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  • Column liquid chromatography  (523)
  • Drosophila  (308)
  • Calcification
  • Rat
  • Springer  (1,131)
  • MDPI Publishing
  • 1990-1994  (755)
  • 1980-1984  (357)
  • 1965-1969  (19)
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  • 1
    Electronic Resource
    Electronic Resource
    Unrewarding experiences and their effect on foraging in the parasitic waspLeptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 465-481 
    Details
    ISSN: 1572-8889
    Keywords: host selection ; experience ; learning ; extinction ; reinforcement ; parasitoids ; Drosophila ; Leptopilina heterotoma ; Hymenoptera ; Eucoilidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The host-foraging behavior of female entomophagous parasitoids is commonly modified by positive associative learning. Typically, a rewarding experience (e.g., successful oviposition in a host) increases a female's foraging effort in a host microhabitat of the type associated with that experience. Less well understood are the effects of unrewarding experiences (i.e., unsuccessful foraging). The influence of unrewarding experience on microhabitat choice and residence time within a microhabitat was examined for the eucoilid parasitoid,Leptopilina heterotoma, in laboratory and greenhouse assays. As determined previously, females which oviposited successfully in either of two microhabitat types (fermenting apple or decaying mushroom) strongly preferred to forage subsequently on that microhabitat type. However, failure to find hosts in the formerly rewarding microhabitat caused females to reverse their preference in favor of a novel microhabitat type. The effect, though striking, was transient: within 1–2 h, the original learned preference was nearly fully restored. Similar effects of unrewarding experiences were observed with respect to the length of time spent foraging in a microhabitat. As determined previously, oviposition experience in a particular microhabitat type increased the time spent foraging in a patch of that microhabitat type. However, failure to find hosts in the patch caused the time a wasp spent in the next unoccupied patch of that type to decrease to almost nothing. In addition, there was a tendency for an unrewarding experience on a formerly rewarding microhabitat type to extend the time spent in a patch of a novel type. The function of the observed effects of unrewarding experiences is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025444
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  • 2
    Electronic Resource
    Electronic Resource
    Drosophila do not skew offspring sex ratio as predicted by trivers and willard (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 231-239 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; sex ratio ; life history ; optimality model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on both previously published literature and results reported here, it appears thatDrosophila melanogaster meet the explicit assumptions of the Trivers and Willard offspring sex allocation model. However, contrary to the model's predictions, offspring sex ratio was not significantly affected when we manipulated factors that influence offspring quality. We suggest that contrary to implicit predictions of offspring sex ratio models,Drosophila may lack the genetic plasticity to readily alter sex ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01988907
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  • 3
    Electronic Resource
    Electronic Resource
    Egg-laying experience and acceptance of parasitized hosts by the parasitoid,Leptopilina heterotoma (Hymenoptera: Eucoilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 331-342 
    Details
    ISSN: 1572-8889
    Keywords: parasitoid ; superparasitism ; learning ; motivation ; egg load ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The influence of egg-laying experience on the response of females of the eucoilid parasitoid,Leptopilina heterotoma, to parasitized and unparasitizedDrosophila melanogaster host larvae was examined under more controlled conditions than those used in past studies. In laboratory assays, we precisely manipulated both the number of eggs laid by females and the kind of larvae (parasitized versus unparasitized) in which the eggs were laid. We found that the tendency to avoid laying eggs in parasitized hosts depended markedly on whether or not eggs had been laid previously, but depended little on whether those eggs had been laid in parasitized or unparasitized hosts. The observed effect of general egg-laying experience on avoidance of parasitized hosts may reflect responses to either changes in the wasp's internal state (perhaps, changes in egg load) or changes in the wasp's neural representation of the external environment (such as those presumed to occur during learning). In light of these results, we offer a tentative reinterpretation of several earlier studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989362
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  • 4
    Electronic Resource
    Electronic Resource
    Courtship success and multivariate analysis of sexual selection on morphometric traits inDrosophila buzzatii (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 8 (1994), S. 219-229 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; sexual selection gradients ; courtship success
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using wild-reared flies, we examined sexual selection on five phenotypic traits (thorax length, wing length, wing width, head width, and face width) inDrosophila buzzatii, by scoring copulatory status in nine mass mating cages. Only male face width was identified as a direct target of sexual selection in an analysis of selection gradient, while indirect selection was present on all other studied traits, as expected from their correlations with face width. In contrast to males, there was no indication of selection in females. Nor was there evidence of assortative mating. The suggested direct selection on face width seems to take place during licking behavior of the courtship and might be related to courtship feeding. This study suggests that courtship success gives rise to indirect selection on body size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01988906
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  • 5
    Electronic Resource
    Electronic Resource
    Parasitization of embedded and nonembeddedDrosophila melanogaster (Diptera: Drosophilidae) pupae by the parasitoidPachycrepoideus vindemniae (Hymenoptera: Pteromalidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 129-131 
