Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes

This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings.     

Aspects of hadrosaurian cranial anatomy

Supraorbital bones in Saurolophus angustirostris are described, and their presence in all hadrosaurs is suggested. Frontal-nasal and premaxillar-nasal fontanellae are distinguished in hadrosaurs; their presence is explained as connected with growth and considered to he responsible for the variability of crest structures. New data indicating the presence of a cartilaginous diverticulum nasi within the circumnarial depression in Saurobphus ongustirostris are presented. A physiological (respiratory and/or thermoregulatory) function of the nasal diverticulum is proposed.     

Double-Antibody Sandwich Enzyme-Linked Immunosorbent Assay for Cellobiohydrolase I

A double-antibody sandwich enzyme-linked immunosorbent assay was developed for quantifying cellobiohydrolase I (CBH I) in crude preparations of the cellulase complex from Trichoderma reesei. The other enzymes (endoglucanase and β-glucosidase) in this complex and other ingredients in culture broth did not interfere with this assay. The antibody configuration that resulted in the highest specificity for the assay of CBH I employed a monoclonal antibody to coat wells in polystyrene plates and peroxidase-labeled polyclonal antibody to detect cellobiohydrolase bound to the immobilized monoclonal antibody. Previously, procedures have not been available for the direct assay of CBH I activity in the presence of the other enzymes in the complex, and current indirect procedures are cumbersome and inaccurate. The direct procedure described here is highly specific for CBH I and useful for quantifying this enzyme in the range of 0.1 to 0.8 μg/ml.     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Multiplex panels of polymorphic microsatellite loci for two cryptic bat species of the genus Pipistrellus,developed by cross‐species amplification within the family Vespertilionidae

The paper presents multiplex panels of polymorphic microsatellites for two closely related cryptic species Pipistrellus pipistrellus and Pipistrellus pygmaeus. We tested the cross‐species amplification of 34 microsatellite loci, originally developed for five vespertilionid bat species. Ten and nine polymorphic loci in P. pipistrellus (mean number of alleles per locus = 10.5) and P. pygmaeus (8.1), respectively, in three multiplex polymerase chain reactions per species were amplified. All loci can be analysed in a single fragment analysis and can be used as markers to the study of evolution and the ecology of structured populations of socially living bats.     

Structural characterization of cationic DODAB bilayers containing C24:1 β-glucosylceramide

The effect of 5 mol%, 9 mol%, and 16 mol% of C24:1 β-glucosylceramide (βGlcCer) on the structure of cationic DODAB bilayers was investigated by means of differential scanning calorimetry (DSC), electron spin resonance (ESR) spectroscopy and fluorescence microscopy. βGlcCer is completely miscible with DODAB at all fractions tested, since no domains were observed in fluorescence microscopy or ESR spectra. The latter showed that βGlcCer destabilized the gel phase of DODAB bilayers by decreasing the gel phase packing. As a consequence, βGlcCer induced a decrease in the phase transition temperature and cooperativity of DODAB bilayers, as seen in DSC thermograms. ESR spectra also showed that βGlcCer induced an increase in DODAB fluid phase order and/or rigidity. Despite their different structures, a similar effect of loosening the gel phase packing and turning the fluid phase more rigid/organized has also been observed when low molar fractions of cholesterol were incorporated in DODAB bilayers. The structural characterization of mixed membranes made of cationic lipids and glucosylceramides may be important for developing novel immunotherapeutic tools such as vaccine adjuvants.     

Thermal transitions of DMPG bilayers in aqueous solution: SAXS structural studies

Dimyristoylphosphatidylglycerol (DMPG) has been extensively studied as a model for biological membranes, since phosphatidylglycerol is the most abundant anionic phospholipid in prokaryotic cells. At low ionic strengths, this lipid presents a peculiar thermal behavior, with two sharp changes in the light scattering profile, at temperatures named here T(on)(m) and T(off)(m). Structural changes involved in the DMPG thermal transitions are here investigated by small angle X-ray scattering (SAXS), and compared to the results yielded by differential scanning calorimetry (DSC) and electron spin resonance (ESR). The SAXS results show a broad peak, indicating that DMPG is organized in single bilayers, for the range of temperature studied (10-45 degrees C). SAXS intensity shows an unusual effect, starting to decrease at T(on)(m), and presenting a sharp increase at T(off)(m). The bilayer electron density profiles, obtained from modeling the SAXS curves, show a gradual decrease in electron density contrast (attributed to separation between charged head groups) and in bilayer thickness between T(on)(m) and T(off)(m). Results yielded by SAXS, DSC and ESR indicate that a chain melting process starts at T(on)(m), but a complete fluid phase exists only for temperatures above T(off)(m), with structural changes occurring at the bilayer level in the intermediate region.     

Probing DMPG vesicle surface with a cationic aqueous soluble spin label

A small, highly aqueous soluble, deuterated, cationic spin label, 4-trimethylammonium-2,2,6,6-tetramethylpiperidine-d17-1-oxyl iodide (dCAT1), was used to directly monitor the negatively charged DMPG vesicle surface in order to test a recent suggestion (Riske et al., Chem. Phys. Lipids, 89 (1997) 31-44) that alterations in the surface potential accompanied apparent phase transitions observed by light scattering. The temperature dependence of the label partition between the lipid surface and the aqueous medium indicated an increase in the surface potential at the gel to liquid-crystal transition, supporting the previous suggestion. Results at the phase transition occurring at a higher temperature were less definitive. Although some change in the dCAT1 ESR spectra was observed, the interpretation of the phenomena is still rather unclear. DMPG surface potentials were estimated from the dCAT1 partition ratios (surface label moles/total label moles), using a simple two-sites model, where the electrostatic potential is zero everywhere but at the vesicle surface, and the interaction between the spin label and the membrane surface is chiefly electrostatic. The Gouy-Chapman-Stern model predicts surface potentials similar to those observed, although the measured decrease in the surface potential with ionic strength is somewhat steeper than that predicted by the model.