Related Experiment Videos
Is the onset of actin histidine methylation under development control in the chick embryo
Insights
Previously, chick skeletal muscle actin showed delayed histidine methylation. However, this study found consistent actin histidine methylation across chick cardiac and brain tissues, indicating it is not developmentally regulated.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Biology
Background:
- Previous research indicated a developmental increase in chick skeletal muscle actin histidine methylation between embryonic days 11 and 18.
- Adult and non-muscle actins typically contain 1 mol of 3-methylhistidine per mol of actin.
Purpose of the Study:
- To investigate if actin histidine methylation onset is uniform across different tissues in chick embryos.
- To determine if actin histidine methylation is under developmental control in cardiac and brain tissues.
Main Methods:
- Analysis of 3-methylhistidine content in cardiac muscle actin from embryonic Day 2 to hatching.
- Analysis of 3-methylhistidine content in brain actin at embryonic Days 9, 11, and 14.
- Utilized both unlabeled actin samples and in vivo [3H]histidine labeling for accurate quantification.
Main Results:
- Cardiac muscle actin consistently showed 1 mol of 3-methylhistidine per mol of actin at all embryonic stages analyzed.
- Brain actin also consistently exhibited 1 mol of 3-methylhistidine per mol of actin at embryonic Days 9, 11, and 14.
- Skeletal muscle samples from Days 11-18 embryos confirmed the presence of 1 mol of 3-methylhistidine per mol of actin.
Conclusions:
- Contrary to prior reports, actin histidine methylation in chick embryos is not under developmental control.
- The level of 3-methylhistidine in actin appears to be constant throughout embryonic development in cardiac and brain tissues.
- This suggests a constitutive rather than developmentally regulated methylation process for actin histidine.
Abstract:
It had previously been reported (B. Krzysik, J. P. Vergnes, and I. R. McManus (1971) Arch. Biochem. Biophys. 146, 34-45) that prior to day 11 of embryonic life chick skeletal muscle actin contained little or no 3-methylhistidine, and that between Day 11 and 18, the degree of actin histidine methylation increased until it leveled off at 1 mol of 3-methylhistidine/mol actin. This is the value seen in adult muscle and nonmuscle actins so far analyzed. To determine whether this delayed onset of actin methylation occurred simultaneously throughout the organism or differed from tissue to tissue, the 3-methylhistidine content of cardiac muscle actin from Day 2 of embryonic life to hatching and of brain actin at Days 9, 11, and 14 were analyzed. These results, obtained by analyzing unlabeled actin samples as well as samples labeled in vivo with [3H]histidine, showed that at all stages, 1 mol of 3-methylhistidine was present per mol of actin. When skeletal muscle samples obtained from Day 11 to 18 embryos were analyzed 1 mol of 3-methylhistidine/mol of actin was observed. Thus, in the chick embryo, contrary to those reports published earlier, it was found that actin histidine methylation is not under developmental control.