    Details
    ISSN: 1572-8889
    Keywords: Drosophila ; parasitoid wasp ; behavior ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989833
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  • 6
    Electronic Resource
    Electronic Resource
    The effects of acclimation and rearing conditions on the response of tropical and temperate populations ofDrosophila melanogaster andD. simulans to a temperature gradient (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 279-288 
    Details
    ISSN: 1572-8889
    Keywords: temperature preference ; Drosophila ; acclimation ; compensation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of rearing and acclimation on the response of adultDrosophila to temperature were investigated in a gradient.D. melanogaster flies preferred a higher mean temperature and were distributed over a wider range of temperatures thanD. simulans flies. Acclimating adults at different temperatures for a week did not influence the response of either species. Adults reared at 28°C as immatures had a lower mean preference than those reared at cooler temperatures, suggesting that flies compensated for the effects of rearing conditions. Adults from tropical and temperate populations ofD. melanogaster andD. simulans did not differ in the mean temperature they preferred in a gradient, suggesting little genetic divergence for this trait within species. The species differences and environmental responses may be related to changes in optimal physiological conditions for the flies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01989735
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  • 7
    Electronic Resource
    Electronic Resource
    Sensorimotor transformation from light reception to phototactic behavior inDrosophila larvae (Diptera: Drosophilidae) (1994)
    Springer
    Journal of insect behavior 7 (1994), S. 553-567 
    Details
    ISSN: 1572-8889
    Keywords: review ; Drosophila ; larva ; phototaxis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper we examine theDrosophila melanogaster larval response to light. We survey the morphology of the larval visual and motor systems in relation to larval locomotory behavior and phototaxis. In addition, this paper proposes a model of sensorimotor transformation and examines the reversal in taxis occurring at theD. melanogaster larval wnadering stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02025449
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  • 8
    Electronic Resource
    Electronic Resource
    Phylogeny of the Drosophila obscura species group deduced from mitochondrial DNA sequences (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 478-488 
    Details
    ISSN: 1432-1432
    Keywords: Mitochondrial DNA ; Nucleotide sequences ; Drosophila ; Rapid phyletic radiation ; Molecular phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Approximately 2 kb corresponding to different regions of the mtDNA of 14 different species of the obscura group of Drosophila have been sequenced. In spite of the uncertainties arising in the phylogenetic reconstruction due to a restrictive selection toward a high mtDNA A+T content, all the phylogenetic analysis carried out clearly indicate that the obscura group is formed by, at least, four well-defined lineages that would have appeared as the consequence of a rapid phyletic radiation. Two of the lineages correspond to monophyletic subgroups (i.e., afftnis and pseudoobscura), whereas the obscura subgroup remains heterogeneous assemblage that could be reasonably subdivided into at least two complexes (i.e., subobscura and obscura).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173417
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  • 9
    Electronic Resource
    Electronic Resource
    Aspects of nonrandom turnover involved in the concerted evolution of intergenic spacers within the ribosomal DNA of Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 151-159 
    Details
    ISSN: 1432-1432
    Keywords: Concerted evolution ; Molecular drive ; Drosophila ; rDNA spacers ; PCR length polymorphism ; MVR-PCR mapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polymerase chain reaction (PCR)-amplified, sequenced, and digitally typed intergenic spacers (IGSs) of the ribosomal (r)DNA in D. melanogaster reveal unexpected features of the mechanisms of turnover involved with the concerted evolution of the gene family. Characterization of the structure of three isolated IGS length variants reveals breakage “hot spots” within the 330-base-pair (bp) subrepeat array found in the spacers. Internal mapping of variant repeats within the 240-bp subrepeat array using a novel digital DNA typing procedure (minisatellite variant repeat [MVR]-PCR) shows an unexpected pattern of clustering of variant repeats. Each 240-bp subrepeat array consists of essentially two halves with the repeats in each half identified by specific mutations. This bipartite structure, observed in a cloned IGS unit, in the majority of genomic DNA of laboratory and wild flies and in PCR-amplified products, has been widely homogenized yet is not predicted by a model of unequal crossing over with randomly placed recombination breakpoints. Furthermore, wild populations contain large numbers of length variants in contrast to uniformly shared length variants in laboratory stocks. High numbers of length variants coupled to the observation of a homogenized bipartite structure of the 240-bp subrepeat array suggest that the unit of turnover and homogenization is smaller than the IGS and might involve gene conversion. The use of PCR for the structural analysis of members of the rDNA gene family coupled to digital DNA typing provides powerful new inroads into the mechanisms of DNA turnover affecting the course of molecular evolution in this family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00163804
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  • 10
    Electronic Resource
    Electronic Resource
    Degenerating gypsy retrotransposons in a male fertility gene on the Y chromosome of Drosophila hydei (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 452-465 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Y chromosome ; Male fertility genes ; Lampbrush loops ; Germ line ; Transposable elements ; Gypsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract During the evolution of the Y chromosome of Drosophila hydei, retrotransposons became incorporated into the lampbrush loop pairs formed by several of the male fertility genes on this chromosome. Although insertions of retrotransposons are involved in many spontaneous mutations, they do not affect the functions of these genes. We have sequenced gypsy elements that are expressed as constituents of male fertility gene Q in the lampbrush loop pair Nooses. We find that these gypsy elements are all truncated and specifically lost those sequences that may interfere with the continuity of lampbrush loop transcription. Only defective coding regions are found within the loop. Gypsy is not transcribed in loops of many other Drosophila species harboring the family. These results suggest that any contribution of gypsy to the function of male fertility gene Q does not depend on a conserved DNA sequence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173414
