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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 10 (1972), S. 82-90 
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Kinetics ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé La cinétique de la formation et de la transformation des précipités de phosphate de calcium, obtenus en mélangeant de volumes égaux de solutions à 6×10−3 M de calcium total et/ou phosphate total est étudiée à 25°C. Les solutions de phosphate sont préajustées à un pH de 7.4. Les changements de pH et de turbidité des solutions sont suivis simultanément en fonction du temps. Les précipités sont isolés à des intervalles de temps variables et caractérisés par diverses méthodes physico-chimiques. Initialement un précipité avec un rapport molaire Ca/P de 1.5, amorphe aux rayons X et en diffraction électronique, est formé. Le spectre IR indique la présence de PO 4 3− et de HPO 4 2− . Après une période métastable, on observe la précipitation d'un matériel cristallin dans ou sur la phase amorphe. Vingt quatre heures après préparation de l'échantillon les précipités présentent surtout les caractères du phosphate octocalcique.
    Abstract: Zusammenfassung Die Kinetik der Bildung und Transformation von Calciumphosphat-Niederschlägen wurde bei 25°C untersucht. Es wurden dazu gleiche Volumen von Lösungen gemischt, bei einer Konzentration von 6×10−3M totales Calcium und/oder totales Phosphat. Die Phosphatlösungen wurden zuerst auf pH 7,4 eingestellt. Veränderungen des pH und Trübung der Lösungen wurden gleichzeitig als eine Funktion der Zeit aufgezeichnet. Niederschläge wurden in verschiedenen Zeitintervallen isoliert und mit verschiedenen physiko-chemischen Methoden charakterisiert. Am Anfang wurde ein Niederschlag mit einem molaren Ca/P-Verhältnis von 1,5, im Röntgenbild und in der Elektronendiffraktion amorph, gebildet. Infrarotspektren deuteten die Anwesenheit von PO 4 3− - und HPO 4 2− -Ionen an. Nach einer metastabilen Periode erfolgte ein Niederschlag aus kristallinem Material innerhalb oder auf der amorphen Substanz. 24 Std nach der Herstellung der Proben zeigten die Niederschläge in der Hauptsache die Charakteristiken von Octocalciumphosphat.
    Notes: Abstract The kinetics of the formation and transformation of calcium phosphate precipitates obtained by mixing equal volumes of solutions, 6×10−3 M in total calcium and/or total phosphate was investigated at 25°. The phosphate solutions were preadjusted to pH 7.4. Changes of the pH and turbidity of the solutions were followed simultaneously as a function of time. Precipitates were isolated at various time intervals and characterized by different physicochemical methods. Initially a precipitate with a molar Ca/P ratio of 1.5, amorphous to X-ray and electron diffraction was formed. IR spectra indicated the presence of PO 4 3− and HPO 4 2− ions. After a period of metastability, precipitation of a crystalline material within or upon the amorphous matter occurred. Twenty four hours after sample preparation the precipitates showed mainly the characteristics of octacalcium phosphate.
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  • 2
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    Calcified tissue international 16 (1974), S. 145-152 
    ISSN: 1432-0827
    Keywords: EHDP ; Bone ; Chemistry ; Serum ; Rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of disodium ethane-1-hydroxy-1,1-diphosphonate (EHDP) on bone and serum chemistry were investigated in adult rabbits. EHDP was administered by subcutaneous injection at doses of 0.25, 2.5 and 10 mg/kg body weight/day for of 28 days. Blood samples were obtained weekly from each rabbit and serum levels of total calcium, ionized calcium, inorganic phosphate and alkaline phosphatase were determined. At the end of the treatment period all rabbits were sacrificed and the tibiae removed for chemical analysis and histological evaluation. The effect of EHDP administration on serum chemistry was both dose- and time-related. The highest of the three doses, 10 mg/kg/day, resulted in a time-related decrease in total serum calcium. This dose also caused a rapid but transient reduction in serum ionized calcium. The effect of EHDP on serum inorganic phosphate was biphasic. Administration of 2.5 mg/kg/day resulted in a time-related elevation in this parameter, whereas the 10 mg/kg/day dose resulted in a time-related hypophosphatemic response. There were no significant drug-related changes in tibial fat-free dry weight, ash weight, total calcium or total phosphorus values. However, administration of 2.5 and 10 mg/kg/day EHDP resulted in increased osteoid tissue as measured histologically. These results are compared with data from other EHDP studies, and discussed in relation to the maturity and growth-state of the experimental animals.
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  • 3
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    Calcified tissue international 23 (1977), S. 13-17 
    ISSN: 1432-0827
    Keywords: Dental calculus ; Glycopeptide ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: 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.
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  • 4
    ISSN: 1432-0975
    Keywords: Key words Otolith ; Chemistry ; ICP-MS ; Stock discrimination ; Epinephelus striatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: 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.
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  • 5
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    Journal of molecular evolution 43 (1996), S. 399-404 
    ISSN: 1432-1432
    Keywords: Asarum ; Dioscorea ; Angiosperms ; Evolution ; Legumins ; Seed proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Analysis of legumin-encoding cDNAs fromDioscorea caucasica Lipsky (Dioscoreaceae) and fromAsarum europaeum L. (Aristolochiaceae) shows that there is an especially methionine-rich legumin subfamily present in the lower angiosperm clades including the Monocotyledoneae. It is characterized by a methionine content of 3–4 mol% which is roughly triple the methionine proportion of most other legumins. These “MetR” legumins, if present, still have to be detected in the higher angiosperms including the important seed crops. Evolutionary analysis suggests that the MetR legumins are the result of a gene duplication allowing the differentiation of legumin genes according to their sulfur content. The duplication event must have taken place before the split into mono- and dicotyledonous plants but probably after the separation of angiosperms and gymnosperms.
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  • 6
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    Journal of molecular evolution 15 (1980), S. 79-101 
    ISSN: 1432-1432
    Keywords: Molecules ; Interstellar ; Chemistry ; Isotopes ; Solar system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The study of interstellar molecules broadly includes two areas of interest. One area uses the unique ability of molecules to act as probes of the physical conditions in the cold, dense, visually opaque component of the interstellar medium. The physical properties of this and other components of the interstellar medium are summarized. The other area deals with the chemistry of interstellar molecules, recent aspects of which are emphasized in this review. Gas-phase chemistry, shock chemistry, and grain surface chemistry are discussed in the context of recent observations. No present observations suggest that surface reactions are relevant, but neither can they be ruled out. Ion-molecule reactions are clearly operative, at least for the simpler species. Chemical isotope fractionation is reviewed, andd it is concluded that the complexities of the chemistry allow no cosmological conclusions to be drawn from observations of deuterium in interstellar molecules, while the presence of13C in interstellar molecules permits an estimate of the12C/13C ratio which is consistent with the current concepts of the nucleosynthesis history of the Galaxy. Possible connections between interstellar molecules and the early molecular history of the solar system are discussed.
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  • 7
    ISSN: 1432-1432
    Keywords: Chloroplast 4.5S rRNA ; Cytosolic and chloroplast 5S rRNAs ; 5.8S rRNA ; 18S rRNA ; Nucleotide sequences ; Phylogenetic trees ; Angiosperms ; Gymnosperms ; Monocotyledons ; Dicotyledons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Complete or partial nucleotide sequences of five different rRNA species, coded by nuclear (18S, 5.8S, and 5S) or chloroplast genomes (5S, 4.5S) from a number of seed plants were determined. Based on the sequence data, the phylogenetic dendrograms were built by two methods, maximum parsimony and compatibility. The topologies of the trees for different rRNA species are not fully congruent, but they share some common features. It may be concluded that both gymnosperms and angiosperms are monophyletic groups. The data obtained suggest that the divergence of all the main groups of extant gymnosperms occurred after the branching off of the angiosperm lineage. As the time of divergence of at least some of these gymnosperm taxa is traceable back to the early Carboniferous, it may be concluded that the genealogical splitting of gymnosperm and angiosperm lineages occurred before this event, at least 360 million years ago, i.e., much earlier than the first angiosperm fossils were dated. Ancestral forms of angiosperms ought to be searched for among Progymnospermopsida. Genealogical relationships among gymnosperm taxa cannot be deduced unambiguously on the basis of rRNA data. The only inference may be that the taxon Gnetopsida is an artificial one, andGnetum andEphedra belong to quite different lineages of gymnosperms. As to the phylogenetic position of the two Angiospermae classes, extant monocotyledons seem to be a paraphyletic group located near the root of the angiosperm branch; it emerged at the earliest stages of angiosperm evolution. We may conclude that either monocotyledonous characters arose independently more than once in different groups of ancient Magnoliales or that monocotyledonous forms rather than dicotyledonous Magnoliales were the earliest angiosperms. Judging by the rRNA trees, Magnoliales are the most ancient group among dicotyledons. The most ancient lineage among monocotyledons leads to modern Liliaceae.
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  • 8
    ISSN: 1432-1432
    Keywords: CpG suppression ; GC content ; Angiosperms ; Isochores ; GC bias ; Mutational pressure ; Error-prone repair ; Transcriptionally coupled repair
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nuclear protein coding sequences from gymnosperms are currently scarce. We have determined 4 kb of nuclear protein coding sequences from gymnosperms and have collected and analyzed 〉60 kb of nuclear sequences from gymnosperms and nonspermatophytes in order to better understand processes influencing genome evolution in plants. We show that conifers possess both biased and nonbiased genes with respect to GC content, as found in monocots, suggesting that the common ancestor of conifers and monocots may have possessed both biased and nonbiased genes. The lack of biased genes in dicots is suggested to be a derived character for this lineage. We present a simple but speculative model of land-plant genome evolution which considers changes in GC bias and CpG frequency, respectively, as independent processes and which can account for several puzzling aspects of observed nucleotide frequencies in plant genes.
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  • 9
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    Pure and applied geophysics 118 (1980), S. 128-151 
    ISSN: 1420-9136
    Keywords: Galactic cosmic rays ; Solar proton events ; Particle precipitation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract An assessment is made of the relative contribution of certain classes of energetic particle precipitation to the chemical composition of the middle atmosphere with emphasis placed on the production of odd nitrogen and odd hydrogen species and their subsequent role in the catalytic removal of ozone. Galactic cosmic radiation is an important source of odd nitrogen in the lower stratosphere but since the peak energy deposition occurs below the region where catalytic removal of O3 is most effective, it is questionable whether this mechanism is important in the overall terrestrial ozone budget. The precipitation of energetic solar protons can periodically produce dramatic enhancement in upper stratospheric NO. The long residence time of NO in this region of the atmosphere, where catalytic interaction with O3 is also most effective, mandates that this mechanism be included in future modelling of the global distribution of O3. Throughout the mesosphere the precipitation of energetic electrons from the outer radiation belt (60°≲Λ≲70°) can sporadically act as a major local source of odd hydrogen and odd nitrogen leading to observable O3 depletion. Future satellite studies should be directed at simultaneously measuring the precipitation flux and the concomitant atmosphere modification, and these results should be employed to develop more sophisticated models of this important coupling.
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  • 10
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    Aquatic sciences 51 (1989), S. 108-128 
    ISSN: 1420-9055
    Keywords: Chemistry ; mountain lakes ; silica ; acidity ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
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  • 11
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    Accreditation and quality assurance 5 (2000), S. 409-413 
    ISSN: 1432-0517
    Keywords: Key words Metrology ; Comparisons ; Chemistry ; Standards
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  After stressing the importance in the modern world of accurate and reproducible measurements, the actions taken by the Bureau International des Poids et Mesures to set up, together with the regional metrology organizations, a series of key comparisons are described. They are the technical foundation of a mutual recognition of national measurement standards arrangement prepared in conjunction with the National Metrology Institutes (NMIs). This arrangement also includes the recognition of calibration and measurement certificates issued by these institutes. Then, the consequences of this arrangement for trade are described. The case of chemical analysis is illustrated by the application of the Kyoto protocol on the reduction of greenhouse gases. But the global workload to be taken up by the International Committee of Weights and Measures, its Consultative Committee for Amount of Substance and the NMIs is huge.
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  • 12
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    Calcified tissue international 14 (1974), S. 3-14 
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Mineral ; Phase ; Chemistry ; Synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des diagrammes de phase d'équilibre ont été déterminés pour le système CaO-P2O5-H2O en utilisant des techniques de synthèse hydrothermique au cours de variatio nsde température allant de 300–600° et 2 Kb H2O de pression. De l'hydroxyapatite bien cristallisé a été synthétisé et caractérisé. De faibles variations de paramètres de la maille cristalline, liées à la température de synthèse et composition globale du matériel initial, ont été déterminées. Des conditions chimiques précises sont nécessaires pour obtenir de l'apatite, en tant que seule phase solide en équilibre dans la solution. Les résultats de diagramme de phase d'équilibre sont comparés avec ceux obtenus dans des milieux synthétiques.
    Abstract: Zusammenfassung Es wurden Gleichgewichts-Phasendiagramme für das System CaO-P2O5-H2O bestimmt, indem hydrothermale Synthese-Techniken im Temperaturbereich von 300–600° und bei einem Druck von 2 Kb H2O verwendet wurden. Es wurde gut-kristallisiertes Hydroxyapatit erzeugt und charakterisiert. Es wurden geringe Unterschiede in den Parametern der Zelleinheiten festgestellt, welche von der angewandten Temperatur und der Zusammensetzung des Startmaterials abhingen. Es waren genaue chemische Bedingungen nötig, um Apatit als die einzige feste Phase im Gleichgewicht mit der Lösung zu erhalten. Die Resultate der Gleichgewichts-Phasendiagramme werden mit früheren Untersuchungen mit der Synthesetechnik verglichen.
    Notes: Abstract Equilibrium phase diagrams have been determined for the system CaO-P2O5-H2 using hydrothermal synthesis techniques in the temperature range 300–600° and 2 Kb H2O pressure. Well-crystallized hydroxyapatite has been produced and characterized. Small variations in unit cell parameters dependent on temperature of synthesis and bulk composition of the starting materials have been determined. Precise chemical conditions were required to obtain apatite as the only solid phase in equilibrium with solution. Equilibrium phase diagram results are compared with previous synthetic investigations.
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  • 13
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    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Keywords: Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Abstract: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notes: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
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  • 14
    ISSN: 1432-0827
    Keywords: Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Abstract: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notes: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
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  • 15
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    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Keywords: Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Abstract: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notes: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
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    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Keywords: Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Abstract: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notes: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
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    Calcified tissue international 10 (1972), S. 171-197 
    ISSN: 1432-0827
    Keywords: Amorphous ; Crystalline ; Calcium phosphate ; Chemistry ; Composition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des échantillons non lavés de phosphate de calcium amorphe (ACP) contiennent une fraction labile, non remplaçable, riche en phosphate acide avec un rapport Ca/P faible: cette fraction est perdue de façon irréversible au cours du lavage. De l'ACP frais, précipité entre pH 6.6–10.6, varie dans un rapport molaire Ca/P de 1.18 à 1.50 et dans un rapport HPO 4 2− /P total de 33.0% à 10.1%. A pH 7.40, de l'ACP frais a un rapport molaire Ca/P de 1.36±0.02 et contient 22.8 (±2.2)% HPO 4 2− . Les résultats obtenus avec du précipité non lavé ne peuvent s'expliquer par du Ca2+ emprisonné et de l'HPO 4 2− ou du Na+, Cl− et CO 3 2− exogènes. Les phosphates de calcium amorphes constituent une classe de sels ayant des caractères chimiques variables et des propriétés physiques identiques, comparables au verre. Le CaHPO4·xH2O non cristallin peut être un ACP, surtout au cours des phases précoces de formation. A des pH physiologiques, l'ACP se transforme en petits cristaux applatis contenant de fortes quantités de phosphate acide facilement remplaçable. Le fait de laver la couche de surface produit un changement chimique dans les nouveaux cristaux: des cristaux non lavés donnent des diagrammes de diffraction d'apatite peu cristallins, ainsi que des spectres infra-rouges peu nets, intermédiaires entre des apatites et du phosphate octocalcique. Des explications structurales sont proposées et les compositions minérales amorphe/cristalline de l'os et du cartilage sont recalculées.
    Abstract: Zusammenfassung Ungewaschene Proben von amorphem Calciumphosphat (ACP) enthalten eine unersetzliche labile Fraktion, welche reich an saurem Phosphat ist und ein niederes Ca/P-Verhältnis hat und welche während des Waschprozesses unwiderruflich verloren geht. Natives ACP, welches im pH-Bereich 6,6–10,6 ausgefällt wurde, variierte im molaren Ca/P-Verhältnis zwischen 1,18 und 1,50 und in HPO 4 2− /totales P zwischen 33,0 und 10,1%. Bei pH 7,40 hatte natives ACP ein molares Ca/P-Verhältnis von 1,36±0,02 und enthielt 22,8 (±2,2)% HPO 4 2− . Die Werte beim ungewaschenen Niederschlag rühren weder von aus dem Überstand aufgenommenem Ca2+ und HPO2−, noch von außen kommendem Na+, Cl− und CO 3 2− her. Die amorphen Calciumphosphate werden als eine Klasse von Salzen erkannt, welche veränderliche chemische, aber identische glasartige physicochemische Eigenschaften haben. Nicht kristallines CaHPO4·xH2O kann auch ein ACP sein, besonders in den frühen Bildungsstadien. Bei physiologischem pH verwandelt sich ACP in kleine plattenförmige Kristalle, welche große Mengen von leicht ersetzbarem saurem Phosphat enthalten. Das Waschen dieser Oberflächenschicht erzeugte chemische Veränderungen in den resultierenden Kristallen; ungewaschene Kristalle zeigten ein Diffraktionsmuster, das nur schwach demjenigen des kristallinen Aspatites glich, aber ein schlecht aufgelöstes Infrarotspektrum, welches zwischen Apatit und Octocalciumphosphat war. Es werden strukturelle Erklärungen für alle diese Phenomena diskutiert, und revidierte amorph/kristalline Mineralzusammensetzungen von Knochen und Knorpel wurden neu berechnet.
    Notes: Abstract Unwashed samples of amorphous calcium phosphate (ACP) contain an irreplaceable labile fraction, rich in acid phosphate and low in Ca/P ratio, which is irreversibly lost during the washing process. Native ACP precipitated in the pH range 6.6–10.6 varied in Ca/P molar ratio from 1.18 to 1.50 and in HPO 4 2− /total P from 33.0% to 10.1%. At pH 7.40, native ACP had a Ca/P molar ratio of 1.36±0.02 and contained 22.8 (±2.2)% HPO 4 2− . Unwashed precipitate data could not be attributed to either trapped supernatant Ca2+ and HPO 4 2− or extraneous Na+, Cl−, and CO 3 2− . The amorphous calcium phosphates are recognized as a class of salts having variable chemical but identical glass-like, physicochemical properties. Non-crystalline CaHPO4·xH2O may also be an ACP, especially during early formative stages. At physiological pH, ACP transforms to small platy crystals containing large amounts of readily-replaceable acid phosphate. Washing this surface layer produced chemical alterations in the resultant crystals; unwashed crystals had poorly-crystalline apatitic diffraction patterns but exhibited poorly-resolved infrared spectra intermediate between apatite and octacalcium phosphate. Structural explanations for all these phenomena are discussed, and revised bone and cartilage amorphous/crystalline mineral compositions have been re-calculated.
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    Calcified tissue international 23 (1977), S. 39-44 
    ISSN: 1432-0827
    Keywords: Dental cementum ; Collagen ; Protein ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: 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.
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    Calcified tissue international 23 (1977), S. 87-94 
    ISSN: 1432-0827
    Keywords: Calcium ; Osteoporosis ; Lactation ; Chemistry
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    Topics: Biology , Medicine , Physics
    Notes: 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.
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    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Keywords: Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Abstract: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notes: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
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    Calcified tissue international 12 (1973), S. 125-136 
    ISSN: 1432-0827
    Keywords: Mineralization ; Molt ; Isopod ; Chemistry ; Light microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Au cours de la phase inhabituelle de mue d'un isopode d'eau courante,Lirceuts brachyrus, la moitié postérieure de l'exosquelette est éliminée 24 heures avant la moitié antérieure. A ce stade, une reminéralisation se développe dans la partie postérieure alors que la partie antérieure est dans un stade de pré-mue. Le pourcentage de différence en calcium dans les deux moitiés à mi-mue et mue complète est respectivement de 22% (p〈0.01) et 33% (p〈0.01), indiquant une complexation du calcium pendant la mue. La rapidité de la reminéralisation est illustrée par le fait que le contenu minéral total double dans la partie postérieure entre la mi-mue et la mue totale et dans la partie antérieure entre la fin de la mue et un jour après. Le carbonate de calcium, sous forme de calcite, a pu être identifié par diffraction électronique de coupes fines des téguments.
    Abstract: Zusammenfassung Während der ungewöhnlichen Häutungssequenz des Frischwasser-IsopodenLirceus brachyurus (Harger) wird die hintere Hälfte des äußeren Skeletts 24 Std vor der vorderen Hälfte abgestoßen. In der halbgehäuteten Phase erfolgt Remineralisation im hinteren Teil, während der vordere Teil in einem Vorhäutungszustand ist. Der prozentuale Unterschied des Calciums in den zwei Hälften bei Halb- und Vollhäutungszustand ist 22% (p〈0,01) bzw. 33% (p〈0,01), was andeutet, daß Calcium während der Häutung abgesondert wird. Die Geschwindigkeit der Remineralisation erhellt aus der Tatsache, daß sich der Gesamtmineralgehalt im hinteren Teil zwischen Halt- und Vollhäutung, in der vorderen Hälfte jedoch zwischen Endhäutung und einem Tag nach der Häutung verdoppelt. Calciumcarbonat in kristalliner Calcitform wurde mittels Elektronendiffraktion von dünnen Hautschnitten nachgewiesen.
    Notes: Abstract During the unusual molt sequence of the fresh-water isopod,Lirceus brachyrus (Harger), the posterior half of the exoskeleton is shed 24 hours before the anterior half. At the half-molt stage, occurs in the posterior part while the anterior portion is in a pre-molt condition. The percentage difference in calcium in the two halves at half-molt and full-molt is22 (p〈0.01) and33 (p〈0.01) respectively, an indication that calcium is sequestered during The rapidity of remineralization is illustrated by the fact that the total mineral content doubles in the posterior part between half and full molt and in the anterior half between the end of molt and one day after ecdysis. Calcium carbonate in the calcite cystalline form was demonstrated by electron diffraction of thin sections of the integument.
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    Calcified tissue international 13 (1973), S. 259-270 
    ISSN: 1432-0827
    Keywords: Fluorapatite ; Exchange ; Chemistry ; Crystallography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante: $$(Ca^2 )9.98(Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )0.02(PO_4^{3 - } )5.98(HCO_3^ - ,CO_3^{2 - } )0.02(F^ - )2$$ . L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante: $$(Ca)_5 (PO_4 )_3 OH solide + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F solide + (OH^ - )$$ , la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
    Abstract: Zusammenfassung Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht: $$(Ca^{2 + } )_{9,98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0,02} (PO_4^{3 - } )_{5,98} (HCO_3^ - ,CO_3^{2 - } )_{0,02} (F^ - )_2 $$ . Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion $$(Ca)_5 (PO_4 )_3 OH_{in fester Form} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{in fester Form} + (OH^ - )$$ wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
    Notes: Abstract A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to $$(Ca^{2 + } )_{9.98} (Sr^{2 + } ,Na^ + ,K^ + ,Mg^{2 + } )_{0.02} (PO_4^{3 - } )_{5.98} (HCO_3^ - ,CO_3^{2 - } )_{0.02} (F^ - )_2 $$ . The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction $$(Ca)_5 (PO_4 )_3 OH_{solid} + (F^ - ) \rightleftarrows (Ca)_5 (PO_4 )_3 F_{solid} + (OH^ - )$$ the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
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    ISSN: 1432-0827
    Keywords: Bacterial amphophile ; Purification ; Chemistry ; Resorption ; Ca influx ; Cyclic AMP
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    Notes: Summary The bone resorptive factor and amphipathic antigen (AcA) previously identified by us in preparations fromActinomyces viscosus have been partially purified, characterized chemically, and compared. They elute at the same location on chromatography with Ac 22. The fatty acid composition of AcA and the bone resorptive factor is the same. Some differences in carbohydrate composition are observed. TheActinomyces factor does not affect calcium influx or cyclic AMP in isolated bone cells. Therefore it is concluded that AcA stimulates resorption either by gaining entrance into bone cells or by way of a yet undetermined second messenger.
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    Sexual plant reproduction 5 (1992), S. 86-88 
    ISSN: 1432-2145
    Keywords: Sex chromosome markers ; Y-chromosome ; Angiosperms ; Silene latifolia ; Melandrium album
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In order to obtain markers for the Y chromosome ofSilene latifolia, we pooled equal weights of leaf tissue from 18 female siblings into one sample and repeated the process with 18 male siblings. Pooling was intended to provide a common genetic background for each sample, leaving the absence or presence of the Y chromosome as the primary difference between the two samples. DNA was extracted from each sample and subjected to polymerase chain reaction (PCR) amplification with arbitrary 10 bp primers. Four of 60 primers used gave an amplification with the male DNA not found among those from the female DNA. Each of these was subsequently shown to provide a reliable marker for the Y chromosome.
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    Astrophysics and space science 224 (1995), S. 81-84 
    ISSN: 1572-946X
    Keywords: Chemistry ; Depletions ; Shocks ; IRAS 05338-0624 ; NGC 1333 IRAS 4
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    Topics: Physics
    Notes: Abstract High resolution interferometer and single-dish observations of young, deeply embedded stellar systems reveal a complex chemistry in the circumstellar environments of low to intermediate mass stars. Depletions of gas-phase molecules, grain mantle evaporation, and shock interactions actively drive chemical processes in different regions around young stars. We present results for two systems, IRAS 05338-0624 and NGC 1333 IRAS 4, to illustrate the behavior found and to examine the physical processes at work.
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    Astrophysics and space science 216 (1994), S. 153-154 
    ISSN: 1572-946X
    Keywords: Chemistry ; Molecular Hydrogen ; Cloud Models
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    Topics: Physics
    Notes: Abstract Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.
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    Boundary layer meteorology 85 (1997), S. 197-222 
    ISSN: 1573-1472
    Keywords: Turbulence ; Chemistry ; Closure ; Convective boundary layer
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    Topics: Geosciences , Physics
    Notes: Abstract We study the interactions of chemistry and turbulent mixing of tracersin the convective boundary layer with a second-order closure model,including higher order chemistry terms. In order to limit the number of predictive equations we prescribe the profiles for ¯w¯Θ, ¯w¯θ ¯θ and the lengthscale l. However, for model validation we treat temperature and humidity asinert tracers, and compare the results with profiles observed during theAir Mass Transformation Experiment, and with similarity expressions for thesurface layer. We find good agreement of the mean profiles, but the (co-)variances are slightly underpredicted. Furthermore, the model usesdiagnostic equations expressing third moments of concentration in terms ofsecond moments and their vertical derivatives. They are compared withlarge-eddy model results, showing good agreement and, therefore, thesimplifications are justified. The model is applied to the transport of two gases subject to one bimolecular reaction. The importance of concentration correlations on themean transformation rate is studied. For two gases diffusing in oppositedirections we find for moderate and fast chemistry a 50% and90% decreased transformation rate due to the negatively correlatedconcentrations. These values are similar to large-eddy results of Schumannand Sykes et al. For two bottom-up tracers we find that the covariance ofboth reactive species is either positive or negative, increasing or reducingthe effective transformation rate depending on the Damköhler number (the ratio of the turbulent and the chemistry timescale). A significantdirect influence of chemistry on the flux divergence is found in bothcases. According to the model the effective transport to mid-levels of theboundary layer is increased when two reactive tracers diffuse in oppositedirections, and decreased in the case of two bottom-up tracers.
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    Plant cell reports 18 (1998), S. 143-147 
    ISSN: 1432-203X
    Keywords: Key wordsNicotiana tabacum ; Male germ unit ; Scanning electron microscopy ; Sperm isolation ; Angiosperms
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    Topics: Biology
    Notes: Abstract Sperm cells are released from pollen tubes of tobacco as linked cells, associated with the vegetative nucleus in an assemblage known as the male germ unit (MGU). Using light microscopy, the MGU assemblage appears to be ensheathed by cytoplasmic material of the pollen tube, which may stabilize their association. Following their release, the shape of the sperm cells and vegetative nucleus changes from an ellipsoidal to a more spheroidal morphology. When most of the cytoplasmic material is dispersed, a boundary remains around the two sperm cells. Using scanning electron microscopy, the cytoplasmic material surrounding the MGU appears filamentous, sometimes twisted and rope-like. Based on these observations, the function of the MGU of tobacco is discussed.
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    ISSN: 1432-2242
    Keywords: DNA fingerprinting ; Repetitive DNA ; Genotype identification ; Angiosperms
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    Notes: Summary Oligonucleotides hybridizing to simple repetitive DNA patterns are highly informative as probes for DNA fingerprinting in all investigated animal species, including man. Here we demonstrate the applicability of this technique in higher plants. The oligonucleotide probes (GTG)5 and (GATA)4 were used to investigate the differences in DNA fingerprint patterns of the following angiosperm species: Triticum aestivum, Secale cereale, Hordeum vulgare, Beta vulgaris, Petunia hybrida, Brassica oleracea, and Nicotiana tabacum. Two species, Hordeum vulgare as a monocot and Beta vulgaris as a dicot, were analyzed in more detail. Their genomes differ considerably in both amount and organization of the simple repetitive sequences (GATA)n, (GACA)n, (GTG)n, and (CT)n due to the evolutionary distance of these two species. Furthermore, several lines and cultivars of Beta vulgaris and Hordeum vulgare can clearly be distinguished on the basis of their highly polymorphic patterns of these repetitive sequences.
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  • 30
    ISSN: 1432-0878
    Keywords: Milk ; Fat globule membrane ; Carbohydrates ; Chemistry ; Ruthenium red ; Ultrastructure
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    Topics: Biology , Medicine
    Notes: 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.
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    Plant systematics and evolution 130 (1978), S. 203-207 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Caryophyllaceae ; Silene ; Chromosome numbers ; Flora of Greece ; Crete
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    Topics: Biology
    Notes: Abstract The chromosome numbers of several Greece species of the genusSilene L. from natural habitats are reported for the first time:S. sieberi, S. niederi, S. radicosa subsp.rechingeri, S. oligantha, S. skorpilii, S. schwarzenbergeri andS. fruticulosa. All species are diploid with 2n = 24 chromosomes, including 0, 2 or 4 SAT-chromosomes;S. niederi has B-chromosomes.
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  • 32
    ISSN: 1615-6110
    Keywords: Angiosperms ; Winteraceae ; Drimys s. str. ; D. brasiliensis (with subsp. and comb. nov.) ; D. roraimensis ; comb. nov. ; D. angustifolia ; Population variation ; eco-geographical differentiation ; epidermis ultrastructure ; Systematics and history of the S. American flora
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    Notes: Abstract Statistical analyses and scatter diagrams illustrate for the polymorphic E. and SE. BrazilianDrimys brasiliensis a clear correlation between morphological variation and eco-geographical differentiation. This is backed by data on the (ultra)structure of the lower leaf surface. A new infraspecific taxonomy is proposed, andD. roraimensis andD. angustifolia are recognized as distinct species of the Guyana Highlands and S. Brazil, respectively. The affinities between these and other taxa of the paleopolyploid genus, its evolution and its position within the family are discussed.
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    Plant systematics and evolution 134 (1980), S. 11-21 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Daucus ; Petroselinum ; Acer ; rRNA ; transcription ; precursors of less than 2.5 × 106 daltons ; processing
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    Topics: Biology
    Notes: Abstract Actively dividing cells from parsley (Petroselinum crispum) and carrot (Daucus carota) (bothApiaceae) andAcer pseudoplatanus (Aceraceae) were used to detect the primary gene product of the rDNA in plant cells. Parsley and carrot cells were labelled with [32P] orthophosphate. In both cases only one high molecular weight rRNA precursor was present on polyacrylamide gels under non-denaturing conditions. Its molecular weight did not exceed 2.5 × 106 daltons. The component emerged from the heterogenous material after a labelling period of 5–10 min. In parsley cells 45 min after onset of incubation labelled mature rRNA (25S and 18S) arrived in the cytoplasm. InAcer pseudoplatanus (incubation period 60 min) two rapidly labelled components did emerge from polyacrylamide gels; their molecular weights were 2.3 and 3.2− 3.4 × 106 daltons. After electrophoresis under denaturing conditions the larger component was no longer present, thus indicating that it was an aggregate of different RNA molecules. The molecular weights of the rRNA precursors ofD. carota andP. crispum determined after electrophoresis in formamide gels were about 2.1 × 106 daltons. From these results we have no evidence for the existence of rRNA precursors exceeding the molecular weight of 2.5 × 106 daltons.
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    Plant systematics and evolution 123 (1975), S. 107-115 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Centaurea ; Chromosome numbers ; Flora of the Mediterranean and C. Europe
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    Topics: Biology
    Notes: Abstract The chromosome numbers of several Mediterranean and Central European species from the genusCentaurea L. have been studied. The material was collected in natural habitats, exceptC. thracica andC. maxima. The numbers forC. cineraria (2n = 36; tetraploid!),C. subtilis (2n = 22),C. sonchifolia (2n = 44),C. sphaerocephala (2n = 44),C. napifolia (2n = 22),C. achaia (2n = 22),C. thracica (2n = 18), andC. maxima (2n = 28) are reported for the first time. For the following species earlier counts are confirmed:C. cineraria (diploid, 2n = 18),C. maculosa (2n = 18),C. rhenana (2n = 18),C. triumfettii (2n = 22 + 0−1 B; first report of accessory chromosome for this species),C. scabiosa (2n = 20 + 0−3 B),C. crassifolia (2n = 30). B-chromosomes are reported for 3 populations ofCentaurea scabiosa from Berlin; they lack in 2 populations from Bayern and Hessen.
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    Plant systematics and evolution 135 (1980), S. 11-39 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Winteraceae ; Drimys brasiliensis ; Development of inflorescences ; flowers and fruits ; reproductive biology ; pollination ; seed dispersal ; vegetative propagation ; early Angiosperm evolution
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    Topics: Biology
    Notes: Abstract From field observations onDrimys brasiliensis, principally in the Botucatu region of São Paulo State, Brazil, new data on the reproductive biology, the rhythm of growth, and the development of lateral cymose inflorescences, flowers and fruits are presented. Pollination accelerates the rate of flower-development for about 4–6 days. Pollination experiments show thatD. brasiliensis is not self-sterile; because of mechanical devices the sticky pollen grains do not normally come into contact with the stigmata unless an animal pollen vector is involved. The pollinators are diurnalColeoptera, Diptera andThysanoptera which eat from the pollen, lick from the stigmatic exudates and (in case of the flies) probably also from the staminal glands. Fruit- and seedeaters are birds which seem to be the main dispersal agents. Establishment of new individuals normally is through seedlings, but also by vegetative propagation through plagiotropous branches which may root and separate from the mother plant. The morphological, developmental and reproductive aspects inD. brasiliensis are discussed in a wider context, compared with data from otherMagnoliidae, and related to aspects of early Angiosperm evolution.
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    Plant systematics and evolution 137 (1981), S. 73-94 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Brassicaceae ; Capsella bursa-pastoris ; Isoenzyme polymorphism ; population analyses ; geographic variation ; heterozygosity ; breeding system
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    Topics: Biology
    Notes: Abstract The genetic variability of natural populations ofCapsella bursapastoris in North- and Middle-Europe has been estimated by means of enzyme assays. Zymograms of 81 populations have been developed. 17 loci could be identified, and 8 of them can be heterozygous. Genetic variability is greater between populations than within. No correlation between actual population sizes and genetic heterogeneity could be detected. Some electromorphs shift their frequencies proportionally to increasing adversity of climatic conditions, some appear to be constant over the whole area, and others are characterized by an apparently irregular variation pattern. Marginal populations comprise a significantly higher proportion of heterozygous plants than central ones. Apart from this clinal variation pattern, a mosaic pattern, strongly related to habitat conditions, was observed: genetic heterogeneity is greater in more intensively disturbed sites. The pattern of genetic variation in natural populations ofCapsella bursa-pastoris is rather highly influenced by the breeding system.
