The effect of intra- and interspecific aggression on patch residence time in Negev Desert gerbils: a competing risk analysis

We observed patch-use behavior by two gerbil species in a fieldsetting and investigated how aggression and intrinsic decision-makinginteract to influence patch residence times. Results were interpretedby using a competing risk analysis model, which uniquely enabledus to estimate the intrinsic patch-leaving decisions independentlyof external interruptions of foraging bouts by aggression. Theexperiment was conducted in two 1-ha field enclosures completelysurrounded by rodent-proof fences and included allopatric (onlyGerbillus andersoni allenbyi) and sympatric (G. a. allenbyiand G. pyramidum) treatments. We predicted that increased foodpatch quality (i.e., habitat quality) should decrease intrinsicpatch-leaving rates and increase rates of aggressive interactionsinvolving the forager feeding in the patch (i.e., the occupantindividual). We also anticipated that increasing populationdensity should result in an increase in the rate of aggressiveinteractions involving the occupant individual. Our resultssupported the first two predictions, indicating a trade-offbetween foraging and aggression. However, the third predictionwas realized only for G. a. allenbyi in allopatry. Furthermore,in allopatry, occupant G. a. allenbyi individuals with highcompetitive ranks were involved in aggressive interactions atlower rates than those with low competitive ranks. However,in sympatry, patch-use behavior of occupant G. a. allenbyi individualswas mainly influenced by aggressive behavior of G. pyramidum,which did not respond to their competitive rank. Thus, it shouldpay less for G. a. allenbyi to be aggressive in sympatric populations.The observed reduction in intraspecific aggression among individualG. a. allenbyi in the presence of G. pyramidum supports thisassertion. We suggest that this reduction likely weakens thenegative effect of intra- and interspecific density on the percapita growth rate of G. a. allenbyi. Because this would changethe slope of the isocline of G. a. allenbyi, it could be animportant mechanism promoting coexistence when habitat selectionis constrained.     

Two uncommon phospholipase D isoenzymes from poppy seedlings (Papaver somniferum L.)

Phospholipase D (PLD) has been detected in seedlings of Papaver somniferum L. cv. Lazúr (Papaveraceae). Purification of the enzyme revealed the existence of two forms of PLD (named as PLD-A and PLD-B). The two enzymes strongly differ in their catalytic properties. The pH optima were found at pH 8.0 for PLD-A and at pH 5.5 for PLD-B. While both enzymes show hydrolytic activity toward phosphatidylcholine (PC) and phosphatidyl-p-nitrophenol (PpNP), PLD-B only was able to catalyze the exchange of choline in PC by glycerol. Both enzymes were activated by Ca²⁺ ions with an optimum concentration of 10 mM. In contrast to PLDs from other plants, PLD-B was still more activated by Zn²⁺ ions with an optimum concentration of 5 mM. The apparent molecular masses of PLD-A and PLD-B, derived from sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE), were estimated to be 116.4 and 114.1 kDa. N-terminal protein sequencing indicated N-terminal blockage in both cases. The isoelectric points were found to be 8.7 for PLD-A and 6.7 for PLD-B. Both enzymes were shown to be N-linked glycoproteins. This paper is the first report on PLD in poppy and indicates some important differences of the two enzyme forms to other PLDs known so far.     

人类生精相关基因TSARG4的cDNA克隆

为了探索精子生成的分子机制 ,从人精子外部致密纤维蛋白相关基因SPAG4(spermantigen 4)和小鼠精母细胞中表达的AK0 0 62 2 5基因出发 ,找到两个人类EST ,BG72 0 5 64和AI70 0 45 4,其中BG72 0 5 64在人睾丸中表达。运用“间隙填充法”填平这两个EST之间的间隙 ,从人睾丸文库中快速克隆了同源于SPAG4和AK0 0 62 2 5基因的人类TSARG4基因 (testisandspermatogenesisrelatedgene 4) (GenBank登录号为AF40 13 5 0 ) ,并用RT PCR对该基因阅读框进行验证。TSARG4基因全长 12 5 2bp ,开放阅读框为 94～ 12 3 3bp ,定位于 2 0q11.2 ,推定编码 3 79个氨基酸 ,预计分子量为 43 0 81.45 ,等电点为 8.61,该基因与小鼠精母细胞基因AK0 0 62 2 5编码的氨基酸序列同源性 74% ,与人类SPAG4基因编码的氨基酸序列同源性 45 %。RT PCR表明人类TSARG4基因在多个组织中均有表达 ,而同源的小鼠AK0 0 62 2 5基因仅在睾丸中表达     