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  • 11
    Electronic Resource
    Electronic Resource
    Visual control of wing beat frequency in Drosophila (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 587-596 
    Details
    ISSN: 1432-1351
    Keywords: Wing beat frequency ; Optomotor responses ; Landing response ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present study shows that the wing beat frequency of Drosophila is visually controlled and modulated in response to different optomotor stimuli. Whereas rotational large field stimuli do not appear to modulate wing beat frequency, single rotating vertical stripes increase or decrease wing beat frequency when moving back-to-front or front-to-back, respectively. Maximal modulations occur at lateral stripe positions. Expansion stimuli eliciting the landing response cause a marked increase in wing beat frequency. Parameters of this frequency response depend in a graded fashion on certain stimulus properties, and the frequency response co-habituates with the landing response. Several results indicate that the frequency response is an integral component of the landing response, although it can also occur when the characteristic front leg extension is not observed. The complex spatial input integration underlying the frequency response and other motor components of the landing response cannot easily be explained by a system of large field integration units, but might indicate the existence of local expansion detectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00199480
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  • 12
    Electronic Resource
    Electronic Resource
    Improved stability of Drosophila larval neuromuscular preparations in haemolymph-like physiological solutions (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 179-191 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Neuromuscular ; Haemolymph ; Membrane potential ; Synaptic potential
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neuromuscular preparations from third instar larvae of Drosophila are not well-maintained in commonly used physiological solutions: vacuoles form in the muscle fibers, and membrane potential declines. These problems may result from the Na∶K ratio and total divalent cation content of these physiological solutions being quite different from those of haemolymph. Accordingly haemolymph-like solutions, based upon ion measurements of major cations, were developed and tested. Haemolymph-like solutions maintained the membrane potential at a relatively constant level, and prolonged the physiological life of the preparations. Synaptic transmission was well-maintained in haemolymph-like solutions, but the excitatory synaptic potentials had a slower time course and summated more effectively with repetitive stimulation, than in standard Drosophila solutions. Voltage-clamp experiments suggest that these effects are linked to more pronounced activation of muscle fiber membrane conductances in standard solutions, rather than to differences in passive muscle membrane properties or changes in postsynaptic receptor channel kinetics. Calcium dependence of transmitter release was steep in both standard and haemolymph-like solutions, but higher external calcium concentrations were required for a given level of release in haemolymph-like solutions. Thus, haemolymph-like solutions allow for prolonged, stable recording of synaptic transmission.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215114
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  • 13
    Electronic Resource
    Electronic Resource
    Altered mechanoreceptor response in Drosophila bang-sensitive mutants (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 267-278 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Bang sensitivity ; Mechanotransduction ; Adaptation ; Sensory coding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Bang-sensitive mutants of Drosophila melano gaster (bas 1, bssMW1, eas2, tko25t) display seizure followed by paralysis when subjected to mechanical shock. However, no physiological or biochemical defect has been found to be common to all of these mutants. In order to observe the effects of bang-sensitive mutations upon an identified neuron, and to study the nature of mechanically induced paralysis, we examined the response of a mechanosensory neuron in these mutants. In each single mutant and the double mutant bas 1 bssMW1, the frequency of action potentials in response to a bristle displacement was reduced. This is the first demonstration of a physiological defect common to several of the bang-sensitive mutations. Adaptation of spike frequency, cumulative adaptation to repeated stimulation (fatigue) and the time course of recovery from adaptation were also examined. Recovery from adaptation to a conditioning stimulus was examined in two mutants (bas 1 and bss MW1), and initial recovery from adaptation was greater in both mutants. Quantification of receptor potentials was complicated by variability inherent in extracellular recording conditions, but examination of the waveform and range of amplitudes did not indicate clear mutant defects. Therefore the differences observed in the spike response may be due to an alteration of the transfer from receptor potentials to action potential production. DNA sequence analysis of tko and eas has indicated that they encode apparently unrelated biochemical products. Our results suggest that these biochemical lesions lead to a common physiological defect in mechanoreceptors. Although this defect does not provide a straightforward explanation for bang sensitivity, the altered cellular process may lead to bang sensitivity through its action in different parts of the nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192986
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  • 14
    Electronic Resource
    Electronic Resource
    Speciation in the Artemia genus: Mitochondrial DNA analysis of bisexual and parthenogenetic brine shrimps (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 156-168 
