158 research outputs found
Glaciambulata Galea, gen. nov.
No full textGenus Glaciambulata Galea, gen. nov. urn:lsid:zoobank.org:act:B2696364-D58F-4BB9-B326-DE244E1FA51A Type species Glaciambulata neumayeri gen. et sp. nov. Diagnosis Crawling medusae, unable to swim, possibly due to the absence of a velum. Umbrella watch glassshaped, margin entire, not lobed; exumbrella smooth; eight radial canals joining a circular canal; centripetal canals absent; manubrium eight-lobed, giving rise to eight perradial mesenteries; eight pairs of gonads, each of which is conFned to either side of a manubrial lobe; tentacles of two types, Fliform and adhesive, arranged in contiguous groups composed of several superimposed rows; 16 free, ectoendodermal statocysts (2 per octant). Etymology From the Latin words glăciēs, meaning ice, and ambŭlo, -āvī, -ātum, -āre, meaning to walk, making reference to the peculiar habit of this medusa. Remarks The Fat, smooth umbrella, and the absence of a velum immediately distinguish the new genus from Ptychogastria Allman, 1878 and Tesserogastria Beyer, 1959. The manubrial shape, the composition and arrangement of tentacles, the presence of mesenteries, and the shape and position of the gonads, are reminiscent of Ptychogastria. The presence of adhesive tentacles, and of 16 statocysts, instead of only 8, further distinguish it from Tesserogastria.Published as part of Horia R. Galea, Cornelia Roder, Christoph Walcher, Marco Warmuth, Eberhard Kohlberg & Philipp F. Fischer, 2016, Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae, pp. 1-30 in European Journal of Taxonomy 252 on page 5, DOI: 10.5852/ejt.2016.252, http://zenodo.org/record/22125
Trachymedusae Haeckel 1866
No full textOrder Trachymedusae Haeckel, 1866 Diagnosis Hydromedusae with umbrella margin entire, not deeply-lobed; with conspicuous marginal nematocyst ring; manubrium with or without gastric peduncle; with circular and radial canals, and gonads usually conFned to the latter; centripetal canals either present or absent; tentacles marginal, either solid, or solid and hollow occurring simultaneously; statocysts of ecto-endodermal origin, either free or enclosed; velum generally well-developed, exceptionally absent. Remarks The diagnosis given above combines those provided by Kramp (1968) and Bouillon et al. (2006), and adds the case when the velum is absent, as it will be shown below for the genus Glaciambulata gen. nov. The taxonomic status of some of the families included in Trachymedusae is unsettled yet. For example, Collins et al. (2008) have shown that the family Geryoniidae Eschscholtz, 1829 is derived from within another order, Limnomedusae Kramp, 1938, and the family Halicreatidae Fewkes, 1886 belongs to a sister group of a clade containing the orders Narcomedusae Haeckel, 1879 and Actinulida Swedmark & Teissier, 1959, as well as the trachymedusan family Rhopalonematidae Russell, 1953. In addition, according to the same source, some characters of the family Petasidae Haeckel, 1879, especially the presence of 4 radial canals instead of generally 8, common to Rhopalonematidae, suggest that it may belong elsewhere.Published as part of Horia R. Galea, Cornelia Roder, Christoph Walcher, Marco Warmuth, Eberhard Kohlberg & Philipp F. Fischer, 2016, Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae, pp. 1-30 in European Journal of Taxonomy 252 on page 3, DOI: 10.5852/ejt.2016.252, http://zenodo.org/record/22125
Ptychogastriidae Mayer 1910
No full textFamily Ptychogastriidae Mayer, 1910 Diagnosis Trachymedusae with either Fat or dome-shaped umbrella; with four-lobed manubrium, not giving rise to mesenteries, or with eight-lobed manubrium, giving rise to eight mesenterial partitions of the subumbrella; without gastric peduncle; mouth with four simple lips; tentacles marginal, either Fliform, not arranged in groups and inserted at varied levels on the umbrellar margin, or Fliform and adhesive occurring simultaneously, and grouped into more or less well-deFned clusters composed of several superimposed rows; eight radial canals joining the circular canal; centripetal canals either absent or present; gonads either simple, elongated and attached to the body of manubrium, or in pairs resulting from the mesenterial partitions and developing on either side of the manubrial lobes; with or without a velum; with either 8 or 16 free, ecto-endodermal statocysts. Remarks Earlier diagnoses (Mayer 1910; Kramp 