Rethinking Salmonella: from food poisoning culprit to cancer-fighting agent

What would you look for in an ideal cancer treatment? You’d probably want something that would only kill cancer cells and leave healthy cells unharmed. It would also be nice if this drug could penetrate deep inside tumours, even if the tumours are dispersed across multiple sites in the body.

What if that anti-cancer treatment was a dose of Salmonella? Would you try it?

Scientists are developing ways to transform bacteria like Salmonella into lean, mean tumour-fighting machines. A new study published this week in Proceedings of the National Academy of Sciences describes a new and innovative way to turn Salmonella into highly specific vehicles that can deliver anti-cancer compounds into the heart of a tumour. Continue reading

Wounded by love: snails struck by love darts have lower survival and reproductive rates

"Shot through the heart and you're to blame, you give love a bad name" In this image of two mating snails, the snail on top shot a love dart through the head of its mating partner. (Credit: Chase and Blanchard, Proc. R. Soc. B (2006) 273, 1471–1475)
“Shot through the heart and you’re to blame, you give love a bad name” In this image of two mating snails, the snail on top shot a love dart through the head of its mating partner. (Credit: Chase and Blanchard, Proc. R. Soc. B 2006, 273:1471)

In classical mythology, Cupid carries two types of arrows: one with a sharp golden tip and one with a blunt tip made of lead. Those struck with the golden arrow are filled with uncontrollable desire while those wounded with the lead arrow are filled with revulsion. In these modern times, we humans are less likely to rely on a winged cherub carrying a quiver full of arrows to help us find love than on online dating sites and Tinder. That’s not to say that projectile weapon systems like the bow and arrow have become obsolete in affairs of the heart. Some species of land snails shoot love darts at their mating partners to increase their reproductive success.

As violent as it sounds, stabbing their mating partner with a love dart improves the likelihood that a snail will father offspring.  These sharp and pointy darts are made of a crystalline form of calcium carbonate called aragonite and coated with mucus. If the dart hits its target, chemicals in the mucus coating are released into the recipient snail’s blood stream. These chemicals serve as signals that trick the female reproductive organs to divert the shooter’s sperm away from the sperm digesting organs and into the sperm storage organs where they can fertilize eggs later. While love darts are known to carry clear benefits for the shooter, not a lot is known about how being hit by a love dart affects the recipient. For the first time, scientists have experimentally studied the costs of this violent and traumatic behaviour to the individual being stabbed. Continue reading

Protecting crops by blocking insect genes: the case for RNA interference

From the potato farms of Prince Edward Island to the cornfields of Iowa, there is a never-ending struggle between farmers and insects. Farmers apply chemical pesticides to protect their crops, which drive the evolution of more insecticide-resistant pests. This, in turn, forces farmers to use insecticides more frequently and at higher doses, which then selects for even more resistant insects. And so on and so on.

In an effort to gain the upper hand, researchers are turning to transgenic plants as a way to increase crop yield while reducing pesticide use. For example, some species of corn, cotton, and potato plants have been engineered to produce a bacterial toxin called Bt that is lethal to insects. Insects that eat leaves from Bt-producing plants ingest the toxin and are killed. But Bt isn’t effective against all agricultural pests and resistance has already been documented in some insects.

Left uncontrolled, potato beetles can completely destroy crops.
Left uncontrolled, potato beetles can completely destroy crops.

A promising area of transgenic plant research is focused on the use of RNA interference, or RNAi, to control insect pests. For any gene to be expressed, the DNA must first be read and converted into RNA. The RNA message is then decoded to produce a protein. Think of your cell as a house and the DNA as the master building plan for that house. Every time you need to make a repair, the general contractor consults the building plan and sends a message to the tradesperson to make the component that is needed. The RNA is the message that your cell uses to produce the parts needed to keep everything running smoothly. In RNAi, the RNA message is intercepted and the proper parts are not made. When the RNA message is for an essential cellular component, blocking the message can lead to cell death and if enough cells are affected, the death of the entire organism. Continue reading