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Vikram Shivakumar

@vikramshivakumar.bsky.social
180 followers 142 following 40 posts

PhD Student @ JHU Langmead Lab

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Reposted by Vikram Shivakumar
Human Pangenome Reference Consortium @humanpangenome.bsky.social · 24/09/2026
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.org
Navigating the pangenome coordinate system with Shredtools
Existing 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...
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Reposted by Vikram Shivakumar
Human Pangenome Reference Consortium @humanpangenome.bsky.social · 26/08/2026
Pangenome coordinates can be complex... Shredtools offers a new approach using exact matches to query pangenome data efficiently. Its tools can extract syntenic regions across hundreds of genomes, making pangenome-scale exploration more accessible. pubmed.ncbi.nlm.nih.gov/42465356/
pubmed.ncbi.nlm.nih.gov
Navigating the pangenome coordinate system with Shredtools - PubMed
Existing 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 represent conserved stretches of columns in the underlying MSA. We introduce Shredtools, which uses mul …
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Mao-Jan Lin @maojanlin.bsky.social · 03/08/2026
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.org
ImpuT2T: Pangenome-Based Patching for Human Genome Assemblies
With 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...
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Ben Langmead @benlangmead.bsky.social · 29/07/2026
📢 Genome Informatics 2026 (Hinxton UK + virtual, 2–4 Dec) is coming! Some confirmed speakers now listed: coursesandconferences.wellcomeconnectingscience.org/event/genome... Early-bird registration & bursary deadlines: 7 Sept. Abstract deadline: 5 Oct. Please submit your work & join us!
Wellcome Genome Campus aerial shot
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Reposted by Vikram Shivakumar
bioRxiv Bioinfo @biorxiv-bioinfo.bsky.social · 29/07/2026
ImpuT2T: Pangenome-Based Patching for Human Genome Assemblies www.biorxiv.org/content/10.64898/20…
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Vikram Shivakumar @vikramshivakumar.bsky.social · 15/07/2026
1/ Excited to share the newest tool in the pangenome MUMiverse: Shredtools! Shredtools enables a user to navigate the pangenome coordinate system with multi-MUMs. More in the thread🧵 Code: github.com/vikshiv/shredtools Interactive tool for querying HPRC assemblies: vikshiv.github.io/shredtools
biorxiv.org
Navigating the pangenome coordinate system with Shredtools
Existing 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...
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Sina Majidian @sinamajidian.bsky.social · 09/07/2026
JOB ALERT! I'm hiring two postdocs in Computational Genomics to join our lab in beautiful Gothenburg, Sweden. Please share and repost! CGRLab.github.io/research/
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Ben Langmead @benlangmead.bsky.social · 22/06/2026
Movi 2 has appeared (as an advance article) in Bioinformatics 🧬 Faster, leaner pangenome queries — half the memory of Movi 1, ~30% faster. Paper: academic.oup.com/bioinformati... Code: github.com/mohsenzakeri/Movi (1/6)
academic.oup.com
Validate User
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KamilSJaron.bsky.social @kamilsjaron.bsky.social · 19/06/2026
Last chance to register for a Scalable genomics course this autumn! It will be a banger. With @katiejenike.bsky.social @richard-durbin.bsky.social @npmalfoy.bsky.social and @vikramshivakumar.bsky.social! coursesandconferences.wellcomeconnectingscience.org/event/scalab...
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Vikram Shivakumar @vikramshivakumar.bsky.social · 21/05/2026
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!
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Vikram Shivakumar @vikramshivakumar.bsky.social · 13/03/2026
Thank you! And thanks to all the wonderful people at JHU I’ve had the pleasure of working with during my PhD. And of course, to my advisor @benlangmead.bsky.social and my super supportive thesis committee members @aphillippy.bsky.social and @mikeschatz.bsky.social. Excited to 🇺🇸 -> 🇬🇧 soon!
