Hydrodynamic functionality of the lorica in choanoflagellates

Choanoflagellates are unicellular eukaryotes that are ubiquitous in aquatic habitats. They have a single flagellum that creates a flow toward a collar filter composed of filter strands that extend from the cell. In one common group, the loricate choanoflagellates, the cell is suspended in an elaborate basket-like structure, the lorica, the function of which remains unknown. Here, we use Computational Fluid Dynamics to explore the possible hydrodynamic function of the lorica. We use the choanoflagellate Diaphaoneca grandis as a model organism. It has been hypothesized that the function of the lorica is to prevent refiltration (flow recirculation) and to increase the drag and, hence, increase the feeding rate and reduce the swimming speed. We find no support for these hypotheses. On the contrary, motile prey are encountered at a much lower rate by the loricate organism. The presence of the lorica does not affect the average swimming speed, but it suppresses the lateral motion and rotation of the cell. Without the lorica, the cell jiggles from side to side while swimming. The unsteady flow generated by the beating flagellum causes reversed flow through the collar filter that may wash away captured prey while it is being transported to the cell body for engulfment. The lorica substantially decreases such flow, hence it potentially increases the capture efficiency. This may be the main adaptive value of the lorica.

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Abundant and diverse Tetrahymena species living in the bladder traps of aquatic carnivorous Utricularia plants

Scientific Reports ◽

10.1038/s41598-019-50123-1 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 2

Author(s):

Chao-Yin Cheng ◽

Shang-Lin Chang ◽

I-Ting Lin ◽

Meng-Chao Yao

Keyword(s):

New Species ◽

Tetrahymena Thermophila ◽

Model Organism ◽

Carnivorous Plant ◽

Laboratory Model ◽

Natural Habitats ◽

Additional Species ◽

Unicellular Eukaryotes ◽

Wide Range ◽

Excellent Candidate

Abstract Ciliates are unicellular eukaryotes known for their cellular complexity and wide range of natural habitats. How they adapt to their niches and what roles they play in ecology remain largely unknown. The genus Tetrahymena is among the best-studied groups of ciliates and one particular species, Tetrahymena thermophila, is a well-known laboratory model organism in cell and molecular biology, making it an excellent candidate for study in protist ecology. Here, based on cytochrome c oxidase subunit I (COX1) gene barcoding, we identify a total of 19 different putative Tetrahymena species and two closely related Glaucoma lineages isolated from distinct natural habitats, of which 13 are new species. These latter include 11 Tetrahymena species found in the bladder traps of Utricularia plants, the most species-rich and widely distributed aquatic carnivorous plant, thus revealing a previously unknown but significant symbiosis of Tetrahymena species living among the microbial community of Utricularia bladder traps. Additional species were collected using an artificial trap method we have developed. We show that diverse Tetrahymena species may live even within the same habitat and that their populations are highly dynamic, suggesting that the diversity and biomass of species worldwide is far greater than currently appreciated.

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Numerical Analysis of the Flow Within a Clark Turbocharger Compressor

ASME 2004 Internal Combustion Engine Division Fall Technical Conference ◽

10.1115/icef2004-0974 ◽

2004 ◽

Author(s):

K. S. Chapman ◽

Sudip Dey ◽

Ali Keshavarz

Keyword(s):

Experimental Data ◽

Numerical Simulation ◽

Numerical Analysis ◽

Flow Field ◽

Field Test ◽

Numerical Results ◽

Operating Conditions ◽

Flow Recirculation ◽

Flow Through

The flow field within a Clark turbocharger compressor has been thoroughly analyzed by numerical simulation. The numerical simulation was validated with experimental data collected from field test sites. The numerical results are found to closely match the experimental data. Once validated, the numerical simulation was used to investigate the flow field within the turbocharger compressor under a variety of operating conditions. Several regions of flow recirculation were identified that restrict flow through the turbocharger.

