By Pam Eastlick
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Greetings all! Well, the animal file is bulging and specifically we have lots of stories about the real multicellular lords of the planet. And of course, that isn’t us. For numbers and biomass, that award goes to the insects. Our first story is actually from the medical file and it concerns some good news about the most deadly killer on the planet.
CURING THE CARRIER
There is no question that mosquitoes are the most deadly killers on the planet because they carry malaria. Of the estimated 250 million people who contract malaria each year, 1 million, most of them children, do not survive. Ninety percent of the fatalities occur in Sub-Saharan Africa.
Each new malaria case starts when the person is bitten by a mosquito belonging to the genus Anopheles. About 25 species of Anopheles are significant vectors of the disease and we have Anopheles mosquitoes here in the Marianas.
Only the female Anopheles mosquitoes feed on blood, which they need to produce eggs. When they bite an infected human or animal, they ingest the malaria parasite which is a single-celled organism called Plasmodium.
Once the Plasmodium cells find themselves inside the mosquito, they spring into action. First, they leave the digestive tract by squeezing through the midgut wall. Most Plasmodium cells don’t survive this journey and are eliminated by the mosquito’s immune cells. A small number survive and attach themselves on the outside of the midgut wall where they develop into brooding cells called oocysts.
Within 10-12 days, thousands of new Plasmodium cells, called sporozoites, sprout inside the oocyst. After hatching from the oocyst, the sporozoites make their way into the insect’s salivary glands where they lie in wait until the mosquito finds a victim for a blood meal. When the mosquito bites, some sporozoites are flushed into the victim’s bloodstream. The average infected mosquito transmits about 40 sporozoites when it bites, but it takes only one to infect a human and make a new malaria victim.
Killing the mosquitoes is one way to halt the transmission of malaria, but unfortunately, they are becoming resistant to virtually every insecticide in the arsenal, and malaria is becoming a world-wide deadly plague. But what if you could prevent the mosquito from becoming infected?
For the first time, University of Arizona entomologists have succeeded in genetically altering mosquitoes in a way that renders them completely immune to the Plasmodium parasite. This raises the hope that it just might be possible to replace wild mosquitoes with lab-bred populations unable to transmit the malaria-causing parasite.
"If you want to effectively stop the spreading of the malaria parasite, you need mosquitoes that are no less than 100 percent resistant to it. If a single parasite slips through and infects a human, the whole approach will be doomed to fail," said Michael Riehle, a professor of entomology in the UA’s College of Agriculture and Life Sciences.
Riehle’s team used molecular biology techniques to design a piece of genetic information capable of inserting itself into a mosquito’s genome. This construct was then injected into the eggs of the mosquitoes. The emerging generation carries the altered genetic information and passes it on to future generations. For their experiments, the scientists used Anopheles stephensi, a mosquito species that is an important malaria vector throughout the Indian subcontinent.
The researchers engineered a piece of genetic code that acts as a molecular switch in the complex control of metabolic functions inside the cell. When Riehle and his co-workers studied the genetically modified mosquitoes after feeding them malaria-infested blood, they noticed that the Plasmodium parasites didn’t infect a single study animal.
"We were surprised how well this works," said Riehle. "We were just hoping to see some effect on the mosquitoes’ growth rate, lifespan or their susceptibility to the parasite, but it was great to see that our construct blocked the infection process completely."
But there are several reasons why it isn’t time to stand up and cheer yet. First, you can create these genetically modified wonders, but how do you get them to be so genetically superior they can replace the existing populations in the wild?
Riehle and his colleagues are also working to modify the mosquito’s genome to cut down on its lifespan. "In the wild, a mosquito lives for an average of two weeks," Riehle explained. "Only the oldest mosquitoes can transmit the parasite. If we can reduce their lifespan, we can reduce the number of infections."
At this point, the modified mosquitoes exist in a highly secured lab environment with no chance of escape. Once researchers find a way to replace wild mosquito populations with lab-bred ones, breakthroughs like the one achieved by Riehle’s group could pave the way toward a world in which malaria is all but history.
