Category Archives: Life Science

Darwin’s Jellyfishes

Palau’s marine-lake jellyfish actually diverged very quickly from their common ancestor, the spotted jellyfish. Like other jellyfish, the spotted jellies are cnidarians, a scientific grouping that includes reef-building corals. The spotted jellyfish drift in Palau’s lagoon, zapping the occasional zooplankton with their stinging nettles and absorbing the sugary by-products of photosynthesizing algae living in their tissues.

Like many jelly species, the spotted jellyfish has a multi-stage life cycle. Adult males and females with the familiar bell-shaped bodies are called medusae, but you would not recognize very young jellyfish as jellyfish at all. After medusae release eggs and sperm into the water, fertilized eggs hatch as larvae that drift for a few days before attaching to solid objects, such as rocks. The larvae morph into polyps resembling tiny anemones. Polyps can bud off into more polyps or, when conditions are right, into new young medusae.
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the jellyfish do not “eat” algae. Like their lagoon ancestors, the jellyfish simply absorb their algae’s photosynthetic leftovers. The jellies get about three-fourths of their energy from algal excretions and the remainder from prey. In essence, the jellyfish are landlords that hunt a bit on the side.

The jellyfish-algae partnership did not originate in the lakes, either. Ancestral spotted jellyfish brought the arrangement with them. “Spotted jellyfish in the lagoon have basic behaviors that help ‘sun’ their algae,” Martin explains. “They move eastward in the morning. The lake jellies have adapted this migration to each individual lake. The most spectacular migration is in Jellyfish Lake.”

The jellies’ migration delicately balances time in the sun (to benefit their algae) and predator avoidance. The gelatinous masses of peanut-shaped Jellyfish Lake begin their day in the western basin. As the sun rises they pulsate eastward toward the rising sun—but not too far east, because the lakeshore is covered with jellyfish-eating anemones. The jellies stop swimming east when they hit the shade cast by mangrove trees lining the shore.
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At nightfall the jellies switch to a vertical migration. Jellyfish Lake reaches depths of 100 feet, but only the top 45 feet contain oxygen. The bottom is a toxic vat of hydrogen sulfide. Bacteria do a brisk business at the interface, metabolizing both the oxygen above and hydrogen sulfide below. Every night the jellies bob up and down from the surface to the bacterial layer. Besides helping the jellyfish stay in place, dipping down treats the jellies’ algae to a midnight snack of nutrients excreted by the microbial masses.

Very Cool.

Macropinna Microstoma: Fish with a Transparent Head

That is a pretty awesome fish. The eyes were believed to be fixed in place and seemed to provide only a “tunnel-vision” view of whatever was directly above the fish’s head. A new paper by Bruce Robison and Kim Reisenbichler shows that these unusual eyes can rotate within a transparent shield that covers the fish’s head. This allows the barreleye to peer up at potential prey or focus forward to see what it is eating.

Deep-sea fish have adapted to their pitch-black environment in a variety of amazing ways. Several species of deep-water fishes in the family Opisthoproctidae are called “barreleyes” because their eyes are tubular in shape. Barreleyes typically live near the depth where sunlight from the surface fades to complete blackness. They use their ultra-sensitive tubular eyes to search for the faint silhouettes of prey overhead.

Full press release

Study Shows Weight Loss From Calorie Reduction Not Low Fat or Low Carb

A Randomized Trial Comparing Low-Fat and Low-Carbohydrate Diets Matched for Energy and Protein

The preliminary results presented in this paper are for the first four of six postmenopausal overweight or obese participants who followed, in random order, both a VLC [very-low-carbohydrate] and an LF [low-fat] diet for 6 weeks. Other outcome measures were serum lipids, glucose, and insulin, as well as dietary compliance and side effects. Our results showed no significant weight loss, lipid, serum insulin, or glucose differences between the two diets. Lipids were dramatically reduced on both diets, with a trend for greater triglyceride reduction on the VLC diet. Glucose levels were also reduced on both diets, with a trend for insulin reduction on the VLC diet. Compliance was excellent with both diets, and side effects were mild

Essentially the study showed that the calories had an impact on weight loss but the makeup of those calories did not. Don’t forget this is just one study. Listen to interview with the Author, Frank Sacks, on Science Friday on NPR.

Gram-negative Bacteria Defy Drug Solutions

Deadly bacteria defy drugs, alarming doctors by Mary Engel

Acinetobacter doesn’t garner as many headlines as methicillin-resistant Staphylococcus aureus, the dangerous superbug better known as MRSA. But a January report by the Infectious Diseases Society of America warned that drug-resistant strains of Acinetobacter baumannii and two other microbes — Pseudomonas aeruginosa and Klebsiella pneumoniae — could soon produce a toll to rival MRSA’s.

