scholarly journals Modeling the Dynamics of Pigment Content in Cells of Dunaliella Salina Teod. Unicellular Alga at the Stage of Carotenogenesis

2019 ◽  
Vol 14 (1) ◽  
pp. 279-289 ◽  
Author(s):  
A.S. Lelekov ◽  
A.B. Borovkov ◽  
T.M. Novikova ◽  
I.N. Gudvilovich ◽  
A.L. Avsiyan ◽  
...  
Keyword(s):  
Salt Water ◽  
Radiation Energy ◽  
Specific Rate ◽  
Induction Phase ◽  
Partial Recovery ◽  
Mineral Components ◽  
Key Enzyme ◽  
Secondary Carotenoids ◽  
External Conditions ◽  
In Cells

The work is focused on modeling of chlorophyll and carotenoids content dynamics in the in cells of the unicellular algae D. salina, living in salt water, at carotenogenesis induction phase. A mathematical model of pigments content in microalgae cells, which experience excess of light energy and the limit of nutrient medium mineral components, is proposed. The model is based on assumption, that observed rate of variation in pigment concentration is an algebraic sum of the rates of synthesis, photodestruction and partial recovery of photo-oxidized pigments. The rate of secondary carotenoids synthesis does not depend on external conditions and is determined by the quantity of key enzyme complex and its turnover rate. The rate of secondary carotenoids and chlorophyll photodestruction depends on the effective light intensity and is proportional to the amount of absorbed photosynthetically active radiation energy. The verification of the derived equations was conducted in the course of D. salina cultivation at the carotenogenesis stage. The specific rate of chlorophyll a photodestruction was determined, which resulted in 0.12 days–1. The secondary carotenoids concentration increases up to the maximum value, which is determined by the ratio of synthesis and photodestruction specific rates, as well as the maximum culture density. Under conditions of natural light in the Sevastopol region, the maximum concentration of carotenoids was 18.33 mg/l or 0.73 g/m2.

Interaction of interferon with cells: characteristic of the induction of interferon uptake in relation to interferon antiviral activity

1970 ◽  
Vol 16 (11) ◽  
pp. 1087-1093 ◽  
Author(s):  
Edward T. Sheaff ◽  
Robert B. Stewart
Keyword(s):  
Antiviral Activity ◽  
Exposure Time ◽  
Low Ph ◽  
Induction Phase ◽  
Uptake System ◽  
Antiviral State ◽  
Factors Influencing ◽  
In Cells

A study of the factors influencing the development of an interferon-induced antiviral state indicated that the induction phase of the interferon "uptake" system was dependent on interferon concentration and exposure time of cells to interferon. The same parameters were found to affect the development of antiviral activity when a greater concentration of interferon was applied to cells which had been induced. Low pH was found to affect, adversely, the development of an antiviral state in cells exposed to interferon. This effect was at the induction rather than the uptake level of interferon action.

scholarly journals Simple binding of protein kinase A prior to phosphorylation allows CFTR anion channels to be opened by nucleotides

2020 ◽  
Vol 117 (35) ◽  
pp. 21740-21746
Author(s):  
Csaba Mihályi ◽  
Iordan Iordanov ◽  
Beáta Töröcsik ◽  
László Csanády
Keyword(s):  
Cystic Fibrosis ◽  
Protein Kinase ◽  
Salt Water ◽  
Anion Channel ◽  
Large Network ◽  
Channel Activation ◽  
Incurable Disease ◽  
Cftr Mutations ◽  
In Cells ◽  
R Domain

