A new killing assay with the Caenorhabditis elegans PX627 mutant to assess the virulence of uropathogenic Escherichia coli strains.

The nematode Caenorhabditis elegans (C. elegans) is a prime invertebrate host model for studying uropathogenic Escherichia coli (UPEC) pathogenesis. The aim of this work was to develop a new C. elegans killing assay based on feeding bacteria by the nematode throughout its life from the egg. With this model, the lifespan of C. elegans rrf-3, temperature-sterile, mutant, and PX627, auxin-inducible infertile, mutant fed UPEC strains, was compared. The behavior of three clinical UPEC strains and the non-pathogenic Escherichia coli OP50 strain was analyzed. Survival curves were generated by the Kaplan-Meier method and compared by the log-rank test over 10 days of follow-up. There was no significant difference between the survival curves obtained with each of the two C. elegans mutants (PX627 and rrf-3) fed with each of the strains of E. coli (OP50, G1722, G1473 or ER41). The UPEC strains were classified according to their virulence in vivo in the C. elegans PX627 mutant. The most virulent strain was ER41 which harbored the virulence genes fimA, papC and hlyA, expressed hemolysis in vitro and showed no antibiotic resistance. The least virulent strain was G1722 which only harbored the two adhesion factor genes, was not hemolytic and was resistant to multiple antibiotics. The C. elegans PX627 mutant fed with UPEC bacteria from the egg stage is a simple and inexpensive invertebrate animal model for assessing the in vivo virulence of different strains. The early exposure of C. elegans to pathogenic bacteria at the egg stage, without the need to change the incubation temperature, is an advantage over previously described C. elegans killing assays.

Does unsaponifiable fraction of grape seed oil attenuate nitric oxide production, oxidant and cytotoxicity activities.

Triterpenoids, tocopherols, and phytosterols presented in unsaponifiable fraction of grape seed oil have several beneficial effects comprising antioxidant, anti-inflammatory, and antitumor capacities. In this study, the unsaponifiable fraction of three Tunisian grape seed varieties (Vitis vinifera L.), namely Merlot, Carignan, and Syrah, was investigated. The identified compounds were two triterpenic compounds (ß-amyrin, lanosterol), six phytosterols (campesterol, ∆7 -avenasterol, stigmasterol, ß-sitosterol, ß-sitostanol, cholesterol), and three tocopherols (α, ß, and γ tocopherols). The unsaponifiable fraction had significant protection against oxidative damage by modulating NO production and antioxidant activity. Statistical analysis showed the presence of three clusters of varieties associated to specific composition patterns. These results clearly demonstrated that unsaponifiable fraction profiles of grape species could be considered as a complementary data to the existing taxonomic evidence and classification purposes. PRACTICAL APPLICATIONS: Recently, much attention has been focused to substitute artificial antioxidant by others originating from natural products as plant matrices. The unsaponifiable fraction of grape seed oils is an interesting source of bioactive components like phytosterols, tocopherols, triterpenoids, and other various components. These components are known for their antitumor, anti-inflammatory and antioxidant capacities.