An international team of researchers, including scientists of the Max Planck Institute of Immunobiology and Epigenetics, has sequenced and analysed the genome of the elephant shark.
The immune system of the elephant shark is simpler than many other vertebrates studied so far. The present studies also explain, why cartilaginous fishes do not generate human-like bones
Comparison of the elephant shark genome with human and other vertebrate genomes has revealed why the skeleton of sharks is made up largely of cartilage and not bone like the human skeleton and that the immune system of the shark is much simpler than that of humans. The findings of Byrappa Venkatesh and his coworkers are published in the latest issue of the scientific journal, Nature.
An unexpected finding of the immune system analysis was that sharks appear to lack special types of so-called T-helper lymphocytes, that – until now – were considered to be essential for defence against viral/bacterial infections and preventing autoimmune reactions such as diabetes and rheumatoid arthritis in vertebrates.
Despite this seemingly primitive organization of the immune system, sharks exhibit robust immune defences and are long-lived. “The structure of the immune system of the elephant shark is very different from mammals,” said Thomas Boehm, co-author and director at the Max Planck Institute of Immunobiology and Epigenetics in Freiburg, Germany. “It is obvious that sharks can efficiently deal with all kinds of infections without this particular cell type. This indicates that nature can come up with different solutions to the same problem,” stated Boehm.
What happens when T-helper cells are being destroyed can be observed in AIDS patients, who succumb to viral and bacterial infections. Up to now, it was assumed that cells are essential for an immune system. The new results are challenging this long-held notion and open up an unprecedented avenue towards the development of non-intuitive strategies to modulate the immune functions of humans.
The researchers also investigated why cartilaginous fishes, including the elephant shark, are unable to replace cartilage with bone like humans and other bony vertebrates. Genome analysis was able to highlight a family of genes that are absent in sharks but present in all bony vertebrates and are critical for bone formation. When the researchers inactivated these genes in bony fishes such as the zebrafish, calcification did not occur. This finding is a strong indication that the investigated gene family could be a starting point for a better understanding of bone diseases such as osteoporosis.
In addition, the study revealed that the elephant shark genome is the slowest evolving among all vertebrates. The elephant shark even beats the coelacanth, also called “the living fossil”, that has recently been shown to evolve extremely slowly. Therefore, the elephant shark is probably the best proxy for the ancestor of all jawed-vertebrates that became extinct a long time ago.
Cartilaginous fishes (comprising sharks, rays, skates and chimaeras) are the oldest living group of jawed-vertebrates that diverged from bony vertebrates about 450 million years ago. The elephant shark (Callorhinchus milii) is a chimaera that inhabits temperate waters of the continental shelves off southern Australia and New Zealand, at depths of 200 to 500 meters. From approximately 1,000 species of cartilaginous fishes, elephant shark was chosen as a model because of its relatively compact genome which is one third the size of the human genome.
The elephant shark genome project was funded mainly by the National Institutes of Health (NIH), USA. It is a collaborative effort of scientists from 12 international institutions, including the Max Planck Institute of Immunobiology and Epigenetics (MPI-IE) in Freiburg, Germany. Viruses, bacteria and other parasites are a continuous threat to all living beings. Therefore, most of them possess elaborate defence strategies to combat these unwanted intruders. At the Max Planck Institute of Immunobiology and Epigenetics, Thomas Boehm studies the evolution of the immune system and its development and function during lifetime of animals. For his fundamental work on development, differentiation and evolution of immune systems, Thomas Boehm is awarded the prestigious Ernst Jung Award for Medicine 2014.
ContactDr. Thomas Boehm
Dr. Thomas Boehm | Max-Planck-Institute
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy