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101.
Flowering time divergence and genomic rearrangements in resynthesized Brassica polyploids (Brassicaceae) 总被引:5,自引:0,他引:5
102.
KAREN BOURGEOIS ERIC VIDAL VINCENT COMOR JEROME LEGRAND SYLVAIN DROMZEE 《The Journal of wildlife management》2008,72(5):1188-1193
Abstract: We tested whether colony-site availability could allow for an increase in the unusually small breeding populations of yelkouan shearwater (Puffinus yelkouan) on the islands of the Port-Cros National Park (France) if feral cat eradication were undertaken. Comparisons between colony and noncolony sites indicated yelkouan shearwaters preferred deep-soiled and low-outcrop-covered coastal sites. A substrate cover, light avoidance, and sea proximity model suggested that 17.5% of unoccupied sites are suitable for colony establishment. The low proportion of suitable sites currently used by yelkouan shearwaters suggests that these colonies could be refuges and that feral cat eradication will probably lead to a breeding population increase. 相似文献
103.
Timing of Kernel Development in Water-stressed Maize: Water Potentials and Abscisic Acid Concentrations 总被引:1,自引:0,他引:1
Maize (Zea mays L. cv. Pioneer 3925) subjected to post-anthesiswater stress during the first 2 weeks of kernel developmenthad lower leaf-water potentials and higher leaf-ABA concentrationsthan well-watered controls. There was a concomitant rise inABA concentration in kernel tissues 3 and 7 d after pollination(DAP), after which the concentration decreased to control levelsby 13 DAP. Kernel water potential, however, remained unchangedby the water stress. Radiolabelled ABA, fed to a leaf, was translocatedto kernels, where free ABA as well as several ABA metaboliteswere the major labelled fractions. This suggested that the stress-inducedkernel ABA was of maternal origin. Since ABA plays a putativerole in seed maturation of several crop species, and appliedABA or water stress often hastens seed development, we expectedthat a water-stress-induced rise in kernel ABA concentrationearly in grain development may serve to prematurely induce storage-productaccumulation. Zein, starch and several enzymes key to the starchsynthesis pathway followed the same course of induction throughoutthe experiment, with no difference between treatments Henceit was concluded that although water stress increased kernelABA independent of kernel water status, there was no apparenteffect of water stress or ABA on timing of early kernel developmentalprocesses. Zea mays L. cv. Pioncer 3925, maize, water stress, abscisic acid, endosperm development 相似文献
104.
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106.
ABSTRACT. Three acidic proteins (42 kD, 43 kD and 50 kD) were present in unusually high concentrations in cortical preparations of the Tetrahymena pattern mutant broadened cortical domains (bcd). Antisera to the 42-kD and 50-kD proteins bound to discharging mucocysts and food vacuole contents in both wild-type and mutant cells. Subsequent analysis revealed that bcd mutant cell pellicles possess five times more "docked" mucocysts than their wild-type counterparts. 相似文献
107.
Massive mortality of aspen following severe drought along the southern edge of the Canadian boreal forest 总被引:2,自引:0,他引:2
MICHAEL MICHAELIAN EDWARD H. HOGG RONALD J. HALL ERIC ARSENAULT 《Global Change Biology》2011,17(6):2084-2094
Drought‐induced, regional‐scale dieback of forests has emerged as a global concern that is expected to escalate under model projections of climate change. Since 2000, drought of unusual severity, extent, and duration has affected large areas of western North America, leading to regional‐scale dieback of forests in the southwestern US. We report on drought impacts on forests in a region farther north, encompassing the transition between boreal forest and prairie in western Canada. A central question is the significance of drought as an agent of large‐scale tree mortality and its potential future impact on carbon cycling in this cold region. We used a combination of plot‐based, meteorological, and remote sensing measures to map and quantify aboveground, dead biomass of trembling aspen (Populus tremuloides Michx.) across an 11.5 Mha survey area where drought was exceptionally severe during 2001–2002. Within this area, a satellite‐based land cover map showed that aspen‐dominated broadleaf forests occupied 2.3 Mha. Aerial surveys revealed extensive patches of severe mortality (>55%) resembling the impacts of fire. Dead aboveground biomass was estimated at 45 Mt, representing 20% of the total aboveground biomass, based on a spatial interpolation of plot‐based measurements. Spatial variation in percentage dead biomass showed a moderately strong correlation with drought severity. In the prairie‐like, southern half of the study area where the drought was most severe, 35% of aspen biomass was dead, compared with an estimated 7% dead biomass in the absence of drought. Drought led to an estimated 29 Mt increase in dead biomass across the survey area, corresponding to 14 Mt of potential future carbon emissions following decomposition. Many recent, comparable episodes of drought‐induced forest dieback have been reported from around the world, which points to an emerging need for multiscale monitoring approaches to quantify drought effects on woody biomass and carbon cycling across large areas. 相似文献
108.
