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  • Artikel  (124)
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  • 1
    Digitale Medien
    Digitale Medien
    The RecA protein as a model molecule for molecular systematic studies of bacteria: Comparison of trees of RecAs and 16S rRNAs from the same species (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1105-1123 
    Details
    ISSN: 1432-1432
    Schlagwort(e): RecA ; Small-subunit rRNA ; Bacteria ; Molecular evolution ; Molecular systematics ; Congruence ; Protein ; Phylogeny ; Gram-positive ; Proteobacteria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The evolution of the RecA protein was analyzed using molecular phylogenetic techniques. Phylogenetic trees of all currently available complete RecA proteins were inferred using multiple maximum parsimony and distance matrix methods. Comparison and analysis of the trees reveal that the inferred relationships among these proteins are highly robust. The RecA trees show consistent subdivisions corresponding to many of the major bacterial groups found in trees of other molecules including the α, β, γ, δ, ε proteobacteria, cyanobacteria, high-GC gram-positives, and the Deinococcus-Thermus group. However, there are interesting differences between the RecA trees and these other trees. For example, in all the RecA trees the proteins from gram-positive species are not monophyletic. In addition, the RecAs of the cyanobacteria consistently group with those of the high-GC gram-positives. To evaluate possible causes and implications of these and other differences phylogenetic trees were generated for small-subunit rRNA sequences from the same (or closely related) species as represented in the RecA analysis. The trees of the two molecules using these equivalent species-sets are highly congruent and have similar resolving power for close, medium, and deep branches in the history of bacteria. The implications of the particular similarities and differences between the trees are discussed. Some of the features that make RecA useful for molecular systematics and for studies of protein evolution are also discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173192
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  • 2
    Digitale Medien
    Digitale Medien
    Phylogeny of African monkeys based upon mitochondrial 12S rRNA sequences (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 173-180 
    Details
    ISSN: 1432-1432
    Schlagwort(e): African monkeys ; mtDNA ; 12S rRNA gene ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The suborder Anthropoidea of the primates has traditionally been divided in three superfamilies: the Hominoidea (apes and humans) and the Cercopithecoidea (Old World monkeys), together comprising the infraorder Catarrhini, and the Ceboidea (New World monkeys) belonging to the infraorder Platyrrhini. We have sequenced an approximately 390-base-pair part of the mitochondrial 12S rRNA gene for 26 species of the major groups of African monkeys and apes and constructed an extensive phylogeny based upon DNA evidence. Not only is this phylogeny of great importance in classification of African guenons, but it also suggests rearrangements in traditional monkey taxonomy and evolution. Baboons and mandrills were found to be not directly related, while we could confirm that the known four superspecies of mangabeys do not form a monophyletic group, but should be separated into two genera, one clustering with baboons and the other with mandrills. Patas monkeys are clearly related to members of the genus Cercopithecus despite their divergence in build and habitat, while the talapoin falls outside the Cercopithecus clade (including the patas monkey).
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00167111
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  • 3
    Digitale Medien
    Digitale Medien
    The evolutionary relationships of two families of cottoid fishes of Lake Baikal (East Siberia) as suggested by analysis of mitochondrial DNA (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 392-399 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Mitochondrial DNA ; Sequencing ; Phylogeny ; Cottoid fishes ; Baikal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Fragments of mtDNA genes Cyt B, ATPase 6, and ATPase 8 of six cottoid fishes species of Lake Baikal (East Siberia) were amplified and sequenced. In addition mtDNAs of the same fish were subjected to restriction analysis. The data obtained were used to construct phylogenetic trees. The topology of the ATPase tree differs from those of the Res (restriction) and Cyt B trees. Clustering of species within the trees confirms the viewpoint of Taliev (1955, Baicalian Sculpins (Cottoidei)) according to which Baikalian cottoids originate from two ancestral forms. The times of branching obtained do not confirm the existing viewpoint according to which the two golomyankas (Comephorus baicalensis and Comephorus dybowskii) are pre-Baikal (Myocene) relicts: these two species may have originated 1.2–1.8 million years ago in Baikal, and they seem to represent an example of rapid morphological evolution which resulted in the formation of a new family.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00164025
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  • 4
    Digitale Medien
    Digitale Medien
    The molecular cloning of a phospholipase A2 from Bothrops jararacussu snake venom: Evolution of venom group II phospholipase A2's may imply gene duplications (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 174-179 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Snake venom ; Bothrops ; Phospholipase ; Myotoxin ; Evolution ; cDNA ; Gene duplication ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The sequence coding for a snake venom phospholipase A2 (PLA2), BJUPLA2, has been cloned from a Bothrops jararacussu venom gland cDNA library. The cDNA sequence predicts a precursor containing a 16-residue signal peptide followed by a molecule of 122 amino acid residues with a strong sequence similarity to group II snake venom PLA2's. A striking feature of the cDNA is the high sequence conservation of the 5′ and 3′ untranslated regions in cDNAs coding for PLA2's from a number of viper species. The greatest sequence variation was observed between the regions coding for the mature proteins, with most substitutions occurring in nonsynonymous sites. The phylogenetic tree constructed by alignment of the amino acid sequence of BJUPLA2 with group II PLA2's in general groups them according to current taxonomical divisions and/or functional activity. It also suggests that gene duplications may have occurred at a number of different points during the evolution of snake venom group II PLA2's.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00170670
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  • 5
    Digitale Medien
    Digitale Medien
    Gorilla and orangutan c-myc nucleotide sequences: Inference on hominoid phylogeny (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 262-276 
    Details
    ISSN: 1432-1432
    Schlagwort(e): DNA sequencing ; c-myc ; Primates ; Phylogeny ; Gorilla ; Orangutan
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nucleotide sequences of the gorilla and orangutan mycloci have been determined by the dideoxy nucleotide method. As previously observed in the human and chimpanzee sequences, an open reading frame (ORF) of 188 codons overlapping exon 1 could be deduced from the gorilla sequence. However, no such ORF appeared in the orangutan sequence. The two sequences were aligned with those of human and chimpanzee as hominoids and of gibbon and marmoset as outgroups of hominoids. The branching order in the evolution of primates was inferred from these data by different methods: maximum parsimony and neighborjoining. Our results support the view that the gorilla lineage branched off before the human and chimpanzee diverged and strengthen the hypothesis that chimpanzee and gorilla are more related to human than is orangutan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01215173
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  • 6
    Digitale Medien
    Digitale Medien
    Arrangement and nucleotide sequence of the gene (fus) encoding elongation factor G (EF-G) from the hyperthermophilic bacterium Aquifex pyrophilus: Phylogenetic depth of hyperthermophilic bacteria inferred from analysis of the EF-G/fus sequences (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 803-812 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Bacterial rooting ; Hyperthermophily ; Elongation factors ; Phylogeny ; pdxJ gene ; Cyanobacteria-chloroplasts ; Streptomycin operon ; Codon position inequality
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The gene fus (for EF-G) of the hyperthermophilic bacterium Aquifex pyrophilus was cloned and sequenced. Unlike the other bacteria, which display the streptomycin-operon arrangement of EF genes (5′-rps12-rps7 fus-tuf-3′), the Aquifex fus gene (700 codons) is not preceded by the two small ribosomal subunit genes although it is still followed by a tuf gene (for EF-Tu). The opposite strand upstream from the EF-G coding locus revealed an open reading frame (ORF) encoding a polypeptide having 52.5% identity with an E. coli protein (the pdxJ gene product) involved in pyridoxine condensation. The Aquifex EF-G was aligned with available homologs representative of Deinococci, high G + C Gram positives, Proteobacteria, cyanobacteria, and several Archaea. Outgroup-rooted phylogenies were constructed from both the amino acid and the DNA sequences using first and second codon positions in the alignments except sites containing synonymous changes. Both datasets and alternative tree-making methods gave a consistent topology, with Aquifex and Thermotoga maritima (a hyperthermophile) as the first and the second deepest offshoots, respectively. However, the robustness of the inferred phylogenies is not impressive. The branching of Aquifex more deeply than Thennotoga and the branching of Thermotoga more deeply than the other taxa examined are given at bootstrap values between 65 and 70% in the fus-based phylogenies, while the EF-G(2)-based phylogenies do not provide a statistically significant level of support (⩽ 50% bootstrap confirmation) for the emergence of Thermotoga between Aquifex and the successive offshoot (Thermus genus). At present, therefore, the placement of Aquifex at the root of the bacterial tree, albeit reproducible, can be asserted only with reservation, while the emergence of Thermotoga between the Aquificales and the Deinococci remains (statistically) indeterminate.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173160
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  • 7
    Digitale Medien
    Digitale Medien
    The Giardia lamblia actin gene and the phylogeny of eukaryotes (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 841-849 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Actin genes ; Giardia lamblia ; GC-content ; Phylogeny ; Slime molds ; Relative rate test
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The single-copy actin gene of Giardia lamblia lacks introns; it has an average of 58% amino acid identity with the actin of other species; and 49 of its amino acids can be aligned with the amino acids of a consensus sequence of heat shock protein 70. Analysis of the potential RNA secondary structure in the transcribed region of the G. lamblia actin gene and of the single-copy actin gene of nine other species did not reveal any conserved structures. The G. lamblia actin sequence was used to root the phylogenetic trees based on 65 actin protein sequences from 43 species. This tree is congruent with small-subunit rRNA trees in that it shows that oomycetes are not related to higher fungi; that kinetoplatid protozoans, green plants, fungi and animals are monophyletic groups; and that the animal and fungal lineages share a more recent common ancestor than either does with the plant lineage. In contrast to smalls-ubunit rRNA trees, this tree shows that slime molds diverged after the plant lineage. The slower rate of evolution of actin genes of slime molds relative to those of plants, fungi, and animals species might be responsible for this incongruent branching.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173163
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  • 8
    Digitale Medien
    Digitale Medien
    Evolutionary relationships of the carbamoylphosphate synthetase genes (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 813-832 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Phylogeny ; Evolution ; Carbamoylphosphate synthetase ; Dihydroorotase ; Aspartate transcarbamoylase ; Intron ; Exon ; Arginine biosynthesis ; Pyrimidine biosynthesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Carbamoylphosphate is a common intermediate in the metabolic pathways leading to the biosynthesis of arginine and pyrimidines. The amino acid sequences of all available proteins that catalyze the formation of carbamoylphosphate were retrieved from Genbank and aligned to estimate their mutual phylogenetic relations. In gram-negative bacteria carbamoylphosphate is synthesized by a two-subunit enzyme with glutamiriase and carbamoylphosphate synthetase (CPS) activity, respectively. In gram-positive bacteria and lower eukaryotes this two-subunit CPS has become dedicated to arginine biosynthesis, while in higher eukaryotes the two subunits fused and subsequently lost the glutaminase activity. The CPS dedicated to pyrimidine synthesis is part of a multifunctional enzyme (CPS II), encoding in addition dihydroorotase and aspartate transcarbamoylase. Evidence is presented to strengthen the hypothesis that the two “kinas” subdomains of all CPS isozymes arose from a duplication of an ancestral gene in the progenote. A further duplication of the entire CPS gene occurred after the divergence of the plants and before the divergence of the fungi from the eukaryotec root, generating the two isoenzymes involved in either the synthesis of arginine or that of pyrimidines. The mutation rate was found to be five- to tenfold higher after the duplication than before, probably reflecting optimization of the enzymes for their newly acquired specialized function. We hypothesize that this duplication arose from a need for metabolic channeling for pyrimidine biosynthesis as it was accompanied by the tagging of the CPS gene with the genes for dihydroorotase and aspartate transcarbamoylase, and as the duplication occurred independently also in gram-positive bacteria. Analysis of the exon-intron organization of the two “kinase” subdomains in CPS I and II suggests that ancient exons may have comprised approx. 19 amino acids, in accordance with the prediction of the “intron-early” theory.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173161
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  • 9
    Digitale Medien
    Digitale Medien
    Molecular evolution of the hepatitis B virus genome (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 587-596 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Nucleotide substitution ; Models ; Maximum likelihood ; Rate heterogeneity at sites ; Phylogeny ; Molecular clock ; Hepatitis B virus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The hepatitis B virus (HBV) has a circular DNA genome of about 3,200 base pairs. Economical use of the genome with overlapping reading frames may have led to severe constraints on nucleotide substitutions along the genome and to highly variable rates of substitution among nucleotide sites. Nucleotide sequences from 13 complete HBV genomes were compared to examine such variability of substitution rates among sites and to examine the phylogenetic relationships among the HBV variants. The maximum likelihood method was employed to fit models of DNA sequence evolution that can account for the complexity of the pattern of nucleotide substitution. Comparison of the models suggests that the rates of substitution are different in different genes and codon positions; for example, the third codon position changes at a rate over ten times higher than the second position. Furthermore, substantial variation of substitution rates was detected even after the effects of genes and codon positions were corrected; that is, rates are different at different sites of the same gene or at the same codon position. Such rates after the correction were also found to be positively correlated at adjacent sites, which indicated the existence of conserved and variable domains in the proteins encoded by the viral genome. A multiparameter model validates the earlier finding that the variation in nucleotide conservation is not random around the HBV genome. The test for the existence of a molecular clock suggests that substitution rates are more or less constant among lineages. The phylogenetic relationships among the viral variants were examined. Although the data do not seem to contain sufficient information to resolve the details of the phylogeny, it appears quite certain that the serotypes of the viral variants do not reflect their genetic relatedness.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175817
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  • 10
    Digitale Medien
    Digitale Medien
    Phylogenetic Analysis of the Aminoacyl-tRNA synthetases (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 487-498 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Aminoacyl-tRNA synthetases ; Phylogeny ; Evolution of protein translation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Numerous aminoacyl-tRNA synthetase sequences have been aligned by computer and phylogenetic trees constructed from them for the two classes of these enzymes. Branching orders based on a consensus of these trees have been proposed for the two groups. Although the order of appearance can be rationalized to fit many different scenarios having to do with the genetic code, the invention of a system for translating nucleic acid sequences into polypeptide chains must have predated the existence of these proteins. In the past, a variety of schemes has been proposed for matching amino acids and tRNAs. Most of these have invoked direct recognition of one by the other, whether or not the anticodon was involved. Often ignored is the possibility of a nonprotein (presumably RNA) matchmaker for bringing the two into conjunction. If such had been the case, then the contemporary aminoacyl-tRNA synthetases could have entered the system gradually, each specific type replacing its matchmaking RNA counterpart in turn. A simple displacement scheme of this sort accommodates the existence of two different families of these enzymes, the second being introduced well before the first had undergone sufficient genetic duplications to specify the full gamut of amino acids. Such a scheme is also consistent with similar amino acids often, but not always, being the substrates of enzymes with the most similar amino acid sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166617
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  • 11
    Digitale Medien
    Digitale Medien
