Sexual selection: Do females follow fads?

Is this male attired in the fashionable look of the season? Based on the reaction of the female in the background, perhaps not. Source: Wikimedia Commons

Timeline, 2008: Sexual selection is a mechanism of evolution that sometimes butts heads with natural selection. Under the tenets of natural selection, nature chooses based on characteristics that confer a competitive edge in a given environment. Under this construct, environment is “the decider.” But in sexual selection, either competition between the same sex or a choice made by the opposite sex determines the traits that persist. Sometimes, such traits aren’t so useful when it comes to the everyday ho-hum activities like foraging for food or avoiding predators, but they can be quite successful at catching the eye of an interested female.

Those female opinions have long been considered unchanging. In the widowbird, for example, having long, flowing black tailfeathers is a great way to attract the lady widow birds. But perhaps they don’t call them widowbirds for nothing: if those male tailfeathers get too long, the bird can’t escape easily from predators and ends up a meal instead of a mate. In these cases, natural selection pushes the tailfeather trait in one direction—shorter—while sexual selection urges it the other way—longer. The upshot is a middling area for tailfeathers length.

This kind of intersexual selection occurs throughout the animal kingdom. Probably the most well-recognized pair that engages in it is the peacock and peahen. Everyone has seen the multicolored baggage any peacock worth his plumage drags around behind him. A peacock will fan out those feathers in an impressive demonstration, strutting back and forth and waving its tail in the wind, showing off for all he’s worth. It’s a successful tactic as long as nothing is around that wants to eat him.

Frogs hoping for a mate find themselves elbow deep in the “paradox of the lek.” The lek is the breeding roundup for frogs, where they all assemble in a sort of amphibian prom. For the males, it’s a tough call, literally. They must call loudly enough to show the females how beautifully androgenized they are—androgens determine the power of their larynx—while at the same time not standing out enough to attract one of the many predators inevitably drawn to a gathering of hundreds of croaking frogs. Trapped in this paradox, the frog does his best, but natural selection and sexual selection again end up stabilizing the trait within expected grooves.

This status quo has become the expectation for many biologists who study sexual selection: natural selection may alter its choices with a shifting environment, but what’s hot to the females stays hot, environmental changes notwithstanding. But the biologists had never taken a close look at the lark bunting.

A male lark bunting has a few traits that may attract females: when it shakes off its drab winter plumage and takes on the glossy black of mating season, the male bird also sports white patches on its wings that flash through the sky and sings a song intended to draw in the ladies. But the ladies appear to be slaves to fashion, not consistently choosing large patches over small, or large bodies over lighter ones. Instead, female lark buntings change their choices with the seasons, selecting a large male one year, a dark-colored male with little in the way of patches the next, and a small-bodied male the next. Lark buntings select a new mate each year, and the choice appears to be linked to how well the male will aid in parenting duties, which both parents share. It may be that a big body is useful in a year of many predators, but a small body might work out better when food supplies are low.

The researchers who uncovered this secret of lark bunting female fickleness watched the birds for five years and based their findings on statistical correlations only. For this reason, they don’t know exactly what drives the females’ annually varying choices, but they speculate that environmental factors play a role. Thus, sexual selection steps away from the realm of the static and becomes more like—possibly almost indistinguishable from—natural selection.

Beethoven died of lead poisoning–or did he?

Did lead kill Beethoven?

Timeline, 2005 and 2010: Literary folk have often noted the passion and emotion of Ludwig van Beethoven’s works. Lucy Honeychurch, the heroine of E.M. Forster’s A Room with a View, became “peevish” after playing Beethoven, and of course there’s the famous hooligan Alex from A Clockwork Orange, who was roused to stunning displays of violence after hearing “Ludwig van.” Given Beethoven’s own behavior, which was punctuated by violent rages, frequent sudden outbursts, and wandering the streets humming loudly, it’s not surprising that his music would communicate his passion.

A heavy metal influence?

A study in 2005 (news release here) yielded results that suggested that much of his anger, however, was attributable to the effects of heavy metal…specifically, lead. Beethoven became sick in his 20s (he also went deaf in his 20s), and suffered until his death at the age of 56 from a variety of illnesses, including chronic diarrhea and other stomach ailments. His death was lingering and painful, and some people thought that he had suffered from syphilis. Yet now many of his symptoms fit the classic description of slow lead poisoning. Among the effects of lead poisoning are irritability, aggressive behavior, headaches, and abdominal pain and cramping, all of which Beethoven experienced.

