identifier: traitmech:000683
label: trichocyst discharge
definition: An exocytotic phenotype in which a microbial cell releases trichocyst
  contents to the exterior through fusion of a trichocyst membrane with the plasma
  membrane.
definition_source: DOI:10.1083/jcb.111.6.2527
trait_category: PHYSIOLOGY
term_kind: CLASS
mapping_status: PROPOSED
parent_traits:
- traitmech:000637
evidence:
- reference: DOI:10.1083/jcb.111.6.2527
  snippet: A Paramecium possesses secretory organelles called trichocysts which are
    docked beneath the plasma membrane awaiting an external stimulus that triggers
    their exocytosis.
  notes: PMID:1703537, PMC2116420. Scientific Abstract and relevant Methods/Results
    OCR read directly in Europe PMC fullTextXML. The snippet is from the scientific
    Abstract; figures were not inspected. AED-triggered release was studied in Paramecium
    tetraurelia stock d4-2, a stock 51 derivative, and mutants. Calcium influx and
    concentration requirements concern this assay, not a universal discharge threshold
    or proven channel identity. The Methods distinguish low-calcium membrane injury
    from secretion; calcium influx alone does not demonstrate release.
- reference: DOI:10.1016/s0143-4160(98)90030-6
  snippet: but only wt cells release trichocysts (t).
  notes: PMID:9681197. Primary PDF at https://d-nb.info/1107191386/34, Figures 1-4
    caption, printed page 351. Pages 351-352 were visually inspected, including paired
    fluorescence/transmitted-light panels and Table 1. Wildtype Paramecium caudatum
    releases trichocysts after local AED or caffeine stimulation; tnd1 shows calcium
    transients and membrane fusion without contents release. Most trichocysts remain
    in wildtype cells during the illustrated local response, so total emptying is
    not required. Mutant tnd1 is boundary evidence, not a positive discharge exemplar.
    Reduced calcium binding is a proposed explanation, not a proven protein lesion.
    Natural strain provenance is unresolved.
- reference: DOI:10.1016/0143-4160(93)90065-e
  snippet: trichocyst contents were slowly extruded
  notes: PMID:7684653. Scientific Abstract retrieved directly using an exact quoted
    DOI query in Europe PMC. Abstract-only access; full Methods and figures were not
    inspected. Slow extrusion under AED and low-calcium conditions shows why rapid
    expansion is not mandatory in this definition. The abstract distinguishes fusion,
    contents release and resealing; prolonged calcium removal is followed by cell
    death. Do not infer calcium irrelevance to all stages or treat terminal damage
    as secretion.
discussions:
- discussion_id: trichocyst-discharge-scope-and-assays
  prompt: Keep cargo release distinct from organelle presence and component steps.
  kind: CURATION_TODO
  status: OPEN
  rationale: Exocytosis traitmech:000637 is the broader parent; the proposal depends
    on its v513 placeholder METPO:1059000. Trichocyst formation, docking, fusion without
    cargo release and isolated matrix expansion do not alone establish completed discharge.
    Lysis and preparation artifacts must be excluded from positive assays. Neither
    rapid extrusion, total emptying nor a shared calcium threshold defines this class.
    The existing myzocytosis record's warning about fixation-associated discharge
    and uncertain prey capture is not resolved by these secretion experiments. No
    exact synonyms, xrefs, SSSOM equivalents or universal prey-capture role are asserted.
  posed_by: codex
  posed_date: '2026-10-08'
- discussion_id: trichocyst-discharge-provenance-and-mechanism
  prompt: Resolve natural culture provenance and taxon-specific release mechanisms.
  kind: KNOWLEDGE_GAP
  status: OPEN
  rationale: These experiments support a secretion phenotype in source-named Paramecium
    systems, not every protist bearing an extrusome. Natural culture provenance and
    strain-level taxonomy remain unchecked, so no canonical examples are assigned.
    A wildtype designation alone does not establish natural provenance; a mutant designation
    alone does not establish engineering. Keep assay-specific calcium observations
    separate and obtain direct functional evidence with taxon-paired accessions before
    adding a protein-resolved graph. Mechanism is deferred, not claimed absent; sequence
    features alone do not establish discharge.
  posed_by: codex
  posed_date: '2026-10-08'
curation_history:
- timestamp: '2026-10-08T16:03:03Z'
  curator: codex
  action: MINTED_TRAITMECH_ID
  changes: Added trichocyst discharge with three primary DOI sources and directly
    checked abstract/caption snippets. Ignored-and-hidden main/worktree/open-PR checks
    support 000683 and v559 block 1063600-1063699. Used existing exocytosis parent
    and its v513 proposal dependency. Kept calcium conditions, fusion-only mutants,
    slow extrusion and provenance qualified; deferred protein mechanism. Existing
    records unchanged. Timestamp is observed UTC.
  llm_assisted: true