300 Teeth: Duck-billed dinosaurs would have been dentist’s dream

Date: August 25, 2016

Source: University of Toronto]

Imagine how much dental care you'd need if you had 300 or more teeth packed together on each side of your mouth.

Duck-billed dinosaurs (hadrosaurs), who lived in the Cretaceous period between 90 million and 65 million years ago, sported this unique dental system, which had never been fully understood until it was examined at the microscopic level through recent research conducted by Aaron LeBlanc, a University of Toronto Mississauga PhD candidate; his supervisor, Professor Robert Reisz, the University of Toronto Mississauga vice-dean, graduate, and colleagues at the Royal Ontario Museum and the Museum of the Rockies.

Rather than shedding teeth and replacing them with new ones like other reptiles, hadrosaurs' mouths contain several parallel stacks of six or more teeth apiece, forming a "highly dynamic network" of teeth that was used to grind and shear tough plant material. Although hadrosaur teeth appear to be fused in place, LeBlanc and his colleagues show that the newest teeth were constantly pushed towards the chewing surface by a complex set of ligaments. When viewed under the microscope, the columns of teeth are not physically touching and are held together by the sand and mud that can get in between the teeth following the decay of the soft ligaments after the animals died.

"Hadrosaur teeth are actually similar to what we have because our teeth are not solidly attached to our jaws. Like us, hadrosaur teeth would have had some fine-scale mobility as they chewed thanks to this ligament system that suspended the teeth in place," says Reisz.

As they reached the grinding surface, hadrosaur teeth were essentially dead, filled with hard tissue -- unlike humans, whose teeth have an inner core filled with blood vessels and nerves.

"Since the teeth were already dead, they could be ground down to little nubbins," Reisz says.

LeBlanc says this tooth structure -- with its tough grinding surface -- was "well-adapted to break down tough plant material for digestion," through both shearing and grinding. This adaptation may have contributed to the hadrosaurs' longevity and proliferation.

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Whiskers help animals sense the direction of the wind

First-ever study shows that rats use whiskers to locate source of airflow

Date: August 24, 2016

Source: Northwestern University

Many animals appear to have an impressive ability to follow the wind to find food, avoid predators, and connect with potential mates. Until now, however, no study had examined how land mammals know the direction of the wind. New research finds that an important part of this ability lies in an animal's whiskers. The work could pave the way for the design of novel airflow measurement devices that imitate these biological sensors.

A team of four PhD students working with Northwestern University's Mitra Hartmann, professor of biomedical and mechanical engineering in Northwestern's McCormick School of Engineering, report in the August 24 issue of Science Advances that rats use their whiskers to help locate airflow sources.

To perform the experiment that led to this discovery, Yan Yu and Matthew Graff, co-first authors of the work, placed five, equally-spaced fans in a semicircle around the edge of a 6-foot circular table. In each trial, one of the five fans was randomly selected to blow air toward a "start-door" located on the opposite side of the table. A rat had to run from the door toward the fan blowing air, and go down a rat-sized hole directly in front of that fan. Each of the five holes (one in front of each fan) led to a tunnel beneath the table, where the rat was rewarded for choosing the correct fan. Cameras positioned above the table recorded the rats' performance.

With five fans to choose from, rats could perform at a 20 percent correct level just by chance. After the rats had performed the task at a level of approximately 60 percent correct or higher for 10 days in a row, the researchers cut off the whiskers (a procedure as painless as a haircut) and looked for changes in behavior. Two additional study authors, Chris Bresee and Yan Man, contributed to running the experiment and analyzing the data. Ultimately, the team's results showed that whisker removal decreased rats' performance by approximately 20 percent.

To explain these results, the researchers noted that the rats were permitted to use any sensory cues they wanted to locate the fan.

"We didn't require the rats to use their whiskers for this task," said Yu.

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Newly discovered 'multicomponent' virus can infect animals

Date: August 25, 2016

Source: US Army Medical Research Institute of Infectious Diseases

Scientists have identified a new "multicomponent" virus -- one containing different segments of genetic material in separate particles -- that can infect animals, according to research published today in the journal Cell Host & Microbe.

This new pathogen, called Guaico Culex virus (GCXV), was isolated from several species of mosquitoes in Central and South America. GCXV does not appear to infect mammals, according to first author Jason Ladner, Ph.D., of the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID). However, the team also isolated a related virus -- called Jingmen tick virus, or JMTV -- from a nonhuman primate. Further analysis demonstrates that both GCXV and JMTV belong to a highly diverse and newly discovered group of viruses called the Jingmenvirus group.