Doctor to businessmen to Sotheby’s to science

Some samples of the great composer’s hair and skull are available today for sophisticated testing for metals. A Viennese doctor apparently snagged a few fragments of his skull 142 years ago and the pieces eventually made their way through the family to a California businessman. The hairs were cut by a student soon after Beethoven died and ended up at a Sotheby’s auction. A few years ago, tests on the hairs suggested that Beethoven’s body harbored high levels of lead—hair accumulates and retains such toxins better than any other tissue—but because the testing method destroyed the hair, further tests were not completed.

Wobbling electrons solve the mystery?

Since that time, a powerful new X-ray technique has become available. The Department of Energy’s Argonne National Laboratory owns the X-ray. In the facility, subatomic particles fly through a tubular tunnel almost at the speed of light, emitting as they travel X-rays 100 times brighter than the sun’s surface. These X-rays can bounce off of the surface of even a tiny sample. As they bounce off of the sample, electrons wobble out of place, releasing energy in a pattern that is specific to the atom being bombarded.

Researchers were interested in Beethoven’s hair and skull pieces. The team that evaluated the samples actually works on developing bacteria that can take up heavy metals and render them relatively harmless; such organisms would be useful in environmental detoxification. They placed Beethoven’s hair in their high-powered X-ray. The electrons wobbled and the pattern indicated that Beethoven was simply full of lead. In fact, they reported that the poor man had about 60 parts per million of lead in his body, which is 100 times normal levels. It certainly was enough to make a person manifest the various symptoms that characterized most of Beethoven’s life.

The team also looked for a pattern that arsenic would emit, and they found none. This result seemed to exonerate Beethoven from having had syphilis, since arsenic would have been the treatment of choice for such an ailment.

Not so fast

At the time the study results were revealed, ideas about how did Beethoven built up so much lead abounded. Some suggested that  his body was less able than normal to rid itself of the heavy metal, through which he’d have been exposed by many channels. His stomach problems and temperament led him to consume much wine, and the vessels for drinking wine contained lead. In addition, his medicines probably were stored in lead-lined bottles or vials, and he may well have visited spas—for his health, ironically—at which he consumed or swam in mineral water containing lead. In one report, Beethoven’s poor doctor was identified as the likely culprit in his demise.

Fast-forward five years to 2010. A deeper analysis (news release here) of the bone fragments from Beethoven’s school indicated that his lead levels were not that spectacular. The bone is the reservoir for most of the lead the body takes up, and Beethoven’s bones simply didn’t have enough to have caused his various physical ailments. While the experts seemed to be in agreement that the results point away from lead, a new heavy metal mystery arose from the results. One skull fragment they tested had about 13 mcg of lead per gram of bone, nothing to write home about, while another sample turned up with 48 micrograms per gram, a much higher level. Nevertheless, we must look elsewhere for what killed one of the world’s greatest western composers. Ideas being tossed around include lupus and heart disease. What we do know is that he lived in terrible pain, both from his maladies and from the treatments designed to help, including pouring hot oil in his ears, according to one Beethoven scholar quoted in the New York Times.

Another wrongly accused suspect

Heavy metals have featured in other historical whodunits. For example, Napoleon reportedly died of stomach cancer during his exile on Elba, but one analysis showed that he actually died of slow arsenic poisoning, suggested to have been at the hand of his closest assistant. Then, much like Beethoven’s story, a later study showed that arsenic likely played no role in the great general’s death.

No legal limit for bats?

  • A bat in the hand

    Timeline, 2010: People with a blood alcohol level of 0.3 percent are undeniably kneewalking, dangerously drunk. In fact, in all 50 states in the US, the cutoff for official intoxication while driving is 0.08, almost a quarter of that amount. But what has people staggering and driving deadly appears to have no effect whatsoever on some bat species.

Why, you may be wondering, would anyone ask this question about bats in the first place? Bats are not notorious alcoholics. But the bat species that dine on fruit or nectar frequently encounter food of the fermented sort, meaning that with every meal, they may also imbibe a martini or two worth of ethanol.

