Temperature dependence of absorption and fluorescence spectra of bacteriochlorophylls in vivo and in vitro

1972 ◽  
Vol 275 (2) ◽  
pp. 169-176 ◽  
Author(s):  
J.C. Goedheer
Keyword(s):  
Temperature Dependence ◽  
Fluorescence Spectra ◽  
Absorption And Fluorescence Spectra

Temperature-dependence of the DnaA–DNA interaction and its effect on the autoregulation of dnaA expression

2012 ◽  
Vol 449 (2) ◽  
pp. 333-341 ◽  
Author(s):  
Chiara Saggioro ◽  
Anne Olliver ◽  
Bianca Sclavi
Keyword(s):  
Temperature Dependence ◽  
Binding Sites ◽  
Dna Interaction ◽  
Bacterial Dna ◽  
Dnaa Protein ◽  
High Affinity ◽  
Key Factor

The DnaA protein is a key factor for the regulation of the timing and synchrony of initiation of bacterial DNA replication. The transcription of the dnaA gene in Escherichia coli is regulated by two promoters, dnaAP1 and dnaAP2. The region between these two promoters contains several DnaA-binding sites that have been shown to play an important role in the negative auto-regulation of dnaA expression. The results obtained in the present study using an in vitro and in vivo quantitative analysis of the effect of mutations to the high-affinity DnaA sites reveal an additional effect of positive autoregulation. We investigated the role of transcription autoregulation in the change of dnaA expression as a function of temperature. While negative auto-regulation is lost at dnaAP1, the effects of both positive and negative autoregulation are maintained at the dnaAP2 promoter upon lowering the growth temperature. These observations can be explained by the results obtained in vitro showing a difference in the temperature-dependence of DnaA–ATP binding to its high- and low-affinity sites, resulting in a decrease in DnaA–ATP oligomerization at lower temperatures. The results of the present study underline the importance of the role for autoregulation of gene expression in the cellular adaptation to different growth temperatures.

scholarly journals Establishment of Fluorescence Sensitization Method for Hydroxysafflor Yellow A

2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
CAO Haiyan ◽  
QIN Xiude ◽  
LIU Chen ◽  
ZHAO Xinzhe ◽  
MA Yuhui ◽  
...  
Keyword(s):  
Detection Limit ◽  
Fluorescence Intensity ◽  
Fluorescence Spectra ◽  
Pharmacological Effects ◽  
Absorption And Fluorescence Spectra ◽  
Hydroxysafflor Yellow A ◽  
T24 Cells ◽  
Fluorescence Sensitization ◽  
In Cells

As the main active ingredient in Chinese medicine safflower, hydroxysafflor yellow A (HSYA) has multiple pharmacological effects. In the work, the absorption and fluorescence spectra of HSYA under different environmental conditions (such as acidity, temperature, ions, viscosity, and surfactant) were investigated. The fluorescence intensity of HSYA varied greatly with acidity, temperature, viscosity, and surfactant, but was less affected by common cations and anions. Among various surfactants, we found that borax can significantly enhance the HSYA fluorescence intensity, and thus, a borax-HSYA sensitization system for HSYA fluorescence was established. In the optimized sensitization system, the fluorescence intensity of HSYA increased by 20 times and showed a good linearity with HSYA concentrations in the range of 0∼10 μM with a detection limit of 8 nM. The borax-HSYA sensitization system is nontoxic to T24 cells and mice and can be used for the fluorescence imaging of HSYA in cells, thereby providing an effective method for analyzing HSYA in vitro and monitoring its metabolism in cells.

Free energy and enthalpy of ATP hydrolysis in the sarcoplasm

1969 ◽  
Vol 174 (1036) ◽  
pp. 348-353 ◽  
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Temperature Dependence ◽  
Thermodynamic Data ◽  
Approximate Calculation ◽  
Atp Hydrolysis ◽  
Equilibrium Conditions ◽  
Thermodynamic Measurements

A rigorous calculation of the free energy available in vivo from ATP hydrolysis requires the following information which is not all available, namely: (i) intra­cellular pH, (ii) activities of all the species of reactants and products in sarcoplasm, (iii) thermodynamic data for all the reactions involved, including values for ionic strength and temperature dependence, and (iv) the extent of deviation from equilibrium conditions, i. e. during contraction. We shall discuss each of these factors in turn and state the assumptions made that allow the approximate calculation of the free energy made available by the following net reaction in the sarcoplasm: ATP +H 2 O → ADP + Pi + H + . (1) Although it can only be an approximation this calculation is useful since it will take into account recent thermodynamic measurements in vitro .

