Showing papers by "University College Cork published in 1973"

Proteolysis of β-casein in Cheddar Cheese

Abstract: β-Casein is highly resistant to proteolysis in Cheddar cheese. A decrease in NaCl concentration reduced its resistance, but even in the absence of salt the amount of proteolysis of β-casein was slight. Proteolysis in Cheddar cheese increased when the moisture levels were raised by adding water. The relative susceptibility of β-casein to proteolysis by rennin was reduced considerably when the concentration of a sodium caseinate solution was raised from 10 to 20%. Sequestering the Ca2+ by means of EDTA had no significant effect on proteolysis of β-casein. It would appear that the resistance of β-casein to proteolysis is due to the substrate rather than the enzyme and it is suggested that the reduced relative susceptibility to proteolysis is due to some concentration-dependent physical change in the casein molecule which renders the β-casein inaccessible. The salt concentration would also appear to influence this change.Cheddar-cheese flavour is largely independent of rennet concentration and it is possible to manufacture cheese of satisfactory quality using half-normal rennet levels.

Casein micelle structure: susceptibility of various casein systems to proteolysis.

Abstract: The susceptibility of the components of various caseinate systems (skim-milk, β-casein-depleted milks, colloidal phosphate-free (CPF) milk, sodium caseinate and isolated β-casein) to proteolysis was investigated. Isolated αs1- and β-caseins were quite susceptible to proteolysis, but their susceptibility decreased in heterogeneous soluble systems and even more so in heterogeneous aggregated systems. In skim-milk and β-casein-depleted milks only about 50% of both αs1- and β-casein was hydrolysable by high levels of rennin, and in CPF milk all αs1- and 70% of the β-casein was hydrolysable. It is suggested that about 50% of micellar β-casein is firmly fixed within the micelle and is unavailable for proteolysis, while the remainder can dissociate from the micelle on cooling and is then readily hydrolysable.The compatibility of the data with the various published models of the casein micelle is discussed, and a modification of Rose's (1969) model is proposed.

The N -acetyl neuraminic-acid content of the milk of various species

Abstract: Average N -acetyl neuraminic-acid (NANA) content of milk from cow, sheep, goat, mare, donkey and sow (about 10 samples from each species) was 17·7, 10·1, 6·4, 6·1, 12·0 and 64·0mg/100 ml, of which 14·2, 8·4, 3·2, 3·1, 5·0 and 53·7mg/100 ml respectively was in the casein fraction. The NANA content of casein showed marked species variation ranging from an average of 2·18 % for the sow to 0·09 % for the goat. About 28 % of the casein NANA of mare's milk was liberated in the fraction soluble in 12 % TCA by the action of rennin at pH 6·6 compared with 75 and around 100 % for donkey's and sow's milk respectively; about half the total NANA in the casein of cow's, sheep's and goat's milk was released under the same conditions.

Nonlinear resonant oscillations in open tubes

Abstract: A gas in a tube, one end of which is open, is driven by a periodic applied velocity or pressure at or near a resonant frequency. Damping is introduced into the system by radiation of energy through the open end. It is shown that shocks are possible at an open end and that there is a critical level of damping which ensures a continuous gas response for all frequencies. At the critical level the amplitude of the response is O (e 1/3 ), where e is the amplitude of the input, and it is bounded by the amplitude predicted by linear theory. There is agreement with the qualitative experimental results available.

A Structuro-functional classification of synovial articular units

Abstract: The articular units found in synovial joints can be classified structurally as modified or unmodified sellar, modified or unmodified ovoid. A fourfold functional classification can also be made in terms of the chordal, arcuate and rotatory motions (sensu medico) permitted or prevented at them. Each structural class corresponds to one and only one functional class. Two apparent exceptions are explained. The parts played by articular structure and by the musculature in determining the movement(s) at a joint are considered briefly.

The Social Survey Movement and Sociology in the United States

Abstract: This paper traces the development of the Social Survey movement in England and the United States, with particular emphasis on the latter, and also attempts to delineate the reciprocal influence it had upon American sociology. In looking at the history of this movement an attempt is made to show how it must be approached in terms of contemporary ideologies. Research of this kind was characterized not only by a previously absent concern with the understanding of the total community by empirical means, but also by a search for the source of social problems which looked not to the individual but to the larger society. During the early decades of this century the Survey movement affected sociological research and writings in the areas of both methodology and community studies.

