 One thing that research on Alzheimer's disease appears to be showing us is that the brains of people with Alzheimer's disease are low in oxygen and we can use the word hypoxic to describe this state. Now we use zebrafish embryos and also adult zebrafish sometimes in order to study the activity of the genes involved in Alzheimer's disease. So how can we expose zebrafish embryos or adults to low oxygen conditions? Well, one way is shown here. Here is a bottle of nitrogen and so this is basically the nitrogen gas but there's no oxygen present at all and here you can see a bottle of water that we would place the embryos or the adult fish in and by simply bubbling the nitrogen through the water we can actually reduce after a number of hours the oxygen levels in that water to about one tenth of what they would normally be. These are hypoxic conditions and we find that when we place zebrafish embryos or adults in that water solution we actually see an increase in the activity of the genes involved with Alzheimer's disease.