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81.
Droba M Droba B Błedniak D 《Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology》2005,142(4):391-397
Activities of seven acid glycosidases: β-N-acetylhexosaminidase (β-HEX), α- and β-galactosidase (α- and β-GAL), α- and β-mannosidase (α- and β-MAN), α-glucosidase and α-fucosidase in magnum region of hen (Gallus gallus domesticus) oviduct, and four acid glycosidases: β-HEX, β-GAL, α- and β-MAN in egg albumen, were investigated. β-HEX from magnum and egg albumen hydrolysed 4-methylumbelliferyl-β-N-acetylhexosamine-6-sulphate (4-MeUmbGlcNAc-6-SO4) like mammalian β-HEX form A. Multiple forms of magnum and egg albumen β-HEX, β-GAL, α- and β-MAN were separated by strong anion exchange chromatography and chromatofocusing method. Chromatofocusing of the magnum resulted in the appearance of multiple forms for β-HEX with pI of 6.18, 5.43, 5.55, 5.34, 5.27 and 5.16, for β-GAL with pI of 4.98, 4.84, 4.77, 4.64 and 4.68–4.63, for α-MAN with pI of ≥ 7.4, 6.75, 6.62 and 6.26, and for β-MAN two forms with pI of 6.37 and 5.77. Chromatofocusing of egg albumen yields multiple forms for β-HEX with pI of 6.24, 6.08, 5.55 and 5.35, for β-GAL two forms with pI of 5.10 and 4.86–4.80 for α-MAN multiple forms with pI of ≥ 7.4, 6.80, 6.60 and 6.30, and for β-MAN forms with pI of 6.30 and 5.77. In conclusion, this study was the first to show β-HEX activity against 4-MeUmbGlcNAc-6-SO4 in the magnum and albumen of bird eggs, corresponding to β-HEX A activity in mammals. Main multiple forms of β-HEX, β-GAL, α- and β-MAN occurring in the magnum were revealed in the egg albumen. Comparison with a cock of the same breed showed that hen egg magnum and albumen has the same multiple forms of the enzymes that are found in the epididymides and seminal plasma of the cock. 相似文献
82.
We emphasize the necessity of a complex approach to evaluating vegetation change at various levels of abstraction. The analytical
steps include comparisons at the data, derived variable, distance, ordination and classification levels. A variety of data
randomization methods incorporated in testing the significance of changes in raw data are introduced and compared. It is shown
that these are true alternatives to Procrustean comparisons, which offer an apparently unfortunate choice in the presence/absence
case. We propose to evaluate nearest neighbor relationships among quadrats in a new method, called adjacency analysis, to
detect temporal trends that may remain unrevealed, should our attention be paid to full distance structures only. As an illustration,
compositional and structural changes in the rock grassland vegetation of the Sas-hegy Nature Reserve (Budapest, Hungary),
intensively sampled by quadrats in 1977 and 2000, are evaluated. Permutation tests show that differences between the 2 years
are much smaller than expected by chance alone. Such an overall stability in community structure, however, does not mean that
minor aspects of vegetation pattern are invariant over the years. Changes in life form and seed mass spectra are explained
by the fluctuation of hemicryptophytes and the slight but detectable expansion of annuals and woody species. Classification
is slightly rearranged in time, with clearly detectable within-cluster changes, also depicted in ordination scattergrams. 相似文献
83.
This review highlights the generation of various types of short forms of membrane hormonal receptors and the mode of regulation of their tissue-specific patterns. The short forms of membrane receptors are classified on the basis of localization of missing functional fragments. The review provides examples of tissues for which expression of short forms may serve as a marker of changes of ontogenetic stage, physiological state, or the development of pathological process. The short forms of receptors are shown to participate in determining tissue-specificity and efficacy of hormonal signal transduction, as well as in transport of hormones within cell, through physiological barriers, and in blood circulation. Peculiarities of signal transduction pathways for short receptor forms and potential physiological significance of these forms are analyzed. It is concluded that the ratio of long and short receptor forms may serve as a key marker of dynamic changes of differentiation stage and alterations of metabolic and proliferative activity of tissues under normal and pathologic conditions, and thus to be an important indicator of therapeutic effect for many pathological processes. 相似文献
84.
The focal adhesion target (FAT) domain of focal adhesion kinase has a four-helix bundle structure. Based on a hydrogen exchange-constrained computer simulation study and some indirect experimental results, it has been suggested that a partially unfolded state of the FAT domain with the N-terminal helix unfolded plays an important role in its biological function. Here, using a native-state hydrogen exchange method, we directly detected an intermediate with the N-terminal helix unfolded in a mutant (Y925E) of the FAT domain. In addition, kinetic folding studies on the FAT domain suggest that this intermediate exists on the native side of the rate-limiting transition state for folding. These results provide more direct evidence of the existence of the proposed intermediate and help to understand the folding mechanism of small single domain proteins. 相似文献
85.
Reeve JR Rosenquist GL Keire DA Chew P Nicholas HB Davis MT Lee TD Shively JE Backus RC 《Biochemical and biophysical research communications》2006,348(3):819-825
Evidence suggests that amino terminal extensions of CCK-8 affect the carboxyl terminal bioactive region of CCK. Cat CCK-58 was purified by low pressure reverse phase and ion-exchange chromatography steps and several reverse phase HPLC steps. The purified peptide and its tryptic fragments were characterized by mass spectral analysis and microsequence analysis. The structure of cat CCK-58 is: AVQKVDGEPRAHLGALLARYIQQARKAPSGRMSVIKNLQSLDPSHRISDRDY(SO3) MGWMDF-amide. Cat and dog CCK-58 are identical except for position 40 which is serine in cat and asparagine in dog. Radioimmunoassay detected cat CCK-58 about 1/10th as well as dog CCK-58, indicating a marked effect on C-terminal immunoreactivity. Cat CCK-58 with a serine at position 40, the same residue found in pig, mouse, cow and rabbit CCK-58, can be used as a unique bioprobe for defining how amino terminal amino acids influence the structure and bioactivity of the carboxyl terminal region of CCK. 相似文献
86.
