TY - JOUR
T1 - Many but not all genes in Chlamydomonas reinhardtii are regulated by the circadian clock
AU - Jacobshagen, Sigrid
AU - Whetstine, J. R.
AU - Boling, J. M.
PY - 2001
Y1 - 2001
N2 - Total RNA from autotrophic Chlamydomonas reinhardtii cultures grown in constant dim light and 17°C constant temperature was subjected to Northern blot analyses. The mRNAs for cytochrome c, β-tubulin, HSP70B (a chloroplastic heat shock protein of the 70 kD family), chloroplastic fructose-bisphosphate aldolase, and GAS3 (a "gamete-specific" protein of unknown function with high expression in gametes but low expression in vegetative cells) each exhibit a clear circadian rhythm in abundance. The rhythms differ significantly in phase and amplitude. The findings show that the genes for cytochrome c and β-tubulin indeed are regulated by the circadian clock, as previously suggested. Experiments with cultures grown at 27°C instead of 17°C further revealed that the rhythms in mRNA abundance for HSP7OB, chloroplastic aldolase, and GAS3 also occur with a similar period at the higher temperature. Thus, the rhythms conform to the criterion of temperature compensation for the period and therefore represent true circadian rhythms. In contrast, the combined amount of mRNA for ubiquitin 52 amino acid fusion protein and ubiquitin 78 to 81 amino acid fusion protein stays constant under both temperature conditions. Because the combined amount of mRNA for the ubiquitin fusion proteins was previously shown to cycle under diurnal conditions when cell division activity is high, our data suggest a regulation of these genes by the cell division cycle and not the circadian clock. In summary, our data, together with several other reports, suggest that the circadian clock regulates many but not all genes in Chlamydomonas reinhardtii.
AB - Total RNA from autotrophic Chlamydomonas reinhardtii cultures grown in constant dim light and 17°C constant temperature was subjected to Northern blot analyses. The mRNAs for cytochrome c, β-tubulin, HSP70B (a chloroplastic heat shock protein of the 70 kD family), chloroplastic fructose-bisphosphate aldolase, and GAS3 (a "gamete-specific" protein of unknown function with high expression in gametes but low expression in vegetative cells) each exhibit a clear circadian rhythm in abundance. The rhythms differ significantly in phase and amplitude. The findings show that the genes for cytochrome c and β-tubulin indeed are regulated by the circadian clock, as previously suggested. Experiments with cultures grown at 27°C instead of 17°C further revealed that the rhythms in mRNA abundance for HSP7OB, chloroplastic aldolase, and GAS3 also occur with a similar period at the higher temperature. Thus, the rhythms conform to the criterion of temperature compensation for the period and therefore represent true circadian rhythms. In contrast, the combined amount of mRNA for ubiquitin 52 amino acid fusion protein and ubiquitin 78 to 81 amino acid fusion protein stays constant under both temperature conditions. Because the combined amount of mRNA for the ubiquitin fusion proteins was previously shown to cycle under diurnal conditions when cell division activity is high, our data suggest a regulation of these genes by the cell division cycle and not the circadian clock. In summary, our data, together with several other reports, suggest that the circadian clock regulates many but not all genes in Chlamydomonas reinhardtii.
KW - Circadian rhythms
KW - Gene expression
KW - Green alga
UR - http://www.scopus.com/inward/record.url?scp=0035698788&partnerID=8YFLogxK
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U2 - 10.1055/s-2001-19370
DO - 10.1055/s-2001-19370
M3 - Article
SN - 1435-8603
VL - 3
SP - 592
EP - 597
JO - Plant Biology
JF - Plant Biology
IS - 6
ER -