Showing papers by "University College Cork published in 1983"
TL;DR: A heat-stable lipase was isolated from a shaken milk culture of Pseudomonas fluorescens strain AFT 36 by DEAE-chromatography and gel filtration in Sepharose 6B, which was very stable over the pH range 6–9 and relatively heat-labile in phosphate buffer in the temperature range 60–80 °C, where it was stabilized significantly by Ca2+.
Abstract: Aeration increased the growth and lipase production in milk by Pseudomonas fluorescens strain AFT 36, isolated from refrigerated bulk milk. A heat-stable lipase was isolated from a shaken milk culture of this microorganism by DEAE-chromatography and gel filtration in Sepharose 6B. The lipase-rich fraction from DEAE cellulose contained 3 lipases that were separated by gel filtration; only the principal lipase, which represented approximately 71% of total lipolytic activity, was characterized. The purified enzyme showed maximum activity on tributyrin at pH 8.0 and 35 degrees C; it had a Km on tributyrin of 3.65 mM and was inhibited by concentrations of substrate greater than approximately 17 mM. The enzyme was very stable over the pH range 6-9; it was relatively heat-labile in phosphate buffer in the temperature range 60-80 degrees C, where it was stabilized significantly by Ca2+. It was, however, very stable at 100-150 degrees C: the D values at 150 degrees C were approximately 22 s and 28 s in phosphate buffer and synthetic milk serum respectively; the corresponding Z values in the temperature range 100-150 degrees C were approximately 40 and approximately 42 degrees C and the Ea for inactivation were 7.65 X 10(4) J mol-1 and 6.97 X 10(4) J mol-1 respectively.
110 citations
TL;DR: It is concluded that the transcapillary escape rate of albumin is independently elevated by poor metabolic control, by hypertension and by microangiopathy.
Abstract: Available evidence indicates that poor metabolic control and raised blood pressure each accelerate the development of diabetic microangiopathy. Microangiopathy is associated with excess albumin deposition in capillary basement membranes and it has been suggested that increased extravasation of plasma constituents may lead to basement membrane thickening. We measured the transcapillary escape rate of albumin, an indicator of the rate of extravasation of intravascular albumin from the circulation per unit time, following intravenous injection of 125I-human serum albumin. We examined the independent effects on the transcapillary escape rate of albumin of non-ketotic poor metabolic control, hypertension and microangiopathy. We studied non-diabetic control subjects and diabetic patients, initially when in non-ketotic poor metabolic control and again when control had been improved. We also studied normotensive well-controlled diabetic patients without microangiopathy, normotensive well-controlled diabetic patients with microangiopathy, hypertensive well-controlled diabetic patients without microangiopathy and hypertensive well-controlled diabetic patients with microangiopathy. The transcapillary escape rate of albumin was similar in non-diabetic control subjects (5.5 +/- 0.7%/h) and in both Type 1 (5.3 +/- 1.2%/h) and Type 2 (5.1 +/- 0.6%/h) normotensive diabetic patients without long-term complications. During poor metabolic control the transcapillary escape rate of albumin was significantly higher than in non-diabetic subjects (8.8 +/- 0.8%/h and 5.5 +/- 0.7%/h respectively, p less than 0.01). With improved control values fell significantly to 6.3 +/- 0.9%/h (p less than 0.02), not significantly different from control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
75 citations
TL;DR: Developments in the application of starter culture systems in different countries are examined and show that significant process control and elimination of phage problems can be achieved.
Abstract: The use of mesophilic starter cultures, containing group N Streptococcus and Leuconostoc species, in the dairy industry is examined. Bacteriophage attack is identified as the main cause of culture inhibition and criteria used to select stable mixed-strain starter cultures and phage-insensitive defined strains are established. The key aspects of culture propagation and storage are highlighted, as well as bulk-culture protection based on physical exclusion of phage and the use of phage-inhibitory media. Developments in the application of starter culture systems in different countries are examined and show that significant process control and elimination of phage problems can be achieved.
61 citations
TL;DR: In this paper, two Hercynian duplexes are developed in Visean limestones in the Basse Normandie quarry, where the lower duplex exposes all the internal thrusts, a reference bed of chalky limestone, the roof and floor thrusts and the duplex tip.
57 citations
TL;DR: Progeny plants produced from single calli show a range of variation qualitatively similar to that previously reported for shoots produced from large numbers of different single protoplast derived calli, that is, intracallus variation appears similar to intercallus variation.
56 citations
TL;DR: Nine mutants within a 23 nucleotide sequence of the trpE gene of Salmonella typhimurium have been characterized and the possibility of such functional imbalance leading to frameshifting in these mutants is discussed.
