Adventitious shoot regeneration from leaf explants and stem nodes of Lilium

A method for the regeneration of lily plantlets (Lilium spp.) through different morphogenic pathways is described. Plant regeneration was obtained from in vitro cultured leaves of four lily hybrids, cultured on Murashige and Skoog's basal medium supplemented with cytokinins (TDZ and BA) and auxins (NAA and IBA) at different concentrations. Direct shoot regeneration occurred with all tested media for the Asiatic lilies `Elite' and `Pollyanna' and also for the Oriental hybrid `Star Gazer'. Callus developed on TDZ-enriched medium from leaf segments of L. longiflorum cv. `Snow Queen' regenerated by direct organogenesis. This occurred on a medium with auxin/ cytokinin balance which was lower than other genotypes. There were fewer problems of sterilization with leaves from sprouted bulbs than in vitro scale culture. This suggests that the leaf-segments obtained in this way could be an alternative to the scales as a source of material for propagation. A protocol for micropropagation based on bulblets from in vitro shoot-tip-derived stem nodes was also used. The development of pseudo-bulbets is particularly advantageous since it allows for structures characterised by absent or low dormancy. Regenerated shoots have been rooted and successfully acclimatized to greenhouse conditions where they flowered after the second year giving plants with true-to-type shape and colour.     

Peptide-mediated DNA condensation for non-viral gene therapy

The construction of non-viral, virus-like vehicles for gene therapy involves the functionalization of multipartite constructs with nucleic acid-binding, cationic agents. Short basic peptides, alone or as fusion proteins, are appropriate DNA binding and condensing elements, whose incorporation into gene delivery vehicles results in the formation of protein–DNA complexes of appropriate size for cell internalization and intracellular trafficking. We review here the most used cationic peptides for artificial virus construction as well as the recently implemented strategies to control the architecture and biological activities of the resulting nanosized particles.     

Recombinant tumor necrosis factor depresses cytochrome P450-dependent microsomal drug metabolism in mice

The effect of recombinant tumor necrosis factor on liver cytochrome P450 and related drug metabolism enzymes was investigated. Treatment of mice with tumor necrosis factor caused a marked depression of cytochrome P450 and some drug metabolizing enzymes (ethoxycoumarin deethylase and arylhydrocarbon hydroxylase) in the liver and many other organs. This effect was maximal 24-48 h after treatment and was dependent on the dose of tumor necrosis factor administered. Depression of liver drug metabolizing enzymes was also observed in the endotoxin-resistant C3H/HeJ strain of mice, thus ruling out that this effect may be due to minor endotoxin contamination of recombinant tumor necrosis factor. These data indicate that depression of liver drug metabolism might be an important side effect of tumor necrosis factor, and suggest a role for this macrophage product as an endogenous regulator of liver metabolism.     

Selective Enhancement of the Fluorescent Pseudomonad Population After Amending the Recirculating Nutrient Solution of Hydroponically Grown Plants with a Nitrogen Stabilizer

Fluorescent pseudomonads have been associated, via diverse mechanisms, with suppression of root disease caused by numerous fungal and fungal-like pathogens. However, inconsistent performance in disease abatement, after their employment, has been a problem. This has been attributed, in part, to the inability of the biocontrol bacterium to maintain a critical threshold population necessary for sustained biocontrol activity. Our results indicate that a nitrogen stabilizer (N-Serve(R), Dow Agrosciences) selectively and significantly enhanced, by two to three orders of magnitude, the resident population of fluorescent pseudomonads in the amended (i.e., 25 mug ml(-1) nitrapyrin, the active ingredient) and recycled nutrient solution used in the cultivation of hydroponically grown gerbera and pepper plants. Pseudomonas putida was confirmed as the predominant bacterium selectively enhanced. Terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rDNA suggested that N-Serve(R) selectively increased P. putida and reduced bacterial diversity 72 h after application. In vitro tests revealed that the observed population increases of fluorescent pseudomonads were preceded by an early growth suppression of indigenous aerobic heterotrophic bacteria (AHB) population. Interestingly, the fluorescent pseudomonad population did not undergo this decrease, as shown in competition assays. Xylene and 1,2,4-trimethylbenzene (i.e., the inert ingredients in N-Serve(R)) were responsible for a significant percentage of the fluorescent pseudomonad population increase. Furthermore, those increases were significantly higher when the active ingredient (i.e., nitrapyrin) and the inert ingredients were combined, which suggests a synergistic response. P. putida strains were screened for the ability to produce antifungal compounds and for the antifungal activity against Pythium aphanidermatum and Phytophthora capsici. The results of this study suggest the presence of diverse mechanisms with disease-suppressing potential. This study demonstrates the possibility of using a specific substrate to selectively enhance and maintain desired populations of a natural-occurring bacterium such as P. putida, a trait considered to have great potential in biocontrol applications for plant protection.     

