Well…erm…

OK, I will have shocked you nicely and perhaps intrigued you almost as much with the blog title. Indeed, the title is not altogether different from Dr Petra Boynton’s title of her Science Oxford Live talk that she gave on 7th October, and I suspect it intrigued just as many people. (As an occasional volunteer at Science Oxford Live, I had said I would be available on that date, and was amused to receive an e-mail reply saying that “I’ve put you down for The Brain on 30th September, and Sex on 7th October”!)

Dr Petra Boynton describes herself as a “Sex educator, Agony Aunt, Academic” on her website, and goes on to say that she is involved in academic research (focussed on sex and relationships in themselves but also on how policy, modernisation and new technologies may affect sexual education and sexual health in various countries), but also in teaching doctors, nurses and other health professionals about sex education. And she certainly comes across as an engaging speaker – but then I guess you’d have to be, with that sort of field of research, wouldn’t you?

Dr Boynton was one of the speakers asked to come back ‘by popular demand’ to Science Oxford Live as part of its 5th birthday celebrations and she certainly proved why she had been so popular the first time round. Her very engaging style contrasted greatly with the most simplistic presentation I had ever seen, consisting only of a set of questions, one per slide. “Those that were asked by previous audiences at talks, in e-mails and past discussions”, she told us, suggesting that they would give a good framework for the talk to come.

“What is sex?” the as-yet shy audience were asked. There were some suggestions about the “special cuddle” and the thing that happens “when a man loves a woman”, but Dr Boynton was having none of that, putting up a list of all the things that sex might represent. For those of you intrigued, these may include anything from masturbation (alone or with a partner), to vaginal penetration, and through more obscure practices such as BDSM (the audience appeared pleased that one of us had the courage to ask what this acronym means!) to phone/text/e-mail sex (the interesting question being, do you have to be in physical contact with someone to be having sex?). In fact, rather interestingly, Dr Boynton pointed out that such lack of clarity can often confuse some sex surveys, because people don’t always agree on what sex actually means!

“Why do people have sex?”, she continued. It appeared that the audience was slightly more conservative with their answers (“because it feels good” or “to have children”) than some of the undergraduate students that had previously answered a survey carried out to find out the answer to this question (amongst others), with their more bizarre answers ranging from “wanting to feel closer to God”, “being bored” and simply “feeling like it”. On a more serious note, Dr Boynton explained that sometimes sexual education for teenagers concentrates far too much on the sexual health itself rather than trying to encourage young people to find things to do that they enjoy, and as a result not be subject to the boredom that often leads them to have sex simply because they’re bored (a fact I didn’t know before, but apparently the prevalence of teenage pregnancies goes up in the summer school holiday months).

“How do you research sex?”, you might have wondered. Well, so did many other people before you and Petra duly explained that, to many people’s disappointment, much of this work is carried out through surveys and by analysing study subjects’ “sex diaries”. And although experiments in the lab, where the subjects are wired up to measure all sorts of bodily signals (eg. brain activity) whilst having sex, are carried out, these are much rarer because of the unnaturalness of the whole set-up (apparently it takes a couple quite a lot of practice to be able to have sex in a laboratory whilst managing to be wired up to several different machines…).

In that vein, Dr Boynton’s talk continued, covering questions ranging from whether female ejaculate exists and what it is, what the correct erection etiquette during dancing is (what should you do – as either the bloke or the girl – if a man and a woman dance together, with the guy getting excited and this being noticed?), how often one should have sex (apparently, there isn’t a “should” about this, and the answer is very individual), all the way to whether she used to scare men away when dating when she told them what her job was. And although shy at the beginning, as a result of Dr Boynton’s flamboyant and open attitude and approach, the audience got more and more drawn in to discussing a topic that is often seen as a taboo even though it shouldn’t be (nevertheless, I am still debating how best to cover the talk in this blog without offending anyone!). By the end of the talk, people were happy to ask questions (even though there had been a box provided before the talk for anonymous questions, if they existed), and the talk provided a partly light-hearted but partly serious discussion on a topic that almost everyone knows something about.

You can read more about Dr Petra Boynton on http://www.drpetra.co.uk/ and you can watch her talk via the webcasting section of the Science Oxford Live website http://www.scienceoxfordlive.com/watch-us-archive/science-oxford-live-s-greatest-hits-sex-webcast

For the first time, a woman has given birth to two children after her fertility was restored using transplants of ovarian tissue that had been removed and frozen during her cancer treatment and then restored once she was cured.

Following her ovarian transplant, Mrs Stinne Holm Bergholdt gave birth to a girl in February 2007 after receiving fertility treatment to help her become pregnant. But then, in 2008, she discovered she had conceived a second child naturally and gave birth to another girl in September 2008.

Her doctor, Professor Claus Yding Andersen, reports her case in Europe’s leading reproductive medicine journal Human Reproduction. “This is the first time in the world that a woman has had two children from separate pregnancies as a result of transplanting frozen/thawed ovarian tissue,” he said. “These results support cryopreservation of ovarian tissue as a valid method of fertility preservation and should encourage the development of this technique as a clinical procedure for girls and young women facing treatment that could damage their ovaries.”

So far, nine children have been born worldwide as a result of transplanting frozen/thawed ovarian tissue (including Mrs Bergholdt’s two). Three have been born in Denmark after treatment carried out by Prof Andersen, who is Professor of Human Reproductive Physiology at the University Hospital of Copenhagen (Denmark). “Mrs Bergholdt gave birth to the first and the third babies and another woman delivered the second baby. This is the highest number of children born from one ovarian cryopreservation programme worldwide. It is interesting to note that nearly all of the nine pregnancies have occurred in Europe and so Europe is in the absolute forefront with this technology,” he said.

Mrs Bergholdt, from Odense, Denmark, who is also one of the authors of the paper, was diagnosed with Ewing’s sarcoma when she was 27 in 2004. Before she began chemotherapy, part of her right ovary was removed and frozen (her left ovary had been removed some years before because of a dermoid cyst, a type of benign ovarian tumour). Her cancer treatment was successful but, as expected, the drugs caused a menopause. In December 2005 six thin strips of ovarian tissue were transplanted back on to what remained of her right ovary. Her ovary began to function normally again and, after mild ovarian stimulation, she became pregnant and gave birth to her first daughter, Aviaja, in February 2007.

