Navigation Links
Genome sequence of small marine creature sheds light on vertebrate origins
Date:6/18/2008

Genome Research is publishing several papers related to analyses of the amphioxus (Branchiostoma floridae) genome sequence. The amphioxus, or lancelet, is a cephalochordate residing in shallow regions of tropical and temperate seas, bearing resemblance to a small fish, however lacking pairs of eyes, limbs, and ears. A member of the chordata phylum along with tunicates (sea squirts) and vertebrates, amphioxus lacks the backbone or spinal column characteristic of vertebrate animals, yet shares the same basic body plan. Amphioxus is therefore an excellent model for investigating how vertebrates evolved from an invertebrate ancestor. Now, researchers are finding that the amphioxus genome sequence is revealing new insights into vertebrate origins and the evolution of complex biological systems, such as immunity and nervous system development. Primary research reports describing these novel findings will be published online June 19, concurrent with publication of the amphioxus genome sequence report in the journal Nature.

1. Primitive pre-vertebrates are still evolving

To investigate the origins of vertebrates and other features of cephalochordate biology, a team of researchers led by Dr. Linda Holland of the Scripps Institution of Oceanography searched the amphioxus genome for specific genes, gene families, and DNA elements that could shed light on chordate biology and evolution. The analysis identified a number of features of amphioxus that are conserved with vertebrates, as well as some that are unique. In addition to new insights on development, cell signaling, immunity, and endocrine systems, Holland and colleagues identified several DNA regulatory elements conserved between amphioxus and humans. Three conserved elements from two human paralogs and a single amphioxus homolog were all shown to drive gene expression in both amphioxus and the mouse. "This is the widest phylogenetic distance to date over which both the sequence and function of cis-regulatory enhancers has been found to be conserved," explains Holland. The group concluded that while amphioxus displays many characteristics of a pre-vertebrate ancestor, it also has specialized features that have developed since diverging from chordate ancestors.

Reference: Holland, L.Z., et al. The amphioxus genome illuminates vertebrate origins and cephalochordate biology. Genome Res. doi:10.1101/gr.073676.107

Contact: Linda Z. Holland, Ph.D., Scripps Institution of Oceanography, La Jolla, CA. (lzholland@ucsd.edu, +1-858-534-5607)


2. Exploring the evolution of vertebrate innate immunity

The immune system of vertebrate animals consists of two components: the innate immune response, a constitutive system ready to respond to a pathogen, and the adaptive immune response, a system of immunological memory that responds to previously encountered pathogens. In a study led by Dr. Anlong Xu of Sun Yat-sen University, scientists searched the amphioxus genome for genes that may be relevant to immunity in order to gain an understanding of what the immune system repertoire of the vertebrate ancestor may have looked like. "Our chordate ancestors had a remarkably elaborate innate immune system, but this system was somehow reduced in the vertebrate lineage, which is unusual to our conventional thinking of the immune system," explains Xu. Furthermore, Xu notes that this work helps to describe a global picture of innate immunity and uncover the evolutionary footsteps underlying the evolution of human immune pathways.

Reference: Huang, S., Yuan, S., Guo, L., Yu, Y., Li, J., Wu, T., Liu, T., Yang, M., Wu, K., Liu, H., Ge, J., Yu, Y., Huang, H., Dong, M., Yu, C., Chen, S., Xu, A. Genomic analysis of the immune gene repertoire of amphioxus reveals extraordinary innate complexity and diversity. Genome Res. doi:10.1101/gr.069674.107

Contact: Anlong Xu, Ph.D., Sun Yat-sen University, Guangzhou, China (lssxal@mail.sysu.edu.cn, +86-20-3933-2990)


3. Hijacking of neural crest genes

In vertebrates, the peripheral nervous system and the craniofacial skeleton develop from a specific set of cells, known as neural crest cells. In this report, researchers in the laboratory of Dr. Marianne Bronner-Fraser at the California Institute of Technology have used the amphioxus genome sequence to investigate how this vertebrate-specific cell type evolved from an invertebrate ancestor. The group found genes in amphioxus that are similar to vertebrate genes related to neural crest cells, however in cephalochordates they are used for other functions. This finding raises the intriguing possibility that during vertebrate evolution, these genes may have "hijacked" for the development of neural crest cells.

Reference: Yu, J.-K., Meulemans, D., McKeown, S., and Bronner-Fraser, M. Insights from the amphioxus genome on the origin of vertebrate neural crest. Genome Res. doi:10.1101/gr.076208.108

Contact: Marianne Bronner-Fraser, Ph.D., California Institute of Technology, Pasadena, CA. (mbronner@caltech.edu, +1-626-395-3355)


'/>"/>

Contact: Peggy Calicchia
calicchi@cshl.edu
516-422-4012
Cold Spring Harbor Laboratory
Source:Eurekalert

Related biology news :

1. EuroDYNA takes lid off the genome
2. Brucella abortus S19 genome sequenced; points toward virulence genes
3. Cold Spring Harbor Protocols features methods for analyzing genomes and plant cells
4. A common aquatic animals genome can capture foreign DNA
5. Scientists decipher fruit tree genome for the first time
6. Scientists discover small RNAs that regulate gene expression and protect the genome
7. First analysis of platypus genome may impact disease prevention
8. Duck-billed platypus genome sequence published
9. The FAQs about the human genome
10. Platypus genome decoded
11. First draft of transgenic papaya genome yields many fruits
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/18/2017)... a global expert in SoC-based imaging and computing solutions, has developed ... the company,s hybrid codec technology. A demonstration utilizing TeraFaces ® , ... showcased during the upcoming Medtec Japan at Tokyo Big Sight April ... Vegas Convention Center April 24-27. ... Click here for an image of the M820 ...
(Date:4/11/2017)... 11, 2017 Research and Markets has announced ... report to their offering. ... global eye tracking market to grow at a CAGR of 30.37% ... Tracking Market 2017-2021, has been prepared based on an in-depth market ... landscape and its growth prospects over the coming years. The report ...
(Date:4/5/2017)... , April 5, 2017 Today ... announcing that the server component of the HYPR platform ... for providing the end-to-end security architecture that empowers biometric ... HYPR has already secured over 15 million users ... including manufacturers of connected home product suites and physical ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... , ... October 12, 2017 , ... ... Wound Market with the addition of its newest module, US Hemostats & Sealants. ... for thrombin hemostats, absorbable hemostats, fibrin sealants, synthetic sealants and biologic sealants used ...
(Date:10/11/2017)... , ... October 11, 2017 , ... Personal eye wash is a basic first aid ... at a time. So which eye do you rinse first if a dangerous substance enters ... Plum Duo Eye Wash with its unique dual eye piece. , “Whether its dirt ...
(Date:10/11/2017)... ... October 11, 2017 , ... Disappearing forests and increased emissions are ... 5.5 million people each year. Especially those living in larger cities are affected by ... in one of the most pollution-affected countries globally - decided to take action. , ...
(Date:10/10/2017)... , ... October 10, 2017 , ... ... Center’s FirstHand program has won a US2020 STEM Mentoring Award. Representatives of the ... for Excellence in Volunteer Experience from US2020. , US2020’s mission is to change ...
Breaking Biology Technology: