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1

Digitale Medien

A sulphated glycopeptide in human supragingival calculus extracts (1977)

Embery, G.

Springer

Calcified tissue international 23 (1977), S. 13-17

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ISSN: 1432-0827

Schlagwort(e): Dental calculus ; Glycopeptide ; Chemistry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary A method is described for the isolation and purification of a sulphated glycopeptide from human supragingival calculus. The compound was isolated after using EDTA treatment, 2 M CaCl2 extraction, proteolytic digestion, ethanol precipitation, and finally purified by DEAE cellulose chromatography. It migrated as a single component on cellulose acetate electrophoresis, and chemical and infrared spectral analysis showed the presence of covalently attached sulphate groups. The sulphated glycopeptide was distinguished from being a sulphated glycosaminoglycan.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02012761

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2

Digitale Medien

Analysis of otolith chemistry in Nassau grouper (Epinephelus striatus) from the Bahamas and Belize using solution-based ICP-MS (1999)

Patterson, H. M. ; Thorrold, S. R. ; Shenker, J.M.

Springer

Coral reefs 18 (1999), S. 171-178

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ISSN: 1432-0975

Schlagwort(e): Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Geologie und Paläontologie

Notizen: Abstract We examined the utility of otolith minor and trace element chemistry, assayed with inductively coupled plasma mass spectrometry (ICP-MS), as a means of delineating population structure in the Nassau grouper (Epinephelus striatus). We characterized the elemental composition of otoliths collected in 1993 from three locations in Exuma Sound, Bahamas and from Glover Reef, Belize in 1995. A single location in Exuma Sound was sampled in 1994 to test temporal variability in otolith composition. Five elements (Ca, Zn, Sr, Ba and Pb) were routinely detected, at levels significantly above background, by solution-based ICP-MS. Results from analysis of variance of elemental data, expressed as a ratio to Ca, indicated that there were no significant differences among the Exuma locations for any element, but significant variability was found between Glover Reef and the pooled Exuma localities for Zn/Ca, Sr/Ca and Ba/Ca ratios. Significant inter-annual differences at one Exuma Sound location was restricted to Ba/Ca ratios. Discriminant function analysis correctly classified 86% and 95% of the Belize and pooled Exuma sites, respectively. Otoliths from Belize were characterized by low Zn/Ca and high Ba/Ca and Pb/Ca ratios compared to otoliths from fish collected in Exuma Sound. Although differences in Ba levels may be related to upwelling at Glover Reef, more data are needed to definitely link otolith composition with regional differences in water chemistry.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s003380050176

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3

Digitale Medien

Phylogenetic position of Dictyostelium inferred from multiple protein data sets (1995)

Kuma, Kei-ichi ; Nikoh, Naruo ; Iwabe, Naoyuki ; [weitere]

Springer

Journal of molecular evolution 41 (1995), S. 238-246

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ISSN: 1432-1432

Schlagwort(e): Cellular slime molds ; Animals ; Fungi ; Plantae ; Maximum-likelihood method ; Evolution

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract The phylogenetic position of Dictyostelium inferred from 18S rRNA data contradicts that from protein data. Protein trees always show the close affinity of Dictyostelium with animals, fungi, and plants, whereas in 18S rRNA trees the branching of Dictyostelium is placed at a position before the massive radiation of protist groups including the divergence of the three kingdoms. To settle this controversial issue and to determine the correct position of Dictyostelium, we inferred the phylogenetic relationship among Dictyostelium and the three kingdoms Animalia, Fungi, and Plantae by a maximum-likelihood method using 19 different protein data sets. It was shown at the significance level of 1 SE that the branching of Dictyostelium antedates the divergence of Animalia and Fungi, and Plantae is an outgroup of the Animalia-Fungi-Dictyostelium clade.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00170678

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4

Digitale Medien

Evolutionary relationships of eukaryotic kingdoms (1996)

