Fillip Port
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crisprflydesign.bsky.social
Fillip Port
@crisprflydesign.bsky.social
2.4K followers 910 following 280 posts
Scientist at the German Cancer Reseach Center in Heidelberg. We develop genome engineering tools for functional genomics. #CRISPR #Drosophila #openscience
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crisprflydesign.bsky.social
So multiplexed Cas12a is safe and specific, but does it actually improve knockout efficiency? Direct comparisons with two established Cas9 libraries show superior performance, uncovering phenotypes that existing approaches miss.
Part of figure 6 showing the results of a systematic comparison of mutagenesis with Cas12a sgRNA arrays to two currently used Cas9 sgRNA libraries. in both cases multiplexed Cas12a editing outperformed current technology and identified several phenotypes missed by established technology.
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
The results were very reassuring: >99% of sgRNA arrays showed on-target activity, while we detected no reproducible off-target cutting on the chromosome arms we screened.
Part of figure 5 showing that Cas12a activity is only detected on chromosome arms with sgRNA arrays targeting genes located on this arm and not elsewhere.
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
Another potential problem: proximity effects, where cutting one gene also deletes neighbors or entire chromosome arms. Testing genes adjacent to characterized loci, we found minimal evidence of such effects in Drosophila (though rare cases do occur).
Part of figure 4 that shows that targeting uncharacterised genes with Cas12a sgRNA arrays does not recapitulate phenotypes known to arise from disruption of neighboring genes (with rare exceptions).
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
As expected, DNA cutting causes an increase in cell death, which is moderate when cut sites are clustered, but excessive when they are distributed over different chromosomes (which is likely to give rise to genomic rearrangements).
Figure 3 showing the number of apoptotic cells in the wing disc epithelium after clustered or dispersed CRISPR cutting. While clustered cuts are moderately toxic, cuts on different chromosomes are highly detrimental.
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
We systematically tested Cas12a mutagenesis with 4 sgRNAs per gene in Drosophila. This included building a modular toolkit: sgRNA arrays for 800+ genes, optimized Cas12a transgenes, and activity reporters to map and measure Cas12a activity in vivo.
Part of Figure 2 showing the different tools we build for multiplexed Cas12a mutagenesis in flies.
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
Make your gene knockouts more efficient with multiplexed Cas12a sgRNAs. Our new paper is out now, with tools available from @addgene.bsky.social , www.plasmids.eu and @vdrc-flies.bsky.social.

www.nature.com/articles/s41...

#CRISPR #geneediting #Drosophila 🧪🧬✂️🔬🪰

Summary 🧵 below.
Header image with the paper title: "Improved in vivo gene knockout with high specificity using multiplexed Cas12a sgRNAs"
January 29, 2026 at 9:26 AM
crisprflydesign.bsky.social
🤯This is wow! Molecular mechanism of mRNA export. by @juliusbrennecke.bsky.social @plaschkalab.bsky.social

www.nature.com/articles/s41...
Illustration of the molecular mechanism controlling mRNA export.
November 6, 2025 at 5:20 PM
crisprflydesign.bsky.social
High levels of Cas9 are toxic in sensory neurons. Reducing Cas9 levels with uORFs avoids toxicity and is compatible with efficient editing. From @thompsonpeerlab.bsky.social. Fly lines @vdrc-flies.bsky.social

#CRISPR #Drosophila

www.biorxiv.org/content/10.1...
Figure from the preprint showing sensory neuron morphology with different levels of Cas9 expression.
October 4, 2025 at 9:10 PM
crisprflydesign.bsky.social
Hey @nature.com What's up with your share buttons? Can we please also get 🦋 and 🦣 options to not exclusively promote the network of the guy who has done more than most to harm US science?
July 16, 2025 at 5:46 PM
crisprflydesign.bsky.social
Some PIs will stop at nothing to motivate their lab members. 🧪
Graffiti at the end of an underpass in Heidelberg saying 'LAB!'.
July 12, 2025 at 11:41 AM
crisprflydesign.bsky.social
Journal spam often gets it wrong, but I do agree that "{title}" is a particularly significant study of mine. 😂🙄
Email invitation to a spam journal based on a previous study titled "{title}"
June 23, 2025 at 3:04 PM
crisprflydesign.bsky.social
Proud parenting moment 🎸
F1 playing guitar at a school band gig.
June 21, 2025 at 8:12 PM
crisprflydesign.bsky.social
Oh nice. We were there just a few days ago. Did a nice hike up to Lac Bleu between Haudères and Arolla. Nice on a hot day, as most is in the forest.
Picture of Lac Bleu in Valais/Switzerland.
June 15, 2025 at 7:15 PM
crisprflydesign.bsky.social
Using #CRISPR to send selected mRNAs to specific subcellular compartments. Exciting technology to probe and harness the spatial organisation of transcripts.

