Characterization and distribution of phenolics in carrot cell walls

Carrot cell walls have been shown to contain significant quantities of esterified p-hydroxybenzoic acid, which is presumed to be esterified to cell wall polymers. The purpose of this study was to investigate the distribution of p-hydroxybenzoic acid and related phenolics among carrot cell wall polysaccharides. Cell wall material was prepared from fresh carrot root tissues and extracted sequentially with water, imidazole, cyclohexane- trans-1,2-diamine- N, N, N', N'-tetraacetate, Na 2CO 3, and KOH (0.5, 1, and 4 M) to leave a cellulose-rich residue. The fractions were analyzed for their carbohydrate and phenolic acid components. Selected soluble fractions were subfractionated further by graded precipitation in ethanol. The majority of the polymer fractions comprised pectic polysaccharides, with varying quantities of neutral sugars (arabinose and galactose). Hemicellulosic polymers were generally found only in the strong alkali extracts (4 M KOH). p-OH-benzoic acid was the predominant phenolic ester and was associated with most fractions analyzed; p-OH-benzaldehyde was also detected in the fractions at much lower levels. Principal components analysis of the chemical data indicated that the p-OH-benzoic acid was associated predominantly with the branched pectic polysaccharides, in contrast to the p-OH-benzaldehyde. The possible roles and functional properties of these phenolics are discussed.     

Effects of plant sulfur nutrition on acrylamide and aroma compounds in cooked wheat

Wheat flour from plants deficient in sulfur has been shown to contain substantially higher levels of free amino acids, particularly asparagine and glutamine, than flour from wheat grown where sulfur nutrition was sufficient. Elevated levels of asparagine resulted in acrylamide levels up to 6 times higher in sulfur-deprived wheat flour, compared with sulfur-sufficient wheat flour, for three varieties of winter wheat. The volatile compounds from flour, heated at 180 degrees C for 20 min, have been compared for these three varieties of wheat grown with and without sulfur fertilizer. Approximately 50 compounds were quantified in the headspace extracts of the heated flour; over 30 compounds were affected by sulfur fertilization, and 15 compounds were affected by variety. Unsaturated aldehydes formed from aldol condensations, Strecker aldehydes, alkylpyrazines, and low molecular weight alkylfurans were found at higher concentrations in the sulfur-deficient flour, whereas low molecular weight pyrroles and thiophenes and sugar breakdown products were found at higher concentrations in the sulfur-sufficient flour. The reasons for these differences and the relationship between acrylamide formation and aroma volatile formation are discussed.     

Molecular virology of feline calicivirus.

Caliciviridae are small, nonenveloped, positive-stranded RNA viruses. Much of our understanding of the molecular biology of the caliciviruses has come from the study of the naturally occurring animal caliciviruses. In particular, many studies have focused on the molecular virology of feline calicivirus (FCV), which reflects its importance as a natural pathogen of cats. FCVs demonstrate a remarkable capacity for high genetic, antigenic, and clinical diversity; "outbreak" vaccine resistant strains occur frequently. This article updates the reader on the current status of clinical behavior and pathogenesis of FCV.     

Diagnostic exercise: papulovesicular dermatitis in rhesus macaques (Macaca mulatta)

Eleven rhesus monkeys developed multifocal erythematous and a vesicular rash. Most recovered spontaneously, but a 21-year-old female became moribund and was euthanized. Findings were of vesicular dermatitis and widespread multifocal hemorrhagic necrosis of the lungs and other viscera, with intralesional intranuclear inclusions. Simian varicella virus was identified as the cause by polymerase chain reaction analysis and serologic testing.     

Evaluation of the pathogenic potential of cervid adenovirus in calves.

Four 3-month-old Jersey calves and three 3-month-old Holstein calves were inoculated with cervid adenovirus and monitored for clinical signs until necropsied between 10 and 42 days postinoculation. The neonatal Jersey calves had received colostrum, and the Holstein calves were colostrum deprived. Preinoculation and postinoculation serum samples were tested for antibodies to the cervid adenovirus, bovine adenovirus type 6, bovine adenovirus type 7, and goat adenovirus type 1. Virus isolation was performed on kidney, nasal secretion, and/or lung homogenates in fetal white-tailed deer lung cells. Negatively stained preparations of feces from Jersey calves were examined weekly using an electron microscope, and weekly blood samples were collected for complete blood counts. Full necropsies were performed on all calves. A complete selection of tissues was evaluated for microscopic changes, and immunohistochemistry was performed on all tissues using a polyclonal antibody to deer adenovirus. No clinical signs were observed in the calves during the study period. Following inoculation, colostrum-deprived calves developed low antibody titers to deer adenovirus, while the Jersey calves that received colostrum did not. Calves that received colostrum had high antibody titers to bovine adenovirus type 7 and goat adenovirus type 1. No consistent gross or microscopic lesions were seen. Adenovirus was not observed in negatively stained preparations of feces. Immunohistochemistry results did not demonstrate virus in all tissues examined microscopically, and virus was not isolated from lungs, nasal secretions, and kidneys.     

A dielectric omnidirectional reflector

A design criterion that permits truly omnidirectional reflectivity for all polarizations of incident light over a wide selectable range of frequencies was used in fabricating an all-dielectric omnidirectional reflector consisting of multilayer films. The reflector was simply constructed as a stack of nine alternating micrometer-thick layers of polystyrene and tellurium and demonstrates omnidirectional reflection over the wavelength range from 10 to 15 micrometers. Because the omnidirectionality criterion is general, it can be used to design omnidirectional reflectors in many frequency ranges of interest. Potential uses depend on the geometry of the system. For example, coating of an enclosure will result in an optical cavity. A hollow tube will produce a low-loss, broadband waveguide, whereas a planar film could be used as an efficient radiative heat barrier or collector in thermoelectric devices.     

Femtosecond dynamics of electron localization at interfaces

The dynamics of two-dimensional small-polaron formation at ultrathin alkane layers on a silver(111) surface have been studied with femtosecond time- and angle-resolved two-photon photoemission spectroscopy. Optical excitation creates interfacial electrons in quasi-free states for motion parallel to the interface. These initially delocalized electrons self-trap as small polarons in a localized state within a few hundred femtoseconds. The localized electrons then decay back to the metal within picoseconds by tunneling through the adlayer potential barrier. The energy dependence of the self-trapping rate has been measured and modeled with a theory analogous to electron transfer theory. This analysis determines the inter- and intramolecular vibrational modes of the overlayer responsible for self-trapping as well as the relaxation energy of the overlayer molecular lattice. These results for a model interface contribute to the fundamental picture of electron behavior in weakly bonded solids and can lead to better understanding of carrier dynamics in many different systems, including organic light-emitting diodes.     

A long-snouted predatory dinosaur from africa and the evolution of spinosaurids

Fossils discovered in Lower Cretaceous (Aptian) rocks in the Tenere Desert of central Niger provide new information about spinosaurids, a peculiar group of piscivorous theropod dinosaurs. The remains, which represent a new genus and species, reveal the extreme elongation and transverse compression of the spinosaurid snout. The postcranial bones include blade-shaped vertebral spines that form a low sail over the hips. Phylogenetic analysis suggests that the enlarged thumb claw and robust forelimb evolved during the Jurassic, before the elongated snout and other fish-eating adaptations in the skull. The close phylogenetic relationship between the new African spinosaurid and Baryonyx from Europe provides evidence of dispersal across the Tethys seaway during the Early Cretaceous.