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91.
John W. Arkwright Neil G. Blenman Ian D. Underhill Simon A. Maunder Nicholas J. Spencer Marcello Costa Simon J. Brookes Michael M. Szczesniak Phil G. Dinning 《Journal of biophotonics》2011,4(4):244-251
Diagnostic catheters based on fibre Bragg gratings (FBG's) are proving to be highly effective for measurement of the muscular activity associated with motility in the human gut. While the primary muscular contractions that generate peristalsis are circumferential in nature, it has long been known that there is also a component of longitudinal contractility present, acting in harmony with the circumferential component to improve the overall efficiency of material movement. We report the detection of longitudinal motion in mammalian intestine using an FBG technique that should be viable for similar detection in humans. The longitudinal sensors have been combined with our previously reported FBG pressure sensing elements to form a composite catheter that allows the relative phase between the two components to be detected. The catheter output has been validated using video mapping in an ex‐vivo rabbit ileum preparation. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
92.
Andrew J. R. Watts Amaya Albalat Ian P. Smith Robert J. A. Atkinson Douglas M. Neil 《Marine Biology Research》2016,12(6):563-572
Norway lobsters, Nephrops norvegicus, are sediment-dwelling decapod crustaceans that excavate burrows from which they make short excursions to feed by predation and scavenging. The females of this species are known to reside within their burrows for an extended period of time over the winter while brooding their eggs. The aim of this study was to assess the likelihood of these females being able to feed during this brooding period. Biophysical and biochemical measurements that had previously been shown to change with starvation under laboratory conditions in male N. norvegicus were taken for female N. norvegicus under similar conditions. These measurements were also compared in both sexes obtained from monthly trawl samples from the Clyde Sea Area, Scotland, UK, together with trawl composition data. The laboratory study showed that the hepatosomatic index, and the copper, lipid and water content of the hepatopancreas can be used as indicators of the state of starvation in females, as in males. In the wild, both sexes have reduced nutritional status during the winter, but not to the degree seen in animals starved for 20 weeks in aquarium trials. This study does not support the hypothesis that females cease feeding over winter, during their brooding period. Firstly, some females were unable to sustain ovary development during starvation under controlled conditions, contrary to field observations. Secondly, field data suggest that there is no sex-specific reduction in nutritional status. 相似文献
93.
Clostridium acetobutylicum Mutants That Produce Butyraldehyde and Altered Quantities of Solvents 总被引:3,自引:2,他引:3 下载免费PDF全文
Spontaneous mutants of Clostridium acetobutylicum NRRL B643 that were resistant to allyl alcohol (AA) were selected and characterized. These mutants contained 10- to 100-fold reduced activities of butanol and ethanol alcohol dehydrogenase. The AA mutants formed two groups and produced no ethanol. Type 1 AA mutants produced significant amounts of a new solvent, butyraldehyde, and contained normal levels of the coenzyme A-dependent butyraldehyde dehydrogenase (BAD). Type 2 AA mutants produced no significant butyraldehyde and lower levels of all solvents, and they contained 45- to 100-fold lower activity levels of BAD. Following ethyl methanesulfonate mutagenesis, low-acid-producing (Acid−) mutants were selected and characterized as superinduced solvent producers, yielding more than 99% of theoretical glucose carbon as solvents and only small amounts of acetate and butyrate. Following ethyl methanesulfonate mutagenesis, 13 sporulation-negative (Spo−) mutants were characterized; and 3 were found to produce only butyrate and acetate, a minor amount of acetone, and no alcohols. These Spo− mutants contained reduced butanol dehydrogenase activity and no BAD enzyme activity. The data support the view that the type 2 AA, the Acid−, and the Spo− mutants somehow alter normal regulated expression of the solvent pathway in C. acetobutylicum. 相似文献
94.
Amlie Le Roy Geoffrey P. F. Mazu Neil B. Metcalfe Frank Seebacher 《Ecology and evolution》2021,11(14):9791
Food availability and temperature influence energetics of animals and can alter behavioral responses such as foraging and spontaneous activity. Food availability, however, is not necessarily a good indicator of energy (ATP) available for cellular processes. The efficiency of energy transduction from food‐derived substrate to ATP in mitochondria can change with environmental context. Our aim was to determine whether the interaction between food availability and temperature affects mitochondrial efficiency and behavior in zebrafish (Danio rerio). We conducted a fully factorial experiment to test the effects of feeding frequency, acclimation temperature (three weeks to 18 or 28°C), and acute test temperature (18 and 28°C) on whole‐animal oxygen consumption, mitochondrial bioenergetics and efficiency (ADP consumed per oxygen atom; P:O ratio), and behavior (boldness and exploration). We show that infrequently fed (once per day on four days per week) zebrafish have greater mitochondrial efficiency than frequently fed (three times per day on five days per week) animals, particularly when warm‐acclimated. The interaction between temperature and feeding frequency influenced exploration of a novel environment, but not boldness. Both resting rate of producing ATP and scope for increasing it were positively correlated with time spent exploring and distance moved in standardized trials. In contrast, behavior was not associated with whole‐animal aerobic (oxygen consumption) scope, but exploration was positively correlated with resting oxygen consumption rates. We highlight the importance of variation in both metabolic (oxygen consumption) rate and efficiency of producing ATP in determining animal performance and behavior. Oxygen consumption represents energy use, and P:O ratio is a variable that determines how much of that energy is allocated to ATP production. Our results emphasize the need to integrate whole‐animal responses with subcellular traits to evaluate the impact of environmental conditions on behavior and movement. 相似文献
95.
96.
