Skip navigation
You are here: Home > NaturePlus > Science News > Science News > Tags > dna

Science News

2 Posts tagged with the dna tag

Tapeworm genomics

Posted by John Jackson Dec 22, 2011

Genome data represent the largest and most diverse set of heritable characters for comparative evolutionary studies. In collaboration with the The Wellcome Trust Sanger Institute, we have recently characterised and assembled the complete genome of Hymenolepis microstoma, a classical tapeworm model with over 50 years of literature supporting it.


Together with colleagues from the University of Würzburg, Germany, Peter Olson and Magdalena Zarowiecki have recently published the first insights into the gene content and general characteristics of tapeworm genomes based on data from Hymenolepis and the medically important genera Echinococcus and Taenia. Findings show that tapeworms have small genomes at ~150 Mb, compared to ~350 Mb in flukes and over 700 Mb in free-living planarians.


Their genomes are compact, containing few repetitive or mobile elements, and appear to contain a majority of common gene families, albeit they may be missing ~10% of 'core' or universal metazoan genes found in free-living animals and typically show a reduction in the number of genes per family. A number of necessary biosynthesis components are missing, such as genes required to synthesise cholesterol, and hence these essential molecules must be taken directly from the host. Data are now publicly available via the Web and promise to accelerate the pace of research in the field by eliminating the need for time consuming and costly genetic manipulations at the bench.

PD Olson, M Zarowiecki, F Kiss and K Brehm (2011). Invited review: Cestode genomics--progress and prospects for understanding basic and applied aspects of flatworm biology. Parasite Immunology [doi: 10.1111/j.1365-3024.2011.01319.x]


The Rappemonads, a new branch of the tree of life has been traced: Dr  Tom Richards (Zoology), in collaboration with scientists from Monterey  Bay Aquarium Research Institute USA, and Dalhousie University Canada,  has identified a previously unknown group of single-celled organisms related to red algae. These newly discovered marine and freshwater cells contain plastids (of which chloroplasts are an example) that photosynthesise, producing energy from sunlight.

It is  estimated that almost 2 million species of plants, animals, fungi and other life forms have been described and  identified in the past two hundred and fifty years.  Much of this science of diversity has been based on physical form - morphology - but in recent years DNA sequencing has made it possible to explore biodiversity in new ways and different environments.  It is thought that much of the biodiversity remaining to be discovered - possibly around 10 million species - lies in single-celled organisms and bacteria, which are too small to see with the naked eye and live in vast numbers in soils, water or sediments. Our understanding of what biodiversity is, and why it is important in ecosystems, continues to change as the technology develops.

Tom and his collaborators used DNA techniques to to investigate unidentified microbes from shorelines in the UK and US, from open sea water and from UK fresh waters.  Their DNA results were compared with information in large scientific databases and proved to be from a new group of organisms, the rappemonads, related to algae, phytoplankton and seaweeds, a unique form of photosynthetic life. It appears that rappemonads occur from time to time in large numbers in transient oceanic blooms, suggesting that it may play a significant role in the global carbon cycle and marine food webs.

Kim, E., Harrison, J., Sudek, S., Jones, M. D. M., Wilcox, H. M., Richards, T. A., Worden, A. Z., & Archibald, J. M. 2011. Newly identified and diverse plastid-bearing branch on the eukaryotic tree of life. Proc. Natl. Acad. Sci. U.S.A. Online Early.