Effect of Shaking on the Growth of Diluted Cultures of <i>Tetrahymena</i>

Hellung‐Larsen, Per; Lyhne, Inger

doi:10.1111/j.1550-7408.1992.tb01328.x

Cited by 12 publications

(6 citation statements)

References 16 publications

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“…Fifty-milliliter cultures of B7 cells were grown at 35C in 500-ml Fernbach flasks. The cultures were kept unshaken to avoid cell division stress (Hellung-Larsen and Lyhne, 1992). Cells in exponential growth phase were used to inoculate the cultures to a concentration of about 10 4 cells ml" 1 .…”

Section: Cell Culturesmentioning

confidence: 99%

Physiological Parameters Affecting the Chemosensory Response of Tetrahymena

Koppelhus

Hellung‐Larsen²,

Leick³

1994

The Biological Bulletin

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We have investigated the significance of a number of physiological parameters in the preparation of cells for experiments on chemokinesis in Tetrahymena. The study comprises (1) growth state of the cells, (2) composition of the starvation medium, (3) concentration of cells during starvation, (4) oxygen saturation of the starvation medium, (5) temperature during starvation, and (6) starvation period. By controlling the physiological state of the cells, we significantly improved the reproducibility of the results obtained in assays for chemokinesis in Tetrahymena. In short, cells optimal for chemokinesis at an assay temperature of 28 degrees C should be starved from the exponential growth phase in a concentration below 2 x 10(5) cells ml-1 for 10-20 h. The surface-to-volume ratio of the starvation medium--water or Hepes buffer--should be about 5 cm-1 (or more) to ensure more than 95% oxygen saturation of the starvation medium. Maximal chemosensory responses were obtained if the cells were starved at 21 degrees C. The chemokinetic potential of the cells decreased significantly, as did the levels of the ratio of ATP to ADP, if cells were starved at higher temperatures. A tentative correlation between the ATP level in the cells and the chemosensory potential of the cells has been found. We suggest that chemokinesis is a constant quality of Tetrahymena, because we found no sign that prolonged starvation or other changes applied to the cells produced an up-regulation of the chemosensory response. Apparently, starvation is obligatory only to remove the growth medium (which is itself a very potent attractant), thereby making the cells sensitive to the chemoattractants.

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Section: Cell Culturesmentioning

confidence: 99%

Physiological Parameters Affecting the Chemosensory Response of Tetrahymena

Koppelhus

Hellung‐Larsen²,

Leick³

1994

The Biological Bulletin

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“…Such a difference could be explained by an increased sensitivity of this strain to a homogeneous distribution of oxygen in the medium (e.g. due to preferential positioning in the water column), which should have been favoured by gentle agitation in ‘IF1’ (Hellung‐Larsen & Lyhne, 1992 ; Brown et al., 2003 ). Since the agitation test carried out with strain D2 suggested no intrinsic impact of shaking on cultures (Appendix S2.3 ), its contribution to the bioavailability of dissolved oxygen was likely greater than that of opening the cap in ‘IF2’, explaining the strong difference between these two intermediate treatments.…”

Section: Discussionmentioning

confidence: 99%

Demography and movement patterns of a freshwater ciliate: The influence of oxygen availability

Brans,

Manzi,

Jacob

et al. 2024

Ecology and Evolution

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In freshwater habitats, aerobic animals and microorganisms can react to oxygen deprivation by a series of behavioural and physiological changes, either as a direct consequence of hindered performance or as adaptive responses towards hypoxic conditions. Since oxygen availability can vary throughout the water column, different strategies exist to avoid hypoxia, including that of active ‘flight’ from low‐oxygen sites. Alternatively, some organisms may invest in slower movement, saving energy until conditions return to more favourable levels, which may be described as a ‘sit‐and‐wait’ strategy. Here, we aimed to determine which, if any, of these strategies could be used by the freshwater ciliate Tetrahymena thermophila when faced with decreasing levels of oxygen availability in the culture medium. We manipulated oxygen flux into clonal cultures of six strains (i.e. genotypes) and followed their growth kinetics for several weeks using automated image analysis, allowing to precisely quantify changes in density, morphology and movement patterns. Oxygen effects on demography and morphology were comparable across strains: reducing oxygen flux decreased the growth rate and maximal density of experimental cultures, while greatly expanding the duration of their stationary phase. Cells sampled during their exponential growth phase were larger and had a more elongated shape under hypoxic conditions, likely mirroring a shift in resource investment towards individual development rather than frequent divisions. In addition to these general patterns, we found evidence for intraspecific variability in movement responses to oxygen limitation. Some strains showed a reduction in swimming speed, potentially associated with a ‘sit‐and‐wait’ strategy; however, the frequent alteration of movement paths towards more linear trajectories also suggests the existence of an inducible ‘flight response’ in this species. Considering the inherent costs of turns associated with non‐linear movement, such a strategy may allow ciliates to escape suboptimal environments at a low energetic cost.

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“…To achieve a high surface area‐to‐volume ratio that ensured optimal oxygenation of the medium, 100 ml of culture medium were used in a 2.8‐liter Fernbach flask. The flask was incubated at constant temperature without shaking, which was avoided because it can have an adverse effect on doubling time (Hellung‐Larsen and Lyhne 1992). For rapid determinations of cell density, absorbance at 600 nm was measured.…”

Section: Methodsmentioning

confidence: 99%

MYO1, a Novel, Unconventional Myosin Gene Affects Endocytosis and Macronuclear Elongation inTetrahymena thermophila

Williams

Hosein

Garcés

et al. 2000

J Eukaryotic Microbiology

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Targeted gene disruption was used to investigate the function of MYO1, an unconventional myosin gene in Tetrahymena thermophila. Phenotypic analysis of a transformed strain that lacked a functional MYO1 gene was conducted at both 20 degrees C and 35 degrees C. At either temperature the delta MYO1 strain had a smaller cytoplasm/nucleus ratio than wild type. At 20 degrees C, delta MYO1 populations had a longer doubling time than wild type, lower saturation density, and a reduced rate of food vacuole formation. However, at 35 degrees C, these characteristics were comparable to wild type. Although micronuclear division and cytokinesis appeared normal in delta MYO1 cells, failure of the macronucleus to elongate properly resulted in unequal segregation of macronuclear DNA in cells maintained at either 20 degrees C or 35 degrees C.

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Effect of Shaking on the Growth of Diluted Cultures of Tetrahymena

Cited by 12 publications

References 16 publications

Physiological Parameters Affecting the Chemosensory Response of Tetrahymena

Physiological Parameters Affecting the Chemosensory Response of Tetrahymena

Demography and movement patterns of a freshwater ciliate: The influence of oxygen availability

MYO1, a Novel, Unconventional Myosin Gene Affects Endocytosis and Macronuclear Elongation inTetrahymena thermophila

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