Catálogo de publicaciones - revistas

<jats:p>Large DNA assembly methodologies underlie milestone achievements in synthetic prokaryotic and budding yeast chromosomes. While budding yeast control chromosome inheritance through ~125-base pair DNA sequence-defined centromeres, mammals and many other eukaryotes use large, epigenetic centromeres. Harnessing centromere epigenetics permits human artificial chromosome (HAC) formation but is not sufficient to avoid rampant multimerization of the initial DNA molecule upon introduction to cells. We describe an approach that efficiently forms single-copy HACs. It employs a ~750-kilobase construct that is sufficiently large to house the distinct chromatin types present at the inner and outer centromere, obviating the need to multimerize. Delivery to mammalian cells is streamlined by employing yeast spheroplast fusion. These developments permit faithful chromosome engineering in the context of metazoan cells.</jats:p>

<jats:p>Ferroelectric nematic liquid crystals are formed by achiral molecules with large dipole moments. Their three-dimensional orientational order is described as unidirectionally polar. We demonstrate that the ground state of a flat slab of a ferroelectric nematic unconstrained by externally imposed alignment directions is chiral, with left- and right-handed twists of polarization. Although the helicoidal deformations and defect walls that separate domains of opposite handedness increase the elastic energy, the twists reduce the electrostatic energy and become weaker when the material is doped with ions. This work shows that the polar orientational order of molecules could trigger chirality in soft matter with no chemically induced chiral centers.</jats:p>

<jats:p> Visual preferences are important drivers of mate choice and sexual selection, but little is known of how they evolve at the genetic level. In this study, we took advantage of the diversity of bright warning patterns displayed by <jats:italic>Heliconius</jats:italic> butterflies, which are also used during mate choice. Combining behavioral, population genomic, and expression analyses, we show that two <jats:italic>Heliconius</jats:italic> species have evolved the same preferences for red patterns by exchanging genetic material through hybridization. Neural expression of <jats:italic>regucalcin1</jats:italic> correlates with visual preference across populations, and disruption of <jats:italic>regucalcin1</jats:italic> with CRISPR-Cas9 impairs courtship toward conspecific females, providing a direct link between gene and behavior. Our results support a role for hybridization during behavioral evolution and show how visually guided behaviors contributing to adaptation and speciation are encoded within the genome. </jats:p>

<jats:p>Cells connect with their environment through surface receptors and use physical tension in receptor–ligand bonds for various cellular processes. Single-molecule techniques have revealed bond strength by measuring “rupture force,” but it has long been recognized that rupture force is dependent on loading rate—how quickly force is ramped up. Thus, the physiological loading rate needs to be measured to reveal the mechanical strength of individual bonds in their functional context. We have developed an overstretching tension sensor (OTS) to allow more accurate force measurement in physiological conditions with single-molecule detection sensitivity even in mechanically active regions. We used serially connected OTSs to show that the integrin loading rate ranged from 0.5 to 4 piconewtons per second and was about three times higher in leukocytes than in epithelial cells.</jats:p>