121 research outputs found

    The BRST treatment of stretched membranes

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    The BRST-invariant formulation of the bosonic stretched membrane is considered. In this formulation the stretched membrane is given as a perturbation around zero-tension membranes, where the BRST-charge decomposes as a sum of a string-like BRST-charge and a perturbation. It is proven, by means of cohomology techniques, that there exists to any order in perturbation theory a canonical transformation that reduces the full BRST-charge to the string-like one. It is also shown that one may extend the results to the quantum level yielding a nilpotent charge in 27 dimensions.Comment: 21 pages, typo's corrected, minor changes in the tex

    Ambient and substrate energy influence decomposer diversity differentially across trophic levels

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    The species-energy hypothesis predicts increasing biodiversity with increasing energy in ecosystems. Proxies for energy availability are often grouped into ambient energy (i.e., solar radiation) and substrate energy (i.e., non-structural carbohydrates or nutritional content). The relative importance of substrate energy is thought to decrease with increasing trophic level from primary consumers to predators, with reciprocal effects of ambient energy. Yet, empirical tests are lacking. We compiled data on 332,557 deadwood-inhabiting beetles of 901 species reared from wood of 49 tree species across Europe. Using host-phylogeny-controlled models, we show that the relative importance of substrate energy versus ambient energy decreases with increasing trophic levels: the diversity of zoophagous and mycetophagous beetles was determined by ambient energy, while non-structural carbohydrate content in woody tissues determined that of xylophagous beetles. Our study thus overall supports the species-energy hypothesis and specifies that the relative importance of ambient temperature increases with increasing trophic level with opposite effects for substrate energy

    Ambient and substrate energy influence decomposer diversity differentially across trophic levels.

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    The species-energy hypothesis predicts increasing biodiversity with increasing energy in ecosystems. Proxies for energy availability are often grouped into ambient energy (i.e., solar radiation) and substrate energy (i.e., non-structural carbohydrates or nutritional content). The relative importance of substrate energy is thought to decrease with increasing trophic level from primary consumers to predators, with reciprocal effects of ambient energy. Yet, empirical tests are lacking. We compiled data on 332,557 deadwood-inhabiting beetles of 901 species reared from wood of 49 tree species across Europe. Using host-phylogeny-controlled models, we show that the relative importance of substrate energy versus ambient energy decreases with increasing trophic levels: the diversity of zoophagous and mycetophagous beetles was determined by ambient energy, while non-structural carbohydrate content in woody tissues determined that of xylophagous beetles. Our study thus overall supports the species-energy hypothesis and specifies that the relative importance of ambient temperature increases with increasing trophic level with opposite effects for substrate energy

    Erythrocyte and Porcine Intestinal Glycosphingolipids Recognized by F4 Fimbriae of Enterotoxigenic Escherichia coli

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    Enterotoxigenic F4-fimbriated Escherichia coli is associated with diarrheal disease in neonatal and postweaning pigs. The F4 fimbriae mediate attachment of the bacteria to the pig intestinal epithelium, enabling an efficient delivery of diarrhea-inducing enterotoxins to the target epithelial cells. There are three variants of F4 fimbriae designated F4ab, F4ac and F4ad, respectively, having different antigenic and adhesive properties. In the present study, the binding of isolated F4ab, F4ac and F4ad fimbriae, and F4ab/ac/ad-fimbriated E. coli, to glycosphingolipids from erythrocytes and from porcine small intestinal epithelium was examined, in order to get a comprehensive view of the F4-binding glycosphingolipids involved in F4-mediated hemagglutination and adhesion to the epithelial cells of porcine intestine. Specific interactions between the F4ab, F4ac and F4ad fimbriae and both acid and non-acid glycosphingolipids were obtained, and after isolation of binding-active glycosphingolipids and characterization by mass spectrometry and proton NMR, distinct carbohydrate binding patterns were defined for each fimbrial subtype. Two novel glycosphingolipids were isolated from chicken erythrocytes, and characterized as GalNAcα3GalNAcß3Galß4Glcß1Cer and GalNAcα3GalNAcß3Galß4GlcNAcß3Galß4Glcß1Cer. These two compounds, and lactosylceramide (Galß4Glcß1Cer) with phytosphingosine and hydroxy fatty acid, were recognized by all three variants of F4 fimbriae. No binding of the F4ad fimbriae or F4ad-fimbriated E. coli to the porcine intestinal glycosphingolipids occurred. However, for F4ab and F4ac two distinct binding patterns were observed. The F4ac fimbriae and the F4ac-expressing E. coli selectively bound to galactosylceramide (Galß1Cer) with sphingosine and hydroxy 24:0 fatty acid, while the porcine intestinal glycosphingolipids recognized by F4ab fimbriae and the F4ab-fimbriated bacteria were characterized as galactosylceramide, sulfatide (SO3-3Galß1Cer), sulf-lactosylceramide (SO3-3Galß4Glcß1Cer), and globotriaosylceramide (Galα4Galß4Glcß1Cer) with phytosphingosine and hydroxy 24:0 fatty acid. Finally, the F4ad fimbriae and the F4ad-fimbriated E. coli, but not the F4ab or F4ac subtypes, bound to reference gangliotriaosylceramide (GalNAcß4Galß4Glcß1Cer), gangliotetraosylceramide (Galß3GalNAcß4Galß4Glcß1Cer), isoglobotriaosylceramide (Galα3Galß4Glcß1Cer), and neolactotetraosylceramide (Galß4GlcNAcß3Galß4Glcß1Cer)

