David Borchelt, a professor of neuroscience affiliated with the Evelyn F. and William L. McKnight Brain Institute of UF, emphasized the importance of verifying promising research results before investing in clinical studies or testing potential therapies in people. Bexarotene has known side effects that include effects on the liver, blood and other metabolic systems.

“We wanted to repeat the study to see if we could build on it, and we couldn’t,” he said. “We thought it was important that something like this, which got a lot of publicity and patients were immediately looking to try to get access to this drug, that it was important to publish the fact that we couldn’t reproduce the most exciting part of the study. Maybe there should be some caution going forward in regard to patients.”

Borchelt and Kevin Felsenstein, an associate professor of neuroscience, said a drug called bexarotene that their team orally administered to mice did not reduce amyloid plaques, waxy buildups on the brain that are a key culprit in Alzheimer’s disease. Their findings will be published in the May 24, 2013, issue of the journal Science magazine, with two additional articles detailing similar results from other researchers.

The research follows up on a 2012 Science article that claimed bexarotene had reversed Alzheimer’s-like symptoms in mice afflicted with the plaques. Authors of that study also administered the drug orally.

The paper “indicated that with as little as three days of treatment, they basically cleared the amyloid deposits from these animals, as well as restored cognitive abilities,” Felsenstein said of the 2012 paper.

He said the results of the original study were surprising, given decades of research that had failed to find a therapy successful in dismantling amyloid plaques.

“We can shut down the production of amyloid in these animal models and the deposits in these animal models don’t disappear,” Felsenstein said. “These deposits have been described by some as cement, and it will take a lot to get rid of them. The fact that something could actually make them disappear in literally a couple of days is — again — very remarkable.”

Interested to see how bexarotene might work to break down amyloid plaques, Felsenstein and Borchelt selected mice approximately the same age as those used in the 2012 study and orally administered the drug to the mice. Tests confirmed the drug had reached its target genes in the mice, and that it elevated levels of a protein called apolipoprotein E. Some scientists believe one of the forms of this protein may prevent the buildup of amyloid brain plaques in people who don’t have Alzheimer’s disease.

But elevated levels of the protein in the mice studied by UF researchers seemed to have no effect on the animals’ amyloid plaques. Samples taken after seven days of treatment with bexarotene showed no significant difference in the number or size of plaques in the animals’ brains. Two teams of researchers from other institutions also were unable to replicate the breakdown of amyloid plaques.

Felsenstein emphasized that his team does not claim the previous study indicating bexarotene’s effectiveness is “totally wrong.”

“We’re just saying right now it’s extremely difficult to replicate and there may be little nuances, that there’s something that we don’t quite understand,” he added. Felsenstein and Borchelt both work at UF’s Center for Translational Research in Neurodegenerative Disease.

The other two research groups who published papers in this week’s journal Science were led by Dr. Bart De Strooper, director of the VIB Center for the Biology of Disease in Belgium, and Sangram S. Sisodia, director of the Center for Molecular Neurobiology at the University of Chicago.

GAINESVILLE, Fla. — The University of Florida today unveiled the state’s most powerful supercomputer, a machine that will help researchers find life-saving drugs, make decades-long weather forecasts and improve armor for troops.

The HiPerGator supercomputer and recent tenfold increase in the size of the university’s data pipeline make UF one of the nation’s leading public universities in research computing.

“If we expect our researchers to be at the forefront of their fields, we need to make sure they have the most powerful tools available to science, and HiPerGator is one of those tools,” UF President Bernie Machen said. “The computer removes the physical limitations on what scientists and engineers can discover. It frees them to follow their imaginations wherever they lead.”

For UF immunologist David Ostrov, HiPerGator will slash a months-long test to identify safe drugs to a single eight-hour work day.

“HiPerGator can help get drugs get from the computer to the clinic more quickly. We want to discover and deliver safe, effective therapies that protect or restore people’s health as soon as we can,” Ostrov said. “UF’s supercomputer will allow me to spend my time on research instead of computing.”

The Dell machine has a peak speed of 150 trillion calculations per second. Put another way, if each calculation were a word in a book, HiPerGator could read the millions of volumes in UF libraries several hundred times per second.

UF worked with Dell, Terascala, Mellanox and AMD to build a machine that makes supercomputing power available to all UF faculty and their collaborators and spreads HiPerGator’s computing power over multiple simultaneous jobs instead of focused on a single task at warp speed. HiPerGator features the latest in high-performance computing technology from Dell and AMD with 16,384 processing cores; a Dell|Terascala HPC Storage Solution (DT-HSS 4.5) with the industry’s fastest open-source parallel file system; and Mellanox’s FDR 56Gb/s InfiniBand interconnects that provide the highest bandwidth and lowest latency. Together these features provide UF researchers unprecedented computation and faster access to data to quickly further their research.

UF unveiled HiPerGator on Tuesday as part of a ribbon-cutting ceremony for the 25,000-square-foot UF Data Center built to house it. HiPerGator was purchased and assembled for $3.4 million, and the Data Center was built for $15 million.

Also today, the university announced that it is the first in the nation to fully implement the Internet2 Innovation Platform, a combination of new technologies and services that will further speed research computing.

GAINESVILLE, Fla. — The University of Florida is the first university to fully connect to the Internet2 Innovation Platform’s three components, an achievement that will transform research at UF and provide a national model for research computing.

The move will allow UF researchers to easily share enormous amounts of data at ultrahigh speeds in collaborations with scientists worldwide.

“Universities across the country are following closely our progress and leadership in this area” said UF Vice President and Chief Information Officer Elias Eldayrie. “They are looking to our experience to learn from it, and we are glad to share it.”

About 30 other universities are working to fulfill the requirements to use the Internet2 Innovation Platform, which provides the advanced networking opportunities necessary for big data research, such as genome sequencing and climate studies.

