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1.
Fast atom bombardment tandem mass spectrometry has been used in the characterization of non-, mono-, di- and trisulfated disaccharides from chondriotin sulfate, dermatan sulfate and hyaluronan. The positional isomers of the sulfate group of mono- and disulfated disaccharides were distinguished from each other by both positive- and negative-ion fast atom bombardment tandem mass spectra, which gave sufficient information characteristic of the isomers. The anomeric isomers of nonsulfated disaccharides were characterized by the technique in the positive-ion mode. This fast atom bombardment collision induced dissociation mass spectrometry/mass spectrometry technique was also applied successfully to the characterization of trisulfated disaccharide.Abbreviations FABMS
fast atom bombardment mass spectrometry
- MI
metastable ion
- CID
collision induced dissociation
- MIKE
mass analysed ion kinetic energy
- SIMS
secondary ion mass spectrometry
- MS/MS
mass spectrometry/mass spectrometry
- HPLC
high performance liquid chromatography
- GlcA
d-gluco-4-enepyranosyluronic acid
- CS
chondroitin sulfate
- DS
dermatan sulfate
- HA
hyaluronan
- UA-GalNAc
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-d-galactose
- UA-GalNAc4S
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose
- UA-GalNAc6S
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose
- UA2S-GalNAc
2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-d-galactose
- UA2S-GalNAc4S
2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-4-O-sulfo-d-galactose
- UA2S-GalNAc6S
2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-6-O-sulfo-d-galactose
- UA-GalNAcDiS
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-4,6-di-O-sulfo-d-galactose
- UA2S-GalNAcDiS
2-acetamido-2-deoxy-3-O-(2-O-sulfo--d-gluco-4-enepyranosyluronic acid)-4,6-di-O-sulfo-d-galactose
- UA-GlcNAc
2-acetamido-2-deoxy-3-O-(-d-gluco-4-enepyranosyluronic acid)-d-glucose 相似文献
2.
Raymond Delpech V Ihara M Coddou C Matsuda K Sattelle DB 《Invertebrate neuroscience : IN》2003,5(1):29-35
Nereistoxin (NTX), a natural neurotoxin from the salivary glands of the marine annelid worm Lumbriconereis heteropoda, is highly toxic to insects. Its synthetic analogue, Cartap, was the first commercial insecticide based on a natural product. We have used voltage-clamp electrophysiology to compare the actions of NTX on recombinant nicotinic acetylcholine receptors (nicotinic AChRs) expressed in Xenopus laevis oocytes following nuclear injection of cDNAs. The recombinant nicotinic AChRs investigated were chicken 7, chicken 42 and the Drosophila melanogaster/chicken hybrid receptors SAD/2 and ALS/2. No agonist action of NTX (0.1–100 M) was observed on chicken 7, chicken 42 and the Drosophila/chicken hybrid nicotinic AChRs. Currents elicited by ACh were reduced in amplitude by NTX in a dose-dependent manner. The toxin was slightly more potent on recombinant Drosophila/vertebrate hybrid receptors than on vertebrate homomeric (7) or heteromeric (42) nicotinic AChRs. Block by NTX of the chicken 7, chicken 42 and the SAD/2 and ALS/2 Drosophila/chicken hybrid receptors is in all cases non-competitive. Thus, the site of action on nicotinic AChRs of NTX, to which the insecticide Cartap is metabolised in insects, differs from that of the major nicotinic AChR-active insecticide, imidacloprid. 相似文献
3.
