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Documents authored by Qi, Yuanyuan


Document
Sapling: Inferring and Summarizing Tumor Phylogenies from Bulk Data Using Backbone Trees

Authors: Yuanyuan Qi and Mohammed El-Kebir

Published in: LIPIcs, Volume 312, 24th International Workshop on Algorithms in Bioinformatics (WABI 2024)


Abstract
Cancer phylogenies are key to understanding tumor evolution. There exist many important downstream analyses that take as input a single or a small number of trees. However, due to uncertainty, one typically infers many, equally-plausible phylogenies from bulk DNA sequencing data of tumors. We introduce Sapling, a heuristic method to solve the Backbone Tree Inference from Reads problem, which seeks a small set of backbone trees on a smaller subset of mutations that collectively summarize the entire solution space. Sapling also includes a greedy algorithm to solve the Backbone Tree Expansion from Reads problem, which aims to expand an inferred backbone tree into a full tree. We prove that both problems are NP-hard. On simulated and real data, we demonstrate that Sapling is capable of inferring high-quality backbone trees that adequately summarize the solution space and that can be expanded into full trees.

Cite as

Yuanyuan Qi and Mohammed El-Kebir. Sapling: Inferring and Summarizing Tumor Phylogenies from Bulk Data Using Backbone Trees. In 24th International Workshop on Algorithms in Bioinformatics (WABI 2024). Leibniz International Proceedings in Informatics (LIPIcs), Volume 312, pp. 7:1-7:19, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2024)


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@InProceedings{qi_et_al:LIPIcs.WABI.2024.7,
  author =	{Qi, Yuanyuan and El-Kebir, Mohammed},
  title =	{{Sapling: Inferring and Summarizing Tumor Phylogenies from Bulk Data Using Backbone Trees}},
  booktitle =	{24th International Workshop on Algorithms in Bioinformatics (WABI 2024)},
  pages =	{7:1--7:19},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-340-9},
  ISSN =	{1868-8969},
  year =	{2024},
  volume =	{312},
  editor =	{Pissis, Solon P. and Sung, Wing-Kin},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WABI.2024.7},
  URN =		{urn:nbn:de:0030-drops-206518},
  doi =		{10.4230/LIPIcs.WABI.2024.7},
  annote =	{Keywords: Cancer, intra-tumor heterogeneity, consensus, maximum agreement}
}
Document
Balancing Minimum Free Energy and Codon Adaptation Index for Pareto Optimal RNA Design

Authors: Xinyu Gu, Yuanyuan Qi, and Mohammed El-Kebir

Published in: LIPIcs, Volume 273, 23rd International Workshop on Algorithms in Bioinformatics (WABI 2023)


Abstract
The problem of designing an RNA sequence v that encodes for a given target protein w plays an important role in messenger RNA (mRNA) vaccine design. Due to codon degeneracy, there exist exponentially many RNA sequences for a single target protein. These candidate RNA sequences may adopt different secondary structure conformations with varying minimum free energy (MFE), affecting their thermodynamic stability and consequently mRNA half-life. In addition, species-specific codon usage bias, as measured by the codon adaptation index (CAI), also plays an essential role in translation efficiency. While previous works have focused on optimizing either MFE or CAI, more recent works have shown the merits of optimizing both objectives. Importantly, there is a trade-off between MFE and CAI, i.e. optimizing one objective is at the expense of the other. Here, we formulate the Pareto Optimal RNA Design problem, seeking the set of Pareto optimal solutions for which no other solution exists that is better in terms of both MFE and CAI. We introduce DERNA (DEsign RNA), which uses the weighted sum method to enumerate the Pareto front by optimizing convex combinations of both objectives. DERNA uses dynamic programming to solve each convex combination in O(|w|³) time and O(|w|²) space. Compared to a previous approach that only optimizes MFE, we show on a benchmark dataset that DERNA obtains solutions with identical MFE but superior CAI. Additionally, we show that DERNA matches the performance in terms of solution quality of LinearDesign, a recent approach that similarly seeks to balance MFE and CAI. Finally, we demonstrate our method’s potential for mRNA vaccine design using SARS-CoV-2 spike as the target protein.

Cite as

Xinyu Gu, Yuanyuan Qi, and Mohammed El-Kebir. Balancing Minimum Free Energy and Codon Adaptation Index for Pareto Optimal RNA Design. In 23rd International Workshop on Algorithms in Bioinformatics (WABI 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 273, pp. 21:1-21:20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{gu_et_al:LIPIcs.WABI.2023.21,
  author =	{Gu, Xinyu and Qi, Yuanyuan and El-Kebir, Mohammed},
  title =	{{Balancing Minimum Free Energy and Codon Adaptation Index for Pareto Optimal RNA Design}},
  booktitle =	{23rd International Workshop on Algorithms in Bioinformatics (WABI 2023)},
  pages =	{21:1--21:20},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-294-5},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{273},
  editor =	{Belazzougui, Djamal and Ouangraoua, A\"{i}da},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.WABI.2023.21},
  URN =		{urn:nbn:de:0030-drops-186479},
  doi =		{10.4230/LIPIcs.WABI.2023.21},
  annote =	{Keywords: Multi-objective optimization, dynamic programming, RNA sequence design, reverse translation, mRNA vaccine design}
}
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