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    Plant systematics and evolution 136 (1980), S. 247-258 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae (=Gramineae) ; Triticum ; Aegilops ; diploid species ; Starch Gel electrophoresis ; allozymic variation ; phylogenetic relationships ; evolution
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    Topics: Biology
    Notes: Abstract Twenty enzyme loci were examined in the diploid species ofTriticum andAegilops for allelic variation by starch gel electrophoresis. SectionSitopsis, including the five species,Ae. speltoides, Ae. lingissima, Ae. sharonensis, Ae. bicornis andAe. searsii form a close subgroup withAe. speltoides slightly removed from the others.T. monococcum s. lat., was found to be closest to the species of theSitopsis group.Ae. comosa, Ae. umbellulata andAe. uniaristata form a second subgroup withAe. caudata most closely related to these species.Ae. squarrosa appears almost equally related to all of the species, showing no special affinity for any one species group. Nineteen out of twenty loci examined were polymorphic with a mean of 6.7 alleles per locus. Species could be, for most loci, characterized by the presence of predominant alleles. A conspicious genetic characteristic ofTriticum-Aegilops is the sharing of these predominant alleles between species. Within species variation is characterized by a diffuse distribution of secondary alleles.
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    Plant systematics and evolution 137 (1981), S. 63-65 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Emblingia ; Emblingiaceae ; Sapindaceae ; Dodonaea ; Stylobasidaceae ; Stylobasium ; Gyrostemonaceae ; Anemophily ; entomophily ; autogamy
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    Topics: Biology
    Notes: Abstract Emblingia is a short lived fire weed with a highly autogamous breeding system.
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    Plant systematics and evolution 138 (1981), S. 47-60 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Ranunculus seguieri ; R. alpestris ; R. traunfellneri ; R. bilobus ; R. crenatus ; Relationship betweenR. seguieri andR. alpestris s. lat.: morphology ; crossing experiments ; chromosome numbers ; karyotypes
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    Notes: Abstract Morphological and cytological investigations as well as crossing experiments were carried out withRanunculus seguieri Vill. and 4 species of theRanunculus alpestris L. group (R. alpestris L.,R. traunfellneri Hoppe,R. bilobus Bertol.,R. crenatus Waldst. & Kit.). ForR. seguieri andR. alpestris, localities and distribution are given in addition to extensive diagnoses. A key to the species includes morphological characteristics and distribution data forR. traunfellneri, R. bilobus, andR. crenatus. New diagnostic characters are described. Crossing experiments betweenR. seguieri and the species of theR. alpestris group were unsuccessful. All 5 species have a chromosome number of 2n = 16, the record forR. bilobus is new. There is no statistically significant difference between the karyotypes ofR. seguieri andR. alpestris s. str. Nevertheless, according to morphological evidence and crossing experiments,R. seguieri is not closely related to theR. alpestris group.
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    Plant systematics and evolution 137 (1981), S. 127-134 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Boraginaceae ; Pyrrolizidine alkaloids ; phenolic compounds ; chemotaxonomy
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    Topics: Biology
    Notes: Abstract By means of thin layer chromatography pyrrolizidine alkaloids and phenolic compounds in some members of the familyBoraginaceae, subfamiliesHeliotropioideae andBoraginoideae, were studied. FromOmphalodes verna a main alkaloid was isolated with an isoretronecanol (or stereoisomeric) nucleus. The chemotaxonomical model ofTétényi forBoraginaceae based on fatty acids is generally supported, but relationships betweenHeliotropioideae andCynoglosseae appear to be closer, suggesting parallel developments from common ancesters.
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    Plant systematics and evolution 138 (1981), S. 175-188 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Eriocaulaceae ; Eriocaulon setaceum ; Embryology ; systematics
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    Topics: Biology
    Notes: Abstract Eriocaulon setaceum can be characterized by: young microsporangium wall with epidermis, endothecium (with fibrous thickenings), and glandular tapetum (uninucleate cells); pollen grains 3-celled, spiraperturate; embryo sac development according to the Polygonum type and with antipodal cyst; endosperm nuclear; embryo small, with incipient differentiation into cotyledonary and epicotylary loci; seed coat mainly from the inner layers of the integuments; pericarp 2-layered and membranous. Embryologically, theEriocaulaceae are nearer to theXyridaceae than to otherFarinosae. Their elevation to the rank of an order,Eriocaulales, therefore appears justified.
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  • 42
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Hordeum spontaneum ; Allozymes ; microgeographic differentiation ; population genetics
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    Notes: Abstract Allozymic variation in proteins encoded by 22 loci was analyzed electrophoretically in 278 individual plants of wild barley,Hordeum spontaneum, the progenitor of cultivated barley, in four 100 meter transects, in Israel, each equally subdivided into basalt and terra rossa soil types. Significant differentiation according to soil was found in 9 alleles. Our results suggest that allozyme polymorphisms in wild barley are at least partly adaptive, and differentiate by edaphic natural selection rather than by stochastic processes, and/or neutrality of allozymic variants.
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    Plant systematics and evolution 139 (1981), S. 11-45 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Solanaceae ; Lycopersicon ; Solanum pennellii ; Allozymes ; electrophoresis ; isozymes ; mating systems ; self-incompatibility
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    Topics: Biology
    Notes: Abstract Genetic variation—primarily in 19 genetic loci of seven enzyme systems—was analyzed in accessions from various parts of the geographic range ofSolanum pennellii, which according to all tested biosystematic criteria behaves like a species ofLycopersicon. In comparison with the largely sympatricL. hirsutum andL. pimpinellifolium, this species exhibits the same trends of reduced allogamy and decreased genetic variation toward the north and south margins of its distribution, though to a much lesser degree; it does not exhibit their trends toward smaller flower size in the same peripheral regions. All three species agree to a considerable extent in the ranking of their tested loci in respect to degree of variablility; however, overall polymorphy is highest inS. pennellii. Except for the appearance of self-compatibility at its southernmost margin,S. pennellii is exclusively and rigidly self-incompatible. Alleles are distributed much more uniformly over the range than in the previously mentioned species, marginal and internal endemic mutants being much less abundant. A marked geographic disagreement is evident in regions of high and low variation. These differences in patterns of genetic variability are reconciled in terms of observed differences in mating systems, probable age of distributions, and adaptive strategies.
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    Plant systematics and evolution 138 (1981), S. 259-262 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Bromeliaceae ; Tillandsia subgen.Allardtia ; T. kolbii ; spec. nova ; Flora of Mexico
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    Notes: Abstract A new species ofTillandsia is described and discussed in regard to related species.
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    Plant systematics and evolution 138 (1981), S. 263-274 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Rutaceae ; Citrus limon ; Style ; canal cells ; canal filling substance ; ultrastructure ; anatomy
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    Notes: Abstract The ultrastructure of the canal cells and the canal filling substance ofCitrus limon have been studied. At maturity the canal cells are very rich in cytoplasm. Their inner tangential walls lining the canal are much thickened and formed by two layers: the outer corresponds to the original wall, the inner is formed by subsequent deposition of abundant materials of different origin. This thickening occurs at the same time as the filling of the stylar canal. Both events are paralleled by considerable dictyosomic activity, the formation of a large amount of rough endoplasmic reticulum, and the incorporation of small cytoplasmic masses into the cell wall, due to plasmalemma evaginations. — The material in the stylar canal has a heterogeneous ultrastructure aspect and consists of polysaccharides, proteins and lipids; it presumably provides nutrients for the growing pollen tubes.
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    Plant systematics and evolution 139 (1982), S. 209-227 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Dicotyledons ; Monocotyledons ; DNA reassociation kinetics ; fast repeats ; repetitive DNA ; single copy DNA ; short period interspersion pattern ; slow repeats ; genome evolution
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    Notes: Abstract Angiosperms investigated by DNA/DNA reassociation studies were classified and tested for a taxonomic class- and subclass-specifity in a biometrical fashion. Monocotyledons and Dicotyledons differ significantly from each other with respect to a genomic parameter (U/R-ratio;U single copy DNA fraction;R = 1-U fraction of repetitive DNA). This difference is discussed from an evolutionary and molecular point of view.—Intercorrelations between the fraction of fast repeats, slow repeats, and single copy DNA can be detected. The amount of DNA organized in a short period pattern of interspersion is found to depend on the fraction of repetitive and single copy DNA. The number of DNA segments tandemly arranged in a short period pattern is linearly correlated withR/U-values. This correlation allows for a formula suitable for the estimation of the number of active genes in angiosperms. The analytical complexities of repetitive and single copy DNA are linearly correlated with the genome size of higher plants. The ratioU/R depends on the genome size of angiosperms in a hyperbolic fashion.
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    Plant systematics and evolution 139 (1982), S. 163-178 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliaceae ; Tulipa subg.Leiostemones ; Giemsa banding ; heterochromatin ; karyosystematics
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    Notes: Abstract The chromosomes of several cultivatedTulipa species of subg.Leiostemones were examined in conventionally stained and C-banded preparations. The heterochromatin content varied from almost none to 45%. Several chromosome types were recognized with respect to chromosome morphology and heterochromatin distribution, and groups of species with common chromosome characteristics could be identified. These karyological relationships are discussed with respect to the groups formed on the basis of floral and bulb charateristics.
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    Plant systematics and evolution 160 (1988), S. 1-28 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Triticeae ; Systematics ; phylogeny ; cladistic ; phytogeography ; isozyme analyses ; chromosome pairing ; DNA analyses ; relationships ; molecular evolution
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    Notes: Abstract The evolution and taxonomic relationships in theTriticeae are discussed with the view to highlight aspects of this agronomically important group of plants, which may be of interest to molecular biology. Some of these aspects are addressed in more detail in adjoining papers in which specific genomic loci have been examined at the DNA sequence or isozyme level. Aspects discussed include the systematics and geographic distribution of theTriticeae species, isozyme and chromosome pairing studies on some of the species as well as more recent developments in DNA analyses. A survey of the systematics of theTriticeae indicated that the genomic system ofLöve is probably the most useful starting point for interpreting molecular data even though the system has many problems from a taxonomic point of view. The geographical distribution ofTriticeae species, using both published and unpublished data, suggested that information of this type taken together with the theory of continental drift provides a broad time-span for considering data from DNA sequence studies. The significance, and modes of analyses, of isozyme studies were assessed because they often provide valuable characters in determining relationships between species. The main character underlyingLöve's andDewey's analyses of theTriticeae, namely chromosome pairing, is discussed with particular reference to isozyme studies to show that in some cases, such as species ofHordeum sensu lato, consistent relationships are obtained. Finally, new developments in understanding chromosome structure are considered in relation to the above variables in the taxonomy and evolution of theTriticeae.
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    Plant systematics and evolution 160 (1988), S. 65-76 
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    Keywords: Angiosperms ; Poaceae ; Triticeae ; Secale cereale ; Agropyron cristatum ; 350-family DNA sequences ; R and P genome ; in situ hybridization ; Nor-loci ; 5 S-DNA loci ; relationship ; chromosome pairing ; isozymes
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    Notes: Abstract Evidence is presented that in the R and P genomes (Secale cereale andAgropyron cristatum, respectively) of theTriticeae there exist closely related 350-family DNA sequences in the terminal heterochromatin. This observation is compared to the relationships between these two genomes derived from a comparison of theNor and5 S DNA loci as well as the available data on morphological characters, chromosome pairing, and isozyme studies. It is concluded that the R and P genomes are not closely related and that the common presence of very similar 350-family DNA sequences reflects the parallel amplification of this family of DNA sequences.
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    Plant systematics and evolution 160 (1988), S. 91-104 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Poaceae ; Triticeae ; Ribosomal DNA spacer regions ; phenetic and molecular relationships
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    Notes: Abstract Two regions of the ribosomal DNA (rDNA) were sequenced from a range of species from the tribeTriticeae. One region, the central spacer, was found to be more divergent in sequence than the other, the 18 S-spacer junction. Both regions contained sequences 20–30 bp long which were more highly conserved than the remainder of the region and their possible significance in rDNA expression is discussed. Phenetic relationships based on the sequence data were generally consistent with the relationships based on other criteria. Species possessing the S, E, J1J2, D, and B genomes clustered together, with the H genome species being the most distinct of those examined. The R, P, and V genome species occupy an intermediate position in the overall pattern of relationships. Some relationships differed in detail from those established by other parameters, for example the position of the N genome species, and explanations for discrepancies of this type are discussed.
