Susceptibility of Phytopathogenic Bacteria to Wheat Purothionins In Vitro

Purothionins are basic polypeptides with antimicrobial properties that are present in the endosperm of wheat and other cereal species. Susceptibility to wheat purothionins among phytopathogenic bacteria of the genera Pseudomonas, Xanthomonas, Agrobacterium, Erwinia, and Corynebacterium has been investigated. Sensitive strains have been found in all of these genera except Agrobacterium (the only strain of A. tumefaciens available proved to be resistant). Minimal inhibitory concentrations (MIC) with partially purified crude purothionins ranged from 1 μg/ml for C. sepedonicum (C.5) to 540 μg/ml for E. amylovora (E.3). Minimal bactericidal concentrations (MBC) were not higher than twice the MIC value, except for C. poinsettiae (C.4) (MBC/MIC = 8). Purothionins α and β, obtained by carboxymethyl-cellulose column chromatography, were tested against P. solanacearum (P.2) and X. phaseoli (X.2); α purothionin was more active than β against X.2, and β more active than α against P.2. This suggests a relationship between polypeptide sequence and specificity of action.     

Conformational comparison of cyclic peptide and pseudopeptide structures with intramolecular hydrogen bonding

An nmr spectral comparison of a model cyclic pentapeptide cyclo(Gly-Pro-Gly-D-Phe-Pro) with an analogous pseudopeptide has been made. The pseudopeptide contains a ψ[CH₂S] amide bond replacement at the only amide linkage that, in the model, is not involved in an intramolecular hydrogen bond. Both proton and carbon-13 nmr spectral evidence confirms the retention of β- and γ-turns in the pseudopeptide in chloroform. Characteristic chemical shifts, temperature dependence, and glycine α-resonances support this interpretation. However, evidence of a more flexible conformation involving cis–trans proline isomerism is seen on addition of dimethylsulfoxide.     

The voltage-dependent anion channel is the target for a new class of inhibitors of the mitochondrial permeability transition pore

The relevance of the mitochondrial permeability transition pore (PTP) in Ca2+ homeostasis and cell death has gained wide attention. Yet, despite detailed functional characterization, the structure of this channel remains elusive. Here we report on a new class of inhibitors of the PTP and on the identification of their molecular target. The most potent among the compounds prepared, Ro 68-3400, inhibited PTP with a potency comparable to that of cyclosporin A. Since Ro 68-3400 has a reactive moiety capable of covalent modification of proteins, [3H]Ro 68-3400 was used as an affinity label for the identification of its protein target. In intact mitochondria isolated from rodent brain and liver and in SH-SY5Y human neuroblastoma cells, [3H]Ro 68-3400 predominantly labeled a protein of approximately 32 kDa. This protein was identified as the isoform 1 of the voltage-dependent anion channel (VDAC). Both functional and affinity labeling experiments indicated that VDAC might correspond to the site for the PTP inhibitor ubiquinone0, whereas other known PTP modulators acted at distinct sites. While Ro 68-3400 represents a new useful tool for the study of the structure and function of VDAC and the PTP, the results obtained provide direct evidence that VDAC1 is a component of this mitochondrial pore.     

The Fanconi anaemia components UBE2T and FANCM are functionally linked to nucleotide excision repair

The many proteins that function in the Fanconi anaemia (FA) monoubiquitylation pathway initiate replicative DNA crosslink repair. However, it is not clear whether individual FA genes participate in DNA repair pathways other than homologous recombination and translesion bypass. Here we show that avian DT40 cell knockouts of two integral FA genes--UBE2T and FANCM are unexpectedly sensitive to UV-induced DNA damage. Comprehensive genetic dissection experiments indicate that both of these FA genes collaborate to promote nucleotide excision repair rather than translesion bypass to protect cells form UV genotoxicity. Furthermore, UBE2T deficiency impacts on the efficient removal of the UV-induced photolesion cyclobutane pyrimidine dimer. Therefore, this work reveals that the FA pathway shares two components with nucleotide excision repair, intimating not only crosstalk between the two major repair pathways, but also potentially identifying a UBE2T-mediated ubiquitin-signalling response pathway that contributes to nucleotide excision repair.     

Selecting the quality of mule duck fatty liver based on near-infrared spectroscopy

Background

“Foie gras” is produced predominantly in France and about 90% of the commercialized product is obtained from male mule ducks. The melting rate (percentage of fat released during cooking) is the main criterion used to determine the quality of “foie gras”. However, up to now the melting rate could not be predicted without causing liver damage, which means that selection programs could not use this criterion.

Methods

Fatty liver phenotypes were obtained for a population of over 1400 overfed male mule ducks. The phenotypes were based on two types of near-infrared spectra (on the liver surface and on ground liver) in order to predict the melting rate and liver composition (ash, dry matter, lipid and protein contents). Genetic parameters were computed in multiple traits with a “sire-dam” model and using a Gibbs sampling approach.

Results

The estimates for the genetic parameters show that the measured melting rate and the predicted melting rate obtained with two near-infrared spectrometer devices are genetically the same trait: genetic correlations are very high (ranging from +0.89 to +0.97 depending on the mule duck parental line and the spectrometer) and heritabilities are comparable. The predictions based on the spectra of ground liver samples using a laboratory spectrometer correlate with those based on the surface spectra using a portable spectrometer (from +0.83 to +0.95 for dry matter, lipid and protein content) and are particularly high for the melting rate (higher than +0.95). Although less accurate than the predictions obtained using the spectra of ground liver samples, the phenotypic prediction of the melting rate based on surface spectra is sufficiently accurate to be used by “foie gras” processors.

Conclusions

Near-infrared spectrometry is an efficient tool to select liver quality in breeding programs because animals can be ranked according to their liver melting rate without damaging their livers. Thus, these original results will help breeders to select ducks based on the liver melting rate, a crucial criterion that defines the quality of the liver and for which there was previously no accurate predictor.     

Lipid components of aristolochia longa

The hexane extract (non-volatiles) of Aristolochia longa yielded fatty acids, methyl, ethyl, isobutyl and phytyl esters, and polyprenols.