Batty sobriety testing

Recognizing this exposure, researchers hypothesized that the bats would suffer impairments similar to those that humans experience when they overindulge. To test this, they selected 106 bats representing six bat species in northern Belize. Some of the bats got a simple sugar-water treat, but the other bats drank up enough ethanol to produce a blood alcohol level of more than 0.3 percent. Then, the bats got the batty version of a field sobriety test.

Bats navigate by echolocation, bouncing sound waves off of nearby objects to identify their location. To determine if the alcohol affected the bats’ navigation skills and jammed the sonar, the researchers festooned a ceiling with dangling plastic chains. The test was to see if the animals could maneuver around the chains while under the influence of a great deal of alcohol. To their surprise, the scientists found that the drunk bats did just as well as the sober ones.

Some bats hold their drink better than others

Interestingly, the bats did show a human-like variation in their alcohol tolerance, with some bats showing higher levels of intoxication than others. But one question that arises from these results is, Why would bats have such an enormous alcohol tolerance?

As it turns out, not all of them do. These New World bats could, it seems, drink their Old World cousins under the table. Previous research with Old World bats from Egypt found that those animals weren’t so great at holding their drink. Thus, it seems that different bat species have different capacities for handling—and functioning under the influence of—alcohol.

One potential explanation the investigators offer for this difference is the availability of the food itself. In some areas, fruit is widely available at all times, meaning that the bats that live there are continually exposed to ethanol in their diet. Since they can’t exactly stop eating, there may have been some selection for those bats who could get drunk but still manage to fly their way home or to more food. In other bat-inhabited areas, however, the food sources vary, and these animals may not experience a daily exposure to intoxication-inducing foods.

Alcohol driving speciation?

This study may be one of the first to identify a potential role for alcohol in the speciation of a taxon. Bats as a group underwent a broad adaptive radiation, meaning that there was a burst of speciation as different bat species evolved in different niches. Factors driving this burst are thought to have included different types of fruit; for example, tough fruits require different bat dentition features compared to soft fruits. Now, it seems that alcohol availability may also have played a role in geographical variation of alcohol tolerance in bats. Bats with greater tolerance would have been able to exploit a readily available supply of alcohol-laden foods.

What’s next in drunk-animal research? The investigators who made this unexpected bat discovery have a new animal target—flying foxes, which aren’t really foxes at all but yet another species of bat that lives in West Africa. We’ll have to wait and see how these Old World bats compare to the New World varieties when it comes to holding their liquor.

Fish can count, too

One, two, three...

Timeline, 2008: We tend to think of a few things we do as being uniquely human. And then we keep finding other organisms that can do them, too. Walking on two legs? Meet the orangutan, walking upright in the trees. Tool use? Crows can make a hook to fish meat out of a tube. The ability to talk? Seems that Neanderthals might have had that, also. OK, well what about counting, having number sense? Baby chickens share this trait with us. To the growing list of other animals that do as well—which includes dolphins, rats, and some monkeys—you can now add the mosquitofish.

Mosquitofish vs Munduruku

Yes, apparently fish can also count, in some cases as well as infants ages 6 to 12 months. In fact, when compared to some natives of the Amazon, the Munduruku, which have limited number language, the fish may even be comparable. The Munduruku people see no value in having a construct for counting beyond five. The mosquitofish, on the other hand, can count about that high and estimate with even higher numbers.

Number sense: It’s not just for people any more

Number sense can be broken down into three paths of perception. We can visually estimate what we see, as people do when they report crowd counts for huge parades or demonstrations. We can also visually count individual units, as we might do just looking at the fingers on one hand. And humans also have the ability to verbally count, theoretically to infinity given sufficient time. While mosquitofish obviously do not count out loud, they do appear to have visual estimation and counting abilities.

Neither is sexual harassment

Their estimation abilities first emerged as a result of sexual harassment. Researchers studying the guppy-like fish noticed that when a male harassed a female, the female fish would take refuge with a group of fish nearby. If there was a choice of groups, or shoals, of different sizes, she would choose the larger of the two. Of course, her ability to tell “larger” might have had nothing to do with actual numbers but instead with the area that the fish occupied. To assess this possibility, researchers performed a number of complex experiments. Their results showed that the females were not relying in occupied area to figure out which group had more fish. They really were using visual number estimation to decide.