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    Plant systematics and evolution 160 (1988), S. 153-158 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Zygophyllaceae ; Balanitaceae ; Balanites aegyptiaca ; Chemosystematics ; quercetin and isorhamnetin glycosides
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    Notes: Abstract Six flavonoid glycosides: quercetin 3-glucoside, quercetin-3-rutinoside; 3-glucoside, 3-rutinoside, 3-7-diglucoside and 3-rhamnogalactoside of isorhamnetin were extracted and identified from the leaves and branches of Egyptian material ofBalanites aegyptiaca. Only isorhamnetin: 3-rutinoside and 3-rhamnogalactoside were recorded from the fruits of the same plant.—Phytochemical aspects ofBalanites aegyptiaca and some genera ofZygophylaceae s. l. viz.Nitraria, Fagonia, Zygophyllum, Seetzenia andTribulus support its affinities with that family.
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    Plant systematics and evolution 160 (1988), S. 143-151 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Fabaceae ; Arachis hypogaea ; Amphidiploids ; chromosome pairing ; genome ; putative ancestors
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    Notes: Abstract Chromosome pairing, pollen and pod fertility in hybrids between cultivated tetraploidArachis hypogaea and 15 synthetic amphidiploids from 8 diploid species (7 of the A genome and 1 of the B genome) of sect.Arachis have been utilized for the identification of putative genome donors in the evolution of cultivatedA. hypogaea. These results, in conjunction with evidence from morphological similarities, phytogeographical distribution and some phytochemical features, confirm the segmental amphidiploid origin ofA. hypogaea. A. batizocoi andA. duranensis are suggested as the donors of the B genome and the A genome respectively.
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    Plant systematics and evolution 160 (1988), S. 181-188 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Ranunculaceae ; Helleborus viridis subsp.viridis and subsp.occidentalis ; H. odorus subsp.laxus. ; Range of distribution ; taxonomy ; Flora of Northern Italy
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    Notes: Abstract The taxon commonly namedHelleborus viridis in Lombardy (NW. Italy) differs from both, subsp.viridis and subsp.occidentalis, and is shown to fall within the variation range ofH. odorus subsp.laxus which has been reported so far for NE. Italy only. TrueH. viridis within Italy grows only in the Maritime Alps.
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    Plant systematics and evolution 160 (1988), S. 189-193 
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    Keywords: Angiosperms ; Euphorbiaceae ; Euphorbia ; Chamaesyce ; Latex starch grains ; phylogenetic and taxonomic implications
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    Notes: Abstract Latex starch grains of certain Indian species ofEuphorbiaceae belonging toEuphorbia, Chamaesyce, Pedilanthus, Synadenium andMonadenium have been studied. They exhibit distinct shapes in different taxa, i.e., rod, spindle, osteoid, dumb-bell and discoid. This helps i.a. in the taxonomic circumscription ofChamaesyce fromEuphorbia.
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    Plant systematics and evolution 161 (1988), S. 35-47 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Cruciferae ; Capsella bursa-pastoris ; Adaptation ; germination behaviour in natural populations ; seed dormancy
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    Topics: Biology
    Notes: Abstract Germination behaviour of variousCapsella bursa-pastoris populations collected from Scandinavia, Middle Europe and the Alps, was tested in unheated, non-illuminated greenhouses (46 populations) and in growth chambers using 5–7 alternating temperature regimes (16 populations). For all populations, the influence of temperature on germination rate is straightforward: the higher the temperature, the greater the germination. Germination capacity, however, may depend on the geographical region. There is also a strong seed age effect on both, rate and capacity of germination. Once dormancy was broken, seeds from all populations were able to germinate over the entire range of temperatures. Some populations revealed a more or less pronounced temperature optimum for germination capacity, others germinated equally well over the entire temperature range. This indicates genetic heterogeneity between populations. However, no correlation between germinability and any environmental pattern was detected. The data indicate thatCapsella bursa-pastoris has adopted a germination strategy which includes a broad temperature tolerance. Germination of wildCapsella plants seems to be regulated by the factors contributing to the inception and breaking of dormancy which depend on pre- and postharvest conditions. Adaptation in germination behaviour inCapsella bursa-pastoris is different from that in other life history traits (flowering behaviour, growth form parameters).
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    Plant systematics and evolution 161 (1988), S. 87-89 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Zygophyllaceae ; Fagonia sinaica ; F. cretica ; F. tenuifolia ; Flavonoids ; chemosystematics
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    Notes: Abstract Eight flavonol glycosides were detected in the three species of theFagonia sinaica complex. They were fully characterized as the 3-glucosides of kaempferol, quercetin and isorhamnetin, 3-rutinoside of quercetin and 3,7-diglucoside of quercetin and isorhamnetin. Two additional glycosides were partially characterized as a kaempferol 3,7-diglycoside and quercetin 3-diglycoside.
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    Plant systematics and evolution 162 (1989), S. 213-229 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Fagaceae ; Cuticles ; Recent ; Tertiary ; evolution
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    Topics: Biology
    Notes: Abstract A systematic reassessment of megafossil records ofFagaceae in Central Europe has been undertaken on the basis of leaf cuticular characters. The oldest representatives date back to the Eocene:Quercus subhercynica spec. nova,Dryophyllum furcinerve (Rossm.)Schmalh.,Trigonobalanopsis rhamnoides (Rossm.) gen. & comb. nov. In the Oligocene other members of extant genera appear:Quercus rhenana (Weyl. & Kilpp.)Knobloch & Kvaček,Fagus attenuata Goepp.,Lithocarpus saxonicus spec. nova. In the Neogene these ancient taxa (except inFagus lineage), are gradually replaced by deciduous species ofQuercus andCastanea. Trigonobalanus andCastanopsis are recorded by fruits (or wood) only.
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    Plant systematics and evolution 162 (1989), S. 165-191 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Chloranthaceae ; Platanaceae ; Trochodendrales ; Fagaceae ; Cercidiphyllum ; Paleobotany ; phylogeny ; floral structure ; leaf architecture
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    Topics: Biology
    Notes: Abstract Paleobotanical studies indicate that several isolated and systematically depauperate groups of extant woody dicotyledons originated in the Mid Cretaceous. TheChloranthaceae had probably differentiated into insect-pollinated (Chloranthus andSarcandra) and wind-pollinated (Ascarina andHedyosmum) forms by the end of the Albian, and leaves referable to theTrochodendrales are known from the Albian and Cenomanian. In the latest Cretaceous and Early Tertiary, extinct representatives of theTrochodendrales includedNordenskioldia and theJoffrea-Nyssidium complex. ThePlatanaceae also differentiated before the end of the Albian and initially had insect-pollinated, unisexual flowers with five carpels or stamens. Some of these features persisted in the platanoid lineage until the Early Tertiary, and during the Paleocene and Eocene thePlatanaceae included forms with elliptical, palmate and pinnate foliage. The history of thePlatanaceae suggests that several features of the reproductive morphology of extant taxa may have arisen in association with a trend toward wind pollination. In the Mid Cretaceous, platanoid foliage partially intergrades with pinnateSapindopsis and pedateDebeya-Dewalquea leaves suggesting a close relationship betweenPlatanaceae andRosidae andFagaceae respectively. TheChloranthaceae, Trochodendrales, andPlatanaceae all occupy a somewhat intermediate position between theMagnoliidae andHamamelidae and are of considerable interest with respect to their role in the initial radiation of nonmagnoliid (“higher”) dicotyledons.
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    Plant systematics and evolution 162 (1989), S. 193-211 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Hamamelididae ; Trochodendrales ; Hamamelidales ; Hamamelidaceae ; Hamamelideae ; fossilHamamelidaceae ; Floral structure ; fruit ; seed ; valvate anther dehiscence ; Floral evolution
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    Notes: Abstract New investigations on the flower and fruit structure of extantHamamelidaceae and other LowerHamamelididae together with new finds of fossil flowers and seeds from the Upper and Lower Cretaceous provide the outline of an increasingly more differentiated picture of the early evolution of the subclass. Three patterns of valvate anther dehiscence are recognized in the subfamilyHamamelidoideae (and the subclassHamamelididae). The basic (plesiomorphic) type within theHamamelididae has 2 valves per theca. The type with 1 valve but 2 pollen sacs per theca is both consistent and exclusive for the 5 southern genera of theHamamelidaceae. They seem to be the remnants of a homogeneous group that originated before the Upper Cretaceous. This is supported by fossil hamamelidaceous flowers from the Upper Cretaceous that have thecae with 1 valve. Since several-seededHamamelidaceae predate one-seeded forms in the fossil seed record (in Europe) and the systematic structure of the one-seeded group is relatively more homogeneous, several-seeded groups are considered to be more ancient. Several parallel evolutionary trends are recognized within theHamamelidaceae as well as within the LowerHamamelididae: anther dehiscence with 2 valves per theca → 1 slit or 1 valve; pollen sacs per theca 2 → 1; pollen tricolpate → polyforate; exine coarsely reticulate → finely reticulate; loss of perianth (tepals or petals and sepals) and concomitant loss of fixed number of floral organs; differentiation of exposed nectaries.
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    Plant systematics and evolution 162 (1989), S. 231-250 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Juglandaceae ; Paleobotany ; pollen ; fruits ; evolution ; Cretaceous ; Tertiary
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    Notes: Abstract The major radiation of theJuglandaceae occurred during the early Tertiary as recorded by the proliferation of juglandaceous pollen and the appearance of fruits representing extinct and extant genera of the family. Juglandaceous pollen types of the Paleocene were predominantly triporate and exhibited a greater diversity in patterns of exinous thinning than occurs in the family today. Analyses of in situ pollen from early Tertiary juglandaceous inflorescences confirms the taxonomic value of certain patterns of exinous thinning. Data from co-occurring fruits and pollen indicate that relatively unspecialized, isopolar triporate pollen of the type presently confined to the tribeEngelhardieae also occurred in other tribes of the family during the Paleocene. Pollination has been mostly anemophilous throughout the Tertiary. Both wind and animal fruit-dispersal syndromes were established early in the radiation of the family but a greater diversity of wind-dispersed genera has prevailed.
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    Plant systematics and evolution 162 (1989), S. 251-265 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Rutaceae ; Phylogeny ; fructifications ; morphology ; anatomy ; paleogeography ; Cretaceous ; Tertiary
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    Notes: Abstract A comparative analysis of the seed morphology and anatomy of fossil and extantRutaceae (mainlyZanthoxyleae andToddalioideae) is presented. This allows to place the most important fossil taxa in a time-table and on paleogeographical maps. A phylogenetic scheme demonstrates the postulated historical relationships ofEvodia, Zanthoxylum, Fagara, Rutaspermum, Acronychia, Toddalia, Fagaropsis, andPhellodendron.
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    Plant systematics and evolution 162 (1989), S. 267-283 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Buxaceae ; Buxus ; Pollen morphology ; leaf venation ; fossil records ; systematics ; evolution ; chorogenesis
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    Notes: Abstract Trends of pollen grain aperture evolution and exine characters as well as characters of leaf venation, petiole and axial vascularization are briefly described and related to geographical distribution and classification ofBuxus. A review of fossil records is given. Three major taxonomic groups can be delimitated within the genus, and aspects of their relationships and chorogenesis are presented. The level of differentiation, the pattern of distribution and the fossil record speak in favour of an ancient origin of the genus.
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    Plant systematics and evolution 165 (1989), S. 227-237 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Eucalyptus ; Eudesmieae ; Floral morphology ; calyx ; corolla ; operculum ; growth ; allometry ; convergence
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    Notes: Abstract In theEudesmieae B eucalypts and inEucalyptus caesia, the perianth of the mature flower consists of a single, anatomically continuous, opercular structure that is crowned by the tips of the original free and separate calycine and corolline whorls. Ontogenetic and comparative evidence supports the hypothesis that this operculum is mostly corolline in composition, and that the calycine parts have been elevated distally onto the dorsal surface. In theEudesmieae B eucalypts this condition appears to be due to precocious initiation of the corolline primordia, followed by expansion and continuity of their growth centres which incorporates the areas at or below the base of the still differentiating calycine whorl. InEucalyptus caesia the corolline primordia are not precocious, but a similar situation is effected by a seemingly retarded increase in receptacle diameter relative to lateral expansion of the corolline growth centre(s). In these two examples the same final perianth form apparently derives from two different sets of growth processes which, nonetheless, result in the same allometric relationships within the developing flower. Although identical at maturity, the operculum form in these two taxa is best described in terms of convergence, rather than homology.
