Tag Archives: invertebrate

When it comes to the world of viruses, we’re just scratching the surface

A pioneering study of invertebrates has revealed what many biologists already suspected: when it comes to viruses, we’ve only seen the tip of the iceberg.

Image credits: University of Sydney.

Invertebrates are the most populous animals. They lack a backbone, but the term is otherwise quite unclear, especially in modern biological contexts. “Invertebrata” is a term of convenience, not a taxon and has very little circumscriptional significance in most cases. Still, the majority of animal species are invertebrates with one estimate putting the figure at 97%. As such you’d expect them to have a tremendous viral fauna as well.

Invertebrates are often understudied when it comes to bacteria and viruses, especially compared to humans and other mammals. We’re less worried about snail viruses affecting us so there’s less incentive to study that. With this idea in mind, Professor Edward Holmes, from the Marie Bashir Institute for Infectious Diseases & Biosecurity and the School of Life and Environmental Sciences set out to see just what kind of viruses live on invertebrates.

They expected something new, but the results were surprising even for them.

“This groundbreaking study re-writes the virology text book by showing that invertebrates carry an extraordinary number of viruses — far more than we ever thought,” Professor Holmes said.

“It’s remarkable that invertebrates like insects carry so very many viruses — no one had thought to look before because most of them had not been associated with human-borne illnesses.”

Much of the interest around this study was focused on insects. Although insects such as mosquitoes are notoriously known for transmitting dangerous diseases such as malaria, most insect viruses are harmless to humans – they’re not even transmissible. Importantly, studies like this could help us better understand where some of the insect-borne diseases originate, such as the controversial ‘Lyme-like disease’ that is claimed to occur following tick bites.

Judging by the genetic evidence, it also seems likely that some of the viruses have been living with their hosts for much longer than previously thought (though the “billions of years” proposed by the University of Sydney announcement is a bit of a stretch, considering that even multicellular organisms hadn’t evolved “billions of years” ago). Still, it’s quite possible that many of the viruses that affect us today are derived from viruses found today in invertebrates.

“We have discovered that most groups of viruses that infect vertebrates — including humans, such as those that cause well-known diseases like influenza — are in fact derived from those present in invertebrates,” said Professor Holmes, who is also based at the University’s multidisciplinary Charles Perkins Centre.

All in all, it seems like there’s a world of viruses we know very little about and which we’re just starting to explore. It may be a perfect time to do that too, because a part of it is already exploring us. There’s a definite need for more research in this area.

Journal Reference: Mang Shi, Xian-Dan Lin, Jun-Hua Tian, Liang-Jun Chen, Xiao Chen, Ci-Xiu Li, Xin-Cheng Qin, Jun Li, Jian-Ping Cao, John-Sebastian Eden, Jan Buchmann, Wen Wang, Jianguo Xu, Edward C. Holmes, Yong-Zhen Zhang. Redefining the invertebrate RNA virosphere. Nature, 2016; DOI: 10.1038/nature20167

ship-worm

Antibiotics of the future might come from the bottom of the oceans

The advent of antibiotics has spared humanity of a great deal of suffering and has saved countless lives through the years. Infectious diseases do not bore too easily and have always put out a fight, though. The bad news is that they’re winning and as the battle rages on, more and more strains become resistant to drugs. The consequences are broad and dire, and this is why scientists today want to be one step ahead and prepare for tomorrow.

Two separate studies recently published by a research partnership called the Philippine Mollusk Symbiont International Cooperative Biodiversity Group discuss how the future’s new class of antibiotics might reside at the bottom of the oceans. Like the name implies, both studies were concentrated on mollusks, a phylum of invertebrates which includes such animals as snails, clams and squid. Many of these ocean animals have been living in harmony with their bacterial companions for millions of years, and it’s in these bacteria that the key to the future’s antibiotics might lie. Having passed the test of time, rending no side effects to their animal companions, these bacteria have already shown promising results.

Ocean bacteria might be key to tomorrow’s antibiotics

ship-wormThe first study, published in the journal Proceedings of the National Academy of Sciences, the researchers tackled shipworms, but don’t let the name fool you too much. These mollusks have more to do with ships themselves than worms. Typically these are considered pests due to their ill-viewed habit of affixing themselves to the sides of wooden ships. Over time they feed on the wood, causing damage to the boat, which can be most unpleasant.

Then comes the question, however. How do these animals feed on wood? Wood is an extremely poor nutrient, far from being an ideal meal for a multicell organism, since it lacks proteins or nitrogen. Here’s the kicker though. The shipworm has a bacteria that converts the wood into a suitable food source where the animal can both live and feed. One such bacteria apparently also secretes a powerful antibiotic, which might hold great promise for combating human diseases.

“The reason why this line of research is so critical is because antibiotic resistance is a serious threat to human health,” said Margo Haygood, Ph.D., a member of the OHSU Institute of Environmental Health and a professor of science and engineering in the OHSU School of Medicine.

“Antibiotics have helped humans battle infectious diseases for over 70 years. However, the dangerous organisms these medications were designed to protect us against have adapted due to widespread use. Without a new class of improved antibiotics, older medications are becoming less and less effective and we need to locate new antibiotics to keep these diseases at bay. Bacteria that live in harmony with animals are a promising source. “

cone snailThe second paper, published in journal Chemistry and Biology, looked at cone snails collected in the Philippine. Previously, only a few studies actually were made to determine whether or not bacteria associated with these mollusks might prove useful in drug development. Mostly, this is due to the fact that cone snails aren’t that welcoming to outside visitors, featuring thick shells and quite a nasty toxic venom why they aren’t too shy about using. Since they pose a sort of miniaturized defense arsenal, it was previously assumed that these animals do not require additional chemical defense, meaning there could be no interest in human medication in turn. This was a false assumption.

Scientists proved that bacteria associated with cone snails actually produce a chemical which is neuroactive, impacting nerve cells (neurons) in the brain. Based on initial findings alone, the bacteria is already considered promising as a viable candidate for a highly powerful painkiller.

“Mollusks with external shells, like the cone snail, were previously overlooked in the search for new antibiotics and other medications,” said, Eric Schmidt, Ph.D., a biochemist at the university of Utah and lead author of the article.

“This discovery tells us that these animals also produce compounds worth studying. It’s hoped that these studies may also provide us with valuable knowledge that will help us combat disease.”

120 million crabs hit the streets

Image by Lilolebob.

Every year, around this time of year, more than 100 million determined crabs take to the streets in a massive attempt to get to their spawning grounds as soon as possible; as a result, they literally flood the streets in Christmas island, covering the streets and forcing rangers to divert traffic and use some quite creative methods of protecting the crustaceans.

Photo by Ian Usher.

However, despite the absolutely huge number of crabs, there have been no reports of violence, from any one of the islands 1200 inhabitants. “It is difficult to see crabs in the houses,” one local resident told BBC Brasil. However, the efforts local rangers have been sustaining are nothing short of laudable; they constructed plastic bridges and fences to keep them from more populated areas and even help them across difficult areas (I don’t know, but I’m guessing difficult urbanized obstacles).

At 135 square km and located 370 km off of Indonesia, this Australian territory is often called the “Galapagos of the Indian Ocean” for its diversity of both plant and animal life. It’s also home to 14 different species of crabs, including the coconut crab, the largest invertebrate in the world. The efforts I mentioned earlier are even more impressive taking into account the 1.5 million people who come to see the amazing wildlife display each year.