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排序方式: 共有153条查询结果,搜索用时 15 毫秒
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2.
A 36 Kilodalton Limiting-CO(2) Induced Polypeptide of Chlamydomonas Is Distinct from the 37 Kilodalton Periplasmic Carbonic Anhydrase 总被引:4,自引:4,他引:0
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Chlamydomonas reinhardtii possesses a CO2-concentrating mechanism, induced by limiting CO2, which involves active transport and accumulation of inorganic carbon within the cell. Synthesis of several proteins is induced by limiting CO2, but, of those, only periplasmic carbonic anhydrase has an identified function in the system. No proteins involved in active transport have yet been identified, but induced, membrane-associated polypeptides, such as the 36 kilodalton polypeptide focused on in this paper, would seem to be candidates for such involvement. The 36 kilodalton polypeptide was shown to be synthesized de novo upon transfer of cells to limiting CO2. It was purified using SDS-PAGE and used to produce polyclonal antibodies. Antibodies were used to confirm the air-specific nature of the polypeptide, its strict association with membrane fractions, and the time course of its induction. Using the antibodies, a single, 36 kilodalton polypeptide was found to be specifically immunoprecipitated from in vitro translation products of poly(A+) RNA from cells only after exposure to limiting CO2. The absence of translatable mRNA for this polypeptide in CO2-enriched cells indicated that regulation occurs at the level of message abundance. The antibodies were also used to demonstrate the distinction between the limiting-CO2 induced 36 kilodalton polypeptide and the similarly sized, limiting-CO2 induced periplasmic carbonic anhydrase. 相似文献
3.
The effects of the trichothecene mycotoxins (acetyl T-2 toxin, T-2 toxin, HT-2 toxin, palmityl T-2 toxin, diacetoxyscirpenol (DAS), deoxynivalenol (DON), and T-2 tetraol) on bovine platelet function were examined in homologous plasma stimulated with platelet activating factor (PAF). The mycotoxins inhibited platelet function with the following order of potency: acetyl T-2 toxin > palmityl T-2 toxin = DAS > HT-2 toxin = T-2 toxin. While T-2 tetraol was completely ineffective as an inhibitor, DON exhibited minimal inhibitory activity at concentrations above 10×10?4M. The stability of the platelet aggregates formed was significantly reduced in all mycotoxin treated platelets compared to that of the untreated PAF controls. It is suggested that the increased sensitivity of PAF stimulated bovine platelets to the more lipophilic mycotoxins may be related to their more efficient partitioning into the platelet membrane compared to the more hydrophilic compounds. 相似文献
4.
Mechanical effects of ET-1 in cardiomyocytes isolated from normal and heart-failed rabbits 总被引:1,自引:0,他引:1
Elizabeth J. Kelso Robert F. Geraghty Barbara J. McDermott Elisabeth R. Trimble D. Paul Nicholls Bernard Silke 《Molecular and cellular biochemistry》1996,157(1-2):149-155
Endothelin (ET-1) is found at elevated concentrations in the plasma of patients with heart failure and in animal models of cardiomyopathy. The peptide is a potent positive inotropic agent, the effects of which are mediated by increases in cytosolic Ca2+ in cardiomyocytes. The object of this study was to investigate at the cellular level, the actions of ET-1 on contractile function and on Ca2+ currents in heart-failed ventricular myocardium. Male New Zealand White rabbits (8 wks) were treated with twice weekly injections of epirubicin (4 mg/kg/wk, n=7) or with saline (n=7) for 6 wks, followed by a washout period of 2 wks. Ventricular cardiomyocytes were isolated from rabbit hearts using Langendorff perfusion with collagenase; contractile function was examined using a video microscopy method, and L-type Ca2+ currents were recorded using a whole-cell patch-clamp technique. ET-1 produced a concentration-dependent increase in contractile response (% increase from basal value) to a maximum at 1 nM ET-1 of 69 ± 11% (mean ± S.D.) in control cardiomyocytes and 33 ± 6% in heart-failed cells. However, there was no significant change in the EC50 obtained with ET-1 for healthy (0.31 ± 0.1 nM) and for failed cardiomyocytes (0.24 ± 0.1 nM). The effects of ET-1 on L-type Ca2+ channels were similar with a peak amplitude at 1 nM ET-1 of –3.26 ± 0.8 in control cardiomyocytes and –3.32 ± 0.9 nA in heart-failed cells. The attenuation of the contractile response to ET-1 in heart-failed cells may reflect a desensitization of ET receptors as a consequence of elevated circulating levels of ET and was not reflected by alteration of transmembrane Ca2+ conductance. It is probable, therefore, that multiple signalling pathways are involved in the actions of ET on ventricular myocardium.Recipient of Servier Investigator Award 相似文献
5.
