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Kim S, Moore BA, Parker C, Siniard WC, Ang J, Teixeira LBC, Thomasy SM, Murphy CJ, Soto E. Clinical and histopathological features of proliferative corneal lesions in Cyprininae fishes: Implications for treatment and insights into corneal tumors. Vet Ophthalmol 2024; 27:200-213. [PMID: 37485736 DOI: 10.1111/vop.13133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 07/10/2023] [Accepted: 07/14/2023] [Indexed: 07/25/2023]
Abstract
Captive fish populations, such as those encompassing aquarium and pet fish, offer significant economic value and are integral to conservation, research, and education. However, these ornamental fish exhibit a reduced ability to protect their ocular surfaces, and our understanding of the ocular diseases that affect them remains limited. Although corneal neoplasms in carp are uncommon, identifying their distinct characteristics is crucial in selecting appropriate therapeutic interventions that aim to preserve vision, prevent the ocular loss, and ultimately ensure the survival of the affected fish. This study provides clinical and histopathological details of various proliferative corneal masses in Cyprininae species, including five koi (Cyprinus carpio) and four goldfish (Carassius auratus). It discusses a spectrum of neoplasms, including soft tissue sarcoma, spindle cell sarcoma, chromatophoroma, and papilloma, in addition to conditions like exuberant granulation tissue and proliferative carp pox. These findings bear significant implications for clinical decision-making and treatment, offering valuable insights into the incidence and characteristics of corneal tumors in captive fish, which could inform further studies in this area.
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Affiliation(s)
- Soohyun Kim
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| | - Bret A Moore
- Department of Small Animal Clinical Science, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Christine Parker
- Departments of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | - Wesley C Siniard
- Departments of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | - June Ang
- Departments of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, California, USA
| | - Leandro B C Teixeira
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sara M Thomasy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, California, USA
| | - Christopher J Murphy
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
- Department of Ophthalmology & Vision Science, School of Medicine, University of California-Davis, Davis, California, USA
| | - Esteban Soto
- Departments of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California Davis, Davis, California, USA
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2
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Barry Collin H, Ratcliffe J, Collin SP. Morphology of the cornea and iris in the Australian lungfish Neoceratodus forsteri (Krefft 1870) (Dipnoi): Functional and evolutionary perspectives of transitioning from an aquatic to a terrestrial environment. J Morphol 2024; 285:e21662. [PMID: 38100743 DOI: 10.1002/jmor.21662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 11/26/2023] [Accepted: 11/29/2023] [Indexed: 12/17/2023]
Abstract
The Australian lungfish, Neoceratodus forsteri (Krefft 1870), is the sole extant member of the Ceratodontidae within the Dipnoi, a small order of sarcopterygian (lobe-finned) fishes, that is thought to be the earliest branching species of extant lungfishes, having changed little over the last 100 million years. To extend studies on anatomical adaptations associated with the fish-tetrapod transition, the ultrastructure of the cornea and iris is investigated using light and electron (transmission and scanning) microscopy to investigate structure-function relationships and compare these to other vertebrate corneas (other fishes and tetrapods). In contrast to previous studies, the cornea is found to have only three main components, comprising an epithelium with its basement membrane, a stroma with a Bowman's layer and an endothelium, and is not split into a dermal (secondary) spectacle and a scleral cornea. The epithelial cells are large, relatively low in density and similar to many species of non-aquatic tetrapods and uniquely possess numerous surface canals that contain and release mucous granules onto the corneal surface to avoid desiccation. A Bowman's layer is present and, in association with extensive branching and anastomosing of the collagen fibrils, may be an adaptation for the inhibition of swelling and/or splitting of the stroma during its amphibious lifestyle. The dorsal region of the stroma possesses aggregations of pigment granules that act as a yellow, short wavelength-absorbing filter during bright light conditions. Desçemet's membrane is absent and replaced by an incomplete basement membrane overlying a monocellular endothelium. The iris is pigmented, well-developed, vascularised and contractile containing reflective crystals anteriorly. Based upon its ultrastructure and functional adaptations, the cornea of N. forsteri is more similar to amphibians than to other bony fishes and is well-adapted for an amphibious lifestyle.
