Friday, July 25, 2008
Maybe more significant for today's debates, however, is that the UK was very lucky to have been host to the pioneering IVF work more than three decades ago. The discussions around this work led to pioneering legislation and to the regulatory authority HFEA (Human Fertilisation and Embryo Authority), which meant that 20 years later, when issues like stem cells and therapeutic cloning came up, the UK was well-prepared and had structures in place to enable new pioneering work to be permitted on its merits, while in places like Germany the debates still rage on. Blind luck for the government of the day, of course, as nobody would have predicted that issues under the remit of the HFEA would become so big so quickly.
So this anniversary offers reason to celebrate not just for people with fertility problems, but also for biomedical scientists.
Thursday, July 24, 2008
Hafsia Herzi who deservedly won the Cesar for "meilleur espoir feminin" (best female newcomer) at the Cesars.
Here's an interview clip with Hafsia Herzi:
Wednesday, July 23, 2008
While not quite perfect (it's quite clear which tracks are killers, and which are fillers), I think it is remarkable as a debut. Imagine Christina Aguilera skipping the "genie in a bottle" phase and doing "stripped" with Daddy Yankee providing the rhythm section. There's an interesting mix of various musical styles from the caribbean and further afield, and Kat's got first writing credit on all tracks but one. Here's definitely somebody to watch.
I usually skip the cringe-worthy spoken intro, though, which also reminded me of Stripped, and which I don't really want to hear 10 times a day (do I hear somebody banging on the door with a sledgehammer ?)
Tuesday, July 22, 2008
In these times of rising sea levels, mangrove swamps offer vital protection for coastlines in the tropics, as research supported by Earthwatch has shown. Now, the biofuel megafarms are threatening this, opening doors for disasters on the scale of the boxing day tsunami. In Kenya, a major sugar cane plantation project has been approved at the expense of a large mangrove area.
Read my story here (open access):
Kenya's conservation challenge
Current Biology, Vol 18, R576-R577, 22 July 2008.
Good news, in the same story, is that Kenya's elephants are doing well.
Monday, July 21, 2008
Intriguing stuff. And a movie script that basically writes itself. Mad scientist fiddles with the human development clock, produces generation of snake-like babies ...
Friday, July 18, 2008
Making Science Sexy.
Complete with exclusive portrait taken by the paper's photographer ...
Thursday, July 17, 2008
Strictly for research, of course, for that book that I haven't written yet.
Wednesday, July 16, 2008
For details visit www.sigridgross.com
It's a coming-of-age story set in the chaotic (and often dangerous) city of Lagos. Atta is certainly an interesting new voice in the underappreciated field of African literature.
PS I'll take this opportunity to emphasize that Peter Hammer Verlag is not a publishing company founded by a Mr Hammer. It is named thus after a tradition going back over centuries of publishing texts that were threatened by censorship under a fictional imprint, which was sometimes given as "Pierre Marteau" and sometimes as the German equivalent "Peter Hammer". The whole point of the exercise being that the person Peter Hammer did not exist. So it's both amusing and somewhat frustrating to read on booksellers websites and in reviews something like Published by Hammer, or by Hammer, Peter.
Tuesday, July 15, 2008
In February 2006, I was famous for a day, making media appearances around the globe. This was all due to a press release which the Royal Society of Chemistry had issued ahead of Valentine’s Day, based on the following story. I have to say, however, that I was quite glad when Valentine’s Day was over and the radio stations stopped calling.
Cupid, the mischievous little archer, may be all around us at this time of the year, but there is little scientific evidence to support the age-old claim that his arrows make people fall in love. Plato’s beautiful explanation involving the loss of an “other half” wouldn’t withstand today’s peer review either. And if anybody tries to sell you a love potion à la Tristan and Isolde, you should not expect any miracles from it.
Despite the failure of the romantic explanations, the romantic phenomenon persists, and according to love researcher Helen Fisher it is “a universal or near-universal cultural constant.” There is no human culture on Earth, she claims, that has been proven not to know the phenomenon of romantic love.
