Related Experiment Video
Updated: Jun 25, 2026
10:06
High Resolution Whole Mount In Situ Hybridization within Zebrafish Embryos to Study Gene Expression and Function
Published on: October 19, 2013
22.1K
Gag proteins encoded by endogenous retroviruses are required for zebrafish development
Ni-Chen Chang1, Jonathan N Wells1, Andrew Y Wang1
1Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14850.
Summary
Recently active transposable elements (TEs) in zebrafish provide essential proteins for embryonic development. These active TEs, like BHIKHARI-1 Gag, are crucial for mesoderm and neural crest formation.
Area of Science:
- Genomics
- Developmental Biology
- Molecular Evolution
Background:
- Transposable elements (TEs) constitute a significant portion of eukaryotic genomes.
- The functional co-option of TEs into host genomes is often studied using ancient, inactive elements.
- Evidence for active TEs contributing beneficially to host organisms is limited.
Purpose of the Study:
- To investigate the role of recently active transposable elements in zebrafish embryonic development.
- To elucidate the mechanisms by which active TEs are integrated into essential biological functions.
Main Methods:
- Utilized knockdown and rescue experiments in zebrafish to assess the function of specific TEs.
- Examined the cellular localization and effects of ectopic expression of TE-derived proteins (Gag) in chicken embryos.
- Investigated the impact of BHIKHARI-2 Gag depletion on neural crest development.
Main Results:
- Demonstrated that the endogenous retrovirus BHIKHARI-1 (Bik-1) Gag protein is essential for mesoderm development in zebrafish.
- Showed that Bik-1 Gag associates with the cell membrane and influences cell migration when ectopically expressed.
- Revealed that depletion of BHIKHARI-2 Gag leads to neural crest development defects in zebrafish.
Conclusions:
- Active transposable elements encode proteins critical for embryonic development in zebrafish.
- Proposed an "addiction" model to explain the integration of active TEs into conserved developmental processes.
- Highlighted the functional significance of recently active TEs beyond their repetitive nature.
Related Concept Videos
01:25The Central Dogma
Overview
01:10Retrovirus Life Cycles
Retroviruses have a single-stranded RNA genome that undergoes a special form of replication. Once the retrovirus has entered the host cell, an enzyme called reverse transcriptase synthesizes double-stranded DNA from the retroviral RNA genome. This DNA copy of the genome is then integrated into the host’s genome inside the nucleus via an enzyme called integrase. Consequently, the retroviral genome is transcribed into RNA whenever the host’s genome is transcribed, allowing the retrovirus to...
03:06From DNA to Protein
The flow of genetic information in cells from DNA to mRNA to protein is described by the central dogma, which states that genes specify the sequence of mRNAs, which in turn specify the sequence of amino acids making up all proteins. The decoding of one molecule to another is performed by specific proteins and RNAs. Because the information stored in DNA is so central to cellular function, it makes intuitive sense that the cell would make mRNA copies of this information for protein synthesis...
02:28Leaky Scanning
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R stands for...
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
01:20The Central Dogma
The central dogma explains the flow of genetic information from DNA nucleotides to the amino acid sequence of proteins.
RNA is the Missing Link Between DNA and Proteins
In the early 1900s, scientists discovered that DNA stores all the information needed for cellular functions and that proteins perform most of these functions. However, the mechanisms of converting genetic information into functional proteins remained unknown for many years. Initially, it was believed that a single gene is...
RNA is the Missing Link Between DNA and Proteins
In the early 1900s, scientists discovered that DNA stores all the information needed for cellular functions and that proteins perform most of these functions. However, the mechanisms of converting genetic information into functional proteins remained unknown for many years. Initially, it was believed that a single gene is...