    Evaluation of several methods for estimating phylogenetic trees when substitution rates differ over nucleotide sites (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 689-697 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Phylogeny ; Maximum likelihood ; Least squares ; Consistency ; Sampling error ; Rate variation at sites ; Gamma distribution ; Computer simulation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Several maximum likelihood and distance matrix methods for estimating phylogenetic trees from homologous DNA sequences were compared when substitution rates at sites were assumed to follow a gamma distribution. Computer simulations were performed to estimate the probabilities that various tree estimation methods recover the true tree topology. The case of four species was considered, and a few combinations of parameters were examined. Attention was applied to discriminating among different sources of error in tree reconstruction, i.e., the inconsistency of the tree estimation method, the sampling error in the estimated tree due to limited sequence length, and the sampling error in the estimated probability due to the number of simulations being limited. Compared to the least squares method based on pairwise distance estimates, the joint likelihood analysis is found to be more robust when rate variation over sites is present but ignored and an assumption is thus violated. With limited data, the likelihood method has a much higher probability of recovering the true tree and is therefore more efficient than the least squares method. The concept of statistical consistency of a tree estimation method and its implications were explored, and it is suggested that, while the efficiency (or sampling error) of a tree estimation method is a very important property, statistical consistency of the method over a wide range of, if not all, parameter values is prerequisite.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00160518
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  • 12
    Digitale Medien
    Digitale Medien
    A method for determining the position and size of optimal sequence regions for phylogenetic analysis (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 1128-1138 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Phylogeny ; Neighbor joining method ; Bootstrap ; Optimal size ; Optimal position ; Nonrandom sequence ; Information ; Foot-and-mouth disease virus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The availability of fast and accurate sequencing procedures along with the use of PCR has led to a proliferation of studies of variability at the molecular level in populations. Nevertheless, it is often impractical to examine long genomic stretches and a large number of individuals at the same time. In order to optimize this kind of study, we suggest a heuristic procedure for detection of the shortest region whose informational content can be considered sufficient for significant phylogenetic reconstruction. The method is based on the comparison of the pairwise genetic distances obtained from a set of sequences of reference to those obtained for different windows of variable size and position by means of a simple index. We also present an approach for testing whether the informative content in the stretches selected in this way is significantly different from the corresponding content shown by the larger genomic regions used as reference. Application of this test to the analysis of the VP1 protein gene of foot-and-mouth-disease type C virus allowed us to define optimal stretches whose informative content is not significantly different from that displayed by the complete VP1 sequence. We showed that the predictions made for type C sequences are valid for type O sequences, indicating that the results of the procedure are consistent.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173194
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  • 13
    Digitale Medien
    Digitale Medien
    Molecular phylogeny of gibbons inferred from mitochondrial DNA sequences: Preliminary report (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 359-365 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Gibbons ; Mitochondrial DNA ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We analyzed the 896 base-pair (bp) mitochondrial DNA (mtDNA) sequences for seven gibbons, representative of three out of four subgenera. The result from our molecular analysis is consistent with previous studies as to the monophyly of subgenusHylobates species, yet the relationship among subgenera remains slightly ambiguous. A striking result of the analysis is the phylogenetic location of Kloss's gibbon (H. klossii). Kloss's gibbon has been considered to be an initial off-shoot of the subgenusHylobates because of its morphological primitiveness. However, our molecular data strongly suggest that Kloss's gibbon speciated most recently within the subgenusHylobates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01215183
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  • 14
    Digitale Medien
    Digitale Medien
    Molecular evolution of group II phospholipases A2 (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 867-877 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Group II phospholipase A2 ; cDNA ; Phylogeny ; Snake venom ; Accelerated evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nucleotide sequences of 13 cDNAs encoding group II phospholipases A2 (PLA2 S), which are from viperidae snake venoms and from mammalian sources, were aligned and analyzed by phylogenetic trees constructed using various components of the sequences. The evolutionary trees derived from the combined sequences of the untranslated (5′ and 3′) region and the signal peptide region of cDNAs were in accord with the consequences from taxonomy. In contrast, the evolutionary trees from the mature protein-coding region sequences of cDNAs and from the amino acid sequences showed random patterns. These observations indicated that the mature protein-coding region has evolved through a process differently from the untranslated and signal peptide regions. The trees built from the nucleotide differences at each of three positions of codons in the mature protein-coding region suggested that snakevenom-gland PLA2 genes have evolved via a process different from mammalian PLA2 genes. The occurrence of accelerated evolution has been recently discovered in Trimeresurus flavoviridis venom-gland group II PLA2 isozyme genes (Nakashima et al. 1993, Proc Natl Acad Sci USA 90:5964–5968), so the present phylogenetic analysis together with the estimation of nucleotide divergence of cDNAs provides further evidence that snakevenom-group II PLA2 isozyme genes have evolved by accelerated evolution to gain diverse physiological activities.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00173166
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  • 15
    Digitale Medien
    Digitale Medien
    Revised dinoflagellate phylogeny inferred from molecular analysis of large-subunit ribosomal RNA gene sequences (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 637-645 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Dinoflagellate ; Phylogeny ; Large-subunit rRNA ; PCR ; Alexandrium spp ; Prorocentrum spp ; Gymnodinium spp
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nucleotide sequence analysis of the PCR products corresponding to the variable large-subunit rRNA domains D1, D2, D9, and D10 from ten representative dinoflagellate species is reported. Species were selected among the main laboratory-grown dinoflagellate groups: Prorocentrales, Gymnodiniales, and Peridiniales which comprise a variety of morphological and ecological characteristics. The sequence alignments comprising up to 1,000 nucleotides from all ten species were employed to analyze the phylogenetic relationships among these dinoflagellates. Maximum parsimony and neighbor joining trees were inferred from the data generated and subsequently tested by bootstrapping. Both the D1/D2 and the D9/D10 regions led to coherent trees in which the main class of dinoflagellates, Dinophyceae, is divided in three groups: prorocentroid, gymnodinioid, and peridinioid. An interesting outcome from the molecular phylogeny obtained was the uncertain emergence of Prorocentrum lima. The molecular results reported agreed with morphological classifications within Peridiniales but not with those of Prorocentrales and Gymnodiniales. Additionally, the sequence comparison analysis provided strong evidence to suggest that Alexandrium minutum and Alexandrium lusitanicum were synonymous species given the identical sequence they shared. Moreover, clone Gg1V, which was determined Gymnodinium catenatum based on morphological criteria, would correspond to a new species of the genus Gymnodinium as its sequence clearly differed from that obtained in G. catenatum. The sequence of the amplified fragments was demonstrated to be a valuable tool for phylogenetic and taxonomical analysis among these highly diversified species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175822
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  • 16
    Digitale Medien
    Digitale Medien
    Molecular phylogeny of Allomyces macrogynus: Congruency between nuclear ribosomal RNA- and mitochondrial protein-based trees (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 657-665 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Ribosomal RNA ; Protein ; Phylogeny ; Mitochondria ; Nuclear ; Lower fungi
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have sequenced the nuclear and mitochondrial small subunit rRNA genes (rns) and the mitochondrial genes coding for subunits 1 and 3 of the cytochrome oxidase (cox1 and cox3, respectively) of the chytridiomycete Allomyces macrogynus. Phylogenetic trees inferred from the derived COX1 and COX3 proteins and the nuclear rns sequences show with good bootstrap support that A. macrogynus is an early diverging fungus. The trees inferred from mitochondrial rns sequences do not yield a topology that is supported by bootstrap analysis. The similarity and the relative robustness of the nuclear rns and the mitochondrial protein-derived phylogenetic trees suggest that protein sequences are of higher value than rRNA sequences for reconstructing mitochondrial evolution. In addition, our trees support a monophyletic origin of mitochondria for the range of analyzed eukaryotes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00175824
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  • 17
    Digitale Medien
    Digitale Medien
    Evolutionary analysis of the picornavirus family (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 362-371 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Picornavirus ; Phylogeny ; Neighborjoining method ; Least-squares method ; Bootstrap ; Variance of branch length ; Statistical geometry in distance space ; Split decomposition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An exhaustive evolutionary analysis of the picornavirus family has been carried out using the amino acid sequences of several proteins of the viruses including: the capsid proteins (1D, 1B, and 1C) situated at the 5′ end of the genome and responsible for the serotype of the viruses, and the viral polymerase (3D), located at the 3′ end of the genome. The evolutionary relationships found among the viruses studied support the new classification, recently suggested, in contrast to the classical one, and the existence of a new genus for the picornavirus family. In the new taxonomic organization, five genera form the picornavirus family: (1) aphthoviruses, (2) cardioviruses, (3) hepatoviruses (previously classified as enteroviruses), (4) renteroviruses (which mainly constitute a combination of the previous genera rhinovirus and enterovirus), and (5) a new genus, with a new and unique representative: the echovirus 22. Our analysis also allowed us, for the first time, to propose the most probable sequence of speciation events to have given rise to the current picornavirus family. The bootstrap procedure was used to check the reliability of the phylogenetic trees obtained. The application of the method of the statistical geometry in distance space to internal branches of the tree revealed a high degree of evolutionary “noise,” which makes the resolution of some internal branching points difficult.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00164022
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  • 18
    Digitale Medien
    Digitale Medien
    Evolution of the fibropellin gene family and patterns of fibropellin gene expression in sea urchin phylogeny (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 34-45 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Sea urchins ; Phylogeny ; Fibropellins ; Gene evolution ; Evolution of direct development
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This study documents evolutionary modifications in the expression patterns of the sea urchin EGF I and EGF III genes, which encode a family of extracellular matrix proteins, the fibropellins. We show that the sea urchin apical lamina, a macromolecular extracellular matrix that surrounds the sea urchin embryo and is made up of the fibropellins, has been conserved through at least 250 million years of echinoid evolution. The contribution of different fibropellin family members to this structure has, however, changed over the course of sea urchin phylogeny, and between two congeneric species that exhibit different developmental modes. Mapping the evolutionary history of the EGF genes on a cladogram of relationships among sea urchins reveals that EGF I is present in all echinoids examined, while EGF III appears to have arisen by duplication and divergence from EGF I during the radiation of a suborder of the camarodont sea urchins some 35–45 million years ago. Alterations in the temporal expression patterns of these genes as well as the loss of one of the two EGF I transcripts and encoded protein are coincident with the evolution of a direct-developing larval form in Heliocidaris erythrogramma. H. erythrogramma and its congener Heliocidaris tuberculata, which develops via a typical echinopluteus larva, shared a common ancestor about 10 million years ago. The differences in fibropellin representation within the apical lamina of the various taxa indicate that a homologous embryonic structure can undergo substantial changes in composition during its evolutionary history.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174039
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  • 19
    Digitale Medien
    Digitale Medien
    The origin of land plants: Phylogenetic relationships among charophytes, bryophytes, and vascular plants inferred from complete small-subunit ribosomal RNA gene sequences (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 74-84 
    Details
    ISSN: 1432-1432
    Schlagwort(e): 18S rRNA ; Sequence analysis ; Phylogeny ; Molecular clock ; Chlorophyceae ; Charophyceae ; Prasinophyceae ; Bryophyta ; Selaginella
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Complete nuclear-encoded small-subunit 18S rRNA (=SSU rRNA) gene sequences were determined for the prasinophyte green alga Mantoniella squamata; the charophycean green algae Chara foetida, Coleochaete scutata, Klebsormidium flaccidum, and Mougeotia scalaris; the bryophytes Marchantia polymorpha, Fossombronia pusilla, and Funaria hygrometrica; and the lycopod Selaginella galleottii to get a better insight into the sequential evolution from green algae to land plants. The sequences were aligned with several previously published SSU rRNA sequences from chlorophytic and charophytic algae as well as from land plants to infer the evolutionary relationships for major evolutionary lineages within the Chlorobionta by distance matrix, maximum parsimony, and maximum likelihood analyses. Phylogenetic trees created by the different methods consistently placed the Charophyceae on the branch leading to the land plants. The Charophyceae were shown to be polyphyletic with the Charales (“charalean” algae) diverging earlier than the Coleochaetales, Klebsormidiales, Chlorokybales, and Zygnematales (“charophycean” algae) which branch from a point closer to the land plants in most analyses. Maximum parsimony and maximum likelihood analyses imply a successive evolution from “charophycean” algae, particularly Coleochaetales, to bryophytes, lycopods, and seed plants. In contrast, distance matrix methods group the bryophytes together with the “charophycean” algae, suggesting a separate evolution of these organisms compared with the club moss and the seed plants.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00174043
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  • 20
    Digitale Medien
    Digitale Medien
    Analyses of ribosomal RNA sequences from glaucocystophyte cyanelles provide new insights into the evolutionary relationships of plastids (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 203-210 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Cyanelles ; Cyanophora paradoxa ; Endosymbiosis ; Evolution ; Glaucocystophyta ; Glaucophyta ; Phylogeny ; Plastid ; 16S ribosomal RNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Glaucocystophyte algae (sensu Kies, Berl. Deutsch. Bot. Ges. 92, 1979) contain plastids (cyanelles) that retain the peptidoglycan wall of the putative cyanobacterial endosymbiont; this and other ultrastructural characters (e.g., unstacked thylakoids, phycobilisomes) have suggested that cyanelles are “primitive” plastids that may represent undeveloped associations between heterotrophic “host” cells (i.e., glaucocystophytes) and cyanobacteria. To test the monophyly of glaucocystophyte cyanelles and to determine their evolutionary relationship to other plastids, complete 16S ribosomal RNA sequences were determined for Cyanophora paradoxa, Glaucocystis nostochinearum, Glaucosphaera vacuolata, and Gloeochaete wittrockiana. Plastid rRNAs were analyzed with the maximum-likelihood, maximumparsimony, and neighbor joining methods. The phylogenetic analyses show that the cyanelles of C. paradoxa, G. nostochinearum, and G. wittrockiana form a distinct evolutionary lineage; these cyanelles presumably share a monophyletic origin. The rDNA sequence of G. vacuolata was positioned within the nongreen plastid lineage. This result is consistent with analyses of nuclear-encoded rRNAs that identify G. vacuolata as a rhodophyte and support its removal from the Glaucocystophyta. Results of a global search with the maximumlikelihood method suggest that cyanelles are the first divergence among all plastids; this result is consistent with a single loss of the peptidoglycan wall in plastids after the divergence of the cyanelles. User-defined tree analyses with the maximum-likelihood method indicate, however, that the position of the cyanelles is not stable within the rRNA phylogenies. Both maximumparsimony and neighbor-joining analyses showed a close evolutionary relationship between cyanelles and nongreen plastids; these phylogenetic methods were sensitive to inclusion/exclusion of the G. wittrockiana cyanelle sequence. Base compositional bias within the G. wittrockiana 16S rRNA may explain this result. Taken together the phylogenetic analyses are interpreted as supporting a near-simultaneous radiation of cyanelles and green and nongreen plastids; these organelles are all rooted within the cyanobacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00170674