1959, 1961, 1968; Bouillon & Boero 2000; Bouillon et al. 2006) are broadened by taking into consideration the shape of the umbrella, the presence/absence of a velum, and of centripetal canals. Indeed, unlike both Ptychogastria Allman, 1878 and Tesserogastria Beyer, 1959, the medusae belonging to the so far monotypic genus Glaciambulata gen. nov. (see below) have Fattened rather than dome-shaped umbrellas, and they also lack a velum. The presence of centripetal canals was curiously excluded from earlier diagnoses of the family, though they are present in P. polaris Allman, 1878. The occurrence of the gonads is henceforth restricted to the manubrium only, because Pectis antarctica Haeckel, 1879, formerly assigned to the genus Ptychogastria by a number of authors, has the gonads on the radial canals and, for this reason, combined with additional characters, does not belong to Ptychogastriidae (see below). The main distinguishing characters of ptychogastriid genera are listed in Table 1. Key to the genera 1. Tentacles exclusively Fliform ………………………………………… Tesserogastria Beyer, 1959 – Tentacles of two types: Fliform and adhesive ………………………………………………………2 2. Umbrella dome-shaped, velum present ……………………………… Ptychogastria Allman, 1878 – Umbrella Fat, velum absent ……………………………………………… Glaciambulata gen. nov.Published as part of Horia R. Galea, Cornelia Roder, Christoph Walcher, Marco Warmuth, Eberhard Kohlberg & Philipp F. Fischer, 2016, Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae, pp. 1-30 in European Journal of Taxonomy 252 on pages 3-4, DOI: 10.5852/ejt.2016.252, http://zenodo.org/record/22125
Ptychogastria Allman 1878
No full textGenus Ptychogastria Allman, 1878 Pectyllis Haeckel, 1879: 265. Pectanthis Haeckel, 1879: 267. Pectyllis – Haeckel 1881a: 9; 1881b: 10. Pectanthis – Haeckel 1881a: 17; 1881b: 19. Diagnosis Crawling ptychogastriid medusae with swimming capabilities; with dome-shaped, marginally-“lobed” umbrella, and eight-lobed manubrium, giving rise to as many mesenterial partitions of the subumbrellar cavity; mouth quadrangular, with simple lips; eight radial canals; centripetal canals either present or absent; eight pairs of gonads conFned to the sides of the manubrial lobes; tentacles Fliform and adhesive, occurring simultaneously and arranged in clusters around the bell margin; velum broad; 16 free, ectoendodermal statocysts (2 per octant). Remarks The diagnoses given by Bouillon & Boero (2000) and Bouillon et al. (2006) are broadened again, so as to include the shape of the umbrella, the presence/absence of centripetal canals, and the presence of a velum, as Allman (1878) and/or Mayer (1910) did earlier. As underlined by Mayer, the «differences between the genera “ Pectyllis,” “ Pectis,” and “ Pectanthis,” as deFned by Haeckel, are so slight as to appear of speciFc rather than of generic value». Indeed, Haeckel (1879) distinguished Pectis (type species Pectis antarctica) from both Pectanthis (type species Pectanthis asteroides) and Pectyllis (type species Pectyllis arctica) through the presence of centripetal canals. In contrast, the tentacles were described as arranged in distinct groups in Pectanthis, and forming comparatively more contiguous groups in both Pectis and Pectyllis. Similarly, Browne (1903) acknowledged earlier that “When Pectis antarctica and Pectanthis asteroides have been again examined it may be found that one genus with three species will be quite sufFcient”. However, it will be shown at the end of this paper that the former species does not belong to Ptychogastriidae, but to a different family of Trachymedusae, viz. Rhopalonematidae Russell, 1953. Key to species: 1. Centripetal canals absent …………………………………………… P. asteroides (Haeckel, 1879) – Centripetal canals present ……………………………………………………… P. polaris Allman, 1878Published as part of Horia R. Galea, Cornelia Roder, Christoph Walcher, Marco Warmuth, Eberhard Kohlberg & Philipp F. Fischer, 2016, Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae, pp. 1-30 in European Journal of Taxonomy 252 on page 11, DOI: 10.5852/ejt.2016.252, http://zenodo.org/record/22125
Die Anpassungsfähigkeit von Korallen an Störung
No full textOffshore reefs (Similan Islands, Thailand) and near-shore reefs (Cahuita, Costa Rica and Hainan, China) under disturbance are investigated. Coral reefs along the west sides of the Similan Islands are naturally affected by Large Amplitude Internal Waves (LAIW), while reefs on the east sides are only impacted to a lower extend. LAIW frequently introduce cold, oxygen depleted, CO2- and nutrient-rich deep water into the reefs which strongly impacts the metabolism of corals. On the other hand, the near-shore reefs under investigation are exposed to anthropogenic impacts. A decrease in live coral cover and biodiversity in the reefs of Costa Rica, and an initiating phase shift from a coral to an algae dominated reefs in Hainan indicate the serious disturbance to these ecosystems. Increasing anthropogenic pressure will inevitably lead to their collapse. In contrast to the pulsed disturbances by LAIW, the chronic land based disturbances are permanently increasing and therefore an acute risk
Coral acclimatization to disturbance
No full textOffshore reefs (Similan Islands, Thailand) and near-shore reefs (Cahuita, Costa Rica and Hainan, China) under disturbance are investigated. Coral reefs along the west sides of the Similan Islands are naturally affected by Large Amplitude Internal Waves (LAIW), while reefs on the east sides are only impacted to a lower extend. LAIW frequently introduce cold, oxygen depleted, CO2- and nutrient-rich deep water into the reefs which strongly impacts the metabolism of corals. On the other hand, the near-shore reefs under investigation are exposed to anthropogenic impacts. A decrease in live coral cover and biodiversity in the reefs of Costa Rica, and an initiating phase shift from a coral to an algae dominated reefs in Hainan indicate the serious disturbance to these ecosystems. Increasing anthropogenic pressure will inevitably lead to their collapse. In contrast to the pulsed disturbances by LAIW, the chronic land based disturbances are permanently increasing and therefore an acute risk
Uns brins de mossarabisme valencià
No full textThe author studies etymologically two Arabisms: roder, which he cosiders to be derived from rotair, not from rodar, and its synonym cullerat, often found in medieval Valencian texts
Uns brins de mossarabisme valencià
No full textAbstract: The author studies etymologically two Arabisms: roder, which he cosiders to be derived from rotair, not from rodar, and its synonym cullerat, often found in medieval Valencian texts
Dynamics and folding of single two-stranded coiled-coil peptides studied by fluorescent energy transfer confocal microscopy
No full textWe report single-molecule measurements on the folding and unfolding conformational equilibrium distributions and dynamics of a disulfide crosslinked version of the two-stranded coiled coil from GCN4. The peptide has a fluorescent donor and acceptor at the N termini of its two chains and a Cys disulfide near its C terminus. Thus, folding brings the two N termini of the two chains close together, resulting in an enhancement of fluorescent resonant energy transfer. End-to-end distance distributions have thus been characterized under conditions where the peptide is nearly fully folded (0 M urea), unfolded (7.4 M urea), and in dynamic exchange between folded and unfolded states (3.0 M urea). The distributions have been compared for the peptide freely diffusing in solution and deposited onto aminopropyl silanized glass. As the urea concentration is increased, the mean end-to-end distance shifts to longer distances both in free solution and on the modified surface. The widths of these distributions indicate that the molecules are undergoing millisecond conformational fluctuations. Under all three conditions, these fluctuations gave nonexponential correlations on 1- to 100-ms time scale. A component of the correlation decay that was sensitive to the concentration of urea corresponded to that measured by bulk relaxation kinetics. Thetrajectories provided effective intramolecular diffusion coefficients as a function of the end-to-end distances for the folded and unfolded states. Single-molecule folding studies provide information concerning the distributions of conformational states in the folded, unfolded, and dynamically interconverting states.Author manuscript. Published in final edited form as: Proc Natl Acad Sci U S A. 2000 November 21; 97(24): 13021-13026.The final published version of this article is located at: http://www.pnas.org/cgi/reprint/97/24/13021NIH GM54616; to William F. DeGradoNIH GM12592; to Robin M. HochstrasserNIH GM48130; to William F. Degrado and Robin M. HochstrasserThis work was supported by GM54616 (to W.F.D.), GM12592 (to R.M.H.) and GM48130 (to W.F.D. and R.M.H.) with instrumentation developed under RR01348. D.S.T. was supported by National Institutes of Health Grant NRSA F32-GM18589.Also available in PubMed Central. PMCID:PMC2717
