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Surface zooplankton and seabird densities and community composition in the Atlantic (between Cape Town and Sanae) and Pacific (between New Zealand and the Ross Sea) sectors of the Southern Ocean are described and related to oceanographic features. Samples were collected during two return voyages aboard the MV Benjamin Bowring as part of the Transglobe Expedition (1979–1981). High abundances of surface zooplankton and seabirds were consistently observed within the main frontal systems of the Southern Ocean. Generally, on a mesoscale significant correlations between surface temperature and the distribution of zooplankton or seabirds were observed. On a macroscale, the geographical positions of the zooplankton and seabird communities coincided with specific water masses. The results of this study suggest that appropriate food availability rather than water temperature is important for the determination of seabird distribution. The ecological importance of the recently described frontal zone associated with the northern boundary of the maximum winter expansion of sea ice is confirmed by biological data obtained in this study. 相似文献
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Evelina L Zdorovenko Evgeny Vinogradov Galina M Zdorovenko Buko Lindner Olga V Bystrova Alexander S Shashkov Klaus Rudolph Ulrich Z?hringer Yuriy A Knirel 《European journal of biochemistry》2004,271(23-24):4968-4977
The core structure of the lipopolysaccharide (LPS) isolated from a rough strain of the phytopathogenic bacterium Pseudomonas syringae pv. phaseolicola, GSPB 711, was investigated by sugar and methylation analyses, Fourier transform ion-cyclotron resonance ESI MS, and one- and two-dimensional 1H-, 13C- and 31P-NMR spectroscopy. Strong alkaline deacylation of the LPS resulted in two core-lipid A backbone undecasaccharide pentakisphosphates in the ratio approximately 2.5 : 1, which corresponded to outer core glycoforms 1 and 2 terminated with either L-rhamnose or 3-deoxy-D-manno-oct-2-ulosonic acid (Kdo), respectively. Mild acid degradation of the LPS gave the major glycoform 1 core octasaccharide and a minor truncated glycoform 2 core heptasaccharide, which resulted from the cleavage of the terminal Kdo residues. The inner core of P. syringae is distinguished by a high degree of phosphorylation of L-glycero-D-manno-heptose residues with phosphate, diphosphate and ethanolamine diphosphate groups. The glycoform 1 core is structurally similar but not identical to one of the core glycoforms of the human pathogenic bacterium Pseudomonas aeruginosa. The outer core composition and structure may be useful as a chemotaxonomic marker for the P. syringae group of bacteria, whereas a more conserved inner core structure appears to be representative for the whole genus Pseudomonas. 相似文献
4.
Zhan Wang Suzon Larocque Evgeny Vinogradov Jean-Robert Brisson Andrew Dacanay Marshall Greenwell Laura L Brown Jianjun Li Eleonora Altman 《European journal of biochemistry》2004,271(22):4507-4516
Aeromonas salmonicida is a pathogenic aquatic bacterium and the causal agent of furunculosis in salmon. In the course of this study, it was found that when grown in vitro on tryptic soy agar, A. salmonicida strain 80204-1 produced a capsular polysaccharide with the identical structure to that of the lipopolysaccharide O-chain polysaccharide. A combination of 1D and 2D NMR methods, including a series of 1D analogues of 3D experiments, together with capillary electrophoresis-electrospray MS (CE-ES-MS), compositional and methylation analyses and specific modifications was used to determine the structure of these polysaccharides. Both polymers were shown to be composed of linear trisaccharide repeating units consisting of 2-acetamido-2-deoxy-D-galacturonic acid (GalNAcA), 3-[(N-acetyl-L-alanyl)amido]-3,6-dideoxy-D-glucose[3-[(N-acetyl-L-alanyl)amido]-3-deoxy-D-quinovose, Qui3NAlaNAc] and 2-acetamido-2,6-dideoxy-D-glucose (2-acetamido-2-deoxy-D-quinovose, QuiNAc) and having the following structure: [-->3)-alpha-D-GalpNAcA-(1-->3)-beta-D-QuipNAc-(1-->4)-beta-D-Quip3NAlaNAc-(1-]n, where GalNAcA is partly presented as an amide and AlaNAc represents N-acetyl-L-alanyl group. CE-ES-MS analysis of CPS and O-chain polysaccharide confirmed that 40% of GalNAcA was present in the amide form. Direct CE-ES-MS/MS analysis of in vivo cultured cells confirmed the formation of a novel polysaccharide, a structure also formed in vitro, which was previously undetectable in bacterial cells grown within implants in fish, and in which GalNAcA was fully amidated. 相似文献
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Mesozooplankton surveys were conducted in April/May for fourconsecutive years (19961999) in the vicinity of the PrinceEdward Islands (PEIs), Southern Ocean. The PEIs are locatedin the Polar Frontal Zone, directly in the path of the east-flowingAntarctic Circumpolar Current. Zooplankton were collected byoblique tows using a Bongo net fitted with 300 µm mesh.The abundance, biomass and average size of the mesozooplanktonin the upstream (USR), inter-island (IIR) and downstream (DSR)regions indicated that some groups and species were significantlyaffected by their interaction with the shallow shelf watersof the PEIs. Total mesozooplankton abundance and biomass weretypically highest in the DSR, but no consistent pattern wasevident in the USR and IIR. Copepods, euphausiids and fish weregenerally of a low