Excerpts from Recent Articles from 2010

2012 Back Issues

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
branching out - October 2012
Humans are unique. Whichever way you look at it. We can talk. We can write. We can build skyscrapers, make art, design weapons and be a general nuisance to many other life forms. About 2.5 million years ago however, our ancestors could not. So what happened? Something was needed to modify brain structure and spark off another form of intelligence. Genetic mutations are the answer to this. And natural selection of course. There is a gene, known as SRGAP2, which is found in the brain tissues of humans and our closest relatives – chimpanzees, gorillas and orang-utans. It so happens that SRGAP2 has a duplicate – SRGAP2C – which seems to be only found in humans. SRGAP2C is thought to have appeared at about the time the Homo genus emerged from the ancestral Australopithecus genus, about 2.5 million years ago. This would suggest that SRGAP2C had a pivotal role in forging the human brain, and was engaged in shifting our ancestors’ somewhat rudimentary behaviour to more sophisticated ways. (PDF version - 372K bytes)
UniProt cross references
SLIT-ROBO Rho GTPase-activating protein 2, Homo sapiens, (Human) : O75044
SLIT-ROBO Rho GTPase-activating protein 2, Mus musculus, (Mouse) : Q91Z67
nature's flaws - September 2012
Nothing is perfect. And nature is no exception. This said, we should be grateful for nature’s imperfections because, were it not for them, we would not be here. Without the changes that have been accumulating in genes over millions of years, we would not know the rich diversity of species that inhabit Earth today. Yet we all know that mutations can be lethal to an individual. Tinker with a crucial position in a gene and you can find yourself with a severe handicap. Extensive damage to a cell’s genome can lead to all sorts of ailments, not the least cancer. This is why Nature imagined DNA repair mechanisms so as to limit the damage and prevent as many mutations as possible. One such mechanism is nucleotide excision repair, and at its heart: protein Xeroderma Pigmentosum A (XPA). (PDF version - 470K bytes)
UniProt cross references
DNA repair protein complementing XP-A cells, Homo sapiens, (Human) : P23025
life's boundaries - September 2012
There is only one way of propagating the species, and that is by mating. However, for many animals, mating usually implies hordes of sperm all fighting to get their nucleus into one egg. The same goes for humans. It is perhaps an odd thing in the first place for Nature to have devised what seems to be an uneconomical procedure, and if an oocyte is fertilised by more than one spermatozoon, the ensuing zygote is not viable. So it was necessary to develop some modus operandi by which one sperm is allowed in, while the others are kept out. In fact, over time, animals have armed themselves with more than one strategy to avoid polyspermy. One of the most definitive is to act upon the zone which surrounds an oocyte – the zona pellucida – by making it impenetrable the moment one sperm has wriggled its way through it. Scientists have known for many years that this particular region changes its structure following fertilisation but they didn’t know what caused the change. Until they discovered a protease, which has been dubbed ovastacin. (PDF version - 90K bytes)
UniProt cross references
Astacin-like metalloendopeptidase, Mus musculus, (Mouse) : Q6HA09
Astacin-like metalloendopeptidase, Homo sapiens, (Human) : Q6HA08
the poison in pain - July 2012
Pain is a persuasive way of keeping the enemy at bay. Hosts of living beings make use of it, both in the animal and the plant world. Many of us have experienced the sting of a nettle, or indeed a wasp, a cat’s scratch and perhaps even the nip of a spider. And who hasn’t used the end of their foot to assign a kick or two, right where it hurts? Besides spitting out a few venomous words… Not many of us, however, have actually come across a snake and the twang of its venom. As we all know – or have been told – a snake’s bite can vary from being a little uncomfortable to excruciatingly painful and even harmful, not to mention fatal. Over the millennia, a snake’s venom has been perfected and become a highly specialised cocktail of hundreds, even thousands, of molecules – most of which are proteins. Recently, scientists discovered a neurotoxin – dubbed MitTx – that causes pain via acid-sensing ion channels which run along the membranes of neurons. A novelty in the world of nociception. (PDF version - 939K bytes)
UniProt cross references
Phospholipase A2 homolog Tx-beta, Micrurus tener tener, (Texas coral snake) : G9I930
Neurotoxin MitTx-alpha, Micrurus tener tener, (Texas coral snake) : G9I929
on the other side - June 2012
We all need sleep. Yet sleep spells ‘off our guards’ and, from a purely biological point of view, it is not a wise move. In the land of Nod, an organism is vulnerable and an easy prey for predator. So there must be something essential in taking a nap for Mother Nature to have thought it up. Indeed, when asleep, organisms are shut off from their surroundings for a period – a period they use to build up the energy they spend their time depleting when awake. It is all a question of vital energy balance. For such a system to work, however, we need something that not only measures our body’s level of energy but also has a role in our sleeping behaviour. There happen to be many known systems that do one or the other but it is the first time that scientists have found a protein that reacts to levels of ATP and is directly involved in the length of time we sleep. (PDF version - 325K bytes)
