Delving into sponge ecosystems
Many of the active substances in today’s pharmaceuticals originate in nature. Could this be where we will find new antibiotics that can take over when the old ones become ineffective because of widespread resistance?
We’ve learned that it is important to preserve the Earth’s rainforests. Not only for the sake of the climate, but also because we might otherwise risk losing numerous plants and animals, many still undiscovered or only sketchily described.
In their hunt for new drugs, Paco Cardenas and his colleagues at the Department of Medicinal Chemistry, Division of Pharmacognosy are not taking to the rainforests. Instead, they’ve decided to take their research into deep water. Literally. They are looking for active substances in sponges that live in deep ocean environments, in some places as vast sponge grounds.
The oceans are some of the most unexplored areas on Earth, but these environments have thus far not inspired the same level of engagement from the public as, say, the rainforests. Even among sea creatures, sponges have been treated rather unfairly. The more visually appealing coral reefs are more popular. But like coral reefs, sponge fields are under constant threat – by climate change, industrial fishing, and oil and gas extraction.
The football sponge, Geodia barretti, which the Uppsala researchers have chosen to study particularly thoroughly, is no beauty. Not even by sponge standards. And the strangest thing of all is that it’s not even spongy.
“If you squeeze it, it feels pretty much like a potato,” explains Karin Steffen, PhD student on the sponge team.
The idea that living sponges would feel like sponges you use in the bath is way off, then. Sponges have skeletons and are rather hard. ‘Bath sponges’ are fished sponges that are then processed so that only the porous skeleton is left.
But sponges are interesting from many different perspectives. Besides the fact that their importance for the entire ocean ecosystem remains poorly surveyed, every animal is an ecosystem in itself. When they ‘eat’, they filter large amounts of water and the inside of a sponge contains, in addition to plankton, bacteria and archaea, a whole cocktail of other things that they have collected from the water around them. For the researchers, it can be a delicate task to sort out which substances actually come from the animal and which were drawn from their surroundings.
In the hunt for active substances that could be used in drugs to benefit humans, the researchers screen large quantities of substances from sponges and test these on various types of bacteria, fungi and parasites.
“The whole genome of Geodia barretti is being sequenced concurrently,” says Paco Cardenas. “We can then look for genes involved in creating the interesting substances.”
Uppsala researchers have had their eyes on Geodia barretti before. On the table in front of us is a porous brown sample. It must be handled with care because it is the actual holotype of the species (a single example of an organism used for its scientific description) from 1855, borrowed from the Natural History Museum in London. Cardenas has received permission to extract a small sample to test if the old, dried sample still holds barettin, a substance that Lars Bohlin, now Professor Emeritus of Pharmacognosy, observed in the 1980s.
Bohlin had noted that Geodia barretti has a smooth surface but, unlike most other similar species, no growth of other organisms. Could this sponge contain a substance that kept them away? He found a substance that was named barettin and it is hoped that this substance could be used in applications such as products to keep bacteria away from surgical instruments or barnacles from boat hulls. One problem, however, has been that barettin is more costly to produce than less environmentally friendly options.
The more researchers learn about Geodia barretti, the more precise they can be in their search for useful substances.
“Our work is also important for the preservation of the sponges,” says Cardenas. “The loss of a species likely also means the loss of the entire bacterial flora.”
Facts/EU project SponGES
Sponge researchers at Uppsala University are part of the EU project Deep-sea Sponge Grounds Ecosystems of the North Atlantic (SponGES). Researchers from 18 different universities and research institutes will survey sponges throughout the deep waters of the North Atlantic. The aim is to learn more about the animals’ ecosystems in order to improve their preservation and sustainable exploitation. Project coordinator Professor Hans Tore Rapp of the University of Bergen says that SponGES is primarily a pure research project, but that the project could also lead to considerable environmental and medical benefits.
- The first animals – Sponges may have been the first animals on our planet. They reproduce by sending out eggs and sperm, which find each other in the water. Sponges share a large part of their genes with humans.
- Linnaeus’s mistake – Uppsala professor Carl Linnaeus didn’t know much about sponges and mistakenly classified them as plants. It wasn’t until the 19th century that sponges were recognised as part of the animal kingdom.
- Best sponge site – To find Geodia barretti in Sweden, you have to head out to the Koster Sea marine park. The area contains thriving species that are otherwise only found further out in the Atlantic.
28 April 2017