Tasmanian Devils face extinction - October 04, 2007

They may not be as cute as koala, as iconic as kangaroos, or as just-plain-weird as the platypus but Australia would still be a poorer place without the Tasmanian Devil. Sadly the devil is headed for extinction within five years, decimated by a deadly, infectious facial tumour (The Age, ABC, AAP, Tasmania's Mercury). Research has now uncovered why the animals have no immune response at all to the tumours - genetic diversity in a key set of genes is so low that the devils' immune systems do not recognise the tumours as foreign.

The research, published online in PNAS, shows that the tumours are actually clonal cell lines - a tissue graft being passed from one animal to another when they bite each other in fights or during mating (abstract, pdf). "We found that the Devils do not mount an immune response against the tumour," says author Katherine Belov from Sydney University's School of Veterinary Science (press release).

"This was due to a loss of genetic diversity in the most important immune gene region of the genome: the Major Histocompatibility Complex (MHC). Matching of MHC genes is the key to successful tissue or organ transplants. In the case of the devil, genetic diversity at MHC genes is so low, and the MHC type of the tumour and host are so alike, that the host does not see the tumour as ‘non-self'."

On the plus side isolated populations of devils might have different MHC genes, and be able to fight the tumour (Mercury). The finding might help stop the spread of the disease, but it's bad news for those already infected. "Essentially, there are no natural barriers to the spread of the disease, so affected individuals must be removed from populations to stop disease transmission," said Belov (press release).

The Sidney Morning Herald last month noted that a set of healthy animals has been sent to zoos and sanctuaries on the mainland under the auspices of the imaginatively titled ‘Project Ark'. The UK's Independent has picked up on this and provides a remarkable example of how similarly journalists think noting: "Less cuddly than the koala, less quirky than the kangaroo, the Tasmanian devil is not everyone's cup of tea." But you'll miss them when they're gone...

See also: Nature's feature from last year.

Image: Getty

http://blogs.nature.com/news/thegreatbeyond/2007/10/tasmanian_devils_face_extincti.html 

A duck-billed plant pulveriser - October 04, 2007

A "monster" dinosaur has been unveiled by Utah scientists. However, although its duck bill contained 300 teeth ready to chew and another 500 in reserve, Gryposaurus monumentensis was a confirmed herbivore (Daily Utah Chronicle, Deseret Morning News). "What you're looking at with Gryposaurus monumentensis is basically the Cretaceous version of a weed whacker," said Terry Gates, a Utah Museum of Natural History and University of Utah palaeontologist (Reuters).

The latter part of its name comes not from the beast's huge size, but from the area where it was found - the Kaiparowits Formation in the Grand Staircase-Escalante National Monument. Roaming the area 75 million years ago, it would have been the largest dinosaur in the Kaiparowits fossil ecosystem, according to Alan Titus, paleontologist for the national monument (press release, research abstract). It was, says Scott Sampson, curator of the Utah Museum of Natural History, "like the Arnold Schwarzenegger of dinosaurs - it's all pumped up" (various, including AP).

Image: Utah Museum of Natural History

http://blogs.nature.com/news/thegreatbeyond/2007/10/a_duckbilled_plant_pulveriser.html 

Par Laurent Sacco, Futura-Sciences

La découverte d'un nouveau fossile de dinosaure dans le désert de Gobi, appartenant à une espèce apparentée aux fameux vélociraptors de Jurassic Park, confirme que les oiseaux sont apparus à la suite d'une miniaturisation progressive des dinosaures à plumes. Le nouveau venu a été baptisé Mahakala et il est âgé de 80 millions d'années.

http://www.futura-sciences.com/fr/sinformer/actualites/news/t/paleontologie/d/mahakala-le-nouveau-dinosaure-oiseau-miniature_12867/  

13 September 2007; | doi:10.1038/news070910-9 / http://www.nature.com/news/2007/070910/full/070910-9.html

Fish for sale

Non-profits auction species names for conservation.

Geoff Brumfiel

Launch the slideshow Gerry Allen / CI

Over the years, philanthropists have lent their names to art galleries, schools and hospitals. But in a watershed auction, the world's rich will be able to add their names to several new species of fish - all in the name of charity.

On Thursday 20 September, an auction to name ten new species of fish is being held by the Monaco-based Monaco-Asia Society, a non-profit organization devoted to Asian causes and Conservation International, based in Arlington, Virginia. The fish are a few of the dozens discovered by Conservation International during expeditions to reefs off the coast of Indonesia's Papua Province in 2006.

Bidders will arrive from around the world for a gala at Monaco's Oceanographic Museum, which sits on a bluff high above the Mediterranean Ocean. Prince Albert II will be in attendance, and auction house Christie's will oversee the bidding pro-bono.

