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991.
992.
Gutiérrez L Vujić Spasić M Muckenthaler MU Lázaro FJ 《Biochimica et biophysica acta》2012,1822(7):1147-1153
Quantitative analysis of the temperature dependent AC magnetic susceptibility of freeze-dried mouse tissues from an Hfe hereditary haemochromatosis disease model indicates that iron predominantly appears biomineralised, like in the ferritin cores, in the liver, the spleen and duodenum. The distribution of the amount of ferritin-like iron between genders and genotypes coincides with that of elemental iron and nonheme iron. Importantly, the so-called paramagnetic iron, a quantity also determined from the magnetic data and indicative of nonmineralised iron forms, appears only marginally increased when iron overload takes place. 相似文献
993.
Intrinsic effects of species on leaf litter and root decomposition: a comparison of temperate grasses from North and South America 总被引:3,自引:0,他引:3
A simple model of water uptake by vegetation is used to aid the discrimination of plant water sources determined with isotope data. In the model, water extracted from different soil depths depends on the leaf–soil potential difference, a root distribution function and a lumped hydraulic conductance parameter. Measurements of plant transpiration rate, and soil and leaf water potentials are used to estimate the value of the conductance parameter. Isotopic ratios in soil water and xylem are then used to constrain the root distribution. The model is applied to field measurements of transpiration, leaf water potential and 18O composition of xylem water on Corymbia clarksoniana, Lophostemon suaveolens, Eucalpytus platyphylla and Melaleuca viridiflora, and soil water potential and 18O composition of soil water to 8.5 m depth, in an open woodland community, Pioneer Valley, North Queensland. Estimates of the water uptake from various depths below the surface are determined for each species. At the time of sampling, the proportion of groundwater extracted by the trees ranged from 100% for C. clarksoniana to <15% for L. suaveolens and E. platyphylla. The advantages of the model over the traditional approach to determining sources of water used by plants using isotope methods are that it: (1) permits more quantitative assessments of the proportion of water sourced from different depths, (2) can deal with gradational soil water isotope profiles (rather than requiring distinct values for end-members), and (3) incorporates additional data on plant water potentials and is based on simple plant physiological processes. 相似文献
994.
995.
Gehman JD Luc F Hall K Lee TH Boland MP Pukala TL Bowie JH Aguilar MI Separovic F 《Biochemistry》2008,47(33):8557-8565
Skin secretions of numerous Australian tree frogs contain antimicrobial peptides that form part of the host defense mechanism against bacterial infection. The mode of action of these antibiotics is thought to be lysis of infectious organisms via cell membrane disruption, on the basis of vesicle-encapsulated dye leakage data [Ambroggio et al. (2005) Biophys. J. 89, 1874-1881]. A detailed understanding of the interaction of these peptides with bacterial membranes at a molecular level, however, is critical to their development as novel antibacterial therapeutics. We focus on four of these peptides, aurein 1.2, citropin 1.1, maculatin 1.1, and caerin 1.1, which exist as random coil in aqueous solution but have alpha-helical secondary structure in membrane mimetic environments. In our earlier solid-state NMR studies, only neutral bilayers of the zwitterionic phospholipid dimyristoylphosphatidylcholine (DMPC) were used. Deuterated DMPC ( d 54-DMPC) was used to probe the effect of the peptides on the order of the lipid acyl chains and dynamics of the phospholipid headgroups by deuterium and (31)P NMR, respectively. In this report we demonstrate several important differences when anionic phospholipid is included in model membranes. Peptide-membrane interactions were characterized using surface plasmon resonance (SPR) spectroscopy and solid-state nuclear magnetic resonance (NMR) spectroscopy. Changes in phospholipid motions and membrane binding information provided additional insight into the action of these antimicrobial peptides. While this set of peptides has significant C- and N-terminal sequence homology, they vary in their mode of membrane interaction. The longer peptides caerin and maculatin exhibited properties that were consistent with transmembrane insertion while citropin and aurein demonstrated membrane disruptive mechanisms. Moreover, aurein was unique with greater perturbation of neutral versus anionic membranes. The results are consistent with a surface interaction for aurein 1.2 and pore formation rather than membrane lysis by the longer peptides. 相似文献
996.
