Dynamics of DNA hydroxymethylation in zebrafish

Area of Science:

• Epigenetics
• Developmental Biology
• Genomics

Background:

• DNA methylation reprogramming involves converting 5-methyldeoxycytidine (mC) to 5-hydroxymethyldeoxycytidine (hmC) in mammals.
• hmC may function as an epigenetic mark with tissue-specific roles.
• Data on hmC levels and distribution in zebrafish are limited.

Purpose of the Study:

• To quantify hmC and mC levels during zebrafish development.
• To determine the tissue distribution of hmC in adult zebrafish.
• To compare hmC patterns in zebrafish with those in mammals.

Main Methods:

• High-performance liquid chromatography mass spectrometry (HPLC-MS) was used.
• Quantification of hmC and mC in zebrafish at various developmental stages (0.5 to 96 hours postfertilization).
• Analysis of hmC and mC levels in adult zebrafish tissues (brain, muscle, liver, intestine, testis).

Main Results:

• mC levels increased from 1.9% at 0.5 hpf to 8.4% at 96 hpf and remained similar in adult tissues.
• hmC was undetectable until 12 hpf, then increased to 0.23% by 96 hpf.
• Adult zebrafish brain had the highest hmC levels (0.49%), with lower amounts in muscle, liver, intestine, and testis, showing an inverse correlation with mC.

Conclusions:

• Zebrafish exhibit similar hmC tissue distribution and levels in adults compared to mammals.
• Zebrafish display distinct hmC patterns during embryonic development compared to mammals.
• Zebrafish serve as a valuable model for investigating the tissue-specific functions of hmC.