1,354 research outputs found
On the mass radiated by coalescing black hole binaries
Get PDFWe derive an analytic phenomenological expression that predicts the final mass of the black hole (BH) remnant resulting from the merger of a generic binary system of BHs on quasi-circular orbits. Besides recovering the correct test-particle limit for extreme mass-ratio binaries, our formula reproduces well the results of all the numerical-relativity simulations published so far, both when applied at separations of a few gravitational radii and when applied at separations of tens of thousands of gravitational radii. These validations make our formula a useful tool in a variety of contexts ranging from gravitational-wave (GW) physics to cosmology. As representative examples, we first illustrate how it can be used to decrease the phase error of the effective-one-body waveforms during the ringdown phase. Second, we show that, when combined with the recently computed self-force correction to the binding energy of nonspinning BH binaries, it provides an estimate of the energy emitted during the merger and ringdown. Finally, we use it to calculate the energy radiated in GWs by massive BH binaries as a function of redshift, using different models for the seeds of the BH population
Entoloma argus O. V. Morozova, E. S. Popov, A. V. Alexandrova & Noordeloos 2022, sp. nov.
No full textEntoloma argus O.V. Morozova, E.S. Popov, A.V. Alexandrova & Noordeloos, sp. nov. (Figs. 3, 4) Mycobank: MB 843250 Type:— VIETNAM. Gia Lai Province, K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, N 14.505520°, E 108.541610°, 1050 m a.s.l., on soil in middle-mountain evergreen mixed forest with a predominance of Podocarpaceae (Dacrydium elatum, Dacrycarpus imbricatus), Magnoliaceae, Burseraceae (Canarium), Myrtaceae (Syzygium), 26 May 2016, O.V. Morozova (holotype: LE F-312694 (!), isotype in VRTC (!), ITS sequence GenBank OM987263, LSU sequence GenBank OM996175). Etymology:—Ἄργος (Greek), Argus (Lat.) a character from ancient Greek mythology. Argos was a one hundred-eyed giant who paid a service to the goddess Hera. Zeus killed the giant, but Hera remembered the giant by placing his one hundred eyes on the tail of the peacock. His name is used in various combinations in the generic and species names of butterflies of the Lycaenidae (Cupidinidae) family. The new Entoloma species is named after the butterfly Plebejus argus, due to the similarity of color. Diagnosis:— Entoloma argus is characterized by the delicate greyish blue basidiomata with the distinctly translucently striate pileus covered by small dark blue squamules on a paler greyish blue background with contrasting dark blue centre, and the smooth, polished stipe concolorous with pileus. Microscopically, the sterile lamella edge of cylindrical to narrowly clavate colorless cystidia, and rather small 5–6 angled spores are characteristic. Description:— Basidiomata small to medium-sized, collybioid. Pileus 15‒25 mm diam., hemispherical to convex soon expanding to plano-convex with flat to slightly depressed centre, with deflexed then straight margin, hygrophanous, translucently striate almost up to the centre, greyish blue (21 C –D4–7), covered with dark blue squamules, glabrescent with age and discoloring to greyish beige, with dark blue (21 F 6–8) fibrillose center. Lamellae moderately distant, adnate-emarginate, ventricose, white, becoming pinkish, with entire edge concolorous with faces. Stipe 30–60 × 1–1.5 mm, cylindrical, smooth, polished, greyish blue, concolorous with pileus (21 C –D4–7), with white tomentum at base. Context white, greyish under the surface. Smell indistinct, taste not reported. Basidiospores (8.5–)9.5–10(–11.4) × (6.0–)6.5–7(–7.5) μm, Q = (1.3–)1.45–1.5(–1.6), heterodiametrical, with 5–6 angles in side-view. Basidia 24–34 × 8.5–11.5 μm, 1–2-spored or 4-spored, narrowly clavate to clavate, clampless. Cheilocystidia 33–53 × 7.5–14 μm, cylindrical to narrowly clavate, sometimes septate, not pigmented, forming a sterile lamellae edge. Pileipellis a cutis of cylindrical hyphae 2–7 μm diam with trichodermal bundles of ascending hyphae with cylindrical to narrowly clavate terminal elements (46–86 × 14–20 μm) forming the macroscopic squamules and central disk of pileus. Clamp connections absent. Habitat and distribution:—In small groups in middle-mountain evergreen mixed forests. Known from Vietnam. Additional specimens examined:— VIETNAM. Gia Lai Province, K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, on