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1.
Biochemistry (Mosc) ; 87(3): 215-224, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-35526850

RESUMO

Color vision sensitivity is crucial for fish adaptation during migration and reproduction. Prolactin and prolactin-like hormone are important regulators in both these processes. We hypothesized that prolactin influences the color vision sensitivity during freshwater migrations in fish. We studied the effects of prolactin and freshwater adaptation during the spawning period on the expression of opsin genes (SWS1, SWS2, RH2, LWS) in the retina of female and male three-spined sticklebacks Gasterosteus aculeatus L. Expression of the prolactin gene increased in the brain of females, but not males, while expression of the prolactin-like hormone decreased in the brain of both male and female sticklebacks during freshwater adaptation. Expression of the SWS2 gene decreased in the retina of females and males during freshwater adaptation and after prolactin administration. Expression of the SWS1 gene decreased in the retina of male sticklebacks after prolactin administration, but not during freshwater adaptation. Expression of the RH2 and LWS genes did not depend on prolactin administration in male and female sticklebacks. We conclude that expression of some opsin genes in the retina of sticklebacks is regulated by prolactin and depends on sex and freshwater adaptation. This expands our knowledge of the adaptive effects of prolactin on fish during freshwater migrations.


Assuntos
Opsinas , Smegmamorpha , Animais , Feminino , Água Doce , Masculino , Opsinas/genética , Opsinas/metabolismo , Prolactina/genética , Prolactina/farmacologia , Retina/metabolismo , Smegmamorpha/genética , Smegmamorpha/metabolismo
2.
Nature ; 604(7905): 384-390, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35388214

RESUMO

G protein-coupled receptors (GPCRs) are cell-surface receptors that respond to various stimuli to induce signalling pathways across cell membranes. Recent progress has yielded atomic structures of key intermediates1,2 and roles for lipids in signalling3,4. However, capturing signalling events of a wild-type receptor in real time, across a native membrane to its downstream effectors, has remained elusive. Here we probe the archetypal class A GPCR, rhodopsin, directly from fragments of native disc membranes using mass spectrometry. We monitor real-time photoconversion of dark-adapted rhodopsin to opsin, delineating retinal isomerization and hydrolysis steps, and further showing that the reaction is significantly slower in its native membrane than in detergent micelles. Considering the lipids ejected with rhodopsin, we demonstrate that opsin can be regenerated in membranes through photoisomerized retinal-lipid conjugates, and we provide evidence for increased association of rhodopsin with unsaturated long-chain phosphatidylcholine during signalling. Capturing the secondary steps of the signalling cascade, we monitor light activation of transducin (Gt) through loss of GDP to generate an intermediate apo-trimeric G protein, and observe Gαt•GTP subunits interacting with PDE6 to hydrolyse cyclic GMP. We also show how rhodopsin-targeting compounds either stimulate or dampen signalling through rhodopsin-opsin and transducin signalling pathways. Our results not only reveal the effect of native lipids on rhodopsin signalling and regeneration but also enable us to propose a paradigm for GPCR drug discovery in native membrane environments.


Assuntos
Opsinas , Rodopsina , Transducina , Isomerismo , Metabolismo dos Lipídeos , Opsinas/metabolismo , Disco Óptico , Fosfatidilcolinas , Conformação Proteica , Receptores Acoplados a Proteínas G , Rodopsina/química
3.
J Neural Eng ; 19(2)2022 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-35320791

