117 results for 1980, ResearchCommons@Waikato

  • Carbon dioxide exchange in lichens: Relationship between the diffusive resistance of carbon dioxide and water vapour

    Green, T.G. Allan; Snelgar, W.P. (1982)

    Journal article
    University of Waikato

    Gaseous diffusion resistances for carbon dioxide and water vapour, thallus water content and thallus water potential were experimentally determined on species of the Stictaceae. The diffusion resistance to water loss was high only at low water contents and correlated closely with thallus water potential. Carbon dioxide diffusion resistances, however, were high at both low and high water contents and, even at medium water contents, were still an order of magnitude greater than the water resistance. These results indicate that carbon dioxide and water vapour exchange occur by different pathways in these lichens. Consequently it is suggested that the lichens have structural adaptations which separate the functions of water uptake, water storage and carbon dioxide exchange.

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  • Further nomenclature and chemical notes on Pseudocyphellaria in New Zealand

    Galloway, D.J.; James, P.W.; Wilkins, Alistair L. (1983)

    Journal article
    University of Waikato

    Nomenclatural notes on the following taxa are provided: Pseudocyphellaria billardierii, P. carpoloma, P. faveolata, P. rufovirescens and P. subvariabilis. Detailed chemical profiles are given for all described species of Pseudocyphellaria in New Zealand. Pseudocyphellaria ardesiaca, P. degelii, P. durietzii, P. fimbriata, P. fimbriatoides, P. gretae, P. knightii, P. maculata and P. sericeofulva spp. nov. are described for the first time.

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  • Motility of the reticulum and rumen of sheep given juice-extracted pasture

    McLeay, Lance M.; Kokich, D.C.; Hockey, H-U.; Trigg, T.E. (1982)


    University of Waikato

    1. Sheep were fed on different diets of juice-extracted herbage to determine what effect juice-extraction had on reticulo-rumen motility. 2. The frequency of A and B sequences of contraction of the reticulo-rumen were recorded during eating, rumination and inactivity for continuous periods of 24–72 h by using integrated electromyograms obtained from electrodes implanted in the musculature of the reticulum and cranial dorsal rumen. 3. Animals were fed on herbage in which approximately 200 g/kg dry matter had been removed in juice extracted from ryegrass (Lolium perenne), white clover (Trifolium repens), mixed ryegrass–white clover and lucerne (Medicago saliva). 4. Over all the frequency of A sequences of contraction did not differ in animals fed on pressed herbage or the unpressed material from which it was derived, although it was slower during rumination on some of the pressed material. In contrast, the frequency of B sequences was higher on the pressed material. The frequencies of contraction of A and B sequences in animals fed on pressed herbage was related to the activity of the animals in the order eating > rumination > inactivity. 5. Changes in reticulo-rumen motility due to juice extraction were small and the frequencies of A and B sequences of contraction in sheep fed on pressed herbage were in the range encountered in ruminants consuming more conventional foods.

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  • Social change, migration and pregnancy intervals

    Pool, Ian; Sceats, Janet E.; Hooper, A.; Huntsman, J.; Pummer, E.; Prior, I. (1987)

    Journal article
    University of Waikato

    Maternity histories from residents of a Pacific Island society, Tokelau, and migrants to New Zealand, are analysed using life table techniques. Inter-cohort differentials in patterns of family formation were found in the total Tokelau-origin population. The process of accelerated timing and spacing of pregnancies was more pronounced among migrants who tended to marry later, be pregnant at marriage, have shorter inter-pregnancy intervals at lower parities and to show evidence of family limitation occurring at higher parities. These results point to the significance of changing patterns of social control on strategies of family building.

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  • Microprocessor-based digital correlator

    Thomas, John C.; Lum, Y.T.; Kennett, David (1983-10)

    Journal article
    University of Waikato

    We describe the design, construction, and operation of a low-cost, microprocessor-based digital correlator. The device has 128 channels, operates in either the single clipping or single scaling mode, and allows selection of the sample interval with 2-digit precision over the range 100 ns to 9.9 s. The device can be operated in the autocorrelate or cross-correlate mode and may easily be expanded to more than 128 correlation channels.

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  • Isolation of anaerobic, extremely thermophilic, sulphur metabolising archaebacteria from New Zealand hot springs

    Patel, B.K.C.; Jasperse-Herst, P.M.; Morgan, Hugh W.; Daniel, Roy M. (1986)

    Journal article
    University of Waikato

    Enrichments of New Zealand geo-thermal samples, initiated in anaerobic sulphur-containing media and incubated at temperatures above 85°C, yielded rod and coccal shaped organisms which possessed archaebacterial characteristics. Pure cultures were isolated and characterised. Five of the seven isolates, which were rod-shaped organisms and did not have an obligate requirement for sulphur respiration, were similar to Ther-moproteus sp. but had more neutral pH optima for growth. Three of these five Thermoproteus sp. were obligate heterotrophs, which has not previously been reported. The two coccal isolates had an obligate requirement for sulphur as an electron acceptor and were similar to Desulfurococcus sp. but again with more neutral pH optima for growth.

