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Drosophila Microinjection - All you need to know

Important: Preparing your DNA sample

Sample quality is the major factor that determines the success or failure of microinjection work. Please read our guidelines for sample preparation before sending your samples for microinjection.

 

Help with experimental design

We are happy to assist with selecting the best host stock (embryos) for your microinjection experiment and with other aspects of experimental design. Please contact us at flyinject@gen.cam.ac.uk. If you prefer a host stock that is not currently kept by the Fly Facility, please send us some healthy flies or direct us to where we can obtain some.

 

Sending your samples for microinjection

Please download and complete the Request for Drosophila Microinjection Work form and send it with your samples for injection to Alla Madich, Department of Genetics, Downing Site, Downing Street, Cambridge, CB2 3EH. UK.

If your sample tube is crushed during transport, your sample may be lost through the lid opening or the tube splitting. Therefore, it is best to mail your sample in a padded envelope (Jiffy bag) or a box. Sealing the lid with parafilm or similar will help prevent the lid opening and also guard against evaporation.

 

Choosing sample names

Our staff need to be able to communicate with you, and with each other, about individual injection samples. Ideally, your sample names should be relatively brief to make this communication easier. However, the names should also be sufficiently unique that they are unlikely to match other sample names currently in our database. So "ABC-123" might be a good choice, whereas "Sample A" is likely not unique, and "pUAST-attB-5'GFP-exonII-frag-3'MycTag-7a" is just too long!

 

Sending fly stocks for microinjection

If you would like us to inject into your own fly line, or into the progeny of a cross that you have set up, please provide us with sufficient flies to make an injection cage. To set up a cage, we need a minimum of 500 flies (300 females, 200 males) and would prefer closer to 1000 flies. Please make sure the flies you provide are free of mites or we may not accept them for injections.

 

Receiving your injected flies

When the service is complete, we will send the injected flies to you via regular mail. In our experience, this approach works well and it is rare that the flies fail to reach their destination. For service plans that involve screening, crossing and/or stock construction (e.g. Plans 2, 3, 5 and 7) we will resend flies at no additional cost if the original package fails to reach you. However, for 'injection only' requests where we ship all the injected larvae (e.g. Plans 1, 4, 6 and 8) we will not repeat the service if you fail to receive the larvae unless the failure clearly results from our own error.

Injection-only requests from outside the UK: In our experience, shipping times to countries outside the UK can vary significantly. This can cause problems for clients outside the UK who make injection-only requests (e.g. Plans 1, 4, 6 and 8) as irreplacable injected larvae may not survive the trip. Therefore, if you are making an injection-only request from outside the UK, we recommend that you arrange alternative shipping (e.g. courier service) at your own expense. You will need to ensure that all the necessary information is proivided to the Fly Facility to ensure a successful shipment.

 

Culturing your injected larvae

For injection-only requests (e.g. Plans 1, 4, 6 and 8), every surviving G0 larva is precious so it important to provide the best possible culture conditions. After injection, we recover viable larvae in a yeast paste/agar plug which we then transfer to a plastic tube containing fly food. We mail this tube to you. Ideally, you should put the tube in a humidified incubator at between 18oC and 25oC.

Before placing the tube in an incubator, check if there are any signs that the food is drying out, since dehydration is the biggest threat to larval survival. Are there gaps between the food and the side of the tube? Does the food appears lumpy rather than smooth? If the food appears to be drying, you can add water directly to the tube. Do not fill water above the surface of the food as you will risk drowning the larvae. Alternatively, you can gently push a ball of tissue paper into the surface of the drying food and then saturate the paper with water. You can also add a liquid yeast paste to the food surface which will both hydrate the tube and nourish the larvae. It is worth continuing to monitor your tubes of injected larvae for dehydration. This is particularly important if your incubator is not humidified or relies on passive humidification (e.g. trays of water placed in the incubator).

We also recommend that you make regular collections of adults when they start emerging from the tube. In our experience, adult flies show better survival when removed from the original tube to a fresh tube shortly after they eclose.

 

Paying for your microinjection work

Click here for a description of our prices and plans

  • University of Cambridge users outside of the Department of Genetics: Please email a copy of your Purchase Order to (simon.collier@gen.cam.ac.uk) at the time you send your samples. Also, please include the Purchase Order number on your Request for Drosophila Microinjection Work form. Invoices for microinjection work are normally sent at the completion of the service unless you request otherwise
  • Users outside of the University of Cambridge: You have two options:
  • Option 1: Purchase Order: Please email a copy of your Purchase Order to (simon.collier@gen.cam.ac.uk) at the time you send your samples. Also, please include the Purchase Order number on your Request for Drosophila Microinjection Work form. Invoices for microinjection work are normally sent at the completion of the service unless you request otherwise
  • Option 2: Credit card:
  1. Credit card users in the UK: Please visit our Online Store for UK Business. Enter the total cost of the sevice including VAT (all UK users outside of the University of Cambridge are required to pay VAT at 20% on their microinjection payments). You will be asked to provide the name of the person who submitted the original Microinjection Request Form as well as their department and institution affiliation. Please provide this information, it will allow us to confidently match your payment to a specific microinjection request.
  2. Credit card users in the rest of the European Community: Please visit our Online Store for EC Business. Enter the total cost of the service excluding VAT. You will be asked to provide the name of the person who submitted the original Microinjection Request Form as well as their department and institution affiliation. Please provide this information, it will allow us to confidently match your payment to a specific microinjection request.

 

VAT charges for Microinjection work

We have been informed by the University of Cambridge Finance Division Tax Office that our Microinjection Service does not qualify for medical VAT-exmption. Consequently all microinjection charges for UK research groups (outside of the University of Cambridge) are subject to VAT at the standard rate (20%).

 

What if my microinjection experiment fails? 

For Plans 2, 3, 5 and 7 we will inject a further 200 embryos (at no extra cost) if we do not obtain our guaranteed number of transformants. However, Plans 1, 4, 6 and 8 are injection only – we do not routinely re-inject if no transformants are obtained. Click here for a description of Plans 1-8.

 

Acknowledging the Fly Facility

Please acknowledge 'The University of Cambridge Department of Genetics Fly Facility' in any publications or public presentations resulting from the use of microinjected flies

 

Our Terms and Conditions

To use our microinjection service, you must agree to our Term and Conditions for Microinjection work.

Contact Information

Tiny fly

E-mail contacts

Simon Collier (Fly Facility Manager): s.collier@gen.cam.ac.uk

General Fly Facility enquiries: flyadmin@gen.cam.ac.uk

Microinjection enquiries: flyinject@gen.cam.ac.uk

Fly food enquiries: flymedia@gen.cam.ac.uk

Stock collection requests and enquiries:

Address

Department of Genetics,
University of Cambridge, Downing Street,
Cambridge CB2 3EH,
United Kingdom

Phone: +44 (0)1223 765124
Fax: +44 (0)1223 333992

 

The Fly Facility webpages are maintained by Simon Collier. Please contact me ) if you have any problems using the site.