Hrushikesh S. Chaudhari Omkar S. Palkar KM Abha Mishra Kalyan K. Sethi 《Journal of biochemical and molecular toxicology》2023,37(9):e23417
During the period of COVID-19, the occurrences of mucormycosis in immunocompromised patients have increased significantly. Mucormycosis (black fungus) is a rare and rapidly progressing fungal infection associated with high mortality and morbidity in India as well as globally. The causative agents for this infection are collectively called mucoromycetes which are the members of the order Mucorales. The diagnosis of the infection needs to be performed as soon as the occurrence of clinical symptoms which differs with types of Mucorales infection. Imaging techniques magnetic resonance imaging or computed tomography scan, culture testing, and microscopy are the approaches for the diagnosis. After the diagnosis of the infection is confirmed, rapid action is needed for the treatment in the form of antifungal therapy or surgery depending upon the severity of the infection. Delaying in treatment declines the chances of survival. In antifungal therapy, there are two approaches first-line therapy (monotherapy) and combination therapy. Amphotericin B ( 1 ) and isavuconazole ( 2 ) are the drugs of choice for first-line therapy in the treatment of mucormycosis. Salvage therapy with posaconazole ( 3 ) and deferasirox ( 4 ) is another approach for patients who are not responsible for any other therapy. Adjunctive therapy is also used in the treatment of mucormycosis along with first-line therapy, which involves hyperbaric oxygen and cytokine therapy. There are some drugs like VT-1161 ( 5 ) and APX001A ( 6 ), Colistin, SCH 42427, and PC1244 that are under clinical trials. Despite all these approaches, none can be 100% successful in giving results. Therefore, new medications with favorable or little side effects are required for the treatment of mucormycosis. 相似文献
6.
The protein sequence of a representative of the zeins, the major storage proteins of maize, has been derived from the nucleotide sequence of a zein cDNA clone. This cDNA was sequence both by the Maxam and Gilbert and the M13-dideoxy techniques. The nucleotide sequence encompasses the non-translated 3' terminus of the mRNA, the entire coding sequence specifying both the mature zein protein and a small signal peptide, and a portion of the non-translated 5' region. The deduced amino acid composition and the amino-terminal amino acid sequence closely resemble those derived from chemical analysis of the zein protein fraction. The data presented represent the first complete amino acid sequence of a plant storage protein. 相似文献
7.
The nucleotide sequence of two zein cDNAs in hybrid plasmids A20 and B49 have been determined. The insert in A20 is 921 bp long including a 5' non-coding region of 60 nucleotides, preceded by what is believed to be an artifactual sequence of 41 nucleotides, and a 3' non-coding region of 87 nucleotides. The B49 insert is 467 bp long and includes approximately one-half the protein coding sequence as well as a 3' non-coding region of 97 nucleotides. These sequences have been compared with the previously published sequence of another zein clone, A30 . A20 and A30 , both encoding 19 000 mol. wt. zeins , have approximately 85% homology at the nucleotide level. The B49 sequence, corresponding to a 22 000 mol. wt. zein, has approximately 65% homology to either A20 or A30 . All three zeins share common features including nearly identical amino acid compositions. In addition, the tandem repeats of 20 amino acids first seen in A30 are also present in A20 and B49 . 相似文献
8.
Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed. 相似文献
9.
Burns C Geraghty R Neville C Murphy A Kavanagh K Doyle S 《Fungal genetics and biology : FG & B》2005,42(4):319-327
Analysis of the genome of the human pathogen, Aspergillus fumigatus, revealed the presence of several putative glutathione transferase (GST) open reading frames. Three A. fumigatus GST genes, termed gstA, B, and C, were cloned and recombinant proteins expressed in Escherichia coli. Functional analysis of recombinant gstA-C confirms that the enzymes exhibit GST activity and glutathione peroxidase activity. RT-PCR confirmed low basal expression of gstA and gstC which was markedly up-regulated (at least 4x-10x) in the presence of either H2O2 or 1-chloro-2,4-dinitrobenzene (CDNB). GstB expression was only observed in the presence of CDNB. These results demonstrate for the first time the existence of three functional GSTs in A. fumigatus and strongly suggest a role for these enzymes in the response of the organism to both oxidative stress and xenobiotic presence. 相似文献
10.
Increased lung levels of matrix metalloproteinase 9 (MMP9) are frequently observed during respiratory syncytial virus (RSV) infection and elevated MMP9 concentrations are associated with severe disease. However little is known of the functional role of MMP9 during lung infection with RSV. To determine whether MMP9 exerted direct antiviral potential, active MMP9 was incubated with RSV, which showed that MMP9 directly prevented RSV infectivity to airway epithelial cells. Using knockout mice the effect of the loss of Mmp9 expression was examined during RSV infection to demonstrate MMP9’s role in viral clearance and disease progression. Seven days following RSV infection, Mmp9
-/- mice displayed substantial weight loss, increased RSV-induced airway hyperresponsiveness (AHR) and reduced clearance of RSV from the lungs compared to wild type mice. Although total bronchoalveolar lavage fluid (BALF) cell counts were similar in both groups, neutrophil recruitment to the lungs during RSV infection was significantly reduced in Mmp9
-/- mice. Reduced neutrophil recruitment coincided with diminished RANTES, IL-1β, SCF, G-CSF expression and p38 phosphorylation. Induction of p38 signaling was required for RANTES and G-CSF expression during RSV infection in airway epithelial cells. Therefore, MMP9 in RSV lung infection significantly enhances neutrophil recruitment, cytokine production and viral clearance while reducing AHR. 相似文献