Ecological traps for dragonflies in a cemetery: the attraction of Sympetrum species (Odonata: Libellulidae) by horizontally polarizing black gravestones

1. We observed that the dragonfly species Sympetrum flaveolum, S. striolatum, S. sanguineum, S. meridionale and S. danae were attracted by polished black gravestones in a Hungarian cemetery. 2. The insects showed the same behaviour as at water: (i) they perched persistently in the immediate vicinity of the chosen gravestones and defended their perch against other dragonflies; (ii) flying individuals repeatedly touched the horizontal surface of the shiny black tombstones with the ventral side of their body; (iii) pairs in tandem position frequently circled above black gravestones. 3. Tombstones preferred by the dragonflies were in the open and had an area of at least 0.5 m² with an almost horizontal, polished, black surface and with at least one perch in their immediate vicinity. 4. Using imaging polarimetry, we found that the black gravestones, like smooth water surfaces, reflect highly and horizontally polarized light. 5. In double‐choice field experiments with various test surfaces, we showed that the dragonflies attracted to shiny black tombstones display positive polarotaxis and, under natural conditions, detect water by means of the horizontally polarized reflected light. This, and the reflection‐polarization characteristics of black gravestones, explain why these dragonflies are attracted to black tombstones. 6. If females attracted to the black gravestones oviposit on them, the latter constitute ecological traps for dragonflies that are not close to water.     

Attraction of insects to potato plants through use of artificial honeydews and aphid juice

Three field experiments were conducted to determine the attractiveness of artificial honeydews and aphid juice to insects. Honeydew mixtures were composed of molasses, honey and tryptophane alone or combined with Feed-Wheast^®, (produced by culturing the yeastKluyveromyces fragilis Jorgensen on cottage cheese whey). Potato plants,Solanum tuberosum L., treated with sprays of these mixtures attracted the following predatory insects: green lacewings,Chrysopa carnea Stephens; ladybird beetlesHippodamia spp.,Coccinella transversoguttata Brown,Scymnus postpinctus Casey; andGeocoris pallens Stal.Lygus hesperus Knight, a phytophagous species was also attracted. Honey and tryptophane were the most attractive to all species. Aphid juice was attractive to several predators but not to lygus bugs. Orientation through olfactory response was indicated for ladybird beetles and lygus bugs. The predatory species attracted are important in the natural control of potato insects. The attraction ofL. hesperus to artificial honeydews may be useful in the control of this pest.     

Degrees of polarization of reflected light eliciting polarotaxis in dragonflies (Odonata), mayflies (Ephemeroptera) and tabanid flies (Tabanidae)

With few exceptions insects whose larvae develop in freshwater possess positive polarotaxis, i.e., are attracted to sources of horizontally polarized light, because they detect water by means of the horizontal polarization of light reflected from the water surface. These insects can be deceived by artificial surfaces (e.g. oil lakes, asphalt roads, black plastic sheets, dark-coloured cars, black gravestones, dark glass surfaces, solar panels) reflecting highly and horizontally polarized light. Apart from the surface characteristics, the extent of such a ‘polarized light pollution’ depends on the illumination conditions, direction of view, and the threshold p* of polarization sensitivity of a given aquatic insect species. p* means the minimum degree of linear polarization p of reflected light that can elicit positive polarotaxis from a given insect species. Earlier there were no quantitative data on p* in aquatic insects. The aim of this work is to provide such data. Using imaging polarimetry in the red, green and blue parts of the spectrum, in multiple-choice field experiments we measured the threshold p* of ventral polarization sensitivity in mayflies, dragonflies and tabanid flies, the positive polarotaxis of which has been shown earlier. In the blue (450 nm) spectral range, for example, we obtained the following thresholds: dragonflies: Enallagma cyathigerum (0% < p* ≤ 17%), Ischnura elegans (17% ≤ p* ≤ 24%). Mayflies: Baetis rhodani (32% ≤ p* ≤ 55%), Ephemera danica, Epeorus silvicola, Rhithrogena semicolorata (55% ≤ p* ≤ 92%). Tabanids: Tabanus bovinus, Tabanus tergestinus (32% ≤ p* ≤ 55%), Tabanus maculicornis (55% ≤ p* ≤ 92%).     