In fact, they seem to use ratios in their determinations, but the ratios need to meet a threshold of difference for the estimations to work. For example, a mosquitofish seems able to distinguish a group of 16 fish as being larger than a group of 8 fish, a ratio of 2:1. But the fish cannot tell a group of 12 from a group of 8, proving unable to distinguish a 3:2 ratio.

Estimating, counting: These fish are brilliant

With lesser numbers, up to about four, however, the fish discard visual estimation and rely instead on actual visual counting. In what really was a clever set of experiments, the research team let an individual female fish spend an hour exploring two areas of an aquarium. In one area, she could see a group of four fish but could only see each fish one at a time. In the other area was a group of three fish, again only visible to the female one at a time. After letting her explore, the researchers then determined where the female spent more time. The fish spent about twice as long swimming close to the larger group. In other words, the fish seems to have counted the number of individuals in each group and based on their counting, figured out which area of the aquarium had the larger group.

Pretend you’re a fish

To get in tune with how meaningful this ability is, visualize the experiment yourself as a human (you’re human, right?). Stand in front of two open doorways. In one doorway, four people appear, one at a time. In the other doorway, three people appear, one at a time. You can count them, distinguishing each different individual, and can tell which doorway leads to the larger group of people. That’s how smart the mosquitofish is.

Why we love our blankies

The box that "duplicated" precious objects

Timeline, 2007: My oldest son is like Linus. He will not part with his “fuzzy,” a blanket that has now survived almost six years of nightlong hugging, trips by plane, train, and automobile, a lonely overnight at a Gymboree, and endless variations on superheroes, ghosts, and pirate headwraps. A professor at the University of Bristol, working with another researcher from Yale, found that children appear to attach a property beyond the physical to these objects of their sleepytime need. The two professors, Bruce Hood and Paul Bloom (of Yale), tested children ages 3 to 6 who had an attachment toy, something that they slept with regularly and had owned for at least one-third of their lives.

For the study, the grownups played a trick on the children. They showed the kids a conjurer’s box with a lot of fancy knobs on it and told them that it was a copying machine that could duplicate objects. To demonstrate, the grownups placed a green block in the machine, fooled around with some of the knobs, and made the first box buzz. Then, the second box of the machine buzzed, and when the doors opened, there was an identical green block behind door number 2.

Linus was engaged in magical thinking

A total of 22 children had brought their attachment objects for the study. After witnessing the amazing abilities of the copying box, four of them simply refused to allow their special object to be “copied” at all. The remaining 18 did allow it, but when choosing between the “copy” and the original, only five selected the “copy.”

Another group of children had brought nonattachment objects for the study. Every child consented to the copying process, and when it came time to choose between their object and the “duplicate,” almost two-thirds opted for the “new” version. Once the study was completed, all children learned that the object they had selected was, in fact, their original toy or blanket.

The Queen’s chalice

The researchers also conducted a different set of experiments in which they placed a goblet in the machine and told the child that it was special either because it was made of silver or had belonged to the “Queen,” presumably the Queen of England. Children who thought it was made of precious metal felt that the “copy” was worth the same as the original; however, children who were told that the original was the Queen’s thought it was of superior value to the “duplicate.”

What drives this kind of irrational, magical thinking? According to Hood, from the University of Bristol, humans are evolved to seek explanations for what cannot be seen, such as gravity. Because mechanisms for many natural phenomena cannot be directly observed but must be inferred, we rely heavily on our intuitive thinking to reach conclusions. This reliance leaves the door open to believing supernatural explanations for what we otherwise cannot explain. Attachment objects may be a substitute for a child who sleeps separately from his mother. But children also appear to confer on the object an “essence,” some meaning beyond its physical worth, something that makes it different from an exact physical duplicate.

The killer’s cardigan

Children are not alone in their reliance on credulity. Grownups use superstition as a way to cope with situations or feel more control over them or to explain the unexplainable. Hood demonstrated the adult tendency to believe an “essence” very clearly in a recent presentation. He offered audience members the chance to earned a quick $25 just for putting on a worn old blue cardigan. Numerous volunteers raised their hands. When he then mentioned that the cardigan had been the property of a notorious mass murderer, most volunteer hands disappeared. The few people who did put on the sweater, which had not really belonged to a murderer, found that the other members of the audience avoided them while they wore it. Scientists are not immune—plenty of us would simply refuse to exchange our wedding rings for an exact copy, for example, even though physically, it is no different from the original we wear on our ring finger.