McAllister SE Ashrafpour H Cahoon N Huang N Moses MA Neligan PC Forrest CR Lipa JE Pang CY 《American journal of physiology. Regulatory, integrative and comparative physiology》2008,295(2):R681-R689
We tested our hypothesis that postischemic conditioning (PostC) is effective in salvage of ischemic skeletal muscle from reperfusion injury and the mechanism involves inhibition of opening of the mitochondrial permeability transition pore (mPTP). In bilateral 8x13 cm pig latissimus dorsi muscle flaps subjected to 4 h ischemia, muscle infarction increased from 22+/-4 to 41+/-1% between 2 and 24 h reperfusion and remained unchanged at 48 (38+/-6%) and 72 (40+/-1%) h reperfusion (P<0.05; n=4 pigs). PostC induced by four cycles of 30-s reperfusion/reocclusion at the onset of reperfusion after 4 h ischemia reduced muscle infarction from 44+/-2 to 22+/-2% at 48 h reperfusion. This infarct protective effect of PostC was mimicked by intravenous injection of the mPTP opening inhibitor cyclosporin A or NIM-811 (10 mg/kg) at 5 min before the end of 4 h ischemia and was abolished by intravenous injection of the mPTP opener atractyloside (10 mg/kg) at 5 min before PostC (P<0.05; n=4-5 pigs). PostC or intravenous cyclosporin A injection at 5 min before reperfusion caused a decrease in muscle myeloperoxidase activity and mitochondrial free Ca2+ concentration and an increase in muscle ATP content after 4 h ischemia and 2 h reperfusion compared with the time-matched controls. These effects of PostC were abolished by intravenous injection of atractyloside at 5 min before PostC (P<0.05; n=6 pigs). These observations support our hypothesis that PostC is effective in salvage of ischemic skeletal muscle from reperfusion injury and the mechanism involves inhibition of opening of the mPTP. 相似文献
97.
Catabolic instability,plasmid gene deletion and recombination in Alcaligenes sp. BR60 总被引:12,自引:0,他引:12
An Alcaligenes sp. BR60, isolated from surface runoff waters of the Hyde Park industrial landfill, contained a novel 85 kb catabolic plasmid (pBR60) functional in 3-chlorobenzoate (3Cba) degradation. The plasmid exhibited a spontaneous 3.2% frequency of deletion of a 14 kb fragment specifying 3Cba degradation. The deletion mutant BR40 and mitomycin C cured strains were not able to grow on 3Cba and had reversion frequencies of less than 10-10 cell-1 generation-1. Transformation or conjugation of pBR60 into cured strains restored catabolic activity. An EcoRI, BgIII, HindIII and SaII restriction map of the deletion region was constructed, and EcoRI and HindIII fragments spanning the deletion region of the plasmid were cloned in pUC18. Conjugation of resistance plasmid R 68.45 into Alcaligenes sp. BR60, with selection on antibiotics, resulted in the elimination of pBR60 and maintenance of unaltered R68.45. In 30% of the exconjugants, 3Cba degradative capacity was retained, although variation in the regulation of 3Cba degradation was observed in these strains. Hybridization of deletion region fragments to BgIII digested total DNA of BR60 and the R68.45 cured exconjugants revealed the presence of pBR60 deletion region sequences in the chromosome of exconjugants. Hybridization also revealed a repeated sequence flanking the deletion region of pBR60. Selection on 4-chlorobenzoate as a sole source of carbon and energy resulted in the isolation of 4Cba+ mutants of Alcaligenes sp. BR60.Abbreviations 3 and 4 Cba
chlorobenzoic acid isomers and growth phenotypes
- HPLC
high pressure liquid chromatography
- ATCC
American Type Culture Collection 相似文献
98.
Lindström Irene Bontell Neil Hall Kevin E Ashelford JP Dubey Jon P Boyle Johan Lindh Judith E Smith 《Genome biology》2009,10(5):R53-17
Background
Toxoplasma gondii is a zoonotic parasite of global importance. In common with many protozoan parasites it has the capacity for sexual recombination, but current evidence suggests this is rarely employed. The global population structure is dominated by a small number of clonal genotypes, which exhibit biallelic variation and limited intralineage divergence. Little is known of the genotypes present in Africa despite the importance of AIDS-associated toxoplasmosis. 相似文献99.
Moses K. Langat Neil R. Crouch Leena Pohjala Päivi Tammela Peter J. Smith Dulcie A. Mulholland 《Phytochemistry letters》2012,5(3):414-418
Two new ent-kauren-19-oic acid derivatives, ent-14S*-hydroxykaur-16-en-19-oic acid and ent-14S*,17-dihydroxykaur-15-en-19-oic acid together with eleven known compounds ent-kaur-16-en-19-oic acid, ent-kaur-16-en-19-al, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid, 8R,13R-epoxylabd-14-ene, eudesm-4(15)-ene-1β,6α-diol, (?)-7-epivaleran-4-one, germacra-4(15), 5E,10(14)-trien-9β-ol, acetyl aleuritolic acid, β-amyrin, and stigmasterol were isolated from the stem bark of Croton pseudopulchellus (Euphorbiaceae). Structures were determined using spectroscopic techniques. Ent-14S*-hydroxykaur-16-en-19-oic acid, ent-kaur-16-en-19-oic acid, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid and 8R,13R-epoxylabd-14-ene were tested for their effects on Semliki Forest virus replication and for cytotoxicity against human liver tumour cells (Huh-7 strain) but were found to be inactive. Ent-kaur-16-en-19-oic acid, the major constituent, showed weak activity against the Plasmodium falciparum (CQS) D10 strain. 相似文献
100.