scholarly journals Myothermic apparatus

1928 ◽  
Vol 103 (723) ◽  
pp. 117-137 ◽  
Keyword(s):  
Heat Production ◽  
Present Author ◽  
Single Stimulus ◽  
Relative Accuracy ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Essential Condition ◽  
Energy Exchanges

The investigation to be described in subsequent papers represent an attempt to clear up, with the greatest accuracy possible, a number of outstanding or controversial points in connection with the energy exchanges of muscle. During the course of them a new and striking phenomenon has been encountered, in respect of the resting heat-production of muscles kept under strictly anaerobic conditions. It has been necessary, moreover, for various purposes, to follow the heat-production of stimulated or recovering muscles for long periods, sometimes for an hour or more. The apparatus available proved inadequate for these new purposes, and had to be designed and constructed afresh. The present paper is a description of the methods finally adopted; the results obtained are given separately. In almost every respect the apparatus now employed will yield more reliable results, and is simpler to use, than any previously described, at any rate by the present author. The essential condition which it fulfils is that it will read, with relative accuracy, not only the heat suddenly produced by a single stimulus, but that liberated over long intervals at rest, or in recovery, or by prolonged discontinuous stimulation.

Versatile Cryostated Optically Transparent Thin-Layer Electrochemical (OTTLE) Cell for Variable-Temperature UV-Vis/IR Spectroelectrochemical Studies

1994 ◽  
Vol 48 (12) ◽  
pp. 1522-1528 ◽  
Author(s):  
F. Hartl ◽  
H. Luyten ◽  
H. A. Nieuwenhuis ◽  
G. C. Schoemaker
Keyword(s):  
Thin Layer ◽  
Low Temperatures ◽  
Variable Temperature ◽  
Experimental Setup ◽  
Strictly Anaerobic ◽  
Carbonyl Complexes ◽  
Anaerobic Conditions ◽  
Optically Transparent ◽  
Solution Layer ◽  
Preset Temperature

This article describes the construction of a novel optically transparent thin-layer electrochemical (OTTLE) cell for IR and UV-Vis spectroelectrochemical experiments at variable temperature. The cell has a three-electrode set melt-sealed into a smooth polyethylene spacer which is sandwiched between two CaF2 windows. The width of this spacer (0.18–0.20 mm) defines the thickness of the thin solution layer. The whole electrode assembly is housed in a thermostated Cu block of the OTTLE cell which fits into a double-walled nitrogen-bath cryostat. The experimental setup permits relatively fast electrolysis within the tested temperature range of 295 to 173 K under strictly anaerobic conditions and protection of light-sensitive compounds. Other important merits of the cell design include lack of leakage, facile cleaning, almost negligible variation of the preset temperature, and facile manipulation in the course of the experiments. The applicability of the variable-temperature IR/UV-Vis OTTLE cell is demonstrated by stabilization of a few electrogenerated carbonyl complexes of Mn(I) and Ru(II) with 3,5-di- tert. butyl-1,2-benzo(semi)quinone (DB(S)Q) and N, N′-diisopropyl-1,4-diaza-1,3-butadiene (iPr-DAB) ligands, respectively, at appropriately low temperatures.

scholarly journals Redesigning Escherichia coli Metabolism for Anaerobic Production of Isobutanol

2011 ◽  
Vol 77 (14) ◽  
pp. 4894-4904 ◽  
Author(s):  
Cong T. Trinh ◽  
Johnny Li ◽  
Harvey W. Blanch ◽  
Douglas S. Clark
Keyword(s):  
Escherichia Coli ◽  
Anaerobic Growth ◽  
Mode Analysis ◽  
Glycolytic Flux ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Content Type ◽  
E Coli ◽  
Model Predictions ◽  
Chromosomal Genes

ABSTRACTFermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design anEscherichia colistrain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism ofE. coliwas decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growthE. colicannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesignedE. colistrain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producingE. colistrain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production.