soil in middle-mountain evergreen mixed forest with a predominance of Podocarpaceae (Dacrydium elatum, Dacrycarpus imbricatus), Magnoliaceae, Burseraceae (Canarium), Myrtaceae (Syzygium), path to the waterfall, N 14.51361°, E 108.54621°, 1007 m a.s.l., 25 May 2016, A. Alexandrova (LE F-315916 (!), ITS sequence GenBank OM 987264); ibid., N 14.505520°, E 108.541610°, 1050 m a.s.l., 28 May 2016, I. Semenyuk and E. Popov (LE F-312695 (!), ITS sequence GenBank OM 987262); ibid., on the river bank, 28 May 2016, O. V. Morozova (LE F-315915 (!), ITS sequence GenBank OM 987265). Notes:— Entoloma argus is distinguished from the macromorphologically similar E. ekaterinae O.V. Morozova, Noordel., K. Nara, Dima & Brandrud, in Crous et al. (2019: 413) from the Russian Far East by the more applanate pileus, different pileipellis structure and shape of the cheilocystidia (cylindrical vs. broadly clavate and subglobose). E. subcaesiellum Noordeloos & O.V. Morozova (2010: 243) also described from the Russian Far East possesses a less squamulose pileus with blue squamules on a greyish beige background and microscopically lacks a distinct trichoderm at pileal center. The European E. phaeodiscum Vila & F. Caballero (2007: 41) differs by the absence of cheilocystidia, less pronounced, fading blue coloration, and geographical distribution.Published as part of Morozova, Olga, Popov, Eugene, Alexandrova, Alina, Pham, Thi Ha Giang & Noordeloos, Machiel Evert, 2022, Four new species of Entoloma (Entolomataceae, Agaricomycetes) subgenera Cyanula and Claudopus from Vietnam and their phylogenetic position, pp. 1-21 in Phytotaxa 549 (1) on pages 8-10, DOI: 10.11646/phytotaxa.549.1.1, http://zenodo.org/record/660526
Mathematical Modelling of Cancer Stem Cells Population Behavior
No full textRecent discovery of cancer stem cells in tumorigenic tissues has raised many questions about their nature, origin, function and their behavior in cell culture. Most of current experiments reporting a dynamics of cancer stem cell populations in culture show the eventual stability of the percentages of these cell populations in the whole population of cancer cells, independently of the starting conditions. In this paper we propose a mathematical model of cancer stem cell population behavior, based on specific features of cancer stem cell divisions and including, as a mathematical formalization of cell-cell communications, an underlying field concept. We compare the qualitative behavior of mathematical models of stem cells evolution, without and with an underlying signal. In absence of an underlying field, we propose a mathematical model described by a system of ordinary differential equations, while in presence of an underlying field it is described by a system of delay differential equations, by admitting a delayed signal originated by existing cells. Under realistic assumptions on the parameters, in both cases (ODE without underlying field, and DDE with underlying field) we show in particular the stability of percentages, provided that the delay is sufficiently small. Further, for the DDE case (in presence of an underlying field) we show the possible existence of, either damped or standing, oscillations in the cell populations, in agreement with some existing mathematical literature. The outcomes of the analysis may offer to experimentalists a tool for addressing the issue regarding the possible non-stem to stem cells transition, by determining conditions under which the stability of cancer stem cells population can be obtained only in the case in which such transition can occur. Further, the provided description of the variable corresponding to an underlying field may stimulate further experiments for elucidating the nature of "instructive" signals for cell divisions, underlying a proper pattern of the biological system
E. K. Breško-Breškovskaja na gastroljach v SŠA, oktjabr’ 1904 - mart 1905 g. Die russische sozialrevolutionäre Befreiungsbewegung, transnationale Öffentlichkeit und US-Dollars
No full textHäfner L. E. K. Breško-Breškovskaja na gastroljach v SŠA, oktjabr’ 1904 - mart 1905 g. Die russische sozialrevolutionäre Befreiungsbewegung, transnationale Öffentlichkeit und US-Dollars. In: Morozova AJ, Suslov AJ, eds. Žit’ istoriej i dumat’ o buduščem: Sbornik statej i materialov k 60-letiju doktora istoričeskich nauk K. N. Morozova. Moskau: bez izdatel'stva; 2021: 235-245
Micropsalliota suricatoides D. D. Ivanova, O. V. Morozova & T. H. G. Pham 2023, sp. nov.
