Dataset Information

Unique SMAD1/5/8 activity at the phalanx-forming region determines digit identity.

ABSTRACT: The zone of polarizing activity is the primary signaling center controlling anterior-posterior patterning of the amniote limb bud. The autopodial interdigits (IDs) are secondary signaling centers proposed to determine digit identity by acting on the cells of the digital ray. Here, we focus on events accompanying digital fate determination and define a region of the digital ray that expresses Sox9 and Bmpr1b and is phosphorylated-SMAD1/5/8 (p-SMAD1/5/8) positive. We name this region the phalanx-forming region (PFR), and show that the PFR cells arise from the distal subridge mesenchyme of digital ray. This phalanx-forming cell lineage is subsequently committed to the cartilage lineage; the fate of these cells is initially labile but becomes fixed as they are incorporated into the condensed cartilage of the digit primordium. Using an in vivo reporter assay, we establish that each digital PFR has a unique p-SMAD1/5/8 activity signature. In addition, we show that changes in this activity correlate with the identity of the digit that forms after experimental manipulation, supporting the idea that threshold signaling levels can lead to different developmental outcomes in a morphogenetic field. Our data define the molecular profile of the PFR, and we propose a model for understanding formation and variation of digits during autopodial development.

SUBMITTER: Suzuki T

PROVIDER: S-EPMC2393776 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature

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Unique SMAD1/5/8 activity at the phalanx-forming region determines digit identity.

Suzuki Takayuki T Hasso Sean M SM Fallon John F JF

Proceedings of the National Academy of Sciences of the United States of America 20080311 11

The zone of polarizing activity is the primary signaling center controlling anterior-posterior patterning of the amniote limb bud. The autopodial interdigits (IDs) are secondary signaling centers proposed to determine digit identity by acting on the cells of the digital ray. Here, we focus on events accompanying digital fate determination and define a region of the digital ray that expresses Sox9 and Bmpr1b and is phosphorylated-SMAD1/5/8 (p-SMAD1/5/8) positive. We name this region the phalanx-f ...[more]

PMID: 18334652

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Project description:Empirical evidence suggests that the rich set of ecosystem functions and nature's contributions to people provided by forests depends on tree diversity. Biodiversity-ecosystem functioning research revealed that not only species richness per se but also other facets of tree diversity, such as tree identity, have to be considered to understand the underlying mechanisms. One important ecosystem function in forests is the decomposition of deadwood that plays a vital role in carbon and nutrient cycling and is assumed to be determined by above- and belowground interactions. However, the actual influence of tree diversity on wood decay in forests remains inconclusive. Recent studies suggest an important role of microclimate and advocate a systematical consideration of small-scale environmental conditions. We studied the influence of tree species richness, tree species identity, and microclimatic conditions on wood decomposition in a 12-year-old tree diversity experiment in Germany, containing six native species within a tree species richness gradient. We assessed wood mass loss, soil microbial properties, and soil surface temperature in high temporal resolution. Our study shows a significant influence of tree species identity on all three variables. The presence of Scots pine strongly increased wood mass loss, while the presence of Norway spruce decreased it. This could be attributed to structural differences in the litter layer that were modifying the capability of plots to hold the soil surface temperature at night, consequently leading to enhanced decomposition rates in plots with higher nighttime surface temperatures. Therefore, our study confirmed the critical role of microclimate for wood decomposition in forests and showed that soil microbial properties alone were not sufficient to predict wood decay. We conclude that tree diversity effects on ecosystem functions may include different biodiversity facets, such as tree identity, tree traits, and functional and structural diversity, in influencing the abiotic and biotic soil properties.

Dataset Information

Unique SMAD1/5/8 activity at the phalanx-forming region determines digit identity.

Publications

Unique SMAD1/5/8 activity at the phalanx-forming region determines digit identity.

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