Nematode may trick birds with berry-bellied ants

Comparison of normal worker ants (top) and ants infected with a nematode. When the ant Cephalotes atratus is infected with a parasitic nematode, its normally black abdomen turns red, resembling the many red berries in the tropical forest canopy. According to researchers, this is a strategy concocted by nematodes to entice birds to eat the normally unpalatable ant and spread the parasite in their droppings. (Credit: Steve Yanoviak/University of Arkansas)

Timeline, 2008: Host-parasite relationships can be some of the most interesting studies in biology. In some cases, a parasite requires more than one host to complete its life cycle, undergoing early development in one host, adult existence in another host, and egg-laying in still another. There’s the hairworm that turns grasshoppers into zombies as part of its life cycle, and the toxoplasma parasite, which may alter the behavior of humans and animals alike. Often, the infection ends with the host engaging in life-threatening behaviors that lead the parasite to the next step in the cycle.

A recent discovery of a most unusual host-parasite relationship, however, results in changes not only in host behavior but also in host appearance. The infected host, an ant living in the forest canopy in Panama and Peru, actually takes on the look of a luscious, ripe fruit.

Berry-butted ants

Researchers had traveled to the Peruvian forest on a quest to learn more about the airborne acrobatics of these ants, Cephalotes atratus. This ant is a true entomological artist, adjusting itself in midair if knocked from its perch. Re-orienting its body, it can glide back to the tree trunk, grabbing on and climbing to where it belongs, avoiding the dangers of the forest floor.

As the investigators monitored the colony, they became aware of some odd-looking members of the group. These ants had large red abdomens that shimmered and glowed and looked for all the world like one of the tropical berries dotting the forest around them. Curious about these odd ants, the scientists took some to the lab for further investigation. Ant researchers are an obsessive breed, and they had even placed a bet over whether or not these berry-bellied ants were a new species.

A belly full of another species’ eggs

When they sliced open one of the bellies under a microscope, what they found surprised them. Inside, a female nematode had packed the ant’s abdomen full of her eggs. The bright red belly was an incubator and, the researchers surmised, a way station on the nematode’s route to the next step in its life cycle. This was the same old C. atratus with a brand new look.

Tropical birds would normally ignore these ants, which are black, bitter, and well defended with a tough, crunchy armor. But any tropical bird would go for a bright, red, beautiful berry just waiting to be plucked. The scientists found that in addition to triggering changes to make the ant belly look like a berry, the nematode also, in the time-honored manner of parasites, altered its host’s behavior: the berry-bellied ants, perched on their trees, would hold their burgeoning abdomens aloft, a typical sign of alarm in ants. A bird would easily be tricked into thinking that the bug was a berry. One quick snap, and that belly full of nematode eggs would be inside the belly of a bird.

Poop: A life cycle completed

And then the eggs would exit the bird the usual way, ending up in the bird’s feces. The ants enter the picture again, this time collecting the feces and their contents as food for their colony’s larvae. The eggs hatch in the larvae and the new nematodes make their way to the ant belly to start the cycle anew.

The nematode itself is a new find, a new species dubbed Myrmeconema neotropicum. And it seems that earlier discoverers of the berry-bellied ants also thought they had a new species on their hands: the researchers turned up a few previous berry-bellied specimens in museums and other collections labeled with new species names. No one had thought that the difference in appearance might be the result of a parasitic infection: this relationship is the first known example of a parasite causing its host to mimic a fruit.

Birds remain the missing link

There is one hitch to the newly discovered nematode-ant-bird association: the researchers never actually saw a tropical bird snap up a juicy, fruit-mimicking ant. They report seeing different species of birds scan the bushes where such ants sheltered, but there were never any witnessed ant consumptions. Thus, this inferred piece of the puzzle—the involvement of birds and their droppings in the life cycle of this nematode—remains to be proven.

Asymmetrical features associated with anger

Don’t anger the asymmetric

After you read this piece, you will probably break out the measuring tape and try to figure out how prone to anger you are, because recent research indicates that anger can be measured in inches.

Using a clever ruse, researchers at Ohio State University found in 2004 that the more asymmetrical a person is in some physical features, the more likely that person is to become angry at rejection. In addition, the scientists found a role for testosterone and sex in these responses.