She breast-fed Aviaja until October 2007 and in January 2008 she returned to Prof Andersen’s fertility clinic for additional IVF treatment so that she could conceive again. However, a pregnancy test revealed she was already pregnant naturally, and in September she gave birth to a healthy girl, Lucca.

Prof Andersen said: “This showed that the original transplanted ovarian strips had continued to work for more than four years and that Mrs Bergholdt still has the capacity to conceive and give birth to healthy children. It is an amazing fact that these ovarian strips have been working for so long and it provides information on how powerful this technique can be. She continues to have natural menstrual cycles and, at present, is using pregnancy-preventing measures to avoid becoming pregnant again.
“She has seven more ovarian strips in the liquid nitrogen tank and may return, if she wishes so, to have more tissue transplanted in order to maintain her ovarian function once the current strips stop working. So, in total, by having around one third of an ovary removed she has the possibility of maintaining her ovarian function for many years. As long as the tissue remains properly stored in liquid nitrogen, it could remain functional for as long as 40 years. However, we do not know this for certain at present.”

Mrs Bergholdt, who is now 32, said: “When I found out I was pregnant for the first time I was of course very happy and excited – but also very afraid and sceptical since I found it very hard to believe that my body was really working again. My cancer had been diagnosed very late because the doctors didn’t take my complaints seriously at that time and kept on telling me that nothing was wrong, so I also wondered if it was really true that I was completely recovered from it. But eventually I started to believe that the pregnancy was really happening and began to enjoy every aspect of it.

“The second time it was quite a surprise to find out I was pregnant since we hadn’t been working on it – we thought we needed assistance like the first time. We had an appointment at the fertility outpatient clinic to talk about the possibility of a second baby, but it turned out that I was already pregnant – naturally. It was a very nice surprise to find out that my body was now functioning normally and that we were having a baby without having to go through the fertility treatment. It was indeed a miracle!”

Mrs Bergholdt said she and her husband had not decided yet whether they wanted more children. “The girls are still so small and need a lot of attention, but maybe in a couple of years we might think about it again.”

Why do we find some people more attractive than others? What makes men look masculine and women look feminine? What can these facial distinctions tell us about our evolution? By drawing on examples from humans, apes and other primates, Dr Eleanor Weston discusses the differences between male and female faces, and the evolution of attractiveness.

Further Information
Dr Eleanor Weston is a mammalian palaeontologist based in the newly opened Darwin Centre at the Natural History Museum, London.
www.eleanorweston.net/sexual_dimorphism.html
www.nhm.ac.uk/visit-us/darwin-centre-visitors/marmontcentre/index.html

In adult fe­male mice, switch­ing off one gene seems to start turn­ing the ovaries in­to tes­ti­cles and trig­gers the pro­duct­ion of male hor­mones at nor­mal male levels, sci­en­tists say.

The cu­ri­ous find­ings have led two re­search­ers to re­mark in a pub­lished pa­per that, bi­o­log­ic­ally speak­ing, fe­males may be en­gaged in a life­long “bat­tle to sup­press their in­ner ma­le.”

Both pa­pers ap­pear in the Dec. 11 is­sue of the re­search jour­nal Cell.

The new results echo a pre­vious study that found that fe­male ovar­ian tissues in mice start to con­vert to male-like tis­sues in the ab­sence of sig­nals from es­tro­gen, a fe­male sex hor­mone. That stu­dy ap­peared in the Dec. 17, 1999 is­sue of the jour­nal Science.

In the newer re­search, N. Hen­ri­ette Uh­len­haut of the Eu­ro­pe­an Mo­lec­u­lar Bi­ol­o­gy Lab­o­r­a­to­ry in Hei­del­berg, Ger­ma­ny, and col­leagues were stu­dy­ing genes that dur­ing de­vel­op­ment are re­spon­si­ble for con­vert­ing glands called go­nads in­to ei­ther ovaries or tes­ti­cles, de­pend­ing on the sex.

Ovaries produce eggs, the fe­male sex cells, while tes­ti­cles produce sperm.

Uh­len­haut and col­leagues ge­net­ic­ally en­gi­neered mice in which the ac­ti­vity of a called Fox2L could be chem­ic­ally sup­pressed in the ovaries.

Fox2L, in turn, is a reg­u­la­tor gene that in­flu­ences the lev­el of ac­ti­vity of an ar­ray of oth­er genes. Among oth­er things, it keeps in check genes that tend to pro­mote tes­ti­cle de­vel­op­ment, ac­cord­ing to Uh­len­haut’s group.

Switch­ing off Fox2L had the im­me­di­ate ef­fect of in­creas­ing the lev­el of ac­ti­vity of some of these “tes­tis-specific” genes, the sci­en­tists re­ported. Crit­i­cal among these, they iden­ti­fied one called Sox9.

Con­com­i­tant with the boost in Sox9 ac­ti­vity was a “re­pro­gram­ming” of cer­tain ovar­i­an cell lin­eages in­to what ap­peared to be tes­tis cell lin­eages, Uh­len­haut and col­leagues found. Mean­while, the mod­i­fied ovaries be­gan pro­duc­ing nor­mal ma­le-like lev­els of the hor­mone tes­tos­ter­one.

“Our re­sults show that main­te­nance of the ovar­i­an phe­no­type [form] is an ac­tive pro­cess through­out life,” the sci­en­tists wrote.

It’s un­clear wheth­er the find­ings would trans­late to hu­mans, but be­cause mice share over 90 per­cent of their genes with hu­mans, it very of­ten hap­pens that mouse pro­cesses have par­al­lels in hu­mans.

It would seem “tes­tic­u­lar de­vel­op­ment is ac­tively re­pressed through­out the life of fe­ma­les,” added An­drew Sin­clair and Craig Smith of the Mur­doch Chil­dren’s Re­search In­sti­tute in Mel­bourne, Aus­tral­ia, in a pa­per pub­lished in the same is­sue of Cell. Sin­clair and Smith—the re­search­ers who in their ar­ti­cle metaphoric­ally sug­gested an “in­ner ma­le” may lurk with­in all fe­ma­les—also not­ed the find­ings go against “con­ven­tional wis­dom” that the ova­ry and tes­tis are “ter­mi­nally dif­fer­en­ti­ated,” or ir­re­versibly de­vel­oped to their ma­ture state.