average size in the IIR. This small sizewas largely attributed to the reduced abundance, or completeabsence, of mesopelagic species from the shelf region. Of totalbiomass, the mesopelagic species Euphausia longirostris, Euphausiasimilis, Pleuromamma abdominalis, Paraeuchaeta biloba and Oncaeaantarctica together contributed an average of 16% to the USR,2% to the IIR and 15% to the DSR. Conversely, epipelagic speciesshowed no consistent pattern of abundance and biomass distributionbetween regions. The low incidence of mesopelagic species overthe island shelf was attributed mainly to reduced advectionof deep water into the shelf region (average depth = 200 m),rather than predation, particularly during the through-flowmode between the islands. This resulted in substantial regionaldifferences in euphausiid community structure. The epipelagicspecies Euphausia vallentini and Thysanoessa vicina completelydominated the IIR, comprising on average 89% of total euphausiidbiomass in this region. However, predation may be importantduring the water-trapping mode between the islands. Advectionof zooplankton into the IIR appeared to be affected by the proximityof the Subantarctic Front (SAF). In 1996, when the SAF was farnorth of the PEIs, reduced current velocities resulted in somedegree of water retention over the shelf and an increased predationimpact. Conversely, when the SAF was close to the PEIs in 1999,more large plankton were transported over the island shelf.High current velocities and productivity associated with theSAF appear to increase the biomass and size of allochthonouszooplankton/nekton advected into the IIR, and consequently mayhave increased the availability of prey to land-based predators.The long-term southward movement of the SAF recently observedin the vicinity of the PEIs may therefore have important implicationsfor the ecosystem of these islands. 相似文献
6.
Marina S. Trofimova Inna M. Zhestkova Valentina P. Kholodova Igor M. Andreev Evgeny M. Sorokin Anna G. Kruglova Vladimir V. Kuznetsov 《Physiologia plantarum》2003,118(2):232-239
The osmotic water permeability ( P os ) of cell membranes isolated from leaves of 40-, 50- and 60-day-old Mesembryanthemum crystallinum plants was estimated by measuring light-scattering kinetics using stopped-flow spectrophotometry. The measurements were performed on the plasma membrane (PM), purified tonoplast (TP), and TP-enriched vesicles. The PM and TP-enriched vesicles were obtained by partitioning the microsomal fraction in an aqueous polymer two-phase system, whereas the purified TP vesicles were prepared by microsomal vesicle flotation on a sucrose cushion. The P os of isolated membranes declined with plant age. The kinetic experiments showed that there was no difference between the P os of the PM and TP isolated from plants of all ages. A 24-h exposure of plants to 400 m M NaCl caused a decline in the P os as well. These findings suggest that, during M. crystallinum transition to CAM, which was induced by plant ageing or salinity, plant osmoregulatory responses included changes in the P os of the leaf-cell membranes. These variations in the P os are discussed in the context of adaptive mechanisms responsible for the maintenance of the water balance in the common ice plant. 相似文献
7.
Andrei G. Pakhomov Boris V. Dubovick Igor G. Degtyariov Anatoly N. Pronkevich 《Bioelectromagnetics》1995,16(4):250-254
The combined effects of microwave radiation and some drugs were studied in an isolated frog auricle preparation. The experiments established that exposure to pulse-modulated 915 MHz microwaves for up to 40 min had no effect on either the rate or the amplitude of spontaneous auricle twitches, unless the average absorbed power was high enough to produce preparation heating. Treatment of the preparation with saline containing (0.6–3.0) 10?5 M of propranolol or (0.5–1.5) 10?7 M of atropine altered neither its pacemaker nor its contractile functions; these drugs also had no effect when they were combined with nonthermal microwave irradiation. Caffeine (1 mM) strongly increased the average heart power, which was calculated as the product of twitch rate and amplitude. The caffeine effect appeared to be significantly augmented (by about 15%, P<0.02) under exposure to burst-type pulsed microwaves (pulse width, 1.5 msec; pause, 2.5 msec; 8 pulses/burst, 16 bursts/s; average SAR, 8–10 W/kg). By itself, this modulation was not effective; the heating of the preparation and saline during exposure was approximately 0.1°C, which could not account for the detected changes. The experimental results demonstrate that caffeine treatment increases the microwave sensitivity of the frog auricle preparation and reveals primarily subthreshold, nonthermal microwave effect. © 1995 Wiley-Liss, Inc. 相似文献
8.
Nikolay K. Kochetkov Nelly N. Malysheva Vladimir I. Torgov Evgeny M. Klimov 《Carbohydrate research》1977,54(2):269-274
The oligosaccharide β-d-Man-(1 → 4)-α-l-Rha (1 → 3)-d-Gal-(6 ← 1)-α-d-Glc, which is the repeating unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella senftenberg, was obtained by glycosylation of benzyl 2,4-di-O-benzyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside or benzyl 2-O-acetyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside with 3-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-β-l-rhamnopyranose 1,2-(methyl orthoacetate) followed by removal of protecting groups. 相似文献
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