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Reposted by Vikram Shivakumar
Matthew Nguyen @mnguyen667.bsky.social · 09/03/2026
1/ Excited to share my first first-author preprint from my PhD! We introduce Perseus, a lineage-aware confidence estimation framework for taxonomic classification in long-read metagenomics. Preprint: www.biorxiv.org/content/10.6... Code: github.com/matnguyen/Pe...
biorxiv.org
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Dr. Jean Fan @jef.works · 02/03/2026
As an alternative to the h-index, I made the Mentorship Index (M-index) to proxy a scientist's contribution to mentoring junior scientists. Ex. M10-index = # last-author publications where the first author had < 10 pubs. Calculate yours: jef.works/Mentorship-I... Blog: jef.works/blog/2026/03... 🧵👇
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Adam Phillippy @aphillippy.bsky.social · 29/01/2026
New tool from @alexsweeten.bsky.social to find and classify all your satellites: "AniAnn's: alignment-free annotation of tandem repeat arrays using fast average nucleotide identity estimates" 📄 www.biorxiv.org/content/10.6... 📦 github.com/marbl/anianns
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Mitchell R. Vollger @mrvollger.bsky.social · 12/01/2026
I am hiring a staff bioinformatician for my new lab at the University of Utah! Please consider applying if you are on the hunt: employment.utah.edu/salt-lake-ci...
employment.utah.edu
Jobs | University of Utah
Founded in 1850, The University of Utah is the flagship institution of higher learning in Utah, and offers over 100 undergraduate and more than 90 graduate degree programs to over 30,000 students. Uni...
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Reposted by Vikram Shivakumar
Heng Li @lh3lh3.bsky.social · 14/01/2026
I am looking for a postdoc to develop high-performance algorithms in computational genomics. Email or DM me if interested. For more information, see hlilab.github.io/vacancies. RTs appreciated!
hlilab.github.io
HLi Lab - Vacancies
Openings
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Vikram Shivakumar @vikramshivakumar.bsky.social · 07/11/2025
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.
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Sina Majidian @sinamajidian.bsky.social · 06/11/2025
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
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Sina Majidian @sinamajidian.bsky.social · 06/11/2025
Fantastic talk by @vikramshivakumar.bsky.social Mumemto—Scalable multi-MUM finding for pangenomes Papers biorxiv.org/content/10.1101/2025.05.20.654611 & doi.org/10.1186/s13059-025-03644-0 Code: github.com/vikshiv/mume... Very efficient pangenome visualization tool, revealing synteny and variations!
Figure 1: (A) Anchor-based merging requires a common sequence (red) present in each partition. Multi-MUMs are merged by identifying overlaps between partition-specific matches in the anchor coordinate space, and a uniqueness threshold determines if a MUM is still unique in each partition after truncation. (B) String-based merging enables compu- tation of multi-MUMs between partitions without a common sequence. An example tree (left) is shown, highlighting the use case where partial multi-MUMs specific to internal nodes (starred) can be computed by merging subclade-based partitions up a tree. (right) MUM overlaps are computed by running Mumemto on the MUM sequences, and the uniqueness threshold array ensures overlaps remain unique across the merged dataset. (C) An example Burrows-Wheeler Transform (BWT), matrix (BWM), and Longest Com- mon Prefix (LCP) array, with sequence IDs for each suffix shown (ID). A non-maximal unique match (UM) is shown, and the uniqueness threshold for this match is found us- ing the flanking LCP values. (D) A partial multi-MUM (in blue) is found in all-but-one sequence (excluded in red). Using two anchor sequences (red and orange), all-but-one partial MUMs can be computed using an augmented anchor-based merging method (sec- tion 2.6).
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Vikram Shivakumar @vikramshivakumar.bsky.social · 04/11/2025
Looking forward to lots of great talks from JHU folks at CSHL this week!
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Reposted by Vikram Shivakumar
Adam Phillippy @aphillippy.bsky.social · 10/10/2025
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. 🦒...
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Adam Phillippy @aphillippy.bsky.social · 10/10/2025
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]...
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Sina Majidian @sinamajidian.bsky.social · 21/09/2025
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)
Figure 1(A) ANI quantifies the similarity between two genomes. ANI can be defined as the number of aligned positions where the two aligned bases are identical, divided by the total number of aligned bases. Historically, ANI was calculated using a single gene family for multiple sequence alignment. Another approach finds orthologous genes between two genomes and reports the average similarity between their CDSs. This method was later extended to whole-genome alignment by identifying local alignments and excluding supplementary alignments with lower similarity. (B) Different ANI tools employ various approaches in calculating ANI values. ANIm, OrthoANI, and FastANI use aligners to identify homologous regions, whereas Mash uses k-mer hashing to estimate similarities. Only alignments with higher similarity represented by green arrows are included in ANI calculations, while red arrows, corresponding to paralogs, are excluded. (C) The proposed benchmarking method evaluates the performance of different tools using both real and simulated data. It assumes that more distantly related species on the phylogenetic tree should have lower ANI similarities. This is measured by calculating the statistics of Spearman rank correlation. We expect a negative correlation between ANI and the tree distance (scatter plot on the right).