Investigation of Resonance Modulation of a Single Rhombic Plasmonic Nanoparticle

Optical extinction resonant properties of the silver rhombic plasmonic nanoparticles in visible regime were investigated by means of finite difference time domain method algorithm-based computational numerical calculation. Considering aspect ratio (a/b) of the x- and y-axes of the rhombic particles, the polarization in different angles of the incident light, and the index of the surrounding medium, we studied the extinction properties of a single rhombus. The simulation results show that there is only one clear resonance peak in the visible regime, and the corresponding plasmon mode is a dipolar plasmon mode. Along the direction of the light polarization, with the increase of the aspect ratio (a/b), red shift of the resonant peak occurs and the extinction efficiency increases accordingly. With the polarization angle varying from 0° to 90°, the resonance peaks show a small blue shift and the corresponding extinction efficiency varies slightly consequently. The tailoring ability of the resonance frequency is shown to be improved due to a unique interaction of local geometry with surface charge distributions.     

Properties of the nonlethal recombinational repair deficient mutants of bacteriophage T4

Summary The rate at which ³H thymidine is incorporated into DNA is increased in T4w-infected cells compared to wild-type when measured late in infection under conditions of low thymidine concentration. This increased DNA synthesis is sensitive to hydroxyurea but not to mitomycin C, and can be prevented by the addition of chloramphenicol early in infection. Also, DNA replicative intermediates isolated from T4w-infected cells late in infection sediment significantly faster than those isolated from wild-type-infected cells. In contrast, DNA replicative intermediates isolated from T4x-or T4y-infected cells sediment more slowly than those produced by wild-type T4. Cells coinfected with wild-type T4⁺ and T4x, y or w; or T4w and T4x or y, produce wild-type DNA replicative intermediates. Cells coinfected with T4x and T4y produce more slowly sedimenting DNA replicative intermediates. Cells coinfected with T4w and wild-type T4 show wild-type rates of DNA synthesis while cells coinfected with T4w and T4x or T4y show increased rates of DNA synthesis over that observed with wild-type alone.     

Kinetics of formation of fibrin oligomers. I. Theory

The course of formation of fibrin oligomers is treated theoretically for the condition that self-assembly of fibrin monomers is rapid compared with the loss of A peptides by the enzymatic action of thrombin. The rate constant for removal of the second A peptide is taken to be larger than that for the first by an arbitrary factor q; the association of activated A sites with their complementary a sites is assumed to be random and independent of oligomer size. Two types of oligomers are considered: noncovalently bonded protofibrils formed by the staggered overlap of thrombin-activated monomers and covalently bonded linear oligomers formed by factor XIIIa-mediated end-to-end ligation of adjacent monomers within protofibrils. Oligomers of the first type, if ligated, are dissociated to oligomers of the second type by solubilization in SDS–urea. Theoretical curves are presented for x _w and x ′_w (weight-average degree of polymerization of staggered overlap and linear ligated oligomers, respectively) and for the weight fractions of monomer, dimer, and decamer of both ligated and unligated species as functions of y, the fraction of A peptide removed; and also for w_x and w′_x, the weight fractions of x-mer of the respective oligomer types, as a function of x at y = 0.5. With increasing q, the maximum w_x or w′_x that a low oligomer will reach during the reaction decreases and the size distribution is broadened toward larger oligomers. Comparison with experiment is made in a companion paper.     

