scholarly journals Flagellum malfunctions trigger metaboly as an escape strategy in Euglena gracilis

2019 ◽  
Author(s):  
Yong-Jun Chen
Keyword(s):  
Euglena Gracilis ◽  
The Body ◽  
Viscous Resistance ◽  
Bionic Design ◽  
Soft Robots ◽  
Bulk Fluid ◽  
Escape Strategy ◽  
Limited Space ◽  
Unicellular Organisms ◽  
Water Blooms

Euglenoids, a family of aquatic unicellular organisms, present the ability to alter the shape of their bodies, a process referred to as metaboly [1–5]. Metaboly is usually used by phagotrophic cells to engulf their prey. However, Euglena gracilis is osmotrophic and photosynthetic. Though metaboly was discovered centuries ago, it remains unclear why E. gracilis undergo metaboly and what causes them to deform [1–5], and some consider metaboly to be a functionless ancestral vestige [5]. Here, we show that flagellum malfunctions trigger metaboly and metaboly is an escape strategy adopted by E. gracilis when the proper rotation and beating of the flagellum are hindered by restrictions including surface obstruction, sticking, resistance, or limited space. Metaboly facilitates escape in five ways: 1) detaching the body from the surface and decreasing the attaching area attached to the interface, which decreases the adhering force and is advantageous for escaping; 2) enlarging the space between flagellum and the restricting surface which restores beating and rotation of the flagellum; 3) decreasing the torque of viscous resistance for rotation of the body and changing the direction of the body to restore flagellar function; 4) decreasing the length of the body, which pulls the flagellum away from the restrictive situations; and 5) crawling backwards on a surface or swimming backwards in a bulk fluid if the flagellum completely malfunctions or has broken off. Taken together, our findings suggest that metaboly plays a key role in enabling E. gracilis to escape from harmful conditions when flagellar functions is impaired or absent. Our findings can inspire the bionic design of adaptive soft robots and facilitate the control of water blooms of euglena in freshwater aquiculture industry.

scholarly journals Microswimmer Propulsion by Two Steadily Rotating Helical Flagella

Micromachines ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 65 ◽  
Author(s):  
Henry Shum
Keyword(s):  
Simple Model ◽  
Cell Body ◽  
Solid Surface ◽  
The Body ◽  
Theoretical Studies ◽  
Bacterial Strains ◽  
Bulk Fluid ◽  
Similar Shape ◽  
Bacterial Morphology ◽  
Single Flagellum

Many theoretical studies of bacterial locomotion adopt a simple model for the organism consisting of a spheroidal cell body and a single corkscrew-shaped flagellum that rotates to propel the body forward. Motivated by experimental observations of a group of magnetotactic bacterial strains, we extended the model by considering two flagella attached to the cell body and rotating about their respective axes. Using numerical simulations, we analyzed the motion of such a microswimmer in bulk fluid and close to a solid surface. We show that positioning the two flagella far apart on the cell body reduces the rate of rotation of the body and increases the swimming speed. Near surfaces, we found that swimmers with two flagella can swim in relatively straight trajectories or circular orbits in either direction. It is also possible for the swimmer to escape from surfaces, unlike a model swimmer of similar shape but with only a single flagellum. Thus, we conclude that there are important implications of swimming with two flagella or flagellar bundles rather than one. These considerations are relevant not only for understanding differences in bacterial morphology but also for designing microrobotic swimmers.

scholarly journals Between extreme simplification and ideal optimization: antennal sensilla morphology of miniaturized Megaphragma wasps (Hymenoptera: Trichogrammatidae)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e6005 ◽  
Author(s):  
Anna V. Diakova ◽  
Anastasia A. Makarova ◽  
Alexey A. Polilov
Keyword(s):  
Body Size ◽  
The Body ◽  
Parasitoid Wasps ◽  
Antennal Sensilla ◽  
Sensilla Styloconica ◽  
Sensory Reception ◽  
Unicellular Organisms ◽  
Males And Females ◽  
High Level ◽  
Insect Antenna

One of the major trends in the evolution of parasitoid wasps is miniaturization, which has produced the smallest known insects. Megaphragma spp. (Hymenoptera: Trichogrammatidae) are smaller than some unicellular organisms, with an adult body length of the smallest only 170 µm. Their parasitoid lifestyle depends on retention of a high level of sensory reception comparable to that in parasitoid wasps that may have antennae hundreds of times larger. Antennal sensilla of males and females of Megaphragma amalphitanum and M. caribea and females of the parthenogenetic M. mymaripenne are described, including sensillum size, external morphology, and distribution. Eight different morphological types of sensilla were discovered, two of them appearing exclusively on female antennae. Two of the types, sensilla styloconica and aporous placoid sensilla, have not been described previously. Regression analyses were performed to detect and evaluate possible miniaturization trends by comparing available data for species of larger parasitoid wasps. The number of antennal sensilla was found to decrease with the body size; M. amalphitanum males have only 39 sensilla per antenna. The number of antennal sensilla types and sizes of the sensilla, however, show little to no correlation with the body size. Our findings on the effects of miniaturization on the antennal sensilla of Megaphragma provide material for discussion on the limits to the reduction of insect antenna.

