Project description:Liquid cultures of the unicellular green alga, Chlamydomonas reinhardtii were grown in media with 6 uM Mn (control) or 1000 uM Mn (experimental), and analyzed by RNA-Seq to identify genes that are differentially expressed in response to excess Mn.
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: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:It is highly necessary to understand the molecular mechanism underlying the salt stress response in green algae, which may contribute to finding the evolutionary cues of abiotic stress response in plants.In the present study, we examined the gene expression pattern in Chlamydomonas reinhardtii GY-D55 cells at different time points, from early stage (2-24 h) to late stage (up to 96 h).
Project description:Linear tetrapyrrole (bilin)-based phytochrome sensors optimize photosynthetic light capture by mediating massive gene reprogramming in land plants, yet surprisingly, many sequenced chlorophyte (green) algae lack phytochrome genes. Previous studies on the heme oxygenase (hmox1) mutant of Chlamydomonas reinhardtii suggest that bilin biosynthesis in plastids is needed for regulation of a limited nuclear gene network implicated in oxygen detoxification during dark to light transitions. The hmox1 mutant is unable to grow photoautotrophically and poorly acclimates to increased illumination even in the presence of acetate. Here we show that these phenotypes reflect the reduced accumulation of PSI reaction centers as well as a loss of PSI and PSII antennae complexes during photoacclimation. Phenotypically, the hmox1 mutant is similar to the chlorophyll biosynthesis mutants, gun4, crd1 and cth1. However, many of the hmox1 phenotypes can be rescued by the application of exogenous biliverdin IXα, the bilin product of HMOX1; this rescue is independent of photosynthesis but strongly dependent upon blue light. RNA-Seq comparisons of hmox1, 4A+ wild type and two genetically complemented lines also reveal that bilins restore regulation of a small network of photosynthesis-associated nuclear genes. These include genes responsible for chlorophyll biosynthesis (CHLI1/2), PSI light-harvesting (LHCA4) and naphthoquinone metabolism (MEN2), all of which show reduced photoinduction in the hmox1 mutant. We propose that a bilin-based, blue light sensory system is responsible for the maintenance of a functional photosynthetic apparatus in light-grown C. reinhardtii. This critical and possibly ancestral role for bilins may be responsible for retention of bilin biosynthesis in all eukaryotic photosynthetic species.
Project description:This data was generated to identify the molecular pathways responsible for nitrous oxide synthesis by the green algae Chlamydomonas reinhardtii, when supplied with nitrite under aerobic conditions (oxia). RNA samples were collected at three time points, 15 min, 3 hours, and 24 hours after the start of the experiment. The control and treatment groups were grown under the same conditions, except treatment group was supplied with 10mM nitrite at time 0. Illumina TruSeq stranded RNA libraries were synthesised from the resulting RNA before sequencing on a HiSeq2500 (125bp). The resulting sequence run generated 241,151,809 paired-end 125bp reads, of which 200,946,839 remained following quality filtering. The short data was mapped to the published genome and read counts were generated with HT-Seq count with the default settings. The raw read count data was analysed by DESeq2 in order to identify genes differentially expressed during nitrous oxide production.
Project description:The Streptophyta include unicellular and multicellular charophyte green algae and land plants. Colonization of the terrestrial habitat by land plants was a major evolutionary event that has transformed our planet. So far lack of genome information on unicellular charophyte algae hinders our understanding of the origin and the evolution from unicellular to multicellular life in Streptophyta. This work reports the high-quality reference genome and transcriptome of Mesostigma viride, a single-celled charophyte alga with a position at the base of Streptophyta. There are abundant segmental duplications and transposable elements in M. viride, which contribute to a relatively large genome with high gene content compared to other algae and early diverging land plants. This work identifies the origin of genetic tools that multicellular Streptophyta have inherited and key genetic innovations required for evolution of land plants from unicellular aquatic ancestors. The findings shed light on the age-old questions of the evolution of multicellularity and the origin of land plants.
Project description:The Streptophyta include unicellular and multicellular charophyte green algae and land plants. Colonization of the terrestrial habitat by land plants was a major evolutionary event that has transformed our planet. So far lack of genome information on unicellular charophyte algae hinders our understanding of the origin and the evolution from unicellular to multicellular life in Streptophyta. This work reports the high-quality reference genome and transcriptome of Mesostigma viride, a single-celled charophyte alga with a position at the base of Streptophyta. There are abundant segmental duplications and transposable elements in M. viride, which contribute to a relatively large genome with high gene content compared to other algae and early diverging land plants. This work identifies the origin of genetic tools that multicellular Streptophyta have inherited and key genetic innovations required for evolution of land plants from unicellular aquatic ancestors. The findings shed light on the age-old questions of the evolution of multicellularity and the origin of land plants.