The cytochrome b region in the mitochondrial DNA of the ant Tetraponera rufoniger: Sequence divergence in hymenoptera may be associated with nucleotide content

Polymerase chain reaction (PCR) followed by sequencing of single-stranded DNA yielded sequence information from the cytochrome b (cyt b) region in mitochondrial DNA from the ant Tetraponera rufoniger. Compared with the cyt b genes from Apis mellifera, Drosophila melanogaster, and D. yakuba, the overall A + T content (A + T%) of that of T. rufoniger is lower (69.9% vs 80.7%, 74.2%, and 73.9%, respectively) than those of the other three. The codon usage in the cyt b gene of T. rufoniger is biased although not as much as in A. mellifera, D. melanogaster, and D. yakuba; T. rufoniger has eight unused codons whereas D. melanogaster, D. yakuba, and A. mellifera have 21, 20, and 23, respectively. The inferred cyt b polypeptide chain (PPC) of T. rufoniger has diverged at least as much from a common ancestor with D. yakuba as has that of A. mellifera (3.5 vs 2.9). Despite the lower A + T%, the relative frequencies of amino acids in the cyt b PPC of T. rufoniger are significantly (P < 0.05) associated with the content of adenine and thymine (A + T%) and size of codon families. The mitochondrially located cytochrome oxidase subunit 11 genes (CO-II) of endopterygote insects have significantly higher average A + T% (75%) than those of exopterygous (69%o) and paleopterous (69%) insects. The increase in A + T% of endopterygote insects occurred in Upper Carboniferous and coincided with a significant acceleration of PPC divergence. However, acceleration of PPC divergence is not significantly correlated with the increase of the A + T% (P > 0.1). The high A + T%, the biased codon usage, and the increased PPC divergence of Hymenoptera can in that respect most easily be explained by directional mutation pressure which began in the Upper Carboniferous and still occurs in most members of the order. Given the roughly identical A + T% of the cyt b and CO-II genes from the other insects whose DNA sequences are known (A. mellifera, D. melanogaster, and D. yakuba), it seems most likely that the A + T% of T. rufoniger declined secondarily within the last 100 Myr as a result of a reduced directional mutation pressure.Abbreviations Myr million years - mtDNA mitochondrial DNA - scnDNA single-copy nuclear DNA - A adenine - C cytosine - G guanine - T thymine - A + T% content of A and T - PPC polypeptide chain - cyt b cytochrome b - CO-I cytochrome oxidase sub-unit I - CO-II cytochrome oxidase subunit II - ND1 NADH dehydrogenase subunit 1 - ND6 NADH dehydrogenase subunit 6 - tRNA _infUCN ^supSer ucN transfer RNA for serine with a UCN anticodon Correspondence to: L.S. Jermiin     

Spectral regions in which aquatic insects see reflected polarized light

For diverse water insects (species of Hydrophilidae, Hadraenidae, Dytiscidae, Haliplidae and aquatic Heteroptera), the attractiveness of an artificial water surface was found to vary when the polarization of the reflected light, the property by which these insects identify water, was abolished in different regions of the spectrum. The sensitivity maxima of their reflection-polarization visual systems (max(POL)) thus determined were in various spectral regions, between < 360 nm (UV) and ca. 550 nm (yellow-green). Species with max(POL) at the short-wavelength end of the spectrum would be able to identify bodies of water by polarization regardless of whether the subsurface reflection was bright or dark; nevertheless, this group includes forms that avoid water with a bright subsurface because of the intensity of the reflected light. Species with max(POL) in the long-wavelength region fail to use certain bodies of water with a bright subsurface as habitats because the light they reflect at the longer wavelengths is insufficiently polarized. That the POL system of a species has a large max could affect habitat choice; on the other hand, it could also be that systems operating in the long-wavelength region were produced in the course of adaptation to the light conditions in or above the habitat.Abbreviations max(POL) spectral sensitivity maximum for polarization vision     

Lamp-Lit Bridges as Dual Light-Traps for the Night-Swarming Mayfly,Ephoron virgo: Interaction of Polarized and Unpolarized Light Pollution