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Affiliation(s)
- Hermann Barry Collin
- Department of Optometry and Vision Science, University of New South Wales, Kensington, New South Wales, Australia
| | - Julian Ratcliffe
- Bioimaging Platform, La Trobe University, Bundoora, Victoria, Australia
| | - Shaun P Collin
- School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
- Oceans Graduate School and Oceans Institute, The University of Western Australia, Crawley, Western Australia, Australia
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3
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Stieb SM, Cortesi F, de Queiroz LJ, Carleton KL, Seehausen O, Marshall NJ. Long-wavelength-sensitive (lws) opsin gene expression, foraging and visual communication in coral reef fishes. Mol Ecol 2023; 32:1656-1672. [PMID: 36560895 PMCID: PMC10065935 DOI: 10.1111/mec.16831] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 11/25/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022]
Abstract
Coral reef fishes are diverse in ecology and behaviour and show remarkable colour variability. Investigating the visual pigment gene (opsin) expression in these fishes makes it possible to associate their visual genotype and phenotype (spectral sensitivities) to visual tasks, such as feeding strategy or conspecific detection. By studying all major damselfish clades (Pomacentridae) and representatives from five other coral reef fish families, we show that the long-wavelength-sensitive (lws) opsin is highly expressed in algivorous and less or not expressed in zooplanktivorous species. Lws is also upregulated in species with orange/red colours (reflectance >520 nm) and expression is highest in orange/red-coloured algivores. Visual models from the perspective of a typical damselfish indicate that sensitivity to longer wavelengths does enhance the ability to detect the red to far-red component of algae and orange/red-coloured conspecifics, possibly enabling social signalling. Character state reconstructions indicate that in the early evolutionary history of damselfishes, there was no lws expression and no orange/red coloration. Omnivory was most often the dominant state. Although herbivory was sometimes dominant, zooplanktivory was never dominant. Sensitivity to long wavelength (increased lws expression) only emerged in association with algivory but never with zooplanktivory. Higher lws expression is also exploited by social signalling in orange/red, which emerged after the transition to algivory. Although the relative timing of traits may deviate by different reconstructions and alternative explanations are possible, our results are consistent with sensory bias whereby social signals evolve as a correlated response to natural selection on sensory system properties in other contexts.
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Affiliation(s)
- Sara M. Stieb
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Luiz Jardim de Queiroz
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
| | - Karen L. Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ole Seehausen
- Centre for Ecology, Evolution and Biogeochemistry (CEEB), EAWAG Swiss Federal Institute of Aquatic Science and Technology, Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, Switzerland
| | - N. Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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Rossi GS, Labbé D, Wright PA. Out of water in the dark: Plasticity in visual structures and function in an amphibious fish. JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:776-784. [PMID: 35727120 DOI: 10.1002/jez.2636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/20/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
Many fishes encounter periods of prolonged darkness within their lifetime, yet the consequences for the visual system are poorly understood. We used an amphibious fish (Kryptolebias marmoratus) that occupies dark terrestrial environments during seasonal droughts to test whether exposure to prolonged darkness diminishes visual performance owing to reduced optic tectum (OT) size and/or neurogenesis. We performed a 3-week acclimation with a 2 ×$\times $ 2 factorial design, in which fish were either acclimated to a 12 h:12 h or 0 h:24 h light:dark photoperiod in water or in air. We found that water-exposed fish had poorer visual acuity when acclimated to the dark, while air-acclimated fish had poorer visual acuity regardless of photoperiod. The ability of K. marmoratus to capture aerial prey from water followed a similar trend, suggesting that good vision is important for hunting effectively. Changes in visual acuity did not result from changes in OT size, but air-acclimated fish had 37% fewer proliferating cells in the OT than water-acclimated fish. As K. marmoratus are unable to eat on land, reducing cell proliferation in the OT may serve as a mechanism to reduce maintenance costs associated with the visual system. Overall, we suggest that prolonged darkness and air exposure can impair vision in K. marmoratus, and that changes in visual performance may be mediated, in part, by OT neurogenesis. More broadly, we show that plastic changes to the visual system of fishes can have potential consequences for organismal performance and fitness.
