-
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 -
Advanced Materials (Deerfield Beach,... Apr 2021Light-driven directional motion is common in nature but remains a challenge for synthetic microparticles, particularly regarding collective motion on a macroscopic...
Light-driven directional motion is common in nature but remains a challenge for synthetic microparticles, particularly regarding collective motion on a macroscopic scale. Successfully engineering microparticles with light-driven collective motion could lead to breakthroughs in drug delivery, contaminant sensing, environmental remediation, and artificial life. Herein, metal-phenolic particle microswimmers capable of autonomously sensing and swimming toward an external light source are reported, with the speed regulated by the wavelength and intensity of illumination. These microswimmers can travel macroscopic distances (centimeters) and can remain illuminated for hours without degradation of motility. Experimental and theoretical analyses demonstrate that motion is generated through chemical transformations of the organic component of the metal-phenolic complex. Furthermore, cargos with specific spectral absorption profiles can be loaded into the particles and endow the particle microswimmers with activated motion corresponding to these spectral characteristics. The programmable nature of the light navigation, tunable size of the particles, and versatility of cargo loading demonstrate the versatility of these metal-phenolic particle microswimmers.
PubMed: 33634513
DOI: 10.1002/adma.202006177 -
Parasitology Research Sep 2021Phototaxis is the common behavioral response exhibited by the oncomiracidia of various monogeneans. However, the changes in the oncomiracidial swimming behavior in...
Phototaxis is the common behavioral response exhibited by the oncomiracidia of various monogeneans. However, the changes in the oncomiracidial swimming behavior in response to light cues are not well understood. Here, we investigated the light responses of four monogeneans that are important pathogens in mariculture, namely Benedenia epinepheli, Benedenia seriolae, Neobenedenia girellae, and Heteraxine heterocerca. The swimming trajectory and speed of oncomiracidia of each species were assessed in a glass Petri dish with an LED light placed adjacent to it, based on three different light responses: LED light in the off position (normal swimming), LED light in the on position (phototactic behavior), and immediately (< 5 s) after switching the LED light off (photophobic behavior). The oncomiracidia of all four species exhibited positive phototactic and photophobic responses; however, the change in swimming speed between each response differed among the species. The oncomiracidia of three species (B. epinepheli, N. girellae, and H. heterocerca) exhibited high swimming speed, as a phototactic response; in contrast, the oncomiracidia of B. seriolae exhibited reduced swimming speed when moving toward the light source. Benedenia epinepheli and H. heterocerca exhibited the highest swimming speed during the phototaxis phase, whereas B. seriolae and N. girellae exhibited the highest swimming speed during the photophobic phase. These light responses are considered adaptive traits to increase the chance of encountering and infecting suitable hosts in nature, and such responses could potentially be applied to the control of parasite infections in aquaculture.
Topics: Animals; Aquaculture; Phototaxis; Trematoda
PubMed: 34405279
DOI: 10.1007/s00436-021-07280-y -
Advanced Materials (Deerfield Beach,... Jan 2024The integration of microorganisms and engineered artificial components has shown considerable promise for creating biohybrid microrobots. The unique features of... (Review)
Review
The integration of microorganisms and engineered artificial components has shown considerable promise for creating biohybrid microrobots. The unique features of microalgae make them attractive candidates as natural actuation materials for the design of biohybrid microrobotic systems. In this review, microalgae-based biohybrid microrobots are introduced for diverse biomedical and environmental applications. The distinct propulsion and phototaxis behaviors of green microalgae, as well as important properties from other photosynthetic microalga systems (blue-green algae and diatom) that are crucial to constructing powerful biohybrid microrobots, will be described first. Then the focus is on chemical and physical routes for functionalizing the algae surface with diverse reactive materials toward the fabrication of advanced biohybrid microalgae robots. Finally, representative applications of such algae-driven microrobots are presented, including drug delivery, imaging, and water decontamination, highlighting the distinct advantages of these active biohybrid robots, along with future prospects and challenges.
