A cell lineage follows descent of biological cells through successive divisions. DNA replication can transmit a mutation to descendant biological cells.
A narrowing of the descendant cell types available to a progenitor. It should be distinguished from failure to sample rare outputs and from changing developmental competence.
The normal or precursor cellular lineage in which a tumour-initiating evolutionary process occurs. It can differ from the phenotype of the established malignant cells.
Following descendants of identified cells through development. Marker expression at one instant is a state measurement rather than a complete lineage history.
The lineage that gives rise to reproductive cells transmitting genetic information between generations, distinguished from somatic body-cell lineages.
In animals with an early segregated germ line, only selected cellular descendants normally contribute to gametes. In other organisms, reproductive lineages can be specified later. A mutation’s presence in a body cell therefore does not alone establish transmission to offspring. [ref]
Mechanisms protecting the inherited genome from transposable elements and other threats. Suppression of transposon RNA, chromatin repression and removal of damaged cells are different protective strategies.
Tracking descendants through an inherited genetic label or sequence change. Labelling specificity, timing and independent activation determine what ancestry can be inferred.
Failure to recover a lineage label from a sampled descendant. No recovered label is therefore not equivalent to proof of absent ancestry.
Using accumulated CRISPR-induced sequence changes as inherited records of ancestry. Nested scars support a lineage tree only after considering recurrent edits, deletion of earlier scars and missing observations.
A lineage-recording approach coupling inherited CRISPR barcode edits with single-cell transcriptomes. It can relate cell identity to developmental ancestry while retaining the limitations of incomplete barcode recovery and edit homoplasy.[ref]
An inherited sequence label used to distinguish cell ancestries. Independent acquisition of the same barcode, loss of the readout and nonuniform barcode frequencies can all confound a clonal inference.
Independent cells receive the same apparent label. If barcode probabilities are , two independent founders match with probability , rather than necessarily the inverse of the nominal library size.
Lineage tracing that identifies descendants of a single ancestor. A labelled group is informative about a clone only if labelling collisions and independent activation are excluded.
The distribution of descendant counts per clone. Differences can arise from proliferation, survival, migration or sampling rather than altered fate choice alone.
Labelling few enough founder cells to resolve individual clones. The acceptable density depends on spatial mixing, label diversity and the chance of independent activation.
Production of more than one differentiated cell type from one confirmed progenitor. Several separately labelled unipotent cells can imitate this pattern if the label is not unique.
Competition among labelled clones with equivalent average reproductive behaviour. Clone extinction can coexist with tissue maintenance, and surviving clones form a selected subset of all initial clones.