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IMPACT OF NURSERY USING DIFFERENT PHYSICAL FILTRATION SYSTEM ON HEMOLYMPH GLUCOSE LEVEL AND SURVIVAL RATE OF SPINY LOBSTER JUVENILE Panulirus homarus

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.29244/jitkt.v9i2.19291 ◽

2018 ◽

Vol 9 (2) ◽

pp. 569-575 ◽

Cited By ~ 1

Author(s):

Ega Aditya Prama ◽

Eddy Supriyono ◽

Kukuh Nirmala ◽

Kukuh Adiyana

Keyword(s):

Survival Rate ◽

Stress Response ◽

Feeding Rate ◽

Spiny Lobster ◽

Initial Weight ◽

Juvenile Period ◽

Early Juvenile ◽

Filtration System ◽

Trash Fish ◽

Flow Through

The problems in culture of early juvenile phase of spiny lobster Panulirus homarus is low survival rate of the seed. One of strategies to improve production is using filtration system during nursery of spiny lobster. The aim of this study to evaluate differentation of physical filtration system on responsse stress and survival rate of juvenile P. homarus. Experimental design of this study consisted of four treatments and two replications. The treatments were using flow through system without protein skimmer and filter (K), filtration system with protein skimmer (SK), filtration system with top filter (F) and filtration system with combinations of protein skimmer and top filter (SKF). P. homarus with initial weight 0.18+0.01 g were cultured for 60 days with density 250 lobster/tank. During maintenance, P. homarus were fed trash fish with feeding rate 20% of body weight. Parameters of glucose hemolymph were evaluated to determine stress response. Stress response was determined at day 0, 6, 20 and 60. Parameters of survival rate were determined at the end of experiment. The result showed that the treatment of filtration system with combination of protein skimmer and top filter (SKF) decreased stress responsse by decreasing glucose hemolymph of juvenile P. homarus during maintenance. Survival rate also higher (P<0.05) in treatment SKF (33.2%) than other treatments. It is concluded that SKF was the best physical filtration system for juvenile period of spiny lobster P. homarus Keywords: filtration system, glucose hemolymph, spiny lobster, survival rate

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Experimental investigation using micro-PIV of the effect of microRNA-1 deficiency on motility in Caenorhabditis elegans

10.1101/2020.06.16.119396 ◽

2020 ◽

Author(s):

S. Ravikumar ◽

M. Fedrizzi ◽

R. Prabhakar ◽

R. Pocock ◽

M. K. O’Bryan ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Swimming Speed ◽

Model Organism ◽

The Body ◽

Wild Type ◽

Mean Power ◽

C Elegans ◽

Micro Piv ◽

Image Velocimetry ◽

Beating Frequency

AbstractCaenorhabditis elegans is a microscopic nematode used extensively as a model organism in studies of neuromuscular function and neurodegenerative disorders. A mutation in mir-1 affects signalling at the neuromuscular junction. We investigate the effect of this mutation on the propulsive power exerted by nematodes as they grow in size with age. We compare the motility of wild-type and mir-1(gk276) mutant nematodes in a Newtonian fluid using a two-component, two dimensional (2C-2D) Digital Microscopic Particle Image Velocimetry (µ-PIV) technique. Beating amplitudes of the head and tail, the wavelength of undulatory waves and the swimming speed scale linearly with size in both the wild-type and mutant strains. The beating frequency is independent of size or position along the body. Differences in the magnitudes of these kinematic parameters between the two strains, however, grow systematically with age. The swimming speed scales linearly with the wave speed of the neuromuscular undulation in both nematode strains with a conserved ratio. The magnitude of mean power and mean local fluid circulation in the mutant is significantly lower compared to those of the wild-type animals of the same age. This indicates that a mutation in mir-1 adversely affects motility in C. elegans.

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Food-dependent aggregation and mobility of the water fleas Ceriodaphnia dubia and Daphnia pulex

Canadian Journal of Zoology ◽

10.1139/z94-163 ◽

1994 ◽

Vol 72 (7) ◽

pp. 1217-1226 ◽

Cited By ~ 28

Author(s):

K. M. Cuddington ◽

E. McCauley

Keyword(s):

Swimming Speed ◽

Daphnia Pulex ◽

Food Concentration ◽

Ceriodaphnia Dubia ◽

General Interest ◽

High Food ◽

Predator Prey ◽

Individual Mobility ◽

Flow Through ◽

Filtering Rates

In this paper, we show that two freshwater cladoceran zooplankters (Ceriodaphnia dubia and Daphnia pulex) differ in swimming speed and ability to locate local regions of high food concentration in a flow-through circular chamber. This comparison is of general interest, since models of spatially structured predator–prey dynamics have predicted that differences in individual mobility and foraging behaviour may affect spatial distributions and, consequently, population dynamics. Daphnia pulex was more mobile than C. dubia, and also located the high end of a food gradient while C. dubia did not. It seems likely that the mechanisms used by D. pulex to locate these regions are related to ingestion and (or) filtering rates. It was hypothesized that individuals reduce their swimming speed in order to linger in regions of high food concentration. Differences in mobility and behaviour between C. dubia and D. pulex were used to generate hypotheses about the distribution and stability of their respective populations. Specifically, it was predicted that C. dubia populations would have a more aggregated and, consequently, a more stable population in smaller environments than D. pulex.