If it is universal, scientists argue, there must be biological basis for it. In other words, it cannot be simply a cultural tradition like cricket or opera. In recent years, some researchers have boldly forsaken their natural fear of the irrational side of the human being and set out to investigate the biological and chemical processes underlying romantic love. In particular, they have studied the action of genes, neurons, and chemical messengers such as hormones and pheromones.
Naturally, if some kind of biological phenomenon is universally found throughout a species, one would suspect it to be engrained in the genes in some form or shape. The trouble with love is that it is a complex phenomenon, presumably controlled by complex interactions between many different gene products. Thus, it would be difficult to study for the same reasons that apply to multifactorial diseases such as heart disease. Furthermore, the trouble with human subjects is that ethical concerns rule out manipulations of their genes, which would be required to deconvolute the interactions of many genes.
Therefore, genetic studies of mating and courtship have so far remained limited to animals and to relatively simple questions. The most spectacular and widely reported study of this type was conducted with two species of North American voles, namely the monogamous prairie voles (Microtus ochrogaster), and the genetically related montane voles (Microtus montanus), which do not form any bonds but copulate at random. Thomas Insel and Larry Young at Emory University in Atlanta, Georgia, discovered an insertion in a gene of the monogamous prairie vole which is suspiciously absent in the polygamous montane vole.
To test whether this insert is linked to the difference in sexual behavior, the researchers incorporated the gene with the insert into the genomes of male montane voles. Indeed, they succeeded in “curing” these rodents from their promiscuity with this simple genetic manipulation.
More recently, another “sex gene” has been tracked down in the fruit fly Drosophila. Ken-Ichi Kimura and coworkers at Hokkaido University demonstrated that the protein encoded by the fruitless gene of Drosophila controls the construction of a male-specific neural circuit which is thought to play a key role in male courtship behavior. Which neatly shifts our attention from genes to neurons and the brain.
Truly madly deeply
Modern brain imaging techniques such as functional magnetic resonance imaging (fMRI) or magneto-encephalographic (MEG) scanning are far from being just another tool in the box. They have opened up a whole new world of possibilities, because they enable researchers to observe the working brain without harming the patient.
Helen Fisher, an anthropologist at Rutgers University, joined forces with the New York researchers Arthur Aron and Lucy Brown to investigate the manifestations of early-stage romantic love in the brain. Essentially, they set out to establish whether love works like a fundamental emotion (e.g. fear) or whether it is produced by the feedback loops of the brain’s reward system (like cocaine addiction).
The researchers recruited ten women and seven men who said to have been intensely in love between one and 17 months, and assessed them by interviews before and after the fMRI study. During the imaging experiment, each participant was shown a photo of their romantic partner and asked to recall any cherished memories linked to that person. As negative controls, they were also shown photos of other friends and family members and asked the same question. To purge any romantic feelings between the photos, the subjects were made to perform mental arithmetics, counting backwards from a randomly selected 4-digit number in steps of 7. (Try this procedure if you ever need to clear your brain of romantic overload -- it seems to have been efficient within less than a minute!)
Comparing the brain scans of their subjects wallowing in romantic memories to those linked to neutral photos and those collected during the mental arithmetics exercise, the researchers were able to pin down several key regions of the brain that appear to be involved in intense romantic feelings but not, for example, in face recognition. Specifically, they recorded activation of the in the right ventral midbrain, around the so-called ventral tegmental area (VTA) and the dorsal caudate body and caudate tail. All these regions are unrelated to primeval instincts and emotions such as fear, but they are linked to the reward system that can get us addicted to drugs.
Reviewing their work in comparison with related papers, Fisher, Aron and Brown conclude that “romantic love is primarily a reward system, which leads to various emotions, rather than a specific emotion.” Characteristically, there is no facial expression that can be unequivocally linked to being in love. They also observe that early stage, intense romantic love is different from both the sex drive and the development of attachment in the later phases of a relationship, which activate different areas of the brain.
