Using pha-1 as a Co-injection marker

Dear all,

Currently am using pha-1 as a co-injection marker for micro-injection.
I am using the mutant strain GE24(e2123) as host strain for microinjection.

I am facing two problems-

  1. They grow super slowly if kept at 15C
  2. The adult worms seem to be sterile (without eggs in the gonads) !

Its the first time that we are using this strain. So is there somebody using the same strain or have used before?
Can you please lend some valuable suggestions to overcome the problems that I am facing or some alternate strategies to do things more effectively.

Thanks a lot.
Waiting for your answer.

well….you might just want to switch to unc-119. it is in wide use and is incorporated into some great molecular tools. unc-119 worms are actually not that hard to inject.
just grow them on some good E. coli, like HB101.


Thanks for your reply.

Is it posible to analyse an axonal defect using this as a co-injection marker?


pha-1 mutant animals at 15°C should be largely wild type, so if your animals are sterile, then you should get a new thaw. Even wild types will be slower at 15°C, probably a week from L4’s to L4’s. We use lin-15 mutants for injections followed by rescue with pL15EK at 20°C. It’s true that unc-119 also works, but frankly it’s a pain to inject, particularly for newer people.


not much detail to go there, but a couple of quick observations that might answer your questions:

  1. The GE24(pha-1) strain does grow more slowly than N2.

  2. However, the majority of worms reach adulthood at 15°C (I have it presently in my 15°C incubator).

  3. My worms drop eggs without much coercion, so I expect yours should too.

All of this brings me to a few of questions:

  1. Are you talking about your transformed worms or your stocks?

  2. If you see no eggs then you get no offspring right? Does that mean you are continually reverting back to the stock plate you were sent???

  3. If the answer to 1. is ‘transformed worms’ then there are number of possibilities.

    If the answer is ‘stocks’, then how are you propagating the worms when not from the original plate (which must now be all but used up)?

  4. If you have offspring, and if no ‘higher force’ is at work here, then you must have worms carrying eggs right?
    then is it so that you are looking at worms that are too young and not carrying eggs…or something else just a confusing.



Thanks for your reply.

Is it posible to analyse an axonal defect using this as a co-injection marker?


‘It’s a question Jim, but not as we know it’

Would you care to elaborate…?

As kevinem stated, if your pha-1(e2123) strain is frequently sterile at 15C it’s likely your strain is defective; you should try replacing it, or rethawing from stocks if it’s been a long time. You might also check the temperature of your incubator - I have no idea what higher temperatures or fluctuating temperature would do to pha-1(e2123) but given a temperature-sensitive strain it’s something worth checking.

You probably shouldn’t use unc-119 (or unc-76, another good co-injection rescue marker) as a co-injection marker for studies of neuronal outgrowth. lin-15 is a good marker; I believe some groups use dpy-20, and a lot of people use fluorescent markers (myo-2-driven pharyngeal expression is fairly common, but other people use fluorescent reporters expressing in a very small number of neurons or in the coelomocytes, so the expression is limited and out of the way from their tissue of interest).