In this study the comparative TLC immunostaining investigation of neutral GSLs and gangliosides from human skeletal and heart muscle is described. A panel of specific polyclonal and monoclonal antibodies as well as the GM1-specific choleragenoid were used for the overlay assays, combined with preceding neuraminidase treatment of gangliosides on TLC plates. This approach proved homologies but also quantitative and qualitative differences in the expression of ganglio-, globo- and neolacto-series neutral GSLs and gangliosides in these two types of striated muscle tissue within the same species. The main neutral GSL in skeletal muscle was LacCer, followed by GbOse3Cer, GbOse4Cer, nLcOse4Cer and monohexosylceramide, whereas in heart muscle GbOse3Cer and GbOse4Cer were the predominant neutral GSLs beside small quantities of LacCer, nLcOse4Cer and monohexosylceramide. No ganglio-series neutral GSLs and no Forssman GSL were found in either muscle tissue. GM3(Neu5Ac) was the major ganglioside, comprising almost 70% in skeletal and about 50% in cardiac muscle total gangliosides. GM2 was found in skeletal muscle only, while GD3 and GM1b-type gangliosides (GM1b and GD1) were undetectable in both tissues. GM1a-core gangliosides (GM1, GD1a, GD1b and GT1b) showed somewhat quantitative differences in each muscle; lactosamine-containing IV3Neu5Ac-nLcOse4Cer was detected in both specimens. Neutral GSLs were identified in TLC runs corresponding to e.g. 0.1 g muscle wet weight (GbOse3Cer, GbOse4Cer), and gangliosides GM3 and GM2 were elucidated in runs which corresponded to 0.2 g muscle tissue. Only 0.02 g and 0.004 g wet weight aliquots were necessary for unequivocal identification of neolacto-type and GM1-core gangliosides, respectively. Muscle is known for the lowest GSL concentration from all vertebrate tissues studied so far. Using the overlay technique, reliable GSL composition could be revealed, even from small muscle probes on a sub-orcinol and sub-resorcinol detection level. Abbreviations: ATCC, American Type Culture Collection; GSL(s), glycosphingolipid(s); HPLC, high performance liquid chromatography; HPTLC, high performance thin layer chromatography; Neu5Ac, N-acetylneuraminic acid; Neu5Gc, N-glycolylneuraminic acid [78]; PBS, phosphate buffered saline. The designation of the following glycosphingolipids follows the IUPAC-IUB recommendations [79] and the ganglioside nomenclature system of Svennerholm [80]. Lactosylceramide or LacCer, Gal1-4Glc1-1Cer; gangliotriaosylceramide or GgOse3Cer, GalNAc1-4Gal1-4Glc1-1Cer; gangliotetraosylceramide or GgOse4Cer, Gal1-3GalNAc1-4Gal1-4Glc1-1Cer; globotriaosylceramide or GbOse3Cer, Gal1-4Gal1-4Glc1-1Cer; globoside or globotetraosylceramide or GbOse4Cer, GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; Fo or Forssman GSL, GalNAc1-3GalNAc1-3Gal1-4Gal1-4Glc1-1Cer; paragloboside or lacto-N-neotetraosylceramide or nLcOse4Cer, Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; lacto-N-norhexaosylceramide or nLcOse6Cer, Gal1-4GlcNAc1-3Gal1-4GlcNAc1-3Gal1-4Glc1-1Cer; GM3, II3Neu5Ac-LacCer; GM2, II3Neu5Ac-GgOse3Cer; GM1 or GM1a, II3Neu5Ac-GgOse4Cer; GM1b, IV3Neu5Ac-GgOse4Cer; GD3, II3(Neu5Ac)2-LacCer; GD1a, IV3Neu5Ac,II3Neu5Ac-GgOse4Cer; GD1b, (II3Neu5Ac)2-GgOse4Cer; GD1, IV3Neu5Ac,III6Neu5Ac-GgOse4Cer; GT1b, IV3Neu5Ac,II3(Neu5Ac)2-GgOse4Cer; GQ1b, IV3(Neu5Ac)2, II3(Neu5Ac)2-GgOse4Cer. 相似文献
4.
