Excerpts from Recent Articles

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Going unnoticed - June 2008

There are people who saunter through life unnoticed until something happens and reveals that they are far less ordinary than they appeared to be. The same goes for Heliobacter pylori. H. pylori is a bacterium which was discovered in the late 1800s but was forgotten for the best part of a century simply because no one had succeeded in cultivating it. Its role in causing gastric diseases was also discussed at the turn of the 19th century, only as the results were published in Polish they met with very little recognition outside Poland. And while H.pylori was being ignored, attempts were being made to study an enzyme which helps it to survive in the organisms it infects: urease. Like H.pylori, urease had to wade through waves of short-sightedness. Not only was it a common belief in those days that enzymes could not be proteins, but enzymes were also thought to exist in excessively low concentrations in plants and animals… Despite these barriers, H.pylori and urease finally triumphed at the end of the 20th century and both turned out to be singular entities. (PDF version - 452k bytes)

Swiss-Prot cross references

Urease subunit alpha, Helicobacter pylori : P14916
Urease subunit beta, Helicobacter pylori : P69996

The selfish smell - May 2008

We are surrounded by smells. Pleasant ones and not so pleasant ones, hard to distinguish ones, mild ones and strong ones. Smells are not part of our everyday life for the simple sake of pleasure. They are there for a purpose. The perfume of a flower can be used as an attractant for a potential pollinator, for instance. The scent given off by a poisonous mushroom is a way of warding off a predator and, by the same token, can be instantly recognised as toxic by an animal, thereby saving both species. Special scents are also given off by males and females when mating is in the air, and no wine grower will ever argue that a wine’s fragrance is not for the sole purpose of seduction. But what is a smell? More often than not, a scent is made up of a mixture of odorant molecules which, together, will trigger off a complex olfactory system that will ultimately let us perceive it and, if we wish to, put words to it. The very first step in such a system involves an odorant receptor to which an odorant molecule binds. Recently, a new human odorant receptor – OR7D4 – was discovered. OR7D4 is special in that it is the first receptor known to respond to a specific odorant molecule. (PDF version - 251k bytes)

Swiss-Prot cross references

Olfactory receptor 7D4, Homo sapiens (Human): Q8NG98

Molecular chastity - April 2008

Triggering off the making of a baby may seem a pretty straightforward process. Which it is, from a certain point of view. Yet, before any decisive action is undertaken by a woman and a man in order to unite their gametes, sperm – like ovules – have already been through a very complex series of developmental transformations. Such transformations ensure that only sperm and ovules of the same species get involved with one another, for example, or that once a couple of gametes has united no one else is allowed in. Properties of this sort are expressed on the molecular level both on the sperm’s and the ovule’s surface. One such molecule is a receptor known as zp3 found in mammals. Zp3 is expressed on the ovule’s surface and, though it is just one of many molecules, it is an essential one. Without it, sperm would not only be incapable of binding to the ovule’s membrane but they would also most probably miss their target altogether. (PDF version - 99k bytes)

Swiss-Prot cross references

Zona pellucida sperm-binding protein 3, Homo sapiens (Human): P21754
Zona pellucida sperm-binding protein 3, Mus musculus (Mouse): P10761
Zona pellucida sperm-binding protein 3, Rattus norvegicus (Rat): P97708

A dog's life - March 2008

Dogs were not meant to fit into a bag. Yet, some do. Consequently, instead of enjoying a healthy walk in the countryside they can go shopping with their owners. Convenience – both for humans and dogs – has trimmed down canine size in the past few hundred years. It is easier for dogs to be part of a household if they are medium-sized and more practical for humans to keep them if they are not too large. As such, natural selection coupled with selective breeding has supplied us with dogs ranging from barely twenty centimetres to giant samples which measure over one metre. And the stakes that a cross between a large poodle and a tiny Chihuahua will produce a medium-sized mongrel are high. So there must be a straightforward mechanism which is involved in their size. IGF1 – or insulin growth factor 1 – seems to be at the heart of such a mechanism. Indeed, scientists have discovered that small dogs all carry a certain variant of IGF1 while large dogs do not – or very few. This would suggest that the IGF1 variant has the power to reduce the size of a dog. (PDF version - 72k bytes)

Swiss-Prot cross references

Insulin-like growth factor 1, Canis familiaris (Dog): P33712

The hands to say it - February 2008

When I was a little girl, I thought that my left-handed classmates were special. I envied their difference. And I used to marvel at the way they crouched over their desk, embracing something invisible as they did their best to avoid smudging ink all over their sheet of paper. Left-handedness is special. But so is right-handedness. Humans are not the only animals to make use of their hands – or claws, or paws, or hooves - but they are the only ones who show a marked preference for either the left one, or the right one. If this is so, there must be a reason for it. And not only must there be a reason but it must translate a certain structure of our brain: an asymmetry somewhere. Indeed, our brain is divided into two hemispheres which are dedicated to processing different activities. One side looks after our dreams, while the other is far more down to earth. LRRTM1 is the first protein to have been discovered which seems to be directly involved in this brain asymmetry. Consequently, it influences the handedness of a human-being and, more astonishingly, may also predispose individuals to psychotic troubles such as schizophrenia. (PDF version - 65k bytes)

Swiss-Prot cross references

Leucine-rich repeat transmembrane neuronal protein 1, Homo sapiens (Human): Q96DN1