Malaria parasites require TLR9 signaling for immune evasion by activating regulatory T cells

Malaria is still a life-threatening infectious disease that continues to produce 2 million deaths annually. Malaria parasites have acquired immune escape mechanisms and prevent the development of sterile immunity. Regulatory T cells (Tregs) have been reported to contribute to immune evasion during malaria in mice and humans, suggesting that activating Tregs is one of the mechanisms by which malaria parasites subvert host immune systems. However, little is known about how these parasites activate Tregs. We herein show that TLR9 signaling to dendritic cells (DCs) is crucial for activation of Tregs. Infection of mice with the rodent malaria parasite Plasmodium yoelii activates Tregs, leading to enhancement of their suppressive function. In vitro activation of Tregs requires the interaction of DCs with parasites in a TLR9-dependent manner. Furthermore, TLR9(-/-) mice are partially resistant to lethal infection, and this is associated with impaired activation of Tregs and subsequent development of effector T cells. Thus, malaria parasites require TLR9 to activate Tregs for immune escape.     

Interleukin-1 stimulates glutamate uptake in glial cells by accelerating membrane trafficking of Na+/K+-ATPase via actin depolymerization

Interleukin-1 (IL-1) is a mediator of brain injury induced by ischemia, trauma, and chronic neurodegenerative disease. IL-1 also has a protective role by preventing neuronal cell death from glutamate neurotoxicity. However, the cellular mechanisms of IL-1 action remain unresolved. In the mammalian retina, glutamate/aspartate transporter (GLAST) is a Na(+)-dependent, major glutamate transporter localized to Müller glial cells, and loss of GLAST leads to glaucomatous retinal degeneration (T. Harada, C. Harada, K. Nakamura, H. A. Quah, A. Okumura, K. Namekata, T. Saeki, M. Aihara, H. Yoshida, A. Mitani, and K. Tanaka, J. Clin. Investig. 117:1763-1770, 2007). We show here that IL-1 increases glutamate uptake in Müller cells by a mechanism that involves increased membrane Na(+)/K(+)-ATPase localization, required for counteracting the Na(+)-glutamate cotransport. IL-1 activated the p38 mitogen-activated protein kinase (MAPK)/capase 11 pathway, which destabilizes the actin cytoskeleton allowing Na(+)/K(+)-ATPase membrane redistribution. Furthermore, pretreatment with IL-1 protected retinal neurons from glutamate neurotoxicity through p38 MAPK signaling. Our observations suggested that IL-1 acts as a potential neuroprotective agent by modulating the functions of the glia-neuron network.     

Study of thermodynamic parameters for solubilization of plant sterol and stanol in bile salt micelles

We investigated the difference between the molecular structures of plant sterols and stanols that affect the solubilization of cholesterol in bile salt micelles (in vitro study). First, the aqueous solubility of beta-sitosterol, beta-sitostanol, and campesterol was determined by considering the specific radioactivity by using a fairly small quantity of each radiolabeled compound. The order of their aqueous solubilities was as follows: cholesterol > campesterol > beta-sitostanol > beta-sitosterol. The maximum solubility of cholesterol and the above mentioned sterol/stanol in sodium taurodeoxycholate and sodium taurocholate solutions (single solubilizate system) was measured. Moreover, the preferential solubilization of cholesterol in bile salt solutions was systematically studied by using different types of plant sterols/stanols. The solubilization results showed that the cholesterol-lowering effect was similar for sterols and stanol. Thermodynamic analysis was applied to these experimental results. The Gibbs energy change (Delta G degrees ) for the solubilization of plant sterols/stanols showed a negative value larger than that for cholesterol.     

The importance of conserved amino acid residues in p94 protease sub-domain IIb and the IS2 region for constitutive autolysis

p94/calpain 3, a skeletal muscle-specific member of calpain protease family, is characterized by apparent Ca(2+)-independence during exhaustive autolysis and concomitant proteolysis of non-self substrates. The purpose of our study was to comprehensively profile the structural basis of p94 enabling activation in the cytosol without an extra Ca(2+). Ca(2+)-dependent p94 mutants were screened using "p94-trapping", which is an application of yeast genetic reporter system called "proteinase-trapping". Several amino acids were revealed as critical for apparent Ca(2+)-independent p94 activity. These results highlight the importance of conserved amino acids in domain IIb as well as in the p94-specific IS2 region.     