Ritva Niemelä Jari Natunen Elina Brotherus Annamari Saarikangas Ossi Renkonen 《Glycoconjugate journal》1995,12(1):36-44
A partially purified preparation of 1,3-fucosyltransferase(s) from human milk was used to [14C]fucosylate oligosac-charides containing Gal1-4GlcNAc units. Substitution ofN-acetyllactosamine at position 3 with a -linkedN-acetylglucosamine enhanced the reactivity of the acceptor, whereas similar substitution at position 6 was inhibitory. Thus, the trisaccharide GlcNAcl-6Gal1-4GlcNAc (5), the branched tetrasaccharide GlcNAc1-3(GlcNAc1-6)Gal1-4GlcNAc (11) and the triply branched decasaccharide GlcNAc1-3(GlcNAc1-6)Gall-4GlcNAc1-3[GlcNAc1-3(GlcNAc1-6)Gal1-4GlcNAc1-6]Gal1-4GlcNAc (26) gave remarkably poor yields of 1,3-fucosylated products in comparison to GlcNAc1-3Gal1-4GlcNAc (3). 1,4-Galactosyl derivatives of5 and11, however, gave good yields of 1,3-fucosylated products, but the fucosylation was restricted to the distalN-acetyllactosamine units of Gal1-4GlcNAc1-6Gal1-4GlcNAc (16), Gal1-4GlcNAc1-3(Gal1-4GlcNAc1-6)Gal1-4GlcNAc (18) and also in Gal1-3Gal1-4GlcNAc1-3(Gal1-3Gal1-4GlcNAc1-6)Gal1-4GlcNAc (22). Immobilized wheat germ agglutinin (WGA), possessing high affinity for16 [1], revealed no affinity for the fucosylated derivative Gal1-4(Fuc1-3)GlcNAc1-6Gal1-4GlcNAc (17). The isomeric heptasaccharides Gal1-4(Fuc1-3)GlcNAc1-3(Gal1-4GlcNAc1-6)Gal1-4GlcNAc (19) and Gal1-4GlcNAc1-3[Gal1-4(Fuc1-3)GlcNAc1-6]Gal1-4GlcNAc (20) were readily separated from each other on WGA-agarose, and so were the isomeric nonasaccharides Gal1-3Gal1-4(Fuc1-3)GlcNAc1-3(Gal1-3Gal1-4GlcNAc1-6)Gal1-4GlcNAc (23) and Gal1-3Gal1-4GlcNAc1-3[Gal1-3Gal1-4(Fuc1-3)GlcNAc1-6]Gal1-4GlcNAc (24). 相似文献
5.
Cell-free extracts from Rhus typhina L. (staghorn sumach) leaves were found to catalyze the transfer of the galloyl moiety of -glucogallin (1-O-galloyl--D-glucose) to 1,6-di-O-galloyl--D-glucose, resulting in the specific formation of 1,2,6-tri-O-galloyl--D-glucose, an intermediate of gallotannin biosynthesis. The reaction product was unequivocally identified by co-chromatography with authentic references using reversed-phase high-performance liquid chromatography and by 1H-nuclear-magnetic-resonance spectroscopy.Abbreviations HPLC
high-performance liquid chromatography
- NMR
nuclear magnetic resonance 相似文献
6.
An overview of Acipenseriformes 总被引:14,自引:0,他引:14
Acipenseriformes occupy a special place in the history of ideas concerning fish evolution, but in many respects, phylogenetic studies of the group remain in their infancy. Even such basic questions as the monophyly of Acipenser (the largest genus) are unanswered. We define relationships based on comparative osteology, which allows us to incorporate well-preserved fossils into analyses. Acipenseriformes has existed at least since the Lower Jurassic (approximately 200 MYBP), and all fossil and recent taxa are from the Holarctic. Phylogenetic relationships among Paleozoic and Early Mesozoic actinopterygians are problematic, but most workers agree that Acipenseriformes is monophyletic and derived from some component of paleonisciform fishes. (Paleonisciformes is a grade of primitive non-neopterygian actinopterygians, sensu Gardiner 1993.) Taxa discussed in comparison here are: Cheirolepis, Polypterus, Mimia, Moythomasia, Birgeria, Saurichthys, Lepisosteus and Amia. We review generic diversity within the four nominal families of fossil and recent Acipenseriformes (Chondrosteidae, Peipiaosteidae, Polyodontidae, and Acipenseridae), and provide a cladogram summarizing osteological characters for those four groups. Monophyly of the two extant families is well-supported, but there are no comprehensive studies of all of the known species and specimens of Chondrosteidae and Peipiaosteidae. As a result, sister-group relationships among Chondrosteidae, Peipiaosteidae, and Acipenseroidei (= Polyodontidae + Acipenseridae) are unresolved. We discuss five features fundamental to the biology of acipenseriforms that benefit from the availability of our new phylogenetic hypothesis: (1) specializations of jaws and operculum relevant to jaw protrusion, feeding, and ram ventilation; (2) anadromy or potamodromy and demersal spawning; (3) paedomorphosis and evolution of the group; (4) the bioégeography of Asian and North American polyodontids and scaphirhynchines; and (5) the great abundance of electroreceptive organs in the rostral and opercular regions. Finally, we summarize our nomenclatural recommendations. 相似文献
7.
