RNAi doesn't just disappear

October 2019

After ten years of development, the US Environmental Protection Agency (EPA) quietly approved the first 'SmartStax Pro' GM maize with an RNA interference gene to kill a major corn pest, western corn root worm [1].

The artificial RNA produced by this technique, 'RNAi', is designed to match precisely the active RNA produced by a vital gene specific to the pest. By high-jacking the pest's own mechanism for silencing that gene, RNAi destroys the expression of the gene and the pest dies.

*Note. RNAi crop sprays are also in use, but are less effective at killing pests than the GM plant version which the pests consume.
A few months after the EPA ushered in this first GM maize with RNAi, a study was published which raised doubts about the claimed specificity of such insecticides. Using the honey bee as a model, the scientists "identified 101 insecticidal RNAs sharing high sequence similarity with genes in honey bees (indicating a huge scope for off-target gene silencing). "Of concern is that gene groups active during vital honey bee embryo formation and development had a disproportionately high sequence similiarity with all these RNAi pesticides: the scope for defective bees seems very real" [2].

RNAi fantasy

February 2018

Some 40% of pollinator species, including butterflies and bees, are facing extinction.

Climate change is, of course, taking its toll as wild animals find their life-cycles out of step with the plants they depend on. More has been made, however, of the toll exacted by neonicotinoid insecticides ('neonics').

Now, the largest ever field study of the effects of neonics on bees has, indeed, confirmed the negative impact. It also revealed the extent of contamination of wild plants. This was backed up by second study published the same day which reported that wildflowers are the bees' main source of exposure to the insecticides.

Errors in CRISPR

November 2017

We don't eat people or mice, but there's a lot to be learned from GM versions of both.

GM people aren't yet a reality, but soon could be. The first clinical trial of a GM technique to correct a faulty gene is already underway in China and another is due to start next year in America.

GM humans have become a realistic goal since the invention of the 'CRISPR/Cas9' system for making precise changes in any genome [1].

CRISPR/Cas9 has been used successfully to restore the sight of blind laboratory mice by correcting a faulty gene. The researchers didn't notice anything wrong with their GM animals. However, the technique is to be applied to humans, and there's an awareness that "every new therapy has some potential side-effects". They therefore decided to check out the possibility of "secondary mutations in (DNA) regions not targeted" by the CRISPR's RNA-homing device which seeks out the DNA sequence destined to be changed.

Convenient GM 'Arctic' apples

July 2017

Consumers in the US Midwest may now be finding a new convenience product in their grocery stores: convenient 10oz packs of conveniently sliced apples which conveniently don't turn brown and are a convenient snack.

The apples carry an inconvenient label consisting of a humanly indecipherable barcode which consumers will inconveniently have to scan with their smartphone to find out what in God's name they're buying.

Synbio bugs

March 2016

Back in 2010, the first 'creation' of a 'synthetic' organism was announced [1].

The 'synthetic organism' was mycoplasma, the smallest known cell, many times smaller than a bacterium.  Like all such microbes, mycoplasma don't have a defined cell nucleus like higher organisms, but have a single DNA-bearing structure ('chromosome').

What was actually synthesised was replica DNA of a sample mycoplasma.  This had been manufactured in computer-designed chunks, then assembled into a chromosome in yeast cells and inserted into a mycoplasma cell whose chromosome had been extracted.  The synbio-bug grew much as usual.

Bt crops - a dead-end street?

November 2015

There's no escaping the fact that farming creates pests.  Nature's monocultures, such as the carpet of bluebells in the woods, choose a time and a place where they don't coincide with anything that might eat them, and can make themselves quite impalatable to passing diners.  Cultivated plants aren't so lucky: they have to grow where and when a human being dictates, and becoming a bugs' banquet is an occupational hazard they're not properly equipped to deal with. 

In the mid-1900s, synthetic pesticides revolutionised agriculture and crop fields got bigger and bigger.  Farmers' joy was short-lived: pests with resistance to the chemicals weren't long in arriving.  By the 1980s, completely susceptible pests had become uncommon, and new pesticides were thin on the ground. 

Then came another revolution in pest control: pesticidal plants which infused themselves from fruit to root with 'Bt' toxin to kill the pests stone dead. 

Natural GM

July 2014

 

Leaf detail. CC photo by Lylir Horton on Flickr

At the same time as genetic engineers have been having fun building chains of nucleic acid (NA) molecules into artificial DNA sequences and using them to infect cells, scientists have been piecing together the story of natural genetic engineering.

Living cells have to adapt very quickly to changes in their environment. If they didn't, there wouldn't be much life on earth. Waiting for an appropriate Darwinian 'random genetic mutation' to crop up would be too slow. Since cells are intelligent enough to correct, as a matter of routine, between 99.9% and 99.99% of DNA errors, and if all else fails have the wisdom to self-destruct instead of reproducing the mistake, random genetic mutations are too rare to rely on for something as important as survival. 

RNAi in GM food crops - risks supressed

June 2014

Photo from Creative Commons

In something of a re-run of the orchestrated defamation of Arpad Pusztai in Scotland in 1998, a respected American professor with 30 years experience to her credit has found herself unable to get funding for her latest biotech-unfriendly research, nor get it published.

She also found Monsanto breathing down her neck in a very unpleasant way.

How to create unhealthy apples

March 2014

Image Creative Commons

Ever thought of the humble apple as a staple health-food?  Not in the USA it seems. 

Exports of American apples (and pears) to Europe have dropped 73% over the last five years.  The culprit lies in the high levels of two pesticides added to wax coatings to prevent 'scald'.

 

'Scald' is a post-harvest storage disorder of apples resulting in discoloured patches on the fruits' skin due to damage and death within the surface layer of cells. The cause seems to be long-term storage, especially under unsuitably humid conditions. Similar-looking post-harvest blemishes may arise due to pesticide treatments, sun, or friction damage in the case of very ripe fruit.

Now, there's another problem looming on the other side of the Atlantic.  Two varieties of GM 'Arctic' apples which don't turn brown when damaged looks set to be approved by the USDA. 

Silencing genes is all the rage

February 2014

Field of corn. By Hugho226 (Own work) [CC0], via Wikimedia Commons

Monsanto's latest venture into the brave now world of GM should give you pause for thought.  Or, several pauses. 

Having finally admitted that its 'Bt' insecticidal crops, designed to kill 'western corn rootworm' have reached the end of their shelf-life due to evolving resistance, Monsanto has found another GM way to kill this major pest. 

The Company has applied for regulatory approval for a new GM corn which produces a gene-altering agent, referred to generically as 'iRNA'.  Insecticidal iRNA is designed to kill insects by shutting down one of their vital genes. 

Scientists have already voiced concerns about this technology because it is based on the assumption that the target genetic sequence to be silenced is unique to the pest , and that reactions to iRNA in food aren't possible.  Neither of these assumptions is scientifically valid [1,2].  This makes putting copious artificial iRNA into the field and food chain the most health-threatening GM adventure yet.