Table of Contents
What is genome duplication?
A whole genome duplication is exactly what it sounds like: an event which creates an organism with additional copies of the entire genome of a species. Regular cells of most organisms that reproduce sexually contain two copies of their entire genome (one inherited from each parent), a state known at being diploid.
What causes genome duplication?
Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes.
How many pairs of chromosomes does a zebrafish have?
Despite this duplication, zebrafish has about the same number of chromosomes as humans (25 vs. 23 pairs), rather than twice as many, as would be expected in the absence of chromosome rearrangements.
What happens after gene duplication?
Abstract. Gene and genome duplications provide a source of genetic material for mutation, drift, and selection to act upon, making new evolutionary opportunities possible. As a result, many have argued that genome duplication is a dominant factor in the evolution of complexity and diversity.
Why are zebrafish closely related to humans?
Zebrafish have a similar genetic structure to humans. They share 70 per cent of genes with us. 84 per cent of genes known to be associated with human disease have a zebrafish counterpart. As a vertebrate, the zebrafish has the same major organs and tissues as humans.
How many chromosomes does zebrafish have?
25 chromosomes
But zebrafish, with 25 chromosomes, has just two more chromosomes in the haploid set than humans.
How does a zebrafish regenerate?
The zebrafish has a remarkable capability to regenerate the heart after ventricular injury or amputation, mainly by the ability of the remaining cardiomyocytes to de-differentiate, and proliferate to replace the lost cardiac tissue (35, 39).
Why can zebrafish regenerate cells on command?
Summary: Scientists have succeeded in determining the number and type of newly formed neurons in zebrafish; practically conducting a ‘census’ in their brains. Following an injury, zebrafish form new neurons and integrate them into the nervous system, which is the reason for their brain regeneration ability.
What is gene duplication evolution?
Evolution by gene duplication is an event by which a gene or part of a gene can have two identical copies that can not be distinguished from each other. This phenomenon is understood to be an important source of novelty in evolution, providing for an expanded repertoire of molecular activities.
How does gene duplication create new genes?
Each new gene must have arisen from an already existing gene.” Gene duplication occurs when errors in the DNA-replication process produce multiple instances of a gene. Over generations, the versions accrue mutations and diverge, so that they eventually encode different molecules, each with their own function.
What is unique about zebrafish?
As a vertebrate, the zebrafish has the same major organs and tissues as humans. Their muscle, blood, kidney and eyes share many features with human systems. Zebrafish have the unique ability to repair heart muscle. For example, if part of their heart is removed they can grow it back in a matter of weeks.
Can zebrafish gene maps be used to identify human genes?
This zebrafish gene map will facilitate molecular identification of mutated zebrafish genes, which can suggest functions for human genes known only by sequence. Research Support, U.S. Gov’t, P.H.S.
How many IGF genes are there in zebrafish?
Insulin-like growth factors (IGFs) are key regulators of development, growth, and longevity. In most vertebrate species including humans, there is one IGF-1 gene and one IGF-2 gene. Here we report the identification and functional characterization of 4 distinct IGF genes (termed as igf-1a, -1b, -2a, and -2b) in zebrafish.
Why do zebrafish have so many co-orthologs?
Moreover, zebrafish, like many teleost fish, are believed to have experienced an additional genome wide duplication event [14], [15]. As a result, they often have two co-orthologs in contrast to a single copy gene in humans and other mammals.
Did vertebrate ancestors have multiple copies of genes?
Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization. It has been suggested that one genome duplication event occurred before, and one after the divergence of ray-finned and lobe-finned fishes.