https://academic.oup.com/bib/article/doi/10.1093/bib/bbaf267/8160681
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Sina Majidian @sinamajidian.bsky.social · 20/08/2025
Great talk by Vikram @vikramshivakumar.bsky.social on studying pangenomes and synteny visualization in #WABI25 Github: github.com/vikshiv/mume... First paper: genomebiology.biomedcentral.com/articles/10.... Second: www.biorxiv.org/content/10.1... #WABI2025
Anchor-based merging requires a common sequence (red) present in each partition. Multi-MUMs are merged by identifying overlaps between partition-specific matches in the anchor coordinate space, and a uniqueness threshold determines if a MUM is still unique in each partition after truncation. (B) String-based merging enables computation of multi-MUMs between partitions without a common sequence. An example tree (left) is shown, highlighting the use case where partial multi-MUMs specific to internal nodes (starred) can be computed by merging subclade- based partitions up a tree. (right) MUM overlaps are computed by running Mumemto on the MUM sequences, and the uniqueness threshold array ensures overlaps remain unique across the merged dataset. (C) An example Burrows-Wheeler Transform (BWT), matrix (BWM), and Longest Common Prefix (LCP) array, with sequence IDs for each suffix shown (ID). A non-maximal unique match (UM) is shown, and the uniqueness threshold for this match is found using the flanking LCP values. (D) A partial multi-MUM (in blue) is found in all-but-one sequence (excluded in red). Using two anchor sequences (red and orange), all-but-one partial MUMs can be computed using an augmented anchor-based merging method.
(A) Phylogeny of geographically diverse A. thaliana accessions (Lian et al. 2024), with broad geographical regions colored. Internal nodes are labeled with the coverage of partial multi-MUMs across the leaves of each node. Internal node partial MUMs are computed by merging subtree-based partitions progressively up the phylogeny. (B) Global multi-MUM synteny across the full dataset shown in blue (with inversions in green). Global MUMs are computed by merging all partitions together (representing the root node). Additionally, three geographically distinct subgroups are highlighted and partition-specific multi-MUMs (in purple, with inversions in pink) reveal local structural variation in centromeric regions.
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Rob Patro @robp.bsky.social · 20/08/2025
Vikram Shivakumar telling us about "Partitioned Multi-MUM finding for scalable pangenomics" #WABI25! So many kinds of matches!
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Liana Lareau @lianafaye.bsky.social · 07/08/2025
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.org
Protein language models reveal evolutionary constraints on synonymous codon choice
Evolution 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...
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Petra Korlević @petrathepostdoc.bsky.social · 31/07/2025
#SciArt doodle of @vikramshivakumar.bsky.social's talk yesterday at the @sangerinstitute.bsky.social on MUMs* *maximal unique matches in pangenomes, now if you did that on sequenced moms you could do mummoms
comic doodle of Vikram Shivakumar in a sweater and checkered shirt on a pink gradient background, with various elements of the talk to the left: two old moms pointing at MUMs, below an explanation of what those are (large chunks of the same DNA sequence through the genome), at the bottom a few of the organisms worked on: a tomato, a potato, an arabidopsis weed.
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jakobheinz.bsky.social @jakobheinz.bsky.social · 21/07/2025
Excited to share our new preprint on detecting foldback artifacts in long reads with my advisors Matthew Meyerson and @lh3lh3.bsky.social ! Stop by poster C-180 on Wednesday at ISMB/ECCB2025 to learn more and chat!
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Vikram Shivakumar @vikramshivakumar.bsky.social · 21/07/2025
If you’re in Liverpool, stop by my poster A217 at ISMB/EECB 2025, and chat about all things pangenomes, MUMs, and alignment (and the Beatles or Oasis-mania)
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Vikram Shivakumar @vikramshivakumar.bsky.social · 17/06/2025
Really excited to see this published! To more mum-finding 🍻
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Rob Patro @robp.bsky.social · 16/06/2025
🖥️🧬We're thrilled to announce that one of our keynote speakers at #WABI2025 will be the inimitable @benlangmead.bsky.social! wabiconf.github.io/2025/talks/t... Ben's keynote is titled "We are what we index; a primer for the Wheeler Graph era", & it's sure to be a whirlwind tour of full-text indexing!
wabiconf.github.io
We are what we index; a primer for the Wheeler Graph era
Talk by Ben Langmead - WABI 2025
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Mohsen Zakeri @mohsenzakeri.bsky.social · 29/05/2025
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.com
Release Movi Color · mohsenzakeri/Movi
This 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 ...
