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Biochemistry. Biokhimiia Oct 2023Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that,... (Review)
Review
Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that, channelrhodopsins are widely used in neuroscience and cardiology as instruments for optogenetic manipulation of the activity of excitable cells. Photocurrents generated by channelrhodopsins were first discovered in the cells of green algae in the 1970s. In this review we describe this discovery and discuss the current state of research in the field.
Topics: Channelrhodopsins; Optogenetics; Phototaxis; Light; Ion Transport
PubMed: 38105024
DOI: 10.1134/S0006297923100115 -
Journal of Plant Research May 2017Brown algae exhibit three patterns of sexual reproduction: isogamy, anisogamy, and oogamy. Unicellular swarmers including gametes and zoospores bear two heterogenous... (Review)
Review
Brown algae exhibit three patterns of sexual reproduction: isogamy, anisogamy, and oogamy. Unicellular swarmers including gametes and zoospores bear two heterogenous flagella, an anterior flagellum with mastigonemes (fine tripartite hairs) and a posterior one. In seawater, these flagellates usually receive physico-chemical signals for finding partners and good habitats. It is well known that brown algal swarmers change their swimming direction depending on blue light (phototaxis), and male gametes do so, based on the sex pheromones from female gametes (chemotaxis). In recent years, the comparative analysis of chemotaxis in isogamy, anisogamy, and oogamy has been conducted. In this paper, we focused on the phototaxis and chemotaxis of brown algal gametes comparing the current knowledge with our recent studies.
Topics: Chemotaxis; Fertilization; Flagella; Fluorescence; Light; Phaeophyceae; Pheromones; Phototaxis; Reproduction; Sperm Motility
PubMed: 28271338
DOI: 10.1007/s10265-017-0914-8 -
Philosophical Transactions of the Royal... Jan 2016Vision allows animals to detect spatial differences in environmental light levels. High-resolution image-forming eyes evolved from low-resolution eyes via increases in... (Review)
Review
Vision allows animals to detect spatial differences in environmental light levels. High-resolution image-forming eyes evolved from low-resolution eyes via increases in photoreceptor cell number, improvements in optics and changes in the neural circuits that process spatially resolved photoreceptor input. However, the evolutionary origins of the first low-resolution visual systems have been unclear. We propose that the lowest resolving (two-pixel) visual systems could initially have functioned in visual phototaxis. During visual phototaxis, such elementary visual systems compare light on either side of the body to regulate phototactic turns. Another, even simpler and non-visual strategy is characteristic of helical phototaxis, mediated by sensory-motor eyespots. The recent mapping of the complete neural circuitry (connectome) of an elementary visual system in the larva of the annelid Platynereis dumerilii sheds new light on the possible paths from non-visual to visual phototaxis and to image-forming vision. We outline an evolutionary scenario focusing on the neuronal circuitry to account for these transitions. We also present a comprehensive review of the structure of phototactic eyes in invertebrate larvae and assign them to the non-visual and visual categories. We propose that non-visual systems may have preceded visual phototactic systems in evolution that in turn may have repeatedly served as intermediates during the evolution of image-forming eyes.
Topics: Animals; Biological Evolution; Eye; Gene Expression Regulation; Opsins; Photoreceptor Cells
PubMed: 26598725
DOI: 10.1098/rstb.2015.0042 -
Aquatic Toxicology (Amsterdam,... Dec 2023Animal-based sensors have been increasingly applied to many water monitoring systems and ecological studies. One of the staple organisms used as living sensors for such... (Review)
Review
Animal-based sensors have been increasingly applied to many water monitoring systems and ecological studies. One of the staple organisms used as living sensors for such systems is Daphnia. This organism has been extensively studied and, with time, used in many toxicological and pharmaceutical bioassays, often used for exploring the ecology of freshwater communities. One of its behaviours used for evaluating the state of the aquatic environment is phototaxis. A disruption in the predicted behaviour is interpreted as a sign of stress and forms the basis for further investigation. However, phototaxis is a result of complex processes counteracting and interacting with each other. Predator presence, food quality, body pigmentation and other factors can greatly affect the predicted phototactic response, hampering its reliability as a bioindicator. Therefore, a holistic approach and meticulous documentation of the methods are needed for the correct interpretation of this behavioural indicator. In this review, we present the current methods used for studying phototaxis, the factors affecting it and proposed ways to optimise the reliability of the results.