Me, I personally prefer a world in which the MOSQUITO is history, but they don’t seem to be working toward that as a goal. Unfortunately.
Of course, it can be argued that the mosquito’s job is biting me and eating my blood, and our next story is about a group of insects who have very strict job standards!
NO OVERTIME FOR THEM!
British researchers working at a station in northern Finland discovered something interesting. They tagged bumblebees with radio transmitters and used them to monitor the bees’ movements during the constant light of the Arctic summer. They found that the bees observe a strict working day, even when the Sun never sets.
This surprised the scientists because they assumed that constant daylight would provide a unique opportunity for the bees to maximize pollen intake and increase colony growth. They theorize that since the bees don’t take advantage of the opportunity, there’s some benefit to an ‘overnight’ break."
The researchers studied both native bees and a group of bee colonies they brought with them. Both species worked a day shift, with maximum activity around midday, and retired to their nests well before midnight. The researchers speculate the bees must have some way of telling the time in the absence of day/night cues. This suggests that the insects may be sensitive to light intensity and quality or changes in temperature.
Speaking about the possible advantages gained by taking some time off, the researchers said, "Despite the light, temperatures do fall during the Arctic ‘night’, so it may be that the bees need to return to their nests in order to warm their brood. Also, it has been suggested that a period of sleep helps bees to remember information gained during the day’s foraging."
These bumblebees are tagged with radio transmitters. (Credit: Stelzer et al., BMC Biology)
Although the Sun never sets in the far north in summer, it does move across the sky. Perhaps this movement is the clue for the bumblebees. We all know that insects have those remarkable compound eyes that give them an unimaginable view of the world. Well, at least most of them do. And now a story about an astounding insect that does NOT have compound eyes, but something else entirely.
SEEING THROUGH VERY DIFFERENT EYES
Researchers at the University of Cincinnati were doing research on the sunburst diving beetle (Thermonectus marmoratus) when they discovered something so totally unexpected as to be almost unbelievable. They found that the larva of the beetle has eyes that are essentially bifocals. It is the first report of truly bifocal lenses in the entire animal kingdom. The larva actually has 12 eyes and at least two of them are equipped with bifocals.
The sunburst diving beetle is a small beetle about the size of a lady bug (also a beetle) that lives in creeks and streams in the western United States. Like moths, butterflies and mosquitoes, it undergoes complete metamorphosis and the larvae, which also live in the water, look quite different from the adults. It’s the larvae that have the bifocal lenses. They lose them when they grow up.
As the researchers zeroed in on how the multiple eyes of this insect worked, they did even more research to try to disprove what they saw. They first used a microscope to look through the lenses of the two eyes. They saw how the lens could make a second image grow sharper — something that could only happen with a bifocal. The graduate student who first discovered the bifocals said "It was my first research project, and I seriously thought I made a mistake, and then we did additional research to try to kill the hypothesis." However, their findings were confirmed with more research in addition to observing the operation of the lens and the two focal planes via a microscope. They saw the bifocal again when they used a method to project a narrow light beam through the lens. "Our findings can only be explained by a truly bifocal lens," write the researchers.
The researchers explain that by using two retinas and two distinct focal planes that are substantially separated, the larvae can more efficiently use these bifocals, compared with the glasses that humans wear, to switch their vision from up-close to distance — the better to see and catch their prey, with their favorite food being mosquito larvae.
University of Cincinnati researchers are reporting on the discovery of a bug with bifocals — such an amazing finding that it initially had the researchers questioning whether they could believe their own eyes. (Credit: Elke Buschbeck)
And so we come full circle. Even though this is face only a mother could love, isn’t it just wonderful that their major food is mosquito larvae?
By Pam Eastlick
Welcome to The Deep science and technology column where we cover topics from the deep sea to deep space and beyond.
