RealClearScience Journal Club

Science Figures Interpreted and Analyzed by RealClearScience

The First Evidence for STDs in Honeybees

Ross Pomeroy - July 2, 2015

One of the most common parasites infecting honeybees is sexually-transmitted, a new study published to Scientific Reports finds.

Nosema is a unicellular fungus that causes nosemosis, the most widespread disease of honeybees. Diseased bees are often afflicted with dysentery, disjointed wings, and an absent sting reflex, among many other symptoms.

The most common way Nosema is passed is via spore-ridden fecal matter. Bees swallow the spores, which make their way to the insects' guts and germinate. But it turns out that spores can also get into the semen of male bees, and when these bees copulate with the queen, she can also become infected.

Researchers primarily based out of the University of Leeds collected sexually mature male bees from 39 colonies infested by Nosema. They then harvested the insects' semen (very delicately, as one would surmise) and inseminated a group of queens. One out of every five of the queens developed nosemosis.

Luckily for the colony, infected queens do not pass Nosema onto their young. None of the 400 eggs laid by queens in the experiment carried the parasite. However, unluckily for parasite-ridden queens, their days are usually numbered once they take on the parasite. An infected queen's ovaries quickly degenerate, severely reducing her egg-laying capacity. Sensing the queen's infertility, workers then set about rearing replacement queens. When one is ready to take the throne, workers encircle the old queen and sting her to death.

"The results provide the first quantitative evidence of a sexually transmitted disease (STD) in social insects," the researchers said of the study.

STDs have been found in insects before, though, unlike vertebrate STDs, which are commonly caused by bacteria or viruses, insect STDS are usually caused by parasites -- mites, nematodes, fungi, and protists.

Source: Roberts, K. E. et al. The cost of promiscuity: sexual transmission of Nosema microsporidian parasites in polyandrous honey bees. Sci. Rep. 5, 10982; doi: 10.1038/srep10982 (2015)

(Image: AP)

Where Conservatives & Liberals Stand on Science

Ross Pomeroy - July 1, 2015

Who is more anti-science: Liberals or Conservatives? The question has been endlessly argued by political talking heads on either side, but the discussion has been surprisingly devoid of quality evidence. Finger-pointing, anecdotes, and one-off polls are used instead, and nothing really gets settled.

Filling the information void this week is a new, in-depth survey from the Pew Research Center. Data scientists polled 2,002 adults nationwide about their views on a wide range of scientific topics, including climate change, vaccines, and genetically-modified organisms (GMOs). The researchers were keen to find out where liberals and conservatives stand.

Energy and climate change were significant categories in the report, and both were highly politicized. Seventy percent of liberals were opposed to the use of hydraulic fracturing to extract oil and natural gas, while fifty-four percent of conservatives favored it. Sixty percent of liberals were also against building more nuclear power plants, while fifty-five percent of conservatives were for it. Vastly more liberals than conservatives accepted the science on climate change. Seventy-six percent of liberals said the Earth is getting warmer due to human activity, while only twenty-nine percent of conservatives agreed.

Surprisingly, anti-science views on vaccines and GMOs, typically attributed to the left, were equally distributed amongst liberals and conservatives. Fifty-seven percent of conservatives and fifty-six percent of liberals said that it is generally unsafe to eat GMOs, despite overwhelming scientific evidence to the contrary. Luckily, misguided views on vaccines were far less prevalent. Just twelve percent of liberals and ten percent of conservatives believed that childhood vaccines are unsafe (but that is still far too high).

The Pew survey replicated previous findings on the topic of evolution. Seventy-seven precent of liberals accepted evolution as a fact, while only forty-three perecent of conservatives did.

Ideally, ideology should never factor into matters of science; the evidence either points one direction or the other. But evidence is sometimes murky, and sadly, it's often misrepresented or neglected entirely.

But at RCS, evidence is all that matters. Last year, we put together an evidence-based primer on a host of politicized issues. If you're curious, check it out.