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  • 21
    Digitale Medien
    Digitale Medien
    Gorilla and orangutan c-myc nucleotide sequences: Inference on hominoid phylogeny (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 262-276 
    Details
    ISSN: 1432-1432
    Schlagwort(e): DNA sequencing ; c-myc ; Primates ; Phylogeny ; Gorilla ; Orangutan
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The nucleotide sequences of the gorilla and orangutan myc loci have been determined by the dideoxy nucleotide method. As previously observed in the human and chimpanzee sequences, an open reading frame (ORF) of 188 codons overlapping exon 1 could be deduced from the gorilla sequence. However, no such ORF appeared in the orangutan sequence. The two sequences were aligned with those of human and chimpanzee as hominoids and of gibbon and marmoset as outgroups of hominoids. The branching order in the evolution of primates was inferred from these data by different methods: maximum parsimony and neighborjoining. Our results support the view that the gorilla lineage branched off before the human and chimpanzee diverged and strengthen the hypothesis that chimpanzee and gorilla are more related to human than is orangutan.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186538
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  • 22
    Digitale Medien
    Digitale Medien
    Evidence on primate phylogeny from ε-globin gene sequences and flanking regions (1995)
    Springer
    Journal of molecular evolution 40 (1995), S. 30-55 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Primates ; Strepsirhines ; Aye-aye ; Lemurs ; Phylogeny ; ε-globin gene ; Molecular evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Phylogenetic relationships among various primate groups were examined based on sequences of ε-globin genes. ε-globin genes were sequenced from five species of strepsirhine primates. These sequences were aligned and compared with other known primate ε-globin sequences, including data from two additional strepsirhine species, one species of tarsier, 19 species of New World monkeys (representing all extant genera), and five species of catarrhines. In addition, a 2-kb segment upstream of the ε-globin gene was sequenced in two of the five strepsirhines examined. This upstream sequence was aligned with five other species of primates for which data are available in this segment. Domestic rabbit and goat were used as outgroups. This analysis supports the monophyly of order Primates but does not support the traditional prosimian grouping of tarsiers, lorisoids, and lemuroids; rather it supports the sister grouping of tarsiers and anthropoids into Haplorhini and the sister grouping of lorisoids and lemuroids into Strepsirhini. The mouse lemur (Microcebus murinus) and dwarf lemur (Cheirogaleus medius) appear to be most closely related to each other, forming a clade with the lemuroids, and are probably not closely related to the lorisoids, as suggested by some morphological studies. Analysis of the ε-globin data supports the hypothesis that the aye-aye (Daubentonia madagascariensis) shares a sister-group relationship with other Malagasy strepsirhines (all being classified as lemuroids). Relationships among ceboids agree with findings from a previous ε-globin study in which fewer outgroup taxa were employed. Rates of molecular evolution were higher in lorisoids than in lemuroids.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00166594
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  • 23
    Digitale Medien
    Digitale Medien
    Molecular phylogeny of gibbons inferred from mitochondrial DNA sequences: Preliminary report (1995)
    Springer
    Journal of molecular evolution 41 (1995), S. 359-365 
    Details
    ISSN: 1432-1432
    Schlagwort(e): Gibbons ; Mitochondrial DNA ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We analyzed the 896 base-pair (bp) mitochondrial DNA (mtDNA) sequences for seven gibbons, representative of three out of four subgenera. The result from our molecular analysis is consistent with previous studies as to the monophyly of subgenus Hylobates species, yet the relationship among subgenera remains slightly ambiguous. A striking result of the analysis is the phylogenetic location of Kloss's gibbon (H. klossii). Kloss's gibbon has been considered to be an initial off-shoot of the subgenus Hylobates because of its morphological primitiveness. However, our molecular data strongly suggest that Kloss's gibbon speciated most recently within the subgenus Hylobates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00186548
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  • 24
    Digitale Medien
    Digitale Medien
    DNA polymerase δ of Physarum polycephalum (1995)
    Springer
    Current genetics 28 (1995), S. 534-545 
    Details
    ISSN: 1432-0983
    Schlagwort(e): DNA polymerase δ ; PCNA ; Phylogeny ; Physarum polycephalum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract DNA polymerase δ from the phylogenetically ancient slime mold Physarum polycephalum has been 380-fold enriched from amoebae. It was found to have the properties typical for this type of DNA polymerase from higher eukaryotes with regard to effectors, template-primer acceptance, co-purification with 3′–5′-exonuclease activity, as well as the effect of endogenous proliferating cell nuclear antigen (PCNA) from amoebae on the stimulation and processivity of DNA synthesis. An identified cDNA fragment shows 65.5% identical amino acides with DNA polymerase δ from Saccharomyces pombe. The molecular mass of the polymerase is 125 kDa while that of PCNA is 35 kDa. During size-exclusion chromatography, the highly purified polymerase eluted in the position of 125 kDa, suggesting that no other proteins were tightly complexed with the enzyme. The DNA polymerases from the (mononucleate) amoebae and from the (multinucleate) plasmodia of P. polycephalum have very similar properties in contrast to their differences in phenotype and their mode of nuclear division. The polymerase shows a higher degree of similarity than DNA polymerase α, and especially the β-like DNA polymerase, with the corresponding polymerases of higher eukaryotes. According to antibody staining, DNA polymerase δ is readily fragmented by proteases, even in the presence of inhibitor cocktails. Including freshly prepared cell lysates, proteolytic fragments are reproducible, the most abundant being 50 kDa in size. The DNA polymerase is recognized by the antisera against two peptides which have been derived by PCR-screening of plasmodial cDNA. One of the proteolytic splitting sites is located within an eight amino-acid stretch between the two antigenic sequences.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00518166
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  • 25
    Digitale Medien
    Digitale Medien
    Anaerobic degradation of ethylbenzene and other aromatic hydrocarbons by new denitrifying bacteria (1995)
    Springer
    Archives of microbiology 163 (1995), S. 96-103 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Anaerobic degradation ; Aromatic hydrocarbons ; Alkylbenzenes ; Ethylbenzene ; Crude oil ; Denitrifying bacteria ; Phylogeny ; Thauera selenatis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Anaerobic degradation of alkylbenzenes with side chains longer than that of toluene was studied in freshwater mud samples in the presence of nitrate. Two new denitrifying strains, EbN1 and PbN1, were isolated on ethylbenzene and n-propylbenzene, respectively. For comparison, two further denitrifying strains, ToN1 and mXyN1, were isolated from the same mud with toluene and m-xylene, respectively. Sequencing of 16SrDNA revealed a close relationship of the new isolates to Thauera selenatis. The strains exhibited different specific capacities for degradation of alkylbenzenes. In addition to ethylbenzene, strain EbN1 utilized toluence, but not propylbenzene. In contrast, propylbenzene-degrading strain PbN1 did not grow on toluene, but was able to utilize ethylbenzene. Strain ToN1 used toluene as the only hydrocarbon substrate, whereas strain mXyN1 utilized both toluene and m-xylene. Measurement of the degradation balance demonstrated complete oxidation of ethylbenzene to CO2 by strain EbN1. Further characteristic substrates of strains EbN1 and PbN1 were 1-phenylethanol and acetophenone. In contrast to the other isolates, strain mXyN1 did not grow on benzyl alcohol. Benzyl alcohol (also m-methylbenzyl alcohol) was even a specific inhibitor of toluene and m-xylene utilization by strain mXyN1. None of the strains was able to grow on any of the alkylbenzenes with oxygen as electron acceptor. However, polar aromatic compounds such as benzoate were utilized under both oxic and anoxic conditions. All four isolates grew anaerobically on crude oil. Gas chromatographic analysis of crude oil after growth of strain ToN1 revealed specific depletion of toluene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00381782
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  • 26
    Digitale Medien
    Digitale Medien
    Anaerobic degradation of ethylbenzene and other aromatic hydrocarbons by new denitrifying bacteria (1995)
    Springer
    Archives of microbiology 163 (1995), S. 96-103 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Anaerobic degradation ; Aromatic ; hydrocarbons ; Alkylbenzenes ; Ethylbenzene ; Crude oil ; Denitrifying bacteria ; Phylogeny ; Thauera selenatis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Anaerobic degradation of alkylbenzenes with side chains longer than that of toluene was studied in freshwater mud samples in the presence of nitrate. Two new denitrifying strains, EbN1 and PbN1, were isolated on ethylbenzene and n-propylbenzene, respectively. For comparison, two further denitrifying strains, ToN1 and mXyN1, were isolated from the same mud with toluene and m-xylene, respectively. Sequencing of 16S rDNA revealed a close relat ionship of the new isolates to Thauera selenatis. The strains exhibited different specific capacities for degradation of alkylbenzenes. In addition to ethylbenzene, strain EbN1 utilized toluene, but not propylbenzene. In contrast, propylbenzene-degrading strain PbN1 did not grow on toluene, but was able to utilize ethylbenzene. Strain ToN1 used toluene as the only hydrocarbon substrate, whereas strain mXyN1 utilized both toluene and m-xylene. Measurement of the degradation balance demonstr ated complete oxidation of ethylbenzene to CO2 by strain EbN1. Further characteristic substrates of strains EbN1 and PbN1 were 1-phenylethanol and acetophenone. In contrast to the other isolates, strain mXyN1 did not grow on benzyl alcohol. Benzyl alcohol (also m-methylbenzyl alcohol) was even a specific inhibitor of toluene and m-xylene utilization by strain mXyN1. None of the strains was able to grow on any of the alkylbenzenes with oxygen as electron acceptor. However, polar aromatic compounds such as benzoate were utilized under both oxic and anoxic conditions. All four isolates grew anaerobically on crude oil. Gas chromatographic analysis of crude oil after growth of strain ToN1 revealed specific depletion of toluene.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00381782
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  • 27
    Digitale Medien
    Digitale Medien
    Heliobacterium modesticaldum, sp. nov., a thermophilic heliobacterium of hot springs and volcanic soils (1995)
    Springer
    Archives of microbiology 163 (1995), S. 259-267 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Key words Anoxygenic phototrophic bacteria ; Heliobacteria ; Heliobacterium modesticaldum ; Thermophily ; Hot springs ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Enrichment cultures for heliobacteria at 50°C yielded several strains of a thermophilic heliobacterium species from Yellowstone hot spring microbial mats and volcanic soils from Iceland. The novel organisms grew optimally above 50°C, contained bacteriochlorophyll g, and lacked intracytoplasmic membranes. All isolates were strict anaerobes and grew best as photoheterotrophs, although chemotrophic dark growth on pyruvate was also possible. These thermophilic heliobacteria were diazotrophic and fixed N2 up to their growth temperature limit of 56°C. Phylogenetic studies showed the new isolates to be specific relatives of Heliobacterium gestii and, as has been found in H. gestii, they produce heat-resistant endospores. The unique assemblage of properties found in these thermophilic heliobacteria implicate them as a new species of this group, and we describe them herein as a new species of the genus Heliobacterium, Heliobacterium modesticaldum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00393378
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  • 28
    Digitale Medien
    Digitale Medien
    Heliobacterium modesticaldum, sp. nov., a thermophilic heliobacterium of hot springs and volcanic soils (1995)
    Springer
    Archives of microbiology 163 (1995), S. 259-267 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Anoxygenic phototrophic bacteria ; Heliobacteria ; Heliobacterium modesticaldum ; Thermophily ; Hot springs ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Enrichment cultures for heliobacteria at 50°C yielded several strains of a thermophilic heliobacterium species from Yellowstone hot spring microbial mats and volcanic soils from Iceland. The novel organisms grew optimally above 50°C, contained bacteriochlorophyll g, and lacked intracytoplasmic membranes. All isolates were strict anaerobes and grew best as photoheterotrophs, although chemotrophic dark growth on pyruvate was also possible. These thermophilic heliobacteria were diazotrophic and fixed N2 up to their growth temperature limit of 56°C. Phylogenetic studies showed the new isolates to be specific relatives of Heliobacterium gestii and, as has been found in H. gestii, they produce heat-resistant endospores. The unique assemblage of properties found in these thermophilic heliobacteria implicate them as a new species of this group, and we describe them herein as a new species of the genus Heliobacterium, Heliobacterium modesticaldum.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00393378
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  • 29
    Digitale Medien
    Digitale Medien
    Relationships among cultivated and wild lentils revealed by RAPD analysis (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 647-654 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Lens ; RAPD ; Cluster analysis ; Diversity ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract RAPD markers were used to distinguish between six different Lens taxa, representing cultivated lentil and its wild relatives. Twenty-four arbitrary sequence 10-mer primers were identified which revealed robust and easily interpretable amplification-product profiles. These generated a total of 88 polymorphic bands in 54 accessions and were used to partition variation within and among Lens taxa. The data showed that, of the taxa examined, ssp. orientalis is most similar to cultivated lentil. L. ervoides was the most divergent wild taxon followed by L. nigricans. The genetic similarity between the latter two species was of the same magnitude as between ssp. orientalis and cultivated lentil. In addition, species-diagnostic amplification products specific to L. odemensis, L. ervoides and L. nigricans were identified. These results correspond well with previous isozyme and RFLP studies. RAPDs, however, appear to provide a greater degree of resolution at a sub-species level. The level of variation detected within cultivated lentils suggests that RAPD markers may be an appropriate technology for the construction of genetic linkage maps between closely related Lens accessions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223292
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  • 30
    Digitale Medien
    Digitale Medien
    Phylogenetic relationships within Hevea brasiliensis as deduced from a polymorphic mitochondrial DNA region (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 876-884 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Hevea brasiliensis ; Mitochondrial DNA ; Phylogeny ; Hypervariable sequence ; Hot spot
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract We have cloned a 4.5-kb mtDNA fragment showing a high RFLP polymorphism between various Hevea genotypes. Subcloning and sequencing of a 1.4-kb segment of this clone allowed us to design PCR amplification primers to isolate homologous mtDNA segments of about 0.9 kb from 23 representative genotypes of Hevea. Complete sequences from 4 genotypes showed between 6.7% and 20.2% of nucleotide diversity, suggesting the presence of a hypervariable, or hotspot, region. A sequence of 345 nucleotides within this region was determined for the 23 genotypes. The phylogenetic relationships inferred from the sequence comparison are in general agreement with the results obtained from mtDNA RFLP analysis, indicating that this polymorphic mtDNA region is a useful molecular marker for phylogenetic analysis within Hevea.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223895
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  • 31
    Digitale Medien
    Digitale Medien
    Phylogenetic relationships of cultivated Prunus species from an analysis of chloroplast DNA variation (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 1035-1041 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Chloroplast ; Phylogeny ; DNA ; PCR ; Prunus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chloroplast DNA (cpDNA) restriction-site mutations in seven cultivated Prunus species were compared to establish the phylogenetic relationships among them. Mutations were detected in 3.2-kb and 2.1-kb amplified regions of variable cpDNA, cut with 21 and 10 restriction endonucleases, respectively, to reveal polymorphisms. Parsimony and cluster analyses were performed. The species pairs P. persica-P. dulcis, P. domestica-P. salicina, and P.cerasus-P. fruticosa were completely monophyletic. All of the species were grouped with conventional subgenus classifications. The subgenus Cerasus was the most diverged. Cerasus ancestors separated from the remainder of Prunus relatively early in the development of the genus. P. persica-P. dulcis, P. domestica-P. salicina and P. armeniaca formed a second monophyletic group. Prunophora species were less diverged than Amygdalus species. The results also suggest that the rate of mutation in Cerasus spp. chloroplast genomes is significantly greater than for the other subgenera sampled.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222918
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  • 32
    Digitale Medien
    Digitale Medien