“It’s exciting that the University of Florida is the first campus to complete the three components of the Internet2 Innovation Platform. Re-architecting the University of Florida network to support software-defined networking, 100G abundant bandwidth and unique support for data-intensive science positions Florida for a new cycle of growth and scientific research,” said Rob Vietzke, Internet2 vice president of network services.

“As other universities also follow Florida’s lead to provide researchers advanced networks with their collaborators and the increased capacity of this unique 100 gigabit per second nationwide network, we can expect new scientific, educational, and economic breakthroughs,” Vietzke said. “The whole academy of higher education can look forward to seeing how Florida innovators and researchers will use this Internet2 Innovation Platform to develop new applications and services never previously possible.”

The Internet2 Innovation Platform provides a high-speed, friction-free computing environment and requires universities that participate to commit to three changes in research computing architecture.

UF is the first to achieve all three: a 100 Gbps connection to Internet2, a Science DMZ, and use of software-defined networking, or SDN.

UF activated its ultra-high-speed 100 Gbps connection in January, a 10-fold expansion of the research standard, 10 Gbps. Only three other institutions are connected to Internet2 at that speed.

UF is a pioneer in the Science DMZ arena, and at a recent Internet2 Innovation Platform meeting was bombarded with questions from other universities about how to make it work, Eldayrie said.

“The University of Florida has led in the DMZ area since 2004 and can provide an example for research that requires this technology,” Eldayrie said.

The Science DMZ separates university administrative computing – transcripts and payrolls, for instance – from research computing, which requires a free flow of information without cumbersome firewalls and switches. UF has had a Science DMZ since 2004, but recently upgraded it from 20 Gbps to 200 Gbps.

Erik Deumens, director of research computing, said the Science DMZ functions as a dedicated network for research on campus, providing a kind of “HOV (high-occupancy-vehicle) lane for research.”

The third requirement was software-defined networking, which allows a researcher to program a network so a colleague anywhere on that network can view, share and manipulate data. SDN solves the problem of getting a variety of machines used by different scientists to talk to each other and ends the days of scientists filling portable hard drives with data and shipping them to collaborators.

Deumens said one of the requirements of participation in the Innovation Platform is to test the limits of SDN, which UF will do this summer in collaboration with Fermilab, a high-energy particle physics laboratory near Chicago.

“We will do a high-bandwidth data transfer with Fermilab, test the technology, and see what lessons we learn,” Deumens said.

On the commodity Internet, Deumens said, information travels in small packets that sometimes take odd detours and a long time to reach a destination, making huge datasets a problem. SDN allows a researcher to tell a switch at a routing station, “I’m going to send a packet, and a billion more will follow, and I want you to treat them all the same way, let them all through, quickly,” Deumens said.

UF is already a key collaborator on several big data projects and one of the top five institutions in contributing computing power to verifying the massive datasets associated with the Higgs-Boson particle discovery. In just one month last year, UF contributed 1,419,000 hours of computing to that project.

“Our researchers now have tools at their disposal that no one else in the country has. They can lead the big data conversation, and this computing infrastructure will give them a competitive advantage in securing funding,” Eldayrie said. “We can recruit the best minds in the world.”

Added Deumens: “Our researchers can think up things they couldn’t imagine without this infrastructure.”

The expansion of research computing on the Internet2 Innovation Platform could have a mind-boggling economic benefit. The original investment in the commodity internet was $400 million over several years. Today, the Internet accounts for more than a trillion dollars a year in economic activity, Vietzke said.

DNA nanotechnology holds great promise as a new way to deliver chemotherapy directly to cancer cells, but until now, scientists have not been able to direct nanotherapies to consistently differentiate cancer cells from healthy ones. Other limiting factors include high costs, too-small amounts of drugs delivered and potential toxic side effects.

“Most nanotechnology relies on a nanoparticle approach, and the particles are made of inorganic materials; after they’ve been used as a carrier for the drug, they’ll be left inside the body,” said the study’s lead investigator, Weihong Tan, a UF distinguished professor of chemistry, professor of physiology and functional genomics, and a member of the UF Shands Cancer Center and the UF Genetics Institute. “Compared to existing nanostructures, our nanotrain is easier and cheaper to make, is highly specific to cancer cells, has a lot of drug-loading power and is very much biocompatible.”

Described in today’s issue of the Proceedings of the National Academy of Sciences, Tan’s DNA nanotrain is a three-dimensional structure composed of short strands of DNA tethered together into one long train. On the end of the nanotrain is an aptamer, a tiny piece of nucleic acid serving as the train’s “locomotive” on biochemical autopilot to home in on and bind to specific cancer cells. Trailing behind are tethered DNA structures that serve as side-by-side, high-capacity “box cars,” transporting bioimaging agents or drug cargos to their targets.

“The beauty of the nanotrain is that by using different disease biomarkers you can hitch different types of DNA probes as the train’s ‘locomotive’ to recognize and target different types of cancers,” Tan said. “We’ve precisely targeted leukemia, lung and liver cancer cells, and because the DNA probes are
so precise in targeting only specific types of cancer cells we’ve seen dramatic reduction in drug toxicity in comparison to standard chemotherapies, which don’t discriminate well between cancerous and healthy cells.”

Tan and his colleagues report that the DNA nanotrains can be cost-effectively made by mixing bits of DNA in a liquid medium. The mixture is then exposed to a compound that stimulates the pieces of DNA to seek each other out and self-assemble into the DNA nanotrains. The type of cancer cell the DNA nanotrain will seek out and destroy is determined by the specific compound added to the mixture as the trigger.

The study demonstrated in vitro and in mice that the DNA nanotrains exclusively target the cancer cells for which their probes were programmed. The DNA probes go straight to the cancer cells, leading the nanotrains to dock on the cell membranes and gain entry into the cells. Once inside, the drug payloads disperse, killing the cancer cells, a process Tan and his team monitored in real time by measuring the amount of fluorescent light emitted. The biodegradable components of the DNA nanotrains decay with the dead cancer cells and are removed by the body’s normal housekeeping mechanisms.