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) anion channel is essential for epithelial salt–water balance. CFTR mutations cause cystic fibrosis, a lethal incurable disease. In cells CFTR is activated through the cAMP signaling pathway, overstimulation of which during cholera leads to CFTR-mediated intestinal salt–water loss. Channel activation is achieved by phosphorylation of its regulatory (R) domain by cAMP-dependent protein kinase catalytic subunit (PKA). Here we show using two independent approaches––an ATP analog that can drive CFTR channel gating but is unsuitable for phosphotransfer by PKA, and CFTR mutants lacking phosphorylatable serines––that PKA efficiently opens CFTR channels through simple binding, under conditions that preclude phosphorylation. Unlike when phosphorylation happens, CFTR activation by PKA binding is completely reversible. Thus, PKA binding promotes release of the unphosphorylated R domain from its inhibitory position, causing full channel activation, whereas phosphorylation serves only to maintain channel activity beyond termination of the PKA signal. The results suggest two levels of CFTR regulation in cells: irreversible through phosphorylation, and reversible through R-domain binding to PKA––and possibly also to other members of a large network of proteins known to interact with the channel.

scholarly journals Markov Fatigue in Single Crystal Airfoils

1992 ◽  
Author(s):  
Charles Annis ◽  
Daniel P. De Luca
Keyword(s):  
Markov Process ◽  
Single Crystal ◽  
Damage Accumulation ◽  
Specific Rate ◽  
Complex Behavior ◽  
Damage Mechanisms ◽  
Turbine Engine ◽  
Microstructural Damage ◽  
Real Physical Process ◽  
External Conditions

This paper considers the influence of microstructure on macrobehavior in single crystal airfoils by treating the micromechanics of damage accumulation as a Markov process. Single Crystal Fatigue (SCF) is a result of several, simultaneous (competing), damage mechanisms, which are selectively favored by particular combinations of external conditions. As with any real physical process, SCF is also influenced by a stochastic component. This probabilistic influence can be exploited to help explain the macrobehavior. We begin with a description of single crystal materials and how they differ from more conventional (isotropic) alloys. Relationships are suggested among the more probable of several competing microstructural damage mechanisms and specific rate-controlling parameters. The states of microstructural damage are then described and catalogued, and the various avenues of damage accumulation are investigated. Next, the Markov paradigm is reviewed as it applies to these materials. Finally, a Markov model is presented to describe the rather complex behavior observed in single crystals, and its use in lifing gas turbine engine airfoils is discussed.

scholarly journals Rod and cone visual cycle consequences of a null mutation in the 11-cis-retinol dehydrogenase gene in man

2000 ◽  
Vol 17 (5) ◽  
pp. 667-678 ◽  
Author(s):  
ARTUR V. CIDECIYAN ◽  
FRANÇOISE HAESELEER ◽  
ROBERT N. FARISS ◽  
TOMAS S. ALEMAN ◽  
GEENG-FU JANG ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Dimensional Structure ◽  
Null Mutation ◽  
Partial Recovery ◽  
Retinol Dehydrogenase ◽  
Rods And Cones ◽  
Key Enzyme ◽  
Kinetics Of

Vertebrate vision starts with photoisomerization of the 11-cis-retinal chromophore to all-trans-retinal. Biosynthesis of 11-cis-retinal is required to maintain vision. A key enzyme catalyzing the oxidation of 11-cis-retinol is 11-cis-retinol dehydrogenase (11-cis-RDH), which is encoded by the RDH5 gene. 11-cis-RDH is expressed in the RPE and not in the neural retina. The consequences of a lack of 11-cis-RDH were studied in a family with fundus albipunctatus. We identified the causative novel RDH5 mutation, Arg157Trp, that replaces an amino acid residue conserved among short-chain alcohol dehydrogenases. Three-dimensional structure modeling and in vitro experiments suggested that this mutation destabilizes proper folding and inactivates the enzyme. Studies using RPE membranes indicated the existence of an alternative oxidizing system for the production of 11-cis-retinal. In vivo visual consequences of this null mutation showed complex kinetics of dark adaptation. Rod and cone resensitization was extremely delayed following full bleaches; unexpectedly, the rate of cone recovery was slower than rods. Cones showed a biphasic recovery with an initial rapid component and an elevated final threshold. Other unanticipated results included normal rod recovery following 0.5% bleach and abnormal recovery following bleaches in the 2–12% range. These intermediate bleaches showed rapid partial recovery of rods with transitory plateaux. Pathways in addition to 11-cis-RDH likely provide 11-cis-retinal for rods and cones and can maintain normal kinetics of visual recovery but only under certain constraints and less efficiently for cone than rod function.