    Pherbellia jalili Mortelmans & Kazerani 2020, sp. nov.

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    <i>Pherbellia jalili</i> Mortelmans & Kazerani sp. nov. <p>(Figs. 2 – 5)</p> <p> <b>Holotype</b>: ♂ Iran, Golestan Province, Shast-Kola forests, 36°44’12’’N, 54°24’15’’E, 814 m, pan trap, 10.vi.2017, Farzaneh Kazerani leg., [IMBGI].</p> <p> <b>Paratypes</b>: 2♂, Iran, Golestan Province, Shast-Kola forests, 36°43’10”N, 54°24’17”E, 817 m, net-sweeping, 10.vi.2017, Farzaneh Kazerani leg [one was completely crushed for barcoding; the other is in the personal collection of the second author]; 2♀, Iran, Golestan Province, Shast-Kola forests, 36°43’10’’N, 54°24’17’’E, 817 m, net-sweeping, 10.vi.2017, Farzaneh Kazerani leg [IMBGI]; 2♂, Iran, Golestan Province, Shast-Kola forests, 36°43’00.7”N, 54°23’13.7’’E, 1271 m, pan traps, 12.vi.2017, Farzaneh Kazerani leg [IMBGI]; 2♀, Iran: Mazanda- ran Province, Neka forests, 36°21ʹ43.03”N, 53°32ʹ56.7’’E, 1495 m, net-sweeping, 15.vii.2018, Farzaneh Kazerani leg [IMBGI].</p> <p> <b>Diagnosis:</b> This new species of <i>Pherbellia</i> is similar to <i>P. annulipes</i> but differs in the color of the femora, black in <i>P. annulipes,</i> yellow in <i>P. jalili</i>. Especially in the shape of the surstyli is characteristic: rounded in <i>P. annulipes,</i> blunt in <i>P. jalili</i>.</p> <p> <b>FIG 2.</b> Lateral view of a male paratype of <i>Pherbellia jalili</i>. <b>FIG 3.</b> Detailed lateral view of a male paratype of <i>Pherbellia jalili</i>, showing especially the setulation on the pleura. <b>FIG 4.</b> Lateral view of andrium of a male paratype of <i>P. jalili.</i> Scale bar = 0.5 mm.</p> <p> <b>FIG 5.</b> Ventral view of andrium of a male paratype of <i>P. jalili.</i> Scale bar = 0.5 mm.</p> <p> <b>Description:</b> Body length 4.21 mm (excluding antennae); wing length 4.17 mm. <i>Head</i>: Ground color yellow except upper 2/3 of occiput, frontal vitta, ocellar triangle, eye margins, and orbital plates dark brown with grayish pubescence (Fig. 2). Frontal vitta subshining, nearly as broad as ocellar triangle and pointed anteriorly, not reaching half the distance from anteriormost point of ocellar triangle to anterior margin of frons. Face concave in lateral view. Oral margin slightly protruding. Two orbital setae, anterior seta about 2/3 the length of posterior seta. Antennae yellowish. Scape short, yellowish. Pedicel oval, yellow with short black seta, darkened in the apical half. Arista implanted at basodorsal margin of flagellomere. Arista yellow, twice as long as height of yellow flagellomere, with uniformly short, sparse setulae to apex, setulae barely longer than arista at base. Face and gena silvery white, gena about 1/4 height of the eye. Palpus entirely yellow. Proboscis yellow. <i>Thorax and abdomen</i>: Scutum dark brown, dusted gray, covered by hairlike black setulae and with a grayish median stripe and a pair of broad, grayish, pruinose dorsocentral stripes; scutellum uniformly grayish pubescent with broad median brown stripe. Pleura dark brown, dusted grayish golden; proepisternum yellow with one ventral seta; anepisternum yellow with brown stripe on upper margin, bare except for 2–3 setulae ventral to the