“Our study found that when loaded with anticancer drugs, these nanotrains inhibited tumor growth in mice more than in those that received drugs injected freely into the bloodstream. What’s more exciting is that the mice treated with these nanotrains suffered dramatically fewer side effects than those treated with free drugs,” said Guizhi Zhu, a UF doctoral student who was instrumental in the study. “This is what we aim to achieve for future clinical health care of cancer patients.”

In addition to longer survival and inhibited tumor growth, the mice that were treated with nanotrain drug delivery experienced less weight loss and are in better condition physically than both the mice that received injected therapy and the mouse control group that received no treatment. Tan and his team attribute these improved outcomes to greatly reduced toxicity achieved by the targeted nanotrain drug delivery.

“We think we have demonstrated that these DNA nanotrains are a promising targeted drug transport platform for delivery of cancer chemotherapeutics with very low toxicity to healthy tissues, and that the platform has wide application for many different cancer types,” Tan said. “Moving forward, we are working to identify optimum dosage using mouse models for T-cell leukemia, lung and liver cancers and triple negative breast cancer.

“It’s very exciting, but we still have a long way to go before human trials,” he said.

With nearly 175,000 described species serving as herbivores, pollinators and prey, Lepidoptera affect humans as agricultural pests and essential pollinators for production of many food crops, said co-author Akito Kawahara, assistant curator of Lepidoptera at the Florida Museum of Natural History’s McGuire Center for Lepidoptera and Biodiversity on the UF campus.

“The new study provides one of our best estimates of the evolutionary relationships of butterflies and moths,” Kawahara said. “When trying to conserve a butterfly or moth species, the biology of that particular species might not be well known because it’s so rare, but if you have a family tree, you can infer these traits based on closely related species.”

The study, funded by the National Science Foundation’s Assembling the Tree of Life program, was authored by 16 researchers from five countries. The researchers collected and analyzed DNA sequences of 483 taxa spanning 115 families of the Ditrysia group, which comprises about 98 percent of described butterfly and moth species. Each specimen was chosen to represent a major family of butterflies or moths.

Kawahara collected specimens and assisted with DNA sequence analysis as a doctoral candidate at the University of Maryland. Published online in the journal PLOS One March 12, the study shows molecular evidence broadly supports the relationships determined by analyzing physical features, but more extensive data is needed to gain complete understanding of Lepidoptera evolution, Kawahara said.

“A big chunk of the tree is still largely uncertain,” Kawahara said. “The collaborative team has made major headway, but there’s still more to do.”

Humans depend on the ocean for food, medicine, transportation and recreation, yet little is known about how these vast ecosystems spanning 70 percent of the Earth’s surface are functioning and changing. Following a workshop sponsored by U.S. federal agencies in 2010, researchers at eight institutions have proposed a blueprint for establishing a cooperative marine biodiversity observation network to monitor trends in marine ecosystem health and the distribution and abundance of oceanic life. The research will appear online in BioScience Thursday and in the journal’s May print issue.

Biodiversity observation networks are indispensible tools, allowing scientists to follow and predict ecosystem changes to facilitate proactive responses to environmental pressures, said study co-author Gustav Paulay, invertebrate zoology curator at the Florida Museum of Natural History on the UF campus.

“Biodiversity is important not only because it’s what the natural world is about, but also because tracking it tells you how healthy things are,” Paulay said. “As an indicator of ecosystem health and resilience, biodiversity is key for sustaining oceans that face accelerating environmental change.”

Experts determined a national marine biodiversity observation network could be established using existing technology within five years with appropriate funding and collaboration, but the effort requires strong leadership to integrate all the necessary elements, Paulay said. The study provides a series of recommendations, including coordination of existing efforts, digitization of historical data — including vast museum collections – and establishment of regional centers to process and identify specimens.

“Tracking diversity is not just about tracking fish, or whales, or corals, but everything,” Paulay said. “To date, there have been few attempts to track biodiversity broadly in the ocean.”

From tiny phytoplankton and massive marine mammals to awe-inspiring sea dragons and ancient reefs, every element is important for healthy ecosystems, Paulay said.

Outside the U.S., efforts to create a marine biodiversity observation network have begun regionally in New Zealand and the European Union. The Smithsonian Institution also launched the first worldwide network of coastal field sites in 2012, a long-term project to monitor the ocean’s coastal ecosystems.

Jim Carlton, a professor at Williams College in Massachusetts and director of the Maritime Studies Program of Williams College and Mystic Seaport, said the concept of a marine network is critical because elements are inter-related, from water quality and issues with fisheries to the regular arrival of new invasive species.

“It’s rather amazing that in 2013, we don’t have a well-established marine biodiversity network — how could we not?” said Carlton, who is not involved with the study. “All coasts around the world are changing and we have a remarkably poor understanding about the extent of that change in many areas.”

People are more dependent on oceans than they may realize, and without a coordinated network, researchers will not know how to manage these ecosystems, he said.

“The oceans are feeding hundreds of millions of people, they control the Earth’s climate, 90 percent of all world goods travel on the ocean and most people in the world live within 100 miles of the sea,” Carlton said. “For recreation, we rely on the fact that we can go to a beach and not get sick. We depend upon a huge amount of these resources in ways that we often don’t know, but it really means maintaining the health of the ocean.”

Divers have witnessed the effects of climate change most clearly on coral reefs, whose delicate ecology is highly sensitive to changes in maximum ocean temperatures, Paulay said.

