Diffusion theory can completely describe the movement of a ciliate along a track of a certain length (L), travelled in a time (t), and with the extremes lying at a distance D. Three important descriptors of this behavior are: (1) the kinetic index (Ik= L/t), namely the average velocity in μm/s, which expresses the state of the “accelerator” of the ciliate; (2) the geometric index (Ig= D/L) measuring the straightness of the track by a dimensionless number. 0 ≤ Ig≤ 1, which expresses the state of the “steering wheel” and represents a sort of “directional efficiency”; and (3) the displacement rate (Rd= D/t), integrating the first two indices and expressing the combined effect of the “accelerator” and the “steering wheel” of the organism with a unique measure (in μm/s), which defines the average displacement rate or the effectiveness of the track in displacing the organism in space. A weighted estimate of general mobility is given by the mobility rate [Rmo= (R̄d.f)creeping- (R̄d.f)swimming], obtained by multiplying the average Rd of the creeping organisms and the average Rd of the swimming organisms by their relative frequencies of occurrence (f), and adding the two products. Values for experimental populations of Oxytricha bifaria (Ciliata, Hypotrichida) maintained at 24, 19, 14, and 9° C demonstrated both the appropriateness and the usefulness of these indices and rates to describe the tracks a posteriori, and to provide measures to reason about their possible adaptive significance.

A Quantitative Approach to Movement, Displacement and Mobility of Protozoa

RICCI, NICOLA;BARBANERA, FILIPPO;ERRA, FABRIZIO
1998

Abstract

Diffusion theory can completely describe the movement of a ciliate along a track of a certain length (L), travelled in a time (t), and with the extremes lying at a distance D. Three important descriptors of this behavior are: (1) the kinetic index (Ik= L/t), namely the average velocity in μm/s, which expresses the state of the “accelerator” of the ciliate; (2) the geometric index (Ig= D/L) measuring the straightness of the track by a dimensionless number. 0 ≤ Ig≤ 1, which expresses the state of the “steering wheel” and represents a sort of “directional efficiency”; and (3) the displacement rate (Rd= D/t), integrating the first two indices and expressing the combined effect of the “accelerator” and the “steering wheel” of the organism with a unique measure (in μm/s), which defines the average displacement rate or the effectiveness of the track in displacing the organism in space. A weighted estimate of general mobility is given by the mobility rate [Rmo= (R̄d.f)creeping- (R̄d.f)swimming], obtained by multiplying the average Rd of the creeping organisms and the average Rd of the swimming organisms by their relative frequencies of occurrence (f), and adding the two products. Values for experimental populations of Oxytricha bifaria (Ciliata, Hypotrichida) maintained at 24, 19, 14, and 9° C demonstrated both the appropriateness and the usefulness of these indices and rates to describe the tracks a posteriori, and to provide measures to reason about their possible adaptive significance.
Ricci, Nicola; Barbanera, Filippo; Erra, Fabrizio
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/48018
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 16
  • ???jsp.display-item.citation.isi??? 16
social impact