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https://www.readbyqxmd.com/read/28212859/docosahexaenoic-acid-phospholipid-differentially-modulates-the-conformation-of-g90v-and-n55k-rhodopsin-mutants-associated-with-retinitis-pigmentosa
#1
Xiaoyun Dong, María Guadalupe Herrera-Hernández, Eva Ramon, Pere Garriga
Rhodopsin is the visual photoreceptor of the retinal rod cells that mediates dim light vision and a prototypical member of the G protein-coupled receptor superfamily. The structural stability and functional performance of rhodopsin are modulated by membrane lipids. Docosahexaenoic acid has been shown to interact with native rhodopsin but no direct evidence has been established on the effect of such lipid on the stability and regeneration of rhodopsin mutants associated with retinal diseases. The stability and regeneration of two thermosensitive mutants G90V and N55K, associated with the retinal degenerative disease retinitis pigmentosa, have been analyzed in docosohexaenoic phospholipid (1,2-didocosa-hexaenoyl-sn-glycero-3-phosphocholine; DDHA-PC) liposomes...
February 14, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28212707/astrobiological-implications-of-dim-light-phototrophy-in-deep-sea-red-clays
#2
Anindita Das, Tanya Singh, P A LokaBharathi, Prashant K Dhakephalkar, Sweta Mallik, Pranav R Kshirsagar, N H Khadge, B Nagender Nath, Satadru Bhattacharya, Aditya Kumar Dagar, Prabhjot Kaur, Dwijesh Ray, Anil D Shukla, Christabelle E G Fernandes, Sheryl O Fernandes, Tresa Remya A Thomas, Mamatha S S, Babu Shashikant Mourya, Ram Murti Meena
Red clays of Central Indian Basin (CIB) under influence of trace of Rodriguez Triple Junction exhibited chemoautotrophy, low temperature hydrothermal alterations and photoautotrophic potential. Seamount flank TVBC-08, hosting such signatures revealed dominance of aerobic anoxygenic phototroph Erythrobacter, with 93% of total 454 pyrosequencing tags. Subsequently, enrichments for both aerobic (Erythrobacter) and anaerobic anoxygenic phototrophs (green and purple sulphur bacteria) under red and white LED light illumination, with average irradiance 30...
February 2017: Life Sciences in Space Research
https://www.readbyqxmd.com/read/28209805/effects-of-photophase-illuminance-on-locomotor-activity-urine-production-and-urinary-6-sulfatoxymelatonin-in-nocturnal-and-diurnal-south-african-rodents
#3
Ingrid van der Merwe, Maria K Oosthuizen, Andre Ganswindt, Abraham Haim, Nigel C Bennett
Effects of photophase illuminance (1, 10, 100 and 330 lux of white incandescent lighting) on daily rhythms of locomotor activity, urine production and 6-sulfatoxymelatonin (6-SMT; 10 lux vs. 330 lux) were studied in nocturnal Namaqua rock mice (Micaelamys namaquensis) and diurnal four striped field mice (Rhabdomys pumilio). Micaelamys namaquensis was consistently nocturnal (∼90-94% nocturnal activity), whereas considerable individual variation marked activity profiles in R. pumilio, but with activity mostly pronounced around twilight (∼55-66% diurnal activity)...
February 16, 2017: Journal of Experimental Biology
https://www.readbyqxmd.com/read/28199005/specialized-photoreceptor-composition-in-the-raptor-fovea
#4
Mindaugas Mitkus, Peter Olsson, Matthew B Toomey, Joseph C Corbo, Almut Kelber
The retinae of many bird species contain a depression with high photoreceptor density known as the fovea. Many species of raptors have two foveae, a deep central fovea and a shallower temporal fovea. Birds have six types of photoreceptors: rods, active in dim light, double cones that are thought to mediate achromatic discrimination, and four types of single cones mediating color vision. To maximize visual acuity, the fovea should only contain photoreceptors contributing to high-resolution vision. Interestingly, it has been suggested that raptors might lack double cones in the fovea...
