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121.
Glenn Yannic Lo?c Pellissier Ma?l Le Corre Christian Dussault Louis Bernatchez Steeve D. C?té 《Proceedings. Biological sciences / The Royal Society》2014,281(1792)
Landscape heterogeneity plays a central role in shaping ecological and evolutionary processes. While species utilization of the landscape is usually viewed as constant within a year, the spatial distribution of individuals is likely to vary in time in relation to particular seasonal needs. Understanding temporal variation in landscape use and genetic connectivity has direct conservation implications. Here, we modelled the daily use of the landscape by caribou in Quebec and Labrador, Canada and tested its ability to explain the genetic relatedness among individuals. We assessed habitat selection using locations of collared individuals in migratory herds and static occurrences from sedentary groups. Connectivity models based on habitat use outperformed a baseline isolation-by-distance model in explaining genetic relatedness, suggesting that variations in landscape features such as snow, vegetation productivity and land use modulate connectivity among populations. Connectivity surfaces derived from habitat use were the best predictors of genetic relatedness. The relationship between connectivity surface and genetic relatedness varied in time and peaked during the rutting period. Landscape permeability in the period of mate searching is especially important to allow gene flow among populations. Our study highlights the importance of considering temporal variations in habitat selection for optimizing connectivity across heterogeneous landscape and counter habitat fragmentation. 相似文献
122.
123.
Louis Tong Jaime Chew Henry Yang Leonard PK Ang Donald TH Tan Roger W Beuerman 《BMC medical genomics》2009,2(1):1-21
Background
Pterygium is a common ocular surface disease characterized by fibrovascular invasion of the cornea and is sight-threatening due to astigmatism, tear film disturbance, or occlusion of the visual axis. However, the mechanisms for formation and post-surgical recurrence of pterygium are not understood, and a valid animal model does not exist. Here, we investigated the possible mechanisms of pterygium pathogenesis and recurrence.Methods
First we performed a genome wide expression analysis (human Affymetrix Genechip, >22000 genes) with principal component analysis and clustering techniques, and validated expression of key molecules with PCR. The controls for this study were the un-involved conjunctival tissue of the same eye obtained during the surgical resection of the lesions. Interesting molecules were further investigated with immunohistochemistry, Western blots, and comparison with tear proteins from pterygium patients.Results
Principal component analysis in pterygium indicated a signature of matrix-related structural proteins, including fibronectin-1 (both splice-forms), collagen-1A2, keratin-12 and small proline rich protein-1. Immunofluorescence showed strong expression of keratin-6A in all layers, especially the superficial layers, of pterygium epithelium, but absent in the control, with up-regulation and nuclear accumulation of the cell adhesion molecule CD24 in the pterygium epithelium. Western blot shows increased protein expression of beta-microseminoprotein, a protein up-regulated in human cutaneous squamous cell carcinoma. Gene products of 22 up-regulated genes in pterygium have also been found by us in human tears using nano-electrospray-liquid chromatography/mass spectrometry after pterygium surgery. Recurrent disease was associated with up-regulation of sialophorin, a negative regulator of cell adhesion, and never in mitosis a-5, known to be involved in cell motility.Conclusion
Aberrant wound healing is therefore a key process in this disease, and strategies in wound remodeling may be appropriate in halting pterygium or its recurrence. For patients demonstrating a profile of 'recurrence', it may be necessary to manage as a poorer prognostic case and perhaps, more adjunctive treatment after resection of the primary lesion. 相似文献124.
Michael N.G. James Gary D. Brayer Louis T.J. Delbaere Anita R. Sielecki Arieh Gertler 《Journal of molecular biology》1980,139(3):423-438
The bacterial serine protease, SGPB, was inhibited by two specific tripeptide chloromethyl ketones, N-t-butyloxycarbonyl-l-alanylglycyl-l-phenylalanine chloromethyl ketone (BocAGFCK) and N-t-butyloxycarbonyl-glycyl-l-leucyl-l-phenylalanine chloromethyl ketone (BocGLFCK). Crystals of the inhibited complexes were grown and examined by X-ray crystallographic methods. The peptide backbone of each inhibitor is bound by three hydrogen bonds to the main chain of residues Ser214 to Gly216. There are two well-characterized hydrophobic pockets, S1 and S2, on the surface of SGPB which accommodate the P1 and P2 side-chains of the BocGLFCK inhibitor. A conformational change of Tyr171 is induced by the binding of this inhibitor. Both inhibitors make two covalent bonds to the SGPB enzyme. The imidazole ring of His57 is alkylated at the N?2 atom and Oγ of Ser195 forms a hemiketal bond with the carbonyl-carbon atom of the inhibitor. Comparison of the binding modes of the two tripeptides in conjunction with the differences in their inhibition constants (KI) allows one to estimate the binding energy of the leucyl side-chain as ?2.6 kcal mol?1. The importance of an electrophilic component in the serine protease mechanism, which involves the polarization of the susceptible carbonyl bond of a substrate or inhibitor by the peptide NH groups of Gly193 and Ser195 is discussed. 相似文献
125.
