Showing papers by "University of Leicester published in 1973"
TL;DR: Sediments from five lakes of the English Lake District have been analysed for 137Cs in order to test the hypothesis that a continuously accumulating lake sediment would incorporate 137Cs from fallout in a distribution pattern similar to that found from regular analysis of rain and air-borne particulate matter.
Abstract: SIGNIFICANT levels of caesium-137 from tests of nuclear weapons were first detected in the atmosphere in 1954; the maximum deposition1 occurred in 1963. It would be expected that a continuously accumulating lake sediment would incorporate 137Cs from fallout in a distribution pattern similar to that found from regular analysis of rain and air-borne particulate matter, provided that there has been no significant mixing in the sediment by diffusion or by the bottom fauna. Sediments from five lakes of the English Lake District have been analysed for 137Cs in order to test this hypothesis (Table 1).
391 citations
TL;DR: Gabbott et al. as mentioned in this paper showed that temperature and nutritive stress resulted in a decline in body condition of mussels, Mytilus edulis, when kept in the laboratory.
Abstract: In a previous paper Bayne & Thompson (1970) showed that temperature and nutritive stress resulted in a decline in body condition of mussels, Mytilus edulis, when kept in the laboratory. Both carbohydrate and protein were lost from the body tissues but the losses (as a percentage of the initial values) were greater from the germinal (mantle) than from the somatic (non-mantle) tissues. In spite of the loss of body reserves, M. edulis was able to continue maturation of the gonad during the autumn to spring period. In the early summer, however, when the gametes were fully ripe, stress resulted in a recession of the gonad and a rapid loss of protein from the mantle tissues. A similar decline in condition index and loss of glycogen and protein has been reported for adult oysters, Ostrea edulis, when maintained under hatchery conditions (Gabbott & Walker, 1971).
285 citations
TL;DR: In this article, the contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson.
Abstract: The contact of random surfaces is discussed in terms of a general theory of such surfaces previously described by Whitehouse and Archard, and the derived results are compared with the earlier work of Greenwood and Williamson. The physical significance of the differences between the two theories are discussed; in particular, the influence of a distribution of asperity curvatures is revealed. It is suggested that the simple model of Greenwood and Williamson can underestimate both the pressures at the true areas of contact and the probability of plastic flow.
230 citations
TL;DR: In this article, three levels of oxygen consumption rate are identified, viz. standard, routine and active, and the exponent that relates routine oxygen consumption to body size varies from high values in the summer to a lower value in the winter.
Abstract: Three levels of oxygen consumption rate are identified, viz. standard, routine and active. Animals fed above the maintenance energy requirement adjust their oxygen consumption rate to a routine level. Animals fed below the maintenance requirement reduce their oxygen consumption rate to a standard level within 35–40 days. The routine rate is seasonally variable, with high values in the winter and low values in the summer. The standard rate also varies seasonally. The exponent that relates routine oxygen consumption to body size varies from a high value in the summer to a lower value in the winter.
214 citations
TL;DR: There was no direct correlation between the rate of oxygen consumption and heart rate, and an apparent absence of a close nervous coupling between ventilation rate andheart rate in M. edulis.
Abstract: The heart beat, ventilation rate and oxygen uptake of Mytilus edulis L. were measured simultaneously, in response to changes in temperature and food level. There was no thermal acclimation of heart-beat frequency or amplitude to temperatures from 5° to 25°C. Oxygen consumption and ventilation rate acclimated to 10°, 15° and 20°C, but not to 25°C. Starvation reduced the rate of oxygen uptake and heart-beat frequency to a “standard level” and, in response to food, the ventilation rate and oxygen consumption immediately increased to an “active level”. Feeding was maintained after the initiation of “active metabolism”, and during the following 10 days the heart-beat frequency gradually increased to the level characteristic of fed individuals. There was no direct correlation between the rate of oxygen consumption and heart rate, and an apparent absence of a close nervous coupling between ventilation rate and heart rate in M. edulis.
146 citations
TL;DR: During starvation Mytilus utilises reserves of energy from the body, and during the winter protein utilisation makes a greater contribution than either carbohydrate or lipid to the balancing of the animals energy budget.
132 citations
TL;DR: Routine rate of oxygen consumption by Mytilus edulis is mainly a direct consequence of the acclimation of ventilation rate, and this differential response may be explained in terms of the effect of temperature on activity and is enhanced by the semi-logarithmic relationship between metabolic rate and activity.
