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Tashiro JH, Ventura DF, Hauzman E. Morphological Plasticity of the Retina of Viperidae Snakes Is Associated With Ontogenetic Changes in Ecology and Behavior. Front Neuroanat 2022; 15:770804. [PMID: 35153683 PMCID: PMC8825375 DOI: 10.3389/fnana.2021.770804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
Snakes of the Viperidae family have retinas adapted to low light conditions, with high packaging of rod-photoreceptors containing the rhodopsin photopigment (RH1), and three types of cone-photoreceptors, large single and double cones with long-wavelength sensitive opsins (LWS), and small single cones with short-wavelength sensitive opsins (SWS1). In this study, we compared the density and distribution of photoreceptors and ganglion cell layer (GCL) cells in whole-mounted retinas of two viperid snakes, the lancehead Bothrops jararaca and the rattlesnake Crotalus durissus, and we estimated the upper limits of spatial resolving power based on anatomical data. The ground-dwelling C. durissus inhabits savannah-like habitats and actively searches for places to hide before using the sit-and-wait hunting strategy to ambush rodents. B. jararaca inhabits forested areas and has ontogenetic changes in ecology and behavior. Adults are terrestrial and use similar hunting strategies to those used by rattlesnakes to prey on rodents. Juveniles are semi-arboreal and use the sit-and-wait strategy and caudal luring to attract ectothermic prey. Our analyses showed that neuronal densities were similar for the two species, but their patterns of distribution were different between and within species. In adults and juveniles of C. durissus, cones were distributed in poorly defined visual streaks and rods were concentrated in the dorsal retina, indicating higher sensitivity in the lower visual field. In adults of B. jararaca, both cones and rods were distributed in poorly defined visual streaks, while in juveniles, rods were concentrated in the dorsal retina and cones in the ventral retina, enhancing sensitivity in the lower visual field and visual acuity in the upper field. The GCL cells had peak densities in the temporal retina of C. durissus and adults of B. jararaca, indicating higher acuity in the frontal field. In juveniles of B. jararaca, the peak density of GCL cells in the ventral retina indicates better acuity in the upper field. The estimated visual acuity varied from 2.3 to 2.8 cycles per degree. Our results showed interspecific differences and suggest ontogenetic plasticity of the retinal architecture associated with changes in the niche occupied by viperid snakes, and highlight the importance of the retinal topography for visual ecology and behavior of snakes.
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Increased burrow oxygen levels trigger defensive burrow-sealing behavior by plateau zokors. Sci Rep 2021; 11:19088. [PMID: 34580363 PMCID: PMC8476587 DOI: 10.1038/s41598-021-98551-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 09/09/2021] [Indexed: 11/29/2022] Open
Abstract
Defensive behaviors are a response to immediate and potential threats in the environment, including abiotic and biotic threats. Subterranean rodents exhibit morphological and physiological adaptions for life underground, and they will seal with mounds and additional plugs when their burrow opened. However, little is known about the factors driving this defensive behavior. In this study, we selected a subterranean rodent, plateau zokor (Myospalax fontanieri), as a species to investigate (both in the laboratory and in the field) the possible factors responsible for burrow-sealing behavior. Our results showed that: (1) In the laboratory, the burrow-sealing frequency of plateau zokor in response to five factors were as follows: oxygen (52.63%) > light (34.58%) > temperature (20.24%) > gas flow (6.48%) > sound/control (0%). Except for light, the burrow-sealing frequency in response to other factors was significantly lower than that in response to oxygen (P < 0.05). (2) Burrow-sealing behavior in response to each treatment did not differ significantly between males and females in the laboratory experiment. (3) In the field, during the animal’s active periods in both the cold and warm season, the burrow-sealing frequency under the oxygen treatment was higher than that under the light and temperature treatments. Plateau zokors were found not to be sensitive to these treatments during their inactive periods during both the cold and warm season. (4) The latency to reseal the burrow showed no obvious differences between each treatment both in the laboratory and in the field. In conclusion, the main factor that influences the burrow-sealing behavior of plateau zokors is the variation in oxygen concentration, and this defensive behavior is related to their activity rhythm.
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Abstract
A retina completely devoid of topographic variations would be homogenous, encoding any given feature uniformly across the visual field. In a naive view, such homogeneity would appear advantageous. However, it is now clear that retinal topographic variations exist across mammalian species in a variety of forms and patterns. We briefly review some of the more established topographic variations in retinas of different mammalian species and focus on the recent discovery that cells belonging to a single neuronal subtype may exhibit distinct topographic variations in distribution, morphology, and even function. We concentrate on the mouse retina-originally viewed as homogenous-in which genetic labeling of distinct neuronal subtypes and other advanced techniques have revealed unexpected anatomical and physiological topographic variations. Notably, different subtypes reveal different patterns of nonuniformity, which may even be opposite or orthogonal to one another. These topographic variations in the encoding of visual space should be considered when studying visual processing in the retina and beyond.
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Affiliation(s)
- Alina Sophie Heukamp
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 7610001, Israel; , ,
| | - Rebekah Anne Warwick
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 7610001, Israel; , ,
| | - Michal Rivlin-Etzion
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 7610001, Israel; , ,
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4
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Abstract
Abstract
Knowledge of a species’ visual system has far reaching implications that affect our understanding of a species’ ecology and evolutionary history. As a model taxon, the heteromyid rodent genus Dipodomys has been valuable in elucidating patterns and mechanisms in biomechanics, ecology, adaptive physiology, biogeography, and more. Although studied extensively, the visual system of Dipodomys has not been described beyond anecdotal mention of their large eyes. Here, the transmittance parameters of the cornea and lens of Ord’s kangaroo rat (Dipodomys ordii) were analyzed and photoreceptor proteins (opsins) expressed in the retina were identified with immunohistochemical (IHC) labeling. Retina maps were constructed to illustrate the relative densities of photoreceptor cells expressing short wavelength (SWS1) opsins, middle/long wavelength (MW/LW) opsins, and rhodopsin (RH1). The retina of D. ordii has variable densities of SWS1 opsin with the highest density being ventral to the optic nerve, high density of MW/LW opsin, and uniform distribution and high density of RH1 across the retina. Our results suggest that D. ordii has a UV-sensitive visual system. Composition and densities of MW/LW- and SWS1-expressing cells resemble that of a crepuscular/diurnal species thereby supporting previous authors who have reported such activity patterns. Uniform retinal distribution of RH1 indicates visual acuity at night, also confirming the paradigm of D. ordii as primarily a nocturnal species and suggesting visual acuity at all times of the day in the species. These results demonstrate not only that the species is capable of UV vision and has a retina characteristic of a diurnal mammal, but that many previously unknown photic niche selective advantages likely have shaped the evolution and ecology of this model taxon.
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Affiliation(s)
- Brandon McDonald
- Cameron University, Department of Agriculture, Biology, and Health Sciences, Lawton, OK, USA
| | - Bryce Geiger
- Cameron University, Department of Agriculture, Biology, and Health Sciences, Lawton, OK, USA
| | - Sarah Vrla
- Cameron University, Department of Agriculture, Biology, and Health Sciences, Lawton, OK, USA
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5
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Emerling CA. Regressed but Not Gone: Patterns of Vision Gene Loss and Retention in Subterranean Mammals. Integr Comp Biol 2019; 58:441-451. [PMID: 29697812 DOI: 10.1093/icb/icy004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Regressive evolution involves the degradation of formerly useful traits as organisms invade novel ecological niches. In animals, committing to a strict subterranean habit can lead to regression of the eyes, likely due to a limited exposure to light. Several lineages of subterranean mammals show evidence of such degeneration, which can include decreased organization of the retina, malformation of the lens, and subcutaneous positioning of the eye. Advances in DNA sequencing have revealed that this regression co-occurs with a degradation of genomic loci encoding visual functions, including protein-coding genes. Other dim light-adapted vertebrates with normal ocular anatomy, such as nocturnal and aquatic species, also demonstrate evidence of visual gene loss, but the absence of comparative studies has led to the untested assumption that subterranean mammals are special in the degree of this genomic regression. Additionally, previous studies have shown that not all vision genes have been lost in subterranean mammals, but it is unclear whether they are under relaxed selection and will ultimately be lost, are maintained due to pleiotropy or if natural selection is favoring the retention of the eye and certain critical underlying loci. Here I report that vision gene loss in subterranean mammals tends to be more extensive in quantity and differs in distribution from other dim light-adapted mammals, although some committed subterranean mammals demonstrate significant overlap with nocturnal microphthalmic species. In addition, blind subterranean mammals retain functional orthologs of non-pleiotropic visual genes that are evolving at rates consistent with purifying selection. Together, these results suggest that although living underground tends to lead to major losses of visual functions, natural selection is maintaining genes that support the eye, perhaps as an organ for circadian and/or circannual entrainment.
