Scientists change genes from daddy’s long legs to daddy’s short legs

For some they are charming, for others they are scary. Regardless of your feelings about the long-legged daddy spider, there’s a good chance you’ve seen the ubiquitous arachnid cross a wall or across its silky web. (And no, he’s definitely not capable of killing you.)

Now, scientists have done something with a species of house spider that you certainly haven’t seen before. They created “short-legged daddy” specimens by altering the genes of the creatures.

Researchers led by Guilherme Gainett of the University of Wisconsin-Madison first sequenced the genome of Phalangium opilio (technically not a spider but a close relative), considered one of the most widespread among more than 6,000 different species long-legged daddy’s – also known as reapers – documented around the world.

Next, the scientists used a technique called RNA interference to turn off, or “knock down,” a pair of genes associated with leg development in hundreds of long-legged daddy embryos. The result was that six of the animals’ eight paws were about half the size of their normal, unmodified counterparts.

The legs appeared to be transformed into another type of appendage, known as the pedipalp, which is used for handling food.

“The daddy long legged genome has great potential to clarify the complex history of the evolution of the arachnid genome and the body plane, as well as reveal how daddy’s long legs make their unique long legs,” said Gainett.

The study is published in the latest issue of the journal Proceedings of the Royal Society B. The research team hopes the work will facilitate the development of more sophisticated tools for functional genetics.

“For the future, we are interested in understanding how genes give rise to new characteristics of arachnids, such as spider fangs and scorpion claws, and in leveraging the genome to develop the first transgenic harvesters”, Gainett added.

As of yet, there are no plans to genetically modify a long-legged daddy species that is in fact as poisonous as the old urban myth claims. This sequel to Arachnophobia will have to wait.