scholarly journals Hydrodynamics of Prey Capture and Transportation in Choanoflagellates

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 94
Author(s):  
Siv Sørensen ◽  
Seyed Saeed Asadzadeh ◽  
Jens Honoré Walther
Keyword(s):  
Fluid Dynamics ◽  
Transport Mechanism ◽  
Potential Role ◽  
Prey Capture ◽  
Finite Size ◽  
Model Organism ◽  
Alternative Mechanism ◽  
Active Transport Mechanism ◽  
Hydrodynamic Effects ◽  
A Current

Choanoflagellates are unicellular microscopic organisms that are believed to be the closest living relatives of animals. They prey on bacteria through the act of the continuous beating of their flagellum, which generates a current through a crown-like filter. Subsequently, the filter retains bacterial particles from the suspension. The mechanism by which the prey is retained and transported along the filter remains unknown. We report here on the hydrodynamic effects on the transportability of bacterial prey of finite size using computational fluid dynamics. Here, the loricate choanoflagellate Diaphaoneca grandis serves as the model organism. The lorica is a basket-like structure found in only some of the species of choanoflagellates. We find that although transportation does not entirely rely on hydrodynamic forces, such forces positively contribute to the transportation of prey along the collar filter. The aiding effects are most possible in non-loricate choanoflagellate species, as compared to loricate species. As hydrodynamic effects are strongly linked to the beat and shape of the flagellum, our results indicate an alternative mechanism for prey transportation, especially in biological systems where having an active transport mechanism is costly or not feasible. This suggests an additional potential role for flagella in addition to providing propulsion and generating feeding currents.

scholarly journals The benefits of planar circular mouths on suction feeding performance

2012 ◽  
Vol 9 (73) ◽  
pp. 1767-1773 ◽  
Author(s):  
Tyler Skorczewski ◽  
Angela Cheer ◽  
Peter C. Wainwright
Keyword(s):  
Prey Capture ◽  
Peak Flow ◽  
Mouth Opening ◽  
Suction Feeding ◽  
Flow Rates ◽  
Computational Fluid Dynamics Simulations ◽  
Enhance Efficiency ◽  
And Performance ◽  
Dynamics Simulations ◽  
Hydrodynamic Effects

Suction feeding is the most common form of prey capture across aquatic feeding vertebrates and many adaptations that enhance efficiency and performance are expected. Many suction feeders have mechanisms that allow the mouth to form a planar and near-circular opening that is believed to have beneficial hydrodynamic effects. We explore the effects of the flattened and circular mouth opening through computational fluid dynamics simulations that allow comparisons with other mouth profiles. Compared to mouths with lateral notches, we find that the planar mouth opening results in higher flow rates into the mouth and a region of highest flow that is positioned at the centre of the mouth aperture. Planar mouths provide not only for better total fluid flow rates through the mouth but also through the centre of the mouth near where suction feeders position their prey. Circular mouths are shown to provide the quickest capture times for spherical and elliptical prey because they expose the prey item to a large region of high flow. Planar and circular mouths result in higher flow velocities with peak flow located at the centre of the mouth opening and they maximize the capacity of the suction feeders to exert hydrodynamic forces on the prey.

scholarly journals Heterokairy: a significant form of developmental plasticity?

2016 ◽  
Vol 12 (9) ◽  
pp. 20160509 ◽  
Author(s):  
S. D. Rundle ◽  
J. I. Spicer
Keyword(s):  
Research Agenda ◽  
Developmental Plasticity ◽  
Potential Role ◽  
Research Effort ◽  
Adaptive Significance ◽  
Research Interest ◽  
Adaptive Plasticity ◽  
Comparative Embryology ◽  
A Current

There is a current surge of research interest in the potential role of developmental plasticity in adaptation and evolution. Here we make a case that some of this research effort should explore the adaptive significance of heterokairy, a specific type of plasticity that describes environmentally driven, altered timing of development within a species. This emphasis seems warranted given the pervasive occurrence of heterochrony, altered developmental timing between species, in evolution. We briefly review studies investigating heterochrony within an adaptive context across animal taxa, including examples that explore links between heterokairy and heterochrony. We then outline how sequence heterokairy could be included within the research agenda for developmental plasticity. We suggest that the study of heterokairy may be particularly pertinent in (i) determining the importance of non-adaptive plasticity, and (ii) embedding concepts from comparative embryology such as developmental modularity and disassociation within a developmental plasticity framework.

Particle-Laden Turbulence: Progress and Perspectives

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Luca Brandt ◽  
Filippo Coletti
Keyword(s):  
Fluid Dynamics ◽  
Fluid Mechanics ◽  
Online Publication ◽  
Granular Media ◽  
Finite Size ◽  
Spherical Particles ◽  
Annual Review ◽  
Publication Date ◽  
Zero Gravity ◽  
Inertial Particles

This review is motivated by the fast progress in our understanding of the physics of particle-laden turbulence in the last decade, partly due to the tremendous advances of measurement and simulation capabilities. The focus is on spherical particles in homogeneous and canonical wall-bounded flows. The analysis of recent data indicates that conclusions drawn in zero gravity should not be extrapolated outside of this condition, and that the particle response time alone cannot completely define the dynamics of finite-size particles. Several breakthroughs have been reported, mostly separately, on the dynamics and turbulence modifications of small inertial particles in dilute conditions and of large weakly buoyant spheres. Measurements at higher concentrations, simulations fully resolving smaller particles, and theoretical tools accounting for both phases are needed to bridge this gap and allow for the exploration of the fluid dynamics of suspensions, from laminar rheology and granular media to particulate turbulence. Expected final online publication date for the Annual Review of Fluid Mechanics, Volume 54 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