They duped 51 men and 49 women into thinking that they were attempting to raise money for a (false) charity. Participants had to make two phone calls in an effort to obtain a donation and expected to receive a reward if they were successful. Instead of the person on the other end of the phone being someone in the middle of his dinner, it was really a researcher, pretending to be a solicitee. At the first phone call, the solicitee pretended to be sympathetic, but politely said that he or she had no money to give. For the second phone call, the responder behaved rudely, saying the donation would be a waste of money. The first response was considered a low-provocation incident, and the second a high-provocation response.

Who hangs up phones any more?

When the unknowing study participants hung up the phone, the force of their hang-up was measured, as were their testosterone levels. Additionally, after the exercise, they had a choice of three letters to send to the people they had called; one letter was polite, one moderately pleasant, and the third accusatory and angry.

After collecting data on the ankles, foot width, ear height and width, palms, wrists, and fingers of the participants, the researchers looked for correlations between asymmetry of these characteristics and an angry response, as measured by the force of the telephone hang-up. They found that asymmetrical people became angrier and slammed the receiver more than symmetrical people. In addition, asymmetrical men hung up with more force under the low-provocation scenario, and asymmetrical women hung up with more force after confronting the rude responder.

Oh, testosterone and anger again?

Testosterone levels also played a role, with higher levels causing a more pronounced anger response, and again, the response showed a sex-bias. High-testosterone men were more likely to hang up forcefully after the low-provocation incident, and high-testosterone women after the high-provocation scenario.

What does it all mean? Are the asymmetric people sensitive to rejection, and thus, easily angered by it? Perhaps. But the researchers hypothesize that stress during embryonic development disrupts the embryo on several levels, from physical symmetry to neuronal connections. Scientists have long thought that shifts from symmetry during embryonic development—for example, the right-hand fingers developing a greater length than the left-hand fingers—occur because stressors send developmental signals awry. If the signals operate and are received correctly, both sides should develop the same way; but cigarette smoke, alcohol, and other stressors can disrupt these signals, and asymmetry—and quick anger—can be the result.

Testosterone and asymmetry

One intriguing finding of the study was that the asymmetry results reflected the testosterone levels of the participants. This outcome brings questions of the relationships among the hormonal parameters of development, their disruption, and later manifestations of these interactions.

If you’re wondering why men got so angry with the polite responder and women more so with the rude responder, here’s the researchers’ explanation: Men are quick to react with anger, but are not as comfortable as women with high-anxiety situations. So, when the tension amps up, men back off, but women may actually become more aggressive.

And those letters? More than a third of the participants wanted to send the rudest letter, regardless of their sex or levels of symmetry or testosterone. Perhaps they were merely foreshadowing the anger that now pervades American politics today.

With clones like these, who needs anemones?

Finding Nemo makes marine biologists of us all

I once lived a block away from a beach in Northern California, and when my sons and I wandered the sands at low tide, we often saw sea anemones attached to the rocks, closed up and looking much like rocks themselves, waiting for the water to return. My sons, fans of Finding Nemo, still find these animals intriguing because of their association with a cartoon clownfish, but as it turns out, these brainless organisms have a few lessons to teach the grownups about the art of war.

Attack of the clones

Anemones, which look like plants that open and close with the rise and fall of the tides, are really animals from the phylum Cnidaria, which makes them close relatives of corals and jellyfish. Although they do provide a home for clownfish in a mutualistic relationship, where both the clownfish and the anemone benefit from the association, anemones are predators. They consist primarily of their stinging tentacles and a central mouth that allows them to eat fish, mussels, plankton, and marine worms.

Although anemones seem to be adhered permanently to rocks, they can, in fact, move around. Anemones have a “foot” that they use to attach to objects, but they also can be free-swimming, which comes in handy in the art of sea anemone warfare. (To see them in action, click on video, above.)

Sea anemone warfare could well be characterized as an attack of the clones. These animals reproduce by a process called lateral fission, in which new anemones grow by mitosis from an existing anemone, although they can engage in sexual reproduction when necessary. But when a colony of anemones is engaged in a battle, it consists entirely of genetically identical clones.

Yet even though they are identical, these clones, like the genetically identical cells in your liver and your heart, have different jobs to do in anemone warfare. Scientists have known that anemones can be aggressive with one another, tossing around stinging cells as their weapons of choice in battle. But observing groups of anemones in their natural environment is almost impossible because the creatures only fight at high tide, masked by the waves.

