Genomes of two spiders offer new information about venom and silk production

Cristina G. Pedraz/DICYT Danish, Chinese and Saudi researchers have sequenced the genome of two spider species: the Brazilian one called tarantula with “white knees” Acanthoscurria geniculado and the African spider called terciopelo Stegodyphus mimosarum. The data have contributed with information about genes and proteins related to venom and silk production, information which could be applied in the pharmacological field in the case of venom and in the biomaterials field in the case of silk.

This is what the scientific team, headed by Trine Bilde, states in an article published in Nature Communications. They explain that, “spiders are predators with ecological value that have complex venom and an extraordinarily resistant silk, which allows them to capture big preys”. Spiders are considered a key species to control insect populations and plagues. The way they use venom and silk allows them to subdue and capture their preys efficiently, with minimum energy performance.

This is what makes the scientists interested in knowing more about them. In order to do it, they have sequenced these species’ genome and transcriptome, which represent the two most important taxonomic groups of spiders. “Spider genomes are big with short exons and long introns, which remind mammal genomes”, they assure.

The study identifies new proteins which may be related to the processing and activation of toxins in the venom and allows new knowledge about the composition of proteins that form silk. In this way, the scientists show that the venom’s genes have evolved by sequential duplication and that the venom’s toxic effect is probably activated by the proteases found in it. On the other hand, the combination of silk genes “shows a very dynamic evolution, with new types of genes and proteins and a new use of aciniform silk”, the one they use to wrap up their preys.

These results may be utilized to promote the use of venom in neurotoxins and insecticides production as well as in new developments in the field of biomaterials, employing silk proteins to create new materials.

Inhabitant of the North of Brazil

The white knees tarantula, Acanthoscurria geniculado, lives in the north of Brazil. It measures between 8 and 20 centimeters and has a special feature of having shining white hair in its legs joints, what contrasts with its body with black hair and its purple urticating bristles in the abdomen. It feeds on small animals, insects as well as mammals, and it lives in dens, under rocks and rotting trees.

	Bibliography
	Sanggaard, K. W., Bechsgaard, J. S., Fang, X., Duan, J., Dyrlund, T. F., et al. (2014). “Spider genomes provide insight into composition and evolution of venom and silk”. Nature Communications. http://dx.doi.org/10.1038/ncomms4765