O.S. wrote:1. I have VERY solid grounds to ask for first co-authorship, but be prepared for the lab mate to say no.
2. I can ask for the paragraph with the mouse description to be taken out of her paper. Since her paper will most likely be published before mine, she will still get a lot of credit for the mouse, but at least everybody who takes time to track down the mouse design will give me the credit (for a job interview I can also prove this was my work)
3. If all fails, I can go to the editorial board of the journal and make a bad case, and like everybody said, ruin my reputation; and most probably still lose in the end.
In the end after a long conversation with my PI he realized it was a big mistake not to be given credit for the mouse and asked me what I want. I chose solution #2 (take out the paragraph with the mouse description) since I do not want any more confrontation with the lab mate.
I don't think this is a good decision. Whether you have a confrontation with your lab mate or not is not so important; what *is* important is your level of contribution to the research and if you think you deserve a shared 1st author position you should say so.
What I find more disturbing, though, is that you write "I have received the manuscript only after it was submitted to the journal". This is definitely not acceptable. You should definitely talk *and* write an email to the boss of your boss.
Before submitting a paper, all co-authors must have been given the chance to read and approve the manuscript. Goes without saying. If your PI does not consider this necessary, no wonder he also doesn't care about your contribution to the research.