A Review of Some Early Design Practice Using Computational Fluid Dynamics and a Current Perspective

2005 ◽  
Vol 127 (1) ◽  
pp. 5-13 ◽  
Author(s):  
J. H. Horlock ◽  
J. D. Denton
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Gas Turbines ◽  
Design Practice ◽  
Future Developments ◽  
Basic Fluid ◽  
Current Perspective ◽  
Computational Fluid Dynamics Cfd ◽  
A Current ◽  
Empirical Design

In the early development of gas turbines, many empirical design rules were used; for example in obtaining fluid deflection using the deviation from blading angles, in the assumption of zero radial velocities (so-called radial equilibrium) and in expressions for clearance loss (the Lakshminarayana formulas). The validity of some of these rules, and the basic fluid mechanics behind them, is examined by use of modern ideas and computational fluid dynamics (CFD) codes. A current perspective of CFD in design is given, together with a view on future developments.

scholarly journals Genetic suppression of defective profilin by attenuated Myosin II reveals a potential role for Myosin II in actin dynamics in vivo in fission yeast

2020 ◽  
Vol 31 (19) ◽  
pp. 2107-2114 ◽  
Author(s):  
Paola Zambon ◽  
Saravanan Palani ◽  
Shekhar Sanjay Jadhav ◽  
Pananghat Gayathri ◽  
Mohan K. Balasubramanian
Keyword(s):  
Fission Yeast ◽  
Double Mutant ◽  
Potential Role ◽  
Myosin Ii ◽  
Model Organism ◽  
Actin Dynamics ◽  
Mutant Analysis ◽  
Genetic Suppression

This work reveals an in vivo role for Myosin II in actin dynamics, potentially in its disassembly and turnover. The work uses double mutant analysis to arrive at this conclusion using the fission yeast as a model organism.

scholarly journals Possible Active Transport Mechanism in Pharmacokinetics of Flunixin-Meglumin in Rabbits.

2001 ◽  
Vol 63 (8) ◽  
pp. 885-888 ◽  
Author(s):  
Yoshie MIYAZAKI ◽  
Yoshihiro HORII ◽  
Naohiro IKENAGA ◽  
Minoru SHIMODA ◽  
Eiichi KOKUE
Keyword(s):  
Active Transport ◽  
Transport Mechanism ◽  
Active Transport Mechanism

Laticifers of Ficus Carica and Their Potential Role in Plant Defense

IAWA Journal ◽  
2014 ◽  
Vol 35 (2) ◽  
pp. 109-115 ◽  
Author(s):  
C. Kajii ◽  
T. Morita ◽  
K. Kuroda
Keyword(s):  
Potential Role ◽  
Secondary Xylem ◽  
Nile Blue ◽  
Ficus Carica ◽  
Secondary Phloem ◽  
Fast Green ◽  
Cambial Zone ◽  
A Current ◽  
Latex Production

The distribution and structure of laticifers in Ficus carica L. were investigated in a current-year branch and an 8-year-old trunk, using serial sections stained with safranin-fast green or nile blue. In the 8-year-old trunk, laticifers were found not only in the cortex, secondary phloem, and pith, but also in the secondary xylem. The laticifers in the phloem and xylem were of the branched, non-articulated type. In addition, horizontal laticifers extending from the phloem through the cambium to the xylem were found in some rays. Laticifers penetrating the cambial initial layer elongated in the cambial zone without cell division. Activation of latex production occurred after wounding of cortex and phloem, and the latex exuded from the cut site of laticifers into the surrounding wounded tissue and broken cells. The potential role of laticifers in defense of F. carica against certain pathogens is discussed.

Active transport of calcium by the small intestine of the rat

1960 ◽  
Vol 198 (2) ◽  
pp. 263-268 ◽  
Author(s):  
David Schachter ◽  
Eugene B. Dowdle ◽  
Harris Schenker
Keyword(s):  
Small Intestine ◽  
Active Transport ◽  
Transport Mechanism ◽  
Cation Transport ◽  
Maximal Rate ◽  
Active Transport Mechanism ◽  
Serosal Surface ◽  
Proximal Small Intestine ◽  
Active Transfer

The rates of active transport of calcium in vitro by everted gut-sacs prepared from the proximal small intestine of the rat have been quantified and expressed in absolute units. A maximal rate of transport has been measured. The bulk of the calcium transferred to the serosal surface of the gut-sac is ionized calcium, suggesting that the process is an active cation transport mechanism. The active transfer is relatively specific for Ca++, and no significant accumulation of Mg++, Sr++, Ba++ or K+ in the fluid bathing the serosal surface could be demonstrated. The active transport of calcium in vitro is greater with gut-sacs from growing than from older rats, and it is greater with gut-sacs from pregnant than from nonpregnant rats. The results suggest that the active transport mechanism can increase the intestinal absorption of calcium facultatively to meet the needs of the organism.

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