Sunday, February 25, 2007


If you are a fruit fly

When animals are reared on a near-starvation diet, they live much longer than those that eat freely. Even the fruit fly Drosophila has this reaction to a low glucose diet, and lives considerably longer on a 5% than on a 15% sugar-yeast diet. This effect of dietary restriction is easily reversed when flies consume more food. Libert et al. report a less expected effect: Just the smell of the flies' food (yeast) can inhibit some of the effects of dietary restriction and shorten the flies' life span by 6 to 18%. Flies lacking an essential part of their odor receptors, which results in their having greatly impaired senses of smell, live longer than flies with intact odor sensation.

Journal abstract below:

Regulation of Drosophila Life Span by Olfaction and Food-Derived Odors

By Sergiy Libert et al.

Smell is an ancient sensory system present in organisms from bacteria to humans. In the nematode Caeonorhabditis elegans, gustatory and olfactory neurons regulate aging and longevity. Using the fruit fly, Drosophila melanogaster, we showed that exposure to nutrient-derived odorants can modulate life span and partially reverse the longevity-extending effects of dietary restriction. Furthermore, mutation of odorant receptor Or83b resulted in severe olfactory defects, altered adult metabolism, enhanced stress resistance, and extended life span. Our findings indicate that olfaction affects adult physiology and aging in Drosophila, possibly through the perceived availability of nutritional resources, and that olfactory regulation of life span is evolutionarily conserved.

Genome scan finds new genetic links to autism

I have often said that there is no such disorder as autism but rather several quite distinct disorders that have communication difficulty in common. The now commonly used phrase "autism spectrum disorders" recognizes that too. The common genes found below may therefore be the ones that affect communication difficulty in particular

The first results from a scan of the world's largest collection of DNA from families affected by autism point to two new genetic links that may predispose people to the brain disorder. The research journal Nature Genetics reported the findings in its Feb. 18 online edition. "This largescale study reveals that autism is an extremely diverse condition. [with] numerous genetic origins, rather than a single or few major causes," said Daniel Geschwind of the University of California, Los Angeles, site of one of the study's 13 research centers.

Autism is a complex disorder that strikes as early as 2 or 3 years of age. It disrupts a child's ability to communicate and develop social relationships. Scientists suspect the disease is highly hereditary. The U.S. Centers for Disease Control and Prevention reports that one in 150 American children is diagnosed with autism or one of its related conditions. Affecting four times as many boys as girls, autism diagnoses have multiplied tenfold in the last decade, for unclear reasons.

The consortium searched for genetic commonalities in autistic people from nearly 1,200 families. The scientists scanned the DNA for variations in gene copy numberstiny tracts of extra or deleted genes thought to be possibly tied to autism.

The large number of families "permitted us to organize autistic children with similar features of this disorder into smaller groups, where gene linkages may be more easily detected," said the university's Rita Cantor.

The results implicated a previously unidentified region of chromosome 11; and neurexin 1, a member of a gene family believed to play a key role in communication between brain cells.

The neurexin finding also highlighted a group of brain cells called glutamate neurons and the genes affecting their development and function, suggesting these are critically involved in autism and related disorders, researchers said.

Scientists cautioned that more studies with even more subjects will be needed to full explain heredity's role in autism. "We are optimistic" that this approach will lead to improved treatments, Geschwind said.

Families who participated had more than one member diagnosed with one of three genetically related diseases: autism, pervasive developmental disorder or Asperger's syndrome.



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.