anterior spiracle; anepimeron with two strong setae and a cluster of 4–5 short setulae; katepisternum setulose (Fig. 3). Mesonotal chaetotaxy: two strong humeral, four notopleurals, two presutural supra-alar, four postsutural supra-alars, four dorsocentrals, two acrostichal, and four scutellars (two basal, two apical). Halter base and stem yellowish with knob slightly infuscated. Calypter small and dark, its margin yellow, with several long yellow setae. All pleura with slight yellowish pubescence. Abdomen yellow except for brown anterior margins of each tergite, these brown bands covered with gray pubescence. All sternites dull grayish, without distinct markings, covered with hairlike black setulae. <i>Legs</i>: Fore coxa yellow with shiny silvery pubescence and a few strong setae, mid and hind coxa yellow with dull white pubescence. Fore femur yellow in anterior and posterior lateral view, dorsal side and apex slightly black, mid- and hind femur yellow, apex darkened. Fore tibia mainly black, slightly yellowish at the base, mid tibia yellow and slightly darkened apically, hind tibia yellow, darkened at the base and apex; fore tarsus black, basitarsus white, mid and hind tarsomeres white. <i>Wing</i>: heavily darkened along costal margin and crossveins, apex slightly darkened. Vein A 1 +CuA 2 reaching wing margin. All veins black except vein Sc yellow. <i>Genital apparatus</i>: Epandrium rounded. Cerci small, yellow. Posterior surstyli large, broader in apical half, triangular with blunt apex, covered with dense black setae, anterior surstyli small, triangular, apex with several short black setae. Both pairs of surstyli protruded ventrally below the andrium (Fig. 3, 4).</p> <p> <b>Female</b>: Similar to male except for more extensively black forefemur and foretarsus.</p> <p> <b>Etymology:</b> The species is named after Prof. Adel Jalili (Research Institute of Forests and Rangelands) for his prominent supporting role in biodiversity studies in Iran.</p> <p> <b>Distribution:</b> <i>Pherbellia jalili</i> is known only from the Hyrcanean forest in Iran, (Fig. 1).</p> <p> <b>Ecology:</b> Nothing is known of the biology of <i>P. jalili</i> except that adults dwell in the Hyrcanean deciduous forests and is probably a typical representative of deciduous forests. This ecoregion in northern Iran lies in a mountainous humid zone and is covered with temperate deciduous forests, known to hold high degrees of endemism (Kazerani <i>et al.</i> 2016).</p>Published as part of <i>Kazerani, Farzaneh, Mortelmans, Jonas, Farashiani, Mohammad Ebrahim & Thorn, Simon, 2020, A new species of Pherbellia (Diptera: Sciomyzidae) from Iran, pp. 361-370 in Zootaxa 4772 (2)</i> on pages 363-366, DOI: 10.11646/zootaxa.4772.2.7, <a href="http://zenodo.org/record/3816562">http://zenodo.org/record/3816562</a&gt

    A new species of Pherbellia (Diptera: Sciomyzidae) from Iran

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    Kazerani, Farzaneh, Mortelmans, Jonas, Farashiani, Mohammad Ebrahim, Thorn, Simon (2020): A new species of Pherbellia (Diptera: Sciomyzidae) from Iran. Zootaxa 4772 (2): 361-370, DOI: https://doi.org/10.11646/zootaxa.4772.2.
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