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Affiliation(s)
- Giulia S Rossi
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
- Department of Biological Sciences, University of Toronto Scarborough, Scarborough, Ontario, Canada
| | - Daniel Labbé
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
- School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Patricia A Wright
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
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de Busserolles F, Cortesi F, Fogg L, Stieb SM, Luehrmann M, Marshall NJ. The visual ecology of Holocentridae, a nocturnal coral reef fish family with a deep-sea-like multibank retina. J Exp Biol 2021; 224:jeb233098. [PMID: 33234682 DOI: 10.1242/jeb.233098] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 11/16/2020] [Indexed: 12/21/2022]
Abstract
The visual systems of teleost fishes usually match their habitats and lifestyles. Since coral reefs are bright and colourful environments, the visual systems of their diurnal inhabitants have been more extensively studied than those of nocturnal species. In order to fill this knowledge gap, we conducted a detailed investigation of the visual system of the nocturnal reef fish family Holocentridae. Results showed that the visual system of holocentrids is well adapted to their nocturnal lifestyle with a rod-dominated retina. Surprisingly, rods in all species were arranged into 6-17 well-defined banks, a feature most commonly found in deep-sea fishes, that may increase the light sensitivity of the eye and/or allow colour discrimination in dim light. Holocentrids also have the potential for dichromatic colour vision during the day with the presence of at least two spectrally different cone types: single cones expressing the blue-sensitive SWS2A gene, and double cones expressing one or two green-sensitive RH2 genes. Some differences were observed between the two subfamilies, with Holocentrinae (squirrelfish) having a slightly more developed photopic visual system than Myripristinae (soldierfish). Moreover, retinal topography of both ganglion cells and cone photoreceptors showed specific patterns for each cell type, likely highlighting different visual demands at different times of the day, such as feeding. Overall, their well-developed scotopic visual systems and the ease of catching and maintaining holocentrids in aquaria, make them ideal models to investigate teleost dim-light vision and more particularly shed light on the function of the multibank retina and its potential for dim-light colour vision.
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Affiliation(s)
- Fanny de Busserolles
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Lily Fogg
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sara M Stieb
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
- Center for Ecology, Evolution and Biogeochemistry, Eawag Federal Institute of Aquatic Science and Technology, Seestrasse 79, 6074 Kastanienbaum, Switzerland; and Institute for Ecology and Evolution, University of Bern, Baltzerstrasse 6, 3012 Bern, Switzerland
| | - Martin Luehrmann
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - N Justin Marshall
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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6
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Carleton KL, Escobar-Camacho D, Stieb SM, Cortesi F, Marshall NJ. Seeing the rainbow: mechanisms underlying spectral sensitivity in teleost fishes. J Exp Biol 2020; 223:jeb193334. [PMID: 32327561 PMCID: PMC7188444 DOI: 10.1242/jeb.193334] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among vertebrates, teleost eye diversity exceeds that found in all other groups. Their spectral sensitivities range from ultraviolet to red, and the number of visual pigments varies from 1 to over 40. This variation is correlated with the different ecologies and life histories of fish species, including their variable aquatic habitats: murky lakes, clear oceans, deep seas and turbulent rivers. These ecotopes often change with the season, but fish may also migrate between ecotopes diurnally, seasonally or ontogenetically. To survive in these variable light habitats, fish visual systems have evolved a suite of mechanisms that modulate spectral sensitivities on a range of timescales. These mechanisms include: (1) optical media that filter light, (2) variations in photoreceptor type and size to vary absorbance and sensitivity, and (3) changes in photoreceptor visual pigments to optimize peak sensitivity. The visual pigment changes can result from changes in chromophore or changes to the opsin. Opsin variation results from changes in opsin sequence, opsin expression or co-expression, and opsin gene duplications and losses. Here, we review visual diversity in a number of teleost groups where the structural and molecular mechanisms underlying their spectral sensitivities have been relatively well determined. Although we document considerable variability, this alone does not imply functional difference per se. We therefore highlight the need for more studies that examine species with known sensitivity differences, emphasizing behavioral experiments to test whether such differences actually matter in the execution of visual tasks that are relevant to the fish.
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Affiliation(s)
- Karen L Carleton
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | | | - Sara M Stieb
- Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland
- Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - Fabio Cortesi
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
| | - N Justin Marshall
- Queensland Brain Institute, University of Queensland, Brisbane 4072 QLD, Australia
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7
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Kondrashev S, Lamash N. Unusual A1/A2–visual pigment conversion during light/dark adaptation in marine fish. Comp Biochem Physiol A Mol Integr Physiol 2019; 238:110560. [DOI: 10.1016/j.cbpa.2019.110560] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 07/24/2019] [Accepted: 08/29/2019] [Indexed: 10/26/2022]
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Abstract
Ensuring the clarity of the ocular surface of fish species with which we interact is of great importance. There is still much more to learn about the ocular surface of fish species. A better understanding of the anatomy, physiology, and pathology of the ocular surface is thus vital for fish welfare, as well as being a fascinating subject in its own right.
