Issue 73  July 20th 2018

How a bacteria-detecting strip of plastic film could make best-before dates irrelevant

It's impossible to tell if meat is contaminated with potentially deadly E. coli bacteria by simply smelling or looking at it, but one day a glance at the plastic packaging could let consumers know if it's safe to eat.

That's the hope of a team of researchers at McMaster University in Hamilton, Ont. They've developed a thin, plastic patch they call Sentinel Wrap that changes colour under ultraviolet light when it comes into contact with meat contaminated with E. coli, a food-borne bacteria that can cause extreme illness or death.

Team member Carlos Filipe, chair of McMaster's chemical engineering department, hopes that shoppers will one day be able to point their smartphone cameras at packaged fresh food and check for contamination by using an app. "The goal is to allow people to ultimately look at the packaged food and be able to tell if there is food contamination, like E. coli, in that food, without having to open the package," says Filipe.

The researchers published their findings in April in the scientific journal ACS Nano, but they still have obstacles to overcome before they can test the patch in the real world. It would first need approval from food regulators, then the researchers would have to bring down the cost of mass production.

"We are hoping that in two years' time, with the industry partners that we are currently talking to, we can at least start some pilot studies on these so that we can have some selected food in grocery stores that we can follow and see what happens," says Tohid Didar, an assistant professor in McMaster's chemical and mechanical engineering department. "That's the goal."

In a Rare Genetic Syndrome, a 11-Year-Old Girl Got Most of Her Genes from Father & Almost None from Mother

In a rare case, an 11-year-old girl from the Czech Republic was born with genes that came almost entirely from her father, instead of half from each parent. Only about 25 people in the world – all girls – have been reported with this genetic syndrome and the Czech girl appears to be the first to have inherited it without developing cancer.

Clinical geneticist Jennifer Kalish of the Children’s Hospital of Philadelphia, who was not involved in the new case, told BuzzFeed News, “Ten to fifteen years ago, we didn’t think this condition was compatible for life. It doesn’t happen every day.” Kalish heads a lab investigating ways to help children with imprinted gene disorders, conditions in which at least one gene is doubled up from mom or dad. Although rare, more of these cases are turning up due to improved genetic testing worldwide.

Researchers found the Czech case because the girl’s parents were trying to understand why she was deaf, as reported in April in the Journal of Human Genetics. At nine years of age, a genetic test revealed that she had two identical copies of a rare gene twice, once from each parent. The rare gene was surprisingly not in her mother, wrote the scientific team, led by Irena Borgulova of the Centre for Medical Genetics and Reproductive Medicine Gennet in Prague. It meant she had inherited two copies of her father’s gene. Subsequently testing showed that it wasn’t just that one gene – she had doubled up on her father’s genes in almost all her chromosomes in most of her cells. Only about 7% of her blood cells, for example, showed any maternal genes and 74% of the cells in her saliva held only paternal genes.

How does this happen? In the girl’s case, instead of the DNA from her father’s sperm and mother’s egg pairing up this way, two copies of the father’s genes zipped together to create a dad-dad set of 23 chromosomes, the full human genome. When the zygote split to create more cells, most ended up with the dad-dad genome.