Search

Start Over Format bez média

31882. Virulent and attenuated lines of Leishmania major: DNA karyotypes and differences in metalloproteinase GP63

Creator:
Sádlová, Jovana, Volf, Petr, Victoir, Kathleen, Dujardin, Jean-Claude, and Votýpka, Jan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Phlebotomus, sand flies, Leishmania major, virulence, leishmanolysin, LPG, proteolytical activity, genomic organisation, minichromosomes, and LD1
Language:
English
Description:
The Leishmania metalloproteinase GP63 has been reported to play important roles mainly in resistance of promastigotes to complement-mediated lysis and in interaction with macrophage receptors. On the other hand, its function in insect vectors is still unclear. We compared the structure and dosage of gp63 genes and the activity of GP63 in Leishmania major Yakimoff et Schokhor strains and lines differing in virulence for mice and ability to develop in sand flies. The results demonstrate considerable variability in amount and proteolytical activity of GP63 among L. major strains although genomic changes in the gp63 locus were not found. Attenuated LV561/AV line showed low amount and low enzymatic activity of GP63. Serial passages of attenuated parasites through either Phlebotomus duboscqi Neveu-Lemaire or through mice led to a recovery of GP63 proteolytical activity to the level present in virulent LV561/V line. Overexpression of GP63 was found in two L. major strains (L119, Neal) with defective lipophosphoglycan (LPG); both these strains were capable to cause mice infection but unable to survive and multiply in sand flies. Differences were found also in karyotypes and in amount of minichromosomes amplified in some lines of the LV561 strain. The results suggest that parasite virulence is not simply correlated with the activity of GP63; however, this enzyme plays a significant role in association with other surface molecules, especially LPG. Overexpression of GP63 can compensate LPG defect in the vertebrate host but in sand flies both molecules fulfil quite different functions and the defect in LPG is lethal for the parasite. On the other hand, linear minichromosomes of about 200 kb found in some lines of the LV561 strain are associated with development in vitro and in the vector but they are not essential for the infection of the vertebrate host.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

31884. Virus-induced changes in photosynthetic parameters and peroxidase isoenzyme contents in tomato (Solanum lycopersicum L.) plants

Creator:
Huseynova, I. M., Mirzayeva, S. M., Sultanova, N. F., Aliyeva, D. R., Mustafayev, N. Sh., and Aliyev, J. A.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
chlorofyl, karotenoidy, chlorophyll, carotenoids, tobamovirus, efektivita fotosystému II, tylakoidní membránové proteiny, peroxidace lipidů, peroxidázové aktivity, photosystem II efficiency, thylakoid membrane proteins, lipid peroxidation, peroxidase activity, 2, and 581
Language:
Multiple languages
Description:
Tomato samples were collected from the field of Absheron peninsula in Azerbaijan in order to evaluate the incidence of main Tobamoviruses. According to results of serological and molecular tests, Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), and Pepper mild mottle virus (PMMoV) were detected as single and mixed infections (TMV + PMMoV; ToMV + PMMoV) in various tomato samples. It was found that Tobamovirus infection caused an increase in the content of malondialdehyde, alterations in the activities of peroxidase enzymes and quantitative and qualitative changes in their molecular isoforms. A comparison of thylakoid membrane polypeptides from virus-infected leaves indicated a decrease in the content of the thylakoid membrane polypeptides with molecular masses of 123, 55, 47, 33, 28-24, 17, and 15 kD. PSII efficiency and the content of chlorophylls (a and b) were significantly lower in the virus-infected leaves., I. M. Huseynova, S. M. Mirzayeva, N. F. Sultanova, D. R. Aliyeva, N. Sh. Mustafayev, J. A. Aliyev., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

31885. Viscoelasticity of biological materials - measurement and practical impact on biomedicine

Creator:
Kuchařová, M., Stanislav Ďoubal, Petr Klemera, Petr Rejchrt, and Navrátil, M.
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, viskoelasticita, kosti, kůže (anatomie), viscoelasticity, bones, skin, arterial walls, 14, and 612
Language:
English
Description:
Mechanical behavior of biological structures under dynamic loading generally depends on elastic as well as viscous properties of biological materials. The significance of “viscous” parameters in real situations remains to be elucidated. Behavior of rheological models consisting of a combination of inertial body and two Voigt’s bodies were described mathematically with respect to inverse problem solution, and behavior in impulse and harmonic loadings was analyzed. Samples of walls of porcine and human aorta thoracica in transverse direction and samples of human bone (caput femoris, substantia compacta) were measured. Deformation responses of human skin in vivo were also measured. Values of elastic moduli of porcine aorta walls were in the interval from 102 kPa to 103 kPa, values of viscous coefficients were in the interval from 102 Pa.s to 103 Pa.s. The value of shear stress moduli of human caput femoris, substantia compacta range from 52.7 to 161.1 MPa, and viscous coefficients were in the interval from 27.3 to 98.9 kPa.s. The role of viscous coefficients is significant for relatively high loading frequencies - in our materials above 8 Hz in aorta walls and 5 Hz for bones. In bones, the viscosity reduced maximum deformation corresponding to short rectangular stress., M. Kuchařová, S. Ďoubal, P. Klemera, P. Rejchrt, M. Navrátil., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