B. P. Gottikh A. A. Krayevsky M. K. Kukhanova A. A. Jatsyna A. M. Kritzyn C. L. Florentiev 《Molecular biology reports》1973,1(3):173-178
Peptide acceptor properties of phenylalanine and glycine esters of 9-(2,3-dihydroxypropyl-1)-adenine and 1-(2,3-dihydroxypropyl-1)-4-thiouracyl were investigated. All these esters appeared to be powerful inhibitors of polyphenylalanine synthesis in E. coli MRE-600 ribosomes charged with poly U. Like puromycin, esters of adenine derivatives accepted the AcPhe residue from Ac-[14C] Phe-tRNA in a ribosomal system charged with poly U. However, peptidyl esters of 9-(2,3-dihydroxypropyl-1)-adenine remained bound with ribosomes. The structure of the peptide esters synthesized was ascertained after dissociation of ribosomes into subparticles by direct comparison with the synthetic specimens.Abbreviations AcPhe
acetyl-l-phenylalanine
- HP-Ade
9-(2,3-dihydroxypropyl-1)-adenine
- Phe-HP-Ade and Gly-HP-Ade
l-phenylalanine and glycine esters of HP-Ade
- Phe-HP-TUra
l-phenylalanine ester 1-(2,3-dihydroxypropyl-1)-4-thiouracyl
- AcPhePhe-HP-Ade and AcPheGly-HP-Ade
acetyl-l-diphenylalanine and acetyl-l-phenylalanylglycine esters of HP-Ade respectively
- AcPhe-puromycin
acetyl-l-phenylalanyl-puromycin 相似文献
8.
Summary
Eimeria cyclopei n.sp. is described from the silky anteater, Cyclopes didactylus, from Pará State, north Brazil. Undifferentiated oocysts, passed in the faeces, complete sporulation in seven days at 26 to 28°C. Oocysts are ellipsoidal to sub-spherical, with a mean size of 28.1 × 23.6 m: the wall is 1.5 to 2.0 m thick, apparently with an outer thin, colourless membrane and two inner, thicker, striated and yellowish layers. There is no micropyle, oocyst residuum or polar body. The mean measurements of sporocysts are 19.0 × 9.0 m, and they are slightly asymmetrical, elongate pear-shape, with a plug-shaped Steida body projecting beyond the end of the sporocyst. Sporozoites are as long as or longer than the sporocysts: The sporocyst residuum is scattered between sporozoites in younger specimens and becomes condensed into rounded mass in older ones. The endogenous stages occur in the epithelial cells of the ileum, on the lumenal side of the host-cell nucleus. Uninucleate meront, microgamont and macrogamont precursors are recognizable morphologically. Mature meronts are 20.0 × 15.7 m some produce 12 to 20 merozoites which are 8.7 × 2.0 m, and others 10 to 26 merozoites which are 11.4 × 2.0 to 15.0 × 3.0 m. Mature microgamonts which are 27.5 × 24.1 m, produce from 150 to 170 microgametes of 7.1 × 1.0 m: microgametes have two flagella of unequal length. Mature macrogamonts are 28.4 × 24.5 m Eimeria choloepi n.sp. is recorded from the two-toed sloth, Choloepus didactylus, from the same area of Brazil. Undifferentiated oocysts, passed in the faeces, complete sporulation in 23 days at 26 to 28°C. Oocysts with a mean size of 23.0 × 20.3 m, have a wall 2.0 to 2.5 m thick which is composed of two thick, yellowish and striated outer layers and a delicate, colourless inner one. There is no micropyle, oocyst residuum or polar granule. Mature sporocysts with a mean size of 11.3 × 7.1 m, are ellipsoidal to egg-shaped and have a poorly developed Steida body. The sporocyst residuum is composed of a small number of large globules: The sporozoites are longer than the sporocyst and strongly recurved. The endogenous stages occur in epithelial cells of the ileum, on the lumenal side of the host-cell nucleus. Dimorphic meronts produce 8 to 18 merozoites which are either 13.0 × 2.0 m or 13.0 × 3.0 m. Microgamonts produce 50 to 80 microgametes of 8.0 × 1.0 m. Mature macrogamonts are 18.3 × 17.9 m. ac]19820212 相似文献
9.