    Details
    ISSN: 1432-1432
    Keywords: Artemia franciscana ; Artemia salina ; Artemia parthenogenetica ; Mitochondrial DNA evolution ; Cytochrome c oxidase I ; Cytochrome b ; Drosophila ; Arthropods ; Parthenogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract From the cloned mitochondrial DNAs (mtDNAs) isolated from two bisexual species, one Mediterranean, Artemia salina, and one American, Artemia franciscana, and two parthenogenetic (diploid and tetraploid) strains of Artemia parthenogenetica collected in Spain, physical maps have been constructed and compared. They are extremely different among themselves, much more than the differences between Drosophila melanogaster and D. yakuba and in the same range of different mammalian species such as mouse/rat or man/cow. The nucleotide sequences of two regions of mtDNA encoding parts of the cytochrome c oxidase subunit I (COI) and cytochrome b (Cytb) genes have been determined in the two bisexual species and the two parthenogenetic strains. Comparisons of these sequences have revealed a high degree of divergence at the nucleotide level, averaging more than 15%, in agreement with the differences found in the physical maps. The majority of the nucleotide changes are silent and there is a strong bias toward transitions, with the C↔T substitutions being highly predominant. The evolutionary distance between the two Artemia parthenogenetica is high and there is no clear relationship with any of the bisexual species, including the one present nowadays in Spain. Using a combination of molecular (mtDNA) and morphological markers it is possible to conclude that all of these Artemia isolates should be actually considered as belonging to different species, even the two Artemia parthenogenetica diploidica and tetraploidica.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00166162
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  • 15
    Electronic Resource
    Electronic Resource
    Interspecific sequence comparison of the muscle-myosin heavy-chain genes from Drosophila hydei and Drosophila melanogaster (1994)
    Springer
    Journal of molecular evolution 39 (1994), S. 357-368 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Muscle-myosin heavy-chain gene ; Alternative exons ; Synonymous substitutions ; Amino acid substitutions ; Evolution ; Testis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The muscle-myosin heavy-chain (mMHC) gene of Drosophila hydei has been sequenced completely (size 23.3 kb). The sequence comparison with the D. melanogaster mMHC gene revealed that the exonintron pattern is identical. The protein coding regions show a high degree of conservation (97%). The alternatively spliced exons (3a-b, 7a-d, 9a-c, 11a-e, and 15a-b) display more variations in the number of nonsynonymous and synonymous substitutions than the common exons (2, 4, 5, 6, 8, 10, 12, 13, 14, 16, 17, and 19). The base composition at synonymous sites of fourfold degenerate codons (third position) is not biased in the alternative exons. In the common exons there exists a bias for C and against A. These findings imply that the alternative exons of the Drosophila mMHC gene evolve at a different, in several cases higher, rate than the common ones. The 5′ splice junctions and 5′ and 3′ untranslated regions show a high level of similarity, indicating a functional constraint on these sequences. The intron regions vary considerably in length within one species, but the corresponding introns are very similar in length between the two species and all contain stretches of sequence similarity. A particular example is the first intron, which contains multiple regions of similarity. In the conserved regions of intron 12 (head-tail border) sequences were found which have the potential to direct another smaller mMHC transcript.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160268
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  • 16
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of the genomic region encompassing Adh and Adh-Dup genes of D. lebanonensis (Scaptodrosophila): Gene expression and evolutionary relationships (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 455-467 
    Details
    ISSN: 1432-1432
    Keywords: Alcohol dehydrogenase ; Drosophila ; Drosophila lebanonensis ; Gene expression ; Codon usage ; Phylogenetic relationships
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The region of the genome of D. lebanonensis that contains the Adh gene and the downstream Adh-dup gene was sequenced. The structure of the two genes is the same as has been described for D. melanogaster. Adh has two promoters and Adh-dup has only one putative promoter. The levels of expression of the two genes in this species are dramatically different. Hybridizing the same Northern blots with a specific probe for Adh-dup, we did not find transcripts for this gene in D. lebanonensis. The level of Adh distal transcript in adults of D. lebanonensis is five times greater than that of D. melanogaster adults. The maximum levels of proximal transcript are attained at different larval stages in the two species, being three times higher in D. melanogaster late-second-instar larvae than in D. lebanonensis first-instar larvae. The level of Adh transcripts allowed us to determine distal and proximal initiation transcription sites, the position of the first intron, the use of two polyadenylation signals, and the heterogeneity of polyadenylation sites. Temporal and spatial expression profiles of the Adh gene of D. lebanonensis show qualitative differences compared with D. melanogaster. Adh and Adh-dup evolve differently as shown by the synonymous and nonsynonymous substitution rates for the coding region of both genes when compared across two species of the melanogaster group, two of the obscura group of the subgenus Sophophora and D. lebanonensis of the victoria group of the subgenus Scaptodrsophila. Synonymous rates for Adh are approximately half those for Adh-dup, while nonsynonymous rates for Adh are generally higher than those for Adh-dup. Adh shows 76.8% identities at the protein level and 70.2% identities at the nucleotide level while Adh-dup shows 83.7% identities at the protein level and 67.5% identities at the nucleotide level. Codon usage for Adh-dup is shown to be less biased than for Adh, which could explain the higher synonymous rates and the generally lower nonsynonymous substitution rates in Adh-dup compared with Adh. Phylogenetic trees reconstructed by distance matrix and parsimony methods show that Sophophora and Scaptodrosophila subgenera diverged shortly after the separation from the Drosophila subgenus.
