Uphill energy transfer in a chlorophyll d-dominating oxygenic photosynthetic prokaryote, Acaryochloris marina

The steady-state fluorescence properties and uphill energy transfer were analyzed on intact cells of a chlorophyll (Chl) d-dominating photosynthetic prokaryote, Acaryochloris marina. Observed spectra revealed clear differences, depending on the cell pigments that had been sensitized; using these properties, it was possible to assign fluorescence components to specific Chl pigments. At 22 degrees C, the main emission at 724 nm came from photosystem (PS) II Chl d, which was also the source of one additional band at 704 nm. Chl a emissions were observed at 681 nm and 671 nm. This emission pattern essentially matched that observed at -196 degrees C, as the main emission of Chl d was located at 735 nm, and three minor bands were observed at 704 nm, 683 nm, and 667 nm, originating from Chl d, Chl a, and Chl a, respectively. These three minor bands, however, had not been sensitized by carotenoids, suggesting specific localization in PS II. At 22 degrees C, excitation of the red edge of the absorption band (which, at 736 nm, was 20 nm longer than the absorption maximum), resulted in fluorescence bands of Chl d at 724 nm and of Chl a at 682 nm, directly demonstrating an uphill energy transfer in this alga. This transfer is a critical factor for in vivo activity, due to an inversion of energy levels between antenna Chl d and the primary electron donor of Chl a in PS II.     

Human homologue of S. pombe Rad9 interacts with BCL-2/BCL-xL and promotes apoptosis

DNA damage induces apoptosis through a signalling pathway that can be suppressed by the BCL-2 protein, but the mechanism by which DNA damage does this is unknown. Here, using yeast two-hybrid and co-immunoprecipitation studies, we show that RAD9, a human protein involved in the control of a cell-cycle checkpoint, interacts with the anti-apoptotic Bcl-2-family proteins BCL-2 and BCL-x L, but not with the pro-apoptotic BAX and BAD. When overexpressed in mammalian cells, RAD9 induces apoptosis that can be blocked by BCL-2 or BCL-x L. Conversely, antisense RAD9 RNA suppresses cell death induced by methyl methanesulphonate. These findings indicate that RAD9 may have a new role in regulating apoptosis after DNA damage, in addition to its previously described checkpoint-control and other radioresistance-promoting functions.     

Intra- and interspecific DNA variation and codon bias of the alcohol dehydrogenase (Adh) locus in Arabis and Arabidopsis species

Sequence variation at the alcohol dehydrogenase (Adh) locus was analyzed for six species each of the genera Arabis and Arabidopsis. Phylogenetic analysis showed that investigated species were grouped into three clusters, and the generic classification did not correspond to the clusterings. The results indicated that the genera could not be distinguished on the basis of the Adh variation. A significant difference in the ratio of silent to replacement sites was detected by MK test in two comparisons, with Arabidopsis thaliana polymorphism due to excess silent divergence. Silent changes were predominant in the evolution of the Adh locus in Arabis and Arabidopsis. To infer evolutionary significance of silent substitutions, codon bias was studied. The degree of codon bias of the Adh region was relatively constant over Arabis and Arabidopsis species. "Preferred" codons of A. thaliana were determined. No evidence of natural selection on codon change was detected in the Adh regions of A. thaliana and Arabis gemmifera.     

A Marked Increase in Free Copper Levels in the Plasma and Liver of LEC Rats: An Animal Model for Wilson Disease and Liver Cancer

Most of copper present in rat plasma and liver binds to caeruloplasmin and metallothionein, respectively, and is not redox active. However, free forms of copper including loosely bound forms to other molecules are redox active. We assessed the free copper in Long-Evans rats with a cinnamon-like coat color (LEC rats), an animal model of Wilson disease and liver cancer. Compared to those of control rats, the liver and plasma of LEC rats showed a marked elevation of free copper, especially at the stage of acute hepatitis, in parallel with an increase of total copper levels in the livers and a decrease of plasma caeruloplasmin (ferroxidase I) activity. At the onset of jaundice, the total copper levels, however, decreased in liver, but increased in plasma, while free copper levels in both liver and plasma remained higher. Free iron levels in both liver and plasma were also determined and did not change significantly, except for the case of plasma in jaundiced rats. The data are consistent with a proposal in which increased levels of redox active free copper in the liver of LEC rats catalyze Fenton-type reactions, producing a large flux of hydroxyl radicals that would play an important role in the observed liver dysfunction, leading to acute hepatitis, and, finally, hepatocarcinoma. This is the first demonstration that the free copper may participate in the pathophysiology of the LEC rats and Wilson disease.     

