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To inoculate the culture jar with the flies, sweep the flies onto the end of a piece of filter paper. Lay the
culture jar on its side and remove the plug. (Do not allow the flies to fall off the paper.) With the handle
of the camel's hair brush, push the end of the filter paper down into the medium (See Figure 2). Plug
the jar. Allow the jar to remain on its side until the flies awaken. This will help to avoid the possibility of
the unconscious Drosophila falling into any moisture and drowning.
Figure 2
It is good practice to check the characteristics of each strain under magnification when subculturing.
There is always the possibility that a stray fly may enter the culture and cause loss of the strain's purity.
Stocks should be subcultured every 2–4 weeks depending upon the temperature. Old cultures should
be discarded after the new cultures become established, in order to avoid contamination. At least two
cultures of each strain should be kept in case one should be unsuccessful.
It is important to make sure that each culture jar is labeled with the type of fly and the date the jar was
inoculated with the flies. The best way to do this is to use the shorthand notation for the particular
strain of fruit fly in the jar. An example of a few shorthand notations would be: + = wild type (red eye),
vg = vestigial wing, b p c = black purple curved. Small letters refer to recessive genes, capital letters
refer to dominant genes (e.g., B = Bar eye). Letters separated by spaces refer to genes on the same
chromosome (e.g., wem = eosin miniature). Letters separated by a semicolon (e.g., w;se – white sepia)
refer to genes located on different chromosomes.
Therefore, a culture jar with a heldout strain of D. melanogaster on February 14 would have the
following label:
ho
2/14
There are so many other notations and additional symbols that it would be impossible to list them
here. All cultures are shipped with a label giving the name of the strain, the shorthand notation, and
the chromosomes on which the genes occur.
Cultures of Drosophila should be kept at a relatively constant temperature closely approximating room
temperature, no lower than 20°C (68°F) and no higher than 25°C (77°F). They should not be exposed to
direct sunlight and may be kept entirely in the dark.
