     
|
|
|
Bennett, Jack. 1999. An inexpensive, simple etherizer for classroom use.
Dros. Inf. Serv. 82: 126. View PDF
Hinton, Claude W. 1999. Use of the wvc chromosome in class laboratories.
Dros. Inf. Serv. 82: 126-127. View PDF
A simplification of an etherizer reported by Lloyd L. Arnold (Amer. Biology Teacher 19: 248-251) has proved very useful in the student and research laboratory. It consists of a polyethylene bottle of the type used to dispense catsup, mustard, or salad dressing, which has a long (3 cm) pointed spout with a small (approx. 1 mm) hole in the end. The bottle is loosely packed with cotton, 5 cc of diethyl ether is added (sufficient for several hours’ use), and the cap and spout are replaced. In use, the vial or bottle containing flies is gently inverted and the spout is carefully inserted past the cotton plug; ether vapor is expelled into the vial or bottle by pressing the sides of the etherizer. CAUTION: Remove spout before releasing sides of the etherizer or the flies may be drawn into the etherizer. When the flies succumb they fall on the cotton plug, which can then be removed and the flies shaken off for examination. The polyethylene bottles cost about 25 cents (and are often thrown away by restaurants and housewives), and are virtually unbreakable. They require much less ether than most other types, and are adaptable to almost any type of container, including the polyethylene population cages.
Several phenomena rarely encountered in undergraduate genetics laboratories can be easily demonstrated in simple crosses involving the unstable wvc ring chromosome (Genetics 40: 951-961), for example, wvc f / y w females by y v f / Y males. As a consequence of elimination of the wvc chromosome, gynandromorphs are frequently encountered among the progeny; those gynandromorphs mosaic in the head may be used to illustrate gene hormones. Exceptional males are also abundant among the offspring; and, although many of these are the result of wvc loss, others are due to primary nondisjunction. This phenomenon is also responsible for exceptional (non-forked) females occurring in the progeny. Position-effect variegation is manifested by the eye pigment of the parental females but not in the F1 wvc females; the effect of the Y chromosome in suppressing position-effect variegation is demonstrated by the exceptional females’ phenotype. To insure maintenance of instability, multiple lines of the stock must be carried and selected frequently.