Thymoquinone causes multiple effects,including cell death,on dividing plant cells

Thymoquinone (TQ) is a major constituent of Nigella sativa oil with reported anti-oxidative activity and anti-inflammatory activity in animal cells. It also inhibits proliferation and induces programmed cell death (apoptosis) in human skin cancer cells. The present study sought to detect the influence of TQ on dividing cells of three plant systems and on expression of Bcl2-associated athanogene-like (BAG-like) genes that might be involved during the process of cell death. BAG genes are known for the regulation of diverse physiological processes in animals, including apoptosis, tumorigenesis, stress responses, and cell division. Synthetic TQ at 0.1 mg/mL greatly reduced wheat seed germination rate, whereas 0.2 mg/mL completely inhibited germination. An Evans blue assay revealed moderate cell death in the meristematic zone of Glycine max roots after 1 h of TQ treatment (0.2 mg/mL), with severe cell death occurring in this zone after 2 h of treatment. Light microscopy of TQ-treated (0.2 mg/mL) onion hairy root tips for 1 h revealed anti-mitotic activity and also cell death-associated changes, including nuclear membrane disruption and nuclear fragmentation. Transmission electron microscopy of TQ-treated cells (0.2 mg/mL) for 1 h revealed shrinkage of the plasma membrane, leakage of cell lysate, degradation of cell walls, enlargement of vacuoles and condensation of nuclei. Expression of one BAG-like gene, previously associated with cell death, was induced 20 min after TQ treatment in Glycine max root tip cells. Thus, TQ has multiple effects, including cell death, on dividing plant cells and plants may serve as a useful system to further investigate the mechanisms underlying the response of eukaryotic cells to TQ.     

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds

The syntheses of new nitroimidazole compounds using silicon–[¹⁸F]fluorine chemistry for the potential detection of tumor hypoxia are described. [¹⁸F]silicon-based compounds were synthesized by coupling 2-nitroimidazole with silyldinaphtyl or silylphenyldi-tert-butyl groups and labeled by fluorolysis or isotopic exchange. Dinaphtyl compounds (6, 10) were labeled in 56–71% yield with a specific activity of 45 GBq/μmol, however these compounds ([¹⁸F]7 and [¹⁸F]11) were not stable in plasma. Phenyldi-tert-butyl compounds were labeled in 70% yield with a specific activity of 3 GBq/μmol by isotopic exchange, or in 81% yield by fluorolysis of siloxanes with a specific activity of 45 GBq/μmol. The labeled compound [¹⁸F]18 was stable in plasma and excreted by the liver and kidneys in vivo. In conclusion, the fluorosilylphenyldi-tert-butyl (SiFA) group is more stable in plasma than fluorosilyldiphenyl moiety. Thus, compound [¹⁸F]18 is suitable for further in vivo assessments.     

Isotope‐labeled amyloid‐β does not transmit to the brain in a prion‐like manner after peripheral administration

Findings of early cerebral amyloid‐β deposition in mice after peripheral injection of amyloid‐β‐containing brain extracts, and in humans following cadaveric human growth hormone treatment raised concerns that amyloid‐β aggregates and possibly Alzheimer’s disease may be transmissible between individuals. Yet, proof that Aβ actually reaches the brain from the peripheral injection site is lacking. Here, we use a proteomic approach combining stable isotope labeling of mammals and targeted mass spectrometry. Specifically, we generate ¹³C‐isotope‐labeled brain extracts from mice expressing human amyloid‐β and track ¹³C‐lysine‐labeled amyloid‐β after intraperitoneal administration into young amyloid precursor protein‐transgenic mice. We detect injected amyloid‐β in the liver and lymphoid tissues for up to 100 days. In contrast, injected ¹³C‐lysine‐labeled amyloid‐β is not detectable in the brain whereas the mice incorporate ¹³C‐lysine from the donor brain extracts into endogenous amyloid‐β. Using a highly sensitive and specific proteomic approach, we demonstrate that amyloid‐β does not reach the brain from the periphery. Our study argues against potential transmissibility of Alzheimer’s disease while opening new avenues to uncover mechanisms of pathophysiological protein deposition.     

