Osmoregulation teaching.

So glad that after a teaching period from 1:30pm to 9:30pm, I was rewarded a comment that "Our TA is cool, much better than the previous one which is so boring". I do not know who is the previous one but I was so glad to hear about a comment like that.

Yesterday, we learned how to use a microscope, observed prepared slides and made some fresh slides demonstrating osmoregulation in living cells. We were supposed to use Neutral Red to make inner epithelium of onions stained visible but it seemed that the dye was dead. So we switched to outer epithelium which was purple in nature. Purple onion cells in 3% NaCl shrunk with some space among cells which were initially tightly connected.

One problem/question I cannot answer is that, why shall we use sucrose solution to activate mitochondria when we stain them with Janus Green B? JG is blue when oxygen is present while pink when oxygen is absent. If we add more sucrose, mitochondria will consume more oxygen which makes the dye turn to pink. However, what we expected is to observe blue mitochondria. According to this logic, sucrose does not help to make mitochondria clear at all.