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Affiliation(s)
- Christopher A Emerling
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA 94720, USA
- Institut des Sciences de l'Evolution de Montpellier (ISEM), Université de Montpellier, CNRS, IRD, EPHE, 34090 Montpellier, France
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6
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Evolution of circadian genes PER and CRY in subterranean rodents. Int J Biol Macromol 2018; 118:1400-1405. [DOI: 10.1016/j.ijbiomac.2018.06.133] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 06/05/2018] [Accepted: 06/26/2018] [Indexed: 01/11/2023]
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7
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The topography of rods, cones and intrinsically photosensitive retinal ganglion cells in the retinas of a nocturnal (Micaelamys namaquensis) and a diurnal (Rhabdomys pumilio) rodent. PLoS One 2018; 13:e0202106. [PMID: 30092025 PMCID: PMC6084985 DOI: 10.1371/journal.pone.0202106] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Accepted: 07/28/2018] [Indexed: 11/19/2022] Open
Abstract
We used immunocytochemistry to determine the presence and topographical density distributions of rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs) in the four-striped field mouse (Rhabdomys pumilio) and the Namaqua rock mouse (Micaelamys namaquensis). Both species possessed duplex retinas that were rod dominated. In R. pumilio, the density of both cones and rods were high (cone to rod ratio: 1:1.23) and reflected the species' fundamentally diurnal, but largely crepuscular lifestyle. Similarly, the ratio of cones to rods in M. namaquensis (1:12.4) reflected its nocturnal lifestyle. Similar rod density peaks were observed (R. pumilio: ~84467/mm2; M. namaquensis: ~81088/mm2), but a density gradient yielded higher values in the central (~56618/mm2) rather than in the peripheral retinal region (~32689/mm2) in R. pumilio. Two separate cone types (S-cones and M/L-cones) were identified implying dichromatic color vision in the study species. In M. namaquensis, both cone populations showed a centro-peripheral density gradient and a consistent S- to M/L-cone ratio (~1:7.8). In R. pumilio, S cones showed a centro-peripheral gradient (S- to M/L-cone ratio; central: 1:7.8; peripheral: 1:6.8) which appeared to form a visual streak, and a specialized area of M/L-cones (S- to M/L-cone ratio: 1:15) was observed inferior to the optic nerve. The number of photoreceptors per linear degree of visual angle, estimated from peak photoreceptor densities and eye size, were four cones and 15 rods per degree in M. namaquensis and 11 cones and 12 rods per degree in R. pumilio. Thus, in nocturnal M. namaquensis rods provide much finer image sampling than cones, whereas in diurnal/crepuscular R. pumilio both photoreceptor types provide fine image sampling. IpRGCs were comparably sparse in R. pumilio (total = 1012) and M. namaquensis (total = 862), but were homogeneously distributed in M. namaquensis and densest in the dorso-nasal quadrant in R. pumilio. The adaptive significance of the latter needs further investigation.
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Karl A, Agte S, Zayas-Santiago A, Makarov FN, Rivera Y, Benedikt J, Francke M, Reichenbach A, Skatchkov SN, Bringmann A. Retinal adaptation to dim light vision in spectacled caimans (Caiman crocodilus fuscus): Analysis of retinal ultrastructure. Exp Eye Res 2018; 173:160-178. [PMID: 29753728 PMCID: PMC9930524 DOI: 10.1016/j.exer.2018.05.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 05/09/2018] [Accepted: 05/09/2018] [Indexed: 11/19/2022]
Abstract
It has been shown that mammalian retinal glial (Müller) cells act as living optical fibers that guide the light through the retinal tissue to the photoreceptor cells (Agte et al., 2011; Franze et al., 2007). However, for nonmammalian species it is unclear whether Müller cells also improve the transretinal light transmission. Furthermore, for nonmammalian species there is a lack of ultrastructural data of the retinal cells, which, in general, delivers fundamental information of the retinal function, i.e. the vision of the species. A detailed study of the cellular ultrastructure provides a basic approach of the research. Thus, the aim of the present study was to investigate the retina of the spectacled caimans at electron and light microscopical levels to describe the structural features. For electron microscopy, we used a superfast microwave fixation procedure in order to achieve more precise ultrastructural information than common fixation techniques. As result, our detailed ultrastructural study of all retinal parts shows structural features which strongly indicate that the caiman retina is adapted to dim light and night vision. Various structural characteristics of Müller cells suppose that the Müller cell may increase the light intensity along the path of light through the neuroretina and, thus, increase the sensitivity of the scotopic vision of spectacled caimans. Müller cells traverse the whole thickness of the neuroretina and thus may guide the light from the inner retinal surface to the photoreceptor cell perikarya and the Müller cell microvilli between the photoreceptor segments. Thick Müller cell trunks/processes traverse the layers which contain light-scattering structures, i.e., nerve fibers and synapses. Large Müller cell somata run through the inner nuclear layer and contain flattened, elongated Müller cell nuclei which are arranged along the light path and, thus, may reduce the loss of the light intensity along the retinal light path. The oblique arrangement of many Müller cell trunks/processes in the inner plexiform layer and the large Müller cell somata in the inner nuclear layer may suggest that light guidance through Müller cells increases the visual sensitivity. Furthermore, an adaptation of the caiman retina to low light levels is strongly supported by detailed ultrastructural data of other retinal parts, e.g. by (i) the presence of a guanine-based retinal tapetum, (ii) the rod dominance of the retina, (iii) the presence of photoreceptor cell nuclei, which penetrate the outer limiting membrane, (iv) the relatively low densities of photoreceptor and neuronal cells which is compensated by (v) the presence of rods with long and thick outer segments, that may increase the probability of photon absorption. According to a cell number analysis, the central and temporal areas of the dorsal tapetal retina, which supports downward prey detection in darker water, are the sites of the highest diurnal contrast/color vision, i.e. cone vision and of the highest retinal light sensitivity, i.e. rod vision.
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Affiliation(s)
- Anett Karl
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany; Carl Ludwig Institute for Physiology, University of Leipzig, Leipzig, Germany.
| | - Silke Agte
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Astrid Zayas-Santiago
- Department of Pathology and Laboratory Medicine, Universidad Central Del Caribe, Bayamón, Puerto Rico, USA
| | - Felix N Makarov
- Laboratory of Neuromorphology, Pavlov Institute of Physiology, Russian Academy of Sciences, Saint Petersburg, Russia
| | - Yomarie Rivera
- Department of Physiology, Universidad Central Del Caribe, Bayamón, Puerto Rico, USA
| | - Jan Benedikt
- Department of Physiology, Universidad Central Del Caribe, Bayamón, Puerto Rico, USA
| | - Mike Francke
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany; Saxonian Incubator for Clinical Translation (SIKT), University of Leipzig, Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute for Brain Research, University of Leipzig, Leipzig, Germany
| | - Serguei N Skatchkov
- Department of Biochemistry, Universidad Central Del Caribe, Bayamón, Puerto Rico, USA; Department of Physiology, Universidad Central Del Caribe, Bayamón, Puerto Rico, USA
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
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Sun H, Zhang Y, Shi Y, Li Y, Li W, Wang Z. Evolution of the CLOCK and BMAL1 genes in a subterranean rodent species (Lasiopodomys mandarinus). Int J Biol Macromol 2018; 109:932-940. [DOI: 10.1016/j.ijbiomac.2017.11.076] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/10/2017] [Accepted: 11/12/2017] [Indexed: 12/01/2022]
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10
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Kuhrt H, Bringmann A, Härtig W, Wibbelt G, Peichl L, Reichenbach A. The Retina of Asian and African Elephants: Comparison of Newborn and Adult. BRAIN, BEHAVIOR AND EVOLUTION 2017; 89:84-103. [PMID: 28437785 DOI: 10.1159/000464097] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 02/14/2017] [Indexed: 11/19/2022]
Abstract
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. We found that the retina of elephants is relatively mature at birth. All retinal layers were well discernible, and various retinal cell types were detected in the newborns, including Müller glial cells (expressing glutamine synthetase and cellular retinal binding protein; CRALBP), cone photoreceptors (expressing S-opsin or M/L-opsin), protein kinase Cα-expressing bipolar cells, tyrosine hydroxylase-, choline acetyltransferase (ChAT)-, calbindin-, and calretinin-expressing amacrine cells, and calbindin-expressing horizontal cells. The retina of newborn elephants contains discrete horizontal cells which coexpress ChAT, calbindin, and calretinin. While the overall structure of the retina is very similar between newborn and adult elephants, various parameters change after birth. The postnatal thickening of the retinal ganglion cell axons and the increase in ganglion cell soma size are explained by the increase in body size after birth, and the decreases in the densities of neuronal and glial cells are explained by the postnatal expansion of the retinal surface area. The expression of glutamine synthetase and CRALBP in the Müller cells of newborn elephants suggests that the cells are already capable of supporting the activities of photoreceptors and neurons. As a peculiarity, the elephant retina contains both normally located and displaced giant ganglion cells, with single cells reaching a diameter of more than 50 µm in adults and therefore being almost in the range of giant retinal ganglion cells found in aquatic mammals. Some of these ganglion cells are displaced into the inner nuclear layer, a unique feature of terrestrial mammals. For the first time, we describe here the occurrence of many bistratified rod bipolar cells in the elephant retina. These bistratified bipolar cells may improve nocturnal contrast perception in elephants given their arrhythmic lifestyle.
