Vikram Shivakumar

Vikram Shivakumar

@vikramshivakumar.bsky.social

PhD Student @ JHU Langmead Lab

179 followers142 following42 posts

Vikram Shivakumar reposted

Must-see new tool from me and Alex! I hurt my back a few weeks ago and was confined to the couch. I used my "break" to play around with webassembly and ended up vibe-coding an AMAZING interactive dotplotter. Passed my prototype to Alex to clean up and extend. Check out his release thread!

Alex Sweeten@alexsweeten.bsky.social

Excited to announce ModDotPlot Browser! A interactive genomic dotplot viewer that runs entirely in a web browser. Load and explore whole chromosomes in seconds! Try it here: marbl.github.io/ModDotPlot-B... User guide:
 github.com/marbl/ModDot... 1/4

Probably the most useful exploratory tool I’ve seen all in a web browser. It’s so quick and easy to use. Super cool stuff. And also an excellent teaching resource to show alignments and dotplots.

Alex Sweeten@alexsweeten.bsky.social

Excited to announce ModDotPlot Browser! A interactive genomic dotplot viewer that runs entirely in a web browser. Load and explore whole chromosomes in seconds! Try it here: marbl.github.io/ModDotPlot-B... User guide:
 github.com/marbl/ModDot... 1/4

Vikram Shivakumar reposted

Vikram Shivakumar reposted

Vikram Shivakumar reposted

Shredtools is making it easier to explore regions across a pangenome by quickly finding matching genomic regions across hundreds of genomes. The tool can identify a gene region across 476 human genomes in approximately half a second.  Read more: www.biorxiv.org/content/10.6...

biorxiv.orgNavigating the pangenome coordinate system with ShredtoolsExisting notions of pangenome coordinates rely on hard-to-compute multiple sequence alignments. On the other hand, pangenome-wide exact unique matches (multi-MUMs) can be computed efficiently, and rep...

Vikram Shivakumar reposted

Vikram Shivakumar reposted

1/ Excited to share our preprint ImpuT2T: a pangenome-based assembly patching tool ImpuT2T scaffolds draft human assemblies with a pangenome (HPRC2) and patches gaps by leveraging linkage disequilibrium and sequence identity between contigs and reference haplotypes Code: github.com/maojanlin/Im...

biorxiv.orgImpuT2T: Pangenome-Based Patching for Human Genome AssembliesWith improvements in sequencing and assembly have come many high-quality telomere-to-telomere assemblies and reference pangenomes. However, the long-read sequencing recipes needed for high quality ass...

10/ The Shredtools HPRC tool is a fully client-side site, fetching multi-MUMs hosted through the AWS Open Data Sponsorship. It enables querying any region from any assembly across HPRC to fetch syntenic regions, even visualizing synteny directly in the browser. Give it a go and send any feedback!

8/ Shredtools queries are efficient thanks to a new index of multi-MUMs. We store MUMs in a binary "bumbl" format, and build a "bumbl.bi" index, similar to a bai file for a bam file. This enables rapid, random access fetching of matches in any query region from any assembly in a collection.

6/ Shredtools extract depends on the coverage of multi-MUMs. Another method, enhance, finds additional matches between MUMs that serve as additional markers of the coordinate system, approaching a full multiple alignment. Figure: extract across the A. thaliana pangenome ("enhanced" MUMs in purple)

7/ multi-MUMs are also efficient to compute. Existing methods can use pairwise alignments to project coordinates across a pangenome, and we show Mumemto multi-MUMs are an order of magnitude faster and more memory-efficient to compute than pairwise genome alignments.

4/ Shredtools reports "bounds", the distance between the ouput region to the nearest flanking MUMs. Querying gene regions across HPRC2 assemblies, more than 80% of regions were immediately flanked by a multi-MUM, yielding exact coordinates across all 476 human assemblies!

5/ are multi-MUMs useful as a coordinate system? We found that multi-MUMs are the ideal choice over unique k-mers, which have lower coverage. And often, the choice of k varies greatly with various parameters of the pangenome.

2/ ⭐ highlight of the release: we implemented shredtools for the HPRC human pangenome as a browser-based, client-side app to query and fetch syntenic regions across the pangenome. You can even visualize synteny right in the browser! Read on for how the method works.

3/ Shredtools uses collinear multi-MUMs from Mumemto as a "coordinate system" for the pangenome, without computing a multiple alignment or graph. The highlight feature is extract: given a local region in any assembly, using multi-MUMs, Shredtools fetches syntenic regions across the whole pangenome!

