Expression of myogenic genes in chickens stimulated in ovo with light and temperature.

Since chicken myogenesis is tightly controlled by myogenic regulatory factors (MRFs), the external stimuli (e.g. light or temperature) affecting the proliferation and differentiation of the muscle cells have a primary effect on the gene expression of MRFs. The aim of this study was to analyze the expression of some of MRF genes (MyoD1, myogenin and Myf5) in response to the stimulation of chicken embryos with green light (AL group) or increased temperature (38.5°C; AT group) on day 18 of embryo development (18ED) as well as on days 4 (4PHD) and 8 (8PHD) post hatch. To achieve this goal a quantitative reverse transcription polymerase chain reaction was used. The most prominent differences in gene expression were observed before hatching. Relative expression of MyoD1 on 18ED was higher (p<0.05) in AL and control (AC) groups in comparison to the AT group. Myogenin expression on 18ED was lower (p<0.05) in control chickens than in both treated groups. Light stimulation in ovo decreased (p<0.05) the Myf5 expression on 18ED in comparison to the control group. Green-light illumination applied during in ovo development had more pronounced effects on mRNA level of MRFs genes measured during both the pre- and post hatch development. The elevated temperature applied during embryonic development affected only the 18ED time point. This suggests that the effect of green-light illumination on chicken myogenesis was more prolonged than that of elevated temperature.