Species‐specific microsatellite loci for the European squid (Loligo vulgaris)

A microsatellite dinucleotide‐enriched library was obtained from the European squid (Loligo vulgaris) and five species‐specific dinucleotide markers were optimized. These markers are highly polymorphic with average expected heterozygosity ranging from 0.706 to 0.927 and allele number ranging from 7 to 17. This set of primers is suitable for population genetic studies.     

The nitrite reductase gene of Pseudomonas aeruginosa: Effect of growth conditions on the expression and construction of a mutant by gene disruption

Abstract The expression of nitrite reductase has been tested in a wild-type strain of Pseudomonas aeruginosa (Pao1) as a function of nitrate concentration under anaerobic and aerobic conditions. Very low levels of basal expression are shown under non-denitrifying conditions (i.e. absence of nitrate, in both aerobic and anaerobic conditions); anaerobiosis is not required for high levels of enzyme production in the presence of nitrate. A Pseudomonas aeruginosa strain, mutated in the nitrite reductase gene, has been obtained by gene replacement. This mutant, the first of this species described up to now, is unable to grow under anaerobic conditions in the presence of nitrate. The anaerobic growth can be restored by complementation with the wild-type gene.     

Synthetic prions with novel strain-specified properties

Prions are infectious proteins that possess multiple self-propagating structures. The information for strains and structural specific barriers appears to be contained exclusively in the folding of the pathological isoform, PrP^Sc. Many recent studies determined that de novo prion strains could be generated in vitro from the structural conversion of recombinant (rec) prion protein (PrP) into amyloidal structures. Our aim was to elucidate the conformational diversity of pathological recPrP amyloids and their biological activities, as well as to gain novel insights in characterizing molecular events involved in mammalian prion conversion and propagation. To this end we generated infectious materials that possess different conformational structures. Our methodology for the prion conversion of recPrP required only purified rec full-length mouse (Mo) PrP and common chemicals. Neither infected brain extracts nor amplified PrP^Sc were used. Following two different in vitro protocols recMoPrP converted to amyloid fibrils without any seeding factor. Mouse hypothalamic GT1 and neuroblastoma N2a cell lines were infected with these amyloid preparations as fast screening methodology to characterize the infectious materials. Remarkably, a large number of amyloid preparations were able to induce the conformational change of endogenous PrP^C to harbor several distinctive proteinase-resistant PrP forms. One such preparation was characterized in vivo habouring a synthetic prion with novel strain specified neuropathological and biochemical properties.     

Synthesis and biological evaluation of new conformationally biased integrin ligands based on a tetrahydroazoninone scaffold

The synthesis of new conformationally biased cyclic pentapeptides, incorporating the RGD sequence, and built around a tetrahydroazoninone scaffold, is reported. They exhibit interesting activity towards integrin alphaVbeta3 and a remarkable selectivity in comparison with integrin alphaVbeta5.     

Mitochondrial bioenergetics in aging

Mitochondria are strongly involved in the production of reactive oxygen species, considered as the pathogenic agent of many diseases and of aging. The mitochondrial theory of aging considers somatic mutations of mitochondrial DNA induced by oxygen radicals as the primary cause of energy decline; experimentally, complex I appears to be mostly affected and to become strongly rate limiting for electron transfer. Mitochondrial bioenergetics is also deranged in human platelets upon aging, as shown by the decreased Pasteur effect (enhancement of lactate production by respiratory chain inhibition). Cells counteract oxidative stress by antioxidants; among lipophilic antioxidants, coenzyme Q is the only one of endogenous biosynthesis. Exogenous coenzyme Q, however, protects cells from oxidative stress by conversion into its reduced antioxidant form by cellular reductases.     

Cyclo(His-Pro) up-regulates heme oxygenase 1 via activation of Nrf2-ARE signalling

Paraquat (1,1'-dimethyl-4,4'-bipyridinium), a widely used non-selective herbicide, is a redox cycling agent with adverse effects on dopamine systems. Epidemiological data have shown that exposure to paraquat is one of the several risk factors for Parkinson's disease. We have already shown that cyclo(His-Pro), an endogenous cyclic dipeptide produced by the cleavage of the thyrotropin releasing hormone, has a cytoprotective effect through a mechanism involving Nrf2 activation that decreases production of reactive oxygen species and increases glutathione synthesis. Using primary neuronal cultures and PC12 cells as targets of paraquat neurotoxicity, we addressed whether and how cyclo(His-Pro) causes cellular protective response against paraquat-mediated cell death. We found that cyclo(His-Pro) attenuated reactive oxygen species production, and prevented glutathione depletion by up-regulating Nrf2 gene expression, triggering its nuclear accumulation and activating the expression of heme oxygenase1. These protective effects were abolished by RNA interference-mediated Nrf2 knock down whereas were unaffected by RNA interference-mediated Keap1 knock down. Inhibition of heme oxygenase activity decreased cyclo(His-Pro)-induced neuroprotection. These results suggest that cyclo(His-Pro), acting as a selective activator of the brain modulable Nrf2 pathway, may be a promising candidate as neuroprotective agent that act through induction of phase II genes.     

Mutant PrP suppresses glutamatergic neurotransmission in cerebellar granule neurons by impairing membrane delivery of VGCC α(2)δ-1 Subunit

How mutant prion protein (PrP) leads to neurological dysfunction in genetic prion diseases is unknown. Tg(PG14) mice synthesize a misfolded mutant PrP which is partially retained in the neuronal endoplasmic reticulum (ER). As these mice age, they develop ataxia and massive degeneration of cerebellar granule neurons (CGNs). Here, we report that motor behavioral deficits in Tg(PG14) mice emerge before neurodegeneration and are associated with defective glutamate exocytosis from granule neurons due to impaired calcium dynamics. We found that mutant PrP interacts with the voltage-gated calcium channel α(2)δ-1 subunit, which promotes the anterograde trafficking of the channel. Owing to ER retention of mutant PrP, α(2)δ-1 accumulates intracellularly, impairing delivery of the channel complex to the cell surface. Thus, mutant PrP disrupts cerebellar glutamatergic neurotransmission by reducing the number of functional channels in CGNs. These results link intracellular PrP retention to synaptic dysfunction, indicating new modalities of neurotoxicity and potential therapeutic strategies.