(Image: AP)

Why Some Flowers Only Smell at Night

Alex B. Berezow - June 29, 2015

"Mary, Mary, quite contrary, how does your garden grow? With silver bells and cockle shells, and one measly petunia!"  --Curly

Curly Howard didn't think highly of petunias, but had the Three Stooges spent more time gardening, they would have known that petunias are most fragrant at nighttime. Now, scientists have figured out the reason why.

Just like animals, plants have circadian rhythms (internal "biological clocks"). Some plant behaviors occur during the day, while others occur during the evening. In the case of flowering, plants prefer to send out scented signals to attract pollinators during the times at which they are most active. For Petunia hybrida cv. Mitchell, which produces white flowers and was the subject of a new PNAS study, this occurs at night, most likely in order to attract moths.

The authors, who were based at the University of Washington, were interested in elucidating the genetic mechanism behind this phenomenon. Their research homed in on a particular regulatory protein, called LHY, whose expression varied throughout the day. Specifically, it was most highly expressed during the morning (when the flowers were unscented) and rarely expressed during the night (when the flowers were most scented).

The figure above depicts the timing of the release of two scented molecules by P. hybrida, methyl benzoate (which has a fruity odor) and benzyl benzoate (which has a balsamic odor). Because LHY expression was lowest during these times, the authors hypothesized that LHY was suppressing genes involved in the production of scent.

And that's exactly what their genetic analysis found. Furthermore, they found that this particular LHY-based circadian mechanism was only present in flower tissue, not in leaves, suggesting that the circadian clock operates differently in different parts of the plant.

Finally, the researchers propose that understanding the genetic mechanism of the circadian rhythm will allow the engineering of plants that exhibit desirable behaviors at particular times of the day. A florist may prefer only flowers that are scented during the day, not during the evening. Similarly, crops could also be engineered to express certain traits throughout the day. Of course, as intriguing as these possibilities are, they require that the vast majority of people somehow overcome their irrational fear of GMOs.

Source: Myles P. Fenske, Kristen D. Hewett Hazelton, Andrew K. Hempton, Jae Sung Shim, Breanne M. Yamamoto, Jeffrey A. Riffell, and Takato Imaizumi. "Circadian clock gene LATE ELONGATED HYPOCOTYL directly regulates the timing of floral scent emission in Petunia." PNAS. Published online before print: 29-June-2015. doi: 10.1073/pnas.1422875112

(AP photo)

This Is When Athletes Hit Their Peak

Ross Pomeroy - June 25, 2015

For many of us, the hump comes too soon. We reach the apex of our physical abilities around age thirty, then it's downhill from there.

Elite athletes peak even earlier, according to a new systematic review published in the journal Sports Medicine.

Sian Allen and Will Hopkins, based out of the Sports Performance Research Institute in New Zealand, poured through the scientific literature to ascertain the age at which athletes competing in various sports hit peak competitive performance. Here's what they found:

- For sprints, jumps, and throws, men and women hit their peak around 25 years of age.

- For sprint swimming events, men peak around 24 years and women peak at roughly 22 years. Endurance swimmers peak about a year earlier for both sexes.

- Male and female marathoners are at their best at ages 30 and 29, respectively.

- Male and female triathletes peak at 27-years-old.

- Men and women competing in the Ironman triathlon, which consists of a 2.4-mile swim, a 112-mile bicycle ride, and a 26.2-mile run, are at their best at the ages of 32 and 34, respectively. 

- Professional hockey players perform best between the ages of 27 and 28.

Generally, the authors noticed that athletes competing in "sprint" events requiring explosive power peak much sooner than athletes competing in endurance or game-oriented events, perhaps because older athletes are able to use experience and savvy to their advantage.

Glaringly missing from the review were sports like baseball, soccer, and football. Surprisingly, researchers have yet to gauge the age of peak formance in those sports.

