28.6.13

Date: 28.6.13
Time: 13:00
Location: The Dunn School of Pathology, Oxford, England

Trypanosome division

My final day in Oxford began with Helen, counting cells under the microscope that have been tagged with DAPI, which tags the nucleus and kinetoplast.  The cells were then counted and sorted into groups based on where they were in the life cycle.  The five groups were 1K1N, 2K1N, 2K2N, Zoid, and Other.  1K1N,
2K1N, and 2K2N refers to the number of nuclei and kinetoplast in the cell.  For example, 1K1N has one nucleus and one kinetoplast, so that cell has either just undergone cell division or has not yet begun cell division.  2K1N cells have begun dividing, as they contain two kinetoplasts, which are the first part of the cell to divide.  2K2N cells have almost completed division, as they contain both two kinetoplasts and two nuclei.  Zoids are cells where division has gone wrong, they contain only one kinetoplast and no nuclei.  Other is for any cells that have encountered other types of mutations or difficulties when dividing.  The amount of cells in each cell stage is proportionate to how much time the cell spends in that cell stage relative to time spent in other stages of the life cycle.  About 75% of the cells can be found in the 1K1N stage, between 10% and 15% in the 2K1N stage, about 5% in the 2K2N stage, and the rest of the cells are either zoids or other.  A total of 500 cells are counted each session and the data is plugged into excel to graph the cell numbers.  This data is usually taken over many trials, where each session a protein is added or subtracted (changing a variable) to observe how that affects the cell's life cycle.

After lunch, Eva began diluting cell samples.  She is studying the role of the flagella in the bloodstream form of leishmania.  She believes that the flagella may act as an antenna, sending signals to other cells.  In order to test this, she got mutated cells from Oregon that have been manipulated so that signals cannot be passed from the flagella.  She froze some down for safekeeping but then wanted to dilute her sample further to a lower cell density.  Siwan and I were then tasked with discovering the amount of solution needed to attain the desired cell density.  The cells were then transferred and allowed to grow in the incubator.

We then took a trip downstairs to learn about mass spectrometry.  Mass spectrometers work by taking

Mass Spectrometer

samples and refining them until they are incredibly small.  They are then released into the machine in the form of a fine spray that is channelled through electric fields.  The sample is then brought up into a rotor that spins the components around, analysing them based on mass.  This gives a graph of the sample sorted into peaks based on mass and relative concentration.  This information is in-putted into a database that will turn the numbers into the compounds present in the sample, and to what degree.  Mass spectrometers are incredibly useful

Our favourite Major MassSpec

because they are able to identify the empirical formulas of compounds.  They are used in almost every lab as well as in law enforcement.  Tabletop mass spectrometers are used in airports to detect drugs or explosives.