Histochemical Demonstration of Certain DPN-Linked Dehydrogenases and of Aldolase in the Red and White Fibres of Pigeon Breast-Muscle

1962 ◽  
Vol s3-103 (61) ◽  
pp. 41-46
Author(s):  
J. C. GEORGE ◽  
C. L. TALESARA
Keyword(s):  
Enzyme Activity ◽  
Histochemical Demonstration ◽  
Breast Muscle ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
High Concentration ◽  
Hydrogen Acceptor ◽  
Localization Pattern ◽  
Important Link

The distribution and localization-pattern of certain DPN-linked dehydrogenases (malic, lactic, D-glucose, glutamic, and a-glycerophosphate) were demonstrated histochemically in the red and white fibres of pigeon breast-muscle by using neotetrazolium as the hydrogen acceptor, under strictly anaerobic conditions. All the dehydrogenases studied showed distinctly higher enzyme activity in the narrow red fibres than in the broad white fibres. That of a-glycerophosphate was, however, found to be appreciably more abundant than other dehydrogenases in the broad fibres. A high concentration of aldolase, which forms an important link in the chain of enzymes in glycolysis, was histochemically demonstrated in the broad, white, glycogen-loaded fibres.

Influence du mode de culture dans la toxinogénèse de Plectridium tetani

1970 ◽  
Vol 16 (2) ◽  
pp. 135-136 ◽  
Author(s):  
G. Vinet ◽  
V. Fredette
Keyword(s):  
Tetanus Toxin ◽  
Culture Medium ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions

Production of tetanus toxin under strictly anaerobic conditions does not favor high titers comparable to those obtained when the surface of the culture medium is largely exposed to the air.

Energy exchanges of pregnant and lactating ewes

1964 ◽  
Vol 15 (1) ◽  
pp. 127 ◽  
Author(s):  
N McCGraham
Keyword(s):  
Heat Production ◽  
Nitrogen Loss ◽  
Metabolizable Energy ◽  
Energy Utilization ◽  
Carbon And Nitrogen ◽  
Direct Measurements ◽  
Heat Increment ◽  
Energy Retention ◽  
Energy Exchanges ◽  
Pregnant Ewe

At intervals throughout gestation, the energy, carbon, and nitrogen exchanges of four Merino ewes were determined with the aid of closed-circuit indirect calorimetry. Six similar but non-pregnant animals were studied at the same time. The food consisted of equal parts of lucerne and wheaten hay; half the sheep in each group were given a constant 600 g/day and half 900 g/day, and the non-pregnant ewes were fasted on one occasion. Free fatty acids, glucose, and ketones in the blood were also determined during the final stages of pregnancy. Balance measurements were continued during lactation, the ewes being given 1200 g food/day for the first month and 900 g for the second. The digestibility of the food was not affected by pregnancy or lactation, but urinary nitrogen loss decreased as pregnancy advanced and was least during lactation. Although a constant amount of food was eaten, the heat production of each pregnant animal increased throughout gestation. The heat increment of pregnancy at term was 90 kca1/24 hr/kg foetal tissue. The most direct measurements of oxygen uptake by the foetus in utero indicate much lower levels of heat production per kilogram of tissue; it is concluded that these are underestimates. The metabolic rate was unusually high immediately before parturition, and in two cases decreased to near non-pregnant levels 24 hr after lambing. The total energy retention of the ewes became smaller as pregnancy advanced, and in two cases was negative at term. Metabolizable energy was used for reproduction with a gross efficiency of 15–22% and a net efficiency of 13%. The metabolizable energy used per kilogram of foetus was approximately 10% of the maintenance requirement of the ewe herself. Daily energy utilization by the conceptus at term probably accounted for 70% of the glucogenic substances available from the food. There was no evidence of increased gluconeogenesis from protein by the pregnant ewe. The nutrition of the ewe during gestation affected lactation mainly in the first week or two. The data indicate that nitrogen intake rather than energy intake limited milk production. Irrespective of the amount of energy in the milk, the heat increment due to feeding was 20% smaller for lactating than for dry fatteningewes. It is suggested that efficient use of acetate by the mammary gland permits more efficient lipogenesis by other tissues.

