Hemagglutinins (lectins) in fruit bodies of Japanese higher fungi

Extracts from fruit bodies of 110 species of Japanese fungi were examined with trypsinized human and rabbit erythrocytes. More than 80% of the extracts showed the hemagglutination activities, a higher proportion than reported previously. Over half of species that had been reported to be inactive exhibited hemagglutination. Among them, some extracts showed human blood group specific-hemagglutination; A-specific,Panellus serotinus, Psathyrella piluliformis, Cantharellus cibarius andStropharia rugosoannulata; B-, O-specific,Gyroporus castaneus andPanellus stypticus; and Ospecific,Linderia bicolumnata andPhallus impudicus. Twenty-one species were reactive toward only rabbit erythrocytes. Several species exhibited very high hemagglutination activity. The results suggested that some of these Japanese fungi would be promising sources of lectins.     

Non-neutralizing antibodies targeting the immunogenic regions of HIV-1 envelope reduce mucosal infection and virus burden in humanized mice

Antibodies are principal immune components elicited by vaccines to induce protection from microbial pathogens. In the Thai RV144 HIV-1 vaccine trial, vaccine efficacy was 31% and the sole primary correlate of reduced risk was shown to be vigorous antibody response targeting the V1V2 region of HIV-1 envelope. Antibodies against V3 also were inversely correlated with infection risk in subsets of vaccinees. Antibodies recognizing these regions, however, do not exhibit potent neutralizing activity. Therefore, we examined the antiviral potential of poorly neutralizing monoclonal antibodies (mAbs) against immunodominant V1V2 and V3 sites by passive administration of human mAbs to humanized mice engrafted with CD34+ hematopoietic stem cells, followed by mucosal challenge with an HIV-1 infectious molecular clone expressing the envelope of a tier 2 resistant HIV-1 strain. Treatment with anti-V1V2 mAb 2158 or anti-V3 mAb 2219 did not prevent infection, but V3 mAb 2219 displayed a superior potency compared to V1V2 mAb 2158 in reducing virus burden. While these mAbs had no or weak neutralizing activity and elicited undetectable levels of antibody-dependent cellular cytotoxicity (ADCC), V3 mAb 2219 displayed a greater capacity to bind virus- and cell-associated HIV-1 envelope and to mediate antibody-dependent cellular phagocytosis (ADCP) and C1q complement binding as compared to V1V2 mAb 2158. Mutations in the Fc region of 2219 diminished these effector activities in vitro and lessened virus control in humanized mice. These results demonstrate the importance of Fc functions other than ADCC for antibodies without potent neutralizing activity.     

Excitation relaxation dynamics and energy transfer in fucoxanthin–chlorophyll a/c-protein complexes,probed by time-resolved fluorescence

In algae, light-harvesting complexes contain specific chlorophylls (Chls) and keto-carotenoids; Chl a, Chl c, and fucoxanthin (Fx) in diatoms and brown algae; Chl a, Chl c, and peridinin in photosynthetic dinoflagellates; and Chl a, Chl b, and siphonaxanthin in green algae. The Fx–Chl a/c-protein (FCP) complex from the diatom Chaetoceros gracilis contains Chl c₁, Chl c₂, and the keto-carotenoid, Fx, as antenna pigments, in addition to Chl a. In the present study, we investigated energy transfer in the FCP complex associated with photosystem II (FCPII) of C. gracilis. For these investigations, we analyzed time-resolved fluorescence spectra, fluorescence rise and decay curves, and time-resolved fluorescence anisotropy data. Chl a exhibited different energy forms with fluorescence peaks ranging from 677 nm to 688 nm. Fx transferred excitation energy to lower-energy Chl a with a time constant of 300 fs. Chl c transferred excitation energy to Chl a with time constants of 500–600 fs (intra-complex transfer), 600–700 fs (intra-complex transfer), and 4–6 ps (inter-complex transfer). The latter process made a greater contribution to total Chl c-to-Chl a transfer in intact cells of C. gracilis than in the isolated FCPII complexes. The lower-energy Chl a received excitation energy from Fx and transferred the energy to higher-energy Chl a. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: Keys to Produce Clean Energy.     