Taken together, the research suggests that the host range of this virus group is quite diverse -- and highlights the potential relevance of these viruses to animal and human health.

"Animal viruses typically have all genome segments packaged together into a single viral particle, so only one of those particles is needed to infect a host cell," Ladner explained. "But in a multicomponent virus, the genome is divided into multiple pieces, with each one packaged separately into a viral particle. At least one particle of each type is required for cell infection."

Several plant pathogens have this type of organization, but the study published today is the first to describe a multicomponent virus that infects animals.

Working with collaborators including the University of Texas Medical Branch and the New York State Department of Health, the USAMRIID team extracted and sequenced virus from mosquitoes collected around the world. The newly discovered virus is named for the Guaico region of Trinidad, where the mosquitoes that contained it were first found.

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Canine hereditary disorders are more widespread than previously indicated

Date: August 22, 2016

Source: University of Helsinki

Genoscoper Ltd. has published in cooperation with the researchers of University of Helsinki and Pennsylvania (USA) so far the most comprehensive study on canine hereditary disorders. The research brings new information about genetic disorders causing diseases in different dog breeds. The results can be utilized both in dog breeding and veterinary diagnostics. The study was published on PLOS ONE on Aug. 15, 2016.

We noted that surprisingly many canine inherited disorders are actually more widespread than indicated by their original discovery studies, which opens up the door for several future scientific investigations, explains senior author Dr. Hannes Lohi from the University of Helsinki canine genetics research group.

The technological potential to test a dog for multiple inherited disorders at once has existed for several years. The challenge is to harness that potential for practical use in improved veterinary disease diagnostics, sustainable breeding selections, personalized pet care, and canine genetics research, says lead author Dr. Jonas Donner of Genoscoper Laboratories. Genoscoper Ltd. is a Finnish company specialized in animal genetics and gene testing.

By testing nearly 7000 dogs representing around 230 different breeds for predisposition to almost 100 genetic disorders, the research team observed that 1 in 6 dogs carried at least one of the tested disease predisposing genetic variants in their genome. Moreover, 1 in 6 of the tested genetic variants was also discovered in a dog breed in which it had not previously been reported in the scientific literature. Through clinical follow up of dogs genetically at risk, the research team was able to confirm that several disorders cause the same disease signs also in other than previously described breeds.

Precisely as we humans, every dog is likely to carry genetic predisposition for some inherited disorder, so we expect these numbers to grow as the numbers of tested disease variants, breeds, and dogs further increase, confirms Dr. Donner.

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Discovery of an ape virus in an Indonesian rodent species

August 26, 2016

The gibbon ape leukemia virus (GALV) is a medically important tool in cancer therapies. GALV is a retrovirus pathogenic to its host species, the southeast Asian lar gibbon (Hylobates lar) and thought to have originated from a cross-species transmission and may not originally be a primate virus at all. An international research team headed by the German Leibniz Institute for Zoo and Wildlife Research (IZW) screened a wide range of rodents from southeast Asia for GALV-like sequences. The discovery of a new GALV in the grassland melomys (Melomys burtoni) from Indonesian New Guinea supports the hypothesis that this host species, and potentially related rodent lineages in Australia and Papua New Guinea, may have played a key role in the spread of GALV-like viruses. The findings were published in the scientific journal Journal of Virology.

The scientists found that rodents from Indonesian New Guinea possibly contributed as vectors to a cross-species transmission leading to the infection of gibbons with the gibbon ape leukemia virus (GALV) and koalas with the koala retrovirus (KoRV). GALV is a retrovirus which causes a cancer (hematopoietic neoplasms) in captive colonies of gibbons. However, GALV has never been isolated from wild primates that did not have a captive origin. This suggests that some other species in contact with captive gibbons are the source of GALV. KoRV is a retrovirus closely related to GALV and therefore the two viruses share a common ancestor. Since koalas and gibbons do not overlap in distribution, a direct natural transmission between koalas and gibbons is unlikely. It is therefore probable that one or more mobile and widely distributed host species such as rodents carry GALV- and KoRV-like viruses and infected koalas and gibbons independently. The findings of this study are consistent with this hypothesis.

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