Evolutionary paths underlying flower color variation in Antirrhinum

To understand evolutionary paths connecting diverse biological forms, we defined a three-dimensional genotypic space separating two flower color morphs of Antirrhinum. A hybrid zone between morphs showed a steep cline specifically at genes controlling flower color differences, indicating that these loci are under selection. Antirrhinum species with diverse floral phenotypes formed a U-shaped cloud within the genotypic space. We propose that this cloud defines an evolutionary path that allows flower color to evolve while circumventing less-adaptive regions. Hybridization between morphs located in different arms of the U-shaped path yields low-fitness genotypes, accounting for the observed steep clines at hybrid zones.     

Atomic-scale control of friction by actuation of nanometer-sized contacts

Stiction and wear are demanding problems in nanoelectromechanical devices, because of their large surface-to-volume ratios and the inapplicability of traditional liquid lubricants. An efficient way to switch friction on and off at the atomic scale is achieved by exciting the mechanical resonances of the sliding system perpendicular to the contact plane. The resulting variations of the interaction energy reduce friction below 10 piconewtons in a finite range of excitation and load, without any noticeable wear. Without actuation, atomic stick-slip motion, which leads to dissipation, is observed in the same range. Even if the normal oscillations require energy to actuate, our technique represents a valuable way to minimize energy dissipation in nanocontacts.     

Direct optical biosensor analysis of folate-binding protein in milk

An automated, rapid, sensitive, and label-free biosensor-based assay for folate-binding protein (FBP) in bovine milk utilizing surface plasmon resonance optical detection is described. The active concentration of FBP is estimated from its specific interaction with a pteroyl-l-glutamic (folic) acid derivative immobilized on the sensor surface in a direct binding assay format. Milk, colostrum, and milk powders are prepared for analysis by dilution into buffer. Analysis conditions, including ligand immobilization, flow rate, contact time, and regeneration, have been defined, and nonspecific binding considerations were evaluated. Performance parameters include a working range for FBP in buffer of 0-200 ng/mL, a method detection limit of 0.13 microg/mL in fluid milk, overall instrument response RSD(R) of 0.64%, a mean interassay RSD(R) of 7.3% for skim milk powder, and surface stability over ca. 200 samples. The technique was applied to the measurement of active FBP content of consumer milks, the heat classification of skim milk powders manufactured under a wide range of thermal processing protocols, and change during early bovine lactation.     

Effect of water deficit on Merlot grape tannins and anthocyanins across four seasons

Tannins and anthocyanins impart important sensory attributes and potential health benefits in wine. The effect of water deficits (WDs) on fruit growth, anthocyanins, and skin tannins was investigated in field grown Vitis vinifera L. ‘Merlot’ berries across four seasons (2004, 2005, 2007, and 2008) by imposing deficits from the onset of ripening until maturity. WD reduced berry weight and increased the concentration of anthocyanins all four seasons, and increased the concentration of tannins three of four seasons. Under WD, anthocyanin concentration at harvest (mg/g of berry fresh weight) was 53.0–61.6% greater than in Controls (C), and anthocyanin content (mg/berry) was 28.7–35.3% greater than in C. By contrast, WD increased tannin concentration (mg/g of berry fresh weight) at harvest by 12.6–36.9% compared to C in 2004, 2005, and 2008, and did not influence the concentration in 2007. Tannin content (mg/berry) at harvest was unaffected except in 2004 when it was 25.7% greater than in C. Thus, water deficits consistently increased anthocyanin concentration by increasing content per berry and reducing fruit growth, but increased tannin concentration less and only by reducing fruit growth, except in one year where the tannin content was increased. These results demonstrate that management of vine water deficit during ripening is a much more effective tool to increase anthocyanins than tannins in Merlot grapes.     

Comment on "Protein sequences from mastodon and Tyrannosaurus rex revealed by mass spectrometry"

We used authentication tests developed for ancient DNA to evaluate claims by Asara et al. (Reports, 13 April 2007, p. 280) of collagen peptide sequences recovered from mastodon and Tyrannosaurus rex fossils. Although the mastodon samples pass these tests, absence of amino acid composition data, lack of evidence for peptide deamidation, and association of alpha1(I) collagen sequences with amphibians rather than birds suggest that T. rex does not.     

Stumpage value in the short wood system for the conversion into high forest of a oak coppice

This study aims to analyze the factors affecting the costs of different logging systems, in particular considering three different bunching-extraction methods. Moreover the stumpage value of each plot was calculated, and a comparison analysis of the results is presented. The work was carried out in Central Italy, in an aged Quercus cerris L. coppice in hill zones, with a 45% average slope. Short wood system harvesting was applied. Felling and processing were performed by chainsaw, while extraction with three different methods: plot No. 1 with mules, plot No. 2 with a tractor with winch, plot No. 3 with polyethylene chute line. Transport of firewood from the forest track to the landing was made by a tractor loaded as a mule. In the plot No. 1 the costs per unit mass (30.76 ? 33% -1 ) were higher despite having the lower cost per hour (39.99 ? -1 ). The reason was the lower productivity (1.3 t 33% ·h -1 ). The plot No. 2 had the highest cost per hour (66.79 ? -1 ). However, productivity was the highest (2.7 t 33% ·h -1 ). This aspect was notable from the financial point of view (24.74 ? 33% -1 ). Plot No. 3 was the less expensive (23.92 ? 33% -1 ). Comparing the three methods, a reduction of the costs through more appropriate extraction systems may increase the stumpage value from 8.3 to 9.65 ? 33% -1 .