RESUMO

Objective.A fundamental challenge in optogenetics is to elicit long-term high-fidelity neuronal spiking with negligible heating. Fast channelrhodopsins (ChRs) require higher irradiances and cause spike failure due to photocurrent desensitization under sustained illumination, whereas, more light-sensitive step-function opsins (SFOs) exhibit prolonged depolarization with insufficient photocurrent and fast response for high-fidelity spiking.Approach.We present a novel method to overcome this fundamental limitation by co-expressing fast ChRs with SFOs. A detailed theoretical analysis of ChETA co-expressed with different SFOs, namely ChR2(C128A), ChR2(C128S), stabilized step-function opsin (SSFO) and step-function opsin with ultra-high light sensitivity (SOUL), expressing hippocampal neurons has been carried out by formulating their accurate theoretical models.Main results.ChETA-SFO-expressing hippocampal neurons shows more stable photocurrent that overcomes spike failure. Spiking fidelity in these neurons can be sustained even at lower irradiances of subsequent pulses (77% of initial pulse intensity in ChETA-ChR2(C128A)-expressing neurons) or by using red-shifted light pulses at appropriate intervals. High-fidelity spiking upto 60 Hz can be evoked in ChETA-ChR2(C128S), ChETA-SSFO and ChETA-SOUL-expressing neurons, which cannot be attained with only SFOs.Significance.The present study provides important insights about photostimulation protocols for bi-stable switching of neurons. This new approach provides a means for sustained low-power, high-frequency and high-fidelity optogenetic switching of neurons, necessary to study various neural functions and neurodegenerative disorders, and enhance the utility of optogenetics for biomedical applications.


Assuntos
Opsinas , Optogenética , Channelrhodopsins/genética , Modelos Teóricos , Neurônios/fisiologia , Opsinas/genética , Opsinas/metabolismo , Optogenética/métodos
4.
Gene ; 825: 146434, 2022 May 30.
Artigo em Inglês | MEDLINE | ID: mdl-35304240

RESUMO

Vision is important for fish to forage food and fishes express opsin genes to receive visual signals. Chinese perch (Siniperca chuatsi) larvae prey on other fish species larvae at firstfeeding but donoteat any zooplankton, the expression of opsin genes in S. chuatsilarvae is unknown. In this study, we conducted a whole-genome analysis and demonstrated that S. chuatsihave5cone opsin genes (sws1, sws2Aα, sws2Aß, rh2and lws)and 2 rod opsin genes (rh1and rh1-exorh). The syntenicanalysisshowedthe flanking genes ofall opsin genes were conserved during fish evolution, but the ancestorof S. chuatsimightlost some opsin gene copies duringtheevolution.The phylogeneticanalysisshowed sws1of S. chuatsiwas closest to those of Lates calcariferwhich had a truncated sws1gene; the sws2Aα, sws2Aß,lws,rh2,rh1 andrh1-exorh of S. chuatsihad a closer relationship with those of Percomorpha fishes.Importantly, results of in situhybridization showed the sws1 opsingene,which is related to forage zooplankton,had extremely low levelexpression in retinaat early stages.Surprisingly, the rh2 opsin gene had a high level expression at firstfeeding stage. The sws2Aα, sws2Aßand lwshad a little expression at early stages but the lwsshowed a increasing trend with larval development, rh1 opsin gene expression appeared at15 dph. In thisstudy, we found a specialpattern of visual opsin genes expression in S. chuatsi, it might influence the larval first feeding and feeding habit.


Assuntos
Percas , Opsinas de Bastonetes , Animais , China , Opsinas/genética , Percas/genética , Filogenia , Opsinas de Bastonetes/genética
5.
Evolution ; 76(4): 837-845, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35247267

RESUMO

Vision is critical for most vertebrates, including fish. One challenge that aquatic habitats pose is the high variability in spectral properties depending on depth and the inherent optical properties of the water. By altering opsin gene expression and chromophore usage, cichlid fish modulate visual sensitivities to maximize sensory input from the available light in their respective habitat. Thyroid hormone (TH) has been proposed to play a role in governing adaptive diversification in visual sensitivity in Nicaraguan Midas cichlids, which evolved in less than 4000 generations. As suggested by indirect measurements of TH levels (i.e., expression of deiodinases), populations adapted to short wavelength light in clear lakes have lower TH levels than ones inhabiting turbid lakes enriched in long-wavelength light. We experimentally manipulated TH levels by exposing 2-week-old Midas cichlids to exogenous TH or a TH inhibitor and measured opsin gene expression and chromophore usage (via cyp27c1 expression). Although exogenous TH induces long-wavelength sensitivity by changing opsin gene expression and chromophore usage in a concerted manner, TH-inhibited fish exhibit a visual phenotype with sensitivities shifted to shorter wavelengths. Tinkering with TH levels in eyes results in concerted phenotypic changes that can provide a rapid mechanism of adaptation to novel light environments.


