Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Sea urchins’ unexpectedly diverse ’innate’ immune capability points to new research avenue


’We are beginning to understand how an animal without an adaptive immune system can still protect itself,’ Smith said, adding: ’The sea urchin may use genes that are different from antibodies and possibly even different mechanisms from humans.’

Strongylocentrotus purpuratus(Nudibranch, or Spanish Dancer). Credit: Dr. Susan Fuhs in Southern California on SCUBA.

Inside that seemingly docile sea urchin there’s a surprisingly active innate immune system, probably utilizing previously unrecognized immune mechanisms, that may also actively function in vertebrates, including humans, according to researchers at George Washington University, in Washington, D.C.

"Discovering this capability goes completely against the long-accepted paradigm that the innate immune system which had evolved over a long period of time was ’perfect’ in terms of meeting lower animals’ needs," L. Courtney Smith, associate professor of Biological Sciences, said. "It was a big surprise, that continues to astound us," she added.

Like many "lower" animals such as insects, earth worms and others without an adaptive immune system (one that can make antibodies), a sea urchin’s innate system seems to produce a wide diversity of proteins that probably can attack germs and protect the sea urchin from infection, a new study from Smith’s lab shows.

She and her colleagues studied the purple sea urchin’s response to a standard bacterial insult (a fragment of the cell wall called lipopolysaccharide, or LPS) using a genomic screen. They discovered that the sea urchin produces a surprisingly large number of proteins against LPS, and that many of them are similar but also show an unexpected amount of variability.

Possible role of ’innate immunity’ higher up the evolutionary ladder

"We are beginning to understand how an animal without an adaptive immune system can still protect itself," Smith said, adding: "We’re beginning to appreciate that the sea urchin may use genes that are different from antibodies and possibly even different mechanisms from humans and yet is still able to produce an array of proteins with lots of diversity."

The paper, "Macroarray analysis of coelomocyte gene expression in response to LPS in the sea urchin. Identification of unexpected immune diversity in an invertebrate," appears in Physiological Genomics, published by the American Physiological Society. Research was by Sham V. Nair, Heather Del Valle, David P. Terwilliger and L. Courtney Smith at George Washington University; and Paul S. Gross at Medical University of South Carolina.

The paper concludes: "Identification of novel mechanisms for generating immune diversity in invertebrates, which has implications for innate immune capabilities in all animals, may result in a better understanding of innate immunity in higher vertebrates."

Latest technology aimed at the base of animal phylogeny branch that includes humans

Sea urchins are at the very bottom of the same branch of the evolutionary tree with sharks (where a type of adaptive immune system was first identified) and the rest of the vertebrates, which include fish, reptiles, birds and of course, mammals such as humans. Thus further understanding of the sea urchin’s immune mechanism could open research possibilities in several directions.

To understand the sea urchin immune system, Smith said her lab "employed comparative and phylogenetic approaches to analyze the sea urchin protein sequences, which yield information on the evolution of immunity in the deuterostome lineage of animals," the subject of the current paper. Another line of investigation is working on characterizing "a large set of putative antimicrobial proteins induced by challenge" with LPS. Using proteomics, genomics and molecular biology, the lab is "working to understand the functions of these proteins, the number of genes in the sea urchin genome and the mechanisms for generating this high level of diversity in an invertebrate immune response," in this case, to LPS.

New mechanisms believed at work to produce diverse immune response

Smith said they had identified a particularly large group of "similar but diverse" proteins that appeared after LPS injection, "which we propose represent a major player in the immune response of the sea urchin." The family of transcripts had previously been designated as 185/333. The paper in Physiological Genomics "is the first report on a genomic screen showing sequences that are similar enough to look like they’re coming from the same gene," Smith noted, but they don’t. This is a current research effort in Smith’s lab.

Nevertheless, she added, the results seem to indicate how invertebrates cope so successfully in their pathogenic environment, perhaps using as yet undiscovered mechanisms, which may also exist in immune systems of more advanced animals. "Our preliminary results indicate there are too few genes to explain the observed nucleotide variability in the ETSs (expressed sequence tags)," the paper said. "This suggests that there may be mechanisms for generating sequence diversity in the 185/333 transcripts that have not been previously characterized."

"This was the big surprise in our findings," Smith noted. ""It is evolutionary significant that animals other than vertebrates have mechanisms, most still unknown, to diversify their innate immune system to address the problem of microbes always finding new ways to infect. It turns out that we and other vertebrates aren’t unique in that. Probably all animals and plants to do this, but we never even thought of asking that question before," she said.

Next steps that could ’revolutionize’ paradigm on invertebrate immune function

The paper itself summarizes the findings and implications like this: "The diversity shown in the innate immune responses of the sea urchin, snail, shrimp and the Amphioxus responding to bacterial, parasitic, fungal, and viral challenges suggests that these animals, and perhaps most animals, may have hitherto unrecognized mechanisms to diversify their responses to foreignness. These mechanisms may either result in broad protection against pathogens or in directed expression of specific peptides to combat specific infecting microbes. The analysis of the sea urchin system promises to uncover mechanisms that generate diversity in immune response, the results of which will contribute to a paradigm shift in our understanding of invertebrate immunity, as suggested by (Martin F.) Flajnik and (Louis) du Pasquier."

Smith added: "A series of followup experiments of the sea urchin’s immune system are expected to revolutionize our understanding of the evolution of immunity and will change completely the current paradigm of how invertebrate immune systems function."

Mayer Resnick | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Make way for the mini flying machines
21.03.2018 | American Chemical Society

nachricht New 4-D printer could reshape the world we live in
21.03.2018 | American Chemical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>