    Mitochondrial gene variation and phylogenetic relationships in the genus Beta (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 914-919 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Sugarbeet ; Beta species ; Mitochondrial gene ; Taxonomy ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Restriction fragment length polymorphisms (RFLPs) for three mitochondrial genes, coxI, coxII and atpA, were used to determine mitochondrial (mt) DNA diversity in 21 accessions of the genus Beta representing wild and cultivated species. On the basis of distribution of the RFLP patterns these Beta genotypes were assigned into six distinct chondriome groups. A high degree of heterogeneity was found to exist between the mitochondrial genomes of the sugarbeet cultivar and the wild species of Procumbentes section. The polymorphic fragments from wild Beta species were cloned and subjected to fine mapping. We found that most of the RFLPs are due to sequence rearrangements rather than point mutations. Our data also suggest that the close linkage between coxII and coxI is taxonomically localized to an evolutionary lineage that led to Vulgares and Corollinae species but not to Procumbentes species. This linkage is most likely to have arisen via the mutation(s) that inserted the DNA segment containing coxI downstream of coxII in the common ancestor of Vulgares and Corollinae species. The results are discussed with regard to the taxonomic and phylogenetic relationships of the Beta species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222903
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  • 33
    Digitale Medien
    Digitale Medien
    Genetic variation within and among different cultivars and landraces of Brassica campestris L. and B. oleracea L. based on isozymes (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 346-352 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Brassica campestris ; Brassica oleracea ; Isozymes ; Genetic variation ; Heterozygosity ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Genetic variation based on isozymes was studied in 43 landraces and cultivars of Brassica campestris from China, 4 cultivars of B. campestris from Sweden and 1 from India, and 5 cultivars of B. oleracea from Sweden and 1 from China (B. alboglabra). A total of 17 isozyme loci was studied, 10 of these were polymorphic in B. campestris and 6 were polymorphic in B. oleracea. The level of heterozygosity seemed to be reduced in the Swedish cultivars compared to the Chinese landraces and cultivars of B. campestris. The level of heterozygosity in B. oleracea was even lower than that in the Swedish cultivars of B. campestris. A phylogeny of the cultivars and landraces of B. campestris showed that the B. campestris var ‘yellow sarson’ cultivar, originating from India, deviated significantly from the other cultivars of B. campestris. A phylogeny of the cultivars of B. oleracea confirmed the expectations that the cultivar B. alboglabra was not closely related to the cultivated forms of B. oleracea.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220898
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  • 34
    Digitale Medien
    Digitale Medien
    Inheritance of isozymes in Brassica campestris L. and genetic divergence among different species of Brassiceae (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 353-360 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Brassica species ; Sinapis species ; Isozymes ; Inheritance ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Electrophoretic investigations of Brassica campestris revealed 8 polymorphic loci that had not been described earlier. The inheritance of 7 of them was determined by crosses between different accessions of B. campestris. A phylogeny of B. campestris, B. nigra, B. alboglabra, Sinapis arvensis and S. alba was estimated from the analysis of 15 isozyme loci. The phylogeny showed a close relationship between B. nigra and S. arvensis and a less close relationship between B. campestris and B. oleracea. S. alba was remotely-related to all of the other species.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00220899
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  • 35
    Digitale Medien
    Digitale Medien
    A single nuclear locus phylogeny of soybean based on DNA sequence (1995)
    Springer
    Theoretical and applied genetics 90 (1995), S. 991-999 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Glycininae ; Soybean ; Phylogeny ; DNA sequence ; Genomic donors ; Glycine ; Phaseoleae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Soybean [Glycine max (L.) Merr.] evolution was examined by sequencing portions of the restriction fragment length polymorphism (RFLP) locus A-199a of 21 taxa from the Glycininae and 1 from the Phaseoleae. Four hundred nucleotides were determined in each, aligned, and then compared for these taxa. Within the annual soybean subgenus (Soja), the four accessions differed at as many as 2.2% of the nucleotides. Among 13 perennial soybean species (subgenus Glycine), nucleotide variation ranged from 1.7% to 8.4%. The nucleotide difference between the two soybean subgenera was 3.0–7.0%. Nucleotide variation between the genus Glycine and the related genera of Neonotonia, Amphicarpa, Teramnus, and Phaseolus ranged from 8.2% to 16.4%. In addition to nucleotide substitutions, insertions/deletions (indels) differences were also observed and were consistent with nucleotide-based analysis. Cladistic analysis of the A-199a sequences was performed using Wagner parsimony to construct a soybean phylogeny. Sixteen equally parsimonious trees were produced from these data. The trees were 246 steps in length with a consistency index of 0.78. Indels distribution upon the consensus topology revealed a pattern congruent with the nucleotide-based phylogeny. The current taxonomic status of the soybean subgenera and the related genera of Neonotonia, Amphicarpa, and Teramnus were well-supported and appear monophyletic in this analysis. Homoplasy within the subgenus Glycine led to a lack of resolved topology for many of these 13 taxa. However, the Glycine clade topology was consistent with phylogenies proposed using crossing experiments and cpDNA RFLPs. These genera were arranged from ancestral to derived as: Teramnus, Amphicarpa, Neonotonia, and Glycine when Phaseolus vulgaris was used as an outgroup.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00222912
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  • 36
    Digitale Medien
    Digitale Medien
    Noncoding chloroplast DNA variation in Mexican pines (1995)
    Springer
    Theoretical and applied genetics 91 (1995), S. 1101-1106 
    Details
    ISSN: 1432-2242
    Schlagwort(e): Pinus ; Noncoding cpDNA ; Genetic variation ; Phylogeny ; Conservation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Universal primers were used for PCR amplification of three noncoding regions of chloroplast DNA in order to study restriction site variation in 12 Mexican pine species. Two length mutations were identified that are of diagnostic value for two subgenera or sections of the genus. Phylogenetic analysis of the restriction site and length variation showed patterns of variation largely consistent with previous arrangements of these pines, except for the position of Pinus nelsonii, indicating that Pinus section Parraya Mayr, as circumscribed by Little and Critchfield (1969) and later authors, is not a monophyletic group.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00223926
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  • 37
    Digitale Medien
    Digitale Medien
    Easel, a gypsy LTR-retrotransposon in the Salmonidae (1995)
    Springer
    Molecular genetics and genomics 249 (1995), S. 229-236 
    Details
    ISSN: 1617-4623
    Schlagwort(e): gypsy ; LTR-retrotransposon ; Fish ; Phylogeny ; Vertebrate
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Despite the close similarities between retroviruses and the gypsy/Ty3 group of LTR-retrotransposons their host ranges are largely distinct: the retroviruses are found only in vertebrates, whereas the gypsy LTR-retrotransposons are almost exclusively restricted to invertebrates, plants and fungi. Here we report the amplification by PCR, and characterisation, of one of the first LTR-retrotransposons to be discovered in vertebrates - in several members of the piscine family Salmonidae. Phylogenetic analysis of this retroelement, termed easel, indicates that it is probably a phylogeneticaly basal member of the gypsy group of LTR-retrotransposons and occurs in some of the same species from which retroviruses have previously been isolated. Thus some members of the Salmonidae are the first organisms known to harbour both retroviral branch elements and the gypsy LTR-retrotransposon branch elements. This creates an overlap in the host ranges of the two retroelement families.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00290370
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  • 38
    Digitale Medien
    Digitale Medien
    Oxidation of acetophenone in a high temperature open-tubular capillary column liquid chromatographic system (1995)
    Springer
    Chromatographia 40 (1995), S. 99-101 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; High temperature open-tubular columns ; Solvent make-up ; Acetophenone oxidation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Acetophnone, a substance stable at room temperature, is readily oxidizes in a high temperature open tubular liquid chromatographic system by the residual oxygen in the mobile phase. The oxidation product is less UV absorptive and detection sensitivity decreases greatly. To prevent the oxidation, through degassing of the mobile phase is necessary.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274615
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  • 39
    Digitale Medien
    Digitale Medien
    The removal of endotoxins from protein solutions using column packings with aminated poly (γ-methyl L-glutamate) spheres (1995)
    Springer
    Chromatographia 40 (1995), S. 33-38 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Endotoxins ; Lipopolysaccharide ; Aminated poly(γ-methyl L-glutamate) ; Bovine serum albumin
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method is described for the selective removal of endotoxins from various protein solutions using columns packed with aminated poly (γ-methyl L-glutamate) (PMLG-NH2) spheres. The PMLG-NH2 adsorbents showed a high adsorbing activity for endotoxins which had an ionic strength of μ=0.05–1.0 and pH 5.0–9.0. The endotoxin-adsorbing capacity per millitre of the wet adsorbent increased from 0.40 to 1.35 mg (E. coli O111: B4 LPS) at μ=0.2 and pH 7.0 while the aminogroup content of the adsorbent increased from 0.8 to 3.5 meq g−1. The PMLG-NH2-3.5 has an amino-group content of 3.5 meq g−1. This column packing selectively adsorbed endotoxins, without loss of the protein, from a γ-globulin or cytochromec solution which contained endotoxins at μ=0.05 and pH 7.0. On the other hand, when bovine serum albumin (BSA) was present in solution with endotoxins, both the endotoxins and the BSA were adsorbed by the column. The BSA-adsorbing activity increased with increasing amino-group content of the adsorbent. However, this undesirable adsorption was suppressed with increasing ionic strength of the buffer. As a result, when the packing which had an amino-group content of 1.5 meg g−1 was used in conditions of μ=0.2 and pH 7.0, the endotoxins were removed from a BSA-containing solution without affecting the recovery of the BSA.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274604
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  • 40
    Digitale Medien
    Digitale Medien
    Analysis of lignin degradation products by capillary electrophoresis (1995)
    Springer
    Chromatographia 40 (1995), S. 51-57 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column electrophoresis ; Column liquid chromatography ; Phenolic lignin degradation compounds ; Sugar degradation products ; Quantitative analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A method for the quantitative analysis of phenolic lignin degradation products by capillary electrophoresis (CE) with on-column UV detection has been developed. The liquid biomass solutions contain low molecular hemicellulosic sugars and phenolic lignin degradation products with various degrees of polymerization. Special attention has been paid to the monomeric phenolic components of lignin degradation fragments, e.g. derivatives of phenolic acids, aldehydes, and alcohols. Uncoated fused silica capillaries and borate-phosphate buffer systems at moderate pH conditions were used in order to separate the compounds of interest. To provide validation of the method, the same samples were analyzed independently by HPLC using gradient elution on a RP-C18 column. As sugar degradation fragment, furan-2-carboxylic acid was detected.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274608
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  • 41
    Digitale Medien
    Digitale Medien
    Liquid chromatography of phenolic compounds in natural water using on-line trace enrichment (1995)
    Springer
    Chromatographia 40 (1995), S. 85-90 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Phenolic compounds ; Ion-pair solid phase extraction ; On-line trace enrichment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two packing materials, C18 and PLRP-S, are studied for on-line trace enrichment of phenolic compounds in water. Various precolumns of different internal diameter are also tested and the addition of an ion-pair reagent to increase retention and thus, breakthrough volumes of phenolic compounds, is studied. Best results are obtained when a PLRP-S precolumn is coupled on-line with a C18 analytical column and DAD detector. Addition of TBA considerably increases breakthrough volumes. In contrast, when a C18 precolumn is used, breakthrough volumes are lower and it is impossible to determine TCP and PCP, under the experimental conditions used, because of interference of other nonpolar compounds in the samples. The performance of the system is evaluated with river and tap water and the preconcentration of 10 ml of sample in a PLRP-S precolumn involves a linear range between 1 μg 1−1 and 20 μl−1 and limits of determination between 0.5 μg l−1 and 1 μg l−1 are obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274612
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  • 42
    Digitale Medien
    Digitale Medien
    Screening of water samples for polar organic micropollutants using on-column sample enrichment (1995)
    Springer
    Chromatographia 40 (1995), S. 631-637 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Trace analysis ; Pesticides in tap water ; Aromatic sulphonates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Methodology and instrumentation are described which allow chromatographic screening of water samples under substantially simplified conditions and at reduced cost. A single column is used to accomplish sample extraction, trace enrichment, and separation. The performance of such a system is demonstrated, and the results compared with conventionally used concepts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315129
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  • 43
    Digitale Medien
    Digitale Medien
    Analysis of pyrithiones by reversed-phase high-performance liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 669-673 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Transchelation ; Zinc pyrithione and related compounds ; Antidandruff formulations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An analytical procedure has been developed for the determination of zinc pyrithione in antidandruff formulations. Zinc pyrithione was converted into a stable copper complex and then analysed by reversed-phase HPLC. The proposed method allows the separation of the analyte from related pyrithiones and therefore is able to verify the compliance of cosmetic preparations with current legislation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315135
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  • 44
    Digitale Medien
    Digitale Medien
    Marked differences between acetonitrile/water and methanol/water mobile phase systems on the thermodynamic behavior of benzodiazepines in reversed phase liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 84-87 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Benzodiazepines ; Solvent effects ; ACN clusters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two different methods were used to determine the separation factor α at different temperatures and the Gibbs-Helmholtz parameters (Δ(ΔH), Δ(ΔS)) of two adjacent benzodiazepines on a chromatogram were obtained from plots of lnα versus 1/T. We first studied each factor (fraction of water ϕ in the ACN/water mixture and column temperatureT), which controls the retention mechanism, and then we examined the simultaneous variation of all these factors. The changes in Δ(ΔH) and Δ(ΔS) in relation to a volume fraction of water ϕ in an ACN/water mixture were examined. In the ACN/water system, Δ(ΔH) was fairly constant in the acetonitrile region of ϕ≤0.52 and appears to be a roughly linear function of ϕ for ϕ≥0.52. In this system Δ(ΔS) is approximately a parabolic function of ϕ with an optimum at ϕ≅0.52. The retention mechanism of ten benzodiazepines was found to be significantly different in the methanol/water and ACN/water mixtures. The separation optimization of these ten benzodiazepines was then considered. A fraction of water of 0.43 in the ACN/water mixture and a column temperature of 44°C gave the most efficient separation conditions in the ACN/water mixture.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274199
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  • 45
    Digitale Medien
    Digitale Medien
    HPLC determination of urinary 2,4- and 2,6-toluendiamines as potential degradation products of polyurethane breast implants (1995)
    Springer
    Chromatographia 41 (1995), S. 661-664 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Polyurethane degradation products ; 2,4- and 2,6-toluendiamine ; Urine analysis ; Breast implants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A reversed-phase HPLC method has been developed for the urinary determination of mutagenic 2,4- and 2,6-toluendiamines. These amines are degradation products of polyurethane, a material used to cover textured silicone breast implants. FMOC-Cl was used as fluorescent derivatising agent in order to obtain a limit of detection of 15 ng/ml in urine. Pre-treatment of urine samples was by liquid/liquid extraction and urine specimens of patients after surgury were analysed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267801
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  • 46
    Digitale Medien
    Digitale Medien
    HPLC analysis of flavonoids and phenolic acids and aldehydes inEucalyptus spp. (1995)
    Springer
    Chromatographia 41 (1995), S. 657-660 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Polyphenols ; Flavonoids ; Phenolic acids and aldehydes ; Eucalyptus spp.
