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Cell Oct 2021Being able to precisely turn on or off particular neurons in the brain at will was a major challenge for the neuroscience field, and few could have anticipated that the...
Being able to precisely turn on or off particular neurons in the brain at will was a major challenge for the neuroscience field, and few could have anticipated that the solution would come from algae. The 2021 Albert Lasker Basic Medical Research Award recognizes the contributions of Peter Hegemann, Dieter Oesterhelt, and Karl Deisseroth for their discovery of light-sensitive microbial proteins that can activate or silence brain cells. Cell editor Nicole Neuman had a conversation with Peter Hegemann about his role in bridging the two fields of microbial phototaxis and neuroscience and his perspective on the nature and future of interdisciplinary science. Excerpts from this conversation are presented below, and the full conversation is available with the article online.
Topics: Awards and Prizes; Bacterial Proteins; Bacteriorhodopsins; Channelrhodopsins; Humans; Light; Optogenetics
PubMed: 34562361
DOI: 10.1016/j.cell.2021.08.009 -
Animal Cognition Nov 2023Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there... (Review)
Review
Light provides a widely abundant energy source and valuable sensory cue in nature. Most animals exposed to light have photoreceptor cells and in addition to eyes, there are many extraocular strategies for light sensing. Here, we review how these simpler forms of detecting light can mediate rapid behavioural responses in animals. Examples of these behaviours include photophobic (light avoidance) or scotophobic (shadow) responses, photokinesis, phototaxis and wavelength discrimination. We review the cells and response mechanisms in these forms of elementary light detection, focusing on aquatic invertebrates with some protist and terrestrial examples to illustrate the general principles. Light cues can be used very efficiently by these simple photosensitive systems to effectively guide animal behaviours without investment in complex and energetically expensive visual structures.
Topics: Animals; Photoreceptor Cells; Eye; Light
PubMed: 37650997
DOI: 10.1007/s10071-023-01818-6 -
Microorganisms Mar 2022In this review, the general background is provided on cyanobacteria, including morphology, cell membrane structure, and their photosynthesis pathway. The presence of... (Review)
Review
In this review, the general background is provided on cyanobacteria, including morphology, cell membrane structure, and their photosynthesis pathway. The presence of cyanobacteria in nature, and their industrial applications are discussed, and their production of secondary metabolites are explained. Biofilm formation, as a common feature of microorganisms, is detailed and the role of cell diffusion in bacterial colonization is described. Then, the discussion is narrowed down to cyanobacterium , as a lab model microorganism. In this relation, the morphology of is discussed and its different elements are detailed. Type IV pili, the complex multi-protein apparatus for motility and cell-cell adhesion in is described and the underlying function of its different elements is detailed. The phototaxis behavior of the cells, in response to homogenous or directional illumination, is reported and its relation to the run and tumble statistics of the cells is emphasized. In suspensions, there may exist a reciprocal interaction between the cell and the carrying fluid. The effects of shear flow on the growth, doubling per day, biomass production, pigments, and lipid production of are reported. Reciprocally, the effects of presence and its motility on the rheological properties of cell suspensions are addressed. This review only takes up the general grounds of cyanobacteria and does not get into the detailed biological aspects per se. Thus, it is substantially more comprehensive in that sense than other reviews that have been published in the last two decades. It is also written not only for the researchers in the field, but for those in physics and engineering, who may find it interesting, useful, and related to their own research.
PubMed: 35456747
DOI: 10.3390/microorganisms10040696 -
Microbial Cell (Graz, Austria) Jan 2020The microbial environment is typically within a fluid and the key processes happen at the microscopic scale where viscosity dominates over inertial forces. Microfluidic... (Review)
Review
The microbial environment is typically within a fluid and the key processes happen at the microscopic scale where viscosity dominates over inertial forces. Microfluidic tools are thus well suited to study microbial motility because they offer precise control of spatial structures and are ideal for the generation of laminar fluid flows with low Reynolds numbers at microbial lengthscales. These tools have been used in combination with microscopy platforms to visualise and study various microbial taxes. These include establishing concentration and temperature gradients to influence motility via chemotaxis and thermotaxis, or controlling the surrounding microenvironment to influence rheotaxis, magnetotaxis, and phototaxis. Improvements in microfluidic technology have allowed fine separation of cells based on subtle differences in motility traits and have applications in synthetic biology, directed evolution, and applied medical microbiology.
