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trichocyst discharge

traitmech:000683 · CLASS · PROPOSED

An exocytotic phenotype in which a microbial cell releases trichocyst contents to the exterior through fusion of a trichocyst membrane with the plasma membrane.

Trait evidence (3)

  • DOI:10.1083/jcb.111.6.2527
    A Paramecium possesses secretory organelles called trichocysts which are docked beneath the plasma membrane awaiting an external stimulus that triggers their exocytosis.

    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.

  • DOI:10.1016/s0143-4160(98)90030-6
    but only wt cells release trichocysts (t).

    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.

  • DOI:10.1016/0143-4160(93)90065-e
    trichocyst contents were slowly extruded

    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.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1083/jcb.111.6.2527

Parent traits (1)

kg-microbe context

No kg-microbe node embedding matched this record in the 2026-04-25 deepwalk.

Discussions and Knowledge Gaps (2)

Open questions attached to this trait. Seeded by just knowledge-gap-scan and curated; see the corpus-wide index.

Keep cargo release distinct from organelle presence and component steps.

CURATION TODO OPEN trichocyst-discharge-scope-and-assays · raised by codex · 2026-10-08

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

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.

Resolve natural culture provenance and taxon-specific release mechanisms.

KNOWLEDGE GAP OPEN trichocyst-discharge-provenance-and-mechanism · raised by codex · 2026-10-08

Not yet attached to a section of this record — a curator sets attaches_to (e.g. causal_graphs#some_edge) so the gap shows beside the mechanism it concerns.

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.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    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.

Recorded curation sessions

  • · codex
    • CREATE — Add evidence-backed trichocyst discharge

      Added traitmech:000683 with three primary DOI sources, directly read scientific-abstract and visually checked caption snippets, exocytosis parent, and v559 proposal depending on v513. Distinguished contents release from fusion alone; retained slow-extrusion, calcium, provenance and mechanism limits. No existing records changed.

    Read this curation session