共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
- Download : Download high-res image (163KB)
- Download : Download full-size image
3.
- Download : Download high-res image (214KB)
- Download : Download full-size image
4.
- Download : Download high-res image (200KB)
- Download : Download full-size image
5.
6.
Contessi S Comelli M Cmet S Lippe G Mavelli I 《Journal of bioenergetics and biomembranes》2007,39(4):291-300
F0F1ATPsynthase is now known to be expressed as a plasma membrane receptor for several extracellular ligands. On hepatocytes,
ecto–F0F1ATPsynthase binds apoA–I and triggers HDL endocytosis concomitant with ATP hydrolysis. Considering that inhibitor protein
IF1 was shown to regulate the hydrolytic activity of ecto–F0F1ATPsynthase and to interact with calmodulin (CaM) in vitro, we investigated the subcellular distributions of IF1, calmodulin (CaM), OSCP and β subunits of F0F1ATPsynthase in HepG2 cells. Using immunofluorescence and Western blotting, we found that around 50% of total cellular IF1 is localized outside mitochondria, a relevant amount of which is associated to the plasma membrane where we also found Ca2+–CaM, OSCP and β. Confocal microscopy showed that IF1 colocalized with Ca2+–CaM on plasma membrane but not in mitochondria, suggesting that Ca2+–CaM may modulate the cell surface availability of IF1 and thus its ability to inhibit ATP hydrolysis by ecto–F0F1ATPsynthase. These observations support a hypothesis that the IF1–Ca2+–CaM complex, forming on plasma membrane, functions in the cellular regulation of HDL endocytosis by hepatocytes. 相似文献
7.
《Current opinion in biotechnology》2013,24(6):987-993
- Download : Download high-res image (166KB)
- Download : Download full-size image
8.
9.
The interaction processes of trace amounts of N-methyl-2-pyrrolidinone (NMP), CS2/NMP (1:1 by volume) and pure NMP solvent with the hydrogen bond of OH?N in coal were constructed and simulated by density functional theory methods. The distances and bond orders between the main related atoms, and the hydrogen bond energy of OH?N were calculated. The calculated results show that pure NMP solvent does not weaken the hydrogen bond of OH?N in coal. However, trace amounts of NMP and CS2/NMP (1:1 by volume) have a strong capacity to weaken the hydrogen bond of OH?N in coal. The H2–N3 distances are elongated from 1.87 Å to 3.80 Å and 3.44 Å, the bond orders of H2–N3 all disappear, and the corresponding hydrogen bond energies of OH?N in coal decrease from 45.72 kJ mol?1 to 7.06 and 11.24 kJ mol?1, respectively. These results show that CS2 added to pure NMP solvent plays an important role in releasing the original capacity of NMP to weaken the hydrogen bond of OH?N in coal, in agreement with experimental observations. 相似文献
10.
Hilary A. Thompson Jeffrey R. White Lisa M. Pratt Peter E. Sauer 《Biogeochemistry》2016,131(1-2):17-33
Small lakes in northern latitudes represent a significant source of CH4 to the atmosphere that is predicted to increase with warming in the Arctic. Yet, whole-lake CH4 budgets are lacking as are measurements of δ13C-CH4 and δ2H-CH4. In this study, we quantify spatial variability of diffusive and ebullitive fluxes of CH4 and corresponding δ13C-CH4 and δ2H-CH4 in a small, Arctic lake system with fringing wetland in southwestern Greenland during summer. Net CH4 flux was highly variable, ranging from an average flux of 7 mg CH4 m?2 d?1 in the deep-water zone to 154 mg CH4 m?2 d?1 along the lake margin. Diffusive flux accounted for ~8.5 % of mean net CH4 flux, with plant-mediated and ebullitive flux accounting for the balance of the total net flux. Methane content of emitted ebullition was low (mean ± SD 10 ± 17 %) compared to previous studies from boreal lakes and wetlands. Isotopic composition of net CH4 emissions varied widely throughout the system, with δ13C-CH4 ranging from ?66.2 to ?55.5 ‰, and δ2H-CH4 ranging from ?345 to ?258 ‰. Carbon isotope composition of CH4 in ebullitive flux showed wider variation compared to net flux, ranging from ?69.2 to ?49.2 ‰. Dissolved CH4 concentrations were highest in the sediment and decreased up the water column. Higher concentrations of CH4 in the hypoxic deep water coincided with decreasing dissolved O2 concentrations, while methanotrophic oxidation dominated in the epilimnion based upon decreasing concentrations and increasing values of δ13C-CH4 and δ2H-CH4. The most depleted 13C- and 2H-isotopic values were observed in profundal bottom waters and in subsurface profundal sediments. Based upon paired δ13C and δ2H observations of CH4, acetate fermentation was likely the dominant production pathway throughout the system. However, isotopic ratios of CH4 in deeper sediments were consistent with mixing/transition between CH4 production pathways, indicating a higher contribution of the CO2 reduction pathway. The large spatial variability in fluxes of CH4 and in isotopic composition of CH4 throughout a single lake system indicates that the underlying mechanisms controlling CH4 cycling (production, consumption and transport) are spatially heterogeneous. Net flux along the lake margin dominated whole-lake flux, suggesting the nearshore littoral area dominates CH4 emissions in these systems. Future studies of whole-lake CH4 budgets should consider this significant spatial heterogeneity. 相似文献
11.