No full text<i>Micropsalliota suricatoides</i> D.D. Ivanova, O.V. Morozova & T.H.G. Pham, <i>sp. nov.</i> (Fig. 5) <p>Mycobank: MB849328</p> <p> Type:— VIETNAM, Dong Nai Province: Vinh Cuu District, Dong Nai Cultural and Nature Reserve, tropical polydominant mixed forest, on soil, 13.06.2011, coll. <i>O. V. Morozova</i>, 280 VN 11 (holotype: LE F-348072!, isotype: VRTC!).</p> <p> Etymology:—Referring to beige clusters of basidiomata with fine fibrillose squamules on caps that remind mobs of meerkats (<i>Suricata suricata</i>).</p> <p>Diagnosis:—This species is characterized by having small size of beige basidiomata, staining yellow when bruised, pileus with brown squamules, utriform and lageniform cheilocystidia, and stipitipellis hyphae with capitate apices.</p> <p> Description: <i>Basidiomata</i> small, beige when fresh, yellow when bruised (3 B 7–8), discoloring to light brown (6D4), brown (6 E 6–4) or dark brown (6 F 4–7) when dried. <i>Pileus</i> 4–13 mm in diameter, campanulate when young, convex when mature; surface dry, beige, brownish orange, greyish orange (5 C 3, 5 B 3), squamulose, darker towards the center due to presence of fine, fibrillose, brown (7 E 8–5) squamules which are located denser in the center; margin white or beige, fibrillose; the surface reddish brown (8 E 4) in KOH. <i>Lamellae</i> free, crowded, 1 mm broad, cream, intercalated with lamellulae. <i>Stipe</i> 16–28 × 0.5–1 mm, cylindrical, greyish brown (6D3) or brownish beige (6 E 3); covered with tiny white fibrillose scales. <i>Annulus</i> persistent, pendent, single, white or concolorous with the pileus.</p> <p> <i>Basidiospores</i> (4.2–)5.4–6.7 × (2.7–)3.2–4.5 µm, Q = 1.31–1.82, Q m = 1.6 (n = 21), amygdaliform in side view, ellipsoid in frontal view, with apical endosporal thickening. <i>Basidia</i> (12–)13.6–14.8(–16.9) × 5.4–6.9 µm, clavate, 2- and 4-spored, hyaline. <i>Cheilocystidia</i> (13.7–)19.5–22.0(–30.2) × (5.1–)9.3–8.8(–13.5) µm, utriform and lageniform, necks and capitula absent. <i>Pleurocystidia</i> absent. <i>Pileipellis</i> a cutis, composed of hyphae 5–8(–10) µm, constricted at the septa, incrusted with brownish pigment. <i>Stipitipellis</i> of cylindrical hyphae 5–8 μm wide, many with capitate apices.</p> <p>Habitat and distribution:—In small groups on soil in tropical evergreen mixed forest. Known only from the type locality in southern Vietnam.</p> <p> Additional specimens examined: VIETNAM, Dong Nai Province:Vinh Cuu District, Dong Nai Cultural and Nature Reserve, tropical polydominant mixed forest, on soil, 14 June 2011, coll. <i>O. V. Morozova</i> LE F-348071 (303 VN 11). Gia Lai Province: K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, polydominant evergreen broadleaf, mixed (dominated by trees from Podocarpaceae, Theaceae, Magnoliaceae, Fagaceae, Hamamelidaceae, Lauraceae, Burseraceae, Myrtaceae, Clusiaceae, Fabaceae) and coniferous (dominated by <i>Dacrydium elatum</i>) forest, 14°28’09.9”N 108°32’24.8”E, elevation 923 m, on soil, 28 October 2022, LE F-348070 (209 NVP 22), coll. <i>N. V. Psurtseva</i>; 27 October 2022, coll. <i>V. A. Dudka</i>, LE F-348069 (222 VN 22).</p> <p> Notes: <i>Micropsalliota suricatoides</i> is characterized by having small basidiomata, basidiomata staining yellow when bruised, beige pileus with brown squamules, utriform and lageniform cheilocystidia, pileipellis hyphae with brownish pigment and stipitipellis hyphae with capitate apices. Two of the specimens from Vietnam has a distinguishable dark umbo (LE F-348070 and LE F-348069). <i>Micropsalliota brunneola</i> Heinem. possesses a larger (20-30 mm in diameter) brown squamulose pileus without umbo, smaller spores (4.1–4.9 × 2.9–3.3 μm), much broader pileipellis hyphae of 8–20 μm in diameter (Heinemann 1980: 46). <i>Micropsalliota allantoidea</i> R.L. Zhao, Desjardin, K. Soytong & K. D. Hyde shares scaly convex pileus, but has brown lamellae, ventricose-capitate cheilocystidia and pileipellis hyphae 8–17 μm in diameter (Zhao <i>et al.</i> 2010: 15). <i>Micropsalliota megaspora</i> R.L. Zhao, Desjardin, Soytong & K.D. Hyde has larger spores (6–8 × 3.8–4.5 μm), ventricose to pyriform cheilocystidia, broader pileipellis hyphae 10–22 μm in diameter. (Zhao <i>et al.</i> 2010: 64). <i>Micropsalliota brunneosquamata</i> L.J. Chen, R.L. Zhao & K.D. Hyde possesses much bigger basidiomata (pileus 31–40 mm in diameter), stipe heavily covered by brown fibrils under annulus with bulbous base, cheilocystidia various in shape, and broader pileipellis hyphae 5–25μm diameter (Chen <i>et al.</i> 2016: 692).</p>Published as part of <i>Ivanova, Daria, Morozova, Olga & Pham, Thi Ha Giang, 2023, Three new species of Micropsalliota (Agaricaceae, Basidiomycota) from central and southern Vietnam, pp. 247-258 in Phytotaxa 626 (4)</i> on pages 254-255, DOI: 10.11646/phytotaxa.626.4.2, <a href="http://zenodo.org/record/10212911">http://zenodo.org/record/10212911</a>
Entoloma daphnis O. V. Morozova, Kovalenko, E. S. Popov & Noordeloos 2022, sp. nov.
No full textEntoloma daphnis O.V. Morozova, Kovalenko, E.S. Popov & Noordeloos, sp. nov. (Figs. 9, 10) Mycobank: MB 843253 Type:— VIETNAM. Dong Nai Prov., Tan Phu Dist., Cat Tien National Park, “ Lagerstroemia trail” near the Park’s Headquarters, N 11.426667°, E 107.426389°, 125 m a.s.l., on fallen log in lowland semi-deciduous tropical forest, 14 June 2010, A. Kovalenko (holotype: LE F-262915 (!), as Entoloma nubilum in Morozova et al. 2012, ITS sequence GenBank OM987266, LSU sequence GenBank OM996177). Etymology:—Δάφνις, from δάφνη–laurel (Greek), in Greek mythology, a beautiful young shepherd in Sicily and inventor of pastoral songs, the son of Hermes (Mercury). The butterfly Polyommatus daphnis was named after him. The new Entoloma species is named after this butterfly, due to the similar color. Diagnosis:— Entoloma daphnis is characterized by small pleurotoid basidiomata, small spores with up to the 8 angles, a trichodermal pileipellis (pileus is densely covered by dark blue fibrils) and lack of cheilocystidia. Description:— Basidiomata small, pleurotoid. Pileus 3–7 mm diam., cupulate then reniform with incurved then lobate margin, non hygrophanous, slightly translucently striate, tomentose to finely squamulose, deep blue to dark blue (20D8, 20E7–8). Lamellae moderately distant intermixed with lamellulae, adnate or slightly emarginate, whitish to bluish near the pileal margin then pinkish with concolorous entire edge. Stipe 3–4 × 0.5–1 mm, reduced, eccentric or lateral, curved, pruinose to tomentose, concolorous with the pileus or slightly paler (20D7), with white arachnoid mycelial strands at the base attached to the substratum. Context thin, bluish, under the surface dark blue. Odor indistinct, taste not reported. Basidiospores (7–)8.3(–9) × (5.5–)5.7(–6) μm, Q = (1.3–)1.45(–1.6), heterodiametrical, with 6–8 angles in sideview. Basidia 23–31 × 9–12 μm, clavate, clampless. Lamellae edge fertile. Cheilocystidia and pleurocystidia absent. Pileipellis a trichoderm of long hairs, composed of chains of cylindrical cells narrower at the apical part (27–62 × 5.5–6.5 μm), broader at the base (27–62 × 5.5–6.5 μm) with dark blue intracellular pigment. Clamp connections, oleiferous hyphae and brilliant granules absent. Notes:— Entoloma cyanomelaenum possesses larger (9–11 × 5.5–6.5 μm) spores and its pileus turns red in KOH (Boedijn 1929; Horak 1980); E. gainsvillae has slightly larger spores (8–10 × 6–7 μm) and a smooth pileus (Murrill 1943; Hesler 1967); E. nubilum differs from E. daphnis by differently-shaped (5–7 angled) spores, a cutis-type pileipellis, and habitat on decaying leaves or on humus (Manimohan et al. 2002); E. icarus possesses larger (10–13 × 7–9 μm) differently-shaped (with 5–7 sharp angles) spores and cheilocystidia.Published as part of Morozova, Olga, Popov, Eugene, Alexandrova, Alina, Pham, Thi Ha Giang & Noordeloos, Machiel Evert, 2022, Four new species of Entoloma (Entolomataceae, Agaricomycetes) subgenera Cyanula and Claudopus from Vietnam and their phylogenetic position, pp. 1-21 in Phytotaxa 549 (1) on pages 15-16, DOI: 10.11646/phytotaxa.549.1.1, http://zenodo.org/record/660526