February 15, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28193823/stellar-performance-mechanisms-underlying-milky-way-orientation-in-dung-beetles
#5
James J Foster, Basil El Jundi, Jochen Smolka, Lana Khaldy, Dan-Eric Nilsson, Marcus J Byrne, Marie Dacke
Nocturnal dung beetles (Scarabaeus satyrus) are currently the only animals that have been demonstrated to use the Milky Way for reliable orientation. In this study, we tested the capacity of S. satyrus to orient under a range of artificial celestial cues, and compared the properties of these cues with images of the Milky Way simulated for a beetle's visual system. We find that the mechanism that permits accurate stellar orientation under the Milky Way is based on an intensity comparison between different regions of the Milky Way...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193822/comparative-system-identification-of-flower-tracking-performance-in-three-hawkmoth-species-reveals-adaptations-for-dim-light-vision
#6
Anna L Stöckl, Klara Kihlström, Steven Chandler, Simon Sponberg
Flight control in insects is heavily dependent on vision. Thus, in dim light, the decreased reliability of visual signal detection also prompts consequences for insect flight. We have an emerging understanding of the neural mechanisms that different species employ to adapt the visual system to low light. However, much less explored are comparative analyses of how low light affects the flight behaviour of insect species, and the corresponding links between physiological adaptations and behaviour. We investigated whether the flower tracking behaviour of three hawkmoth species with different diel activity patterns revealed luminance-dependent adaptations, using a system identification approach...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193821/insect-photoreceptor-adaptations-to-night-vision
#7
REVIEW
Anna Honkanen, Esa-Ville Immonen, Iikka Salmela, Kyösti Heimonen, Matti Weckström
Night vision is ultimately about extracting information from a noisy visual input. Several species of nocturnal insects exhibit complex visually guided behaviour in conditions where most animals are practically blind. The compound eyes of nocturnal insects produce strong responses to single photons and process them into meaningful neural signals, which are amplified by specialized neuroanatomical structures. While a lot is known about the light responses and the anatomical structures that promote pooling of responses to increase sensitivity, there is still a dearth of knowledge on the physiology of night vision...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193820/functional-preservation-and-variation-in-the-cone-opsin-genes-of-nocturnal-tarsiers
#8
Gillian L Moritz, Perry S Ong, George H Perry, Nathaniel J Dominy
The short-wavelength sensitive (S-) opsin gene OPN1SW is pseudogenized in some nocturnal primates and retained in others, enabling dichromatic colour vision. Debate on the functional significance of this variation has focused on dark conditions, yet many nocturnal species initiate activity under dim (mesopic) light levels that can support colour vision. Tarsiers are nocturnal, twilight-active primates and exemplary visual predators; they also express different colour vision phenotypes, raising the possibility of discrete adaptations to mesopic conditions...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193819/the-evolution-of-rod-photoreceptors
#9
REVIEW
Ala Morshedian, Gordon L Fain
Photoreceptors in animals are generally of two kinds: the ciliary or c-type and the rhabdomeric or r-type. Although ciliary photoreceptors are found in many phyla, vertebrates seem to be unique in having two distinct kinds which together span the entire range of vision, from single photons to bright light. We ask why the principal photoreceptors of vertebrates are ciliary and not rhabdomeric, and how rods evolved from less sensitive cone-like photoreceptors to produce our duplex retina. We suggest that the principal advantage of vertebrate ciliary receptors is that they use less ATP than rhabdomeric photoreceptors...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193818/processing-of-single-photon-responses-in-the-mammalian-on-and-off-retinal-pathways-at-the-sensitivity-limit-of-vision
#10
Daisuke Takeshita, Lina Smeds, Petri Ala-Laurila
Visually guided behaviour at its sensitivity limit relies on single-photon responses originating in a small number of rod photoreceptors. For decades, researchers have debated the neural mechanisms and noise sources that underlie this striking sensitivity. To address this question, we need to understand the constraints arising from the retinal output signals provided by distinct retinal ganglion cell types. It has recently been shown in the primate retina that On and Off parasol ganglion cells, the cell types likely to underlie light detection at the absolute visual threshold, differ fundamentally not only in response polarity, but also in the way they handle single-photon responses originating in rods...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193817/behavioural-and-physiological-limits-to-vision-in-mammals
#11
REVIEW
Greg D Field, Alapakkam P Sampath
Human vision is exquisitely sensitive-a dark-adapted observer is capable of reliably detecting the absorption of a few quanta of light. Such sensitivity requires that the sensory receptors of the retina, rod photoreceptors, generate a reliable signal when single photons are absorbed. In addition, the retina must be able to extract this information and relay it to higher visual centres under conditions where very few rods signal single-photon responses while the majority generate only noise. Critical to signal transmission are mechanistic optimizations within rods and their dedicated retinal circuits that enhance the discriminability of single-photon responses by mitigating photoreceptor and synaptic noise...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193816/ontogenetic-adaptations-in-the-visual-systems-of-deep-sea-crustaceans
#12
Tamara M Frank
For all visually competent organisms, the driving force behind the adaptation of photoreceptors involves obtaining the best balance of resolution to sensitivity in the prevailing light regime, as an increase in sensitivity often results in a decrease in resolution. A number of marine species have an additional problem to deal with, in that the juvenile stages live in relatively brightly lit shallow (100-200 m depth) waters, whereas the adult stages have daytime depths of more than 600 m, where little downwelling light remains...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193815/seeing-in-the-deep-sea-visual-adaptations-in-lanternfishes