Ecological photopollution created by artificial night lighting can alter animal behavior and lead to population declines and biodiversity loss. Polarized light pollution is a second type of photopollution that triggers water-seeking insects to ovisposit on smooth and dark man-made objects, because they simulate the polarization signatures of natural water bodies. We document a case study of the interaction of these two forms of photopollution by conducting observations and experiments near a lamp-lit bridge over the river Danube that attracts mass swarms of the mayfly Ephoron virgo away from the river to oviposit on the asphalt road of the bridge. Millions of mayflies swarmed near bridge-lights for two weeks. We found these swarms to be composed of 99% adult females performing their upstream compensatory flight and were attracted upward toward unpolarized bridge-lamp light, and away from the horizontally polarized light trail of the river. Imaging polarimetry confirmed that the asphalt surface of the bridge was strongly and horizontally polarized, providing a supernormal ovipositional cue to Ephoron virgo, while other parts of the bridge were poor polarizers of lamplight. Collectively, we confirm that Ephoron virgo is independently attracted to both unpolarized and polarized light sources, that both types of photopollution are being produced at the bridge, and that spatial patterns of swarming and oviposition are consistent with evolved behaviors being triggered maladaptively by these two types of light pollution. We suggest solutions to bridge and lighting design that should prevent or mitigate the impacts of such scenarios in the future. The detrimental impacts of such scenarios may extend beyond Ephoron virgo.     

Organisation in the pelagic ecosystem

A continuous, steady-state theory has been developed for the abundance of organisms in the pelagic ecosystem as a function of their body weight. It is based on accepted relationships for the weight-dependence of metabolism and growth, in a context where individual organisms are assigned to one of a series of size classes for which the nominal weights increase in a geometric progression. Analysis of the biomass flow in such a representation leads to the conclusion that, in the steady state, the total biomass in any given size class decreases in a regular manner with increasing size. Explicitly,b(w ₂)/b(w ₁)~(w ₂/w ₁)^0.22, whereb(w ₂) andb(w ₁) are the total biomasses in the size classes characterised by weightsw ₂ andw ₁, respectively. The exponent (–0.22) represents a balance between catabolism and anabolism, based on published reviews concerning the revelant parameters. This result agrees favourably with data collected by other workers in the subtropical oceans. The theory can be used to draw conclusions about the functional dynamics of the pelagic ecosystem, such as community respiration and rate of biomass flow.     

Conformational aspects of polypeptides. XVII. Synthesis of oligomers and co-oligomers derived from L-alanine and L-glutamic acid

A series of oligomers was synthesized of the form: Where Z is the benzyloxycarbonyl group and n = 2, 3, 5, 10. We encountered difficulty in dissolving the decamer in any solvent except strong organic acids. We therefore prepared co-oligomers of the type: where (a) w = x = y = 1; (b) w = 0, x = y = 3; and (c) w = x = y = 3. A series of model compounds composed of glycine L -alamine and γ-methyl-L -glutamate were also prepared. We converted manyof the benzyloxycarbonyl oligopeptides into their corresponding acetyl derivatives. Some of these peptides were synthesized by mixed anhydride and active ester techniques while others were prepared via azide coupling techniques using the tert-butoxycarbonylhydrazide blocking group. All reactions proceeded with retention of configuration.     

Blue through UV polarization sensitivities in insects

A Signal-to-Noise optimization model has now been extended to explain the range of species-specific polarization sensitivities of insects. The different polarization sensitivities are shown to represent optimizations for the detection of plane polarized (Rayleigh-scattered) skylight over a range of atmospheric polarization conditions. Rhodopsin absorption spectra with peaks in the Blue (max450 nm) maximize detection efficiencies under conditions of high polarization. Rhodopsin absorption spectra peaking in the UV (max350 nm) maximize Signal-to-Noise Ratios for the detection of polarized skylight at the other extreme of low polarization.     

