KELCH F-BOX Protein Positively Influences Arabidopsis Seed Germination by Targeting PHYTOCHROME-INTERACTING FACTOR1

Seeds employ sensory systems that assess various environmental cues over time to maximize the successful transition from embryo to seedling. Here we show that the Arabidopsis F-BOX protein COLD TEMPERATURE-GERMINATING (CTG)-10, identified by activation tagging, is a positive regulator of this process. When overexpressed (OE), CTG10 hastens aspects of seed germination. CTG10 is expressed predominantly in the hypocotyl, and the protein is localized to the nucleus. CTG10 interacts with PHYTOCHROME-INTERACTING FACTOR 1 (PIF1) and helps regulate its abundance in planta. CTG10-OE accelerates the loss of PIF1 in light, increasing germination efficiency, while PIF1-OE lines fail to complete germination in darkness, which is reversed by concurrent CTG10-OE. Double-mutant (pif1 ctg10) lines demonstrated that PIF1 is epistatic to CTG10. Both CTG10 and PIF1 amounts decline during seed germination in the light but reaccumulate in the dark. PIF1 in turn down-regulates CTG10 transcription, suggesting a feedback loop of CTG10/PIF1 control. The genetic, physiological, and biochemical evidence, when taken together, leads us to propose that PIF1 and CTG10 coexist, and even accumulate, in the nucleus in darkness, but that, following illumination, CTG10 assists in reducing PIF1 amounts, thus promoting the completion of seed germination and subsequent seedling development

Tracing social interactions in Pleistocene North America via 3D model analysis of stone tool asymmetry.

Stone tools, often the sole remnant of prehistoric hunter-gatherer behavior, are frequently used as evidence of ancient human mobility, resource use, and environmental adaptation. In North America, studies of morphological variation in projectile points have provided important insights into migration and interactions of human groups as early as 12-13 kya. Using new approaches to 3D imaging and morphometric analysis, we here quantify bifacial asymmetry among early North American projectile point styles to better understand changes in knapping technique and cultural transmission. Using a sample of 100 fluted bifaces of Clovis and post-Clovis styles in the eastern United States ca. 13,100-9,000 cal BP (i.e., Clovis, Debert-Vail, Bull Brook, Michaud-Neponset/Barnes, and Crowfield), we employed two different approaches for statistical shape analysis: our previously presented method for analysis of 2D flake scar contours, and a new approach for 3D surface analysis using spherical harmonics (SPHARM). Whereas bifacial asymmetry in point shape does not vary significantly across this stylistic sequence, our measure of asymmetric flake scar patterning shows temporal variation that may signify the beginning of regionalization among early New World colonists

Three-dimensional models and their associated flake scar contours (superimposed flake scars from front and back faces) for projectile points of each style group.

<p>From left to right: Clovis US, Clovis East, Bull Brook, Debert-Vail, Michaud-Neponset Barnes, and Crowfield. Specimens displaying both high (top row) and low (bottom row) flake scar asymmetry are shown.</p

Results of F-tests for variance differences between log-transformed measures of flake scar (2D contour) asymmetry by style group.

<p>Results of F-tests for variance differences between log-transformed measures of flake scar (2D contour) asymmetry by style group.</p

Pairwise p-values (corrected for type I error) from t-tests of differences in flake scar (2D contour) asymmetry between style groups.

<p>Pairwise p-values (corrected for type I error) from t-tests of differences in flake scar (2D contour) asymmetry between style groups.</p

Flake scar contours from the front and back sides were obtained as isoheight contours created by intersecting the 3D surface model with two x−y planes, each offset a distance of ¼ total specimen thickness in the positive or negative z-direction.

<p>See Sholts et al. (2012) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179933#pone.0179933.ref007" target="_blank">7</a>] for a full description of this process.</p

Geographic distribution of the eastern projectile points used in this study, with major sites listed.

<p>Map created by author JAMG using the ArcGIS 10.3.1 software.</p

Pairwise p-values (corrected for type I error) from t-tests of differences in surface (3D) asymmetry between style groups.

<p>Pairwise p-values (corrected for type I error) from t-tests of differences in surface (3D) asymmetry between style groups.</p