To solve this problem, a group of California researchers took a rock with two clone tribes of anemones on it into the lab and created their own, controlled high and low tides. What they saw astonished them. The clones, although identical, appeared to have different jobs and assorted themselves in different positions depending on their role in the colony.

Battle arms, or “acrorhagi”

The warring groups had a clearly marked demilitarized zone on the rock, a border region that researchers say can be maintained for long periods in the wild. When the tide is high, though, one group of clones will send out scouts, anemones that venture into the border area in an apparent bid to expand the territory for the colony. When the opposition colony senses the presence of the scouts, its warriors go into action, puffing up large specialized battle arms called acrorhagi, tripling their body length, and firing off salvos of stinging cells at the adventuresome scouts. Even warriors as far as four rows back get into the action, rearing up the toss cells and defend their territory.

In the midst of this battle, the reproductive clones hunker down in the center of the colony, protected and able to produce more clones. Clones differentiate into warriors or scouts or reproducers based on environmental signals interacting with their genes; every clonal group has a different response to these signals and arranges its armies in different permutations.

Poor Stumpy

Warriors very rarely win a battle, and typically, the anemones maintained their territories rather than achieving any major expansions. The scouts appear to run the greatest risk; one hapless scout from the lab studies, whom the researchers nicknamed Stumpy, was so aggressive in its explorations that when it returned to its home colony, it was attacked by its own clones. Researchers speculated that it bore far too many foreign stinging cells sustained in the attacks, thus resulting in a case of mistaken identity for poor Stumpy.

Crazy cat lady may have microbe to blame

Toxoplasma gondii is the cat-borne parasite responsible for causing toxoplasmosis and a host of other problems in humans. This close relative of the malaria-causing protozoan may drive human behavior and immunity, in addition to causing acute illness and devastating birth defects. Recent research points to a single gene underlying this parasite’s virulence in the human host. It’s scary yet fascinating to think that a single gene from a single organism could have such dramatic effects on our species.

Warning pregnant women away from litter boxes

Because T. gondii infection can result in serious fetal defects, many pregnant women have heard of toxoplasmosis, an illness that often goes unnoticed in the afflicted person. Pregnant women are warned away from cat litter boxes and even away from gardening because contact with cat feces can mean contact with the parasite. T. gondii spends the sexual part of its life cycle in cats, but for its asexual life, it can parasitize a number of hosts, from pigs to lambs to mice to people. People also can acquire the infection from eating undercooked meat or drinking contaminated water. In some countries, like Brazil, up to 60% of the population has been exposed to T. gondii; in the United States, about 33% of people tested have antibodies to the parasite, indicating past infection.

Link between parasite and schizophrenia

The “crazy cat lady” has practically become a social stereotype in the United States and other countries, conjuring the image of a woman who lives with 25 cats and talks to herself a lot. But researchers investigating schizophrenia have actually identified a potential link between people who are exposed to Toxoplasma infection and the manifestations of schizophrenia; for example, several studies have identified higher levels of antibodies to the parasite in people with schizophrenia, and infection with Toxoplasma can cause damage to brain cells that is similar to the damage seen in patients with schizophrenia. Toxoplasmosis can also sometimes lead to symptoms of psychosis.

The fact is that most people don’t know they have toxoplasmosis because they have healthy immune systems. In people with compromised immunity, however, such as those with HIV, T. gondii can precipitate an extreme form of dementia that eventually kills them. The dementia is so severe that the sufferer eventually becomes completely unaware of his or her surroundings and lapses into a coma. The bug, however, also can affect the central nervous system in healthy people and is also linked to severe eye problems even in patients who are not immunocompromised. One researcher has claimed that infection with the parasite makes men dumber and women act like “sex kittens.”