To those reading this article who are "past their prime," don't fret too much. While physiological ability tends to wane after age thirty, cognitive ability has been shown to increase in healthy individuals until at least age sixty. Though you may not be stronger or faster, you're almost certainly wiser.

Source: Sian V. Allen & Will G. Hopkins.  Age of Peak Competitive Performance of Elite Athletes: A Systematic Review. 19 June 2015. Sports Medicine. DOI: 10.1007/s40279-015-0354-3

(Image: AP)

A Giant, Predatory Worm Has Invaded Florida

Ross Pomeroy - June 24, 2015

In 2014, Jean-Lou Justine, a Professor of parasitology at the Nation Museum of Natural History in Paris, put out an urgent warning: the New Guinea flatworm had arrived in France.

He was right to be concerned. Slimy, roughly 65 millimeters in length, and sporting a ravenous appetite for snails, the highly invasive worm has been known to decimate local invertebrate species wherever it has landed. Was France's prized escargot in jeopardy?

Fortunately, the French invasion seems to be contained for now. However, worldwide, the New Guinea flatworm is on the move, and with the help of citizen scientists, Justine has just revealed that the large, predatory worm has landed in continental America, specifically Florida.

"The species is apparently now well established," Justine reported in the open-access journal PeerJ, "with several different locations found in 2014 in Miami Dade County."

Platydemus manokwari, as scientists call the flatworm, is bad news. Armed with a chemical-based tracking method attuned to mucus trails, it efficiently stalks its prey. Once the invasive flatworms gobble up local snails, they feast on earthworms and slugs. Sometimes they'll even cannibalize each other. Unsurprisingly, nothing really eats P. manokwari, which is a key reason why it thrives in a variety of habitats. Another is that scientists have not yet developed a successful method for controlling the flatworm

Apart from its disgusting appearance, the New Guinea flatworm is an affront to humans for another key reason: it's a vector of an even smaller worm, the parasitic rat lungworm, which causes meningitis. Humans can be infected by eating cabbage leaves tainted with rat lungworm larvae left behind by the flatworms. For some reason, P. manokwari frequently dwells in cabbage fields.

About the only thing that stops the flatworms is the cold. Temperatures 50 °F or below seem to be their undoing.

Justine warns that that P. manokwari may eventually move out of Florida.

"In addition to their natural spread, specimens of P. manokwari can easily be passively spread mainly with infested plants, plant parts and soil. The species could potentially eventually be spread from Florida throughout the US mainland, and this can be considered a significant potential threat to the whole US."

Source: Justine et al. (2015), The invasive land planarian Platydemus manokwari (Platyhelminthes, Geoplanidae): records from six new localities, including the first in the USA. PeerJ 3:e1037; DOI 10.7717/peerj.1037

(Images: Makiri Sei, Justine et. al. 2015)

A Chimpanzee Has Rattled Off a Drum Solo

Ross Pomeroy - June 22, 2015

Barney was a fairly normal chimpanzee. A 24-year-old, low-ranking member of a group of five adult male chimpanzees raised at the Biomedical Primate Research Centre in the Netherlands, he generally showed stereotypical behaviors: he played, he banged bottles, he climbed trees. Then, one January day, he walked away from his group and sat down outside, placing an upturned bucket between his feet. He then rattled off the only-known spontaneous, unsolicited chimpanzee drum solo. Primatologists at the center were taken completely by surprise. With no camera nearby, they recorded the five-minute performance with a simple voice recorder.

 

This happened more than a decade ago, yet Barney's performance has only just been revealed in the journal Scientific Reports.

In the wild, chimpanzees "drum" to communicate, but this isn't anything like what Buddy Rich would bang out. Male chimps might grab a nearby tree with their arms and furiously smack the trunk with their feet, hooting and hollering in the process. The act resembles a child throwing a tantrum. The purpose is not to make music; it's to make noise.

So then what was Barney doing? Could he have been playing rudimentary music?