Viagra affects growth of the male sex organ of plants, by intensifying the effect of nitric oxide during plant fertilization. This discovery, made by the Plant Development team at the Instituto Gulbenkian de Ciência(IGC), in Portugal, will be published in Development, in June. The study, led by José Feijó, takes a step further in understanding fertilization in plants, a complex process but an absolutely essential one for the survival and evolution of species.

Pollen grains, which contain the plants’ male gametes (sperm cells), are carried from the male organ of the flower (the stamen) to the female organ (the pistil). Here the pollen germinates and grows a pollen tube, which extends and is guided to the ovary, where it releases the sperm. The sperm fuse with the egg cells, giving rise to an embryo, part of the seed. For many years now, scientists have been trying to unravel the mechanisms that guide the pollen tube along the long route to reach the ovary.

The Plant Development group of the IGC, now shows, for the first time, that nitric oxide (NO), a well-known gas that animal cells use as a hormone, influences the speed and direction of growth of lily pollen tubes. Upon encountering a point source of NO, lily pollen tubes slow down, almost stop, make a 90 degree turn, and start growing again.

The IGC researchers bathed the pollen tubes in several enzyme inhibitors to identify the messenger molecule, inside the cell, that mediates the response to NO, sensed outside the cell. Of the inhibitors tested, only Viagra intensified the effect of NO, to the point where the pollen tubes made a 180 degree turn. Viagra is known to cause build up of cyclic GMP (cGMP) inside a cell; the researchers thus conclude that NO acts on the pollen tubes via this small messenger molecule.

These findings underscore how fundamental biological processes, such as fertilization, are conserved in their basic mechanisms, from plants to animals: Viagra, a drug that affects signalling inside the cell, has similar effects on male sex organs in animals and in plants.

There is general agreement amongst plant scientists that the pollen tube is guided by mechanical and chemical signals. The new findings of the IGC researchers take the search for a unifying theory of pollen tube guidance a step further. The scientists suggest that, in the plant, NO is released by the female organ and acts as a signpost to make the pollen tube change direction at the right place along the route.

According to José Feijó, there is still some way to go to fully understand how NO acts in plants. This gas is full of surprises, both in animals and in plants. In animals, amongst many other functions, NO controls blood pressure and acts as a messenger between cells of the nervous system. Nitroglycerine alleviates the symptoms of cardiac arrest because it causes cells to release NO.

Article Credit: AlphaGalileo

Experimental mouse breeding in a near-zero-gravity space simulation suggests making babies is best left to Earthlings.

According to Japanese biologists, defects in their microgravity embryos suggest that “fertilization can occur normally” in space, but standard Earth gravity may be needed for embryo development.

The experiment, published Tuesday in Public Library of Science ONE, is the latest addition to a surprisingly large body of literature on how the space environment affects the cellular basics of reproduction.

Among the animals that have been bred in space are frogs, salamanders, sea urchins — who didn’t do so well — and fish. (Birds and bees are, understandably if unfortunately, not on the list.)

Rather less research, however, has been done on mammalian reproduction in space, and there’s reason to think the potential effects of low gravity would be pronounced in mammals, whose embryonic development is more complicated and sensitive than other animals.

To test these effects, the researchers artificially fertilized mouse eggs with sperm that had been stored inside a three-dimensional clinostat, a machine that mimics weightlessness by rotating objects in such a way that the effects of gravity are spread in every direction.

Fertilization took place normally, suggesting that microgravity hadn’t harmed the sperm. But as the embryos continued to develop inside the clinostat, many developed problems. Their cells had trouble dividing and maturing.

Some were ultimately implanted in female mice and survived to a healthy birth, but at lower numbers than a regular-gravity control group. Part of the difference could be the result of performing tricky procedures on sensitive cells, but the researchers suspect they also reflect the affect of a low-gravity environment on cellular processes that evolved for Earth-specific physics.

“Sustaining life beyond Earth either on space stations or on other planets will require a clear understanding of how the space environment affects key phases of mammalian reproduction,” write the researchers.

Article Credit: Wired Science

Assisted reproductive technology (ART) is responsible for an estimated 219,000 to 246,000 babies born each year worldwide according to an international study. The study also finds that the number of ART procedures is growing steadily: in just two years (from 2000 to 2002) ART activity increased by more than 25%.

The study, which is published online today (Thursday 28 May) in Europe’s leading reproductive medicine journal Human Reproduction [1], gives figures and estimates for the year 2002, the most recent year for which world figures are available. A total of 1563 clinics in 53 countries provided data for the report, but data were missing from several other countries, mostly in Asia, Africa, Oceania and the West Indies. The authors estimated that these missing countries probably performed between 10-20% of ART procedures, and they took this into account when they calculated the total number of ART babies born worldwide.

Professor Jacques de Mouzon, a specialist in public health at INSERM (Paris, France), led the International Committee for Monitoring Assisted Reproductive Technology (ICMART) that compiled the report. He said: “This is the eighth world report on ART produced by ICMART since 1989, and is useful because, even if it is imperfect, it gives data that can inform debate and decision-making on issues such as availability and the benefits and risks of this important medical practice. It allows us to make comparisons between countries and regions, and to analyse trends by comparing with previous reports.

“There are several important points to highlight. There has been a constant increase in ART activity: it increased by more than 25% in the two years since the previous report for the year 2000. This is due not only to an increase in the number of countries participating in this report but also to an increase in ART activity in most individual countries.

“However, there are wide variations between countries in the availability and quality of ART. There are several reasons for this, such as fertility rates, women’s age, insurance cover, the national economy, but the most important is certainly inequality in access to healthcare and ART. In Western Europe it is easier for people to access good healthcare, and funding for ART tends to be more generous than in developing countries. This raises the question of developing so called ‘low cost’ ART in low-income countries; it would probably mean lower success rates (the problem would be to define what rates would be acceptable), but greater access to treatment. In addition, treatment is usually more aggressive in developing countries and in all countries where ART is expensive for patients, leading to the consequent problems of multiple births, ovarian hyperstimulation syndrome and the need for foetal reductions.”