Remapping Peripersonal Space by Using Foot-Sole Vibrations Without Any Body Movement

2019 ◽  
Vol 30 (10) ◽  
pp. 1522-1532 ◽  
Author(s):  
Tomohiro Amemiya ◽  
Yasushi Ikei ◽  
Michiteru Kitazaki
Keyword(s):  
Spatial Cognition ◽  
Multisensory Processing ◽  
Body Movement ◽  
Motor Program ◽  
Peripersonal Space ◽  
The Body ◽  
Rhythmic Pattern ◽  
Limited Space ◽  
Tactile Stimuli ◽  
Soles Of The Feet

The limited space immediately surrounding our body, known as peripersonal space (PPS), has been investigated by focusing on changes in the multisensory processing of audio-tactile stimuli occurring within or outside the PPS. Some studies have reported that the PPS representation is extended by body actions such as walking. However, it is unclear whether the PPS changes when a walking-like sensation is induced but the body neither moves nor is forced to move. Here, we show that a rhythmic pattern consisting of walking-sound vibrations applied to the soles of the feet, but not the forearms, boosted tactile processing when looming sounds were located near the body. The findings suggest that an extension of the PPS representation can be triggered by stimulating the soles in the absence of body action, which may automatically drive a motor program for walking, leading to a change in spatial cognition around the body.

The Composition and Origin of the Foetal Fluids of the Pig

Development ◽  
1957 ◽  
Vol 5 (1) ◽  
pp. 43-50
Author(s):  
R. A. McCance ◽  
J. W. T. Dickerson
Keyword(s):  
Active Material ◽  
Distal Tubule ◽  
Body Fluids ◽  
The Body ◽  
Sweat Glands ◽  
Pituitary Hormone ◽  
Posterior Pituitary ◽  
Unicellular Organisms ◽  
Posterior Pituitary Hormone ◽  
Active Reabsorption

Many of the unicellular organisms have a greater concentration of osmotically active material within their body fluids than there is in the medium surrounding them, and the higher animals have glands like the kidney and sweat glands which are able to elaborate fluids with much lower concentrations of sodium and chloride than the body-fluids from which they were derived. The concentrations of sodium and chloride in hypotonic urine and sweat are much lower than those in the serum, and consequently the total osmolar concentrations are also lower, but the urea is characteristically higher. There is no proof that the process is one involving the secretion of water; and, indeed, the kidney is now thought to produce a hypotonic urine by the active reabsorption of sodium from the distal tubule, the walls of which are impermeable to water unless there is posterior pituitary hormone in the circulation.

On the Experimental Determination of the Resistance Components of a Submerged Spheroid

1973 ◽  
Vol 17 (02) ◽  
pp. 72-79
Author(s):  
César Farell ◽  
Oktay Güven
Keyword(s):  
Boundary Condition ◽  
Free Surface ◽  
Surface Wind ◽  
Rigid Wall ◽  
The Body ◽  
Viscous Drag ◽  
Viscous Resistance ◽  
Surface Boundary ◽  
Total Resistance ◽  
Viscous Effects

Towing-tank measurements of the viscous resistance of a spheroid model by means of wake surveys together with total resistance measurements show that the proximity of the free surface greatly influences the viscous resistance, which becomes much larger than the deep-submergence resistance as the spheroid approaches the free surface. Wind tunnel measurements reveal a similar effect of a rigid wall on the viscous drag of a body. The values of the wave resistance obtained as the difference between the measured values of total resistance and viscous resistance are found to be in agreement, for the range of Froude numbers investigated, with the analytical results obtained neglecting viscous effects and linearizing the free-surface boundary condition, but satisfying exactly the boundary condition on the surface of the body.

scholarly journals Soft mobile robot inspired by animal-like running motion

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tongil Park ◽  
Youngsu Cha
Keyword(s):  
Numerical Simulation ◽  
Mobile Robot ◽  
Body Length ◽  
The Body ◽  
Legged Robots ◽  
Main Body ◽  
Soft Robots ◽  
Activation Condition ◽  
Physical Mechanisms ◽  
Amplitude Difference