“The scale of change was driven home to me in Palau in 1998, during a survey soon after the 1998 Pacific-wide warming event,” Paulay said. “Palau is one of the gems of the world in terms of marine environments and reef diversity. When we returned to sites that once had acre upon acre of vibrant staghorn and bottlebrush corals covering the bottom, we found but a desert of dead skeletons — mortality was virtually 100 percent.”

Study co-authors include Emmett Duffy of the College of William and Mary, Linda Amaral-Zettler of the Marine Biological Laboratory in Woods Hole, Mass., Daphne Fautin of the University of Kansas, Tatiana Rynearson of the University of Rhode Island, Heidi Sosik of the Woods Hole Oceanographic Institution, and John Stachowicz of the University of California, Davis.

GAINESVILLE, Fla. — Crops aren’t just for food, fiber and fuel. Researchers at the University of Florida are making new industrial applications possible for them as well.

They’ve developed a method to turn sugarcane bagasse — the crushed-stalk waste product of sugar production — into succinic acid that can be used to make pharmaceuticals, protective coatings and compostable bags.

The process uses no food crops or petroleum as raw materials. In contrast, most currently produced succinic acid is petroleum derived. The research is detailed in a study in the March 5 issue of the journal Proceedings of the National Academy of Sciences.

“I believe renewable chemicals will be at least a part of the future of our chemical industry, if we want to decrease the demand for petroleum,” said Xuan Wang, the study’s lead author and an assistant scientist in UF’s microbiology and cell science department.

Renewable chemicals are created from materials that can be replenished, whereas nonrenewable chemicals are produced from limited resources, such as petroleum.

The research is part of a larger project led by Lonnie Ingram, a distinguished professor in the department and a member of UF’s Institute of Food and Agricultural Sciences. His work seeks to turn discarded plant material, as well as sugars produced from crops such as sweet sorghum, into fuel and renewable products in a cost-effective and economically viable manner.

Key to the research are E. coli bacteria that Ingram and his team have genetically engineered to produce specific products by fermenting sugar. The team’s previous accomplishments include E. coli strains that can produce fuel ethanol and ones that make lactic acid, which is used to create biodegradable and recyclable bioplastics.

To achieve cost-effective succinic acid production using waste plant materials, however, the researchers had to make an E. coli strain tolerant to growth-stopping inhibitors. The newly engineered strain, called XW 136, produced more than 30 grams per liter of succinate using sugars derived from sugarcane bagasse.

This was the first time succinic acid production from sugarcane bagasse had been achieved without the use of expensive and cost-prohibitive steps to remove the inhibitors, Wang said.

“The inhibitors produced from waste plant materials are barriers for the industrial chemical production using renewable sources,” Wang said. “Now our work provides a direction for effectively improving inhibitor tolerance.”

The ethanol production technology from Ingram’s research team, including the genetically engineered bacteria, is currently in use in fuel plants in Florida, Louisiana and Japan. Microorganisms the team has engineered to make bioplastics are being used in facilities in Louisiana and Spain.

Although many birds perished or became displaced during a mass extinction event following the first arrival of humans to the Caribbean islands, fossil evidence shows some species were more resilient than others. The research provides range and dispersal patterns from A.D. 600 to 1600 that may be used to create conservation plans for tropical mountainous regions, some of the most threatened habitats worldwide. Understanding what caused recent extinctions – whether direct habitat loss or introduction of invasive species — helps researchers predict future ecological impacts. The study was published online in The Holocene March 12 and is scheduled to appear in the journal’s print edition in July.

“People arrive about 6,000 years ago and within a millennium or two, you lose the big, spectacular critters — the ground sloths, the monkeys, the biggest rodents and some of the big extinct birds, like giant owls and eagles,” said lead author David Steadman, ornithology curator at the Florida Museum of Natural History on the UF campus. “We have some bird species from our fossil site that, from a modern standpoint, are just as extinct as the others, but in fact, they almost were able to survive longer. That helps give us a gauge on what the future might bring.”

Researchers used comparisons with modern bones to identify 23 species from the 4,857 bird fossils excavated from Trouing Jean Paul, a cave in southeast Haiti at an elevation of about 6,000 feet. The most common bird species include the Zenaida Dove, the Black Swift, the Least Pauraque, the Hispaniolan woodpecker and a new, undescribed extinct woodcock in the genus Scolopax. Researchers believe the woodcock became extinct between A.D. 1350 and 1800, surviving the first arrival of the Amerindians 6,000 years ago, but dying off following the arrival of Europeans and African peoples in 1492, Steadman said.

“When you take a look at what could’ve caused this, it really does just keep pointing to humans,” Steadman said. “I just think it’s habitat loss from people and introduction of non-native, invasive plants and animals. It’s the same thing we’re dealing with in Florida now — who knows what the pythons are going to wipe out in the Everglades.”

Researchers radiocarbon-dated six individual bones from the extinct woodcock to determine the site’s age. Because the locality also includes fossils of frogs, lizards, snakes, bats and rodents, in addition to the Common Barn Owl and Ashy-faced Owl, it was likely a roost where owls deposited boney pellets of their prey, scientists said.

Of the present-day species found at the site, as many as one-third are considered threatened today and four of the 23 total species are no longer found in the area. Their predominant habitat was pine forests, which are mostly disturbed today or entirely cut down for agriculture. The Least Pauraque, a type of nightjar, is now an endangered species that lives in an extremely localized area, Steadman said.

“This gives us some evidence of how drastic the range contraction was of this species — the Least Pauraque not only lived in the mountains, it was common there,” Steadman said. “Within 1,000 years, it’s lost most of its range and most of its population. From the standpoint of evolution, if we want that species to ever have the opportunity to evolve through time, we need to be concerned with time intervals that are measured in centuries and millennia, not just decades.”

Jim Mead, professor and chair of the department of geosciences at East Tennessee State University, said the research is important because the direct radiocarbon dating represents a much later time period than the arrival of the first Amerindians.

