Purpose To assess for activation of the unfolded protein response in corneal endothelium of Fuchs endothelial corneal dystrophy patients. Design Retrospective comparative case series of laboratory specimens Methods Corneal specimens of patients with Fuchs dystrophy and controls with corneal pathologies other than Fuchs dystrophy were evaluated by transmission electron microscopy (TEM) to evaluate for structural changes of the rough endoplasmic reticulum in corneal endothelium. TEM images were evaluated for alterations of rough endoplasmic reticulum as sign of unfolded protein response. Normal autopsy eyes, Fuchs dystrophy, and keratoconus corneas were used for immunohistochemistry. Immunohistochemistry was performed on formalin-fixed, paraffin-embedded sections of patient corneas for three unfolded protein response markers (GRP78, phospho-eIF2α, CHOP) and two apoptosis markers (Caspase 3 and 9). Immunohistochemistry signal quantitation of corneal endothelium for evaluation of marker expression was performed using automated software. Corneal sections were assessed quantitatively for levels of immunohistochemistry marker expression. Results TEM showed enlargement of rough endoplasmic reticulum in corneal endothelium of all Fuchs dystrophy specimens. Immunohistochemistry quantitation demonstrated a significant increase in mean signal in corneal endothelium from Fuchs dystrophy patients for markers GRP78, phospho-eIF2α, CHOP and caspase 9, compared with non- Fuchs dystrophy corneas (p < 0.05). Conclusions Results of both TEM and immunohistochemistry indicate activation of unfolded protein response in Fuchs dystrophy. Unfolded protein response activation leads to endothelial cell apoptosis in Fuchs dystrophy and may play a central pathogenic role in this disease.

We study the stellar-to-halo mass relation (SHMR) for central and satellite galaxies with total dynamical masses above $10^{10.5}~\rm {M}_\odot$ using the suite of cosmological magneto-hydrodynamical simulations IllustrisTNG. In particular, we quantify environmental effects on satellite populations from TNG50, TNG100, and TNG300 located within the virial radius of group- and cluster-like hosts with total masses of $10^{12-15.2}~\rm {M}_\odot$. At fixed stellar mass, the satellite SHMR exhibits a distinct shift towards lower dynamical mass compared to the SHMR of centrals. Conversely, at fixed dynamical mass, satellite galaxies appear to have larger stellar-to-total mass fractions than centrals by up to a factor of a few. The systematic deviation from the central SHMR is larger for satellites in more massive hosts, at smaller cluster-centric distances, with earlier infall times, and that inhabit higher local density environments; moreover, it is in place already at early times (z ≲ 2). Systematic environmental effects might contribute to the perceived galaxy-to-galaxy variation in the measured SHMR when galaxies cannot be separated into satellites and centrals. The SHMR of satellites exhibits a larger scatter than centrals (by up to ∼0.8 dex), over the whole range of dynamical mass. The shift of the satellite SHMR results mostly from tidal stripping of their dark matter, which affects satellites in an outside-in fashion: the departure of the satellite SHMR from the centrals’ relation diminishes for measurements of dynamical mass in progressively smaller apertures. Finally, we provide a family of fitting functions for the SHMR predicted by IllustrisTNG.

Virgo is a dynamically young galaxy cluster with substructure in its spatial and kinematic distribution. Here, we simultaneously study the phase-space distribution and the main characteristics of Virgo's galaxies, particularly its most abundant galaxy population -the early-type dwarfs -to understand their environmental transformation histories. Aside from known correlations with morphological types -like the larger average clustercentric distance of late-type galaxies -we find an intriguing behavior of early types with magnitudes −17 ≥ M r ≥ −18. They show a large velocity spread and an asymmetric phase-space distribution, similar to the late-type galaxies and different from the early types just one magnitude brighter/fainter. Furthermore, we find a close phase-space aggregation of early-type dwarfs at large clustercentric distance and high relative velocity. Nearly all of them show signatures of disk components and their colors imply stellar ages that are younger than the population average. They are not located closely together but spread azimuthally around the cluster center. We show that this is expected from simulations of an infalling galaxy group that slowly gets dispersed after its first pericentric passage. We thus conclude that these galaxies are recent arrivals, and that the peculiar phase-space distribution of early-type dwarfs is evidence for the ongoing growth of this galaxy population. Studying galaxies based on their phase space correlations is a unique way to compare the properties of recent and older cluster members, and to understand which environment most influenced their present-day characteristics.

We study the abundance of satellite galaxies around 198 Milky Way- (MW) and M31-like hosts in TNG50, the final instalment in the IllustrisTNG suite of cosmological magnetohydrodynamical simulations. MW/M31-like analogues are defined as disky galaxies with stellar masses of $M_* = 10^{10.5 - 11.2}~\rm {M}_\odot$ in relative isolation at z = 0. By defining satellites as galaxies with $M_* \ge 5\times 10^{6}~\rm {M}_\odot$ within $300~\rm {kpc}$ (3D) of their host, we find a remarkable level of diversity and host-to-host scatter across individual host galaxies. The median TNG50 MW/M31-like galaxy hosts a total of $5^{+6}_{-3}$ satellites with $M_* \ge 8 \times 10^6~\rm {M}_\odot$, reaching up to $M_* \sim 10^{8.5^{+0.9}_{-1.1}}~\rm {M}_\odot$. Even at a fixed host halo mass of $10^{12}~\rm {M}_\odot$, the total number of satellites ranges between 0 − 11. The abundance of subhaloes with $M_\rm {dyn} \ge 5 \times 10^7~\rm {M}_\odot$ is larger by a factor of more than 10. The number of all satellites (subhaloes) ever accreted is larger by a factor of 4 − 5 (3 − 5) than those surviving to z = 0. Hosts with larger galaxy stellar mass, brighter K-band luminosity, more recent halo assembly, and – most significantly – larger total halo mass typically have a larger number of surviving satellites. The satellite abundances around TNG50 MW/M31-like galaxies are consistent with those of mass-matched hosts from observational surveys (e.g. SAGA) and previous simulations (e.g. Latte). While the observed MW satellite system falls within the TNG50 scatter across all stellar masses considered, M31 is slightly more satellite-rich than our 1σ scatter but well consistent with the high-mass end of the TNG50 sample. We find a handful of systems with both a Large and a Small Magellanic Cloud-like satellite. There is no missing satellites problem according to TNG50.