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31.
Lakhu M. Keshvara Elizabeth M. Newton A. Heather Good Ole Hindsgaul Monica M. Palcic 《Glycoconjugate journal》1992,9(1):16-20
ELISA assays have been developed for (1–3)N-acetylgalactosaminyltransferase (blood group A transferase) and (1–3)galactosyltransferase (blood group B transferase) activities. In these assays, microtitre plates coated with the bovine serum albumin conjugate of a synthetic Fuc1–2Gal-R acceptor substrate are incubated with the appropriate nucleotide donor (UDP-GalNAc or UDP-Gal) and human serum as the enzyme source. The resulting trisaccharide products Fuc1–2(GalNAc1–3)Gal-R-BSA or Fuc1–2(Gal1–3)Gal-R-BSA are detected and quantified with monoclonal antibodies selected not to cross-react with the substrate structure. With less than a microliter of human serum, product formation is proportional to enzyme concentration and to time of incubation of up to 90 min. 相似文献
32.
Pancreatic adenocarcinomas induced in Syrian hamsters by treatment with N-nitrosobis(2-oxopropyl) amine express blood group A antigen, which is absent in normal pancreatic cells. On membrane glycoproteins purified from tumors, blood group A antigen has been found to be expressed on multiantennary Asn-linked complex glycans. In this study, we investigated the effect of inhibitors of Asn-glycan processing on blood group A antigen bearing glycan structures in a cell line (PC-1) established from a primary induced pancreatic cancer. Expression of blood group A antigen on cells and in membrane preparations was blocked by treatment with 1-deoxymannojirimycin, an inhibitor of mannosidase I, but was retained after treatment with swainsonine, an inhibitor of mannosidase II. However, swainsonine treatment altered the glycan structure associated with blood group A antigen from an endoglycosidase H resistant type to a sensitive type, indicating that the blood group A structure might shift from a complex type to a hybrid type glycan by this treatment. These results demonstrate that Asn-linked glycans carry the major blood group A antigens in PC-1 cells. 相似文献
33.
Donna Robbins Colin A. Chapman Richard W. Wrangham 《Primates; journal of primatology》1991,32(3):301-305
Gibbons and spider monkeys have similar diets, body size, and locomotor patterns. They are therefore expected to be subject
to similar socioecological rules. However their grouping patterns differ. Gibbons live in small stable groups, whereas spider
monkey form unstable sub-groups that vary from small to large during different seasons. If similar principles apply to the
two species, food abundance should vary more for spider monkeys than for gibbons; food density should be similar for the two
species when spider monkey sub-groups are the same size as gibbon groups; and the highest level of food abundance should be
higher for spider monkeys than for gibbons. These predictions are upheld for a comparison of particular populations ofHylobates muelleri andAteles geoffroyi. 相似文献
34.
Optimal hunting group size: the need for lions to defend their kills against loss to spotted hyaenas 总被引:4,自引:1,他引:3
S.M. COOPER 《African Journal of Ecology》1991,29(2):130-136
This paper presents preliminary evidence that kleptoparasitism by spotted hyaenas may influence optimal hunting group size of lions. In the absence of adult male lions, hyaenas can drive female and subadult lions off their kills provided they outnumber the lions by a factor of four. Hence the larger the group of lions on the kill, the greater their chance of defending their food against invading hyaenas. At Savuti, where there was a shortage of adult male lions, the groups of female and subadult lions lost almost 20% of their food to hyaenas. Losses were most frequent for those living in small groups. These lions were often satiated by the time the hyaenas acquired the kill, so the hyaenas did not cause immediate need, yet constituted a constant energy drain on lions by forcing them to hunt more frequently. The implications of these observations for modelling optimal hunting group size of lions are discussed. 相似文献
35.
Peter Mitchell 《Bioscience reports》1991,11(6):297-346
Chemical transformations, like osmotic translocations, are transport processes when looked at in detail. In chemiosmotic systems, the pathways of specific ligand conduction are spatially orientated through osmoenzymes and porters in which the actions of chemical group, electron and solute transfer occur as vectorial (or higher tensorial order) diffusion processes down gradients of total potential energy that represent real spatially-directed fields of force. Thus, it has been possible to describe classical bag-of-enzymes biochemistry as well as membrane biochemistry in terms of transport. But it would not have been possible to explain biological transport in terms of classical transformational biochemistry or chemistry. The recognition of this conceptual asymmetry in favour of transport has seemed to be upsetting to some biochemists and chemists; and they have resisted the shift towards thinking primarily in terms of the vectorial forces and co-linear displacements of ligands in place of their much less informative scalar products that correspond to the conventional scalar energies. Nevertheless, considerable progress has been made in establishing vectorial metabolism and osmochemistry as acceptable biochemical disciplines embracing transport and metabolism, and bioenergetics has been fundamentally transformed as a result. 相似文献
36.
