Recent developments in prion disease research: diagnostic tools and in vitro cell culture models

After prion infection, an abnormal isoform of prion protein (PrP(Sc)) converts the cellular isoform of prion protein (PrP(C)) into PrP(Sc). PrP(C)-to-PrP(Sc) conversion leads to PrP(Sc) accumulation and PrP(C) deficiency, contributing etiologically to induction of prion diseases. Presently, most of the diagnostic methods for prion diseases are dependent on PrP(Sc) detection. Highly sensitive/accurate specific detection of PrP(Sc) in many different samples is a prerequisite for attempts to develop reliable detection methods. Towards this goal, several methods have recently been developed to facilitate sensitive and precise detection of PrP(Sc), namely, protein misfolding cyclic amplification, conformation-dependent immunoassay, dissociation-enhanced lanthanide fluorescent immunoassay, capillary gel electrophoresis, fluorescence correlation spectroscopy, flow microbead immunoassay, etc. Additionally, functionally relevant prion-susceptible cell culture models that recognize the complexity of the mechanisms of prion infection have also been pursued, not only in relation to diagnosis, but also in relation to prion biology. Prion protein (PrP) gene-deficient neuronal cell lines that can clearly elucidate PrP(C) functions would contribute to understanding of the prion infection mechanism. In this review, we describe the trend in recent development of diagnostic methods and cell culture models for prion diseases and their potential applications in prion biology.     

Catalytic pyrolysis of cellulose in sulfolane with some acidic catalysts

Catalytic pyrolysis of cellulose in sulfolane (tetramethylene sulfone) with sulfuric acid or polyphosphoric acid gave levoglucosenone, furfural, and 5-hydroxymethyl furfural (5-HMF) up to 42.2%, 26.9%, and 8.8% (as mol% yield based on the glucose unit), respectively. Pyrolysis behaviors of the intermediates indicated the conversion pathways, and the conversion: levoglucosenone → furfural was found to require water. The control of the water content in the pyrolysis medium was quite effective in controlling the product selectivity between levoglucosenone and furfural: mild vacuum conditions to remove the product water dramatically enhanced the levoglucosenone yield, while steam distillation conditions increased the furfural and 5-HMF yields.     

Microbial community profiles in intercellular fluid of rice

Plants harbor microorganisms that are thought to stimulate plant defense systems or promote plant growth. Individual species in these intercellular microbial communities are often not sufficiently abundant to be easily described, although some endophytic microorganisms amenable to culture have been characterized. To better understand the microbial population of plants, we collected intercellular fluid (IF) from leaf blades and sheaths of rice and subsequently isolated DNA from the IF. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S and 18S rDNA fragments amplified from IF DNA by PCR indicated that these band patterns were distinguishable from those of a leaf surface-wash fluid (SF). Analysis of a set of rDNA fragments amplified from IF DNA of rice with different genotypes, paddies or growth stages for the primary survey of overall microbial community in the IF suggested that this approach is suitable for analyzing microbial diversity in the IF from various plant samples. Actually, comparative analysis of amplified rDNA fragments of rice and other five plant species indicated that the microbial diversity in IF is likely to vary substantially among plant species. We can also use sequence analysis of 16S rDNA fragments amplified from rice IF DNA to identify species including unculturable bacteria and proteobacteria and Xanthomonas and 18S rDNA fragments to identify Tilletiaria anomala, Tilletia iowensis, Ustilago maydis and unculturable eukaryotes. Thus, IF DNA analysis seems to be a good tool to further study the microbial ecology of plants.     