www.nature.com/articles/s41...
Screenshot from the linked paper that used RNA-targeting Cas13 to link mRNAs to motor proteins for intracellular transport.
May 27, 2025 at 6:51 AM
crisprflydesign.bsky.social
CRISPR mutagenesis is also not perfect. A common limitation is generation of genetic mosaics, where only some cells carry gene knockouts. But our new generation of tools substatially improves on that. Described in the preprint below with flies on their way to VDRC:
www.biorxiv.org/content/10.1...
May 26, 2025 at 7:29 AM
crisprflydesign.bsky.social
Why use #CRISPR in #Drosophila when RNAi works so well? Because for some genes well is not good enough.

Check out new preprint from the lab demonstrating a role for Vps15 in Wingless trafficking. Something that was missed in several RNAi screens.

www.biorxiv.org/content/10.1...
Images from the linked preprint showing Wingless stainings in the Drosophila wing imaginal disc. Targeting vps15 with two indepependent RNAi lines (paper also shows the same with a third line) does not result in a phenotype. In contrast, targeting vps15 with two independent sgRNA constructs and Cas9 results in strong accumulation of Wingless protein in perturbed cells.
May 26, 2025 at 7:29 AM
crisprflydesign.bsky.social
Progress 🌻
Picture of a front yard garden. The earth is mostly bare with only a few shrubs visible. The same garden two years later. There is hip-high vegetation including various flowers in full bloom.
May 4, 2025 at 8:44 PM
crisprflydesign.bsky.social
Out of office post.

#takeabreak
#dolomites
April 18, 2025 at 4:36 PM
crisprflydesign.bsky.social
🙄
April 8, 2025 at 7:51 AM
crisprflydesign.bsky.social
That's an interesting twist of the "it's not 'fruit fly', it's 'vinegar fly'" debate.
March 6, 2025 at 10:14 PM
crisprflydesign.bsky.social
Heidelberg today. Together for freedom, diversity, and democracy.
Pictures from a march against fascism in Heidelberg a week before the German general election. Pictures from a march against fascism in Heidelberg a week before the German general election. Pictures from a march against fascism in Heidelberg a week before the German general election.
February 15, 2025 at 4:43 PM
crisprflydesign.bsky.social
Sunday beaking: Yoghurt-Emmer Sourdough.

#bread
Bread loaf after proofing during the bench rest. Same bread after baking.
January 12, 2025 at 9:53 PM
crisprflydesign.bsky.social
This is such an iconic shot. I suspect the other contestants in this competition did not feel particularly optimistic.
Screenshot from a Guardian article about the World Sports Photography award. Overall winner was an iconic image of the surfer Gabriel Medina at the Olympics.
January 10, 2025 at 7:49 AM
crisprflydesign.bsky.social
This is a nice example, because it's know what happens when smo LOF mutations are induced with different efficiency. The currently used Cas9 tools phenocopy induction with medium efficiency, while multiplex Cas12a editing looks exactly like highly efficient induction of known smo LOF clones.
January 7, 2025 at 9:25 PM
crisprflydesign.bsky.social
The power of Cas12a-enabled sgRNA multiplexing for gene disruption.

Today’s example: smoothened
1/3
#CRISPR #Drosophila
Images of Drosophila wings. Control wings expressing CRISPR components exclusively in the germline have normal morphology. Targeting the central hedgehog signaling component smoothened with Cas9 and either one or two sgRNAs results in wings of reduced size and missing and ectopic vein tissue (middle panels). Targeting smoothened with Cas12a+ and four sgRNAs results in very small wings without veins.
January 7, 2025 at 9:25 PM