Issue 79 / January - February 2011
Your sleep shapes your hair
1- Your sleep shapes your hair
Original Article: Akashi M. et al., PNAS 107, 15643 (2010).
Feeling sleepy during the day after a long flight? Internal body clock genes are to blame. Circadian (Latin: âaroundâ âthe dayâ) rhythm genes take part in a time dependent cycling of an organism to carry out daily physiological processes. These signals include very basic needs such as feeling sleepy at nighttime and waking up during the day and repeats about every 24 hours. Malfunctioning circadian rhythm genes are implicated in several sleep disorders. According to a recent study done by Makoto Akashi and his colleagues at Yamaguchi University in Japan, hair follicle cells were found to closely follow the gene expression pattern of the internal circadian rhythm of the human body. Gene expression patterns can be extracted from hair follicles from pulled hair. Studying the circadian rhythm genes and expression profiles has been quite an inconvenience for researchers up until now. This study provides a new alternative method for tapping into this machinery. Donât be surprised if you are asked for a couple of hairs pulled from your scalp if you go to a doctor complaining about your sleep disorder in the future. This method could have implications in the field of diagnostic medicine as a less invasive method for diagnosing problems since it allows us to conveniently gain access to the gene expression profiles of a person. We are not at a stage where we can control our sleep cycle at our convenience, but this is a step towards facilitating our understanding of this mechanism.
2- Western diet disturbs our bacterial guests
Original Article: De Filippo C. et al., PNAS 107, 14691 (2010).
Did you know that there are 100 trillions of microbes living happily ever after in your gut? This is about 10 times as many cells as make up the whole human body. But, no need to panic, because the sole purpose of their presence is to serve us by aiding in our daily digestion, metabolism and improving our immune system overall. A recent study shows that our friendly inhabitants are drastically affected by the human diet. A research group at Meyer Children Hospital in Italy analyzed and compared the fecal microbiota of children from Europe to that of children from rural African village of Burkino Faso (BF). When they examined the diets of each group closely, they saw that the BF diet is rich in cereals, vegetables and legumes, whereas the European diet is usually rich in animal protein, sugar, starch, and fat. Thus, children from Africa typically have a high-fiber diet and the children from Europe have a low-fiber diet. Next, researchers characterized the gut microbiotas of each group from fecal samples. The results revealed that gut microbiota was drastically different between these groups. Interestingly, BF children had several types of bacteria that seem to produce substantial amounts of short chain fatty acids (SCFAs) as a result of fiber-rich diet. The high levels of SCFAs are known to result in high energy levels and an increased anti-inflammatory capacity. The fact that African populations have almost no non-infectious colonic diseases may be attributed to the enriched diversity of gut microbiota due to the high-fiber diet of African children. This study once again emphasizes the importance of a fiber rich diet and it becomes clear that the adoption of such a diet and refraining from fast food culture would be beneficial to all of us.
3- Eat more, enjoy less
Original Article: Stice E. et al., The Journal of Neuroscience 30, 13105 (2010).
Why do obese people tend to overeat? A new study suggests a vicious cycle stemming from an obese individualâs desire to compensate for reduced pleasure from food. Degree of pleasure derived from eating correlates with the amount of released dopamine, which is associated with food intake. The researchers studied 26 overweight and obese volunteers, who were subjected to fMRI brain scans to identify brain regions that became active as they sipped both sugary milkshakes and a flavorless liquid. Every participant was tested twice over a six month period. Participants who gained weight showed significantly less activation in response to the milkshake intake upon a six-month follow-up relative to their baseline scan and relative to participants who did not gain weight. According to these results intake of palatable food results in down regulation of D2 receptors, reduced D2 sensitivity, and decreased reward sensitivity, implying that overeating may contribute to reduced striatal responsivity. These results will likely be important in developing programs to prevent and treat obesity, and also help us understand why obesity typically shows a chronic course and is resistant to treatment. Here is another reason to eat less: to get more pleasure from the food we eat.
4- Tough Malagasy spiders
Original Article: Agnarsson I. et al., PLoS one 5, e11234 (2010).
There are 40,000 kinds of spiders. They have little bodies, but the webs that they knit with their long thin legs using the silk from their tiny bodies are examples of great talent. Among the 200,000 types of silk which spiders produce, each have different combinations of properties, such as stickiness, durability or thickness, etc. A recently discovered spider found in Madagascar has an even more amazing talent. This kind of spider with its 3â5 cm long body size can make a web that can cross a river 2.5 meters wide with the ends of the nets attached to trees on either bank of a riverside. These nets have been found to be the strongest biological material ever known. After careful measurement, it was discovered that these webs are 10 times stronger (350 MJ/m3) than Kevlar, which is the material used in bulletproof vest, and some threads become even more durable (520 MJ/m3), which means that this spider beats even the most talented scientists and engineers with its skinny small legs and tiny little brain by developing material which is more than ten times tougher. It is believed that these spiders need to have strong nets in order to bare the extreme weather conditions above the river and catch the bugs flying over the river. There are still investigations that have yet to be done in order to find out further properties of such webs. âVerily in these things there are signs for those who consider.â