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Affiliation(s)
- David L Williams
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK.
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Puzzolo D, Pisani A, Malta C, Santoro G, Meduri A, Abbate F, Montalbano G, Wylegala E, Rana RA, Bucchieri F, Ieni A, Aragona P, Micali A. Structural, ultrastructural, and morphometric study of the zebrafish ocular surface: a model for human corneal diseases? Curr Eye Res 2017; 43:175-185. [PMID: 29111817 DOI: 10.1080/02713683.2017.1385087] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE A morphological and morphometric study of the adult zebrafish ocular surface was performed to provide a comprehensive description of its parts and to evaluate its similarity to the human. MATERIALS AND METHODS The eyes of adult zebrafish were processed for light, transmission and scanning electron microscopy, and for immunohistochemical stain of corneal nerves; a morphometric analysis was also performed on several morphological parameters. RESULTS The corneal epithelium was formed by five layers of cells. No Bowman's layer could be demonstrated. The stroma consisted of lamellae of different thickness with few keratocytes. The Descemet's membrane was absent as the flat and polygonal endothelial cells directly adhered to the deepest corneal lamella. The immunohistochemical stain of neurofilaments failed to demonstrate corneal nerve fibers. The conjunctival epithelium was stratified, overlying the stroma formed by a subepithelial and a deep layer, this latter connected to the scleral cartilage. In the peripheral cornea and in the conjunctiva, many goblet and rodlet cells were observed. The morphometric analysis showed that the peripheral cornea epithelium was thicker when compared to the other parts of the ocular surface, with smaller superficial cells. Desmosomes and hemidesmosomes in the conjunctiva were significantly fewer in number than the other parts of the ocular surface. The stroma was thinner in the conjunctiva than in the cornea, while corneal lamellae were thicker in the intermediate stroma. CONCLUSIONS The zebrafish ocular surface showed significant differences compared to the human, such as the absence of Bowman's layer, Descemet's membrane and corneal nerve fibers, the reduced stromal thickness, and the presence of rodlet cells. On the basis of these original findings, it is suggested that the use of the zebrafish as a model for studying normal or pathological human corneas should be undertaken with particular caution.
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Affiliation(s)
- Domenico Puzzolo
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
| | - Antonina Pisani
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
| | - Consuelo Malta
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
| | - Giuseppe Santoro
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
| | - Alessandro Meduri
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
| | - Francesco Abbate
- b Department of Veterinary Sciences, Laboratory of Zebrafish Neuromorphology , University of Messina , Messina , Italy
| | - Giuseppe Montalbano
- b Department of Veterinary Sciences, Laboratory of Zebrafish Neuromorphology , University of Messina , Messina , Italy
| | - Edward Wylegala
- c Clinical Department of Ophthalmology, School of Medicine with the Division of Dentistry in Zabrze , Medical University of Silesia , Katowice , Poland
| | - Rosa Alba Rana
- d Department of Medicine and Science of Aging , University of Chieti , Chieti , Italy
| | - Fabio Bucchieri
- e Department of Experimental Medicine, Section of Anatomy , University of Palermo , Palermo , Italy
| | - Antonio Ieni
- f Department of Human Pathology , University of Messina , Messina , Italy
| | - Pasquale Aragona
- g Department of Biomedical Sciences, Regional Referral Center for the Ocular Surface Diseases , University of Messina , Messina , Italy
| | - Antonio Micali
- a Department of Biomedical Sciences , University of Messina , Messina , Italy
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de Busserolles F, Hart NS, Hunt DM, Davies WI, Marshall NJ, Clarke MW, Hahne D, Collin SP. Spectral Tuning in the Eyes of Deep-Sea Lanternfishes (Myctophidae): A Novel Sexually Dimorphic Intra-Ocular Filter. BRAIN, BEHAVIOR AND EVOLUTION 2015; 85:77-93. [DOI: 10.1159/000371652] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 09/15/2014] [Indexed: 11/19/2022]
Abstract
Deep-sea fishes possess several adaptations to facilitate vision where light detection is pushed to its limit. Lanternfishes (Myctophidae), one of the world's most abundant groups of mesopelagic fishes, possess a novel and unique visual specialisation, a sexually dimorphic photostable yellow pigmentation, constituting the first record of a visual sexual dimorphism in any non-primate vertebrate. The topographic distribution of the yellow pigmentation across the retina is species specific, varying in location, shape and size. Spectrophotometric analyses reveal that this new retinal specialisation differs between species in terms of composition and acts as a filter, absorbing maximally between 356 and 443 nm. Microspectrophotometry and molecular analyses indicate that the species containing this pigmentation also possess at least 2 spectrally distinct rod visual pigments as a result of a duplication of the Rh1 opsin gene. After modelling the effect of the yellow pigmentation on photoreceptor spectral sensitivity, we suggest that this unique specialisation acts as a filter to enhance contrast, thereby improving the detection of bioluminescent emissions and possibly fluorescence in the extreme environment of the deep sea. The fact that this yellow pigmentation is species specific, sexually dimorphic and isolated within specific parts of the retina indicates an evolutionary pressure to visualise prey/predators/mates in a particular part of each species' visual field.