Green-leaf-derived C6-aroma compounds with potent antibacterial action that act on both Gram-negative and Gram-positive bacteria

All eight C6-aliphatic alcohol and aldehyde compounds in naturally occurring green leaves showed bacteriostatic effects against Staphylococcus aureus IFO 12732, methicillin-resistant S. aureus, Escherichia coli IFO 3301, E. coli O157:H7, and Salmonella enteritidis, with bacteriostatic activities of less than 12.5 microg mL(-1). In this study, the susceptibility of Gram-positive bacteria tested was observed to be greater than that of Gram-negative bacteria. The bactericidal action of the aldehyde compounds was found to be much stronger than that of the alcohol compounds under both liquid and gaseous conditions. The most effective compound was (3E)-hexenal at concentrations of 0.1 and 1 microg mL(-1), which killed 2.1 x 10(5) cfu mL(-1) of S. aureus IFO 12732 and 1.4 x 10(5) cfu mL(-1) of E. coli IFO 3301, respectively, by direct contact with the compound. Lethality of (3E)-hexenal against S. aureus IFO 12732 and E. coli IFO 3301 was also observed as a result of gaseous contact at concentrations of 3 and 30 microg mL(-1), respectively. The bactericidal effects of 30 microg mL(-1) (3E)-hexenal were thoroughly maintained throughout periods of 2 days and 1 day against S. aureus IFO 12732 and E. coli IFO 3301, respectively, by a complex formation with alpha-cyclodextrin.     

Variations in nitrogen uptake and nitrate-nitrogen concentration among sorghum groups

Nitrogen uptake and nitrate-N concentration in forage sorghums, which are related to ground water pollution or feed quality under conditions of crop fertilization by only animal wastes, were examined. Seventy-four genotypes of sorghum and Sudan grass were tested. They were classified into 4 groups; grain type and dual purpose type sorghums (6 and 13 genotypes, respectively, Sorghum bicolor Moench), sorgo type sorghum (21, S. bicolor), Sudan type sorghum (22, S. bicolor × S. sudanense (Piper) Stapf), Sudan grass (12, S. sudanense). There was a strong correlation between dry matter (DM) yield and N uptake, with the sorgo type producing the highest DM matter yield and showing the highest N uptake. Nitrate-N, which causes nitrate poisoning of ruminants, was detected mostly in the stem of all the genotypes. The nitrate-N concentration based on DM could be calculated accurately by multiplying the nitrate-N concentration of stem on a fresh matter basis by the DM partitioning ratio of stem divided by the DM concentration of stem. The grain type and the dual purpose type of sorghums with dry stem showed the lowest nitrate-N concentration because these plants had a lower DM partitioning ratio of stem and higher DM concentration of stem. Sudan grass and Sudan type sorghum with the genetic background of Sudan grass showed higher nitrate-N concentrations owing to their ability to accumulate nitrate-N.     

Redox Status and Neuro Inflammation Indexes in Cerebellum and Motor Cortex of Wistar Rats Supplemented with Natural Sources of Omega-3 Fatty Acids and Astaxanthin: Fish Oil,Krill Oil,and Algal Biomass

Health authorities worldwide have consistently recommended the regular consumption of marine fishes and seafood to preserve memory, sustain cognitive functions, and prevent neurodegenerative processes in humans. Shrimp, crabs, lobster, and salmon are of particular interest in the human diet due to their substantial provision of omega-3 fatty acids (n-3/PUFAs) and the antioxidant carotenoid astaxanthin (ASTA). However, the optimal ratio between these nutraceuticals in natural sources is apparently the key factor for maximum protection against most neuro-motor disorders. Therefore, we aimed here to investigate the effects of a long-term supplementation with (n-3)/PUFAs-rich fish oil, ASTA-rich algal biomass, the combination of them, or krill oil (a natural combination of both nutrients) on baseline redox balance and neuro-inflammation indexes in cerebellum and motor cortex of Wistar rats. Significant changes in redox metabolism were only observed upon ASTA supplementation, which reinforce its antioxidant properties with a putative mitochondrial-centered action in rat brain. Krill oil imposed mild astrocyte activation in motor cortex of Wistar rats, although no redox or inflammatory index was concomitantly altered. In summary, there is no experimental evidence that krill oil, fish oil, oralgal biomass (minor variation), drastically change the baseline oxidative conditions or the neuro-inflammatory scenario in neuromotor-associated rat brain regions.