Características morfogênicas de cultivares de azevém-anual diploide e tetraploides.

O azevém-anual (Lolium multiflorum Lam.) é amplamente utilizado no Sul do Brasil, com grande importância nos sistemas integrados de produção agropecuária, pois é a principal espécie forrageira de inverno, apresentando boa produção e qualidade. Diversas cultivares de azevém-anual diploides e tetraploides têm sido registradas e lançadas no mercado nos últimos anos, muitas diferindo de cultivares mais antigas. Materiais diploides e tetraploides podem apresentar variações no tamanho de perfilhos, folhas e sementes. Definir características morfogênicas tem implicações no manejo, estimativa do potencial produtivo e pode ser um recurso para comparação das cultivares. O objetivo deste trabalho foi avaliar características morfogênicas de 6 cultivares de azevém-anual, uma delas diploide e as outras tetraploides. Foram testadas em blocos ao acaso com quatro repetições, as cultivares: Empasc 304 (diplóide) e Potro, BarHQ, Barjumbo, KLm 138, e Maximus (Tetraploides). Não houve diferença significativa entre as cultivares para nenhuma das características morfogênicas avaliadas (P>0.055). Os valores médios das variáveis foram de 2.25 +- 0.17 cm dia-1 para a taxa de alongamento foliar, 0.75 +- 0.04 cm dia-1 para taxa de senescência foliar, 0.15 +- 0.006 cm dia-1 para taxa de alongamento de pseudocolmos, 9.71 +- 1.38 dias para filocrono e duração de vida de folhas foi de 41.97 +- 4.52 dias

Single-molecule experiments in biological physics: methods and applications

I review single-molecule experiments (SME) in biological physics. Recent technological developments have provided the tools to design and build scientific instruments of high enough sensitivity and precision to manipulate and visualize individual molecules and measure microscopic forces. Using SME it is possible to: manipulate molecules one at a time and measure distributions describing molecular properties; characterize the kinetics of biomolecular reactions and; detect molecular intermediates. SME provide the additional information about thermodynamics and kinetics of biomolecular processes. This complements information obtained in traditional bulk assays. In SME it is also possible to measure small energies and detect large Brownian deviations in biomolecular reactions, thereby offering new methods and systems to scrutinize the basic foundations of statistical mechanics. This review is written at a very introductory level emphasizing the importance of SME to scientists interested in knowing the common playground of ideas and the interdisciplinary topics accessible by these techniques. The review discusses SME from an experimental perspective, first exposing the most common experimental methodologies and later presenting various molecular systems where such techniques have been applied. I briefly discuss experimental techniques such as atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers (MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I then present several applications of SME to the study of nucleic acids (DNA, RNA and DNA condensation), proteins (protein-protein interactions, protein folding and molecular motors). Finally, I discuss applications of SME to the study of the nonequilibrium thermodynamics of small systems and the experimental verification of fluctuation theorems. I conclude with a discussion of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond. Matt

Mapping cortical brain asymmetry in 17,141 healthy individuals worldwide via the ENIGMA Consortium.

Hemispheric asymmetry is a cardinal feature of human brain organization. Altered brain asymmetry has also been linked to some cognitive and neuropsychiatric disorders. Here, the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium presents the largest-ever analysis of cerebral cortical asymmetry and its variability across individuals. Cortical thickness and surface area were assessed in MRI scans of 17,141 healthy individuals from 99 datasets worldwide. Results revealed widespread asymmetries at both hemispheric and regional levels, with a generally thicker cortex but smaller surface area in the left hemisphere relative to the right. Regionally, asymmetries of cortical thickness and/or surface area were found in the inferior frontal gyrus, transverse temporal gyrus, parahippocampal gyrus, and entorhinal cortex. These regions are involved in lateralized functions, including language and visuospatial processing. In addition to population-level asymmetries, variability in brain asymmetry was related to sex, age, and intracranial volume. Interestingly, we did not find significant associations between asymmetries and handedness. Finally, with two independent pedigree datasets (n = 1,443 and 1,113, respectively), we found several asymmetries showing significant, replicable heritability. The structural asymmetries identified and their variabilities and heritability provide a reference resource for future studies on the genetic basis of brain asymmetry and altered laterality in cognitive, neurological, and psychiatric disorders