Glycosylation is one of the most important post-translational modifications and it is clear that the single step of -1,4-galactosylation is performed by a family of -1,4-galactosyltransferases (4-GalTs) and that each member of this family may play a distinct role in different tissues and cells. In this study, we characterized the gene expression of six 4-GalTs in mouse testis and analyzed the changes of galactosylation of testis glycoproteins during postnatal development. Northern blot analysis revealed that 4-GalT-I and 4-GalT-IV were expressed mainly in newborn mouse testis and that the expression of 4-GalT-II increased markedly and persisted at the highest levels in adult mouse testis. The expression of 4-GalT-III and 4-GalT-V, however, remained relatively at low levels during mouse testicular development. In contrast, the expression of 4-GalT-VI was undetectable in mouse testis. The gene expression of 4-GalT-II in mouse testis was further analyzed by in situ hybridization due to its unique expression pattern. Strong hybridization signals were detected in the seminiferous tubules and the expression varied among the different stages of spermatogenic differentiation. The distinct gene expression patterns of 4-GalTs in mouse testis could affect the differential galactosylation of testis glycoproteins, as revealed by lectin histochemistry analysis. 相似文献
10.
Improved rate of callus induction from rice anther culture following microscopic staging of microspores in iron alum-haematoxylin 总被引:1,自引:0,他引:1
H. S. Gupta D. N. Borthakur 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1987,74(1):95-99
Summary High frequencies of callusing were obtained in indica rice from the microspores which were staged in acetic acid iron alum-haematoxylin stain prior to culture on G5 medium. Two local varieties, Khonorullo and Namyi, and two advance pre-release cultures, PK 1-1-3 and PK 12-22, were used in this investigation. All the cultures exhibited a wide adaptation to varying medium; however, the frequency of callusing was highest (45.5%) in PK 1-1-3 followed by PK 12-22 (32.4%) and Khonorullo (31.6%). Cold shock (10 °C) for 11 days enhanced the frequency of callusing by 200% in Khonorullo. 相似文献
11.
Jan-Olof Berg 《Current microbiology》1981,5(1):13-17
The localizations of six glycosidases produced byBacteroides fragilis—-glucosidase, -glucosidase, -galactosidase, -galactosidase, -N-acetylglucosaminidase, and -l-fucosidase—were studied. Cell fractions and cell extracts were obtained by Triton X-100 release, by disruption by freeze-pressing and sonication, and by osmotic release. Isoelectric focusing of a cytoplasmic and of a Triton X-100 extract of the cell wall fraction was performed and revealed differences in the relative distribution of differently charged forms of -N-acetylglucosaminidase. -Galactosidase and alkaline phosphatase were used as cytoplasmic and periplasmic markers, respectively. It is concluded that inB. fragilis -glucosidase is periplasmic, -l-fucosidase and -galactosidase are cytoplasmic, and -n-acetylglucosaminidase is cell associated and bound to the cell envelope by hydrophobic interactions. -Glucosidase and -galactosidase are localized cytoplasmically and/or located in the cell envelope. 相似文献
12.