UniProt cross references
ATP-binding cassette sub-family C member 9, Homo sapiens, (Human) : O60706
ATP-binding cassette sub-family C member 9, Drosophila melanogaster, (Fruit fly) : Q9VL32
on sex, drugs and satisfaction - May 2012
Pleasure is not a human invention. Experiences that arouse a feeling of contentment are as old as life. They have, in fact, kept life going. It is yet another of Mother Nature’s tricks. If an organism perceives something as good, then it will do it again. If you want to keep a species going, the best way to do it is to reproduce. And, if the act of copulation is a pleasant experience, there’s a fair chance you’ll have another go at it. Eating, sex and social interactions are examples of acts most animals are accustomed to, and for which they are rewarded with a positive feeling. They also happen to be interactions which keep a species alive. But what happens when an animal meets frustration? Following rejection by a potential mate, for example? It finds some other way to quench its desires. Given the chance, Drosophila melanogaster will actually turn to alcohol if mating has been denied. Sex and alcohol are part of a highly complex reward system that has had plenty of time to evolve. Recently, scientists discovered the agent which orchestrates both behaviours: Neuropeptide F. (PDF version - 243K bytes)
UniProt cross references
Neuropeptide F, Drosophila melanogaster, (Fruit fly) : Q9VET0
kiss of life - April 2012
We all take Spring for granted. The moment the first bouts of warmth hit the air, we fully expect to see the lawn duly mottled with daisies, leaves pushing their way into the nascent season and flowers blossoming wherever we care to look. And quite rightly so. We all know it’s going to happen since it does every year. And we do realise that Nature needs to renew itself every once in a while. The process is – you could say – automatic. But it is only automatic because there are hordes of molecules that are able to recognise, in many different ways, the environmental cues – such as warmth and humidity for instance – and translate them into growth. An amazing state of affairs, if you give it a little thought. One such molecule, known as DELLA protein RGL2, has been the centre of attention amongst plant molecular biologists for some time now. Indeed, RGL2 is proving to be at the very heart of seed germination. (PDF version - 33K bytes)
UniProt cross references
DELLA protein RGL2, Arabidopsis thaliana, (Mouse-ear cress) : Q8GXW1
the ends of our fingers - March 2012
Fingertips are hugely sensitive. And, besides the fairly recent mobile phones that rely on them entirely, we put their sensitivity to use constantly. They are able to grasp subtle differences in temperature and texture – such as discern warm from tepid for example, or a dry surface from a greasy one. They are also able to touch or feel extremely delicately. In truth, the ends of our fingers are able to give a pretty clear picture of what is happening around us. This, of course, is thanks to nerve ends which reach the very tips of them. But scientists are now suggesting that our digital refinement may also be partly due to the epidermal ridges which cover them. In other words: our fingerprints. Fingerprint architecture is slowly being uncovered, thanks to diseases that have the power to wipe them away. One such disease – known as adermatoglyphia – is caused by a deficiency in a protein known as SMARCAD1. (PDF version - 230K bytes)
UniProt cross references
SWI/SNF-related matrix-associated actin-dependent regulator of chromatin subfamily A containing DEAD/H box 1, Homo sapiens, (Human) : Q9H4L7
get a grip - January 2012
Someone once told me that they had spread grease all over the drainpipe that crawled up the front of their house, to prevent cats from climbing up it. It’s a very simple and pretty harmless way of keeping the enemy away. It’s hardly surprising, then, that Nature thought up just the same trick millions of years ago. Many higher plants’ stems – and also sometimes their leaves – are covered with a whitish surface, which is slightly greasy to the touch. Botanists have known for a long time that wax in plants has many roles and that the powdery blooms on stems seem to be involved in keeping harmful insects away. The question is: how? But perhaps even just as important a question is: what makes the wax? Because if scientists are able to be on a more intimate level with what produces it, then they will be able to think up insect repellents that are more in keeping with Nature’s ways. Not so long ago, researchers discovered an enzyme which synthesises lupeol, the wax component which forms the greater part of the powdery bloom. (PDF version - 47K bytes)
UniProt cross references
Lupeol synthase, Ricinus communis, (Castor bean) : Q2XPU7


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