Excerpts from Recent Articles from 2005

2005 Back Issues

The thread of life - December 2005
Christmas seems to come around faster each year. And with it, the inevitable sensation that time is truly passing and – though we may be getting a little wiser – we are getting none the younger. Like it or not, we are stuck with life the way we are stuck with the prospect of death. We can trick the traces of the passage of time with plastic surgery but underneath, our bodies are ageing without mercy. How? And is it genetic? Environmental? Both? Neither? A child’s development into a full-grown adult bears a strong genetic component. It is not yet clear, though, whether the process of ‘just getting old’ does too – although a number of disorders which bring on premature ageing would suggest something of the like. A protein named Klotho, discovered by chance in the late 1990s, is helping to unveil the process involved in an individual’s longevity. (PDF version - 49K bytes)
Swiss-Prot cross references
Klotho, Homo sapiens (Human): Q9UEF7
Klotho, Mus musculus (Mouse): O35082
Klotho, Rattus norvegicus (Rat): Q9Z2Y9
A grey matter - November 2005
The human brain has been a hot issue for centuries. Physical anthropology flourished in the 19th century and with it the science of craniometry compounded by a growing belief in biological determinism. Intelligence – that intangible quality – was quantified and said to be dependent on brain size. Criminality was based on facial features and cranial particularities. And the notion of racism became a bodily measurement. Thankfully, the 20th century offered the necessary wherewithal to tone down all these beliefs thanks to an ever-growing knowledge of the molecular processes going on inside the human body. Intelligence is no longer quantifiable and cannot be defined according to the size of a human brain. Criminality has nothing to do with someone’s looks and population genetics have demonstrated that the notion of race has no real meaning. Despite all this, it is clear that modern humans would not be where they are, were it not for the size of their brain, and its grey matter. And we now know of a number of proteins that are involved in such a process, one of which is a protein known as microcephalin. (PDF version - 43K bytes)
Swiss-Prot cross references
Microcephalin, Homo sapiens (Human): Q8NEM0
The colour of the rose - October 2005
One of the beauties of Autumn is the firework of orange, yellow and red hues it displays. Anthocyanin is a plant pigment involved in this colourful palette. And not only in the autumnal shades but also in the reds, blues and purples of petals and fruit all year round. The array of colours offered to us by Nature has always fascinated scientists who have put a great deal of effort into understanding both the structure of the various pigments but also the pathways leading to their synthesis. The final steps leading to anthocyanin are performed by an enzyme known as anthocyanidin glucosyltransferase. And in roses, this particular enzyme catalyses not one reaction – as is the case in the production of other flower anthocyanins known to date – but two reactions which lead to rose anthocyanin. (PDF version - 50K bytes)
Swiss-Prot cross references
Anthocyanidin 5,3-O-glucosyltransferase, Rosa hybrid cultivar: Q4R1I9
Shackled sperm - September 2005
We are all looking for attention. One way or another. Even spermatozoa. In its race to fertilise, a spermatozoon modifies the egg’s surface thereby demolishing the hope of millions of its kind. It may lack fair play but it certainly is an effective way of grabbing attention. This is exclusiveness on the level of sperm. However, scientists are beginning to realise that semen also has its ways: coagulation. What better way to hinder the advancement of a supplementary troop of sperm than by the erection of a biological fortification? When semen is ejaculated, it coagulates almost instantly to then liquefy slowly, unshackling spermatozoa in the process. A number of chemical entities are involved, one of which is semenogelin, the protein which forms the coagulate scaffold. (PDF version - 46K bytes)
Swiss-Prot cross references
Semenogelin-1, Homo sapiens (Human): P04279
Semenogelin-2, Homo sapiens (Human): Q02383
No one nose - August 2005
Do we, or do we not, have a sixth sense? Yes say most. And it certainly does seem to be the case. Like many animals, we are capable of responding to sensory chemicals of which we are quite unaware – pheromones – and that can modify our behavior. We are, however, in the process of losing – though not all agree – the organ which may well have been used by our ancestors to perceive such an obscure sense: the vomeronasal organ which can be observed just in the inside of our nostrils. The intriguing part is that a subfamily of protein receptors, which suspiciously resemble known mammalian pheromone receptors, has been discovered in humans: the type 1 vomeronasal receptors. Could it be then that not only do we have a sixth sense but we also have an organ dedicated to it? Just like in the good old days? (PDF version - 45K bytes)
Swiss-Prot cross references
Type 1 vomeronasal receptor 1, Homo sapiens (Human): Q9GZP7
Type 1 vomeronasal receptor 2, Homo sapiens (Human): Q8NFZ6
Type 1 vomeronasal receptor 3, Homo sapiens (Human): Q9BXE9
Type 1 vomeronasal receptor 4, Homo sapiens (Human): Q7Z5H5
Type 1 vomeronasal receptor 5, Homo sapiens (Human): Q7Z5H4
The life of a whiff - July 2005
Any scent conveys a message. It can be a nice one or not such a nice one but a smell always has something to say. And living organisms of all forms and sizes make great use of scents in matters so crucial as reproduction or more down to earth as mere survival. A scent can ward off a predator or, on the contrary, attract an admirer. Flowers are great users of smells; since they cannot move around the way animals do, they make sure their scented emissions can. And they know when to let a whiff off. A scent is a combination of chemicals that a flower synthesizes. A flower, however, will not release a fragrance unless it needs to. What is it that orchestrates the biosynthesis and subsequent emission of a smell or not? In petunias, a protein known as ODORANT-1 seems to be at the heart of smell: without it, a petunia’s petal would be scentless. (PDF version - 38K bytes)

