scholarly journals Studies on the, Comparative Physiology of Chara Australis 1. Growth Pattern and Gross Cytology of the Internodal Oell

1964 ◽  
Vol 17 (1) ◽  
pp. 49 ◽  
Author(s):  
Marie J Peebles FV Mercer ◽  
TC Chambers
Keyword(s):  
Growth Pattern ◽  
Unit Volume ◽  
Exponential Phase ◽  
Linear Phase ◽  
Comparative Physiology ◽  
Growth Phases ◽  
Internodal Cell ◽  
Chara Australis ◽  
Very High ◽  
In Cells

The growth of the internodal cell and its parts appears to be allometric. Two growth phases are recognized, an exponential phase in the young cells followed by a linear phase during which the internode expands by up to 200 mm in length. In the exponential phase the cytoplasm to vacuole ratio declines from a very high value to about 0�04--0�06 and then remains constant throughout the linear phase. In the linear phase the structure of the protoplast, at the light.microscope level, is similar for all cells; a unit volume of the protoplast appears similar in cells from 10 to 200 rum in length.

scholarly journals Studies on the Comparative Physiology of Chara Australis II. The Fine Structure of The Protoplast

1964 ◽  
Vol 17 (2) ◽  
pp. 372 ◽  
Author(s):  
TC CHAMBERS ◽  
FV MERCER
Keyword(s):  
Fine Structure ◽  
Unit Volume ◽  
Higher Plants ◽  
Linear Phase ◽  
Comparative Physiology ◽  
Thin Sections ◽  
Golgi Bodies ◽  
Constant Structure ◽  
Parenchyma Cells ◽  
Chara Australis

The fine structure of the internodal cells of G. australis in the linear phase of cell expansion is described from electron micrographs of thin sections of osmium. and permanganate-fixed material. . The static picture obtained is basically similar to that of the parenchyma cells of higher plants as established by electron-microscope observations. A unit volume of protoplast has the same fine structure in cells ranging from 1 em to many centimetres in length, and contains cell wall, plasmalemma, tonoplast, endoplasmic reticulum, golgi bodies, micro somes, mitochondria, chloro_ plasts, nuclei, and other inclusions. This constant structure may account for the constant metabolism per unit volume of protoplast during the linear phase of development. A brief discussion of the possible significance of this picture of the structure of the internodal protoplast to the functional activity of the cell is given.

scholarly journals Measuring and modeling energy and power consumption in living microbial cells with a synthetic ATP reporter

BMC Biology ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yijie Deng ◽  
Douglas Raymond Beahm ◽  
Steven Ionov ◽  
Rahul Sarpeshkar
Keyword(s):  
Power Consumption ◽  
Stationary Phases ◽  
Energy Levels ◽  
Circuit Model ◽  
Exponential Phase ◽  
Bacterial Cells ◽  
Growth Phases ◽  
E Coli ◽  
Living Organisms ◽  
In Cells

Abstract Background Adenosine triphosphate (ATP) is the main energy carrier in living organisms, critical for metabolism and essential physiological processes. In humans, abnormal regulation of energy levels (ATP concentration) and power consumption (ATP consumption flux) in cells is associated with numerous diseases from cancer, to viral infection and immune dysfunction, while in microbes it influences their responses to drugs and other stresses. The measurement and modeling of ATP dynamics in cells is therefore a critical component in understanding fundamental physiology and its role in pathology. Despite the importance of ATP, our current understanding of energy dynamics and homeostasis in living cells has been limited by the lack of easy-to-use ATP sensors and the lack of models that enable accurate estimates of energy and power consumption related to these ATP dynamics. Here we describe a dynamic model and an ATP reporter that tracks ATP in E. coli over different growth phases. Results The reporter is made by fusing an ATP-sensing rrnB P1 promoter with a fast-folding and fast-degrading GFP. Good correlations between reporter GFP and cellular ATP were obtained in E. coli growing in both minimal and rich media and in various strains. The ATP reporter can reliably monitor bacterial ATP dynamics in response to nutrient availability. Fitting the dynamics of experimental data corresponding to cell growth, glucose, acetate, dissolved oxygen, and ATP yielded a mathematical and circuit model. This model can accurately predict cellular energy and power consumption under various conditions. We found that cellular power consumption varies significantly from approximately 0.8 and 0.2 million ATP/s for a tested strain during lag and stationary phases to 6.4 million ATP/s during exponential phase, indicating ~ 8–30-fold changes of metabolic rates among different growth phases. Bacteria turn over their cellular ATP pool a few times per second during the exponential phase and slow this rate by ~ 2–5-fold in lag and stationary phases. Conclusion Our rrnB P1-GFP reporter and kinetic circuit model provide a fast and simple way to monitor and predict energy and power consumption dynamics in bacterial cells, which can impact fundamental scientific studies and applied medical treatments in the future.