Availability of ART varied from two cycles per million inhabitants (Ecuador) to 3688 per million in Israel.

Other key findings from the study include:
1. A large increase in the use of ICSI (intracytoplasmic sperm injection) as opposed to conventional IVF (in vitro fertilisation) worldwide. Since 2000 it increased from 54% to 61% in North America, 46% to 54% in Europe, and in 2002 it had reached 76% in Latin America and more than 92% in the Middle East.
2. Pregnancy and delivery rates have increased for both fresh and frozen embryo cycles despite a decrease in the number of embryos transferred. More than 601,250 ART cycles worldwide resulted in delivery rates after IVF, ICSI and frozen embryo transfer (FET) of 22%, 21% and 15% respectively per aspiration (attempt at egg retrieval). This compares with delivery rates after IVF, ICSI and FET in 2000 of nearly 19%, 20% and 12% respectively.
3. When cycles using fresh embryos were combined with frozen embryo cycles, the cumulative delivery rate per aspiration was 26%.
4. Cumulative delivery rates per aspiration varied among countries, ranging from 14% to 39%. While Tunisia and Libya reported the highest rates at 39%, this represented only a few fertility centres in each country. Therefore, the USA, where reports cover almost all fertility centres in the country, had the highest rate at 37.5%.
5. The transfer of multiple embryos has decreased, leading to a small decline in multiple births. The percentage of four or more embryo transfers decreased from 15.4% in 2000 to 13.7% in 2002. The proportion of twin and triplet pregnancies decreased from 26.5% to 25.7%, and from 2.9% to 2.5% respectively.
6. There has been a 47% increase in the proportion of FET cycles, which is due mainly to the decrease in the number of embryos transferred at one time, with any left over being frozen for future attempts.

Prof de Mouzon said: “It is difficult to explain the reasons behind the increase in ICSI as we have no reason to believe there has been a similar increase in the rise in male infertility, and ICSI has not been demonstrated to improve treatment results for infertility that is not caused by infertile men. It could be because more infertile men are agreeing to seek treatment, that the diagnosis of male infertility is improving, that male infertility per se is increasing (due to exposure to sperm-damaging compounds in the environment), that fertility teams turn to ICSI more rapidly when conventional IVF fails, or that ICSI is still viewed as more efficient, even in the absence of scientific proof, which may be the major factor in Latin America and the Middle East. I suspect the overall explanation is probably a mixture of several of these factors.”

The increased use of frozen embryo cycles was very good news because it improved cumulative pregnancy and delivery rates and helped reduce the number of multiple embryo transfers and multiple births, he said.

“Our report shows that delivery rates per aspiration increased in 2002 even though the average number of embryos transferred was reduced. For example, in Australia where a mean average of 1.8 embryos were transferred, the delivery rate per aspiration was 19.5% for fresh cycles and 29.4% for fresh and frozen cycles together. This should encourage countries to implement embryo transfer policies that reduce the risk of multiple births,” said Prof de Mouzon.

The authors warn that variation in data quality, in addition to differences in practices, legislation, guidelines, culture and religion, means that comparisons between countries “must be done with caution”.

Contact (media enquiries only):
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Email: wordmason@mac.com

Alligators display the same loyalty to their mating partners as birds reveals a study published today in Molecular Ecology. The ten-year-study by scientists from the Savannah River Ecology Laboratory reveals that up to 70% of females chose to remain with their partner, often for many years.

The team, led by Drs. Travis Glenn, Ruth Elsey, Tracey Tuberville and Stacey Lance, spent a decade examining the mating system of alligators living in the Louisiana Department of Wildlife and Fisheries’ Rockefeller Wildlife Refuge (RWR) in Louisiana. Once they had successfully re-trapped a female they recognized the potential to examine individual behaviour over multiple mating seasons and determine if mate fidelity or pair bonding occurs.

“Given how incredibly open and dense the alligator population is at RWR we didn’t expect to find fidelity,” said Lance. “To actually find that 70% of our re-trapped females showed mate fidelity was really incredible. I don’t think any of us expected that the same pair of alligators that bred together in 1997 would still be breeding together in 2005 and may still be producing nests together to this day.”

This new discovery gives a new insight into the complex mating system of the alligator. Parental care is typically lacking in most reptiles, but not crocodilians who display parental care though nurturing young and defending the nest. In 2001 multiple paternity was discovered as the alligator mating system, yet it remains unknown as to how this benefits the species

However, while the females at RWR move freely through male territories, leading to high mate encounter rates, this study reveals that many alligators choose to mate with the same partner over many mating seasons. This amounts to the first evidence for partial mate fidelity in any crocodilian species and reveals a similarity in mating patterns between alligators and bird species.

Crocodilians are the sole surviving reptilian archosaurs, a group of ancient reptiles that includes dinosaurs and gave rise to birds. It is this evolutionary relationship to birds which means crocodilians are in a unique phylogenetic position to provide information about the ancestral mating systems of both birds and many dinosaurs.

“In this study, by combining molecular techniques with field studies we were able to figure something out about a species that we never would have known otherwise,” concludes Lance. “Hopefully future studies will also lead to some unexpected and equally fascinating results.”

Article Credit: AlphaGalileo

The secret to immortality may be sex — cells, that is.
The cells of especially long-lived roundworms run some of the same genetic programs found in sperm and egg cells. Known as germline cells, they can replicate indefinitely without wearing down, and have fascinated researchers seeking lessons in their longevity.

Other, so-called somatic cells rapidly accumulate genetic and mechanical damage, and divide roughly 50 times before dying.

Exactly why germline cells live so long isn’t completely understood. They do possess unusually large telomeres — protein caps on the ends of chromosomes that prevent those genetic spools from unraveling. They also possess mutations in genes linked to fighting off pathogens and repairing toxin damage.

In a study described Sunday in Nature, researchers compared gene expression in germline cells with somatic cells taken from roundworms engineered to live several times longer than normal. The profiles matched. When long-lived and standard roundworms were exposed to pollutants, cells from the former escaped relatively unscathed. And when the researchers turned those typically-germline genes off, the worms’ lifespans returned to normal.

Whether the same mechanisms work in humans remains to be seen, but the prospect is tantalizing.

