identifier: traitmech:000008
label: ionizing radiation tolerant
definition: An environmental tolerance in which an organism survives high doses of
  ionizing radiation (e.g. gamma rays), typically via efficient repair of DNA double-strand
  breaks and protection of the proteome from oxidative damage.
definition_source: DOI:10.3390/genes14091803
trait_category: ENVIRONMENT
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- traitmech:000007
synonyms:
- synonym_text: gamma radiation resistant
  synonym_type: NARROW_SYNONYM
  source: DOI:10.3390/genes14091803
evidence:
- reference: DOI:10.3390/genes14091803
  snippet: Deinococcus radiodurans R1 demonstrates a significantly higher radiation
    resistance with D10 values exceeding 12 kGy for gamma radiation and 700 J/m2 for
    UV-C radiation
  notes: 'Organism example: Deinococcus radiodurans tolerates gamma (ionizing) radiation
    D10 doses exceeding 12 kGy.'
- reference: DOI:10.1101/cshperspect.a012765
  snippet: A strong correlation has been shown between intracellular Mn/Fe concentration
    ratios and bacterial resistance to radiation
  notes: Mechanism support — manganese-mediated oxidative-damage protection underlies
    survival of lethal ionizing-radiation doses.
canonical_examples:
- taxon_id: NCBITaxon:1299
  taxon_label: Deinococcus radiodurans
  note: "extreme ionizing-radiation resistance"
  reference: PMID:10567266
causal_graphs:
- graph_id: ionizing_radiation_tolerance_dsb_repair
  title: Ionizing-radiation tolerance via double-strand-break repair
  description: Evidence-backed causal sketch linking gamma-radiation exposure to efficient
    repair of DNA double-strand breaks and Mn-mediated oxidative protection.
  nodes:
  - node_id: ionizing_tolerant_trait
    label: ionizing radiation tolerant
    node_type: TRAIT
    grounding: traitmech:000008
    description: Survival of high doses of ionizing (gamma) radiation.
  - node_id: gamma_radiation
    label: gamma radiation
    node_type: ENVIRONMENTAL_FACTOR
    description: High-energy ionizing radiation causing DNA double-strand breaks.
  - node_id: dsb_repair
    label: double-strand break repair
    node_type: BIOLOGICAL_PROCESS
    grounding: GO:0006302
    description: Repair of radiation-induced DNA double-strand breaks.
  - node_id: mn_antioxidant_protection
    label: manganese-mediated oxidative-damage protection
    node_type: BIOLOGICAL_PROCESS
    description: Mn(II)-antioxidant shielding of repair proteins from oxidative damage.
  - node_id: dsb_clustered_lesions
    label: DNA double-strand breaks and clustered lesions
    node_type: STATE
    description: Single- and double-strand DNA breaks, abasic sites and complex clustered
      lesions produced by ionizing radiation.
  - node_id: mn_fe_ratio
    label: high intracellular Mn/Fe ratio
    node_type: QUALITY
    description: Elevated intracellular manganese-to-iron concentration ratio associated
      with antioxidant proteome protection.
  edges:
  - subject: gamma_radiation
    predicate: challenges
    object: ionizing_tolerant_trait
    description: Gamma exposure is the environmental challenge the trait counters.
    evidence:
    - reference: DOI:10.3390/genes14091803
      notes: Deinococcus radiodurans tolerates gamma D10 doses exceeding 12 kGy.
    predicate_id: METPO:2007406
  - subject: dsb_repair
    predicate: enables
    object: ionizing_tolerant_trait
    description: Efficient DSB repair restores chromosomal integrity after ionizing-radiation
      damage.
    evidence:
    - reference: DOI:10.3390/genes14091803
      notes: D. radiodurans tolerates lethal gamma doses through DSB-repair machinery.
    predicate_id: RO:0002327
  - subject: mn_antioxidant_protection
    predicate: enables
    object: ionizing_tolerant_trait
    description: Mn-antioxidant proteome protection preserves repair capacity under
      irradiation.
    evidence:
    - reference: DOI:10.1101/cshperspect.a012765
      notes: Intracellular Mn/Fe ratio correlates with bacterial radiation resistance.
    predicate_id: RO:0002327
  - subject: gamma_radiation
    predicate: causes
    object: dsb_clustered_lesions
    description: Ionizing radiation produces DNA double- and single-strand breaks
      and complex clustered lesions.
    evidence:
    - reference: DOI:10.1007/978-3-031-18810-7_9
      notes: Ionizing radiation produces single- and double-strand DNA breaks, abasic
        sites and complex clustered lesions (broad radiobiology, across taxa).
    predicate_id: biolink:causes
  - subject: dsb_repair
    predicate: repairs
    object: dsb_clustered_lesions
    description: Double-strand break repair resolves the clustered DNA lesions inflicted
      by ionizing radiation.
    evidence:
    - reference: DOI:10.1007/978-3-031-18810-7_9
      notes: DSB-repair machinery resolves radiation-induced strand breaks and clustered
        lesions to restore chromosomal integrity.
  - subject: mn_fe_ratio
    predicate: positively correlates with
    object: ionizing_tolerant_trait
    description: A high intracellular Mn/Fe ratio correlates with antioxidant proteome
      protection and survival of ionizing radiation.
    evidence:
    - reference: DOI:10.1101/cshperspect.a012765
      notes: 'Strong correlation: radiation-resistant bacteria carry more Mn2+ and
        ~3x less Fe2+, giving antioxidant protection of the cellular proteome.'
  - subject: mn_fe_ratio
    predicate: enables
    object: mn_antioxidant_protection
    description: A high Mn/Fe ratio supplies the Mn(II) complexes that shield repair
      proteins from oxidative damage.
    evidence:
    - reference: DOI:10.1101/cshperspect.a012765
      notes: Elevated Mn/Fe ratio underlies Mn-antioxidant protection of the proteome
        during irradiation.
    predicate_id: RO:0002327
curation_history:
- timestamp: '2026-05-28T00:00:00Z'
  curator: claude
  action: PROPOSED_FROM_RESEARCH
  changes: Proposed candidate ENVIRONMENT trait (ionizing/gamma radiation tolerance)
    from literature research; sub-variant of radiotolerant.
  llm_assisted: true
- timestamp: '2026-06-09T14:00:00Z'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added evidence-backed causal graph (DSB repair + Mn-antioxidant) with GO
    node grounding and RO/METPO predicate groundings; promoted PROPOSED to REVIEWED.
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 4 evidence-backed generic edges (2 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:10Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:causes×1, RO:0002327×1).
  llm_assisted: true