In a follow-up study, Fisher and her colleagues have started to look at what happens when love goes wrong. “We all get ‘dumped’ at one point or another,” Fisher says. “So I wanted to see what happens in the brain when you are rejected in love.” Accordingly, she and her colleagues applied the brain imaging technology to a group of 15 volunteers who had recently been dumped. From the preliminary results, Fisher concludes that “a lot happens in the brain when you look at a photo of someone who has just abandoned you, including activity in brain regions associated with physical pain, obsessive/compulsive behaviors, controlling anger, and regions that we use when we are trying to speculate on what someone else is thinking.” Far from switching off the brain activities involved in the previous romantic bliss, Fisher finds that “it also appears that when you get dumped you start to love your rejecting partner even harder.”
A key feature of the brain areas that the US researchers have connected to romantic love is that they are involved in signaling pathways using the hormone dopamine. But which other hormones can be blamed for the emotional rollercoasters of romantic love?
Molecules in love
Donatella Marazziti, a psychiatrist at the University of Pisa, started out investigating the hormonal changes connected to obsessive/compulsive disorder, and then moved on to those that occur when people fall in love. Initially, she and her coworkers found a decrease of the functionality of serotonin transporters in the blood of enamored volunteers, who had been selected and rated on the “Passionate Love Scale” (PLS) much like those in the US studies above. Like obsessive/compulsive patients, the love-struck volunteers showed a reduced concentration of serotonin in the blood, which might explain why early phase romantic love can turn into obsession.
In her most recent study, Marazziti, together with Domenico Canale, casts the net wider to check for changes in the concentration of a number of hormones, including estradiol, progesterone, DHEAS (dehydroepiandrosterone), and androstenedione, which were found to be unaffected by any romantic feelings. In contrast, they observed changes for cortisol, FSH (follicle stimulating hormone), and testosterone. Some effects were gender-specific. For example, testosterone was found to be increased in women but reduced in men when they are in love.
If lovers swear their feelings to be ever-lasting, the hormones clearly tell a different story. Re-testing the same subjects 12-24 months later, Marazziti and Canale found that the hormonal differences had disappeared entirely, even if the relationships remained intact.
Using the same method for volunteer selection, Enzo Emanuele and his coworkers at the University of Pavia investigated whether a different class of chemical messengers, the neurotrophins, is involved in the romantic experience. They reported at the end of 2005 that the concentration of nerve growth factor (NGF) in the blood exceeds normal levels in enamored volunteers, and that it increases with the intensity of romantic feelings as measured by the PLS. Whether more NGF is needed in early stage romance because of all the new experiences that are engraved into the brain, or whether it has a second, as yet unknown function in the chemistry of love remains to be explored.
Emanuele and coworkers, too, found that after 12-24 months all the love molecules had gone, even if the relationship survived. Neither the initial intensity on the PLS nor the concentration of NGF appeared to be a suitable predictor for the fate of the relationship after that period.
Another molecular messenger of love is phenylethylamine, a neurotransmitter which is structurally related to amphetamines. “Phenylethylamine is responsible for ‘love at first sight,’” says Gabi Froböse, who co-authored the book “Cupid’s Chemistry -- the science of love and desire” with her husband Rolf Froböse. “But after the initial euphoria which may last two to three years, its effect fades.”
But, if all the chemical messengers of intensive romantic feelings disappear within two years, what is the chemical glue that keeps (at least some) couples together ?
A key molecule for the attachment phase is the hormone oxytocin, a nonapeptide that was first described as the chemical principle that induces labor and lactation, but later found a second job as the human “cuddle hormone.” It is related to the hormone vasopressin, which controls kidney function and is also involved in the attachment of the above-mentioned prairie voles.
Experiments have shown that -- depending on the species -- either or both of these hormones can make animals snuggle up. In humans, it has been shown that oxytocin production is high during female orgasm, accounting for her desire for cuddles after the event. Apart from that, and its role in childbirth, very little was known about oxytocin’s role in human physiology and psychology until very recently.
Last year, several groups reported progress in the investigation of the role of oxytocin in humans, linking the hormone to early socialization, social cognition, and trust. Michael Kosfeld and his coworkers at the University of Zurich, in particular, showed that application of oxytocin via a nasal spray made participants in a “trust game” they devised more trusting towards other human participants, but not towards a computer. This finding fits in with the expectations of the Italian researchers. “I am not surprised by the results of Kosfeld’s paper,” says Donatella Marazziti, who has just completed a study of oxytocin in romantic love but keeps the details under wraps.