CRAIG A. FAULHABER NOVA J. SILVY ROEL R. LOPEZ DAVID H. LAFEVER PHILIP A. FRANK MARKUS J. PETERSON 《The Journal of wildlife management》2008,72(5):1161-1167
Abstract: We used radiotelemetry to locate daytime forms of endangered Lower Keys marsh rabbits (LKMRs; Sylvilagus palustris hefneri) throughout their range so we could determine habitat characteristics of diurnal cover. We typically found forms (n = 1,298) of 36 rabbits in brackish wetlands in patches of saltmarsh or buttonwoods. In freshwater wetlands, forms (n = 54) were located most often in patches of freshwater hardwoods embedded in or adjacent to freshwater marshes. Forms (n = 942) in brackish wetlands were characterized by thick groundcover (>75%), whereas those (n = 42) in freshwater wetlands had both thick groundcover and canopy vegetation. The mean minimum convex polygon around forms of 15 rabbits was 1.4 ha (SD = 1.7), with smaller ranges characterized by thick bunchgrasses or clump-forming sedges. To increase the amount of annual space usable by LKMRs, managers should provide more saltmarsh habitat interspersed with buttonwoods and enhance ground cover in existing habitat. 相似文献
87.
Marco Schmidt Holger Kreft Adjima Thiombiano Georg Zizka 《Diversity & distributions》2005,11(6):509-516
A map of plant species diversity in Burkina Faso is presented based on field observations and specimen data from the Ouagadougou University Herbarium (OUA) and the Herbarium Senckenbergianum (FR). A map of collecting intensity and field observations illustrates centres of botanical research activities in Burkina Faso. To overcome problems associated with biased sampling intensity, distributions of species have been modelled and extrapolated to maps of vascular plant diversity, life forms and diversity of four selected families (Poaceae, Cyperaceae, Dioscoreaceae and Rubiaceae). The area of most intensive collection and observation is around Gorom‐Gorom and Fada N’Gourma. Modelled diversity generally increases towards the south, as does the proportion of phanerophytes, lianas and hemicryptophytes, while the opposite trend is observed for therophytes. Poaceae diversity is highly correlated with total vascular plant diversity, making the family especially suitable as an indicator for overall plant diversity. Cyperaceae are rather evenly distributed throughout the country, Dioscoreaceae are restricted to the Sudanian Zone. Rubiaceae have their highest diversities in the very south. Our approach can be transferred to areas with a similar database, certainly to other areas within West Africa. Future research should focus on distribution data for rare species, enabling our approach to evaluate the West African system of protected areas. 相似文献
88.
Ecological Strategy of Bacteria: Specific Nature of the Problem 总被引:2,自引:0,他引:2
E. L. Golovlev 《Microbiology》2001,70(4):379-383
An attempt is made to sum up the results of the many years of using the conception of ecological strategy in bacterial ecology. Taking into account the specificities of microorganisms and their natural selection and the coevolution of microorganisms within evolving microbial communities, an inference is derived that the ecological strategy of most bacteria is the sum of a number of particular canonical strategies, some of which are common to higher organisms. It is proposed to call these particular strategies ecological tactics. The author considers this review to be a basis for a discussion. 相似文献
89.
Prietzel Jörg Weick Corry Korintenberg Julia Seybold Gabriele Thumerer Thomas Treml Bernd 《Plant and Soil》2001,230(2):287-305
The effect of repeated (NH4)2SO4 applications (3 × 700 kg ha–1 in 1988, 1991, and 1994, respectively) on S pools in soil, soil microbial biomass, and ground vegetation was studied at two Norway spruce (Picea abies L. [Karst.]) sites in the Black Forest/Germany. In both eco-systems, most of the total S pool was located in the soil. The soil also was the predominant compartment for retention of applied SO4
2--S. The fractions of organic and inorganic S forms in the initial soil S content, and the retention of experimentally applied S was different for both sites. In the podzol Schluchsee, organic S accounted for 92% of total S. In the cambisol Villingen, the S pool consisted of 33% organic S and 67% inorganic S. The retention of applied S in various compartments of both ecosystems reflected these proportions. Only minor amounts of fertilized S (<1%) was retained in the spruce trees, ground vegetation, and soil microbial biomass. However, between 51% (Villingen) and 72% (Schluchsee) of the applied S was retained in the soil. In the Schluchsee podzol, 75% of retained fertilizer S was accumulated as ester sulfate, whereas SO4
2-adsorption and precipitation of Al hydroxy sulfates were restricted by dissolved organic matter in the soil solution. In the Villingen cambisol, SO4
2- adsorption was the dominant process of S retention, although 20% of the fertilized S again was retained as ester sulfate. The significant relevance of organic S forms in the retention of fertilizer S in both soils emphasizes the need for models which include the formation and re-mineralization of organic S compounds, especially of ester sulfates, for correctly simulating and predicting the retention and remobilization of S in acid forest soils subject to changing atmospheric N and S deposition. 相似文献
90.