Nucleotide sequence of cDNA coding for saporin-6, a type-1 ribosome-inactivating protein from Saponaria officinalis

We have isolated and sequenced partial cDNA clones that encode SO-6, a ribosome-inactivating protein from Saponaria officinalis. A cDNA library was constructed from the leaves of this plant and screened with synthetic oligonucleotide probes representing various portions of the protein. The deduced amino acid sequence shows the signal peptide and a coding region virtually accounting for the entire amino acid sequence of SO-6. The sequence reveals regions of similarity to other ribosome-inactivating proteins, especially in a region of the molecule where critical amino acid residues might participate in the active site.     

Expression, in Escherichia coli, of a soluble human Tumor Necrosis Factor receptor

We have expressed in Escherichia coli a soluble, truncated form of the human 55 kDa Tumor Necrosis Factor (TNF) receptor. For this purpose a plasmid was constructed which contains the extracellular domain of the 55 kDa TNF receptor fused to the coding sequence of the IgG binding domains of protein A from Staphylococcus aureus. The fusion product (TNFR-PA) obtained in E. coli is a soluble protein which bound human TNFα (huTNFα) with high affinity. In ligand-blotting experiments huTNFα bound to a single 52 kDa protein, a molecular mass corresponding to that expected for the monomeric fusion product. In gel filtration experiments binding activity was recovered from fractions that eluted at a volume corresponding to 140–150 kDa. TNFR-PA neutralized huTNFα in an in vitro cytotoxicity assay.     

Constitutive over-expression of two wheat pathogenesis-related genes enhances resistance of tobacco plants to Phytophthora nicotianae

The potential role in plant defence of the two wheat pathogenesis-related proteins of class 4 Wheatwin1 and Wheatwin2, possessing high in vitro antimicrobial activity against several pathogens, was investigated through over-expression of their encoding genes wPR4a and wPR4b in transgenic tobacco plants. Several independent transformants were obtained, expressing high levels of either transgene when analysed by northern and western blotting. Accumulation of the wPR4b-encoded protein Wheatwin2 in the apoplast of transgenic plants was also demonstrated. When homozygous transgenic lines in the T4 generation were tested for increased tolerance to Phytophthora nicotianae, they were found to be significantly more resistant than both the wild type and their isogenic, non-wPR4 transgenic lines. These results suggest that both Wheatwins might have in vivo antimicrobial activity, confirming earlier indications from in vitro assays.     

Effect of the DnaK chaperone on the conformational quality of JCV VP1 virus‐like particles produced in Escherichia coli

Protein nanoparticles such as virus‐like particles (VLPs) can be obtained by recombinant protein production of viral capsid proteins and spontaneous self‐assembling in cell factories. Contrarily to infective viral particles, VLPs lack infective viral genome while retaining important viral properties like cellular tropism and intracellular delivery of internalized molecules. These properties make VLPs promising and fully biocompatible nanovehicles for drug delivery. VLPs of human JC virus (hJCV) VP1 capsid protein produced in Escherichia coli elicit variable hemagglutination properties when incubated at different NaCl concentrations and pH conditions, being optimal at 200 mM NaCl and at pH range between 5.8 and 7.5. In addition, the presence or absence of chaperone DnaK in E. coli cells influence the solubility of recombinant VP1 and the conformational quality of this protein in the VLPs. The hemagglutination ability of hJCV VP1 VLPs contained in E. coli cell extracts can be modulated by buffer composition in the hemagglutination assay. It has been also determined that the production of recombinant hJCV VP1 in E. coli is favored by the absence of chaperone DnaK as observed by Western Blot analysis in different E. coli genetic backgrounds, indicating a proteolysis targeting role for DnaK. However, solubility is highly compromised in a DnaK^? E. coli strain suggesting an important role of this chaperone in reduction of protein aggregates. Finally, hemagglutination efficiency of recombinant VP1 is directly related to the presence of DnaK in the producing cells. © 2014 American Institute of Chemical Engineers Biotechnol. Prog., 30:744–748, 2014     

Structure-based optimization of potent PDK1 inhibitors

In this Letter is described the structure-based design of potent dihydro-pyrazoloquinazolines as PDK1 inhibitors. Starting from low potency HTS hits with the aid of X-ray crystallography and modeling, a medicinal chemistry activity was carried out to improve potency versus PDK1 and selectivity versus CDK2 protein kinase.