The Evolution of a Self-Sustained Oscillation in a Nonlinear Continuous System

Abstract: : A gas filled tube has a pressure sensitive heat source at the center, while energy is allowed to radiate from the ends. For a sufficiently large feedback coefficient the system is linearly unstable. Within the nonlinear theory, the self-excited oscillation initially grows until a shock forms. The shock acts as a dissipative mechanism so that a balance is achieved and ultimately a time periodic state is reached. The small amplitude disturbance in the pipe is represented as the superposition of two simple waves traveling in opposite directions, and without interaction. Based on this representation the problem reduces to solving a nonlinear difference equation. (Author)

A technique for studying the rate of root growth of intact seedlings in a herbicide medium

Abstract: Summary. Time-lapse cine photography was used to record intact seedling root growth of pea and barley during separate exposure of root, shoot + seed, or entire needling to herbicides. The shoot + seed and the root zones were isolated in two square Petri dishes fixed edge to edge, and separately treated with moistened herbicide-treated sand. The seated dishes were placed at an angle of 30° in a photographic chamber. Photographs of roots were automatically recorded at 10-min intervals on 16 mm high speed reversal film over 72 h. Root length images on film were measured using an ocular micrometer. Root growth of pea and barley seedlings was normal when the shoot + seed zone was treated with 2,4-D at 1 and 10 ppm, respectively. In similar treatment of roots growth inhibition occurred after approximately 20 h in both plants, and root growth ceased alter 32 h in peas, and 57 h in barley. These results indicate the inherent tolerance of barley roots to 2,4-D. Technique pour l'etude du taux de croissance des racines intactes de plantules dans un milieu herbicide Resume. Le cinema au ralenti a ete utilise pour enregistrer la croissance des raciness intactes de plantules de pois et d'orge pendant une exposition separee des racines, de la partic aericnne + la semence ou dc la plantule entiere aux herbicides. La parlie aerienne + la semence et les zones de racines ont ete isolees dans deux boites de Petri carrees fixees par leurs angles et traitees separement avec du sable humidific par un traitement herbicide. Les boites fermees hermetiquement ont ete plaees sous un angle de 30° dans une chambre photographique. Les photographies des racines ont ete prises automntiquement a des intervalles de dix minutes pendant 72 heures sur un film reversible de 16 mm a haute sensibilite. La longueur des images des racines sur le film a ete mesuree a I'aide d'un oculaire micrometrique. La croissance des racines des plantules de pois et d'orge a ete normale quand la zone partic aerienne + semence a ete traitee avec du 2,4-D a 1 et 10 ppm respectivement. L'inhibition de la croissance apres un traitement similaire des racines se manifesta approximativement 20 heurcs apres dans les deux planles; la croissance des racines fut arretee apres 32 heures chez le pois et 57 heurcs chcz I'orge. Ces resultats mettent cn evidence la tolerance naturelle des racincs d'orge au 2,4-D. Eine Methods zur Messung des Wurzelwachslums intakler Keimlinge in Herbizidlosung Zusammenfassung. Zeitrafferphotographie wurde benutzt, um das Wurzelwachstum intakter Erbsen- und Gerstenkeimlinge zu messen, wobei entweder die Wurzel, der Spros mit Samen oder auch der gesamte Keimling den Herbiziden ausgesetzt wurden. Der Spros mit dem Samen und die Wurzelzone wurden in zwei aneinander befestigten quadratischen Petrischalen isoliert und fcuchtem, mit Herbizid behandellem Sand. getrennt ausgesetzt. Die verschlossenen Schalen wurden in einem Winkel von 30° in einer photographischen Kammer aufgestellt. In Abstanden von 10 min wurden die Wurzein mil 16mm-Umkehrfilm photographiert. Die Wurzellangen wurden auf dem Film mit einem Okularmikrometer gemessen. Bei Behandlung der Sprosone (einschlieslich Samen) mit 1 bzw. 10 ppm 2,4-D war das Wachstum von Erbsen- und Gerstenkeimlingen normal. Wurden die Wurzeln behandelt, so trat bei beiden Arten nach etwa 20 Stunden Wachstumshemmung auf. Das Wurzelwachstum kam bei der Erbse nach 32 Stunden und bei der Gerste nach 57 Stunden zum Stillstand. Diese Ergebnisse zeigen die den Gersnwurzeln innewohnende Toleranz gegenuber 2,4-D.