Swiss-Prot cross references

ODORANT1 protein Petunia hybrida (Petunia): Q50EX6

Lipid freight - June 2005
Life is not static. Despite the apparent coolness of living matter’s external features – save for the twitch of an insect’s antenna or the flick of a chameleon’s tongue – our insides are seething. Molecules of all shapes and sizes are being frantically – and continuously – ferried from one part of our body to another by way of an intricate mesh of highways and side roads which bear as many sign posts and traffic regulations as any regular metropolis. When humans need to go from A to B, they climb into a car, hop onto a bus or thumb a ride. What kind of transport do proteins use? Or other biomolecules? Well, there seem to be as many means of ‘biotransport’ as there are makes of car. And one is the Lipid Transfer Particle (LTP), a lipid shuttle found in insects, the scaffolding of which depends on a particular type of protein: the lipophorins. (PDF version - 315K bytes)
Swiss-Prot cross references
Apolipophorin precursor (Apolipophorin I and II) Manduca sexta (Tobacco hornworm): Q25490
Apolipophorin III Manduca sexta (Tobacco hornworm): P13276
Apolipophorin precursor (Apolipophorin I and II) Locusta migratoria (Migratory locust): Q9U943
Apolipophorin III Locusta migratoria (Migratory locust): P10762
Tintin's blight - May 2005
Tintin never grew up. Readers followed his travels around the world for almost fifty years and yet the Belgian journalist showed no signs of aging whatsoever. No grey hair, no wrinkles, no loss of stamina. He never changed style either; he never seemed to tire of his knickerbockers nor of his cranial crest. But that is beside the point… How can a human span a lifetime looking as though he never grew older than the age of fifteen? Hypogonadotropic hypogonadism or HH say some. HH is a condition in which the subject who is inflicted with it never reaches puberty. Typically, in a man, this would mean that he shows no signs of becoming one, i.e. in growing facial hair for example or being the proud owner of a mature reproductive system. Tintin never took his pants down but any of his readers know that he certainly never showed signs of growing a beard. HH in a man is caused when the regulation of the male hormone, testosterone, is deficient. And we now know of one protein which seems to have a key role in such a regulation: the KiSS-1 receptor. (PDF version - 27K bytes)
Swiss-Prot cross references
KiSS-1 receptor, Homo sapiens (Human): Q969F8
Metastasis-suppressor KiSS-1, Homo sapiens (Human): Q15726
Flower power - April 2005
There is not much we have in common with sweet corn and yet, when you take a closer look at the way an egg cell is fertilised in flowering plants, it is difficult to avoid making comparisons with humans. A long tube – the pollen tube – must make its way into the female gametophyte and release its sperm cells which will then fertilise the egg cell. The great difference however is that a pollen tube has to elongate and travel quite far to perform its business because pollen – unlike sperm – is not mobile. A number of questions arise. What, for instance, guides the pollen tube towards the gametophyte? And how does it know when it has reached it? Scientists have found the beginning of an answer in the form of a small protein: Zea mays EGG APPARATUS 1 or ZmEA1, which has a role in pollen tube guidance and orientation in the phases preceding egg cell fertilisation. (PDF version - 56K bytes)
Swiss-Prot cross references
Egg apparatus-1 protein (ZmEA1), Zea mays (Maize): Q5G8Z3
Forbidden fruit - March 2005