Greetings! Today we’re going to investigate the wonderful world of animals. Specifically we’re going to visit some of the members of the dominant group of animals on the land part of Planet Earth. Ah, you’re thinking, didn’t she just do an article on medicine? Humans are definitely the lords of the Earth, aren’t they?
Well no, not in numbers and not in sheer body mass. That honor belongs to the six-legged animals, the insects, which represent over 90% of the differing metazoan life forms on land.
Love them or hate them, you probably wouldn’t be here without them since most of the plant food you depend on (even if you’re a thoroughgoing carnivore) is pollinated by them. So off we go into the wonderful world of insects.
If you’re talking size dominance and not numbers dominance, the largest land animal isn’t us either, it’s the elephant. And it turns out that elephants have something to say about insects. Literally.
OUCH!
Although they may be the largest land animal, it turns out that elephants (who are not stupid) produce an alarm call associated with the threat of bees, and have been shown to retreat when a recording of the call is played even when there aren’t any bees around.
A team of scientists from Oxford University, Save the Elephants, and Disney’s Animal Kingdom, made the discovery as part of an ongoing study of elephants in Kenya. They played the sound of angry bees to elephant families and studied their reactions. They found that elephants not only flee from the buzzing sound but also make a unique ‘rumbling’ call and shake their heads from side to side.
The team then isolated the specific acoustic qualities associated with the rumbling call and played the sounds back to the elephants to confirm that the recorded call triggered the elephants’ decision to flee even when there was no buzzing and no sign of any bees.
They tested their hypothesis by using both an original recording of the call and an identical recording with the frequency shifted. They also used a different elephant rumble as a control. They reported that the results were dramatic: six out of ten elephant families fled from the area of the loud speaker when they played the ‘bee rumble’ compared to just two families that left the area when they played both the control rumble and the frequency-shifted call. Moreover, they also found that the elephants moved much farther away when they heard the ‘bee’ alarm call than the other rumbles.
The researchers believe such calls may be an emotional response to a threat, a way to coordinate group movements and warn nearby elephants — or even a way of teaching inexperienced and vulnerable young elephants to beware. Further work is needed to confirm whether the rumble call is used for other kinds of threats, not just bees.
Earlier Oxford University research found that elephants avoid beehives in the wild and will also flee from the recorded sound of angry bees. In 2009 a pilot study showed that a fence made out of beehives wired together significantly reduced crop raids by elephants. The team hopes that the new findings could help develop new ways to defuse potential conflicts between humans and elephants.
Despite their thick hides adult elephants can be stung around their eyes or up their trunks, and calves could potentially be killed by a swarm of stinging bees as they have yet to develop thick protective skin.
Elephants run from bee sounds making ‘bee rumble’. (Credit: OU/Lucy King)
So why do you think the largest animals would flee from one of the smallest? Have you ever seen an elephant trunk up close and personal? Have you ever had a gnat fly up your nose? The openings in elephant trunks are large enough that a bee could get in there. Gnats don’t sting. Think about it.
And now an interesting (and more soothing) story about how insects may help protect your money. When I was younger, United States paper money didn’t change much. Each minor change was accompanied by much public wrangling and debate. Then in the 1990’s we got a whole bunch of new paper money with virtually no warning and no public debate. Did you ever wonder why?
The answer is simple. The advent of color copiers. All of a sudden, ANYBODY could easily produce virtually undetectable counterfeit money and I suspect a great many people did. Hence the ‘invisible portrait’ and other measures that make making money a lot harder than it used to be.
But counterfeiters are inventive and all countries are interested in protecting everybody’s money. Now, scientists have discovered a way of mimicking the bright and beautiful colors of butterfly wings. Their findings could have important applications in the security printing industry, helping to make bank notes and credit cards harder to forge.
BUTTERFLIES AND BETTER MONEY
The striking iridescent colors displayed by beetles, butterflies and other insects have long fascinated both physicists and biologists, but mimicking nature’s most colorful, eye-catching surfaces has proved difficult. That’s because pigments don’t create those iridescent colors. They’re produced by light bouncing off microscopic structures on the insects’ wings.