Two-gene systems of vernalization requirement and narrow-sense earliness in einkorn wheat.

The genetic segregation of the heading trait was analyzed using a recombinant inbred line (RIL) of einkorn wheat, RILWA-1, derived from cultivated Triticum monococcum L., and wild-type T. boeoticum Boiss. The latency to heading was examined in 115 lines under controlled environmental conditions, as well as in the field, and the degrees of narrow-sense earliness and vernalization requirement were evaluated for quantitative trait locus (QTL) analysis. Single-marker analysis using 107 RFLP markers segregating in RILWA-1 detected 20 linking markers for heading factors. In all marker loci, the alleles for early heading were conferred by T. monococcum. In interval analysis of chromosome 5Am, two vernalization genes, Vrn-Am1 and Vrn-Am2, were precisely mapped to the Xcdo504-Xpsr426 interval on the central region of the long arm and to the Xwg114-Xwec87 interval on its distal region, respectively. Interval analysis also showed that two genes for narrow-sense earliness, designated Nse-3Am and Nse-5Am, were located on chromosome 3Am and 5Am, respectively. It was noticed that heading time in the field was determined mainly by Nse-3Am, suggesting that narrow-sense earliness is critical for heading in the field in einkorn wheat.     

2'-O,4'-C-ethylene-bridged nucleic acids (ENA): highly nuclease-resistant and thermodynamically stable oligonucleotides for antisense drug.

To develop antisense oligonucleotides, novel nucleosides, 2'-O,4'-C-ethylene nucleosides and their corresponding phosphoramidites, were synthesized as building blocks. The 1H NMR analysis showed that the 2'-O,4'-C-ethylene linkage of these nucleosides restricts the sugar puckering to the N-conformation as well as the linkage of 2'-O,4'-C-methylene nucleosides which are known as bridged nucleic acids (BNA) or locked nucleic acids (LNA). The ethylene-bridged nucleic acids (ENA) showed a high binding affinity for the complementary RNA strand (DeltaT(m)=+5.2 degrees C/modification) and were more nuclease-resistant than natural DNA and BNA/LNA. These results indicate that ENA have better properties as antisense oligonucleotides than BNA/LNA.     

The mechanism of placental alkaline phosphatase induction in vitro

The mechanism of placental alkaline phosphatase (PLAP) induction by prednisolone in a uterine cervical epidermoid cancer cell line SKG-IIIa was investigated in vitro by enzyme-cytochemistry, enzyme immunoassay, Northern and Southern blot analysis, and in situ hybridization. Enzyme-cytochemical alkaline phosphatase (ALP) staining and immunoassay revealed increased levels of PLAP (heat-stable ALP) in prednisolone-treated cells. Northern blot analysis and in situ hybridization showed increased amounts of PLAP mRNA. Southern blot analysis indicated that PLAP was not a product of an amplified or rearranged gene. These findings suggest that the induction of PLAP mRNA in SKG-IIIa cells by prednisolone in turn increased the levels of PLAP.     

The giant mycoheterotrophic orchid Erythrorchis altissima is associated mainly with a divergent set of wood‐decaying fungi

The climbing orchid Erythrorchis altissima is the largest mycoheterotroph in the world. Although previous in vitro work suggests that E. altissima has a unique symbiosis with wood‐decaying fungi, little is known about how this giant orchid meets its carbon and nutrient demands exclusively via mycorrhizal fungi. In this study, the mycorrhizal fungi of E. altissima were molecularly identified using root samples from 26 individuals. Furthermore, in vitro symbiotic germination with five fungi and stable isotope compositions in five E. altissima at one site were examined. In total, 37 fungal operational taxonomic units (OTUs) belonging to nine orders in Basidiomycota were identified from the orchid roots. Most of the fungal OTUs were wood‐decaying fungi, but underground roots had ectomycorrhizal Russula. Two fungal isolates from mycorrhizal roots induced seed germination and subsequent seedling development in vitro. Measurement of carbon and nitrogen stable isotope abundances revealed that E. altissima is a full mycoheterotroph whose carbon originates mainly from wood‐decaying fungi. All of the results show that E. altissima is associated with a wide range of wood‐ and soil‐inhabiting fungi, the majority of which are wood‐decaying taxa. This generalist association enables E. altissima to access a large carbon pool in woody debris and has been key to the evolution of such a large mycoheterotroph.