestone standard. Crassulacean acid metabolism plants apparently utilize both ribulose-1, 5-diphosphate carboxylase and phosphoenolpyruvate carboxylase to assimilate atmospheric CO2 and, depending on environmental conditions, have 13C/12C ratios indicative of either carboxylase or to any intermediate value. The degree of discrimination against 13C and the resultant 13C/12C ratio from the photosynthetically fixed CO2 is influenced by environmental conditions and is not a specific and fixed characteristic of a Crassulacean acid metabolism plant. Certain Crassulacean acid metabolism plants may shift their ratios as much as 17 δ 13C‰ in specific environments.

Medium for the isolation of Aeromonas hydrophila.

Abstract: A new differential medium, Rimler-Shotts, was tested with 109 isolates representing 13 genera of bacteria obtained from aquatic environments and animals. This medium was effective in presumptive identification of the strains of Aeromonas hydrophila examined, with 94% accuracy. Strains of Citrobacter which were hydrogen sulfide-variable could not be separated from A. hydrophila. This medium was designed to facilitate diagnosis of A. hydrophila infections in animals and humans.

Phosphoenolpyruvate Carboxykinase in Plants Exhibiting Crassulacean Acid Metabolism

Abstract: Phosphoenolpyruvate carboxykinase has been found in significant activities in a number of plants exhibiting Crassulacean acid metabolism. Thirty-five species were surveyed for phosphoenolpyruvate carboxykinase, phosphoenolpyruvate carboxylase, ribulose diphosphate carboxylase, malic enzyme, and malate dehydrogenase (NAD). Plants which showed high activities of malic enzyme contained no detectable phosphoenolpyruvate carboxykinase, while plants with high activities of the latter enzyme contained little malic enzyme. It is proposed that phosphoenolpyruvate carboxykinase acts as a decarboxylase during the light period, furnishing CO 2 for the pentose cycle and phosphoenolpyruvate for gluconeogenesis. Some properties of phosphoenolpyruvate carboxykinase in crude extracts of pineapple leaves were investigated. The enzyme required Mn 2+ , Mg 2+ , and ATP for maximum activity. About 60% of the activity could be pelleted, along with chloroplasts and mitochondria, in extracts from leaves kept in the dark overnight.

Trans-β-farnesene, Alarm Pheromone of the Green Peach Aphid, Myzus persicae (Sulzer)

Abstract: THE chemical structure of the repellent odour found in the cornicle secretion of the aphid M. persicae1 has been identified as trans-β-farnesene.

Reading and Sentence Completion by a Chimpanzee (Pan)

Abstract: Four studies revealed that a 2½-year-old chimpanzee (Pan), after 6 months of computer-controlled language training, proficiently reads projected word-characters that constitute the beginnings of sentences and, in accordance with their meanings and serial order, either finishes the sentences for reward or rejects them.

Genetic divergence in body size among experimental populations of drosophila pseudoobscura kept at different temperatures