Surface area–volume ratios in insects

Body mass, volume and surface area are important for many aspects of the physiology and performance of species. Whereas body mass scaling received a lot of attention in the literature, surface areas of animals have not been measured explicitly in this context. We quantified surface area–volume (SA/V) ratios for the first time using 3D surface models based on a structured light scanning method for 126 species of pollinating insects from 4 orders (Diptera, Hymenoptera, Lepidoptera, and Coleoptera). Water loss of 67 species was measured gravimetrically at very dry conditions for 2 h at 15 and 30 °C to demonstrate the applicability of the new 3D surface measurements and relevance for predicting the performance of insects. Quantified SA/V ratios significantly explained the variation in water loss across species, both directly or after accounting for isometric scaling (residuals of the SA/V ～ mass^2/3 relationship). Small insects with a proportionally larger surface area had the highest water loss rates. Surface scans of insects to quantify allometric SA/V ratios thus provide a promising method to predict physiological responses, improving the potential of body mass isometry alone that assume geometric similarity.     

Duplication and diversification of trehalase confers evolutionary advantages on lepidopteran insects

Gene duplication provides a major source of new genes for evolutionary novelty and ecological adaptation. However, the maintenance of duplicated genes and their relevance to adaptive evolution has long been debated. Insect trehalase (Treh) plays key roles in energy metabolism, growth, and stress recovery. Here, we show that the duplication of Treh in Lepidoptera (butterflies and moths) is linked with their adaptation to various environmental stresses. Generally, two Treh genes are present in insects: Treh1 and Treh2. We report three distinct forms of Treh in lepidopteran insects, where Treh1 was duplicated into two gene clusters (Treh1a and Treh1b). These gene clusters differ in gene expression patterns, enzymatic properties, and subcellular localizations, suggesting that the enzymes probably underwent sub‐ and/or neofunctionalization in the lepidopteran insects. Interestingly, selective pressure analysis provided significant evidence of positive selection on duplicate Treh1b gene in lepidopteran insect lineages. Most positively selected sites were located in the alpha‐helical region, and several sites were close to the trehalose binding and catalytic sites. Subcellular adaptation of duplicate Treh1b driven by positive selection appears to have occurred as a result of selected changes in specific sequences, allowing for rapid reprogramming of duplicated Treh during evolution. Our results suggest that gene duplication of Treh and subsequent functional diversification could increase the survival rate of lepidopteran insects through various regulations of intracellular trehalose levels, facilitating their adaptation to diverse habitats. This study provides evidence regarding the mechanism by which gene family expansion can contribute to species adaptation through gene duplication and subsequent functional diversification.     

Synthesis,antitumour and antioxidant activities of novel α,β-unsaturated ketones and related heterocyclic analogues: EGFR inhibition and molecular modelling study

New α,β-unsaturated ketones 4a,b; 5a–c; and 6a,b; as well as 4-H pyran 7; pyrazoline 8a,b; isoxazoline 9; pyridine 10–11; and quinoline-4-carboxylic acid 12a,b derivatives were synthesized and evaluated for in vitro antitumour activity against HepG2, MCF-7, HeLa, and PC-3 cancer cell lines. Antioxidant activity was investigated by the ability of these compounds to scavenge the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS^?+). Compounds 6a, 6b, 7, and 8b exhibited potent antitumour activities against all tested cell lines with [IC₅₀] ?5.5–18.1 µΜ), in addition to significantly high ABTS^?+ scavenging activities. In vitro EGFR kinase assay for 6a, 6b, 7, and 8b as the most potent antitumour compounds showed that; compounds 6b, and 7 exhibited worthy EGFR inhibition activity with IC₅₀ values of 0.56 and 1.6?µM, respectively, while compounds 6a and 8b showed good inhibition activity with IC₅₀ values of 4.66 and 2.16?µM, respectively, compared with sorafenib reference drug (IC₅₀?=?1.28?µM). Molecular modelling studies for compounds 6b, 7, and 8b were conducted to exhibit the binding mode towards EGFR kinase, which showed similar interaction with erlotinib.     

