Exploring the 'last frontier' of our genome

Sep 23, 2011 By Viviane Callier
In this image of a human cell, the centromeres are the pink spots and the blue "sticks" are chromosomes. Credit: Karen Hayden, Duke

The human genome first appeared in print in 2001. But scientists aren’t done yet. There’s part of our DNA that geneticists have yet to assemble a sequence for: the centromeres.

Centromeres are necessary for chromosomes to segregate during cell division so that each new cell receives a complete copy of the . If chromosome segregation does not occur correctly, the resulting cells could die or become cancerous.

The sequence of centromeres remains one of the mysterious regions in the human genome because these areas are made of highly repetitive DNA sequences called satellite DNAs, said Karen Hayden, a recent graduate of Hunt Willard’s lab in Duke’s IGSP.

Centromere sequences are currently represented as gaps or spaceholders in the genome. Hayden, however, has developed a new strategy to study these elusive arrangements of DNA.

To study genomic material, scientists first break it into small pieces and sequence them. Then, much like a puzzle, they reassemble the pieces into the full sequence.

But when highly repetitive DNA, such as is found in centromeres, is broken into pieces, the parts of the puzzle look strikingly similar. As a result, scientists have trouble knowing if they have truly reassembled the pieces into the original sequence.

Using computational methods and studying the centromere sequences in the lab, however, Hayden was able to solve the puzzle and determine sequence arrangement in human centromeres. She also created a database to analyze the variations in among centromere sequences in the .

Hayden said she hopes that the experiments she designed, along with the database of sequences, will provide the tools to study whether certain centromere sequences are more highly associated with diseases, such as cancer and birth defects.

This fall she will go to the Segal Lab at the Weizmann Institute in Israel to model the physical properties of centromeric sequences and study if centromeric play a role in the centromere function. She then plans to continue her work in David Haussler’s lab at UC Santa Cruz.

Explore further: First detailed microscopy evidence of bacteria at the lower size limit of life

add to favorites email to friend print save as pdf

Related Stories

Centromeres cross over, a lot

Jun 12, 2008

Recombination at centromeres is higher than anywhere else on the chromosome, even though methyltransferases do their best to prevent it, say Jaco et al., as published in the June 16 issue of the Journal of Cell Biology.

Genome sequence for the domestic horse unveiled

Nov 05, 2009

The whole genome sequence of the domestic horse has been completed by the genome-sequencing center of The Broad Institute of MIT and Harvard, in collaboration with an international team of researchers that ...

Degrading proteins to divide cells

Aug 26, 2011

A group of scientists led by the IRB Barcelona, Spain, researcher Ferran Azora­n has identified the main instrument that Drosophila cells use to define the identity and function of the centromere in the Drosophila. A ...

Human chromosome 3 is sequenced

Apr 27, 2006

The sequencing of human chromosome 3 at Baylor College represents the final stage of a multi-year project to sequence the human genome.

Recommended for you

Malaria transmission linked to mosquitoes' sexual biology

Feb 26, 2015

Sexual biology may be the key to uncovering why Anopheles mosquitoes are unique in their ability to transmit malaria to humans, according to researchers at Harvard T. H. Chan School of Public Health and University of Per ...

Intermediary neuron acts as synaptic cloaking device

Feb 26, 2015

Neuroscientists believe that the connectome, a map of each and every connection between the millions of neurons in the brain, will provide a blueprint that will allow them to link brain anatomy to brain function. ...

Skeleton of cells controls cell multiplication

Feb 26, 2015

A research team from Instituto Gulbenkian de Ciencia (IGC; Portugal), led by Florence Janody, in collaboration with Nicolas Tapon from London Research Institute (LRI; UK), discovered that the cell's skeleton ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.