Project description:The daily cycle of night and day affects the behaviour and physiology of almost all living things. At the molecular level, many genes show daily changes in expression levels. To determine whether changes in transcript abundance occur in wood forming tissues of Eucalyptus trees we used a cDNA microarray to examine gene expression levels at roughly four hour intervals throughout the day. Experiments were performed using RNA extracted from two biological replicates - GU (Eucalyptus grandis x E. urophylla) and GC (Eucalyptus grandis x camaldulensis) trees. A loop design was used, linking six time points. A dye swap was incorporated to eliminate dye bias.
Project description:The gene expression profiles of the differentiating xylem of 91 Eucalyptus grandis backcross individuals were characterized following a loop design (Churchill, G.A. Nat Genet. 2002 Dec;32 Suppl:490-5). In this design, RNA from genotype 1666 (labeled with Cy5) was hybridized with RNA from genotype 1667 (labeled with Cy3) on the first slide(GEO accession number GSM7637); the same genotype 1667 (now labeled with Cy5) was compared with genotype 1669 (Cy3) on the second slide (GSM7638), and so on. The loop was completed when genotype 1666 (Cy3) was contrasted to individual 1796 (Cy3) on slide GSM7727. Therefore, 91 individuals (genotypes) from the E. grandis backcross population were analyzed in two replicates, one with RNA labeled with Cy3 and the other with Cy5. Keywords = Eucalyptus, xylem, microarray Keywords: ordered
Project description:In order to pinpoint the most differentially expressed genes between Eucalyptus grandis leaf blades and vascular (xylem) tissues as well as between E. grandis and Eucalyptus globulus xylem tissues, a total number of nine 50mer-oligoprobes covering the length of each one of 21,432 unique sequences derived from the Genolyptus EST dataset were synthesized “on-chip” in duplicate, randomly distributed in two blocks of each slide. Probes were also synthesized from ten cDNA sequences encoding known human proteins as negative controls, totaling 21,442 sequences. Leaves and xylem samples were taken from two E. grandis clonal trees, i.e., both derived from the same matrix tree and harboring the same genotype. Two additional xylem samples were collected from two other E. grandis clonal trees of a different genotype, as well as from two E. globulus clonal trees. Therefore, ten cDNA samples and ten identical chips were produced at Roche NimbleGen for the microarray assays, with a total number of 385,956 features per slide. Besides the discovery of differentially expressed genes between leaf and xylem, we wanted to test the validity of the assumed “technical” and “biological duplicates” since all trees were field-grown and four years-old in age.