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111.
Gupta N Goyal N Bhatia N Kamboj KK Rastogi AK 《Indian journal of experimental biology》2001,39(7):623-628
Antigenic characterization of the soluble fraction of axenic amastigotes of Leishmania donovani ( strain Dd8, causative agent of Indian kala-azar) and their comparison with promastigotes is reported. The axenic amastigotes were assessed for their immunological status employing anti-A2 monoclonal antibody which is extremely specific for L. donovani amastigotes. SDS-PAGE of 35[S] methionine labeled proteins of the two parasite stages exhibited few stage specific and some conserved antigens in both the stages. An increased synthesis of heat shock proteins was observed in axenic amastigotes. Western blot experiments employing sera of kala azar positive patients identified immunodominent antigens of 116,83,26 and 12 kDa in axenic amastigotes which were not present in promastigotes. These amastigote stage specific antigens may have immense potential in immunodiagnosis and prophylaxis of kala-azar. 相似文献
112.
Hunt CR Dix DJ Sharma GG Pandita RK Gupta A Funk M Pandita TK 《Molecular and cellular biology》2004,24(2):899-911
Heat shock proteins (HSPs) are highly conserved among all organisms from prokaryotes to eukaryotes. In mice, the HSP genes Hsp70.1 and Hsp70.3 are induced by both endogenous and exogenous stressors, such as heat and toxicants. In order to determine whether such proteins specifically influence genomic instability, mice deficient for Hsp70.1 and Hsp70.3 (Hsp70.1/3(-/-) mice) were generated by gene targeting. Mouse embryonic fibroblasts (MEFs) prepared from Hsp70.1/3(-/-) mice did not synthesize Hsp70.1 or Hsp70.3 after heat-induced stress. While the Hsp70.1/3(-/-) mutant mice were fertile, their cells displayed genomic instability that was enhanced by heat treatment. Cells from Hsp70.1/3(-/-) mice also display a higher frequency of chromosome end-to-end associations than do control Hsp70.1/3(+/+) cells. To determine whether observed genomic instability was related to defective chromosome repair, Hsp70.1/3(-/-) and Hsp70.1/3(+/+) fibroblasts were treated with ionizing radiation (IR) alone or heat and IR. Exposure to IR led to more residual chromosome aberrations, radioresistant DNA synthesis (a hallmark of genomic instability), increased cell killing, and enhanced IR-induced oncogenic transformation in Hsp70.1/3(-/-) cells. Heat treatment prior to IR exposure enhanced cell killing, S-phase-specific chromosome damage, and the frequency of transformants in Hsp70.1/3(-/-) cells in comparison to Hsp70.1/3(+/+) cells. Both in vivo and in vitro studies demonstrate for the first time that Hsp70.1 and Hsp70.3 have an essential role in maintaining genomic stability under stress conditions. 相似文献
113.
Partial purification of chlorophyll degrading enzymes from cavendish banana (Musa Cavendishi) 总被引:1,自引:0,他引:1
Cavendish banana (Musa Cavendishi, subgroup AAA) remains green upon ripening at tropical temperature (25-30 degrees C), due to incomplete degradation of chlorophyll (Chl). Earlier, evidence for the existence of two distinct degradative pathways--chlorophyllase and chlorophyll oxidase pathways in these bananas was provided. Here, an attempt has been made to understand further the mechanism of inhibition of Chl degradation at different stages of ripening and detecting various enzyme activities by partial purification. Soluble and Triton-solubilized protein fractions obtained from peel acetone powder from green-unripe, green-ripe and yellow-ripe bananas efficiently degraded Chl a. About 2-fold increase in Chl hydrolyzing/oxidizing and magnesium-dechelatase activities was observed in ripe, as compared to green-unripe bananas. The electrophoretic pattern of the soluble and detergent-solubilized proteins from the three stages of ripening revealed that the latter fraction contained only three slow moving proteins, which were found to be glycoproteins, as revealed in PAS staining. The soluble enzyme fraction contained all other bands along with the above three bands, as observed in the Native-PAGE of DEAE-Sepharose purified fractions. Only soluble fraction from 'green-ripe' bananas, catalyzed formation of an unknown intermediate (retention time 8.6 min), which was formed by the action of Triton-solubilized enzyme fractions, obtained from 'green-unripe' and 'yellow-ripe' bananas. The enzyme responsible for the formation of this intermediate might be involved in the stay-green character and could be a component of Chl oxidase pathway. Partial purification of soluble protein fraction by DEAE-Sepharose showed the presence of chlorophyllase, magnesium-dechelatase, pheophorbide a oxygenase, red fluorescent catabolite reductase and Chl oxidase. Native PAGE of pooled fractions showed separation of proteins in different bands. Pooled fractions IV and VI showed the presence of a single major band, resulting in almost a homogenous preparation in a single step. Fraction IV catalyzed dechelation of Mg by Mg-dechelatase, while fraction VI catalyzed the formation of 132-OH-Chl a by chlorophyll oxidase. Chlorophyll oxidase activity was stimulated by linolenic acid, indicating involvement of lipoxygenase in oxidative Chl degradation, thereby resulting in the formation of 13(2)-OH-Chl a as product. The results show the presence of various enzymes of chlorophyllase and chlorophyll oxidase pathways in soluble enzyme fraction. 相似文献
114.
