Page 153 - phytochemistry general program
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distributed in the aqueous media.
Subculture
Subculturing is the transfer of part of callus into fresh medium. This must be done
at time intervals because of the following:
1- Growth on the same medium for an extended period of time will lead to
depletion of essential nutrients and to the gradual dryness of the agar due to the
water loss.
Metabolites secreted by growing cells may also accumulate to a toxic level in .3
the medium.
Done every 4-6 weeks.
After maximum growth, it is transferred to soil.
Rules of subculturing
The transferred fragments of callus must be of sufficient mass to assure renewed
growth on the fresh medium. If the inoculum is too small it may exhibit very slow
rate of growth.
Callus should be divided (Friable callus can be subdivided with a thin spatula & .1
Hard callus growth can be transferred to a sterile petri dish and sliced into .2
fragments).
During subculturing, strict aseptic precautions should be followed to avoid
contamination.
Quantitation of tissue culture (growth curve)
The growth of a culture over a period of time, whether it is a callus or a
suspension culture, is characterized by an increase in cell number, an increase in
volume or mass, and changes in biochemistry and cellular complexity.
The growth of a cell suspension culture can be followed by measuring a selected
parameter at intervals during the growth cycle. e.g. fresh weight, dry weight, cell
number, total protein synthesis such determinations are time consuming. Cell
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