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    Plant systematics and evolution 166 (1989), S. 41-44 
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    Keywords: Angiosperms ; Araceae ; Arum spp. ; Pollen types ; pollination
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    Notes: Abstract In a second paper onArum pollen seven further taxa are investigated. Most of them have spinose pollen, only inA. korolkowii the pollen is scabrose. The possible relation between pollen sculpturing and the actual pollination mode is discussed.
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    Plant systematics and evolution 166 (1989), S. 11-30 
    ISSN: 1615-6110
    Keywords: Angiosperms ; monocotyledons ; Amaryllidaceae ; Eucharis ; Phenetics ; chromosome morphology ; isozyme electrophoresis ; speciation ; sibling species
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    Notes: Abstract Eucharis candida andE. formosa are two often sympatric species of bulbous geophytes restricted to neotropical rain forest understory. The species are most common in eastern Ecuador, and are the only two east Ecuadorean species of the genus found north of the Pastaza valley. Data from phenetic, karyotypic, and preliminary isozyme electrophoretic analyses of both species are represented. The species are distinguishable phenetically and karyologically, but isozyme-based relationships are more complex. Phenetic resolution of the isozyme phenotypes supports recognition of two species in Ecuador. A Peruvian isolate ofE. formosa, though not morphologically distinct, shows both allozyme and chromosomal divergence from Ecuadorean populations. Cladistic relationships based on overall allozyme data do not support species distinction, but a novel electrophoretic phenotype for glutathione reductase is shared only by individuals ofE. candida. An apparent geographic component within the monophyletic groups resolved in the cladogram suggests that some degree of gene flow between these two species has been maintained without the complete loss of morpholgoical species identity. This may have been mediated either by artificial population structures due to a probable long history of cultivation, or via Pleistocene refugia effects. Both species may have originated in eastern Ecuador from a common ancestral population which has since radiated outward, perhaps several times.
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    Plant systematics and evolution 166 (1989), S. 45-67 
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    Keywords: Angiosperms ; Compositae ; Espeletia ; Diallel cross ; pollen donors ; parental effects ; outcrossing distance ; inbreeding ; seed abortion ; incompatibility ; pollen tube growth
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    Notes: Abstract The influence of different pollen donors on seed formation was investigated in three populations ofEspeletia schultzii that differ in environmental conditions and life history characteristics. Self pollen and pollen from different donors (〈 15m apart) within each population was used in a diallel design in order to test the genetic base of seed set variation. Three measures of seed formation were used: (1) achene number; (2) proportion of filled achenes (fruits) that distinguishes between achenes with seeds and empty achenes; (3) proportion of aborted seeds that distinguishes between viable and aborted seeds. Self-pollinations resulted in empty achenes. Achene number did not vary between the different pollen donors. A bimodal pattern of filled achenes was found in two populations in two consecutive years. On the other hand, a unimodal pattern was found in crosses between more distant donors (〉 30m). These patterns seems to be the results of a sporophytic incompatibility system. Seed abortion was highest at the higher elevations and seems to be correlated with elevation rather than with any genetic effect.
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    Plant systematics and evolution 166 (1989), S. 69-78 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leguminosae ; Medicago lupulina ; M. secundiflora ; Chromosomes ; karyotypes ; chloroplast DNA evolution ; phylogeny
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    Notes: Abstract Studies were made on the chromosome complements and chloroplast genomes ofMedicago lupulina andM. secundiflora, which comprise sectionLupularia ofMedicago. Both types of analyses indicated more substantial differences between these species than suggested by external morphology.Medicago lupulina has a relatively asymmetrical karyotype in terms of centromeric position and relative length. The karyotype ofM. secundiflora is comparatively more asymmetrical in centromeric position and reduced in absolute size but exhibits greater symmetry in relative length. The restriction endonuclease fragmentation patterns of the chloropiast DNA of these two species (with Bam HI, Eco RI, Bgl II, and Xho I) show little similarity, with only 17% of the fragments matching in size. The lack of interspecific congruence among data of morphology, karyology and cpDNA inLupularia is contrary to consistency exhibited among these data inMedicago subsect.Intertextae.
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    Plant systematics and evolution 166 (1989), S. 131-139 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Najadaceae ; Najas marina ; Isozymes ; polyploidy ; Polymorphism
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    Notes: Abstract The genetic variability of five natural populations ofNajas marina L., i.e. one diploid of subsp.marina (Europe), two of subsp.intermedia (Europe) and both a diploid (C. Africa) and a tetraploid (Middle East) of subsp.armata, has been estimated by means of electrophoretic studies. These populations differ in their morphology and karyotype. Emphasis is placed on the characteristics and status of a tetraploid cytotype from Merkaz Sappir (Israel). Almost all the variation observed is expressed in seed alcohol dehydrogenase (ADH). The differences are in a unique allele of theAdh-2 locus and in the formation of novel heteromeric isozymes.Adh genes in seeds can be used as a marker for the autotetraploid character. The other enzyme systems tested failed in this respect. The genetic variability based on 23 loci is rather low. Nevertheless, the autotetraploid population has a higher or equal ratio of polymorphic loci than the related diploids. Cluster analysis illustrated not only thatNajas marina subsp.marina has diverged much from subsp.intermedia and subsp.armata, but also showed the difference between the latter two taxa, as well as the intermediate position of the autotetraploid population.
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    Plant systematics and evolution 166 (1989), S. 183-196 
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    Keywords: Angiosperms ; Myrtaceae ; Eucalyptus ; E. clöeziana ; Monocalyptus ; Floral morphology ; operculum ; androecium ; staminophore ; phyllotaxy
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    Notes: Abstract Flowers ofEucalyptus clöeziana have two clearly distinct perianth whorls. The small free parts of the outer (calycine) whorl cease growth early and are lost from the flower; the parts of the inner (corolline) whorl become continuous laterally by confluence of growth centres and form an operculum in the mature flower. The stamens are inserted on a circumfloral buttress (staminophore) that is homologous to the adaxial corolline component inAngophora and the bloodwood andEudesmia eucalypts. Flowers ofMonocalyptus have only one perianth whorl, which is opercular. The stamens are similarly inserted on a circumfloral buttress. Developmental study does not provide conclusive evidence for either a calycine or corolline determination of theMonocalyptus operculum, but comparison with other eucalypt groups, includingE. clöeziana (the sister taxon), predicts an essentially corolline composition.
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    Plant systematics and evolution 166 (1989), S. 211-223 
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    Keywords: Angiosperms ; Poaceae ; Triticeae ; Hordeum brachyantherum ; H. californicum ; H. capense ; H. secalinum ; Morphometrics ; cluster analysis ; classificatory discriminant analysis ; canonical analysis ; sheared principal component analysis ; bootstrap validation ; identification key
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    Notes: Abstract Field collections and 296 herbarium sheets were examined for 27 morphometric variables. A priori species identifcation was based on geographical distribution except forH. californicum, a diploid species primarily occurring in California and differing from the much more widespread tetraploidH. brachyantherum that thrives in N. America and N.E. Asia;H. capense grows in S. Africa andH. secalinum mainly in Europe. Various cluster analyses were used followed by cluster recovery verification. Classificatory discriminant analysis and validation by the bootstrap yielded 85–90% overall total correct classification of the four species. Canonical analysis revealed thatH. californicum occupies an intermediate phenetic position among the other three distinct species. Factors of shape differences were unravelled and portrayed by shearing. A revised key to species was drawn up.
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    Plant systematics and evolution 166 (1989), S. 225-241 
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    Keywords: Angiosperms ; Geraniaceae ; Geranium caespitosum ; Breeding system ; ecotype ; gynodioecy ; pollen sterility ; self-fertility ; selfing ; inbreeding depression ; stigma receptivity
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    Notes: Abstract Characters that have the potential to alter the breeding system ofGeranium caespitosum were investigated. The characters differ mechanistically, functioning either endogenously and independent of pollen transfer, or exogenously by influencing pollen transfer. Little variation in self-fertility (endogenous mechanism) was measured among populations from different elevations grown in a common garden. Variation in floral morphology (exogenous mechanism) was limited and unlikely to create a change in the breeding system. Macroscopic variation (exogenous mechanism), including gynodioecy, sexual specialization, and pollen sterility, was observed in extreme elevation populations and probably has a sizeable effect on the breeding system.
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    Plant systematics and evolution 166 (1989), S. 249-252 
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    Keywords: Angiosperms ; Primulaceae ; Cyclamen ; C. somalense ; Taxonomy ; phytogeography ; Mediterranean floristic element ; Flora of Somalia
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    Notes: Abstract Cyclamen somalense Thulin & Warfa, spec. nova, the first member of the genus known from tropical Africa, is described from the Al Miskat Mts in NE. Somalia. The new species is closely related to the E. MediterraneanC. persicum Mill. The disjunct Mediterranean element in the mountain flora of northern Somalia, to whichC. somalense belongs, is believed to be largely a relict of Tertiary origin.
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  • 73
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    Keywords: Angiosperms ; Ranunculaceae ; Ranunculus cantoniensis ; R. chinensis ; R. silerifolius ; Amphidiploid ; aneuploid induction ; cytotaxonomy ; fertility ; habitat segregation ; hybrid ; multivalent ; speciation
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    Notes: Abstract Cytogenetical studies were carried out on the successive generations of offsprings from the induced tetraploid hybrid (2n = 32) betweenRanunculus silerifolius (2n = 16) andR. chinensis (2n = 16). Aneuploids, 2n = 30 to 35, frequently occurred. In latter subsequent generations the deviation of aneuploids increased, but the proportion of euploids decreased, accompanied by the reduction of fertility of pollen grains and seed sets. F2 and F4 PMCs constantly exhibited meiotic abnormality, i.e. formation of quadrivalents and univalents. The speciation process ofR. cantoniensis (2n = 32), which was presumed to arise from tetraploid hybrids between the above two species, is discussed on the basis of the above evidences.
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    Plant systematics and evolution 167 (1989), S. 137-148 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Leporella ; Formicidae ; Myrmecia ; Ant pollination pseudocopulation ; floral morphology
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    Notes: Abstract Leporella fimbriata is a self compatible orchid of southern Australia. It is dependant across its range on unique pollination by sexually attracted male winged antsMyrmecia urens, which pseudocopulate with the flower. Typical pollination sequences began with an initial circling then zig-zag flight to the flower. Vectors usually alighted on the inflorescence stem and quickly crawled to the flower where they adopted a copulatory position sideways along the wide labellum, pseudocopulatory probing immediately followed. In this position pollen carried on the thorax was deposited on the stigma. Departure from the labellum usually resulted in pollinium removal. Pollinator movements were restricted and the distribution leptokurtic with a mean of 3.141 ± 4.59 m. Pollination was widespread but variable from site to site and season to season with a maximum of 70% of all flowers being pollinated. Pollinator limitation is indicated. Traits essential for this pollination interaction include the coincidence of orchid and ant geographic distributions and the coincidence of flowering with the flight period of the ant. The production of pheromonelike substances and the distinctive floral morphology are also essential for attraction and manipulation of male ants. The ant mating system which the orchid can exploit is also important.
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    Plant systematics and evolution 167 (1989), S. 189-194 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Magnoliidae ; Annonaceae ; Annona ; Rollinia ; Beetle pollination ; flower evolution
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    Notes: Abstract Dynastid scarab beetle pollination appears basic within the genusAnnona. Those species ofAnnona which are more morphologically derived, as well as allRollinia spp. possess reduced floral chambers and attract small beetles likeNitidulidae orStaphylinidae. Pollination of the primitive species ofAnnona byDynastinae would imply that the genus had not evolved before the Tertiary. The fossil record is in congruence with this hypothesis. Once again it is stressed that the cantharophilous syndrome, as it is found in theAnnonaceae, Magnoliaceae, Eupomatiaceae andCalycanthaceae, with beetles being exclusive pollinators, is a secondary and derived condition and obviously different from the expected basic entomophily of the original angiosperms.