Abstract There is a considerable demand for legged robots with exploring capabilities such as passing through narrow pathways. Soft robots can provide a solution for such applications. Here, we propose a soft legged mobile robot with bimorph piezoelectric main body and pre-curved piezoelectric legs. We experimentally demonstrate the performance of the soft mobile robot. The mobile robot can move 70% of the body length per second. In addition, we investigate physical mechanisms behind the locomotion of the mobile robot using a numerical simulation. Interestingly, the mobile robot generates an animal-like running motion. We find that the amplitude difference of the legs, depending on the leg activation condition, may affect the performance of the robot. We also confirm that the soft mobile robot can maintain the movement under impulsive shock owing to its flexibility.

scholarly journals How Euglena gracilis swims: flow field reconstruction and analysis

2020 ◽  
Author(s):  
Nicola Giuliani ◽  
Massimiliano Rossi ◽  
Giovanni Noselli ◽  
Antonio DeSimone
Keyword(s):  
Flow Field ◽  
Euglena Gracilis ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
The Body ◽  
Coarse Grained ◽  
Optimal Interpolation ◽  
Flow Field Reconstruction ◽  
Surrounding Fluid

AbstractEuglena gracilis is a unicellular organism that swims by beating a single anterior flagellum. We study the nonplanar waveforms spanned by the flagellum during a swimming stroke, and the three-dimensional flows that they generate in the surrounding fluid.Starting from a small set of time-indexed images obtained by optical microscopy on a swimming Euglena cell, we construct a numerical interpolation of the stroke. We define an optimal interpolation (which we call synthetic stroke) by minimizing the discrepancy between experimentally measured velocities (of the swimmer) and those computed by solving numerically the equations of motion of the swimmer driven by the trial interpolated stroke. The good match we obtain between experimentally measured and numerically computed trajectories provides a first validation of our synthetic stroke.We further validate the procedure by studying the flow velocities induced in the surrounding fluid. We compare the experimentally measured flow fields with the corresponding quantities computed by solving numerically the Stokes equations for the fluid flow, in which the forcing is provided by the synthetic stroke, and find good matching.Finally, we use the synthetic stroke to derive a coarse-grained model of the flow field resolved in terms of a few dominant singularities. The far field is well approximated by a time-varying Stresslet, and we show that the average behavior of Euglena during one stroke is that of an off-axis puller. The reconstruction of the flow field closer to the swimmer body requires a more complex system of singularities. A system of two Stokeslets and one Rotlet, that can be loosely associated with the force exerted by the flagellum, the drag of the body, and a torque to guarantee rotational equilibrium, provides a good approximation.

Bionic design of the body of tank-like climbing robot

2012 ◽  
Author(s):  
Yongjie Zhang ◽  
Xuan Wu ◽  
Yanwei Liu ◽  
Chongyang Hu ◽  
Shaoming Sun ◽  
...  
Keyword(s):  
The Body ◽  
Climbing Robot ◽  
Bionic Design

scholarly journals Soft Controllable Carbon Fibre-based Piezoresistive Self-Sensing Actuators

Actuators ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 79
Author(s):  
Min Pan ◽  
Chenggang Yuan ◽  
Hastha Anpalagan ◽  
Andrew Plummer ◽  
Jun Zou ◽  
...  
Keyword(s):  
Carbon Fibre ◽  
Position Control ◽  
Control Method ◽  
Feedforward Control ◽  
The Body ◽  
Physical Contact ◽  
Sensing Element ◽  
Resistance Change ◽  
Soft Robots ◽  
Loop Control

Soft robots and devices exploit deformable materials that are capable of changes in shape to allow conformable physical contact for controlled manipulation. While the use of embedded sensors in soft actuation systems is gaining increasing interest, there are limited examples where the body of the actuator or robot is able to act as the sensing element. In addition, the conventional feedforward control method is widely used for the design of a controller, resulting in imprecise position control from a sensory input. In this work, we fabricate a soft self-sensing finger actuator using flexible carbon fibre-based piezoresistive composites to achieve an inherent sensing functionality and design a dual-closed-loop control system for precise actuator position control. The resistance change of the actuator body was used to monitor deformation and fed back to the motion controller. The experimental and simulated results demonstrated the effectiveness, robustness and good controllability of the soft finger actuator. Our work explores the emerging influence of inherently piezoresistive soft actuators to address the challenges of self-sensing, actuation and control, which can benefit the design of next-generation soft robots.

Sign in / Sign up

Export Citation Format

Share Document