18 research outputs found
The Capsella rubella genome and the genomic consequences of rapid mating system evolution. Nat Gen 45: 831–835. doi:10.1038/ng.2669. . CC-BY-NC-ND 4.0 International licensepeer-reviewed) is the author/funder. It is made available under a The copyright hol
3 1 l e t t e r s The shift from outcrossing to selfing is common in flowering plants 1,2 , but the genomic consequences and the speed at which they emerge remain poorly understood. An excellent model for understanding the evolution of self fertilization is provided by Capsella rubella, which became self compatible <200,000 years ago. We report a C. rubella reference genome sequence and compare RNA expression and polymorphism patterns between C. rubella and its outcrossing progenitor Capsella grandiflora. We found a clear shift in the expression of genes associated with flowering phenotypes, similar to that seen in Arabidopsis, in which self fertilization evolved about 1 million years ago. Comparisons of the two Capsella species showed evidence of rapid genome-wide relaxation of purifying selection in C. rubella without a concomitant change in transposable element abundance. Overall we document that the transition to selfing may be typified by parallel shifts in gene expression, along with a measurable reduction of purifying selection
Leading Grassroots Change in the Academy: Strategic and Ideological Adaptation in the Civic Engagement Movement
The Capsella rubella genome and the genomic consequences of rapid mating system evolution
The shift from outcrossing to selfing is common in flowering plants, but the genomic consequences and the speed at which they emerge remain poorly understood. An excellent model for understanding the evolution of self fertilization is provided by Capsella rubella, which became self compatible <200,000 years ago. We report a C. rubella reference genome sequence and compare RNA expression and polymorphism patterns between C. rubella and its outcrossing progenitor Capsella grandiflora. We found a clear shift in the expression of genes associated with flowering phenotypes, similar to that seen in Arabidopsis, in which self fertilization evolved about 1 million years ago. Comparisons of the two Capsella species showed evidence of rapid genome-wide relaxation of purifying selection in C. rubella without a concomitant change in transposable element abundance. Overall we document that the transition to selfing may be typified by parallel shifts in gene expression, along with a measurable reduction of purifying selection
Exclusive ρ 0 meson photoproduction with a leading neutron at HERA
A first measurement is presented of exclusive photoproduction of mesons associated with leading neutrons at HERA. The data were taken with the H1 detector in the years 2006 and 2007 at a centre-of-mass energy of GeV and correspond to an integrated luminosity of 1.16 pb. The mesons with transverse momenta , are detected in the Forward Neutron Calorimeter. The phase space of the measurement is defined by the photon virtuality GeV, the total energy of the photon–proton system GeV and the polar angle of the leading neutron mrad. The cross section of the reaction is measured as a function of several variables. The data are interpreted in terms of a double peripheral process, involving pion exchange at the proton vertex followed by elastic photoproduction of a meson on the virtual pion. In the framework of one-pion-exchange dominance the elastic cross section of photon-pion scattering, , is extracted. The value of this cross section indicates significant absorptive corrections for the exclusive reaction
Diffractive Photoproduction of Mesons with Large Momentum Transfer at HERA
The diffractive photoproduction of rho mesons, e p \to e rho Y, with large
momentum transfer squared at the proton vertex, |t|, is studied with the H1
detector at HERA using an integrated luminosity of 20.1 pb^{-1}. The
photon-proton centre of mass energy spans the range 75 < W < 95 GeV, the photon
virtuality is restricted to Q^2 < 0.01 GeV^2 and the mass M_Y of the proton
remnant is below 5 GeV. The t dependence of the cross section is measured for
the range 1.5 < |t| < 10.0 GeV^2 and is well described by a power law, dsigma/
d|t| \propto |t|^{-n}. The spin density matrix elements, which provide
information on the helicity structure of the interaction, are extracted using
measurements of angular distributions of the rho decay products. The data
indicate a violation of s-channel helicity conservation, with contributions
from both single and double helicity-flip being observed. The results are
compared to the predictions of perturbative QCD models.Comment: 19 pages, 5 figures, 2 table