#13
REVIEW
Fanny de Busserolles, N Justin Marshall
Ecological and behavioural constraints play a major role in shaping the visual system of different organisms. In the mesopelagic zone of the deep- sea, between 200 and 1000 m, very low intensities of downwelling light remain, creating one of the dimmest habitats in the world. This ambient light is, however, enhanced by a multitude of bioluminescent signals emitted by its inhabitants, but these are generally dim and intermittent. As a result, the visual system of mesopelagic organisms has been pushed to its sensitivity limits in order to function in this extreme environment...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193814/two-eyes-for-two-purposes-in-situ-evidence-for-asymmetric-vision-in-the-cockeyed-squids-histioteuthis-heteropsis-and-stigmatoteuthis-dofleini
#14
Kate N Thomas, Bruce H Robison, Sönke Johnsen
The light environment of the mesopelagic realm of the ocean changes with both depth and viewer orientation, and this has probably driven the high diversity of visual adaptations found among its inhabitants. The mesopelagic 'cockeyed' squids of family Histioteuthidae have unusual eyes, as the left and right eyes are dimorphic in size, shape and sometimes lens pigmentation. This dimorphism may be an adaptation to the two different sources of light in the mesopelagic realm, with the large eye oriented upward to view objects silhouetted against the dim, downwelling sunlight and the small eye oriented slightly downward to view bioluminescent point sources...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193813/subtle-changes-in-the-landmark-panorama-disrupt-visual-navigation-in-a-nocturnal-bull-ant
#15
Ajay Narendra, Fiorella Ramirez-Esquivel
The ability of ants to navigate when the visual landmark information is altered has often been tested by creating large and artificial discrepancies in their visual environment. Here, we had an opportunity to slightly modify the natural visual environment around the nest of the nocturnal bull ant Myrmecia pyriformis We achieved this by felling three dead trees, two located along the typical route followed by the foragers of that particular nest and one in a direction perpendicular to their foraging direction...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193812/coping-with-copepods-do-right-whales-eubalaena-glacialis-forage-visually-in-dark-waters
#16
Thomas W Cronin, Jeffry I Fasick, Lorian E Schweikert, Sönke Johnsen, Lorren J Kezmoh, Mark F Baumgartner
North Atlantic right whales (Eubalaena glacialis) feed during the spring and early summer in marine waters off the northeast coast of North America. Their food primarily consists of planktonic copepods, Calanus finmarchicus, which they consume in large numbers by ram filter feeding. The coastal waters where these whales forage are turbid, but they successfully locate copepod swarms during the day at depths exceeding 100 m, where light is very dim and copepod patches may be difficult to see. Using models of E...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193811/the-dual-rod-system-of-amphibians-supports-colour-discrimination-at-the-absolute-visual-threshold
#17
Carola A M Yovanovich, Sanna M Koskela, Noora Nevala, Sergei L Kondrashev, Almut Kelber, Kristian Donner
The presence of two spectrally different kinds of rod photoreceptors in amphibians has been hypothesized to enable purely rod-based colour vision at very low light levels. The hypothesis has never been properly tested, so we performed three behavioural experiments at different light intensities with toads (Bufo) and frogs (Rana) to determine the thresholds for colour discrimination. The thresholds of toads were different in mate choice and prey-catching tasks, suggesting that the differential sensitivities of different spectral cone types as well as task-specific factors set limits for the use of colour in these behavioural contexts...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193810/thresholds-and-noise-limitations-of-colour-vision-in-dim-light
#18
REVIEW
Almut Kelber, Carola Yovanovich, Peter Olsson
Colour discrimination is based on opponent photoreceptor interactions, and limited by receptor noise. In dim light, photon shot noise impairs colour vision, and in vertebrates, the absolute threshold of colour vision is set by dark noise in cones. Nocturnal insects (e.g. moths and nocturnal bees) and vertebrates lacking rods (geckos) have adaptations to reduce receptor noise and use chromatic vision even in very dim light. In contrast, vertebrates with duplex retinae use colour-blind rod vision when noisy cone signals become unreliable, and their transition from cone- to rod-based vision is marked by the Purkinje shift...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193809/living-in-the-dark-does-not-mean-a-blind-life-bird-and-mammal-visual-communication-in-dim-light
#19
REVIEW
Vincenzo Penteriani, María Del Mar Delgado
For many years, it was believed that bird and mammal communication 'in the dark of the night' relied exclusively on vocal and chemical signalling. However, in recent decades, several case studies have conveyed the idea that the nocturnal world is rich in visual information. Clearly, a visual signal needs a source of light to work, but diurnal light (twilight included, i.e. any light directly dependent on the sun) is not the only source of luminosity on this planet. Actually, moonlight represents a powerful source of illumination that cannot be neglected from the perspective of visual communication...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28193808/the-remarkable-visual-capacities-of-nocturnal-insects-vision-at-the-limits-with-small-eyes-and-tiny-brains
#20
REVIEW
Eric J Warrant
Nocturnal insects have evolved remarkable visual capacities, despite small eyes and tiny brains. They can see colour, control flight and land, react to faint movements in their environment, navigate using dim celestial cues and find their way home after a long and tortuous foraging trip using learned visual landmarks. These impressive visual abilities occur at light levels when only a trickle of photons are being absorbed by each photoreceptor, begging the question of how the visual system nonetheless generates the reliable signals needed to steer behaviour...
April 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
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