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Affiliation(s)
- Heidrun Kuhrt
- Paul Flechsig Institute of Brain Research, University of Leipzig Medical Faculty, Leipzig, Germany
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11
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Peichl L, Kaiser A, Rakotondraparany F, Dubielzig RR, Goodman SM, Kappeler PM. Diversity of photoreceptor arrangements in nocturnal, cathemeral and diurnal Malagasy lemurs. J Comp Neurol 2017; 527:13-37. [DOI: 10.1002/cne.24167] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 12/29/2016] [Accepted: 12/30/2016] [Indexed: 12/23/2022]
Affiliation(s)
- Leo Peichl
- Max Planck Institute for Brain Research; Max-von-Laue-Straße 4, 60438 Frankfurt am Main Germany
- Ernst Strüngmann Institute for Neuroscience; Deutschordenstraße 46, 60528 Frankfurt am Main Germany
- Institute of Cellular and Molecular Anatomy, Dr. Senckenbergische Anatomie, Goethe University Frankfurt; Theodor-Stern-Kai 7, 60590 Frankfurt am Main Germany
| | - Alexander Kaiser
- Department Biology II; Ludwig-Maximilians University Munich; Großhaderner Straße 2-4, 82152 Martinsried-Planegg Germany
- Institute of Zoology; University of Veterinary Medicine Hannover; Bünteweg 17, 30559 Hannover Germany
| | - Felix Rakotondraparany
- Département de Zoologie et Biodiversité Animale; Université d’Antananarivo; BP 906, Antananarivo 101 Madagascar
| | - Richard R. Dubielzig
- School of Veterinary Medicine; University of Wisconsin; 2015 Linden Drive Madison Wisconsin 53706
| | - Steven M. Goodman
- The Field Museum of Natural History; 1400 South Lake Shore Drive, Chicago Illinois 60605
- Association Vahatra; BP 3972, Antananarivo 101 Madagascar
| | - Peter M. Kappeler
- Behavioral Ecology and Sociobiology Unit, German Primate Center; Kellnerweg 4, 37077 Göttingen Germany
- Johann-Friedrich-Blumenbach-Institute of Zoology and Anthropology; University Göttingen; Kellnerweg 6, 37077 Göttingen Germany
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Selective binocular vision loss in two subterranean caviomorph rodents: Spalacopus cyanus and Ctenomys talarum. Sci Rep 2017; 7:41704. [PMID: 28150809 PMCID: PMC5288697 DOI: 10.1038/srep41704] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 12/19/2016] [Indexed: 11/09/2022] Open
Abstract
To what extent can the mammalian visual system be shaped by visual behavior? Here we analyze the shape of the visual fields, the densities and distribution of cells in the retinal ganglion-cell layer and the organization of the visual projections in two species of facultative non-strictly subterranean rodents, Spalacopus cyanus and Ctenomys talarum, aiming to compare these traits with those of phylogenetically closely related species possessing contrasting diurnal/nocturnal visual habits. S. cyanus shows a definite zone of frontal binocular overlap and a corresponding area centralis, but a highly reduced amount of ipsilateral retinal projections. The situation in C. talarum is more extreme as it lacks of a fronto-ventral area of binocular superposition, has no recognizable area centralis and shows no ipsilateral retinal projections except to the suprachiasmatic nucleus. In both species, the extension of the monocular visual field and of the dorsal region of binocular overlap as well as the whole set of contralateral visual projections, appear well-developed. We conclude that these subterranean rodents exhibit, paradoxically, diurnal instead of nocturnal visual specializations, but at the same time suffer a specific regression of the anatomical substrate for stereopsis. We discuss these findings in light of the visual ecology of subterranean lifestyles.
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Kott O, Němec P, Fremlová A, Mazoch V, Šumbera R. Behavioural Tests Reveal Severe Visual Deficits in the Strictly Subterranean African Mole-Rats (Bathyergidae) but Efficient Vision in the Fossorial Rodent Coruro (Spalacopus cyanus, Octodontidae). Ethology 2016. [DOI: 10.1111/eth.12515] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ondřej Kott
- Department of Zoology; Faculty of Science; University of South Bohemia; České Budějovice Czech Republic
| | - Pavel Němec
- Department of Zoology; Faculty of Science; Charles University in Prague; Prague Czech Republic
| | - Aneta Fremlová
- Department of Zoology; Faculty of Science; University of South Bohemia; České Budějovice Czech Republic
| | - Vladimír Mazoch
- Department of Zoology; Faculty of Science; University of South Bohemia; České Budějovice Czech Republic
| | - Radim Šumbera
- Department of Zoology; Faculty of Science; University of South Bohemia; České Budějovice Czech Republic
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Melin AD, Wells K, Moritz GL, Kistler L, Orkin JD, Timm RM, Bernard H, Lakim MB, Perry GH, Kawamura S, Dominy NJ. Euarchontan Opsin Variation Brings New Focus to Primate Origins. Mol Biol Evol 2016; 33:1029-41. [PMID: 26739880 PMCID: PMC4776711 DOI: 10.1093/molbev/msv346] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Debate on the adaptive origins of primates has long focused on the functional ecology of the primate visual system. For example, it is hypothesized that variable expression of short- (SWS1) and middle-to-long-wavelength sensitive (M/LWS) opsins, which confer color vision, can be used to infer ancestral activity patterns and therefore selective ecological pressures. A problem with this approach is that opsin gene variation is incompletely known in the grandorder Euarchonta, that is, the orders Scandentia (treeshrews), Dermoptera (colugos), and Primates. The ancestral state of primate color vision is therefore uncertain. Here, we report on the genes (OPN1SW and OPN1LW) that encode SWS1 and M/LWS opsins in seven species of treeshrew, including the sole nocturnal scandentian Ptilocercus lowii. In addition, we examined the opsin genes of the Central American woolly opossum (Caluromys derbianus), an enduring ecological analogue in the debate on primate origins. Our results indicate: 1) retention of ultraviolet (UV) visual sensitivity in C. derbianus and a shift from UV to blue spectral sensitivities at the base of Euarchonta; 2) ancient pseudogenization of OPN1SW in the ancestors of P. lowii, but a signature of purifying selection in those of C. derbianus; and, 3) the absence of OPN1LW polymorphism among diurnal treeshrews. These findings suggest functional variation in the color vision of nocturnal mammals and a distinctive visual ecology of early primates, perhaps one that demanded greater spatial resolution under light levels that could support cone-mediated color discrimination.
