Tissue Engineering The Neural Retina With Human Embryonic Stem Cells: Exploring The Role Of The Retinal Pigment Epithelium

In order to restore vision in the late stages of retinal degeneration, it is necessary to address loss of cells from both the retinal pigment epithelium (RPE) and the neural retina. As a step towards generating neural retinal tissue for translational studies, we evaluated a biodegradable polymer scaffold as a three-dimensional vehicle for the directed differentiation of H9 human embryonic stem cells (H9-hESC) into neural retina. Polymer scaffolds were electrospun from 14% w/v polycaprolactone (PCL), approximated the thickness of native neural retina, and consisted of loose, randomly oriented fibers of subcellular diameter. H9-hESC were seeded to PCL scaffolds, cultured in retinal differentiation media, and compared by immunofluorescence and quantitative real-time RT-PCR (qRT2-PCR) to H9-hESC differentiated on porous Transwell filters. H9-hESC cultured on PCL scaffolds migrated up to 40 microns into the scaffold and expressed markers consistent with cellular proliferation and differentiation into neural retina. Cultures on PCL scaffolds showed equivalent or increased expression of neural retinal markers compared to those grown on Transwell filters. We then co-cultured H9-hESC differentiated on PCL scaffolds with monolayers of RPE and found that each tissue affects the other\u27s maturation. Co-cultured neural retina expressed higher levels of retinal maturation markers, and the transepithelial resistance (TER) of co-cultured RPE was more consistent with physiologic values. Finally, we found that TRP channels expressed in RPE localize to various subdomains of the RPE apical membrane, where they potentially mediate RPE-retinal interactions by sensing the ionic composition of the subretinal space

DIVE in the cosmic web: voids with Delaunay Triangulation from discrete matter tracer distributions

We present a novel parameter-free cosmological void finder (\textsc{dive}, Delaunay TrIangulation Void findEr) based on Delaunay Triangulation (DT), which efficiently computes the empty spheres constrained by a discrete set of tracers. We define the spheres as DT voids, and describe their properties, including an universal density profile together with an intrinsic scatter. We apply this technique on 100 halo catalogues with volumes of 2.5\,$h^{-1}$Gpc side each, with a bias and number density similar to the BOSS CMASS Luminous Red Galaxies, performed with the \textsc{patchy} code. Our results show that there are two main species of DT voids, which can be characterised by the radius: they have different responses to halo redshift space distortions, to number density of tracers, and reside in different dark matter environments. Based on dynamical arguments using the tidal field tensor, we demonstrate that large DT voids are hosted in expanding regions, whereas the haloes used to construct them reside in collapsing ones. Our approach is therefore able to efficiently determine the troughs of the density field from galaxy surveys, and can be used to study their clustering. We further study the power spectra of DT voids, and find that the bias of the two populations are different, demonstrating that the small DT voids are essentially tracers of groups of haloes.Comment: 12 pages, 13 figure

Dissecting the genome-wide evolution and function of R2R3-MYB transcription factor family in Rosa chinensis

Rosa chinensis, an important ancestor species of Rosa hybrida, the most popular ornamental plant species worldwide, produces flowers with diverse colors and fragrances. The R2R3-MYB transcription factor family controls a wide variety of plant-specific metabolic processes, especially phenylpropanoid metabolism. Despite their importance for the ornamental value of flowers, the evolution of R2R3-MYB genes in plants has not been comprehensively characterized. In this study, 121 predicted R2R3-MYB gene sequences were identified in the rose genome. Additionally, a phylogenomic synteny network (synnet) was applied for the R2R3-MYB gene families in 35 complete plant genomes. We also analyzed the R2R3-MYB genes regarding their genomic locations, Ka/Ks ratio, encoded conserved motifs, and spatiotemporal expression. Our results indicated that R2R3-MYBs have multiple synteny clusters. The RcMYB114a gene was included in the Rosaceae-specific Cluster 54, with independent evolutionary patterns. On the basis of these results and an analysis of RcMYB114a-overexpressing tobacco leaf samples, we predicted that RcMYB114a functions in the phenylpropanoid pathway. We clarified the relationship between R2R3-MYB gene evolution and function from a new perspective. Our study data may be relevant for elucidating the regulation of floral metabolism in roses at the transcript level

A comment on "Ab initio calculations of pressure-dependence of high-order elastic constants using finite deformations approach" by I. Mosyagin, A.V. Lugovskoy, O.M. Krasilnikov, Yu.Kh. Vekilov, S.I. Simak and I.A. Abrikosov

Recently, I. Mosyagin, A.V. Lugovskoy, O.M. Krasilnikov, Yu.Kh. Vekilov, S.I. Simak and I.A. Abrikosov in the paper: "Ab initio calculations of pressure-dependence of high-order elastic constants using finite deformations approach"[Computer Physics Communications 220 (2017) 2030] presented a description of a technique for ab initio calculations of the pressure dependence of second- and third-order elastic constants. Unfortunately, the work contains serious and fundamental flaws in the field of finite-deformation solid mechanics.Comment: 3 pages, 0 figure