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Standards of the polyphenols occurring in wood, bark and leaf extracts ofEucalyptus spp. (i.e. flavonoids and phenolic acids and aldehydes) have been analyzed by HPLC using reversed phase columns, gradient elution and diode-array detection. The conditions used are reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267800
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  • 47
    Digitale Medien
    Digitale Medien
    Polymer encapsulated stationary phases with improved efficiency (1995)
    Springer
    Chromatographia 40 (1995), S. 657-661 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Reversed phases ; Polyencapsulated silica ; Polyacrylates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary By copolymerization of silica modified with vinyl groups and acrylic acid esters in suspension highly efficient, polymeric-encapsulated stationary-phases can be prepared. The suspending liquid has to be selected such that the monomers are at least partially adsorbed on the surface and the polymer formed does not precipitate. Under these conditions stationary phases capable of speedy mass transfer can be prepared, where the reduced plate heights are between 2 and 3. The silica surface shielding is optimized so that basic and acidic solutes elute with symmetrical peak.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315133
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  • 48
    Digitale Medien
    Digitale Medien
    Determination of D- and L-amino acid residues in peptides with fluorescent chiral tagging reagents by high-performance liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 645-651 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Chiral resolution of amino acids ; Pre-column derivatization ; Fluorescent chiral tagging reagents ; Stereochemical purity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Derivatization of amino acid enantiomers with fluorescent chiral Edman-type reagents, 4-(3-isothiocyanatopyrrolidin-1-yl)-7-nitro-2,1,3-benzoxadiazole [R(−)- and S(+)-NBD-PyNCS] and 4-(3-isothiocyanatopyrrolidin-1-yl)-7-(N,N-dimethylaminosulfonyl)-2,1,3-benzoxadiazole [R(−)-and S(+)-DBD-PyNCS], yields corresponding diastereomers separable by reversed-phase HPLC on normal achiral columns. The resolved diastereomers were detected fluorometrically at 530 nm with excitation at 490 nm for the NBD-PyNCS derivatives and at 560 nm with excitation at 450 nm for those derived from DBD-PyNCS reagents. This HPLC-derivatization method was used for evaluation of stereochemical purity for some synthetic commercial peptides. The enantioanalysis was reliable down to 0.05% racemization of the amino acid residues and a quantity of 100 μg peptide sample was usually enough for the analysis. Two acid hydrolysis methods, i.e. the standard procedure with constant-boiling hydrochloric acid (HCl) and a rapid vapor-phase procedure with HCl-trifluoroacetic acid (TFA) mixture, were compared. The later was found to be unsuitable owing to increased racemization of the amino acid residues during the hydrolysis. Judging from the results obtained for proline and leucine residues, most of the tested peptides including biologically active peptides, such as neurotensin, [d-Ala2,d-Leu5]-enkepharin and morphine tolerance peptide, possessed stereochemical purities higher than 98%. Influence of structural features of the peptides on the racemization of the amino acid residues was found to be significant.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315131
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  • 49
    Digitale Medien
    Digitale Medien
    HPLC-continuous-flow fast atom bombardment mass spectrometry (HPLC-CFFAB) — a convenient method for the analysis of bile acids in bile and serum (1995)
    Springer
    Chromatographia 40 (1995), S. 674-679 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Mass spectrometric detection ; Fast atom bombardment ionization ; Serum bile acid ; Rat bile
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary In order to analyse bile acids in biological matrices, e.g. rat bile and human serum, high performance liquid chromatography (HPLC) was coupled to continuous-flow fast atom bombardment mass spectrometry (CFFAB-MS). A gradient elution system which had already proved to be well suited for the quantitative determination of conjugated bile acids in bile was modified to allow HPLC-CFFAB-MS-coupling. Due to the sensitivity of this coupling method it is possible to obtain more information about the biliary bile acid pattern and species-specific secondary bile acids. Furthermore, we were able to identify obviously unknown bile acid species in rat bile which most likely classify as mono-oxo and di-oxo-taurocholates (MW 513 Da, 511 Da) and mono-oxo-glycocholates (MW 463 Da). In the present study we show that using this system it is possible to determine both conjugated and unconjugated as well as sulfated bile acids, without time consuming group separation and derivatization, from rat bile and human serum. In addition, it is suggested that the method presented here should be considered for use in routine analysis.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315136
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  • 50
    Digitale Medien
    Digitale Medien
    Fluorescence enhancement of dansylamino acids by bovine serum albumin as mobile phase additive in microcolumn liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 159-162 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Fluorescence enhancement ; Bovine serum albumin ; Dansylamino acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The effects of acetonitrile and bovine serum albumin (BSA) concentrations on the signal intensity and retention behavior of dansylamino acids have been examined by using γ-cyclodextrin-bonded silica gel as the stationary phase in microcolumn liquid chromatography. Fluorescence intensities of dansylamino acids were enhanced by BSA as a mobile phase additive, e.g., detection limits of dansyl derivatives of L-Ala and L-Phe were improved by a factor of 12–18.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02272165
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  • 51
    Digitale Medien
    Digitale Medien
    A statistical study of the correlation between k′ or log k′ and log Pow for a group of benzene and naphthalene derivatives in micellar liquid chromatography using a C-18 column (1995)
    Springer
    Chromatographia 40 (1995), S. 185-192 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Micellar liquid phases ; Octanol-water partition coefficient ; Benzene and naphthalene derivatives
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary It is shown that the logarithm of the capacity factor (log k′) for fifteen benzene and naphthalene derivatives in micellar liquid chromatography with forty nine different mobile phases generally correlates better with the logarithm of the octanol-water partition coefficient (log Pow) than the capacity factor (k′). Optimum conditions are established to obtain the best linear correlations of log k′-log Pow.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02272169
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  • 52
    Digitale Medien
    Digitale Medien
    Improvement of selectivity of electrochemical detection for the determination of compounds with chloro aromatic rings (1995)
    Springer
    Chromatographia 40 (1995), S. 247-252 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Photolysis ; Electrochemical detection ; Drugs with chlorinated aromatic rings
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Pharmaceuticals containing a thiazide ring or chlorinated aromatic ring were investigated with respect to enhanced selectivity in determination. Oxidative electrochemical detection coupled with HPLC was used to study the influence of the pH of the mobile phase under conditions of photolysis. To cover a pH range 3.9–12, the employment of a polymer column stable in alkaline media was necessary. The method offers the great advantage of derivatization without chemicals at low operating potentials, thereby providing high selectivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290353
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  • 53
    Digitale Medien
    Digitale Medien
    Separation of structural isomers using cyclodextrin-polymers coated on silica beads (1995)
    Springer
    Chromatographia 40 (1995), S. 296-302 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Structural isomer separation ; Cyclodextrin ; Polymers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Several β-cyclodextrin (CD)-bonded stationary phases for high performance liquid chromatography (HPLC) were prepared, based on silica beads coated with a poly(alkylamine), [poly(ethyleneimine)(PEI)]. In order to obtain stationary phases with a high content of CD and maximum accessibility of the CD cavity, the functionalization was carried out after the coating, using the mono-tosyl derivative of CD as the intermediate. The ability of these supports to separate ortho, meta and para isomers of some disubstituted benzene derivatives was examined. The contribution of the amino groups of the polymer and of the CD cavity to the separation process is discussed. The resolution is mainly based on the difference in the stability of the complexes of the various isomers with CD. The influence of the amount of CD on the height of the theoretical plate is also studied.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290360
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  • 54
    Digitale Medien
    Digitale Medien
    A potential application for large diameter pellicular supports in the reversed phase study of ultra high molecular mass polystyrenes (1995)
    Springer
    Chromatographia 40 (1995), S. 307-312 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Reversed phase ; Polystyrene ; Pellicular ; Ultra high molecular mass
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Ultra high molecular mass (〉 7 million dalton) polystyrenes are prone to degradation in size exclusion chromatography. In gradient elution reversed phase HPLC they do not elute visibly on small particle size porous supports. However, large diameter C18 pellicular particles were successfully employed for reversed phase study of ultra high molecular mass (15 million dalton) polystyrenes without polymer degradation during elution. Although retention for the lower molecular mass polystyrenes was lower than on small diameter porous particles, the medium high molecular mass polystyrenes (0.5–1 million dalton) showed similar retention. The addition of small diameter porous particles in small quantities, to the large diameter pellicular particles, increased the amount of retention of the low molecular mass polystyrenes without affecting the higher molecular mass polystyrenes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290362
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  • 55
    Digitale Medien
    Digitale Medien
    High performance liquid chromatographic determination of methyl ethyl ketone in urine as its 3-methyl-2-benzothiazolinone hydrazone derivative (1995)
    Springer
    Chromatographia 40 (1995), S. 336-340 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Methyl ethyl ketone in urine ; Derivatization ; 3-Methyl-2-benzothiazolinone hydrazone ; Comparison with GC-MS
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A HPLC method for the determination of methyl ethyl ketone (MEK) in urine after derivatization with 3-methyl-2-benzothiazolinone hydrazone is proposed. The calibration curve for the ketone was linear, ranging between 0.23–10 mg/L, with a detection limit of 0.025 mg/L. The results were compared to those obtained by GC-MS, coupled to the headspace technique. MEK derivatization and the derivative purification processes were verified with respect to the main variables such as reaction temperature, reagent concentration, probable interferences and enrichment phase. The method is simple and reliable and shows a good sensitivity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290366
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  • 56
    Digitale Medien
    Digitale Medien
    Liquid chromatographic analysis of sulfornamides in foods (1995)
    Springer
    Chromatographia 40 (1995), S. 382-386 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Sulfonamides in foodstuffs ; Honey ; Milk ; Eggs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A procedure for the simultaneous determination of several sulfonamides in different foods, such as honey, milk and eggs is proposed. The analysis is carried out using reversed phase liquid chromatography with spectrophotometric detection. Optimization of the mobile phase led to good separation and a short analysis time when an initial isocratic step with a 3∶97 acetonitrile: water mixture was used for 5 minutes, followed by a linear gradient up to a 40∶60 mixture over 15 min. The proposed method is suitable for routine quality control analysis to ensure the absence of sulfonamides in foods. Recovery studies yielded good results for all food samples because there were no interferences from the matrices.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269899
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  • 57
    Digitale Medien
    Digitale Medien
    Determination of aflatoxins in peanut meal by LC/MS with a particle beam interface (1995)
    Springer
    Chromatographia 40 (1995), S. 411-416 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Particle beam LC/MS interface ; Capillary columns for LC ; Mycotoxins ; Peanut meal
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A new method for the analysis of aflatoxins in food extracts, based on liquid chromatography/mass spectrometry interfacing, is presented. The chromatographic separation was performed with a reversed phase packed capillary column coupled with a modified particle beam interface capable of handling microliter per minute flow rates. This system allows higher overall sensitivity and easier operation procedures. The method has proved to be particularly suitable for the analysis of the toxins in very complex matrices. The specificity of electron impact ionization allowed positive identification of the aflatoxins with an excellent response linearity for accurate quantitation.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269904
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  • 58
    Digitale Medien
    Digitale Medien
    Retention parameters of some isomeric 2-benzoylbenzoic acids in reversed-phase ion-pair high performance thin-layer and column chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 453-457 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Thin-layer chromatography ; Reversed phase ; 2-benzoylbenzoic acids ; Anionic and cationic counter ions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The 2-benzoylbenzoic acid series was investigated by reversed-phase, high-performance, thin-layer and column chromatography using various alkylammonium salts and di(2-ethylhexyl)orthophosphoric acid as polar associating reagents. The effects of the individual substituents on retention were quantified by Δlog k′ and ΔRM values. The compounds investigated differing in molecular structure (hydrophilic and hydrophobic substituents) commonly occurring groups in drugs and biologically active substances provide information on molecular interaction in these ion-pair systems. The combined effects on retention of organic modifier and ion-pair reagent concentration were investigated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269912
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  • 59
    Digitale Medien
    Digitale Medien
    Determination of D- and L-amino acids in biological samples by two-dimensional column liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 6-14 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Two-dimensional separation ; D- and L-amino acids ; Enantioseperation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 μl heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274188
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  • 60
    Digitale Medien
    Digitale Medien
    Simultaneous determination of preservatives, sweeteners and antioxidants in foods by paired-ion liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 43-50 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Ion pair LC ; Sweeteners, preservatives and antioxidants ; Food additive analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na and acesulfame-K), preservatives (sodium dehydroacetate, sorbic acid, salicyclic acid, benzoic acid, succinic acid, methyl-para-hydroxybenzoic acid, ethylpara-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, isopropyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 mM aqueous α-hydroxy-isobutyric acid solution (pH 4.5) (2.2 ∶ 3.4 or 2.4 ∶ 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a C18 column with a flow rate at 1.0 mL/min and detection at 233 nm were used. This method was found to be very reproducible with detection limits ranged from 0.15 to 3.00 μg. The retention factor (k) of each additive could be affected by concentrations of hexadecyltrimethylammonium bromide and α-hydroxyisobutyric acid, and pH and ratio of mobile phase. The presence of additives in some food samples was determined.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274194
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  • 61
    Digitale Medien
    Digitale Medien
    Prediction of precision from signal and noise measurement in liquid chromatography: Mathematical relationship between integration domain and precision (1995)
    Springer