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    URL: http://dx.doi.org/10.1007/BF00178845
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  • 17
    Electronic Resource
    Electronic Resource
    Drive-selection equilibrium: Homopolymer evolution in the Drosophila gene mastermind (1994)
    Springer
    Journal of molecular evolution 38 (1994), S. 637-641 
    Details
    ISSN: 1432-1432
    Keywords: mastermind ; Drosophila ; Homopolymer ; Repeat length variation ; Molecular drive ; Natural selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Interspecific sequence comparison of the highly repetitive Drosophila gene mastermind (mam) reveals extensive length variation in homopolymer domains. The length variation in homopolymers is due to nucleotide misalignment in the underlying triplet repeats, which can lead to slippage mutations during DNA replication or repair. In mam, the length variation in repetitive regions appears to be balanced by natural selection acting to maintain the distance between two highly conserved charge clusters. Here we report a statistical test of the null hypothesis that the similarity in the amino acid distance between the charge clusters of each species arose by chance. The results suggest that at mam there is a juxtaposition of length variability due to molecular drive and length conservation maintained by natural selection. The analysis of mam allows the extension of current theories of drive-selection interaction to encompass homopolymers. Our model of drive-selection equilibrium suggests that the physical flexibility, length variability, and abundance of homopolymer domains provide an important source of genetic variation for natural populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175884
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  • 18
    Electronic Resource
    Electronic Resource
    Olfactory physiology in the Drosophila maxillary palp requires the visual system gene rdgB (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 687-693 
    Details
    ISSN: 1432-1351
    Keywords: rdgB ; Maxillary palp ; Drosophila ; Electrophysiology ; Olfaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We describe the kinetics of odorant response in the maxillary palp of Drosophila, and show that the rate of recovery from odorant stimulation is affected by mutation of the rdgB (retinal degeneration B) gene. We use immunocytochemistry to confirm that the rdgB gene product is expressed in the maxillary palp. rdgB has recently been shown to encode a protein with Ca2+-binding sites and sequence similarity to rat brain phosphatidylinositol transfer protein; it is located near the rhabdomeric membranes in photoreceptor cells, where it has been suggested to play a role in membrane transport. The delay in recovery kinetics that we observe in olfactory tissue may reflect a defect in membrane restoration at the conclusion of the olfactory transduction cascade. The use of common molecules in the physiology of two olfactory organs, and in both visual and olfactory physiology, is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191841
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  • 19
    Electronic Resource
    Electronic Resource
    Quantifying relative importance of maxillary palp information on the olfactory behavior of Drosophila melanogaster (1994)
    Springer
    Journal of comparative physiology 175 (1994), S. 761-766 
    Details
    ISSN: 1432-1351
    Keywords: Olfactory behavior ; Antenna ; Maxillary palp ; Olfaction ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Maxillary palps have been proposed as secondary olfactory organs, after the antennae, in Drosophila melanogaster. Our study tries to establish the quantitative importance of both organs as olfactory information mediators. Dose-response curves for three odorants: ethyl acetate, propionaldehyde and benzaldehyde were carried out for comparing olfaction in either complete animals or flies surgically deprived of antennae. Antennaless flies tested in our behavioral assay showed indifferent, attractant and repellent responses depending on concentration, similarly as normal flies do. However, they clearly displayed less sensitivity than normal flies. The range of concentrations they were able to perceive was correlated to antennal sensitivity approximately by a factor 1∶10 for ethyl acetate and benzaldehyde, and between 1∶10 and 1∶100 at high concentrations of propionaldehyde. A complementary experiment was performed to test changes in olfactory behavior produced by removing maxillary palps in the presence of antennae. At high concentrations of odorant, responses to ethyl acetate and propionaldehyde experienced small changes when both palps were removed. Results are compatible with a summation model of all olfactory information reaching the brain either through antennae or palps.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191847
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    Renal eicosanoids and blood pressure in genetically hypertensive rats of the lyon strain (1994)
    Springer
    Journal of biomedical science 1 (1994), S. 201-203 
    Details
    ISSN: 1423-0127
    Keywords: Hypertension ; Eicosanoid ; Rat ; Genetics ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The present paper reviews the evidence for a possible involvement of renal eicosanoids in the pathophysiology of high blood pressure in genetically hypertensive rats of the Lyon strain. Both in vivo and in vitro experiments suggest that an increased ability to synthesize the vasoconstrictor prostaglandin H2 and/or thromboxane A2 in renal vessels (1) acts as an autocrine amplifier of pressor agents and (2) may contribute to resetting the pressure natriuresis curve which is a prerequisite for the development and maintenance of hypertension.
