Outside influence: Genes outside nucleus have disproportionate effect

Oct 11, 2013
Studies on Arabidopsis plants like this six-week-old lab-grown specimen show that the genes of mitochondria and chloroplasts have a disproportionate effect on cellular metabolism compared to the far more numerous nuclear genes. Credit: Baohua Li, UC Davis

New research from the University of California, Davis, shows that the tiny proportion of a cell's DNA that is located outside the cell nucleus has a disproportionately large effect on a cell's metabolism. The work, with the model plant Arabidopsis, may have implications for future treatments for inherited diseases in humans.

Plant and animal carry most of their on chromosomes in the , separated from the rest of the cell. However, they also contain a small number of genes in organelles that lie outside the nucleus. These are the mitochondria, which generate energy for animal and plant cells, and chloroplasts, which carry out photosynthesis in plant cells.

The influence of genes outside the nucleus was known to an earlier generation of field ecologists and crop breeders, said Dan Kliebenstein, professor in the UC Davis Department of Plant Sciences and Genome Center and senior author on the paper published Oct. 8 in the online journal eLife. This is the first time that the effect has been quantified with a genomic approach, he said.

Bindu Joseph, a postdoctoral researcher in Kliebenstein's lab, and Kliebenstein studied how variation in 25,000 nuclear genes and 200 organellar genes affected the levels of thousands of individual chemicals, or metabolites, in leaf tissue from 316 individual Arabidopsis plants.

They found that 80 percent of the metabolites measured were directly affected by variation in the organellar genes—about the same proportion that were affected by variation among the much larger number of nuclear genes. There were also indirect effects, where organellar genes regulated the activity of that in turn affected metabolism.

"At first it's surprising, but at another level you almost expect it," Kliebenstein said. "These organelles produce energy and sugar for cells, so they are very important."

Similar effects could also occur in mammalian cells, Kliebenstein said. That has implications for in vitro fertilization therapies aimed at preventing diseases caused by faulty mitochondria being passed from mother to child. The British government recently proposed draft regulations for "three-parent embryos," created by taking a the nucleus from a fertilized egg and putting it into an egg cell from a third donor with its own set of . The technique has so far only been tested in animals.

"From what we can see in plants, there might be an issue, but it needs testing," Kliebenstein said.

Large population surveys that aim to link conditions such as obesity to specific genes should also take more account of organellar genes, he said.

Explore further: Synthetic biology on ordinary paper, results off the page

More information: dx.doi.org/10.7554/eLife.00776

Related Stories

Cell powerhouses shape risk of heart disease

Sep 29, 2013

(Phys.org) —Genes in mitochondria, the "powerhouses" that turn sugar into energy in human cells, shape each person's risk for heart disease and diabetes, according to a study published recently by researchers ...

Cell nuclei harbor factories that transcribe genes

Sep 27, 2013

Our genetic heritage is contained—and protected—in the nucleus of the cells that compose us. Copies of the DNA exit the nucleus to be read and translated into proteins in the cell cytoplasm. The transit between the nucleus ...

Moving genes have scientists seeing spots

Sep 09, 2013

An international team of scientists led by the UK's John Innes Centre and including scientists from Australia, Portugal, China and Italy has perfected a way of watching genes move within a living plant cell.

Possible culprits in congenital heart defects identified

Oct 03, 2013

Mitochondria are the power plants of cells, manufacturing chemical fuel so a cell can perform its many tasks. These cellular power plants also are well known for their role in ridding the body of old or damaged cells.

Recommended for you

Team advances genome editing technique

Oct 21, 2014

Customized genome editing – the ability to edit desired DNA sequences to add, delete, activate or suppress specific genes – has major potential for application in medicine, biotechnology, food and agriculture.

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

VendicarE
1 / 5 (1) Oct 12, 2013
Impossible. My conservative Political ideology demands that all genes be inside the nucleus.

As God Fearing Americans who cherish our traditional values and pure racial heritage we must resist these Commie scientists and their genes out of the nucleus nonsense.

Defund them NOW! They are just in it for the money.

This Junk Science is just welfare for the rich scientific elites.
nanotech_republika_pl
not rated yet Oct 12, 2013
This work may have implication on MitoSENS, http://en.wikiped...nescence
which proposes, in humans, to copy "the DNA for mitochondria completely within the cellular nucleus, where it is better protected."