    Chromatographia 41 (1995), S. 75-83 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Limit of detection ; Precision ; Uncertainty prediction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The precision of integration over noisy instrumental output for quantitative analysis is studied. A probability theory is developed to predict the relative standard deviation (RSD) of integration results over an integration domain from one-point integation (peak height measurement) to entire area integration in HPLC. Common integration modes of horizontal zero line and oblique zero line are taken into account, but no peak overlap is assumed. The question of the analytical superiority of peak height measurement or integration for quantitation is answered. In the HPLC apparatus used, the minimum RSD of measurements is found in the integration domain of ca. ±0.5 σ for analytes [peaks are approximated by the Gaussian signal of width, σ (standard deviation)]. The RSD of integration measurements is also shown to depend on the stochastic properties of back-ground noise (uncorrelated noise and correlated 1/f type noise). The theoretical conclusion is verified by Monte Carlo simulation and HPLC experiments for some aromatic compounds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274198
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  • 62
    Digitale Medien
    Digitale Medien
    Ion-pair reversed-phase and low-molecular-weight aqueous gel permeation high-performance liquid chromatography methods for the determination of amoxicillin oligomersa (1995)
    Springer
    Chromatographia 41 (1995), S. 651-656 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Ion-pair and GPC separations ; Amoxicillin oligomers ; β-Lactam ring polymers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Polymeric substances formed from concentrated sodium amoxicillin in an aqueous solution have been separated using two high-performance liquid chromatographic methods. We used a C18 reversed-phase column with tetrabutylammonium chloride as an ion-pairing agent with an acetonitrile gradient and a TSKgel G2500PWxl column with water as the solvent for gel permeation chromatography. The separated materials, ranging in size from the monomer to the tetramer, have been characterized by functional-group chemical analysis, while the identification of the piperazine-2,5-dione was done using a pure standard. A greater number of peaks which were also better defined were obtained using the ion-pair reversed-phase method, and open and closed beta-lactam ring polymer forms could be distinguished. Using the gel permeation method, only a few monomer, piperazine-2,5-dione, dimer, trimer and combined amoxicillin trimer and tetramer peaks were obtained with water, although those obtained were quite well defined. The data on the time-course of formation of the oligomers and the amoxicillin degradation product were virtually identical by both methods.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267799
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  • 63
    Digitale Medien
    Digitale Medien
    Signal enhancement by on-column fluorimetric detection in gradient elution of dansyl amino acids in liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 148-152 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; On-column fluorimetric detection ; Gradient elution ; Dansyl amino acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Fluorimetric detection in the presence of a stationary phase has been applied to gradient elution of dansyl amino acids in liquid chromatography. A 1.5 mm ID quartz tube packed with the same materials as the separation column was employed for the flow cell. Conventional-size columns were employed. The peak height of analytes increased with increasing retention owing to focusing and environmental effects of the stationary phase, leading to improvements in sensitivity, which was pronounced for analytes eluting late. The lower the gradient, the larger the improvement in sensitivity achieved. Detection limits were improved by a factor of up to 5.1 by fluorimetric detection using the packed flow cell, compared with those achieved using a common empty flow cell.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267946
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  • 64
    Digitale Medien
    Digitale Medien
    A study of the behaviour of some new column materials in the chromatographic analysis of Cinchona alkaloids (1995)
    Springer
    Chromatographia 41 (1995), S. 153-160 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; LC-MS ; Cinchona alkaloids ; New column packing materials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A major problem in the HPLC analysis of alkaloids is the poor peak shape and consequently low resolution, due to the interactions of the basic alkaloids with the residual acidic silanol groups of most reversed phase materials. The performance of new packing materials specially designed for the separation of basic compounds has been studied using mobile phases without the special additives commonly applied in the analysis of alkaloids. Strongly basic Cinchona alkaloids were used as test compounds. Retention characteristics and selectivities of each material were studied, after mobile phase optimisation for the column. The influence of the major factors (nature and content of the organic modifier, pH value, salt concentration) affecting resolution was studied. The mobile phases were chosen so that they could be used in thermospray LC-MS. The addition of salts to the mobile phase improves separation but in general the modification of the mobile phase gave little change in selectivity. The performance of silicabased C18 material proved superior to the polymer materials tested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267947
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  • 65
    Digitale Medien
    Digitale Medien
    A phylogenetic study of titi monkeys, genusCallicebus, based on cranial measurements: I. Phyletic groups ofCallicebus (1995)
    Springer
    Primates 36 (1995), S. 101-120 
    Details
    ISSN: 0032-8332
    Schlagwort(e): Callicebus ; Multivariate analysis ; Cranial measurements ; Shape factor ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Examinations of 23 forms ofCallicebus were made to elucidate their phylogenetic relationships based on cranial measurements. Multivariate statistical methods of distance analysis utilizing Q-mode correlation coefficients and principal component analysis were employed. As a result, the following five distinct groups were recognized morphometrically among the 23 species and subspecies: theDonacophilus, Cupreus, Moloch, Personatus, andTorquatus groups. Moreover, the phenetic characters of cranial size, karyotype, pelage coloration, and geographic range were consistent with the results of this group classification. It could be safely concluded therefore that these groups represented phylogenetically independent groups, in view of the fact that the rate of character differentiation was not appreciably different among closely related groups. Of the five groups, thePersonatus andTorquatus groups were respectively considered to maintain a higher peculiarity of character differentiation within theCallicebus phylogeny, since these two groups individually displayed the higher magnitudes of differentiation in both their craniometric shape and some phenetic features. Conversely, the other three groups were considered to be closer to each other in theCallicebus phylogeny.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02381918
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  • 66
    Digitale Medien
    Digitale Medien
    Ecomorphological diversification and convergence in fluvial cichlid fishes (1995)
    Springer
    Environmental biology of fishes 44 (1995), S. 235-261 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Adaptive radiation ; Convergent evolution ; Costa Rica ; Diet ; Phylogeny ; Venezuela ; Zambia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis We compared ecological and morphological patterns among cichlid faunas from three different biotic regions: the Río Tortuguero/Rio Sarapiquf in Costa Rica, the Río Apure drainage in Venezuela, and the Upper Zambezi drainage in Zambia. Cichlids comprise 19 percent of the fish fauna in the Tortuguero and Upper Zambezi drainages and 6.5 percent in the Apure drainage. Cichlid faunas exhibited similar patterns of habitat and food resource utilization, although vegetation-dwelling is more common and detritivory and herbivory are rarer in the Apure fauna. We hypothesize that South American ostariophysan fishes were more preadapted than cichlids to exploit detritivore and herbivore niches. The Zambezi cichlid fauna shows less ecomorphological diversification than the other two faunas, even though the degree of dietary diversification is similar among faunas. Chaetobranchus flavescens from the Venezuelan fauna is the only species that specializes on zooplankton as an adult, and algae grazing (Neetroplus nematopus) and specialized fruit feeding (‘Cichlasoma’ tuba) were represented only in the Costa Rican fauna. Based on the most recent hypothesized phylogeny for the family Cichlidae, we identified numerous interfaunal ecomorphological and feeding niche convergences. Patterns of ecomorphological divergence in relation to cladogenesis indicate a faster rate of evolutionary niche diversification in Central American cichlids compared with the two other faunas.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005919
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  • 67
    Digitale Medien
    Digitale Medien
    The phylogenetic relationships ofEeniella nana Smith, Batenburg-van der Vegte et Scheffers based on the partial sequences of 18S and 26S ribosomal RNAs (Candidaceae) (1995)
    Springer
    Journal of industrial microbiology and biotechnology 14 (1995), S. 456-460 
    Details
    ISSN: 1476-5535
    Schlagwort(e): Eeniella nana ; rRNA partial sequences ; Taxonomy ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Summary Two strains ofEeniella nana were examined for their partial base sequences of 18S and 26S rRNAs. In the partial base sequences of 18S rRNA (prositions 1451 through 1618, 168 bases) the strains ofE. nana have five, five, four and eleven base differences with those ofDekkera bruxellensis (type species).D. anomala (andBrettanomyces anomalus),D. naardenensis andD. custersiana, respectively. In the 26S rRNA partial base sequencings (positions 1611 through 1835, 225 bases and positions 493 through 622, 130 bases) the base differences were 46, 43, 34 and 40 and the percent similarities were 53–54, 51–54, 56–57 and 51–53, respectively. The sequence data obtained are discussed phylogenetically and taxonomically, especially on retention of the generic nameEeniella.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01573957
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  • 68
    Digitale Medien
    Digitale Medien
    Ecomorphological correlates in ten species of subtropical seagrass fishes: diet and microhabitat utilization (1995)
    Springer
    Environmental biology of fishes 44 (1995), S. 37-60 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Tampa Bay ; Morphology ; Feeding ; Phylogeny ; Convergence ; Specialization Synopsis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis Ecomorphological correlates were sought among ten species of distantly related subtropical seagrass fishes. Morphometric data associated with feeding and microhabitat utilization were compared by principal components analysis, cluster analysis, and canonical correspondence analysis to dietary data. Morphology was generally a poor predictor of diet except for a group of mid-water planktotrophic filter feeders. Separation of the species along morphological axes appears to be related more to microhabitat utilization resulting in three major groups: (1) a group of planktotrophic, mid-water fishes specialized for cruising and seeking out evasive prey characterized by a compressed fusiform body, forked caudal fin, long, closely spaced gill rakers, short to intermediate! length pectoral fin, pointed pectoral fin, large lateral eye, short head, and a terminal or subterminal mouth; (2) slow swimming, less maneuverable epibenthic fishes that pick or suck their prey off the substrate. They are united by more rounded caudal and pectoral fins, and short or no gill rakers; and (3) a group of more mobile and maneuverable epibenthic foragers characterized by a more compressed, sub-gibbose body, long, pointed pectoral fins, forked caudal fins, large lateral eyes, subterminal mouth, and greater jaw protrusibility. Cases of convergence in trophic and microhabitat utilization characters were apparent in some of the groups.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005906
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  • 69
    Digitale Medien
    Digitale Medien
    Perspectives on the ecomorphology of bony fishes (1995)
    Springer
    Environmental biology of fishes 44 (1995), S. 11-20 
    Details
    ISSN: 1573-5133
    Schlagwort(e): Morphology ; Ecology ; Form ; Biological role ; Performance ; Ontogeny ; Optimization ; Phylogeny ; Constraints ; Adaptation ; Fundamental niche ; Realized niche
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Synopsis The field of ecomorphology has a long history with early roots in Europe. In this half of the century the application of ecomorphology to the biology of fishes has developed in the former Soviet Union, Poland and Czechoslovakia, The Netherlands, and in North America. While the specific approaches vary among countries, many North American studies begin by comparing morphological variation with variation in ecological characteristics at the intra or interspecific levels. These initial correlative studies form the ground work for hypotheses that explore the mechanistic underpinnings of the observed ecomorphological associations. Supporting these mechanistic hypotheses are insights from functional studies which demonstrate the limits to potential resource use resulting from a particular morphology; however, the actual resource use is likely to be more limited due to additional constraints provided by internal (e.g., behavior, physiology) and external (e.g., resource abundance, predator distribution) factors. The results from performance studies in the laboratory or field can be used to test specific ecomorphological hypotheses developed from the initial correlational and functional studies. Such studies may, but rarely do, incorporate an ontogenetic analysis of the ecomorphological association to determine their effect on performance. Finally, input from phylogenetic analyses allow an investigator to examine the evolution of specific features and to assess the rates and directionality of character evolution. The structural and ecological diversity of fishes provides a fertile ground to investigate these interactions. The contributions in this volume highlight some of the specific directions for ecomorphological research covering a variety of biological processes in fishes. These include foraging, locomotion, reproduction, respiration, and sensory systems. Running through these papers are new insights into universal ecomorphological issues, i.e., the relationships between form and ecological role and the factors that modify these relationships.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00005904
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  • 70
    Digitale Medien
    Digitale Medien
    Determination of vitamin A in pharmaceutical preparations by high-performance liquid chromatography with diode-array detection (1995)
    Springer
    Chromatographia 40 (1995), S. 143-146 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Diode-array detection ; Retinol acetate ; Pharmaceutical preparations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A very simple high-performance liquid chromatographic method for determination of Vitamin A in pharmaceutical preparations without the need for saponification was developed. A reversed-phase (Nova-Pack C18, 4 μm) column was used with a mobile phase of acetonitrile-tetrahydrofuran-water (55∶37∶8) and a flowrate of 1.5 ml/min. Sample treatment only consisted of the extraction of retinol acetate content from capsules or tablets with methanol. Total extraction was achieved by shaking vigorously with the aid of magnetic stirring for three hours at room temperature. No change of solvent is necessary to introduce the sample in the chromatographic system. This method is suitable for routine quantification of Vitamin A.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02272162
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  • 71
    Digitale Medien
    Digitale Medien
    Thermodynamic behavior of mixed benzodiazepines by a new liquid chromatographic method (1995)
    Springer
    Chromatographia 40 (1995), S. 193-196 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Chemometric methodology ; Elution order ; Simplex optimization ; Benzodiazepines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Using a rapid chemometric methodology to determine the separation factor, α, at different temperatures, Gibbs Helmholtz parameters (Δ (ΔH), Δ (ΔS), Δ (ΔG)) of two adjacent benodiazepines on a chromatogram were obtained from ln α versus T−1 plots. A temperature dependent reversal of the elution order was studied and the mobile phase composition and column temperature were optimized to obtain the best separation. A flow rate of 0.80 ml min−1 with 52.6% methanol in the methanol-water mixture and a column temperature of 48°C gave the most efficient separation of ten benzodiazepines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02272170
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  • 72
    Digitale Medien
    Digitale Medien
    Mixed-mode liquid chromatography of aliphatic anionic surfactants with a naphthalenetrisulfonate mobile phase (1995)
    Springer
    Chromatographia 40 (1995), S. 237-246 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Mixed mode stationary phases ; Indirect photometric and fluorometric detection ; Conductimetric detection ; Alkyl-sulphates, and sulphonat-phosphates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Separation of three classes of anionic surfactants (alkyl sulfates, alkanesulfonates, and alkyl phosphates) are achieved on a mixed-mode reversed phase (RP) phenyl/-anion exchange column using a naphthalenetrisulfonate (NTS)-acetonitrile (ACN) mobile phase via indirect photometric, indirect fluorometric, direct or indirect conductivity detection. Mixtures of C5−C18 sulfates, C6−C18 sulfonates, and C1−C4 phosphates (mono- and di-ester) can be separated in less than 20, 24, and 20 min respectively. Although hydrophobic effects are more pronounced in mixed-mode chromatography, equivalent-per-equivalent exchange of analysis and eluent ion is still required for sensitive indirect photometric, fluorometric, or conductivity detection. The detection limits of alkyl sulfates and alkanesulfonates are in the range of 3–15 pmoles which are at least an order of magnitude better than suppressed conductivity detection. The determination of surfactants in a variety of real samples is also presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290352