12.
Ayumi Tanaka-Oda Tanaka Kenzo Yuta Inoue Midori Yano Keisuke Koba Tomoaki Ichie 《Trees - Structure and Function》2016,30(2):509-522
Key message
Large variations in leaf δ 15 N in Bornean tropical rainforest trees may indicate that various tropical species have species-specific strategy for nitrogen uptake under low soil nutrient conditions, including root symbiotic microorganisms such as ectomycorrhiza.Abstract
Lowland tropical rainforests in Southeast Asia are characterized by high species diversity despite limited soil nutrient conditions. The plant nitrogen isotope ratio (δ15N) reflects plant uptake of soil nitrogen. We analyzed δ15N values and nitrogen content (N %) in leaves and roots of 108 woody species with different types of symbiotic microorganisms, of different life forms (emergent, canopy, sub-canopy, understory, and canopy gap species), and from different families in a Bornean lowland dipterocarp forest to gain more insight into the diversity of nitrogen uptake strategy in the rhizosphere. Leaf δ15N values in the species studied varied largely from ?7.2 to 5.0 ‰, which is comparable to the values of known Asian trees including temperate, sub-tropical, and tropical mountain forests. Leaf δ15N also varied significantly among both life forms and families, though the phylogenetically independent contrast (PIC) relationships were not statistically significant among life form, family, and symbiotic types. Some families showed specific leaf δ15N values; Dipterocarpaceae, the dominant family in the canopy layer with symbiotic ectomycorrhiza in Southeast Asia, had small intraspecific variation and higher leaf δ15N values (0.03 ‰) compared with species exhibiting arbuscular mycorrhiza, whereas several families such as Burseraceae, Euphorbiaceae, and Myrtaceae showed large interspecific variation in leaf δ15N (e.g., from ?7.2 to 5.0 ‰ in Euphorbiaceae). These variations suggest that tropical species may have family- or species-specific strategy, such as root symbiotic microorganisms, for nitrogen uptake under low-nutrient conditions in tropical rainforests in Southeast Asia.13.
14.
《Animal : an international journal of animal bioscience》2021,15(9):100320
The identification of the presence of genotype by environment interaction effects on important traits in Holstein cattle allows for the use of international genetic evaluations and a more efficient design of regional genetic evaluation programmes. The aim of this study was to determine the genotype × environment interaction effects in Chilean Holstein dairy cattle through the analysis of records corresponding to calvings between 1998 and 2015. Herds were classified in the central and southern regions of Chile based on herd location as well as by high and low levels of production environments based on the fat plus protein yield averages per herd within each region. The central region has a Mediterranean climate and a confined production system while the southern region has a humid temperate climate and a production system based on grazing with supplementation. Traits studied were milk yield (MY), fat yield (FY), protein yield (PY), fat content (FC) and protein content (PC) by lactation, age at first calving (AFC) and calving interval (CI). Several four-trait mixed animal models were applied to environmental category data as different traits, which included herd-year-calving season (herd-year-birth season for AFC) and lactation number as fixed effects, and animal additive genetic, sire-herd, permanent environment and residual effects as random effects. Genetic correlations (rg) for MY, FY, FC, PC and CI were found to decrease as differences between environmental categories increased. The rg between the most extreme environmental categories considered in this study for AFC (0.26) was the only one found statistically lower than 0.60. Genetic correlation values statistically lower than 0.80 (P < 0.05) were observed for AFC, CI, MY, FY and PY between some environmental categories. If separate genetic evaluations are adopted as practical criteria when the value of rg is lower than 0.60, the consequence of improving a multi-trait economic breeding objective in this population is likely to be small unless extreme environmental categories are considered. However, a moderate decrease in selection response and re-ranking of selection candidates is expected for AFC, CI and yield traits when selection is performed in different environmental conditions. Genotype × environment interaction effects involving production systems in a Mediterranean climate and confinement vs. Temperate Oceanic climate and grazing with supplementation, and between two fat plus protein yield level categories within each environment, were at most moderate for the studied traits. 相似文献
15.