Finally, another family of chemical messengers associated with love, the pheromones, is equally poorly understood in humans, as most of our knowledge derives from animals. By definition, pheromones are chemicals intended for the communication between individuals of the same species. Their use in insects is well understood to the extent that “pheromone traps” are commercially available for crop protection.
Our knowledge is much more incomplete for mammals, let alone humans. Most people’s educated guess is that pheromones secreted from some glands, e.g. with the sweat, are recognized by receptors presumably located in that very small part of our nose known as Jacobson’s organ or vomero-nasal organ (VMO, see page XXXX). However, it was only in 2002 that researchers could pin down some putative mammalian pheromone receptors in mice.10 In October 2005, the group of Hiroko Kimoto at the University of Tokyo added a surprising piece to the jigsaw. The Japanese researchers showed that a non-volatile mouse pheromone, which they called ESP-1 (exocrine-gland secreting peptide), is released from the tear glands of the male mouse and -- after face to face contact -- activates receptors in the VMO of the female.11
Again, it remains unclear whether tears of the human male have a similar effect. Indeed, there is a long-running controversy as to whether the human VMO is in fact a working part of our physiology or whether it’s an inactive relic of mammalian evolution. It now appears that the evidence is slowly giving the pro-VMO party the upper hand. To any romantically inclined chemist, it should be deeply satisfying to be able to prove that chemical messengers communicate romantic feeling between humans. After all, this is the only thing that science can offer as a real-world analogy to Cupid’s arrows.
G. Froböse and R. Froböse: Lust and love: is it more than chemistry? Cambridge, UK, RSC 2006.
Fisher, Helen: Why we love -- the nature and chemistry of romantic love. New York, Henry Holt, 2004.
K.-I. Kimura et al., Nature 2005, 438, 229.
A. Aron et al., J. Neurophysiol. 2005, 94, 327-337.
H. Fisher et al., J. Comp. Neurol. 2005, 493, 58-62.
D. Marazziti, D. Canale, Psychoneuroendocrinology 2004, 29, 931.
E. Emanuele et al., Psychoneuroendocrinology 2005, 30, 1017.
A. B. Wismer Fries et al., Proc. Natl. Acad. Sci USA
P. Kirsch et al., J. Neurosci. 2005, 25, 11489.
M. Kosfeld et al., Nature 2005, 435, 673.
H. Kimoto et al., Nature 2005, 437, 898.
What happened next
No major advance has come to my attention, but if anything does turn up, I will of course have to wait for Valentine’s Day to come round, because “seasonal” stories will get the biggest coverage in the media.
Monday, July 14, 2008
Apart from the 219th anniversary of Bastille Day, we are today also celebrating the launch of my platypuses book in the US.
You should now be able to get it from
Barnes and Noble
... now I'm running out of bookshops I know, but the gist is you should find it in every good book shop, presumably on the popular science shelf, between John Gribbin and Paul Halpern :) Now how do I get Oprah to present it on her show ???
Saturday, July 12, 2008
All together now
I have always enjoyed challenging the traditional view that humans are the “highest” life form on Earth and everything else is more or less primitive. For instance, bacteria aren’t quite as dumb as they may appear. Large numbers of them can coordinate their activities in time and space, relying on a form of chemical communication known as quorum sensing. Social behavior in bacteria? What a crazy idea …
An old but persistent myth has it that our own species Homo sapiens sapiens represents the most sophisticated life form on Earth, while bacteria are the most primitive one. Douglas Adams has famously overturned the first part of this myth, and microbiologists are now beginning to realise that bacteria are a lot more sophisticated than we mere mortals used to think. True, the few species that can be easily cultivated in the lab are often well described by the assumption of a single cell programmed to divide after a certain time as long as there is enough food around. But if you observe bacteria out in the wild, they are a lot more complex and less predictable.
By now, microbiologists estimate that the majority of the bacterial biomass is in fact not found as free-living single cells, but rather involved in some kind of higher organisation, including symbiosis with other organisms (e.g. in lichens or animal guts) and biofilms. Cyanobacteria can become part of lichens which look deceptively like higher plants, and also in layer structures which obey strict structural organization on large scales. Colonies of luminescent bacteria can send out precisely coordinated flashes of light. All these “social” activities require each individual bacterium to know of the presence of the others and to communicate with them. For this purpose, they have a chemical signalling system known as quorum sensing.