Abstract: Nine mutants within a 23 nucleotide sequence of the trpE gene of Salmonella typhimurium have been characterized. trpE91, a mutant which is externally suppressible has a single base deletion. Eight (or nine) nucleotides upstream of this deletion, two independently isolated mutations have the same transversion. In combination with trpE91 these mutations lead to partial restoration of synthesis of anthranilate synthetase in the absence of external suppressors. In the transversion the sequence A CA is changed to A AA and this new sequence may be the site where frameshifting occurs to allow leakiness. Leakiness is displayed by two further mutants of the same sign as trpE91, and one of the opposite sign, in the absence of any base substitution or external suppressors. Specific sequences, e.g., UUUC, may be especially prone to frameshifting and this sequence is created at the site of the +1 frameshift mutant which displays leakiness. In the new reading frame generated by the two -1 frame leaky mutants, a tryptophan codon is encountered. Leakiness is necessarily detected in the absence of tryptophan and under these conditions there will be a shortage of charged tryptophan tRNA. The possibility of such functional imbalance leading to frameshifting in these mutants is discussed.
52 citations
TL;DR: A metalloproteinase isolated from a shaken milk culture of Pseudomonas fluorescens AFT 36 was very unstable in 0·1 m-phosphate buffer, pH 6·6, being completely denatured above 70 °C in 1 min, and at higher temperatures the enzyme, although susceptible to autolysis, is inactive.
Abstract: A metalloproteinase, isolated from a shaken milk culture of Pseudomonas fluorescens AFT 36 by chromatography in DEAE and CM-cellulose and Sephadex G-150, was very unstable in 0.1 M-phosphate buffer, pH 6.6, being completely denatured above 70 degrees C in 1 min. It was also unstable in a Ca-containing buffer (synthetic milk salts, SMS) between 50 and 60 degrees C (minimum at 55 degrees C), but stability was very high above 80 degrees C in this buffer. D-values were determined at 10 degrees C intervals in the range 70-150 degrees C in SMS from which a Z value of 31.9 degrees C and an Ea of 8.82 X 10(4) J mol-1 were calculated; the half-life at 150 degrees C was 9 s. Instability at 55 degrees C was due to autolysis as evidenced by gel electrophoresis, gel filtration and increase in 2,4,6-trinitrobenzenesulphonic acid-reactive amino groups. The extent of inactivation experienced at 80 degrees C was inversely related to the rate of heating to 80 degrees C, i.e. length of time spent in the neighbourhood of 55 degrees C. Addition of increasing concentrations of caseinate substrate reduced inactivation of the enzyme at 55 degrees C, presumably due to substrate binding. Attempts to stabilize the enzyme at 55 degrees C by addition of EDTA or by adjusting the reaction pH to 4.2, at which the enzyme has little proteolytic activity, were unsuccessful, although autolysis was prevented. Unlike the proteinase from Ps. fluorescens MC 60, AFT 36 proteinase did not inactivate itself on cooling to 55 degrees C from 80, 100 or 150 degrees C, but did regain autolytic activity on cooling to below 50 degrees C to an extent dependent on the duration of holding at the lower temperature. It is suggested that on heating to approximately 55 degrees C, a conformational change occurs which renders the enzyme susceptible to proteolysis by still active enzyme; at higher temperatures the enzyme, although susceptible to autolysis, is inactive; an active conformation is restored on cooling to below 50 degrees C.
41 citations
TL;DR: Evidence was obtained to show that the activity of NADH oxidase was not affected by several intermediates of carbohydrate metabolism, and its synthesis was regulated via induction by O2 with an overriding catabolite repression type control, when cells were grown at the expense of glucose.
Abstract: Hydrogen peroxide accumulated in aerated cultures of Streptococcus lactis C10, the amount depending on the sugar being utilized. When the energy source was galactose or (to a lesser extent) lactose or maltose, H2O2 reached autoinhibitory levels. With glucose, H2O2 reached levels which did not cause obvious inhibition, and then declined. Washed cell suspensions utilized several media ingredients including glucose, galactose and yeast extract as substrates for O2 uptake, but cell-free extracts utilized none of these. The only substrate which supported O2 uptake by cell-free extracts was NADH. The activity of NADH oxidase was not affected by several intermediates of carbohydrate metabolism. Evidence was obtained to show that its synthesis was regulated via induction by O2 with an overriding catabolite repression type control, when cells were grown at the expense of glucose.
33 citations
TL;DR: In the case of a vertical section constructed at an oblique angle to the transport direction, the bulk strain value obtained is a minimum and can be corrected to the true value of bulk strain in the perpendicular, vertical section by a simple trigonometric calculation.