An oral recombinant vaccine in dogs against Echinococcus granulosus, the causative agent of human hydatid disease: a pilot study

Dogs are the main source of human cystic echinococcosis. An oral vaccine would be an important contribution to control programs in endemic countries. We conducted two parallel experimental trials in Morocco and Tunisia of a new oral vaccine candidate against Echinococcus granulosus in 28 dogs. The vaccine was prepared using two recombinant proteins from adult worms, a tropomyosin (EgTrp) and a fibrillar protein similar to paramyosin (EgA31), cloned and expressed in a live attenuated strain of Salmonella enterica serovar typhimurium.In each country, five dogs were vaccinated with the associated EgA31 and EgTrp; three dogs received only the vector Salmonella; and six dogs were used as different controls. The vaccinated dogs received two oral doses of the vaccine 21 d apart, and were challenged 20 d later with 75,000 living protoscoleces. The controls were challenged under the same conditions. All dogs were sacrificed 26-29 d postchallenge, before the appearance of eggs, for safety reasons.We studied the histological responses to both the vaccine and control at the level of the duodenum, the natural localization of the cestode. Here we show a significant decrease of parasite burden in vaccinated dogs (70% to 80%) and a slower development rate in all remaining worms. The Salmonella vaccine EgA31-EgTrp demonstrated a high efficacy against E. granulosus promoting its potential role in reducing transmission to humans and animals.     

Effects of plant protease inhibitors, oryzacystatin I and soybean Bowman-Birk inhibitor, on the aphid Macrosiphum euphorbiae (Homoptera, Aphididae) and its parasitoid Aphelinus abdominalis (Hymenoptera, Aphelinidae)

Transgenic plants expressing protease inhibitors (PIs) have emerged in recent years as an alternative strategy for pest control. Beneficial insects such as parasitoids may therefore be exposed to these entomotoxins either via the host or by direct exposure to the plant itself. With the objective of assessing the effects of PIs towards aphid parasitoids, bioassays using soybean Bowman-Birk inhibitor (SbBBI) or oryzacystatin I (OCI) on artificial diet were performed on Macrosiphum euphorbiae-Aphelinus abdominalis system. OCI significantly reduced nymphal survival of the potato aphid M. euphorbiae and prevented aphids from reproducing. This negative effect was much more pronounced than with other aphid species. On the contrary, SbBBI did not affect nymphal viability but significantly altered adult demographic parameters. Enzymatic inhibition assays showed that digestive proteolytic activity of larvae and adults of Aphelinus abdominalis predominantly relies on serine proteases and especially on chymotrypsin-like activity. Immunoassays suggested that OCI bound to aphid proteins and accumulated in aphid tissues, whereas SbBBI remained unbound in the gut. Bioassays using M. euphorbiae reared on artificial diets supplemented with both OCI and SbBBI showed a fitness impairment of Aphelinus abdominalis that developed on intoxicated aphids. However, only SbBBI was detected in parasitoid larvae, while no PI could be detected in adult parasitoids that emerged from PI-intoxicated aphids. The potential impact of PI-expressing plants on aphid parasitoids and their combined efficiency for aphid control are discussed.     

Lampbrush W and Z heterochromosome characterization with a monoclonal antibody and heat-induced chromosomal markers in the newtPleurodeles waltl: W chromosome plays a role in female sex determination

Two subsets of lateral loops scattered on lampbrush chromosomes of the newtPleurodeles waltl were characterized. One group was identified by labelling with a monoclonal antibody (A1). The second group was identified by the ability of the loops to be induced by heat treatment. Three loops of each subset were mapped on a short region of the two homologues of lampbrush bivalent IV. These regions appear to be heteromorphic because the six loops are always heterozygous. Five loops are found on one homologue and the sixth on the partner. The distribution of these markers in phenotypic females corresponding to the three sexual genotypes ZW, WW and ZZ shows an absolute correlation of the five loop group with the W chromosome and of the other loop with the Z chromosome. Therefore the heteromorphic regions of the homologues correspond to the differential segments of the heterochromosomes. The identification of a trisomic ZZW female suggests that the W chromosome bears female sex determinants. Furthermore the results show that heat induces loop development and that under normal conditions giant loop development is influenced by the sexual genotype.