Project description:This SuperSeries is composed of the following subset Series: GSE20859: Change in gene expression in Chlamydomonas reinhardtii upon heat shock GSE20860: Change in gene expression in Chlamydomonas reinhardtii upon feeding with hemin and Mg-protoporphyrin Refer to individual Series
Project description:The tetrapyrroles Mg-protoporphyrin IX (MgProto) and heme, in Chlamydomonas reinhardtii only synthesized within the chloroplast, have been implicated in retrograde control of nuclear gene expression in this unicellular green alga. However, feeding of the two tetrapyrroles to Chlamydomonas cultures growing in the dark has previously been shown to transiently induce 5 nuclear genes, among them three genes coding for the chloroplast heat shock proteins HSP70A, B and E. Here, we measured the impact of MgProto and hemin feeding in the dark on changes in gene expression at the genomic level. About 10% of the 10000 genes represented on the microarray showed a transient up or down regulation with a fold change of 4 or more (p ≤0.05). The two most prominent groups of regulated genes were those where both MgProto and heme caused either an up or down regulation. Minor regulatory groups consisted of genes which were either down- or up-regulated by one of the tetrapyrroles but not by the other. In contrast, feeding of protoporphyrin IX had no regulatory effect on a number of selected genes. Interestingly, 499 of the 982 responding genes were also regulated by heat shock; 85% of those showed the same response (up or down) as seen after MgProto/heme feeding, indicating a previously not anticipated role of MgProto and heme in stress response. Indeed, most prominent among the functional groups of annotated genes up or down regulated by the tetrapyrroles were those whose gene products are involved in protein folding and/or protein degradation. Striking is the virtual absence of regulated genes that encode constituents of the photosynthetic apparatus. This and the transient nature of changes in gene expression observed upon feeding of the tetrapyrroles suggest a signaling role of these plastid compounds in the adaptation of the alga to alterations in the environment.
Project description:The transcriptome of Chlamydomonas reinhardtii was characterized via RNA sequencing (RNA-seq) after exposure to a non-toxic concentration of AgNPs (0.05 mg/L). The copper deficiency responsive genes were discovered to be upregulated and responsible for the interaction between algae and AgNPs.
Project description:Different high temperatures adversely affect crop and algal yields with various responses in photosynthetic cells. The list of genes required for thermotolerance remains elusive. Additionally, it is unclear how carbon source availability affects heat responses in plants and algae. We utilized the insertional, indexed, genome-saturating mutant library of the unicellular, eukaryotic green alga Chlamydomonas reinhardtii to perform genome-wide, quantitative, pooled screens under moderate (35oC) or acute (40oC) high temperatures with or without organic carbon sources. We identified heat-sensitive mutants based on quantitative growth rates and identified putative heat tolerance genes (HTGs). By triangulating HTGs with heat-induced transcripts or proteins in wildtype cultures and MapMan functional annotations, we present a high/medium-confidence list of 933 Chlamydomonas genes with putative roles in heat tolerance. Triangulated HTGs include those with known thermotolerance roles and novel genes with little or no functional annotation. About 50% of these high-confidence HTGs in Chlamydomonas have orthologs in green lineage organisms, including crop species. Arabidopsis thaliana mutants deficient in the ortholog of a high-confidence Chlamydomonas HTG were also heat sensitive. This work expands our knowledge of heat responses in photosynthetic cells and provides engineering targets to improve thermotolerance in algae and crops.
Project description:RNA populations in Chlamydomonas reinhardtii Keywords: Highly parallel pyrosequencing Small RNAs were prepared from Chlamydomonas reinhardtii total extracts,ligated to a 3' adaptor and a 5' acceptor sequentially, and then RT-PCR amplified. PCR products were reamplified using a pair of 454 cloning primers and provided to 454 Life Sciences (Branford, CT) for sequencing. For technical details, see Tao Zhao, Guanglin Li, Shijun Mi, Shan Li, Gregory J. Hannon, Xiu-Jie Wang, and Yijun Qi. 2007. A Complex System of Small RNAs in the Unicellular Green Alga Chlamydomonas reinhardtii. Genes & Development
Project description:endogenous small RNAs from Chlamydomonas reinhardtii strain J3(mt-) vegetative cells Keywords: High throughput 454 small RNA sequencing
