identifier: METPO:1000672 label: dumbbell shaped definition: A cell shape in which an organism consists of two rounded cell bodies connected by a narrower central isthmus, often resulting from incomplete or snapping cell division. definition_source: DOI:10.1111/j.1574-6976.2011.00298.x trait_category: MORPHOLOGY term_kind: CLASS mapping_status: REVIEWED parent_traits: - METPO:1000666 synonyms: - synonym_text: S_star_dumbbell_pleomorphic synonym_type: RELATED_SYNONYM source: metpo.owl - synonym_text: dumbbell-shaped synonym_type: RELATED_SYNONYM source: metpo.owl evidence: - reference: DOI:10.1111/j.1574-6976.2011.00298.x snippet: snapping cell division notes: Corynebacterineae review supports snapping/V-form division producing transient dumbbell pairs. causal_graphs: - graph_id: dumbbell_shaped_snapping_division title: Dumbbell-shape snapping division intermediate description: DOI-backed graph linking pre-separation septum constriction and snapping/incomplete cell division to dumbbell cell pairs. nodes: - node_id: dumbbell_shaped_trait label: dumbbell shaped node_type: TRAIT grounding: METPO:1000672 description: Two-lobe cell body joined by a central isthmus. - node_id: midcell_constriction label: midcell constriction node_type: BIOLOGICAL_PROCESS description: Division-site constriction pinching the cell at midcell. - node_id: snapping_division label: snapping division node_type: BIOLOGICAL_PROCESS description: Incomplete outer-layer separation that keeps daughter cells linked. - node_id: dumbbell_intermediate label: dumbbell intermediate node_type: BIOLOGICAL_PROCESS description: Two-lobe cell pair joined by an isthmus prior to full separation. - node_id: septal_pg_hydrolysis label: septal peptidoglycan hydrolysis node_type: BIOLOGICAL_PROCESS description: Precisely timed and localized hydrolysis of septal peptidoglycan at the division junction. - node_id: daughter_cell_separation label: daughter cell separation node_type: BIOLOGICAL_PROCESS description: Resolution of the septum into two physically separated daughter cells, often via V-snapping. grounding: GO:0000920 - node_id: outer_envelope_continuity label: outer envelope layer continuity node_type: STATE description: Arabinogalactan and mycolic-acid outer layers remaining continuous across the septum. - node_id: mechanical_snapping_separation label: mechanical snapping separation node_type: BIOLOGICAL_PROCESS description: Rupture of continuous outer envelope layers producing an uneven mechanical snap. - node_id: v_shaped_daughters label: V-shaped attached daughters node_type: TRAIT description: Angular V-shaped arrangement of partially attached daughter cells from snapping division. - node_id: septal_hydrolases label: septal peptidoglycan hydrolases (RipA/RpfB) node_type: GENE_OR_PROTEIN description: Peptidoglycan-cleaving enzymes that cut the septum to separate daughter cells. - node_id: polar_growth label: polar growth from nascent septum node_type: BIOLOGICAL_PROCESS description: Apical cell-wall growth initiated from the new pole at the nascent septum. edges: - subject: midcell_constriction predicate: produces object: dumbbell_intermediate description: Strong midcell constriction creates a two-lobe pre-division morphology. evidence: - reference: DOI:10.1111/j.1574-6976.2011.00298.x snippet: snapping cell division notes: Supports midcell constriction as the proximate event preceding dumbbell intermediates. predicate_id: METPO:2000202 - subject: snapping_division predicate: stabilizes object: dumbbell_intermediate description: Snapping/V-form division preserves linkage between daughter cells. evidence: - reference: DOI:10.1111/j.1574-6976.2011.00298.x snippet: snapping cell division notes: Supports snapping division as the mechanism stabilizing post-division dumbbells. - subject: dumbbell_intermediate predicate: manifests as object: dumbbell_shaped_trait description: The dumbbell intermediate manifests the dumbbell-shaped trait. evidence: - reference: DOI:10.1111/j.1574-6976.2011.00298.x snippet: snapping cell division notes: Supports the trait endpoint. predicate_id: METPO:2007400 - subject: septal_pg_hydrolysis predicate: enables object: daughter_cell_separation description: Timed, localized septal PG hydrolysis enables daughter-cell separation / V-snapping. evidence: - reference: DOI:10.1073/pnas.2214599119 notes: Daughter cell separation requires precisely timed and localized peptidoglycan hydrolysis at the septal junction. predicate_id: RO:0002327 - subject: septal_pg_hydrolysis predicate: combined with object: mechanical_snapping_separation description: Septal PG cleavage while outer AG/MA layers remain continuous leads to mechanical snapping separation. evidence: - reference: DOI:10.1128/mmbr.00028-07 notes: Overlying envelope layers (AG, mycolic acids) remain continuous across the septum; separation occurs by rupture of these outer layers, an uneven mechanical snap. - subject: outer_envelope_continuity predicate: promotes object: mechanical_snapping_separation description: Continuity of outer envelope layers forces a final mechanical rupture (snap) to complete separation. evidence: - reference: DOI:10.1128/mmbr.00028-07 notes: Continuity/intertwining of AG and mycolate outer layers forces a final mechanical rupture. predicate_id: RO:0002213 - subject: mechanical_snapping_separation predicate: produces object: v_shaped_daughters description: Uneven rupture of intertwined outer envelope layers produces V-shaped attached daughters. evidence: - reference: DOI:10.1128/mmbr.00028-07 notes: Uneven rupturing produces the V-shape; snapping division produces angular daughter arrangements. predicate_id: METPO:2000202 - subject: septal_hydrolases predicate: mediates object: septal_pg_hydrolysis description: Septal PG hydrolases (RipA, RpfB) cleave the septum to separate daughter cells. evidence: - reference: DOI:10.1038/nrmicro3299 notes: RipA and RpfB cleave the septum to separate the daughter cells. - subject: polar_growth predicate: aggravates object: mechanical_snapping_separation description: Polar growth from the nascent septum can aggravate rupture/snapping of outer layers. evidence: - reference: DOI:10.1128/mmbr.00028-07 notes: Polar growth from the nascent septum can aggravate rupture; relevant to transient two-bulb dumbbell form before full snap. curation_history: - timestamp: '2026-05-05T01:35:46.888187+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 midcell constriction and snapping division to dumbbell cell 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 (METPO:2000202×1). 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: '2026-06-23T00:00:00Z' curator: claude action: ENRICH_CAUSAL_GRAPH changes: Added 6 evidence-backed generic edges (7 new nodes) from the deep-research report. llm_assisted: true - timestamp: '2026-06-24T17:21:13Z' curator: claude action: GROUND_CAUSAL_PREDICATES changes: Grounded 3 causal-edge predicate_id field(s) via mappings/predicate_grounding.tsv (RO:0002327×1, RO:0002213×1, METPO:2000202×1). llm_assisted: true - timestamp: '2026-06-24T17:23:33Z' curator: claude action: GROUND_CAUSAL_NODES changes: Grounded 1 causal-node grounding field(s) via mappings/node_grounding.tsv (GO:0000920×1). llm_assisted: true