“Given that protection of the germ line is an evolutionarily shared trait across species, it will be interesting to investigate whether this is a broadly conserved mechanism of modulating lifespan,” wrote the researchers.

If so, then those mutations could be used in therapies that “assist in cellular repair and possibly regeneration,” they wrote.

Article Credit: Wired Science

Observing the mechanisms of evolution in order to understand how a species adapts to another under different ecological conditions was the goal of researchers at the Laboratoire Écologie et Évolution at CNRS, Université Pierre et Marie Curie and the École Normale Supérieure. They studied two bacteria – a predator and a prey – over 300 generations in a controlled environment. For the first time, these scientists were able to demonstrate that the coevolutionary process is dependent on ecological conditions. Indeed, under certain conditions, the prey becomes resistant to the predator, which itself evolves so that it can attack this new prey. In addition, the scientists issued a warning against the previously envisaged use of this predator (Bdellovibrio bacteriovorus) as a “living antibiotic” because, like other antibiotics, this could lead to the selection of resistant pathogenic bacteria.

Since publication of the Origin of Species by Charles Darwin 150 years ago, it has been known that one of the dynamics of evolution is natural selection. Its results depend on environmental conditions and interactions between the species present (competition, predation, parasitism, cooperation). Some twenty years ago, a new field of research – experimental evolution – started to develop, and it has enabled scientists to better understand the mechanisms underlying evolution. For example, one idea was to cultivate populations of bacteria under well-controlled conditions over a large number of generations. These populations are made up of numerous individuals that were initially identical from the genetic point of view. And because the turnover of generations was very rapid, just a few months were sufficient to observe the emergence of new mutants, constituting a source of genetically-different lines. Instead of reconstituting the past, the scientists thus became eye-witnesses to the appearance of new species.

Scientists in the Laboratoire Écologie et Évolution have used this type of experiment to understand how the environment influences the evolution of a pair of bacteria. One was the predator, Bdellovibrio bacteriovorus, and the other the prey, Pseudomonas fluorescens. The predator penetrated the prey and killed it by consuming it from the inside. This predator is a relatively common bacterium, one which British researchers have suggested could be used as a “living antibiotic”. As for the prey, it benefits from a considerable capacity for adaptation: when cultured in a bottle of liquid medium (not agitated), it gave rise to two new forms (or species), each occupying an ecological niche: the WS (Wrinkly Spreader morph) formed a biofilm on the surface of the nutrient medium while the FS (Fuzzy Spreader morph) lived at the bottom of the bottle where low oxygen levels were present. The SM (ancestral smooth morph), the initial form, occupied the liquid phase of the oxygen-rich nutrient medium. Each species formed colonies with a different appearance, so that population diversification could be monitored.

During their experiment, the researchers worked on 36 populations of P. fluorescens, cultured in a liquid medium and sealed within 36 constantly-agitated bottles. They introduced the predator into half of these bottles. At regular intervals (2, 3 or 4 days), a fraction of each population (1% or 0.1%) was collected and inoculated into a new bottle filled with fresh culture medium. These transfers simulated an environmental disturbance and could be compared with a hurricane sweeping through a forest, flattening large trees but allowing other undergrowth species to develop. By varying the frequency and intensity of disturbances, some species were privileged over others, thus ensuring either the maintenance of biodiversity or, on the contrary, the proliferation of certain species. During the experiments, the frequency and intensity of transfers was varied, so that the researchers were able to simulate six different environmental conditions. Thus 20 successive transfers (corresponding to 300 generations) were performed, during which the predators and prey were preserved by freezing, making it possible to test the efficiency of predators on ancestral prey after evolution, or vice versa. By “manipulating” time in this way, the scientists were able to follow evolutions in predator efficiency and prey resistance.

At the end of the experiments, only the SM prey were present in predator-free bottles; no new species had appeared. In the other bottles, predator presence caused the natural selection of predator-resistant prey: the prey had thus evolved. The appearance of several types of resistant preys was observed, taking the SM, FS and WS forms. WS morphs adhered to the walls, were difficult to transfer and ultimately disappeared from the experiment. SM morphs grew more rapidly than FS, but were less predator-resistant. Depending on the conditions of transfer, one or the other was selected. The predator also evolved. It was able to adapt to FS resistant prey, but not to SM resistant prey. What makes prey resistant or predators capable of attacking them again remains poorly understood. Sequencing the genome of these bacteria will probably throw light on the underlying mechanisms. Whatever the case, these scientists showed for the first time that the coevolution of prey and predator is not systematic, but depends on the type of resistance displayed by the prey, which itself is selected as a function of ecological conditions. In the end, it is the environment that determines whether coevolution will occur, or not.

In addition, rather than using an antibiotic compound, two British researchers proposed a few years ago that B. bacteriovorus could be used as a predator to kill bacteria responsible for human diseases. They thought that no bacillus (a group of bacteria to which the prey, P. fluorescens, belongs) could develop resistance to this predator. These recent experiments have demonstrated the contrary. In the light of these findings, use of a bacterial predator as a living antibiotic could cause the selection of bacterial strains resistant to this predator, so that there would not necessarily be any further advantages to be gained over standard, chemical antibiotic therapy.

Article Credit: AlphaGalileo

Tributyltin (TBT) paints, used to prevent sea vessels becoming encrusted with barnacles and other marine life, causes the female dog-whelk to develop a penis and other male sex organs—a phenomenon known as imposex.
The male organs block the egg-laying tube or oviduct, causing a build-up of eggs, a potentially fatal situation that results in a rapid decline of dog-whelk populations once reproducing females are lost.

Scientists have now discovered that ten years after the ban of TBT antifouling paints on small craft, populations of dog-whelks around some parts of the Isle of Wight coast have not yet recovered. The findings will be presented at the Solent Science Conference tomorrow (21 – 22 September) at the Southampton Oceanography Centre. ‘In 1987, a survey around the Isle of Wight revealed that while still common on the south coast, dog-whelk populations on the Solent shores had become extinct or reached dangerously low levels. The degree of imposex was higher in populations closer to the Solent. Exposure of TBT at one nanogram per litre—that’s around one teaspoonful in a swimming pool—can initiate imposex,’ explains Roger Herbert of the Isle of Wight-based Medina Valley Centre. Later that year, TBT paints were banned for use on craft under 25 metres in length.

