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11.
Adrenocortical responses to diverse stressful situations (dehydration, formaldehyde treatment and salt loading) were studied in the adult female soft-shelled turtle, Lissenmys p. punctata. Dehydration, formaldehyde treatment (formalin, 1%: 0.1 ml/100 g body weight daily) or salt loading (NaCl, 1%: 0.1 ml/100 g body weight daily) treatments consecutively for 7 days caused hypertrophy of the adrenocortical cells with their nuclear diameter increased, and depletions of adrenal cholesterol and ascorbic acid concentrations followed by decreased acid phosphatase and alkaline phosphatase activities in turtles. Corticosterone levels were elevated in both the adrenal gland and serum of turtles after dehydration and formalin stress, but the hormone level remained unaltered after salt loading in turtles. The results suggest active involvement of adrenal cortex in stress for homeostasis in Lissemys turtles. 相似文献
12.
Effect of green tea polyphenols on angiogenesis induced by an angiogenin-like protein 总被引:2,自引:0,他引:2
Maiti TK Chatterjee J Dasgupta S 《Biochemical and biophysical research communications》2003,308(1):64-67
Angiogenesis is a fundamental process by which new blood vessels are formed. The angiogenesis process is induced by several growth factors. Among them angiogenin is the most potent blood vessel inducer known. In this paper, we have investigated the effect of green tea polyphenols, mainly the catechins, on an angiogenin-like protein induced angiogenesis process. The angiogenin-like protein was isolated from goat serum and the effect of green tea components was tested by the chicken chorioallantoic membrane (CAM) assay. The results show that green tea components are capable of reducing the vascularization on CAM that is induced by the angiogenin-like protein. 相似文献
13.
Nitesh Kumar Somlata Mohit Mazumder Priyanka Dutta Sankar Maiti Samudrala Gourinath 《PLoS pathogens》2014,10(9)
Entamoeba histolytica is a protist parasite that is the causative agent of amoebiasis, and is a highly motile organism. The motility is essential for its survival and pathogenesis, and a dynamic actin cytoskeleton is required for this process. EhCoactosin, an actin-binding protein of the ADF/cofilin family, participates in actin dynamics, and here we report our studies of this protein using both structural and functional approaches. The X-ray crystal structure of EhCoactosin resembles that of human coactosin-like protein, with major differences in the distribution of surface charges and the orientation of terminal regions. According to in vitro binding assays, full-length EhCoactosin binds both F- and G-actin. Instead of acting to depolymerize or severe F-actin, EhCoactosin directly stabilizes the polymer. When EhCoactosin was visualized in E. histolytica cells using either confocal imaging or total internal reflectance microscopy, it was found to colocalize with F-actin at phagocytic cups. Over-expression of this protein stabilized F-actin and inhibited the phagocytic process. EhCoactosin appears to be an unusual type of coactosin involved in E. histolytica actin dynamics. 相似文献
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Post-translational modification (PTM) of RNA binding proteins (RBPs) play a very important role in determining their binding to cognate RNAs and therefore regulate the downstream effects. Lysine can undergo various PTMs and thereby contribute to the regulation of different cellular processes. It can be reversibly acetylated and methylated using a pool of respective enzymes, to act as a switch for controlling the binding efficiency of RBPs. Here we have delineated the thermodynamic and kinetic effects of N-acetylation and N-monomethylation of lysine on interaction between HIV-1 TAR RNA and its cognate binder Tat peptide ( a model system). Our results indicate that acetylation of lysine 50 (K50), leads to eight- fold reduction in binding affinity, originating exclusively from entropy changes whereas, lysine 51 (K51) acetylation resulted only in three fold decrease with large enthalpy-entropy compensation. The measurement of kinetic parameters indicated major change (4.5 fold) in dissociation rate in case of K50 acetylation however, K51 acetylation showed similar effect on both association and dissociation rates. In contrast, lysine methylation did not affect the binding affinity of Tat peptide to TAR RNA at K50, nonetheless three fold enhancement in binding affinity was observed at K51 position. In spite of large enthalpy-entropy compensation, lysine methylation seems to have more pronounced position specific effect on the kinetic parameters. In case of K50 methylation, simultaneous increase was observed in the rate of association and dissociation leaving binding affinity unaffected. The increased binding affinity for methylated Tat at K51 stems from faster association rate with slightly slower dissociation rate. 相似文献
17.
Abstract The binding of the benzodioxolo-benzoquinolizine alkaloid, berberine chloride to natural and synthetic DNAs has been studied by intrinsic and extrinsic circular dichroic measurements. Binding of berberine causes changes in the circular dichroism spectrum of DNA as shown by the increase of molar ellipticity of the 270nm band, but with very little change of the 240nm band. The molar ellipticity at the saturation depends strongly on the base composition of DNA and also on salt concentration, but always larger for the AT rich DNA than the GC rich DNA The features in the circular dichroic spectral changes of berberine-synthetic DNA complexes were similar to that of native DNA but depends on the sequence of base pairs. On binding to DNA and polynucleotides, the alkaloid becomes optically active. The extrinsic circular dichroism developed in the visible absorption region (300–500nm) for the berberine-DNA complexes shows two broad spectral bands in the regions 425–440nm and 340–360nm with the maximum varying depending on base composition and sequence of DNA While the 425nm band shows less variation on the binding ratio, the 360nm band is remarkably dependent on the DNA/alkaloid ratio. The generation of the alkaloid associated extrinsic circular dichroic bands is not dependent on the base composition or sequence of base pairs, but the nature and magnitude of the bands are very much dependent on these two factors and also on the salt concentration. The interpretation of the results with respect to the modes of the alkaloid binding to DNA are presented. 相似文献
18.
