gyrotaxis

traitmech:000583 · CLASS · PROPOSED

A motile phenotype in which the balance of gravitational and viscous torques biases an organism's swimming orientation.

Trait evidence (2)

DOI:10.1073/pnas.2206738119
The orientational response to the gravity-viscous torque balance is known as gyrotaxis

Introduction, page 1; definition checked against the publisher-formatted article deposited by the authors at https://api.repository.cam.ac.uk/server/api/core/bitstreams/ac9ccafe-f229-477c-9d59-b7a56cd506a0/content (PMID:36219692; PMC9586295). The second of the introduction's three accumulation mechanisms starts 'The second is response to an external field': it describes swimming in still water and gravitational restoration resisted hydrodynamically, then names this response gyrotaxis. This record follows Zeng's broader usage, not a universal requirement or exclusion of imposed shear. Results, Figures 5-7, and Materials and Methods distinguish gravitational reorientation from wall-contact effects in Heterosigma akashiwo GY-H24. Shape asymmetry and density asymmetry are alternatives; bottom-heaviness is not universal. The full main article was read; supplementary material and movies were not inspected. No gravity-sensing receptor is asserted.
DOI:10.1126/science.1167334
The swimming direction, θ, is then set by the balance of viscous and gravitactic torques

Page 1068, left column beneath Figure 2; the typeset theta in the torque-balance sentence was visually checked because PDF extraction substitutes q. This passage concerns imposed shear. Live-cell experiments are on pages 1067-1069 of the full main article at https://stockerlab.ethz.ch/wp-content/uploads/2013/01/17.-DurhamKesslerStocker_Science2009.pdf (PMID:19229037). Chlamydomonas nivalis and Heterosigma akashiwo formed layers in a depth-varying shear chamber; dead cells did not. Gyrotactic trapping is a population consequence under suitable shear, not the definition of the organismal trait or the cause of every oceanic thin layer. Ocean-scale results are model predictions. The supplement and exact culture identities were not verified; no strain or modern C. nivalis taxon identity is inferred.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1073/pnas.2206738119

Parent traits (1)

motile METPO:1000702

kg-microbe context

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

Canonical examples (1)

Organisms cited as exemplars of this trait. Taxon ids are NCBITaxon and link out to the NCBI record.

Heterosigma akashiwo NCBITaxon:2829 DOI:10.1073/pnas.2206738119 GY-H24 culture, examined 3-9 hours into the light phase of a 12-hour light/12-hour dark cycle. Figures 5-7 show gravitational reorientation and wall-modified swimming in a sealed, still-fluid microchannel; upward bias is not asserted for every cell or diurnal phase. This example follows Zeng's explicit still-water usage of gyrotaxis; it is not an imposed-shear experiment. The NCBI identifier is species-level, not a resolved GY-H24 strain accession.

Discussions and Knowledge Gaps (1)

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

Represent physical torque-mediated orientation without inventing a protein sensor.

CURATION TODO OPEN gyrotaxis-physical-mechanism-representation · raised by codex · 2026-10-04

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.

The primary papers describe a physical mechanism, so the absence of a protein accession is not absence of mechanistic evidence. This identity/evidence pass omits a graph: the current MECHANISTIC coverage audit requires a protein node and protein example, whereas NONMECHANISTIC is reserved for measurement or classification contexts. Resolve a faithful representation separately instead of relabeling the physical mechanism or inventing a sensor. Keep gravity-viscous orientation distinct from wall-contact responses and high-shear trapping. Gyrotaxis is not an exact synonym of gravitaxis, rheotaxis, bioconvection or thin-layer formation. QuickGO returned no gyrotaxis term on 2026-10-04; no exact external xref is asserted.

Curation history

2026-10-04T01:16:29Z · MINTED_TRAITMECH_ID · codex
Added gyrotaxis with two primary DOI sources, contiguous evidence snippets and a light-phase-qualified GY-H24 example at verified species taxon NCBITaxon:2829. Ignored-and-hidden novelty searches found no exact record or METPO class. Reserved METPO:1053700 in proposal v460. Recorded the physical-graph representation gap without asserting an unsupported protein or receptor.
2026-10-04T01:41:15Z · ADDRESS_REVIEW_FINDINGS · codex
Addressed PR 1646 issues 1647 and 1648: replaced the Durham population outcome snippet with its typeset torque-balance statement; anchored Zeng's broader still-water usage to the specific introduction passage and qualified the canonical example. Definition and hierarchy unchanged.