Absence of far-red emission band in aggregated core antenna complexes

Reported herein is a Stark fluorescence spectroscopy study performed on photosystem II core antenna complexes CP43 and CP47 in their native and aggregated states. The systematic mathematical modeling of the Stark fluorescence spectra with the aid of conventional Liptay formalism revealed that induction of aggregation in both the core antenna complexes via detergent removal results in a single quenched species characterized by a remarkably broad and inhomogenously broadened emission lineshape peaking around 700 nm. The quenched species possesses a fairly large magnitude of charge-transfer character. From the analogy with the results from aggregated peripheral antenna complexes, the quenched species is thought to originate from the enhanced chlorophyll-chlorophyll interaction due to aggregation. However, in contrast, aggregation of both core antenna complexes did not produce a far-red emission band at ～730 nm, which was identified in most of the aggregated peripheral antenna complexes. The 730-nm emission band of the aggregated peripheral antenna complexes was attributed to the enhanced chlorophyll-carotenoid (lutein1) interaction in the terminal emitter locus. Therefore, it is very likely that the no occurrence of the far-red band in the aggregated core antenna complexes is directly related to the absence of lutein1 in their structures. The absence of the far-red band also suggests the possibility that aggregation-induced conformational change of the core antenna complexes does not yield a chlorophyll-carotenoid interaction associated energy dissipation channel.     

Sialyl-glycoconjugates in cholesterol-rich microdomains of P388 cells are the triggers for apoptosis induced by Rana catesbeiana oocyte ribonuclease

SBL/RC-RNase was originally isolated from frog (Rana catesbeiana) oocytes and purified as a novel sialic acid-binding lectin (SBL) that displayed strong anti-cancer activity. SBL was later shown to be identical to a ribonuclease (RC-RNase) from oocytes of the same species. The administration of SBL/RC-RNase induced apoptosis (with nuclear condensation and DNA fragmentation) in mouse leukemia P388 cells but did not kill umbilical vein endothelial or fibroblast cells derived from normal tissues. The cytotoxic activity of SBL/RC-RNase was inhibited by desialylation of P388 cells and/or the co-presence of free bovine submaxillary mucin. FACS analysis showed that SBL/RC-RNase was incorporated into cells after attachment to cholesterol-rich microdomains. Addition of the cholesterol remover methyl-β-cyclodextrin reduced SBL/RC-RNase-induced apoptosis. Apoptosis occurred through the caspase-3 pathway following activation of caspase-8 by SBL/RC-RNase. A heat shock cognate protein (Hsc70) and a heat shock protein (Hsp70) (each 70 kDa) on the cell membrane were shown to bind to SBL/RC-RNase by mass spectrometric and flow cytometric analyses. Quercetin, an inhibitor of Hsc70 and Hsp70, significantly reduced SBL/RC-RNase-induced apoptosis. Taken together, our findings suggest that sialyl-glycoconjugates present in cholesterol-rich microdomains form complexes with Hsc70 or Hsp70 that act as triggers for SBL/RC-RNase to induce apoptosis through a pathway involving the activation of caspase-3 and caspase-8.     

Female prereproductive coloration reduces mating harassment in damselflies

Conspicuous female coloration can evolve through male mate choice or via female-female competition thereby increasing female mating success. However, when mating is not beneficial, such as in pre-reproductive females, selection should favor cryptic rather than conspicuous coloration to avoid male detection and the associated harassment. Nevertheless, conspicuous female coloration occurs in many prereproductive animals, and its evolution remains an enigma. Here, I studied conspicuous female coloration in Agriocnemis femina damselflies, in which the conspicuous red color of the immature females changes to a less conspicuous green approximately a week after their emergence. I measured body size, weight, and egg numbers of the female morphs and found that red females are smaller and lighter and do not carry developed eggs. Finally, I calculated the occurrence frequency and mating frequency of red and green females in several populations over a three-year period. The results demonstrate that red females mated less frequently than green females even when red females were the abundant morph in the populations. I concluded that conspicuous female coloration is likely to function as a warning signal of sexual unprofitability, thereby reducing sexual harassment for females and unprofitable mating for males.     

Hi-Bi Photonic Crystal Fiber for Broadband Filter Realization Using Copper Microwires

This paper presents a highly birefringence (Hi-Bi) photonic crystal fiber (PCF)-based single-polarization filter, which consists of copper microwires. Copper is chemically stable and the use of microwires is benefit to fabricate than any metal-coated PCF. The filter characteristics are inspected by the full-vector finite element method (FEM). The proposed filter can filter out y-polarized mode, while the x-polarized mode can be guided. The confinement loss of the y-polarized mode at the wavelength of 1.31 μm is achieved of 696.79 dB/cm, while the x-polarized loss is only 4.34 dB/cm. According to numerical results, 20 dB bandwidth of the proposed filter with a maximum value of crosstalk of 601.37 dB is achieved of 650 nm that range from 1.1 to 1.75 μm. Furthermore, the insertion loss of the guided mode (x-polarization) is as low as 0.142 dB for 1 mm of fiber length. Moreover, by optimizing the structural parameters, it has shown that the proposed filter can be effective at any wavelength at the optical communication window.