Kumar, Sudhir ; Rzhetsky, Andrey

Springer

Journal of molecular evolution 42 (1996), S. 183-193

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ISSN: 1432-1432

Schlagwort(e): Small-subunit ribosomal RNA ; Phylogeny ; Animals ; Fungi ; Plants ; Alveolates ; Heterokonts ; Stramenopiles

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract The evolutionary relationships of four eukaryotic kingdoms—Animalia, Plantae, Fungi, and Protista—remain unclear. In particular, statistical support for the closeness of animals to fungi rather than to plants is lacking, and a preferred branching order of these and other eukaryotic lineages is still controversial even though molecular sequences from diverse eukaryotic taxa have been analyzed. We report a statistical analysis of 214 sequences of nuclear small-subunit ribosomal RNA (srRNA) gene undertaken to clarify these evolutionary relationships. We have considered the variability of substitution rates and the nonindependence of nucleotide substitution across sites in the srRNA gene in testing alternative hypotheses regarding the branching patterns of eukaryote phylogeny. We find that the rates of evolution among sites in the srRNA sequences vary substantially and are approximately gamma distributed with size and shape parameter equal to 0.76. Our results suggest that (1) the animals and true fungi are indeed closer to each other than to any other “crown” group in the eukaryote tree, (2) red algae are the closest relatives of animals, true fungi, and green plants, and (3) the heterokonts and alveolates probably evolved prior to the divergence of red algae and animal-fungus-green-plant lineages. Furthermore, our analyses indicate that the branching order of the eukaryotic lineages that diverged prior to the evolution of alveolates may be generally difficult to resolve with the srRNA sequence data.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02198844

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5

Digitale Medien

Chemistry of high mountain lakes in siliceous chatchments of the Central Eastern Alps (1989)

Psenner, Roland

Springer

Aquatic sciences 51 (1989), S. 108-128

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ISSN: 1420-9055

Schlagwort(e): Chemistry ; mountain lakes ; silica ; acidity ; sediment

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Alpine lakes in siliceous catchments of Tyrol and Carinthia (Austria) show signs of acidification. About 9% of the studied lakes have no alkalinity, more than 20% are below pH 6. About two thirds of all lakes have acid neutralizing capacities below 100 μeq 1−1. In spite of moderate precipitation acidity, some lakes show considerable concentrations of dissolved reactive aluminum during or shortly after snowmelt. High altitude lakes of the Alps are definitely more acidic than high mountain lakes in remote areas. Large differences in water and soil chemistry of nearby situated lakes were attributed to heterogeneities of bedrock geology. Paleolimnological investigations on former pH values of five lakes, based on diatom assemblages in the sediment, showed different developments: recent and past acidification, stable conditions, and alkalinization.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00879298

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6

Digitale Medien

Proteins of the periodontium (1977)

Birkedal-Hansen, Henning ; Butler, William T. ; Taylor, Robert E.

Springer

Calcified tissue international 23 (1977), S. 39-44

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ISSN: 1432-0827

Schlagwort(e): Dental cementum ; Collagen ; Protein ; Chemistry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary Cyanogen bromide (CNBr) peptides were prepared of the insoluble collagen of bovine dental cementum. Following chromatographic separation, the peptides were identified by their amino-acid composition. Type I collagen ([α1(I)]2α2) accounted for more than 90% of the organic matrix, while Type III collagen ([α1(III)]3) was present at a level of approximately 5%. Amino-acid analyses revealed that the CNBr peptides from α1(I) and α2 chains of cementum closely resembled the corresponding peptides from calf skin. The only systematic difference was a higher level of hydroxylation of prolyl and lysyl residues of the cementum peptides.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02012764

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7

Digitale Medien

Calcium deficiency, pregnancy, and lactation in rats (1977)

Rasmussen, P.