Subfractionation of Rabbit Skeletal-Muscle Microsomal Fraction

Abstract: In rabbit skeletal muscle a well-defined and highly organized system of internal membranes exists. These were first described by Retzius (1881) and Veratti (1902), subsequently overlooked and later rediscovered by Porter & Palade (1957) and Andersson-Cedergren (1959) and others. The skeletal-muscle cell is composed of three main structural components. These are, first, the myofibrils or contractile elements, the chief components of which are the thick and the thin filaments. The second group of structural components embraces the mitochondria, nuclei and ribosomes. Lysosomes have been reported in fractions prepared by the fractionation of skeletal muscle; however, their origin is obscure (Stagni & De Bernard, 1968). The internal membrane systems and the external membrane constitute the third group of structural components. The cell membrane or sarcolemma and the intracellular membrane systems together control the initiation of contraction and the subsequent relaxation of the muscle cell. Homogenization of skeletal muscle results in the formation of small rounded-off vesicles by an active pinching-off process of the various membrane systems (Palade & Siekevitz, 1956). These vesicles are to be found in the microsomal fraction (de Duve, 1964; Reid, 1967). The microsomal fraction would be expected to contain, in addition to the vesicles derived from the sarcoplasmic reticulum and from the transverse tubule system, elements of the outer cell membrane or sarcolemma and possibly vesicles arising by fragmentation of the mitochondria during the homogenization. Many enzymic activities have been demonstrated cytochemically to be associated with the internal membrane systems. Among these are ATPase* (EC 3.6.1.4) (Zebe, 1965) and acetylcholinesterase (EC 3.1.1.7) (Karnofsky, 1964). The ATPase activities associated with the internal membrane systems have been extensively studied since the discovery of the relaxing factor (Marsh, 1952). For a review of the various muscle ATPases see Duggan (1971). The ATP-dependent Ca2+-transporting system, which is responsible for the lowering of the sarcoplasmic Ca2+ concentration and thereby resulting in relaxation of the muscle, is present in the sarcoplasmic reticulum. Another microsomal ATPase activity has been found that is active in the absence of Ca2+ (Weber et al., 1966; Duggan, 1968b). This is the Ca2+-independent or basal ATPase. White skeletal muscle of the rabbit was homogenized in ice-cold 1 .OM-sucrose, forming a 25 % (w/v) homogenate. After a preliminary centrifugation for lOmin at 4°C at 4OOOg in an MSE High Speed 18 centrifuge (rotor no. 69179) the sediment was discarded. The supernatant, after filtration through several layers of cheesecloth, was diluted with half its volume of ice-cold distilled deionized water. This diluted supernatant was then centrifuged for 30min at 4°C at 15000g in the same centrifuge and rotor as used above. Again the sediment was discarded and the supernatant filtered through several layers of cheesecloth. This filtered supernatant served as the starting material for the preparation of concentrated microsomal suspensions. The preparation of concentrated microsomal suspensions was achieved by using the BXIV zonal rotor and a large sample volume (450ml). The microsomal material was sedimented from this sample into a lOOml layer of 1.0M-sucrose by centrifugation for 1 h at 4°C at 30000rev./min in an MSE Super Speed 50 centrifuge. After centrifugation the microsomal material was collected in four 25ml fractions. Analysis for the various enzymes and protein were carried out as described previously (Headon & Duggan, 1970). Fraction 2 was found to contain much of the total ATPase and Ca2+-uptake activities.