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    URL: http://dx.doi.org/10.1007/BF02253302
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    BrdU incorporation reveals DNA replication in non dividing glial cells in the larval abdominal CNS ofDrosophila (1994)
    Springer
    Development genes and evolution 204 (1994), S. 54-61 
    Details
    ISSN: 1432-041X
    Keywords: CNS ; Glia ; Drosophila ; BrdU
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glial cells are of significant importance for central nervous system development and function. In insects, knowledge of the types and development of CNS glia is rather low. This is especially true for postembryonic glial development. Using bromodeoxyuridine incorporation and enhancer trap lines we identified a reproducible spatial and temporal pattern of DNA replicating cells in the abdominal larval CNS (A3-7 neuromeres) ofDrosophila melanogaster. These cells correspond to embryonically established glial cells in that region. Except for a specific subfraction, these cells apparently do not divide during larval life. Similar patterns were found in two otherDrosophila species,D. virilis andD. hydei.
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    URL: http://dx.doi.org/10.1007/BF00744873
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    Drosophila glial development is regulated by genes involved in the control of neuronal cell fate (1994)
    Springer
    Development genes and evolution 204 (1994), S. 118-125 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; glia ; Proneural ; Neurogenic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila proneural genes specify neuronal determination among cells within the ectoderm. Here we address the question of whether proneural genes also affect the specification of glia, the most abundant cell type in the nervous system. We provide evidence that the proneural gene daughterless is essential for the formation of two major classes of PNS glia. In contrast, the proneural genes in the achaete-scute complex have no detectable effect on the specification and differentiation of these PNS glia and certain CNS glia. We also show that, as with neuronal development, glial determination is restricted by the neurogenic genes neuralized, Delta, and the genes of the Enhancer of split complex. Finally, we demonstrate that prospero, a gene involved in neuronal differentiation, also affects glial development. These results demonstrate extensive overlap in the genetic control of glial and neuronal development.
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    URL: http://dx.doi.org/10.1007/BF00361106
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    Embryonic origin and differentiation of the Drosophila heart (1994)
    Springer
    Development genes and evolution 203 (1994), S. 266-280 
    Details
    ISSN: 1432-041X
    Keywords: Heart ; Drosophila ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have followed the normal development of the different cell types associated with the Drosophila dorsal vessel, i.e. cardioblasts, pericardial cells, alary muscles, lymph gland and ring gland, by using several tissue-specific markers and transmission electron microscopy. Precursors of pericardial cells and cardioblasts split as two longitudinal rows of cells from the lateral mesoderm of segments T2-A7 (“cardiogenic region”) during stage 12. The lymph gland and dorsal part of the ring gland (corpus allatum) originate from clusters of lateral mesodermal cells located in T3 and T1/dorsal ridge, respectively. Cardioblast precursors are strictly segmentally organized; each of T2-A6 gives rise to six cardioblasts. While moving dorsally during the stages leading up to dorsal closure, cardioblast precursors become flattened, polarized cells aligned in a regular longitudinal row. At dorsal closure, the leading edges of the cardioblast precursors meet their contralateral counterparts. The lumen of the dorsal vessel is formed when the trailing edges of the cardioblast precursors of either side bend around and contact each other. The amnioserosa invaginates during dorsal closure and is transiently attached to the cardioblasts; however, it does not contribute to the cells associated with the dorsal vessel and degenerates during late embryogenesis. We describe ultrastructural characteristics of cardioblast differentiation and discuss similarities between cardioblast development and capillary differentiation in vertebrates.
