High Energy Irradiation at the Leading Tip of Moving Diatoms Causes a Rapid Change of Cell Direction

Cohn, Stanley A.; Spurck, Timothy P.; Pickett‐Heaps, Jeremy D.

doi:10.1080/0269249x.1999.9705466

Cited by 29 publications

(23 citation statements)

References 31 publications

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“…These results, together with the experiments on multiple consecutive trailing-end irradiations, confirm the suggestions made from our earlier work (Cohn et al 1999(Cohn et al , 2004) that high level irradiation at the trailing end represses subsequent direction changes, biasing the cells to keep moving in the same direction. Thus, repression of direction changes for a cell moving away from the light effectively represents an out-of-light response.…”

Section: Discussionsupporting

confidence: 90%

“…Leading-end irradiations generated a 2-3 fold repression of response, which was maximal about 15-60 s after the initial irradiation, while trailing-end irradiation generated a 3-6 fold repression, which often lasted longer. Such differences might suggest that the high light irradiation at the trailing end simply solidifies the pre-existing cellular motility structure and organization, while high light irradiations at the leading end triggers the cell to change direction, and then causes repression briefly, to avoid rapid cell oscillations (as seen when the entire cell is irradiated, Cohn et al 1999).…”

Section: Discussionmentioning

confidence: 99%

“…This assay was an adaptation of several previously described assays (Wilson & Forer 1987, Spurck et al 1990, Cohn et al 1999. Samples of cultured diatom cells were isolated by micropipet, rinsed three times in fresh DM and transferred to a glass slide that had two thin spacing strips of VALAP (Vaseline: lanolin: paraffin 1:1:1 by weight) added to prevent crushing of cells.…”

Section: Irradiation Assaysmentioning

confidence: 99%

“…Pennate, benthic diatoms are often known to display active cell motility within the confines of their local substrata (Häder & Hoiczyk 1992, Cohn & Disparti 1994, Serôdio et al 2006, Du et al 2010, with movements that are strongly sensitive to the surrounding light and environmental conditions (Cohn & Disparti 1994, Cohn & Weitzell 1996, Cohn et al 1999, Falciatore et al 2000, Cohn 2001, Serôdio et al 2006. The movement of pennate diatoms is not only crucial for their own ecological success, but their motile secretions are considered to be responsible for significant ecological development and stabilization of the sediments in which they reside (Paterson 1989 Specifically, the direction of cell movement seems strongly correlated with the quality of light exposed on the tips of the cells (Nultsch 1971, 1975, Wenderoth 1982, Nultsch & Häder 1988, Cohn et al 2004, with cells displaying either positive (step-up; out-of-light) or negative (step-down; into light) photophobic responses depending on the light received on each end of the cell.…”

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of light-stimulated motility responses in three diatom species

et al. 2015

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Diatoms have long been known to be photosensitive, altering the direction of their movement in response to changes in ambient light conditions detected at the tips of the cells. In order to better understand the light conditions responsible for triggering positive photophobic (out-of-light) and negative photophobic (into-light) responses of diatoms, cells from three species of diatoms, Craticula cuspidata (Kützing) D.G. Mann, Stauroneis phoenicenteron (Nitzsch) Ehrenberg, and Pinnularia viridis (Nitzsch) Ehrenberg, were irradiated at their leading or trailing ends during cell movement. The response times for direction changes when cells were irradiated at various irradiance levels and wavelengths were measured to determine the quality of light responsible for eliciting cell direction changes in each of the three species. All three species displayed strong out-of-light responses at the highest irradiances measured. Craticula cuspidata cells displayed negative photophobic sensitivity (into-light) responses in moderate level blue light, while S. phoenicenteron cells showed into-light responses with low-level red light. Pinnularia viridis cells showed less responsiveness to blue and green light than the other two species, and almost no sensitivity to red light. By re-irradiating cells a second time after a previous leading or trailing end irradiation, we observed a 2-3 fold (leading) or 3-8 fold (trailing) motility repression, caused by the initial light exposures, which lasted for approximately 30-60 sec. Irradiating the cells multiple times, upon each direction change, indicated some degree of habituation to irradiation over time. Multiple consecutive irradiations of the trailing end of diatoms resulted in strong repression of any direction change, with cells continuing to move in the same direction for up to 20 min; this repression became reduced as the interval time between trailing-end irradiations increased. These results suggest that diatoms display species-specific physiological responses to light irradiations that may help them to appropriately respond to ambient light conditions, and better organize and succeed within larger algal or multi-species diatom assemblages.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Irradiation Assaysmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparative analysis of light-stimulated motility responses in three diatom species