Very bittersweet for me too. I’ll always be grateful for your mentorship and for the amazing lab and community I’ve been fortunate to grow alongside over the years. I’ll definitely miss Baltimore and the wonderful genomics community at Hopkins. Looking forward to the next chapter in Cambridge!

Ben Langmead@benlangmead.bsky.social

Proud & bittersweet day, hooding the superb @vikramshivakumar.bsky.social. We will miss your energy, camaraderie & leadership. Your work truly speaks for itself, both scholarly and Mario Kart related. Wishing you the absolute best as you move to Cambridge, UK to be an ESPOD fellow!

Really excited to see our new work in scaling Mumemto to any size pangenome published in Genome Research this morning. And right on cue with the great opportunity to present this work at #GI2025 this week.

Genome Research @genomeresearch.bsky.social

#GI2025 Vikram Shivakumar from Ben Langmead's lab (@benlangmead.bsky.social) presents "MumemtoM - partitioned Multi-MUM finding for scalable pangenomics ". Now published in Genome Research @genomeresearch.bsky.social. Read full text here ➡️ tinyurl.com/Genome-Res-2...

Vikram Shivakumar reposted

Replying to @sinamajidian.bsky.social

Nicole Brown gave a fantastic talk on Identifying introgressions across pangenomes with Panagram It uses k-mer conservation to annotate genomic variation across hundreds of genomes, followed by normalization of k-mer profiles to identify introgression events github.com/kjenike/pana... #GI2025

Looking forward to lots of great talks from JHU folks at CSHL this week!

JHU Computer Science@jhucompsci.bsky.social

Check out the cool work being presented by our students at Genome Informatics! This year’s event was co-organized by @benlangmead.bsky.social, & features talks from @vikramshivakumar.bsky.social & more, plus posters from @alexsweeten.bsky.social, @maojanlin.bsky.social, & @sinamajidian.bsky.social:

Vikram Shivakumar reposted

Replying to @aphillippy.bsky.social

If that’s not enough, we threw in a complete, T2T giraffe genome! Giraffe genomes are pretty cool. Almost all of their chromosomes are Robertsonian fusions of the typically telocentric ruminant chromosomes. 🐄 vs. 🦒...

Vikram Shivakumar reposted

Last week we were in the Washington Post for our characterization of Robertsonian chromosomes. This week we are entering our 10th day of being shut down and all of our research is on hold. To help me feel not-so-bad, here is a thread of some studies we released right before the shutdown 🧵 [1/n]...

Vikram Shivakumar reposted

Excited to share our EvANI benchmarking workflow, published in Briefings in Bioinformatics doi.org/10.1093/bib/... Computing average nucleotide identity (ANI) is neither conceptually nor computationally trivial. Its definition has evolved over years, with different meanings and assumptions (1/5)

Vikram Shivakumar reposted

Vikram Shivakumar telling us about "Partitioned Multi-MUM finding for scalable pangenomics" #WABI25! So many kinds of matches!

Vikram Shivakumar reposted

This preprint from Helen Sakharova is one of the coolest things to come out of my lab: “Protein language models reveal evolutionary constraints on synonymous codon choice.” Codon choice is a big puzzle in how information is encoded in genomes, and we have a new angle. www.biorxiv.org/content/10.1...

biorxiv.orgProtein language models reveal evolutionary constraints on synonymous codon choiceEvolution has shaped the genetic code, with subtle pressures leading to preferences for some synonymous codons over others. Codons are translated at different speeds by the ribosome, imposing constrai...

Really excited to see this published! To more mum-finding 🍻

Ben Langmead@benlangmead.bsky.social

Now published! Note that since Vikram's original post (quoted here), he's made it easy to dynamically update a set of multi-MUMs (e.g. when more genomes are added to a pangenome) and to find multi-MUMs for huge collections like HPRCv2 genomebiology.biomedcentral.com/articles/10....

Vikram Shivakumar reposted

1/5 We introduce Movi Color, led by Steven Tan (a brilliant undergrad member of Langmead lab) for taxonomic and multi-class classification. It uses a full-text index based on the move structure and does not rely on predefined values (like k-mer length) for index building. github.com/mohsenzakeri...

github.comRelease Movi Color · mohsenzakeri/MoviThis version introduces Movi Color. Movi rows are augmented with run colors, defined based on the origin of the suffixes within each run. The Movi Color index can be built by either an additional ...
bioRxiv Bioinfo@biorxiv-bioinfo.bsky.social

Movi Color: fast and accurate long-read classification with the move structure https://www.biorxiv.org/content/10.1101/2025.05.22.655637v1