Shoot tips of wheat as an alternative source for regenerable embryogenic callus cultures 总被引:5,自引:0,他引:5
Shoot tips of Triticum aestivum L. cvs. Turbo and Nandu, both summer wheat varieties, were excised from 4 and 10 day-old seedlings, and used for induction of embryogenic callus. A modified L3 medium, supplemented with 10 M 2,4-dichlorophenoxyacetic acid (2,4-d) for culture initiation, and 5 M 2,4-d for subculturing, was optimal; 90% of 4 day-old Turbo seedlings formed embryogenic callus. Optimal plant regeneration was achieved from callus incubated on a modified MS medium without 2,4-d, but supplemented with 2.22 M 6-benzylaminopurine and 0.27 M naphthaleneacetic acid. Plantlets formed via embryogenesis from all embryogenic Turbo calli initiated from 4 day-old explants, with a mean number of 8 regenerants per explant. Regeneration occured via embryogenesis only. Results obtained using Nandu were within the same range.Abbreviations BA
6-benzylaminopurine
- 2,4-d
2,4-dichlorophenoxyacetic acid
- NAA
naphthaleneacetic acid 相似文献
13.
Callus induction and plant regeneration in Vetiveria zizanioides 总被引:7,自引:0,他引:7
Marco Mucciarelli Marisa Gallino Silvano Scannerini Massimo Maffei 《Plant Cell, Tissue and Organ Culture》1993,35(3):267-271
Callus induction was obtained from basal parts of Vetiveria zizanioides Stapf. leaves cultured on Murashige and Skoog (MS) medium supplemented with 9.0 M 2,4-dichlorophenoxyacetic acid (2,4-d), 5.7 M indoleacetic acid (IAA) and 4.6 M kinetin. Calli were maintained on MS medium with the addition of 0.9 M 2,4-d and 2.3 M kinetin. Shoot formation was obtained from fast growing 14-day-old callus on the same basal medium supplemented with 0.9 M 2,4-d and 9.3 M kinetin. Embryo-like structures were observed. When transferred to basal medium, shoots readily developed roots. Fully developed regenerated plants were then successfully established in soil. 相似文献
14.
Rudolf Geyer Silvia Diabaté Hildegard Geyer Hans-Dieter Klenk Heiner Niemann Stephan Stirm 《Glycoconjugate journal》1987,4(1):17-32
Fowl plague virus, strain Dutch, was metabolically labeled withd-[2-3H]mannose, or withd-[6-3H]glucosamine, and the small subunit (HA2; 0.8 mg in total) of the viral hemagglutinin was isolated by preparative sodium dodecylsulfate-polyacrylamide gel electrophoresis. After proteolytic digestion, the radioactive oligosaccharides were sequentially liberated from the glycopeptides by treatment with different endo--N-acetylglucosaminidases and with peptide:N-glycosidase or, finally, by hydrazinolysis. In this manner, four groups of glycans could be obtained by consecutive gel filtrations and were subfractionated by HPLC. The structures of the individual oligosaccharides were analyzed by micromethylation, by acetolysis or by digestion with exoglycosidases. The major species amongst the high mannose glycans at Ans-406 of the viral glycopolypeptide were found to be Man1-2Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNac1-4GlcNAc and Man1-3(Man1-2Man1-6)Man1-6(Man1-2Man1-2Man1-3)Man1-4GlcNAc1-4GlcNAc, while the complex glycans at Asn-478 are predominantly GlcNAc1-2Man1-3(GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc (lacking, in part, one of the outerN-acetylglucosamine residues) and GlcNAc1-2Man1-3(Gal1-4GlcNAc1-2Man1-6)Man1-4GlcNAc1-4GlcNAc.Abbreviation BSA
bovine serum albumin
- endo D (F,H)
endo--N-acetyl-d-glucosaminidase D (F,H)
- HA
hemagglutinin (HA1, large subunit of HA
- HA2
small subunit
- FPV
fowl plague virus
- PNGase F
peptide:N-glycosidase F
- SDS
sodium dodecylsulfate 相似文献
15.
A simple synthesis of octyl 3,6-di-O-(-d-mannopyranosyl)--d-mannopyranoside is described. The key features of the synthetic scheme are the formation of the -mannosidic linkage by 1-O-alkylation of 2,3,4,6-tetra-O-acetyl-,-d-mannopyranose with octyl iodide and glycosylation of unprotected octyl -d-mannopyranoside using limiting acetobromomannose. The trisaccharide is shown to be an acceptor forN-acetylglucosaminyltransferase-I with aK
M of 585 µm. 相似文献
16.