31 citations
TL;DR: It is demonstrated that degenerative changes are extensively present in membranes that rupture prematurely, particularly before the onset of premature labour, and a role for plasminogen in membrane rupture is suggested.
31 citations
TL;DR: There was phenotypic variation in explant and cell cultures: grossly abnormal, albino and green, shoot-like and root-like structures either failed to root or establish and survive in soil but most surviving plants showed a range of character variability similar to the controls.
Abstract: Plants regenerated directly from potato stem explants and from callus derived from single potato stem callus cells were compared with plants from rooted lateral buds as controls. There was phenotypic variation in explant and cell cultures: grossly abnormal, albino and green, shoot-like and root-like structures either failed to root or establish and survive in soil but most surviving plants showed a range of character variability similar to the controls. Explant and cell culture-derived variation is discussed in relation to the improvement of specific characters in commercial potato cultivars.
TL;DR: The ultrastructure of pike peripheral blood cells, lymphocytes, thrombocytes, granulocytes, and monocytes is described and a preliminary investigation of the structure of the haemopoietic cells in the thymus, anterior kidney, and spleen was carried out.
Abstract: The ultrastructure of pike peripheral blood cells, lymphocytes, thrombocytes, granulocytes, and monocytes is described. At present there are no reliable criteria for differentiating between round thrombocytes and small lymphocytes of fish on a routine basis. At the ultrastructural level thrombocytes could be clearly differentiated from lymphocytes by cytoplasmic canals and vesicles, marginal microtubules, and large glycogen deposits. Electron microscopic identification of thrombocytes was confirmed by examining the ultrastructural features of a purified thrombocyte fraction. In addition, a preliminary investigation of the structure of the haemopoietic cells in the thymus, anterior kidney, and spleen was carried out.
TL;DR: In this article, the potential required to intiate oxidation of a platinum surface in aqueous media shows a variation of about 90, rather than 59 mV per unit change in solution pH.
TL;DR: Cloned segments of Rhizobium genomic DNA encoding sequences for cyclic AMP synthesis (Adenyl cyclase) were identified from a gene bank of R. meliloti and will be a useful tool in elucidating the role of cAMP in these agronomically important bacteria.
Abstract: Cloned segments of Rhizobium genomic DNA encoding sequences for cyclic AMP synthesis (Adenyl cyclase) were identified from a gene bank of R. meliloti. The cloned DNA weakly complemented Escherichia coli Δcya mutants, promoting the expression of adenyl cyclase activity and the accumulation of cAMP. The complemented Δcya clones were also capable of inducing a number of cAMP dependent carbon utilization operons but displayed an altered pattern of catabolite repression control. A common 5.4 Kb Bg/II DNA fragment, with internal EcoR1, BamH1 and PstI sites and inserted in different orientations was identified in the complementing recombinant plasmids. The identification of this DNA sequence will be a useful tool in elucidating the role of cAMP in these agronomically important bacteria.
TL;DR: In this article, an inviscid gas is contained in a tube which is closed at one end and is excited by an oscillating piston at the other end, and the evolution of the gas motion, from the initial rest state to the final periodic state, is examined.
Abstract: An inviscid gas is contained in a tube which is closed at one end and is excited by an oscillating piston at the other end. The motion of the gas is assumed to be one-dimensional and isentropic. The evolution of the gas motion, from the initial rest state to the final periodic state, is examined. The motion is characterised by a similarity parameter. It is shown how shocks form and are sustained within the resonant band, while outside the resonant band shocks form but decay to leave essentially the linear solution.
TL;DR: Investigation of the growth to flowering of approximately 1000 plants of 2 cultivars revealed insignificant variation from type, and storage of bud tips, buds and rooted shoots in vitro for up to one year is described, with regeneration of plants.
TL;DR: In this paper, cyclic α-diazoketones react with phenylsulphenyl chloride at room temperature to furnish α-chloro-α-(phenylthio)cycloalkanones, which undergo ready dehydrochlorination to α-(phenylonthio)-cycloenones when treated with triethylamine.
TL;DR: All but the extreme 5' end of a DNA copy of the bacteriophage MS2 lysis gene downstream of a lac-induced promoter on a multicopy plasmid was inserted, showing that phage coat protein is not required for the lytic process itself.
Abstract: We inserted all but the extreme 5′ end of a DNA copy of the bacteriophage MS2 lysis gene downstream of a lac -induced promoter on a multicopy plasmid. Upon induction, cells harboring this plasmid began to lyse, showing that phage coat protein is not required for the lytic process itself.
TL;DR: Low plasma copper concentration may influence normal human female fertility in infertile and fertile women and in women with secondary rather than primary infertility.