Synthesis and Self-aggregation of Zinc 20-Halogenochlorins as a Model for Bacteriochlorophylls c/d

1998 ◽  
Vol 02 (02) ◽  
pp. 159-169 ◽  
Author(s):  
YASUHIKO KUREISHI ◽  
HITOSHI TAMIAKI
Keyword(s):  
Fluorescence Spectra ◽  
Heavy Atom ◽  
Structural Models ◽  
Polar Solvents ◽  
Methyl Group ◽  
Visible Spectra ◽  
Self Aggregation ◽  
Atom Effect

Zinc 20-halogenochlorins 2(20- F ), 3(20- Cl ) and 4(20- Br ) were synthesized by halogenation of a chlorophyll a derivative at the 20-position as a model for bacteriochlorophyll ( BChl )c, which possesses a methyl group at the 20-position and 20-unsubstituted BChl d. Visible spectra in a polar tetrahydrofuran ( THF ) solution showed that 2-4 were monomeric and the planarity of the chlorin ring, was distorted with increasing bulkiness of the 20-substituent. Visible, circular dichroism and IR spectra revealed that 2-4 self-aggregated to form oligomers similarly with 20-unsubstituted 1 and BChls c/d in the heterogeneous thin film as well as in homogeneous non-polar solvents (1% (v/v) THF-hexane). Therefore, the in vitro self-aggregates of 2-4 are good structural models for in vivo BChls c/d self-aggregates, the main antenna components of photosynthetic green bacteria. Fluorescence spectra showed that monomeric 3 and 4 were less emissive than 1 and 2 due to the heavy atom effect which could not be observed in the oligomeric species, indicating that the in vitro aggregates should be promising as functional (light-harvesting) models.

scholarly journals Cytotoxicity of doxorubicin conjugated with C60 fullerene. Structural and in vitro studies

2019 ◽  
Vol 30 (6) ◽  
pp. 2327-2338
Author(s):  
Kamila Butowska ◽  
Witold Kozak ◽  
Magdalena Zdrowowicz ◽  
Samanta Makurat ◽  
Michał Rychłowski ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Fluorescence Spectra ◽  
C60 Fullerene ◽  
Absorption And Fluorescence Spectra ◽  
H Nmr ◽  
Low Toxicity ◽  
Pass Through ◽  
The Impact

Abstract Conjugating an anticancer drug of high biological efficacy but large cytotoxicity with a “transporting” molecule of low toxicity constitutes a valuable approach to design safe drug delivery system. In the present study, doxorubicin (DOX) a drug of large cardiotoxicity was chemically conjugated to a C60-fullerene. The synthesized molecule, a fullerene-doxorubicin conjugate (Ful-DOX), was characterized using the 1H NMR and MALDI TOF mass spectrometry. The absorption and fluorescence spectra and dynamic light scattering of the conjugate were recorded in an aqueous solution, while the impact on viability of several cancer cell lines of the free DOX and the conjugate was compared using the SRB and WST-1 assays. A low antiproliferative activity of the conjugate as compared to the free DOX is a consequence of the presence of fullerene moiety in the former, which is also responsible for the conjugate aggregation in an aqueous solution. Unlike free DOX, these aggregates cannot pass through the nuclear membrane (as demonstrated by the confocal microscopy measurements), which makes them marginally cytotoxic.

Induction and Differentiation of Dental Epithelium in Vivo and in Vitro

1982 ◽  
Vol 40 ◽  
pp. 142-145
Author(s):  
E. J. Kollar
Keyword(s):  
Connective Tissue ◽  
Oral Mucosa ◽  
Basal Lamina ◽  
Functional Derivatives ◽  
Specific Source ◽  
Dental Epithelium ◽  
Connective Tissue Stroma

The differentiation and maintenance of many specialized epithelial structures are dependent on the underlying connective tissue stroma and on an intact basal lamina. These requirements are especially stringent in the development and maintenance of the skin and oral mucosa. The keratinization patterns of thin or thick cornified layers as well as the appearance of specialized functional derivatives such as hair and teeth can be correlated with the specific source of stroma which supports these differentiated expressions.

Ultrastructural Correlations between Clonal Human Tumor Colonies and in Vivo Neoplasms

1982 ◽  
Vol 40 ◽  
pp. 210-211
Author(s):  
M.J. Murphy ◽  
R.R. Price ◽  
J.C. Sloman
Keyword(s):  
Cultured Cells ◽  
Human Tumor ◽  
Cell Type ◽  
Tumor Mass ◽  
Initial Cell ◽  
Cloning Assay ◽  
Human Tumor Cloning ◽  
The Relationship

The in vitro human tumor cloning assay originally described by Salmon and Hamburger has been applied recently to the investigation of differential anti-tumor drug sensitivities over a broad range of human neoplasms. A major problem in the acceptance of this technique has been the question of the relationship between the cultured cells and the original patient tumor, i.e., whether the colonies that develop derive from the neoplasm or from some other cell type within the initial cell population. A study of the ultrastructural morphology of the cultured cells vs. patient tumor has therefore been undertaken to resolve this question. Direct correlation was assured by division of a common tumor mass at surgical resection, one biopsy being fixed for TEM studies, the second being rapidly transported to the laboratory for culture.

