High resolution imaging and interpretation of three-dimensional RPE sheet structure.

The retinal pigment epithelium (RPE) is a monolayer of pigmented cells which plays an essential role in visual function via its interaction with the adjacent neural retina. Typically hexagonal in shape and arranged in a mosaic-like pattern, RPE cells maintain a relatively uniform size and arrangement in healthy eyes. Under stress or disease conditions such as age-related macular degeneration (AMD) and other heritable vision disorders, individual RPE cell dysmorphia has been observed.

Pentosan Polysulfate Sodium Causes Diminished Function and Subtle Morphological Changes in Retina and RPE of Mice.

Purpose: There are numerous reports of a distinctive maculopathy in adults exposed to pentosan polysulfate sodium (PPS), a drug prescribed to treat bladder discomfort associated with interstitial cystitis. We tested whether PPS treatment of mice injures RPE or retina to provide insight into the etiology of the human condition.

Methods: Mice were fed PPS-supplemented chow over 14 months.

Age-Related RPE changes in Wildtype C57BL/6J Mice between 2 and 32 Months.

Purpose: This study provides a systematic evaluation of age-related changes in RPE cell structure and function using a morphometric approach. We aim to better capture nuanced predictive changes in cell heterogeneity that reflect loss of RPE integrity during normal aging. Using C57BL6/J mice ranging from P60-P730, we sought to evaluate how regional changes in RPE shape reflect incremental losses in RPE cell function with advancing age.

Changes in neuropeptide large dense core vesicle trafficking dynamics contribute to adaptive responses to a systemic homeostatic challenge.

Neuropeptides are packed into large dense core vesicles (LDCVs) that are transported from the soma out into their processes. Limited information exists regarding mechanisms regulating LDCV trafficking, particularly during challenges to bodily homeostasis. Addressing this gap, we used 2-photon imaging in an preparation to study LDCVs trafficking dynamics in vasopressin (VP) neurons, which traffic and release neuropeptide from their dendrites and axons.

Protocols for measuring cold-evoked neural activity and cold tolerance in Drosophila larvae following fictive cold acclimation.

Here, we outline protocols to study cold acclimation in Drosophila from a neurobiological perspective, starting with fictive cold acclimation using a custom-built optogenetics-housing apparatus we call the OptoBox. We also provide detailed steps for single-unit electrophysiological recordings from larval cold nociceptors and a high-throughput cold-tolerance assay. These protocols expand the toolkit for the study of insect cold acclimation and nociception.

Identification of a neural basis for cold acclimation in larvae.

Low temperatures can be fatal to insects, but many species have evolved the ability to cold acclimate, thereby increasing their cold tolerance. It has been previously shown that larvae perform cold-evoked behaviors under the control of noxious cold-sensing neurons (nociceptors), but it is unknown how the nervous system might participate in cold tolerance. Herein, we describe cold-nociceptive behavior among 11 drosophilid species; we find that the predominant cold-evoked larval response is a head-to-tail contraction behavior, which is likely inherited from a common ancestor, but is unlikely to be protective.

Age-Related Retinal Changes in Wild-Type C57BL/6J Mice Between 2 and 32 Months.

Purpose: The purpose of this study was to extend our understanding of how aging affects normal retina function and morphology in wild-type C57BL/6J mice, by analyzing electrophysiological recordings and in vivo and post mortem anatomy.

Methods: Electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT), and confocal scanning laser ophthalmoscope (cSLO) in vivo images were obtained from mice between the ages of 2 and 32 months in four groups: group 1 (<0.5 years), group 2 (1.

Morphometric Analysis of Retinal Pigment Epithelial Cells From C57BL/6J Mice During Aging.

Purpose: To quantitatively evaluate the changes in orientation and morphometric features of mouse retinal pigment epithelial (RPE) cells in different regions of the eye during aging.

Methods: We segmented individual RPE cells from whole RPE flatmount images of C57BL/6J mice (postnatal days 30 to 720) using a machine-learning method and evaluated changes in morphometric features, including our newly developed metric combining alignment and shape of RPE cells during aging.

Results: Mainly, the anterior part of the RPE sheet grows during aging, while the posterior part remains constant.

Loss-of-function mutations in Lysyl-tRNA synthetase cause various leukoencephalopathy phenotypes.

Objective: To expand the clinical spectrum of lysyl-tRNA synthetase () gene-related diseases, which so far includes Charcot-Marie-Tooth disease, congenital visual impairment and microcephaly, and nonsyndromic hearing impairment.

Methods: Whole-exome sequencing was performed on index patients from 4 unrelated families with leukoencephalopathy. Candidate pathogenic variants and their cosegregation were confirmed by Sanger sequencing.

Comparison of histologic findings in age-related macular degeneration with RPE flatmount images.

Purpose: To visualize and analyze ex vivo flatmounted human RPE morphology from patients with age-related macular degeneration (AMD), and to compare the morphology with histologic findings. To establish whether the sub-RPE structures identified en face in RPE flatmount preparations are drusen with histopathological registration in serial sections. To detect characteristic patterns found en face in RPE with the same structures in histological cross sections from eyes from cadavers of patients with AMD.

Differential Exon Expression in a Large Family of Retinal Genes Is Regulated by a Single Trans Locus.

Transcription and RNA processing can generate many variant mRNAs (isoforms) from a given genomic locus. The more we learn about RNA processing the more we realize how complex it can be. Examining the expression profiles of individual exons, we observed that specific exons were differentially expressed across a large number of genes in mice.

Orbitofrontal Cortex Neurons Respond to Sound and Activate Primary Auditory Cortex Neurons.

Sensory environments change over a wide dynamic range and sensory processing can change rapidly to facilitate stable perception. While rapid changes may occur throughout the sensory processing pathway, cortical changes are believed to profoundly influence perception. Prior stimulation studies showed that orbitofrontal cortex (OFC) can modify receptive fields and sensory coding in A1, but the engagement of OFC during listening and the pathways mediating OFC influences on A1 are unknown.

IRBP deficiency permits precocious ocular development and myopia.

Purpose: Interphotoreceptor retinoid-binding protein (IRBP) is abundant in the subretinal space and binds retinoids and lipophilic molecules. The expression of IRBP begins precociously early in mouse eye development. IRBP-deficient (KO) mice show less cell death in the inner retinal layers of the retina before eyelid opening compared to wild-type C57BL/6J (WT) controls and eventually develop profound myopia.