31886. Viscosimetric analysis of the mechanism of ATP hydrolysis by pea chloroplast F1-ATPase

Creator:
Malyan, A. N.
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
kinetika, viskozita, kinetics, viscosity, ATP hydrolysis, F1-ATPase, 2, and 581
Language:
Multiple languages
Description:
Dependence of ATP hydrolysis kinetics by the chloroplast coupling factor (CF1) on medium viscosity was studied at varying temperatures. For samples with oxidized and reduced CF1 γ-subunit, this dependence was shown to be described by Cramers’ relationship k - (η/ηo)-n, where k is the reaction rate constant, η/ηo is the medium/water viscosity ratio, and 0 < n < 1. Transition of the γ-subunit from its reduced to oxidized state was accompanied by increasing n value, which is indicative of increasing friction losses between certain enzyme sections and the solution. The increased medium viscosity produced no effect on the reaction activation energy which appeared to be almost the same for the both enzyme states. The molecular mechanisms responsible for CF1 activity loss in viscous media are discussed., A.N. Malyan., and Obsahuje bibliografii
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

31887. Visegrádská čtyřka ocenila mladé badatele

Creator:
Havlů, Veronika, Kaluža, Luděk, and Petr Hlavinka
Format:
print, bez média, and svazek
Type:
article, články, model:article, and TEXT
Subject:
Věda. Všeobecnosti. Základy vědy a kultury. Vědecká práce, Kaluža, Luděk, Hlavinka, Petr, Visegrádská skupina, vědecká práce, podpora vědy a výzkumu, ceny a vyznamenání, scientific work, government aid to research, awards, 12, and 00
Language:
Czech
Description:
Veronika Havlů.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31888. Visfatin is actively secreted in vitro from U-937 macrophages, but only passively released from 3T3-L1 adipocytes and HepG2 hepatocytes

Creator:
Svoboda, P., Křížová, E., Čeňková, K., Vápenková, K., Jarmila Zídková, Václav Zídek, and Vojtěch Škop
Format:
print, bez média, and svazek
Type:
article, články, journal articles, model:article, and TEXT
Subject:
Fyziologie člověka a srovnávací fyziologie, fyziologie, physiology, nampt, visfatin, active secretion, adipocytes, hepatocytes, macrophages, 14, and 612
Language:
English
Description:
Visfatin is a multi-functional molecule that can act intracellularly and extracellularly as an adipokine, cytokine and enzyme. One of the main questions concerning visfatin is the mechanism of its secretion; whether, how and from which cells visfatin is released. The objective of this in vitro study was to observe the active secretion of visfatin from 3T3-L1 preadipocytes and adipocytes, HepG2 hepatocytes, U-937, THP-1 and HL-60 monocytes and macrophages. The amount of visfatin in media and cell lysate was always related to the intracellular enzyme, glyceraldehyde-3- phosphate dehydrogenase (GAPDH), to exclude the passive release of visfatin. Visfatin was not found in media of 3T3-L1 preadipocytes. In media of 3T3-L1 adipocytes and HepG2 hepatocytes, the ratio of visfatin to the amount of GAPDH was identical to cell lysates. Hence, it is likely that these cells do not actively secrete visfatin in a significant manner. However, we found that significant producers of visfatin are differentiated macrophages and that the amount of secreted visfatin depends on used cell line and it is affected by the mode of differentiation. Results show that 3T3-L1 adipocytes and HepG2 hepatocytes released visfatin only passively during the cell death. U-937 macrophages secrete visfatin in the greatest level from all of the tested cell lines., P. Svoboda, E. Křížová, K. Čeňková, K. Vápenková, J. Zídková, V. Zídek, V. Škop., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

31889. Visio Pauli: pozdněantické, respektive středověké opus apertum a jeho cesty latinským a českým středověkem (K metodologii bádání o jednom apokryfu)

Creator:
Jiroušková, Lenka
Format:
bez média and svazek
Type:
model:article and TEXT
Language:
Czech
Description:
The Visio Pauli, one of the most popular ‘Visions’ of the Middle Ages, constitutes the European form of an originally Oriental apocrypha known as ‘The Apocalypse of Paul’. On its journey through the Latin Middle Ages this text was used in many ways, which have fundamentally influenced its textual shape. The article outlines concisely the dissemination of the Visio Pauli in the Medieval West, its incorporation into new, shifting transmission patterns and textual combinations. It will be shown that the Eastern apocrypha from late Antiquity, the Paulus-Apocalypse, and its reworked European version, the Visio Pauli – the first a closed, the second an open text – in their complex transmission histories represent two entirely different realisations of one and the same material. The analysis, however, concentrates on the specific Bohemian redaction and its Old Czech version. The shape of a text will here be conceived in terms of its dissemination and concrete uses. The focus of the investigation consists, therefore, in the ways in which the variable and open were fixed, and the circumstances, consequences and description of this process. From material to text, from text to context, or, the other way round, from context to text – these are the aspects of the literary, structural, and functional analysis of the Visio Pauli in the context of cultural history. This approach constitutes an attempt to describe the text transmission differently from conventional textual criticism, and how to think about the shape of medieval texts in the context of their concrete use and function. The article is a reworking of a lecture given at Prague and Brno in 2008 and is essentially an abridged version of the author’s Ph.D. thesis, Die Visio Pauli: Wege und Wandlungen einer orientalischen Apokryphe im lateinischen Mittelalter unter Einschlus der alttschechischen und deutschsprachigen Textzeugen, Leiden and Boston: Brill (Mittellateinische Studien und Texte 34), 2006. It is the first written presentation of this research in Czech.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

Limit your search

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

Show values starting with
more »

View distribution

Current results range from 1626 to 2022

View larger »