Deep sea creatures provide clues to the evolution of humanity

Studying the genome of a marine creature by scientists at Scripps Institution of Oceanography at the University of California San Diego brings a new light source to explain the mystery that covers the important part of the tree of life.

Biological researcher Linda Holland of Scripps Institution of Oceanography and colleagues from the United States, Europe and Asia recently decoded and analyzed the basic ingredients in the genetic material of a marine animal. The worm is called amphioxus , also called bipolar. Amphioxus, though not widely known, is noteworthy in the field of science because it is one of the closest living invertebrates to vertebrates. Although amphioxus was isolated from vertebrates over 520 million years ago, its genome still contains many unresolved clues about evolution.

The research directed by Holland was published in the June issue of Genome Research. The same article about the study is also published in the June 19 issue of the journal Nature.

Holland and colleagues studied the genes of the bivalve species Branchiostoma floridae through samples obtained in recent years during fieldwork in Tampa, Fla.

Amphioxus spawn.(Photo: Dr. Simona Candiani)

Because the amphioxus species evolves slowly, its body retains many similarities to fossils from the Cambrian period. It plays an important comparative role in understanding how vertebrates have evolved and adapted. It also brings new information about the process of vertebrates using old genes to perform new functions.

Holland, the Department of Ocean Biological Studies at Scripps Institution of Oceanography, said: 'We have found that vertically complex vertebrates do not produce many new genes to achieve that structure. Amphioxus shows that vertebrates have actually used old genes, recombined, changed the regulatory mechanism, which has probably since transformed gene function . '

First discovered in the 1700s, amphioxus shaped like a fish with a small caudal fin and medium sized fins but not pairs. They spend most of their time burying themselves in the sand, with their mouths wide open to filter food.

The human genome has only about 25% more than amphioxus genome. During evolution, humans doubled their genetic resources to perform many different functions. The doubling process facilitates humanity as well as other vertebrates to have a more versatile kit to create different structures that do not appear in amphioxus, including cells. Pigments and cartilage are structured from type II collagen protein.

In the new study, Holland and colleagues published success in understanding the roots of important body functions such as immunity. While vertebrates have two immune systems: one is the innate system that acts as the first common defense against pathogens; the second is an adaptive system by forming specific antibodies to each specific pathogen. Invertebrates such as amphioxus have only the innate immune system. For amphioxus, several innate immune genes have been duplicated independently. Perhaps with the second line of defense against the immune defense of invertebrates such as amphioxus, vertebrates are less dependent on the innate immune system to cope with infectious agents. infection.

The cells of the neural crest in vertebrates are an ideal example of how old genes have gained new functions. In all vertebrate animals, neural crest cells migrate from the neural tube development process in the body, increasing structures such as pigment cells, cartilage in the head and many types of cells. another cell. Although amphioxus has a spinal cord and brain and uses genes in the way of vertebrate animals, amphioxus has no neural crest cells. However, amphioxus still has all the genes needed to create migrating neural crest cells. Vertebrates only incorporate these genes in a new way . This phenomenon is like a cook putting all the leftovers in the fridge mixed together to create a delicious dish.

Holland said: 'The message obtained from this arrangement is that the amphioxus genome of humans and genomes is quite similar.'

30 laboratories around the world have attempted to collaborate to analyze the amphioxus gene sequence.

An in-depth analysis of the amphioxus genome of humans and genomes will yield more important clues about genetic evolution.

'All that is collected today is just like the tip of an iceberg. It will take years for us to get a closer look at the human genome and amphioxus genome. As a role to find out the evolutionary process as well as its general approach, the amphioxus genome is actually a gold mine that will remain in value in the coming years. '

In addition to Holland, co-authors of the study published in Genome Research include: Ricard Albalat, Kaoru Azumi, Australian Benito-Gutiérrez, Matthew J. Blow, Marianne Bronner-Fraser, Frederic Brunet, Thomas Butts, Simona Candiani, Pieter J. de Jong, Larry J. Dishaw, David EK Ferrier, Jordi Garcia-Fernàndez, Jeremy J. Gibson-Brown, Carmela Gissi, Adam Godzik, Finn Hallbök, Dan Hirose, Kazuyoshi Hosomichi, Tetsuro Ikuta, Hidetoshi Inoko, Masanori Kasahara, Jun Kasamatsu, Takeshi Kawashima, Ayuko Kimura, Masaaki Kobayashi, Zbynek Kozmik, Kaoru Kubokawa, Vincent Laudet, Gary W. Litman, Alice C. McHardy, Daniel Meulemans, Masaru Nonaka, Robert P. Olinski, Kazutoyo Osoegawa, Zeev Pancer, Len A Pennacchio, Mario Pestarino, Jonathan P. Rast, Isidore Rigoutsos, Marc Robinson-Rechavi, Graeme Roch, Hidetoshi Saiga, Yasunori Sasakura, Masanobu Satake, Yutaka Satou, Michael Schubert, Nancy Sherwood, Takashi Shiina, Naohito Takatori, Javier Tello, Pavel Vopalensky, Shuic hi Wada, Anlong Xu, Yuzhen Ye, Keita Yoshida, Fumiko Yoshizaki, Jr-Kai Yu, Qing Zhang, Christian M. Zmasek, Nicholas H. Putnam, Daniel S. Rokhsar, Noriyuki Satoh and Peter WH Holland.

Others involved in the amphioxus genome project include Pieter de Jong and Kazutoyo Osoegawa of Oakland Children's Hospital (CHORI).

The study was conducted by the US National Science Foundation, the US National Institutes of Health, the Wellcome Trust (United Kingdom), BBSRC (United Kingdom), MEXT (Japan), the MSMT Application Center and the Academy of Science. Study (Czech Republic), global COEs and 21st century at Kyoto University (Japan), Ministerio de Educación y Ciencia (Spain), MIUR (Italy), FIRB 2001 BAU01WAFY, together with MENRT, CNRS and CRESCENDO - Project incorporating European Union FP6 funding.