It was originally discovered in luminescent bacteria, which only light up when there are many of their friends around. In the 1970s, researchers showed that the bacteria secrete a molecular messenger, called the autoinducer, into the medium, and only produce light when they sense a threshold concentration of this molecule. For many years, biologists believed this communication to be specific to bioluminescence. It was only in the 1990s that quorum sensing turned out to be a much more general phenomenon, involved in disparate processes including synthesis of antibiotics in Erwinia carotovora, and the production of virulence factors in pathogenic bacteria.
The molecular mechanisms of quorum sensing have long remained mysterious. In 2002, two crystal structures of proteins involved in the process allowed researchers to put together at least some of the fundamental pieces of the mechanism. The group of Frederic Hughson at Princeton University (New Jersey) identified a hitherto elusive autoinducer, known as AI-2 by solving the crystal structure of its receptor which turned out to contain the AI-2 molecule. While many of the bacterial pheromones known so far are specific to one species, AI-2 appears to be widely distributed and might even serve as a communication device between different species.
The receptor in question was LuxP, a protein involved in the coordinated bioluminescence of the marine bacterium Vibrio harveyi (a harmless distant relative of the cholera germ, named after the pioneer of bioluminescence research, E.Newton Harvey). While the protein structure as such was similar to those of other binding proteins located in the periplasm (the space between cell membrane and cell wall), it was the unusual chemical structure of the autoinducer trapped inside, representing the first example of a biomolecule containing boron, which secured its place on the pages of Nature.
A few months later, the group of Andrzej Joachimiak at the Argonne National Laboratory (Argonne, Illinois) presented another crystal structure of a key protein involved in quorum sensing. Their target is the protein TraR from the plant pathogen Agrobacterium tumefaciens. This protein is related to another quorum sensor from the bioluminescence system and constitutes a direct link between pheromone recognition and the resulting change in gene expression, as it acts both as a signal receptor and as a transcription enhancer. The Argonne group managed to catch it in flagranti, with two molecules of the autoinducer and a piece of the target DNA bound to the protein dimer.
One of the most intriguing aspects of the resulting structure is that the pheromone appears to be completely encapsulated within the protein fold. In accordance with earlier biochemical work indicating that the protein acquires resistance against protease digestion when binding the small molecule, this finding suggests that the sensor “folds around” its messenger molecule. In other words, it starts out from some more loosely folded, probably monomeric conformation, and only folds into the DNA-binding dimer when it has secured its two molecules of the autoinducer. Thus, binding of the signalling molecule is an essentially irreversible switch from an inactive TraR to the active conformation.
As A.tumefaciens makes its living by invading plants and setting up colonies in structures which look like tumours (hence the name), it is rather important for the individual bacteria to know whether they are part of a successful invasion troop, or whether they are out on their own. The traR gene is switched on as soon as the bacterium senses certain plant-specific chemicals, and the individualist turns into a part of a coordinated army from then on. Deeper understanding of bacterial communication gathered from the present structural work and future research should hopefully enable us also to fight bacterial invasions of our own bodies more efficiently - seeing that we are supposedly smarter than they are.
The quorum sensing site: http://www.nottingham.ac.uk/quorum/
X. Chen et al., Nature, 2002, 415, 545.
R. Zhang et al., Nature, 2002, 417, 971.
What happened next
No bacterial communications have reached my sensors in recent years, but I am sure that a lot of interesting work continues to be performed in this field – try visiting the quorum sensing site to get an impression of what’s going on.
PS in fact there is something on the social life of bacteria in the current issue of Science magazine, which I haven't read yet, but I may end up writing something about that, too.
Friday, July 11, 2008
They sell it for $ 33 with free delivery, so get one now, and one for your auntie, one for your friend ...
