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the taste of sweet - May 2013

Humans have always sought to make life sweeter. In prehistoric times, sugar cane was already being grown for its sweetening powers, and the sugar added to beverages and food. But why do humans like what is sweet so much? This may well have evolved from our distant ancestors, as far back as those who bore little resemblance to us. In the wild, animals have to depend on colour but also taste – and its very close sister, smell – to distinguish what is edible from what is likely to be toxic. On the whole, bitter is better left alone. As things evolved, a sweet taste became a feeling that was comforting one way or another. So, slowly but surely, sweetness was added to all sorts of foods and liquids. And, today, sugar is usually part of a Westerner’s diet – whether we are aware of it or not. As a result, towards the end of the 20th century, it had become clear that sugar – or an excess of it – was proving to be harmful to the human population, and it was necessary to find ways of making life sweeter without the nasty side effects. In the early 1980s, one such sweetener was rediscovered in a South American plant, Lippia dulcis. Known as Hernandulcin, researchers have recently managed to isolate a key enzyme in its synthesis, known as (+)-epi-alpha-bisabolol synthase. (PDF version - 51K bytes)

UniProt cross references

(+)-epi-alpha-bisabolol synthase, Lippia dulcis, (Aztec sweet herb) : J7LH11

the silence within - March 2013

There can be little worse than seeing – and feeling - your own child retreat into a world that doesn’t involve yours. Especially at a period of life when contact with a mother and a father is such a vital component of an infant’s development. And such a pleasurable one for the parents. Autism hits about one child in a thousand – although the contours of the affliction remain a little hazy. There are many forms. Some more serious than others. Some widespread while others are rare, or even unique. The common denominator is what could be described as a characteristic aloneness, where those suffering from autism are unable to interact socially and communicate in the way most of us do. Today, researchers believe that autism has a strong genetic component and that certain mutations are at the heart of autistic behaviour. One such mutation affects an enzyme known as BCKDK and may well be responsible for a rare hereditary form of autism that could be treated with a specific diet. (PDF version - 499K bytes)

UniProt cross references

BCKDK, Homo sapiens , (Human) : O14874

a wretched tale - January 2013

We all need guidance in life. And sperm cells are no exception to the rule. In plants, as in all living beings that depend on sex to multiply, a male gamete has to reach a female gamete in order to fuse with it. All sorts of mechanisms are used for this to occur. And plants are among the most imaginative organisms on the planet, simply because their mobility is so reduced. As such, they depend on forms of mobility that surround them: wind, bees, wild animals… And they have exploited this remarkably. At the molecular level, however, plants are far more mobile. An example is pollen tube elongation. In mouse-ear cress (Arabidopsis thaliana), for instance, once the pollen is ready to germinate, a bulge protrudes from its surface, elongates – and forms what is known as the pollen tube. Hordes of molecules are involved in pollen tube elongation. But you also need something which can actually guide the tube towards the ovule. And its name is protein HAPLESS 2, or HAP2. (PDF version - 193K bytes)

UniProt cross references

Protein HAPLESS 2, Arabidopsis thaliana , (Mouse-ear cress) : F4JP36

unusual liaisons - December 2012

Sex for procreation. It doesn’t sound in the least bit eccentric. But how about sex between a flower and an insect? We all know that flowers depend very much on insects to perpetuate their species. It is their answer to a lack of legs or wings. Consequently, over the millennia, plants have devised the most creative ways of luring insects into the places where they keep pollen. Some flowers have thought up shapes that resemble an insect’s mate, or places that are ideal for shelter, or they cunningly display colours that are hard for the six-legged species to ignore. Many plants give off scents to trick pollinators. One particular type of orchid has gone a step further and found out how to mimic the sex pheromones of some wasps. The poor wretches are tricked into thinking that the orchid is a potential sex mate and land on it to copulate. It’s a SAD story really. Indeed, SAD – otherwise known as stearoly-acyl carrier protein desaturase – is the key enzyme in the synthesis of the fraudulent pheromone. (PDF version - 319K bytes)

UniProt cross references

Acyl-[acyl-carrier-protein] desaturase 2, chloroplastic, Ophrys sphegodes, (Early spider orchid) : E3PZS2

asking life to be patient - November 2012

One thousand, every heartbeat. That is the rate at which sperm multiply in a healthy human male individual the moment puberty kicks off. It is a lot. And each sperm is potentially fertile. Ejaculation is therefore a very serious affair, and pushes one lonely egg into dangerous terrain if pregnancy is not desired. This is where contraceptives come in. Contraceptives for men – other than condoms and vasectomy – remain a tricky affair for a number of reasons. One being the sheer amount of sperm a contraceptive has to consider. Finding a solution at the level of the egg seems – naturally – less of a hassle than looking for something able to deal with millions of sperm at a time. Which is no doubt one of the reasons – though by far not the sole reason – that the popular pill came crashing into our society in the 1960s. Fifty years later, there is hope that a male contraceptive has been found. It all has to do with a protein known as Bromodomain testis-specific protein and a small inhibitor molecule known as JQ1. (PDF version - 66K bytes)

UniProt cross references

Bromodomain testis-specific protein, Homo sapiens, (Human) : Q58F21

Bromodomain testis-specific protein, Mus musculus, (Mouse) : Q91Y44