• Collection of mammary glands from trapped possums

• Snap freeze mammary glands next day

• Extract RNA fragments corresponding to J protein, C-alpha and pIgR (polymeric Ig receptor)

• mRNAs for C-alpha, J proteins and pIgR were expressed throughout lactation

• Meaning IgA is transferred to milk throughout lactation

• But – 2 main periods of increased expression of these genes

• 1. At beginning of lactation

• 2. At end of switch period (when young grows fur and is about to leave pouch). This is around 106-115 days.

• At both these times, young is about to be exposed to new pathogens

• So, it needs protection in form of more IgA.

• Mammary glands frozen as soon as possible, I.e. morning after trapping

• Random selection of possums as they have been trapped

• The mammary glands collected ranged from day 1 to day 190 of lactation

• Testing for presence of these genes is a good way of monitoring IgA transfer into milk

• There may have been only a few captured possums from a certain lactation period giving us weak evidence.

• Only 35 possums were captured – is the sample large enough?

• Trapping method may favour certain individuals e.g. those in need of food.

• No direct measurement of IgA taken

•Unclear aim

• Main queries were with sample size and composition i.e. were there enough of each lactation period to get a good valid results?

• Overall study had a good conclusion however its difficult to know if they fulfilled the aim of the experiment.