S. J. Ochatt 《Plant Cell, Tissue and Organ Culture》1991,25(2):161-167
Leaf protoplasts of axenic shoot cultures of Lonicera nitida cv Maigrun underwent sustained division to give multicellular colonies (microcalli) on a modified, ammonium-free MS (Murashige & Skoog) medium containing 0.5 mg l-1 NAA (1-naphthaleneacetic acid), 1.0 mg l-1 BAP (6-benzylaminopurine) and 150 mg l-1 casein enzymatic hydrolysate. Callus was produced upon transfer of cell colonies to MS medium with 2.0 mg l-1 NAA and 0.2 mg l-1 BAP. About 110 days from isolation protoplast-derived shoots were regenerated on a half-strength MS medium with 0.01 mg l-1 NAA, 5.0 mg l-1 BAP, 0.5 mg l-1 zeatin and a complex mixture of group B vitamins. The replacement of such mixture by 250 mg l-1 casein enzymatic hydrolysate promoted rhizogenesis in calli, with shoot buds being subsequently regenerated from the protoplast-derived roots. Micropropagation of protoplast-derived shoots (of either origin) was difficult, due to a strong apical dominance, but could be accomplished by transferring single-node explants to half-strength MS medium with 1.5 mg l-1 BAP. Such shoots were, in turn, successfully rooted and transferred to the glasshouse where they completed acclimatization.Abbreviations BAP
6-benzylaminopurine
- CPW
Power et al. (1989) medium
- 2,4-D
2,4-dichlorophenoxyacetic acid
- FDA
fluorescein diacetate
- F.P.E.
final plating efficiency
- f.wt.
fresh weight
- IAA
4-indole-3yl-acetic acid
- IBA
4-indole-3yl-butyric acid
- I.P.E.
initial plating efficiency
- MES
2-N-morpholinoethane sulfonic acid
- M.P.E.
intermediate plating efficiency
- MS
Murashige & Skoog (1962) medium
- NAA
1-naphthaleneacetic acid
- PVP-10
polyvinylpirrolidone
- Av MW 10,000, TIBA
2,3,5-tri-iodobenzoic acid
- Z
zeatin 相似文献
37.
Expansion of the canine A blood group system 总被引:1,自引:0,他引:1
A detailed study of the canine A blood group system was undertaken, resulting in the expansion of this system into a three-factor, four-allelic one with the recognition of an additional subtype, a3. The serological and extensive family data supported the proposed genetic theory of four alleles with dominance with the order being Aa1, Aa2, Aa3 and A-. Gene frequencies of the alleles were determined in various breeds of dogs with frequencies in the general Brisbane population being 0.244 (Aa1), 0.042 (Aa2), 0.045 (Aa3) and 0.669 (A-). 相似文献
38.
E. Hanlidou S. Kokkini A. M. Bosabalidis J. -M. Bessière 《Plant Systematics and Evolution》1991,177(1-2):17-26
Plant material ofCalamintha menthifolia was collected from two populations grown in the Vikos-Aoos area (NW. Greece). The structure and ontogeny of the glandular trichomes and the chemical composition of the secreted essential oil were studied. The leaves ofC. menthifolia have numerous glandular trichomes of three morphological distinct types: 1) glandular scales with a unicellular foot and stalk, and a 12-celled head, 2) glandular hairs with a unicellular foot and stalk, and a unicellular pear-shaped head and 3) glandular hairs with a unicellular foot, a bicellular stalk and a unicellular elongated head. Qualitative and quantitative GC-MS analyses of the essential oils revealed piperitone oxide as the main constituent in both populations. In the light of these results the relationships beweenC. menthifolia and other members of theSatureja group as well as its taxonomy are discussed. 相似文献
39.
W. B. RUDMAN 《Zoological Journal of the Linnean Society》1985,83(3):241-299
Nineteen species of chromodorid nudibranchs are described including three new species of Chromodoris , two of Glossodoris and one each of Noumea, Cadlina and Thorunna from the Indo-West Pacific. The colour of all species is white with either a single yellow or gold band at the edge of the mantle or a double band of red and yellow, or orange and red or purple. All previously described species with similar colour patterns, from both the Indo-West Pacific and other regions are discussed. 相似文献
40.
Visible absorption and CD spectral and potentiometric studies on the His- and Tyr-containing ternary copper(II) complexes Cu(A)(L-B), where A refers to L-His, D-His, or L-Tyr and B to Lys, Tyr, Trp, Phe, Ala, Val, Arg, Glu, Asn, Gln, Ser, or Thr, were made to study ligand-ligand interactions in the complexes. While the CD spectral magnitudes in the d—d region are additive in the absence of side chain interactions and can be estimated from the magnitudes for the ternary systems involving DL-A or DL-B, deviation from the additivity was observed for Cu(L-His)(L-B) (B = LysH, Tyr, Trp, or Phe) and Cu(L-Tyr)(L-Trp). From the stability constants determined at 25 °C and I = 0.1 M (KNO3), the equilibrium constants, K, for the following hypothetical equilibria were calculated to be large (0.14–0.60) for formation of Cu(L-/D-His)(L-B)(B = Tyr or Trp) and Cu(D-His)(L-Phe) with Cu(en)(L-Ala) as standard: The positive values indicate the stabilization due to the stacking between the imidazole ring of His and the aromatic side chain of L-B. Solvent dependence of the CD spectra for Cu(L-His)(L-LysH) and Cu(L-His) L-Trp) further supported the existence of the intramolecular electrostatic and hydrophobic interactions. 相似文献