et al. 2015

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“…The four species used in this study have previously been shown to differ from one another in terms of magnitude of speed generated, wavelength sensitivity to light, and strength of adhesion to substrata (Cohn & Disparti 1994, Cohn & Weitzell 1996, Cohn et al 1999. And yet, the four species show a remarkable uniformity in their loss of motility at about 35°C.…”

Section: Discussionmentioning

confidence: 92%

The Effect of Temperature and Mixed Species Composition on Diatom Motility and Adhesion

et al. 2003

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Four species of biraphid pennate diatoms (Craticula cuspidata (Kiitzing) D.G. Mann, Stauroneis phoenicenteron (Nitzsch) Ehrenberg, Nitzschia linearis (Agardh) W. Smith, and Pinnularia viridis (Nitzsch) Ehrenberg) were studied to determine the effect of temperature changes on their motility and adhesion to the substratum. The pattern of cell movement in response to temperature was similar in all species; the average cell speed increased with temperature, with a maximal speed at 30-35°C. Temperatures > 35OC caused a rapid decrease in cell speed, with cells showing little movement at 40°C; the shape of the temperature profile was nearly identical in all species. The loss of motility above the threshold was not due to cell death as cells exposed to 42°C could recover movement when cooled. In contrast to temperature effects on cell movement, its effect on adhesion for all four species showed distinct qualitative differences. The adhesion of P. viridis and S. phoenicenteron to a glass substrate decreased from 20°C to 35"C, but increased slightly at 45OC. The loss of adhesion in S. phoenicenteron was not quite as severe as in P. viridis, with the latter showing little ability to remain adhered at higher temperatures. Nitzschia linearis demonstrated a higher degree of cell adhesion between 5 and 45°C than C. cuspidata, with both species showing little change in adhesion over the temperature range. Flume studies also demonstrated that P. viridis decreased its adhesion as temperature increased, while S. phoenicenteron maintained or slightly increased its adhesion. The lack of correlation between the adhesion and speed responses to temperature changes and the uniformity in the shape of the temperature/speed profile for all four species suggest that alterations in adhesion characteristics are not directly responsible for regulating cell speed. Both cell speed and adhesion were sensitive to the presence of a second species. Pinnularia viridis displayed lower adhesion in dual-species test samples, and exhibited significantly reduced average speed in the presence of S. phoenicenteron, but not when co-incubated with C. cuspidata. In contrast, S. phoenicenteron showed no change in adhesion in the presence of P. viridis. Additional species had no effect on the cell speed of either C. cuspidata or S. phoenicenteron, while C. cuspidata did show reduced adhesion in the presence of P. viridis. Our results suggest that ecologically important behaviours such as movement and adhesion can respond not only to environmental factors such as temperature, but also to the presence or absence of other diatom species.

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On Light and Diatoms: A Photonics and Photobiology Review

Ghobara

Mazumder

Vinayak

et al. 2019

Diatoms: Fundamentals and Applications

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High Energy Irradiation at the Leading Tip of Moving Diatoms Causes a Rapid Change of Cell Direction

Cited by 29 publications

References 31 publications

Comparative analysis of light-stimulated motility responses in three diatom species

Comparative analysis of light-stimulated motility responses in three diatom species

The Effect of Temperature and Mixed Species Composition on Diatom Motility and Adhesion

On Light and Diatoms: A Photonics and Photobiology Review

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