Palmitoylation of the canine histamine H2 receptor occurs at Cys(305) and is important for cell surface targeting.

To determine the presence and functional role of the histamine H2 receptor (H2R) palmitoylation, a receptor with a Cys(305) to Ala (A(305) receptor) mutation was generated. Wild-type (WT) and A(305) receptors were tagged at their N-termini with a hemagglutinin (HA) epitope. WT, but not A(305), receptors incorporated [3H]palmitate by metabolic labeling, indicating that the H2R is palmitoylated at Cys(305). Immunocytochemistry of WT and A(305) receptors expressed in COS7 cells revealed WT receptors to be distributed at the plasma membrane, while the majority of A(305) receptors were localized intracellularly with only a small portion being at the plasma membrane. However, the affinity of the A(305) receptor for tiotidine was comparable to that of the WT receptor. In addition, when the amounts of cell surface receptors as determined by anti-HA antibody binding were equivalent, A(305) receptors mediated production of more cAMP than WT receptors. Preincubation of COS7 cells expressing each receptor with 10(-5) M histamine for 30 min reduced subsequent cAMP production in response to histamine via the receptors to similar extents, indicating that palmitoylation is not necessary for desensitization. In addition, cell surface A(305) receptors were capable of being internalized from the cell surface at a rate and extent similar to those of WT receptors. Finally, CHO cell lines stably expressing either WT or A(305) receptors were incubated with 10(-5) M histamine for 1, 6, 12 and 24 h. Total amounts of WT and A(305) receptors, as determined by tiotidine binding, were reduced by incubation, indicating downregulation. Downregulation of the A(305) receptor was more extensive than that of the WT receptor. Thus, palmitoylation of the H2R might be important for targeting to the cell surface and stability.     

Broad-scale geographic patterns in the distribution of vertically-transmitted, asexual endophytes in four naturally-occurring grasses in Sweden

The presence and distribution of vertically-transmitted, asexual Neotyphodium/Epichloë endophytes in four species of widely distributed grasses, all members of the sub-family Pooideae, were determined at 57 spatially-distinct sites across Sweden in naturally-occurring grass populations. While these endophytes are well-studied in agricultural systems, much less is known about their abundance and distribution in non-agricultural systems at larger scales across landscapes. We used two screening methods to detect endophytes: 1) visual inspection of fixed, stained grass shoots, and 2) immunoblot cards with monoclonal antibodies specific for Neotyphodium / Epichloë endophytes. Infection frequency (i.e. the proportion of individuals) varied widely among species and among sites, a finding common to most studies performed in non-agricultural ecosystems. Festuca rubra had the highest overall infection frequency (23% visual screening, 27% immunoblot screening), while Deschampsia flexuosa (4%) and Poa trivialis (4%) had low frequencies of infection. None of the sampled Agrostis capillaris populations were infected. In F. rubra , the within-site infection frequency varied from 0 to 100%. A significant altitudinal gradient was found for F. rubra , with the infection frequency of the vertically-transmitted endophyte Epichloë festucae decreasing with increasing altitude above sea level. The high variation across and within grass species at different geographical locations that ours and others' studies reveal, agree with suggestions that agronomic model systems cannot be readily extrapolated to understand the ecological role of endophytes in native grasses in the wild. Further investigation into the underlying cause of the observed altitudinal gradient is required to understand broader-scale patterns in the distribution of endophyte-infected grasses.     

A 2-quinolinecarboxylate-substituted ruthenium(II) complex as a new type of sensitizer for dye-sensitized solar cells

A new type of ruthenium(II) complex containing a 2-quinolinecarboxylate ligand was designed and synthesized as a sensitizer for dye-sensitized solar cells, and its photophysical and photochemical properties were characterized. The solar cells created with this complex exhibited efficient panchromatic sensitization over the entire visible wavelength range extending into the near-IR region. An overall conversion efficiency of 8.2% was attained under standard air mass 1.5 irradiation (100 mW cm⁻²) with the short-circuit photocurrent density of 18.2 mA cm⁻², the open-circuit photovoltage of 0.63 V and the fill factor of 0.72.     