129 citations
TL;DR: It is proposed that extension in length of the cell envelope occurs at a linear rate which is proportional to the growth rate and which doubles at the time of termination of rounds of replication, and changes in volume not associated with a change in growth rate are accommodated by achange in cell width.
Abstract: Average cell mass is shown to be inversely related to the concentration of thymine in the growth medium of a thy(-) strain of Escherichia coli. The kinetics of the transition from one steady-state average cell mass to another was followed in an attempt to determine the relationship between the chromosome replication time and the time between completion of a round of chromosome replication and the subsequent cell division. Differences in average cell mass are shown to be associated with similar differences in average cell volume. Changes in volume associated with changes in thymine concentration are shown to be due primarily to differences in the width of cells. It is proposed that extension in length of the cell envelope occurs at a linear rate which is proportional to the growth rate and which doubles at the time of termination of rounds of replication. Changes in volume not associated with a change in growth rate are therefore accommodated by a change in cell width. Conditions are described under which average cell mass can continue to increase in successive generations and no steady-state average cell mass is achieved.
126 citations
TL;DR: The behaviour, during the multicellular phase of the life-cycle, of amoebae of Dictyostelium discoideum grown in different media is described and the relationship between this sorting out behaviour and the mechanism of pattern formation in fruiting-body morphogenesis is discussed.
Abstract: The behaviour, during the multicellular phase of the life-cycle, of amoebae of Dictyostelium discoideum grown in different media is described. Amoebal populations were marked by growth-temperature-sensitive genetic lesions which do not interfere with developmental phenomena. The fate of cell populations was determined by measuring the relative number of mutant and wild-type cells at various stages in the life-cycle. Cells sort out during development in such a way that they may be ordered in a sequence in which those given early in the following list preferentially appear in the spore population when mixed with those given later in the list: cells grown in axenic medium + 86 mm glucose and harvested when in the exponential phase of growth; cells grown in axenic medium and harvested when in the exponential phase of growth; cells grown on bacteria and harvested when in the exponential phase of growth; cells grown in axenic medium + 86 mM glucose and harvested when in the stationary phase of growth. Chemotactic aggregation and grex migration are not essential for sorting-out to occur but, in the normal life-cycle, the cells of a grex formed from amoebae grown in different media have sorted out anteroposteriorly. The relationship between this sorting out behaviour and the mechanism of pattern formation in fruiting-body morphogenesis is discussed. Differences in density of the amoebae cannot account for the sorting out predispositions we observe.
124 citations
TL;DR: The North Atlantic Archaean craton, exposed in parts of Greenland, Labrador and northwest Scotland, is a high-grade gneiss terrain which contrasts with Archaean granite-greenstone-belt terrains such as those of southern Africa.
Abstract: The North Atlantic Archaean craton, exposed in parts of Greenland, Labrador and northwest Scotland, is a high-grade gneiss terrain which contrasts with Archaean granite-greenstone-belt terrains such as those of southern Africa. The tonalitic to granitic banded or agmatitic gneisses which occupy most of the craton are considered to be derived largely from granitic bodies emplaced within the crust. Early granitic gneisses of this type in Godthabsfiord are at least 3800 Ma in age and it is suggested that a granitic basement of similar age extended over much of the craton. Most of this early basement was reworked and interleaved with metamorphosed supracrustal rocks, with layered anorthositic complexes and with abundant tonalitic gneisses derived from younger intrusions. Identifiable metavolcanics and metasediments, forming narrow belts in the gneisses, occupy less than 20% of the craton; they include highly-metamorphosed basic, ultrabasic and intermediate-acid volcanic rocks with associated intrusions and predominantly chemical sedimentary rocks. Clastic sediments are preserved in the lower part of the Isua supracrustal belt where they are overlain by banded ironstones and metavolcanics. All these rocks suffered profound deformation and metamorphism which destroyed their primary relationships and culminated in the development of fold interference patterns without linear grain and in granulite or amphibolite-facies metamorphism ending at about 2800 Ma. Tectonic and metamorphic episodes over the next thousand million years were more localized and served to differentiate the Archaean craton from border-zones of early Proterozoic mobility.
118 citations
TL;DR: In the decerebrate cat, mechanical stimulation of the mucosa of the hard palate elicits four distinct oral reflexes—transient jaw-opening, transient jaw-closing, prolonged jaw- opening and a repeating tongue movement.