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Affiliation(s)
- Amanda D Melin
- Department of Anthropology, Dartmouth College, Hanover, NH Department of Anthropology and Archaeology, and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB
| | - Konstans Wells
- Environmental Futures Research Institute, Griffith University, Brisbane, QLD, Australia
| | - Gillian L Moritz
- Department of Biological Sciences, Class of 1978 Life Sciences Center, Dartmouth College, Hanover, NH Department of Evolutionary Anthropology, Duke University
| | - Logan Kistler
- Departments of Anthropology and Biology, Pennsylvania State University School of Life Sciences, Gibbet Hill Campus, University of Warwick, Coventry, United Kingdom
| | - Joseph D Orkin
- Department of Anthropology and Archaeology, and Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB Department of Anthropology, Washington University in St. Louis
| | - Robert M Timm
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence
| | - Henry Bernard
- Institute for Tropical Biology and Conservation, Universiti Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
| | - Maklarin B Lakim
- Sabah Parks, Lot 45 & 46 KK Times Square Coastal Highway, Kota Kinabalu, Sabah, Malaysia
| | - George H Perry
- Departments of Anthropology and Biology, Pennsylvania State University
| | - Shoji Kawamura
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Japan
| | - Nathaniel J Dominy
- Department of Anthropology, Dartmouth College, Hanover, NH Department of Biological Sciences, Class of 1978 Life Sciences Center, Dartmouth College, Hanover, NH
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Du K, Yang L, He S. Phylogenomic analyses reveal a molecular signature linked to subterranean adaptation in rodents. BMC Evol Biol 2015; 15:287. [PMID: 26683336 PMCID: PMC4683706 DOI: 10.1186/s12862-015-0564-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 12/08/2015] [Indexed: 11/15/2022] Open
Abstract
Background Genome-wide signatures of convergent evolution are widely expected but rarely revealed in animals. Subterranean rodent genome and transcriptome data produced by next-generation sequencing facilitate the use of phylogenetic methods to infer non-synonymous and synonymous substitution rates within coding regions, which can reveal changes at the molecular level that are correlated with the dramatic shift from a terrestrial to subterranean habitat. Results Our study used previously sequenced genome or transcriptome data of two subterranean rodents, the blind mole rat and naked mole rat, and their terrestrial relatives, the mouse and guinea pig, to investigate the genetic basis of rodent subterranean adaptation. An analysis of 4996 orthologous genes revealed that the substitution pace of coding sequences was significantly slower in the blind mole rat than in the mouse, and slower in the naked mole rat than in the guinea pig. The dN/dS ratio was significantly higher in the blind mole rat than in the mouse and in the naked mole rat than in the guinea pig. These patterns are most likely related to the longer generation time and lower effective population size of subterranean rodents caused by subterranean ecological constraints. We also identified some genes and gene ontology (GO) categories that might be candidates for adaptation to subterranean life. Conclusions Our study reveals a case of subterranean convergent evolution in rodents that is correlated with change in the pace and mode of molecular evolution observed at the genome scale. We believe that this genomic signature could have also evolved in other cases of subterranean convergence. Additionally, the genes that displayed the most radical changes in their patterns of evolution and their associated GO categories provide a strong basis for further comparative and functional studies, and potentially reveal molecular signatures of adaptation to subterranean life. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0564-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kang Du
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Liandong Yang
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China. .,University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Shunping He
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
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16
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Emerling CA, Huynh HT, Nguyen MA, Meredith RW, Springer MS. Spectral shifts of mammalian ultraviolet-sensitive pigments (short wavelength-sensitive opsin 1) are associated with eye length and photic niche evolution. Proc Biol Sci 2015; 282:20151817. [PMID: 26582021 PMCID: PMC4685808 DOI: 10.1098/rspb.2015.1817] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 10/09/2015] [Indexed: 11/12/2022] Open
Abstract
Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet- and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage.
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Affiliation(s)
- Christopher A Emerling
- Department of Biology, University of California Riverside, Riverside, CA, USA Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Hieu T Huynh
- Department of Biology, University of California Riverside, Riverside, CA, USA School of Pharmacy, Loma Linda University, Loma Linda, CA, USA
| | - Minh A Nguyen
- Department of Biology, University of California Riverside, Riverside, CA, USA School of Pharmacy, Loma Linda University, Loma Linda, CA, USA
| | - Robert W Meredith
- Department of Biology, University of California Riverside, Riverside, CA, USA Department of Biology and Molecular Biology, Montclair State University, Montclair, NJ, USA
| | - Mark S Springer
- Department of Biology, University of California Riverside, Riverside, CA, USA
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Szabadfi K, Estrada C, Fernandez-Villalba E, Tarragon E, Setalo G, Izura V, Reglodi D, Tamas A, Gabriel R, Herrero MT. Retinal aging in the diurnal Chilean rodent (Octodon degus): histological, ultrastructural and neurochemical alterations of the vertical information processing pathway. Front Cell Neurosci 2015; 9:126. [PMID: 25954153 PMCID: PMC4405622 DOI: 10.3389/fncel.2015.00126] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 03/17/2015] [Indexed: 12/25/2022] Open
Abstract
The retina is sensitive to age-dependent degeneration. To find suitable animal models to understand and map this process has particular importance. The degu (Octodon degus) is a diurnal rodent with dichromatic color vision. Its retinal structure is similar to that in humans in many respects, therefore, it is well suited to study retinal aging. Histological, cell type-specific and ultrastructural alterations were examined in 6-, 12- and 36-months old degus. The characteristic layers of the retina were present at all ages, but slightly loosened tissue structure could be observed in 36-month-old animals both at light and electron microscopic levels. Elevated Glial fibrillary acidic protein (GFAP) expression was observed in Müller glial cells in aging retinas. The number of rod bipolar cells and the ganglion cells was reduced in the aging specimens, while that of cone bipolar cells remained unchanged. Other age-related differences were detected at ultrastructural level: alteration of the retinal pigment epithelium and degenerated photoreceptor cells were evident. Ribbon synapses were sparse and often differed in morphology from those in the young animals. These results support our hypothesis that (i) the rod pathway seems to be more sensitive than the cone pathway to age-related cell loss; (ii) structural changes in the basement membrane of pigment epithelial cells can be one of the early signs of degenerative processes; (iii) the loss of synaptic proteins especially from those of the ribbon synapses are characteristic; and (iv) the degu retina may be a suitable model for studying retinal aging.
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Affiliation(s)
- Krisztina Szabadfi
- Department of Experimental Zoology and Neurobiology, University of Pecs Pecs, Hungary ; Janos Szentagothai Research Center Pecs, Hungary
| | - Cristina Estrada
- Clinical and Experimental Neuroscience (NiCE), CIBERNED and Institute of Bio-Health Research of Murcia (IMIB), School of Medicine, Campus Mare Nostrum, University of Murcia Murcia, Spain
| | - Emiliano Fernandez-Villalba
- Clinical and Experimental Neuroscience (NiCE), CIBERNED and Institute of Bio-Health Research of Murcia (IMIB), School of Medicine, Campus Mare Nostrum, University of Murcia Murcia, Spain
| | - Ernesto Tarragon
- Clinical and Experimental Neuroscience (NiCE), CIBERNED and Institute of Bio-Health Research of Murcia (IMIB), School of Medicine, Campus Mare Nostrum, University of Murcia Murcia, Spain
| | - Gyorgy Setalo
- Department of Medical Biology, University of Pecs Pecs, Hungary
| | - Virginia Izura
- Clinical and Experimental Neuroscience (NiCE), CIBERNED and Institute of Bio-Health Research of Murcia (IMIB), School of Medicine, Campus Mare Nostrum, University of Murcia Murcia, Spain
| | - Dora Reglodi
- Department of Anatomy, MTA-PTE "Lendulet" PACAP Research Team, University of Pecs Pecs, Hungary
| | - Andrea Tamas
- Department of Anatomy, MTA-PTE "Lendulet" PACAP Research Team, University of Pecs Pecs, Hungary
| | - Robert Gabriel
- Department of Experimental Zoology and Neurobiology, University of Pecs Pecs, Hungary ; Janos Szentagothai Research Center Pecs, Hungary
| | - Maria Trinidad Herrero
- Clinical and Experimental Neuroscience (NiCE), CIBERNED and Institute of Bio-Health Research of Murcia (IMIB), School of Medicine, Campus Mare Nostrum, University of Murcia Murcia, Spain
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18
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Wu J, Xiang H, Qi Y, Yang D, Wang X, Sun H, Wang F, Liu B. Adaptive evolution of the STRA6 genes in mammalian. PLoS One 2014; 9:e108388. [PMID: 25251323 PMCID: PMC4177561 DOI: 10.1371/journal.pone.0108388] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 08/20/2014] [Indexed: 11/19/2022] Open
Abstract
Stimulated by retinoic acid 6 (STRA6) is the receptor for retinol binding protein and is relevant for the transport of retinol to specific sites such as the eye. The adaptive evolution mechanism that vertebrates have occupied nearly every habitat available on earth and adopted various lifestyles associated with different light conditions and visual challenges, as well as their role in development and adaptation is thus far unknown. In this work, we have investigated different aspects of vertebrate STRA6 evolution and used molecular evolutionary analyses to detect evidence of vertebrate adaptation to the lightless habitat. Free-ratio model revealed significant rate shifts immediately after the species divergence. The amino acid sites detected to be under positive selection are within the extracellular loops of STRA6 protein. Branch-site model A test revealed that STRA6 has undergone positive selection in the different phyla of mammalian except for the branch of rodent. The results suggest that interactions between different light environments and host may be driving adaptive change in STRA6 by competition between species. In support of this, we found that altered functional constraints may take place at some amino acid residues after speciation. We suggest that STRA6 has undergone adaptive evolution in different branch of vertebrate relation to habitat environment.