The researchers behind the discovery can't be precisely sure, but they can say that the incident was both "intentional" and "decontextualized." Barney produced more than 685 drumbeats spread over eleven sequences for almost five minutes, remaining focused the entire time. Moreover, the drumming did not seem to serve any communicative purpose, as all of the other chimpanzees were inside and out of earshot.

An analysis of the drumming also revealed that, in five of the sequences, Barney maintained a distinct and even tempo.

"The beating in these five sequences was not only regular, but was even extremely so on occasions, with an average tempo of 257 beats per minute. This pace is close to human tempo for rhythmic music," the researchers write.

With Barney's drum solo now enshrined in the scientific literature, chimpanzees join whales and certain species of birds in the ranks of animals that may be capable of creating and enjoying something resembling music.

"Barney’s performance confirms that the chimpanzee, our closest relative, could indeed be capable of drumming like a human," the researchers say. "Our data are probably the first strong evidence of an evolutionary link between wild beating in chimpanzees and our own musical origins."

Source: Dufour, V. et al. Chimpanzee drumming: a spontaneous performance with characteristics of human musical drumming. Sci. Rep. 5, 11320; doi: 10.1038/srep11320 (2015).

(Top Image: Camille Martin)

How Much DNA Is There on Earth?

Ross Pomeroy - June 11, 2015

What if the Earth was a computer?

Well then it would be able to tell us the Ultimate Question of Life, the Universe, and Everything, as anybody who has ever read Douglas Adams' aptly named Hitchhiker's Trilogy knows!

The Earth would also have a computational power of approximately 1015 yottaNOPS (yotta equaling 1024), which is about 1022 times faster than China's Tianhe-2, the most powerful supercomputer in the world. This, we know, thanks to a fascinating analysis just published to the journal PLoS Biology.

The Earth is brimming with life, and within that life, is information, stored in strands of deoxyribonucleic acid: DNA. This information constitutes instructions that tell life how to grow and function. In a multitude of analyses, scientists have tabulated the biomass present on Earth: the blood, the guts, the bark, the leaves, all biological material that makes up life. Yet, curiously, nobody previously attempted to measure the sheer amount of information present within that life. University of Edinburgh researchers Hanna Landenmark, Duncan Forgan, and Charles Cockell just did.

By using prior estimates of biomass, cellular abundance, and average genome size, they calculated the amount of DNA on Earth from all domains of life:  5.3 × 1031 megabases, a mind-boggling amount.

"This quantity corresponds to approximately 5 × 1010 tonnes of DNA," the researchers say. "[T]his... is equivalent to the volume of approximately 1 billion standard shipping containers... By analogy, it would require 1021 computers with the mean storage capacity of the world’s four most powerful supercomputers to store this information."

Taking the rate of DNA transcription as an analogy for processing speed, they further estimated Earth's computational power: 1015 yottaNOPS.

The researchers' calculations are part of a new, informational approach to understanding life on our planet.

"In this way, the biosphere can be visualised as a large, parallel supercomputer, with the information storage represented by the total amount of DNA and the processing power symbolised by transcription rates. In analogy with the Internet, all organisms on Earth are individual containers of information connected through interactions and biogeochemical cycles in a large, global, bottom-up network," the researchers say.

They draw further analogies.

"For example, mass extinctions can be considered to be similar to physical hard drive damage in a computer."

One pressing question Landenmark and her colleagues did not answer: Does the Earth run on Mac OS X or Windows?

Source: Landenmark HKE, Forgan DH, Cockell CS (2015) An Estimate of the Total DNA in the Biosphere. PLoS Biol 13(6): e1002168. doi:10.1371/ journal.pbio.1002168

Creative People Really Are a Little Crazy

Alex B. Berezow - June 8, 2015

The notion that highly creative people tend to be eccentric or even a little "crazy" is not just a stereotype. New research in the journal Nature Neuroscience has shown that people who are genetically predisposed toward schizophrenia or bipolar disorder are likelier to be artists or a member of the creative professions.