Ten years on, dog-whelk populations around the Isle of Wight have been re-surveyed. ‘We have found evidence of a rapid recovery in some populations but a decline in others. Imposex levels at Bembridge have fallen dramatically with a corresponding rise in dog-whelk populations. But at locations on the south coast, imposex levels are dropping surprisingly slowly-populations at Ventnor are actually decreasing,’ says University of Southampton’s Simon Bray.

The researchers hope to carry out more studies to help explain these differences. ‘Dog-whelks are an important indicator of the extent of TBT pollution and provide evidence of contamination at sites which have not been chemically sampled. Further research needs to be carried out to fully clarify the long-term effect of TBT on the Solent’s marine life,’ concludes Roger Herbert.

Article Credit: AlphaGalileo

A group of organisms that has never had sex in over 40 million years of existence has nevertheless managed to evolve into distinct species, says new research published today. The study challenges the assumption that sex is necessary for organisms to diversify and provides scientists with new insight into why species evolve in the first place.

The research, published in PLoS Biology, focuses on the study of bdelloid rotifers, microscopic aquatic animals that live in watery or occasionally wet habitats including ponds, rivers, soils, and on mosses and lichens. These tiny asexual creatures multiply by producing eggs that are genetic clones of the mother – there are no males. Fossil records and molecular data show that bdelloid rotifers have been around for over 40 million years without sexually reproducing, and yet this new study has shown that they have evolved into distinct species.

Using a combination of DNA sequencing and jaw measurements taken using a scanning electron microscope, the research team examined bdelloid rotifers living in different aquatic environments across the UK, Italy and other parts of the world. They found genetic and jaw-shape evidence that the rotifers had evolved into distinct species by adapting to differences in their environment.

Dr Tim Barraclough from Imperial College London’s Division of Biology explained: “We found evidence that different populations of these creatures have diverged into distinct species, not just because they become isolated in different places, but because of the differing selection pressures in different environments.

“One remarkable example is of two species living in close proximity on the body of another animal, a water louse. One lives around its legs, the other on its chest, yet they have diverged in body size and jaw shape to occupy these distinct ecological niches. Our results show that, over millions of years, natural selection has caused divergence into distinct entities equivalent to the species found in sexual organisms.”

Previously, many scientists had thought that sexual reproduction was necessary for speciation because of the importance of interbreeding in explaining speciation in sexual organisms. Asexual creatures like the bdelloid rotifers were known not to be all identical, but it had been argued that the differences might arise solely through the chance build-up of random mutations that occur in the ‘cloning’ process when a new rotifer is born. The new study proves that these differences are not random and are the result of so-called ‘divergent selection’, a process well known to cause the origin of species in sexual organisms.

Dr Barraclough adds: “These really are amazing creatures, whose very existence calls into question scientific understanding, because it is generally thought that asexual creatures die out quickly, but these have been around for millions of years.

“Our proof that natural selection has driven their divergence into distinct species is another example of these miniscule creatures surprising scientists – and their ability to survive and adapt to change certainly raises interesting questions about our understanding of evolutionary processes.”

Article Credit: AlphaGalileo

How do we choose our mates? For quite some time now, scientists suspect that it is not for looks or fashion, neither for love or sympathy. It may be the genes that determine our preference for certain males or females. A new study provides support for this idea by looking at lemurs in Madagaskar. Female fat-tailed dwarf lemurs (Cheirogaleus medius) live in life-long pairs, yet notoriously cheat on their partners to improve the genetic fitness of their offspring. Scientists at the Leibniz Institute for Zoo and Wildlife Research in Berlin published the study in the journal Evolutionary Ecology (DOI 10.1007/s10682-007-9186-4).

The team headed by Prof. Simone Sommer looked for possible genetic benefits in the obligate pair-living fat-tailed dwarf lemur which maintains life-long pair bonds but has an extremely high rate of extra-pair paternity. Possible mechanisms of female mate choice were investigated by analyzing overall genetic variability as well as a marker of adaptive significance (major histocompatibility complex, MHC-DRB exon 2). MHC-genes determine not only the individual’s immune response but also the individual’s body odour. This holds true for animals as well as for humans.

The study indicated that females preferred males both as social and as genetic fathers for their offspring if they have a higher number of MHC-alleles and MHC-supertypes, a lower overlap with the female’s MHC-supertypes as well as a higher genome-wide heterozygosity than randomly assigned males. This means that females looked for the most genetically different males preferably with a “healthy” set of genes. Mutual relatedness had no influence on mate choice.

Interestingly, females were most likely to cheat on their social partner if he had a higher overlap with the female’s MHC supertype. Extra-pair mates were chosen mostly for their genetic difference, thus maximising the genetic complementarity of sires to the females.

Article Credit: AlphaGalileo

Researchers from St. Petersburg have ascertained that formation of a child’s sex depends, among other things, on the geomagnetic field status at the time of conception.

Who will be born – a boy or a girl? The answer to this question that worries all parents is determined by a lot of conditions, including external ones. The scientists of the Central Scientific-Research Institute of Radiology and Nuclear Medicine, Ministry of Health Care of the Russian Federation (St. Petersburg) and the St. Petersburg branch of Institute of Terrestrial Magnetism, Ionosphere and Radiopropagation, Russian Academy of Sciences (IZMIRAN), have ascertained that the sex of a child depends, among other things, on the level of disturbances of geomagnetic field status at the time of conception.

The researchers have retrospectively analyzed the connection between more than 600 randomly chosen supposed conception instants and the geomagnetic field status within the 1914-1979 timeframe. These instants were mainly inhabitants of St. Petersburg and the St. Petersburg Region. As the exact date of conception is normally unknown, therefore the researchers subtracted 280 days from the date of the child’s birth and determined the geomagnetic field status on that day and on the dates of nearest extremums before and after the supposed conception.

Regardless of the fact that the frequency of the boys’ and girls’ births was on the whole approximately equal within the period under review, some interesting regularities were still discovered. It has turned out that in case of lowering intensity of magnetic field oscillation at the point of conception, boys were borns more frequently (approximately 16 boys per 10 girls), but in case of increasing its intensity – girls were born more frequently (approximately 15 girls per 10 boys).

