The influence of mineral salts on fecundity of the water flea (Daphnia magna) and the implications on toxicity testing of industrial wastewater

The effects of mineral salts constituting water hardness on fecundity ofDaphnia magna were assessed. Of the salts tested, increased concentrations of NaHCO₃ and MgSO₄ had no effect on fecundity, CaSO₄ significantly increased fecundity, and KCl significantly reduced fecundity. The number of offspring produced per daphnid was correlative to the CaSO₄ concentration at CaSO₄ concentrations between 91 and 2100 mg/ℓ. The effects of CaSO₄ on daphnid fecundity could influence the interpretive outcome of industrial wastewater toxicity tests using this species when the waste and dilution waters contain different concentrations of CaSO₄. It is recommended that when performing these tests, dilution water be sampled at the intake site of the industry's water source, thus assuring initial comparability of the waste and dilution waters. The CaSO₄ content of the water prior to and after industrial use should be determined to identify any alterations of CaSO₄ concentration during use. Identification of CaSO₄ concentration differences can aid in the interpretation of effects associated with the wastewater.     

Selection for Resistance to Leptosphaerulina Leaf Spot in Alfalfa

Significant differences were observed among 11 alfalfa cultivars for the percentage of plants resitant to Leptospbaerulina briosiana after one inoculation. Screening for resistance was done by inoculating 18 day old plants (cv. Europe), held in a moist chamber, with L. briosiana. The self- and cross-progenies of plants resistant to L. briosiana after two inoculations showed slightly higher resistance to Leptosphaerulina leaf spot than the unselected original population but the difference was significant for the cross-progeny only. Larger variations were observed among self-progenies than cross-progenies. No correlation was found between self - and cross-progenies. At least three inoculations may be necessary to eliminate most susceptible plants. Mas selection was as effective as the polycross progeny test to improve the level of resistance of the selected populations as compared with the unselected one but the difference was agronomically unimportant. Under field conditions, the plants selected as resistant after two inoculations in the laboratory showed better resistance to L. briosiana than the susceptible ones but only on the first of three notations. The population derived from plants selected from cv. Europe as resistant to L. briosiana in the laboratory was not significantly more resitant than cv. Europe in the filed but generally showed less foliar infection.     

Membrane particle changes attending the acrosome reaction in guinea pig spermatozoa

To examine the freeze-fracture appearance of membrane alterations accompanying the preparation of sperm membranes for fusions-the first preparatory stage occurring before physiological release of the acrosomal content, the second afterward-we induced the acrosome reaction in capacitated guinea pig spermatozoa by adding calcium to the mixture. The most common features observed before fusion of the acrosomal and plasma membranes were the deletion of fibrillar intramembranous particles from the E-fracture faces of both membranes, and the clearance of globular particles from the P face of the plasma membrane-events taking place near the terminus of the equatorial segment. Large particles, >12nm, remained not far from the cleared E-face patches. The P face of the outer acrosomal membrane is virtually clear from the outset. In addition, when fusion was completed, occasional double lines of large particles transiently embossed the P face of the plasma membrane (postacrosomal) side of the fusion zone. Behind the line of fusion, another series of particle-cleared foci emerged. We interpreted these postfusion membrane clearances as a second adaptation for sperm-egg interaction. Induction of the acrosome reaction in media containing phosphatidylcholine liposomes resulted in their apparent attachment, incorporation, or exchange in both the originally and secondarily cleared regions. Our observations support the concepts that membranes become receptive to union at particle- deficient interfaces, and that the physiologically created barren areas in freeze-fracture replicas may herald incipient membrane fusion.     