scholarly journals A Three-phase Model for the Analysis of Sigmoid Patterns of Growth

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 761C-761
Author(s):  
J.H. Lieth ◽  
P.R. Fisher ◽  
R.D. Heins
Keyword(s):  
Shoot Elongation ◽  
Growth Function ◽  
Logistic Function ◽  
Exponential Phase ◽  
Linear Phase ◽  
Growth Phases ◽  
Three Phase ◽  
Richards Function ◽  
Saturation Phase ◽  
Over Time

A growth function was developed for describing the progression of shoot elongation over time. While existing functions, such as the logistic function or Richards function, can be fitted to most sigmoid data, we observed situations where distinct lag, linear, and saturation phases were observed but not well represented by these traditional functions. A function was developed that explicitly models three phases of growth as a curvilinear (exponential) phase, followed by a linear phase, and terminating in a saturation phase. This function was found to be as flexible as the Richards function and can be used for virtually any sigmoid data. The model behavior was an improvement over the Richards function in cases where distinct transitions between the three growth phases are evident. The model also lends itself well to simulation of growth using the differential equation approximation for the function.

scholarly journals Analysis of Dibenzothiophene Desulfurization in a Recombinant Pseudomonas putida Strain

2008 ◽  
Vol 75 (3) ◽  
pp. 875-877 ◽  
Author(s):  
Javier Calzada ◽  
Mar�a T. Zamarro ◽  
Almudena Alc�n ◽  
Victoria E. Santos ◽  
Eduardo D�az ◽  
...  
Keyword(s):  
Pseudomonas Putida ◽  
Exponential Growth ◽  
Exponential Phase ◽  
Cell Process ◽  
Growth Phases ◽  
Early Exponential Phase ◽  
Sharp Maximum ◽  
Resting Cell

ABSTRACT Biodesulfurization was monitored in a recombinant Pseudomonas putida CECT5279 strain. DszB desulfinase activity reached a sharp maximum at the early exponential phase, but it rapidly decreased at later growth phases. A model two-step resting-cell process combining sequentially P. putida cells from the late and early exponential growth phases was designed to significantly increase biodesulfurization.

scholarly journals AUTORADIOGRAPHIC DETECTION OF ANTIGENS IN CELLS USING TRITIUM-LABELED ANTIBODIES

1970 ◽  
Vol 18 (7) ◽  
pp. 490-497 ◽  
Author(s):  
K. OSTROWSKI ◽  
E. A. BARNARD ◽  
W. SAWICKI ◽  
T. CHORZELSKI ◽  
A. LANGNER ◽  
...  
Keyword(s):  
Acetic Anhydride ◽  
Fluorescent Marker ◽  
Isotopic Method ◽  
Relative Quantitation ◽  
Antibody Titers ◽  
Autoradiographic Detection ◽  
Very High ◽  
In Cells

Immunoglobulins specific for cellular antigens of several types were treated with 3H-acetic anhydride in conditions which were shown to introduce three to four 3H-acetyl groups per molecule, with very high retention of the antibody titers. Methods were established for application of these labeled globulins in an autoradiographic procedure. The results show that localization of cell-bound antigens can be demonstrated by this method, by silver grain concentrations at sites that correspond to those demonstrated by the same globulins labeled with a fluorescent marker. A control nonimmune globulin was reacted similarly and gave no labeling of the same tissues. The advantage of the isotopic method would be the relative quantitation that it is, in principle, capable of yielding.