     

MRP1 Expressed on Burkitt’s Lymphoma Cells was Depleted by Catfish Egg Lectin Through Gb3-Glycosphingolipid and Enhanced Cytotoxic Effect of Drugs

A novel anticancer mechanism of catfish (Silurus asotus) egg lectin (SAL) was found to occur via the down-regulation of the membrane transopter protein, MRP1 (multidrug resistance associate protein-1) on Burkitt's lymphoma cells through Gb3(Galα1-4Galβ1-4Glc)-glycosphingolipid. Although SAL did not influence the viability of the cells directly, only 10 and 100 ng/mL of vincristine and etoposide, respectively induced anticancer effects when the lectin was applied in conjunction with these drugs. These phenomena were specifically inhibited by the co-presence of the α-galactoside, melibiose, which is a strong haptenic sugar of SAL that mimicks Gb3. The degree of expression regulation of the transporter proteins on the cells surface was investigated through the examination of the binding between SAL and Gb3-glycosphingolipid by immunological and molecular biological procedures. PCR data showed that MRP1 was more highly expressed when compared to another ATP-binding cassette family, multi-drug resistant protein and the expression levels of MRP1 on the cells were specifically dose- and time-dependently depleted by the addition of SAL. These results were also evaluated by immunological procedures using FACS and western-blotting. Small interfering RNA coding a part of MRP1 was transfected to Raji cells to knock down the protein, and cell death was increased by 10% when vincristine was administered at a concentration as low as 10 ng/mL compared to non-transfected cells. These results indicated that SAL possesses the potential to enhance the anticancer activites of low-concentrations of vincristine by the down-regulating the MRP1 gene expression to inhibit the multidrug resistance by binding to the target ligand Gb3-glycosphingolipid on Burkitt's lymphoma cells.     

A Lectin from the Mussel Mytilus galloprovincialis Has a Highly Novel Primary Structure and Induces Glycan-mediated Cytotoxicity of Globotriaosylceramide-expressing Lymphoma Cells

A novel lectin structure was found for a 17-kDa α-d-galactose-binding lectin (termed “MytiLec”) isolated from the Mediterranean mussel, Mytilus galloprovincialis. The complete primary structure of the lectin was determined by Edman degradation and mass spectrometric analysis. MytiLec was found to consist of 149 amino acids with a total molecular mass of 16,812.59 Da by Fourier transform-ion cyclotron resonance mass spectrometry, in good agreement with the calculated value of 16,823.22 Da. MytiLec had an N terminus of acetylthreonine and a primary structure that was highly novel in comparison with those of all known lectins in the structure database. The polypeptide structure consisted of three tandem-repeat domains of ∼50 amino acids each having 45–52% homology with each other. Frontal affinity chromatography technology indicated that MytiLec bound specifically to globotriose (Gb3; Galα1–4Galβ1–4Glc), the epitope of globotriaosylceramide. MytiLec showed a dose-dependent cytotoxic effect on human Burkitt lymphoma Raji cells (which have high surface expression of Gb3) but had no such effect on erythroleukemia K562 cells (which do not express Gb3). The cytotoxic effect of MytiLec was specifically blocked by the co-presence of an α-galactoside. MytiLec treatment of Raji cells caused increased binding of anti-annexin V antibody and incorporation of propidium iodide, which are indicators of cell membrane inversion and perforation. MytiLec is the first reported lectin having a primary structure with the highly novel triple tandem-repeat domain and showing transduction of apoptotic signaling against Burkitt lymphoma cells by interaction with a glycosphingolipid-enriched microdomain containing Gb3.     

Fecal collection, ambient preservation, and DNA extraction for PCR amplification of bacterial and human markers from human feces

Feces contain intestinal bacteria and exfoliated epithelial cells that may provide useful information concerning gastrointestinal tract health. Intestinal bacteria that synthesize or metabolize potential carcinogens and produce anti-tumorigenic products may have relevance to colorectal cancer, the second most common cause of cancer deaths in the USA. To facilitate epidemiological studies relating bacterial and epithelial cell DNA and RNA markers, preservative/extraction methods suitable for self-collection and shipping of fecal samples at room temperature were tested. Purification and PCR amplification of fecal DNA were compared after preservation of stool samples in RNAlater (R) or Paxgene (P), or after drying over silica gel (S) or on Whatman FTA cards (W). Comparisons were made to samples frozen in liquid nitrogen (N2). DNA purification methods included Whatman (accompanying FTA cards), Mo-Bio Fecal (MB), Qiagen Stool (QS), and others. Extraction methods were compared for amount of DNA extracted, DNA amplifiable in a real-time SYBR-Green quantitative PCR format, and the presence of PCR inhibitors. DNA can be extracted after room temperature storage for five days from W, R, S and P, and from N2 frozen samples. High amounts of total DNA and PCR-amplifiable Bacteroides spp. DNA (34%+/-9% of total DNA) with relatively little PCR inhibition were especially obtained with QS extraction applied to R preserved samples (method QS-R). DNA for human reduced folate carrier (SLC19A1) genomic sequence was also detected in 90% of the QS-R extracts. Thus, fecal DNA is well preserved by methods suitable for self-collection that may be useful in future molecular epidemiological studies of intestinal bacteria and human cancer markers.     

Bagworm decorations are an anti-predatory structure

1. Many animals decorate their exterior with environmental materials, and these decorations are predicted to increase their survival. The adaptive significance of these decorations, however, has seldom been tested experimentally under field conditions.
2. This study researched the anti-predatory functions of the decoration (bag) of a bagworm moth, Eumeta crameri, against their natural predator, Oecophylla smaragdina, the Asian weaver ant. The study experimentally tested if bag removal from caterpillars resulted in more predation than bagged caterpillars under field conditions, which would support the hypothesis that bags are selected to protect the caterpillars against their predators.
3. In support of the prediction, this study showed that caterpillars without a bag were attacked, killed, and taken to ants' nests significantly more than bagged caterpillars. The study provides rare experimental evidence for the anti-predatory functions of the decoration under field conditions. This study suggests that decorating behaviour has evolved in animals as an anti-predatory defence mechanism.