Southern Irish Unionism: A Study of Cork Unionists, 1884–1914 ( The Alexander Prize Essay )

Abstract: August The Fifth, 1914, was a cool, windy day at Mitchels-town. County Cork: but the guests at the houseparty in the Castle were not really conscious of the chilly breeze that whisked the clouds over the tops of the Galtee mountains that stood towering behind the Castle. Here during the afternoon the guests moved about the sunny, gusty terraces and talked, in little low groups, of the War. In retrospect, however, both this garden-party and those who attended it have a significance, dramatic and historical. August the fifth was the day after the War broke out; the garden-party was one of the last ever held in the Castle; and it was not a very ordinary group of people who talked of the War, and of whether its coming would avert the calamity of Home Rule.

Standing waves in an open pipe: A nonlinear initial-boundary value problem

Abstract: Transient disturbances in a column of gas in an open tube are described using a nonlinear theory which includes both amplitude dispersion and wave interactions. For reflection from an open end, the theory must include the second nonlinear correction to the characteristic to distinguish the linear and nonlinear travel times. The initial value problem is reduced to solving a functional difference equation which determines the signal on a boundary. When the signal is damped by allowing radiation of energy at the boundaries, it may be possible to prevent shock formation.

Seasonal changes in the sensitivity of frog skin to prostaglandin and the effect of external sodium and chloride on the response

Abstract: It has been reported that prostaglandin E1 stimulates sodium transport across isolated frog skin. This paper is primarily concerned with a seasonal change in the sensitivity of frog skin to prostaglandin E1 and F1∝. To determine prostaglandin action on sodium transport, the abdominal skin ofRana temporaria was mounted in an Ussing-type chamber and the shortcircuit current was recorded. In some experiments the skin potential and conductance were also measured. Arachidonic acid, a possible tissue precursor of prostaglandin also increases the short-circuit current. The prostaglandin action is independent of outside chloride and unchanged with 1/10 Ringer outside. The frog skin shows the same seasonal variation in sensitivity to prostaglandins as reported by others for anti-diuretic hormone. Cold season frogs gave large responses whereas summer frogs at ambient temperatures were quite refractory. Pyruvate can restore, in part, the ability of summer skins to respond to prostaglandin as for anti-diuretic hormone. It is concluded that the refractory nature of summer skins is due, in part, to a lack of a suitable energy source.

Molecular Weights of Mammalian Sera A-Type Carboxylic Ester Hydrolases

Abstract: The apparent molecular weight of D-alanine aminotransferase, determined with a calibrated Sephadex G-200 column, was about 60000. The purified aminotransferase was active with D-alanine and D-glutamate but not with L-alanine or L-glutamate. The product of the catalysed reaction of D-alanine with 2-oxoglutarate was not 1.-glutamate, as indicated by a negative L-glutamate dehydrogenase assay, thus indicating the production of D-glutamate. The pH optimum of the aminotransferase was 7.8-7.9 when the assays were buffered by ~ O ~ M H , P O , K O H , and was not significantly different when 100mM-tris-HC1 was used. The enzyme exhibited the initial-rate kinetics of an enzyme with a Ping Pong reaction mechanism. Double-reciprocal plots of u-alanine concentration (33-3 mM) versus enzyme velocity a t various fixed 2-oxoglutarate concentrations (2-0.08m~) gave a family of straight parallel lines. A series of parallel lines was also obtained when reciprocals of the 2-oxoglutarate concentrations were plotted at the different D-alanine concentrations. In addition, u-glutamate was a competitive inhibitor with respect to 1,-alanine, and D-glutamate was a non-competitive inhibitor against 2-oxoglutarate. L-Glutamate did not cause inhibition up to 301n~ . The K,,, values for D-alanine and 2-oxoglutarate were 2.4 and 0.05mM respectively. Incubation of the aminotransferase with 4.0m~-p-chloromercuribenzoate for 30min caused 36 inhibition. The presence of D-alanine and pyridoxal 5’-phosphate during the incubation afforded some protection. Therefore the enzyme was not very sensitive to inhibition by p-chloromercuribenzoate, although it was not as resistant as the Dalanine aminotransferase from Bacillus suhtilis (Martinez-Carrion &Jenkins, 1965). The function of D-alanine aminotransferase in Rhizobiim japonicurn is probably the provision of D-amino acids for cell-wall synthesis. However, the fact that its activity in both the bacteria and soya-bean root nodules is greater than that of 1.-alanine aminotransferase suggests that the rate of D-amino acid metabolism is significant in both bacteria and nodules.