For a green alga, spotted salamanders are stressful hosts

May 2, 2017

New research shows how two drastically different organisms—a green alga and the spotted salamander—get along as cellular roommates. Scientists at the American Museum of Natural History and Gettysburg College found that this symbiosis, the only known example that includes a vertebrate species, puts stress on algal cells, changing the way they make energy, but does not seem to negatively impact salamander cells. The work is published today in the journal eLife.

"Science shows us the many ways that life is interconnected, especially on the microscopic level, where we see how many organisms depend on close contact with or internalization of other species for food, defense, or reproduction," said lead author John Burns, a postdoctoral researcher in the Museum's Division of Invertebrate Zoology. "But the relationship between this particular alga and salamander is very unusual."

Scientists have known for more than a century that a green alga (Oophila amblystomatis) grows in the egg cases of the spotted salamander (Ambystoma maculatum)—the strange pairing is visible to the naked eye in the green hue of salamanders' eggs. The symbiosis was originally thought to occur only between the salamander embryo and the algae living outside it. The embryos produce nitrogen-rich waste that is useful to algae, and the algae increases the oxygen content of the fluid around the respiring embryos. But recent research has revealed that the algae are actually located inside cells all over the spotted salamander's body. This cell-within-a-cell relationship can also be found in corals and in the guts of cicadas, but the green alga-spotted salamander interaction is the only known example of a symbiont entering the cells of a vertebrate species.

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Earliest relative of Brachiosaurus dinosaur found in France

May 2, 2017 by Colin Smith

Scientists have re-examined an overlooked museum fossil and discovered that it is the earliest member of the titanosauriform family of dinosaurs.

The fossil, which the researchers from Imperial College London and their colleagues in Europe have named Vouivria damparisensis, has been identified as a brachiosaurid sauropod dinosaur.

The researchers suggest the age of Vouivria is around 160 million years old, making it the earliest known fossil from the titanosauriform family of dinosaurs, which includes better-known dinosaurs such as the Brachiosaurus. When the fossil was first discovered in France in the 1930s, its species was not identified, and until now it has largely been ignored in scientific literature.

The new analysis of the fossil indicates that Vouivria died at an early age, weighed around 15,000 kilograms and was over 15 metres long, which is roughly 1.5 times the size of a double-decker bus in the UK.

It had a long neck held at around a 45 degree angle, a long tail, and four legs of equal length. It would have been a plant eater.

Dr Philip Mannion, the lead author of the study from the Department of Earth Science and Engineering at Imperial College London, said: "Vouivria would have been a herbivore, eating all kinds of vegetation, such as ferns and conifers. This creature lived in the Late Jurassic, around 160 million years ago, at a time when Europe was a series of islands. We don't know what this creature died from, but millions of years later it is providing important evidence to help us understand in more detail the evolution of brachiosaurid sauropods and a much bigger group of dinosaurs that they belonged to, called titanosauriforms."

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New species of dinosaur increases the already unexpected diversity of 'whiplash dinosaurs'

May 2, 2017

Researchers from Italy and Portugal describe yet another new sauropod species from 150 million years ago, from Wyoming, USA

The new species, Galeamopus pabsti, is the most recent dinosaur to be described by paleontologists from the Department of Earth Sciences of the University of Turin, Italy; the Faculty of Science and Technology, Universidade Nova de Lisboa, and the Museum of Lourinhã in Portugal. This Jurassic dinosaur was originally excavated in 1995 by a Swiss team, led by Hans-Jakob "Kirby" Siber and Ben Pabst, in Wyoming, in the United States and is the latest in a series of new discoveries by the paleontologists Emanuel Tschopp and Octávio Mateus, which started in 2012 with Kaatedocus siberi. The paper describing the new species was published online in the open access scientific journal PeerJ on Tuesday, May 2.

Galeamopus pabsti is similar to the famous dinosaur Diplodocus, but with more massive legs, and a particularly high and triangular neck close to the head. It is the second species of the genus Galeamopus to be shown to be different to Diplodocus by the same researchers (the first being published in 2015, in a paper which also reinstated the brontosaurus as a distinct genus). The new species is dedicated to Ben Pabst, who found the skeleton, and prepared it for mounting at the Sauriermuseum Aathal in Switzerland, where it is one of the main attractions of the permanent exhibit.

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Most mammals big or small take about 12 seconds to defecate

26 April 2017

By Chelsea Whyte

Everyone poops, and it takes them about the same amount of time. A new study of the hydrodynamics of defecation finds that all mammals with faeces like ours take 12 seconds on average to relieve themselves, no matter how large or small the animal.

The research, published in Soft Matter, reveals that the soft matter coming out of the hind ends of elephants, pandas, warthogs and dogs slides out of the rectum on a layer of mucus that keeps toilet time to a minimum.

“The smell of body waste attracts predators, which is dangerous for animals. If they stay longer doing their thing, they’re exposing themselves and risking being discovered,” says Patricia Yang, a mechanical engineer at the Georgia Institute of Technology in Atlanta.

Yang and colleagues filmed elephants, pandas and warthogs at a local zoo, and one team member’s dog in a park, as they defecated. All these animals produce cylindrical faeces, like we do, and this is the most common kind among mammals. Though the animals’ body masses ranged from 4 to 4,000 kilograms, the duration of defecation remained constant.
Slimy Chute

That consistency across animals is down to a few things. First, the length of faecal pieces was 5 times as long as the diameter of the rectum in each of the animals.

Yang also found that the normal, low-level pressure animals apply to push through a bowel movement is constant, and unrelated to a creature’s body mass. This means that, whether it’s a human or a mouse, the pressure used on normal excrement is the same. This is similar to her previous finding that mammals take the same amount of time to empty their bladders.


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Mud DNA means we can detect ancient humans even without fossils

27 April 2017
 
By Michael Le Page

We have an astonishing new way to study our early human ancestors: looking for their DNA in ancient sediments in places such as caves.

A team of researchers has found the DNA of Neanderthals and Denisovans in some of the sites where they are known to have lived.

“I think we show convincingly that these sequences are authentic,” says lead author Viviane Slon of the Max Planck Institute for Evolutionary Anthropology in Germany.
 
The approach can now be used to find out whether early humans were present even when no bones have been found – and what kind of humans they were. It might also help resolve the debate about when the Americas were first inhabited by people, for instance.
Universe in a gram of mud

Just about any sample of soil or water is full of DNA from all kinds of organisms. Sequencing this “environmental DNA” is an increasingly powerful tool for studying ecosystems.

For instance, biologists were recently able to identify several caves where “baby dragons”, or olms, live simply by analysing the water flowing out of them.

In sediments buried in cool caves and in permafrost, this environmental DNA can survive for up to 700,000 years. In 2003, a team led by Eske Willerslev, now at the University of Cambridge, was the first to show that it was possible to find ancient DNA from species like the woolly mammoth, in frozen mud in Siberian permafrost.

Now Slon’s team has shown that ancient human DNA can survive in sediments too. Her team sequenced all the DNA present in sediment samples from sites where hominins lived, such as Denisova cave in Russia. The biologists then used short pieces of modern human mitochondrial DNA to extract longer bits of DNA containing a matching sequence from the samples.

The team looked for DNA from the energy-generating mitochondria within our cells, because they each contain the same DNA and there are hundreds per cell, so it is the type most likely to survive.



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