Tesserogastria musculosa Beyer 1959
No full textTesserogastria musculosa Beyer, 1959 Fig. 4 F–G Tesserogastria musculosa Beyer, 1959: 122, pls 1– 2. Tesserogastria musculosa – Hesthagen 1971: 3, Fgs 2–10. — Bouillon 1985: 202. — Larson et al. 1992: 284. — Bouillon et al. 2006: 112. Description Umbrella bell-shaped, about as high as broad (up to 2.5 mm), with a small, blunt, apical projection surrounded by a circular depression. Exumbrella devoid of radial ridges. Mesoglea rather thin, comparatively thickened at margin, accommodating a belt of chordal cells on which the tentacles insert. Over 300 tentacles, inserted at 3–5 superimposed levels, apparently not forming distinct rows or clusters; solid, core composed of a single row of chordal cells; proximally constricted, leaving tear drop-shaped scars when shed; blunt-ended to pointed distally, and there devoid of adhesive pads; nematocysts evenly dispersed in epidermis, except for the distal tip, where they are comparatively crowded. Manubrium cross-shaped (four perradial lobes are distinguishable), except proximally where it assumes an octagonal shape at the origin of the radial canals; relatively long, though devoid of a peduncle, and extending somewhat beyond the bell margin; mesenteries absent; mouth square, with four simple lips provided with ciliated cells in the epidermis. Eight radial canals with rounded cross sections connect to the broad ring canal, elliptical in cross section, longer axis oral-aboral; centripetal canals absent. A conspicuous nematocyst ring on lower side of umbrella margin. Velum extremely broad and strong. Eight slender, elongated gonads, in four perradial pairs; one pair conFned to each manubrial lobe. Eight small, shortstalked, interradial statocysts with single, spherical statoliths; one statocyst in each octant. Cnidome: almost spherical stenoteles [(7–8) × (6–7) µm], tear drop-shaped microbasic euryteles [(4–7) × (3– 5) µm], and atrichous isorhizas (ca 2 µm); the capsules occur in both tentacles and the marginal ring. Color: umbrella translucent, with white to yellow epidermal spots at junction of radial canals with the ring canal. Remarks Although the tentacles were described as “not arranged in distinct rows, nor in clusters” around the bell margin, Beyer (1959) acknowledged that “It is possible, however, to trace some repetition in the arrangement, and this makes 48 groups […]. The pattern is thus not quite unlike that of Ptychogastria polaris Allman […]”. However, no further details were given relative to the position of these groups with respect to the radial canals. Their presence, if conFrmed again, would not be surprising, given that more or less distinct groups of tentacles can be found in both Ptychogastria and Glaciambulata, the sole marked difference in this respect being the total absence of tentacles with adhesive pads in Tesserogastria. Though no such structures have been observed, “The amount of debris so frequently found to be sticking to the tentacle ends indicate that they are adhesive” (Beyer 1959). The so called adhesion is, most probably, due to the crowded condition of the nematocysts in the tentacle tips (Beyer 1959), and the possible glutinant nature of some of them (Hesthagen 1971). The development from the egg, and the behavior of the medusa were thoroughly documented by Hesthagen (1971). Ecology A soft bottom species, never captured in plankton nets or vertical hauls (Beyer 1959). The medusae move extremely slowly, and have never been observed to swim in captivity, unless they were forced to do so and, in this case, their swimming was jerky. Specimens of this species have been collected between 60–350 m (Hesthagen 1971). Distribution Only known from the Norwegian coast of the North Sea, between Bergen and Oslo (Hesthagen 1971).Published as part of Horia R. Galea, Cornelia Roder, Christoph Walcher, Marco Warmuth, Eberhard Kohlberg & Philipp F. Fischer, 2016, Glaciambulata neumayeri gen. et sp. nov., a new Antarctic trachymedusa (Cnidaria: Hydrozoa), with a revision of the family Ptychogastriidae, pp. 1-30 in European Journal of Taxonomy 252 on pages 16-17, DOI: 10.5852/ejt.2016.252, http://zenodo.org/record/22125
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