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  • The industrial potential of enzymes from extremely thermophilic bacteria

    Daniel, Roy M.; Cowan, Don A.; Morgan, Hugh W. (1981)

    Journal article
    University of Waikato

    The thermal regions of the central North Island of New Zealand are some of the most extensive in the world. In addition, they are readily accessible and contain a diversity of ecological habitats, including a large number at 100°C. These areas are regarded as an important tourist attraction, and as a source of geothermal power, It is now clear that they also contain an important and unique genetic resource.

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  • Thermonema lapsum gen. nov., sp. nov., a Thermophilic Gliding Bacterium

    Hudson, J. Andrew; Schofield, Karin M.; Morgan, Hugh W.; Daniel, Roy M. (1989)

    Journal article
    University of Waikato

    We previously reported the isolation of five strains of a thermophilic gliding organism. These strains are described here as a new genus and species, Thermonema lapsum. The isolates can be readily distinguished from other thermophilic gliding bacteria as they are apparently unicellular aerobic filaments that grow optimally at 60°C. Their cell walls are similar in ultrastructure to those of gram-negative cells, but they are susceptible to penicillin G. Our isolates can be grown on a fully defined medium containing amino acids. Oxidation-versus-fermentation tests indicate that deamination takes place. The type strain, strain 23/9, has been deposited with the American Type Culture Collection as strain ATCC 43542.

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  • Caldolase, a chelator-insensitive extracellular serine proteinase from a Thermus spp.

    Saravani, G.A.; Cowan, Don A.; Daniel, Roy M.; Morgan, Hugh W. (1989)

    Journal article
    University of Waikato

    An extracellular alkaline serine proteinase from Thermus strain ToK3 was isolated and purified to homogeneity by (NH4)2SO4 precipitation followed by ion-exchange chromatography on DEAE-cellulose and QAE-Sephadex, affinity chromatography on N alpha-benzyloxycarbonyl-D-phenylalanyl-triethylenetetraminyl-Sepha rose 4B and gel-filtration chromatography on Sephadex G-75. The purified enzyme had a pI of 8.9 and an Mr determined by gel-permeation chromatography of 25,000. The specific activity was about 37,700 proteolytic units/mg with casein as substrate, and the pH optimum was 9.5. Proteolytic activity was inhibited by low concentrations of di-isopropyl phosphorofluoridate and phenylmethanesulphonyl fluoride, but was unaffected by EDTA, EGTA, o-phenanthroline, N-ethyl-5-phenylisoxazolium-3'-sulphonate, N alpha-p-tosyl-L-phenylalanylchloromethane, N alpha-p-tosyl-L-lysylchloromethane, trypsin inhibitors and pepstatin A. The enzyme contained approx. 10% carbohydrate and four disulphide bonds. No Ca2+, Zn2+ or free thiol groups were detected. It hydrolysed several native and dye-linked proteins and synthetic chromogenic peptides and esters. The enzyme was very thermostable (half-life values were 840 min at 80 degrees C, 45 min at 90 degrees C and 5 min at 100 degrees C). The enzyme was unstable at low ionic strength: after 60 min at 75 degrees C in 0.1 M-Tris/acetate buffer, pH 8, only 20% activity remained, compared with no loss in 0.1 M-Tris/acetate buffer, pH 8, containing 0.4 M-NaCl.

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  • Very stable enzymes from extremely thermophilic archaebacteria and eubacteria

    Bragger, J.M.; Daniel, Roy M.; Coolbear, Tim; Morgan, Hugh W. (1989)

    Journal article
    University of Waikato

    Thirty-six thermophilic archaebacteria and nine extremely thermophilic eubacteria have been screened on solid media for extracellular amylase, protease, hemicellulase (xylanase), cellulase, pectinase and lipase activities. Extracellular enzymes were detected in 14 archaebacteria belonging to three different orders. Twelve of these were able to degrade starch and casein and the two Thermofilum strains were able to degrade starch, xylan and carboxymethylcellulose. Three of the eubacteria could degrade only starch. The other six (including four Thermotoga strains) all had activity against starch, xylan and carboxymethylcellulose, and one also had activity against casein. Some of the amylolytic archaebacteria released α-glucosidase, β-glucosidase, amylase and transglucosylase activities into liquid media containing starch or maltose. Thermotoga strain FjSS3B.1 released amylase, xylanase, cellulase and β -glucosidase activities into the medium when grown in the presence of substrates. When the partially purified enzymes from Thermotoga and some of the archaebacteria were compared with known thermostable enzymes the majority were found to be the most thermostable of their type. The β-glucosidase, xylanase and cellulase from Thermotoga and two -glucosidases, a β-glucosidase, an amylase and a pullulanase from archaebacteria all have half-lives of at least 15 min at 105°C.