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    URL: http://dx.doi.org/10.1007/BF00360522
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    Novel tissue units of regional differentiation in the gut epithelium of Drosopbila, as revealed by P-element-mediated detection of enhancer (1994)
    Springer
    Development genes and evolution 203 (1994), S. 243-249 
    Details
    ISSN: 1432-041X
    Keywords: Gut ; Drosophila ; Compartment ; Regional differentiation ; P-element enhancer detectors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We analysed spatial patterns of expression of a lacZ reporter gene in the gut of Drosophila larvae that had been transformed with a P-element-lacZ vector to identify regional differences in gene expression. lacZ-positive epithelial cells formed distinct domains with discrete transverse and longitudinal boundaries along the gut tube. Boundaries were often found at sites at which morphological boundaries were not obvious. The gut epithelium was subdivided into 36 compartments by the boundaries. We refer to these novel compartments as “tissue compartments”. The lacZ-positive domain of each strain appeared as a single tissue compartment or as a combination of several tissue compartments. The tissue compartment is considered to be a unit of regional differentiation. The spatial organization of the tissue compartments may represent the “floor plan”, determined by genes that control the regional differentiation of this nonsegmental organ.
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    URL: http://dx.doi.org/10.1007/BF00360519
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    The function of the proneural genes achaete and scute in the spatio-temporal patterning of the adult labellar bristles of Drosophila melanogaster (1994)
    Springer
    Development genes and evolution 203 (1994), S. 340-350 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; achaete ; scute ; Taste bristles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sensory precursors for labellar taste bristles develop from the labial disc in three distinct temporal waves occurring at 0 h, 8 h and 14 h of pupal development. In each temporal wave, transcripts for the achaete (ac) and scute (sc) genes are expressed in overlapping patterns in cells of the disc epithelium prior to the appearance of sensory mother cells (SMCs). No bristles form in mutant flies in which the ac and sc genes are absent. When the sc gene alone is deleted, a set of seven bristles fail to form. Pulses of ubiquitous sc + expression during pupal development, in a strain mutant for both ac and sc, can result in flies with all the labellar bristles at their correct positions. sc + pulses at times corresponding to the initiation of each of the waves of SMC specification in the disc was sufficient to restore bristle pattern. Bristles were not induced at ectopic positions and times as a result of the ubiquitous expression of sc +. These results suggest that the proneural genes ac and sc do not themselves set the pattern of the labellar bristles. Instead, they are required for the elaboration of the pattern set by other gene products. We also show that the formation and positioning of the later waves of bristles can take place even in the absence of bristles normally specified earlier.
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    URL: http://dx.doi.org/10.1007/BF00457805
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    Fate-mapping in the procephalic region of the embryonic Drosopbila head (1994)
    Springer
    Development genes and evolution 203 (1994), S. 367-373 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Embryogenesis ; Morphogenetic movements ; Brain ; HRP
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using intracellular horseradish peroxidase injection we traced the developmental fate of early gastrula cells of the procephalic region in the stage 16/17 embryo. Morphogenetic movements in the developing brain are described in three dimensions. The results are related to head segmentation, and an early gastrula fate map of pregnathal head segments is proposed.
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    URL: http://dx.doi.org/10.1007/BF00188684
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    BrdU incorporation reveals DNA replication in non dividing glial cells in the larval abdominal CNS of Drosophila (1994)
    Springer
    Development genes and evolution 204 (1994), S. 54-61 
    Details
    ISSN: 1432-041X
    Keywords: CNS ; Glia ; Drosophila ; BrdU
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Glial cells are of significant importance for central nervous system development and function. In insects, knowledge of the types and development of CNS glia is rather low. This is especially true for postembryonic glial development. Using bromodeoxyuridine incorporation and enhancer trap lines we identified a reproducible spatial and temporal pattern of DNA replicating cells in the abdominal larval CNS (A3-7 neuromeres) of Drosophila melanogaster. These cells correspond to embryonically established glial cells in that region. Except for a specific subfraction, these cells apparently do not divide during larval life. Similar patterns were found in two other Drosophila species, D. virilis and D. hydei.
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    URL: http://dx.doi.org/10.1007/BF00189068
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    Noninvasive loading of the rat ulna in vivo induces a strain-related modeling response uncomplicated by trauma or periostal pressure (1994)
    Springer
    Calcified tissue international 54 (1994), S. 241-247 
    Details
    ISSN: 1432-0827
    Keywords: Loading ; Strain ; Modeling ; Rat ; Ulna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Adaptive changes in bone modeling in response to noninvasive, cyclic axial loading of the rat ulna were compared with those using 4-point bending of the tibia. Twenty cycles daily of 4-point bending for 10 days were applied to rat tibiae through loading points 23 and 11 mm apart. Control bones received nonbending loads through loading points 11 mm apart. As woven bone was produced in both situations, any strain-related response was confounded by the response to direct periosteal pressure. Four-point bending is not, therefore, an ideal mode of loading for the investigation of strain-related adaptive modeling. The ulna's adaptive response to daily axial loading over 9 days was investigated in 30 rats. Groups 1–3 were loaded for 1200 cycles: Group 1 at 10 Hz and 20 N, Group 2 at 10 Hz and 15 N, and Group 3 at 20 Hz and 15 N. Groups 4 and 5 received 12,000 cycles of 20 N and 15 N at 10 Hz. Groups 1 and 4 showed a similar amount of new bone formation. Group 4 showed the same pattern of response but in reduced amount. The responses in Groups 2 and 3 were either small or absent. Strains were measured with single-element, miniature strain gauges bonded around the circumference of dissected bones. The 20 N loading induced peak strains of 3500–4500 μstrain. The width of the periosteal new bone response was proportional to the longitudinal strain at each point around the bone's circumference. It appears that when a bone is loaded in a normal strain distribution, an osteogenic response occurs when peak physiological strains are exceeded. In this situation the amount of new bone formed at each location is proportional to the local surface strain. Cycle numbers between 1200 and 12,000, and cycle frequencies between 10 and 20 Hz have no effect on the bone's adaptive response.