Because creativity, by definition, requires people to "think different" as Apple would say, it is reasonable to speculate that creativity and psychiatric disorders are related and perhaps even share similar genetic mechanisms. The main question plaguing researchers, however, is whether this link is primarily due to genetic or environmental influences. So, a team of international researchers set about shedding more light on the matter.

Previously, research has shown that creative people are likelier to be bipolar, and writers, specifically, are likelier to possess some sort of mental illness. (This is beginning to concern your humble correspondent.) Additionally, people who possess genetic risk factors for schizophrenia, but are not actually schizophrenic, still show abormal thought patterns. It stands to reason, therefore, that people who have a few, but not too many, gene variants ("alleles") associated with mental illness might stand to benefit from a boost in creativity.

To determine this, the research team calculated polygenic risk scores (a measure of a person's genetic predisposition toward a particular disease) to see if they can predict whether or not a person was "creative." The answer is yes, though there is a pretty major caveat. (See chart.)

As shown in the "Combined" sample, artists from Sweden and the Netherlands were 23% more likely (OR = 1.23) than non-artists to have a polygenic risk score that indicated a vulnerability to schizophrenia or bipolar disorder. The p-values were robust. (Similar results were observed for a large sample of Icelanders.)

However, a separate analysis ("CAQ-Arts Score") based on a numerical measure of a person's creativity failed to produce a statistically significant result. Moreover, the ability of polygenic risk scores to explain variation in creativity is fairly limited. Indeed, the authors found that only about 0.25% of the variation in creativity could be explained by a genetic predisposition to schizophrenia or bipolar disorder. That means that 99.75% of the variation in creativity between individuals is explained by other genetic factors or by environmental factors.

Now, it must be pointed out that miniscule results like this are quite typical of such studies. Last year, a study reported that a genetic predisposition to schizophrenia explained less than 1% of the variance in marijuana use.

Clearly, this data is informative, but of limited utility. Until we have a more comprehensive understanding of genetics and genomics, we will have to settle for finding one tiny piece of the puzzle at a time.

Source: Robert A Power et al. "Polygenic risk scores for schizophrenia and bipolar disorder predict creativity." Nat Neurosci. Published online 8-June-2015. doi:10.1038/nn.4040

(AP photo)

Your Viral History in a Drop of Blood

Alex B. Berezow - June 4, 2015

Viruses are pernicious beasts. Some of them can sneakily hide inside the body, long after the initial infection has been cleared. For instance, varicella zoster virus (VZV), a type of herpesvirus that causes chickenpox, survives in an inactive state inside nerve cells for the remainder of a person's life. Then, for unknown reasons, it can reactivate, causing shingles in old people or even healthy 30-year-olds. Other viruses may play a role in chronic conditions such as asthma or inflammatory bowel disease.

For these reasons, knowing the viruses to which a patient has been exposed throughout his life can provide useful insights for both diagnostic and research purposes. But given both practical and technological limitations, there was no good way to perform such a test. Now, an international team of researchers, based mostly out of Harvard, has invented a device that can conduct a large-scale screen of prior viral infections. And amazingly, all that is required is a single drop of blood.

How It Works

The new platform, which the team calls VirScan, is based on a well-known technique called phage display. This clever technique examines protein-protein interactions. In this case, the team is interested in knowing if antibodies from a patient's blood sample bind to proteins from human viruses. If at some point in the past a patient was infected with a particular virus, his blood should contain antibodies against proteins from that virus.

The researchers created an enormous "library" of nearly 94,000 protein sequences from every virus that infects humans. In total, they retrieved protein sequences for more than 1,000 different strains representing 206 viral species. From the protein sequences, they deduced the DNA sequences which encoded them. Then, they synthesized short DNA segments (200 "letters" long) based on these sequences and cloned them into T7 phage, small viruses that infect only bacteria. When grown, the phage "displayed" on their surfaces the small proteins encoded by the short DNA segments. In other words, the phage were acting like mannequins, except instead of clothing, they were displaying small human virus proteins. (See figure below, panels a-c).

