A complex system of ligaments and a muscle keep the crystalline lens in place in the eyes of bony fishes (teleosts)

Khorramshahi, Omid; Schartau, J. Marcus; Kröger, Ronald H. H.

doi:10.1016/j.visres.2008.03.017

Cited by 26 publications

(31 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Also in contrast to mammalian lenses, in which accommodation is achieved by shape change, in the teleost eye accommodation is achieved by movement of the lens toward or away from the retina (28). The lens is held firmly in place by a number of suspensory ligaments attached to the lens capsule (24) and is pulled backward against the resistance of the vitreous humor by the lens muscle. It can be argued that the relatively rigid nature of the teleost lens is a consequence of this mechanism, as shape distortion when the lens is pulled by the lens muscle would cause unwanted errors in accommodation.…”

Section: Discussionmentioning

confidence: 99%

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

Rhodes

Breck²,

Waagbø³

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

-Volume homeostasis is essential for the preservation of lens transparency and this is of particular significance to anadromous fish species where migration from freshwater to seawater presents severe osmotic challenges. In Atlantic salmon (Salmo salar L.), aqueous humor (AH) osmolality is greater in fish acclimated to seawater compared with young freshwater fish, and levels of lens N-acetylhistidine (NAH) are much higher in seawater fish. Here we investigate NAH as an osmolyte in the lenses of salmon receiving diets either with or without histidine supplementation. In the histidine-supplemented diet (HD) histidine content was 14.2 g/kg, and in the control diet (CD) histidine content was 8.9 g/kg. A transient increase in AH osmolality of 20 mmol/kg was observed in fish transferred from freshwater to seawater. In a lens culture model, temporary decreases in volume and transparency were observed when lenses were exposed to hyperosmotic conditions. A positive linear relationship between extracellular osmolality and lens NAH content was also observed, whereas there was no change in lens histidine content. Hypoosmotic exposure stimulated [ 14 C]-histidine efflux by 9.2-and 2.6-fold in CD and HD lenses, respectively. NAH efflux, measured by HPLC, was stimulated by hypoosmotic exposure to a much greater extent in HD lenses. In vivo, lens NAH increased in response to elevated AH osmolality in HD but not CD fish. In conclusion, NAH has an important and novel role as a compatible osmolyte in salmon lens. Furthermore, it is the major osmolyte that balances increases in AH osmolality when fish move from freshwater to seawater. A deficiency in NAH would lead to a dysfunction of the normal osmoregulatory processes in the lens, and we propose that this would contribute to cataract formation in fish deficient in histidine. histidine PREVALENCE OF CATARACT IN farmed Atlantic salmon (Salmo salar L.) has increased in recent years (3) and this has been linked to the removal of a rich source of dietary histidine (blood meal) (7). Several recent studies have investigated the possible causes of cataract in farmed salmon (6, 9, 30), although the mechanisms involved remain to be elucidated.Osmotic stress has been shown to contribute to cataract formation in multiple species, including man (19). Efficient volume regulation is crucial for the maintenance of lens transparency and disruption to the tightly packed and highly ordered cells and proteins that make up the lens will cause a loss of lens transparency. In fish there are numerous examples where osmotic factors have been shown to play a role in cataract development (20), and the anadromous life cycle of the Atlantic salmon exposes the fish to particularly severe osmotic stress. The early part of salmon development is spent in freshwater as parr followed by transformation to smolts before entering the sea. Despite the physiological changes associated with parr-smolt transformation, a preadaption for life in seawater, reversible osmotic cataracts, are commonly described immediately aft...

show abstract

Section: Discussionmentioning

confidence: 99%

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

Rhodes

Breck²,

Waagbø³

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

View full text Add to dashboard Cite

show abstract

“…These include the following: (1) the position and shape of the optic nerve head, including multiple Sharma, 1987, 1988] and elongated [Collin et al, 2000] optic nerve heads; (2) any remaining scars due to the healing (or partial healing) of the embryonic fissure or falciform process [Collin and Pettigrew, 1988a]; (3) the shape and depth of any foveal pit or depression in the retina [Collin and Collin, 1999;Collin et al, 2000;Moroney and Pettigrew, 1987;Wood, 1917]; (4) retinal thickening(s) across the retinal meridian typically indicating the position of one or more horizontal/visual streaks [Munk, 1970]); (5) differences in the size, shape and attachment of the lens [Gustafsson et al, 2010;Khorramshahi et al, 2008]; (6) the presence or absence of vitreal vascularization, a conus or a pecten [Collin, 1989a;Hanyu, 1962;Nguyen, 1970;Smith et al, 1996;Yu et al, 2009], and (7) colored eye shine produced by any tapetal material underlying the retina to increase visual sensitivity [Braekevelt, 1986[Braekevelt, , 1990Collin and Collin, 1993;Nicol, 1981]. The presence of these morphological and, in many cases, species-or taxon-specific variables presents technical difficulties.…”

Section: Discussionmentioning

confidence: 99%

The Retinal Wholemount Technique: A Window to Understanding the Brain and Behaviour

et al. 2011

View full text Add to dashboard Cite

The accessibility of the vertebrate retina has provided the opportunity to assess various parameters of the visual abilities of a range of species. This thin but complex extension of the brain achieves a large proportion of the necessary visual processing of an optical image before information is delivered to the brain as neural impulses. Studies of the retina as a wholemount or a flattened sheet of neural tissue are abundant due to the large amount of information that can be analysed, as follows: the level of summation or convergence; the coverage, stratification and potential sites of synaptic connections; the spatial resolving power; the arrangement of neuronal arrays or mosaics; electrophysiological access for the recording of responses to visual stimuli; the spatial arrangement of cell dendritic fields; location of retinal ‘blind spots’ (optic nerve, falciform process and pecten); topographic differences in retinal cell sampling; spectral filters, and reflective structures. The present study examines all aspects of the wholemount technique, including enucleation, fixation, retinal extraction, flattening, staining, visualization of labelled cells and stereological mapping of cell density. Uniquely, it highlights the crucial technical and often species-specific differences encountered when examining a range of vertebrate taxa (fishes, reptiles, birds and mammals). This broad comparative approach will enable future studies to overcome technical difficulties, thus permitting larger conceptual questions to be posed regarding the diversity of visual tasks across phylogenetic boundaries.