TL;DR: Yersiniosis is a disease of man and other animals due to Yersinia pseudotuberculosis and Y. enterocolitica that has been recorded in Europe, but in recent years the disease has been recognized more frequently in North America, Asia and Australia.
Abstract: Yersiniosis is a disease of man and other animals due to Yersinia pseudotuberculosis (syn. Pasteurella pseudotuberculosis) and Y. enterocolitica. The majority of human and animal infections have been recorded in Europe, but in recent years the disease has been recognized more frequently in North America, Asia and Australia. In the United Kingdom Y. pseudotuberculosis infection has been found in 6 species of wild mammals and in 21 species of wild birds. Principal reservoirs of infection are rodents and birds. Human infection with Y. pseudotuberculosis is probably acquired by direct or indirect contact with animals. Yersinia enterocolitica infection is less widespread in wild animals but more prevalent in human beings than the corresponding Y. pseudotuberculosis infection. Its epidemiology remains obscure.
TL;DR: In this article, the authors interpreted iron-rich mudstones (umbers), directly overlying pillow lavas of the Troodos Massif, Cyprus, as precipitates connected with late stages of volcanism on a Cretaceous ocean ridge.
TL;DR: The data are in closest agreement with the hypothesis that episome replication coincides with termination of rounds of chromosome replication and are inconsistent with the hypotheses that it occurs at a constant cell age, or at the same time as initiation of roundsof chromosome replication.
TL;DR: The range of chromosome number and structure observed in established cultures strongly points to the origin of these changes during culture, and the precise distribution of chromosomes at mitotic anaphase seems the most likely point at which instability could be induced in culture.
Abstract: CULTURED cells of both animal and plant tissues are characterised by instability of chromosome number and structure1,2. Although there is evidence3 that polyploid plant cell lines may arise from endoreduplicated nuclei in the original explant, the range of chromosome number and structure observed in established cultures strongly points to the origin of these changes during culture. Since the precise distribution of chromosomes at mitotic anaphase is the essential prerequisite for chromosome number stability5, this seems the most likely point at which instability could be induced in culture. It has been shown6,7 that, in culture, animal cells of various species are characterised by the presence of multipolar mitoses, a feature which would produce daughter nuclei with aneuploid chromosome numbers. Such multipolar mitoses have been briefly noted for plant tissue cultures8,9 but their frequencies have not been quantified.
TL;DR: In this paper, the granulite facies metamorphism is recognized as a distinctive time marker which probably has the following chronological relationships with other principal events in the Archaean of West Greenland, particularly in the Godthaabsfjord area.
Abstract: IN the Archaean basement complex of West Greenland there are several widely separated granulite facies areas, up to 100 km across1. Rocks from three such areas, Sukkertoppen, Nord-land and Fiskenaesset (Fig. 1), were originally selected for this study on the assumption that the granulite facies metamorphism represented the oldest metamorphic event observable in West Greenland1. This idea has been shown to be ill founded by subsequent geological and geochronological work2,3. The granulite facies metamorphism is now recognized as a distinctive time marker which probably has the following chronological relationships with other principal events in the Archaean of West Greenland, particularly in the Godthaabsfjord area2,3: (1) Plutonic development ∼ 3,700-3,750 m.y. ago4,5 of a complex of granites, granodiorites and tonalites. Metamorphism, migmatization and deformation, with production of banded gneisses (Amitsoq gneisses). (2) Intrusion of a basic dyke swarm (Ameralik dykes) into the Amitsoq gneisses. (3) Eruption of basic volcanics and deposition of sediments (Malene supracrustals). (4) Emplacement of basic igneous complexes with prominent calcic anorthosites. Possibly broadly similar in age throughout the Archaean of West Greenland. (5) Tectonic interleaving of earlier rock units. (6) Intrusion of major suite of granites, granodiorites, tonalites and diorites at 3,040 ±50 m.y. ago6, the parent rocks of the Nuk gneisses. (7) Deformation and folding, accompanied by migmatization and metamorphism that culminated in amphibolite facies conditions in the Godthaabsfjord area, but reached granulite facies to the north and south (in the areas we discuss in this communication). Earlier felsic rocks converted to gneisses. (8) Emplacement of Qorqut granite and pegmatites, ˜ 2,600 m.y. ago (Oxford unpublished data). Intrusion of Precamb-rian dolerite dykes.
TL;DR: In this article, a lower bound on the rupture times of solid circular torsion bars is derived using an iterative procedure for different constitutive and damage laws, and a single reference stress can be defined for the structure.
