Light and tree size influence belowground development in yellow birch and sugar maple

The effects of light and tree size on the root architecture and mycorrhiza of yellow birch (Betula alleghaniensis Britton) and sugar maple (Acer saccharum Marsh) growing in the understory of deciduous forests in southern Qu

The ecology of pine forest soil fungi and their reaction following a forest fire

Bibliography: p. 138-145

Response to an ozone gradient of growth and enzymes implicated in tolerance to oxidative stress in Acer saccharum (Marsh.) seedlings

Two-year-old sugar maple (Acer saccharum Marsh.) seedlings were exposed in open top chambers to an extensive gradient of O3 (0 to 300 nL.L-1) during 85 days under two light environments (20% and 80% of full sun at noon on a sunny day). The growth of truncated seedlings (with one flush of leaves) and episodic seedlings (with two flushes) was decreased as O3 increased, especially the growth of the second flush which developed under the oxidative treatment. Visible leaf injuries developed during the season under high O3 concentrations. Survivalist growth strategy of sugar maple, as seen by the root/shoot ratio, together with the enzymatic stimulations of glucose 6-phosphate dehydrogenase, phosphoenolpyruvate carboxylase and glutathione reductase allowed the seedlings to tolerate the O3 doses. However, at the end of the season, the cumulative oxidative stress in the second flush of the episodic seedlings exposed to concentrations over 150 nL.L-1 O3 was too large and exceeded the capacity of seedlings for detoxification and repairDes semis d'érable à sucre (Acer saccharum Marsh.) de deux ans sont exposés en chambre à ciel ouvert à un large gradient d'O3 (0 to 300 nL.L-1) pendant 85 jours sous deux environnements lumineux (20 ou 80 % de plein soleil, journée ensoleillée à midi). Avec l'augmentation des concentrations d'O3, on observe une réduction de la croissance des semis ayant un ou deux flushs de feuilles. La réduction de croissance est particulièrement importante pour le deuxième flush de feuilles qui se développe pendant le traitement. Des dommages foliaires apparaissent durant la saison et sous fortes concentrations d'O3. La stratégie de croissance de survie de l'érable à sucre, montré par le rapport racine/tige, de même que les stimulations enzymatiques de la glucose 6-phosphate déhydrogenase, la phosphoénolpyruvate carboxylase et la glutathion réductase permettent une tolérance aux doses d'O3 reçues. Cependant, à la fin de la saison, le stress oxydatif cumulatif dans le deuxième flush des semis exposés à des concentrations d'O3 supérieures à 150 nL.L-1 est trop fort et excède la capacité de détoxification et réparation des semi

Association scan of 14,500 nonsynonymous SNPs in four diseases identifies autoimmunity variants

We have genotyped 14,436 nonsynonymous SNPs (nsSNPs) and 897 major histocompatibility complex (MHC) tag SNPs from 1,000 independent cases of ankylosing spondylitis ( AS), autoimmune thyroid disease (AITD), multiple sclerosis ( MS) and breast cancer ( BC). Comparing these data against a common control dataset derived from 1,500 randomly selected healthy British individuals, we report initial association and independent replication in a North American sample of two new loci related to ankylosing spondylitis, ARTS1 and IL23R, and confirmation of the previously reported association of AITD with TSHR and FCRL3. These findings, enabled in part by increased statistical power resulting from the expansion of the control reference group to include individuals from the other disease groups, highlight notable new possibilities for autoimmune regulation and suggest that IL23R may be a common susceptibility factor for the major 'seronegative' disease

Association scan of 14,500 nonsynonymous SNPs in four diseases identifies autoimmunity variants

We have genotyped 14,436 nonsynonymous SNPs (nsSNPs) and 897 major histocompatibility complex (MHC) tag SNPs from 1,000 independent cases of ankylosing spondylitis (AS), autoimmune thyroid disease (AITD), multiple sclerosis (MS) and breast cancer (BC). Comparing these data against a common control dataset derived from 1,500 randomly selected healthy British individuals, we report initial association and independent replication in a North American sample of two new loci related to ankylosing spondylitis, ARTS1 and IL23R, and confirmation of the previously reported association of AITD with TSHR and FCRL3. These findings, enabled in part by increased statistical power resulting from the expansion of the control reference group to include individuals from the other disease groups, highlight notable new possibilities for autoimmune regulation and suggest that IL23R may be a common susceptibility factor for the major 'seronegative' diseases

Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls

There is increasing evidence that genome-wide association (GWA) studies represent a powerful approach to the identification of genes involved in common human diseases. We describe a joint GWA study (using the Affymetrix GeneChip 500K Mapping Array Set) undertaken in the British population, which has examined similar to 2,000 individuals for each of 7 major diseases and a shared set of similar to 3,000 controls. Case-control comparisons identified 24 independent association signals at P < 5 X 10(-7): 1 in bipolar disorder, 1 in coronary artery disease, 9 in Crohn's disease, 3 in rheumatoid arthritis, 7 in type 1 diabetes and 3 in type 2 diabetes. On the basis of prior findings and replication studies thus-far completed, almost all of these signals reflect genuine susceptibility effects. We observed association at many previously identified loci, and found compelling evidence that some loci confer risk for more than one of the diseases studied. Across all diseases, we identified a large number of further signals (including 58 loci with single-point P values between 10(-5) and 5 X 10(-7)) likely to yield additional susceptibility loci. The importance of appropriately large samples was confirmed by the modest effect sizes observed at most loci identified. This study thus represents a thorough validation of the GWA approach. It has also demonstrated that careful use of a shared control group represents a safe and effective approach to GWA analyses of multiple disease phenotypes; has generated a genome-wide genotype database for future studies of common diseases in the British population; and shown that, provided individuals with non-European ancestry are excluded, the extent of population stratification in the British population is generally modest. Our findings offer new avenues for exploring the pathophysiology of these important disorders. We anticipate that our data, results and software, which will be widely available to other investigators, will provide a powerful resource for human genetics research