Abstract: The body dimensions of many animals vary in a regular way with environmental temperature, and the several "ecogeographical rules" have been formulated to describe these situations (see Mayr, 1963, for a review). The rules are most often discussed for homeotherms, since a possible connection with conservation of body heat arises, but many organisms with no internal regulation of body temperature vary in a similar way (Ray, 1960; Lindsey, 1966). The morphological variation may be simply a phenotypic response to temperature, reflecting developmental plasticity, or it may be partly or wholly genetic. Genetic differences in morphology are established from comparisons among geographic strains reared under the same, or nearly the same, conditions. The probable role of selection in producing the genetic differences is inferred from a correlation of genetic variation in morphology with environmental variation in temperature. Particularly for poikilotherms such as insects, a physiological basis for selection by environmental temperature or its correlates is often not apparent. Genetic variation in morphology, as measured by such characters as wing and thorax length, has been recorded for four Drosophila species. Stalker and Carson (1947) found that wing length in D. robusta decreased with mean annual temperature of the localities at which collections were taken, while thorax length varied in the opposite direction. Prevosti (1955) and Misra and Reeve (1964) showed a decrease in both wing length and thorax length with mean annual temperature for populations of D. subobscura. Tantawy and Mallah (1961) found that wing length and thorax length were higher in strains of D. melanogaster from cooler areas within the Middle East. Wing length is an excellent index of body size in D. pseudoobscura (Sokoloff, 1966); although it varies among populations, there is no correlation with latitude or mean annual temperature (Sokoloff, 1965; Anderson, 1968). In nature, of course, temperature is only one of many factors which influence selection for body size, and the confounding effects of other selective factors may obscure the individual effect of temperature. That discernible clines exist at all is a clear indication of the importance of temperature. Laboratory populations maintained at different temperatures provide a means of assessing the selective effects of temperature on body size with less complication from other environmental factors. Anderson (1966) studied experimental populations of D. pseudoobscura which were kept for six years at 16, 25, and 27 C, two replicate populations being maintained at each temperature. After one and a half years there was no evidence for divergence in body size, as measured by wing length, but at six years a striking divergence was evident, the populations kept at 16 C having become genetically determined for much larger size than those kept at 25 and 27 C. Temperature was clearly a major environmental difference among these populations, and the similarity of results for the replicate populations at each temperature argues against a chance divergence to larger size at the lower temperature and smaller size at the higher temperatures. Thus the morphological divergence among the experimental populations could well result from a selection similar to that which acts in

Sporicidal Properties of Hydrogen Peroxide Against Food Spoilage Organisms

Abstract: The sporicidal properties of hydrogen peroxide were evaluated at concentrations of 10 to 41% and at temperatures of 24 to 76 C. The organisms tested and their relative resistance at 24 C to 25.8% H2O2 were: Bacillus subtilis SA 22 > B. subtilis var. globigii > B. coagulans > B. stearothermophilus > Clostridium sp. putrefactive anaerobe 3679 > S. aureus, with “D” values of 7.3, 2, 1.8, 1.5, 0.8., and 0.2 min, respectively. Heat shocking spores prior to hydrogen peroxide treatment decreased their resistance. Wet spores were more resistant than dry spores when good mixing was achieved during hydrogen peroxide treatment. Inactivation curves followed first-order kinetics except for a lag period where the inactivation rate was very slow. Increasing the H2O2 concentration and the temperature reduced the lag period.

Isolation of Assimilatory- and Dissimilatory-Type Sulfite Reductases from Desulfovibrio vulgaris

Abstract: Bisulfite reductase (desulfoviridin) and an assimilatory sulfite reductase have been purified from extracts of Desulfovibrio vulgaris. The bisulfite reductase has absorption maxima at 628, 580, 408, 390, and 279 nm, and a molecular weight of 226,000 by sedimentation equilibrium, and was judged to be free of other proteins by disk electrophoresis and ultracentrifugation. On gels, purified bisulfite reductase exhibited two green bands which coincided with activity and protein. The enzyme appears to be a tetramer but was shown to have two different types of subunits having molecular weights of 42,000 and 50,000. The chromophore did not form an alkaline ferrohemochromogen, was not reduced with dithionite or borohydride, and did not form a spectrally visible complex with CO. The assimilatory sulfite reductase has absorption maxima at 590, 545, 405 and 275 nm and a molecular weight of 26,800, and appears to consist of a single polypeptide chain as it is not dissociated into subunits by sodium dodecyl sulfate. By disk electrophoresis, purified sulfite reductase exhibited a single greenish-brown band which coincided with activity and protein. The sole product of the reduction was sulfide, and the chromophore was reduced by borohydride in the presence of sulfite. Carbon monoxide reacted with the reduced chromophore but it did not form a typical pyridine ferrohemochromogen. Thiosulfate, trithionate, and tetrathionate were not reduced by either enzyme preparation. In the presence of 8 M urea, the spectrum of bisulfite reductase resembles that of the sulfite reductase, thus suggesting a chemical relationship between the two chromophores.

Isolation of a new pigment, desulforubidin, from Desulfovibrio desulfuricans (Norway strain) and its role in sulfite reduction.

