scholarly journals Characterization of Chlamydomonas reinhardtii Mutants That Exhibit Strong Positive Phototaxis

Plants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1483
Author(s):  
Jun Morishita ◽  
Ryutaro Tokutsu ◽  
Jun Minagawa ◽  
Toru Hisabori ◽  
Ken-ichi Wakabayashi
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Regulatory Mechanism ◽  
Model Organism ◽  
Negative Phototaxis ◽  
Light Conditions ◽  
Wild Type ◽  
Positive Phototaxis ◽  
Unicellular Green Alga ◽  
Cellular Factors

The most motile phototrophic organisms exhibit photo-induced behavioral responses (photobehavior) to inhabit better light conditions for photosynthesis. The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism to study photobehavior. Several years ago, we found that C. reinhardtii cells reverse their phototactic signs (i.e., positive and negative phototaxis) depending on the amount of reactive oxygen species (ROS) accumulated in the cell. However, its molecular mechanism is unclear. In this study, we isolated seven mutants showing positive phototaxis, even after the induction of negative phototaxis (ap1~7: always positive) to understand the ROS-dependent regulatory mechanism for the phototactic sign. We found no common feature in the mutants regarding their growth, high-light tolerance, and photosynthetic phenotypes. Interestingly, five of them grew faster than the wild type. These data suggest that the ROS-dependent regulation of the phototactic sign is not a single pathway and is affected by various cellular factors. Additionally, the isolation and analyses of mutants with defects in phototactic-sign regulation may provide clues for their application to the efficient cultivation of algae.

scholarly journals Biochemical Characterization of Wild-Type and Mutant Isoamylases of Chlamydomonas reinhardtii Supports a Function of the Multimeric Enzyme Organization in Amylopectin Maturation

2001 ◽  
Vol 125 (4) ◽  
pp. 1723-1731 ◽  
Author(s):  
David Dauvillée ◽  
Christophe Colleoni ◽  
Gregory Mouille ◽  
Matthew K. Morell ◽  
Christophe d'Hulst ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Biochemical Characterization ◽  
Wild Type ◽  
Enzyme Organization

scholarly journals Identification of the agg1 mutation responsible for negative phototaxis in a “wild-type” strain of Chlamydomonas reinhardtii

2016 ◽  
Vol 7 ◽  
pp. 379-385 ◽  
Author(s):  
Takahiro Ide ◽  
Shota Mochiji ◽  
Noriko Ueki ◽  
Katsushi Yamaguchi ◽  
Shuji Shigenobu ◽  
...  
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Type Strain ◽  
Wild Type Strain ◽  
Negative Phototaxis ◽  
Wild Type

Characterization of a norflurazon-resistant mutant of Chlamydomonas reinhardtii

Weed Science ◽  
1997 ◽  
Vol 45 (3) ◽  
pp. 374-377 ◽  
Author(s):  
Varsha Vartak ◽  
Sujata Bhargava
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Mode Of Action ◽  
Resistant Mutant ◽  
Phytoene Desaturase ◽  
Wild Type ◽  
Cross Tolerance ◽  
In The Wild ◽  
Similar Mode ◽  
Target Enzyme

A norflurazon-resistant mutant has been isolated from Chlamydomonas reinhardtii that showed a three-fold factor of resistance over wild type cultures. In comparison to wild type cultures, the mutant showed better retention of chlorophylls and carotenoids when grown in light in the presence of norflurazon. When grown in the dark, chlorophyll losses were similar, while carotenoid losses were lower than in the wild type cultures. Higher levels of phytoene accumulated in the wild type cultures in the presence of norflurazon than in the resistant cultures. The resistant cultures also showed cross tolerance to EMD-IT 5914, a herbicide with a similar mode of action. Norflurazon resistance in this alga appears to arise from alterations in the target enzyme phytoene desaturase.