“What Steadman is finding, more often than not, is that we as people bring in other things with us and indirectly wipe out other animals,” said Mead, who was not involved with the study. “He’s providing background data and I think that’s critical to Hispaniola because you have two countries on that island and they’re quite different culturally and economically, so those countries are going to play different games on the local fauna.”

Mead said it is also significant that Trouing Jean Paul occurs at a high elevation, where human or climate pressures could result in animals finding a “refugia” upslope.

“Typically, a lot of sites are found in lower elevation, or we go to the lower elevations to look at localities we work on,” Mead said. “But Dave is saying, ‘Why don’t we look at these other areas that haven’t really been examined?’ This one cave is a critical one for that. It gives us a 3-D look at environments on an island.”

Oona Takano, who helped sort and identify the specimens as a UF undergraduate student, is a study co-author.

The 5-million-year-old fossils belong to the same lineage as the famous Smilodon fatalis from the La Brea Tar Pits in Los Angeles, a large, carnivorous apex predator with elongated upper canine teeth. Previous research suggested the group of saber-toothed cats known as Smilodontini originated in the Old World and then migrated to North America, but the age of the new species indicates the group likely originated in North America. The study appeared online in the journal PLOS One Wednesday.

“Smilodon first shows up on the fossil record around 2.5 million years ago, but there haven’t been a lot of good intermediate forms for understanding where it came from,” said study co-author Richard Hulbert Jr., vertebrate paleontology collections manager at the Florida Museum of Natural History on the UF campus. “The new species shows that the most famous saber-toothed cat, Smilodon, had a New World origin and it and its ancestors lived in the southeastern U.S. for at least 5 million years before their extinction about 11,000 years ago. Compared to what we knew about these earlier saber-toothed cats 20 or 30 years ago, we now have a much better understanding of this group.”

Hulbert helped uncover fossils of the new genus and species, Rhizosmilodon fiteae, from a phosphate mine during excavations in 1990. The species was named after Barbara Fite of Lutz, Fla., who in 2011 donated one of the critical specimens used for the new description and allowed UF scientists to make casts of two other partial jaws in her collection.

The donation was a major contribution to the research because the remarkably well-preserved lower jaw contains almost pristine examples of all three chewing teeth, Hulbert said. The genus name Rhizosmilodon, meaning “root of Smilodon,” implies the animal could be a missing link and direct ancestor of Smilodon, which became extinct about 11,000 years ago.

The study’s lead author, Steven Wallace, an associate professor in the department of geosciences and member of the Don Sundquist Center of Excellence in Paleontology at East Tennessee State University, used comparative analysis of saber-toothed cat anatomy to help determine the animal’s taxonomy. The analysis was primarily based on structure of the animal’s lower jaw and teeth, smaller than the Smilodon and about the size of a modern Florida panther.

“The taxonomy of this animal was controversial because when it was first published 20 years ago, they only had one partial, somewhat-decent lower jaw, and it was missing some of the critical features,” Hulbert said. “We now have more complete specimens showing it has a mixture of primitive and advanced characters, and does not match any previously named saber-toothed cat genus or species.”

Originally misidentified as a member of the genus Megantereon in the early 1980s, Rhizosmilodon is instead the sister taxon to Megantereon and Smilodon, and the oldest of the group. These three cats are in the same tribe — meaning they are more closely related than a family or subfamily — and are often called as saber-toothed cats because of their long canine teeth, Hulbert said.

“When people think of saber-toothed cats, they think of it as just one thing, as if the famous tar pit saber-toothed cat was the only species, when in fact, it was an almost worldwide radiation of cats that lasted over 10 million years and probably had a total of about 20 valid species,” Hulbert said. “Counting the newly described animal, there are now six different species of saber-toothed cats known just from Florida.”

Saber-toothed cat expert Julie Meachen, an instructor at Marshall University School of Medicine in Huntington, W. Va., said the study helps settle the debate about whether the tribe arose from the Eurasia before coming to North America.

“I think that this revision was well-needed,” Meachen said. “The fact that it’s one of the oldest lineages is really interesting because that means that this exciting group of saber-toothed cats really is a North American tribe — it evolved and persisted in North America.”

Since 1915, more than 60 new species of reptiles, birds and mammals have been named from Central Florida phosphate mines, located southeast of Tampa and south of Lakeland. Rhizosmilodon lived in a forested coastal habitat that was also home to rhinos, tapirs, three-toed horses, peccaries, llamas and deer. Its relatively small size probably allowed it to climb trees and safely hide captured prey from large carnivores, such as packs of wolf-sized hyena-dogs and an extinct type of bear larger than the modern grizzly.

Since the time of Darwin 150 years ago, researchers have believed large predators like birds mainly influenced the evolution of coloration in butterflies. In the first behavioral study to directly test the defense mechanism of hairstreak butterflies, UF lepidopterist Andrei Sourakov found that the appearance of a false head – a wing pattern found on hundreds of hairstreak butterflies worldwide – was 100 percent effective against attacks from a jumping spider. The research published online March 8 in the Journal of Natural History shows small arthropods, rather than large vertebrate predators, may influence butterfly evolution.

“Everything we observe out there has been blamed on birds: aposematic coloration, mimicry and various defensive patterns like eyespots,” said study author Andrei Sourakov, a collection coordinator at the Florida Museum of Natural History’s McGuire Center for Lepidoptera and Biodiversity on the UF campus. “It’s a big step in general and a big leap of faith to realize that a creature as tiny as a jumping spider, whose brain and life span are really small compared to birds, can actually be partially responsible for the great diversity of patterns that evolved out there among Lepidoptera and other insects.”

Sourakov’s behavioral experiments at the McGuire Center showed the Red-banded Hairstreak butterfly, Calycopis cecrops, whose spots and tail imitate a false head, successfully escaped all 16 attacks from the jumping spider, Phidippus pulcherrimus. When 11 other butterfly and moth species from seven different families were exposed to the jumping spider, they were unable to escape attack in every case. Sourakov videotaped the experiments and analyzed the results in slow motion.