scholarly journals Calibration of a Single-Cell Calorimeter in a New Transient-state Test Bench

2020 ◽  
Vol 225 ◽  
pp. 04009
Author(s):  
J. Burn ◽  
C. Reynard-Carette ◽  
M. Carette ◽  
A. Lyoussi ◽  
A. Volte ◽  
...  
Keyword(s):  
Single Cell ◽  
Nuclear Research ◽  
Transient State ◽  
Radiation Energy ◽  
Thermal Design ◽  
Nuclear Radiation ◽  
State Test ◽  
External Conditions ◽  
New Sensors ◽  
Energy Deposition Rate

The nuclear radiation energy deposition rate is a key value for the thermal design of experiments, on materials and nuclear fuels, carried out in experimental channels of nuclear research reactors. Studies are led for two kinds of sensor currently dedicated to quantifying this value and corresponding to calorimeter. Development of new sensors but also improvement of their calibration and their associated interpretation methods are necessary. These aims are possible by many ways such as numerical simulations of sensor, characterizations under laboratory conditions and experimental campaign under irradiation conditions. The calibration step under non-irradiation conditions represents a crucial phase. This phase requires the development of specific benches. The present paper focuses on a new thermal-transient bench and its use to perform calibration of a polish single-cell calorimeter. The new bench is detailed. First studies of the influence of external conditions (temperature, velocity) on the calorimeter sensitivity are presented and discussed.

scholarly journals Distribution Patterns of Ornithine Decarboxylase in Cells and Tissues: Facts, Problems, and Postulates

2002 ◽  
Vol 50 (9) ◽  
pp. 1143-1160 ◽  
Author(s):  
Raymond G. Schipper ◽  
Albert A.J. Verhofstad
Keyword(s):  
Ornithine Decarboxylase ◽  
Cellular Localization ◽  
Distribution Patterns ◽  
Cellular Level ◽  
Physiological Status ◽  
Polyamine Biosynthesis ◽  
Key Enzyme ◽  
And Function ◽  
In Cells

Ornithine decarboxylase (ODC) is a key enzyme in polyamine biosynthesis. Increased polyamine levels are required for growth, differentiation, and transformation of cells. In situ detection of ODC in cells and tissues has been performed with biochemical, enzyme cytochemical, immunocytochemical, and in situ hybridization techniques. Different localization patterns at the cellular level have been described, depending on the type of cells or tissues studied. These patterns varied from exclusively cytoplasmic to both cytoplasmic and nuclear. These discrepancies can be partially explained by the (lack of) sensitivity and/or specificity of the methods used, but it is more likely that (sub)cellular localization of ODC is cell type-specific and/or depends on the physiological status (growth, differentiation, malignant transformation, apoptosis) of cells. Intracellular translocation of ODC may be a prerequisite for its regulation and function.

The contractile vacuole fluid discharge rate is determined by the vacuole size immediately before the start of discharge in Paramecium multimicronucleatum

1997 ◽  
Vol 200 (12) ◽  
pp. 1737-1744 ◽  
Author(s):  
Y Naitoh ◽  
T Tominaga ◽  
R Allen
Keyword(s):  
Discharge Rate ◽  
Contractile Vacuole ◽  
Pore Shape ◽  
Membrane Tension ◽  
Membrane Area ◽  
External Conditions ◽  
Line Passing ◽  
Planar Membrane ◽  
Precise Relationship ◽  
In Cells