PubMed: 32161767
DOI: 10.15698/mic2020.03.710 -
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 -
Current Biology : CB Jul 2022Diverse light-sensing organs (i.e., eyes) have evolved across animals. Interestingly, several subcellular analogs have been found in eukaryotic microbes. All of these... (Review)
Review
Diverse light-sensing organs (i.e., eyes) have evolved across animals. Interestingly, several subcellular analogs have been found in eukaryotic microbes. All of these systems have a common "recipe": a light occluding or refractory surface juxtaposed to a membrane-layer enriched in type I rhodopsins. In the fungi, several lineages have been shown to detect light using a diversity of non-homologous photo-responsive proteins. However, these systems are not associated with an eyespot-like organelle with one exception found in the zoosporic fungus Blastocladiella emersonii (Be).Be possesses both elements of this recipe: an eyespot composed of lipid-filled structures (often called the side-body complex [SBC]), co-localized with a membrane enriched with a gene-fusion protein composed of a type I (microbial) rhodopsin and guanylyl cyclase enzyme domain (CyclOp-fusion protein). Here, we identify homologous pathway components in four Chytridiomycota orders (Chytridiales, Synchytriales, Rhizophydiales, and Monoblepharidiales). To further explore the architecture of the fungal zoospore and its lipid organelles, we reviewed electron microscopy data (e.g., the works of Barr and Hartmann and Reichle and Fuller) and performed fluorescence-microscopy imaging of four CyclOp-carrying zoosporic fungal species, showing the presence of a variety of candidate eyespot-cytoskeletal ultrastructure systems. We then assessed the presence of canonical photoreceptors across the fungi and inferred that the last common fungal ancestor was able to sense light across a range of wavelengths using a variety of systems, including blue-green-light detection. Our data imply, independently of how the fungal tree of life is rooted, that the apparatus for a CyclOp-organelle light perception system was an ancestral feature of the fungi.
Topics: Animals; Blastocladiella; Chytridiomycota; Fungi; Guanylate Cyclase; Lipids; Minocycline; Rhodopsin
PubMed: 35675809
DOI: 10.1016/j.cub.2022.05.034 -
RSC Advances Feb 2023Rhodopsins, a family of photoreceptive membrane proteins, contain retinal as a chromophore and were firstly identified as reddish pigments from frog retina in 1876.... (Review)
Review
Rhodopsins, a family of photoreceptive membrane proteins, contain retinal as a chromophore and were firstly identified as reddish pigments from frog retina in 1876. Since then, rhodopsin-like proteins have been identified mainly from animal eyes. In 1971, a rhodopsin-like pigment was discovered from the archaeon and named bacteriorhodopsin. While it was believed that rhodopsin- and bacteriorhodopsin-like proteins were expressed only in animal eyes and archaea, respectively, before the 1990s, a variety of rhodopsin-like proteins (called animal rhodopsins or opsins) and bacteriorhodopsin-like proteins (called microbial rhodopsins) have been progressively identified from various tissues of animals and microorganisms, respectively. Here, we comprehensively introduce the research conducted on animal and microbial rhodopsins. Recent analysis has revealed that the two rhodopsin families have common molecular properties, such as the protein structure (, 7-transmembrane structure), retinal structure (, binding ability to - and -retinal), color sensitivity (, UV- and visible-light sensitivities), and photoreaction (, triggering structural changes by light and heat), more than what was expected at the early stages of rhodopsin research. Contrastingly, their molecular functions are distinctively different (, G protein-coupled receptors and photoisomerases for animal rhodopsins and ion transporters and phototaxis sensors for microbial rhodopsins). Therefore, based on their similarities and dissimilarities, we propose that animal and microbial rhodopsins have convergently evolved from their distinctive origins as multi-colored retinal-binding membrane proteins whose activities are regulated by light and heat but independently evolved for different molecular and physiological functions in the cognate organism.
PubMed: 36793294
DOI: 10.1039/d2ra07073a -
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 -
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 -
Applied and Environmental Microbiology Jun 2023Filamentous cyanobacteria exhibit some of the greatest developmental complexity observed in the prokaryotic domain. This includes the ability to differentiate... (Review)
Review
Filamentous cyanobacteria exhibit some of the greatest developmental complexity observed in the prokaryotic domain. This includes the ability to differentiate nitrogen-fixing cells known as heterocysts, spore-like akinetes, and hormogonia, which are specialized motile filaments capable of gliding on solid surfaces. Hormogonia and motility play critical roles in several aspects of the biology of filamentous cyanobacteria, including dispersal, phototaxis, the formation of supracellular structures, and the establishment of nitrogen-fixing symbioses with plants. While heterocyst development has been investigated extensively at the molecular level, much less is known about akinete or hormogonium development and motility. This is due, in part, to the loss of developmental complexity during prolonged laboratory culture in commonly employed model filamentous cyanobacteria. In this review, recent progress in understanding the molecular level regulation of hormogonium development and motility in filamentous cyanobacteria is discussed, with a focus on experiments performed using the genetically tractable model filamentous cyanobacterium Nostoc punctiforme, which retains the developmental complexity of field isolates.
Topics: Gene Expression Regulation, Bacterial; Nostoc; Fimbriae, Bacterial; Symbiosis; Nitrogen; Bacterial Proteins
PubMed: 37199640
DOI: 10.1128/aem.00392-23