“From the video, you can see the spider is always very precise,” Sourakov said. “In one video, the spider sees a moth that looks like a leaf and it walks very carefully around to the head and then jumps at the head region. The spider has an innate or acquired ability to distinguish the head region very well and it always attacks there to deliver its venom to the vital center to instantly paralyze the prey. Most importantly, the spider is very small, so sometimes its prey is 10 times larger.”

The species of hairstreak butterfly and jumping spider used in the experiment are both common in the southeastern U.S., with similar relatives spread worldwide. In nature, the spider and hairstreak come into contact when the butterfly lands on leaves or flowers to rest and feed. Female red-banded hairstreak butterflies lay their eggs in leaf litters, which are often crawling with spiders.

David Wagner, a professor of ecology and evolutionary biology at the University of Connecticut who was not involved with the study, said the research shows scientists need to rethink what drives adaptive coloration patterns because the results suggest that “birds are only part of the story.”

“I’m just so impressed with Andrei’s experimental protocol and the fact that the jumping spider could not catch the hairstreak butterflies,” Wagner said. “His empirical study will do much to cause us to rethink the vision and the visual acuity that certain invertebrate predators have when hunting their prey and how this has really molded how some organisms not only look like, but perhaps how they act, as well.”

Unlike other butterflies, hairstreaks constantly move the hind wings that carry the false head pattern, a behavior that seems to increase in the presence of the spider, as if the butterfly is attracting attention to itself, Sourakov said. In museum collections, hairstreak specimens are frequently found with the false-head portion of the wings missing. During the experiments, the spider always attacked the butterfly’s false head, thereby avoiding its vital organs.

“The false head hypothesis in hairstreaks has been in circulation for a long time because people always speculated that their tails move around in order to fake out the predators, but there was little experimental evidence,” Sourakov said.

Sourakov said he hopes the study encourages behavioral ecologists to further test the idea that evolution in butterflies and moths may be driven by small invertebrate predators.

“This clearly shows it’s possible that many spectacular patterns that we find in smaller insects may be due to spider pressure rather than bird pressure,” Sourakov said. “The butterfly escapes from the spider – it’s a fairytale story.”

The two new ancient extinct alligator-like animals and an extinct hippo-like species inhabited Central America during the Miocene about 20 million years ago. The research expands the range of ancient animals in the subtropics — some of the most diverse areas today about which little is known historically because lush vegetation prevents paleontological excavations — and may be used to better understand how climate change affects species dispersal today. The two studies appear online today in the same issue of the Journal of Vertebrate Paleontology.

The fossils shed new light on scientists’ understanding of species distribution because they represent a time before the formation of the Isthmus of Panama, when the continents of North and South America were separated by oceanic waters.

“In part we are trying to understand how ecosystems have responded to animals moving long distances and across geographic barriers in the past,” said study co-author Jonathan Bloch, associate curator of vertebrate paleontology at the Florida Museum of Natural History on the UF campus. “It’s a testing ground for things like invasive species – if you have things that migrated from one place into another in the past, then potentially you have the ability to look at what impact a new species might have on an ecosystem in the future.”

The research was funded by the National Science Foundation Panama Canal Partnerships in International Research and Education project, which supports paleontological excavation of the canal during construction expected to continue through 2014.

“We’re very fortunate we could get the funding for PIRE to take advantage of this opportunity — we’re getting to sample these areas that are completely unsampled,” said Alex Hastings, lead author of the crocodilian study and a visiting instructor at Georgia Southern University who conducted the research for the project as a UF graduate student.

Researchers analyzed all known crocodilian fossils from the Panama Canal, including the oldest records of Central American caimans, which are cousins of alligators. The more primitive species, named Culebrasuchus mesoamericanus, may represent an evolutionary transition between caimans and alligators, Hastings said.

“You mix an alligator and one of the more primitive caimans and you end up with this caiman that has a much flatter snout, making it more like an alligator,” Hastings said. “Before this, there were no fossil crocodilian skulls known from Central America.”

Christopher Brochu, an assistant professor of vertebrate paleontology in the department of geoscience at the University of Iowa, said “the caiman fossil record is tantalizing,” and the new data shows there is still a long way to go before researchers understand the group.

“The fossils that are in this paper are from a later time period, but some of them appear to be earlier-branching groups, which could be very important,” said Brochu, who was not involved with the study. “The problem is, because we know so little about early caiman history, it’s very difficult to tell where these later forms actually go on the family tree.”

The new mammal species researchers described is an anthracothere, Arretotherium meridionale, an even-toed hooved mammal previously thought to be related to living hippos and intensively studied on the basis of its hypothetical relationship with whales. About the size of a cow, the mammal would have lived in a semi-aquatic environment in Central America, said lead author and UF graduate student Aldo Rincon.

“With the evolution of new terrestrial corridors like this peninsula connecting North America with Central America, this is one of the most amazing examples of the different kind of paths land animals can take,” Rincon said. “Somehow this anthracothere is similar to anthracotheres from other continents like northern Africa and northeastern Asia.”

Researchers also name a second crocodilian species, Centenariosuchus gilmorei, after Charles Gilmore, who first reported evidence of crocodilian fossils collected during construction of the canal 100 years ago. The genus is named in honor of the canal’s centennial in 2014.

Researchers will continue excavating deposits from the Panama Canal during construction to widen and straighten the channel and build new locks. The project is funded by a $3.8 million NSF grant to develop partnerships between the U.S. and Panama and engage the next generation of scientists in paleontological and geological discoveries along the canal.

Study co-authors include Bruce MacFadden of UF and Carlos Jaramillo of the Smithsonian Tropical Research Institute.