Topics: Animals; Water Pollutants, Chemical; Phototaxis; Reproducibility of Results; Daphnia
PubMed: 38000135
DOI: 10.1016/j.aquatox.2023.106762 -
Philosophical Transactions of the Royal... Oct 2009Phototaxis in the broadest sense means positive or negative displacement along a light gradient or vector. Prokaryotes most often use a biased random walk strategy,... (Review)
Review
Phototaxis in the broadest sense means positive or negative displacement along a light gradient or vector. Prokaryotes most often use a biased random walk strategy, employing type I sensory rhodopsin photoreceptors and two-component signalling to regulate flagellar reversal. This strategy only allows phototaxis along steep light gradients, as found in microbial mats or sediments. Some filamentous cyanobacteria evolved the ability to steer towards a light vector. Even these cyanobacteria, however, can only navigate in two dimensions, gliding on a surface. In contrast, eukaryotes evolved the capacity to follow a light vector in three dimensions in open water. This strategy requires a polarized organism with a stable form, helical swimming with cilia and a shading or focusing body adjacent to a light sensor to allow for discrimination of light direction. Such arrangement and the ability of three-dimensional phototactic navigation evolved at least eight times independently in eukaryotes. The origin of three-dimensional phototaxis often followed a transition from a benthic to a pelagic lifestyle and the acquisition of chloroplasts either via primary or secondary endosymbiosis. Based on our understanding of the mechanism of phototaxis in single-celled eukaryotes and animal larvae, it is possible to define a series of elementary evolutionary steps, each of potential selective advantage, which can lead to pelagic phototactic navigation. We can conclude that it is relatively easy to evolve phototaxis once cell polarity, ciliary swimming and a stable cell shape are present.
Topics: Animals; Biological Evolution; Eukaryota; Light Signal Transduction; Prokaryotic Cells
PubMed: 19720645
DOI: 10.1098/rstb.2009.0072 -
Plant Signaling & Behavior Dec 2023Photosynthetic organisms biosynthesize various carotenoids, a group of light-absorbing isoprenoid pigments that have key functions in photosynthesis, photoprotection,... (Review)
Review
Photosynthetic organisms biosynthesize various carotenoids, a group of light-absorbing isoprenoid pigments that have key functions in photosynthesis, photoprotection, and phototaxis. Microalgae, in particular, contain diverse carotenoids and carotenoid biosynthetic pathways as a consequence of the various endosymbiotic events in their evolutionary history. Carotenoids such as astaxanthin, diadinoxanthin, and fucoxanthin are unique to algae. In microalgae, carotenoids are concentrated in the eyespot, a pigmented organelle that is important for phototaxis. A wide range of microalgae, including chlorophytes, euglenophytes, ochrophytes, and haptophytes, have an eyespot. In the chlorophyte , carotenoid layers in the eyespot reflect light to amplify the photosignal and shield photoreceptors from light, thereby enabling precise phototaxis. Our recent research revealed that, in contrast to the β-carotene-rich eyespot of , the euglenophyte relies on zeaxanthin for stable eyespot formation and phototaxis. In this review, we highlight recent advancements in the study of eyespot carotenoids and phototaxis in these microalgae, placing special emphasis on the diversity of carotenoid-dependent visual systems among microalgae.