This isn't the first auction for a species name. For example, in 2005 an anonymous online bidder won the right to name a new kind of Bolivian monkey for a charitable donation of US$650,000. But this is the first time that multiple species will be auctioned in a single event, according to Monaco-Asia Society president Francesco Bongiovanni.

There's nothing wrong with naming an animal after the rich and famous, says Andrew Polaszek, executive secretary at the International Commission on Zoological Nomenclature in London. The only technical requirements, he says, are that the name must have a generic and specific part and be published in a paper or monograph - something that Conservation International will presumably do. Species are routinely named after famous scientists, and one species of cave beetle is even named after Adolf Hitler. He says that "you can essentially name a species anything you want".

Bongiovanni says he hopes the gala will raise US$1.2-1.4 million for further expeditions and conservation efforts in the region. But is it fair to name a species after a wealthy patron, rather than the scientist who discovered or described it? Bongiovanni says yes - especially because it is all for the greater good of the fish. "At the end of the day," he says, "these species need names."

13 September 2007; | doi:10.1038/news070910-11 / http://www.nature.com/news/2007/070910/full/070910-11.html

Salmon parents give birth to trout

Genetic technique creates viable fish sperm and eggs.

Nicola Jones

Trout juveniles at 6 months old, generated from surrogate salmon parents. Science

Researchers have succeeded in making salmon couples give birth to trout - using a technique that they argue could help to preserve rare species of fish.

Goro Yoshizaki and his colleagues at the Tokyo University of Marine Science and Technology in Japan had previously shown that male salmon could be injected with cells from closely-related trout to produce viable trout sperm. When the sperm were introduced to trout eggs, healthy trout offspring were produced.

Now the researchers have taken the work a step further, showing that salmon can be not only the biological fathers but also the mothers of trout offspring. The new work, published in Science, shows how two sterile masu salmon (Oncorhynchus masou) can together produce nothing but healthy rainbow trout (O. mykiss).

The technique relies on the injection of trout spermatagonia - the early, stem-cell stage of sperm - into salmon embryos, so that the growing salmon produce trout sperm and eggs. The technique could be very useful for storing back-up genetic material of different fish species that are today under threat, because spermatagonia can be easily cryopreserved, says David Penman, a fish geneticist at the University of Stirling, UK.

With many plants and animals, seeds, sperm and eggs can be cryopreserved to later resurrect a species that has died out. "The problem with gene-banking when you come to fish, is that it's almost impossible with eggs," says Penman. "The eggs are very big, very yolky," he says, which makes them nearly impossible to freeze.

If Yoshizaki's technique is broadly applicable to other fish, it will mean that their eggs don't need to be preserved - they could be made at a later date, in a surrogate fish.

The sperm that turned

Injecting trout spermatogonia into a salmon embryo. Science

If trout spermatagonia are injected into normal male salmon embryos, the fish will grow up to produce a mix of different types of sperm - some salmon, and some trout. In the team's previous work, when sperm from male salmon treated with primordial germ cells (an even earlier stage of sperm) were used to fertilize trout eggs, just 0.4% of the resulting offspring were healthy trout. The rest were hybrids that did not survive.

To increase this percentage, the team turned to salmon designed to have three sets of chromosomes instead of the usual two, making them sterile. When they are injected with spermatagonia, the only viable sperm the males later produce comes from these injected cells - making them 100% trout.

The group also met with success doing the same thing with sterile female salmon. When the female fish were injected as embryos with spermatagonia, the eggs they produced were all trout eggs.

The fact that an early form of sperm could be used to prompt the growth of eggs shows just how flexible these fish are to this type of treatment, notes Penman. "It's really amazing to see that they injected spermatagonia and got eggs - the fish are very plastic."

When mated, these salmon parents produced healthy trout offspring, which in turn mated to give a healthy second generation.

Save the fish

Yoshizaki and his colleagues hope the technique could be used to help save endangered fish.

"There are lots of species of fish that are threatened," says Penman. He says he thinks that to use this approach properly will mean thinking about cryopreserving a lot of material, to save all species and ensure that resulting populations are not too inbred. And some species are likely to be easier to work with than others, he adds. "If you don't happen to have a closely related recipient [for a surrogate] then you'd struggle. There are some groups where there are lots of close relatives, but some where there are only a few," he says.

"It's better to look at all the aspects of conservation biology - but this will be a useful additional technique, as a backup," Penman says.

Reference : Okutsu, T., Shikina, S., Kanno, M., Takeuchi, Y.& Yoshizaki, G.,Science 317,1517(2007).