The dance of the chromosomes

April 2011

Time-lapse photographs taken of a single point on a chromosome inside the nucleus in a living cell, demonstrated very graphically why GM is an inherently disruptive technology.

The marked spot, which could represent any gene, was seen to be in constant rapid motion, travelling between the periphery and the centre of the nucleus four times within a 60 second period.

When the normal business of the cell is in progress, an “elegant choreography” is performed by the mingling chromosomes, putting each gene in an ever-changing location in the nucleus and in an ever-changing position in relation to every other gene.

The biotech industry, with its blinkers firmly in place, has never looked beyond the molecular sequence of the DNA which forms a gene, and the single protein which can be generated by an artificial gene. The 98% non-gene DNA is dismissed as 'junk', and the protein structure to which the DNA is bound is dismissed as mere 'scaffolding'.

Science outside industry is uncovering a very different picture.

The nature of the carrier protein is subject to change and mutation, profoundly altering the expression of the genes it carries. For example, the protein 'scaffold' determines the all-important folding of the DNA attached to it: this affects the structure and timing of the protein expressed. It is the protein matrix which transports the DNA to precise locations within the nucleus: one position will express the gene while another represses it, another will allow any damage to be repaired, and another will degrade and recycle DNA matter damaged beyond repair. The ability to move quickly and precisely is clearly vital, not only for correct coherent expression of genes, but for the very health of every cell and the whole organism.

The scientists who carried out this ground-breaking research described the centre zone of the working nucleus as a “riot of movement” in which the seemingly amorphous nucleus has compartmentalised zones, and location is everything.

What will happen to this elegant choreography when a GM-laden bullet rips through it leaving its DNA debris behind? Or, when a cunningly redesigned pathogen forces its way in to insert its man-made burden?

In a constantly shifting and totally interconnected system, random attacks can only disrupt the whole functioning and create vulnerability to disease.

Acknowledging this inherent weakness in the genetic transformation process, the latest thrust of GM research is to insert, not single genes or groups of genes, but an entire man-made mini-chromosomes which will sit outside the nucleus. The genes packed into these chromosomes are naked of all controlling segments which might interfere with their artificial function.

Mini-chromosomes are being promoted as a way to avoid the nuclear disruption of genetic transformation, and to by-pass the self-regulating capacity of healthy cells which usually expels or silences foreign DNA. It will certainly allow much more complex sets of genes to be inserted. Since pollen generally transmits only the nuclear material from the parent, mini-chromosomes are touted as a way to avoid the biotech bugbear of gene pollution.

Unfortunately, mini-chromosomes bring as many new problems as they (may) solve.

There are assumptions being made about mini-chromosomes which might well prove as simplistic as the old genetic transformation process:

• How likely is it that nuclear function will be disrupted by the presence of a foreign body in the surrounding cell with which it's intimately connected?
• How likely is it that the cells and whole organism harbouring a large foreign body, will be healthy?
• How often will the the artificial cell bodies make their way into pollen and out into the wider environment?

Artificial chromosomes share important characteristics with bacterial DNA, and it is to be expected that bacteria will be able to incorporate some or all of their genes and be able to transfer them to other bacteria and beyond. Since the main reason for mini-chromosome development is in the manufacture of pharmaceuticals and industrial chemicals, horizontal gene transfer can be predicted to have serious long-term consequences.

The by-passing of the nuclear communication and repair system is downright dangerous. No-one can predict how unregulated DNA will evolve to produce who knows what toxins. The problem is, mini-chromosomes can't dance.

(This article is adapted from an article which appeared on GM-free Scotland in September 2009. View an archived copy of that article here.)

Sources

• Susan M. Gasser, Tracking the dance of DNA and structural proteins within the nucleus shows that placement makes the difference between gene activity & silence, The scientist, July 2009
• The new weapons of genetic engineering, GRAIN, 17.03.09, www.grain.org.seedling;?id=576