Metabolic engineering of the Chl d-dominated cyanobacterium Acaryochloris marina: production of a novel Chl species by the introduction of the chlorophyllide a oxygenase gene

In oxygenic photosynthetic organisms, the properties of photosynthetic reaction systems primarily depend on the Chl species used. Acquisition of new Chl species with unique optical properties may have enabled photosynthetic organisms to adapt to various light environments. The artificial production of a new Chl species in an existing photosynthetic organism by metabolic engineering provides a model system to investigate how an organism responds to a newly acquired pigment. In the current study, we established a transformation system for a Chl d-dominated cyanobacterium, Acaryochloris marina, for the first time. The expression vector (constructed from a broad-host-range plasmid) was introduced into A. marina by conjugal gene transfer. The introduction of a gene for chlorophyllide a oxygenase, which is responsible for Chl b biosynthesis, into A. marina resulted in a transformant that synthesized a novel Chl species instead of Chl b. The content of the novel Chl in the transformant was approximately 10% of the total Chl, but the level of Chl a, another Chl in A. marina, did not change. The chemical structure of the novel Chl was determined to be [7-formyl]-Chl d(P) by mass spectrometry and nuclear magnetic resonance spectroscopy. [7-Formyl]-Chl d(P) is hypothesized to be produced by the combined action of chlorophyllide a oxygenase and enzyme(s) involved in Chl d biosynthesis. These results demonstrate the flexibility of the Chl biosynthetic pathway for the production of novel Chl species, indicating that a new organism with a novel Chl might be discovered in the future.     

High-performance liquid chromatographic determination of the polar metabolites of nifedipine in plasma, blood and urine

A relatively simple reversed-phase high-performance liquid chromatographic method for the determination of the polar metabolites of nifedipine in biological fluids is described. After conversion of 2-hydroxymethyl-6-methyl-4-(2-nitrophenyl)pyridine-3,5-dicarboxylic acid 5-methyl ester (IV) into 5,7-dihydro-2-methyl-4-(2-nitrophenyl)-5-oxofuro[3,4-b]pyridine-3-carboxylic acid methyl ester (V) by heating under acidic conditions, V was extracted with n-pentane—dichloromethane (7:3) and analysed on a C₁₈ column with ultraviolet detection. Subsequently, 2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinedicarboxylic acid monomethyl ester (III) was extracted with chloroform and analysed on the same system. Limits of determination in blood were 0.1 μg/ml for III and 0.05 μg/ml for IV and V; these limits were two to ten times higher for urine. This inter-assay variability was always less than 7.5%.     

1-H MRS changes in dorsolateral prefrontal cortex after donepezil treatment in patients with mild to moderate Alzheimer's disease

Magnetic resonance spectroscopy (MRS) noninvasively provides information on the concentration of some cerebral metabolites in vivo. Among those measurable by proton magnetic resonance spectroscopy (1H-MRS), N-acetyl-aspartate (NAA) is decreased, and myo-inositol (ml) and choline (Cho) levels are increased in patients with Alzheimer's disease (AD). Donepezil, an acetylcholinesteraze inhibitor, has proven effect on cognitive symptoms in patients with AD. In previous studies, treatment response was associated with an increase of NAA and NAA/Cr in the parietal lobe and hippocampi. Correlation of longitudinal changes of 1H-MRS detectable metabolites in dorsolateral prefrontal cortex (DLPFC) with clinically observable changes is a poorly researched topic. The objective of this non-interventional study is to assess whether changes in 1H-MRS measurable metabolites correlate with clinical outcome after donepezil treatment. Twelve patients with mild to moderate AD were evaluated during 26 weeks of donepezil treatment. 1H-MRS parameters in DLPFC were assessed before and after 26 weeks of donepezil treatment. Cognition was assessed with Alzheimer's Disease Assessment Scale cognitive subscale (ADAS-Cog). A significant increase in NAA/Cr ratio and significantly lower decrease in mI/Cr ratio were found in AD patients with positive treatment response. The results of this study indicate possible modest donepezil effect on prevention of neuronal functional deterioration in DLPFC which correlates with clinical outcome and point the use of 1HMRS as technique of help in assessment of drug effect.