Abstract: L ower bounds on the rupture times of steadily loaded solid circular torsion bars are shown to agree well with values of the rupture times computed using an iterative procedure for different constitutive and damage laws. Corresponding to the lower bound rupture time a single reference stress can be defined for the structure. Multi-axial rupture effects are included in determining a lower bound rupture time and simple statements are made regarding structural performance and different types of material behaviour. The mode of expression of the Kachanov damage parameter in the calculation method is shown to be unimportant. Good agreement is shown between the prediction method and the results of experiments conducted on bars prepared from different materials.
TL;DR: The endothelial membranes took up added Ca in the presence of added ATP and this uptake was inhibited by indomethacin and also by members of a group of pharmacologically‐related drugs.
Abstract: 1. Cellular membranes were obtained by centrifugation of homogenates of various human and guinea-pig tissues. These membranes took up added calcium (Ca) when incubated at 25° C for 10 min in histidine buffer at pH 7·4. The uptake of Ca was increased by the presence of adenosine triphosphate (ATP).
2. Evidence is presented that the membrane fragments which took up Ca under these conditions were derived from the endoplasmic reticulum.
3. The ATP-dependent uptake of Ca by membranes derived from guinea-pig aortic or gastric smooth muscle or from human umbilical arterial muscle was inhibited by indomethacin in a concentration-dependent manner.
4. The ATP-dependent uptake of Ca by membranes derived from heart, brain, skeletal muscle or liver of the guinea-pig was not inhibited by indomethacin.
5. Endothelial cells were obtained from the lining of the human umbilical vein. Cellular membranes were prepared from the endothelial cells by homogenization and centrifugation. The endothelial membranes took up added Ca in the presence of added ATP and this uptake was inhibited by indomethacin and also by members of a group of pharmacologically-related drugs.
TL;DR: The Chuar Group is a group of 6,610 ft (2,013 m) thick and has been divided into three formations and seven members as discussed by the authors, and the lower two formations, Galeros (below) and Kwagunt (above) are predominantly argillaceous with thin limestone beds, while the highest, Sixty Mile Formation, is mostly coarse breccia.
Abstract: The Chuar Group is exposed in tributary canyons to the Colorado River over an area some 15 mi (24 km) long and 4 mi (6 km) wide. The rocks are faulted against Paleozoic rocks by the Butte fault on the east, and unconformably overlain by Paleozoic rocks to the west. The group is 6,610 ft (2,013 m) thick and has been divided into three formations and seven members. The lower two formations, Galeros (below) and Kwagunt (above) are predominantly argillaceous with subordinate thin limestone beds, while the highest, Sixty Mile Formation, is mostly coarse breccia. Stromatolites are present at three horizons, one of them biohermal. The form-genera Inzeria , Baicalia , and Boxonia indicate an upper Riphean age. The mega-planktonic fossil Chuaria occurs near the top of the Kwagunt Formation. The Chuar rocks are probably younger than any other Precambrian rocks in Arizona. They may be contemporary with rocks below the Cambrian in eastern California, and with the Windermere Formation of the northern Cordillera.
TL;DR: The oldest greenstone belts are largely granulites and gneisses, and in west Greenland there is evidence of 1000 Ma of crustal history before the final high-grade metamorphism as discussed by the authors.
Abstract: The oldest Archaean rocks in most shield regions are largely granulites and gneisses, and in west Greenland there is evidence of 1000 Ma of crustal history before the final high-grade metamorphism. Archaean greenstone belts are mostly younger than the high-grade terrains although in some areas, such as southern Africa, this has not yet been proved reliably. The greenstone belts may have developed as oceanic crust in connexion with plate movements, the earlier continents being represented by the more deeply eroded high-grade regions. Stabilization of the Archaean cratons is signalled by continental-scale intrusion of dolerite dyke swarms. Proterozoic mobile belts are exposed at two structural levels. Some early linear basins have mio- and eu-geosynclinal parts and may have been located along Proterozoic suture lines. More deeply eroded mobile belts are often floored by extensive, partly reworked, crystalline basement and probably developed along linear rifted zones which acted as loci for high heat flow and igneous activity; they lack ophiolites and are difficult to interpret as collision-type mountain belts. Most probably there were intra-continental plate movements in the Proterozoic.
TL;DR: A statistical treatment of steady-state enzyme kinetic measurements is described that allows for depletion of free substrate or free inhibitor concentrations owing to significant binding to the enzyme.