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Affiliation(s)
- Jianghong Wu
- Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot, China
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
- Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
- * E-mail: (JHW); (HX)
| | - Hui Xiang
- Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
- * E-mail: (JHW); (HX)
| | - Yunxia Qi
- Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot, China
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
| | - Ding Yang
- Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot, China
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
| | - Xiaojuan Wang
- Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot, China
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
| | - Hailian Sun
- Inner Mongolia Prataculture Research Center, Chinese Academy of Science, Hohhot, China
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
| | - Feng Wang
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
| | - Bin Liu
- Animal Husbandry Institute, Inner Mongolia Academy of Agricultural & Animal Husbandry Sciences, Hohhot, China
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19
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Palacios-Muñoz A, Escobar MJ, Vielma A, Araya J, Astudillo A, Valdivia G, García IE, Hurtado J, Schmachtenberg O, Martínez AD, Palacios AG. Role of connexin channels in the retinal light response of a diurnal rodent. Front Cell Neurosci 2014; 8:249. [PMID: 25202238 PMCID: PMC4142540 DOI: 10.3389/fncel.2014.00249] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 08/05/2014] [Indexed: 01/02/2023] Open
Abstract
Several studies have shown that connexin channels play an important role in retinal neural coding in nocturnal rodents. However, the contribution of these channels to signal processing in the retina of diurnal rodents remains unclear. To gain insight into this problem, we studied connexin expression and the contribution of connexin channels to the retinal light response in the diurnal rodent Octodon degus (degu) compared to rat, using in vivo ERG recording under scotopic and photopic light adaptation. Analysis of the degu genome showed that the common retinal connexins present a high degree of homology to orthologs expressed in other mammals, and expression of Cx36 and Cx43 was confirmed in degu retina. Cx36 localized mainly to the outer and inner plexiform layers (IPLs), while Cx43 was expressed mostly in cells of the retinal pigment epithelium. Under scotopic conditions, the b-wave response amplitude was strongly reduced by 18-β-glycyrrhetinic acid (β-GA) (−45.1% in degu, compared to −52.2% in rat), suggesting that connexins are modulating this response. Remarkably, under photopic adaptation, β-GA increased the ERG b-wave amplitude in degu (+107.2%) while reducing it in rat (−62.3%). Moreover, β-GA diminished the spontaneous action potential firing rate in ganglion cells (GCs) and increased the response latency of ON and OFF GCs. Our results support the notion that connexins exert a fine-tuning control of the retinal light response and have an important role in retinal neural coding.
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Affiliation(s)
- Angelina Palacios-Muñoz
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Maria J Escobar
- Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile
| | - Alex Vielma
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Joaquín Araya
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Aland Astudillo
- Departamento de Electrónica, Universidad Técnico Federico Santa María Valparaíso, Chile
| | - Gonzalo Valdivia
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Isaac E García
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - José Hurtado
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile
| | - Oliver Schmachtenberg
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Agustín D Martínez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile
| | - Adrian G Palacios
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso Valparaíso, Chile ; Instituto de Sistemas Complejos de Valparaíso Valparaíso, Chile
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20
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Emerling CA, Springer MS. Eyes underground: regression of visual protein networks in subterranean mammals. Mol Phylogenet Evol 2014; 78:260-70. [PMID: 24859681 DOI: 10.1016/j.ympev.2014.05.016] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 04/26/2014] [Accepted: 05/05/2014] [Indexed: 11/26/2022]
Abstract
Regressive evolution involves the degeneration of formerly useful structures in a lineage over time, and may be accompanied by the molecular decay of phenotype-specific genes. The mammalian eye has repeatedly undergone degeneration in taxa that occupy dim-light environments including subterranean habitats. Here we assess whether a decrease in the amount of light that reaches the retina is associated with increased regression of retinal genes, whether the phototransduction and visual cycle pathways degrade in a predictable pattern, and if the timing of retinal gene loss is associated with the entrance of mammalian lineages into subterranean environments. Sequence data were obtained from the publically available genomes of the Cape golden mole (Chrysochloris asiatica), naked mole-rat (Heterocephalus glaber) and star-nosed mole (Condylura cristata) for 65 genes associated with phototransduction, the visual cycle, and other retinal functions. Gene sequences were inspected for inactivating mutations and, when present, pseudogene sequences were compared to sequences from subaerial outgroup species. To test whether retinal degeneration is correlated with historical entrances into subterranean environments, estimated dates of retinal gene inactivation were compared to the fossil record and phylogenetic inferences of ancestral fossoriality. Our results show that (1) lower levels of light available to the retina correspond with an increase in the number of retinal pseudogenes, (2) retinal protein networks generally degrade in a predictable manner, although the extensive loss of cone phototransduction genes in Heterocephalus raises further questions regarding SWS1-cone monochromacy versus functional rod monochromacy in this species, and (3) inactivation dates of retinal genes usually post-date inferred entrances into subterranean habitats.
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Affiliation(s)
- Christopher A Emerling
- Department of Biology, University of California Riverside, 900 University Ave, Riverside, CA 92521, United States.
| | - Mark S Springer
- Department of Biology, University of California Riverside, 900 University Ave, Riverside, CA 92521, United States.
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21
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Douglas RH, Jeffery G. The spectral transmission of ocular media suggests ultraviolet sensitivity is widespread among mammals. Proc Biol Sci 2014; 281:20132995. [PMID: 24552839 PMCID: PMC4027392 DOI: 10.1098/rspb.2013.2995] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although ultraviolet (UV) sensitivity is widespread among animals it is considered rare in mammals, being restricted to the few species that have a visual pigment maximally sensitive (λmax) below 400 nm. However, even animals without such a pigment will be UV-sensitive if they have ocular media that transmit these wavelengths, as all visual pigments absorb significant amounts of UV if the energy level is sufficient. Although it is known that lenses of diurnal sciurid rodents, tree shrews and primates prevent UV from reaching the retina, the degree of UV transmission by ocular media of most other mammals without a visual pigment with λmax in the UV is unknown. We examined lenses of 38 mammalian species from 25 families in nine orders and observed large diversity in the degree of short-wavelength transmission. All species whose lenses removed short wavelengths had retinae specialized for high spatial resolution and relatively high cone numbers, suggesting that UV removal is primarily linked to increased acuity. Other mammals, however, such as hedgehogs, dogs, cats, ferrets and okapis had lenses transmitting significant amounts of UVA (315-400 nm), suggesting that they will be UV-sensitive even without a specific UV visual pigment.
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Affiliation(s)
- R H Douglas
- Department of Optometry and Visual Science, City University London, , Northampton Square, London EC1V 0HB, UK, Institute of Ophthalmology, University College London, , 11-43 Bath Street, London EC1V 9EL, UK
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22
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Retinal cone photoreceptors of the deer mouse Peromyscus maniculatus: development, topography, opsin expression and spectral tuning. PLoS One 2013; 8:e80910. [PMID: 24260509 PMCID: PMC3829927 DOI: 10.1371/journal.pone.0080910] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Accepted: 10/09/2013] [Indexed: 11/19/2022] Open
Abstract
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. Rod photoreceptors were counted using differential interference contrast microscopy. Pigmented P. maniculatus have a rod-dominated retina with rod densities of about 450.000/mm2 and cone densities of 3000 - 6500/mm2. Two cone opsins, shortwave sensitive (S) and middle-to-longwave sensitive (M), are present and expressed in distinct cone types. Partial sequencing of the S opsin gene strongly supports UV sensitivity of the S cone visual pigment. The S cones constitute a 5-15% minority of the cones. Different from house mouse, S and M cone distributions do not have dorsoventral gradients, and coexpression of both opsins in single cones is exceptional (<2% of the cones). In albino P. maniculatus, rod densities are reduced by approximately 40% (270.000/mm2). Overall, cone density and the density of cones exclusively expressing S opsin are not significantly different from pigmented P. maniculatus. However, in albino retinas S opsin is coexpressed with M opsin in 60-90% of the cones and therefore the population of cones expressing only M opsin is significantly reduced to 5-25%. In conclusion, deer mouse cone properties largely conform to the general mammalian pattern, hence the deer mouse may be better suited than the house mouse for the study of certain basic cone properties, including the effects of albinism on cone opsin expression.
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Abstract
AbstractS 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. During retinal development, SWS1 opsin expression generally precedes that of LWS opsin, and evidence from genetic studies indicates that the S cone pathway may be the default pathway for cone development. With the notable exception of the cartilaginous fishes, where S cones appear to be absent, they are present in representative species from all other vertebrate classes. S cone loss is not, however, uncommon; they are absent from most aquatic mammals and from some but not all nocturnal terrestrial species. The peak spectral sensitivity of S cones depends on the spectral characteristics of the pigment present. Evidence from the study of agnathans and teleost fishes indicates that the ancestral vertebrate SWS1 pigment was ultraviolet (UV) sensitive with a peak around 360 nm, but this has shifted into the violet region of the spectrum (>380 nm) on many separate occasions during vertebrate evolution. In all cases, the shift was generated by just one or a few replacements in tuning-relevant residues. Only in the avian lineage has tuning moved in the opposite direction, with the reinvention of UV-sensitive pigments.
