Topic
Gravitaxis
About: Gravitaxis is a research topic. Over the lifetime, 206 publications have been published within this topic receiving 6096 citations.
Papers published on a yearly basis
Papers
TL;DR: A geometrical arrangement is shown whereby the effect can be made the basis of a new method for concentrating and separating motile cells, and the role of gyrotaxis is discussed in the maintenance of naturally occurring descending streams of cells and in bioconvection patterns.
Abstract: The swimming direction of algal cells can be guided so that the cells are focused into a concentrated beam. This directed locomotion, or taxis, results from the orientation of the cells' axes by compensating gravitational and viscous torques. It is named gyrotaxis because of this origin. Gyrotaxis includes rheotaxis1, which is concerned with orientation and locomotion of elongated microorganisms, especially spermatozoa, in fluids with a velocity gradient. I present here a simplified theory of gyrotaxis, together with experimental evidence. A geometrical arrangement is shown whereby the effect can be made the basis of a new method for concentrating and separating motile cells. Unlike standard concentration/separation techniques, the gyrotactic method requires active participation of the cells and can, in principle, distinguish among them on the basis of morphology and swimming behaviour. I also discuss the role of gyrotaxis in the maintenance of naturally occurring descending streams of cells and in bioconvection patterns.
431 citations
TL;DR: It is demonstrated that a shape anisotropy alone is sufficient to induce gravitactic motion with either preferential upward or downward swimming, and trochoid-like trajectories transversal to the direction of gravity are observed.
Abstract: Gravitaxis describes the ability of microorganisms to adjust their swimming motion on the gravitational field, yet its mechanism remains unclear. Here, the authors show that an asymmetric shape of colloidal particles is alone sufficient to induce gravitactic motion in the absence of density inhomogeneity.
306 citations
TL;DR: The simplest interpretation of these data is that gravitropic sensing is plastid-based, since starchless and intermediate starch mutants show reduced grav itropic sensitivity.
Abstract: Data and theories about the identity of the mass that acts in gravitropic sensing are reviewed. Gravity sensing may have evolved several times in plants and algae in processes such as gravitropism of organs and tip-growing cells, gravimorphism, gravitaxis, and the regulation of cytoplasmic streaming in internodal cells of Chara. In the latter and in gravitaxis, the mass of the entire cell may function in sensing. But gravitropic sensing appears to rely upon the mass of amyloplasts that sediment since (i) the location of cells with sedimentation is highly regulated, (ii) such cells contain other morphological specializations favoring sedimentation, (iii) sedimentation always correlates with gravitropic competence in wild-type plants, (iv) magnetophoretic movement of rootcap amyloplasts mimics gravitropism, and (v) starchless and intermediate starch mutants show reduced gravitropic sensitivity. The simplest interpretation of these data is that gravitropic sensing is plastid-based.
298 citations
TL;DR: The motion of swimming micro-organisms that have a preferred direction of travel, such as single-celled algae moving upwards (gravitaxis) or towards a light source (phototaxis), is modelled as the continuous limit of a correlated and biased random walk as the time step tends to zero.
237 citations
TL;DR: This tutorial review covers the most representative examples of light-driven micro/nanomotors developed so far, which self-propelled exclusively under fuel-free conditions, along with their similarities with the motion modes of microorganisms.
Abstract: The recent advances in the micro/nanomotor field have shown great progress in the propulsion of such devices by fuel-free mechanisms. Light, as an abundant and natural source, has been demonstrated to be a promising external field to wirelessly induce the motion of these tiny micro/nanomachines, without the need of any toxic fuel or complex system set-up. This tutorial review covers the most representative examples of light-driven micro/nanomotors developed so far, which self-propelled exclusively under fuel-free conditions. Their different swimming behaviors triggered by light stimuli, divided into four main categories (schooling, phototaxis, gravitaxis and directional motion), are discussed along with their similarities with the motion modes of microorganisms. Moreover, the main parameters that influence the motion of light-driven photocatalytic-based micro/nanomotors as well as alternative strategies to develop more efficient systems are also discussed.
201 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2022 | 1 |
| 2021 | 5 |
| 2020 | 5 |
| 2019 | 6 |
| 2018 | 8 |
| 2017 | 8 |