gravitaxis

traitmech:000584 · CLASS · PROPOSED

A motile phenotype in which the direction of active swimming is biased relative to gravity.

Trait evidence (2)

DOI:10.1038/s41598-018-26046-8
Predominantly, E. gracilis shows a negative gravitaxis behavior.

Introduction, page 1, visually verified at https://d-nb.info/1186379677/34 (PMID:29765103; PMC5954063). Direction varies with culture age. Results, Figure 4 and Supplementary Figure 6e-g distinguish upward-biased controls from EgPCDUF4201/CaM2 knockdowns. Full main text and supplement 41598_2018_26046_MOESM1_ESM.pdf inspected via Europe PMC. Supplementary Figure 5e, not the main text's 5c, measures flagellar length; Supplementary Table 1 reports comparable, not identical, speeds. These controls do not exclude every flagellar defect. PKA phosphorylation and a direct dynein link remain hypotheses.
DOI:10.1242/jeb.050666
the ability to swim preferentially upwards (negative gravitaxis) is primarily the result of upwardly curving trajectories

Summary (PMID:21112996); publisher main-text Methods, Results and Discussion inspected. Curved trajectories agree with a physical shape-orientation model, but shape and orientation rate were not measured simultaneously in the same individual. This is not proof that all protists lack gravity receptors. Gravikinesis concerns orientation-dependent swimming speed, not the directional phenotype. Equation images and supplementary material were not inspected; no equation-derived or supplement-only claim is asserted.

Provenance

Identifier source: TraitMech local identifier
Definition source: DOI:10.1038/s41598-018-26046-8

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 (2)

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

Euglena gracilis NCBITaxon:3039 DOI:10.1038/s41598-018-26046-8 Strain Z, axenic organic-medium cultures at 20 C under continuous light. Figure 4a and Supplementary Figure 6e show upward-biased wild-type controls; Methods specify buffer-only electroporation. These are not the RNAi knockdowns. NCBI identifier is species-level, not a strain accession; no universal age-independent direction is implied.
Paramecium caudatum NCBITaxon:5885 DOI:10.1242/jeb.050666 Wild-type cells from one-week-old boiled-hay-infusion cultures. After several hours in the observation chamber, rotation of the chamber revealed upward-curving swimming tracks (Results, Figure 2). NCBI identifier is species-level; the paper does not supply a resolved strain accession.

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 gravity-relative swimming distinct from settling and neighboring traits.

CURATION TODO OPEN gravitaxis-direction-and-process-boundaries · 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.

Positive and negative gravitaxis are directional cases, not a requirement that all cells always swim upward. Passive settling alone and speed changes alone do not establish this trait. The definition does not require an active gravity receptor: powered swimming and physical orientation can coexist. Gyrotaxis (traitmech:000583) specifies a gravity-viscous torque mechanism, not an exact synonym or a disjoint phenotype. No new subsumption axiom between them is asserted without reviewing both scopes. QuickGO resolved active GO:0042332 gravitaxis on 2026-10-04, including geotaxis as an exact lexical synonym. It denotes a biological process rather than this organismal disposition; keep it out of equivalent xrefs and resolve any mapping separately.

Resolve exact protein anchors and a faithful physical-mechanism graph.

CURATION TODO OPEN gravitaxis-mechanism-grounding · 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 sources provide mechanism evidence, but this first record does not yet include a graph. Nasir's CaM2 accession EU935858 resolves to UniProtKB:B5THA2, an unreviewed entry without a Proteomes cross-reference in the 2026-10-04 REST response. An exact EgPCDUF4201 name query returned no hit; this does not establish sequence absence. Resolve eligible exact examples before adding the molecular branch; a DUF4201 match alone does not demonstrate gravitaxis. For the physical branch, the current MECHANISTIC coverage audit requires a protein node and example. Do not invent a receptor or misclassify physical causation as NONMECHANISTIC to satisfy that audit.

Curation history

2026-10-04T02:18:15Z · MINTED_TRAITMECH_ID · codex
Added gravitaxis with two primary DOI sources, contiguous snippets and source-qualified examples at verified species taxa 3039 and 5885. Ignored-and-hidden searches found only gyrotaxis boundary mentions, not an exact record or METPO term. Reserved METPO:1053800 in proposal v461; documented process-grain and mechanism-grounding gaps without substituting a protein or asserting a universal receptor.