Assuntos
Ciclídeos , Visão de Cores , Animais , Ciclídeos/genética , Ciclídeos/metabolismo , Opsinas/genética , Fenótipo , Hormônios Tireóideos/metabolismo
6.
J Exp Biol ; 225(7)2022 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-35244167

RESUMO

Vision is used by animals to find food and mates, avoid predators, defend resources and navigate through complex habitats. Behavioural experiments are essential for understanding animals' perception but are often challenging and time-consuming; therefore, using species that can be trained easily for complex tasks is advantageous. Picasso triggerfish, Rhinecanthus aculeatus, have been used in many behavioural studies investigating vision and navigation. However, little is known about the molecular and anatomical basis of their visual system. We addressed this knowledge gap here and behaviourally tested achromatic and chromatic acuity. In terms of visual opsins, R. aculeatus possessed one rod opsin gene (RH1) and at least nine cone opsins: one violet-sensitive SWS2B gene, seven duplicates of the blue-green-sensitive RH2 gene (RH2A, RH2B, RH2C1-5) and one red-sensitive LWS gene. However, only five cone opsins were expressed: SWS2B expression was consistent, while RH2A, RH2C-1 and RH2C-2 expression varied depending on whether fish were sampled from the field or aquaria. Levels of LWS expression were very low. Using fluorescence in situ hybridisation, we found SWS2B was expressed exclusively in single cones, whereas RH2A and RH2Cs were expressed in opposite double cone members. Anatomical resolution estimated from ganglion cell densities was 6.8 cycles per degree (cpd), which was significantly higher than values obtained from behavioural testing for black-and-white achromatic stimuli (3.9 cpd) and chromatic stimuli (1.7-1.8 cpd). These measures were twice as high as previously reported. This detailed information on their visual system will help inform future studies with this emerging focal species.


Assuntos
Opsinas dos Cones , Tetraodontiformes , Animais , Opsinas dos Cones/genética , Opsinas dos Cones/metabolismo , Opsinas/genética , Opsinas/metabolismo , Filogenia , Células Fotorreceptoras Retinianas Cones , Opsinas de Bastonetes/genética , Opsinas de Bastonetes/metabolismo
7.
Mol Biol Evol ; 39(4)2022 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-35348742

RESUMO

The evolution of color vision is often studied through the lens of receptor gain relative to an ancestor with fewer spectral classes of photoreceptor. For instance, in Heliconius butterflies, a genus-specific UVRh opsin duplication led to the evolution of UV color discrimination in Heliconius erato females, a rare trait among butterflies. However, color vision evolution is not well understood in the context of loss. In Heliconius melpomene and Heliconius ismenius lineages, the UV2 receptor subtype has been lost, which limits female color vision in shorter wavelengths. Here, we compare the visual systems of butterflies that have either retained or lost the UV2 photoreceptor using intracellular recordings, ATAC-seq, and antibody staining. We identify several ways these butterflies modulate their color vision. In H. melpomene, chromatin reorganization has downregulated an otherwise intact UVRh2 gene, whereas in H. ismenius, pseudogenization has led to the truncation of UVRh2. In species that lack the UV2 receptor, the peak sensitivity of the remaining UV1 photoreceptor cell is shifted to longer wavelengths. Across Heliconius, we identify the widespread use of filtering pigments and co-expression of two opsins in the same photoreceptor cells. Multiple mechanisms of spectral tuning, including the molecular evolution of blue opsins, have led to the divergence of receptor sensitivities between species. The diversity of photoreceptor and ommatidial subtypes between species suggests that Heliconius visual systems are under varying selection pressures for color discrimination. Modulating the wavelengths of peak sensitivities of both the blue- and remaining UV-sensitive photoreceptor cells suggests that Heliconius species may have compensated for UV receptor loss.