Topics: Carotenoids; Microalgae; Phototaxis; Terpenes; beta Carotene
PubMed: 37724547
DOI: 10.1080/15592324.2023.2257348 -
Pest Management Science Dec 2019Many insects, especially nocturnal insects, exhibit positive phototaxis to artificial lights. Light traps are currently used to monitor and manage insect pest... (Review)
Review
Many insects, especially nocturnal insects, exhibit positive phototaxis to artificial lights. Light traps are currently used to monitor and manage insect pest populations, and play a crucial role in physical pest control. Efficient use of light traps to attract target insect pests is an important topic in the application of integrated pest management (IPM). Phototactic responses of insects vary among species, light characteristics and the physiological status of the insects. In addition, light can cause several biological responses, including biochemical, physiological, molecular and fitness changes in insects. In this review, we discuss several hypotheses on insect phototaxis, factors affecting insect phototaxis, insect-sensitive wavelengths, biological responses of insects to light, and countermeasures for conserving beneficial insects and increasing the effect of trapping. In addition, we provide information on the different sensitivities to wavelengths causing positive phototactic behavior in > 70 insect pest and beneficial insect species. The use of advanced light traps equipped with superior light sources, such as light-emitting diodes (LEDs), will make physical pest control in IPM more efficient. © 2019 Society of Chemical Industry.
Topics: Animals; Insect Control; Insecta; Phototaxis
PubMed: 31251458
DOI: 10.1002/ps.5536 -
MBio Dec 2021Cyanobacteria rely on photosynthesis, and thus have evolved complex responses to light. These include phototaxis, the ability of cells to sense light direction and move...
Cyanobacteria rely on photosynthesis, and thus have evolved complex responses to light. These include phototaxis, the ability of cells to sense light direction and move towards or away from it. Analysis of mutants has demonstrated that phototaxis requires the coordination of multiple photoreceptors and signal transduction networks. The output of these networks is relayed to type IV pili (T4P) that attach to and exert forces on surfaces or other neighboring cells to drive "twitching" or "gliding" motility. This, along with the extrusion of polysaccharides or "slime" by cells, facilitates the emergence of group behavior. We evaluate recent models that describe the emergence of collective colony-scale behavior from the responses of individual, interacting cells. We highlight the advantages of "active matter" approaches in the study of bacterial communities, discussing key differences between emergent behavior in cyanobacterial phototaxis and similar behavior in chemotaxis or quorum sensing.
Topics: Bacterial Proteins; Chemotaxis; Fimbriae, Bacterial; Light; Mutation; Phototaxis; Quorum Sensing; Synechocystis
PubMed: 34809455
DOI: 10.1128/mBio.02398-21 -
Soft Matter Dec 2020Biomimetic behaviour in artificially created active matter that allows deterministic and controlled motility has become of growing interest in recent years. It is well...
Biomimetic behaviour in artificially created active matter that allows deterministic and controlled motility has become of growing interest in recent years. It is well known that phototrophic bacteria optimize their position with respect to light by phototaxis. Here, we describe how our fully artificial, magnetic and photocatalytic microswimmers undergo a specific type of behaviour that strongly resembles phototaxis: when crossing an illuminated stripe the particles repeatedly turn back towards the light once they reach the dark region, without any obvious reason for the particles to do so. In order to understand the origin of this behaviour we analyze different influences and elucidate through experiments and theoretical considerations that this behavior arises from a combination of orientational stabilization through activity and destabilizing Brownian motion. This interplay shows beautifully how simple physical effects can combine into complex behaviours.
Topics: Cell Movement; Light; Motion; Phototaxis; Physical Phenomena
PubMed: 33112347
DOI: 10.1039/d0sm01603a -
Zoological Science Jun 2023Different crustacean species can differ in their response to light. In Tanaidacea, a small group of aquatic, benthic crustaceans, previous studies suggested that several...
Different crustacean species can differ in their response to light. In Tanaidacea, a small group of aquatic, benthic crustaceans, previous studies suggested that several species may be positively phototactic based on their attraction to nocturnal light traps, but no experimental investigations of phototaxis had been conducted on this group. Here we show experimentally that two species in the genus are phototactic but exhibit opposite reactions to light; , which inhabits the blades and stipes of seaweeds, was positively phototactic, whereas , which inhabits muddy sediments overlying bedrock, was negatively phototactic. This differential response may reflect differences in photoenvironment between these species' microhabitats.
Topics: Animals; Water; Phototaxis; Crustacea
PubMed: 37256567
DOI: 10.2108/zs220118