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61.
The suitability of the reductive-cleavage method for analysis of the linkage positions in d-fructofuranosyl residues of d-fructans was examined by using sucrose, chicory-root inulin, and Aerobacter levanicum levan as models. Permethylation, and reductive cleavage with triethylsilane in the presence of either boron trifluoride etherate or trimethylsilyl trifluoromethanesulfonate, gave the expected methylated derivatives of 2,5-anhydro-d-mannitol and 2,5-anhydro-d-glucitol. With either catalyst, nonreducing (terminal) d-fructofuranosyl groups and d-fructofuranosyl residues linked at O-1 gave derivatives having the manno configuration as the major product, whereas d-fructofuranosyl residues linked at O-6, and at both O-1 and O-6, gave derivatives having the gluco configuration as the major product. The independent synthesis, and n.m.r.- and mass-spectral characterization, of the methylated 2,5-anhydro-d-mannitol and 2,5-anhydro-d-glucitol derivatives formed from these residues by reductive cleavage are reported. 相似文献
62.
The cell-surface expression patterns of major histocompatibility complex (MHC) class I, class II and heat-shock protein 72
(HSP72) molecules were measured on human lung (LX-1) and mammary (MX-1) carcinoma cells. No major differences were found in
the MHC cell-surface expression pattern of both cell lines. However, they differ significantly in their capacity to express
HSP72 on their cell surface. Under physiological conditions LX-1 cells express HSP72 molecules on more than 90% of the cells,
whereas MX-1 cells exhibit no significant HSP72 cell-surface expression (less than 5%). These expression patterns remained
stable in all further cell passages tested. The sensitivity to lysis mediated by an interleukin-2 (IL-2)-stimulated, adherent
natural killer (NK) cell population could be correlated with the amount of cell-surface-expressed HSP72 molecules. By antibody-blocking
studies, using HSP72-specific monoclonal antibody (mAb), a strong inhibition of lysis was only found with LX-1 cells but not
with MX-1 cells. In contrast to the cell-surface expression, the cytoplasmic amount of HSP72 in MX-1 cells was twice as high
compared to LX-1 cells under physiological conditions. After nonlethal heat-shock the rate of induction and the total cytoplasmic
amounts of HSP72 were comparable in both cell lines. The clonogenic cell viability of LX-1 cells after incubation at temperatures
ranging from 41°C to 44°C was significantly elevated compared to that of MX-1 cells. In conclusion we state the following:
(i) HSP72 cell-surface expression on human carcinoma cells is independent of the cytoplasmic amount of HSP72; (ii) the cell-surface
expression of HSP72 is associated with an increased sensitivity of tumour cells to lysis mediated by an IL-2-stimulated, adherent
NK cell population; (iii) thermoresistance is not related to the cytoplasmic HSP72 level but might be related to the amount
of HSP72 expressed on the cell surface.
Received: 20 June 1996 / Accepted: 25 September 1996 相似文献
63.
Rolf Erhard und Michael Wink 《Journal of Ornithology》1987,128(4):477-484
Zusammenfassung Die Brutverbreitung der Vögel im Großraum Bonn wurde 1975 und 1985 in jeweils 221 Minutengitterfeldern von je 2,2 km2 Größe kartiert. Statistisch signifikante Zunahmen besetzter Gitterfelder wurden für 9 Arten, Abnahmen für 22 Arten registriert, die z. T. auch andernorts festgestellt wurden. Unter Verwendung von Kartierungsdaten 1974–1978 konnte bei 14 Arten eine signifikante Änderung (Zunahmen: Sperber, Habicht, Singdrossel; Abnahmen: Steinschmätzer, Rebhuhn, Schafstelze, Grauammer, Mehlschwalbe, Feldsperling, Fasan, Dorngrasmücke, Hänfling, Feldlerche und Zaunkönig) nachgewiesen werden. Die Untersuchung zeigt, daß die Rasterkartierung gut geeignet ist, Aussagen über großflächige und langfristige Populationsveränderungen zu machen.
Fluctuation of breeding populations in the area of Bonn: Analysis of grid mapping in 1975 and 1985
Summary The distribution of breeding birds in the area of Bonn was mapped in 1975 and 1985 in 221 grids of 2.2 km2 size each. These data were analyzed to see whether fluctuations in the breeding populations occurred during the 11 years. It was based on the assumption that strong population changes should be reflected in the number of grids occupied by a species. Statistically significant increases were recorded for 9 species, decreases for 22 species. Taking other grid-map data from 1974 til 1978 (Wink 1980) into account, a continuous and significant trend could be established for 14 species (increase:Accipiter nisus, A. gentilis, Turdus philomelos; decrease:Oenanthe oenanthe, Perdix perdix, Motacilla flava, Emberiza calandra, Delichon urbica, Passer montanus, Phasianus colchicus, Sylvia communis, Acanthis cannabina, Alauda arvensis, Troglodytes troglodytes). This study shows that grid-mapping may provide valuable data on population trends of breeding birds.相似文献
64.