Assuntos
Borboletas , Visão de Cores , Animais , Borboletas/genética , Visão de Cores/genética , Feminino , Opsinas/genética , Células Fotorreceptoras , Asas de Animais
8.
Biophys J ; 121(9): 1765-1776, 2022 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-35331688

RESUMO

In the past decade, optogenetics has become a nearly ubiquitous tool in neuroscience because it enables researchers to manipulate neural activity with high temporal resolution and genetic specificity. Rational engineering of optogenetic tools has produced channelrhodopsins with a wide range of kinetics and photocurrent magnitude. Genome mining for previously unidentified species of rhodopsin has uncovered optogenetic tools with diverse spectral sensitivities. However, rational engineering of a rhodopsin has thus far been unable to re-engineer spectral sensitivity while preserving full photocurrent. Here, we developed and characterized ChroME-mTFP, a rhodopsin-fluorescent protein fusion that drives photocurrent through Förster resonance energy transfer (FRET). This FRET-opsin mechanism artificially broadened the activation spectrum of the blue-green-light-activated rhodopsin ChroME by approximately 50 nm, driving higher photocurrent at blue-shifted excitation wavelengths without sacrificing kinetics. The excitation spectra's increase at short wavelengths enabled us to optogenetically excite neurons at lower excitation powers with shorter wavelengths of light. Increasing this rhodopsin's sensitivity to shorter, bluer wavelengths pushes it toward dual-channel, crosstalk-free optogenetic stimulation and imaging with green-light-activated sensors. However, this iteration of FRET-opsin suffers from some imaging-light-induced photocurrent crosstalk from green or yellow light due to maintained, low-efficiency excitation at longer wavelengths.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Rodopsina , Channelrhodopsins/metabolismo , Opsinas/metabolismo , Optogenética/métodos , Rodopsina/genética , Rodopsina/metabolismo
9.
Adv Sci (Weinh) ; 9(12): e2104140, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35187865

RESUMO

Optogenetics has become a widely used technique in neuroscience research, capable of controlling neuronal activity with high spatiotemporal precision and cell-type specificity. Expressing exogenous opsins in the selected cells can induce neuronal activation upon light irradiation, and the activation depends on the power of incident light. However, high optical power can also lead to off-target neuronal activation or even cell damage. Limiting the incident power, but enhancing power distribution to the targeted neurons, can improve optogenetic efficiency and reduce off-target effects. Here, the use of optical lenses made of polystyrene microspheres is demonstrated to achieve effective focusing of the incident light of relatively low power to neighboring neurons via photonic jets. The presence of microspheres significantly localizes and enhances the power density to the target neurons both in vitro and ex vivo, resulting in increased inward current and evoked action potentials. In vivo results show optogenetic stimulation with microspheres that can evoke significantly more motor behavior and neuronal activation at lowered power density. In all, a proof-of-concept of a strategy is demonstrated to increase the efficacy of optogenetic neuromodulation using pulses of reduced optical power.


Assuntos
Opsinas , Optogenética , Potenciais de Ação , Neurônios/fisiologia , Optogenética/métodos , Fótons
10.
Poult Sci ; 101(4): 101699, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35176701