The Reactions of Normal and Mutant Types of Gammarus Chevreuxi to Light

1932 ◽  
Vol 9 (4) ◽  
pp. 427-440
Author(s):  
A. WOLSKY ◽  
J. S. HUXLEY
Keyword(s):  
Acetic Acid ◽  
Moderate Degree ◽  
Negative Phototaxis ◽  
Wild Type ◽  
Type Specimens ◽  
Optic Nerves ◽  
Positive Phototaxis ◽  
Statistical Results

1. A method is described for obtaining statistical results on the phototaxis of G. chevreuxi. A long tube is illuminated from one end and the numbers of animals in two arbitrarily delimited end-sections counted at regular intervals. 2. Wild-type specimens in normal conditions show a moderate degree of negative phototaxis. 3. Animals with one eye varnished show circus movements; hence the phototaxis is true tropotaxis (Fränkel, 1931 4. The sense of reaction can be reversed and the animals made to show a moderate positive phototaxis by the addition of acetic acid. Caffein has no effect. 5. Red-eyed mutants, which lack most of the melanin eye pigment, behave similarly to the wild type, though there are indications that they are often rather more sensitive to light, as shown by stronger negative phototaxis in normal conditions, weaker positive phototaxis after addition of acid. The variability of the results, however, is too great to permit of definitive conclusions being drawn. 6. Albino and colourless mutants, which possess neither retinulae nor optic nerves, show no phototaxis.

A genetic analysis of suppressors of the PF10 mutation in Chlamydomonas reinhardtii.

Genetics ◽  
1988 ◽  
Vol 120 (4) ◽  
pp. 965-976 ◽  
Author(s):  
S K Dutcher ◽  
W Gibbons ◽  
W B Inwood
Keyword(s):  
Chlamydomonas Reinhardtii ◽  
Wild Type Allele ◽  
Wild Type ◽  
Low Light ◽  
Suppressor Activity ◽  
Type Allele ◽  
Light Intensities ◽  
Unicellular Green Alga ◽  
Diploid Cells ◽  
Extragenic Suppressors

Abstract A mutation at the PF10 locus of the unicellular green alga Chlamydomonas reinhardtii leads to abnormal cell motility. The asymmetric form of the ciliary beat stroke characteristic of wild-type flagella is modified by this mutation to a nearly symmetric beat. We report here that this abnormal motility is a conditional phenotype that depends on light intensity. In the absence of light or under low light intensities, the motility is more severely impaired than at higher light intensities. By UV mutagenesis we obtained 11 intragenic and 70 extragenic strains that show reversion of the pf10 motility phenotype observed in low light. The intragenic events reverted the motility phenotype of the pf10 mutation completely. The extragenic events define at least seven suppressor loci; these map to linkage groups IV, VII, IX, XI, XII and XVII. Suppressor mutations at two of the seven loci (LIS1 and LIS2) require light for their suppressor activity. Forty-eight of the 70 extragenic suppressors were examined in heterozygous diploid cells; 47 of these mutants were recessive to the wild-type allele and one mutant (bop5-1) was dominant to the wild-type allele. Complementation analysis of the 47 recessive mutants showed unusual patterns. Most mutants within a recombinationally defined group failed to complement one another, although there were pairs that showed intra-allelic complementation. Additionally, some of the mutants at each recombinationally defined locus failed to complement mutants at other loci. They define dominant enhancers of one another.

scholarly journals Induction and characterization of mitochondrial DNA mutants in Chlamydomonas reinhardtii.

1989 ◽  
Vol 108 (4) ◽  
pp. 1221-1226 ◽  
Author(s):  
R F Matagne ◽  
M R Michel-Wolwertz ◽  
C Munaut ◽  
C Duyckaerts ◽  
F Sluse
Keyword(s):  
Mitochondrial Dna ◽  
Cytochrome C ◽  
Chlamydomonas Reinhardtii ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Wild Type ◽  
Apocytochrome B ◽  
Cytochrome Pathway ◽  
Apocytochrome B Gene

In addition to lethal minute colony mutations which correspond to loss of mitochondrial DNA, acriflavin induces in Chlamydomonas reinhardtii a low percentage of cells that grow in the light but do not divide under heterotrophic conditions. Two such obligate photoautotrophic mutants were shown to lack the cyanide-sensitive cytochrome pathway of the respiration and to have a reduced cytochrome c oxidase activity. In crosses to wild type, the mutations are transmitted almost exclusively from the mating type minus parent. A same pattern of inheritance is seen for the mitochondrial DNA in crosses between the two interfertile species C. reinhardtii and Chlamydomonas smithii. Both mutants have a deletion in the region of the mitochondrial DNA containing the apocytochrome b gene and possibly the unidentified URFx gene.

Sign in / Sign up

Export Citation Format

Share Document