Sunday, July 11, 2010

What came first the chicken or the egg?

British researchers may have uncovered a partial answer to the age-old question, "what came first the chicken or the egg?"
According to a team, comprising researchers from the University of Warwick and the University of Sheffield, the answer is "chicken" or at least a particular chicken protein.
There is, however, a further twist - this particular chicken protein turns out to come both first and last. That neat trick it performs provides new insights into control of crystal growth which is key to egg shell production.
Scientists have long believed that a chicken eggshell protein called ovocledidin-17 (OC-17) must play some role in egg shell formation. The protein is found only in the mineral region of the egg (the hard part of the shell) and lab bench results showed that it appeared to influence the transformation of (CaCo3) into calcite crystals. The mechanism of this control remained unclear. How this process could be used to form an actual eggshell remained unclear.
University of Warwick researchers Mark Rodger and David Quigley, in collaboration with colleagues at the University of Sheffield, have now been able to apply a powerful computing tool called metadynamics and the UK national supercomputer in Edinburgh to crack this egg problem.

Dr David Quigley from the Department of Physics and Centre for Scientific Computing, University of Warwick, said: "Metadynamics extends conventional molecular dynamics (MD) simulations and is particularly good at sampling transitions between disordered and ordered states of matter."
Using these tools, the team was able to create simulations that showed exactly how the protein bound to amorphous calcium carbonate surface using two clusters of "arginine residues", located on two loops of the protein and creating a literal chemical "clamp" to nano sized particles of calcium carbonate.
While clamped in this way, the OC-17 encourages the nanoparticles of calcium carbonate to transform into "calcite crystallites" that form the tiny of nucleus of crystals that can continue to grow on their own. But they also noticed that sometimes this chemical clamp didn't work. The OC-17 just seemed to detatch from the nanoparticle or "be desorbed".
Professor Mark Rodger from Department of Chemistry and Centre for Scientific Computing, University of Warwick, said: "With the larger nanoparticles we examined we found that the binding sites for this chemical clamp were the same as the smaller nanoparticles but the binding was much weaker. In the simulations we performed, the protein never desorbed from the smaller nanoparticle, but always fell off or desorbed from the larger one. However in each case, desorption occurred at or after nucleation of calcite."

The researchers had therefore uncovered an incredibly elegant process allowing highly efficient recycling of the OC-17 protein. Effectively it acts as a catalyst, clamping on to calcium carbonate particles to kickstart crystal formation and then dropping off when the crystal nucleus is sufficiently large to grow under its own steam. This frees up the OC-17 to promote more yet more crystallisation, facilitating the speedy, literally overnight creation of an egg shell.

The researchers believe that this new insight into the elegant and highly efficient methods of promoting and controlling crystallisation in nature will be of great benefit to anyone exploring how to promote and control artificial forms of crystallisation. '

 Thx 2 Yahoo...

Tuesday, July 6, 2010

Just sniff him out

DID YOU know that the odour of your man's body is probably what makes you want to touch him? You may scoff at the idea, especially since there is such a plethora of products to disguise this- deodorants, body washes and creams. But the reality is that the natural, unscented smell of a male body and sweat is far more sexually potent than the Axe spray he applies to mask it!
According to a study by the UK-based Social Issues Research Centre, females often get attracted to the scent of male sweat. Our bodies release certain chemical substances, called pheromones that are sensed through the nose and trigger sexual urges in prospective partners. These are secreted by sweat glands largely present in underarms, nipples, genitals, and outer ears."
Body odour often influences a partner's sexual behaviour and women are more receptive to it," says Dr ( Col) V K Wadia, consultant, psychosexual medicine. " During a sexual intercourse, specific odours are secreted by men and it's a woman's perception how she gets influenced by them," he adds.

Not only is body odour significant in sexual behaviour, it plays a decisive role in mate choice as well. "Men and women tend to prefer the odour of individuals who are genetically dissimilar to them," says Dr Anoop Misra, director, department of diabetes and metabolic diseases, Fortis Hospital.
This reduces the chances of inbreeding and renders offspring more resistant to diseases and infections. However, odour preferences can vary according to hormonal changes. "Studies say that women often prefer the odour of men with good parenting skills in the 'fertile period' or the postmenstrual phase," says Dr Misra.
ON THE other hand, men find women more attractive during ovulation. This is mainly due to the specific odour of women in that period. It has also been found that women who are emotionally bonded with their partners perceive the odour of other men less pleasant.
So, what makes our odour so specific? Usually when we perspire, sweat reacts with bacteria present on our skin. This releases some chemicals, hence causing body odour. But it's not just an outcome of sweat. "All of us have a signature odour. This uniqueness is marked by genetics, diet, age, gender, hormones, and environmental factors," says Dr Sushila Kataria, senior consultant, internal medicine, Medanta - The Medicity.
This explains why babies smell different from adults, and how odour changes with the onset of puberty. This also explains why some of us have specific unpleasant odours. Bad breath or strong sweat can be a sign of underlying physical problems. "Patients with diabetic ketoacidosis can have a fruity odour in their breath and skin," says Dr Misra.
Diabetic ketoacidosis is a condition of excessively high blood sugar level that leads to formation of chemical substances called ketone bodies. Their presence causes the typical smell. The best way to prevent is to keep one's blood sugar levels in control.

"In case of chronic kidney problem, or dysfunctional kidneys, the patient's body odour may resemble that of ammonia. This is because such patients retain more wastes or urea in the blood, that spreads to skin and evaporates with sweat," says Prof ( Dr) S C Tiwari, director, nephrology, Fortis Group of Hospitals.
Moreover, a musty odour in hair, breath or skin could be a sign of a genetic disorder called phenylketonuria (PKU). Left untreated in early childhood, it could lead to mental retardation or brain damage later. "Similarly, bad breath could be a symptom of non-healing ulcers in the throat, lungs or respiratory tract," points out Manoj K Goel, director, pulmonology, Delhi Heart and Lung Institute. Bad breath could also be sign of bacterial pneumonia and chronic bronchitis.

"Cough accompanied by foul smell may be a symptom of lung abscess. Such infections pose immense risks as these could result in cancer if left unattended," he cautions.

monalisa.das@mailtoday.in
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