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    Plant systematics and evolution 168 (1989), S. 49-57 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Compositae ; Hypochoeris ; Karyotype ; karyogram ; idiogram ; basic chromosome number ; symmetry of karyotype ; asymmetrical index
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    Notes: Abstract FiveHypochoeris spp. from Sicily have been investigated:H. glabra L. (2n=10),H. radicata L. (2n=8),H. cretensis L. (2n=6),H. laevigata L. (2n=12),H. robertia Fiori (2n=8). Basic chromosome numbers are very variable, x = 3, 4, 5, 6. The karyotype of each species is presented. Geographical origin (S. America or Mediterranean region) of the genusHypochoeris and the taxonomic position ofH. robertia are discussed.
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    Plant systematics and evolution 168 (1989), S. 143-148 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Caryophyllaceae ; Silene sect.Siphonomorpha ; sect.Auriculatae ; Crossing experiments
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    Notes: Abstract Ten species in the genusSilene sectt.Siphonomorpha andAuriculatae were crossed artificially involving 612 crosses to test inter- and infraspecific, intervarietal and intersectional crossability. In sect.Siphonomorpha all interspecific crosses (between diploids) failed due to cross- or seed-incompatibility; however, intervarietal crosses betweenS. gigantea var.gigantea andS. gigantea var.incana produced hybrids. In sect.Auriculatae hybrids were produced betweenS. vallesia andS. boryi, both tetraploids, but crosses between these and the diploid species were unsuccessful. The delimitation and status of the species in both sections was supported by the crossing results.
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    Plant systematics and evolution 168 (1989), S. 159-165 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Coryanthes ; Fragrance analyses ; 2-N-methylaminobenzaldehyde ; taxonomic studies
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    Topics: Biology
    Notes: Abstract All members of the investigated genusCoryanthes (subtribeStanhopeinae) are pollinated by male euglossine bees. The different fragrance profiles are the primary reproductive isolating mechanisms, because the flowers are interfertile. The fragrance patterns of 17 species ofCoryanthes were analyzed by gas chromatography as a means to improve the classification of this genus. A first amine (2-N-methylaminobenzaldehyde) was found to be the main fragrance compound of an as yet unclassifiedCoryanthes species.
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    Plant systematics and evolution 168 (1989), S. 221-225 
    ISSN: 1615-6110
    Keywords: Angiosperms ; monocotyledons ; Araceae ; Pothos sect.Allopothos ; Pothos crassipedunculatus ; spec. nova ; Taxonomy ; systematics ; Flora of India
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    Topics: Biology
    Notes: Abstract Pothos crassipedunculatus Sivadasan & Mohanan (Araceae), a new species closely related to the SW. Indian endemic and little known speciesP. thomsonianus Schott is described. It is characterized by the the non-ligulate, shortly vaginate petiole, thickly peduncled inflorescence, broadly ovate spathe and a sessile spadix. It is included in ser.Brevivaginati Engler of sect.Allopothos Schott.
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  • 80
    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliaceae ; Asphodelus tenuifolius ; A. fistulosus ; Cytogenetics ; electrophoretics ; morphology ; duplication genes ; speciation
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    Notes: Abstract The biological analysis of six populations ofAsphodelus tenuifolius and 12 populations ofA. fistulosus has confirmed that they are separate species. Both their floral structures (length of the tepals, stamens, anthers and style) and also their pollen size are clearly different.A. tenuifolius has only the 2n = 28 chromosome race, whileA. fistulosus has 2n = 28 and 2n = 56.A. tenuifolius is genetically less variable thanA. fistulosus and they have different electrophoretic mobilities. Gene duplication phenomena exist in the 2n = 28 level of both species.
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  • 81
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    Plant systematics and evolution 169 (1990), S. 41-54 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Abutilon theophrasti ; Datura stramonium ; Panicum miliaceum ; Sorghum halepense ; Setaria faberi ; Weeds ; allozymes ; life history ; variation ; Flora of N. America
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationships of allozyme and life history variation in a particularly narrow ecological setting are studied. Levels of genetic variation are compared in five introduced, predominantly selfing weedy species that are undergoing rapid range expansion northward in eastern N. America, mostly in monocultures of soybean and maize. In all of these species, a low level of allozyme variation contrasts sharply with the substantial inter- and intrapopulational variation in morphological and phenological life history features. Evolutionary and historical factors, determining variability of the species examined are reviewed, including founder effects, breeding system, environmental homogeneity, polyploidy, domestication, and crop-weed interactions.
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  • 82
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    Keywords: Angiosperms ; Boraginaceae ; Symphytum tuberosum complex ; S. grandiflorum agg ; Chemotaxonomy ; pyrrolizidine alkaloids ; triterpenes
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    Topics: Biology
    Notes: Abstract InS. tuberosum subspp.tuberosum andnodosum, S. grandiflorum andS. ibericum the presence of the pyrrolizidine alkaloids lycopsamine, echimidine and symphytine could be demonstrated. The taxonS. tuberosum contains an unknown compound that seems to be specific for this taxon. This compound is not the pyrrolizidine alkaloid anadoline which has previously been reported for this species. It is possibly represented by a peak on GC/MS with a molecular ion peak at m/z 623 (as TMS derivative) and can be used as a chemotaxonomic marker for the speciesS. tuberosum. The pyrrolizidine alkaloid pattern of the two subspecies ofS. tuberosum reinforces the close relationship. Fresh material ofS. tuberosum contained the triterpene isobauerenol, but in herbarium material isobauerenol was lacking. InS. grandiflorum, neither fresh nor dried material contains isobauerenol. In herbarium material ofS. ibericum also no isobauerenol could be found. More extensive chemotaxonomical research is necessary to support the view thatS. abchasicum is more closely related toS. ibericum than toS. grandiflorum.
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  • 83
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    Plant systematics and evolution 169 (1990), S. 97-110 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Compositae ; Inuleae ; Antennaria ; A. rosea ; Agamic complex ; agamospermy ; asexual reproduction ; clonal organism ; dioecy ; morphology ; numerical taxonomy ; phenetics ; polyploidy ; systematics
    Source: Springer Online Journal Archives 1860-2000
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    Notes: Abstract TheAntennaria rosea polyploid agamic complex is one of the most morphologically diverse and widespread complexes of N. AmericanAntennaria. The group is taxonomically confusing because of numerous agamospermous microspecies, having been recognized as distinct species. Morphometric analyses have demonstrated that the primary source of morphological variability in the complex derives from six sexually reproducing progenitors,A. aromatica, A. corymbosa, A. media, A. microphylla, A. racemona, andA. umbrinella. Additionally, two other sexually reproducing species,A. marginata andA. rosulata, may have contributed to the genetic complexity of theA. rosea complex. Cluster analysis indicates that four discrete morphological groups exist within theA. rosea complex. Each group could be the result of predominance of genes from different groups of sexual progenitors. AsA. rosea is of multiple hybrid origin, from among several sexual progenitors, it is advisable to recognizeA. rosea as a distinct species from its sexual progenitors.
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  • 84
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Inuleae ; Antennaria ; Geographic variation ; clinal variation ; principal component analysis ; correlation coefficients
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    Notes: Abstract Patterns of intraspecific variation were examined inAntennaria alborosea A. E. Porsild,A. corymbosa E. Nels,A. marginata Greene,A. microphylla Rydb.,A. parvifolia Nutt., andA. umbrinella Rydb. AlthoughA. alborosea was initially considered arctic in distribution, it became apparent that a southern montane element also exists. Our results suggest that morphological differences between arctic and southern montane specimens represent clinal variation. The additional morphological data for specimens that occur more than 1,500 km south of the species' range as it was initially described result in a better understanding of this once presumed arctic taxon. Morphological variation in the dioecious speciesA. corymbosa, A. marginata, A. microphylla, A. parvifolia, andA. umbrinella was greater between the genders than was geographic variation within each gender. These results demonstrate that both pistillate and staminate specimens must be examined in dioecious species ofAntennaria if morphological variation in the respective species is to be fully understood. Character size or number of broadly distributed species (A. microphylla andA. parvifolia) generally decreased with increasing longitude, whereas characters of species with more restricted distributions (A. alborosea, A. corymbosa, andA. marginata) generally increased in size or number with increasing latitude or longitude.Antennaria umbrinella was an exception in this respect.
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    Plant systematics and evolution 168 (1989), S. 123-141 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Liliiflorae ; Liliales ; Dioscoreales ; Asparagales ; Cladistics ; relationships ; taxonomy
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    Topics: Biology
    Notes: Abstract Comparisons between previous intuitive or phenetic classifications of the netveinedLiliiflorae was used to determine a suitable group of taxa for cladistic analyses. The resultant 48 genera and generic groupings comprising 19 families from within theAsparagales, Liliales andDioscoreales were then analysed. The cladistics largely supported previous treatments, with theLiliales, Dioscoreales andAsparagales all monophyletic.
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    Plant systematics and evolution 169 (1990), S. 25-29 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Oxalidaceae ; Oxalis tuberosa alliance ; Chromosome numbers ; karyotype analyses ; cytotaxonomy
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    Topics: Biology
    Notes: Abstract Twelve taxa of theOxalis tuberosa alliance were analysed and found to share the same basic chromosome number x = 8. The karyotypes are composed by small metacentric and submetacentric chromosomes. Different ploidy levels were found among the taxa: there were 9 diploids, 1 tetraploid, 1 hexaploid and 1 octoploid. The last ploidy level corresponds toO. tuberosa, the only tuber bearing taxon found so far in the alliance. Cytotaxonomic evidence and evolutionary considerations suggest to classify theO. tuberosa alliance in sect.Herrerea.
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    Plant systematics and evolution 169 (1990), S. 65-68 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Boraginaceae ; Onosma gigantea ; Trichodesma africana ; Trichodesma boissieri ; Buzz-pollination
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    Notes: Abstract Buzz-pollination was observed in three nectariferousBoraginaceae spp.:Onosma gigantea Lam.,Trichodesma africana (L.)R. Br. andT. boissieri Post. An evolutionary pathway from usual nectariferous flowers to typical buzz-pollinated flowers is suggested.
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    Plant systematics and evolution 169 (1990), S. 81-96 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Gramineae ; Festuceae ; Dactylis glomerata ; Enzymatic markers ; phenology ; interploid exchanges ; autopolyploidy ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phylogenetic relationships between sympatric, morphologically indistinguishable diploid and tetraploid plants ofDactylis glomerata L. (Gramineae) in Galicia (Spain) were assessed using allozyme markers for 6 distinct systems. The study exploited recent introduction in Galicia and subsequent hybridization of an alien 4xDactylis subspecies possessing distinct allozymes from those of all the native plants. Opportunities for gene exchanges between the ploidies were estimated from in situ observations of flowering, examination of progenies in 2x/4x natural and experimental crosses, and enzyme analyses. Results show a high genetic similarity between the Galician diploids and tetraploids, which possess peculiar alleles in common. Although the ploidy levels usually have distinct flowering periods, interploidal crosses do occasionally occur. Gene flow is likely much more important from the diploid to the tetraploid level. A good genetic intermixing occurs between the Galician and the alien tetraploid entities which have simultaneous flowering. Autopolyploidization of the diploids followed by various rates of hybridization is proposed as one very probable origin of natural tetraploids inDactylis.
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  • 89
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    Keywords: Angiosperms ; Asteraceae ; Inuleae ; Antennaria alborosea ; A. corymbosa ; A. marginata ; A. microphylla ; A. parvifolia ; A. rosea ; A. umbrinella ; Taxonomy ; multivariate morphometrics
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    Notes: Abstract Multivariate analysis of vegetative and reproductive characters was used to examine morphological relatedness amongAntennaria alborosea A. E. Porsild,A. corymbosa E. Nels.,A. marginata Greene,A. microphylla Rydb.,A. parvifolia Nutt.,A. rosea Greene, andA. umbrinella Rydb. Both pistillate and staminate plants were examined. Some of the characters examined were variable in one species, but stable in another (i.e., presence or absence of papillae on the achenes). Our analyses indicate that the seven species are morphologically distinct. It is hypothesized that theA. rosea agamic complex arose through hybridization amongA. corymbosa, A. microphylla, A. umbrinella, and possiblyA. dioica (L.)Gaertn. However, hybridization between the three former species and others, as well as their subsequent morphological responses to different environmental conditions causes confusion in recognizing the taxa.Antennaria angustifolia Rydb.,A. arida E. Nels.,A. confinis Greene,A. scariosa E. Nels.,A. foliacea humilis Rydb.,A. concinna E. Nels., andA. viscidula E. Nels. are considered to represent F 1 hybrids.
