VLAD PRELUCA, BOGDAN HORATIU SERB, SANDA MARCHIAN, DITER ATASIE, MIHAELA CERNUSCA MITARIU, ALEXANDRU SABAU, CRISTIAN TANTAR, DAN SABAU DIMETHYL-SULFOXIDE IS A SUITABLE SOLVENT FOR FLUORESCENT MICROSCOPY DETECTION OF MEDIUM AND STRONG HEAT SHOCK INDUCTORS USING TRANSGENIC ZEBRAFISH Heat shock inductors have potential as treatment for degenerative and protein misfolding diseases. Dimethyl-sulfoxide is widely used as a solvent in pharmacological screening tests and has been shown to have heat shock induction effects. Transgenic Tg (hsp70l:EGFP-HRAS_G12V)io3(AB) zebrafish larvae were exposed for 24 hours to dimethyl-sulfoxide in concentratios of 0.1-2%, and to moderate heat shock inductors pentoxifylline and tacrolimus. Positive controls were exposed to 35, 38 and 40°C for 20 min, and incubated for 24 h at 28°C. Heat shock response was measured by fluorescence microscopy and signal intensity quantification in FIJI. Dimethyl-sulfoxide caused a dose-dependant increase in fluorescent intensity, but significantly lower compared with exposure to 38 and 40°C. Pentoxifylline and tacrolimus induced a significantly higher increase in fluorescence compared with 0.5% dimethyl-sulfoxide. Thus, although dimethyl-sulfoxide has independent heat shock induction effects, concentrations of up to 0.5% are suitable for heat shock response screening tests.