Comprehensive Discovery of Cell-Cycle-Essential Pathways in Chlamydomonas reinhardtii

Extensive in vivo replacement of hydrogen by deuterium, a stable isotope of hydrogen, induces a distinct stress response, reduces cell growth and impairs cell division in various organisms. Microalgae, including Chlamydomonas reinhardtii, a well-established model organism in cell cycle studies, are no exception. Chlamydomonas reinhardtii, a green unicellular alga of the Chlorophyceae class, divides by multiple fission, grows autotrophically and can be synchronized by alternating light/dark regimes; this makes it a model of first choice to discriminate the effect of deuterium on growth and/or division. Here, we investigate the effects of high doses of deuterium on cell cycle progression in C. reinhardtii. Synchronous cultures of C. reinhardtii were cultivated in growth medium containing 70 or 90% D2O. We characterize specific deuterium-induced shifts in attainment of commitment points during growth and/or division of C. reinhardtii, contradicting the role of the “sizer” in regulating the cell cycle. Consequently, impaired cell cycle progression in deuterated cultures causes (over)accumulation of starch and lipids, suggesting a promising potential for microalgae to produce deuterated organic compounds.

Download Full-text

Sequences controlling transcription of the Chlamydomonas reinhardtii beta 2-tubulin gene after deflagellation and during the cell cycle

Molecular and Cellular Biology ◽

10.1128/mcb.14.8.5165-5174.1994 ◽

1994 ◽

Vol 14 (8) ◽

pp. 5165-5174

Author(s):

J P Davies ◽

A R Grossman

Keyword(s):

Cell Cycle ◽

Chlamydomonas Reinhardtii ◽

Transcription Initiation ◽

Chimeric Gene ◽

Transcriptional Level ◽

Sequence Motif ◽

Tubulin Gene ◽

Rich Region ◽

Beta 2 ◽

Encoding Genes

In Chlamydomonas reinhardtii, transcripts from the beta 2-tubulin gene (tubB2), as well as those from other tubulin-encoding genes, accumulate immediately after flagellar excision as well as at a specific time in the cell cycle. Control of tubB2 transcript accumulation following deflagellation is regulated, at least partially, at the transcriptional level. We have fused the tubB2 promoter to the arylsulfatase (ars) reporter gene, introduced this construct into C. reinhardtii, and compared expression of the chimeric gene with that of the endogenous tubB2 gene. After flagellar excision, transcripts from the tubB2/ars chimeric gene accumulate with kinetics similar to those of transcripts from the endogenous tubB2 gene. The tubB2/ars transcripts also accumulate in a cell cycle-specific manner; however, chimeric transcripts are more abundant earlier in the cell cycle than the endogenous tubB2 transcripts. To elucidate transcriptional control of tubB2, we have mutated or removed sequences in the tubB2 promoter and examined the effect on transcription. The tubB2 promoter shares features with the promoters of other tubulin-encoding genes; these include a GC-rich region between the TATA box and the transcription initiation site and multiple copies of a 10-bp sequence motif that we call the tub box. The tubB2 gene contains seven tub box motifs. Changing the GC-rich region to an AT-rich region or removing three of the seven tub box motifs did not significantly affect transcription of the chimeric gene. However, removing four or five tub box motifs prevented increased transcription following deflagellation and diminished cell cycle-regulated transcription from the tubB2 promoter.

Download Full-text

Alternative Splicing During the Chlamydomonasreinhardtii Cell Cycle

G3 Genes|Genome|Genetics ◽

10.1534/g3.120.401622 ◽

2020 ◽

Vol 10 (10) ◽

pp. 3797-3810

Author(s):

Manishi Pandey ◽

Gary D. Stormo ◽

Susan K. Dutcher

Keyword(s):