The three bugs belong to a large category of bacteria called “gram-negative” that are especially hard to fight because they are wrapped in a double membrane and harbor enzymes that chew up many antibiotics. As dangerous as MRSA is, some antibiotics can still treat it, and more are in development, experts say.

But the drugs once used to treat gram-negative bacteria are becoming ineffective, and finding effective new ones is especially challenging.
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For the most part, gram-negative bacteria are hospital scourges — harmless to healthy people but ready to infect already-damaged tissue. The bacteria steal into the body via ventilator tubes, catheters, open wounds and burns, causing pneumonia, urinary tract infections, and bone, joint and bloodstream infections.

Pseudomonas is widely found in soil and water, and rarely causes problems except in hospitals.

Why Does Hair Turn Grey as We Age?

A team of European scientists have learned why our hair turns gray as we age. Despite the notion that gray hair is a sign of wisdom, these researchers show that going gray is caused by a massive build up of hydrogen peroxide due to wear and tear of our hair follicles. The peroxide winds up blocking the normal synthesis of melanin, our hair’s natural pigment.

“Not only blondes change their hair color with hydrogen peroxide,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “All of our hair cells make a tiny bit of hydrogen peroxide, but as we get older, this little bit becomes a lot. We bleach our hair pigment from within, and our hair turns gray and then white. This research, however, is an important first step to get at the root of the problem, so to speak.”

The researchers made this discovery by examining cell cultures of human hair follicles. They found that the build up of hydrogen peroxide was caused by a reduction of an enzyme that breaks up hydrogen peroxide into water and oxygen (catalase). They also discovered that hair follicles could not repair the damage caused by the hydrogen peroxide because of low levels of enzymes that normally serve this function (MSR A and B). Further complicating matters, the high levels of hydrogen peroxide and low levels of MSR A and B, disrupt the formation of an enzyme (tyrosinase) that leads to the production of melanin in hair follicles. Melanin is the pigment responsible for hair color, skin color, and eye color. The researchers speculate that a similar breakdown in the skin could be the root cause of vitiligo.

Weissmann added. “This study is a prime example of how basic research in biology can benefit us in ways never imagined.”

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Gene Duplication and Evolution

Roughly 10 million years ago, a major genetic change occurred in a common ancestor of gorillas, chimpanzees, and humans. Segments of DNA in its genome began to form duplicate copies at a greater rate than in the past, creating an instability that persists in the genome of modern humans and contributes to diseases like autism and schizophrenia. But that gene duplication also may be responsible for a genetic flexibility that has resulted in some uniquely human characteristics.

“Because of the architecture of the human genome, genetic material is constantly being added and deleted in certain regions,” says Howard Hughes Medical Institute investigator and University of Washington geneticist Evan Eichler, who led the project that uncovered the new findings. “These are really like volcanoes in the genome, blowing out pieces of DNA.”

Eichler and his colleagues focused on the genomes of four different species: macaques, orangutans, chimpanzees, and humans. All are descended from a single ancestral species that lived about 25 million years ago. The line leading to macaques broke off first, so that macaques are the most distantly related to humans in evolutionary terms. Orangutans, chimpanzees, and humans share a common ancestor that lived 12-16 million years ago. Chimps and humans are descended from a common ancestral species that lived about 6 million years ago.

By comparing the DNA sequences of the four species, Eichler and his colleagues identified gene duplications in the lineages leading to these species since they shared a common ancestor. They also were able to estimate when a duplication occurred from the number of species sharing that duplication. For example, a duplication observed in orangutan, chimpanzees, and humans but not in macaques must have occurred sometime after 25 million years ago but before the orangutan lineage branched off.

Eichler’s research team found an especially high rate of duplications in the ancestral species leading to chimps and humans, even though other mutational processes, such as changes in single DNA letters, were slowing down during this period.

Darwin’s Beetles Still Producing Surprises

As part of National Science Foundation-funded research on the evolution of male dimorphism in insects, biology professors J. Mark Rowland, UNM, and Douglas J. Emlen, UM, were surprised to find that many species of beetles are capable of producing not only two, but three different types of males.

The sex lives of animals is known to be complicated business. Where competition in mating is particularly intense, many kinds of animals produce enlarged weapons that function in male combat and utilize alternative tactics in deploying them. Such exaggerated structures include horns in dinosaurs and deer, and tusks in elephants and walrus.

Elaborate male weapons are also known to occur in many types of insects. Now it appears, as the research of Rowland and Emlen illustrates, that male weaponry and alternative mating tactics can be much more complex in the lives of beetles than previously imagined.