Researchers at the University of Cambridge studied the Indonesian Peacock butterfly (Papilio blumei). The wing scales of this beautiful butterfly have intricate, microscopic structures that resemble the inside of an egg carton on their surfaces. Because of their shape and the fact that they’re made from alternate layers of cuticle and air, the structures produce intense refracted colors.
The researchers used some nanofabrication procedures — including self-assembly and atomic layer deposition – to make structurally identical copies of the butterfly scales. These copies produced the same vivid colors as the butterflies’ wings. Not only does this discovery help researchers gain a deeper understanding of the physics behind butterfly’ colors, it may have promising applications in security printing.
The artificial structures could be used to encrypt information in optical signatures on banknotes or other valuable items to protect them against forgery. In the future we may find structures based on butterflies wings on a $20 bill or even our passports.
Interestingly enough, the butterfly may be using its colors to encrypt itself. It may appear to be one color to potential mates but another color to predators. The researchers discovered that the shiny green patches on the Peacock butterfly’s wings appear to be bright blue at certain wavelengths but green to the unaided eye. It’s possible that the Peacock butterfly appears bright blue to other Peacock butterflies, but a dull patchy green to potential predators like birds (and humans).
The bright green wings of the P. blumei butterfly result from the mixing of the different colors of light that are reflected from different regions of the scales found on the wings of these butterflies. (Credit: Mathias Kolle, University of Cambridge)
And now we come to an insect that has a rep that’s a lot worse than butterflies or even bees. I mean, how often have you looked someone in the eye and shouted “You bee!” But I’d be willing to bet money that you’ve said “You louse!” to somebody at least once. Or called them a lousy (insert pejorative here).
Lice. Not wonderful dinnertime conversation. Head lice, body lice, pelvic lice. We’ve all had encounters with them and none of them were pleasant. Now a research team reports it has sequenced the body louse genome, an achievement that will yield new insights into louse — and human — biology and evolution.
THAT’S JUST LOUSY
The blood-sucking parasite [now, THERE’S a pejorative for you] Pediculus humanus humanus L. has been around for millions of years of human history. The body louse spread epidemic typhus and trench fever to Napoleon’s retreating army in Russia in 1812, and body lice plagued Lewis and Clark on their adventures in the New World.
The human body louse feeds on human blood and is closely related to the head louse, Pediculus humanus capitis, which feeds on human blood too. But the body louse lives in clothing and, unlike the head louse, can spread bacterial diseases.
The human body louse has the smallest genome of any insect sequenced so far and that probably reflects its protected habitat and predictable diet. After all, lice ecology is very simple. It lives only on humans and it eats only human blood. So it has no need for genes that control sensing or responding to varied environments. The genome analysis found very few genes for light-sensing receptors and significantly fewer taste and odor receptors than other insects.
The body louse is completely dependent on humans for its survival; it will die if separated from its host for very long. It is also completely dependent on a microbe that lives inside it: the bacterium Candidatus pediculicola.
The researchers also sequenced the bacterium genome and discovered that it makes an e nutrient, Vitamin B5, which the louse must have and can’t make on its own. This, the researchers report, will make the body louse a useful tool for understanding the co-evolution of disease-carrying parasites and their bacterial co-conspirators.
Not only is studying the human body louse important in the context of human health, it’s also useful in understanding insect evolution. It’s only the second genome sequenced so far of an insect with gradual development. Although most insect species undergo complete metamorphosis, gradual metamorphosis is the older developmental program. The body louse genome can provide a baseline for understanding how complete metamorphosis, a key to insect domination of the planet, came to evolve.
The human body louse, Pediculus humanus humanus L., has been a witness to, and participant in, millions of years of human history. (Credit: CDC Photo, Courtesy of Frank Collins, Ph.D.)
Well, I hope you haven’t decided that this column is just lousy!