Estrogen has a profound impact on human physiology and affects numerous genes. The classical estrogen reaction is mediated by its receptors (ERs), which bind to the estrogen response elements (EREs) in target gene's promoter region. Due to tedious and expensive experiments, a limited number of human genes are functionally well characterized. It is still unclear how many and which human genes respond to estrogen treatment. We propose a simple, economic, yet effective computational method to predict a subclass of estrogen responsive genes. Our method relies on the similarity of ERE frames across different promoters in the human genome. Matching ERE frames of a test set of 60 known estrogen responsive genes to the collection of over 18,000 human promoters, we obtained 604 candidate genes. Evaluating our result by comparison with the published microarray data and literature, we found that more than half (53.6%, 324/604) of predicted candidate genes are responsive to estrogen. We believe this method can significantly reduce the number of testing potential estrogen target genes and provide functional clues for annotating part of genes that lack functional information. 相似文献
115.
The biology of triploid fish 总被引:1,自引:0,他引:1
Basant?K.?TiwaryEmail author R.?Kirubagaran Arun?K.?Ray 《Reviews in Fish Biology and Fisheries》2004,14(4):391-402
This review deals with major areas of triploidy research in fish. It includes not only methods for induction and detection of triploidy but also the impact of triploidy on morphology, anatomy, growth, haematology, energetics, behaviour, endocrinology and gonads in various species of fish, studied so far. The future prospects of research on triploid fish are discussed inviting researchers with diverse areas of interest in fish biology. 相似文献
116.
Differential modulation of voltage-dependent K+ currents in colonic smooth muscle by oxidants 总被引:1,自引:0,他引:1
The effect of oxidants on voltage-dependent K+ currents was examined in mouse colonic smooth muscle cells. Exposure to either chloramine-T (Ch-T), an agent known to oxidize both cysteine and methionine residues, or the colon-specific oxidant monochloramine (NH2Cl) completely suppressed the transient outward K+ current (Ito) while simultaneously enhancing the sustained delayed rectifier K+ current (Idr). In contrast, the cysteine-specific oxidants hydrogen peroxide (H2O2) and 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) exhibited partial and slow suppression of Ito by inducing a shift in channel availability of -18 mV without affecting Idr. After enhancement by NH2Cl or Ch-T, Idr was sensitive to 10 mM tetraethylammonium but not to other K+ channel blockers, suggesting that it represented activation of the resting Idr and not a separate K+ conductance. Extracellular dithiothreitol (DTT) partially reversed the effect of H2O2 and DTNB on Ito but not the actions of NH2Cl and Ch-T on either Idr or Ito. Dialysis of myocytes with GSH (5 mM) or DTT (5 mM) prevented suppression of Ito by H2O2 and DTNB but did not alter the effects of NH2Cl or Ch-T on either Idr or Ito. Ch-T and NH2Cl completely blocked Ito generated by murine Kv4.1, 4.2, and 4.3 in Xenopus oocytes, an effect not reversible by intracellular DTT. In contrast, intracellular DTT reversed the effect of H2O2 and DTNB on the cloned channels. These results suggest that Ito is suppressed via modification of both methionine and cysteine residues, whereas enhancement of Idr likely results from methionine oxidation alone. colon; colitis; redox; ion channel 相似文献
117.
