Limits...
Fundamental origins and limits for scaling a maternal morphogen gradient.

He F, Wei C, Wu H, Cheung D, Jiao R, Ma J - Nat Commun (2015)

Bottom Line: Here we develop a model, Tissue Expansion-Modulated Maternal Morphogen Scaling (TEM(3)S), to study scaled anterior-posterior patterning in Drosophila embryos.Using both ovaries and embryos, we measure a core quantity of the model, the scaling power of the Bicoid (Bcd) morphogen gradient's amplitude nA.This delicate connection between the two transitioning stages of a life cycle, stemming from a finite value of nA~3, underscores a key feature of developmental systems depicted by TEM(3)S.

View Article: PubMed Central - PubMed

Affiliation: Division of Biomedical Informatics, Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, Ohio 45229, USA.

ABSTRACT
Tissue expansion and patterning are integral to development; however, it is unknown quantitatively how a mother accumulates molecular resources to invest in the future of instructing robust embryonic patterning. Here we develop a model, Tissue Expansion-Modulated Maternal Morphogen Scaling (TEM(3)S), to study scaled anterior-posterior patterning in Drosophila embryos. Using both ovaries and embryos, we measure a core quantity of the model, the scaling power of the Bicoid (Bcd) morphogen gradient's amplitude nA. We also evaluate directly model-derived predictions about Bcd gradient and patterning properties. Our results show that scaling of the Bcd gradient in the embryo originates from, and is constrained fundamentally by, a dynamic relationship between maternal tissue expansion and bcd gene copy number expansion in the ovary. This delicate connection between the two transitioning stages of a life cycle, stemming from a finite value of nA~3, underscores a key feature of developmental systems depicted by TEM(3)S.

No MeSH data available.


Scaling power estimations for bulk nuclear DNA and gene copy numbers in nurse cellsa–c) Log-log plots for genome polyploidy equivalent (a), bcd gene copy number (b) or nos gene copy number (c), against nurse cell nuclear diameter. Solid line is linear fit, with scaling power, 95% CI and R2 shown. Inset shows fitting of data from individual lines. For WT (shown in black), n0 = 2.42 ± 0.09, R2 = 0.91; n1bcd = 2.82 ± 0.20, R2 = 0.80; n1nos = 2.83 ± 0.22, R2 = 0.76. For the large-egg line (shown in blue): n0 = 2.27 ± 0.23, R2 = 0.67; n1bcd = 3.10 ± 0.31, R2 = 0.67; n1nos = 2.79 ± 0.44, R2 = 0.45. For the small-egg line (shown in red): n0 = 2.50 ± 0.27, R2 = 0.74; n1bcd = 2.93 ± 0.45, R2 = 0.60; n1nos = 3.14 ± 0.43, R2 = 0.78.
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Figure 4: Scaling power estimations for bulk nuclear DNA and gene copy numbers in nurse cellsa–c) Log-log plots for genome polyploidy equivalent (a), bcd gene copy number (b) or nos gene copy number (c), against nurse cell nuclear diameter. Solid line is linear fit, with scaling power, 95% CI and R2 shown. Inset shows fitting of data from individual lines. For WT (shown in black), n0 = 2.42 ± 0.09, R2 = 0.91; n1bcd = 2.82 ± 0.20, R2 = 0.80; n1nos = 2.83 ± 0.22, R2 = 0.76. For the large-egg line (shown in blue): n0 = 2.27 ± 0.23, R2 = 0.67; n1bcd = 3.10 ± 0.31, R2 = 0.67; n1nos = 2.79 ± 0.44, R2 = 0.45. For the small-egg line (shown in red): n0 = 2.50 ± 0.27, R2 = 0.74; n1bcd = 2.93 ± 0.45, R2 = 0.60; n1nos = 3.14 ± 0.43, R2 = 0.78.

Mentions: Since the bcd gene locus is a part of the entire genome undergoing endoreplication, we first quantified the bulk nuclear DNA in relation to the expansion of the nurse cell nuclear diameter l. We estimated the scaling power for the bulk nuclear DNA n0 using the fitted slope in a log-log plot (Fig. 4a). We obtained n0 = 2.42, 2.27 and 2.50 for WT, large- and small-egg lines, respectively (95% confidence intervals are: 2.32~2.51, 2.04~2.50 and 2.22~2.77). Using all data pooled, n0 = 2.43 (95% CI = 2.20~2.66).


Fundamental origins and limits for scaling a maternal morphogen gradient.