Anisomycin Selectively Desensitizes Signalling Components Involved in Stress Kinase Activation and fos and jun Induction 总被引:5,自引:0,他引:5 下载免费PDF全文
Catherine A. Hazzalin Rozen Le Panse Eva Cano Louis C. Mahadevan 《Molecular and cellular biology》1998,18(4):1844-1854
Anisomycin, a translational inhibitor secreted by Streptomyces spp., strongly activates the stress-activated mitogen-activated protein (MAP) kinases JNK/SAPK (c-Jun NH2-terminal kinase/stress-activated protein kinase) and p38/RK in mammalian cells, resulting in rapid induction of immediate-early (IE) genes in the nucleus. Here, we have characterized this response further with respect to homologous and heterologous desensitization of IE gene induction and stress kinase activation. We show that anisomycin acts exactly like a signalling agonist in eliciting highly specific and virtually complete homologous desensitization. Anisomycin desensitization of a panel of IE genes (c-fos, fosB, c-jun, junB, and junD), using epidermal growth factor (EGF), basic fibroblast growth factor, (bFGF), tumor necrosis factor alpha (TNF-α), anisomycin, tetradecanoyl phorbol acetate (TPA), and UV radiation as secondary stimuli, was found to be extremely specific both with respect to the secondary stimuli and at the level of individual genes. Further, we show that anisomycin-induced homologous desensitization is caused by the fact that anisomycin no longer activates the JNK/SAPK and p38/RK MAP kinase cascades in desensitized cells. In anisomycin-desensitized cells, activation of JNK/SAPKs by UV radiation and hyperosmolarity is almost completely lost, and that of the p38/RK cascade is reduced to about 50% of the normal response. However, all other stimuli produced normal or augmented activation of these two kinase cascades in anisomycin-desensitized cells. These data show that anisomycin behaves like a true signalling agonist and suggest that the anisomycin-desensitized signalling component(s) is not involved in JNK/SAPK or p38/RK activation by EGF, bFGF, TNF-α, or TPA but may play a significant role in UV- and hyperosmolarity-stimulated responses. 相似文献
126.
Katja Behnke Maaria Loivamäki Ina Zimmer Heinz Rennenberg Jörg-Peter Schnitzler Sandrine Louis 《Photosynthesis research》2010,104(1):5-17
In the present study, we combined transient temperature and light stress (sunfleck) and comparably analyzed photosynthetic
gas exchange in Grey poplar which has been genetically modified in isoprene emission capacity. Overall, we demonstrate that
for poplar leaves the ability to emit isoprene is crucial to maintain photosynthesis when exposed to sunflecks. Net CO2 assimilation and electron transport rates were strongly impaired in sunfleck-treated non-isoprene emitting poplars. Similar
impairment was not detected when the leaves were exposed to high light (lightflecks) only. Within 10 h non-isoprene emitting
poplars recovered from sunfleck-related impairment as indicated by chlorophyll fluorescence and microarray analysis. Unstressed
leaves of non-isoprene emitting poplars had higher ascorbate contents, but also higher contents of malondialdehyde than wild-type.
Microarray analyses revealed lipid and chlorophyll degradation processes in the non-isoprene emitting poplars. Thus, there
is evidence for an adjustment of the antioxidative system in the non-isoprene emitting poplars even under normal growth conditions. 相似文献
127.
The patterns of five multilocus isozyme systems were investigated in seed, shoot and cotyledon tissue of two species of mesquite, Prosopis glandulosa var. glandulosa and P. pallida. The isozymes of malate dehydrogenase, peroxidase, esterase, alcohol dehydrogenase and acid phosphatase from each of these tissues were analysed by starch gel electrophoresis and specific histochemical stains. In the case of each enzyme system examined, there were distinctly different isozymes which could be utilized to differentiate between these two species. 相似文献
128.
Mark G. McDougall Louis P. Hosta Shiv Kumar Carl W. Fuller 《Nucleosides, nucleotides & nucleic acids》2013,32(4-5):1009-1011
Abstract 7-Chloro- and 7- Iodo-7-Deaza-2′-Deoxyguanosine-5′-Triphosphates were employed as substrates replacing dGTP, dITP, or 7-Deaza-2′-Deoxyguanosine-5′-Triphosphate in sequencing reactions with Thermo SequenaseTM. Analysis of the reaction products by denaturing gel electrophoresis indicates DNA containing these halogenated analogs can form strong secondary structures. 相似文献
129.
The isolation and properties of phenylalanine hydroxylase from human liver 总被引:3,自引:1,他引:3 下载免费PDF全文
Phenylalanine hydroxylase was prepared from human foetal liver and purified 800-fold; it appeared to be essentially pure. The phenylalanine hydroxylase activity of the liver was confined to a single protein of mol.wt. approx. 108000, but omission of a preliminary filtration step resulted in partial conversion into a second enzymically active protein of mol.wt. approx. 250000. Human adult and full-term infant liver also contained a single phenylalanine hydroxylase with molecular weights and kinetic parameters the same as those of the foetal enzyme; foetal, newborn and adult phenylalanine hydroxylase are probably identical. The K(m) values for phenylalanine and cofactor were respectively one-quarter and twice those found for rat liver phenylalanine hydroxylase. As with the rat enzyme, human phenylalanine hydroxylase acted also on p-fluorophenylalanine, which was inhibitory at high concentrations, and p-chlorophenylalanine acted as an inhibitor competing with phenylalanine. Iron-chelating and copper-chelating agents inhibited human phenylalanine hydroxylase. Thiol-binding reagents inhibited the enzyme but, as with the rat enzyme, phenylalanine both stabilized the human enzyme and offered some protection against these inhibitors. It is hoped that isolation of the normal enzyme will further the study of phenylketonuria. 相似文献
130.
Marcelo H Ratto Louis TJ Delbaere Yvonne A Leduc Roger A Pierson Gregg P Adams 《Reproductive biology and endocrinology : RB&E》2011,9(1):24