Abstract: A statistical treatment of steady-state enzyme kinetic measurements is described that allows for depletion of free substrate or free inhibitor concentrations owing to significant binding to the enzyme. Vmax., Km or Ki, enzyme concentration, the concentration of substrate or inhibitor required for a half-maximal effect and standard errors of these parameters can be calculated from dose–response measurements; the concentration of each component of the system may be estimated also. The statistically best values of the parameters are used to convert dose–response curves into convenient linear forms. The method is applied to dose–response measurements of hydroxyquinoline N-oxide inhibition of bacterial respiration and aminopterin inhibition of dihydrofolate reductase. Two FORTRAN programs for this method have been deposited as Supplementary Publication no. SUP 50019 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies may be obtained on the terms indicated in Biochem. J. (1973) 131, 5.
TL;DR: Evidence is presented for the belief that the activity of the adenylate cyclase enzyme controls the amount of cyclic AMP synthesized rather than the activity or amount of CYP phosphodiesterase present.
Abstract: During growth of myxamoebae of Dictyostelium discoideum (strain Ax-2) in axenic medium, the myxamoebae secrete cyclic AMP. As the cells leave the exponential phase of growth and enter the stationary phase, there is an approximate doubling of the intracellular cyclic AMP content, but the amount of extracellular cyclic AMP remains proportional, at all times, to the number of myxamoebae present. During development of axenically grown myxamoebae, there is first a rise in the intracellular concentration of cyclic AMP, followed by a rise in the amount of extracellular cyclic AMP, which reaches a peak at the time of aggregation and then declines. There is a second peak in the amount of extracellular cyclic AMP found at the time of fruiting-body formation, but this second peak is not associated with a rise in the intracellular cyclic AMP concentration. Controls thus exist over the synthesis and secretion of cyclic AMP. Evidence is presented for the belief that the activity of the adenylate cyclase enzyme controls the amount of cyclic AMP synthesized rather than the activity or amount of cyclic AMP phosphodiesterase present. Similar changes occur in extracellular cyclic AMP and phosphodiesterase concentrations during incubation of myxamoebae in buffered suspensions to those occuring during the first few hours of development of such cells on solid media, but the timing of these changes is different.
TL;DR: The possibility that the different cytochrome oxidases may terminate respiratory chains of different redox span or may be associated with separate phosphorylating or non-phosphorylates chains is discussed in relation to the general properties and physiological functions of these oxidases.
Abstract: 1The oxidative phosphorylation efficiencies of seven species of bacteria, selected on the basis of their cytochrome oxidase composition, were determined from measurements of growth efficiencies with respect to oxygen (YO2) and →H+/O quotients of washed cell suspensions.
2Organisms which contained either cytochrome oxidase aa3 (Bacillus subtilis, Microbacterium thermosphactum) or o (Xanthomonas hyacynthi, Acinetobacter lwoffi, Escherichia coli and Kurthia zopfii) as their sole terminal oxidase exhibited P/O ratios of approximately 3 whereas Acetobacter T71, which contained cytochrome oxidase a1, as its major oxidase, exhibited a P/O ratio of approximately 1.
3The synthesis of cytochrome oxidases a1, and a2 by E. coli under oxygen-limited conditions was accompanied by a sharp decrease in whole-cell energy-conversation efficiency. A similar decrease in efficiency was also observed as a result of the increased use by K. zopfii of a second oxidase, insensitive to cyanide and carbon monoxide, which has not hitherto been reported.
4The possibility that the different cytochrome oxidases may terminate respiratory chains of different redox span or may be associated with separate phosphorylating or non-phosphorylating chains is discussed in relation to the general properties and physiological functions of these oxidases.
TL;DR: A comparison study of the effects of light quality on GLYCOLLATE BIOSYNTHESIS by using a trial-and-error approach and the results show that the former is more beneficial than the latter.