Modifications of anionic-lipid domains preceding membrane fusion in guinea pig sperm

The relationship between anionic-lipid concentration and the functional properties of plasma-membrane domains was explored using the guinea-pig sperm membrane as a model, with polymyxin B (PXB) as a probe. Areas of plasmalemma specialized for fusion during the acrosome reaction had a higher affinity for the probe than adjacent nonfusigenic regions. In addition, capacitation--a process preceding acrosome:plasma-membrane fusion--markedly enlarged the area susceptible to PXB binding over the acrosomal cap. Protease treatment mimicked capacitation by increasing the acrosome-reaction incidence as well as PXB binding, at enzyme concentrations not affecting the surface coat nor altering filipin/sterol localization. Both proteolytic digestion and capacitation failed to augment PXB- or filipin-affinity in nonfusigenic zones, such as the post-acrosomal segment, including its particle-free maculae. Incubation of sperm in capacitating medium supplemented with 32P-labeled phosphate, followed by lipid extraction, thin-layer chromatography, and autoradiography, revealed a radioactive band comigrating with cardiolipin and phosphatidic acid. Vermiform protrusions elicited by PXB in the outer lamellae of cardiolipin- phosphatidylcholine liposomes resembled those seen in fusional regions of sperm membrane. We conclude that (a) differing concentrations of anionic lipids are found in adjacent domains of the sperm plasma membrane; (b) these domains mirror the functional regions of the membrane, with higher anionic-lipid concentrations localized over fusional zones; (c) the surface coat does not participate in the maintenance of such domains; (d) anionic-lipid synthesis may contribute to their formation; and (e) anionic-lipid concentrations increase as the membrane becomes fusionally competent, indicating that cellular modulation of lipid domains accompanies regulation of membrane function.     

Monoclonal antibodies to rabbit liver cytochrome P-448

Cytochrome P-448 (mol wt 55,000 Daltons) from rabbit liver was purified to a specific content of 16.6 nmol/mg. Mice were immunised with this preparation, their spleens removed and dissociated lymphocytes hybridised with myeloma cells. Four monoclonal antibodies against cytochrome P-448 were raised and partially characterised. All four antibodies interacted with cytochrome P-448 in intact microsomal fractions and selectively immunoadsorbed cytochrome P-448 from solubilised microsomal preparations. One of the antibodies inhibited benzo[a] pyrene hydroxylase activity in a reconstituted system, one had no effect on activity and two increased activity. The possible applications of such antibodies are discussed.     

Nanocrystalline SrS:Ce3+ system for the generation of white light‐emitting diodes

Nanocrystalline SrS phosphors doped with Ce³⁺ ions at different concentrations (0.5, 1, 1.5 and 2 mol%) are synthesized via the solid‐state diffusion method (SSDM), which is suitable for the large‐scale production of phosphors in industrial applications. The as‐prepared samples are characterized using an X‐ray diffraction (XRD) technique, field emission scanning electron microscopy (FESEM), high‐resolution transmission electron microscopy (HRTEM) and energy‐dispersive X‐ray (EDX) analysis. The optical properties of these phosphors are analyzed using reflectance spectra, photoluminescence spectra and afterglow decay curves. The cubic structure of the SrS phosphor is confirmed by XRD analysis and the crystallite size calculated by Scherer's formula using XRD data shows the nanocrystalline nature of the phosphors. No phase change is observed with increasing concentrations of Ce³⁺ ions. The surface morphology of the prepared phosphors is determined by FESEM, which shows a sphere‐like structure and good connectivity of the grains. The authenticity of the formation of nanocrystalline phosphors is examined by HRTEM analysis. Elemental compositional information for the prepared phosphors is gathered by EDX analysis. Photoluminescence studies reveal that the emission spectra of the prepared phosphor shows broad band emission centered at 458 and 550 nm due to the transition of electrons from the 5d → 4f energy levels. The afterglow decay characteristics of different as‐synthesized SrS:Ce³⁺ nanophosphors are conceptually described. Copyright © 2016 John Wiley & Sons, Ltd.     

Biodecolourization of azo and triphenylmethane dyes by <Emphasis Type="Italic">Dichomitus squalens</Emphasis> and <Emphasis Type="Italic">Phlebia</Emphasis> spp

Nine white-rot fungal strains were screened for biodecolourization of brilliant green, cresol red, crystal violet, congo red and orange II. Dichomitus squalens, Phlebia fascicularia and P. floridensis decolourized all of the dyes on solid agar medium and possessed better decolourization ability than Phanerochaete chrysosporium when tested in nitrogen-limited broth medium. Journal of Industrial Microbiology & Biotechnology (2002) 28, 201–203 DOI: 10.1038/sj/jim/7000222 Received 12 July 2001/ Accepted in revised form 22 October 2001     