Exercise-induced suppression of acylated ghrelin in humans.

Ghrelin is an orexigenic hormone secreted from endocrine cells in the stomach and other tissues. Acylation of ghrelin is essential for appetite regulation. Vigorous exercise induces appetite suppression, but this does not appear to be related to suppressed concentrations of total ghrelin. This study examined the effect of exercise and feeding on plasma acylated ghrelin and appetite. Nine male subjects aged 19-25 yr participated in two, 9-h trials (exercise and control) in a random crossover design. Trials began at 0800 in the morning after an overnight fast. In the exercise trial, subjects ran for 60 min at 72% of maximum oxygen uptake between 0800 and 0900. After this, they rested for 8 h and consumed a test meal at 1100. In the control trial, subjects rested for 9 h and consumed a test meal at 1100. Area under the curve values for plasma acylated ghrelin concentration (assessed from venous blood samples) were lower over the first 3 h and the full 9 h of the exercise trial compared with the control trial: 317+/-135 vs. 510+/-186 pg.ml(-1).3 h and 917+/-342 vs. 1,401+/-521 pg.ml(-1).9 h (means+/-SE) respectively (P<0.05). Area under the curve values for hunger (assessed using a visual scale) were lower over the first 3 h of the exercise trial compared with the control trial (P=0.013). These findings demonstrate that plasma acylated ghrelin concentration and hunger are suppressed during running.     

Selective excretion of anti-inflammatory cytokine Interleukin-10 in a superantigen-inducing neonatal infectious disease

Neonatal toxic shock syndrome (TSS)-like exanthematous disease (NTED) is an emerging neonatal infectious disease caused by TSS toxin-1 (TSST-1). Although NTED and TSS are caused by the same superantigenic exotoxin, NTED is less severe than TSS. The mechanism of this reduced severity in NTED has not been elucidated. Thirteen patients with NTED were enrolled in the study. We investigated serum cytokine profile using a cytometric bead array system with a cytokine panel. Expression of Vβ2 and CD45RO in CD4⁺ T cells was investigated in mononuclear cells by using flowcytometry. Ten patients with other bacterial infections and eight patients without any infections were also enrolled as control groups. The mean serum level of IL-10 was 1209.9 pg/mL in patients with NTED at the time of admission into the study. The other inhibitory cytokine, IL-4, exhibited a minimum level. The high level of IL-10 rapidly decreased within 3–9 days of the onset of NTED. The cytokine profile of NTED, with its high IL-10 level, was clearly different from that of the other bacterial infections. The increased level of IL-10 seems to be related to the reduced severity of NTED. Th2 shift is not thought to be the cause of this IL-10 excretion.     

Cellular internalization of arginine‐rich peptides into tobacco suspension cells: a structure–activity relationship study

Translocation of several fluorescently labeled arginine‐rich peptides into intact plant cells was quantitatively examined in order to investigate the structural factors required for efficient cellular internalization, and thereby, to evaluate the potential of arginine‐rich peptides as intracellular delivery vectors in plants. Cell‐penetrating peptides (CPPs) such as arginine‐rich peptides permit the direct introduction of biologically active macromolecules into plant cytoplasm to manipulate various intracellular processes. While a significant level of adsorption of applied arginine‐rich peptides was observed in the cell walls rich in negative charges, removal of adsorbed peptides by trypsin treatment allowed determination of the amount of internalized peptides in a quantitative manner using spectrofluorometric analysis. The internalization of arginine‐rich peptides depended on the number of arginine residues, and the peptide containing eight arginine residues showed most effective internalization. Besides, the position of small cargoes attached to the arginine‐rich peptides markedly affected the internalization efficiency. The results obtained in this study provide useful information for the development of efficient intracellular delivery tools in plant science. Copyright © 2008 European Peptide Society and John Wiley & Sons, Ltd.     

Wider Retinal Artery Trajectories in Eyes with Macular Hole Than in Fellow Eyes of Patients with Unilateral Idiopathic Macular Hole

Purpose

To determine whether the width of the retinal artery (RA) trajectory was associated with the presence of a macular hole (MH).