Entoloma daphnis O. V. Morozova, Kovalenko, E. S. Popov & Noordeloos 2022, sp. nov.
No full textEntoloma daphnis O.V. Morozova, Kovalenko, E.S. Popov & Noordeloos, sp. nov. (Figs. 9, 10) Mycobank: MB 843253 Type:— VIETNAM. Dong Nai Prov., Tan Phu Dist., Cat Tien National Park, “ Lagerstroemia trail” near the Park’s Headquarters, N 11.426667°, E 107.426389°, 125 m a.s.l., on fallen log in lowland semi-deciduous tropical forest, 14 June 2010, A. Kovalenko (holotype: LE F-262915 (!), as Entoloma nubilum in Morozova et al. 2012, ITS sequence GenBank OM987266, LSU sequence GenBank OM996177). Etymology:—Δάφνις, from δάφνη–laurel (Greek), in Greek mythology, a beautiful young shepherd in Sicily and inventor of pastoral songs, the son of Hermes (Mercury). The butterfly Polyommatus daphnis was named after him. The new Entoloma species is named after this butterfly, due to the similar color. Diagnosis:— Entoloma daphnis is characterized by small pleurotoid basidiomata, small spores with up to the 8 angles, a trichodermal pileipellis (pileus is densely covered by dark blue fibrils) and lack of cheilocystidia. Description:— Basidiomata small, pleurotoid. Pileus 3–7 mm diam., cupulate then reniform with incurved then lobate margin, non hygrophanous, slightly translucently striate, tomentose to finely squamulose, deep blue to dark blue (20D8, 20E7–8). Lamellae moderately distant intermixed with lamellulae, adnate or slightly emarginate, whitish to bluish near the pileal margin then pinkish with concolorous entire edge. Stipe 3–4 × 0.5–1 mm, reduced, eccentric or lateral, curved, pruinose to tomentose, concolorous with the pileus or slightly paler (20D7), with white arachnoid mycelial strands at the base attached to the substratum. Context thin, bluish, under the surface dark blue. Odor indistinct, taste not reported. Basidiospores (7–)8.3(–9) × (5.5–)5.7(–6) μm, Q = (1.3–)1.45(–1.6), heterodiametrical, with 6–8 angles in sideview. Basidia 23–31 × 9–12 μm, clavate, clampless. Lamellae edge fertile. Cheilocystidia and pleurocystidia absent. Pileipellis a trichoderm of long hairs, composed of chains of cylindrical cells narrower at the apical part (27–62 × 5.5–6.5 μm), broader at the base (27–62 × 5.5–6.5 μm) with dark blue intracellular pigment. Clamp connections, oleiferous hyphae and brilliant granules absent. Notes:— Entoloma cyanomelaenum possesses larger (9–11 × 5.5–6.5 μm) spores and its pileus turns red in KOH (Boedijn 1929; Horak 1980); E. gainsvillae has slightly larger spores (8–10 × 6–7 μm) and a smooth pileus (Murrill 1943; Hesler 1967); E. nubilum differs from E. daphnis by differently-shaped (5–7 angled) spores, a cutis-type pileipellis, and habitat on decaying leaves or on humus (Manimohan et al. 2002); E. icarus possesses larger (10–13 × 7–9 μm) differently-shaped (with 5–7 sharp angles) spores and cheilocystidia.Published as part of Morozova, Olga, Popov, Eugene, Alexandrova, Alina, Pham, Thi Ha Giang & Noordeloos, Machiel Evert, 2022, Four new species of Entoloma (Entolomataceae, Agaricomycetes) subgenera Cyanula and Claudopus from Vietnam and their phylogenetic position, pp. 1-21 in Phytotaxa 549 (1) on pages 15-16, DOI: 10.11646/phytotaxa.549.1.1, http://zenodo.org/record/660526
Entoloma arion O. V. Morozova, E. S. Popov, T. H. G. Pham & Noordeloos 2022, sp. nov.
