There are over 40 known diseases that are passed only from mother to child, some of them severe and debilitating. These diseases come from the mitochondrial DNA (mtDNA) of the mother, but the proportion of DNA that is passed to the children are so varied that scientists have no means of predicting the severity and presenting symptoms of the disease in the offsprings.

That is, until recently when scientists located a genetic bottleneck in the mitochondria of the mother’s developing eggs that determines the proportion of mutated mtDNA that mothers transmit to their child. Understanding this bottleneck event, and really predicting its outcome in the child, is so important in the treatment and genetic counseling of diseases that are maternally inherited.

The study appears in the December issue of the Nature Genetics journal.

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The land of pineapples, bananas and sugarcane, Hawaii seems like an unlikely place to grow corn. But in the last 10 years or so, the Aloha state has been home to genetically modified crops - potatoes, soybeans, wheat, beets, rice, safflower and other food traditionally grown in the mainlands.

Scientific American takes another jab at the pros and cons debate on Genetically modified food, in the background of a economically thriving but ecologically isolated Hawaii. Of interest is a report that genetic drift has been found in non-GM papaya seeds that test positive for GM material. The safety of genetically modified food is always a top debate topic. But in the case of Hawaiians, rejection of GM food, in particular taro root crop, has as more to do with its legendary origins and ties with the Hawaiian culture.

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  A highly cited Nature paper that identified a long-sought receptor critical for mediating plant response to stress is being retracted after researchers were unable to reproduce the results. (The Scientist)

The paper in question was the first to identify a receptor for abscicic acid (ABA), which regulates plant stress response. It has been cited some 120 times since its publication in 2006. Scientific experiments are not exact nor always produce results that are set in stone. Even the cleanest and best experiments will find changes in the future as methods and technology improve. But that’s the nature of science. We discover something new and report it, and other scientists test our methods and results. Now I suppose citing the retracted Nature paper is not a real problem unless future studies relied on the assumption that this one paper was correct. Unfortunately, that’s exactly what the problem was.

"It obviously put a big dent in what we’re doing," said corresponding author Robert Hill. "It’s meant that we’ve had to go back and reinterpret data." One graduate student has had to "chop a publication" which was based on the assumption that the ABA receptor was real. "I’ve come to reconcile with the problem," said Hill, adding that he is working to correct it "without hurting too many people."

image: sxc

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A new genetic syndrome was discovered in a group of families in Quebec with a common ancestor. The syndrome was named MEDNIK to describe the resulting phenotypes - mental retardation, enteropathy, deafness, peripheral neuropathy, ichthyosis, and keratodermia.

The scientists found a new splice mutation in the AP1S1 gene, which encodes a subunit of a complex (AP) responsible for selecting which proteins move within the cell. A zebrafish knockdown model was used to study the loss of the gene’s function further. Injecting the affected larvae with a human normal AP1S1 mRNA restored some phenotypes.

The study is published in PLOS Genetics.

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