Effects of substrate and hypoxia on smooth muscle metabolism and contraction

1989 ◽  
Vol 256 (4) ◽  
pp. C719-C727 ◽  
Author(s):  
I. R. Wendt
Keyword(s):  
Smooth Muscle ◽  
Oxygen Consumption ◽  
Urinary Bladder ◽  
Heat Production ◽  
Lactate Production ◽  
Muscle Metabolism ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Sufficient Energy ◽  
Rabbit Urinary Bladder

Suprabasal heat production, oxygen consumption, and lactate production were measured, together with force, in 30-s isometric contractions of longitudinal smooth muscle from rabbit urinary bladder at 27 degrees C. Either glucose or pyruvate was provided as exogenous substrate. Under aerobic conditions with glucose as substrate, force averaged 95 mN/mm2 and heat production 121 mJ/g. Oxygen consumption (0.18 mumol/g) could account for only two-thirds of the total energy expenditure represented as heat production. The remaining one-third was accounted for by aerobic lactate production (0.36 mumol/g). When pyruvate replaced glucose as substrate, both the force developed and the total heat liberated were unchanged. Oxygen consumption, however, increased by approximately 40% (to 0.25 mumol/g) and was able to fully account for the measured heat production. The frequency of spontaneous contractions under aerobic conditions was always reduced in the presence of pyruvate. Under anaerobic conditions force was essentially unaltered, and heat production was only slightly reduced (101 mJ/g) with glucose present. Lactate production increased threefold over that under aerobic conditions. With pyruvate as substrate both force and heat production declined markedly (to less than 5% of the aerobic values). The results indicate that under aerobic conditions and with glucose as substrate, smooth muscle of rabbit urinary bladder generates about one-third of its suprabasal energy requirements through glycolysis and that glycolysis can be further accelerated under anaerobic conditions to provide sufficient energy to sustain contraction. If pyruvate replaces glucose as substrate, the metabolism shifts to being virtually all oxidative, and contraction can no longer be sustained in the absence of oxygen.

Recovery heat production of mammalian fast- and slow-twitch muscles

1976 ◽  
Vol 230 (6) ◽  
pp. 1637-1643 ◽  
Author(s):  
IR Wendt ◽  
CL Gibbs
Keyword(s):  
Heat Production ◽  
Total Heat ◽  
Anaerobic Conditions ◽  
A Value ◽  
Glycolytic Activity ◽  
Slow Twitch ◽  
Initial Recovery ◽  
Fast Twitch ◽  
Mitochondrial Oxidative Metabolism ◽  
Initial Heat

Relationships between initial heat and recovery heat in fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus (SOL) muscles of the rat have been investigated by estimating the ratio of total heat (initial + recovery) to estimated initial heat. Results obtained from SOL agreed well with earlier data from amphibian skeletal muscle and indicated that in tetanic contractions of SOL the ratio,total heat/initial heat, was slightly greater than 2. Experiments on EDL revealed complexities not previously reported for amphibian muscle. Anaerobic total heat production by EDL was as much as 75% of aerobic heat production. When the initial heat was estimated under anaerobic conditions and with iodacetate present, the apparent ratio of total heat/initial heat in tetanic contractions of EDL approached a value of 2. The results are discussed in relation to the enzymatic characteristics of these muscles, and it is suggested that the recovery heat of SOL arises mainly from mitochondrial oxidative metabolism while that of EDL arises, to a large extent, from glycolytic activity.

scholarly journals The Disulfide Bond Formation Pathway Is Essential for Anaerobic Growth of Escherichia coli