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11
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Talbot C, Jordan TM, Roberts NW, Collin SP, Marshall NJ, Temple SE. Corneal microprojections in coleoid cephalopods. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2012; 198:849-56. [PMID: 22983438 DOI: 10.1007/s00359-012-0755-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 08/23/2012] [Accepted: 08/27/2012] [Indexed: 10/27/2022]
Abstract
The cornea is the first optical element in the path of light entering the eye, playing a role in image formation and protection. Corneas of vertebrate simple camera-type eyes possess microprojections on the outer surface in the form of microridges, microvilli, and microplicae. Corneas of invertebrates, which have simple or compound eyes, or both, may be featureless or may possess microprojections in the form of nipples. It was previously unknown whether cephalopods (invertebrates with camera-type eyes like vertebrates) possess corneal microprojections and, if so, of what form. Using scanning electron microscopy, we examined corneas of a range of cephalopods and discovered nipple-like microprojections in all species. In some species, nipples were like those described on arthropod compound eyes, with a regular hexagonal arrangement and sizes ranging from 75 to 103 nm in diameter. In others, nipples were nodule shaped and irregularly distributed. Although terrestrial invertebrate nipples create an antireflective surface that may play a role in camouflage, no such optical function can be assigned to cephalopod nipples due to refractive index similarities of corneas and water. Their function may be to increase surface-area-to-volume ratio of corneal epithelial cells to increase nutrient, gas, and metabolite exchange, and/or stabilize the corneal mucous layer, as proposed for corneal microprojections of vertebrates.
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Affiliation(s)
- Christopher Talbot
- Sensory Neurobiology Group, Queensland Brain Institute and School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD, 4072, Australia
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12
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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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13
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Collin SP, Davies WL, Hart NS, Hunt DM. The evolution of early vertebrate photoreceptors. Philos Trans R Soc Lond B Biol Sci 2009; 364:2925-40. [PMID: 19720654 PMCID: PMC2781863 DOI: 10.1098/rstb.2009.0099] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these 'living fossils', we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.
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Affiliation(s)
- Shaun P Collin
- School of Biomedical Sciences, The University of Queensland, Brisbane 4072, Queensland, Australia.
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14
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Feathers with Ocular Architecture: Implications for Functional and Evolutionary Similarities of Visual Signals and Receptors. Evol Biol 2009. [DOI: 10.1007/s11692-009-9059-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Doucet SM, Meadows MG. Iridescence: a functional perspective. J R Soc Interface 2009; 6 Suppl 2:S115-32. [PMID: 19336344 PMCID: PMC2706478 DOI: 10.1098/rsif.2008.0395.focus] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 01/09/2009] [Accepted: 01/12/2009] [Indexed: 11/12/2022] Open
Abstract
In animals, iridescence is generated by the interaction of light with biological tissues that are nanostructured to produce thin films or diffraction gratings. Uniquely among animal visual signals, the study of iridescent coloration contributes to biological and physical sciences by enhancing our understanding of the evolution of communication strategies, and by providing insights into physical optics and inspiring biomimetic technologies useful to humans. Iridescent colours are found in a broad diversity of animal taxa ranging from diminutive marine copepods to terrestrial insects and birds. Iridescent coloration has received a surge of research interest of late, and studies have focused on both characterizing the nanostructures responsible for producing iridescence and identifying the behavioural functions of iridescent colours. In this paper, we begin with a brief description of colour production mechanisms in animals and provide a general overview of the taxonomic distribution of iridescent colours. We then highlight unique properties of iridescent signals and review the proposed functions of iridescent coloration, focusing, in particular, on the ways in which iridescent colours allow animals to communicate with conspecifics and avoid predators. We conclude with a brief overview of non-communicative functions of iridescence in animals. Despite the vast amount of recent work on animal iridescence, our review reveals that many proposed functions of iridescent coloration remain virtually unexplored, and this area is clearly ripe for future research.
