Distinct retinal ganglion cell types in strictly subterranean, naturally microphthalmic mammals.

African mole-rats (Bathyergidae, Rodentia) are subterranean rodents that live in extensive dark underground tunnel systems and rarely emerge aboveground. They can discriminate between light and dark but show no overt visually driven behaviours except for light-avoidance responses. Their eyes and central visual system are strongly reduced but not degenerated.

No evidence for age-related alterations in the marmoset retina.

The physiological aging process of the retina is accompanied by various and sometimes extensive changes: Macular degeneration, retinopathies and glaucoma are the most common findings in the elderly and can potentially lead to irreversible visual disablements up to blindness. To study the aging process and to identify possible therapeutic targets to counteract these diseases, the use of appropriate animal models is mandatory. Besides the most commonly used rodent species, a non-human primate, the common marmoset () emerged as a promising animal model of human aging over the last years.

Eye-Transcriptome and Genome-Wide Sequencing for Scolecophidia: Implications for Inferring the Visual System of the Ancestral Snake.

Molecular genetic data have recently been incorporated in attempts to reconstruct the ecology of the ancestral snake, though this has been limited by a paucity of data for one of the two main extant snake taxa, the highly fossorial Scolecophidia. Here we present and analyze vision genes from the first eye-transcriptomic and genome-wide data for Scolecophidia, for Anilios bicolor, and A. bituberculatus, respectively.

Author Correction: Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Magnetoreception: activation of avian cryptochrome 1a in various light conditions.

The avian magnetic inclination compass is based on radical pair processes, with cryptochrome (Cry) assumed to form the crucial radical pairs; it requires short-wavelength light from UV to green. Under high-intensity narrow-band lights and when yellow light is added, the magnetic compass is disrupted: migratory birds no longer prefer their migratory direction, but show other orientation responses. The candidate receptor molecule Cry1a is located in the shortwavelength-sensitive SWS1 cone photoreceptors in the retina.

The rod signaling pathway in marsupial retinae.

The retinal rod pathway, featuring dedicated rod bipolar cells (RBCs) and AII amacrine cells, has been intensely studied in placental mammals. Here, we analyzed the rod pathway in a nocturnal marsupial, the South American opossum Monodelphis domestica to elucidate whether marsupials have a similar rod pathway. The retina was dominated by rods with densities of 338,000-413,000/mm².

Retinal photoreceptor and ganglion cell types and topographies in the red fox (Vulpes vulpes) and Arctic fox (Vulpes lagopus).

The red fox (Vulpes vulpes) is the carnivore with the widest distribution in the world. Not much is known about the visual system of these predominantly forest-dwelling animals. The closely related Arctic fox (Vulpes lagopus) lives in more open tundra habitats.

Biomonitoring of polychlorinated biphenyls in Bavaria/Germany-long-term observations and standardization.

In the 1980s, it was demonstrated that semi-volatile organic compounds (SVOCs) like polychlorinated biphenyls (PCBs) accumulate in plant leaves. Plants are at the base of the food chain, and therefore a starting point for transfer of PCBs to animals and related human exposure. For two decades, the Environment Agency of the German federal state of Bavaria (LfU) has been operating long-term monitoring stations to measure the impact of organic air pollutants.

The Retina of Asian and African Elephants: Comparison of Newborn and Adult.

Elephants are precocial mammals that are relatively mature as newborns and mobile shortly after birth. To determine whether the retina of newborn elephants is capable of supporting the mobility of elephant calves, we compared the retinal structures of 2 newborn elephants (1 African and 1 Asian) and 2 adult animals of both species by immunohistochemical and morphometric methods. For the first time, we present here a comprehensive qualitative and quantitative characterization of the cellular composition of the newborn and the adult retinas of 2 elephant species.

Diversity of photoreceptor arrangements in nocturnal, cathemeral and diurnal Malagasy lemurs.

The lemurs of Madagascar (Primates: Lemuriformes) are a monophyletic group that has lived in isolation from other primates for about 50 million years. Lemurs have diversified into species with diverse daily activity patterns and correspondingly different visual adaptations. We assessed the arrangements of retinal cone and rod photoreceptors in six nocturnal, three cathemeral and two diurnal lemur species and quantified different parameters in six of the species.

