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

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.


Related in: MedlinePlus

The differentiation tree of the axolotl (Ambystoma mexicanum) up to neural plate formation (stages 8–12 raised at 20 °C). All cell types are presumptive. Red branches to the left labelled with the letter C indicates a contraction wave, while green branches to the right labelled with the letter E indicates an expansion wave. The time axis (vertical) is represented in two ways: (1) on the left, are hours since fertilization for embryos raised at 20 °C, (2) on the right are stage numbers based on distinctly recognizable morphological features [49]. Regarded as a vector, the vertical component of each edge represents the duration of each wave. The ordinal axis is horizontal in this figure. Note each numbered wave may pass through one tissue and continue into an adjacent tissue and so, for example, E3 begins in endodermal tissue and then continues into mesodermal tissue. From [10] with permission of World Scientific Publishing. The differentiation codes based on the named tissues (boxes) and unnamed intermediate tissues (black dots) with unique differentiation codes are determined from this tree and shown in Table S6.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5037352&req=5

biology-05-00033-f013: The differentiation tree of the axolotl (Ambystoma mexicanum) up to neural plate formation (stages 8–12 raised at 20 °C). All cell types are presumptive. Red branches to the left labelled with the letter C indicates a contraction wave, while green branches to the right labelled with the letter E indicates an expansion wave. The time axis (vertical) is represented in two ways: (1) on the left, are hours since fertilization for embryos raised at 20 °C, (2) on the right are stage numbers based on distinctly recognizable morphological features [49]. Regarded as a vector, the vertical component of each edge represents the duration of each wave. The ordinal axis is horizontal in this figure. Note each numbered wave may pass through one tissue and continue into an adjacent tissue and so, for example, E3 begins in endodermal tissue and then continues into mesodermal tissue. From [10] with permission of World Scientific Publishing. The differentiation codes based on the named tissues (boxes) and unnamed intermediate tissues (black dots) with unique differentiation codes are determined from this tree and shown in Table S6.

Mentions: Another analysis of the data involves transforming the differentiation code into a series of letters and then aligning them to achieve a comparison between species or mutant genotypes within a species. The CAST codes for Ciona and C. elegans are located in Tables S4 and 5, respectively. Our convention (see Methods) is already in use for the differentiation tree of Ambystoma mexicanum (Urodele Salamander, axolotl). This differentiation tree is shown in Figure 13. In mosaic development, a smaller cell in a binary division represents a contraction wave, and a larger cell in a binary division represents an expansion wave (see [13]). The differentiation codes classify single differentiation trees, while the CAST translation allows for alignment with other differentiation trees to find common motifs or alignment gaps. For example, we might want to discover repeatable sequences of differentiations across species. Through comparison with lineage trees and fate maps, CAST code alignments and motif finding might uncover how portions of the differentiation tree topology get duplicated across evolution. In particular, CASTing allows a comparison between the differentiation trees of mosaic and regulating embryos.


Quantifying Mosaic Development: Towards an Evo-Devo Postmodern Synthesis of the Evolution of Development via Differentiation Trees of Embryos
The differentiation tree of the axolotl (Ambystoma mexicanum) up to neural plate formation (stages 8–12 raised at 20 °C). All cell types are presumptive. Red branches to the left labelled with the letter C indicates a contraction wave, while green branches to the right labelled with the letter E indicates an expansion wave. The time axis (vertical) is represented in two ways: (1) on the left, are hours since fertilization for embryos raised at 20 °C, (2) on the right are stage numbers based on distinctly recognizable morphological features [49]. Regarded as a vector, the vertical component of each edge represents the duration of each wave. The ordinal axis is horizontal in this figure. Note each numbered wave may pass through one tissue and continue into an adjacent tissue and so, for example, E3 begins in endodermal tissue and then continues into mesodermal tissue. From [10] with permission of World Scientific Publishing. The differentiation codes based on the named tissues (boxes) and unnamed intermediate tissues (black dots) with unique differentiation codes are determined from this tree and shown in Table S6.
© Copyright Policy
Related In: Results  -  Collection

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

biology-05-00033-f013: The differentiation tree of the axolotl (Ambystoma mexicanum) up to neural plate formation (stages 8–12 raised at 20 °C). All cell types are presumptive. Red branches to the left labelled with the letter C indicates a contraction wave, while green branches to the right labelled with the letter E indicates an expansion wave. The time axis (vertical) is represented in two ways: (1) on the left, are hours since fertilization for embryos raised at 20 °C, (2) on the right are stage numbers based on distinctly recognizable morphological features [49]. Regarded as a vector, the vertical component of each edge represents the duration of each wave. The ordinal axis is horizontal in this figure. Note each numbered wave may pass through one tissue and continue into an adjacent tissue and so, for example, E3 begins in endodermal tissue and then continues into mesodermal tissue. From [10] with permission of World Scientific Publishing. The differentiation codes based on the named tissues (boxes) and unnamed intermediate tissues (black dots) with unique differentiation codes are determined from this tree and shown in Table S6.
Mentions: Another analysis of the data involves transforming the differentiation code into a series of letters and then aligning them to achieve a comparison between species or mutant genotypes within a species. The CAST codes for Ciona and C. elegans are located in Tables S4 and 5, respectively. Our convention (see Methods) is already in use for the differentiation tree of Ambystoma mexicanum (Urodele Salamander, axolotl). This differentiation tree is shown in Figure 13. In mosaic development, a smaller cell in a binary division represents a contraction wave, and a larger cell in a binary division represents an expansion wave (see [13]). The differentiation codes classify single differentiation trees, while the CAST translation allows for alignment with other differentiation trees to find common motifs or alignment gaps. For example, we might want to discover repeatable sequences of differentiations across species. Through comparison with lineage trees and fate maps, CAST code alignments and motif finding might uncover how portions of the differentiation tree topology get duplicated across evolution. In particular, CASTing allows a comparison between the differentiation trees of mosaic and regulating embryos.

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.


Related in: MedlinePlus