TL;DR: Citrate, oxalate and EDTA markedly reduced the [Ca+] in the milk and increased its ethanol stability by shifting the ethanol/pH profile to lower pH values.
Abstract: Fifteen polyvalent organic salts and acids increased, some very markedly, the heat stability of milk progressively with increasing concentration; acetate and mesaconic acid had no effect, and maleate caused destabilization. Citrate, oxalate and EDTA markedly reduced the [Ca+] in the milk and increased its ethanol stability by shifting the ethanol/pH profile to lower pH values. These additives ≥ 20 mmol/l prevented the coagulation of milk by rennet, but the other additives caused only slight increases in RCT.
Citrate, EDTA and oxalate disrupted casein micelles and would therefore not be suitable additives: however, the other acids and salts did not alter the appearance of the milk and might be recommended as suitable additives to improve the heat stability. In terms of the response to the level of Ca2+ and colloidal calcium phosphate in milk, there appeared to be a correlation between ethanol stability and rennet coagulation time.
Journal Article•
TL;DR: The implications of plant propagation via tissue culture and the potential for chemotherapeutants in the latter have been discussed, and the search for endogenous antiviral mechanisms in plants is explored.
Abstract: Publisher Summary This chapter discusses existing gaps in plant virus disease control where there is a commercial need for chemotherapeutants. The replication strategy of the main plant virus type is discussed and the relation between the plant virus and its host has been outlined as a background to a review of targets for chemical action, screening methods used by plant virologists, and results obtained. The chapter discusses selective aspects of the literature on antiviral benzimidazoles and their derivatives, ribavirin and plant hormones, comparing results obtained in animals and plants where appropriate. It also discusses the symptom suppression in plants by benzimidazole derivatives and of the search for endogenous antiviral mechanisms in plants. In conclusion, the implications of plant propagation via tissue culture and the potential for chemotherapeutants in the latter have been discussed.
TL;DR: In this paper, the 57 Fe Mossbauer spectra of related iron cluster carbides and nitrides were measured at liquid nitrogen temperatures and the isomer shift and quadrupole splitting parameters were reported.
TL;DR: In this paper, the authors present the results of an empirical investigation of the diffusion of the multidivisional form structure among a sample of large U.K. quoted companies.
TL;DR: In this article, the authors reported an unusual simultaneous increase in the cosmic-ray shower rate at two recording stations separated by 250 km, which was the only one of its kind detected in three years of observation.
Abstract: The authors report on an unusual simultaneous increase in the cosmic-ray shower rate at two recording stations separated by 250 km. The event lasted for 20 s. This event was the only one of its kind detected in three years of observation. The duration and structure of this event is different from a recently reported single-station cosmic-ray burst. The simultaneity of the coincident event suggests that it was caused by a burst of cosmic gamma rays. There is a possibility that this event may be related to the largest observed glitch of the pulsar in the Crab Nebula.
TL;DR: The data indicate, moreover, that the tryptophan prototrophs contain a duplication that extends at least from glpT to xyl, a region of greater than 30% of the Salmonella chromosome.
Abstract: Strains of Salmonella typhimurium that contain the aroC321 allele require phenylalanine, tyrosine, and tryptophan for growth but revert to tryptophan-prototrophy at high frequencies (about 10-4 per cell plated). The Trp+ derivatives remain auxotrophic for phenylalanine and tyrosine and are genetically unstable, in that they readily give rise to cells that require all three aromatic amino acids. On the basis of growth characteristics and genetic instability, it has been proposed that reversion to tryptophan-prototrophy in aroC321 strains occurs by genetic duplication. This paper provides genetic evidence in support of that hypothesis. The data indicate, moreover, that the tryptophan prototrophs contain a duplication that extends at least from glpT to xyl, a region of greater than 30% of the Salmonella chromosome. The aroC locus is found within the duplicated region, and aroC321/aroC321 merodiploids apparently grow as tryptophan prototrophs because of a genedosage effect.
TL;DR: In this article, the d.c. polarographic and cyclic and cathodic stripping voltammetric behavior of some primary, secondary and tertiary thioamides based on tetrahydroquinoline, is described.
TL;DR: In this paper, a blood plasma sample was spiked with flurazepam and its metabolites and diluted with water (1 + 1), after protein precipitation and protein removal, the residue was dissolved in the mobile phase for injection onto a reverse-phase LiChrosorb column.
TL;DR: Human amniochorion has been studied by indirect immunofluorescence using a monoclonal antibody to a monomorphic determinant of HLA-DR antigens and positive staining was noted only on significant numbers of large cells with irregular cytoplasmic processes in the mesenchymal connective tissue layer of the membranes.