He F, Wei C, Wu H, Cheung D, Jiao R, Ma J - Nat Commun (2015)

Scaling power estimations for bulk nuclear DNA and gene copy numbers in nurse cellsa–c) Log-log plots for genome polyploidy equivalent (a), bcd gene copy number (b) or nos gene copy number (c), against nurse cell nuclear diameter. Solid line is linear fit, with scaling power, 95% CI and R2 shown. Inset shows fitting of data from individual lines. For WT (shown in black), n0 = 2.42 ± 0.09, R2 = 0.91; n1bcd = 2.82 ± 0.20, R2 = 0.80; n1nos = 2.83 ± 0.22, R2 = 0.76. For the large-egg line (shown in blue): n0 = 2.27 ± 0.23, R2 = 0.67; n1bcd = 3.10 ± 0.31, R2 = 0.67; n1nos = 2.79 ± 0.44, R2 = 0.45. For the small-egg line (shown in red): n0 = 2.50 ± 0.27, R2 = 0.74; n1bcd = 2.93 ± 0.45, R2 = 0.60; n1nos = 3.14 ± 0.43, R2 = 0.78.
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Related In: Results  -  Collection

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Figure 4: Scaling power estimations for bulk nuclear DNA and gene copy numbers in nurse cellsa–c) Log-log plots for genome polyploidy equivalent (a), bcd gene copy number (b) or nos gene copy number (c), against nurse cell nuclear diameter. Solid line is linear fit, with scaling power, 95% CI and R2 shown. Inset shows fitting of data from individual lines. For WT (shown in black), n0 = 2.42 ± 0.09, R2 = 0.91; n1bcd = 2.82 ± 0.20, R2 = 0.80; n1nos = 2.83 ± 0.22, R2 = 0.76. For the large-egg line (shown in blue): n0 = 2.27 ± 0.23, R2 = 0.67; n1bcd = 3.10 ± 0.31, R2 = 0.67; n1nos = 2.79 ± 0.44, R2 = 0.45. For the small-egg line (shown in red): n0 = 2.50 ± 0.27, R2 = 0.74; n1bcd = 2.93 ± 0.45, R2 = 0.60; n1nos = 3.14 ± 0.43, R2 = 0.78.
Mentions: Since the bcd gene locus is a part of the entire genome undergoing endoreplication, we first quantified the bulk nuclear DNA in relation to the expansion of the nurse cell nuclear diameter l. We estimated the scaling power for the bulk nuclear DNA n0 using the fitted slope in a log-log plot (Fig. 4a). We obtained n0 = 2.42, 2.27 and 2.50 for WT, large- and small-egg lines, respectively (95% confidence intervals are: 2.32~2.51, 2.04~2.50 and 2.22~2.77). Using all data pooled, n0 = 2.43 (95% CI = 2.20~2.66).

Bottom Line: Here we develop a model, Tissue Expansion-Modulated Maternal Morphogen Scaling (TEM(3)S), to study scaled anterior-posterior patterning in Drosophila embryos.Using both ovaries and embryos, we measure a core quantity of the model, the scaling power of the Bicoid (Bcd) morphogen gradient's amplitude nA.This delicate connection between the two transitioning stages of a life cycle, stemming from a finite value of nA~3, underscores a key feature of developmental systems depicted by TEM(3)S.

View Article: PubMed Central - PubMed

Affiliation: Division of Biomedical Informatics, Cincinnati Children's Research Foundation, 3333 Burnet Avenue, Cincinnati, Ohio 45229, USA.

ABSTRACT
Tissue expansion and patterning are integral to development; however, it is unknown quantitatively how a mother accumulates molecular resources to invest in the future of instructing robust embryonic patterning. Here we develop a model, Tissue Expansion-Modulated Maternal Morphogen Scaling (TEM(3)S), to study scaled anterior-posterior patterning in Drosophila embryos. Using both ovaries and embryos, we measure a core quantity of the model, the scaling power of the Bicoid (Bcd) morphogen gradient's amplitude nA. We also evaluate directly model-derived predictions about Bcd gradient and patterning properties. Our results show that scaling of the Bcd gradient in the embryo originates from, and is constrained fundamentally by, a dynamic relationship between maternal tissue expansion and bcd gene copy number expansion in the ovary. This delicate connection between the two transitioning stages of a life cycle, stemming from a finite value of nA~3, underscores a key feature of developmental systems depicted by TEM(3)S.

No MeSH data available.