RESUMO

The Pekin duck is a valuable agricultural commodity globally and in the United States. Pekin ducks are seasonal breeders; they are sensitive to light and thus, research on the neuroendocrine and behavioral responses are needed to maximize production and to improve their welfare. There is compelling evidence that specific wavelengths of light may adversely alter the growth and welfare of meat (grow out) ducks. However, despite a birds' dependence upon light, in commercial poultry hatcheries, incubators almost exclusively hold eggs in the dark. Therefore, our objective was to determine the effects of lighting on the expression of retina photoreceptors (RPs) and deep brain photoreceptors (DBPs) during duck embryological development. Two groups of ducks were raised with and without light over 21 d from egg laying, embryonic day 0. Brain and retinal tissues were collected at embryonic days 3, 7, 11, 16, and 21 of a 24 d incubation period. qRT-PCR was performed on RPs (OPN1LW, OPN2SW, OPN1SW, MAFA, RHO, and RBP3) and the DBP OPN4M from retinal and brain samples, respectively. We find that the presence and absence of light during pre-hatch incubation, had no influence on the expression of any retinal photoreceptor. However, a late embryological increase in DBP OPN4M expression was observed. Taken together, the impact of light during pre-hatch incubation does not impact the overall post-hatch production. However, future directions should explore how OPN4M pre-hatch activation impacts Pekin duck post-hatch development and growth.


Assuntos
Patos , Opsinas , Animais , Galinhas , Patos/fisiologia , Desenvolvimento Embrionário , Incubadoras , Óvulo
11.
Int J Mol Sci ; 23(3)2022 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-35163334

RESUMO

One important role of epigenetic regulation is controlling gene expression in development and homeostasis. However, little is known about epigenetics' role in regulating opsin expression. Cell cultures (HEK 293, Y79, and WERI) producing different levels of opsins were treated with 5-aza-2'-deoxycytidine (5-Aza-dc) and/or sodium butyrate (SB) or suberoylanilide hydroxamic acid (SAHA) for 72 h. Global DNA methylation, site-specific methylation, and expressions of opsins were measured by LUMA assay, bisulfite pyrosequencing, and qPCR, respectively. Mouse retinal explants from wild-type P0/P1 pups were ex vivo cultured with/without 5-Aza-dc or SAHA for 6 days. The morphology of explants, DNA methylation, and expressions of opsins was examined. The drugs induced global DNA hypomethylation or increased histone acetylation in cells, including DNA hypomethylation of rhodopsin (RHO) and L-opsin (OPN1LW) and a concomitant increase in their expression. Further upregulation of RHO and/or OPN1LW in HEK 293 or WERI cells was observed with 5-Aza-dc and either SB or SAHA combination treatment. Mouse retinal explants developed normally but had drug-dependent differential DNA methylation and expression patterns of opsins. DNA methylation and histone acetylation directly regulate opsin expression both in vitro and ex vivo. The ability to manipulate opsin expression using epigenetic modifiers enables further study into the role of epigenetics in eye development and disease.


Assuntos
Metilação de DNA , Histonas , Acetilação , Animais , Azacitidina/farmacologia , Decitabina/farmacologia , Epigênese Genética , Expressão Gênica , Células HEK293 , Inibidores de Histona Desacetilases/farmacologia , Histonas/metabolismo , Humanos , Ácidos Hidroxâmicos/farmacologia , Camundongos , Opsinas/genética , Opsinas/metabolismo , Opsinas de Bastonetes/genética , Opsinas de Bastonetes/metabolismo
12.
Neuron ; 110(7): 1139-1155.e6, 2022 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-35120626

RESUMO

The biophysical properties of existing optogenetic tools constrain the scale, speed, and fidelity of precise optogenetic control. Here, we use structure-guided mutagenesis to engineer opsins that exhibit very high potency while retaining fast kinetics. These new opsins enable large-scale, temporally and spatially precise control of population neural activity. We extensively benchmark these new opsins against existing optogenetic tools and provide a detailed biophysical characterization of a diverse family of opsins under two-photon illumination. This establishes a resource for matching the optimal opsin to the goals and constraints of patterned optogenetics experiments. Finally, by combining these new opsins with optimized procedures for holographic photostimulation, we demonstrate the simultaneous coactivation of several hundred spatially defined neurons with a single hologram and nearly double that number by temporally interleaving holograms at fast rates. These newly engineered opsins substantially extend the capabilities of patterned illumination optogenetic paradigms for addressing neural circuits and behavior.