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HAP2-Mediated Gamete Fusion: Lessons From the World of Unicellular Eukaryotes

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.807313 ◽

2022 ◽

Vol 9 ◽

Author(s):

Jennifer F. Pinello ◽

Theodore G. Clark

Keyword(s):

Tetrahymena Thermophila ◽

Model Organism ◽

Mating Types ◽

Protozoan Parasites ◽

Free Living ◽

Gamete Fusion ◽

Unicellular Eukaryotes ◽

Current State ◽

The World

Most, if not all the cellular requirements for fertilization and sexual reproduction arose early in evolution and are retained in extant lineages of single-celled organisms including a number of important model organism species. In recent years, work in two such species, the green alga, Chlamydomonas reinhardtii, and the free-living ciliate, Tetrahymena thermophila, have lent important new insights into the role of HAP2/GCS1 as a catalyst for gamete fusion in organisms ranging from protists to flowering plants and insects. Here we summarize the current state of knowledge around how mating types from these algal and ciliate systems recognize, adhere and fuse to one another, current gaps in our understanding of HAP2-mediated gamete fusion, and opportunities for applying what we know in practical terms, especially for the control of protozoan parasites.

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X-Ray Analysis of Frozen Hydrated Sections:The Unconventional Approach

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100056065 ◽

1982 ◽

Vol 40 ◽

pp. 754-757

Author(s):

R. Beeuwkes ◽

A. Saubermann ◽

P. Echlin ◽

S. Churchill

Keyword(s):

Ratio Method ◽

Frozen Sections ◽

Technical Problems ◽

Sample Handling ◽

X Ray ◽

Common Group ◽

Ideal Method ◽

Classic Paper ◽

Physical Principles ◽

The Ideal

Fifteen years ago, Hall described clearly the advantages of the thin section approach to biological x-ray microanalysis, and described clearly the ratio method for quantitive analysis in such preparations. In this now classic paper, he also made it clear that the ideal method of sample preparation would involve only freezing and sectioning at low temperature. Subsequently, Hall and his coworkers, as well as others, have applied themselves to the task of direct x-ray microanalysis of frozen sections. To achieve this goal, different methodological approachs have been developed as different groups sought solutions to a common group of technical problems. This report describes some of these problems and indicates the specific approaches and procedures developed by our group in order to overcome them. We acknowledge that the techniques evolved by our group are quite different from earlier approaches to cryomicrotomy and sample handling, hence the title of our paper. However, such departures from tradition have been based upon our attempt to apply basic physical principles to the processes involved. We feel we have demonstrated that such a break with tradition has valuable consequences.

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Development of apical pits in chloride cells of the gills of Pimephales promelas after chronic exposure to acid water

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100076044 ◽

1983 ◽

Vol 41 ◽

pp. 462-463

Author(s):

Richard L. Leino ◽

Jon G. Anderson ◽

J. Howard McCormick

Keyword(s):

Confidence Interval ◽

Chronic Exposure ◽

Lake Superior ◽

Pimephales Promelas ◽

Chloride Cells ◽

Fathead Minnows ◽

Secondary Lamellae ◽

Untreated Water ◽

Water Ph ◽

Flow Through

Groups of 12 fathead minnows were exposed for 129 days to Lake Superior water acidified (pH 5.0, 5.5, 6.0 or 6.5) with reagent grade H2SO4 by means of a multichannel toxicant system for flow-through bioassays. Untreated water (pH 7.5) had the following properties: hardness 45.3 ± 0.3 (95% confidence interval) mg/1 as CaCO3; alkalinity 42.6 ± 0.2 mg/1; Cl- 0.03 meq/1; Na+ 0.05 meq/1; K+ 0.01 meq/1; Ca2+ 0.68 meq/1; Mg2+ 0.26 meq/1; dissolved O2 5.8 ± 0.3 mg/1; free CO2 3.2 ± 0.4 mg/1; T= 24.3 ± 0.1°C. The 1st, 2nd and 3rd gills were subsequently processed for LM (methacrylate), TEM and SEM respectively.Three changes involving chloride cells were correlated with increasing acidity: 1) the appearance of apical pits (figs. 2,5 as compared to figs. 1, 3,4) in chloride cells (about 22% of the chloride cells had pits at pH 5.0); 2) increases in their numbers and 3) increases in the % of these cells in the epithelium of the secondary lamellae.

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