scholarly journals Assessment of 3D MINFLUX data for quantitative structural biology in cells

2021 ◽  
Author(s):  
Kirti Prakash ◽  
Alistair Curd
Keyword(s):  
Quantitative Analysis ◽  
Structural Biology ◽  
Single Molecule ◽  
Structural Features ◽  
Localization Microscopy ◽  
Current State ◽  
New Development ◽  
Very High ◽  
Single Molecule Localization Microscopy ◽  
In Cells

MINFLUX is a promising new development in single-molecule localization microscopy, claiming a resolution of 1-3 nm in living and fixed biological specimens. While MINFLUX can achieve very high localisation precision, quantitative analysis of reported results leads us to dispute the resolution claim and question reliability for imaging sub-100-nm structural features, in its current state.

Coulometric microrespirometry

1982 ◽  
Vol 243 (1) ◽  
pp. R185-R192
Author(s):  
A. A. Heusner ◽  
J. P. Hurley ◽  
R. Arbogast
Keyword(s):  
Closed System ◽  
Unit Volume ◽  
O2 Consumption ◽  
Comparative Physiology ◽  
Organ Cultures ◽  
Temperature Range ◽  
Metabolic Studies ◽  
Upper Limit ◽  
Cuso4 Solution ◽  
Better Than

Capacitive coulometry is based on the automatic quantitative replacement of O2 consumed by an animal in a closed system with electrolytic O2, produced by discharging a capacitor through a CuSO4 solution. The sensitivity of the device is better than 0.1 nl. The unit volume of O2 produced (1 nl) is both accurate and precise within 1% in a temperature range from 2.8 to 40 degrees C. The upper limit of recordable O2 consumption is 1 ml/h. The microrespirometer can be autoclaved, making the technique ideally suited for metabolic studies in microbiology, cell and organ cultures, and comparative physiology.

scholarly journals Ethanol Stimulates Trehalose Production through a SpoT-DksA-AlgU-Dependent Pathway inPseudomonas aeruginosa

2019 ◽  
Vol 201 (12) ◽  
Author(s):  
Colleen E. Harty ◽  
Dorival Martins ◽  
Georgia Doing ◽  
Dallas L. Mould ◽  
Michelle E. Clay ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Quorum Sensing ◽  
Cell Density ◽  
Sigma Factor ◽  
Strong Support ◽  
Transcriptional Response ◽  
Exponential Phase ◽  
Fermentation Products ◽  
Content Type ◽  
In Cells

ABSTRACTPseudomonas aeruginosafrequently resides among ethanol-producing microbes, making its response to the microbially produced concentrations of ethanol relevant to understanding its biology. Our transcriptome analysis found that genes involved in trehalose metabolism were induced by low concentrations of ethanol, and biochemical assays showed that levels of intracellular trehalose increased significantly upon growth with ethanol. The increase in trehalose was dependent on the TreYZ pathway but not other trehalose-metabolic enzymes (TreS or TreA). The sigma factor AlgU (AlgT), a homolog of RpoE in other species, was required for increased expression of thetreZgene and trehalose levels, but induction was not controlled by the well-characterized proteolysis of its anti-sigma factor, MucA. Growth with ethanol led to increased SpoT-dependent (p)ppGpp accumulation, which stimulates AlgU-dependent transcription oftreZand other AlgU-regulated genes through DksA, a (p)ppGpp and RNA polymerase binding protein. Ethanol stimulation of trehalose also required acylhomoserine lactone (AHL)-mediated quorum sensing (QS), as induction was not observed in a ΔlasRΔrhlRstrain. A network analysis using a model, eADAGE, built from publicly availableP. aeruginosatranscriptome data sets (J. Tan, G. Doing, K. A. Lewis, C. E. Price, et al., Cell Syst 5:63–71, 2017, https://doi.org/10.1016/j.cels.2017.06.003) provided strong support for our model in whichtreZand coregulated genes are controlled by both AlgU- and AHL-mediated QS. Consistent with (p)ppGpp- and AHL-mediated quorum-sensing regulation, ethanol, even when added at the time of culture inoculation, stimulatedtreZtranscript levels and trehalose production in cells from post-exponential-phase cultures but not in cells from exponential-phase cultures. These data highlight the integration of growth and cell density cues in theP. aeruginosatranscriptional response to ethanol.IMPORTANCEPseudomonas aeruginosais often found with bacteria and fungi that produce fermentation products, including ethanol. At concentrations similar to those produced by environmental microbes, we found that ethanol stimulated expression of trehalose-biosynthetic genes and cellular levels of trehalose, a disaccharide that protects against environmental stresses. The induction of trehalose by ethanol required the alternative sigma factor AlgU through DksA- and SpoT-dependent (p)ppGpp. Trehalose accumulation also required AHL quorum sensing and occurred only in post-exponential-phase cultures. This work highlights how cells integrate cell density and growth cues in their responses to products made by other microbes and reveals a new role for (p)ppGpp in the regulation of AlgU activity.