No full textEntoloma arion O.V. Morozova, E.S. Popov, T.H.G. Pham & Noordeloos, sp. nov. (Figs. 5, 6) Mycobank: MB 843251 Type:— VIETNAM. Gia Lai Province, K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, N 14.487996°, E 108.57101°, 960 m a.s.l., on soil along a track in middle-mountain evergreen mixed forest with a predominance of Podocarpaceae (Dacrydium elatum, Dacrycarpus imbricatus), Magnoliaceae, Burseraceae (Canarium), Myrtaceae (Syzygium), 29 May 2016, O.V. Morozova and E.S. Popov (holotype: LE F-312691 (!), isotype in VRTC (!), ITS sequence GenBank OM987259, LSU sequence GenBank OM996176). Etymology:—Ἀρίων (Greek), Aríon (Lat.) a Greek poet, singer and musician who played the cithara (7–6th centuries BC). According to legend, Arion sailed with rich treasures on a ship to Corinth. The sailors, wanting to take possession of the singer’s wealth, threw him overboard, but Arion was rescued by a dolphin and safely reached Corinth. A butterfly Phengaris arion of the Lycaenidae (Cupidinidae) family with a blue upper and a light under surface of the wings was named after him. Our new species is similar to it in colors. Diagnosis:— Entoloma arion is characterized by the bright blue, radially fibrillose pileus with rather dark blue central spot and scales at first densely covering whole surface, moving apart with pileus expansion, showing a whitish or light blue background, and a white stipe that is minutely innately fibrillose and pruinose at the apex. Microscopically, cylindrical to broadly clavate septate cheilocystidia and caulocystidia in the form of bundles of long hairs are distinctive. Description:— Basidiomata small to medium-sized, collybioid. Pileus 10‒25 mm diam., hemisphaerical, convex, soon expanding to plano-convex with flat to slightly depressed centre, with deflexed then straight margin, non hygrophanous, non translucently striate, radially fibrillose, at first entirely densely covered with dark blue to blackish blue squamules (20 E – F 6–8), moving apart with pileus expansion showing whitish or light blue (20 B – C 4–6) background, with fibrillose, contrasting blackish blue centre. Lamellae moderately distant, broadly adnate, slightly emarginate with a small tooth, segmentiform to arcuate, white, or pale bluish in young basidiomata, becoming pinkish, with irregular concolorous edge. Stipe 30–70 × 1.5–2 mm, cylindrical, minutely innately fibrillose, pruinose in upper part, translucent, white or pale bluish in young basidiomata. Context white. Smell indistinct, taste not reported. Basidiospores (9.5–)10.5–12(–13) × (6.5–)7–7.5(–8.5) μm, Q = (1.3–)1.5(–1.7), heterodiametrical, with 5–6 angles in side-view. Basidia 23–30 × 9–12 μm, 1–2-or 4-spored, narrowly clavate to clavate, clampless. Cheilocystidia 27–78 × 7–18 μm, cylindrical or narrowly to broadly clavate, often septate, not pigmented, forming a sterile lamellar edge or intermixed with basidia. Pileipellis a cutis with transition to a trichoderm, composed of repent cylindrical hyphae 4–8 μm diam with narrowly clavate to fusoid ascending terminal elements 70–210 × 15–25 μm, a trichoderm at center. Caulocystidia in the form of bundles of hairs up to 200 μm long composed of chains of cylindrical cells 23–44 × 5–10 μm. Clamp connections absent. Habitat and distribution:—In small groups in the middle-mountain evergreen mixed forests. Known only from Vietnam. Additional specimens examined:— VIETNAM. Gia Lai Province, K’Bang District, Son Lang Commune, Kon Chu Rang Nature Reserve, N 14.49776°, E 108.556993°, 975 m a.s.l., on soil along a track in middle-mountain evergreen mixed forest with a predominance of Podocarpaceae (Dacrydium elatum, Dacrycarpus imbricatus), Magnoliaceae, Burseraceae (Canarium), Myrtaceae (Syzygium), 28 May 