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    Plant systematics and evolution 170 (1990), S. 37-51 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Valerianaceae ; Transfer cells ; lignification ; lipid droplets ; oil cells ; tannins ; Development ; structure ; axial distribution ; transmission electron microscopy
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    Notes: Abstract Development, structure and the axial distribution of transfer cells and their lignification were investigated inValerianella locusta, Valeriana officinalis, andV. tuberosa (Valerianaceae). Fundamental new results are: (1) Transfer cells often contain numerous lipid droplets. Within the stem the distribution of cells containing lipid droplets correlates to that of transfer cells. (2) InValeriana officinalis persisting protuberances are frequently found on pit membranes of xylem transfer cells. Lignified transfer cells can undergo a second modification: a layer covering the secondary wall forms wall ingrowths similar to those of transfer cells. (3) Peripheral pith cells, abuting transfer cells, are able to modify into transfer cells. Cambial derivatives are only temporarily developed as transfer cells. (4) Phloem transfer cells are found in vascular bundles of the whole axis. (5) In roots, xylem transfer cells are poorly developed or absent. (6) Oil cells with oil bodies are present in the rape ofValeriana tuberosa. They are absent however in the stem of the species investigated. (7) Tannins occur in elements of the primary cortex, phloem and secondary xylem ofValeriana officinalis.
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  • 91
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    Plant systematics and evolution 169 (1990), S. 237-243 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Heliantheae ; Ambrosia ; Anther ; crystals ; pollen ; sperm cells ; tapetum
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    Topics: Biology
    Notes: Abstract Staminate flowers of giant ragweed,Ambrosia trifida L. (Asteraceae, tribeHeliantheae, subtribeAmbrosiinae) were processed into resin and sectioned 1–2 µm thick. The invasive (amoeboid) anther tapetum remains parietal until microspores are released from tetrads, then it swells and invades the locule, merging gradually into a single protoplast that flows among the microspores. After the tapetal membrane ruptures at late microspore stage, tapetal debris fills the locule, then disappears as pollen matures. Pollen becomes tricelled before anthesis. The two sperm cell nuclei are slender and wormlike. The present report supports the two generalizations that invasive tapetum and tricelled pollen are attributes of theAsteraceae.
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    Plant systematics and evolution 170 (1990), S. 205-214 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Polemoniaceae ; Pollen ; ovule ratio ; stigmatic pollen germination ; breeding systems
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    Topics: Biology
    Notes: Abstract Pollen — ovule ratios and percentages of stigmatic pollen germination (SPG) were measured for over 160 taxa of thePolemoniaceae. When related to taxa with known breeding systems, it is found that low SPGs and high P:O ratios characterize xenogamous plants, high SPGs and low P:Os characterize autogamous plants. There is a significant negative correlation between P:O ratio and SPG in the whole family as well as in certain genera. Both measures can serve as reliable indicators of the breeding systems in taxa of thePolemoniaceae and can be measured in dried or living specimens. Accordingly, most polemons feature “mixed” breeding system, i.e. facultative xenogamy or facultative autogamy. Xenogamy is common among the tropical genera and in theLeptodactylon, Phlox andPolemonium. Autogamy is more frequent in the tribeGilieae (particularly inGilia) than in the other tribes. Annual taxa tend to be autogamous, showing on the average higher SPG and lower P:O ratio. The lepidopteran-pollinated group of species have a higher mean P:O ratio and lower mean SPG thus indicating that such plants are associated with crosspollination more than the others.
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  • 93
    ISSN: 1615-6110
    Keywords: Angiosperms ; Compositae ; Eupatorium ; Chromosomal distance ; chromosomal identity ; karyotype analysis ; statistics phenetics
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    Notes: Abstract Somatic metaphase karyotypes were analyzed for 22 diploid species ofEupatorium. The karyotypic comparisons were made using two indices: minimal chromosomal distance (MCD), measuring overall dissimilarities, and chromosomal identity (CI), measuring number of morphologically identical chromosomes between species. The resulting phenograms from these indices are largely compatible. The 22 species cluster into four groups in the phenogram using MCD, and the grouping corresponds well with morphology or geographic distribution into the three N. American groupsEutrochium, Uncasia, Traganthes, and the E. Asian group. These results suggest that karyotypes in perennialEupatorium have been considerably conservative and changed not through large chromosomal mutations but through small chromosomal mutations gradually fixed.
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  • 94
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    Keywords: Angiosperms ; Scrophulariaceae ; Striga hermonthica ; Hemiparasitism ; hostspecificity ; enzyme electrophoresis ; genetic diversity ; Flora of Burkina Faso ; Sudan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Striga hermonthica is a root hemiparasite that attacks onlyGramineae, includingSorghum and millet for which it is a principal cause of lowered yield. Enzyme electrophoresis was used to investigate genetic diversity inStriga hermonthica and to determine the level of differentiation between host-specialized populations. Nine genetic loci coding eight enzymes were interpreted and data obtained from three populations: oneSorghum-adapted population from Sudan and two populations from Burkina Faso, oneSorghum-adapted and the other millet-adapted. Levels of polymorphism were similarly high in all three populations (P=0.625, A=2.6−2.8, H=0.293−0.401). Genotypic frequencies at most loci conformed to Hardy-Weinberg expectations in each population, consistent with outcrossing as predicted from previous studies of floral biology. Occasional heterozygote deficiencies were probably the result of Wahlund effect. The mean value of FST over the three populations was 0.068, indicating a slight to moderate level of genetic differentiation among the populations. The two Burkina Faso populations were more closely related (S=0.940, D=0.006) than either was to the Sudan population, suggesting that geographic separation is more important than host specialization in contributing to population differentiation. TheSorghum-adapted population was slightly closer to the Burkina FasoSorghum-adapted population (S=0.873, D=0.047) than to Burkina Faso millet-adapted population (S=0.851, D=0.074). The absence of substantial genetic divergence between host-specific populations ofStriga could result either from recent evolution of host-specialized strains or from strong selection for physiological specialization in the face of substantial gene flow between the populations.
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    Plant systematics and evolution 178 (1991), S. 195-223 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Podostemaceae ; Tristichoideae ; Indotristicha ramosissima ; Rheophytes ; water plants ; life history ; development ; root-shoot model ; leaf-stem intermediates ; phyllotaxis ; flower structure ; systematics
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    Notes: Abstract The developmental morphology ofIndotristicha ramosissima, a submerged rheophyte from South India, is described. Besides creeping organs (called roots) there are branched shoots with two kinds of short-lived photosynthetic appendages: scales and compound structures (called ramuli). These ramuli may be interpreted as leaf-stem intermediates because they combine typical leaf characters (extra-axillary position, determinate growth, subtending an axillary bud) and typical stem characters (nearly radial symmetry, acropetal development with apical meristem, arrangement of the scaly subunits helical or irregular). Floral shoots arise from axillary exogenous buds along the vegetative shoots, occasionally also from endogenous buds along the roots and vegetative shoots. The uppermost scales and ramuli of each floral shoot form a cup-like structure around the base of the terminal flower.Indotristicha is thought to be primitive within theTristichoideae (Podostemaceae). Some morphogenetic switches are postulated in order to deriveIndotristicha from a putative ancestor that still showed the classical root-shoot model typical of most angiosperms.
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    Plant systematics and evolution 178 (1991), S. 225-233 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Gramineae ; Eleusine ; DNA amount ; intra- and interspecific variation ; karyotypes ; hybridisation ; polyploidy ; domestication ; evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 2C nuclear DNA amounts were determined in 30 collections belonging to 10 species ofEleusine. About a 2.5-fold variation in genome size is evident in the genus. The 2C DNA amount in the diploid species ranged from 2.50 pg inE. verticillata to 3.35 pg inE. intermedia. In contrast, the tetraploid species showed a range from 4.95 pg inE. africana to 6.13 pg inE. floccifolia. At intraspecific level 10 collections ofE. coracana, 6 ofE. indica, 4 ofE. africana, 2 ofE. tristachya, and 2 ofE. kigeziensis did not show any significant variation. However, 2 collections ofE. floccifolia, connected with polyploidy, displayed about 90% variation. Polyploid species showed approximately double the genome size of that of their corresponding diploids. An evolutionary increase in DNA amount is evident inE. coracana during the course of its origin and domestication fromE. africana.
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    Plant systematics and evolution 178 (1991), S. 235-245 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Orchidaceae ; Ophrys ; Orchis ; Anacamptis ; Polyploidy ; aneuploidy ; karyology ; systematics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Studies on chromosome numbers and karyotypes in Orchid taxa from Apulia (Italy) revealed triploid complements inOphrys tenthredinifera andOrchis italica. InO. tenthredinifera there is no significant difference between the diploid and the triploid karyotypes. The tetraploid cytotype ofAnacamptis pyramidalis forms 36 bivalents during metaphase I in embryo sac mother cells. Aneuploidy was noticed inOphrys bertolonii ×O. tarentina with chromosome numbers n = 19 and 2n = 38. There were diploid (2n = 2x = 36), tetraploid (2n = 4x = 72), hexaploid (2n = 6x = 108) and octoploid (2n = 8x = 144) cells in the ovary wall of the diploid hybridOphrys apulica ×O. bombyliflora. Evolutionary trends inOphrys andOrchis chromosomes are discussed.
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    Plant systematics and evolution 179 (1992), S. 1-18 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Asteraceae ; Centaurea ; Acrocentron ; Karyology ; biogeography
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    Topics: Biology
    Notes: Abstract The karyology ofCentaurea sect.Acrocentron is surveyed. 19 chromosome counts on 8 species are reported; those onC. acaulis, C. crocata, C. galianoi, C. pubescens, andC. malinvaldiana are new. The basic chromosome numbers of the section are x = 11 and x = 10. Karyological arguments have been used to show that evolution was from x = 11 to x = 10. This is supported by biogeographical data. Two main centres of diversification of sect.Acrocentron were studied from that point of view: the East and the Southwest Mediterranean region.
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    Plant systematics and evolution 198 (1995), S. 235-252 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Pollen ; pollen colour ; pollen signal ; spectral reflection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The spectral reflection of pollen in 67 plant species out of 28 families was measured by means of mass recording of pollen grains. Various types of spectral reflection curves were found, but 75% belonged to two categories: 1. Human-yellow pollen with strong reflection in the green and red, and low reflection in the ultraviolet and blue range of wavelengths. 2. Human-whitish pollen with strong reflection in the green and red and additional reflection of shorter wavelengths. It is shown that it is important to have information about the mode of the visual pollen display — crypsis or colour contrast against the corolla, pollen advertisement, or concealment — and the visual capabilities of the presumed pollinators in order to be able to discuss the signalling function of pollen colours.
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    Plant systematics and evolution 199 (1996), S. 121-152 
    ISSN: 1615-6110
    Keywords: Angiosperms ; Leaf development ; organismal approach ; blastozone ; organogenetic competence ; primary morphogenesis ; marginal meristems ; topography ; eumeristem ; cytohistological gradients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A new term — the “blastozone” — is proposed to designate regions of the shoot competent for organogenesis. It is argued that the notion of “marginal meristems” is based on the cell theory and thus may not be appropriate to elucidate the process of organ formation. For instance, with respect to the occurrence of initials and of an elevated cell division rate marginal meristems have been shown to be doubtful structures. Furthermore, organogenetic competent regions form only parts of the meristems of the shoot. The study of blastozones from an organismic perspective reveals primary morphogenetic events such as initiation, incorporation, and fusion processes. Loss of morphogenetic competence is associated with histogenetic events, e.g., trichome outgrowth, and indicates the onset of processes leading to maturation. The marginal blastozone of the leaf is then used up although meristem features continue to be expressed. A series of SEM studies in several genera exemplifies the proposed viewpoint, demonstrating some of the morphogenetic potentialities of angiosperm leaf marginal blastozones.
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