Worm Breeder's Gazette 12(1): 52 (September 1, 1991)
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have devised a very convenient, semi-automated injection setup closely based on the system of Mello and Ambros (WBG 11(4):7). It provides many of the advantages of the digital automated systems available, at a minute fraction of the cost. Our system is very similar to that described by Mello and Ambros, and anyone with a system like theirs can upgrade. The main difference is that the 3-way ball valve, used to control the duration of injection flow, has been replaced with an electronic solenoid-operated valve. This permits foot pedal (or any other way you'd prefer to operate an electric switch) control, and leaves both hands free to deal with micro-manipulation and focusing. In addition, the solenoid operated valve can open and close in a fraction of a second, permitting very precise control of flow. If the needle happens to be in the wrong place, a quick tap will show this without appreciably damaging the worm. At high pressure, quick on/off pulses also appear to aid in unclogging clogged needles, while at low pressure the system is ideal for pulse-filling oocyte nuclei or gonads. By varying the pulse time, it is possible to compensate for the flow characteristics of individual needles.
By selecting the right match of components, it is possible to construct a system as drawn below which is extremely compact, attaching directly to the pressure source, requiring no cut hypodermic needles or tubing (except the piece connected to your needle) and occupying no bench space at all. Shown not to scale below, the entire system that attaches to a pressure regulator measures only 3" x 5" x 3/4", and minimizes dead gas space. Fittings such as those described by Mello and Ambros can be used; however, the key is to replace the 3-way ball valve ( B41X52 )with a solenoid valve such as the NUPRO® 110vac model. All metal-to-metal connections should be wrapped in Teflon-based tape. Controlled pressure can be supplied to this system with a nitrogen tank via a high-pressure regulator or with a pump or in-house compressed air via a low-pressure regulator.
For a complete parts list and any additional information, please contact us. In addition, a pre-assembled and tested complete system including foot pedal controller and the tubing that attaches directly to your needles can be obtained from TRITECH Research (see above address and phone number). As an introductory offer to worm breeders, the system is available for $210, or $360 with high-quality pressure regulator and tank fitting (approximately the retail cost of the unassembled components).
[See Figure 1]