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81.
Previously, treatment of Tamm-Horsfall glycoprotein (THp) from different
donors with endo-beta-galactosidase has been shown to liberate a tetra- and
a Sd(a)-active pentasaccharide, concluding the presence of N-linked
carbohydrate chains containing additional N - acetyllactosamine units.
These type of oligosaccharides were not found in a detailed structure
elucidation of the carbohydrate moiety of THp of one male donor, suggesting
a donor-specific feature for these type of structures. Therefore, THp was
isolated from four healthy male donors and each subjected to
endo-beta-galactosidase treatment in order to release these tetra- and
Sd(a)-active pentasaccharide. Differences were observed in the total amount
of released tetra- and Sda-active pentasaccharide of the used donors (42,
470, 478, 718 microg/100 mg THp), indicating that the presence of repeating
N-acetyllactosamine units incorporated into the N-glycan moiety of THp is
donor specific. Furthermore, a higher expression of the Sd(a) determinant
on antennae which display N-acetyllactosamine elongation was observed,
suggesting a better accessibility for the
beta-N-acetylgalactosaminyltransferase. In order to characterize the
N-glycans containing repeating N- acetyllactosamine units, carbohydrate
chains were enzymatically released from THp and isolated. The
tetraantennary fraction, which accounts for more than 33% of the total
carbohydrate moiety of THp, was used to isolate oligosaccharides containing
additional N - acetyllactosamine units. Five N-linked tetraantennary
oligosaccharides containing a repeating N-acetyllactosamine unit were
identified, varying from structures bearing four Sd(a) determinants to
structures containing no Sd(a) determinant (see below). One compound was
used in order to specify the branch location of the additional N-
acetyllactosamine unit, and it appeared that only the Gal-6' and Gal-8'
residues were occupied by a repeating N -acetyllactosamine unit.
相似文献
82.
Geographical variation in acoustic signals of the planthopper, Nilaparvata bakeri (Muir), in Asia: species recognition and sexual selection 总被引:1,自引:0,他引:1
MICHAEL F. CLARIDGE JOHN C. MORGAN 《Biological journal of the Linnean Society. Linnean Society of London》1993,48(3):267-281
Populations of the planthopper .Nilaparvata bakeri (Muir) were sampled from the Philippines (Luzon), Indonesia (Bali), India (Bihar) and Sri Lanka (Central Province) from the grass Leersia hexandra (Schwartz), and cultured in Cardiff. Low intensity vibratory signals produced by males and females during mate location and courtship were recorded and analysed. Obvious differences were found between male calling songs of insects from the Philippines and those from the other three areas. Smaller differences were detected between the Indonesian, Indian and Sri Lankan populations. Hybrids between Philippine and Indonesian, and Indonesian and Sri Lankan, insects were obtained freely in the laboratory. Male calls of F, hybrids were variable and intermediate between parentals. Mate choice experiments showed no significant assortative mating between the different populations. There was no indication of reproductive isolation and therefore of different biological species. The assumption that different male calling songs necessarily indicate the presence of different biological species is not confirmed in this example. 相似文献
83.
Wingfield BD; Grant WS; Wolfaardt JF; Wingfield MJ 《Molecular biology and evolution》1994,11(3):376-383
The genus Ceratocystis sensu stricto includes important fungal pathogens of
woody and herbaceous plants. This genus is distinguished from species in
Ceratocystis sensu lato by the presence of Chalara anamorphs. Ascospore
shape has been used extensively in delineating Ceratocystis taxa, which
show a large variety of ascospore shapes. Sequence analysis of one region
of he 18S ribosomal RNA subunit and two regions of the 28S ribosomal RNA
subunit showed that there was a majority of multiple substitutions at
nucleotide sites and that there was a low transition/transversion ratio, T
= 0.72. Both of these results suggest that these are well established, old
species. Ascospore morphology, for the most part, was not congruent with
the molecular phylogeny, and the use of morphological characters may be
misleading in the taxonomy of these species.
相似文献
84.