Sharma A Isogai M Yamamoto T Sakaguchi K Hashimoto J Komatsu S 《Plant & cell physiology》2004,45(6):684-692
Calreticulin (CRT), a major Ca2+-sequestering protein, has beenimplicated in a variety of cellular functions such as Ca2+ storage,signaling and chaperone activity within the cytoplasm and endoplasmicreticulum. To investigate the biological role of CRT in rice,21 partial cDNAs, encoding proteins that interacted with riceCRT in a yeast two-hybrid interaction-cloning system, were characterizedand the nucleotide sequences were found to be identical to eachother. A full-length cDNA of 3.5 kb, obtained from ricegenomic sequence data and 5' RACE, codes for a novel proteinof 966 amino acid residues and was designated as CRTintP (CRTinteracting protein). Primary sequence analysis of CRTintP showedno sequence homology with the known functional proteins; however,a potential ubiquitin-like domain at the N-terminal togetherwith a putative leucine zipper, a nuclear localization signaland several sites for serine/threonine kinases were evident.Cellular localization of CRTintP demonstrated its role in directinggreen fluorescent protein to the nucleus in onion epidermalcells. Northern and immunoblot analysis showed increased expressionof CRT and CRTintP in response to cold stress. Co-immunoprecipitationusing anti-CRT antibodies confirmed the existence of the CRT-CRTintPcomplex in vivo in the stressed leaf tissue, suggesting theirpotential role in regulating stress response.
4 Corresponding author: E-mail, skomatsu{at}affrc.go.jp; Fax, +81-298-38-7464. 相似文献
118.
119.
Detection of low levels of Listeria monocytogenes cells by using a fiber-optic immunosensor 总被引:2,自引:0,他引:2
Biosensor technology has a great potential to meet the need for sensitive and nearly real-time microbial detection from foods. An antibody-based fiber-optic biosensor to detect low levels of Listeria monocytogenes cells following an enrichment step was developed. The principle of the sensor is a sandwich immunoassay where a rabbit polyclonal antibody was first immobilized on polystyrene fiber waveguides through a biotin-streptavidin reaction to capture Listeria cells on the fiber. Capture of cells on the fibers was confirmed by scanning electron microscopy. A cyanine 5-labeled murine monoclonal antibody, C11E9, was used to generate a specific fluorescent signal, which was acquired by launching a 635-nm laser light from an Analyte 2000 and collected by a photodetector at 670 to 710 nm. This immunosensor was specific for L. monocytogenes and showed a significantly higher signal strength than for other Listeria species or other microorganisms, including Escherichia coli, Enterococcus faecalis, Salmonella enterica, Lactobacillus plantarum, Carnobacterium gallinarum, Hafnia alvei, Corynebacterium glutamicum, Enterobacter aerogenes, Pseudomonas aeruginosa, and Serratia marcescens, in pure or in mixed-culture setup. Fiber-optic results could be obtained within 2.5 h of sampling. The sensitivity threshold was about 4.3 x 10(3) CFU/ml for a pure culture of L. monocytogenes grown at 37 degrees C. When L. monocytogenes was mixed with lactic acid bacteria or grown at 10 degrees C with 3.5% NaCl, the detection threshold was 4.1 x 10(4) or 2.8 x 10(7) CFU/ml, respectively. In less than 24 h, this method could detect L. monocytogenes in hot dog or bologna naturally contaminated or artificially inoculated with 10 to 1,000 CFU/g after enrichment in buffered Listeria enrichment broth. 相似文献
120.
Springer J Wagner S Subramamiam A McGregor GP Groneberg DA Fischer A 《Regulatory peptides》2004,118(1-2):19-23
Brain-derived neurotrophic factor (BDNF) is a key modulator during the development of jugular and nodose ganglia neurons, which represent the origin of a large proportion of the sensory innervation of the lung. It belongs to the family of neurotrophins, which have been shown to induce the expression of tachykinins. To assess the interactions of BDNF and the tachykinin neurokinin A (NKA) in small pulmonary vessels, BDNF-transgenic mice were examined for tachykinin contents in the airways, heart, trigeminal ganglion and jugular and nodose ganglion complex (JNC) using reverse phase HPLC (rpHPLC) and radioimmunoassay. BDNF-overexpression led to increased NKA levels in the heart and the JNC, whereas only slightly enhanced levels in the trigeminal ganglion were detected. Lower NKA levels were found in the lung. To assess vasoreactivity in small arteries, precision cut lung slices were subjected to videomorphometry and the response to NKA was examined, which showed significantly stronger effects in the BDNF-transgenic mice, while NK-2 receptor mRNA expression, assayed by real-time RT-PCR, was reduced. In conclusion, BDNF-overexpression results in decreased levels of NKA in the lung with subsequently increased NKA-sensitivity of small arteries. These findings point to a modulatory role of neurotrophins in small respiratory vessel tone regulation. 相似文献