Thyroid Hormone Signaling in the Mouse Retina.

Thyroid hormone is a crucial regulator of gene expression in the developing and adult retina. Here we sought to map sites of thyroid hormone signaling at the cellular level using the transgenic FINDT3 reporter mouse model in which neurons express β-galactosidase (β-gal) under the control of a hybrid Gal4-TRα receptor when triiodothyronine (T3) and cofactors of thyroid receptor signaling are present. In the adult retina, nearly all neurons of the ganglion cell layer (GCL, ganglion cells and displaced amacrine cells) showed strong β-gal labeling.

Seasonally Changing Cryptochrome 1b Expression in the Retinal Ganglion Cells of a Migrating Passerine Bird.

Cryptochromes, blue-light absorbing proteins involved in the circadian clock, have been proposed to be the receptor molecules of the avian magnetic compass. In birds, several cryptochromes occur: Cryptochrome 2, Cryptochrome 4 and two splice products of Cryptochrome 1, Cry1a and Cry1b. With an antibody not distinguishing between the two splice products, Cryptochrome 1 had been detected in the retinal ganglion cells of garden warblers during migration.

Cryptochrome 1 in Retinal Cone Photoreceptors Suggests a Novel Functional Role in Mammals.

Cryptochromes are a ubiquitous group of blue-light absorbing flavoproteins that in the mammalian retina have an important role in the circadian clock. In birds, cryptochrome 1a (Cry1a), localized in the UV/violet-sensitive S1 cone photoreceptors, is proposed to be the retinal receptor molecule of the light-dependent magnetic compass. The retinal localization of mammalian Cry1, homologue to avian Cry1a, is unknown, and it is open whether mammalian Cry1 is also involved in magnetic field sensing.

Cone bipolar cells in the retina of the microbat Carollia perspicillata.

We studied the retinal cone bipolar cells of Carollia perspicillata, a microchiropteran bat of the phyllostomid family. Microchiroptera are strongly nocturnal, with small eyes and rod-dominated retinae. However, they also possess a significant cone population (2-4%) comprising two spectral types, which are hence the basis for daylight and color vision.

Magnetoreception in birds: I. Immunohistochemical studies concerning the cryptochrome cycle.

Cryptochrome 1a, located in the UV/violet-sensitive cones in the avian retina, is discussed as receptor molecule for the magnetic compass of birds. Our previous immunohistochemical studies of chicken retinae with an antiserum that labelled only activated cryptochrome 1a had shown activation of cryptochrome 1a under 373 nm UV, 424 nm blue, 502 nm turquoise and 565 nm green light. Green light, however, does not allow the first step of photoreduction of oxidized cryptochromes to the semiquinone.

DNA methylation reader MECP2: cell type- and differentiation stage-specific protein distribution.

Background: Methyl-CpG binding protein 2 (MECP2) is a protein that specifically binds methylated DNA, thus regulating transcription and chromatin organization. Mutations in the gene have been identified as the principal cause of Rett syndrome, a severe neurological disorder. Although the role of MECP2 has been extensively studied in nervous tissues, still very little is known about its function and cell type specific distribution in other tissues.

Expression and Evolution of Short Wavelength Sensitive Opsins in Colugos: A Nocturnal Lineage That Informs Debate on Primate Origins.

A nocturnal activity pattern is central to almost all hypotheses on the adaptive origins of primates. This enduring view has been challenged in recent years on the basis of variation in the opsin genes of nocturnal primates. A correspondence between the opsin genes and activity patterns of species in Euarchonta-the superordinal group that includes the orders Primates, Dermoptera (colugos), and Scandentia (treeshrews)-could prove instructive, yet the basic biology of the dermopteran visual system is practically unknown.

Retinal cone photoreceptors of the deer mouse Peromyscus maniculatus: development, topography, opsin expression and spectral tuning.

