I don't have liquid nitrogen, so can I store whole plants (stem, root, leaves) for further DNA and enzyme analysis in a normal home refrigerator?
Dear Samrina,
Fresh leaves, stems or roots can be packed in a moist paper (soft paper that is used as hand towels), and into a zip-lock bag. Keep them in a polystyrene bin on ice, keep the bin closed. If you want to use leaves, try getting th whole twig so you can process it later, in the lab. You should be able to keep the plant material this way for 48 h. Alternately you can keep the twigs in a vase until you take to lab.
Regards
Thanks Veronica for picking up the finer detail. We routinely do SSR and I was thinking in those terms. If Samrina is interested in the enzyme profile at the time of harvest, then she has to freeze immediately.
thank you you both of them to guide me.I am working on antioxidative enzyme,so its also need immediately freezing point?And also which degree of temperature is suitable for storage?
Hi Samrina,
As you stated-- you DO NOT have liquid nitrogen....please take a look at this paper below. They were doing antioxidant enzymes as well. Look like -80oC is critical, read on........
[ http://www.ncbi.nlm.nih.gov/pubmed/15080616 ]
J Agric Food Chem. 2004 Apr 21;52(8):2167-73.
Pre-extraction preparation (fresh, frozen, freeze-dried, or acetone powdered) and long-term storage of fruit and vegetable tissues: effects on antioxidant enzyme activity.
Lester GE1, Hodges DM, Meyer RD, Munro KD.
Author information
1Kika de la Garza Subtropical Agricultural Research Center, Agricultural Research Service, US Department of Agriculture, Building 200, 2413 East Highway 83, Weslaco, Texas 78596, USA. [email protected]
Abstract
Activities of the antioxidant enzymes ascorbate peroxidase, catalase, dehydroascorbate reductase, glutathione reductase, guaiacol peroxidase, monodehydroascorbate reductase, and superoxide dismutase were assayed in honeydew (Cucumis melo L.) fruit and spinach (Spinacia oleracea L.) leaves either as fresh, frozen to -80 degrees C, frozen in liquid nitrogen, freeze-dried, or acetone powder, representing the various ways tissues are treated prior to enzyme extraction. Treated tissues were analyzed following treatment or stored for up to 8 weeks at -80 degrees C. Enzyme activities in fruit frozen with or without liquid nitrogen and leaves frozen with or without liquid nitrogen or freeze-dried were equal to those of fresh tissue. Enzyme activities in freeze-dried or acetone-powdered fruit and leaves and in acetone-powdered tissues were significantly higher or lower than those in fresh tissue. Enzyme activities in both tissues frozen with or without liquid nitrogen and stored for 8 weeks at -80 degrees C changed little; those in freeze-dried and acetone-powdered tissues, however, significantly increased/decreased over the same period. Fresh tissue should be used in antioxidant enzyme assays, but if storage is necessary, tissues should be placed directly into a -80 degrees C freezer.
For long time keeping whole plants you can try drying them vin litle warm dry air flux at 30° C, then store in an air-safe plastic PVC bag and keep all-time either in normal freeze 1°-4°C (for 3-5 weeks) or in deep freeze -10°- -30°C (for1-3 months) with a little loss of enzyme and other substance activities. If you want them fresh-and-wet 'looking' then use Ranjith Pathirama's and V. Mora's advices, which are best for your purposes. Handle plants carefully. Freeze quickly after drying. If its possible don't cut plants into pieces.Do not defreeze and then refreeze. If its possible use dry oxyzen-free air in the bags or only dry cold nitrogen or hydrogen and remove the abudant air from the bags, for better results. I wish you best effort, Samrina.
What about dry ice? You will get approx. -80C. Just watch concentration of CO2.
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