Non-contact universal sample presentation for room temperature macromolecular crystallography using acoustic levitation

Macromolecular Crystallography is a powerful and valuable technique to assess protein structures. Samples are commonly cryogenically cooled to minimise radiation damage effects from the X-ray beam, but low temperatures hinder normal protein functions and this procedure can introduce structural artefacts. Previous experiments utilising acoustic levitation for beamline science have focused on Langevin horns which deliver significant power to the confined droplet and are complex to set up accurately. In this work, the low power, portable TinyLev acoustic levitation system is used in combination with an approach to dispense and contain droplets, free of physical sample support to aid protein crystallography experiments. This method facilitates efficient X-ray data acquisition in ambient conditions compatible with dynamic studies. Levitated samples remain free of interference from fixed sample mounts, receive negligible heating, do not suffer significant evaporation and since the system occupies a small volume, can be readily installed at other light sources

Durum wheat (Triticum durum Desf.) Mediterranean landraces as sources of variability for allelic combinations at Glu-1/Glu-3 loci affecting gluten strength and pasta cooking quality

With the aim of identifying durum wheat landraces (LR) with a potential use in breeding programs for gluten strength enhancement, the allelic combinations present at five glutenin loci were determined in a collection of 155 LR from 21 Mediterranean countries. A set of 18 modern cultivars (MC) was used for comparison. Gluten strength was determined by SDS-sedimentation test on grain samples from field experiments conducted during 3 years. A total number of 131 different allelic/banding pattern combinations were found. Taking together high (HMW-) and low (LMW-) molecular weight glutenin subunit loci resulted in 126 combinations in LR, but only nine in MC, which are characterized for having strong gluten. Two LMW-2 type models were identified in the collection and LMW-1 types were absent. LMW-2 was present in 78 % of MC, including the only three with outstanding gluten strength (Ocotillo, Claudio and Meridiano), while 14 % of the LR had LMW-2 and 6 % LMW-2-. In the LR a known combination LMW-2 (aaa) and three new ones had a positive effect on the gluten strength. LMW-2 models were found in high frequency in LR from Italy and the three Maghreb countries; from medium to low frequencies in genotypes from Turkey, Jordan, Lebanon, Portugal and Spain, and were absent in the remaining countries. The large variability found in LR proved their potential value in breeding to broaden the genetic basis of gluten quality improvement. Genotypes interesting for breeding purposes are identified.info:eu-repo/semantics/publishedVersio