Efficient somatic embryogenesis (SE) and in vitro flowering and fruiting were achieved in Saposhnikovia divaricata (Turcz.) Schischk. Friable embryogenic callus developed from the root, internode, and leaf explants on Murashige and Skoog
medium (MS) with 2.26 μM 2,4-dichlorophenoxyacetic acid (2,4-D), and subsequently developed into somatic embryos on MS medium
containing 4–5% sucrose, 1.74 μM naphthaleneacetic acid (NAA), 4.44 μM 6-benzylaminopurine (BA), and 1.90 μM abscisic acid
(ABA). Then the mature embryos were separated and transferred onto MS with 3% sucrose and 0.6% agar for further development
and conversion to plantlets. In vitro flowering and fruiting were obtained when the subcultures were carried out for over
15 months. Paclobutrazol (PP333) or ethephon (ETH) at low levels promoted flowering significantly. Also, abnormal rootless
somatic embryos of S. divaricata could form flowers and fruits in vitro. 相似文献
16.
Activation of β-adrenoceptors in area CA1 of the hippocampus facilitates in vitro long-term potentiation (LTP) in this region. However, it is unclear if in vivo LTP in area CA1 and hippocampus-dependent learning are subjected to β-adrenergic regulation. To address this question, we investigated the effects of the β-adrenergic agonist L-isoproterenol or antagonist DL-propranolol on in vivo LTP of area CA1 and the spatial learning in Morris water maze. In the presence of L-isoproterenol (through local infusion into area CA1), the theta-pulse stimulation with the parameter of 10 Hz, 150 pulses/train, 1 train, a frequency weakly modifying synaptic strength, induced a robust LTP, and this effect was blocked when DL-propranolol was co-administered. By contrast, the theta-pulse stimulation with the parameter of 5 Hz, 150 pulses/train, 3 trains, a frequency strongly modifying synaptic strength, induced a significantly smaller LTP when DL-propranolol was administered into area CA1. Accordingly, DL-propranolol impaired the spatial learning in the water maze when infused into area CA1 20 min pretraining. Compared with control rats, the DL-propranolol-treated rats showed significantly slower learning in the water maze and subsequently exhibited poor memory retention at 24-h test. These results suggest that β-adrenoceptors in area CA1 are involved in regulating in vivo synaptic plasticity of this area and are important for spatial learning. 相似文献
17.
18.
《CMAJ》1959,80(7):604-608,610
19.
20.
Schistosomiasis, currently the second most common parasitic disease of humans in tropical regions is caused by the eggs of trematode worms of the genus Schistosoma. Understanding egg formation and specifically the synthesis of the eggshell comprises, consequently, a promising starting point to cure and prevent the disease. To shed light on the genetics of the latter process, we analysed the three known S. mansoni eggshell proteins P14, P19 and P48 against the background of the species inferred proteome and of eggshell proteins identified in other trematode species. Our results suggest that eggshell formation in Schistosoma involves a multitude of different proteins organised in currently three distinct protein families (P14, P48 and P34 eggshell protein family). The first two families are of simple structure. Their respective members share a substantial degree of sequence similarity and are, to date, observed only in the genus Schistosoma. In contrast, the P34 family of eggshell proteins is complex. Its in part highly diverged members share only a conserved motif of 67-aa length on average and are detected in various trematode species. The resulting widespread occurrence of this protein motif suggests an important role during eggshell formation in trematodes. Screening more than 7,000 putative proteins of S. mansoni, we could identify six new members of the P34 protein family that are likely to be involved in eggshell formation in this species.Electronic Supplementary Material Supplementary material is available for this article at . 相似文献