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

~ Betty ~ Leave a comment

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 →

How whales lost their sense of smell and taste

~ Betty ~ 4 Comments

humpback-whale-436115_1280

Whales are very likeable creatures. They are highly intelligent, sentient and social. But without a doubt, they would make terrible chefs and untrustworthy food critics. It seems that somewhere along the evolutionary path, whales lost their sense of smell and much of their sense of taste.

Baleen whales are some of the largest animals in the world and spend most of their time below the water surface, making them difficult to find and even more difficult to study. The group of Japanese researchers at Kyoto University worked around these challenges by using genome sequencing and fossil records to study the evolution of smell and taste in toothed and baleen whales. The researchers isolated DNA from minke whale meat purchased at a fish market and sequenced it to assemble the entire genome of the minke whale. For comparison, they also used the previously sequenced genomes of the bottlenose dolphin, a toothed whale, and cow, which, along with pigs and hippos, belongs to the same clade as cetaceans.

In mammals, odours in the air are detected by different receptors in our nasal cavity. When they compared the whale genomes to the cow genome, the researchers found that both whale genomes had lost a large number of genes required for odour detection. The most notable of these is the family of genes known as olfactory receptors (OR). The cow genome contained over 900 functional OR genes while the minke whale and dolphin genomes contained just 70 and 12, respectively. Mice, with their keen sense of smell, have over 1000 OR genes. Continue reading →

The lesser of two evils: e-cigarette exposure weakens anti-bacterial and anti-viral defenses

~ Betty ~ Leave a comment

During cold and flu season, many of us try to boost our immune system to resist getting sick. But if you smoke, you are at a greater risk of acquiring an infection and becoming ill. Both cigarette smoke and nicotine are known to suppress the body’s immune system, which contribute to smokers being more susceptible to bacterial and viral infections. Patients with chronic obstructive pulmonary disease caused by smoking are especially prone to lung infections.

Electronic cigarettes, or e-cigarettes, are widely believed to be a healthier alternative to traditional cigarettes. While they undoubtedly cause less harm than traditional cigarettes, e-cigarettes are still hazardous to your health. A team of researchers led by Prof. Shyam Biswal at Johns Hopkins University has shown that exposure to e-cigarettes impairs your body’s ability to fight off bacterial and viral infections.

To study the effects of e-cigarette vapor on immune responses, the researchers developed the first mouse model for e-cigarette exposure. They used a modified cigarette smoke machine that regularly puffed e-cigarette vapor into a small chamber. Mice were exposed to e-cigarette vapor in the chamber for one and a half hours twice per day for two weeks. Continue reading →