Assuntos
Rede Nervosa , Opsinas , Optogenética , Holografia/métodos , Rede Nervosa/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Opsinas/química , Opsinas/genética , Optogenética/métodos
13.
J Exp Biol ; 225(6)2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-35224643

RESUMO

Stomatopod crustaceans, or mantis shrimps, are known for their extensive range of spectral sensitivity but relatively poor spectral discrimination. Instead of the colour-opponent mechanism of other colour vision systems, the 12 narrow-band colour channels they possess may underlie a different method of colour processing. We investigated one hypothesis in which the photoreceptors are proposed to act as individual wave-band detectors, interpreting colour as a parallel pattern of photoreceptor activation, rather than a ratiometric comparison of individual signals. This different form of colour detection has been used to explain previous behavioural tests in which low-saturation blue was not discriminated from grey, potentially because of similar activation patterns. Results here, however, indicate that the stomatopod Haptosquilla trispinosa was able to easily distinguish several colours, including blue of both high and low saturation, from greys. The animals did show a decrease in performance over time in an artificially lit environment, indicating plasticity in colour discrimination ability. This rapid plasticity, most likely the result of a change in opsin (visual pigment) expression, has now been noted in several animal lineages (both invertebrate and vertebrate) and is a factor we suggest needs attention and potential re-examination in any colour-based behavioural tests. As for stomatopods, it remains unclear why they achieve poor colour discrimination using the most comprehensive set of spectral sensitivities in the animal kingdom and also what form of colour processing they may utilise.


Assuntos
Visão de Cores , Animais , Percepção de Cores/fisiologia , Crustáceos/fisiologia , Opsinas , Células Fotorreceptoras de Invertebrados/fisiologia , Pigmentos da Retina/fisiologia
14.
Elife ; 112022 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-35199641

RESUMO

Opsins are universal photoreceptive proteins in animals and can be classified into three types based on their photoreaction properties. Upon light irradiation, vertebrate rhodopsin forms a metastable active state, which cannot revert back to the original dark state via either photoreaction or thermal reaction. By contrast, after photoreception, most opsins form a stable active state which can photoconvert back to the dark state. Moreover, we recently found a novel type of opsins whose activity is regulated by photocycling. However, the molecular mechanism underlying this diversification of opsins remains unknown. In this study, we showed that vertebrate rhodopsin acquired the photocyclic and photoreversible properties upon introduction of a single mutation at position 188. This revealed that the residue at position 188 contributes to the diversification of photoreaction properties of opsins by its regulation of the recovery from the active state to the original dark state.


Assuntos
Substituição de Aminoácidos , Rodopsina/genética , Sequência de Aminoácidos , Animais , Bovinos , Luz , Mutação , Opsinas/genética , Opsinas/metabolismo , Rodopsina/metabolismo , Vertebrados/genética
15.
Mol Biol Evol ; 39(3)2022 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-35143663

RESUMO

Opsins, the protein moieties of animal visual photo-pigments, have emerged as moonlighting proteins with diverse, light-dependent and -independent physiological functions. This raises the need to revise some basic assumptions concerning opsin expression, structure, classification, and evolution.


Assuntos
Evolução Molecular , Opsinas , Animais , Opsinas/genética , Opsinas/metabolismo , Filogenia , Pigmentos da Retina , Opsinas de Bastonetes/genética
16.
Nat Commun ; 13(1): 839, 2022 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-35149715

RESUMO

Optogenetic methods provide efficient cell-specific modulations, and the ability of simultaneous neural activation and inhibition in the same brain region of freely moving animals is highly desirable. Here we report bidirectional neuronal activity manipulation accomplished by a wireless, dual-color optogenetic probe in synergy with the co-expression of two spectrally distinct opsins (ChrimsonR and stGtACR2) in a rodent model. The flexible probe comprises vertically assembled, thin-film microscale light-emitting diodes with a lateral dimension of 125 × 180 µm2, showing colocalized red and blue emissions and enabling chronic in vivo operations with desirable biocompatibilities. Red or blue irradiations deterministically evoke or silence neurons co-expressing the two opsins. The probe interferes with dopaminergic neurons in the ventral tegmental area of mice, increasing or decreasing dopamine levels. Such bidirectional regulations further generate rewarding and aversive behaviors and interrogate social interactions among multiple mice. These technologies create numerous opportunities and implications for brain research.


