AKIMA interpolation: A tool used in direct slit-length desmearing procedures of non-frequency- limited X-ray scattering curves

X-ray small- and medium-angle scattering of partially ordered or semicrystalline materials is composed of background scattering from the form scattering of the components and from the amorphous phase and of peaks from the scattering of the crystallites. By the slit geometry of X-ray diffractometers constructed for registration of small- and medium-angle X-ray scattering, the diffuse scattering and the peaks are distorted and the peak positions and half-widths are changed. A program module based on the Akima interpolation [Akima (1970). J. Assoc. Comput. Mach. 17, 589-602] is proposed for calculation of the first derivative of the complete smeared scattering curve, which is then explicitly used in direct collimation-correction procedures. The desmearing of scattering curves from semicrystalline starch samples proves the convenience of the method for low-noise conditions and exhibits a significant gain of measuring time in comparison with data of comparable accuracy but measured with Soller-slit collimation systems or desmeared with direct methods using frequency filtering

Gain, Loss and Divergence in Primate Zinc-Finger Genes: A Rich Resource for Evolution of Gene Regulatory Differences between Species

The molecular changes underlying major phenotypic differences between humans and other primates are not well understood, but alterations in gene regulation are likely to play a major role. Here we performed a thorough evolutionary analysis of the largest family of primate transcription factors, the Krüppel-type zinc finger (KZNF) gene family. We identified and curated gene and pseudogene models for KZNFs in three primate species, chimpanzee, orangutan and rhesus macaque, to allow for a comparison with the curated set of human KZNFs. We show that the recent evolutionary history of primate KZNFs has been complex, including many lineage-specific duplications and deletions. We found 213 species-specific KZNFs, among them 7 human-specific and 23 chimpanzee-specific genes. Two human-specific genes were validated experimentally. Ten genes have been lost in humans and 13 in chimpanzees, either through deletion or pseudogenization. We also identified 30 KZNF orthologs with human-specific and 42 with chimpanzee-specific sequence changes that are predicted to affect DNA binding properties of the proteins. Eleven of these genes show signatures of accelerated evolution, suggesting positive selection between humans and chimpanzees. During primate evolution the most extensive re-shaping of the KZNF repertoire, including most gene additions, pseudogenizations, and structural changes occurred within the subfamily homininae. Using zinc finger (ZNF) binding predictions, we suggest potential impact these changes have had on human gene regulatory networks. The large species differences in this family of TFs stands in stark contrast to the overall high conservation of primate genomes and potentially represents a potent driver of primate evolution

Flavour-improved alcohol-free beer – Quality traits, ageing and sensory perception

The increasing popularity of alcohol-free beers (AFBs) fosters the industry interest in delivering the best possible product. Yet, a remaining sensory defect of AFBs is the over-perception of wort flavour, caused by elevated concentrations of small volatile flavour compounds (i.e. aldehydes). Previously, molecular sieves (hydrophobic ZSM-5 type zeolites) were found most suitable to remove these flavours by adsorption with high selectivity from the AFBs. In this work, a flavour-improved beer is produced at pilot-scale using this novel technology, and its chemical composition, sensory profile and stability are evaluated against a reference. Aldehyde concentrations in the flavour-improved product were found 79–93% lower than in the reference. The distinct difference was confirmed with a trained sensory panel and could be conserved even after three months ageing at 30 °C. Future work will focus on the process design to scale up this technology.BT/Bioprocess Engineerin

Strukturbildung von Biopolymeren (Proteinen). Struktur aufgefalteter Proteine und Protein-Protein-Wechselwirkungen in konzentrierten Loesungen

Small-angle X-ray scattering and dynamic light scattering investigations on proteins denatured by acid or by guanidine hydrochloride (proteins apo-cytochrome c, streptokinase, histon H1, staphylokinase, phosphoglycerate kinase) proved that the denatured proteins have the conformation of a perturbed random coil with repulsive potentials between the chain segments. Structural models are proposed for streptokinase and staphylokinase in solution. Both consist of compact, separately folded domains (four domains in streptokinase; two domains in staphylokinase) linked by mobil segments of the protein chain. The molecules exhibit the conformation of a flexible string-of-beds in solution by which crystallization is subdued. In the frame of this work computer programs and theoretical methods have been developed for an improved interpretation of small- and intermediate-angle X-ray scattering results. (WEN)SIGLEAvailable from TIB Hannover: F94B976+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman