Zebrafish facility problem - underdevelopment of embryos

[zebra]

Hi all,

Our problem is that embryos,
which were injected (independently from what they were injected with)
exhibited severe delay in development (at 24hpf were still at the stage corresponding to about 10hpf).
From the other hand embryos, which were not injected (chorion was intact) were developing normally, with only small number (about 5-10%) or no embryos exhibiting delayed phenotype. To avoid further comments: embryos are kept in 28C, in small E3 medium volumes with addition of methylene blue, about 50 per plate.
At the same time we could observe a film of bacteria? at the bottom of
Petri dishes just after 24 h.

Adult fish within the system did not exhibit any behavioral
change, increased death rate or disease symptoms.
I would be grateful for any advice.

Best
Beata

[moulderg]

I would wonder if the methylene blue was a problem. I don't use it in several years of work. It is somewhat toxic.

[sgrego08]

Are these mRNA injections? What concentration are you injecting? High injections of RNA can cause developmental delays. Conversely, what else is in your injection solution?