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The phenotypic responses of functional traits in natural populations are driven by genetic diversity and phenotypic plasticity. These two mechanisms enable trees to cope with rapid climate change. We studied two European temperate tree species (sessile oak and European beech), focusing on (i) in situ variations of leaf functional traits (morphological and physiological) along two altitudinal gradients and (ii) the extent to which these variations were under environmental and/or genetic control using a common garden experiment. For all traits, altitudinal trends tended to be highly consistent between species and transects. For both species, leaf mass per area displayed a positive linear correlation with altitude, whereas leaf size was negatively correlated with altitude. We also observed a significant increase in leaf physiological performance with increasing altitude: populations at high altitudes had higher maximum rates of assimilation, stomatal conductance and leaf nitrogen content than those at low altitudes. In the common garden experiment, genetic differentiation between populations accounted for 0-28% of total phenotypic variation. However, only two traits (leaf mass per area and nitrogen content) exhibited a significant cline. The combination of in situ and common garden experiments used here made it possible to demonstrate, for both species, a weaker effect of genetic variation than of variations in natural conditions, suggesting a strong effect of the environment on leaf functional traits. Finally, we demonstrated that intrapopulation variability was systematically higher than interpopulation variability, whatever the functional trait considered, indicating a high potential capacity to adapt to climate change. 相似文献
613.
Ferritins are the main iron storage proteins found in animals, plants, and bacteria. The capacity to store iron in ferritin is essential for life in mammals, but the mechanism by which cytosolic iron is delivered to ferritin is unknown. Human ferritins expressed in yeast contain little iron. Human poly (rC)-binding protein 1 (PCBP1) increased the amount of iron loaded into ferritin when expressed in yeast. PCBP1 bound to ferritin in vivo and bound iron and facilitated iron loading into ferritin in vitro. Depletion of PCBP1 in human cells inhibited ferritin iron loading and increased cytosolic iron pools. Thus, PCBP1 can function as a cytosolic iron chaperone in the delivery of iron to ferritin. 相似文献
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Miyake N Chilton J Psatha M Cheng L Andrews C Chan WM Law K Crosier M Lindsay S Cheung M Allen J Gutowski NJ Ellard S Young E Iannaccone A Appukuttan B Stout JT Christiansen S Ciccarelli ML Baldi A Campioni M Zenteno JC Davenport D Mariani LE Sahin M Guthrie S Engle EC 《Science (New York, N.Y.)》2008,321(5890):839-843
Duane's retraction syndrome (DRS) is a complex congenital eye movement disorder caused by aberrant innervation of the extraocular muscles by axons of brainstem motor neurons. Studying families with a variant form of the disorder (DURS2-DRS), we have identified causative heterozygous missense mutations in CHN1, a gene on chromosome 2q31 that encodes alpha2-chimaerin, a Rac guanosine triphosphatase-activating protein (RacGAP) signaling protein previously implicated in the pathfinding of corticospinal axons in mice. We found that these are gain-of-function mutations that increase alpha2-chimaerin RacGAP activity in vitro. Several of the mutations appeared to enhance alpha2-chimaerin translocation to the cell membrane or enhance its ability to self-associate. Expression of mutant alpha2-chimaerin constructs in chick embryos resulted in failure of oculomotor axons to innervate their target extraocular muscles. We conclude that alpha2-chimaerin has a critical developmental function in ocular motor axon pathfinding. 相似文献
616.
Klein RJ Zeiss C Chew EY Tsai JY Sackler RS Haynes C Henning AK SanGiovanni JP Mane SM Mayne ST Bracken MB Ferris FL Ott J Barnstable C Hoh J 《Science (New York, N.Y.)》2005,308(5720):385-389
Age-related macular degeneration (AMD) is a major cause of blindness in the elderly. We report a genome-wide screen of 96 cases and 50 controls for polymorphisms associated with AMD. Among 116,204 single-nucleotide polymorphisms genotyped, an intronic and common variant in the complement factor H gene (CFH) is strongly associated with AMD (nominal P value <10(-7)). In individuals homozygous for the risk allele, the likelihood of AMD is increased by a factor of 7.4 (95% confidence interval 2.9 to 19). Resequencing revealed a polymorphism in linkage disequilibrium with the risk allele representing a tyrosine-histidine change at amino acid 402. This polymorphism is in a region of CFH that binds heparin and C-reactive protein. The CFH gene is located on chromosome 1 in a region repeatedly linked to AMD in family-based studies. 相似文献
617.
Type I ubiquitin-like proteins constitute a family of protein modifiers. Here we report the identification of a posttranslational protein modifier from Saccharomyces cerevisiae, Hub1. Overexpression of Hub1 resulted in enhanced conjugate formation when its carboxyl-terminal residue was deleted, suggesting that mature Hub1 may be produced by proteolytic processing. In vivo targets of Hub1 conjugation included cell polarity factors Sph1 and Hbt1. In the hub1Delta mutant, the subcellular localization of both Hbt1 and Sph1 was disrupted, and cell polarization during the formation of mating projections was defective. Consistent with these polarization defects, the hub1Delta mutant was deficient in mating. 相似文献
618.
Wang JW Howson JM Ghansah T Desponts C Ninos JM May SL Nguyen KH Toyama-Sorimachi N Kerr WG 《Science (New York, N.Y.)》2002,295(5562):2094-2097
Natural killer cell (NK) receptors for major histocompatibility complex (MHC) class I influence engraftment and graft-versus-tumor effects after allogeneic bone marrow transplantation. We find that SH2-containing inositol phosphatase (SHIP) influences the repertoire of NK receptors. In adult SHIP-/- mice, the NK compartment is dominated by cells that express two inhibitory receptors capable of binding either self or allogeneic MHC ligands. This promiscuous repertoire has significant functional consequences, because SHIP-/- mice fail to reject fully mismatched allogeneic marrow grafts and show enhanced survival after such transplants. Thus, SHIP plays an important role in two processes that limit the success of allogeneic marrow transplantation: graft rejection and graft-versus-host disease. 相似文献
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620.
Jackson CM 《Science (New York, N.Y.)》2005,308(5729):1750-1752