Here's the fantastic blurb again, for those who haven't seen it yet:
Michael Gross has been writing about science full time for the last eight years and as a night time hobby for the previous seven. From his treasure troves, he now presents his favourite science stories from these 15 years. What are the attractions that make him revisit a topic or reread an article again and again? Often, it’s the sheer craziness of wildly unexpected findings or grotesquely oversized challenges. In other stories, there is a sexy element or a an unexpected insight into the human condition. And sometimes, when reporting new and future technologies, the author just can’t help thinking: “cooooooool!” So here are more than 60 crazy, sexy and cool science stories for you to enjoy.
Thursday, July 10, 2008
During the 10 days it was away I used my old Macintosh LC75, built 1993, which I had in daily use until autumn last year (2007), and only stopped using for reasons not related to the computer (e.g. that computers at the library no longer have a floppy drive, which I needed to transfer files written at home).
I admit that the comparison is slightly unfair, as my Mac came out of a pool of maybe a dozen similar machines at the lab, and I picked it as my personal Mac in around 1999, so at that time any computers that may have broken down after 18 months would no longer have been in the pool. So it is a "survivor" by default.
But still, 15 years vs. 18 months, that is quite remarkable. The last laptop PC I bought for myself, back in the 90s, didn't survive more than 2 years either.
Wednesday, July 09, 2008
All four seasons are here:
Tuesday, July 08, 2008
My opinion about the book is nicely summarised in the title of the review:
Right answers for wrong questions
which I think is close to the title I suggested (I may have written "wrong questions, right answers"). Given the quality of the 10 questions, which I grouped into 2 real scientific questions, 4 philosophical ones, and 4 policy questions, the book is surprisingly good, in fact.
Monday, July 07, 2008
Reise zum Ursprung der Säugetiere?
Das Schnabeltier-Genom und die Evolution.
and a column about the Bologna reform of higher education across Europe (which Brits probably haven't even noticed, as everybody else will move closer to the British system of bachelor / master):
Pisa, Bologna, Florenz ?
PS: Sorry I can't update the publications list on the website right now. back to normal service in a week or so.
PPS Oh and I've also created my very first Wikipedia entry, about the painter Alexander Calvelli. Great fun, should do that more often.
Friday, July 04, 2008
bonk: the curious coupling of sex and science
Allen Lane 2008
I have by now accumulated a nice little collection of books about the science of love and sex -- of course for serious research only. On that shelf, “bonk” is by far the most entertaining book I’ve come across. Not worrying too much about love and all the emotional baggage that we humans connect with it, Roach goes, chimp-like, straight to the hard core of the matter.
Which of course is a very tricky thing to do for somebody writing in English, the language of puritanism and all kinds of post Victorian hang-ups around human sexuality. Notwithstanding, Roach attacks the matter fearlessly and head-on, using her fine sense of humour to overcome any embarrassment she or some of her readers may be feeling.
The book is mainly about how scientists manage to survive in a field that suffers enormously from the above-mentioned hang-ups and prudishness and is therefore still the most under-developed part of human biology (remember that a large part of the clitoris was only discovered a few years ago!). One doesn’t get much of an overview of what is known about love and sex (for this, the book “Lust and love: is it more than chemistry?”, which I translated, works better, even if I say so myself), but one does get a good sense of the challenges -- resulting from nature, methodology, and from the weird attitude our society has towards the most natural of all inter-human activities -- and how the very small number of researchers in the field are facing them. As a bonus, one gets to LOL a lot.
Thursday, July 03, 2008
The five women populating his love life look interesting, I guess I would write kafkaesque novels too, if I were torn between these ...
Wednesday, July 02, 2008
Read my story here.
Tuesday, July 01, 2008
The most interesting new example is Lymphotactin, which can form a monomer with alpha/beta structure, or a dimer with no alpha helical content at all. This is published in PNAS, 105, 5057, 2008.
Way back when I have also written about proteins switching between alpha and beta structure, mainly in the context of amyloid formation by alpha helical proteins:
Groß M (2000): Current Protein and Peptide Science 1, 339-347
Proteins that convert from alpha helix to beta sheet: Implications for folding and disease
But as I never got round to learning Greek, I didn't think of calling them "metamorphic proteins" as the Science piece now does. Damn. Another missed opportunity ...