ROP18: Watch out for this one

There are different strains of T. gondii, and investigators have noted that the Type 1 strain is most closely associated with disease. Studies of T. gondii, which has a genome with about 6000 genes, have pinpointed the virulence capacity of the strain to a single gene, dubbed ROP18. This gene encodes a kinase, one of a huge class of cell signaling proteins that add phosphates to molecules. Typically in cell signaling, kinases exist in a series, phosphorylating the next protein in the pathway, which helps maintain regulation of the signaling. The most virulent T. gondii strains have a form of the gene that differs from that carried by benign strains. Researchers speculate that this kinase interferes with a cell’s normal signaling, hijacking it for its own purposes, including growth and reproduction. The good news is that because kinases are so important in cell signaling, pharmaceutical companies have developed libraries of molecules that inhibit specific kinases, so one potential path to preventing toxoplasmosis is to discover an inhibitor of ROP18.

Rats get a little nutty from it, too

Not only has this parasite been linked to the ability to alter human behavior, but it also appears to alter rodent behavior in ways that favor its own reproduction. For example, rodents exposed to toxoplasma via cat feces actually become more likely to hang out near cat urine. If a cat eats the infected animal, the toxoplasmosis bug can then move into the sexual phase of its life cycle in the cat.

Magnetic fields and the Q

Sorry, not for Trekkies. This Q is chemical.

People have been concerned for years about magnetic fields having adverse health effects–or even have peddled magnets as being health beneficial. But although scientists have demonstrated repeatedly a chemical response to magnetic fields, no one has ever shown the magnetic fields directly affecting an organism.

The earth’s core is weakly magnetic, the result of the attraction between electric currents moving in the same direction. Nature presents plenty of examples of animals that appear to use magnetic fields. Some bacteria can detect the fields and use them for movement. Birds appear to use magnetic fields to navigate, and researchers have shown that attaching magnets to birds interferes with their ability to navigate. Honey bees become confused in their dances when the earth’s magnetic fields fluctuate, and even amphibians appear to use magnetism for navigation. But no one has clearly demonstrated the mechanism by which animals sense and use magnetic fields.

Do pigeons use a compass?

Some research points to birds using tiny magnetic particles in their beaks to fly the right way. But these particles don’t tell the birds which way is north; they simply help the bird create a topographical map in its head of the earth over which it flies. The magnetic particles tell a pigeon there’s a mountain below, but not that the mountain is to the north. The conundrum has been to figure out how the pigeon knows which way is north in the absence of other pointers, such as constellations.

The answer to the conundrum lies with the bacteria. Scientists in the UK have used the purple bacterium Rhodobacter sphaeroides to examine what magnetic fields do at the molecular level. These bacteria are photosynthetic, and absorb light to convert to energy in the same way plants do. The absorbed light triggers a set of reactions that carry energy via electrons to the reaction center, where a pigment traps it. Under normal conditions, as the pigment traps the energy, it also almost instantaneously converts it to a stable, safe form, but sometimes the energy can form an excited molecule that can be biologically dangerous. As it turns out, these reactive molecules may be sensitive to magnetic fields.

A radical pair…or dangerous triplet

A chemical mechanism called the “Radical Pair Mechanism” is the method by which the potentially dangerous molecules can form. In this mechanism, an electron in an excited state may pair with another type of electron in an excited state. If the two excited molecules come together, they can form what is called a “radical pair in a singlet state,” because they are two singlets that have paired. Under normal conditions, this pairing does not happen; in the photosynthetic bacterium, for example, a compound called a quinone (Q) inhibits formation of this pair or of an equally damaging triplet of one electron type or the other.

But when a Q is not present, the singlet or triplet state results. If the triplet forms, it can interact with oxygen to produce a highly reactive, biologically damaging singlet molecule that we know as a “radical.” You have probably heard of radicals in the context of antioxidants—they are the molecules that antioxidants soak up to prevent their causing harm. You may also have heard of carotenoid, a pigment that is an antioxidant. In a normal photosynthetic bacterium, the carotenoids present serve as the Q, the compound that prevents formation of the damaging radical.

A helpful effect of magnetic fields?

Where do magnetic fields come in? Previous work indicated an influence of magnetic fields on triplet formation, and thus, on radical formation. One excellent model to test the effects of fields in a biological system is to remove the Q, the molecular sponge for the triplets, and then apply magnetic fields to see whether triplets—and radicals—form.

That’s exactly what the researchers did, using a mutated form of R. sphaeroides that did not make carotenoids—the Q. The result? The stronger the field, the less radical product was made. They have demonstrated a magnetic field effect in an organism for the first time, and the effect was helpful, not damaging. Their next step, which they are working on, is examining whether or not the bacteria grow better in the presence of the fields.

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