scholarly journals Post-translational modification of the protein-synthesis initiation factor eIF-4D by spermidine in rat hepatoma cells

1986 ◽  
Vol 239 (2) ◽  
pp. 379-386 ◽  
Author(s):  
E W Gerner ◽  
P S Mamont ◽  
A Bernhardt ◽  
M Siat
Keyword(s):  
Growth Rates ◽  
Exponential Phase ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Polyamine Metabolism ◽  
Synthesis Rate ◽  
Post Translational Modification ◽  
Irreversible Inhibitor ◽  
Rat Hepatoma ◽  
In Cells

The rates of synthesis and turnover of the rare amino acid hypusine [N6-(4-amino-2-hydroxybutyl)-2,6-diaminohexanoic acid] in protein were studied in relationship to polyamine metabolism and growth rates in rat hepatoma tissue-culture (HTC) cells. Hypusine is selectively formed in the eukaryotic translation initiation factor eIF-4D, by a post-translational mechanism involving spermidine [Cooper, Park, Folk, Safer & Braverman (1983) Proc. Natl. Acad. Sci. U.S.A. 80, 1854-1857]. The half-life of the hypusine-containing protein was longer than 24 h. In cells whose intracellular spermidine pools had been initially depleted, by using DL-alpha-difluoromethylornithine (DFMO), maximum synthesis rates of hypusine in protein were 5-10 times higher, on restoration of endogenous spermidine contents by exogenous addition, than those observed in untreated exponential-phase cultures. In cells pretreated with DFMO, the rate of hypusine synthesis was constant for up to 1 h after the addition of 5 microM-spermidine, whereas endogenous spermidine contents varied from less than 1 to more than 10 nmol/mg of protein. However, the overall amount of hypusine formed, during the first 1 h after the addition of various concentrations of spermidine (0.05-10 microM) to the culture medium, was markedly dependent on the final endogenous spermidine content achieved at the end of the 1 h measurement interval. Early in exponential-phase growth, protein-bound hypusine was synthesized at a rate of 1-2 pmol/h per mg of protein. This rate decreased to less than 0.5 pmol/h per mg of protein when cell growth rates decreased as cultures reached high cell densities. Analysis of the polyamine substrate specificity for hypusine formation showed that N1-acetylspermidine did not compete with spermidine in the reaction, nor did N1-(buta-2,3-dienyl)-N2-methylbutane-1,4-diamine, and irreversible inhibitor of polyamine oxidase, block the reaction. On the basis of comparative radiolabelling experiments, spermine was either a poor substrate, or not a substrate, for hypusine formation. These results confirm that spermidine is the likely precursor of the aminohydroxybutyl moiety of hypusine, and show that overall hypusine formation, but not necessarily the synthesis rate, is dependent on the endogenous spermidine concentration, especially under conditions where spermidine concentrations are initially low, as is the case after DFMO treatment, and then increase.

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