Female yellow fever mosquitoes sometimes contend with the courtship and mating efforts of males from another, competing species — the Asian tiger mosquito.

She’s naïve, he’s sneaky. Both species spread dengue, a viral disease that’s a major human health threat.

In an ironic turnabout, Florida dengue cases may rise in the near future due to female yellow fever mosquitoes becoming savvy about the false-flag suitors, leading to increased yellow fever mosquito populations, says an expert with the University of Florida’s Institute of Food and Agricultural Sciences.

When male Asian tiger mosquitoes successfully deceive yellow fever females, their matings are fruitless – the two species can’t produce offspring together, said Phil Lounibos, a distinguished professor of entomology with UF’s Florida Medical Entomology Laboratory in Vero Beach. Instead, chemicals transferred during mating render the yellow fever female sterile for the rest of her short life.

Scientists believe this phenomenon, called satyrization, helps explain how the Asian tiger mosquito quickly became established throughout the Southeastern U.S. in the 1980s.

If satyrization happens hundreds or thousands of times in a place where both species share habitat, the net result is fewer yellow fever mosquito eggs being laid. Ultimately, satyrization reduces yellow fever mosquito populations, leaving more ecological “space” for the Asian tiger to occupy, Lounibos said.

Both mosquitoes are container-nesting species that seek water trapped in old tires, flowerpots, cup-shaped plants and the like. Both eagerly prey on humans, and are long associated with human communities. Both are invasive and annoying to Florida residents.

And, because they can transmit human disease, both species are public-health concerns. But yellow fever mosquitoes are believed to be more efficient than Asian tigers at transmitting pathogens to people.

A paper published in the Feb. 19 issue of the journal Proceedings of the National Academy of Sciences describes laboratory experiments suggesting that female yellow fever mosquitoes may develop an ability to spurn advances from Asian tiger males.

“We don’t know that they are better able to discriminate between males of their own species and Asian tigers,” said Lounibos, one of the paper’s authors. “What we can say is, females from colonies that have a history of exposure to Asian tiger males are less likely to mate with Asian tiger males.”

The exact reason the females manage to avoid deception is unknown, he said.

“It may be that some subtle nuance in the behavior of the yellow fever females is involved,” said Lounibos, at the Florida Medical Entomology Laboratory in Vero Beach.

He also noted that if female yellow fever mosquitoes can rapidly evolve an aversion to Asian tiger males in the wild, then perhaps diminished yellow fever mosquito populations would gradually rebound.

Lounibos said he has received anecdotal reports of greater yellow fever mosquito presence in some South Florida locales.

Currently, the major health concern associated with the yellow fever mosquito is dengue. It causes severe flu-like symptoms, including fever, muscle and joint pain, headache, and possibly gastrointestinal issues. In the past few years, dengue has become a significant public health issue in South Florida, particularly the Keys.

Resurgent populations of yellow fever mosquitoes could lead to more dengue cases, Lounibos said, so one of his objectives for the near future is to investigate some of the areas where yellow fever mosquitoes are said to be making a comeback.

In the study, Lounibos and colleagues set up laboratory experiments in which various male/female pairings of mosquitoes could mingle and possibly mate.

The results showed that, on average, mating was about three times as likely between female yellow fever mosquitoes and male Asian tigers, compared with female Asian tigers and male yellow fever mosquitoes.

Yellow fever females from colonies that had never encountered Asian tiger mosquitoes were tricked about 25 percent more often, compared with females from colonies that had a history of co-existing with Asian tiger colonies.

The other research team members were postdoctoral associate Irka Bargielowski and doctoral student Maria Cristina Carrasquilla, both with FMEL.

Hundreds of millions of head louse infestations affect children worldwide every year and numbers continue to rise, partly due to resistance to insecticidal shampoos. The study appearing online in the journal PLOS One today is the first to analyze nuclear genetic variation of head lice, providing a more complete evolutionary history of the parasite. Understanding genetic structure worldwide allows researchers to make insecticides tailored to a particular population, because control methods effective in one region may not be successful in others.

“Insect populations will develop resistance to insecticides in different ways and to create an effective management plan, you need to take into consideration the genetic profiles of these populations,” said lead author Marina Ascunce, a postdoctoral associate with the Florida Museum of Natural History on the UF campus. “If these populations have high gene flow, you may need to apply a different treatment than if you have populations that are not migrating among each other.”

The two-year study is part of a long-term project to better understand human evolution and migration patterns throughout history, such as the possible interaction between Neanderthals and modern humans, Ascunce said.

“The nucleus is really telling us the history of the species as a whole,” said Ascunce, who is also affiliated with UF’s biology department. “It’s a very host-specific parasite and this is telling us we can compare lice with human genetic data.”

Researchers analyzed nuclear genetic variation in 93 human lice from 11 sites in four regions: North America, Central America, Asia and Europe. Using 15 newly developed microsatellite loci, or molecular markers, which identify a particular sequence of DNA, scientists discovered the genetic variation of head lice is greater than expected, Ascunce said.

“When we started this project, we thought, ‘Well, humans move all over the globe like crazy,’ ” Ascunce said. “However, this doesn’t impact the genetic structure of the lice, because you get different genetic structures for each geographic region. For example, a louse from Europe will have a genetic profile that is different from a louse from Central America.”

In the analysis, lice were grouped into genetic clusters to see which geographic populations were most closely related. Unexpected similarities were seen in lice from distant locations, Ascunce said.

“Geographically, the U.S. and Honduras are closer together, but genetically, Honduras is closer to Asia,” Ascunce said. “This is showing us that the lice from Honduras were probably brought from Asia when the first people arrived in the Americas.”

Lice from New York showed similarities with those from the United Kingdom and Norway, while lice from Nepal seem to be in between those from Canada and Cambodia.

