Pattern Swimming by Polytomella agilis

Gittleson, S. M.; Jahn, Theodore L.

doi:10.1086/282555

Cited by 20 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As noted by Noever (1991), hypergravity during flight experiments occurred and continued for 20·s before and after the short-term (25·s) microgravity, so that the changes in the pattern size were transitional during the limited period of hypergravity and also occurred with the oscillatory changes in gravity (normalhyper--micro--hyper--normal) within a few minutes. It might be possible that the rapid oscillatory changes in gravity affect the pattern-forming response of organisms, which occurs over a time period of several tens of seconds (Gittleson and Jahn, 1968;Wille and Ehret, 1968;Childress et al, 1975). In addition, it is possible that the direction of gravity vector changed with respect to the suspension chamber under hypergravity performed by pulling up and down the trajectory of the airplane in the parabolic flight maneuvers.…”

Section: Discussionmentioning

confidence: 99%

“…These facts indicate that bioconvective pattern formation is highly sensitive to the gravity environment. Although parabolic flight is one of a few available experimental tools with which to simulate microgravity in ground-based experiments, oscillatory changes in gravity, which involve alternating phases of different gravities, each lasting only some 20·s, might affect the consequential pattern forming response, which would continue for up to several tens of seconds (Gittleson and Jahn, 1968;Wille and Ehret, 1968;Childress et al, 1975).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Bioconvective pattern formation ofTetrahymenaunder altered gravity

Mogami

Yamane

Gino

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

SUMMARY Bioconvection is a result of the negative gravitactic behavior of microorganisms. When the top-heavy density gradient generated by gravitaxis grows sufficiently large, an overturning convection occurs leading to a formation of characteristic patterns, which involve highly concentrated aggregation of cells into extended two-dimensional structures. Although gravity is a crucial factor, few experiments have been done with reference to gravity as an experimental variable. In order to gain an insight into the hydrodynamic as well as biological dependence of the convective motion on gravity, we investigated changes in bioconvective patterns of Tetrahymena under altered gravity acceleration generated by a long-arm centrifuge. Bioconvective patterns recorded of three different cell strains (T. pyriformis, T. thermophila and its behavioral mutant,TNR) were analyzed quantitatively using space-time plot and Fourier analysis. For example, under subcritical conditions, when T. pyriformis(1.0×106 cells ml-1) was placed in a 2 mm-deep chamber, no spatial pattern was observed at 1 g. When the suspension was centrifuged, however, patterns began to appear as acceleration increased over a critical value (1.5 g), and then remained steady. The formation was reversible, i.e. the patterns disappeared again as acceleration decreased. Under supracritical conditions, i.e. when a suspension of the same density was placed in a 4 mm-deep chamber, a steady state pattern was formed at 1 g. The pattern spacing in the steady state was observed to decrease stepwise in response to step increases in acceleration. Fourier analysis demonstrated that for TNR the mean wave number changed almost simultaneously with step changes in acceleration, whereas the responses were less sharp in the wild-type strains. This may suggest that the locomotor phenotype of the cell, such as its avoiding response ability, has a crucial role in bioconvective pattern formation. These findings are discussed in relation to former theoretical studies.

show abstract

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Bioconvective pattern formation ofTetrahymenaunder altered gravity

Mogami

Yamane

Gino

et al. 2004

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…Regular patterns spontaneously emerge in the suspension of some swimming microorganisms, even if initially the suspension is completely homogenous. Protists, particularly the ciliate Tetrahymena and the flagellates Euglena, Polytomella, and Chlamydomonas, have been extensively used for experimental studies on bioconvection (Wager, 1911;Robbins, 1952;Loefer and Mefferd, 1952;Gittleson and Jahn, 1968;Levandowsky et al, 1975;Fornshell, 1978;Kessler, 1985a;Yamamoto et al, 1992;Bees and Hill, 1997;Mogami et al, 2004;Akiyama et al, 2005;Nguyen-Quang et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Gravity-Dependent Changes in Bioconvection ofTetrahymenaandChlamydomonasDuring Parabolic Flight: Increases in Wave Number Induced by Pre- and Post-Parabola Hypergravity

et al. 2011

View full text Add to dashboard Cite

Bioconvection emerges in a dense suspension of swimming protists as a consequence of their negative-gravitactic upward migration and later settling as a blob of density greater than that of water. Thus, gravity is an important parameter governing bioconvective pattern formation. However, inconsistencies are found in previous studies dealing with the response of bioconvection patterns to increased gravity acceleration (hypergravity); the wave number of the patterns has been reported to decrease during the hypergravity phases of parabolic aircraft flight, while it increases in centrifugal hypergravity. In this paper, we reassess the responses of bioconvection to altered gravity during parabolic flight on the basis of vertical and horizontal observations of the patterns formed by Tetrahymena thermophila and Chlamydomonas reinhardtii. Spatiotemporal analyses of the horizontal patterns revealed an increase in the pattern wave number in both pre- and post-parabola hypergravity. Vertical pattern analysis was generally in line with the horizontal pattern analysis, and further revealed that hypergravity-induced changes preceded at the top layer of the suspensions while microgravity-induced changes appeared to occur from the bottom part of the settling blobs. The responses to altered gravity were rather different between the two sample species: T. thermophila tended to drastically modify its bioconvection patterns in response to changes in gravity level, while the patterns of C. reinhardtii responded to a much lesser extent. This difference can be attributed to the distinct physical and physiological properties of the individual organisms, suggesting a significant contribution of the gyrotactic property to the swimming behavior of some protists.

show abstract