Presence Of Phenylthiourea Research Articles

Synthesis of Allobetulin Using Phenylthiourea

A new method for preparing allobetulin via thermal rearrangement of betulin in the presence of phenylthiourea without using acidic reagents was found.

Ferritin H subunit gene is specifically expressed in melanophore precursor-derived white pigment cells in which reflecting platelets are formed from stage II melanosomes in the periodic albino mutant of Xenopus laevis.

“White pigment cells” are derived from melanophore precursors and contain both melanophore-specific and iridophore-specific pigment organelles. Whereas melanophores differentiate in the wild type regenerating tail, white pigment cells appear in the regenerating tail in the periodic albino mutant (a p /a p) of Xenopus laevis. The localization and density of white pigment cells in the mutant regenerating tail are similar to those of melanophores in the wild type regenerating tail. Here, white pigment cells in the mutant regenerating tail have been compared with melanophores in the wild type regenerating tail in the presence of phenylthiourea (PTU), which inhibits melanosome maturation in melanophores but does not affect reflecting platelet formation in white pigment cells. Ultrastructural analysis shows that reflecting platelet formation in white pigment cells is different from that in iridophores. Reflecting platelets in iridophores are formed from spherical vesicles with electron-dense material, whereas they are formed from stage II melanosomes characteristic of melanophore precursors in white pigment cells. Ultrastructural features of pigment organelles, except reflecting platelets, are similar between mutant melanophores and white pigment cells. In an attempt to identify specific genes in white pigment cells, a subtracted cDNA library enriched for mutant cDNAs has been prepared. Subtracted cDNA fragments have been cloned and selected by whole mount in situ hybridization. Among cDNA fragments examined so far, the ferritin H subunit gene is specifically expressed in white pigment cells, but not in melanophores. Pigment organellogenesis and specific gene expression in white pigment cells are also discussed.

Enzyme activity in banana fruits rotted by Botryodiplodia theobromae Pat.

Peroxidase and polyphenol oxidase activities in fruits of two cultivars of banana, 'champa' and 'kanthali' rotted by <i>Botryodiplodia theobromae</i> Pat. was studied. The enzymes showed much higher activities in infected than that in uninfected 'tissues. Increase in peroxidase activity was evidently inhibited by cycloheximide. Polyphenol oxidase activity was also inhibited in presence of phenylthiourea and Na-diethyldithiocarbamate more strongly by the former. Increase in activities seemed to be due to increased sytheses of the enzymes. In an <i>in vitro</i> culture, the fungus exhibited some peroxidase but no polyphenoloxidase activity.

A zebrafish model for nevus regeneration

A zebrafish model for nevus regeneration

MATHEMATICAL AND QUANTUM CHEMICAL STUDIES FOR THE CORROSION INHIBITION OF STEEL IN HCL ACID

The application of empirical and quantum chemical models on the corrosion inhibition of steel in hydrochloric acid in presence of phenylthiourea (PTU) as corrosion inhibitor have been modeled. Two mathematical models were used, third order polynomial model and Arrhenius type equation model. Levenberg-Marquardt method was used to evaluate the coefficients of two Models. Two models were suitable to represent the corrosion rate data at different conditions. The correlation coefficient of third order model was 0.973, while for the Arrhenius type model was 0.919. The structure of inhibitor was optimized by ArgusLab 4.0.1 package. The quantum chemical parameters (EHOMO, ELUMO, ΔE, and dipole moment µ) were estimated by PM3-SCF method

THE EFFECT OF TEMPERATURE AND ACID CONCENTRATION ON POLARIZATION RESISTANCE FOR A CORROSION REACTION UNDER ACTIVATION CONTROL