Topics: Microalgae; Robotics
PubMed: 37471001
DOI: 10.1002/adma.202303714 -
Insects Nov 2023Ants are one of the largest insect groups, with the most species and individuals in the world, and they have an important ecological function. Ants are not only an... (Review)
Review
Ants are one of the largest insect groups, with the most species and individuals in the world, and they have an important ecological function. Ants are not only an important part of the food chains but are also one of the main decomposers on the Earth; they can also improve soil fertility, etc. However, some species of ants are harmful to human beings, which leads to people's panic or worry about coming into contact with these insects during their daily home life or in their tourism or leisure activities. The presence of ants in indoor living facilities and in outdoor green spaces, parks, gardens, and tourist attractions seriously interferes with the leisure life and entertainment activities of all people (especially children). How can we control ants in these environments? Do we kill them by spraying insecticides, or do we adopt green prevention and control technology for the ecological management of ants? This topic is related to healthy life for the public and the protection of the ecological environment. In this paper, the species and diversity of ants are introduced, and research progress regarding ant tropism is introduced according to the three aspects of phototaxis, chromotaxis, and chemotaxis (i.e., "3-tropisms"). The research on repellent substances from plants and insects and the related ant attractants are also summarized, analyzed, and discussed, in order to help the research and application of green prevention and control technology for ant diversity protection and conservation.
PubMed: 37999091
DOI: 10.3390/insects14110892 -
Journal of the American Chemical Society May 2020The incorporation of molecular switches in organic structures is of great interest in the chemical design of stimuli-responsive materials that mimic the complex...
The incorporation of molecular switches in organic structures is of great interest in the chemical design of stimuli-responsive materials that mimic the complex functions of living systems. Merocyanine dyes that convert to spiropyran moieties upon exposure to visible light have been extensively studied as they can be incorporated in hydrated covalent networks that will expel water when this conversion occurs and induce a volumetric shrinkage. We report here on a sulfonate-based water-soluble photoswitch that, in contrast to the well-known systems, triggers a volumetric expansion in hydrogels upon exposure to photons. Contraction is in turn observed under dark conditions in a highly reversible manner. The novel behavior of the photoswitch incorporated in the covalent network was predicted by coarse-grained simulations of the system's chemical structure. Using pH control and polymeric structures that differ in lower critical solution temperature, we were able to develop hydrogels with highly tunable volumetric expansion. The novel molecular function of the systems developed here led to materials with the negative phototaxis observed in plants and could expand the potential use of hydrogels as sensors, soft robots, and actuators.
Topics: Benzopyrans; Hydrogels; Indoles; Light; Molecular Structure; Nitro Compounds
PubMed: 32330027
DOI: 10.1021/jacs.0c02201 -
MBio Jun 2022Strains of the freshwater cyanobacterium Synechococcus elongatus were first isolated approximately 60 years ago, and PCC 7942 is well established as a model for...
Strains of the freshwater cyanobacterium Synechococcus elongatus were first isolated approximately 60 years ago, and PCC 7942 is well established as a model for photosynthesis, circadian biology, and biotechnology research. The recent isolation of UTEX 3055 and subsequent discoveries in biofilm and phototaxis phenotypes suggest that lab strains of S. elongatus are highly domesticated. We performed a comprehensive genome comparison among the available genomes of S. elongatus and sequenced two additional laboratory strains to trace the loss of native phenotypes from the standard lab strains and determine the genetic basis of useful phenotypes. The genome comparison analysis provides a pangenome description of S. elongatus, as well as correction of extensive errors in the published sequence for the type strain PCC 6301. The comparison of gene sets and single nucleotide polymorphisms (SNPs) among strains clarifies strain isolation histories and, together with large-scale genome differences, supports a hypothesis of laboratory domestication. Prophage genes in laboratory strains, but not UTEX 3055, affect pigmentation, while unique genes in UTEX 3055 are necessary for phototaxis. The genomic differences identified in this study include previously reported SNPs that are, in reality, sequencing errors, as well as SNPs and genome differences that have phenotypic consequences. One SNP in the circadian response regulator that has caused confusion is clarified here as belonging to an aberrant clone of PCC 7942, used for the published genome sequence, that has confounded the interpretation of circadian fitness research. Synechococcus elongatus is a versatile and robust model cyanobacterium for photosynthetic metabolism and circadian biology research, with utility as a biological production platform. We compared the genomes of closely related S. elongatus strains to create a pangenome annotation to aid gene discovery for novel phenotypes. The comparative genomic analysis revealed the need for a new sequence of the species type strain PCC 6301 and includes two new sequences for S. elongatus strains PCC 6311 and PCC 7943. The genomic comparison revealed a pattern of early laboratory domestication of strains, clarifies the relationship between the strains PCC 6301 and UTEX 2973, and showed that differences in large prophage regions, operons, and even single nucleotides have effects on phenotypes as wide-ranging as pigmentation, phototaxis, and circadian gene expression.