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Moritz GL, Lim NTL, Neitz M, Peichl L, Dominy NJ. Expression and Evolution of Short Wavelength Sensitive Opsins in Colugos: A Nocturnal Lineage That Informs Debate on Primate Origins. Evol Biol 2013; 40:542-553. [PMID: 24293738 PMCID: PMC3832777 DOI: 10.1007/s11692-013-9230-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 03/29/2013] [Indexed: 11/25/2022]
Abstract
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. Here we show that the eye of the Sunda colugo (Galeopterus variegatus) lacks a tapetum lucidum and has an avascular retina, and we report on the expression and spectral sensitivity of cone photopigments. We found that Sunda colugos have intact short wavelength sensitive (S-) and long wavelength sensitive (L-) opsin genes, and that both opsins are expressed in cone photoreceptors of the retina. The inferred peak spectral sensitivities are 451 and 562 nm, respectively. In line with adaptation to nocturnal vision, cone densities are low. Surprisingly, a majority of S-cones coexpress some L-opsin. We also show that the ratio of rates of nonsynonymous to synonymous substitutions of exon 1 of the S-opsin gene is indicative of purifying selection. Taken together, our results suggest that natural selection has favored a functional S-opsin in a nocturnal lineage for at least 45 million years. Accordingly, a nocturnal activity pattern remains the most likely ancestral character state of euprimates.
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Affiliation(s)
- Gillian L. Moritz
- Department of Biological Sciences, Dartmouth College, The Class of 1978 Life Sciences Center, 78 College Street, Hanover, NH 03755 USA
| | - Norman T.-L. Lim
- Department of Wildlife, Fish and Conservation Biology, University of California, One Shields Avenue, Davis, CA 95616 USA
| | - Maureen Neitz
- Department of Ophthalmology, University of Washington, Box 356485, 1959 NE Pacific Street, Seattle, WA 98195 USA
| | - Leo Peichl
- Max Planck Institute for Brain Research, Deutschordenstrasse 46, 60528 Frankfurt am Main, Germany
| | - Nathaniel J. Dominy
- Department of Biological Sciences, Dartmouth College, The Class of 1978 Life Sciences Center, 78 College Street, Hanover, NH 03755 USA
- Department of Anthropology, Dartmouth College, 6047 Silsby Hall, Hanover, NH 03755 USA
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Ardiles AO, Ewer J, Acosta ML, Kirkwood A, Martinez AD, Ebensperger LA, Bozinovic F, Lee TM, Palacios AG. Octodon degus (Molina 1782): a model in comparative biology and biomedicine. Cold Spring Harb Protoc 2013; 2013:312-8. [PMID: 23547147 DOI: 10.1101/pdb.emo071357] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
One major goal of integrative and comparative biology is to understand and explain the interaction between the performance and behavior of animals in their natural environment. The Caviomorph, Octodon degu, is a native rodent species from Chile, and represents a unique model to study physiological and behavioral traits, including cognitive and sensory abilities. Degus live in colonies and have a well-structured social organization, with a mostly diurnal-crepuscular circadian activity pattern. More notable is the fact that in captivity, they reproduce and live between 5 and 7 yr and show hallmarks of neurodegenerative diseases (including Alzheimer's disease), diabetes, and cancer.
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Affiliation(s)
- Alvaro O Ardiles
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, 2360102 Valparaíso, Chile
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DAVIES WAYNEIL, COLLIN SHAUNP, HUNT DAVIDM. Molecular ecology and adaptation of visual photopigments in craniates. Mol Ecol 2012; 21:3121-58. [DOI: 10.1111/j.1365-294x.2012.05617.x] [Citation(s) in RCA: 156] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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MELIN AMANDAD, MORITZ GILLIANL, FOSBURY ROBERTAE, KAWAMURA SHOJI, DOMINY NATHANIELJ. Why Aye-Ayes See Blue. Am J Primatol 2012; 74:185-92. [DOI: 10.1002/ajp.21996] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- AMANDA D. MELIN
- Department of Anthropology; Dartmouth College; Hanover; New Hampshire
| | - GILLIAN L. MORITZ
- Department of Biological Sciences; Dartmouth College; Hanover; New Hampshire
| | | | - SHOJI KAWAMURA
- Department of Integrated Bioscience; University of Tokyo; Kashiwa; Chiba; Japan
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Why different regions of the retina have different spectral sensitivities: A review of mechanisms and functional significance of intraretinal variability in spectral sensitivity in vertebrates. Vis Neurosci 2011; 28:281-93. [DOI: 10.1017/s0952523811000113] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractVision is used in nearly all aspects of animal behavior, from prey and predator detection to mate selection and parental care. However, the light environment typically is not uniform in every direction, and visual tasks may be specific to particular parts of an animal’s field of view. These spatial differences may explain the presence of several adaptations in the eyes of vertebrates that alter spectral sensitivity of the eye in different directions. Mechanisms that alter spectral sensitivity across the retina include (but are not limited to) variations in: corneal filters, oil droplets, macula lutea, tapeta, chromophore ratios, photoreceptor classes, and opsin expression. The resultant variations in spectral sensitivity across the retina are referred to as intraretinal variability in spectral sensitivity (IVSS). At first considered an obscure and rare phenomenon, it is becoming clear that IVSS is widespread among all vertebrates, and examples have been found from every major group. This review will describe the mechanisms mediating differences in spectral sensitivity, which are in general well understood, as well as explore the functional significance of intraretinal variability, which for the most part is unclear at best.
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Schleich CE, Vielma A, Glösmann M, Palacios AG, Peichl L. Retinal photoreceptors of two subterranean tuco-tuco species (Rodentia, Ctenomys): morphology, topography, and spectral sensitivity. J Comp Neurol 2010; 518:4001-15. [PMID: 20737597 DOI: 10.1002/cne.22440] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Traditionally, vision was thought to be useless for animals living in dark underground habitats, but recent studies in a range of subterranean rodent species have shown a large diversity of eye features, from small subcutaneous eyes to normal-sized functional eyes. We analyzed the retinal photoreceptors in the subterranean hystricomorph rodents Ctenomys talarum and Ctenomys magellanicus to elucidate whether adaptation was to their near-lightless burrows or rather to their occasional diurnal surface activity. Both species had normally developed eyes. Overall photoreceptor densities were comparatively low (95,000-150,000/mm(2) in C. magellanicus, 110,000-200,000/mm(2) in C. talarum), and cone proportions were rather high (10-31% and 14-31%, respectively). The majority of cones expressed the middle-to-longwave-sensitive (L) opsin, and a 6-16% minority expressed the shortwave-sensitive (S) opsin. In both species the densities of L and S cones were higher in ventral than in dorsal retina. In both species the tuning-relevant amino acids of the S opsin indicate sensitivity in the near UV rather than the blue/violet range. Photopic spectral electroretinograms were recorded. Unexpectedly, their sensitivity profiles were best fitted by the linear summation of three visual pigment templates with lambda(max) at 370 nm (S pigment, UV), at 510 nm (L pigment), and at 450 nm (an as-yet unexplained mechanism). Avoiding predators and selecting food during the brief aboveground excursions may have exerted pressure to retain robust cone-based vision in Ctenomys. UV tuning of the S cone pigment is shared with a number of other hystricomorphs.
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Affiliation(s)
- Cristian E Schleich
- Laboratorio Ecofisiología, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Argentina.