The effect of temperature ( 30,40,50,and 600C) on the polarization resistance (Rp) has beenanalyzed for the corrosion of carbon steel in 1,3, and 5N HCl solution in absence & presence ofphenylthiourea(PHTU) as corrosion inhibitor.The polarization resistance was measured at abovementioned conditions using BETACRUNCH program developed by Green and Gandi[Green,1982]. i.e; Values of applied current densities at potentials of +20,+10,-10 mv and then -20,+10,-10mV(SCE) from corrosion potentials were used to obtain corrosion parameters: iCorr ,ba bc followed by applying the equation: Rp = ( ba bc )/ 2.303 x iCorr.( ba + bc ).It is observed that: (i) for a certain acid concentration the polarization resistance decreased with increase in temperatureand/or decrease in inhibitor concentration.(ii) for a certain temperature, the polarization resistance decreases with an increase in acid concentration in presence and absence of inhibitor.

The effect of temperature on the corrosion of mild steel in acidic media in the presence of some sulphur-containing organic compounds

The effects of methylthiourea (MTU), phenylthiourea (PTU) and thiobenzamide (TBA) on the corrosion of mild steel in 0.1 M H 2SO 4 solution at temperatures of 30 °C, 40 °C and 50 °C have been studied. AC impedance, polarization resistance measurement and polarization curves measurement techniques have been used to obtain experimental data. The percent inhibition efficiency (IE%) and activation energy ( E a) have been determined in the presence and in the absence of these compounds. The results showed that all compounds have good inhibtion properties at all temperatures studied. The value of activation energy ( E a) found in the presence of PTU and TBA is smaller than that in the uninhibited solution while it is greater in the presence of MTU. The reasons that cause the deviation of a Nyquist plot from a semicircle have been investigated. Differential capacitance ( Q dl) has been used instead of double layer capacitance ( C dl) to represent the experimental deviations of a Nyquist plot from a semicircle. Whether the difference in real impedance at lower and higher frequencies correspond with the charge transfer resistance ( R t) has been discussed by taking the resistance contribution of diffuse layer into account. The resistance measured with AC impedance technique has been divided into charge transfer resistance ( R t) and diffuse layer resistance ( R d). The corrosion current density ( i corr) values have been determined by making use of the variation of corrosion potential with pH.

Cytological events induced by arachidonic acid in potato tubers.

Necrosis of potato tuber cells is enhanced, after 24 h incubation, by arachidonic acid (AA), an elicitor of the hypersensitive response in Solarium tuberosum L. and also by Fenton's reagents (a hydroxyl radical-generating system) either alone or in association with AA. The phenomenon is independent of tuber age. In aged tubers, phenylthiourea (PTU) causes a significant reduction of AA-induced cell necrosis. Necrosis observed in the presence of PTU alone is lower than in other treatments, and neither different from the controls nor affected by-tuber age. Cell size is not affected by treatments or ageing. Nuclear hypertrophy occurs independently of tuber ape, with the highest values after treatment with AA and Fenton's reagents. Nucleolar extrusion is observed in all treatments but earliest in the presence of AA. AA also enhances the number of lignified parenchymal cells and, to a lesser extent, the number of traeheary elements.

Enhancement of expression of lens phenotype in cultures of pigmented epithelial cells by hyaluronidase in the presence of phenylthiourea

Pigmented epithelial cells isolated from 8–9-day-old chick embryos can transdifferentiate into lens-like cells at the terminal period of the third generation of culture. However, efficiency of this transdifferentiation is usually rather low. Phenylthiourea, a potent inhibitor of melanin synthesis, effectively enhances transdifferentiation of pigmented epithelial cells into lens-like cells in vitro. Lentoid bodies began to appear in the multilayered region of primary cultures of pigmented epithelial cells maintained in medium containing phenylthiourea at concentrations between 0.5 and 1.0 mM. Furthermore, the enhancing effect of phenylthiourea can be amplified with testicular hyaluronidase. Under these conditions, pigmented epithelial cells grow vigorously and lose their differentiative properties, efficiently switching their phenotype into lens-like cells some 20 days after initiation of culture in the presence of both substances. Semiquantitative analysis revealed that testicular hyaluronidase amplified the effect of phenylthiourea more than 100-fold. It has been suggested that phenotypic expression of pigmented epithelial cells during transdifferentiation can be regulated by manipulating the microenvironment in which these cells reside.