Topics: Bacterial Proteins; Genomics; Phenotype; Photosynthesis; Synechococcus
PubMed: 35475644
DOI: 10.1128/mbio.00862-22 -
Molecular Biology and Evolution May 2021Anthozoan corals are an ecologically important group of cnidarians, which power the productivity of reef ecosystems. They are sessile, inhabit shallow, tropical oceans... (Comparative Study)
Comparative Study
Anthozoan corals are an ecologically important group of cnidarians, which power the productivity of reef ecosystems. They are sessile, inhabit shallow, tropical oceans and are highly dependent on sun- and moonlight to regulate sexual reproduction, phototaxis, and photosymbiosis. However, their exposure to high levels of sunlight also imposes an increased risk of UV-induced DNA damage. How have these challenging photic environments influenced photoreceptor evolution and function in these animals? To address this question, we initially screened the cnidarian photoreceptor repertoire for Anthozoa-specific signatures by a broad-scale evolutionary analysis. We compared transcriptomic data of more than 36 cnidarian species and revealed a more diverse photoreceptor repertoire in the anthozoan subphylum than in the subphylum Medusozoa. We classified the three principle opsin classes into distinct subtypes and showed that Anthozoa retained all three classes, which diversified into at least six subtypes. In contrast, in Medusozoa, only one class with a single subtype persists. Similarly, in Anthozoa, we documented three photolyase classes and two cryptochrome (CRY) classes, whereas CRYs are entirely absent in Medusozoa. Interestingly, we also identified one anthozoan CRY class, which exhibited unique tandem duplications of the core functional domains. We next explored the functionality of anthozoan photoreceptors in the model species Exaiptasia diaphana (Aiptasia), which recapitulates key photo-behaviors of corals. We show that the diverse opsin genes are differentially expressed in important life stages common to reef-building corals and Aiptasia and that CRY expression is light regulated. We thereby provide important clues linking coral evolution with photoreceptor diversification.
Topics: Animals; Anthozoa; Biological Evolution; Cryptochromes; Opsins; Photoreceptor Cells, Invertebrate
PubMed: 33226083
DOI: 10.1093/molbev/msaa304 -
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 -
Journal of Neurogenetics Sep 2021The social ants, bees, wasps, and termites include some of the most ecologically-successful groups of animal species. Their dominance in most terrestrial environments is... (Review)
Review
The social ants, bees, wasps, and termites include some of the most ecologically-successful groups of animal species. Their dominance in most terrestrial environments is attributed to their social lifestyle, which enable their colonies to exploit environmental resources with remarkable efficiency. One key attribute of social insect colonies is the division of labour that emerges among the sterile workers, which represent the majority of colony members. Studies of the mechanisms that drive division of labour systems across diverse social species have provided fundamental insights into the developmental, physiological, molecular, and genomic processes that regulate sociality, and the possible genetic routes that may have led to its evolution from a solitary ancestor. Here we specifically discuss the conserved role of the gene, which encodes a cGMP-dependent protein kinase (PKG). Originally identified as a behaviourally polymorphic gene that drives alternative foraging strategies in the fruit fly , changes in expression and kinase activity were later shown to play a key role in the division of labour in diverse social insect species as well. In particular, appears to regulate worker transitions between behavioural tasks and specific behavioural traits associated with morphological castes. Although the specific neuroethological role of in the insect brain remains mostly unknown, studies in genetically tractable insect species indicate that PKG signalling plays a conserved role in the neuronal plasticity of sensory, cognitive and motor functions, which underlie behaviours relevant to division of labour, including appetitive learning, aggression, stress response, phototaxis, and the response to pheromones.
Topics: Animals; Behavior, Animal; Cyclic GMP-Dependent Protein Kinases; Insecta; Social Behavior
PubMed: 34151702
DOI: 10.1080/01677063.2021.1940173