TraitMech

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viscotaxis

traitmech:000593 · CLASS · PROPOSED

A motile phenotype in which active locomotion produces net migration in response to a spatial gradient in surrounding fluid viscosity.

Trait evidence (3)

  • DOI:10.1099/00221287-109-1-113
    We have designated this positive response to a viscosity gradient as 'viscotaxis'.

    Abstract, exact-matched at Europe PMC (PMID:731206); full text not inspected. The antecedent is preferential migration into the more viscous region by the paper's historically named Leptospira interrogans (biflexa) strain B16. This supports positive viscotaxis under the reported conditions, not a universal direction of response. The historical name has not been reconciled to a modern species or strain taxon; no modern Leptospira identity or pathogenicity is inferred.

  • DOI:10.1038/s41598-020-79887-7
    they concentrate in the region of low viscosity or maintain a uniform concentration profile, depending on the viscosity ratio between the two regions.

    Abstract, exact-matched at Europe PMC (PMID:33432106). PMC7801662 full text, Fig. 5 and supplement Figs. S1-S3 were inspected. Wild-type Chlamydomonas reinhardtii showed net redistribution toward lower viscosity in some tested conditions but not others. Short-flagella results are not substituted for the wild type. Measurements followed pump stoppage; optical filtering limited phototactic bias. Interface reorientation, speed and angular diffusion jointly affect transport; a uniform profile is not positive evidence of net migration. The confined sharp-interface experiment does not directly validate an unconfined slowly varying gradient model. Strain accession provenance remains unresolved.

  • DOI:10.1103/physrevlett.120.208002
    suitable body shapes create viscotaxis based on a systematic asymmetry of viscous forces acting on a microswimmer.

    Abstract, exact-matched at Europe PMC (PMID:29864289); full text not inspected. This is a theoretical framework for self-propelled swimmers in slowly varying viscosity fields, not a new biological migration assay or receptor discovery. It supports a possible hydrodynamic contribution without requiring a universal sensory pathway. Suggested functions of microbial body-shape changes are not treated as experimentally established molecular mechanisms.

Provenance

Identifier source
TraitMech local identifier
Definition source
DOI:10.1099/00221287-109-1-113

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.

Retain directional and environmental scope of viscosity-driven migration.

CURATION TODO OPEN viscotaxis-direction-and-physical-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.

The class permits migration toward higher or lower fluid viscosity; neither direction nor a preferred viscosity is universal. Uniform-viscosity speed changes, passive advection and differential growth alone do not establish this trait. Keep fluid-viscosity gradients distinct from flow-directed rheotaxis, osmotic gradients, chemical cues and substrate stiffness or loss-modulus gradients. Coupled cues require controls rather than assumed equivalence. Hydrodynamic turning can bias an actively swimming organism without requiring a receptor. External equivalents and lexical variants remain unasserted pending authority and scope checks.

Resolve natural strain identities and distinguish models from mechanisms.

CURATION TODO OPEN viscotaxis-canonical-provenance-and-mechanisms · 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.

Reconcile the historical Leptospira B16 designation with current taxonomy before adding a canonical example; do not infer modern L. interrogans membership from the article title. The algae study distinguishes wild-type and short-flagella cells, but strain accessions and natural provenance have not been established in this curation. Keep their observations separate and resolve NCBI identity before adding examples. Inspect remaining full texts and separate proposed shape-dependent hydrodynamics from measured reorientation or redistribution. No universal receptor or protein-resolved causal pathway follows from these sources; taxon-paired accessions and direct evidence are needed before adding molecular edges. A NONMECHANISTIC graph must not bypass those requirements.

Curation history

  1. · MINTED_TRAITMECH_ID · codex

    Added viscotaxis with three primary DOI citations and exact abstract snippets. Ignored-and-hidden novelty searches and structured OWL review found no exact record or METPO term. Reserved METPO:1054700 in v470. Inspected the algae full text and supplementary figures to separate conditional spatial redistribution from speed changes and model interpretations. Kept positive and negative response scope, deferred historical strain taxonomy, canonical examples, external equivalents and protein-resolved mechanisms.