Related Experiment Video
Updated: Aug 13, 2026
15:42
Double Whole Mount in situ Hybridization of Early Chick Embryos
Published on: October 27, 2008
H2A.F: an extremely variant histone H2A sequence expressed in the chicken embryo
Summary
Researchers identified a novel histone H2A variant (H2A.F) in chicken embryos. This variant protein is highly divergent and shows a restricted tissue distribution, suggesting specialized functions.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Histones are crucial for DNA packaging in chromatin.
- Histone variants can alter nucleosome function and gene regulation.
- Chicken embryonic RNA was used to explore histone gene diversity.
Purpose of the Study:
- To identify and characterize novel histone gene transcripts in chicken embryos.
- To investigate the sequence and potential function of variant histone H2A proteins.
Main Methods:
- Construction of a cDNA clone bank from chicken embryonic RNA.
- Selection of clones with poor hybridization to embryonic histone gene probes.
- DNA sequencing of selected cDNA clones to predict protein sequences.
Main Results:
- A highly variant H2A protein (H2A.F) was identified, 40% divergent from canonical H2A.
- The H2A.F gene is not highly conserved across species but may exist as a gene family in chickens.
- H2A.F mRNA is ~820 base pairs, polyadenylylated, and exhibits limited tissue distribution in embryos.
Conclusions:
- H2A.F represents a significantly divergent histone H2A variant in chicken embryos.
- The unique features of H2A.F (sequence, polyadenylation, tissue distribution) suggest specialized roles in embryonic development.
- Further research is needed to elucidate the precise function of H2A.F in chromatin structure and gene regulation.
Related Concept Videos
02:32Position-effect Variegation
In 1928, a German botanist Emil Heitz observed the moss nuclei with a DNA binding dye. He observed that while some chromatin regions decondense and spread out in the interphase nucleus, others do not. He termed them euchromatin and heterochromatin, respectively. He proposed that the heterochromatin regions reflect a functionally inactive state of the genome. It was later confirmed that heterochromatin is transcriptionally repressed, and euchromatin is transcriptionally active chromatin.
02:32Histone Modification
The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
Acetylation
The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
02:30Histone Variants at the Centromere
Histone variants are the histone proteins with structural and sequence variations. These variants may be regarded as “mutant” forms that replace their canonical histone counterparts in the nucleosomes. Specific post-translational modifications on the histone variants enable further chromatin complexity and regulate tissue-specific gene expression. The most common histone variants are from histone H2A, H2B, and linker histone H1 families. However, several variants of histone H3 variants are also...
01:01Euchromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions take up more dye, appearing darker, while the less-compact areas take up less dye and appear lighter. Based on the compaction level, chromatins are classified into two primary forms – euchromatin and heterochromatin.
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
Euchromatin is the less dense region of the chromatin and stains lighter. Euchromatin contains histone H3 extensively...
02:38Heterochromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
02:38Heterochromatin
The extent of chromatin compaction can be studied by staining chromatin using specific DNA binding dyes. Under the microscope, the dense-compacted regions that take up more dye are called heterochromatin. Heterochromatin is further classified into two forms – constitutive heterochromatin and facultative heterochromatin.
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at 9th...