Bacteria in cancer therapy: a novel experimental strategy

Resistance to conventional anticancer therapies in patients with advanced solid tumors has prompted the need of alternative cancer therapies. Moreover, the success of novel cancer therapies depends on their selectivity for cancer cells with limited toxicity to normal tissues. Several decades after Coley's work a variety of natural and genetically modified non-pathogenic bacterial species are being explored as potential antitumor agents, either to provide direct tumoricidal effects or to deliver tumoricidal molecules. Live, attenuated or genetically modified non-pathogenic bacterial species are capable of multiplying selectively in tumors and inhibiting their growth. Due to their selectivity for tumor tissues, these bacteria and their spores also serve as ideal vectors for delivering therapeutic proteins to tumors. Bacterial toxins too have emerged as promising cancer treatment strategy. The most potential and promising strategy is bacteria based gene-directed enzyme prodrug therapy. Although it has shown successful results in vivo yet further investigation about the targeting mechanisms of the bacteria are required to make it a complete therapeutic approach in cancer treatment.     

Production of haploids and doubled haploids in oil palm

Background

Studies on host-pathogen interactions in a range of pathosystems have revealed an array of mechanisms by which plants reduce the efficiency of pathogenesis. While R-gene mediated resistance confers highly effective defense responses against pathogen invasion, quantitative resistance is associated with intermediate levels of resistance that reduces disease progress. To test the hypothesis that specific loci affect distinct stages of fungal pathogenesis, a set of maize introgression lines was used for mapping and characterization of quantitative trait loci (QTL) conditioning resistance to Setosphaeria turcica, the causal agent of northern leaf blight (NLB). To better understand the nature of quantitative resistance, the identified QTL were further tested for three secondary hypotheses: (1) that disease QTL differ by host developmental stage; (2) that their performance changes across environments; and (3) that they condition broad-spectrum resistance.

Results

Among a set of 82 introgression lines, seven lines were confirmed as more resistant or susceptible than B73. Two NLB QTL were validated in BC₄F₂ segregating populations and advanced introgression lines. These loci, designated qNLB1.02 and qNLB1.06, were investigated in detail by comparing the introgression lines with B73 for a series of macroscopic and microscopic disease components targeting different stages of NLB development. Repeated greenhouse and field trials revealed that qNLB1.06 _Tx303 (the Tx303 allele at bin 1.06) reduces the efficiency of fungal penetration, while qNLB1.02 _B73 (the B73 allele at bin 1.02) enhances the accumulation of callose and phenolics surrounding infection sites, reduces hyphal growth into the vascular bundle and impairs the subsequent necrotrophic colonization in the leaves. The QTL were equally effective in both juvenile and adult plants; qNLB1.06 _Tx303 showed greater effectiveness in the field than in the greenhouse. In addition to NLB resistance, qNLB1.02 _B73 was associated with resistance to Stewart's wilt and common rust, while qNLB1.06 _Tx303 conferred resistance to Stewart's wilt. The non-specific resistance may be attributed to pleiotropy or linkage.

Conclusions

Our research has led to successful identification of two reliably-expressed QTL that can potentially be utilized to protect maize from S. turcica in different environments. This approach to identifying and dissecting quantitative resistance in plants will facilitate the application of quantitative resistance in crop protection.     

Identification of an intracellular microdomain of the P2X7 receptor that is crucial in basolateral membrane targeting in epithelial cells

We investigated membrane targeting of the P2X₇ receptor (P2X₇R) in polarized epithelial cells using immunofluorescent confocal imaging. The wild-type receptor was targeted to the basolateral membrane, independently of adaptor protein μ1B. Deletion of the majority of the intracellular C-terminus, or the last 26 residues (P570-Y595), conferred targeting of the protein to the apical membrane. Alanine substitution in the microdomain P582-Q587 caused similar apical membrane targeting without major effect on the receptor function and surface expression. Our results show basolateral membrane targeting of the P2X₇R in epithelial cells and that the intracellular C-terminal microdomain P582-Q587 is crucial in this process.

Structured summary

MINT-8055849:Beta-catenin (uniprotkb:B6V8E6) and P2X7R (uniprotkb:Q64663) colocalize (MI:0403) by fluorescence microscopy (MI:0416)