World's largest animal genome belongs to locust

(Press-News.org) Contact information: Jia Liu
liujia@genomics.cn
BGI Shenzhen
World's largest animal genome belongs to locust Offering new insight into explaining their swarming and long-distance migratory behaviors January 14, 2014, Shenzhen, China - Researchers from Institute of Zoology, Chinese Academy of Sciences, BGI and other institutes have successfully decoded the whole genome sequence of Locust (Locusta migratoria), the most widespread locust species. The yielded genome is remarkably big- at 6.5 gigabytes, which is the largest animal genome sequenced so far. The latest study has been published online in the journal Nature Communications.

It surprises us that a single locust can eat its own bodyweight in food in a single day; this is, proportionately, 60 times a human's daily consumption. They are capable of inflicting famine and wiping out livelihoods when they swarms, which can cost countries billions of dollars in lost harvests and eradication efforts.

In this study, researchers sequenced Locusta migratoria using next-gen sequencing technology, totally yielding 721Gb of data, which covered 114 × of the 6.3Gb locust genome size. They annotated and predicted about 17,307 gene models, and identified over 2,639 repeat gene families. Moreover, they discovered that the top ten repeat families only represented 10% of the total genome sequences, suggesting that there were no dominant families in the L. migratoria genome.

Compared with other reference insect genomes, researchers found the reason why locust has such large genome is transposable element proliferation combined with slow rates of loss for these elements. According to statistics, repetitive elements constituted 60% of the assembled genome. The transposable element in the Locust genome was expanded when comparing with the other insects. Besides, they also found that the locust genome exhibited the lowest rate of DNA deletions relative to the other insects.

To investigate the potential involvement of epigenetic regulation in locust phase change, researchers performed comparative methylome and transcriptome analysis. One interesting finding was that repetitive elements were highly methylated and introns had higher methylation levels than exons in locust genome. It was also noteworthy that there had changes in genes involved in the regulation of the cytoskeletal microtubular system and in neuronal activity during the onset of phase change in locusts from solitarious to swarm.

As we all know, locust has an most distinguishing feature- the long-distance flight- which enables them can fly at speed of hundreds of kilometers an hour, or even cross the ocean. In this study, researchers found that locust had developed a highly efficient energy supply system by expansion genes in lipid metabolism and detoxification to fulfill the intensive energy consumption during their long-distance flight. The expansion of its gustatory and olfactory receptor gene families is for its strong adaptation to host plant recognition.

To advance the development of new effective insecticides, researchers identified the gene targets for pest control and new insecticides, such as cys-loop ligand-gated ion channels and G-protein-coupled receptors, which are considered to be major traditional insecticide targets, and the repertoire of several biological processes that may serve as mechanistic targets and lead to the development of specific and sustainable pest control methods.

### About BGI BGI was founded in 1999 with the mission of being a premier scientific partner to the global research community. The goal of BGI is to make leading-edge genomic science highly accessible through its investment in infrastructure that leverages the best available technology, economies of scale, and expert bioinformatics resources. BGI, which includes both private non-profit genomic research institutes and sequencing application commercial units, and its affiliates, BGI Americas, headquartered in Cambridge, MA, and BGI Europe, headquartered in Copenhagen, Denmark, have established partnerships and collaborations with leading academic and government research institutions as well as global biotechnology and pharmaceutical companies, supporting a variety of disease, agricultural, environmental, and related applications.

BGI has established a proven track record of excellence, delivering results with high efficiency and accuracy for innovative, high-profile research which has generated over 250 publications in top-tier journals such as Nature and Science. These accomplishments include sequencing one percent of the human genome for the International Human Genome Project, contributing 10 percent to the International Human HapMap Project, carrying out research to combat SARS and German deadly E. coli, playing a key role in the Sino-British Chicken Genome Project, and completing the sequence of the rice genome, the silkworm genome, the first Asian diploid genome, the potato genome, and, most recently, have sequenced the human Gut metagenome, and a significant proportion of the genomes for 1,000 genomes. For more information about BGI please visit http://www.genomics.cn.

Contact Information: Bicheng Yang, Ph.D.
Public Communication Officer
BGI
+86-755-82639701
yangbicheng@genomics.cn
http://www.genomics.cn