After a century’s ban, Switzerland has legalised the production of absinthe – the emerald-green liquor which was said to have caused the madness of many throughout the 1900s, one of whom was the Dutch artist Vincent van Gogh. The beverage is prepared by macerating a cornucopia of spices and herbs such as aniseed, fennel, hyssop, lemon balm, angelica, star anise, dittany, juniper, nutmeg, veronica and wormwood oil in alcohol. It is hardly surprising that, upon abuse and on a long-term basis, such a mixture of chemicals should have an undesirable effect on our system. Nevertheless, at the dawn of the 21st century, a greater understanding of absinthe’s claimed toxicity is surfacing and fingers are pointing at thujone, a terpenoid found in wormwood oil. Besides lending absinthe its particular flavour, thujone has the ability to bind to receptors in our brain – gamma-aminobutyric acid A receptors or GABAA receptors – which can bring on a number of brain disorders. (PDF version - 80K bytes)
Swiss-Prot cross references
Gamma-aminobutyric-acid receptor gamma-3 subunit, Homo sapiens (Human): Q99928
Gamma-aminobutyric-acid receptor gamma-2 subunit, Homo sapiens (Human): P18507
Gamma-aminobutyric-acid receptor gamma-1 subunit, Homo sapiens (Human): Q8N1C3
Gamma-aminobutyric-acid receptor beta-3 subunit, Homo sapiens (Human): P28472
Gamma-aminobutyric-acid receptor beta-2 subunit, Homo sapiens (Human): P47870
Gamma-aminobutyric-acid receptor beta-1 subunit, Homo sapiens (Human): P18505
Gamma-aminobutyric-acid receptor alpha-6 subunit, Homo sapiens (Human): Q16445
Gamma-aminobutyric-acid receptor alpha-5 subunit, Homo sapiens (Human): P31644
Gamma-aminobutyric-acid receptor alpha-4 subunit, Homo sapiens (Human): P48169
Gamma-aminobutyric-acid receptor alpha-3 subunit, Homo sapiens (Human): P34903
Gamma-aminobutyric-acid receptor alpha-2 subunit, Homo sapiens (Human): P47869
Gamma-aminobutyric-acid receptor alpha-1 subunit, Homo sapiens (Human): P14867
The taste experience - February 2005
To what end do we need to taste? Just to enjoy a night out at the restaurant? Fish can also taste. But they do not go out for dinner. We – like all animals – taste because we have to be able to distinguish between what is good for us, and what is not. Nowadays, things are easy. All you have to do is saunter down the road to the nearest supermarket and pick out what you need. Most of us can read, and relate the word ‘tomato’, ‘steak’ or ‘chocolate’ to a taste. Thousands of years ago, though, there were no supermarkets (or chocolate) and our ancestors could only rely on their taste buds. As a consequence, they learned that sweet-tasting foods were probably edible, whilst bitter ones were probably not, because – more often than not – bitterness spelled poison. And the distinction we are able to make between sweet and bitter resides in taste receptors which are lodged in the recesses of our taste buds. (PDF version - 76K bytes)
Swiss-Prot cross references
Sweet taste receptor T1R3, Homo sapiens (Human): Q7RTX0
Sweet taste receptor T1R2, Homo sapiens (Human): Q8TE23
Sweet taste receptor T1R1, Homo sapiens (Human): Q7RTX1
Questioning Colour - January 2005
In the early days of the last century, scientists believed that the colour of our eyes was a straightforward inherited trait. Mendel’s laws of inheritance had become fashionable and eugenicists saw in them an elegant and practical way to define our species. However, as the years passed and research in genetics progressed, ascribing the pigmentation of our eyes to the powers of a sole gene soon showed its weaknesses. Pigmentation proved to be a complex biological process. Nevertheless, as the 20th century bows out and the 21st bows in, it appears that – though pigmentation as a whole is part of an intricate biochemical network – the colour of our eyes does indeed seem to be in the hands of one gene which codes for a protein known as the P protein. (PDF version - 47K bytes)
Swiss-Prot cross references
P protein, Homo sapiens (Human): Q04671


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