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Affiliation(s)
- Stéphanie M Doucet
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada N9B 3P4.
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Long-wave sensitivity in the masked greenling (Hexagrammos octogrammus), a shallow-water marine fish. Vision Res 2008; 48:2269-74. [PMID: 18675840 DOI: 10.1016/j.visres.2008.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2008] [Revised: 06/05/2008] [Accepted: 07/04/2008] [Indexed: 11/22/2022]
Abstract
Microspectrophotometry (MSP) revealed that surprisingly for a "fully marine" species, in summer, photoreceptors of the nearshore scorpaeniform fish known as the masked greenling, Hexagrammos octogrammus, contained exclusively, or presumably, porphyropsin with a small admixture of rhodopsin. As a result of this, the lambda(max) of the spectral sensitivity of the photoreceptors were significantly shifted to longer wavelengths as compared to the lambda(max) typical of marine shallow-water fishes, showing about 530 nm for rods and single cones, and 570/625 nm for double-cone members. These unique spectral shifts would permit a cone-driven wavelength discrimination in spite of high-density orange corneal filters which block light at lower wavelengths.
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Bailes HJ, Trezise AEO, Collin SP. The optics of the growing lungfish eye: Lens shape, focal ratio and pupillary movements inNeoceratodus forsteri(Krefft, 1870). Vis Neurosci 2007; 24:377-87. [PMID: 17822577 DOI: 10.1017/s0952523807070381] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Accepted: 04/12/2007] [Indexed: 11/07/2022]
Abstract
Lungfish (order Dipnoi) evolved during the Devonian period and are believed to be the closest living relatives to the land vertebrates. Here we describe the previously unknown morphology of the lungfish eye in order to examine ocular adaptations present in early sarcopterygian fish. Unlike many teleosts, the Australian lungfishNeoceratodus forsteripossesses a mobile pupil with a slow pupillary response similar to amphibians. The structure of the eye changes from juvenile to adult, with both eye and lens becoming more elliptical in shape with growth. This change in structure results in a decrease in focal ratio (the distance from lens center to the retina divided by the lens radius) and increased retinal illumination in adult fish. Despite a degree of lenticular correction for spherical aberration, there is considerable variation across the lens. A re-calculation of spatial resolving power using measured focal ratios from cryosectioning reveals a low ability to discriminate fine detail. The dipnoan eye shares more features with amphibian eyes than with most teleost eyes, which may echo the visual needs of this living fossil.
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Affiliation(s)
- Helena J Bailes
- School of Biomedical Sciences, The University of Queensland, St Lucia, Brisbane, QLD 4072, Australia.
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Siebeck UE, Marshall NJ. Potential ultraviolet vision in pre-settlement larvae and settled reef fish—A comparison across 23 families. Vision Res 2007; 47:2337-52. [PMID: 17632200 DOI: 10.1016/j.visres.2007.05.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2007] [Revised: 05/18/2007] [Accepted: 05/23/2007] [Indexed: 10/23/2022]
Abstract
After hatching, larvae of coral reef fishes experience a pelagic phase during which they are diurnal planktivores. It has been suggested that ultraviolet (UV) vision is beneficial for the detection of planktonic prey. Aims were therefore to investigate whether ocular media of pre-settlement reef fish differ from those of respective adults, and whether larvae have UV-transparent ocular media required for UV vision. The ocular media of 84 pre-settlement and 98 adult species belonging to the same families were measured and compared. We suggest that adult lifestyle rather than planktivory in general shapes the ocular media properties of pre-settlement larvae.
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Affiliation(s)
- U E Siebeck
- Vision Touch and Hearing Research Laboratory, School of Biomedical Sciences, University of Queensland, St. Lucia 4072, Australia.
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