Abstract: A new pigment, desulforubidin, that has sulfite reducing activity, has been purified from extracts of the Norway strain of Desulfovibrio desulfuricans, which lacks desulfoviridin.

Parents and peers: Socialization agents in the coital behavior of young adults∗

Abstract: In spite of the plethora of books, films and talk about sex, comparatively little is known about the interrelations between sexuality and socialization (Gagnon 1966) It is true that the patterning of premarital sexual behavior has been traced to such factors as differences in social class, religiosity and irreligiosity differential sex role conditioning, peer reference groups, and conservatism and liberalism (Kinsey et al, 1953; Locke, 1951; Kanin and Howard, 1958; Reiss, 1967; and Mirande, 1968); nevertheless there has been little closure in regard to the long range effects of various socializing agents upon the premarital sexual behavior of adolescents and young adults In the absence of any general theory, there have been numerous assumptions upon which sex problem-oriented professionals have operated For example some family counselors view premarital coitus (especially on the part of adolescent females) as an 4'acting out' of aggression and anxieties which have been generated within family interaction (Ackerman, 1 958; Friedman et al, 1 970) Others, as for instance some family life specialists hold that early adolescent experiments in coital activity often are due to ignorance and misinformation about sex Operating on this assumption, many sex educators believe that an adequate sex education, especially if it is augmented by trained parentsv may reduce the need for early coital experimentation (Calderone, 1965; Gadpaille, 1970) Yet another assumption has been made by some who have called attention tO the "exposure factor' within the contemporary dating and courtship systems For example, many writers have deplored, especially for young teens, the American dating arrangement known as "going steady" The implicit idea behind this proscription is the suspicion that greater exposure to intimate male-female interaction

The Role of Weather Variables and Flight Direction in Determining the Magnitude of Nocturnal Bird Migration

Abstract: Autumn nocturnal bird migration was investigated at two stations in the southeastern United States by means of Weather Surveillance Radar (WSR—57) and visual observations. Multivariate analyses were used to examined the influence of environmental variables on the night—to—night magnitude of migration. Landbirds selectively flew with the wind, regardless of its direction or speed. As a result, they frequently migrated in seasonally inappropriate directions. The volume of migration varied by several orders of magnitude from night to night, but southward flights averaged about five times larger than those in other directions. This implies that the birds employed some selection in terms of the weather conditions under which they initiated migratory flights. Multivariate analyses showed that wind direction, 24—hr change in temperature, and an index of the synoptic weather situation accounted for 5.2% of the night—to—night varaibility in the magnitude of passerine migration. Migration volume was also related to the passage of cold fronts. Migations were heavier in northerly winds, falling temperatures, and the anticyclonic weather that usually prevails shortly after the passage of a cold front. The efficiency of downwind flight is enhanced by the facts that average winds blow roughly in the migratory directions of the birds and that the birds show behavioral selection in terms of the wind directions and synoptic weather situations in which they initiate migration. Night—to—night variations in migration density can be accounted for on the basis of interactions between the circadian nature of Zugunruhe, the energetic state of the bird, and the direct influence of weather on the initiation of migratory flights.

Evidence for similar biochemical requirements for bioluminescence among the coelenterates.

Abstract: We present evidence that the chemical requirements among all the bioluminescent coelenterates that have been examined are very similar or identical to those already described for Renilla by Cormier and associates Components required for luminescence in Renilla were also found in a number of bioluminescent coelenterates examined such as Aequorea, Obelia, Cavernularia, Ptilosarcus, Stylatula, Acanthoptilum, Parazoanthus and Mnemiopsis Depending on the organism these include one or more of the following: luciferyl sulfate, luciferase, and luciferin sulfokinase These isolated components were found to be indistinguishable from those found in Renilla as evidenced by their reactivity in the Renilla bioluminescent system, by the spectral characteristics of the isolated luciferyl sulfates, by the molecular weights of the luciferases, and by the colors of the bioluminescence produced in vitro

Application and implementation

Abstract: Organizations are in constant interaction with their environment. This phenomenon has been termed in the literature as the environment-organizational interface. An organization acquires information concerning changes in its environment via some scanning system. This paper presents the results of an empirical investigation of the scanning process. The relationships of scanning to different environmental states is discussed and various propositions advanced. Different environmental states (stable versus dynamic) are moderated by the determinants of hierarchical levels and functional specialties in the firm.