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  • A cell-associated oligo-1,6-alpha-glucosidase from an extremely thermophilic anaerobic bacterium, Thermoanaerobium Tok6-B1.

    Plant, Adrian R.; Parratt, S.; Daniel, Roy M.; Morgan, Hugh W. (1988)

    Journal article
    University of Waikato

    Cell-associated oligo-1,6-alpha-glucosidase (EC 3.2.1.10) was isolated from Thermoanaerobium Tok6-B1 grown on starch-containing medium. Activity was purified 11.4-fold by salt precipitation, gel filtration, hydroxyapatite and anion-exchange chromatography. Molecular mass was determined as 30,000 by SDS/polyacrylamide-gel electrophoresis and 33,000 by analytical gel filtration. The probable order of specificity was p-nitrophenyl-alpha D-glucose greater than-isomaltose greater than-isomaltotriose greater than-panose greater than-nigerose and no activity was shown against malto-oligosaccharides, melezitose, melibiose, raffinose, cellobiose, sophorose, gentiobiose, lactose, pullulan, dextran or amylose. The optima for activity and stability were between pH 5.6 and 7.0 and the half-life at pH 6.5 was 1000 min at 70 degrees C and 20 min at 76 degrees C. Activity was stabilized by substrate, Mg2+, Mn2+ and Ca2+, but was destabilized by Zn2+ and EDTA. N-Ethylmaleimide, glucose and 1-O-methyl-alpha D-glucose were inhibitory but 1-O-methyl-beta D-glucose stimulated activity. The activation energy (Ea) was 109 kJ/mol.

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  • Distribution of reverse gyrase in representative species of eubacteria and archaebacteria

    Collin, R.G.; Morgan, Hugh W.; Musgrave, D.R.; Daniel, Roy M. (1988)

    Journal article
    University of Waikato

    Reverse gyrase is a topoisomerase which positively supercoils closed circular plasmid DNA. Reverse gyrase activity is restricted to the thermoacidophilic group of archaebacteria. Thermophilic methanogens and eubacteria and all mesophilic organisms screened had no reverse gyrase activity. The result supports the deep phylogenetic divergence in archaebacterial evolution.

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  • Proteases from extreme thermophiles

    Coolbear, Tim; Daniel, Roy M.; Cowan, Don A.; Morgan, Hugh W. (1988)

    Journal article
    University of Waikato

    Extremely thermophilic bacteria are those that grow optimally at 65 ℃ or higher. Comparative data are presented on extracellular proteases from two extremely thermophilic eubacteria and one extremely thermophilic archaebacterium. The eubacteria were a Bacillus isolate (protease unnamed) and a Thermus isolate (protease named caldolysin) with optimum growth temperatures of 65 ℃ and 75 ℃, respectively. The archaebacterium was a Desulfurococcus isolate (protease named archaelysin) with an optimum growth temperature of 88 ℃.

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  • Anaerobic growth and denitrification by Rhizobium japonicum and other rhizobia

    Daniel, Roy M.; Smith, I.M.; Phillip, J.A.D.; Ratcliffe, H.D.; Drozd, J.W.; Bull, A.T. (1980)

    Journal article
    University of Waikato

    The product of nitrate respiration in Rhizobium japonicum and a number of other rhizobia capable of anaerobic growth utilizing nitrate was N2O. No N2 or ammonia was formed. Nitrate reduction was linked to ATP formation during anaerobic but not during aerobic growth. Free-living rhizobia may remove fixed nitrogen from the soil by denitrification.

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  • Energy coupling in soybean bacteroids

    Ratcliffe, H.D.; Drozd, J.W.; Bull, A.T.; Daniel, Roy M. (1980)

