Describe the steps required to produce identical genetically modified AD mice.
Suggest why having an animal model of a human disease is helpful.
Scientists wanted to find out whether alterations in gene expression were important in the failure of the AD mice to learn. Groups of normal mice and AD mice were either trained so that they could learn to swim a water maze, or given no training. The mice in the four groups then had mRNA extracted from the memory-related regions of their brains. Reverse transcription of the mRNA from each group was carried out and the resulting cDNA was labelled with fluorescent nucleotides. This was then used in DNA microarray analysis on slides containing DNA sequences from $33696$ mouse genes. Explain the principles behind this DNA microarray analysis.
Table 5.1 gives a summary of the microarray findings for differences in gene expression in: • an untrained AD mouse compared with an untrained normal mouse • a trained AD mouse compared with a trained normal mouse.
Calculate the percentage of mouse genes whose expression has been shown to be affected by training. Show your working.
State what the results in Table 5.1 indicate about the effect of training and learning on gene expression in brain cells.
The genes expressed in the brains of normal mice during training and learning encode proteins that are important in synapse and memory formation. Many of these genes are regulated by one transcription factor, a protein called $Crtc1$. To improve learning in AD mice, researchers induced over-expression of the $Crtc1$ gene in the brains of AD mice by using a virus vector to deliver the gene to mouse brain cells.
State the name given to this form of treatment.
Suggest the effects of over-expression in the brain of the $Crtc1$ gene on AD mice.