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Kott O, Šumbera R, Němec P. Light perception in two strictly subterranean rodents: life in the dark or blue? PLoS One 2010; 5:e11810. [PMID: 20676369 PMCID: PMC2911378 DOI: 10.1371/journal.pone.0011810] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Accepted: 06/23/2010] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND The African mole-rats (Bathyergidae, Rodentia) are strictly subterranean, congenitally microphthalmic rodents that are hardly ever exposed to environmental light. Because of the lack of an overt behavioural reaction to light, they have long been considered to be blind. However, recent anatomical studies have suggested retention of basic visual capabilities. In this study, we employed behavioural tests to find out if two mole-rat species are able to discriminate between light and dark, if they are able to discriminate colours and, finally, if the presence of light in burrows provokes plugging behaviour, which is assumed to have a primarily anti-predatory function. METHODOLOGY/PRINCIPAL FINDING We used a binary choice test to show that the silvery mole-rat Heliophobius argenteocinereus and the giant mole-rat Fukomys mechowii exhibit a clear photoavoidance response to full-spectrum ("white"), blue and green-yellow light, but no significant reaction to ultraviolet or red light during nest building. The mole-rats thus retain dark/light discrimination capabilities and a capacity to perceive short to medium-wavelength light in the photopic range of intensities. These findings further suggest that the mole-rat S opsin has its absorption maximum in the violet/blue part of the spectrum. The assay did not yield conclusive evidence regarding colour discrimination. To test the putative role of vision in bathyergid anti-predatory behaviour, we examined the reaction of mole-rats to the incidence of light in an artificial burrow system. The presence of light in the burrow effectively induced plugging of the illuminated tunnel. CONCLUSION/SIGNIFICANCE Our findings suggest that the photopic vision is conserved and that low acuity residual vision plays an important role in predator avoidance and tunnel maintenance in the African mole-rats.
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Affiliation(s)
- Ondřej Kott
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Radim Šumbera
- Department of Zoology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
| | - Pavel Němec
- Department of Zoology, Faculty of Science, Charles University in Prague, Prague, Czech Republic
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Palacios AG, Bozinovic F, Vielma A, Arrese CA, Hunt DM, Peichl L. Retinal photoreceptor arrangement, SWS1 and LWS opsin sequence, and electroretinography in the South American marsupial Thylamys elegans (Waterhouse, 1839). J Comp Neurol 2010; 518:1589-602. [PMID: 20187149 DOI: 10.1002/cne.22292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We studied the retinal photoreceptors in the mouse opossum Thylamys elegans, a nocturnal South American marsupial. A variety of photoreceptor properties and color vision capabilities have been documented in Australian marsupials, and we were interested to establish what similarities and differences this American marsupial showed. Thylamys opsin gene sequencing revealed two cone opsins, a longwave-sensitive (LWS) opsin and a shortwave-sensitive (SWS1) opsin with deduced peak sensitivities at 560 nm and 360 nm (ultraviolet), respectively. Immunocytochemistry located these opsins to separate cone populations, a majority of LWS cones (density range 1,600-5,600/mm(2)) and a minority of SWS1 cones (density range 100-690/mm(2)). With rod densities of 440,000-590,000/mm(2), the cones constituted 0.4-1.2% of the photoreceptors. This is a suitable adaptation to nocturnal vision. Cone densities peaked in a horizontally elongated region ventral to the optic nerve head. In ventral-but not dorsal-retina, roughly 40% of the LWS opsin-expressing cones occurred as close pairs (double cones), and one member of each double cone contained a colorless oil droplet. The corneal electroretinogram (ERG) showed a high scotopic sensitivity with a rod peak sensitivity at 505 nm. At mesopic light levels, the spectral ERG revealed the contributions of a UV-sensitive SWS1 cone mechanism and an LWS cone mechanism with peak sensitivities at 365 nm and 555 nm, respectively, confirming the tuning predictions from the cone opsin sequences. The two spectral cone types provide the basis for dichromatic color vision, or trichromacy if the rods contribute to color processing at mesopic light levels.
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Affiliation(s)
- Adrián G Palacios
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso 2370006, Chile
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Abstract
Cones with peak sensitivity to light at long (L), medium (M) and short (S) wavelengths are unequal in number on the human retina: S cones are rare (<10%) while increasing in fraction from center to periphery, and the L/M cone proportions are highly variable between individuals. What optical properties of the eye, and statistical properties of natural scenes, might drive this organization? We found that the spatial-chromatic structure of natural scenes was largely symmetric between the L, M and S sensitivity bands. Given this symmetry, short wavelength attenuation by ocular media gave L/M cones a modest signal-to-noise advantage, which was amplified, especially in the denser central retina, by long-wavelength accommodation of the lens. Meanwhile, total information represented by the cone mosaic remained relatively insensitive to L/M proportions. Thus, the observed cone array design along with a long-wavelength accommodated lens provides a selective advantage: it is maximally informative. Human color perception arises by comparing the signals from cones with peak sensitivities, at long (L), medium (M) and short (S) wavelengths. In dichromats, a characteristic distribution of S and M cones supports blue-yellow color vision: a few S and mostly M. When L cones are added, allowing red-green color vision, the S proportion remains low, increasing slowly with increasing retinal eccentricity, but the L/M proportion can vary 5-fold without affecting red-green color perception. We offer a unified explanation of these striking facts. First, we find that the spatial-chromatic statistics of natural scenes are largely symmetric between the L, M and S sensitivity bands. Thus, attenuation of blue light in the optical media, and chromatic aberration after long-wavelength accommodation of the lens, can give L/M cones an advantage. Quantitatively, information transmission by the cone array is maximized when the S proportion is low but increasing slowly with retinal eccentricity, accompanied by a lens accommodated to red light. After including blur by the lens, the optimum depends weakly on the red/green ratio, allowing large variations without loss of function. This explains the basic layout of the cone mosaic: for the resources invested, the organization maximizes information.
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Hunt DM, Carvalho LS, Cowing JA, Davies WL. Evolution and spectral tuning of visual pigments in birds and mammals. Philos Trans R Soc Lond B Biol Sci 2009; 364:2941-55. [PMID: 19720655 DOI: 10.1098/rstb.2009.0044] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Variation in the types and spectral characteristics of visual pigments is a common mechanism for the adaptation of the vertebrate visual system to prevailing light conditions. The extent of this diversity in mammals and birds is discussed in detail in this review, alongside an in-depth consideration of the molecular changes involved. In mammals, a nocturnal stage in early evolution is thought to underlie the reduction in the number of classes of cone visual pigment genes from four to only two, with the secondary loss of one of these genes in many monochromatic nocturnal and marine species. The trichromacy seen in many primates arises from either a polymorphism or duplication of one of these genes. In contrast, birds have retained the four ancestral cone visual pigment genes, with a generally conserved expression in either single or double cone classes. The loss of sensitivity to ultraviolet (UV) irradiation is a feature of both mammalian and avian visual evolution, with UV sensitivity retained among mammals by only a subset of rodents and marsupials. Where it is found in birds, it is not ancestral but newly acquired.
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Affiliation(s)
- David M Hunt
- UCL Institute of Ophthalmology, London EC1V 9EL, UK.
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Müller B, Glösmann M, Peichl L, Knop GC, Hagemann C, Ammermüller J. Bat eyes have ultraviolet-sensitive cone photoreceptors. PLoS One 2009; 4:e6390. [PMID: 19636375 PMCID: PMC2712075 DOI: 10.1371/journal.pone.0006390] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 06/26/2009] [Indexed: 11/18/2022] Open
Abstract
Mammalian retinae have rod photoreceptors for night vision and cone photoreceptors for daylight and colour vision. For colour discrimination, most mammals possess two cone populations with two visual pigments (opsins) that have absorption maxima at short wavelengths (blue or ultraviolet light) and long wavelengths (green or red light). Microchiropteran bats, which use echolocation to navigate and forage in complete darkness, have long been considered to have pure rod retinae. Here we use opsin immunohistochemistry to show that two phyllostomid microbats, Glossophaga soricina and Carollia perspicillata, possess a significant population of cones and express two cone opsins, a shortwave-sensitive (S) opsin and a longwave-sensitive (L) opsin. A substantial population of cones expresses S opsin exclusively, whereas the other cones mostly coexpress L and S opsin. S opsin gene analysis suggests ultraviolet (UV, wavelengths <400 nm) sensitivity, and corneal electroretinogram recordings reveal an elevated sensitivity to UV light which is mediated by an S cone visual pigment. Therefore bats have retained the ancestral UV tuning of the S cone pigment. We conclude that bats have the prerequisite for daylight vision, dichromatic colour vision, and UV vision. For bats, the UV-sensitive cones may be advantageous for visual orientation at twilight, predator avoidance, and detection of UV-reflecting flowers for those that feed on nectar.
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Affiliation(s)
- Brigitte Müller
- Max Planck Institute for Brain Research, Frankfurt/Main, Germany.