Methods

A retrospective cross sectional case-control study was performed. The fundus photographs were rotated 90 degrees, and the coordinates of the best fit curve of the RA trajectory were determined automatically based on these plots using the ImageJ program. The converted coordinates were fit to a second degree polynomial (ax²/100 + bx + c) equation. The width and steepness of the RA trajectory, “a”, of the eyes with a MH eye were compared to that of the fellow eyes.

Results

One hundred and ten eyes of 55 consecutive patients (30 women) with a unilateral MH and healthy fellow eyes were analyzed. The mean age was 64.9 years (range 47-81 years). The constant ‘a’ was significantly smaller in eyes with a MH than that of the fellow eyes (0.379 ± 0.094 vs 0.416 ± 0.121, P = 0.001, paired t test), indicating that the RA trajectory was wider in the MH eyes than in the fellow eyes. There was a significant correlation between the axial length and ‘a’ of the RA trajectory in the MH eyes (R = 0.273, P = 0.044) and in the fellow eyes (R = 0.356, P = 0.008; Spearman’s rank correlation coefficient).

Conclusions

Because eyes with a MH have a significantly wider and flatter RA trajectory, there may be greater traction on the fovea which is located between the RA arches. The causative role of this finding is still unclear.     

A Naturally Occurring Canine Model of Autosomal Recessive Congenital Stationary Night Blindness

Congenital stationary night blindness (CSNB) is a non-progressive, clinically and genetically heterogeneous disease of impaired night vision. We report a naturally-occurring, stationary, autosomal recessive phenotype in beagle dogs with normal daylight vision but absent night vision. Affected dogs had normal retinas on clinical examination, but showed no detectable rod responses. They had “negative-type” mixed rod and cone responses in full-field ERGs. Their photopic long-flash ERGs had normal OFF-responses associated with severely reduced ON-responses. The phenotype is similar to the Schubert-Bornschein form of complete CSNB in humans. Homozygosity mapping ruled out most known CSNB candidates as well as CACNA2D4 and GNB3. Three remaining genes were excluded based on sequencing the open reading frame and intron-exon boundaries (RHO, NYX), causal to a different form of CSNB (RHO) or X-chromosome (NYX, CACNA1F) location. Among the genes expressed in the photoreceptors and their synaptic terminals, and mGluR6 cascade and modulators, reduced expression of GNAT1, CACNA2D4 and NYX was observed by qRT-PCR in both carrier (n = 2) and affected (n = 2) retinas whereas CACNA1F was down-regulated only in the affecteds. Retinal morphology revealed normal cellular layers and structure, and electron microscopy showed normal rod spherules and synaptic ribbons. No difference from normal was observed by immunohistochemistry (IHC) for antibodies labeling rods, cones and their presynaptic terminals. None of the retinas showed any sign of stress. Selected proteins of mGluR6 cascade and its modulators were examined by IHC and showed that PKCα weakly labeled the rod bipolar somata in the affected, but intensely labeled axonal terminals that appeared thickened and irregular. Dendritic terminals of ON-bipolar cells showed increased Goα labeling. Both PKCα and Goα labeled the more prominent bipolar dendrites that extended into the OPL in affected but not normal retinas. Interestingly, RGS11 showed no labeling in the affected retina. Our results indicate involvement of a yet unknown gene in this canine model of complete CSNB.     

Rapid and Quantitative Assay of Amyloid-Seeding Activity in Human Brains Affected with Prion Diseases

The infectious agents of the transmissible spongiform encephalopathies are composed of amyloidogenic prion protein, PrP^Sc. Real-time quaking-induced conversion can amplify very small amounts of PrP^Sc seeds in tissues/body fluids of patients or animals. Using this in vitro PrP-amyloid amplification assay, we quantitated the seeding activity of affected human brains. End-point assay using serially diluted brain homogenates of sporadic Creutzfeldt–Jakob disease patients demonstrated that 50% seeding dose (SD₅₀) is reached approximately 10¹⁰/g brain (values varies 10^8.79–10.63/g). A genetic case (GSS-P102L) yielded a similar level of seeding activity in an autopsy brain sample. The range of PrP^Sc concentrations in the samples, determined by dot-blot assay, was 0.6–5.4 μg/g brain; therefore, we estimated that 1 SD₅₀ unit was equivalent to 0.06–0.27 fg of PrP^Sc. The SD₅₀ values of the affected brains dropped more than three orders of magnitude after autoclaving at 121°C. This new method for quantitation of human prion activity provides a new way to reduce the risk of iatrogenic prion transmission.