Structure of a NHEJ polymerase-mediated DNA synaptic complex     

Brissett NC  Pitcher RS  Juarez R  Picher AJ  Green AJ  Dafforn TR  Fox GC  Blanco L  Doherty AJ 《Science (New York, N.Y.)》2007,318(5849):456-459

Nonhomologous end joining (NHEJ) is a critical DNA double-strand break (DSB) repair pathway required to maintain genome stability. Many prokaryotes possess a minimalist NHEJ apparatus required to repair DSBs during stationary phase, composed of two conserved core proteins, Ku and ligase D (LigD). The crystal structure of Mycobacterium tuberculosis polymerase domain of LigD mediating the synapsis of two noncomplementary DNA ends revealed a variety of interactions, including microhomology base pairing, mismatched and flipped-out bases, and 3' termini forming hairpin-like ends. Biochemical and biophysical studies confirmed that polymerase-induced end synapsis also occurs in solution. We propose that this DNA synaptic structure reflects an intermediate bridging stage of the NHEJ process, before end processing and ligation, with both the polymerase and the DNA sequence playing pivotal roles in determining the sequential order of synapsis and remodeling before end joining.  相似文献   

A comparison of mortality rates between top height trees and average site trees   总被引：1，自引：0，他引：1  

Daniel Mailly  Mélanie Gaudreault  Geneviève Picher  Isabelle Auger  David Pothier 《Annals of Forest Science》2009,66(2):202-202

? Although comparisons between methods of selecting trees for site index estimates are well documented in the literature, little is known on mortality rates of different canopy tree cohorts used for that purpose.

? This study was initiated to test the hypothesis that the mortality rates of top height trees are lower than those of codominants only or a combination of codominant and dominant trees. To test this hypothesis, we used records from a network of permanent sample plots in Québec and studied the fate of different cohorts of site trees for five different species.

? Our results did not show clear evidence of lower mortality rates for top height trees. Instead we found that depending on the species, top height trees have lower (Populus tremuloides, Pinus banksiana), higher (Picea mariana, Abies balsamea) or equal mortality rates (Betula papyrifera) than codominant trees or codominant and dominant trees combined.

? These results suggest a tendency for shade intolerant species to maintain lower top height tree mortality rates over time when compared to shade tolerant species. In the latter case, it is also shown that spruce budworm epidemics (Choristoneura fumiferana) did not change the pattern of mortality rates of site trees of A. balsamea.

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Initial distance to Kalmia angustifolia as a predictor of planted conifer growth     

Thiffault  Nelson  Picher  Geneviève  Auger  Isabelle 《New Forests》2012,43(5-6):849-868

New Forests - In the Canadian boreal forest, conifer plantations are mainly used to overcome poor natural regeneration following harvesting or wildfires. However, competitive interactions can...  相似文献