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CO2 Production Rate (co2 + production_rate)
Selected AbstractsSingle QTL mapping and nucleotide-level resolution of a physiologic trait in wine Saccharomyces cerevisiae strainsFEMS YEAST RESEARCH, Issue 6 2007Philippe Marullo Abstract Natural Saccharomyces cerevisiae yeast strains exhibit very large genotypic and phenotypic diversity. However, the link between phenotype variation and genetic determinism is still difficult to identify, especially in wild populations. Using genome hybridization on DNA microarrays, it is now possible to identify single-feature polymorphisms among divergent yeast strains. This tool offers the possibility of applying quantitative genetics to wild yeast strains. In this instance, we studied the genetic basis for variations in acetic acid production using progeny derived from two strains from grape must isolates. The trait was quantified during alcoholic fermentation of the two strains and 108 segregants derived from their crossing. A genetic map of 2212 markers was generated using oligonucleotide microarrays, and a major quantitative trait locus (QTL) was mapped with high significance. Further investigations showed that this QTL was due to a nonsynonymous single-nucleotide polymorphism that targeted the catalytic core of asparaginase type I (ASP1) and abolished its activity. This QTL was only effective when asparagine was used as a major nitrogen source. Our results link nitrogen assimilation and CO2 production rate to acetic acid production, as well as, on a broader scale, illustrating the specific problem of quantitative genetics when working with nonlaboratory microorganisms. [source] Wing wear, aerodynamics and flight energetics in bumblebees (Bombus terrestris): an experimental studyFUNCTIONAL ECOLOGY, Issue 4 2001A. Hedenström Summary 1,Previous work has shown that wing wear increases mortality rate in bumblebees. Two proximate explanations have been suggested to account for this: increased energy flight costs and increased predation risk due to reduced manoeuvrability. 2,Wing wear was mimicked by experimentally clipping the forewing distal trailing edge, causing a 10% wing area reduction. Experimental and sham control bumblebees were induced to hover in a flight respirometry chamber for measuring metabolic rate of hovering. Simultaneous video and sound recordings were taken for wingbeat kinematic data required for an aerodynamic analysis. 3,In the experimental group with reduced wing area we measured increased wingbeat frequency, lift coefficient and induced power, but a reduced profile power. The mechanical power output, assuming perfect elastic storage in the flight system, remained largely unchanged after the wing-trimming treatment. 4,Metabolic flight costs (CO2 production rate) did not increase significantly in the reduced wing area group, which is in line with the aerodynamic power output. 5,Our results indicate that an increase of flight cost due to wing wear is not a likely explanation for increased mortality rate in bumblebees. Wing wear may, however, affect escape performance from predators. [source] Advantages of deuterium-labelled mixed triacylglycerol in studies of intraluminal fat digestionRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 2 2006Christine Slater The 13C-mixed triacylglcerol (MTG, 1,3-distearyl, 2-[1- 13C]octanoyl glycerol) breath test is a non-invasive measure of intraluminal fat digestion. Recovery of 13C in breath CO2 is incomplete (<50%) owing to sequestration of 13C into organic molecules via the tricarboxylic acid (TCA) cycle. In addition lack of knowledge of CO2 production rate (VCO2) during the test leads to errors in the calculated percentage dose recovered (PDR). 2H sequestration into organic molecules is low (,4%) and is not influenced by factors that affect VCO2 such as food intake or physical activity. After oxidation of 2H-labelled macromolecules, the label appears in body water, which can be sampled non-invasively in urine or saliva. After an overnight fast, two healthy adults consumed [2H]MTG (1,3-distearyl, 2-[2H15]octanoyl glycerol) and [13C]MTG (1,3 distearyl, 2-[1- 13C]octanoyl glycerol) simultaneously. Total body water (TBW) was measured by 18O dilution and also estimated from height and weight. Urine and saliva were sampled at baseline and for 10,h after consumption of the test meal. The abundance of 2HOH and H218O in urine and saliva was measured by continuous-flow isotope-ratio mass spectrometry. Cumulative PDR of 2H and 18O was calculated from the plateau enrichment, which was reached by 6,h in both saliva and urine. Recovery of 2H calculated using measured TBW was compared with that using an estimated value of TBW. Mean recovery of 2H in saliva was 99.3% and in urine was 96.4%. Errors introduced by estimating TBW were <5%. [2H]MTG could provide a simpler, more robust, indirect test of intraluminal fat digestion compared with the 13C-breath test. Further studies are required in pancreatic insufficient patients. Copyright © 2005 John Wiley & Sons, Ltd. [source] Aerobic batch cultivation in micro bioreactor with integrated electrochemical sensor arrayBIOTECHNOLOGY PROGRESS, Issue 1 2010Michiel van Leeuwen Abstract Aerobic batch cultivations of Candida utilis were carried out in two micro bioreactors with a working volume of 100 ,L operated in parallel. The dimensions of the micro bioreactors were similar as the wells in a 96-well microtiter plate, to preserve compatibility with the current high-throughput cultivation systems. Each micro bioreactor was equipped with an electrochemical sensor array for the online measurement of temperature, pH, dissolved oxygen, and viable biomass concentration. Furthermore, the CO2 production rate was obtained from the online measurement of cumulative CO2 production during the cultivation. The online data obtained by the sensor array and the CO2 production measurements appeared to be very reproducible for all batch cultivations performed and were highly comparable to measurement results obtained during a similar aerobic batch cultivation carried out in a conventional 4L bench-scale bioreactor. Although the sensor chip certainly needs further improvement on some points, this work clearly shows the applicability of electrochemical sensor arrays for the monitoring of parallel micro-scale fermentations, e.g. using the 96-well microtiterplate format. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Development of a system for the on-line measurement of carbon dioxide production in microbioreactors: Application to aerobic batch cultivations of Candida utilisBIOTECHNOLOGY PROGRESS, Issue 3 2009Michiel van Leeuwen Abstract We developed and applied a conductometric method for the quantitative online measurement of the carbon dioxide (CO2) production during batch cultivations of Candida utilis on a 100-,L scale. The applied method for the CO2 measurement consisted of absorption of the produced CO2 from the exhaust gas of the microbioreactor in an alkali solution, of which the conductivity was measured on-line. The measured conductivity change of the alkali solution showed a linear relation with the total amount of CO2 absorbed. After calibration of the CO2 measurement system, it was connected to a well of a 96-well microtiter plate. The mixing in the well was achieved by a magnetic stirrer. Using online measurement of the CO2 production during the cultivation, we show reproducible exponential batch growth of C. utilis on a 100-,L scale. The CO2 production measurements obtained from the microcultivation were compared with the CO2 production measurement in a 4-L bioreactor equipped with a conventional off-gas analyzer. The measurements showed that on-line measurement of the CO2 production rate in microbioreactors can provide essential data for quantitative physiological studies and provide better understanding of microscale cultivations. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 [source] | ||||||||||