Flavor perception and aroma release from model dairy desserts

Six model dairy desserts, with three different textures and two sucrose levels, were equally flavored with a blend of four aroma compounds [ethyl pentanoate, amyl acetate, hexanal, and (E)-2-hexenal] and evaluated by a seven person panel in order to study whether the sensory perception of the flavor and the aroma release during eating varied with the textural characteristics or the sweetness intensity of the desserts. The sensory perception was recorded by the time intensity (TI) method, while the in vivo aroma release was simultaneously measured by the MS-nose. Considering the panel as a whole, averaged flavor intensity increased with sucrose level and varied with the texture of the desserts. Depending on the aroma compound, the averaged profile of in vivo aroma release varied, but for each aroma compound, averaged aroma release showed no difference with the sucrose level and little difference with the texture of the desserts. Perceptual sweetness-aroma interactions were the main factors influencing perception whatever the texture of the desserts.     

Evolution of Chemical Composition and Microbial Activity during Storage of Compost-Based Mixes

? Horticultural substrates composed of equal parts of peat and compost (v/v) were stored for a period of 24 weeks. The chemical properties and the microbial activity were determined periodically for a wet mix (55% moisture), a dry mix (25% moisture) and a wet mix amended with feather meal. Results showed that electrical conductivity and major nutrients increased with the length of the storage period whereas pH, ammonium and minor elements with the exception of manganese were strongly reduced. The pH and the chemical composition of the dry mix were not affected during storage. Feather meal actively stimulated the microorganisms within few weeks and raised electrical conductivity and nitrates at the end of storage. It was concluded that changes which occurred during storage were related to the microbial activity.     

Translational operator of mRNA on the ribosome: how repressor proteins exclude ribosome binding

The ribosome of Thermus thermophilus was cocrystallized with initiator transfer RNA (tRNA) and a structured messenger RNA (mRNA) carrying a translational operator. The path of the mRNA was defined at 5.5 angstroms resolution by comparing it with either the crystal structure of the same ribosomal complex lacking mRNA or with an unstructured mRNA. A precise ribosomal environment positions the operator stem-loop structure perpendicular to the surface of the ribosome on the platform of the 30S subunit. The binding of the operator and of the initiator tRNA occurs on the ribosome with an unoccupied tRNA exit site, which is expected for an initiation complex. The positioning of the regulatory domain of the operator relative to the ribosome elucidates the molecular mechanism by which the bound repressor switches off translation. Our data suggest a general way in which mRNA control elements must be placed on the ribosome to perform their regulatory task.     

Tight junction proteins in the canine epidermis: A pilot study on their distribution in normal and in high IgE-producing canines

Epidermal tight junctions (TJ) have been well-described in human medicine and are involved in many skin diseases such as atopic dermatitis (AD). In dogs, there are no data regarding the implication of TJ in skin diseases including canine AD.The aim of this study was to compare the expression and the distribution of ZO-1, occludin and claudin-1 in the epidermis of healthy and atopic dogs.Skin biopsies from 6 high IgE-producing beagles sensitized to house dust mite (atopic group) were used. Skin specimens from nine healthy dogs without skin issues were sampled (healthy group).Immunoperoxydase staining was used to study the staining pattern of zonula occludens-1 (ZO-1), occludin and claudin-1 in the epidermis of healthy and atopic dogs. Positive controls were healthy human skin samples.Labeling patterns were assessed by 2 examiners blinded to the identities of the specimens. Comparisons between groups were performed using an exact Wilcoxon-Mann-Whitney test.The mean total expression score of claudin-1 was lower in atopic dogs as compared to healthy subjects. Occludin and ZO-1 expression remained unchanged within each group.These results suggest a defect in claudin-1 expression in the nonlesional epidermis of atopic dogs.