Characterization of excitation beam on second-harmonic generation in fibrillous type I collagen

Following our established theoretical model to deal with the second-harmonic generation (SHG) excited by a linearly polarized focused beam in type I collagen, in this paper, we further quantitatively characterize the differences between SHG emissions in type I collagen excited by collimated and focused beams. The effects of the linear polarization angle (α) and the fibril polarity characterized by the hyperpolarizability ratio ρ on SHG emission has been compared under collimated and focused beam excitation, respectively. In particular, SHG emission components along the i axis ( I_2w,i )\left( {I_{2\omega {,}i} } \right) (i = x,y,z), the induced SHG emission deviation angle γ _ij , and the detected SHG signals (I _2ω,ij ) in the ij plane by rotating the applied polarizer angle φ _ij have been investigated (i = x, x, y; j = y, z, z). Results show that under our simulation model, SHG emission in the xy plane, such as I _2ω,x ,I _2ω,y ,γ _xy and I _2ω,xy varying as polarization angle (α) under collimated and focused light, presents no significant difference. The reverse of the fibril polarity has induced great impact on I _2ω,x ,γ _xy and I _2ω,xy in both collimated and focused light. I _2ω,x and γ _xy show similarity, but I _2ω,xy at α = 30° demonstrates a slight difference in focused light to that in collimated light. Under focused light, the reverse of fibril polarity causes obvious changes of the collected SHG intensity I _2ω,xz and I _2ω,yz at a special polarization angle α = 60° and γ _xz , γ _yz along α.     

昆虫水平基因转移及其研究进展

水平基因转移(horizontal gene transfer, HGT)是生物体获得遗传信息的方式之一,对生物体进化起重要作用。近年来,越来越多昆虫中的水平基因转移现象被报道,如在鳞翅目(如家蚕、甜菜夜蛾、小菜蛾、斜纹夜蛾)、半翅目(如柑橘粉蚧、烟粉虱)、鞘翅目(如咖啡果小蠹、米象、光肩星天牛)、膜翅目(如金小蜂)、双翅目(如果蝇、白纹伊蚊)等昆虫中广泛存在水平转移基因,且不同的水平转移基因对昆虫的营养合成与共生、吸收与消化、毒素产生与解毒、生长和发育、体色改变等方面有着重要作用。本文结合国内外专家学者的相关报道,就HGT的研究步骤与技术方法、评判HGT发生的方法、昆虫HGT的供体与功能几个方面进行了总结和讨论,以期更加深入地了解水平基因转移现象,为探究水平基因转移的作用机制、理解昆虫的进化、遗传和行为、并将水平基因转移应用到农业生产中为农业害虫的绿色防治提供更多思路。     

Bacillus thuringiensis isolates from soil and diseased insects in Egyptian cotton fields and their activity against lepidopterous insects

The distribution of Bacillus thuringiensis in Egyptian soils of cotton cultivations represented by 11 governorates was studied. This study aimed to isolate indigenous strains that may be potent against some lepidopterous insect pests. Out of 45 isolates, only 10 were effective and they showed high levels of toxicity against the target insects at 500 μg/ml (80% larval mortality or higher). Among these 10 isolates, two isolates were potent against Spodoptera littoralis, two isolates were potent against Helicoverpa (= Heliothis) armigera, seven isolates were potent against Pectinophora gossypiella, but none were potent against Agrotis ypsilon. LC₅₀ and LC₉₀ values and the potency of the B. thuringiensis isolates have been determined. Trials were conducted to isolate B. thuringiensis from diseased lepidopterous insects collected from the same locations, but all isolates showed low potential activity against the target insects. These findings showed promise for the possible use of some indigenous B. thuringiensis strains in the control of lepidopterous pests in Egypt.     