2016, O.V. Morozova and E.S. Popov (LE F-312692 (!), ITS sequence GenBank OM987260; LE F-315917 (!), ITS sequence GenBank OM987261). Notes:— Entoloma arion can be easily recognized by the bright blue pileus and contrasting white stipe, a very rare combination in subgenus Cyanula. Entoloma floccosodentatum Corner & E. Horak, in Horak (1980: 288) from New Caledonia is superficially similar in colors, spore size and cystidia form, but its pileus is pale blue and smooth, or only innately fibrillose, or tomentose. The presence of clamps on the hyphae indicates that Entoloma floccosodentatum does not belong to the subgenus Cyanula. Geographically it is also very distant and isolated.Published as part of Morozova, Olga, Popov, Eugene, Alexandrova, Alina, Pham, Thi Ha Giang & Noordeloos, Machiel Evert, 2022, Four new species of Entoloma (Entolomataceae, Agaricomycetes) subgenera Cyanula and Claudopus from Vietnam and their phylogenetic position, pp. 1-21 in Phytotaxa 549 (1) on pages 10-13, DOI: 10.11646/phytotaxa.549.1.1, http://zenodo.org/record/660526
Exploring methionine Gamma-lyase structure-function relationship via microspectrophotometry and X-ray crystallography.
No full textPyridoxal 5'-phosphate (PLP) dependent methionine γ-lyase catalyzes the breakdown of L-methionine to α-ketobutyric acid, methanethiol and ammonia. This enzyme, present in anaerobic microorganisms, has biomedical interest both for its activity as antitumor agent, depleting methionine supply in methionine-dependent cancers, and as target in the treatment of human pathogen infections, activating the pro-drug trifluoromethionine. To validate the structure of the enzyme from Citrobacter freundii, crystallized from monomethyl ether polyethylene glycol 2000, for the development of lead compounds, the reactivity of the crystalline enzyme towards L-methionine, substrate analogs and inhibitors was determined by polarized absorption microspectrophotometry. Spectral data were also collected for enzyme crystals, grown in monomethyl ether polyethylene glycol 2000 in the presence of ammonium sulfate. The three-dimensional structure of these enzyme crystals, solved at 1.65Å resolution with R(free) 23.2%, revealed the surprising absence of the aldimine bond between the active site Lys210 and PLP. Different hypothesis are proposed and discussed in the light of spectral and structural data, pointing out to the relevance of the complementarity between X-ray crystallography and single crystal spectroscopy for the understanding of biological mechanisms at molecular level. This article is part of a Special Issue entitled: Protein Structure and Function in the Crystalline State
Soluble and nanoporous silica gel-entrapped C. freundii methionine γ-lyase
No full textMethionine γ-lyase is a pyridoxal 5’-phosphate dependent tetramer that catalyzes the ,γ-elimination of methionine in ammonia, methanethiol and -ketobutyrate. MGL catalytic power has been exploited as a therapeutic strategy to reduce the viability of cancer cells or bacteria. In order to obtain a stable enzyme to be delivered at the site of action, MGL can be encapsulated in a variety of matrices. As a reference encapsulation strategy we have prepared MGL nanoporous wet silica gels. Immobilized MGL gels were characterized with regards to activity, stability, absorption, circular dichroism and fluorescence properties and compared with soluble MGL. We found that MGL gels exhibit i) spectroscopic properties very similar to MGL in solution, ii) a higher stability with respect to the soluble enzyme and iii) catalytic activity six-fold lower than in solution. These findings prove that MGL encapsulation is a suitable strategy for therapeutic applications
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