Jürgen Haffer 《Journal of Ornithology》1997,138(1):61-72
Zusammenfassung Die Ablösung des essentialistischen (typologischen) Denkens bei Vertretern der systematischen Ornithologie durch das darwinistische (evolutionäre) Populationsdenken um die letzte Jahrhundertwende bildete eine scharfe historische Diskontinuität. Die essentialistische Denkweise, die in Europa während des 19. Jahrhunderts dominierend war, erreichte ihr Ende im Werk vonOtto Kleinschmidt (1870–1954), dem letzten Vertreter derPallas-Schlegel Schule. In den ersten Jahrzehnten dieses Jahrhunderts wurde die evolutionäre Denkweise der Ornithologen der nordamerikanischenBaird-Coues Schule und der europäischenSeebohm-Harter Schule bestimmend. Die weite taxonomische Begrenzung von Arten durch die Ornithologen der essentialistischenPallas-Schlegel Schule und der evolutionären Mikrotaxonomie täuscht Gemeinsamkeiten dieser Schulen vor; im theoretischen Denken ihrer Vertreter bestanden fundamentale Unterschiede. Gegenwärtig ist eine Entwicklung innerhalb der evolutionären Mikrotaxonomie erkennbar, die möglicherweise in naher Zukunft zu einer Trennung in zwei Schulen mit verschiedenen Artkonzepten und unterschiedlicher Artabgrenzung führen wird: (a) Weite Artabgrenzung (mit relativ wenigen polytypischen Arten) und (b) enge Artabgrenzung (mit relativ vielen monotypischen Arten). Dazwischen vermitteln intermediäre Vorschläge. Der wissenschaftliche Naturschutz bezieht sich heute auf evolutionär signifikante Einheiten und ist unabhängig von den verschiedenen systematischen Konzeptionen über die Art.
Essentialistic and evolutionary thinking in the field of systematic ornithology during the 19th and 20th century
Essentialistic thinking dominated systematic ornithology in North America during the first half of the 19th century and in Europe until the beginning of this century, when evolutionary thinking superseded it marking a sharp historical discontinuity. Evolutionary thinking of the ornithologists of the North AmericanBaird-Coues school and of the EuropeanSeebohm-Hartert school prevailed increasingly from the late 19th century and early 20th century onward, respectively. The representatives of the essentialisticPallas-Schlegel school and of evolutionary microtaxonomy delimited species taxa broadly which common procedure concealed the fundamental differences in their theoretical thinking. Within the near future, evolutionary microtaxonomy may split into two different schools supporting different species concepts and a different delimitation of species taxa: (a) Wide species limits resulting in relatively few polytypic species taxa and (b) narrow species limits resulting in numerous monotypic species taxa; intermediate views connect these extremes. Conservation biology refers to evolutionarily significant units and is independent of the different views of systematists as to what constitutes a species.相似文献
17.
Electrospray ionization mass spectra of phycocyaninsof eight samples from natural blooms of Microcystis aeruginosa f. aeruginosa collectedat different eutrophic pond and lakes indicated thatthe subunits of phycocyanins in the samespecies have different molecular masses, whereas the subunits have almost constant molecularmasses. A negative linear relationship between themolecular mass of subunit of phycocyanin andthe concentration of chlorophyll of natural andcolonial cyanobacterial samples was found. Aninterannual similarity of the subunitmolecular masses of phycocyanins was observed fromsamples collected at the same sampling site at LakeKasumigaura during 1994 and 1995. A locationalvariability of the subunit molecular massesof phycocyanins was also observed among samplescollected at three eutrophic pond and lakes. 相似文献
18.
