identifier: METPO:1000484 label: temperature delta low definition: A temperature delta phenotype with a growth-supporting temperature breadth of approximately 5–10 °C, characteristic of organisms with limited thermal-tolerance breadth. definition_source: DOI:10.1146/annurev-micro-091313-103612 trait_category: ENVIRONMENT term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000303 synonyms: - synonym_text: Td_5_10 synonym_type: RELATED_SYNONYM source: metpo.owl evidence: - reference: DOI:10.1146/annurev-micro-091313-103612 snippet: more unsaturated fatty acids notes: Membrane-adaptation review supports limited thermal-adaptation flexibility as the basis of narrow thermal-tolerance breadths. causal_graphs: - graph_id: temperature_delta_low_limited_breadth title: Temperature-delta-low limited-breadth thermal adaptation description: DOI-backed graph linking limited thermal-adaptation flexibility to a 5–10 °C temperature growth breadth. nodes: - node_id: temperature_delta_low_trait label: temperature delta low node_type: TRAIT grounding: METPO:1000484 description: Temperature growth-supporting breadth approximately 5–10 °C. - node_id: temperature_delta label: temperature delta node_type: TRAIT grounding: METPO:1000303 description: Breadth of the growth-supporting ambient-temperature range. - node_id: limited_thermal_adaptation label: limited thermal-adaptation flexibility node_type: BIOLOGICAL_PROCESS description: Modest capacity to remodel membrane lipids and enzymes across small temperature shifts. - node_id: temperature_decrease label: temperature decrease node_type: ENVIRONMENTAL_FACTOR description: A drop in ambient growth temperature (cooling). - node_id: membrane_rigidification label: membrane rigidification/thickening node_type: BIOLOGICAL_PROCESS description: Reduced bilayer fluidity and increased thickness on cooling, with liquid-crystalline-to-gel transition. - node_id: unsaturated_fatty_acids label: membrane unsaturated fatty acids node_type: CHEMICAL description: Unsaturated fatty acids incorporated into membrane lipids that lower the bilayer melting point. - node_id: homeoviscous_adaptation label: homeoviscous adaptation / restored fluidity node_type: BIOLOGICAL_PROCESS description: Lipid remodeling that maintains membrane fluidity across temperature, restoring bilayer fluidity. - node_id: anteiso_bcfa_shift label: iso-to-anteiso branched-chain fatty acid shift node_type: BIOLOGICAL_PROCESS description: Long-term membrane fluidization via iso-to-anteiso branched-chain fatty acid switching. edges: - subject: limited_thermal_adaptation predicate: produces object: temperature_delta_low_trait description: Limited thermal-adaptation flexibility yields a 5–10 °C temperature-delta breadth. evidence: - reference: DOI:10.1146/annurev-micro-091313-103612 snippet: more unsaturated fatty acids notes: Supports limited thermal-adaptation flexibility as the basis of narrow breadth. predicate_id: METPO:2000202 - subject: temperature_delta_low_trait predicate: is a object: temperature_delta description: Temperature delta low is a quantitative bin of the temperature-delta phenotype. evidence: - reference: DOI:10.1016/s0300-9629(97)00003-0 snippet: adapted to environments of high temperature notes: Supports the 5–10 °C breadth as a value within the temperature-delta distribution. predicate_id: rdfs:subClassOf - subject: temperature_decrease predicate: causes object: membrane_rigidification description: Cooling reduces bilayer fluidity, inducing membrane rigidification and thickening. evidence: - reference: DOI:10.1128/spectrum.03925-23 notes: Decreasing temperature induces membrane rigidification and thickening, producing a liquid-crystalline-to-gel phase transition. predicate_id: biolink:causes - subject: unsaturated_fatty_acids predicate: contributes to object: homeoviscous_adaptation description: Increased membrane unsaturated fatty acids counter low-temperature rigidification and restore bilayer fluidity. evidence: - reference: DOI:10.1146/annurev-micro-091313-103612 notes: Bacteria perform homoviscous adaptation by increasing membrane unsaturated fatty acids as growth temperature decreases, thereby restoring bilayer fluidity. predicate_id: RO:0002326 - subject: homeoviscous_adaptation predicate: counteracts object: membrane_rigidification description: Homeoviscous adaptation restores fluidity, opposing cold-induced membrane rigidification. evidence: - reference: DOI:10.1146/annurev-micro-091313-103612 notes: Homeoviscous adaptation restores bilayer fluidity against rigidification as growth temperature decreases. - subject: temperature_decrease predicate: shifts object: anteiso_bcfa_shift description: Low-temperature acclimation drives iso-to-anteiso branched-chain fatty acid switching for membrane fluidization. evidence: - reference: DOI:10.1007/s42770-023-01057-4 notes: Predominant long-term adaptation to low temperatures occurs via fluidization of the membrane by chain branching, specifically iso-to-anteiso SFA switching. - subject: anteiso_bcfa_shift predicate: contributes to object: homeoviscous_adaptation description: Branched-chain fatty acid remodeling fluidizes the membrane, supporting homeoviscous adaptation. evidence: - reference: DOI:10.1007/s42770-023-01057-4 notes: Long-term low-temperature adaptation fluidizes the membrane via introduction of chain branching, a homeoviscous mechanism. predicate_id: RO:0002326 - subject: limited_thermal_adaptation predicate: limits object: homeoviscous_adaptation description: Impaired acyl-chain remodeling capacity constrains homeoviscous adaptation flexibility, narrowing thermal breadth. evidence: - reference: DOI:10.1101/2023.11.10.566608 notes: 'Impaired homeoviscous adaptation: unable to regulate the acyl chain profile to the same extent in response to temperature fluctuations.' predicate_id: RO:0002212 curation_history: - timestamp: '2026-05-05T01:35:46.843770+00:00' curator: seed_from_metpo action: SEEDED_FROM_METPO changes: imported from data/raw/metpo.owl (CLASS) llm_assisted: false - timestamp: '2026-05-13T11:00:00-07:00' curator: claude action: CURATED_CAUSAL_GRAPH changes: Added DOI-backed definition and causal graph linking limited thermal-adaptation flexibility to the narrow-breadth temperature-delta-low bin. llm_assisted: true - timestamp: '2026-05-20T03:35:30Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 2 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (METPO:2000202×1, rdfs:subClassOf×1). llm_assisted: true - timestamp: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 6 evidence-backed generic edges (5 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:11Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002326×2, biolink:causes×1, RO:0002212×1). llm_assisted: true