Bacterial Artificial Chromosomes (BAC) have been developed to hold much larger pieces of DNA than a plasmid can. BAC vectors were originally created from part of an unusual plasmid present in some bacteria called the F’ plasmid.
The F’ plasmid allows bacteria to have “sex” (well, sort of: F’ helps bacteria give its genome to another bacteria but this only happens rarely when bacteria are under a lot of stress). F’ had been studied extensively and it was found that it could hold up to a million basepairs of DNA from another bacteria. Also, F’ has origins of replication and bacteria have a way to control how F’ is copied.
Monday, May 26, 2008
Friday, May 16, 2008
Mitochondrial Eve
'Mitochondrial Eve' Research: Humanity Was Genetically Divided For 100,000 Years
A Picture of the Ancient Past
Finding:
Based on Anthroopological genetic research, researchers believe that about 60,000 years ago, modern humans started the journey to populate the world. However, relatively little is known about the demographic history of our species over the previous 140,000 years in Africa.
The current study focuses on Africa and refines the understanding of early modern Homo sapiens history. These early human populations were small and isolated from each other for many tens of thousands of years.
The research was based on a survey of African mitochondrial DNA (mtDNA) and is the most extensive survey of its kind. It included over 600 complete mtDNA genomes from indigenous populations across the continent.
How Old Was “Mitochondrial Eve”?
MtDNA, inherited down the maternal line, was used in 1987 to discover the age of the “Mitochondrial Eve,” the most recent common female ancestor of everyone alive today. This work has since been extended to show unequivocally that “Mitochondrial Eve” was an African woman who lived sometime during the past 200,000 years.
Recent data suggests that Eastern Africa went through a series of massive droughts between 90,000 and 135,000 years ago. It is possible that this climate shift contributed to the population splits. What is surprising is the length of time the populations were separate — for as much as half of our entire history as a species.
The study shows that tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA.
A Picture of the Ancient Past
Finding:
Based on Anthroopological genetic research, researchers believe that about 60,000 years ago, modern humans started the journey to populate the world. However, relatively little is known about the demographic history of our species over the previous 140,000 years in Africa.
The current study focuses on Africa and refines the understanding of early modern Homo sapiens history. These early human populations were small and isolated from each other for many tens of thousands of years.
The research was based on a survey of African mitochondrial DNA (mtDNA) and is the most extensive survey of its kind. It included over 600 complete mtDNA genomes from indigenous populations across the continent.
How Old Was “Mitochondrial Eve”?
MtDNA, inherited down the maternal line, was used in 1987 to discover the age of the “Mitochondrial Eve,” the most recent common female ancestor of everyone alive today. This work has since been extended to show unequivocally that “Mitochondrial Eve” was an African woman who lived sometime during the past 200,000 years.
Recent data suggests that Eastern Africa went through a series of massive droughts between 90,000 and 135,000 years ago. It is possible that this climate shift contributed to the population splits. What is surprising is the length of time the populations were separate — for as much as half of our entire history as a species.
The study shows that tiny bands of early humans, forced apart by harsh environmental conditions, coming back from the brink to reunite and populate the world. Truly an epic drama, written in our DNA.
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