“We discovered a novel mating system in which the individual males of various species of beetles have the capacity to express one of three alternative morphologies,” said Rowland. “In many dung beetles , smaller males are unlikely to prevail in direct contests with alpha males. These beta males develop disproportionally smaller horns and employ alternative, less aggressive, reproductive tactics.

“The trimorphic species reported here have alpha, beta and gamma (completely hornless) male – three qualitatively distinct forms. A mating strategy with three such tactics implies considerable complexity, but may actually involve operational rules reminiscent of the old rock, paper, scissors game.”
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Extinct Ibex is Resurrected by Cloning

Extinct ibex is resurrected by cloning

The Pyrenean ibex, a form of wild mountain goat, was officially declared extinct in 2000 when the last-known animal of its kind was found dead in northern Spain. Shortly before its death, scientists preserved skin samples of the goat, a subspecies of the Spanish ibex that live in mountain ranges across the country, in liquid nitrogen.

Using DNA taken from these skin samples, the scientists were able to replace the genetic material in eggs from domestic goats, to clone a female Pyrenean ibex, or bucardo as they are known. It is the first time an extinct animal has been cloned.

Sadly, the newborn ibex kid died shortly after birth due to physical defects in its lungs. Other cloned animals, including sheep, have been born with similar lung defects. But the breakthrough has raised hopes that it will be possible to save endangered and newly extinct species by resurrecting them from frozen tissue.

It has also increased the possibility that it will one day be possible to reproduce long-dead species such as woolly mammoths and even dinosaurs.

An Artificial Nerve Networks

When neurons – brain nerve cells – are grown in culture, they don’t form complex ‘thinking’ networks. Moses, Feinerman and Rotem wondered whether the physical structure of the nerve network could be designed to be more brain-like. To simplify things, they grew a model nerve network in one dimension only – by getting the neurons to grow along a groove etched in a glass plate. The scientists found they could stimulate these nerve cells using a magnetic field (as opposed to other systems of lab-grown neurons that only react to electricity).

Experimenting further with the linear set-up, the group found that varying the width of the neuron stripe affected how well it would send signals. Nerve cells in the brain are connected to great numbers of other cells through their axons (long, thin extensions), and they must receive a minimum number of incoming signals before they fire one off in response. The researchers identified a threshold thickness, one that allowed the development of around 100 axons. Below this number, the chance of a response was iffy, while just a few over this number greatly raised the chance a signal would be passed on.

The scientists then took two thin stripes of around 100 axons each and created a logic gate similar to one in an electronic computer. Both of these ‘wires’ were connected to a small number of nerve cells. When the cells received a signal along just one of the ‘wires,’ the outcome was uncertain; but a signal sent along both ‘wires’ simultaneously was assured of a response. This type of structure is known as an AND gate. The next structure the team created was slightly more complex: Triangles fashioned from the neuron stripes were lined up in a row, point to rib, in a way that forced the axons to develop and send signals in one direction only. Several of these segmented shapes were then attached together in a loop to create a closed circuit. The regular relay of nerve signals around the circuit turned it into a sort of biological clock or pacemaker.

Moses: ‘We have been able to enforce simplicity on an inherently complicated system. Now we can ask, ‘What do nerve cells grown in culture require in order to be able to carry out complex calculations?’ As we find answers, we get closer to understanding the conditions needed for creating a synthetic, many-neuron ‘thinking’ apparatus.’

Full press release

Promoting Bio-Literacy

Wisconsin State Herbarium tries to ‘counteract bio-illiteracy’

“In a past century people could go outside and name the flowers or trees,” said Ken Cameron, the herbarium’s director. “Now you take a kid outside and the most they can say is, ‘It’s a tree.’ If we can get students in and get them excited, then I think we’ve helped to counteract bio-illiteracy.”
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Herbaria are becoming more of a rarity. And the UW-Madison has the third largest collection of any public university in the country, behind the universities of California and Michigan. At many universities, botany has been absorbed into large biology departments, and collections put into storage. That has not happened at UW-Madison.

“The combination of having a botany department and a big herbarium is getting pretty rare,” said David Baum, botany department chairman. “And more and more herbaria are closing or making the decision to move off campus into storage, which has a real negative effect on research.”

The University of Wisconsin-Madison Herbarium, founded in 1849 (the year the University was founded), is a museum collection of dried, labeled plants of state, national and international importance, which is used extensively for taxonomic and ecological research, as well as for teaching and public service. It contains the world’s largest collection of Wisconsin plants, about one-third of its 1,000,000 specimens having been collected within the state. Most of the world’s floras are well represented, and the holdings from certain areas, such as the Upper Midwest, eastern North America and western Mexico, are widely recognized as resources of global significance.