Microinjection has become a very important technique for inserting substances into living cells. This is a very important application for cell and molecular biology studies, genetic engineering, production of transgenic animals, in vitro fertilization, and cloning. A very fine micro needle attached to a specialized optical microscope setup called a micromanipulator is used to penetrate the cell membrane or the nuclear envelope and inject its contents using either hydrostatic pressure (pressure injection) or electric currents (ionophoresis). Numerous types of substances can be injected in this manner, including drugs, histochemical markers, antibodies, proteins, flurochromes, RNA and DNA.
The MMN-1 coarse manipulator from Narishige enables remote controlled movement of a micro-pipette to the ideal position within the observation field of a microscope. It is suitable for a wide range of microinjection applications. It is a compact precision instrument, easy to assemble and takes minimal space while ensuring a wide working space on the microscope stage. In addition, it can be easily adapted for both right and left handed users (as is the case in my lab). The bar mount system of the MMN-1 coarse manipulator makes it very versatile and easily adaptable to a variety of installations, including liquid hydraulic micromanipulators and it is compatible with any microscope. It is very easy to operate and has a movement range in the 3 axes of X: 30 mm, Y: 30 mm, and Z: 30 mm.
The control of the MMN-1 coarse manipulator is made even easier by the use of a joystick. In our lab, we have the MMO-202ND three-axis hanging joystick from Narishige. Like all Narishige products, it is a precision instrument that enables fine movement in 3 dimensions without changing knobs, and it can be used with either the right or left hand. The joystick can be moved in the X-Y plane by pushing in the desired direction and in the Z plane by rotating the top knob. The joystick is very compact and space saving, but at the same time, it enables delicate movements with enhanced resistance to vibration. The working distances of the head stage secure 10 mm in all (XYZ) directions.
The joystick has to be handled with care, kept at constant temperature and in a dry environment. When it is not in use, the control knobs should be returned to zero and the teflon tubes should be kept affixed to the microscope with scotch tape to avoid unwanted movements during injections.
The micromanipulator is attached to a pipette that is used for microinjections. The pipette is set at a standard point by using the coarse manipulator to place the needle tip in the field of view. Next, the fine control is used to bring the tip of the needle and the cell to be injected in close proximity and to perform the injection.
I use the MMN-1 coarse manipulator and MMO-202ND three-axis hanging joystick micromanipulator system attached to a Nikon TE-2002E microscope for microinjection of Drosophila embryos with various proteins, fluroochromes, and inhibitors. Briefly, the embryos are aligned on agar plates, dried, and covered with halocarbon oil. They are injected using a 10X objective and then visualized with a 60X objective. I use a plastic syringe attached to the micromanipulator to pressure inject the embryos.
Postdoc
Department of Medical Genetics and Microbiology
University of Toronto