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11.
Premysl Ponka Jitka Borova Jan Neuwirt 《Biochimica et Biophysica Acta (BBA)/General Subjects》1980,632(4):527-535
A high level of non-heme iron (either labelled or unlabelled) in mitochondria, ferritin and low-molecular-weight pool of reticulocytes was induced by preincubation with isonicotinic acid hydrazide or penicillamine together with either 59Fe- or 56Fe-labelled transferrin. Addition of apotransferrin during reincubation of 59Fe-labelled reticulocytes was accompanied by the transfer of 59Fe from low-molecular-weight pool to transferrin, which was found in the reticulocyte cytosol both free and bound to a carrier. Similarly, when cells were reincubated with 125I-labelled transferrin, more 125I-labelled radioactivity was found, in both free and carrier-bound transferrin peaks, in reticulocytes with a high level of low-molecular-weight cold iron than in control ones. These results suggest that transferrin enters reticulocytes takes up iron from low-molecular-weight pool. 相似文献
12.
Tamara Pečenková Přemysl Pejchar Tomáš Moravec Matěj Drs Samuel Haluška Jiří Šantrůček Andrea Potocká Viktor Žárský Martin Potocký 《Molecular Plant Pathology》2022,23(5):664-678
The pathogenesis-related 1 (PR1) proteins are members of the cross-kingdom conserved CAP superfamily (from Cysteine-rich secretory protein, Antigen 5, and PR1 proteins). PR1 mRNA expression is frequently used for biotic stress monitoring in plants; however, the molecular mechanisms of its cellular processing, localization, and function are still unknown. To analyse the localization and immunity features of Arabidopsis thaliana PR1, we employed transient expression in Nicotiana benthamiana of the tagged full-length PR1 construct, and also disrupted variants with C-terminal truncations or mutations. We found that en route from the endoplasmic reticulum, the PR1 protein transits via the multivesicular body and undergoes partial proteolytic processing, dependent on an intact C-terminal motif. Importantly, only nonmutated or processing-mimicking variants of PR1 are secreted to the apoplast. The C-terminal proteolytic cleavage releases a protein fragment that acts as a modulator of plant defence responses, including localized cell death control. However, other parts of PR1 also have immunity potential unrelated to cell death. The described modes of the PR1 contribution to immunity were found to be tissue-localized and host plant ontogenesis dependent. 相似文献
13.
The catalytic role of iron in the Haber-Weiss chemistry, which results in propagation of damaging reactive oxygen species (ROS), is well established. In this review, we attempt to summarize the recent evidence showing the reverse: That reactive oxygen and nitrogen species can significantly affect iron metabolism. Their interaction with iron-regulatory proteins (IRPs) seems to be one of the essential mechanisms of influencing iron homeostasis. Iron depletion is known to provoke normal iron uptake via IRPs, superoxide and hydrogen peroxide are supposed to cause unnecessary iron uptake by similar mechanism. Furthermore, ROS are able to release iron from iron-containing molecules. On the contrary, nitric oxide (NO) appears to be involved in cellular defense against the iron-mediated ROS generation probably mainly by inducing iron removal from cells. In addition, NO may attenuate the effect of superoxide by mutual reaction, although the reaction product—peroxynitrite—is capable to produce highly reactive hydroxyl radicals. 相似文献
14.
Verdú EF Deng Y Bercik P Collins SM 《American journal of physiology. Gastrointestinal and liver physiology》2002,283(1):G27-G36
The association between oral contraceptives or pregnancy and inflammatory bowel disease is unclear. We investigated whether 17beta-estradiol modulates intestinal inflammation in two models of colitis. Female mice were treated with 17beta-estradiol alone or with tamoxifen, tamoxifen alone, 17 alpha-estradiol, or placebo. Dinitrobenzene sulfonic acid (DNB)- or dextran sodium sulfate (DSS)-induced colitis were assessed macroscopically, histologically, and by myeloperoxidase (MPO) activity. Malondialdehyde and mRNA levels of intercellular adhesion molecule-1 (ICAM-1), interferon-gamma (IFN-gamma), and interleukin-13 (IL-13) were determined. In DNB colitis, 17beta-estradiol alone, but not 17beta-estradiol plus tamoxifen, or 17 alpha-estradiol reduced macroscopic and histological scores, MPO activity and malondialdehyde levels. 17beta-Estradiol also decreased the expression of ICAM-1, IFN-gamma, and IL-13 mRNA levels compared with placebo. In contrast, 17beta-Estradiol increased the macroscopic and histological scores compared with placebo in mice with DSS colitis. These results demonstrate anti-inflammatory and proinflammatory effects of 17beta-estradiol in two different models of experimental colitis. The net modulatory effect most likely reflects a combination of estrogen receptor-mediated effects and antioxidant activity and may explain, in part, conflicting results from clinical trials. 相似文献
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16.