2017 ◽  
Vol 199 (16) ◽  
Author(s):  
Brian M. Meehan ◽  
Cristina Landeta ◽  
Dana Boyd ◽  
Jonathan Beckwith
Keyword(s):  
Escherichia Coli ◽  
Disulfide Bond ◽  
Bond Formation ◽  
Anaerobic Growth ◽  
Strictly Anaerobic ◽  
Disulfide Bond Formation ◽  
Anaerobic Conditions ◽  
Content Type ◽  
E Coli ◽  
Laboratory Conditions

ABSTRACT Disulfide bonds are critical to the stability and function of many bacterial proteins. In the periplasm of Escherichia coli, intramolecular disulfide bond formation is catalyzed by the two-component disulfide bond forming (DSB) system. Inactivation of the DSB pathway has been shown to lead to a number of pleotropic effects, although cells remain viable under standard laboratory conditions. However, we show here that dsb strains of E. coli reversibly filament under aerobic conditions and fail to grow anaerobically unless a strong oxidant is provided in the growth medium. These findings demonstrate that the background disulfide bond formation necessary to maintain the viability of dsb strains is oxygen dependent. LptD, a key component of the lipopolysaccharide transport system, fails to fold properly in dsb strains exposed to anaerobic conditions, suggesting that these mutants may have defects in outer membrane assembly. We also show that anaerobic growth of dsb mutants can be restored by suppressor mutations in the disulfide bond isomerization system. Overall, our results underscore the importance of proper disulfide bond formation to pathways critical to E. coli viability under conditions where oxygen is limited. IMPORTANCE While the disulfide bond formation (DSB) system of E. coli has been studied for decades and has been shown to play an important role in the proper folding of many proteins, including some associated with virulence, it was considered dispensable for growth under most laboratory conditions. This work represents the first attempt to study the effects of the DSB system under strictly anaerobic conditions, simulating the environment encountered by pathogenic E. coli strains in the human intestinal tract. By demonstrating that the DSB system is essential for growth under such conditions, this work suggests that compounds inhibiting Dsb enzymes might act not only as antivirulents but also as true antibiotics.

scholarly journals Copper(I) transfer into metallothionein mediated by glutathione

1993 ◽  
Vol 292 (3) ◽  
pp. 673-676 ◽  
Author(s):  
A M D C Ferreira ◽  
M R Ciriolo ◽  
L Marcocci ◽  
G Rotilio
Keyword(s):  
Superoxide Dismutase ◽  
Protein Structure ◽  
Binding Sites ◽  
Emission Band ◽  
Strictly Anaerobic ◽  
Metal Bioavailability ◽  
Anaerobic Conditions ◽  
Fluorescence Maximum ◽  
Evolutionary Changes ◽  
Metal Composition

Rabbit liver metallothionein depleted of Cd(II) and Zn(II) was fully reconstituted using a Cu(I)-GSH complex under strictly anaerobic conditions. Anaerobic fluorescence titration, using an emission band at 625 nm which is diagnostic of the correct insertion of Cu(I) into the thiolate clusters of metallothionein, showed that the fluorescence maximum was obtained on addition of as many Cu(I) equivalents as the available Cu(I)-binding sites in the protein (i.e. 12). Binding was nearly complete within 1 min, and Cu(I)-GSH was much more efficient than Cu(I)-thiourea or Cu(I)-acetonitrile in metallothionein reconstitution. In air, full reconstitution was obtained with stoichiometric copper only when an excess of GSH was present in the reaction mixture. Cu(I)-GSH was also able to displace Zn(II) and Cd(II) from natural metallized thionein. It is concluded that: (a) Cu(I)-GSH is a potential physiological Cu(I) carrier, not only for Cu2+/Zn2+ superoxide dismutase [Ciriolo, Desideri, Paci and Rotilio (1990) J. Biol. Chem. 265, 11030-11034] but also for metallothionein; (b) in the case of metallothionein, physiological concentrations of GSH protect the protein from autoxidation in air and facilitate Cu(I)-thiolate exchange; (c) the natural metal composition of metallothionein may be related to metal bioavailability rather than to evolutionary changes in protein structure.

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