NLM DIR Seminar Schedule
UPCOMING SEMINARS
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April 1, 2025 Roman Kogay
Horizontal transfer of bacterial operons into eukaryote genomes -
April 8, 2025 Jaya Srivastava
TBD -
April 15, 2025 Pascal Mutz
TBD -
April 18, 2025 Valentina Boeva, Department of Computer Science, ETH Zurich
Decoding tumor heterogeneity: computational methods for scRNA-seq and spatial omics -
April 22, 2025 Stanley Liang
TBD
RECENT SEMINARS
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March 25, 2025 Yifan Yang
Adversarial Manipulation and Data Memorization in Large Language Models for Medicine -
March 11, 2025 Sofya Garushyants
Tmn – bacterial anti-phage defense system -
March 4, 2025 Sanasar Babajanyan
Evolution of antivirus defense in prokaryotes depending on the environmental virus load -
Feb. 25, 2025 Zhizheng Wang
GeneAgent: Self-verification Language Agent for Gene Set Analysis using Domain Databases -
Feb. 18, 2025 Samuel Lee
Efficient predictions of alternative protein conformations by AlphaFold2-based sequence association
Scheduled Seminars on March 4, 2025
In-person: Building 38A/B2N14 NCBI Library or Meeting Link
Contact NLMDIRSeminarScheduling@mail.nih.gov with questions about this seminar.
Abstract:
Prokaryotes can acquire antivirus immunity via two fundamentally distinct types of processes: direct interaction with the virus as in CRISPR-Cas adaptive immunity systems and horizontal transfer of defense genes which is the main route of transmission of innate immunity systems. These routes of defense evolution are not mutually exclusive and may operate simultaneously, but empirical observations suggest that at least in some bacterial and archaeal species, one or the other dominates the defense landscape. We hypothesized that the observed dichotomy is due to the different life-history tradeoffs characteristic of these organisms. To test this hypothesis, we analyzed a mathematical model of a well-mixed population of prokaryotes under a stochastically changing viral load. Optimization of the long-term growth rate of the population reveals two contrasting modes of defense evolution. In a stable, predictable and fluctuating, unpredictable environments with a moderate viral load, adaptive immunity and horizontal transfer of defense genes become the optimal routes of immunity acquisition, respectively. In the HGT-dominant mode, we observe a universal distribution of the fraction of microbes possessing different immune repertoires. Under very low virus load, the cost of immunity exceeds its benefits such that the optimal state of a prokaryote is carrying no defense systems at all. By contrast, under very high virus load, horizontal spread of defense systems dominates regardless of the stability of the environments. These findings seem to explain some consistently observed but enigmatic patterns in the spread of antivirus defense systems among prokaryotes such as the ubiquity of adaptive immunity in hyperthermophiles contrasting their patchy distribution among mesophiles.