show abstract

“…Estas agr upaciones presentan numerosas interdigitaciones citoplasmáticas, denominadas uniones "Ball-and-socket" (Blankenship et al 2007), también han sido descritas para primates no humanos (Dickson & Crock 1972), conejos (Al-khudari et al 2007), ratones (Blankenship et al 2007) y humanos (AlGhoul, et al 2003), donde se reporta que están encargadas de unir, compactar y estabilizar las fi bras del cristalino durante la acomodación (Blankenship et al 2007). Las regiones laterales del cristalino de los peces necesitan mayor estabilidad estructural porque están asociadas a movimientos de translación y rotación llevados a cabo durante la acomodación (Khorramshahi et al 2008).…”

Section: Discussionunclassified

“…Luego de atravesar la córnea, los haces de luz son seleccionados por el iris (Munz 1971) y dirigidos hacia el cristalino, que es una estr uctura esférica transparente encargada de enfocar los fotones en la retina. Esta estr uctura se encuentra sopor tada por un complejo sistema de ligamentos y músculos (Khorramshahi et al 2008). La retina es un tejido neuroepitelial derivado de las estructuras internas y externas de la cúpula óptica, especializada en la captura, interpretación y transmisión de información desde el ambiente hacia el cerebro (Collin & Shand 2003).…”

Section: Introductionunclassified

Descripción histológica del ojo de Panaque nigrolineatus (Siluriformes: Loricariidae) y sus implicaciones ecomorfológicas

Corchuelo

Caldas

Peña³

et al. 2012

Rev. chil. hist. nat.

View full text Add to dashboard Cite

RESUMENLa cucha real (Panaque nigrolineatus) es endémica de las cuencas del Orinoco y Amazonas. La información relacionada con el sistema visual de esta especie es muy escasa, a pesar de ser un sentido fundamental en la interacción del individuo con su ambiente. Los especímenes se clasifi caron en dos grupos en base a su tamaño corporal: pequeños (longitud estándar (media ± DE) de 5.92 ± 1.43 cm y peso promedio de 8.50 ± 6.8 g) y grandes (longitud estándar (media ± DE) de 15.9 ± 0.69 cm y peso promedio de 142.48 ± 18.71 g). En los ejemplares pequeños, el ojo presentó una morfología redondeada, y en los de mayor tamaño presentó una morfología ligeramente alargada. Se obtuvieron cortes histológicos de 7 µm que fueron coloreados con las técnicas H&E y Orceína. El tamaño relativo del ojo fue mayor en los ejemplares pequeños (6.46 %) que en los de mayor tamaño (4.55 %). El espesor de la córnea de los grupos evaluados, presentó variaciones morfométricas signifi cativas, entre su espesor central y periférico. La esclera presentó tejido conectivo denso. Los individuos de mayor tamaño corporal tienen una esclera signifi cativamente más gruesa tanto en la región lateral como en la región posterior. Algo similar ocurre con el espesor del iris. La pupila presentó morfología omega. En el cristalino fueron evidenciadas interdigitaciones celulares ubicadas en las regiones laterales. La retina de P. nigrolineatus está compuesta por siete capas. No existen diferencias signifi cativas entre el espesor de la retina de los dos grupos evaluados de P. nigrolineatus. Se observaron de 10 a 12 papilas del nervio óptico en la retina de P. nigrolineatus cuyo diámetro oscila entre 24.57 y 131.90 µm. Teniendo en cuenta el análisis histológico y morfométrico del ojo de P. nigrolineatus, esta especie presenta adaptaciones orientadas a suplir los requerimientos visuales de organismos bentónicos que habitan ecosistemas con cuerpos de agua turbios, de baja luminosidad, corrientes rápidas y estructuralmente complejos.Palabras clave: Colombia, ecomorfología, papilas de nervio óptico, sistema visual. ABSTRACTRoyal pleco (Panaque nigrolineatus) is endemic from the Orinoco and Amazon basins. Information related to the visual system of this fi sh is scant, despite this sense is essential to the interactions with the environment. Specimens were classifi ed into two groups based on their weight and standard length: small (standard length (mean ± SD) of 5.92 ± 1.43 cm and average weight (± SD) 8.50 ± 6.8 g) and large (standard length (mean ± SD) of 15.9 ± 0.69 cm and average weight (± SD) 142.48 ± 18.71 g). The eye of small individuals had a rounded morphology in contrast with the slightly elongated morphology of large individuals. Seven µm histological sections were obtained and stained with H&E and Orcein techniques. Relative size of the eye was higher in small individuals (6.46 %) than in larger (4.55 %). Corneal central and peripheral thickness presented signifi cant morphometric differences, in both groups. The sclera is composed of dense connective...

show abstract

A complex system of ligaments and a muscle keep the crystalline lens in place in the eyes of bony fishes (teleosts)

Cited by 26 publications

References 21 publications

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

N-acetylhistidine, a novel osmolyte in the lens of Atlantic salmon (Salmo salar L.)

The Retinal Wholemount Technique: A Window to Understanding the Brain and Behaviour

Descripción histológica del ojo de Panaque nigrolineatus (Siluriformes: Loricariidae) y sus implicaciones ecomorfológicas

Contact Info

Product

Resources

About