Abstract: INTRODUCTION . . . . 751 GLYCOLLATE FORMATION DURING PHOTOSYNTHESIS. 753 GLYCOLLATE EXCRETION BY ALGAE . 755 REGULATION OF GLYCOLLATE EXCRETION BY ALGAE. . 755 EFFECT OF LIGHT QUALITY ON GLYCOLLATE BIOSYNTHESIS BY ALGAE. . . . 757 GLYCOLLATE OXIDIZING ENZYME OF ALGAE. 757 REGULATION OF GLYCOLLATE DEHYDROGENASE ACTIVITY IN ALGAE . 758 GLYCOLLATE PATHWAY IN ALGAE 758 PHOTOHETEROTROPHIC GROWTH OF ALGAE ON GLYCOLLATE . \. . 760 INTRACELLULAR LOCALIZATION OF THE GLYCOLLATE PATHWAY IN ALGAE . 760 PHOTORESPIRATION IN ALGAE . . . . . . . . . 762 CONCLUSIONS . . . . . . . . . . . 763 REFERENCES . . . . . . . . . 764
TL;DR: Long-term labelling experiments indicate turnover of RNA during the phase of active cell division and suggest that a large proportion of the degradation products are not re-utilized for RNA synthesis.
Abstract: [2-14C]-uridine is rapidly taken up by sycamore cells in suspension culture. A proportion of the radioactivity enters RNA without measurable delay, whilst the remainder equilibrates with a large pool of phosphorylated compounds, the major radioactive component of which is 5'-UMP. Both the uracil and cytosine residues of RNA receive label from [14C]-uridine and, when the cells are supplied with high concentrations of uridine, these bases are derived almost exclusively from the nucleoside. [14C]-uridine is incorporated into RNA at all stages of the growth cycle of batch cultures; its continuing incorporation, when the total RNA content of the cells is rapidly decreasing, indicates a high rate of turnover of the total RNA. Long-term labelling experiments also indicate turnover of RNA during the phase of active cell division and suggest that a large proportion of the degradation products are not re-utilized for RNA synthesis. Sycamore cells degrade [2-14C]-uridine with release of 14C02. The proportion degraded increases from 25 per cent at an external uridine concentration of 10 '6 M to 75 per cent at 10~3 M. Despite this, nucleic acids are the only macromolecules that receive a significant amount of radioactivity from [2-14]C-uridine.
TL;DR: Control freezing and low temperature storage of cultured plant cells might enable the characters of newly initiated cultures to be preserved, and preliminary work with plant cells has shown the promise of this approach.
Abstract: MANY plant tissue cultures change in growth rate, chromosome cytology and morphogenic potential during repeated subculture1–3. Controlled freezing and low temperature storage of cultured plant cells might enable the characters of newly initiated cultures to be preserved. Cell preservation at the temperature of liquid N2 (−196° C) has been successful with animal cells4 and preliminary work with plant cells has shown the promise of this approach5–7. Latta has reported regrowth of cultures of carrot (Daucus carota L.) following freezing for up to 2 months at −40° C or at −196° C but did not assess the percentage of cells surviving6.
TL;DR: The purification of beta-N-acetylhexosaminidase, alpha-glucosidase and beta-mannosid enzyme from the spent growth medium of Dictyostelium discoideum strain Ax-2 myxamoebae is described.
Abstract: The purification of beta-N-acetylhexosaminidase, alpha-glucosidase, alpha-mannosidase and beta-glucosidase from the spent growth medium of Dictyostelium discoideum strain Ax-2 myxamoebae is described. beta-N-Acetylhexosaminidase and alpha-glucosidase were obtained in high yield and as homogeneous preparations whereas the alpha-mannosidase preparation consisted of two electrophoretically distinct isoenzymes. The physical, chemical and kinetic properties of these enzymes are described.
TL;DR: This mutant grew in media containing any one of a variety of substances, including hexoses, hexose 6-phosphates, sugar acids and glucogenic substrates, at rates not significantly different from those at which the parent organism grew on these substrates.
Abstract: 1. The isolation and properties of a mutant of Escherichia coli devoid of fructose 1-phosphate kinase activity are described. 2. This mutant grew in media containing any one of a variety of substances, including hexoses, hexose 6-phosphates, sugar acids and glucogenic substrates, at rates not significantly different from those at which the parent organism grew on these substrates. However, only the parent grew on fructose or fructose 1-phosphate. 3. Fructose and fructose 1-phosphate inhibit the growth of the mutant, but not of its parent, on other carbon sources. 4. Even though not previously exposed to fructose, the mutant took up [14C]fructose rapidly but to only a small extent: [14C]fructose 1-phosphate was identified as the predominant labelled product. In contrast, the equally rapid but more extensive uptake of [14C]fructose by the parent organism required prior growth in the presence of fructose.
TL;DR: The changes which occur within the respiratory system of A. vinelandii following the sudden exposure of low aeration cultures to excess oxygen conditions are described and, by lowering the energy conservation efficiency, appear to be responsible for the resultant phenomenon of enhanced respiration.