Assuntos
Comportamento Animal , Optogenética/instrumentação , Optogenética/métodos , Tecnologia sem Fio , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/fisiologia , Dopamina , Neurônios Dopaminérgicos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Opsinas , Área Tegmentar Ventral , Tecnologia sem Fio/instrumentação
17.
PLoS Genet ; 18(2): e1010033, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-35143488

RESUMO

To survive, organisms need to precisely respond to various environmental factors, such as light and gravity. Among these, light is so important for most life on Earth that light-response systems have become extraordinarily developed during evolution, especially in multicellular animals. A combination of photoreceptors, nervous system components, and effectors allows these animals to respond to light stimuli. In most macroscopic animals, muscles function as effectors responding to light, and in some microscopic aquatic animals, cilia play a role. It is likely that the cilia-based response was the first to develop and that it has been substituted by the muscle-based response along with increases in body size. However, although the function of muscle appears prominent, it is poorly understood whether ciliary responses to light are present and/or functional, especially in deuterostomes, because it is possible that these responses are too subtle to be observed, unlike muscle responses. Here, we show that planktonic sea urchin larvae reverse their swimming direction due to the inhibitory effect of light on the cholinergic neuron signaling>forward swimming pathway. We found that strong photoirradiation of larvae that stay on the surface of seawater immediately drives the larvae away from the surface due to backward swimming. When Opsin2, which is expressed in mesenchymal cells in larval arms, is knocked down, the larvae do not show backward swimming under photoirradiation. Although Opsin2-expressing cells are not neuronal cells, immunohistochemical analysis revealed that they directly attach to cholinergic neurons, which are thought to regulate forward swimming. These data indicate that light, through Opsin2, inhibits the activity of cholinergic signaling, which normally promotes larval forward swimming, and that the light-dependent ciliary response is present in deuterostomes. These findings shed light on how light-responsive tissues/organelles have been conserved and diversified during evolution.


Assuntos
Movimento/fisiologia , Células Fotorreceptoras/metabolismo , Ouriços-do-Mar/metabolismo , Animais , Cílios/metabolismo , Larva/metabolismo , Luz , Locomoção/fisiologia , Músculos/fisiologia , Opsinas/genética , Opsinas/metabolismo , Plâncton
18.
BMC Ecol Evol ; 22(1): 2, 2022 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-34996358

RESUMO

BACKGROUND: Visual opsins are expressed in the compound eyes and ocelli of insects and enable light detection. Three distinct phylogenetic groups of visual opsins are found in insects, named long (LW), short (SW) and ultraviolet (UV) wavelength sensitive opsins. Recently, the LW group was found to be duplicated into the LW2b and the LW2a opsins. The expression of LW2b opsins is ocelli specific in some insects (e.g., bees, cricket, scorpion flies), but the gene was not found in other orders possessing three or less ocelli (e.g., dragonflies, beetles, moths, bugs). In flies, two LW2b homologs have been characterised, with one expressed in the ocelli and the other in the compound eyes. To date, it remains unclear which evolutionary forces have driven gains and losses of LW opsins in insects. Here we take advantage of the recent rapid increase in available sequence data (i.e., from insect genomes, targeted PCR amplification, RNAseq) to characterize the phylogenetic relationships of 1000 opsin sequences in 18 orders of Insects. The resulting phylogeny discriminates between four main groups of opsins, and onto this phylogeny we mapped relevant morphological and life history traits. RESULTS: Our results demonstrate a conserved LW2b opsin only present in insects with three ocelli. Only two groups (Brachycera and Odonata) possess more than one LW2b opsin, likely linked to their life history. In flies, we hypothesize that the duplication of the LW2b opsin occurred after the transition from aquatic to terrestrial larvae. During this transition, higher flies (Brachycera) lost a copy of the LW2a opsin, still expressed and duplicated in the compound eyes of lower flies (Nematocera). In higher flies, the LW2b opsin has been duplicated and expressed in the compound eyes while the ocelli and the LW2b opsin were lost in lower flies. In dragonflies, specialisation of flight capabilities likely drove the diversification of the LW2b visual opsins. CONCLUSION: The presence of the LW2b opsin in insects possessing three ocelli suggests a role in specific flight capabilities (e.g., stationary flight). This study provides the most complete view of the evolution of visual opsin genes in insects yet, and provides new insight into the influence of ocelli and life history traits on opsin evolution in insects.


