Project description:C. reinhardtii cells exposed to abiotic stresses (e.g. iron-, nitrogen-, zinc- or phosphorus-deficiency) accumulate TAGs which are stored in lipid droplets. Here, we report that iron starvation leads to formation of lipids bodies and accumulation of TAGs. This occurs between 12 and 24 h of iron-starvation. C. reinhardtii cells deprived for iron have more saturated FA, due to the loss of functional FA desaturases, which are diiron enzymes. The abundance of a plastid ACP-acyl desaturase (FAB2) is significantly decreased to the same degree as observed for ferredoxin, which is a substrate of the desaturases. The increase in saturated FA (C16:0 and C18:0) is concomitant with the decrease in saturated FA (C16:4, C18:3 or C18:4). This pattern was observed for MGDG, DGTS or DGDG. When we monitored the absolute levels of glycerolipids, MGDG content dropped significantly after only 2 h of iron-starvation. On the other hand, DGTS and DGDG contents gradually decrease until a minimum is reached after 24-48 h of iron-deprivation. RNA-Seq analysis of iron-starved C. reinhardtii cells revealed significant changes in many transcripts coding for enzymes involved in FA metabolism. The mRNA abundances of genes coding for components involved in TAG accumulation (DGAT or MLDP) are increased. A more dramatic increase at the transcript level has been observed for many lipases, suggesting that a major remodeling of lipid membranes occurs during iron-starvation in C. reinhardtii.
Project description:Small RNAs (21-24 nt) are pivotal regulators of gene expression that guide both transcriptional and post-transcriptional silencing mechanisms in diverse eukaryotes, including most if not all plants. MicroRNAs (miRNAs) and short interfering RNAs (siRNAs) are the two major types, both of which have a demonstrated and important role in plant development, stress responses and pathogen resistance. In this work, we used a deep sequencing approach (Sequencing-By-Synthesis, or SBS) to develop sequence resources of small RNAs from cultures of Chlamydomonas reinhardtii (in control, phosphate starvation and sulphate starvation conditions). The high depth of the resulting datasets enabled us to examine in detail critical small RNA features as size distribution, tissue-specific regulation and sequence conservation between different organs in this species. We also developed database resources and a dedicated website (http://smallrna.udel.edu/) with computational tools for allowing other users to identify new miRNAs or siRNAs involved in specific regulatory pathways, verify the degree of conservation of these sequences in other plant species and map small RNAs on genes or larger regions of the genome under study.
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:C. reinhardtii cells exposed to abiotic stresses (e.g. iron-, nitrogen-, zinc- or phosphorus-deficiency) accumulate TAGs which are stored in lipid droplets. Here, we report that iron starvation leads to formation of lipids bodies and accumulation of TAGs. This occurs between 12 and 24 h of iron-starvation. C. reinhardtii cells deprived for iron have more saturated FA, due to the loss of functional FA desaturases, which are diiron enzymes. The abundance of a plastid ACP-acyl desaturase (FAB2) is significantly decreased to the same degree as observed for ferredoxin, which is a substrate of the desaturases. The increase in saturated FA (C16:0 and C18:0) is concomitant with the decrease in saturated FA (C16:4, C18:3 or C18:4). This pattern was observed for MGDG, DGTS or DGDG. When we monitored the absolute levels of glycerolipids, MGDG content dropped significantly after only 2 h of iron-starvation. On the other hand, DGTS and DGDG contents gradually decrease until a minimum is reached after 24-48 h of iron-deprivation. RNA-Seq analysis of iron-starved C. reinhardtii cells revealed significant changes in many transcripts coding for enzymes involved in FA metabolism. The mRNA abundances of genes coding for components involved in TAG accumulation (DGAT or MLDP) are increased. A more dramatic increase at the transcript level has been observed for many lipases, suggesting that a major remodeling of lipid membranes occurs during iron-starvation in C. reinhardtii. Sampling of Chlamydomonas CC-4532 (2137) cells cultivated photoheterotrophically (TAP) under iron-starvation condition (0 uM Fe-EDTA). Samples were collected from biological duplicates after washing in TAP medium lacking Fe at 0, 0.5, 1, 2, 4, 8, 12, 24 and 48 hours.
Project description:endogenous small RNAs from Chlamydomonas reinhardtii strain J3(mt-) vegetative cells Keywords: High throughput 454 small RNA sequencing
Project description:Chlamydomonas reinhardtii exposed to various concentrations of silver For this experiment,C. reinhardtii were exposed to (4) different concentrations of silver, as biological triplicates
Project description:DCL3 appeared several times in a forward genetic screen meant to isolate genes involved in miRNA-mediated RNA silencing in Chlamydomonas reinhardtii. Because of that, and in order to define the role of DCL3 in the processing of small RNAs on a genome-wide basis, we sequence the small RNA transcriptome of dcl3 mutant and parental lines.