Paul A. De Luca Luc F. Bussière Daniel Souto-Vilaros Dave Goulson Andrew C. Mason Mario Vallejo-Marín 《Oecologia》2013,172(3):805-816
Buzz-pollination is a plant strategy that promotes gamete transfer by requiring a pollinator, typically bees (Hymenoptera: Apoidea), to vibrate a flower’s anthers in order to extract pollen. Although buzz-pollination is widespread in angiosperms with over 20,000 species using it, little is known about the functional connection between natural variation in buzzing vibrations and the amount of pollen that can be extracted from anthers. We characterized variability in the vibrations produced by Bombus terrestris bumblebees while collecting pollen from Solanum rostratum (Solanaceae), a buzz-pollinated plant. We found substantial variation in several buzzing properties both within and among workers from a single colony. As expected, some of this variation was predicted by the physical attributes of individual bumblebees: heavier workers produced buzzes of greater amplitude. We then constructed artificial “pollination buzzes” that varied in three parameters (peak frequency, peak amplitude, and duration), and stimulated S. rostratum flowers with these synthetic buzzes to quantify the relationship between buzz properties and pollen removal. We found that greater amplitude and longer duration buzzes ejected substantially more pollen, while frequency had no directional effect and only a weak quadratic effect on the amount of pollen removed. These findings suggest that foraging bumblebees may improve pollen collection by increasing the duration or amplitude of their buzzes. Moreover, given that amplitude is positively correlated with mass, preferential foraging by heavier workers is likely to result in the largest pollen yields per bee, and this could have significant consequences for the success of a colony foraging on buzz-pollinated flowers. 相似文献
997.
A radiation hybrid map of the RN region in pigs demonstrates conserved gene order compared with the human and mouse genomes 总被引:2,自引:0,他引:2
Annie Robic Virginie Seroude Jin-Tae Jeon Martine Yerle Luc Wasungu Leif Andersson Joël Gellin Denis Milan 《Mammalian genome》1999,10(6):565-568
We recently constructed a 7000-rad porcine whole-genome radiation hybrid (RH) panel with the primary objective of integrating
linkage maps of microsatellites with evolutionary conserved genes into one ordered map. In order to evaluate the resolution
of this RH panel, we have now constructed a radiation hybrid map of the Chromosome (Chr) 15q2.3-q2.6 region containing the
RN gene. This gene has large effects on glycogen content in muscle and meat quality. Ten microsatellites covering a region of
55 centiMorgans and eight genes (AE3, FN1, IGFBP5, INHA, IRS1, PAX3, TNP1, and VIL1) were placed on the Sscr15 RH map. All the genes, except IRS1, were mapped on the RH map between microsatellites located in 15q2.5. The relative order of AE3 and INHA was inverted on the porcine physical map in comparison with the mouse linkage map. The order of other genes already mapped
in the mouse (FN1, IGFBP5, TNP1, VIL1, INHA/AE3, and PAX3) was identical in pigs. We found no clear difference between the gene order on pig Chr 15 and human Chr 2q.
Received: 4 November 1998 / Accepted: 8 February 1999 相似文献
998.
999.
Umberto Restuccia Egisto Boschetti Elisa Fasoli Frederic Fortis Luc Guerrier Angela Bachi Alexander V. Kravchuk Pier Giorgio Righetti 《Journal of Proteomics》2009,72(6):1061
The pre-treatment of biological extracts with the aim of detecting very low-abundance proteins generates complexity requiring a proper fractionation. Therefore the success of identifying all newly detectable species depends on the selected fractionation methods.In this context and starting from a human serum, where the dynamic concentration range was reduced by means of a preliminary treatment with a combinatorial hexapeptide ligand library, we fractionated the sample using a novel method based on the differences in isoelectric points of proteins by means of Solid-State Buffers (SSB) associated with cation exchangers. The number of fractions was limited to four and was compared to a classical anion exchange method generating the same number of fractions.What was observed is that when using SSB technology the protein redundancy between fractions was significantly reduced compared to ion exchange fractionation allowing thus a better detection of novel species. The analysis of trypsinized protein fractions by nanoLC-MS/MS confirmed that the SSB technology used is more discriminant than anion exchange chromatography fractionation.A sample fractionation by SSB after the reduction of dynamic concentration range can be accomplished without either adjustment of pH and ionic strength or protein concentration and cleanup. Both advantages over either classical chromatography or isoelectric fractionations allow approaching the discovery of markers of interest under easier conditions applicable in a variety of fields of investigation. 相似文献
1000.
Beatrice Cousin Emmanuel Ravet Sandrine Poglio Fabienne De Toni Mélanie Bertuzzi Hubert Lulka Ismahane Touil Mireille André Jean-Louis Grolleau Jean-Marie Péron Jean-Pierre Chavoin Philippe Bourin Luc Pénicaud Louis Casteilla Louis Buscail Pierre Cordelier 《PloS one》2009,4(7)