Weighted Wilcoxon-type smoothly clipped absolute deviation method

Summary .  Shrinkage-type variable selection procedures have recently seen increasing applications in biomedical research. However, their performance can be adversely influenced by outliers in either the response or the covariate space. This article proposes a weighted Wilcoxon-type smoothly clipped absolute deviation (WW-SCAD) method, which deals with robust variable selection and robust estimation simultaneously. The new procedure can be conveniently implemented with the statistical software R . We establish that the WW-SCAD correctly identifies the set of zero coefficients with probability approaching one and estimates the nonzero coefficients with the rate   n ^−1/2  . Moreover, with appropriately chosen weights the WW-SCAD is robust with respect to outliers in both the x and y directions. The important special case with constant weights yields an oracle-type estimator with high efficiency in the presence of heavier-tailed random errors. The robustness of the WW-SCAD is partly justified by its asymptotic performance under local shrinking contamination. We propose a Bayesian information criterion type tuning parameter selector for the WW-SCAD. The performance of the WW-SCAD is demonstrated via simulations and by an application to a study that investigates the effects of personal characteristics and dietary factors on plasma beta-carotene level.     

Synthesis of N-tetra-O-acetyl-β-d-glucopyranosyl-N′-(4′,6′-diarylpyrimidin-2′-yl)thioureas

Some 2-amino-4,6-diarylpyrimidines 2 have been prepared from substituted benzylideneacetophenones and guanidine hydrochloride in the presence of alkali by conventional heating in alcoholic medium and microwave heating in solvent-free conditions. N-(2,3,4,6-Tetra-O-acetyl-β-d-glucopyranosyl)-N′-(4′,6′-diarylpyrimidin-2′-yl)thioureas 4 have been synthesized by reaction of per-O-acetylated glucopyranosyl isothiocyanate 1 and substituted 2-amino-4,6-diarylpyrimidines 2. Two different methods have been used, namely, refluxing in anhydrous dioxane and solvent-free microwave-assisted coupling. The second procedure afforded higher yields in much shorter reaction times. The compounds 2 and 4 were tested for their antibacterial and antifungal activities in vitro against Staphylococcus epidermidis, Enterobacter aerogenes and Candida albicans by disc diffusion method.     

Soluble glucomannan isolated from Candida utilis primes blood phagocytes

It is well documented that the polysaccharide glucomannan (GM), an abundant constituent of the fungal cell wall, in the form of particulate induces strong activation of phagocytes, however, the effects of soluble GM are not known. Activation of phagocyte anti-microbial mechanisms is a crucial part of the innate host defense against invading pathogens. However, under uncontrolled inflammatory conditions they contribute to damage of surrounding tissues. Thus, to prevent these deleterious effects, the activation of phagocytes is a tightly regulated process. Therefore, in this study we analyzed the effect of soluble GM on some neutrophil functions such as reactive oxygen species production, degranulation, and receptor mobilization at the plasma membrane. Soluble GM at the tested concentrations did not stimulate oxidative burst of phagocytes directly but significantly potentiated oxidative burst in response to opsonized zymosan particles. GM induced significant phosphorylation of p47phox subunit of NADPH oxidase on Ser345. This priming effect of GM was accompanied by time and concentration dependent degranulation characterized by increased surface expression of receptors stored in neutrophil granules (CD10, CD11b, CD14, CD35, and CD66b). Degranulation was further confirmed by increase of elastase activity in media. Thus, it could be suggested that soluble GM induces priming of phagocytes connected with their degranulation, the increase of surface receptor expression, and potentiation of oxidative burst response to opsonized particles through the activation of NADPH oxidase.     

SAHA treatment overcomes the anti-apoptotic effects of Bcl-2 and is associated with the formation of mature PML nuclear bodies in human leukemic U937 cells

Bcl-2 protects tumor cells from the apoptotic effects of various antineoplastic agents. Increased expression of Bcl-2 has been associated with poor response to chemotherapy in various malignancies, including leukemia. Therefore, bypassing the resistance conferred by anti-apoptotic factors such as Bcl-2 represents an attractive therapeutic strategy against cancer cells, including leukemic cells. We undertook this study to examine whether SAHA (suberoylanilide hydroxamic acid) overcomes the resistance by Bcl-2 in human leukemic cells, with a specific focus on the involvement of PML-NBs. Experiments were conducted with Bcl-2-overexpressing human leukemic U937 cells. Since we previously demonstrated that overexpression of Bcl-2 attenuates resveratrol-induced apoptosis in human leukemic U937 cells, resveratrol-treated U937 cells were used as a negative control. The present study indicates that SAHA at 1-7 μM, the dose range known to induce apoptosis in various cancer cells, overcomes the anti-apoptotic effects of Bcl-2 in Bcl-2-overexpressing human leukemic U937 cells. Notably, we observed that SAHA-induced formation of mature promyelocytic leukemia (PML) nuclear bodies (NBs) correlates with overcoming the anti-apoptotic effects of Bcl-2 in human leukemic U937 cells. Thus, PML protein and the formation of mature PML-NBs could be considered as therapeutic targets that could help bypass the resistance to apoptosis conferred by Bcl-2. Elucidating exactly how PML regulates Bcl-2 will require further work.     