Next, the authors combined the phage with antibodies (panel d) extracted from human blood. If the blood sample contained antibodies against any of the proteins displayed on the phage particles, they would bind. Then, special antibody-binding proteins with tiny magnetic beads attached were added to the mixture (panel e). This allowed the phage with antibodies attached to be isolated, while the phage without antibodies attached were washed away and discarded. Thus, only phage displaying virus proteins that had been bound by an antibody were kept. By amplifying and sequencing the short DNA segments inside these phage (panel f), the researchers could determine against which viruses the individual had developed antibodies.

Patients' Viral Histories

Using their new tool, the researchers examined blood samples from 569 people. They found that the average person has been infected with 10 viral species. (See graph.)

Ten viral species may seem rather low. Considering that adults catch between two and four colds per year, it might be expected that the average person would be exposed to far more than ten viral species. However, a person can become sick if exposed to different strains of the same species of virus. There are many different strains of rhinovirus, for instance, which is the most common cause of colds. So, a person who had twenty infections with twenty different strains of rhinovirus would still only register as having been infected by one viral species. Interestingly, two of the individuals had been exposed to 84 viral species. (It is unclear if those individuals were Gene Simmons, Ron Jeremy, or Charlie Sheen.)

Excluding volunteers with HIV and HCV, the authors created a list of the most common viruses. (See chart; the number represents the percentage of individuals who tested positive for the virus.)

Of the top five most common viruses detected in their samples, four are causes of the common cold (rhinovirus A and B, adenovirus C, and respiratory syncytial virus), while human herpesvirus 4 is the cause of mononucleosis, the "kissing disease."

Limitations

Like every new technology, there are limitations. Probably the most serious drawback for VirScan is that the immune response wanes over time. Therefore, VirScan would give false negatives for any viruses against which a person's immune system is no longer producing antibodies. However, in an interview with RealClearScience, principal investigator Dr. Stephen Elledge suggested a possible solution: Activate memory B cells, which "remember" previous infections, to produce antibodies. This should, in theory, solve the problem.

Additionally, Dr. Elledge's team suggests that VirScan could be adapted to detect other microbes, such as bacteria, fungi, and parasites. At an estimated cost of merely $25, VirScan appears to represent a giant leap forward for personalized medicine.

Source: George J. Xu et al. "Comprehensive serological profiling of human populations using a synthetic human virome." Science 348 (6239). 5-June-2015. doi: 10.1126/science.aaa0698

(AP photo)

The Most Dangerous Jobs in the U.S.

Alex B. Berezow - June 1, 2015

Thanks to Mike Rowe, we know that chicken sexer, horse inseminator, and sewer inspector are among the dirtiest jobs in America. But the dirtiest jobs are not necessarily the most dangerous. For that information, we must consult the U.S. Bureau of Labor Statistics.

Recently, the BLS released its annual report of the most dangerous jobs in America. The chart below depicts the most dangerous industry sectors. (Note that military, volunteers, and people under the age of 16 were excluded. The red bars indicate the total number of fatalities, while the blue bars indicate the fatality rate in deaths per 100,000 workers -- which is the far more relevant statistic.)

As shown, the three most dangerous industry sectors are agriculture/forestry/fishing/hunting, transportation/warehousing, and mining/quarrying/oil and gas extraction.

But this is a "big picture" view and, thus, is not terribly informative. We want to know which specific jobs are the most dangerous. Well, the BLS has data on that, too:

Loggers, fishermen, pilots/flight engineers, roofers, and (to my surprise) garbage collectors constituted the five most dangerous occupations in America.

Be thankful, therefore, to the good men and women who provide us wood and paper, tasty fish, fast transportation, and nice, clean homes. Many have died providing us these basic comforts.

Source: Bureau of Labor Statistics. Census of Fatal Occupational Injuries Charts, 1992-2013. Updated April 22, 2015. (PDF)

(AP photo)

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