identifier: METPO:1000694
label: square shaped
definition: A cell shape in which an organism forms flat, square or rectangular cells.
definition_source: DOI:10.1099/ijs.0.65431-0
trait_category: MORPHOLOGY
term_kind: CLASS
mapping_status: REVIEWED
parent_traits:
- METPO:1000666
synonyms:
- synonym_text: square
  synonym_type: RELATED_SYNONYM
  source: metpo.owl
evidence:
- reference: DOI:10.1099/ijs.0.65431-0
  snippet: flat square or disc-shaped cells
  notes: Haloquadratum walsbyi description supports flat square cell morphology in
    halophilic archaea.
- reference: DOI:10.1146/annurev-cellbio-101011-155745
  snippet: cell shape is genetically determined
  notes: Cell-shape review supports anisotropic envelope growth as the basis for non-round
    cell geometries.
canonical_examples:
- taxon_id: NCBITaxon:293091
  taxon_label: Haloquadratum walsbyi
  note: "Universally cited square/rectangular flat-celled archaeon (2-5 um wide x 0.1-0.2 um thick); dominant in hypersaline salterns."
  reference: DOI:10.1371/journal.pone.0018653
causal_graphs:
- graph_id: square_shaped_planar_anisotropic_growth
  title: Square-shape planar anisotropic envelope growth
  description: DOI-backed graph linking anisotropic planar cell-envelope growth and
    S-layer-constrained right-angle geometry to flat square cells.
  nodes:
  - node_id: square_shaped_trait
    label: square shaped
    node_type: TRAIT
    grounding: METPO:1000694
    description: Flat square or rectangular cell geometry.
  - node_id: planar_envelope_growth
    label: planar envelope growth
    node_type: BIOLOGICAL_PROCESS
    description: Cell-envelope expansion in two orthogonal in-plane directions.
  - node_id: slayer_constraints
    label: S-layer constraints
    node_type: ORGANELLE
    description: Paracrystalline S-layer that imposes geometric constraints on cell
      shape.
    grounding: GO:0030115
  - node_id: right_angle_growth
    label: right-angle growth geometry
    node_type: BIOLOGICAL_PROCESS
    description: Growth pattern producing perpendicular cell edges.
  - node_id: archaeal_slayer
    label: archaeal S-layer
    node_type: ORGANELLE
    description: Paracrystalline surface (S-)layer of glycosylated proteins coating
      the archaeal cell.
  - node_id: cell_shape
    label: cell shape
    node_type: QUALITY
    description: Overall geometric form of the cell.
  - node_id: mechanical_stability
    label: mechanical stability
    node_type: QUALITY
    description: Resistance of the cell envelope to mechanical deformation.
  - node_id: cytoskeletal_growth_axis_control
    label: cytoskeletal control of local growth and division axis
    node_type: BIOLOGICAL_PROCESS
    description: Precise control of local envelope growth and division axis guided
      by cytoskeletal filaments and an overlying S-layer coat.
  - node_id: slayer_proteins
    label: S-layer proteins
    node_type: GENE_OR_PROTEIN
    description: Glycoprotein subunits forming the paracrystalline S-layer lattice.
  - node_id: cell_shape_size_defect
    label: cell shape and size defect
    node_type: STATE
    description: Aberrant cell shape and size resulting from loss of S-layer integrity.
  edges:
  - subject: planar_envelope_growth
    predicate: enables
    object: right_angle_growth
    description: Planar envelope growth in two axes supports rectangular geometry.
    evidence:
    - reference: DOI:10.1099/ijs.0.65431-0
      snippet: flat square or disc-shaped cells
      notes: Supports planar growth as the cellular basis for flat square cells.
    predicate_id: RO:0002327
  - subject: slayer_constraints
    predicate: causes
    object: right_angle_growth
    description: The paracrystalline S-layer constrains envelope geometry toward right
      angles.
    evidence:
    - reference: DOI:10.1146/annurev-cellbio-101011-155745
      snippet: cell shape is genetically determined
      notes: Supports envelope architectural constraints (e.g., S-layer) as shape
        determinants.
    predicate_id: biolink:causes
  - subject: right_angle_growth
    predicate: manifests as
    object: square_shaped_trait
    description: Right-angle planar geometry manifests the square-shaped trait.
    evidence:
    - reference: DOI:10.1099/ijs.0.65431-0
      snippet: square or disc-shaped cells
      notes: Supports the trait endpoint.
    predicate_id: METPO:2007400
  - subject: archaeal_slayer
    predicate: defines
    object: cell_shape
    description: The archaeal S-layer is a primary structural determinant of cell
      shape.
    evidence:
    - reference: DOI:10.1038/s41564-022-01215-8
      notes: S-layers are known to fulfil roles in defining the cell-shape, providing
        mechanical stability and functioning as molecular sieves.
    predicate_id: METPO:2007500
  - subject: archaeal_slayer
    predicate: provides
    object: mechanical_stability
    description: The archaeal S-layer provides mechanical stability to the cell envelope.
    evidence:
    - reference: DOI:10.1038/s41564-022-01215-8
      notes: S-layers are known to fulfil roles in defining the cell-shape, providing
        mechanical stability and functioning as molecular sieves.
  - subject: cytoskeletal_growth_axis_control
    predicate: gives rise to
    object: square_shaped_trait
    description: Precise cytoskeleton- and S-layer-guided control of local growth
      and division axis gives rise to flat geometric (square/triangular) archaeal
      shapes.
    evidence:
    - reference: DOI:10.1038/s41564-022-01215-8
      notes: These cell shapes arise as the result of precise cellular control of
        local growth and the axis of division under the guidance of cytoskeletal filaments
        and an overlying coat of glycosylated proteins, also termed the S-layer.
  - subject: slayer_proteins
    predicate: causes when lost
    object: cell_shape_size_defect
    description: Loss of S-layer proteins causes profound defects in cell shape and
      size, evidencing the S-layer causal role in archaeal morphology.
    evidence:
    - reference: DOI:10.1038/s41564-022-01215-8
      notes: S-layer proteins were recently found to be dispensable for S.islandicus
        viability, but cells lacking these proteins exhibited profound defects in
        cell shape and size.
curation_history:
- timestamp: '2026-05-05T01:35:46.900481+00:00'
  curator: seed_from_metpo
  action: SEEDED_FROM_METPO
  changes: imported from data/raw/metpo.owl (CLASS)
  llm_assisted: false
- timestamp: '2026-05-11T22:45:00-07:00'
  curator: claude
  action: CURATED_CAUSAL_GRAPH
  changes: Added DOI-backed definition and causal graph linking planar anisotropic
    envelope growth and S-layer constraints to square-shaped halophile morphology.
  llm_assisted: true
- timestamp: '2026-05-20T03:35:31Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (RO:0002327×1).
  llm_assisted: true
- timestamp: '2026-05-23T21:30:07Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007400×1).
  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:
    shapes → causes ×1.'
  llm_assisted: true
- timestamp: '2026-05-24T04:13:22Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (biolink:causes×1).
  llm_assisted: true
- timestamp: '2026-06-23T00:00:00Z'
  curator: claude
  action: ENRICH_CAUSAL_GRAPH
  changes: Added 4 evidence-backed generic edges (6 new nodes) from the deep-research
    report.
  llm_assisted: true
- timestamp: '2026-06-24T17:21:14Z'
  curator: claude
  action: GROUND_CAUSAL_PREDICATES
  changes: Grounded 1 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv
    (METPO:2007500×1).
  llm_assisted: true