    Journal article
    University of Waikato

    Biological dinitrogen fixation by Rhizobium spp. in the root nodules of leguminous plants such as soybean is of considerable agronomic importance. Biological dinitrogen fixation is ATP- and reductant-dependent; between 12 and 30 mol of ATP are required per mol of dinitrogen reduced [1]. All free-living rhizobia are aerobic although some strains will also grow anaerobically with nitrate as the terminal electron acceptor [2] ; ATP and reductant are generated during the oxidation of an exogenously supplied carbon source. In the bacteroids within the root nodule the exogenous carbon source (photosynthate) is derived from photosynthetic CO₂ fixation by the host plant. The identity of the carbon source(s) oxidised by the bacteroids in vivo has not yet been confirmed although sucrose is the major photosynthetic product translocated to the root nodules [3]. As dinitrogen fixation represents a drain on the photosynthetic supply [4,5] and since the supply of photosynthate is probably one of the major factors that limits dinitrogen fixation in the Rhizobium-legume symbiosis [6] a high efficiency of energy coupling within the bacteroids would minimise the amount of photosynthate required to be oxidised to supply the ATP and reductant necessary for dinitrogen fLxation. The number of sites of oxidative phosphorylation in the bacteroids is unknown although Laane et al. [7,8] have found respiration induced membrane energisation in R. leguminosarum bacteroids. We investigated both the capability of the bacteroids to oxidise a variety of carbon sources and the number of sites of oxidative phosphorylation (proton-translocating loops) in the bacteroids.

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  • The purification and some properties of a stereospecific D-asparaginase from an extremely thermophilic bacterium, Thermus aquaticus.

    Guy, G.R.; Daniel, Roy M. (1982)

    Journal article
    University of Waikato

    A specific D-asparaginase was isolated and crystallized from Thermus aquaticus strain T351. It is present in larger amounts than the L-asparaginase. The enzyme has a molecular weight of 60 000, an isoelectric point of 4.8 and a Km of 2 mM. It has 6 disulphide bonds/molecule, and a histidine residue at the active site. It is inhibited by keto acids and by high salt concentrations.

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  • Anaerobic growth, nitrate reduction and denitrification in 46 rhizobium strains

    Daniel, Roy M.; Limmer, A.W.; Steele, K.W.; Smith, I.M. (1982)

    Journal article
    University of Waikato

    A total of 46 rhizobial strains were assessed for anaerobic growth in the presence of nitrate, and, using the criteria of nitrate utilization and nitrous oxide and nitrogen production, for their ability to denitrify. Nitrite production was also measured. Half of the strains were denitrifiers: these included all five strains of R. meliloti tested which produced N2 from nitrate and most of the slow-growing rhizobia, but none of the 14 strains of R. trifolii.

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  • A correlation between protein thermostability and resistance to proteolysis.

    Daniel, Roy M.; Cowan, Don A.; Morgan, Hugh W.; Curran, M.P. (1982)

    Journal article
    University of Waikato

    The loss of activity due to proteolysis of purified L-asparaginase and beta-galactosidase from different sources correlates with the thermal instability of the enzymes. A similar correlation is found when populations of soluble proteins from micro-organisms grown at different temperatures are compared for proteolytic susceptibility and thermal stability. It is proposed that there is a general correlation between the thermostability of proteins and their resistance to proteolysis.

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  • A soluble NADH dehydrogenase (NADH: ferricyanide oxidoreductase) from Thermus aquaticus strain T351.

    Walsh, K.A.; Daniel, Roy M.; Morgan, Hugh W. (1983)

    Journal article
    University of Waikato

    A soluble NADH dehydrogenase (NADH:ferricyanide oxidoreductase) has been obtained by simple disruption of cells of Thermus aquaticus strain T351, and purified. The enzyme is of low molecular mass, 50 000 Da, and displays many of the properties of the membrane-bound enzyme, including inhibition by both NADH and ferricyanide, and the same Km for ferricyanide. The enzyme contains 0.05 mol of FMN, 0.16 mol of labile sulphur and 2.2 mol of iron per mol of protein. The enzyme is inhibited by NAD and cupferron competitively with ferricyanide, and by ATP (but not ADP) competitively with NADH. The enzyme is particularly thermostable, having a half-life at 95 degrees C of 35 min. The effect of temperature on the molar absorption coefficient and the stability of NADH was determined.

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  • Effect of oxygen on the synthesis, activity and breakdown of the rhizobium denitrification system

    O'Hara, G.W.; Daniel, Roy M.; Steele, K.W. (1983)

    Journal article
    University of Waikato

    The synthesis, activity and breakdown of the denitrifying enzymes of Rhizobium japonicum, R. lupini and R. meliloti were found to be regulated by O₂. Nitrogen oxide reductases were present in anaerobically grown and symbiotic R. japonicum, but in the case of organisms that had been grown aerobically the enzymes were induced only after a period of incubation under anaerobic conditions. Activity of the denitrification system that had been induced in aerobically grown cells was inhibited by O₂. Denitrification by anaerobically grown cells and bacteroids was stimulated by 5% O₂. Air inhibited denitrification completely. Little loss of denitrifying activity was shown by cells incubated in 5% O₂, but cells incubated at 10% O₂ showed a rapid loss of denitrification activity.

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