Prey preference of Orius sauteri between Western Flower Thrips and spider mites

Prey preference of polyphagous predators plays an important role in the suppression of various species of pest insects. In this study, the prey preference of Orius sauteri (Poppius) (Heteroptera: Anthocoridae) between deutonymphs of Tetranychus urticae Koch (Acari: Tetranychidae) and second instars of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and the influence of spider mite density on the preference were examined in the laboratory in three-dimensional set-ups at 25 ± 1 °C and 70 ± 5% r.h. The results showed that the predatory bug in the presence of equal densities of the two prey species had a clear preference for thrips (preference index β: 0.86 ± 0.02), consuming 7.2 thrips larvae and 1.5 spider mite deutonymphs during the experimental periods of 6 h. The number of thrips consumed by O. sauteri did not change when the density ratio of thrips to spider mites was decreased from 1:1 to 1:5. Predation on spider mites increased when their ratio to thrips increased, but the disproportionate predation (i.e., the functional response) of O. sauteri towards spider mites resulted in a linear increase in the preference for F. occidentalis . The possible implications of these findings for the suppression of spider mites by O. sauteri in relation to the recent invasion of F. occidentalis into China are discussed.     

Coreactant electrogenerated chemiluminescence of ruthenium porphyrins

The coreactant electrogenerated chemiluminescence (ECL) of 5,10,15,20-tetraphenyl-21H,23H-porphine ruthenium(II) carbonyl (Ru(TPP)(CO))), and 2,3,7,8,12,13,17, 18-octaethyl-21H,23H-porphine ruthenium(II) carbonyl (Ru(OEP)(CO)) in acetonitrile is reported. Both complexes have absorption maxima in the visible region of the spectrum and emit in fluid solution at room temperature around 650 nm in acetonitrile. Photoluminescence efficiencies (?_em) were between 1.5 × 10⁻⁴ and 4.0 × 10⁻⁴ when compared to (bpy = 2,2′-bipyridine) with ?_em = 0.042. The complexes show two-electrochemically reversible oxidations via cyclic voltammetry. ECL was generated using tri-n-propylamine (TPrA) as an oxidative-reductive coreactant and the ECL peaks at a potential corresponding to oxidation of both the TPrA and both of the porphyrin oxidations. ECL efficiencies (?_ecl) were 0.65 for Ru(TPP)(CO) and 0.58 for Ru(OEP)(CO) when compared to (?_ecl = 1). Also, qualitative studies using transmission filters suggest that both complexes emit ECL in approximately the same region as their photoluminescence, indicating that the same excited state is formed in both experiments.     

Determination of stability constants between complexing agents and At(I) and At(III) species present at ultra-trace concentrations

A competition method is proposed to determine the complexation constants between At(I) and At(III) species and complexing agents. The method, tested with an inorganic ligand, thiocyanate ion (SCN⁻), and an organic macromolecule, thiacalix[4]arenetetrasulfonate (LH₄) is based on solid/liquid separation or liquid/liquid extraction. For the solid/liquid separation, the cationic exchanger Dowex 50X8 was used. The interaction of At(I) and At(III) with the cationic exchanger is specific but could not be described by the expected cation exchange process. Most probably, At(I, III) interacts with a “strong” site (in weak amount) to form a surface complex at the surface of the resin organic skeleton. For the liquid/liquid separation, chloroform, toluene and hexane were used. All solvents extract astatine species with distribution coefficients varying between 0.7 and 120. The extraction process was shown to be independent of aqueous phase characteristics (pH, ionic strength) and was explained by the solvation of astatine species by the organic solvent. The effect of the addition of the thiacalix[4]arenetetrasulfonate on the solid/liquid or liquid/liquid distribution coefficients could be well described by the formation of a 1:1 complex with stability constants of log β₁ = 4.5 ± 0.4 and 3.3 ± 0.3 for At(I) and At(III), respectively. For the thiocyanate ion, the data measured in the presence of the organic solvents could be explained by the formation of both 1:1 and 1:2 At:SCN complexes. In the case of the solid/liquid separation, data analysis was hampered by the probable formation of a ternary complex between At(I, III), SCN⁻ and the functional groups of the resin. As for the calixarene, the interaction strength appeared slightly higher for At(I) (log β₂ = 5.9 ± 0.3 and log β₁ = 3.8 ± 0.2 for 1:2 and 1:1 complexed species, respectively) than for At(III) (log β₂ = 5.3 ± 0.2 and log β₁ = 2.8 ± 0.2 for 1:2 and 1:1 complexed species, respectively).