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  • 73
    Digitale Medien
    Digitale Medien
    Enantiomeric separation of D/L-carnitine using HPLC and CZE after derivatization (1995)
    Springer
    Chromatographia 40 (1995), S. 287-295 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Capillary zone electrophoresis ; Enantioseparation ; Carnitine ; Derivatization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Carnitine is an essential component in tissues of animals, higher plants and many microorganisms. Whereas the L-carnitine enantiomer plays an important role in the metabolism of long chain fatty acids, D-carnitine has a considerable toxic influence on biochemical processes. The analytical separation of D-and L-carnitine depends upon derivatization with UV-or fluorescently active substances, e.g. FMOC and (+)/(−)-FLEC. The separation of diastereomeric (+)- and (−)-FLEC carnitine esters was performed successfully with capillary zone electrophoresis (CZE) and HPLC, after optimization of the derivatization process and of the composition and pH of the buffer, using UV- and fluorescence detection. With HPLC separation a detection limit of the carnitine esters of 5 μmol/l when using fluorescence detection was achieved. With both separation systems baseline resolution and short analysis times could be obtained. The enantiomeric FMOC derivatives could be separated using the electrophoretic system and acidic buffers with high concentrations of an osmotic flow modifier together with γ-cyclodextrine as chiral selector. The applicability of the optimized separation conditions are demonstrated in the analysis of agar culture medium inoculated withPseudomonas putida and of pharmaceutical formulations. In all samples very low amounts of D- or L-carnitine could be determined in the presence of the other enantiomeric form. Problems caused by the impurity of the carnitine standards or the derivatization agent (+)/(−)-FLEC are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290359
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  • 74
    Digitale Medien
    Digitale Medien
    Retention of fullerenes by octadecyl silica. Correlation with NMR spectra at low temperatures (1995)
    Springer
    Chromatographia 40 (1995), S. 507-512 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Fullerenes ; Retention vs NMR spectra ; C18 phases ; Low temperature separations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The temperature effect on the retention of fullerenes in the range 80°C to −70°C in liquid chromatography (LC) has been examined using octadecylsilica stationary phases (ODS). It has been found that the maximum retention temperature lies around −10°C with a highly carbon loaded ODS phase. Solid state CPMAS NMR measurements on the stationary phases indicated that the relaxation time at the 30 ppm methylene signal changes with the temperature and has a minimum relaxation time at the temperature which closely matches the maximum retention temperature observed in chromatography. The interpretation of both NMR spectroscopic and LC chromatographic data are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290260
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  • 75
    Digitale Medien
    Digitale Medien
    Derivatisation of DL-amino acids by urethane — Protected α-amino acidN-carboxyanhydrides for separation by LC (1995)
    Springer
    Chromatographia 40 (1995), S. 601-606 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Amino acid analysis ; Chirality ; Diastereoisomers ; Dipeptides
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Using a robotic autosampler, free DL-amino acids were derivatized with highly reactive, urethane-protected, L-α-amino acidN-carboxyanhydrides (NACs) with structures: Boc-Phe-NCA, Boc-Asn(Trt)-NCA, Fmoc-Lys(Boc)-NCA, Fmoc-Met-NCA, Fmoc-Ala-NCA, Z-Ala-NCA, Z-Val-NCA and Z-Leu-NCA (Boc=tert-butyloxycarbonyl, Trt=trityl, Fmoc=9-(fluor-enylmethyl)oxycarbonyl, Z=benzyloxycarbonyl). Using sodium borate buffer and acetonitrile solvent, derivatization was complete in 3.5 min at room temperature. By selection of an appropriate reagent, the resulting diastereomeric,N-protected dipeptides were separated on an octylsilica stationary phase using mixtures of sodium acetate buffer and acetonitrile as eluents.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290275
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  • 76
    Digitale Medien
    Digitale Medien
    High-performance liquid chromatography of dihydroxyacetone as its bis-2,4-dinitrophenylhydrazone derivative (1995)
    Springer
    Chromatographia 41 (1995), S. 61-65 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Dihydroxyacetone ; 2,4-dinitrophenylhydrazine ; Tanning creams
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A rapid and simple HPLC method for the identification and determination of dihydroxyacetone, a tanning agent widely used in a variety of preparations, is presented. The method consists of the analysis of the formulated products after a derivatization reaction which enhances the response and the detection limit of the chromatographic analysis. The characterization and the elucidation of the spacial geometry of the synthesized derivative are described.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02274196
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  • 77
    Digitale Medien
    Digitale Medien
    High performance liquid chromatographic analysis of Patent Blue V in cheese (1995)
    Springer
    Chromatographia 41 (1995), S. 431-434 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Thin-layer chromatography ; Patent Blue V in cheese
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The HPLC method developed for the analysis of the dye Patent Blue V in extracts from cheese is sufficiently sensitive to detect and measure concentrations above 0.1 ppm with a standard deviation of 3%. The extraction procedure described gives a recovery from cheese of about 80%. The method has been applied to commercial samples of cheese and a concentration of the dye of about 0.12 ppm was measured in one case.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318618
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  • 78
    Digitale Medien
    Digitale Medien
    Modelling and prediction of retention in high-performance liquid chromatography by using neural networks (1995)
    Springer
    Chromatographia 41 (1995), S. 435-444 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Micellar liquid chromatography ; Neural networks ; Retention modelling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Multi-layer feed-forward neural networks trained with an error back-propagation algorithm have been used to model retention behaviour of liquid chromatography as a function of the composition of the mobile phases. Conventional hydro-organic and micellar mobile phases were considered. Accurate retention modelling and prediction have been achieved using mobile phases defined by two, three and four parameters. With micellar mobile phases, the parameters involved included the concentrations of surfactant and organic modifier, pH and temperature. It is shown that neural networks provide a competitive tool to model varied inherent nonlinear relationships of retention behaviour with respect to the mobile phase parameters. The soft models defined by the weights of the networks are capable of accommodating all types of linear and nonlinear relationships, neural networks being specially useful when the relationships between retention behaviour and the mobile phase parameters are unknown. However, to train neural networks more experimental points than with hard-modelling methods are required, hence the use of the networks is recommended only for those cases where adequate theoretical or empirical models do not exist.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318619
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  • 79
    Digitale Medien
    Digitale Medien
    Simultaneous assay of four stereoisomers of diltiazem hydrochloride. Application to in vitro chiral inversion studies (1995)
    Springer
    Chromatographia 41 (1995), S. 450-454 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Diltiazem hydrochloride stereoisomers ; Chiralcel OF ; Chiral inversion ; Epimerization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The simultaneous stereospecific assay of four stereoisomers of diltiazem hydrochloride in bulk drug and aqueous solution was developed using HPLC on a Chiralcel OF column. The four isomers were quantitated with good precision by the internal standard method. The chiral inversion of (+)-cis-diltiazem hydrochloride in vitro, stability of its (2S, 3S) configuration in the solid and aqueous states was examined by HPLC. Chiral inversion of (+)-cis-diltiazem hydrochloride was not observed in the solid state, and its (2S, 3S) configuration was stable to heat, humidity and light. Chiral inversion of (+)-cis-diltiazem hydrochloride (2S, 3S) was observed in aqueous solution under UV, but not in aqueous solution stored at 80°C for 5h nor under visible light for 10 h. The (+)-cis-diltiazem hydrochloride (2S, 3S) epimerized to (+)-trans-diltiazem hydrochloride (2R, 3S) with a half-life of 5h in aqueous solution under UV but the reverse chiral inversion of (+)-trans-diltiazem hydrochloride (2R, 3S) to (+)-cis-diltiazem hydrochloride (2S, 3S) was not observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318621
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  • 80
    Digitale Medien
    Digitale Medien
    Detoxification of acetonitrile-water wastes from liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 488-491 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Acetonitrile disposal ; Acetonitrile hydrolysis ; Degradation kinetics ; Waste solvent management
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Acetonitrile is one of the most frequently used solvents in column liquid chromatography. Because of its toxicity, safe disposal of the waste solvent is essential. Combustion in a hazardous waste plant, if available, is recommended. Otherwise the waste can be degraded in the laboratory to acetic acid and ammonia by treatment with sodium hydroxide. The addition of hydrogen peroxide is not necessary. The waste needs to be diluted to 10% acetonitrile in water in order to prevent the formation of a two-phase system on addition of concentrated sodium hydroxide. This reagent must be added in excess; 2.5 mols of sodium hydroxide per mol of acetonitrile are recommended. It was found that the kinetics are of second order, with an activation energy of 89 kJ mol−1 and a frequency factor of 9×109. Therefore even at room temperature degradation is possible, although a hydrolysis time of approximately 15 days is needed under these conditions. At 80°C, where refluxing is not necessary, hydrolysis is complete after, e.g., 2 h, depending on the amount of sodium hydroxide added.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318626
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  • 81
    Digitale Medien
    Digitale Medien
    Retention behaviour of metal complexes with 5-sulphoquinoline-8-ol in reversed-phase ion-pair liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 532-538 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Ion-pair LC ; 5-Sulphoquinoline-8-ol ; Metal complexes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The reversed-phase ion-pair liquid chromatographic behaviour of several metal complexes with 5-sulphoquinoline-8-ol (HQS) on an octadecyl-modified silica column was investigated by using a fluorescence detector. The aluminum complex gave two peaks on the chromatograms when eluents containing phosphate buffer were used. The effects of the pH of the eluent, HQS concentration, the nature of anions in the eluent, and the column temperature on the retention behaviour of the aluminum complex are discussed on the basis of the equilibria and the kinetics of the complexation of the aluminum ion with HQS and anions in the eluent. The equilibrium constant for the interconversion reaction between the two Al(III)-HQS species which correspond to the two peaks observed and the second stepwise formation constant for the Zn(II)-HQS complex were evaluated from the HPLC data obtained.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269716
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  • 82
    Digitale Medien
    Digitale Medien
    Liquid chromatographic determination of aniline and derivatives in environmental waters at nanogram per litre levels using fluorescamine pre-column derivatization (1995)
    Springer
    Chromatographia 41 (1995), S. 568-572 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Fluorescamine derivatives ; Aniline and aniline derivatives ; Environmental waters
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Fluorescamine (fluram) has been used as a fluorogenic compound for pre-column derivatization of aniline and some derivatives. Anilines were derivatized with fluram in citrate buffer media (pH 5.5) to form pyrrolinones. The highly fluorescence pyrrolinones were isolated and pre-concentrated by solid phase extraction. A reversed phase, Spherisorb RP-8 column and tetrahydrofuran: water:formic acid (42∶56∶2) mobile phase was used for separation. Detection method was by a sensitive fluorimetric method and quantitation was at 395 and 495 nm. The various parameters such as reaction conditions between anilines and fluram, solid phase extraction and chromatographic separation were optimized. Calibrations were linear over the range considered with excellent correlation coefficients (r〉0.999). Relative standard deviations are less than 2.5% and detection limits for aniline,p-toluidine, 4-chloroaniline and 4-bromoaniline were 6, 30, 6 and 8 ng L−1, respectively. This method has been used successfully for the determination of anilines in environmental waters.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269721
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  • 83
    Digitale Medien
    Digitale Medien
    Separation of saponins and determination of quinovic acid 3-O-α-L-rhamnopyranoside fromNauclea diderrichii (de Wild) Merr. Bark by high performance liquid chromatography (1995)
    Springer
    Chromatographia 41 (1995), S. 581-584 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Nauclea diderrichii (de Wild) Merr ; Saponins ; Alkaloid glycoside ; Chrysanthelline A
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A reversed-phase HPLC determination of 11 saponins and an alkaloid glycoside inNauclea diderrichii bark is described. Quantitative analysis of quinovic acid 3-O-α-L-rhamnopyranoside which is one of the main saponins was determined, using Chrysanthelline A as internal standard. The complete separation was achieved in 47 minutes. The method of quantification was validated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269723
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  • 84
    Digitale Medien
    Digitale Medien
    Quantitative determination of toxic mono- and non-ortho polychlorinated biphenyls in cod liver oil after selective liquid chromatographic separation (1995)
    Springer
    Chromatographia 41 (1995), S. 585-593 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Gas chromatography ; Column liquid chromatography ; Polychlorinated biphenyls ; Cod liver oil
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary By application of a chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269724
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  • 85
    Digitale Medien
    Digitale Medien
    Enantiomeric separation of trimetoquinol, denopamine and timepidium by capillary electrophoresis and HPLC and the application of capillary electrophoresis to the optical purity testing of the drugs (1995)
    Springer
    Chromatographia 40 (1995), S. 638-644 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Capillary electrophoresis ; Enantiomer separation ; Trimetoquinol ; Denopamine ; Timepidium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two methods for the direct separation of the enantiomers of trimetoquinol hydrochloride, denopamine and timepidium bromide were investigated, namely capillary zone electrophoresis (CZE) using cyclodextrins (CDs) (CD-CZE) and high-performance liquid chromatography (HPLC) using chiral stationary phases (CSPs). By CZE, separation of the enantiomers of trimetoquinol was successfully achieved when using β-cyclodextrin (β-CD), heptakis(2,6-di-0-methyl)-β-cyclodextrin (DM-β-CD) and β-CD polymer, but direct HPLC separation of the enantiomers was not successful. The enantiomers of denopamine were successfully separated by both CZE, employing DM-β-CD under acidic conditions, and HPLC, with cyclodextrin immobilized CSPs (CD-CSPs). Timepidium bromide, which is a racemic drug, was successfully enantioseparated by both CD-CZE and HPLC with CD-CSPs. The CD-CZE mode was selected as the optical purity testing method for trimetoquinol and denopamine because of the superiority of capillary electrophoretic (CE) techniques. Method validation results obtained clearly show that the CE method would be useful as an quality control method for assessing the optical purity of the drugs.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315130
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  • 86
    Digitale Medien
    Digitale Medien
