TraitMech

TraitMech › PHYSIOLOGY

photokinesis

traitmech:000587 · CLASS · PROPOSED

A motile phenotype in which the speed of active locomotion changes in response to illumination intensity, without requiring orientation toward or away from the light source.

Trait evidence (2)

  • DOI:10.1128/AEM.67.12.5410-5419.2001
    swimming velocities are correlated to the illumination intensity.

    Introduction's photokinesis definition; publisher full text at https://journals.asm.org/doi/10.1128/AEM.67.12.5410-5419.2001 and Figure 2A-B with caption inspected. In Marichromatium gracile CE2205, the anoxic 1 mM total-sulfide preparation shows lower speed at low irradiance; oxic controls (>100 micromolar oxygen, no free sulfide) show no significant irradiance dependence. Reported irradiance is visible-region scalar irradiance (400-700 nm), with a fixed visible:near-infrared photon ratio of 1:8.3. Measurements use two-dimensional cell tracks after 60 s at each irradiance. Exponential-phase cells with sulfur globules were sampled above bottom aggregates. The collection-supplied strain is not assigned an independently verified natural lineage here. The separate gradient-migration results are attributed to phobic responses, not used to infer directional photokinesis.

  • DOI:10.1016/S0176-1617(00)80045-0
    Photosynthetically active continuous red light reversibly enhances the swimming velocity and increases or decreases the precision of gravitaxis, depending on its initial level.

    Abstract, PMID:12090268, exact-matched at Europe PMC. This primary study of Chlamydomonas reinhardtii supports light-dependent speed modulation alongside a distinct orientation response. Its blue-light responses have different kinetics; proposed chlamy-rhodopsin participation is explicitly inferential. Subscription full text was not inspected; no strain lineage, protein accession or full-text-only result is inferred.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1128/AEM.67.12.5410-5419.2001

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.

Preserve the speed-response scope when mapping light responses.

CURATION TODO OPEN photokinesis-speed-and-direction-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.

This definition follows the speed usage in the cited experiments. It does not require increasing speed, a photosynthetic energy mechanism, or an isolated response without concurrent taxis. Phototaxis concerns orientation; photophobic responses concern avoidance or reversals. They may coexist with photokinesis, but no equivalence, disjointness or parent-child relation is asserted. The obsolete METPO:1000241 phototaxis class is not an exact match or a replacement target. Reconcile broader kinesis terminology before adding turning-frequency synonyms or external xrefs.

Verify natural exemplars and protein-resolved causal branches.

CURATION TODO OPEN photokinesis-strain-and-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.

Qualified experimental observations are retained without canonical taxa pending independent CE2205 lineage verification or a fully inspected algal strain source. Collection provenance alone does not establish unperturbed natural ancestry. Mechanism discussion in the sources does not establish one universal receptor, and the algal abstract only suggests rhodopsin participation. A mechanistic graph is deferred pending source-backed causal edges and eligible taxon-paired protein examples. Do not borrow the generic motile graph or use NONMECHANISTIC to bypass this gap.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added photokinesis with two primary DOI citations and contiguous snippets. Ignored-and-hidden searches found no exact record or METPO term; nearby obsolete phototaxis is distinct. Reserved METPO:1054100 in proposal v464. Preserved oxygen, spectral and experimental-state qualifiers; deferred natural canonical taxa and protein-level graphs.