The precise relationship between the rate of contractile vacuole fluid discharge and the vacuole diameter at the start of systole was determined in cells of Paramecium multimicronucleatum subjected to various external conditions. The rate of discharge was higher when the diameter was larger. When the rate of discharge was plotted against the diameter, the points fell around a single parabolic line passing through the origin and were independent of the external conditions employed. This implies that the rate of discharge is proportional to the square of the vacuole diameter. We have previously proposed a hypothesis in which membrane tension in the contractile vacuole is altered as its planar membrane becomes tubular or as tubules become planar membrane (termed the membrane area-proportional tension hypothesis). We propose here that it is this change in membrane tension which determines the vacuole pore shape and sets the subsequent rate of fluid discharge.

Cytoplasmic Tubules in Cells Infected with Laryngotracheitis Virus

1969 ◽  
Vol 27 ◽  
pp. 376-377
Author(s):  
A. M. Watrach
Keyword(s):  
Tissue Culture ◽  
Small Proportion ◽  
Chicken Embryo ◽  
Culture Cells ◽  
Tissue Culture Cells ◽  
Morphologic Characteristics ◽  
Infectious Laryngotracheitis ◽  
Laryngotracheitis Virus ◽  
In Cells

During a study of the development of infectious laryngotracheitis (LT) virus in tissue culture cells, unusual tubular formations were found in the cytoplasm of a small proportion of the affected cells. It is the purpose of this report to describe the morphologic characteristics of the tubules and to discuss their possible association with the development of virus.The source and maintenance of the strain of LT virus have been described. Prior to this study, the virus was passed several times in chicken embryo kidney (CEK) tissue culture cells.

Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

1971 ◽  
Vol 29 ◽  
pp. 548-549
Author(s):  
Awtar Krishan ◽  
Dora Hsu
Keyword(s):  
Granular Material ◽  
Rna Synthesis ◽  
Culture Medium ◽  
Actinomycin D ◽  
Metabolic Inhibitors ◽  
Protein And Rna Synthesis ◽  
Apparent Reduction ◽  
Plant Alkaloids ◽  
In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

Detection of Nucleic Acids in Cells or Tissue Sections Using In situ Polymerase Chain Reaction (PCR)

1996 ◽  
Vol 54 ◽  
pp. 16-17
Author(s):  
J. R. Hully ◽  
K. R. Luehrsen ◽  
K. Aoyagi ◽  
C. Shoemaker ◽  
R. Abramson
Keyword(s):  
Nucleic Acids ◽  
Viral Infections ◽  
Anatomical Location ◽  
Rt Pcr ◽  
Reverse Transcription Pcr ◽  
Cellular Source ◽  
Gene Transcripts ◽  
Initial Description ◽  
In Cells

The development of PCR technology has greatly accelerated medical research at the genetic and molecular levels. Until recently, the inherent sensitivity of this technique has been limited to isolated preparations of nucleic acids which lack or at best have limited morphological information. With the obvious exception of cell lines, traditional PCR or reverse transcription-PCR (RT-PCR) cannot identify the cellular source of the amplified product. In contrast, in situ hybridization (ISH) by definition, defines the anatomical location of a gene and/or it’s product. However, this technique lacks the sensitivity of PCR and cannot routinely detect less than 10 to 20 copies per cell. Consequently, the localization of rare transcripts, latent viral infections, foreign or altered genes cannot be identified by this technique. In situ PCR or in situ RT-PCR is a combination of the two techniques, exploiting the sensitivity of PCR and the anatomical definition provided by ISH. Since it’s initial description considerable advances have been made in the application of in situ PCR, improvements in protocols, and the development of hardware dedicated to in situ PCR using conventional microscope slides. Our understanding of the importance of viral latency or viral burden in regards to HIV, HPV, and KSHV infections has benefited from this technique, enabling detection of single viral copies in cells or tissue otherwise thought to be normal. Clearly, this technique will be useful tool in pathobiology especially carcinogenesis, gene therapy and manipulations, the study of rare gene transcripts, and forensics.

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