    Effects of kinematic viscosity of the slurry on the packing efficiency of PEEK microbore columns for liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 662-668 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Microbore columns ; Column packing ; Slurry viscosity ; Surfactants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The kinematic viscosity of the slurry used for the packing of microbore columns for liquid chromatography has been correlated with the packing efficiency. The columns were packed into polyetheretherketone (PEEK) tubing with an internal diameter of 0.5 mm using unbonded and bonded spherical silica gels under constant pressure conditions. Higher efficiencies were obtained using slurries suspended in aqueous solutions of surfactants, such as polyoxyethylene sorbitane monolaurte (Tween-20) and sodium dodecyl sulphate, in comparison with organic solvents usually used for column packing. The concentration dependencies of the relative kinematic viscosities of six slurries were compared using capillary viscometry. The slurries with low relative viscosities possessed rheological properties which enabled high packing densities, typical of a stable dense random packing arrangement, to be obtained at moderate packing pressures. The unusually low relative viscosities are discussed in terms of a “porous hydrodynamic bearing” model. The techniques used should also be generally applicable to the slurry packing of conventional columns.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315134
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  • 87
    Digitale Medien
    Digitale Medien
    Effect of pH on the retention behaviour of some preservatives-antioxidants in reversed-phase high-performance liquid chromatography (1995)
    Springer
    Chromatographia 40 (1995), S. 652-656 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Preservatives-antioxidants ; Eluent pH ; Retention and separation factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary In this paper the dependence of eluent pH on the efficiency of separation in RP-HPLC is described. Preservatives-antioxidants, esters ofp-hydroxybenzoic acid (methyl, ethyl, propyl and butyl parabens), sorbic acid, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG) and L-ascorbic acid (Vitamine C) were investigated by reversed-phase high-performance liquid chromatography, utilising isocratic elution with UV detection. The mobile phase composition (methanol-water v/v containing 1% acetic acid), was varied in order to obtain the best separation. For all substances analysed the pH, pKa and the fitted pKa values were calculated in different mixtures of mobile phases using the graphical method of Charlot and Trémillon [1]. The retention factors (k) and the separation factors (α) were also calculated.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315132
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  • 88
    Digitale Medien
    Digitale Medien
    Evaluation of the loadability of an immobilised protein chiral stationary phase (1995)
    Springer
    Chromatographia 40 (1995), S. 680-683 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Chiral stationary phase ; Preparative chromatography ; Benzodiazepines
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary High performance liquid chromatography chiral stationary phases based on immobilized proteins are well known and commonly used. This work reports on an evaluation of a Human Serum Albumin stationary phase in the preparative separation of benzodiazepines.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02315137
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  • 89
    Digitale Medien
    Digitale Medien
    An HPLC screening method for the detection of isonicotinic acid hydrazide in cattle milk (1995)
    Springer
    Chromatographia 40 (1995), S. 170-174 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Isoniazid in milk ; SPE preconcentration ; Diode array UV spectra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A simple, fast, accurate and highly sensitive (5 ng/ml) method for the detection of sionicotinic acid hydrazide (isoniazid) in cattle milk is described, based upon an RP-HPLC system, equipped with a C18 column and a UV detector. Milk was deproteinized with trichloroacetic acid and treated with cinnamaldehyde, before being injected into the HPLC system. Preconcentration of samples on an SPE phenyl cartridge allows the sensitivity of the method to be increased to 0.05 ng/ml using a UV detector. The presence of isoniazid can be confirmed at concentrations as low as 0.4 ng/ml, through a diode-array UV spectrum of isoniazid hydrazone. The analytical procedure here described is routinely applied to investigate the illegal administration of isoniazid to cattle, as it provides a means of screening that can be carried out in a very short time.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02272167
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  • 90
    Digitale Medien
    Digitale Medien
    Description of the retention behaviour of solutes in micellar liquid chromatography with organic modifiers: Comparison of two methods (1995)
    Springer
    Chromatographia 40 (1995), S. 279-286 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Micellar liquid phases ; Hybrid mobile phases ; Retention behaviour
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Two methods for the description of the retention behaviour of solutes in micellar liquid chromatography are compared. One of them divides the parameter space into triangular subspaces, fitting a different equation in each subspace. The second method makes use of a unique equation, valid in the whole parameter space. In both cases, equations of the type log k=f (μ, ϕ), and 1/k=f (μ, ϕ), (μ and ϕ are the concentration of surfactant and alcohol, respectively), were used to describe the retention. The use of the hyperbolic function, 1/k=c0+c1μ+c3μϕ, to describe the whole parameter space yielded the best prediction. When a small portion of the parameter space was modelled, a simpler hyperbolic function, lacking the μϕ term often led to good results. The logarithmic equations usually gave the poorer predictions.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290358
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  • 91
    Digitale Medien
    Digitale Medien
    Use of high speed liquid chromatography (HSLC) in the pharmaceutical industry. Practical aspects and limitations (1995)
    Springer
    Chromatographia 40 (1995), S. 394-398 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; High speed LC ; Pharmaceutical drugs ; Routine analysis ; Fast HPLC
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary High performance liquid chromatography (HPLC) is widely used in drug development and quality control. The main objective is to obtain dependable results in the shortest time in order to reduce the time taken to develop drugs and to ensure better quality of the final compound. High speed liquid chromatography (HSLC) helps us to reach this objective. In this paper pratical aspects of HSLC are discussed mainly in terms of instrument requirements and the practical needs of users. Comparison between HPLC and HSLC separations of pharmaceutical preparations are given and discussed. The contribution of HSLC to decrease solvent consumption and consequently analysis cost and its role in reducing environmental pollution, are also mentioned.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269901
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  • 92
    Digitale Medien
    Digitale Medien
    Indirect photometric detection of inorganic anions by microcolumn liquid chromatography using anthraquinone-disulfonate as visualization agent (1995)
    Springer
    Chromatographia 40 (1995), S. 379-381 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Indirect photometric detection ; Anthraquinone-disulfonate ion ; Inorganic anions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Disodium salts of several anthraquinone-disulfonic acids, which possess large molar absorptivity, were employed as the visualization agent for microcolumn ion chromatography with indirect photometric detection. Detection limits of inorganic anions were improved, e.g., concentration detection limits of chloride, nitrate and sulfate were 0.91–1.6 μmol L−1 at S/N=3, corresponding to mass detection limits of 18–32 fmol. The present system was applied to the determination of inorganic anions in tap water.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269898
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  • 93
    Digitale Medien
    Digitale Medien
    Determination of biogenic amines in wine after clean-up by solid-phase extraction (1995)
    Springer
    Chromatographia 40 (1995), S. 404-410 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Solid-phase extraction ; Wine ; Biogenic amines ; Phthalaldehyde
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A suitable method for the determination of 16 biogenic amines in wine has been developed. The method involves clean-up of wine samples using ion-exchange cartridges and a preconcentration step, under controlled vacuum, before derivatization of the amines by treatment with phthalaldehyde (PA) and reversedphase HPLC with gradient elution and fluorimetric detection. Linearity of response was obtained for all the biogenic amines from 100 μg L−1 to mg L−1. Limits of detection for the amines were similar for all PA-derivatives (25–50 μg L−1) and the quantitation limits were about 0.1 mg L−1. After clean-up and preconcentration, the concentration levels increased 10-fold for all amines except putrescine and cadaverine, which gave poor recovery by this method unlike the rest which gave recoveries of almost 90%. The overall process was successfully applied to identify and quantify biogenic amines in several red wines from the Tarragona region.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269903
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  • 94
    Digitale Medien
    Digitale Medien
    Elution behaviour of anions and cations on a mixed-bed stationary phase of anion and cation exchange resins (1995)
    Springer
    Chromatographia 40 (1995), S. 539-544 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Mixed-bed stationary phase ; Anion and cation exchange resins ; Retention mechanism of anions and cations
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary The retention mechanism of anions and cations on a mixed-bed column packed with a mixture of strong anion and cation exchange resins has been studied. Organic acids and inorganic anions have showed the same elution behaviour on the mixed-bed column as on a single anion exchange column. In contrast, different elution behaviours for cations have been observed between the mixed-bed column and a single cation exchange column. On the mixed-bed column, cations would be eluted by a mixed retention mechanism. The primary retention mechanism is ion exchange with eluent cation (H+) for all cations. The ion exchange mechanism on the sites occupied by anion exchange groups makes a greater contribution for monovalent cations. A partition mechanism between the stationary phase and mobile phase contributes to the separation of Mg2+ and Ca2+ by forming neutral compounds.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290265
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  • 95
    Digitale Medien
    Digitale Medien
    Highly efficient separations on 5 μm internal diameter open tubular capillaries coated with thick polyacrylate stationary phases (1995)
    Springer
    Chromatographia 40 (1995), S. 587-593 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Open tubular columns ; Cross-linked polyacrylate stationary phases ; Photopolymerization ; PTH-amino acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Fused silica capillaries with an internal diameter of 5 μm were coated with polyacrylate films containing either alkyl or ether functionalities. Polymer networks were created byin situ photopolymerization of acrylic monomers. Capillaries with phase ratios up to 1.3, having excellent separation efficiencies, could be prepared. The performance of these capillaries was demonstrated by the separation of various solute mixtures. Nineteen phenylthiohydantoin (PTH) amino acid derivatives could be separated in less then 10 minutes when using UV detection. Laser Induced Fluorescence detection was used for the separation of polycyclic aromatic hydrocarbons, dansyl (Dns) derivatized amino acids ando-phthalaldehyde (OPA) derivatized aliphatic amines which could be separated with approximately 310,000 plates in less than 3.5 minutes corresponding to around 1500 plates per second.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02290273
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  • 96
    Digitale Medien
    Digitale Medien
    Evaluation of double solid-phase extraction system for determining triazine herbicides in milk (1995)
    Springer
    Chromatographia 41 (1995), S. 178-182 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Solid-phase extraction ; Triazine herbicides ; Milk
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary High-performance liquid chromatography with UV detection was used to determine eight triazine herbicides in milk. Solid-phase extraction was performed using a double trap; first, a nonspecific adsorbent (Carbograph), and then a cation exchanger (SCX). Eluate from the SCX was evaporated to dryness under reduced pressure and redissolved in mobile phase. An aliquot was injected into the chromatography, which was operated isocratically in the reverse-phase mode with UV detection at 225 nm. Analytical recoveries for the eight triazines ranged from 73.0% to 92.4%. The limit of sensitivity of this method was about 0.09 ng mL−1 of milk. The method was validated and evaluated by comparison with a method reported in literature.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267951
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  • 97
    Digitale Medien
    Digitale Medien
    Supercritical fluid extraction-high performance liquid chromatography on-line coupling: Extraction of some model aromatic compounds (1995)
    Springer
    Chromatographia 41 (1995), S. 238-242 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Supercritical fluid extraction ; Column liquid chromatography ; Aromatic compounds on silica
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An SFE-HPLC system has been tested with a simple model aromatic mixture on spiked silica. The spiked silica was extracted with pure CO2 and the extract retained in a trap packed with C18 material. Quantitative separation and reproducity have been investigated and are reported.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02267962
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  • 98
    Digitale Medien
    Digitale Medien
    Ion chromatographic separation of alkylsulphonic acids with conductivity detection (1995)
    Springer
    Chromatographia 41 (1995), S. 445-449 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Ion chromatography ; Alkylsulphonic acids ; Conductivity detection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An ion chromatographic (IC) method has been developed for the separation of alkylsulphonic acid. Two different stationary phases, silica-based and polymer-based ion-exchange resins, were studied using pure ion exchange and/or hydrophobic interaction mechanisms. Correlations between analyte hydrophobicity and eluent polarity were made in order to investigate the possibility of changing the dominant separation mechanism by varying the eluent composition. The alkyl chain lengths of the sulphonic acids analysed ranged from C1 to C9. Detection limits in the submicromolar range were obtained by suppressed conductivity detection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02318620
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  • 99
    Digitale Medien
    Digitale Medien
    High-performance anion-exchange chromatography of carbohydrates using a new resin and pulsed amperometric detection (1995)
    Springer
    Chromatographia 41 (1995), S. 511-515 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Polymeric bonded phase ; Anion-exchange chromatography ; Pulsed amperometric detection ; Carbohydrates
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary This paper reports the results of a study on the use of a new polymer-based, strong anion-exchange, stationary phase for rapid and selective separation of carbohydrates and related compounds by high-pH, anion-exchange chromatography with pulsed amperometric detection. The new adsorbent has been obtained by direct nitration of 2.8 μm, spherical non-porous highly crosslinked, styrene-divinylbenzene copolymer beads, followed by reduction of superficially introduced nitro groups with nascent hydrogen and quaternization of the resultant amino groups with iodomethane. It is reported that by optimizing the ionic strength of the mobile phase, columns packed with the new anion-exchanger can be successfully employed to separate, either in isocratic or gradient elution mode, oligosaccharides, positional isomers of gluco-disaccharides, as well as uronic acids and sugar monophosphates.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269712
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  • 100
    Digitale Medien
    Digitale Medien
    Optimization of a chromatographic method for the gram-scale preparative fractionation of soybean phospholipids (1995)
    Springer
    Chromatographia 41 (1995), S. 527-531 
    Details
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Analytical and preparative scales ; Soybean phospholipids ; Mass detector
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary To enable the study of the functional properties of pure soybean phospholipids, a chromatographic method was developed for the preparative fractionation of soybean lecithin. A coarse and irregularly shaped silica gel was used as the stationary phase, whereas the mobile phase consisted of three mixtures of hexane, 2-propanol and water of increasing polarity. These solvents were included in a step gradient, formed by an isocratic pump connected to a solvent changer. To reduce solvent consumption, the procedure was optimised using a method development column. The solvent program and the sample load were shown to affect mainly the purity and recovery of phosphatidylinositol.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02269715
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