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Vikram Shivakumar @vikramshivakumar.bsky.social · 27/05/2025
Excited to share a new update to Mumemto, scaling MUM and conserved element finding to any size pangenome! Preprint out now w/ @benlangmead.bsky.social. Mumemto scales to the new HPRC v2 release and beyond, and can merge in future assemblies without any recomputation! 1/n
biorxiv.org
Partitioned Multi-MUM finding for scalable pangenomics
Pangenome collections are growing to hundreds of high-quality genomes. This necessitates scalable methods for constructing pangenome alignments that can incorporate newly-sequenced assemblies. We prev...
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Arun Das @arun-das.bsky.social · 15/05/2025
Our pre-print on investigating variation in South Asian genomes is now out! Thank you to @mikeschatz.bsky.social, @rajivmccoy.bsky.social and @aabiddanda.bsky.social for all their work on this. 🧵 A thread on the key results and takeaways from our work:
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Sara Carioscia @saracarioscia.bsky.social · 07/05/2025
If you are here at #bog25 please check out my poster (number 87) tonight! 😁 Showing our work on common variation associated with aneuploidy in human embryos
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Vikram Shivakumar @vikramshivakumar.bsky.social · 09/05/2025
Excited to share our latest work on comparing and visualizing multiple genome assemblies to identify conservation and structural variation in pangenomes with Mumemto! Check out poster 250 at #bog25 if you are here. New preprint coming very soon 👀
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Igor Martayan @imartayan.bsky.social · 27/04/2025
Next up is Nathaniel Brown from @benlangmead.bsky.social's group presenting col-bwt, a new algorithm for computing chain statistics using multi-maximal unique matches. www.biorxiv.org/content/10.1...
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Nature Methods @natmethods.nature.com · 28/03/2025
Uncalled4: a toolkit for nanopore signal alignment, analysis and visualization of DNA and RNA modifications. www.nature.com/articles/s41...
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Bohan Ni @bohanni.bsky.social · 26/03/2025
Happy to share our work characterizing functional rare SVs in rare diseases with long-read genome sequencing and transcriptomic outlier data: genome.cshlp.org/content/earl...
genome.cshlp.org
Integration of transcriptomics and long-read genomics prioritizes structural variants in rare disease
An international, peer-reviewed genome sciences journal featuring outstanding original research that offers novel insights into the biology of all organisms
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Ben Langmead @benlangmead.bsky.social · 08/03/2025
Scenes from #StandUpForScience2025 in DC today. Huge contingent from Johns Hopkins, and also from UMD & DC/Virginia Unis.
Group at the rally by the Lincoln MemorialGroup at the rally by the Lincoln Memorial, with Bill NyeView along the Reflecting Pool from Lincoln MemorialLincoln Memorial
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Vikram Shivakumar @vikramshivakumar.bsky.social · 26/02/2025
We ran Mumemto on 474 human assemblies from @humanpangenome.bsky.social to find syntenic regions using MUMs. Mumemto scales remarkably well to large pangenomes thanks to compressed-space algos! It took under 2 days across 7 nodes (each using ~500 GB memory).
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Vikram Shivakumar @vikramshivakumar.bsky.social · 06/01/2025
Excited to share a preprint for (w/ @benlangmead.bsky.social) our new tool, Mumemto, on biorxiv! Mumemto finds multi-MUMs across pangenomes (i.e. mummer but for pangenomes). It can rapidly visualize synteny, identify misassemblies, and accelerate core genome and multiple alignment, highlighting SVs.
biorxiv.org
Mumemto: efficient maximal matching across pangenomes
Aligning genomes into common coordinates is central to pangenome analysis and construction, but it is also computationally expensive. Multi-sequence maximal unique matches (multi-MUMs) are guideposts ...
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bioRxiv Bioinfo @biorxiv-bioinfo.bsky.social · 06/01/2025
Mumemto: efficient maximal matching across pangenomes www.biorxiv.org/content/10.1101/202…
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