A quantitative analysis of photoreceptor properties was performed in the retina of the nocturnal deer mouse, Peromyscus maniculatus, using pigmented (wildtype) and albino animals. The aim was to establish whether the deer mouse is a more suitable model species than the house mouse for photoreceptor studies, and whether oculocutaneous albinism affects its photoreceptor properties. In retinal flatmounts, cone photoreceptors were identified by opsin immunostaining, and their numbers, spectral types, and distributions across the retina were determined.

Efficacy of a novel prewarming system in the prevention of perioperative hypothermia. A prospective, randomized, multicenter study.

Background: Perioperative hypothermia is a common complication during general anesthesia. Although rewarming of patients before surgery has been used as a preventive measure and some guidelines recommend it, the implementation of prewarming for every surgical patient is cumbersome. Therefore, we sought to determine the efficacy of two novel prewarming methods that could facilitate prewarming in daily practice.

Magnetoreception: activated cryptochrome 1a concurs with magnetic orientation in birds.

The radical pair model proposes that the avian magnetic compass is based on radical pair processes in the eye, with cryptochrome, a flavoprotein, suggested as receptor molecule. Cryptochrome 1a (Cry1a) is localized at the discs of the outer segments of the UV/violet cones of European robins and chickens. Here, we show the activation characteristics of a bird cryptochrome in vivo under natural conditions.

S cones: Evolution, retinal distribution, development, and spectral sensitivity.

S cones expressing the short wavelength-sensitive type 1 (SWS1) class of visual pigment generally form only a minority type of cone photoreceptor within the vertebrate duplex retina. Hence, their primary role is in color vision, not in high acuity vision. In mammals, S cones may be present as a constant fraction of the cones across the retina, may be restricted to certain regions of the retina or may form a gradient across the retina, and in some species, there is coexpression of SWS1 and the long wavelength-sensitive (LWS) class of pigment in many cones.

LBR and lamin A/C sequentially tether peripheral heterochromatin and inversely regulate differentiation.

Eukaryotic cells have a layer of heterochromatin at the nuclear periphery. To investigate mechanisms regulating chromatin distribution, we analyzed heterochromatin organization in different tissues and species, including mice with mutations in the lamin B receptor (Lbr) and lamin A (Lmna) genes that encode nuclear envelope (NE) proteins. We identified LBR- and lamin-A/C-dependent mechanisms tethering heterochromatin to the NE.

The rod pathway of the microbat retina has bistratified rod bipolar cells and tristratified AII amacrine cells.

We studied the retinal rod pathway of Carollia perspicillata and Glossophaga soricina, frugivorous microbats of the phyllostomid family. Protein kinase Cα (PKCα) immunolabeling revealed abundant rod bipolar cells (RBCs) with axon terminals in the innermost sublamina of the inner plexiform layer (IPL), which is typical for mammals. Extraordinarily, the RBC axons showed additional synaptic contacts in a second sublamina further out in the IPL.

Avian ultraviolet/violet cones as magnetoreceptors: The problem of separating visual and magnetic information.

In a recent paper, we described the localization of cryptochrome 1a in the retina of domestic chickens, Gallus gallus, and European robins, Erithacus rubecula: Cryptochrome 1a was found exclusively along the membranes of the disks in the outer segments of the ultraviolet/violet single cones. Cryptochrome has been suggested to act as receptor molecule for the avian magnetic compass, which would mean that the UV/V cones have a double function: they mediate vision in the short-wavelength range and, at the same time, magnetic directional information. This has important implications and raises a number of questions, in particular, how the two types of input are separated.

Avian ultraviolet/violet cones identified as probable magnetoreceptors.

Background: The Radical-Pair-Model postulates that the reception of magnetic compass directions in birds is based on spin-chemical reactions in specialized photopigments in the eye, with cryptochromes discussed as candidate molecules. But so far, the exact subcellular characterization of these molecules in the retina remained unknown.

Methodology/principal Findings: We here describe the localization of cryptochrome 1a (Cry1a) in the retina of European robins, Erithacus rubecula, and domestic chickens, Gallus gallus, two species that have been shown to use the magnetic field for compass orientation.