The Physiology of Sulphate-Reducing Bacteria

Abstract: Publisher Summary The chapter discusses the physiology of sulphate-reducing bacteria. The chapter presents an account of their ecology and economic activities as relevant to the subject as their multiplication can have considerable ecological and economic consequences, and since these are due to their special physiology, in particular, the production of hydrogen sulphide. The sulphate-reducing bacteria form a physiologically distinctive group of anaerobic bacteria, their oxidative metabolism being based, not on fermentation, but on the reduction of sulphate or certain other inorganic sulphur compounds. Their physiology has broad analogies with that of the nitrate-reducing bacteria (denitrifying bacteria), but they are all exacting anaerobes and no examples of facultative aerobes are known. Some representatives of the group are capable of growth by non-respiratory processes involving dismutation of substrates, such as pyruvate, fumarate, or choline. Even when reducing sulphate, these organisms are completely unable to oxidize their carbon compounds, such as fatty acids; usually acetic acid plus carbon dioxide are the normal end products of carbon metabolism. The present chapter brings up to date all those publications on this group of bacteria, which had come to the author's attention by early 1972. Reviews of related subjects that have been published during this period, and which makes reference to these bacteria reviewing the general metabolism of sulphur bacteria. The chapter also discusses the chemical and biochemical activities of these bacteria.

Cell wall composition and synthesis via Golgi-directed scale formation in the marine eucaryote, Schizochytrium aggregatum, with a note on Thraustochytrium sp.

Abstract: Cell walls of Schizochytrium aggregatum and Thraustochytrium sp. were mechanically isolated and subjected to chemical analysis. On a dry weight basis the cell walls contain 21–36% carbohydrate and 30–43% protein. The principal sugar (>95%) of the Schizochytrium wall is l-galactose, while the Thraustochytrium cell wall contains l-galactose, d-galactose and xylose with l-galactose predominating. Ultrastructurally the cell walls of both organisms consist of a laminated structure which yields thin, flexible, nearly circular scales (0.5–1.1 μ in diameter) upon sonic disintegration. Structures presumed to be developing wall scales are found within cisternae of the Golgi apparatus in both organisms. The chemical composition and method of formation of the cell wall in these two protists is distinctly different from that found in the Saprolegniales (Oomycetes), the group with which these organisms have hitherto been aligned.

Alkylpyrazine alarm pheromones in ponerine ants.

Abstract: The mandibular gland secretions of the ponerine ants Odontomachus hastatus, O. clarus, and O. brunneus contain alkylpyrazines. These compounds, 2,5-dimethyl-3-isopentylpyrazine in O. hastatus and O. clarus, and 2,6-dimethyl-3-pentyl-, -butyl-, -propyl-, and -ethyl-pyrazines in O. brunneus, have previously not been found as animal natural products. These compounds function as powerful releasers of alarm behavior for Odontomachus workers and are probably also utilized as defensive compounds.

Flux density for ray propagation in geometrical optics

Abstract: A general formula is derived that specifies the illumination (flux density) over an arbitrary receiver surface when light rays are reflected by or refracted through a curved surface. The direction of the deflected ray and its intersection with the receiving surface, used with the equation for the surfaces, lead to a transformation that maps an element of deflecting area onto the receiving area, by means of the jacobian determinant. A formula for the flux density along a ray path follows as a special case. An equation for the caustic surface is obtained from the latter. As an example radiation flux-density contours are calculated for a plane wave reflected from a sphere. Flux density and the caustic surface are calculated for a plane wave reflected onto a plane from a concave spherical lens and also for a plane wave refracted onto a plane through a hemisphere.