What is the fine-grained topic of the following text: Three histone modifications associated with active transcription, histone H3 lysine 9 acetylation (H3K9ac), H3 lysine 4 trimethylation (H3K4me3), and H4 lysine 5 acetylation (H4K5ac) were enriched at specific Ltf promoter regions after DES treatment, but this enrichment was not maintained in adults. Only return the topic.
Histone modifications associated with active transcription in specific Ltf promoter regions after DES treatment.