First CRISPR-edited spider spins red fluorescent silk

In a reported first, researchers have successfully used CRISPR gene editing in spiders, inserting the gene for a red fluorescent protein into the major ampullate silk gene of Parasteatoda tepidariorum. The edited orb weaver spun crimson fibers and passed the glow to its young, evidence that spider silk can now be genetically tuned for bespoke materials and biomedical uses.

The study was published in Angewandte Chemie, International Edition.

Professor Dr. Thomas Scheibel, senior author of the study from the University of Bayreuth, highlighted the promise for materials science. In a statement, he noted that the technique “could be used to further increase the already high tensile strength of spider silk.”

The team also employed CRISPR to “knock-out” (disable) the sine oculis gene, which resulted in offspring with total eye loss. This finding confirmed the gene’s role in the development of spider eyes. Simultaneously, it demonstrated CRISPR’s utility for fundamental studies in spider developmental genetics.

Considering the wide range of possible applications, it is surprising that there have been no studies to date using CRISPR-Cas9 in spiders —Professor Dr. Thomas Scheibel

The knock-in experiment shows that researchers can introduce new genetic code into the MaSp2 silk gene without disrupting how the spider assembles its silk fibers. This is a big step, as it opens the door to potentially weaving new functions. Potential applications might include antimicrobial components, conductive elements, or even drug-delivery mechanisms, which could be incorporated into dragline silk as it’s being spun. This kind of “build-as-you-spin” engineering could lead to novel “living composite” fibers, offering a way around the often complex and costly chemical additions required after spinning in many other biomaterial approaches.

The Office of Naval Research and U.S. Air Force backed this work, which demonstrates how CRISPR can allow researchers to study aspects of spider biology previously difficult to access, such as genes involved in mid-to-late nymphal development or early cell-to-cell communication.

As the authors note, “The ability to employ CRISPR gene engineering in spider silk holds significant promise for research concerning material sciences.” To date, output is limited. In their paper, the researchers report microinjecting CRISPR-Cas9 ribonucleoproteins into adult female P. tepidariorum, then screening 59 egg sacs. Only four of these sacs produced edited hatchlings, yielding a roughly 6% to 7% efficiency rate per egg sac. Still, these mutants demonstrated two key outcomes. First, knocking out the sine oculis gene mentioned above, and two, knocking in a gene for a red fluorescent protein within the MaSp2 silk gene yielded scarlet fibers. The researchers accomplished this latter without detectably disrupting the silk’s assembly. That, in turn, suggests the potential for functionalized silk that maintains good structural properties.

Another caveat: spiders are cannibalistic, so scaling beyond boutique labs could require novel husbandry.