Ultrastructure of melanocyte-keratinocyte interactions and pigment transfer in vitro

1978 ◽  
Vol 36 (2) ◽  
pp. 650-651
Author(s):  
Raul I. Garcia ◽  
Evelyn A. Flynn ◽  
George Szabo
Keyword(s):  
Direct Injection ◽  
Skin Pigmentation ◽  
Freeze Fracture ◽  
Pigment Granule ◽  
Time Lapse ◽  
Ultrastructural Level ◽  
Lanthanum Tracer ◽  
A Cell

Skin pigmentation in mammals involves the interaction of epidermal melanocytes and keratinocytes in the structural and functional unit known as the Epidermal Melanin Unit. Melanocytes(M) synthesize melanin within specialized membrane-bound organelles, the melanosome or pigment granule. These are subsequently transferred by way of M dendrites to keratinocytes(K) by a mechanism still to be clearly defined. Three different, though not necessarily mutually exclusive, mechanisms of melanosome transfer have been proposed: cytophagocytosis by K of M dendrite tips containing melanosomes, direct injection of melanosomes into the K cytoplasm through a cell-to-cell pore or communicating channel formed by localized fusion of M and K cell membranes, release of melanosomes into the extracellular space(ECS) by exocytosis followed by K uptake using conventional phagocytosis. Variability in methods of transfer has been noted both in vivo and in vitro and there is evidence in support of each transfer mechanism. We Have previously studied M-K interactions in vitro using time-lapse cinemicrography and in vivo at the ultrastructural level using lanthanum tracer and freeze-fracture.

In vitro and in vivo polysaccharides assembly: ultrastructural and cytochemical study of growing plant cell wall components.

1978 ◽  
Vol 36 (2) ◽  
pp. 434-435
Author(s):  
D. Reis ◽  
B. Vian ◽  
J. C. Roland
Keyword(s):  
Cell Wall ◽  
Self Assembly ◽  
Plant Cell Wall ◽  
Higher Plants ◽  
Three Dimensional ◽  
Cytochemical Study ◽  
Wall Components

Wall morphogenesis in higher plants is a problem still open to controversy. Until now the possibility of a transmembrane control and the involvement of microtubules were mostly envisaged. Self-assembly processes have been observed in the case of walls of Chlamydomonas and bacteria. Spontaneous gelling interactions between xanthan and galactomannan from Ceratonia have been analyzed very recently. The present work provides indications that some processes of spontaneous aggregation could occur in higher plants during the formation and expansion of cell wall.Observations were performed on hypocotyl of mung bean (Phaseolus aureus) for which growth characteristics and wall composition have been previously defined.In situ, the walls of actively growing cells (primary walls) show an ordered three-dimensional organization (fig. 1). The wall is typically polylamellate with multifibrillar layers alternately transverse and longitudinal. Between these layers intermediate strata exist in which the orientation of microfibrils progressively rotates. Thus a progressive change in the morphogenetic activity occurs.

Probing the ultrastructure of the mitotic and meiotic spindle in eggs: An expeditious approach based on semi-thin (0.25 μm) serial sections

1983 ◽  
Vol 41 ◽  
pp. 552-555
Author(s):  
Conly L. Rieder ◽  
S. Bowser ◽  
R. Nowogrodzki ◽  
K. Ross ◽  
G. Sluder
Keyword(s):  
Small Sample Size ◽  
Small Sample ◽  
Meiotic Spindle ◽  
Serial Sections ◽  
Mitotic Apparatus ◽  
Thin Sections ◽  
Cell Cycles ◽  
Ultrastructural Studies

Eggs have long been a favorite material for studying the mechanism of karyokinesis in-vivo and in-vitro. They can be obtained in great numbers and, when fertilized, divide synchronously over many cell cycles. However, they are not considered to be a practical system for ultrastructural studies on the mitotic apparatus (MA) for several reasons, the most obvious of which is that sectioning them is a formidable task: over 1000 ultra-thin sections need to be cut from a single 80-100 μm diameter egg and of these sections only a small percentage will contain the area or structure of interest. Thus it is difficult and time consuming to obtain reliable ultrastructural data concerning the MA of eggs; and when it is obtained it is necessarily based on a small sample size.We have recently developed a procedure which will facilitate many studies concerned with the ultrastructure of the MA in eggs. It is based on the availability of biological HVEM's and on the observation that 0.25 μm thick serial sections can be screened at high resolution for content (after mounting on slot grids and staining with uranyl and lead) by phase contrast light microscopy (LM; Figs 1-2).

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