文档介绍：Microarray Analysis of Drosophila Development During Metamorphosis
K. P. White, S. A. Rifkin P. Hurban and D. S. Hogness
Goal
Use of DNA microarrays to study changes in gene expression patterns during Drosophila metamorphosis, induced by ecdysone peaks.
Studies were performed during six time points relative to the puparium formation (PF) stages that span two ecdysone pulses.
Drosophila metamorphosis : material
Array elements : 6'240 cDNA clones from the Berkeley Drosophila Genome Project, covering about 40% of the total estimated number of genes in Drosophila, plus known ecdysone-regulated control genes
Interesting subset : 534 elements displaying threefold or more differential expression during metamorphosis
Number of experiments : 19, covering 6 time points relative to PF
The arrays
Drosophila metamorphosis : material
Reference sample Cy3-labelled : Animals in puparium formation (PF) stage, 0 hour
Time-course experiments, Cy5-labelled :18 and 4 hours before PF , and 3, 6, 9, 12 hours after PF
The samples
Drosophila metamorphosis : methods
Two methods were used to interpret the data :
1- The Stanford clustering method.
2- A anizing map (SOM) algorithm.
This method allows the user to choose the
number of desired clusters. The result is displayed in graphs which represent the clusters. Time points are represented in these graphs from left to right.
Drosophila metamorphosis : results
Stanford clustering
Differentially expressed genes fall into two main categories. The first category contains genes that are expressed at 18 hours BFP (before the late larval ecdysone pulse) but then fall to low or undetectable levels during this pulse. This category is colored red in the first column. They are potentially repressed by ecdysone
The second category consists of genes expressed at low or undetectable levels before the late larval ecdysone pulse but then are induced during this pulse. They are potentially induced by ecdysone.
Drosophila metamorphos