Gene Expression ◽

Cell Cycle ◽

Alternative Splicing ◽

Chlamydomonas Reinhardtii ◽

Intron Retention ◽

Exon Skipping ◽

Dark Phase ◽

Periodic Patterns ◽

Genome Wide ◽

Splicing Pattern

Genome-wide analysis of transcriptome data in Chlamydomonas reinhardtii shows periodic patterns in gene expression levels when cultures are grown under alternating light and dark cycles so that G1 of the cell cycle occurs in the light phase and S/M/G0 occurs during the dark phase. However, alternative splicing, a process that enables a greater protein diversity from a limited set of genes, remains largely unexplored by previous transcriptome based studies in C. reinhardtii. In this study, we used existing longitudinal RNA-seq data obtained during the light-dark cycle to investigate the changes in the alternative splicing pattern and found that 3277 genes (19.75% of 17,746 genes) undergo alternative splicing. These splicing events include Alternative 5′ (Alt 5′), Alternative 3′ (Alt 3′) and Exon skipping (ES) events that are referred as alternative site selection (ASS) events and Intron retention (IR) events. By clustering analysis, we identified a subset of events (26 ASS events and 10 IR events) that show periodic changes in the splicing pattern during the cell cycle. About two-thirds of these 36 genes either introduce a pre-termination codon (PTC) or introduce insertions or deletions into functional domains of the proteins, which implicate splicing in altering gene function. These findings suggest that alternative splicing is also regulated during the Chlamydomonas cell cycle, although not as extensively as changes in gene expression. The longitudinal changes in the alternative splicing pattern during the cell cycle captured by this study provides an important resource to investigate alternative splicing in genes of interest during the cell cycle in Chlamydomonas reinhardtii and other eukaryotes.

Download Full-text

Chlamydomonas reinhardtii: duration of its cell cycle and phases at growth rates affected by light intensity

Planta ◽

10.1007/s00425-010-1282-y ◽

2010 ◽

Vol 233 (1) ◽

pp. 75-86 ◽

Cited By ~ 41

Author(s):

Milada Vítová ◽

Kateřina Bišová ◽

Dáša Umysová ◽

Monika Hlavová ◽

Shigeyuki Kawano ◽

...

Keyword(s):

Cell Cycle ◽

Light Intensity ◽

Chlamydomonas Reinhardtii ◽

Growth Rates

Download Full-text

Cell cycle arrest in response to DNA damage in Chlamydomonas reinhardtii

Comparative Biochemistry and Physiology Part A Molecular & Integrative Physiology ◽

10.1016/j.cbpa.2009.04.388 ◽

2009 ◽

Vol 153 (2) ◽

pp. S180

Author(s):

Mária Cížková ◽

Monika Hlavová ◽

Dáša Umysová ◽

Milada Vítová ◽

James G. Umen ◽

...

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Chlamydomonas Reinhardtii ◽

Cell Cycle Arrest ◽

Cycle Arrest

Download Full-text

Thylakoid membrane biogenesis in Chlamydomonas reinhardtii 137+. II. Cell-cycle variations in the synthesis and assembly of pigment.

The Journal of Cell Biology ◽

10.1083/jcb.93.2.411 ◽

1982 ◽

Vol 93 (2) ◽

pp. 411-416 ◽

Cited By ~ 9

Author(s):

D R Janero ◽

R Barrnett

Keyword(s):

Cell Cycle ◽

Chlamydomonas Reinhardtii ◽

Thylakoid Membrane ◽

Direct Analysis ◽

Cellular Level ◽

Periodic Pattern ◽

Cell Cycle Time ◽

Pigment Synthesis ◽

Thylakoid Biogenesis ◽

Kinetics Of

Synthesis of the chlorophyll and the major carotenoid pigments and their assembly into thylakoid membrane have been studied throughout the 12-h light/12-h dark vegetative cell cycle of synchronous Chlamydomonas reinhardtii 137+ (wild-type). Pulse exposure of cells to radioactive acetate under conditions in which labeling accurately reflects lipogenesis, followed by cellular fractionation to purify thylakoid membrane, allowed direct analysis of the pigment synthesis and assembly attendant to thylakoid biogenesis. All pigments are synthesized and assembled into thylakoids continuously, but differentially, with respect to cell-cycle time. Highest synthesis and assembly rates are confined to the photoperiod (mid-to-late G1) and support chlorophyll and carotenoid accretion before M-phase. The lower levels at which these processes take place during the dark period (S, M, and early-to-mid G1) have been ascribed to pigment turnover. Within this general periodic pattern, pigment synthesis and assembly occur in a "multi-step" manner, i.e., by a temporally-ordered, stepwise integration of the various pigments into the thylakoid membrane matrix. The cell-cycle kinetics of pigment assembly at the subcellular level mirror the kinetics of pigment synthesis at the cellular level, indicating that pigment synthesis not only provides chlorophyll and carotenoid for thylakoid biogenesis but may also serve as a critical rate-determinant to pigment assembly.

Download Full-text