Urinary excretion of 1-hydroxypyrene as a biomarker of exposure to polycyclic aromatic hydrocarbons from different sources

1-Hydroxypyrene (1-OHP) urinary excretion has been studied in subjects exposed to polycyclic aromatic hydrocarbons (PAH) from different sources (urban air pollution, cigarette smoking, food contamination or occupational exposure). In Study A, statistically significant differences among subjects categorized according to daily cigarette consumption were observed: 1-OHP median excretion of heavy smokers (more than 20 cigarettes per day; 1-OHP=371 ng l^-1; n=6) was significantly increased over that of non-smokers (1-OHP=160 ng l^-1; n=79), light smokers (less than 10 cigarettes per day,1-OHP=157 ng l^-1; n=7) and also medium smokers (10-20 cigarettes per day, 1-OHP=154 ng l^-1; n=13) (p&lt;0.04). In smokers, 1-OHP excretion (y, ng l^-1) increased with the intensity of cigarette consumption and was associated with self-reported number of cigarettes smoked daily (x, n) (y=20+16.6x; r=0.58, n=22, p&lt;0.01), urinary thiocyanate (x, µmoll^-1) (y=55+2.6x; r=0.57, n=20, p&lt;0.01) and cotinine (x, µg l^-1) (y=89+0.23x; r=0.62, n=17, p&lt;0.01). In Study B the influence of smoked food consumption on 1-OHP excretion was evaluated: 1-OHP excretion began to increase as soon as 3 h after a PAH-rich meal and peak values were reached between 6 and 9 h after lunch. Maximum excretion mean values were respectively 525 ng l^-1 for non-smokers (n=8) and 650 ng l^-1 for smokers (n= 4). 1-OHP concentrations in next-morning samples were back to pre-lunch levels both for non-smokers and smokers. In Study C non-smoker workers (n=28) occupationally exposed to PAH in a steel plant were investigated. At values of airborne pyrene ranging between 6 and 30 µg m^-3, excretion values of 1-OHP up to 80000 ng l^-1 were observed. The use of urinary 1-OHP as a screening test to discriminate between smokers and non-smokers in the presence of uncorrected dietary influence has been calculated according to a cut-off value of 461 ng l^-1 (reference group upper limit): the 1-OHP positive predictive value is 57%, its predictive negative value is 77%, sensitivity is 15% and specificity is 96%. In conclusion, 1-OHP appears to be a valuable biomarker of pyrene exposure. It will be nevertheless more accurate in assessing human PAH exposure from multiple sources if the influence of different kinetics for inhaled (particulate or gaseous) or ingested PAH are considered and if the role of oxidative polymorphism is adequately elucidated. The possibility of using 1-OHP to estimate the total burden of PAH from different sources or of screening groups with different PAH exposure appears to be a possible approach. However, the use of 1-OHP to evaluate the associated risk of cancer is still a premature target.     

Synthesis and potential antitumor activity of 7-(4-substituted piperazin-1-yl)-4-oxoquinolines based on ciprofloxacin and norfloxacin scaffolds: in silico studies

The potential antitumor activities of a series of 7-(4-substituted piperazin-1-yl)fluoroquinolone derivatives (1–14a,b) using ciprofloxacin and norfloxacin as scaffolds are described. These compounds exhibit potent and broad spectrum antitumor activities using 60 human cell lines in addition to the inherent antibacterial activity. Compounds 1a, 2a, 3b, 6b and 7a were found to be the most potent, while 2b, 5b, and 6a were found to have an average activity. The results of this study demonstrated that compounds 1a, 2a, 3b, 6b and 7a (mean GI₅₀; 2.63–3.09?µM) are nearly 7-fold more potent compared with the positive control 5-fluorouracil (mean GI₅₀; 22.60?µM). More interestingly, compounds 1a, 2a, 3b, 6b and 7a have an almost antitumor activity similar to gefitinib (mean GI₅₀; 3.24?µM) and are nearly 2-fold more potent compared to erlotinib (mean GI₅₀; 7.29?µM). In silico study and ADME-Tox prediction methodology were used to study the antitumor activity of the most active compounds and to identify the structural features required for antitumor activity.