Because previous research had only been mitochondrial, the study is a good first step toward understanding the nuclear and genomic-wide diversity of lice, said molecular anthropologist Drew Kitchen, an assistant professor at Iowa State University, who was not affiliated with the research.

“The structure of head lice around the world seems to match the structure of human populations, as well,” he said. “That further affirms the co-evolutionary history of human head lice and human populations.”

The study also includes analysis of clothing lice from Canada and Nepal, showing there may be gene flow between clothing and head lice. Study co-authors hope to continue this analysis because clothing lice make bacteria linked to certain diseases, including typhus, trench fever and relapsing fever, Ascunce said. More than 50 researchers worldwide collect and send lice to the Florida Museum of Natural History for the project.

“We really need to understand if there is gene flow between clothing and head lice and how that could potentially represent a risk of epidemic diseases in head lice,” Ascunce said. “One of these bacteria was recently found in head lice in Nepal, the U.S. and Ethiopia.”

Study co-author David Reed, associate curator of mammals at the Florida Museum of Natural History, is the project’s principal investigator. Other co-authors include Melissa Toups of Indiana University, Gebreyes Kassu and Jackie Fane of UF and Katlyn Scholl, all previously with the Florida Museum of Natural History.

Researchers Andrew Tatem and Christina Chiyaka found that those countries that have eliminated malaria have maintained their malaria-free states with remarkable stability, going against traditional theory. Between 1945 and 2010, 79 countries eliminated malaria and 75, or 95 percent, remained malaria-free, shrinking the geographic range of the disease, the researchers said.

For the 99 countries with endemic malaria today, the research by Tatem and his colleagues has important implications for tackling the problem. The elimination of malaria may be less costly to achieve and maintain than previously thought, Tatem said.

“Traditional theory suggests that we have to get rid of malaria completely, all across the world, all at around the same time, to keep new cases from being imported and starting outbreaks in elimination countries all over again,” said Tatem, who conducted the research at UF and now is a professor at the University of Southampton in the United Kingdom. Chiyaka also has moved to the United Kingdom with her family.

The researchers found, however, that malaria elimination may be a ‘sticky state,’ meaning that once elimination is achieved, resurgence becomes a rare event.

“For instance, the United States imports 1,500 cases of malaria per year but has seen very few local outbreaks resulting from these, despite still having mosquitoes capable of spreading malaria,” Tatem said. “The United States doesn’t have active control measures in place, but does have a well-functioning detection system in place to take care of it.”

Tatem said that many factors, working in combination, have likely contributed to the stability of malaria elimination seen in many countries. These include urbanization, which creates environments that are unfavorable for malaria-spreading mosquitoes; improvements in surveillance within health systems to ensure that imported cases are treated promptly and any local outbreaks are controlled early; and travel patterns, with travelers who bring in infections from elsewhere rarely ending up in rural areas where mosquito densities are highest, thus reducing the likelihood of onward spread.

Malaria has long been a global health issue. In 1955, the World Health Organization launched an eradication campaign that eliminated the disease in many temperate and subtropical regions but did not achieve worldwide eradication. The program was scrapped after less than two decades in favor of controlling malaria. However, WHO attributed about 660,000 deaths to the disease in 2010, mostly African children.

Now, a University of Florida expert says tourists armed with cameras may be a new source of data about the gentle giants, often seen in the Gulf of Mexico. Photographs could help scientists gauge the shark’s abundance and shed light on its longevity, migratory patterns, breeding habits and other information needed for conservation efforts.

A study published in the current issue of the journal Wildlife Research examined whale shark photographs and video still images posted online by vacationers on diving or sightseeing excursions who had seen the creatures. The researchers concluded that the material was often suitable for use in scientific studies that identify and track individual whale sharks.

“We need to consider all available information to try and fill the gaps of knowledge for data-deficient, vulnerable species like whale sharks,” said Juliane Struve, a research assistant professor with UF’s Institute of Food and Agricultural Sciences. “Citizen photos are as useful as researcher photos if they meet the requirements of photo identification.”

Whale sharks can be individually identified because each one has a unique pattern of spots and lines on its back, giving the creature a visual signature akin to a fingerprint, Struve said. And, unlike many large marine species, whale sharks often swim close to the surface, making them accessible to photographers.

In certain areas, large congregations of whale sharks appear annually, and tourism industries have sprung up to help people get close to the fish, which can reach a maximum length of more than 40 feet and a weight of more than 45,000 pounds.

Worldwide, there are believed to be about 100,000 whale sharks, which eat plankton and pose no threat to man. Though not classified as endangered, whale sharks are killed for their meat and fins, and sometimes die after being accidentally caught in tuna nets.

The study focused on images captured in the Republic of the Maldives, a chain of islands southeast of India, in a part of the Indian Ocean where whale sharks often congregate. Researchers examined about 300 images from tourists and 300 taken by scientists.

Images were considered acceptable if they provided a clear view of the left side of the whale shark’s body, clearly showing the spot pattern near the gills.

About 85 percent of the images from amateurs were good enough to allow identification of an individual whale shark, Struve said. Thus, online efforts to solicit and collect tourists’ whale shark photos could help scientists gain a better understanding of the species for conservation efforts, she said.

At least one whale shark tourism provider is eager to educate his clients about photo-sharing opportunities.

Roddrigo Sidney, owner of Cancún Whale Shark Tours and Holbox Whale Shark Tours on Mexico’s Yucatán Peninsula, said his business serves more than 20,000 tourists each summer as they come to see huge aggregations of whale sharks in the Gulf of Mexico.

“If we had a brochure telling our guests where to send the photos I’d be happy to help,” he said. “I’m sure that a number of them would be happy to assist.”

Sidney said his company includes information on whale shark biology as part of the training provided to clients as they prepare to swim with the fish. Efforts to better understand whale sharks will have a positive effect for his business, he said.

For more information on whale shark photographs and their use in scientific research, see http://whaleshark.org.