Springer

Calcified tissue international 23 (1977), S. 87-94

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ISSN: 1432-0827

Schlagwort(e): Calcium ; Osteoporosis ; Lactation ; Chemistry

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin , Physik

Notizen: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02012771

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8

Digitale Medien

Ultrastructural characterization by ruthenium red of the surface of the fat globule membrane of human and rat milk with data on carbohydrates of fractions of rat milk (1975)

Monis, Benito ; Rovasio, Roberto A. ; Valentich, Mirta A.

Springer

Cell & tissue research 157 (1975), S. 17-24

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ISSN: 1432-0878

Schlagwort(e): Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary The fat globules of the cream fractions of human and rat milk were stained with ruthenium red. Under the electron microscope, discrete granules and an amorphous coat of lesser density are seen at the surface of the milk fat globules. Since ruthenium red binds anionic groups selectively, it is probable that the granules containe the greatest concentration of these groups. The cream fraction of rat milk contains hexoses, hexosamines, methylpentoses and sialic acid. Methylpentoses and hexosamines are significantly enriched in the cream fraction. It is concluded that the finding of a surface coat in milk fat globules is in keeping with the Bargmann-Knoop model and suggests a distinct mechanism for carrying certain complex carbohydrates in milk. The role of the negative charges at the outer surface of the membrane coat in maintaining fat globules in suspension and in binding certain cations such as calcium is suggested.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00223228

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9

Digitale Medien

The ultrastructure, catecholamine, and prolactin contents of the rostral pars distalis of the fish Mugil platanus after reserpine or 6-hydroxydopamine administration (1975)

Zambrano, David

Springer

Cell & tissue research 162 (1975), S. 551-563

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ISSN: 1432-0878

Schlagwort(e): Hypophysis ; Rostral pars distalis ; Mugil platanus ; Animals ; Prolactin hormone secretion

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary The rostral pars distalis (RPD) of the teleost Mugil platanus from animals pretreated with reserpine or 6-hydroxydopamine (6-HODA) were assayed for dopamine (DA) or noradrenaline (NA) or for prolactin hormone. Such determinations were coupled with electron microscopy. It was found that reserpine and 6-HODA produced a significant decrease in the content of DA, NA, and prolactin. Electron microscope studies revealed that prolactin cells became activated as judged by ultrastructural criteria. After 6-HODA treatment type “B” neurosecretory fibers entering the RPD became selectively destroyed. These observations lead us to suggest that prolactin secretion is under inhibitory control by type “B” neurosecretory fibers of adrenergic nature.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00209354

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10

Digitale Medien

Calcium phosphates in pharmaceutical tableting (1993)

Schmidt, P. C. ; Herzog, R.

Springer

Pharmacy world & science 15 (1993), S. 105-115

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ISSN: 1573-739X

Schlagwort(e): Calcium phosphates ; Drug compounding ; Excipients ; Particle size ; Physics ; Powders ; Tablets

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Notizen: Abstract Ten commercially available calcium phosphates used for direct tableting were evaluated. The particle size distributions, powder properties, Sorption isotherms and pH values of aqueous slurries were compared. All samples showed good or at least sufficient flowability. Scanning electron micrographs illustrated the different kinds of manufacturing and gave hints on their expectable behaviour under compaction pressure. The sorption isotherms of identical chemical substances, which had been manufactured by different methods, differed strongly. This can be related to their specific surface areas. Most of the hydroxylapatites have large surface areas and can absorb up to more than 15% water at 93% relative humidity. Dibasic calcium phosphate dihydrate was non-hygroscopic and absorbed less than 1% water. With the exception of monobasic calcium phosphate monohydrate all calcium phosphates behaved quite neutral in water. Monobasic calcium phosphate monohydrate can be regarded as a solid acid. Although the calcium phosphates are usually stable substances, the role of crystal water in the case of dibasic calcium phosphate dihydrate and monobasic calcium phosphate monohydrate is problematic due to possible interactions with active ingredients.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02113938

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