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Delgado LM, Vielma AH, Kähne T, Palacios AG, Schmachtenberg O. The GABAergic system in the retina of neonate and adult Octodon degus, studied by immunohistochemistry and electroretinography. J Comp Neurol 2009; 514:459-72. [PMID: 19350652 DOI: 10.1002/cne.22023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
UNLABELLED In the vertebrate retina, gamma-aminobutyric acid (GABA) mediates inhibitory processes that shape the visual response and is also thought to have neurotrophic functions during retinal development. To investigate the role of GABAergic signaling at the beginning of visual experience, we used immunohistochemistry to compare the distribution of GABA, the two isoforms of glutamic acid decarboxylase GAD65/67, and the GABA receptor types A, B, and C, in neonate versus adult Octodon degus, a native South American rodent with diurnal-crepuscular activity and a high cone-to-rod ratio. In parallel, we used electroretinography to evaluate retinal functionality and to test the contribution of fast GABAergic transmission to light responses at both developmental stages. Neonate O. degus opened their eyes on postnatal day (P)0 and displayed an adult-like retinal morphology at this time. GABA, its biosynthetic sources, and receptors had a similar cellular distribution in neonates and adults, but labeling of the outer plexiform layer and of certain amacrine and ganglion cells was more conspicuous at P0. In neonates, retinal sensitivity was 10 times lower than in adults, responses to ultraviolet light could not be detected, and oscillatory potentials were reduced or absent. Blockade of GABA(A/C) receptors by bicuculline and TPMPA had no noticeable effect in neonates, while it significantly altered the electroretinogram response in adults. CONCLUSION In spite of modest differences regarding retinal morphology and GABAergic expression, overall light response properties and GABAergic signaling are undeveloped in neonate O. degus compared to adults, suggesting that full retinal functionality requires a period of neural refinement under visual experience.
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Affiliation(s)
- Luz M Delgado
- Centro de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Chile
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The topography of cone photoreceptors in the retina of a diurnal rodent, the agouti (Dasyprocta aguti). Vis Neurosci 2009; 26:167-75. [PMID: 19250601 DOI: 10.1017/s095252380808098x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The presence, density distribution, and mosaic regularity of cone types were studied in the retina of the diurnal agouti, Dasyprocta aguti. Longwave-sensitive (L-) and shortwave-sensitive (S-) cones were detected by antibodies against the respective cone opsins. L- and S-cones were found to represent around 90 and 10% of the cone population, respectively. There was no evidence for L- and S-opsin coexpression in agouti cones. L-cone densities were highest, up to 14,000/mm2, along a horizontal visual streak located about 2-3 mm dorsal to the optic nerve, and the L-cone distribution showed a dorsoventral asymmetry with higher densities in ventral (about 10,000/mm2) than in dorsal (about 4000/mm2) retinal regions. This L-cone topography parallels the agouti's ganglion cell topography. S-cones had a peak density of 1500-2000/mm2 in the central retinal region but did not form a visual streak. Their distribution also showed a dorsoventral asymmetry with densities around 600/mm2 in dorsal and around 1000/mm2 in ventral retinal regions. The patterning of cone arrays was assessed by the density recovery profile analysis. At all eccentricities evaluated, the S-cone mosaic less efficiently packed than the L-cone mosaic. Rod densities ranged from 47,000/mm2 in peripheral to 64,000/mm2 in central retina, and rod:cone ratios were 4:1-9:1. The comparatively low rod density and high cone proportion appear well adapted to the diurnal lifestyle of the agouti.
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Kronfeld-Schor N, Dayan T. Activity patterns of rodents: the physiological ecology of biological rhythms. BIOL RHYTHM RES 2008. [DOI: 10.1080/09291010701683268] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Castilla AM, Robles H, Van Dongen S, Matthysen E. The influence of egg size and colour on egg consumption by the Algerian hedgehog (Atelerix algirus). J ETHOL 2008. [DOI: 10.1007/s10164-008-0095-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Ahnelt PK, Schubert C, Kübber-Heiss A, Schiviz A, Anger E. Independent variation of retinal S and M cone photoreceptor topographies: A survey of four families of mammals. Vis Neurosci 2006; 23:429-35. [PMID: 16961976 DOI: 10.1017/s095252380623342x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Accepted: 12/26/2005] [Indexed: 11/07/2022]
Abstract
In mammals, cone photoreceptor subtypes are thought to establish topographies that reflect the species-relevant properties of the visual environment. Middle- to long-wavelength-sensitive (M) cones are the dominant population and in most species they form an area centralis at the visual axis. Short-wavelength-sensitive (S) cone topographies do not always match this pattern. We here correlate the interrelationship of S and M cone topographies in representatives of several mammalian orders with different visual ecology, including man, cheetah, cat, Eurasian lynx, African lion, wild hog, roe deer, and red deer. Retinas were labeled with opsin antisera and S and M cone distributions as well as S/M cone ratios were mapped. We find that species inhabiting open environments show M cone horizontal streaks (cheetah, pig, deer). Species living in structured habitats (tiger, lynx, red deer) have increased S cone densities along the retinal margin. In species with active vision (cheetah, bear, tiger, man), S cone distributions are more likely to follow the centripetal M cone gradients. Small species show a ventral bias of peak S cone density which either matches the peak of M cone density in a temporal area centralis (diurnal sciurid rodents, tree shrews) or not (cat, manul, roe deer). Thus, in addition to habitat structure, physical size and specific lifestyle patterns (e.g. food acquisition) appear to underlie the independent variations of M and S cone topographies.
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Affiliation(s)
- Peter Kurt Ahnelt
- Department of Physiology, Unit of Physiology and Pathophysiology, Medical University of Vienna, Vienna, Austria.
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Hagemeyer P, Begall S. Individual Odour Similarity and Discrimination in the Coruro (Spalacopus cyanus, Octodontidae). Ethology 2006. [DOI: 10.1111/j.1439-0310.2006.01198.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Peichl L. Diversity of mammalian photoreceptor properties: adaptations to habitat and lifestyle? ACTA ACUST UNITED AC 2006; 287:1001-12. [PMID: 16200646 DOI: 10.1002/ar.a.20262] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
All mammalian retinae contain rod photoreceptors for low-light vision and cone photoreceptors for daylight and color vision. Most nonprimate mammals have dichromatic color vision based on two cone types with spectrally different visual pigments: a short-wavelength-sensitive (S-)cone and a long-wavelength-sensitive (L-)cone. Superimposed on this basic similarity, there are remarkable differences between species. This article reviews some striking examples. The density ratio of cones to rods ranges from 1:200 in the most nocturnal to 20:1 in a few diurnal species. In some species, the proportion of the spectral cone types and their distribution across the retina deviate from the pattern found in most mammals, including a complete absence of S-cones. Depending on species, the spectral sensitivity of the L-cone pigment may peak in the green, yellow, or orange, and that of the S-cone pigment in the blue, violet, or near-ultraviolet. While exclusive expression of one pigment per cone is the rule, some species feature coexpression of the L- and S-pigment in a significant proportion of their cones. It is widely assumed that all these variations represent adaptations to specific visual needs associated with particular habitats and lifestyles. However, in many cases we have not yet identified the adaptive value of a given photoreceptor arrangement. Comparative anatomy is a fruitful approach to explore the range of possible arrangements within the blueprint of the mammalian retina and to identify species with particularly interesting or puzzling patterns that deserve further scrutiny with physiological and behavioral assays.
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Affiliation(s)
- Leo Peichl
- Max Planck Institute for Brain Research, Frankfurt, Germany.
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Müller B, Goodman SM, Peichl L. Cone photoreceptor diversity in the retinas of fruit bats (megachiroptera). BRAIN, BEHAVIOR AND EVOLUTION 2005; 70:90-104. [PMID: 17522478 DOI: 10.1159/000102971] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Accepted: 09/24/2006] [Indexed: 11/19/2022]
Abstract
Older studies have claimed that bats including the Megachiroptera (fruit bats or flying foxes) have pure-rod retinas and possess no cone photoreceptors. We have determined the presence and the population densities of spectral cone types in six megachiropteran species belonging to four genera: Pteropus rufus, P. niger, P. rodricensis, Rousettus madagascariensis, Eidolon dupreanum, and Epomophorus gambianus. Spectral cone types and rods were assessed immunocytochemically with opsin-specific antibodies. All six species have rod-dominated retinas but possess significant cone populations. The high rod densities (range 350,000-800,000/mm(2), depending on species and retinal location) provide good scotopic sensitivity in these predominantly nocturnal animals. With the cones (density range 1,300-11,000/mm(2), corresponding to 0.25-0.6% of the photoreceptors, depending on species and retinal location) the retinas also possess the prerequisite for vision at photopic light levels. The three Pteropus species have two spectral cone types, a majority of middle-to-long-wave sensitive (L-) cones, and a minority of short-wave sensitive (S-) cones, indicating the potential for dichromatic color vision. This conforms to the pattern found in most mammals. In contrast, Rousettus, Eidolon and Epomophorus have L-cones but completely lack S-cones, indicating cone monochromacy and color blindness. The discussion relates these findings to the visual behavior of fruit bats.
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Affiliation(s)
- Brigitte Müller
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany.
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