Assuntos
Traços de História de Vida , Odonatos , Animais , Abelhas , Insetos/genética , Odonatos/metabolismo , Opsinas/genética , Filogenia
19.
J Exp Biol ; 225(3)2022 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-35029279

RESUMO

Stomatopod crustaceans have among the most complex eyes in the animal kingdom, with up to 12 different color detection channels. The capabilities of these unique eyes include photoreception of ultraviolet (UV) wavelengths (<400 nm). UV vision has been well characterized in adult stomatopods but has not been previously demonstrated in the comparatively simpler larval eye. Larval stomatopod eyes are developmentally distinct from their adult counterpart and have been described as lacking the visual pigment diversity and morphological specializations found in adult eyes. However, recent studies have provided evidence that larval stomatopod eyes are more complex than previously thought and warrant closer investigation. Using electroretinogram recordings in live animals we found physiological evidence of blue- and UV-sensitive photoreceptors in larvae of the Caribbean stomatopod species Neogonodactylus oerstedii. Transcriptomes of individual larvae were used to identify the expression of three distinct UV opsin mRNA transcripts, which may indicate the presence of multiple UV spectral channels. This is the first paper to document UV vision in any larval stomatopod, expanding our understanding of the importance of UV sensitivity in plankton. Larval stomatopod eyes are more complex and more similar to adult eyes than expected, showing previously uncharacterized molecular diversity and physiological functions.


Assuntos
Crustáceos , Opsinas , Visão Ocular , Animais , Crustáceos/fisiologia , Olho , Larva , Opsinas/genética , Opsinas/metabolismo , Raios Ultravioleta
20.
Commun Biol ; 5(1): 63, 2022 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-35042952

RESUMO

Opsins are G protein-coupled receptors specialized for photoreception in animals. Opn5 is categorized in an independent opsin group and functions for various non-visual photoreceptions. Among vertebrate Opn5 subgroups (Opn5m, Opn5L1 and Opn5L2), Opn5m and Opn5L2 bind 11-cis retinal to form a UV-sensitive resting state, which is inter-convertible with the all-trans retinal bound active state by photoreception. Thus, these opsins are characterized as bistable opsins. To assess the molecular basis of the UV-sensitive bistable property, we introduced comprehensive mutations at Thr188, which is well conserved among these opsins. The mutations in Opn5m drastically hampered 11-cis retinal incorporation and the bistable photoreaction. Moreover, T188C mutant Opn5m exclusively bound all-trans retinal and thermally self-regenerated to the original form after photoreception, which is similar to the photocyclic property of Opn5L1 bearing Cys188. Therefore, the residue at position 188 underlies the UV-sensitive bistable property of Opn5m and contributes to the diversification of vertebrate Opn5 subgroups.


Assuntos
Aminoácidos/química , Proteínas de Membrana/efeitos da radiação , Opsinas/efeitos da radiação , Raios Ultravioleta , Proteínas de Xenopus/efeitos da radiação , Animais , Proteínas de Membrana/química , Opsinas/química , Xenopus , Proteínas de Xenopus/química
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