Lai-Xi Wang Nadejda V. Pavlova Su-Chen Li Yu-Teh Li Yuan C. Lee 《Glycoconjugate journal》1996,13(3):359-365
4-Methylumbelliferyl 6-O-benzyl--d-lactoside (6Bn-MU-Lac) and some related compounds were synthesizedvia different selective reactions including phase-transfer glycosylation. Their suitability as substrates for a fluorometric assay of ceramide glycanase (CGase) was evaluated. Among others, the 6Bn-MU-Lac, which is resistant to exogalactosidase, was found to be a suitable substrate for routine assay of the CGase activity. For American leech CGase, theK
m value is 0.232 mM at pH 5.
Abbreviations: CGase, ceramide glycanase; Gal, galactose; Glc, Glucose; Lac, lactose; MU, 4-methylumbelliferone; MU-Lac, 4-methylumbelliferyl -d-lactoside; bBn-Lac, 6-O-benzyl-lactose; 6Bn-MU-Lac, 4-methylumbelliferyl 6-Obenzyl--d-lactoside; 46Bd-MU-Lac, 4-methylumbelliferyl 4,6-O-benzylidene--d-lactoside; MU-Cel, 4-methylumbellifery -d-cellobioside; 46Bd-MU-Cel, 4-methylumbelliferyl 4,6-O-benzylidene--d-cellobioside; TLC, thin layer chromatography;1H-NMR, proton nuclear magnetic resonance; GSL, glycosphingolipids; CSA, 10-camphorsulfonic acid. See Scheme 1 for chemical structures. 相似文献
19.
Roy Douglas Pearson 《Acta biotheoretica》1981,30(3):171-176
Variation or rearrangement of regulatory genes is responsible for cellular malignant change. These types of chromosomal variations also produce heterochrony or paedomorphic evolution at the organismal level. Analogously, neoplasia represents a cellular macroevolutionary event, and a tumour can be said to be an evolved population of cells. To understand this cellular evolution to malignancy, it may be necessary to go beyond a clonal selection (adaptationist) explanation of neoplastic alteration. In the pericellular environment natural selection consists of the organizational restraints of surrounding cells as well as the host's immunological surveillance and non-specific monocyte-macrophage systems. Indirect evidence suggests that success for the neoplasm depends not upon clonal selection, but solely upon a genetic methodology—the function of which is to elude selection.The author has coined the term cellular heterochrony to illustrate analogic similarities in the molecular modes of speciation between anaplastic cancer cells and the heterochronic evolution of organisms. By reverting to a juvenile (embryonic) repertoire of cellular behaviour a tumour secures its own tenure or niche by usurping the host's armamentarium of selection forces, employing many of the same or similar methods by which implanting and invading tissues of the mammalian embryo forestall maternal detection and rejection. A number of ways by which the tumour blocks, subverts or evades selection are discussed. 相似文献
20.
Summary A detailed conformational analysis was performed for the synthetic branched trisaccharide -d-Man-NAc-(14)-[-d-Glc-(13)]-l-Rha 1 which represents the repeating unit of the O-antigenic polysaccharide of Aeromonas salmonicida. The study was based on 26 experimental NOE curves from 1D transient NOE experiments, employing Gaussian-shaped inversion pulses at 600 MHz. Eight of the NOE curves were interglycosidic and thus useful for an analysis of glycosidic linkage orientations. Metropolis Monte Carlo (MMC) simulations and minimum-energy calculations with the program GEGOP were used to obtain theoretical NOE curves which were compared to the experimental ones. MMC simulations with different temperature parameters of 310, 600, 900 and 2000 K allowed identification of NOEs which are sensitive towards different conformation distributions-not only different conformations-at both glycosidic linkages in 1. A comparison of trisaccharide 1 with the constituent disaccharides -d-ManNAc-(14)-l-Rha 2 and -d-Glc-(13)-l-Rha 3 revealed effects of branching on glycosidic linkage flexibility. A quantitative evaluation was facilitated by the introduction of entropy-related flexibility parameters. Our study indicates a notable restriction of flexibility, especially at the (13) linkage in 1. Although overall flexibility in 1 is reduced as compared to the constituent disaccharides 2 and 3, it cannot be neglected altogether. In summary, combined transient NOE experiments and MMC simulations provide a simple approach to analyse glycosidic linkage flexibility. 相似文献