Membrane compartmentalized ATP and its preferential use by the Na, K-ATPase of human red cell ghosts
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This paper describes work which begins to define the molecular organization in the region of the membrane that comprises the functional domain of the Na:K pump. The membrane-bound phosphoglycerate kinase (PGK) and Na, K-ATPase appear to be directly linked via a compartmentalized form of ATP. Evidence for the membrane pool of ATP is based on the labeling characteristics of the phosphoproteins by [γ-(32)P]ATP of ghosts incubated under various conditions. Preincubation of ghosts in the presence of ATP at 37 degrees C, but not at 0 degrees C, completely obscures the formation of the Na-phosphoprotein in ghosts washed and subsequently incubated in the presence of [gamma-(32)P]ATP. In contrast to the Na component, the Mg component of phosphorylation is only slightly altered by preincubation with ATP. ATPase activity measured as (32)P(i) liberated during the subsequent incubation at 0 degrees C, reflects completely the differential effects of preincubation with ATP on (32)P incorporation into phosphoprotein. ATP placed within the pool by preincubation can be removed by operating the Na, K-ATPase or the PGK reaction in the reverse direction by use of exogenous substrates. Alternatively, the membrane pool of ATP can be formed also from exogenous substrates by running the PGK reaction in the forward direction. These results, while providing direct support for a membrane compartment of ATP, also indicate the location of this compartment in relation to the PGK and the Na, K-ATPase. In addition, these results also imply that the Mg and Na components are different enzymatic entities since substrate ATP can be derived from separate sources. 相似文献
85.
SUMMARY. The macro-invertebrate fauna and substrate were studied in a riffle and pool from a regulated (Elan) and an unregulated (Wye) river in summer. There were some differences in the substrate particle size distribution of the two rivers and between the riffle and the pool on the Wye. There was more detritus in pools than in riffles in both rivers and generally more in the Elan than the Wye. Deposits on the bed of the Elan were rich in iron and manganese.
On the Wye. there was a greater density of invertebrates in the riffle than in the pool, but species richness was similar. Most species showed some preferences for either the riffle or the pool. The riffle contained a substantial number of Ephemeroptera, Trichoptera, Plecoptera and Simuliidae (52%) whilst the pool was dominated by chironomids (71%). Compared with the Wye, total invertebrate density and species richness were reduced in the Elan. Some species characteristic of riffles were reduced or absent on the Elan. Invertebrate density on the Elan was similar in the riffle and pool; species richness was greater in the riffle. The distribution and abundance of invertebrates is discussed in relation to such environmental factors as water velocity through the substrate and dissolved oxygen supply in interstitial habitats. 相似文献
On the Wye. there was a greater density of invertebrates in the riffle than in the pool, but species richness was similar. Most species showed some preferences for either the riffle or the pool. The riffle contained a substantial number of Ephemeroptera, Trichoptera, Plecoptera and Simuliidae (52%) whilst the pool was dominated by chironomids (71%). Compared with the Wye, total invertebrate density and species richness were reduced in the Elan. Some species characteristic of riffles were reduced or absent on the Elan. Invertebrate density on the Elan was similar in the riffle and pool; species richness was greater in the riffle. The distribution and abundance of invertebrates is discussed in relation to such environmental factors as water velocity through the substrate and dissolved oxygen supply in interstitial habitats. 相似文献
86.
Pascopyrum smithii (C3) andBouteloua gracilis (C4) are importantforage grasses native to the Colorado shortgrass steppe. Thisstudy investigated photosynthetic responses of these grassesto long-term CO2enrichment and temperature in relation to leafnonstructural carbohydrate (TNC) and [N]. Glasshouse-grown seedlingswere transferred to growth chambers and grown for 49 d at twoCO2concentrations (380 and 750 µmol mol-1) at 20 and 35°C, and two additional temperatures (25 and 30 °C) at750 µmol mol-1CO2. Leaf CO2exchange rate (CER) was measuredat a plant's respective growth temperature and at two CO2concentrationsof approx. 380 and 700 µmol mol-1. Long-term CO2enrichmentstimulated CER in both species, although the response was greaterin the C3,P. smithii . Doubling the [CO2] from 380 to 750 µmolmol-1stimulated CER ofP. smithii slightly more in plants grownand measured at 30 °C compared to plants grown at 20, 25or 35 °C. CO2-enriched plants sometimes exhibited lowerCER when compared to ambient-grown controls measured at thesame [CO2], indicating photosynthetic acclimation to CO2growthregime. InP. smithii , such reductions in CER were associatedwith increases in TNC and specific leaf mass, reductions inleaf [N] and, in one instance, a reduction in leaf conductancecompared to controls. InB. gracilis , photosynthetic acclimationwas observed more often, but significant changes in leaf metabolitelevels from growth at different [CO2] were generally less evident.Temperatures considered optimal for growth (C3: 20 °C; C4:35 °C) sometimes led to CO2-induced accumulations of TNCin both species, with starch accumulating in the leaves of bothspecies, and fructans accumulating only inP. smithii. Photosynthesisof both species is likely to be enhanced in future CO2-enrichedand warmer environments, although responses will sometimes beattenuated by acclimation. Acclimation; blue grama (Bouteloua gracilis (H.B.K.) Lag ex Steud.); leaf nitrogen concentration; nonstructural carbohydrates; photosynthesis; western wheatgrass (Pascopyrum smithii (Rydb.) Love) 相似文献
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