Characterization of salt stress-induced palmelloids in the green alga, Chlamydomonas reinhardtii

Khona, Dolly; Shirolikar, Seema; Gawde, Kanak K.; Hom, Erik F. Y.; Deodhar, Manjushree A.; D’Souza, Jacinta S.

doi:10.1016/j.algal.2016.03.035

Cited by 101 publications

(107 citation statements)

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“…Tunicamycin treatment arrested Chlamydomonas cell growth, and induced aggregation and chlorosis in a concentration‐dependent manner (Figure ). Many cells aggregated in random numbers and also in four‐cell units, which resemble palmelloid, a structure reported in stressed Chlamydomonas (Khona et al ., ). These results indicate that tunicamycin indeed induced severe stress in Chlamydomonas cells.…”

Section: Discussionmentioning

confidence: 97%

Identification and functional study of the endoplasmic reticulum stress sensor IRE1 in Chlamydomonas reinhardtii

et al. 2018

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In many eukaryotes, endoplasmic reticulum (ER) stress activates the unfolded protein response (UPR) via the transmembrane endoribonuclease IRE1 to maintain ER homeostasis. The ER stress response in microalgae has not been studied in detail. Here, we identified Chlamydomonas reinhardtii IRE1 (CrIRE1) and characterized two independent knock-down alleles of this gene. CrIRE1 is similar to IRE1s identified in budding yeast, plants, and humans, in terms of conserved domains, but differs in having the tandem zinc-finger domain at the C terminus. CrIRE1 was highly induced under ER stress conditions, and the expression of a chimeric protein consisting of the luminal N-terminal region of CrIRE1 fused to the cytosolic C-terminal region of yeast Ire1p rescued the yeast ∆ire1 mutant. Both allelic ire1 knock-down mutants ire1-1 and ire1-2 were much more sensitive than their parental strain CC-4533 to the ER stress inducers tunicamycin, dithiothreitol and brefeldin A. Treatment with a low concentration of tunicamycin resulted in growth arrest and cytolysis in ire1 mutants, but not in CC-4533 cells. Furthermore, in the mutants, ER stress marker gene expression was reduced, and reactive oxygen species (ROS) marker gene expression was increased. The survival of ire1 mutants treated with tunicamycin improved in the presence of the ROS scavenger glutathione, suggesting that ire1 mutants failed to maintain ROS levels under ER stress. Together, these results indicate that CrIRE1 functions as an important component of the ER stress response in Chlamydomonas, and suggest that the ER stress sensor IRE1 is highly conserved during the evolutionary history.

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Section: Discussionmentioning

confidence: 97%

Identification and functional study of the endoplasmic reticulum stress sensor IRE1 in Chlamydomonas reinhardtii

et al. 2018

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“…Formation of palmelloids or groups of nonflagelled cells is not uncommon in laboratory culture of this alga (Harris, 2009); and the mechanisms that drive the transition from unicellular to colonial lifestyle are poorly understood. Palmelloid formation is generally associated with the adverse environmental conditions, such as presence of predators (Herron et al, 2019;Lurling and Beekman, 2006), salt stress (Khona et al, 2016;Takouridis et al, 2015) and organic acids induced stress (Iwasa and Murakami, 1969). Possible palmelloid formation in presence of micropollutants was rarely reported (Goff et al, 2013;Jamers and De Coen, 2010) despite the extended use of Chlamydomonas strain in ecotoxicological studies.…”

Section: Introductionmentioning

confidence: 99%

Morphological plasticity inChlamydomonas reinhardtiiand acclimation to micropollutant stress

