Isolation and Characterization of Chemotaxis Mutants of Chlamydomonas reinhardtii

Abstract

Zoospores of Chlamydomonas reinhardtii exhibit chemotaxis towards maltose, sucrose, xylose, mannitol, and ammonium. Ten independent mutants defective in chemotaxis towards sugars have been isolated. These mutants form five phenotypic classes. Genetic analysis of two mutant strains defective in chemotaxis to maltose (CHE1, CHE3) and two mutant strains defective in chemotaxis to sucrose (CHE2, CHE4) indicated that the defect in them depended on single nuclear recessive mutant alleles. Mutations mal1, mal2, suc1, and suc2 represent four chemotactic loci that are unlinked to the marker mt located on the linkage group VI. Four loci are unlinked to each other. These observations suggest that the mal and the suc loci do not constitute a spatially single functional group.

Phototactic activity inChlamydomonas'non-phototactic' mutants deficient in Ca2+-dependent control of flagellar dominance or in inner-arm dynein

“…2F) might be a reflection of the functioning of multiple pathways with different light-intensity dependencies. Such multiple pathways for motility control might be important not only for producing phototactic behavior but for integrating various signals from external conditions, including chemicals (Hirschberg and Rogers, 1978;Ermilova et al, 1996), gravity (Bean, 1977;Yoshimura et al, 2003) and light.…”

ACETATE IS A CHEMOATTRACTANT FOR THE COLONIAL GREEN ALGA ASTREPHOMENE GUBERNACULIFERA (CHLOROPHYCEAE)1

“…This contrasts with the strong chemoresponse of A. gubernaculifera to acetate. Asterphomene gubernaculifera was not attracted to sugars as was C. reinhardtii (Ermilova et al 1993, 1996) nor to amino acids as were D. tertiolecta (Sjoblad et al 1978b) and D. salina (Kohidai et al 1996), except that phenylalanine attracted both A. gubernaculifera and D. tertiolecta (Sjoblad et al 1978b).…”

“…We used several different methods to demonstrate chemoattraction of A. gubernaculifera by acetate. Within the chlorophytes, Chlamydomonas and the related alga Dunaliella have been reported to be chemoattracted by organic (Sjoblad et al 1978b, Hirschberg and Rodgers 1978, Ermilova et al 1993, 1996, Kohidai et al 1996) and inorganic (Hirschberg and Rodgers 1978, Sjoblad et al 1978b, Sjoblad and Frederikse 1981, Byrne et al 1992) molecules. In general, these studies have shown a consistent attraction of these algae to ammonium ions (Sjoblad et al 1978a, Hirschberg and Rodgers 1978, Sjoblad and Frederikse 1981, Byrne et al 1992) but very little consistency in the response to organic attractants.…”

“…Although not as well known as phototaxis, many algae also show behavioral responses that result in accumulation around certain chemical stimuli (Levandowsky and Hauser 1978, Amsler and Iken 2001). Organisms that have been shown to exhibit such behaviors include several members of the unicellular Volvocales, especially Chlamydomonas and Dunaliella (Frank 1904, Hirschberg and Rodgers 1978, Sjoblad et al 1978a,b, Sjoblad and Frederikse 1981, Byrne et al 1992, Ermilova et al 1993, 1996, Kohidai et al 1996). Genetic analyses have shown the chemoattraction sensory pathway uses some of the same molecular components as the phototactic pathway in C. reinhardtii (Ermilova et al 1998, 2000).…”