Antoaneta B. M. Kroumova Dipak K. Sahoo Sumita Raha Michael Goodin Indu B. Maiti George J. Wagner 《Plant cell reports》2013,32(11):1771-1782
Key message
Phylloplanins are plant-derived, antifungal glycoproteins produced by leaf trichomes. Expression of phylloplanin-GFP fusion gene to the apoplast of a blue mold susceptible tobacco resulted in increased resistance to this pathogen.Abstract
Tobaccos and certain other plants secrete phylloplanin glycoproteins to aerial surfaces where they appear to provide first-point-of-contact resistance against fungi/fungi-like pathogens. These proteins can be collected by water washing of aerial plant surfaces, and as shown for tobacco and a sunflower phylloplanins, spraying concentrated washes onto, e.g., turf grass aerial surfaces can provide resistance against various fungi/fungi-like pathogens, in the laboratory. These results suggest that natural-product, phylloplanins may be useful as broad-selectivity fungicides. An obvious question now is can a tobacco phylloplanin gene be introduced into a disease-susceptible plant to confer endogenous resistance. Here we demonstrate that introduction of a tobacco phylloplanin gene—as a fusion with the GFP gene—targeted to the apoplasm can increase resistance to blue mold disease in a susceptible host tobacco. 相似文献19.
Gunjan Arora Andaleeb Sajid Mary Diana Arulanandh Richa Misra Anshika Singhal Santosh Kumar Lalit K. Singh Abid R. Mattoo Rishi Raj Souvik Maiti Sharmila Basu-Modak Yogendra Singh 《Biometals》2013,26(5):715-730
Bacillus anthracis Ser/Thr protein kinase PrkC (BasPrkC) is important for virulence of the bacterium within the host. Homologs of PrkC and its cognate phosphatase PrpC (BasPrpC) are the most conserved mediators of signaling events in diverse bacteria. BasPrkC homolog in Bacillus subtilis regulates critical processes like spore germination and BasPrpC modulates the activity of BasPrkC by dephosphorylation. So far, biochemical and genetic studies have provided important insights into the roles of BasPrkC and BasPrpC; however, regulation of their activities is not known. We studied the regulation of BasPrkC/BasPrpC pair and observed that Zn2+ metal ions can alter their activities. Zn2+ promotes BasPrkC kinase activity while inhibits the BasPrpC phosphatase activity. Concentration of Zn2+ in growing B. anthracis cells was found to vary with growth phase. Zn2+ was found to be lowest in log phase cells while it was highest in spores. This variation in Zn2+ concentration is significant for understanding the antagonistic activities of BasPrkC/BasPrpC pair. Our results also show that BasPrkC activity is modulated by temperature changes and kinase inhibitors. Additionally, we identified Elongation Factor Tu (BasEf-Tu) as a substrate of BasPrkC/BasPrpC pair and assessed the impact of their regulation on BasEf-Tu phosphorylation. Based on these results, we propose Zn2+ as an important regulator of BasPrkC/BasPrpC mediated phosphorylation cascades. Thus, this study reveals additional means by which BasPrkC can be activated leading to autophosphorylation and substrate phosphorylation. 相似文献
20.
Loss of CLPP alleviates mitochondrial cardiomyopathy without affecting the mammalian UPRmt
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Dominic Seiferling Karolina Szczepanowska Christina Becker Katharina Senft Steffen Hermans Priyanka Maiti Tim König Alexandra Kukat Aleksandra Trifunovic 《EMBO reports》2016,17(7):953-964
The mitochondrial matrix protease CLPP plays a central role in the activation of the mitochondrial unfolded protein response (UPRmt) in Caenorhabditis elegans. Far less is known about mammalian UPRmt signaling, although similar roles were assumed for central players, including CLPP. To better understand the mammalian UPRmt signaling, we deleted CLPP in hearts of DARS2‐deficient animals that show robust induction of UPRmt due to strong dysregulation of mitochondrial translation. Remarkably, our results clearly show that mammalian CLPP is neither required for, nor it regulates the UPRmt in mammals. Surprisingly, we demonstrate that a strong mitochondrial cardiomyopathy and diminished respiration due to DARS2 deficiency can be alleviated by the loss of CLPP, leading to an increased de novo synthesis of individual OXPHOS subunits. These results question our current understanding of the UPRmt signaling in mammals, while introducing CLPP as a possible novel target for therapeutic intervention in mitochondrial diseases. 相似文献