Chiral superstructures of insulin amyloid fibrils

Hydrodynamic forces are capable of inducing structural order in dispersed solid phases, and of causing symmetry-breaking when chiral crystals precipitate from an achiral liquid phase. Until it was observed upon vortex-assisted fibrillation of insulin, such behavior had been thought to be confined to few unbiological systems. In this paper we are discussing chiroptical properties of two chiral variants of insulin amyloid, termed +ICD and -ICD, which form during the process of chiral bifurcation in vortexed solutions of aggregating insulin. As conventional measurements of circular dichroism of solid, anisotropic substances are particularly vulnerable to overlapping influences of linear birefringence and linear dichroism, we have employed complementary tools including dedicated universal chiroptical spectrophotometer to rule out such artifacts. We propose that the strong chiroptical properties of +ICD and -ICD insulin fibrils are an aspect of genuine superstructural chirality of amyloid fibrils and of powerful excitonic couplings taking place within them. A comparison of thioflavin T complexes with fibrils formed by insulin and polyglutamic acid suggests that the extrinsic Cotton effect stemming from the level of single twisted dye molecules is weaker, although diagnostically useful, and cannot account for the overall magnitude of ICD of the dye bound to ±ICD insulin amyloid.     

Population genetic structure of Bryde’s whales (<Emphasis Type="Italic">Balaenoptera brydei</Emphasis>) at the inter-oceanic and trans-equatorial levels

Bryde’s whales (Balaenoptera brydei) differ from other typical baleen whale species because they are restricted to tropical and warm temperate waters in major oceans, and frequent trans-equatorial movement has been suggested for the species. We tested this hypothesis by analyzing genetic variation at 17 microsatellite loci (N = 508) and 299 bp of mitochondrial DNA (mtDNA) control region sequences (N = 472) in individuals obtained from the western North Pacific, South Pacific, and eastern Indian Ocean. Combined use of microsatellite and mtDNA markers allowed us to distinguish between contemporary gene flow and ancestral polymorphism and to describe sex-specific philopatry. A high level of genetic diversity was found within the samples. Both nuclear and mtDNA markers displayed similar population structure, indicating a lack of sex-specific philopatry. Spatial structuring was detected using both frequency-based population parameters and individual-based Bayesian approaches. Whales in the samples from different oceanic regions came from genetically distinct populations with evidence of limited gene flow. We observed low mtDNA sequence divergence among populations and a lack of concordance between geographic and phylogenetic position of mtDNA haplotypes, suggesting recent separation of populations rather than frequent trans-equatorial and inter-oceanic movement. We conclude that current gene flow between Bryde’s whale populations is low and that effective management actions should treat them as separate entities to ensure continued existence of the species.     

Susceptibility to T cell-mediated injury in immune complex disease is linked to local activation of renin-angiotensin system: the role of NF-AT pathway

FcR provides a critical link between ligands and effector cells in immune complex diseases. Emerging evidence reveals that angiotensin (Ang)II exerts a wide variety of cellular effects and contributes to the pathogenesis of inflammatory diseases. In anti-glomerular basement membrane Ab-induced glomerulonephritis (GN), we have previously noted that FcR-deficient mice (gamma(-/-)) surviving from lethal initial damage still developed mesangial proliferative GN, which was drastically prevented by an AngII type 1 receptor (AT1) blocker. We further examined the mechanisms by which renin-Ang system (RAS) participates in this immune disease. Using bone marrow chimeras between gamma(-/-) and AT1(-/-) mice, we found that glomerular injury in gamma(-/-) mice was associated with CD4(+) T cell infiltration depending on renal AT1-stimulation. Based on findings in cutaneous delayed-type hypersensitivity, we showed that AngII-activated renal resident cells are responsible for the recruitment of effector T cells. We next examined the chemotactic activity of AngII-stimulated mesangial cells, as potential mechanisms coupling RAS and cellular immunity. Chemotactic activity for T cells and Th1-associated chemokine (IFN-gamma-inducible protein-10 and macrophage-inflammatory protein 1alpha) expression was markedly reduced in mesangial cells from AT1(-/-) mice. Moreover, this activity was mainly through calcineurin-dependent NF-AT. Although IFN-gamma-inducible protein-10 was NF-kappaB-dependent, macrophage-inflammatory protein 1alpha was dominantly regulated by NF-AT. Furthermore, AT1-dependent NF-AT activation was observed in injured glomeruli by Southwestern histochemistry. In conclusion, our data indicate that local RAS activation, partly via the local NF-AT pathway, enhances the susceptibility to T cell-mediated injury in anti-glomerular basement membrane Ab-induced GN. This novel mechanism affords a rationale for the use of drugs interfering with RAS in immune renal diseases.     

Two replication regions in the pJM1 virulence plasmid of the marine pathogen Vibrio anguillarum

Vibrio anguillarum is a fish pathogen that causes vibriosis, a serious hemorrhagic septicemia, in wild and cultured fish. Many serotype O1 strains of this bacterium harbor the 65kb plasmid pJM1 carrying the majority of genes encoding the siderophore anguibactin iron transport system that is one of the most important virulence factors of this bacterium. We previously identified a replication region of the pJM1 plasmid named ori1. In this work we determined that ori1 can replicate in Escherichia coli and that the chromosome-encoded proteins DnaB, DnaC and DnaG are essential for its replication whereas PolI, IHF and DnaA are not required. The copy number of the pJM1 plasmid is 1-2, albeit cloned smaller fragments of the ori1 region replicate with higher copy numbers in V. anguillarum while in E. coli we did not observe an obvious difference of the copy numbers of these constructs which were all high. Furthermore, we were able to delete the ori1 region from the pJM1 plasmid and identified a second replication region in pJM1 that we named ori2. This second replication region is located on ORF25 that is within the trans-acting factor (TAFr) region, and showed that it can only replicate in V. anguillarum.     

Direct bioethanol production from brown macroalgae by co-culture of two engineered Saccharomyces cerevisiae strains

A co-culture platform for bioethanol production from brown macroalgae was developed, consisting of two types of engineered Saccharomyces cerevisiae strains; alginate- and mannitol-assimilating yeast (AM1), and cellulase-displaying yeast (CDY). When the 5% (w/v) brown macroalgae Ecklonia kurome was used as the sole carbon source for this system, 2.1 g/L of ethanol was produced, along with simultaneous consumption of alginate, mannitol, and glucans.     

Synthesis of modified siRNA bearing C-5 polyamine-substituted pyrimidine nucleoside in their 3'-overhang regions and its RNAi activity

Short interfering RNA (siRNA) induces specific gene silencing by the RNA interference (RNAi) pathway. Nucleosides in the 3′-overhang regions of siRNAs were replaced with 5-bis(aminoethyl)aminoethylcarbamoylmethyl-2′-deoxyuridine or thymidine. siRNA bearing modified nucleoside was more active in silencing the gene expression of hepatocyte nuclear factor 4α (HNF4α) compared with siRNA bearing thymidine.     

Association of plasma viral RNA load with prognosis in cats naturally infected with feline immunodeficiency virus

We measured the quantity of plasma feline immunodeficiency virus (FIV) RNA using a real-time sequence detecting system. Plasma viral RNA load was shown to correlate with the clinical stage, survival time, and disease progression in naturally FIV-infected cats. The present study indicates that the plasma viral RNA load can be used as a clinical marker representing the impairment of the immune system and predicting the clinical outcome in FIV-infected cats.