The first detailed morphological study of larvae, pupae and adults of a species of the hooded beetles (Coleoptera: Corylophidae) – Sericoderus lateralis – is presented. Histological sectioning, scanning and transmission electron microscopy, laser confocal microscopy and 3D-computer reconstruction were used. For the first time we report that according to the morphometric data of S. lateralis, at least some corylophid beetles have three larval stages. A phylogenetic position of Corylophidae within a cucujoid-cleroid clade is confirmed, and also the placement of Sericoderini within a corlyophid subgroup, which does not include Periptycinae and Foadiini. The larvae of Sericoderus are mainly characterized by plesiomorphic features compared to those of other corylophid tribes, notably Peltinodini and Rypobiini. Morphological and developmental consequences of miniaturization are discussed. Corylophid beetles display much less specific and far-reaching morphological consequences of miniaturization compared to Ptiliidae. We report the presence of unique modifications in the neural system not shared with any other insects, such as a distinctly asymmetric supraoesophageal ganglion in first instar larva, and a total displacement of the brain to the thorax in the adult stage. A highly unusual feature of the digestive tract is the sclerotised, V-shaped ventral wall of the pharynx. Developmental and size dependent changes in the relative volume of different organs are addressed. All organ systems change allometrically in the development of S. lateralis. Allometric trends in the volume of organs confirm that the factors limiting miniaturization are the size of the neural system, associated with the number and size of neurons (most critical for first instar larva), the mass of the skeleton, the egg size, and consequently the volume of the reproductive system (for free-living insects). 相似文献
65.
66.
Dung Quang Nguyen Dominik Schneider Nicole Brinkmann Bin Song Dennis Janz Ingo Schöning Rolf Daniel Rodica Pena Andrea Polle 《Environmental microbiology》2020,22(8):3081-3095
Root-associated fungi (RAF) link nutrient fluxes between soil and roots and thus play important roles in ecosystem functioning. To enhance our understanding of the factors that control RAF, we fitted statistical models to explain variation in RAF community structure using data from 150 temperate forest sites covering a broad range of environmental conditions and chemical root traits. We found that variation in RAF communities was related to both root traits (e.g., cations, carbohydrates, NO3−) and soil properties (pH, cations, moisture, C/N). The identified drivers were the combined result of distinct response patterns of fungal taxa (determined at the rank of orders) to biotic and abiotic factors. Our results support that RAF community variation is related to evolutionary adaptedness of fungal lineages and consequently, drivers of RAF communities are context-dependent. 相似文献
67.
Amy E. Zanne Kessy Abarenkov Michelle E. Afkhami Carlos A. Aguilar‐Trigueros Scott Bates Jennifer M. Bhatnagar Posy E. Busby Natalie Christian William K. Cornwell Thomas W. Crowther Habacuc Flores‐Moreno Dimitrios Floudas Romina Gazis David Hibbett Peter Kennedy Daniel L. Lindner Daniel S. Maynard Amy M. Milo Rolf Henrik Nilsson Jeff Powell Mark Schildhauer Jonathan Schilling Kathleen K. Treseder 《Biological reviews of the Cambridge Philosophical Society》2020,95(2):409-433
Fungi play many essential roles in ecosystems. They facilitate plant access to nutrients and water, serve as decay agents that cycle carbon and nutrients through the soil, water and atmosphere, and are major regulators of macro‐organismal populations. Although technological advances are improving the detection and identification of fungi, there still exist key gaps in our ecological knowledge of this kingdom, especially related to function . Trait‐based approaches have been instrumental in strengthening our understanding of plant functional ecology and, as such, provide excellent models for deepening our understanding of fungal functional ecology in ways that complement insights gained from traditional and ‐omics‐based techniques. In this review, we synthesize current knowledge of fungal functional ecology, taxonomy and systematics and introduce a novel database of fungal functional traits (FunFun). FunFun is built to interface with other databases to explore and predict how fungal functional diversity varies by taxonomy, guild, and other evolutionary or ecological grouping variables. To highlight how a quantitative trait‐based approach can provide new insights, we describe multiple targeted examples and end by suggesting next steps in the rapidly growing field of fungal functional ecology. 相似文献
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70.
The striated muscles of Derocheilocaris typica consist of mononucleated cells, each containing one filament bundle. Large muscles consist of two or more cells adjacent to each other. The mitochondria line up along the filament bundle on one side. The nucleus is situated in the mitochondrial row and has a small cytoplasmic area around it filled with glycogen. The sarcomeres are between 3 and 6 μm long. The Z-line and H band are present. Six thin filaments surround one thick filament. All muscles belong to the phasic type. The tubular system emanates from the ends of the muscle cell and penetrates the whole cell. The tubules are formed as cisterns, which also open at the cell membrane at the level of the I bands. They have sarcoplasmic cisterns on both sides forming a continuous triad system. Partially transformed epidermal cells mediate muscle insertions on the cuticle. Tendons are formed with the transformed epidermal cells being supplemented by fibroblasts forming collagen fibers. Dorsal and ventral abdominal muscles are innervated from the dorso-lateral nerve arising from the nerve chain. Each muscle cell receives one axon, which forms one synapse on the mitochondrial-free side of the muscles. Axons form terminal spines, which make axo-axonal synapses. 相似文献