Cellular immune responses of spruce budworm larvae to Entomophthora egressa protoplasts and other test particles

The protoplast stage of two isolates of Entomophthora egressa developed normally and eventually produced conidiophores when injected into larvae of the spruce budworm, Choristoneura fumiferana. The spruce budworm hemocytes never made long-term contact with the protoplasts either in vivo or in vitro. The protoplasts made active, short-term contact with spruce budworm granulocytes both in vivo and in vitro. Total larval hemocyte counts (THC) initially declined when larvae were injected with protoplasts, growth medium (MGM), or Escherichia coli. The recovery rate to THC control levels was similar for MGM and protoplasts and supports the concept of nonrecognition of protoplasts by the hemocytes. The granulocytes were important in both nodulation and phagocytosis of E. coli and Bacillus cereus, whereas the plasmatocytes were important in phagocytosis. In in vitro studies, spruce budworm granulocytes did not adhere to rod-shaped hyphal bodies, spherical hyphal bodies, or germinating spherical hyphal bodies of E. egressa, whereas the granulocytes readily encapsulated the hyphae. There was no evidence for the production by the protoplasts of metabolites which might interfere with hemocyte adhesion. When protoplasts contacted Tenebrio molitor granulocytes, the protoplasts reacted by increasing the number of protoplasmic extensions and by granule discharge. The process of granule discharge may be an active protoplast defense mechanism. The sporangiospores of Absidia repens and Rhizopus nigricans adhered to spruce budworm granulocytes; however, the number of A. repens spores per granulocyte and the level of granulocytes with spores decreased in the presence of phenylthiourea. The adhesion of A. repens spores to granulocytes was enhanced by N-acetylglucosamine, whereas glucosamine, sucrose, fucose, fructose, arabinose, and galactose either had no effect on or reduced spore adhesion. Thus, the chitin (or its subunits) in the hyphal wall may initiate the granulocyte response.

The anodic dissolution of iron and the behaviour of some corrosion inhibitors investigated by the potentiodynamic method

The influence of the anion, of oxygen and of some corrosion inhibitors on the shape of the anodic polarization curve of iron has been investigated by the potentiodynamic method, under controlled conditions.For samples annealed in hydrogen atmosphere in N HClO4 the anodic polarization curve shows two distinct slopes, 60 mV at low current densities and of 30 mV at higher current densities. In N H2SO4 the slopes are respectively of 70 mV and 40 mV. A single slope of 60 mV is obtained in HCl solution. A comparison of these results is made with those obtained by other authors by the transient method.The small influence of iodide ions on the polarization curves obtained in the presence of phenylthiourea seems to demonstrate that this compound is adsorbed in molecular rather than ionic form. As expected, the inhibiting power of polybutanimine is increased by the presence of iodide ions.

Potentiodynamic measurements of polarization curves on armco iron in acid medium in the presence of thiourea derivatives

Anodic and cathodic polarization curves were obtained for Armco iron sheets, previously annealed under hydrogen, in 1 N HCl saturated with hydrogen. The measurements were carried out with a potentiodynamic apparatus, with potential varied at 2 V/hr. The solution flowed through the measuring cell at a velocity of 1 1/min. Similar curves were obtained in the presence of 10−5 and 10−3 M phenylthiourea (PHTU), respectively.The corrosion current densities obtained from extrapolation of polarization curves are compared with those obtained from the colorimetric determination of dissolved iron. The change in slope of the Tafel lines in the presence of PHTU, with respect to those obtained in the blank test, are discussed in the light of both the results of previous experiments and the factors that may arise in the presence of PHTU.