Scientists create a new standard genome for a highly studied worm

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A new study conducted by Cornell University revealed that the genome of a widely documented worm, on which many studies are based, was defective. Now a new genomic sequence will set the record straight and improve the accuracy of future research.

When scientists study the genetics of an organism, they start with a standard genome sequenced from a single, basic strain. It's like a chessboard in a game of chess: each board is basically the same.

A model organism used by scientists in research is a worm called Caenorhabditis elegans. The worm – the first multicellular eukaryote (animal, plant or fungus) to have its genome sequenced – is easy to grow and has a simple biology, without bone, heart or circulatory system. At the same time, it shares many genes and molecular pathways with humans, making it a model of choice for studying gene function, drug treatments, aging, and human diseases such as cancer and diabetes.

Genetic studies of C. elegans were based on a single strain, called N2, which researchers have been commissioning for decades C. elegans storage center at the University of Minnesota. Although people tried to meet a common standard, individual laboratories developed N2 strains themselves, which led to their transformation.

"In the last decade, with more advanced genetic experiments using high levels of DNA sequencing, scientists have been alarmed to find that there was no longer a single strain of DNA." laboratory that everyone was using, "said Erich Schwarz, assistant professor of research at the Molecule Department. Biology and genetics. "In 40 years, many different strains of N2 have appeared, we can not count on any of them to do experiments."

Schwarz is the lead author of a new study published in Genome research which describes a single genetically clean strain, called VC2010, in which each individual is truly identical. Schwarz and his colleagues at the University of Tokyo, Stanford University, the University of British Columbia, and the University of Minnesota have used advanced techniques to sequence the VC2010 genome and create a new standard.

As part of the study, the researchers compared VC2010 to the original N2 genome. They were expecting an almost perfect match but had a surprise. "In addition to the 100 million nucleotides we expected to see, we discovered an additional 2 million nucleotides, an additional 2% of the genome," which was hidden in the original, probably because of the limitations of the original. old technology, said Schwarz.

Schwarz added that similar problems probably occurred in standard genomes of other organisms, including humans. "This shows us that having the true full DNA of an animal is not as easy as we thought," he said.

Other laboratories have started using modern sequencing tools to reassess other genomes, which has implications for synthetic biology, where scientists create life, such as bacteria, from nothing. "Having a very good DNA sequence is an important baseline," said Schwarz.