Multichannel Systems Roboinject Manual - Manual (Page 51)

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4 Injection
4.1 About Injection with the Roboinject
Manual injection is often a limiting factor in high-throughput screens. The Roboinject injects
Xenopus oocytes and other large cells or small embryos in a fully automated way.
For example, injection and cultivation of Xenopus oocytes are performed using disposable
standard 96 well plates, which are commercially available from several providers. The oocytes are
plated into the wells in a couple of minutes and can be kept there for several days. They quickly
settle within the cone-shaped wells and adhere to the well bottom after a few hours. The oocytes
do not have to leave the plate anymore; you can easily transfer the oocytes from the incubator to
the Roboinject and back again. For other cells or organisms custom-designed well plates can be
easily adapted.
The cDNA, mRNA or compound to be injected is automatically taken up into the injection needle
and then pushed into either the nucleus or the cytoplasm by the positive displacement method.
Using positive displacement has the advantage that the injected volume is always as pre-selected.
Importantly, it is independent of the viscosity of the samples or the opening diameter of the
injection needle. Another advantage of positive displacement based injectors when compared
to air-pressure driven system is, that there is no need of tedious volume calibrations.
The overall expression rate you can achieve with the Roboinject is by no means worse than success
rate with manual RNA injection of Xenopus oocytes and can reach close to 100 percent. Of course,
the success rate depends on the receptor type and oocyte performance.