Kocourková D Krcková Z Pejchar P Veselková S Valentová O Wimalasekera R Scherer GF Martinec J 《Journal of experimental botany》2011,62(11):3753-3763
Phosphatidylcholine-hydrolysing phospholipase C, also known as non-specific phospholipase C (NPC), is a new member of the plant phospholipase family that reacts to environmental stresses such as phosphate deficiency and aluminium toxicity, and has a role in root development and brassinolide signalling. Expression of NPC4, one of the six NPC genes in Arabidopsis, was highly induced by NaCl. Maximum expression was observed from 3?h to 6?h after the salt treatment and was dependent on salt concentration. Results of histochemical analysis of P(NPC4):GUS plants showed the localization of salt-induced expression in root tips. On the biochemical level, increased NPC enzyme activity, indicated by accumulation of diacylglycerol, was observed as early as after 30?min of salt treatment of Arabidopsis seedlings. Phenotype analysis of NPC4 knockout plants showed increased sensitivity to salinity as compared with wild-type plants. Under salt stress npc4 plants had shorter roots, lower fresh weight, and reduced seed germination. Expression levels of abscisic acid-related genes ABI1, ABI2, RAB18, PP2CA, and SOT12 were substantially reduced in salt-treated npc4 plants. These observations demonstrate a role for NPC4 in the response of Arabidopsis to salt stress. 相似文献
17.
Verdu EF Bercik P Huang XX Lu J Al-Mutawaly N Sakai H Tompkins TA Croitoru K Tsuchida E Perdue M Collins SM 《American journal of physiology. Gastrointestinal and liver physiology》2008,295(4):G664-G670
The role of chronic infections, such as Helicobacter pylori (Hp), to produce sustained changes in host physiology remains controversial. In this study, we investigate whether the antigenic or bacterial content of the gut, after Hp eradication, influences the changes in gut function induced by chronic Hp infection. Mice were infected with Hp for 4 mo and then treated with antibiotics or placebo for 2 wk. Gastric emptying was measured using videofluoroscopy, feeding behavior using a 24-h feeding system, and intestinal permeability using an isolated jejunal segment arterially perfused with an artificial oxygen carrier, hemoglobin vesicles. Immune responses were assessed by CD3(+) cell counts and anti-Hp antibodies using ELISA. To determine the role of luminal factors in host physiology posteradication, groups of mice received the probiotics containing Lactobacillus rhamnosus R0011 and L. helveticus R0052 or placebo for 2 wk or crude Hp antigen weekly for 2 mo. Chronic Hp infection was associated with delayed gastric emptying, increased intestinal permeability, and increased gastric CD3(+) cell counts. Hp-induced altered feeding patterns did not reverse after eradication. Probiotics accelerated the recovery of paracellular permeability and delayed gastric emptying, improved the CD3(+) cell counts, and normalized altered feeding patterns posteradication. Hp antigen resulted in increased anti-Hp antibodies and increased CD3(+) cell counts in the stomach and delayed recovery of gastric function. Our results suggest that the bacterial content of the gut, as well as the presence of relevant antigens, influences the rate of recovery of host pathophysiology induced by chronic Hp infection. These changes do not seem to occur in association with modulation of intestinal permeability. 相似文献
18.
Assessing the conservation value of a human-dominated island landscape: Plant diversity in Hawaii 总被引:1,自引:1,他引:0
Rebecca L. Goldman Liba Pejchar Goldstein Gretchen C. Daily 《Biodiversity and Conservation》2008,17(7):1765-1781
The conversion of native habitats to pasture and other working lands, unbuilt lands modified by humans for production, is
one of the greatest threats to biodiversity. While some human-dominated landscapes on continents support relatively high native
biodiversity, this capacity is little studied in oceanic island systems characterized by high endemism and vulnerability to
invasion. Using Hawaii as a case study, we assessed the conservation value of working landscapes on an oceanic island by surveying
native and non-native plant diversity in mature native forest and in the three dominant land covers/uses to which it has been
converted: native, Acacia koa timber plantations, wooded pasture, and open pasture. As expected, native plant diversity (richness and abundance) was significantly
higher and non-native abundance significantly lower in mature native forests than any other site type. A. koa plantations and wooded pasture supported four and three times greater, respectively, species richness of native understory
plants than open pasture. Also, A. koa plantations and wooded pasture supported similar species communities with about 75% species in common. Conservation and restoration
of mature native forest in Hawaii is essential for the protection of native, rare species and limiting the spread of non-native
species. A. koa plantations and wooded pasture, however, may help harmonize production and conservation by supporting livelihoods, more biodiversity
than open pasture, and some connectivity between native forest remnants important for sustaining landscape-level conservation
value into the future. 相似文献
19.
Försterová M Jandurová Z Marques F Gano L Lubal P Vanek J Hermann P Santos I 《Journal of inorganic biochemistry》2008,102(7):1531-1540
The novel methylphosphonic acid monoethylester (H4dotpOEt) has been synthesized and characterized and their complexes with Sm(III) and Ho(III) ions were studied. Dissociation constants of the ligand are lower than those of H4dota. The stability constants of the Ln(III)-H4dotpOEt complexes are surprisingly much lower that those of H4dota (H4dota = 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) probably due to a lower coordination ability of the phosphonate monoester groups. Acid-assisted decomplexation studies have shown that both complexes are less kinetically inert than the H4dota complexes, but still much more inert than complexes of open-chain ligands. Nevertheless, the synthesis of 153Sm and 166Ho complexes with this ligand led to stable complexes both in vitro and in vivo. A very low binding of these complexes to hydroxyapatite (HA) and calcified tissues was observed confirming the assumption that a fully ionized phosphonate group(s) is necessary for a strong bone affinity. Both complexes show similar behaviour in vivo and, in general, follow the biodistribution trend of the H4dota complexes with the same metals. 相似文献