Onion root

[Eggman]

Hi all,
I have a teacher here who wants to do an experiment to stain onion root that she vaguely remembers doing when she was in high school. Does anyone have a method of this experiment I could get a hold of? And any idea where I can acquire onion root? Is it easiest just to take a regular onion, sit it on a flask with water and let it grow?

[lada]

Yes, I buy an onion and grow new root by sitting it on the conical flask or small beaker and have enough water to just touch the roots.
Not sure about the exp, but they genly crush or slice the root, colour it and observe under microscope for mitosis( so root must be freshly growing)
Lada

[ri]

Hi,
by Googling 'onion root stain', it comes up with a few ideas that may jog your teachers memory. I have been lucky to have been given an onion root squash with superb mitosis displayed in all it's stages. It's labelled '5 AU stain'-wish I was a histologist to know what that means!
Good luck,
~Robyn

[bindi]

We are boring and have bought prepared slides!

[ellice]

We used to do this experiment using alfalfa sprouts, but have since resorted to prepared slides.

[elly]

Hi Justin,
The stain we have used to show mitosis in onion and garlic root is aceto-orcein stain, (approx $30 per 100mls from the chemical companies)

Hope this helps

[judygee]

Justin - just catching up with your post of last week re Onion root tip squash using Aceto-orcein. We have not had any success with this Prac! Yes we can grow the onion roots (remove old dried roots, sit base in jar of water & wait till 1.5 - 2.5cm in length). As near to sunrise as possible - remove end 1cm & place in fixative solution (Acetic Ethanol) to remain for 12 to 24 hours. Heat 1M HCl to 60 degrees Celcius transfer root tips to hot acid and leave for 5 mins (Do not continue to heat acid!) Place root on clean slide cut off last 2 - 3mm, add one or two drops of Aceto-orcein. Using a scalpel break tip into fine pieces (do not allow to dry out - add more stain if necessary!) Place cover slip over root tip, lay small piece of folded paper towel over c/slip, place left thumb on towel directly over c/slip and with right thumb press down gently but firmly on top of left crushing the cells (do not twist thumb!) Aim is to crush without disrupting the cell's position. Draw more stain under the c/slip if necessary. Use microscope to examine slide! I am assuming our technique is off as we have had no success with this prac. We do have prepared slides, so we know what we are looking for, but alas, no joy!! Would be interested to know how you fare!!!! Cheers. Judy.

[Trudy]

I've tried this a couple of times as well and only had limited success. Its very time consuming and I'm sure all in the way you hold your tongue at various points, there is a method in the book The Laboratory (available from Southern Biological- a must if you don't already own one) look under aceto-orcein stain and acetic ethanol fixative sol. Reads a bit like a witches brew - especially the bit when making up the fixative with regards to harvesting of the root - "When the roots are 1.5 to 2 cm and the time is as close to sunrise as possible......" Must be the optimum division time anyway I vote go with slides much much easier and with guaranteed results.
Good Luck
Trudy