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Quantifying Mosaic Development: Towards an Evo-Devo Postmodern Synthesis of the Evolution of Development via Differentiation Trees of Embryos

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ABSTRACT

Embryonic development proceeds through a series of differentiation events. The mosaic version of this process (binary cell divisions) can be analyzed by comparing early development of Cionaintestinalis and Caenorhabditis elegans. To do this, we reorganize lineage trees into differentiation trees using the graph theory ordering of relative cell volume. Lineage and differentiation trees provide us with means to classify each cell using binary codes. Extracting data characterizing lineage tree position, cell volume, and nucleus position for each cell during early embryogenesis, we conduct several statistical analyses, both within and between taxa. We compare both cell volume distributions and cell volume across developmental time within and between single species and assess differences between lineage tree and differentiation tree orderings. This enhances our understanding of the differentiation events in a model of pure mosaic embryogenesis and its relationship to evolutionary conservation. We also contribute several new techniques for assessing both differences between lineage trees and differentiation trees, and differences between differentiation trees of different species. The results suggest that at the level of differentiation trees, there are broad similarities between distantly related mosaic embryos that might be essential to understanding evolutionary change and phylogeny reconstruction. Differentiation trees may therefore provide a basis for an Evo-Devo Postmodern Synthesis.

No MeSH data available.


Embryo volume per cell stage of embryogenesis for Ciona. Volume (measured in cubic microns) is averaged over a number of observations (N). N (stage) is given in Table S1.
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biology-05-00033-f002: Embryo volume per cell stage of embryogenesis for Ciona. Volume (measured in cubic microns) is averaged over a number of observations (N). N (stage) is given in Table S1.

Mentions: This representative ascidian (tunicate, Urochordata) is an entirely hermaphroditic species that has 1579 cells at the mid-tailbud stage [52]. Datasets [8,53] consist of pre-gastrulation cell divisions (up to 112-cell stage). Biometric data for each cell includes cell names (identity) and percentage of total embryo volume for the 2-, 4-, 8-, 16-, 24-, 32-, 44-, 64-, 76-, and 112-cell stages (data available from [54]). Volume for each cell is calculated as a percentage of the entire embryo at that stage. Figure 2 demonstrates the total volume for all embryos (per stage) in the available dataset, which is calculated as the sum of the cell volumes of all the cells at a given stage. While there is technical variation in the data for total embryo size, there is no strong trend, and so we can calculate the average volume, independent of stage, over this range of stages, as 2.04 × 106 µm3. In the original acquisition of the data, a tracer enzyme was used to identify each cell body in a whole embryo. All data (cell identities and volumetric measurements) from each embryonic stage were integrated into a single data structure in order to determine line of descent based on a reference lineage tree [8], confidence intervals, and differentiation tree order.


Quantifying Mosaic Development: Towards an Evo-Devo Postmodern Synthesis of the Evolution of Development via Differentiation Trees of Embryos
Embryo volume per cell stage of embryogenesis for Ciona. Volume (measured in cubic microns) is averaged over a number of observations (N). N (stage) is given in Table S1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037352&req=5

biology-05-00033-f002: Embryo volume per cell stage of embryogenesis for Ciona. Volume (measured in cubic microns) is averaged over a number of observations (N). N (stage) is given in Table S1.
Mentions: This representative ascidian (tunicate, Urochordata) is an entirely hermaphroditic species that has 1579 cells at the mid-tailbud stage [52]. Datasets [8,53] consist of pre-gastrulation cell divisions (up to 112-cell stage). Biometric data for each cell includes cell names (identity) and percentage of total embryo volume for the 2-, 4-, 8-, 16-, 24-, 32-, 44-, 64-, 76-, and 112-cell stages (data available from [54]). Volume for each cell is calculated as a percentage of the entire embryo at that stage. Figure 2 demonstrates the total volume for all embryos (per stage) in the available dataset, which is calculated as the sum of the cell volumes of all the cells at a given stage. While there is technical variation in the data for total embryo size, there is no strong trend, and so we can calculate the average volume, independent of stage, over this range of stages, as 2.04 × 106 µm3. In the original acquisition of the data, a tracer enzyme was used to identify each cell body in a whole embryo. All data (cell identities and volumetric measurements) from each embryonic stage were integrated into a single data structure in order to determine line of descent based on a reference lineage tree [8], confidence intervals, and differentiation tree order.

View Article: PubMed Central - PubMed

ABSTRACT

Embryonic development proceeds through a series of differentiation events. The mosaic version of this process (binary cell divisions) can be analyzed by comparing early development of Cionaintestinalis and Caenorhabditis elegans. To do this, we reorganize lineage trees into differentiation trees using the graph theory ordering of relative cell volume. Lineage and differentiation trees provide us with means to classify each cell using binary codes. Extracting data characterizing lineage tree position, cell volume, and nucleus position for each cell during early embryogenesis, we conduct several statistical analyses, both within and between taxa. We compare both cell volume distributions and cell volume across developmental time within and between single species and assess differences between lineage tree and differentiation tree orderings. This enhances our understanding of the differentiation events in a model of pure mosaic embryogenesis and its relationship to evolutionary conservation. We also contribute several new techniques for assessing both differences between lineage trees and differentiation trees, and differences between differentiation trees of different species. The results suggest that at the level of differentiation trees, there are broad similarities between distantly related mosaic embryos that might be essential to understanding evolutionary change and phylogeny reconstruction. Differentiation trees may therefore provide a basis for an Evo-Devo Postmodern Synthesis.

No MeSH data available.