Can science explain this regularity? The researchers suppose that the discovered dependence is connected with the roles which are assigned by evolution to the male and female sex: the female role is stabilization, the male one – lability, search. That means that in unfavorable environment (in this case – increased level of magnetic field distortion) preconditions for girls’ birth occur in gametal cells, and vice versa, in favorable environment (decreased level of distortion), boys are born.

Such preconditions appearance mechanism is yet unclear. However, the researchers assume that it is connected with the presence of free-radical particles in the cells, fluctuations in ultra-low magnetic fields intensity being able to influence these particles’ recombination processes, and also to affect decay of some types of blood leucocytes, for example, neutrophils, which significantly decrease in number during disturbed geomagnetic activity periods.

Article Credit: AlphaGalileo

Hens solicit sex in the morning to avoid sexual harassment in male-dominated groups of chickens, shown in a new study by Hanne Løvlie of Stockholm University, Sweden, and Dr Tommaso Pizzari of the University of Oxford, UK.

In the animal kingdom, males more often than females can increase their reproductive success by being promiscuous. This in turn can result in males imposing high numbers of copulation attempts and sexual harassment on females.

In the promiscuous feral chicken, males initiate more than 90 per cents of all copulation attempts; most of them in the evening after hens have laid their eggs and are most fertile. In female-dominated groups hens are also interested in sex in evenings. However, as shown in a new study published in American Naturalist, in male-dominated groups hens rather initiate sex in mornings.

‘Sexual harassment in evenings in male-dominated groups may just be too much for the hens’, says Hanne Løvlie from Stockholm University, one of the researchers of the study. ‘Hens were exposed to more intense sexual harassment in male-dominated group. By initiating sex in mornings when the cockerels are less amorous and the free-ranging chickens also are more spread out foraging, hens may avoid the intense sexual harassment in evenings.’

The study shows that changes in the intensity of sexual harassment trigger a plasticity in the hens’ sexual behaviour not before shown. A plasticity that in turn may enable hens to mate without suffering sexual harassment.

‘The sexes therefore not only fall out on how much sex they want, but also when at day to have it’, says Hanne Løvlie.

Article Credit: AlphaGalileo

Mendel solved the logic of inheritance in his monastery garden with no more technology than Darwin had in his garden at Down House. So why couldn’t Darwin have done it too? A Journal of Biology article argues that Darwin’s background, influences and research focus gave him a viewpoint that prevented him from interpreting the evidence that was all around him, even in his own work.

Darwin’s commitment to quantitative variation as the raw material of evolution meant he could not see the logic of inheritance, argues Jonathan Howard of the University of Cologne, Germany.

“Quantitative variation was at the heart of Darwin’s evolution, and quantitative variation is the last place where clean Mendelian inheritance can be seen,” says Howard. “Darwin boxed himself in, unable to see the laws of inheritance in continuous variation, unable to see the real importance of discontinuous variation where the laws of inheritance could be discerned.”

Moravian priest and scientist Gregor Mendel (1822 – 1884) studied clear-cut, inherited traits in pea plants, which he grew in the monastery gardens in Brno. Mendel showed that trait inheritance follow simple laws, which were later named after him. Mendel’s work was rediscovered at the beginning of the 20th century, and laid the foundations for genetics. Mendel had a good understanding of biology, but his understanding of physics, statistics and probability theory were far superior to Darwin’s.

Darwin’s view of biology was greatly influenced by geologist Charles Lyell during and after the 1831-1836 Beagle voyage, leading to Darwin’s focus on infinitely tiny differences between individuals giving infinitesimal advantages or disadvantages in survival. For Darwin, selection of these variants over hundreds of thousands of generations was the critical process in evolution.

Darwin’s book The Different Forms of Flowers on Plants of the Same Species details breeding experiments involving a well-defined “unit” character, yielding clear data interpretable as ‘Mendelian’ ratios. But these went unremarked by Darwin, who insisted, because of his belief that only quantitative variation contributed to evolution, that the rules of inheritance were too complex and not ready for definitive analysis.

Heredity and variation played central roles in Darwin’s development of the theory of evolution by natural selection. His view that variation is caused by random, quasi-physical events outside environmental control, is much as we believe today. But he never freed himself from the incorrect belief that environmentally determined changes could also be inherited, another victim of his focus on quantitative characters, height, weight and so on, which are strongly influenced by environmental effects.

Article Credit: AlphaGalileo

There’s a reason why women have stronger senses of smell than men. They can’t afford not to.

“Women have a larger interest in reproductive events because they have fewer opportunities for passing on their genes than men,” said George Preti, a Monell Chemical Senses Center organic chemist.

In a study published Monday in Flavour and Fragrance, Preti and colleagues found that women were able to detect body odors masked by other fragrances. Male noses quickly lost the scent.

“Men produce thousands of gametes every day, women just one every month,” Preti said. “Their investment in a reproductive event is higher than men’s, so they’re more biologically attuned to who they’re mating with.”

Preti and other pheromone researchers suspect that mammalian olfactory systems actually evolved to detect chemical traces of genetic incompatibility in the odors of potential mates.

Of the odor-masking compounds used in the study, said Preti, the most effective were eventually used in two brands of commercial deodorant.

Article Credit: Wired Science

A third-year undergraduate student at The University of Nottingham has had her research into the sex life of the pond snail published in a peer-reviewed journal.

The study by Hayley Frend, who is a student in the School of Biology, was published today in the Royal Society Journal Biology Letters.

With a grant of £1,500 from the Nuffield Foundation Hayley Frend has shown that just like humans the pond snail is genetically programmed to use the left or right handed side of its brain to perform different tasks.

In the past it was naively presumed that only humans use different sides of their brains to carry out different tasks. Research has since shown that some vertebrates, such as fish, can use their brains in this way. And recently it has been shown that behavioural handedness is not just confined to vertebrates.

Hayley spent the summer in the laboratories at the Institute of Genetics studying the sex life and genetics of the pond snail, Lymnaea stagnalis. She has established that just like humans, snails also tend to have brains that produce ‘handed’ behaviour.

Her work, under the supervision of lecturer, Dr Angus Davison has shown that a handedness of the pond snail in their mating behaviour is matched by an asymmetry in the brain which is pre-programmed by its mother’s genes.