RANDY T. CLARK JON E. SHAFF ERIC J. CRAFT SUSAN R. MCCOUCH DANIEL J. ANESHANSLEY LEON V. KOCHIAN 《Plant, cell & environment》2013,36(2):454-466
High‐throughput phenotyping of root systems requires a combination of specialized techniques and adaptable plant growth, root imaging and software tools. A custom phenotyping platform was designed to capture images of whole root systems, and novel software tools were developed to process and analyse these images. The platform and its components are adaptable to a wide range root phenotyping studies using diverse growth systems (hydroponics, paper pouches, gel and soil) involving several plant species, including, but not limited to, rice, maize, sorghum, tomato and Arabidopsis. The RootReader2D software tool is free and publicly available and was designed with both user‐guided and automated features that increase flexibility and enhance efficiency when measuring root growth traits from specific roots or entire root systems during large‐scale phenotyping studies. To demonstrate the unique capabilities and high‐throughput capacity of this phenotyping platform for studying root systems, genome‐wide association studies on rice (Oryza sativa) and maize (Zea mays) root growth were performed and root traits related to aluminium (Al) tolerance were analysed on the parents of the maize nested association mapping (NAM) population. 相似文献
109.
1. The presence of kairomone from the predaceous larval dipteran Chaoborus americanus can result in juvenile Daphnia pulex positioning themselves higher in the water column. Chaoborus normally lives at greater depth during the day, so this behavioural response by Daphnia will reduce its encounter rate with the predator and enhance survival. 2. Behavioural observations of seven clones from a single population were made under four treatments (with and without Chaoborus kairomone prior to and/or during experiments). 3. All clones moved higher when exposed to kairomones during behavioural observations. Six moved higher when kairomone was added prior to the experiment (i.e. pre‐conditioned), while the other clone went lower, providing evidence for the presence of genetic variation in induced behaviour. When this clone was removed from the analysis, the evidence for genetic variation in induced response disappeared. 4. Juvenile Daphnia that were pre‐conditioned had a significantly greater response than those that had no previous exposure. Of the total shift in depth (comparing treatment and control means), 38% was due to prior exposure to the kairomone (‘preconditioning’), while 62% was due to exposure during the 2‐h experiments when the depth selection was assessed. When the effect of the one clone with a qualitatively different response was removed, these two figures became 45% and 55%, respectively. 5. The enhanced effect of prior exposure to the kairomone during development suggests that such exposure causes greater sensitivity to the kairomone. 相似文献
110.
The evolutionary dynamics of the tetra-nucleotide microsatellite locus Spl-106 were investigated at the repeat and flanking sequences in 137 individuals of 15 Acipenseriform species, giving 93 homologous
sequences, which were detected in 11 out of 15 species. Twenty-three haplotypes of flanking sequences and three distinct types
of repeats, type I, type II and type III, were found within these 93 sequences. The MS-Align phylogenetic method, newly applied
to microsatellite sequences, permitted us to understand the repeat and flanking sequence evolution of Spl-106 locus. The flanking region of locus Spl-106 was highly conserved among the species of genera Acipenser, Huso and Scaphirhynchus, which diverged about 150 million years ago (Mya). The rate of flanking sequence divergence at the microsatellite locus Spl-106 in sturgeons is between 0.011% and 0.079% with an average at 0.028% per million years. Sequence alignment and phylogenetic
trees produced by MS-Align showed that both the flanking and repeat regions can cluster the alleles of different species into
Pacific and Atlantic lineages. Our results show a synchronous evolutionary pattern between the flanking and repeat regions.
Moreover, the coexistence of different repeat types in the same species, even in the same individual, is probably due to two
duplication events encompassing the locus Spl-106 that occurred during the divergence of Pacific lineage. The first occured before the diversification of Pacific species (121–96 Mya)
and led to repeat types I and II. The second occurred more recently, just before the speciation of A. sinensis and A. dabryanus (69–10 Mya), and led to repeat type III. Sequences in the same species with different repeat types probably corresponds to
paralogous loci. This study sheds a new light on the evolutionary mechanisms that shape the complex microsatellite loci involving
different repeat types. 相似文献