Cheloni

2020

Preprint

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Phytoplankton are characterized by a great phenotypic plasticity and amazing morphological variability, both playing a primary role in the acclimation to changing environments. However, there is a knowledge gap concerning the role of algal morphological plasticity in stress responses and acclimation to micropollutants. The present study aims examining the palmelloid colony formation of the green alga Chlamydomonas reinhardtii upon micropollutants exposure.Cells were exposed to four micropollutants (MPs) with different modes of action (copper, cadmium, PFOS and paraquat) for a duration of 72h. Effects of MPs on palmelloid formation, growth and physiological traits (chlorophyll fluorescence, membrane integrity and oxidative stress) were monitored via flow cytometry and fluorescence microscopy. Palmelloid formation was observed upon treatment with the four micropollutants. Number of palmelloid colonies and their size were dependent on MP concentration and exposure duration. Cells reverted to their unicellular lifestyle when colonies were harvested and inoculated in fresh medium indicating that palmelloid formation is a plastic response to micropollutants. No physiological effects of these compounds were observed in cells forming palmelloids and palmelloid colonies accumulated lower Cd concentration than unicellular C. reinhardtii suggesting that colony formation protects the cells form MPs exposure. The results show that colony formation in Chlamydomonas reinhardtii is a stress response strategy activated to face sub-lethal micropollutant concentrations.HIGHLIGHTSSub-lethal concentrations of micropollutants (MPs) induce palmelloid formation in C. reinhardtiiMorphological changes are not associated to adverse effects on algal cellsPalmelloid formation is transitory, cells revert to unicellular lifestyle in the absence of MPsCells within large colonies experience lower Cd exposure than unicellular C. reinhardtiiPalmelloid formation is a morphological stress response that plays a role in cells acclimation to MPs

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“…Multicellular Chlamydomonas clusters have clear spatial boundaries, but as cells are able to leave palmelloid clusters (Khona et al 2016) we do not consider them indivisible. Cell clusters may form via aggregation between separate genetic strains, suggesting Chlamydomonas clusters are not always genetically homogenous (Sathe and Durand 2015); however, in the other studies discussed above, the clusters are considered to be clonally formed and genetically homogenous.…”

Section: Chlamydomonasmentioning

confidence: 99%

“…These clusters typically include 2, 4, 8, or 16 cells. Palmelloid clusters can facultatively form as a result of treatment inhibiting daughter cell hatching (e.g., calcium deprivation, chelating agents, high salt concentrations) and treatment resulting in cell wall aberrations (Iwasa and Murakami 1968;Nakamura et al 1975Nakamura et al , 1978Harris 2009;Khona et al 2016). More recently, multicellular clusters of Chlamydomonas have been used to investigate ecological and evolutionary questions.…”

Section: Chlamydomonasmentioning

confidence: 99%

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Evolution of Individuality: A Case Study in the Volvocine Green Algae

Hanschen¹,

Davison²,

Grochau-Wright³

et al. 2017

Philosophy, Theory, and Practice in Biology

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While numerous criteria have been proposed in definitions of biological individuality, it is not clear whether these criteria reflect the evolutionary processes that underlie transitions in individuality. We consider the evolution of individuality during the transition from unicellular to multicellular life. We assume that "individuality" (however it is defined) has changed in the volvocine green algae lineage during the transition from single cells, to simple multicellular colonies with four to one hundred cells, to more complex multicellular organisms with thousands of differentiated cells. We map traits associated with the various proposed individuality criteria onto volvocine algae species thought to be similar to ancestral forms arising during this transition in individuality. We find that the fulfillment of some criteria, such as genetic homogeneity and genetic uniqueness, do not change across species, while traits underpinning other aspects of individuality, including degrees of integration, group-level fitness and adaptation, and group indivisibility, change dramatically. We observe that different kinds of individuals likely exist at different levels of organization (cell and group) in the same species of algae. Future research should focus on the causes and consequences of variation in individuality.

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Characterization of salt stress-induced palmelloids in the green alga, Chlamydomonas reinhardtii

Cited by 101 publications

References 73 publications

Identification and functional study of the endoplasmic reticulum stress sensor IRE1 in Chlamydomonas reinhardtii

Identification and functional study of the endoplasmic reticulum stress sensor IRE1 in Chlamydomonas reinhardtii

Morphological plasticity inChlamydomonas reinhardtiiand acclimation to micropollutant stress

Evolution of Individuality: A Case Study in the Volvocine Green Algae

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