The pond snail nearly always has a right handed (dextral) to its shell but sometimes it is left handed (sinistral). As dextral snails circle anticlockwise and sinistral snails circle clockwise, an unusual consequence is that two ‘mirror image’ snails will circle in different directions and are frequently unable to mate.

Hayley’s Supervisor, Dr Angus Davison said: “It never fails to surprise me how research on a mere pond snail can contribute to an understanding of the way our own brain works. Lots of new research, not just my lab, is showing that the effective functioning of the brain, whether they are human, fish or invertebrates, requires that the separate halves of the brain dedicate themselves to separate functions. If this specialisation has evolved multiple times, then it is clearly a very important one for animals.”

Hayley said: “It was an invaluable experience for me to work in the lab over the summer, but I never expected that my work would be published so rapidly. I am so excited!”

The Nuffield Foundation is an independent charity committed to the careers of young scientists. Nottingham’s two science bursary schemes offer the opportunity for school and college pupils and undergraduates to gain an insight into the world of research through summer research placements.

The work was funded by the Nuffield Foundation, but the views expressed are those of the grant holder and not those of the Foundation.

Article Credit: AlphaGalileo

Scientists have revealed what may well be the first pervasive ‘rule’ of evolution.
In a study published in the Proceedings of the National Academy of Sciences researchers have found evidence which suggests that evolution drives animals to become increasingly more complex.

Looking back through the last 550 million years of the fossil catalogue to the present day, the team investigated the different evolutionary branches of the crustacean family tree.

They were seeking examples along the tree where animals evolved that were simpler than their ancestors.

Instead they found organisms with increasingly more complex structures and features, suggesting that there is some mechanism driving change in this direction.

“If you start with the simplest possible animal body, then there’s only one direction to evolve in – you have to become more complex,” said Dr Matthew Wills from the Department of Biology & Biochemistry at the University of Bath who worked with colleagues Sarah Adamowicz from from the University of Waterloo (Canada) and Andy Purvis from Imperial College London.

“Sooner or later, however, you reach a level of complexity where it’s possible to go backwards and become simpler again.

“What’s astonishing is that hardly any crustaceans have taken this backwards route.

“Instead, almost all branches have evolved in the same direction, becoming more complex in parallel.

“This is the nearest thing to a pervasive evolutionary rule that’s been found.

“Of course, there are exceptions within the crustacean family tree, but most of these are parasites, or animals living in remote habitats such as isolated marine caves.

“For those free-living animals in the ‘rat-race’ of evolution, it seems that competition may be the driving force behind the trend.

“What’s new about our results is that they show us how this increase in complexity has occurred.

“Strikingly, it looks far more like a disciplined march than a milling crowd.”

Dr Adamowicz said: “Previous researchers noticed increasing morphological complexity in the fossil record, but this pattern can occur due to the chance origination of a few new types of animals.

“Our study uses information about the inter-relatedness of different animal groups – the ‘Tree of Life’ – to demonstrate that complexity has evolved numerous times independently.”

Like all arthropods, crustaceans’ bodies are built up of repeating segments. In the simplest crustaceans, the segments are quite similar – one after the other. In the most complex, such as shrimps and lobsters, almost every segment is different, bearing antennae, jaws, claws, walking legs, paddles and gills.

The American biologist Leigh Van Valen coined the phrase ‘Red Queen’ for the evolutionary arms race phenomenon. In Through the Looking-Glass Lewis Carroll’s Red Queen advises Alice that: “It takes all the running you can do, to keep in the same place.”

“Those crustacean groups going extinct tended to be less complex than the others around at the time,” said Dr Wills.

“There’s even a link between average complexity within a group and the number of species alive today.

“All organisms have a common ancestor, so that every living species is part of a giant family tree of life.”

Dr Adamowicz added: “With a few exceptions, once branches of the tree have separated they continue to evolve independently.

“Looking at many independent branches is similar to viewing multiple repeated runs of the tape of evolution.

“Our results apply to a group of animals with bodies made of repeated units. We must not forget that bacteria – very simple organisms – are among the most successful living things. Therefore, the trend towards complexity is compelling but does not describe the history of all life.”

http://www.bath.ac.uk/news/2008/3/17/ruleevolution.html

Research published in the online journal, BMC Biotechnology reports on a new, large-scale technique for distinguishing between male and female ostrich chicks using DNA extracted from feathers. This new technique will remove the need for invasive procedures currently in use to sex-type ostriches and allow breeders to discover the sex of their chicks much earlier. Details of this new technique can now be read by all interested parties because of the decision of the authors to publish in the open access journal, BMC Biotechnology.

Although native to Africa, Ostriches are now farmed all over the world for their meat, feathers and hide. Ostriches, like many bird species, show few external differences between the sexes. In the 1960`s a surgical technique was developed to tell male and female birds apart, which involved a small operation under anaesthetic. However, this procedure can result in bleeding and infection, as well as being stressful for the birds. In addition, ostrich chicks must be around three months old before their sex can be distinguished in this way.

For most birds genetic tests have largely replaced surgery as a means of determining the sex of a chick. However, genetic tests are usually based on differences between genes carried on sex chromosomes. Unfortunately, the sex chromosomes in ostriches are very similar making these sort of genetic tests useless. Whilst some new tests have been devised, they are not suitable for the large-scale analyses that are needed by commercial ostrich breeders.

To solve this problem, researchers from Brazil have devised a fast, large-scale technique, which can be used to sex-type ostriches from feathers. They used feathers rather than blood samples because it is more practical for farmers and less stressful for the birds to collect feather samples. The procedure involves a genetic technique known as the polymerase chain reaction (PCR) which can “amplify” fragments of DNA that are specific to male or female ostriches. The researchers used their technique to sex-type 96 five-day-old ostrich chicks. Three months later, the sex of the chicks was also determined by using the traditional surgical technique. To their delight the researchers found that there was 100% agreement between the new genetic technique and the traditional surgical procedure, confirming that their method worked.

“We have established a fast, safe and inexpensive procedure for large-scale sex-typing of ostriches using DNA extracted from feathers. This procedure will be useful the gender identification of chicks in the first days of nestling life”, explained the authors.

Article Credit: AlphaGalileo