Dataset Information

Gradual plasticity alters population dynamics in variable environments: thermal acclimation in the green alga Chlamydomonas reinhartdii.

ABSTRACT: Environmental variability is ubiquitous, but its effects on populations are not fully understood or predictable. Recent attention has focused on how rapid evolution can impact ecological dynamics via adaptive trait change. However, the impact of trait change arising from plastic responses has received less attention, and is often assumed to optimize performance and unfold on a separate, faster timescale than ecological dynamics. Challenging these assumptions, we propose that gradual plasticity is important for ecological dynamics, and present a study of the plastic responses of the freshwater green algae Chlamydomonas reinhardtii as it acclimates to temperature changes. First, we show that C. reinhardtii's gradual acclimation responses can both enhance and suppress its performance after a perturbation, depending on its prior thermal history. Second, we demonstrate that where conventional approaches fail to predict the population dynamics of C. reinhardtii exposed to temperature fluctuations, a new model of gradual acclimation succeeds. Finally, using high-resolution data, we show that phytoplankton in lake ecosystems can experience thermal variation sufficient to make acclimation relevant. These results challenge prevailing assumptions about plasticity's interactions with ecological dynamics. Amidst the current emphasis on rapid evolution, it is critical that we also develop predictive methods accounting for plasticity.

SUBMITTER: Kremer CT

PROVIDER: S-EPMC5784192 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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Gradual plasticity alters population dynamics in variable environments: thermal acclimation in the green alga <i>Chlamydomonas reinhartdii</i>.

Kremer Colin T CT Fey Samuel B SB Arellano Aldo A AA Vasseur David A DA

Proceedings. Biological sciences 20180101 1870

Environmental variability is ubiquitous, but its effects on populations are not fully understood or predictable. Recent attention has focused on how rapid evolution can impact ecological dynamics via adaptive trait change. However, the impact of trait change arising from plastic responses has received less attention, and is often assumed to optimize performance and unfold on a separate, faster timescale than ecological dynamics. Challenging these assumptions, we propose that gradual plasticity i ...[more]

PMID: 29321297

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Project description:Algal photo-bio hydrogen production, a promising method for producing clean and renewable fuel in the form of hydrogen gas, has been studied extensively over the last few decades. In this study, microarray analyses were used to obtain a global expression profile of mRNA abundance in the green alga Chlamydomonas reinhardtii at five different time points before the onset and during the course of sulphur depleted hydrogen production. The present work confirms previous findings on the impacts of sulphur deprivation but also provides new insights into photosynthesis, sulphur assimilation and carbon metabolism under sulphur starvation towards hydrogen production. For instance, while a general trend towards repression of transcripts encoding photosynthetic genes was observed, the abundance of Lhcbm9 (encoding a major light harvesting polypeptide) and LhcSR1 (encoding a chlorophyll binding protein) was strongly elevated throughout the experiment, suggesting remodeling of the photosystem II light harvesting complex as well as an important function of Lhcbm9 under sulphur starvation. This study presents the first global transcriptional analysis of C. reinhardtii during hydrogen production using five major time points at Peak Oxygen, Mid Oxygen, Zero Oxygen, Mid Hydrogen and Peak Hydrogen. Keywords: Time course, sulfur deprivation, hydrogen production. Time course microarray analyses were used to analyze the global gene expression in sulfur depleted hydrogen producing C. reinhardtii. When depleted of sulfur, a sealed an illuminated C. reinhardtii culture slowly becomes anaerobic and produces hydrogen gas. Based on the changes in the dissolved O2 level and H2 production rate, the whole course of H2 production from the starting of S deprivation to the end of H2 production can be divided into five phases including an Aerobic Phase (I) in which the dissolved O2 level goes up (I), an O2 Consumption Phase (II), an Anaerobic Phase (III), a H2 Production Phase (IV) and a Termination phase (V). Samples were taken from three different bioreactors (biological replicates) at the following time points after the start of S depletion: 6 h, 16 h, 21 h, 37 h and 52 h corresponding to Peak O2, Mid O2, Zero O2, Mid H2 and Peak H2.

Project description:Swimming suspensions of Chlamydomonas eugametos were pelleted and homogenized, and the metabolism of inositol polyphosphates by cellular homogenates or supernatants was investigated. Ins(1,4,5)P3 was dephosphorylated under physiological conditions to yield a single InsP2, Ins(1,4]2. In the presence of ATP it was phosphorylated to give Ins(1,3,4,5)P3 as the only InsP4. The Ins(1,4,5)P3 3-kinase activity was predominantly soluble, was not detectably affected by calmodulin or Ca2+, and had a Km for Ins(1,4,5)P3 of 50 microM (two orders of magnitude higher than its mammalian counterpart). Ins(1,3,4,5)P4 was dephosphorylated by the cellular supernatants to Ins(1,3,4)P3 and Ins(1,4,5)P3, and could be phosphorylated to Ins(1,3,4,5,6)P4. No Ins(1,3,4)P3 6-kinase activity could be detected, and experiments with [3H]Ins(1,4,[32P]5)P3 revealed that Ins(1,3,4,5,6)P5 is formed from Ins(1,4,5)P3 with little loss of the 5-phosphate, i.e. the predominant route of synthesis is probably by a direct 6-phosphorylation of Ins(1,3,4,5)P4. Similar experiments with an (NH4)2SO4 fraction of turkey erythrocyte cytosol gave essentially the same result, i.e. direct phosphorylation of Ins(1,3,4,5)P4 in the 6 position is the predominant route of synthesis of InsP5 from that InsP4 in vitro. No InsP6 formation was detected in any of these experiments, but labelling of intact C. eugametos with [3H]inositol revealed that the cells do synthesize InsP6. The lipids of C. eugametos cells contain PtdIns, PtdIns(4)P and PtdIns(4,5)P2 [Irvine, Letcher, Lander, Drøbak, Dawson & Musgrave (1989) Plant Physiol. 64, 888-892]. Further examination of 32P-labelled lipids revealed that about 20% of the PtdInsP was the PtdIns(3)P isomer, and about 1% or less of the PtdInsP2 was the PtdIns(3,4)P2 isomer. The overall inositide metabolism of C. eugametos resembles that of a mammalian cell more closely than it does that of a plant cell or slime mould, and this suggests firstly that the known metabolism of inositol polyphosphates arose at an early time in eukaryotic evolution, and secondly that Chlamydomonas might prove a useful organism for genetic and comparative studies of inositide enzymology.

Dataset Information

Gradual plasticity alters population dynamics in variable environments: thermal acclimation in the green alga Chlamydomonas reinhartdii.

Publications

Gradual plasticity alters population dynamics in variable environments: thermal acclimation in the green alga <i>Chlamydomonas reinhartdii</i>.

Similar Datasets

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