identifier: METPO:1000883
label: cell length very small
definition: A cell-length phenotype in which the longer cell dimension is at most
  approximately 1.3 micrometers.
definition_source: DOI:10.1038/ismej.2014.60
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000881
synonyms:
- synonym_text: L_<=1.3
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
evidence:
- reference: DOI:10.1038/ismej.2014.60
  snippet: small cells and genomes
  notes: Streamlining review links very small cell sizes to oligotrophic lifestyle
    and reduced cellular material requirements.
causal_graphs:
- graph_id: cell_length_very_small_streamlining
  title: Very-small cell-length streamlining
  description: DOI-backed graph linking strong nutrient limitation and streamlining
    selection to very-small cell length (≤1.3 μm).
  nodes:
  - node_id: cell_length_very_small_trait
    label: cell length very small
    node_type: TRAIT
    grounding: METPO:1000883
    description: Cell length at most ~1.3 μm.
  - node_id: cell_length_trait
    label: cell length
    node_type: TRAIT
    grounding: METPO:1000881
    description: Longer cellular dimension under shared size regulation.
  - node_id: streamlining_selection
    label: streamlining selection
    node_type: BIOLOGICAL_PROCESS
    description: Selection for reduced cellular and genomic material under chronic
      nutrient limitation.
  - node_id: oligotrophic_environment
    label: oligotrophic environment
    node_type: ENVIRONMENTAL_FACTOR
    description: Persistent low-nutrient setting that favors miniaturized cells.
  - node_id: genome_streamlining
    label: genome streamlining
    node_type: BIOLOGICAL_PROCESS
    description: Adaptive reduction of genome size and cellular material, characterized
      by small cells (~1 um) and small genomes.
  - node_id: carbon_limitation
    label: carbon limitation
    node_type: ENVIRONMENTAL_FACTOR
    description: Low carbon availability, an ecological driver associated with streamlining.
  - node_id: nitrogen_limitation
    label: nitrogen limitation
    node_type: ENVIRONMENTAL_FACTOR
    description: Low nitrogen availability, an ecological driver associated with streamlining.
  - node_id: reduced_transcriptional_regulation
    label: reduced transcriptional regulation
    node_type: BIOLOGICAL_PROCESS
    description: Reduction of transcriptional regulatory machinery in oligotrophic
      microorganisms.
  - node_id: nutrient_poor_environment
    label: nutrient-poor environment
    node_type: ENVIRONMENTAL_FACTOR
    description: Environment with low nutrient availability favoring low-regulation,
      streamlined strategies.
  edges:
  - subject: oligotrophic_environment
    predicate: regulates
    object: streamlining_selection
    description: Persistent oligotrophy selects for streamlined cells and genomes.
    evidence:
    - reference: DOI:10.1038/ismej.2014.60
      snippet: small cells and genomes
      notes: Supports oligotrophic regimes as drivers of cell miniaturization.
    predicate_id: RO:0002211
  - subject: streamlining_selection
    predicate: produces
    object: cell_length_very_small_trait
    description: Streamlining selection produces very small cell length values.
    evidence:
    - reference: DOI:10.1038/ismej.2014.60
      snippet: small cells
      notes: Supports very small length as an outcome of streamlining selection.
    predicate_id: METPO:2000202
  - subject: cell_length_very_small_trait
    predicate: is a
    object: cell_length_trait
    description: Very small cell length is a quantitative bin of the cell-length phenotype.
    evidence:
    - reference: DOI:10.1016/j.cub.2014.07.022
      snippet: cell size is tightly controlled
      notes: Supports very small cell length as a value within the regulated cell-length
        distribution.
    predicate_id: rdfs:subClassOf
  - subject: oligotrophic_environment
    predicate: selects for
    object: genome_streamlining
    description: Oligotrophic environments select for genome streamlining.
    evidence:
    - reference: DOI:10.1128/mSphereDirect.00011-19
      notes: Genome streamlining is characterized by small cells (~1 um), small genomes
        (~1-2 Mbp), and is strongly associated with carbon and nitrogen limitation.
    predicate_id: METPO:2007401
  - subject: carbon_limitation
    predicate: associated with
    object: genome_streamlining
    description: Carbon limitation is associated with genome streamlining.
    evidence:
    - reference: DOI:10.1128/mSphereDirect.00011-19
      notes: Streamlining is strongly associated with carbon and nitrogen limitation.
    predicate_id: biolink:associated_with
  - subject: nitrogen_limitation
    predicate: associated with
    object: genome_streamlining
    description: Nitrogen limitation is associated with genome streamlining.
    evidence:
    - reference: DOI:10.1128/mSphereDirect.00011-19
      notes: Streamlining is strongly associated with carbon and nitrogen limitation.
    predicate_id: biolink:associated_with
  - subject: genome_streamlining
    predicate: contributes to
    object: cell_length_very_small_trait
    description: Genome streamlining contributes to very small cell size.
    evidence:
    - reference: DOI:10.1038/s41467-024-48591-9
      notes: Prominent oligotrophic taxa (SAR11, Prochlorococcus) have streamlined
        genomes (~1.5 Mb) and extremely small cell volumes (~0.1 um3).
    predicate_id: RO:0002326
  - subject: reduced_transcriptional_regulation
    predicate: enhances fitness in
    object: nutrient_poor_environment
    description: Reduced transcriptional regulation enhances fitness in nutrient-poor
      environments, a companion of streamlining.
    evidence:
    - reference: DOI:10.1128/MMBR.00124-22
      notes: A reduction of transcriptional regulation in aquatic oligotrophic microorganisms
        enhances fitness in nutrient-poor environments.
curation_history:
- timestamp: '2026-05-05T01:35:46.919417+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-11T22:30:00-07:00'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added DOI-backed causal graph linking oligotrophic streamlining selection
    to very small cell length.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:31Z'
  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: '2026-05-24T04:13:19Z'
  curator: claude
  action: RENAME_PREDICATE_LABELS
  changes: 'Renamed 1 causal-edge predicate label(s) to align with existing groundings:
    drives → regulates ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:21Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002211×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 5 evidence-backed generic edges (5 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:13Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 4 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:associated_with×2, METPO:2007401×1, RO:0002326×1).
  llm_assisted: true