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    URL: http://dx.doi.org/10.1007/BF00301686
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    Effect of running exercise on the bone loss induced by orchidectomy in the rat (1994)
    Springer
    Calcified tissue international 55 (1994), S. 33-37 
    Details
    ISSN: 1432-0827
    Keywords: Osteoporosis ; Rat ; Orchidectomy ; Exercise ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of exercise on castration-induced osteoporosis in 3-month-old male rats weighing 264±4 g at the beginning of the experiment was studied. A testosterone deficiency was induced by orchidectomy (ORC), and the exercise group ran 10 m/minute for 1 hour a day on a treadmill at 0% grade. There were seven groups of eight rats (n=56) randomized into a control group killed at time 0, and sham, ORC and ORC and exercise groups killed at 4 and 8 weeks. ORC reduced body weight gain (with analysis of variance (ANOVA) P〈0.001), and at 4 weeks the body weight was 343±14 g in ORC group and 301±4 g in the ORC and exercise group (P〈0.01). The increase in femoral length was slower in the ORC+exercise groups. The ash weight of the tibia did not decrease significantly after ORC or ORC+ exercise. ORC did not affect 45Ca incorporation, but exercise slightly increased it in the whole tibia 8 weeks after ORC (with ANOVA P=0.057). ORC had significantly lowered the trabecular bone volume in the secondary spongiosa of the distal femur at 4 and 8 weeks, and exercise did not prevent this. This is an opposite finding to our previous study with ovariectomized female rats [12]. ORC also significantly had reduced the osteoblast-lined trabecular bone surface and the number of osteoclasts by 8 weeks after the operation. Exercise increased the osteoblast-lined surface and the number of osteoclasts. The mechanical strength of the femoral neck also was reduced after ORC and this was not prevented by exercise either. In conclusion, ORC reduces bone growth and turnover which leads to osteopenia in growing rats. Moderate treadmill exercise does not reverse the ORC-induced loss of trabecular bone and the reduced mechanical strength of the femoral neck, although it has a positive effect on the osteoblast and osteoclast indices and on calcium incorporation into bone.
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    URL: http://dx.doi.org/10.1007/BF00310166
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    The in vivo effect of a new, in vitro, extremely potent vitamin D3 analog KH1060 on the suppression of renal allograft rejection in the rat (1994)
    Springer
    Calcified tissue international 54 (1994), S. 150-154 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin D analog ; KH1060 ; Kidney transplantation ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract KH1060 is a new 20-epi-vitamin D3 analog, which has exerted a considerable immunosuppressive potency in vitro. We have tested in vivo the effect of KH1060 on the suppression of renal allograft rejection in the rat. Allogenic kidney transplantation from DA donor rats to Lewis recipient rats treated intraperitoneally with KH1060 in doses from 0.2 to 6 μg/kg/day, or saline (placebo group), or CyA 10 mg/kg/day for 10 days (positive control group), was performed. Median graft survival time in KH1060-treated groups was 7–9 days, in the placebo group 6 days, whereas CyA led to long-term graft survival, 34 days in 50% of rats and 〉100 days in 50% of rats. In vivo, KH1060 failed to prolong renal allograft survival considerably, and led to development of hypercalcemia. Our results stress the existence of a large discrepancy between the in vitro and in vivo immunoregulatory effects of this vitamin D analog.
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    Effect of ultrafilterable fragments from chondroitinase and protease-treated aggrecan on calcium phosphate precipitation in liposomal suspensions (1994)
    Springer
    Calcified tissue international 55 (1994), S. 176-179 
    Details
    ISSN: 1432-0827
    Keywords: Calcification ; Calcium phosphates ; Liposomes ; Mineralization ; Proteoglycans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A liposome-centered endogenous precipitation method was used to investigate the effect of ultrafilterable fragments from the enzymatic digestion of rat chondrosarcoma aggrecan on the formation of insoluble calcium phosphate salts in buffered solutions at pH 7.4 and 22°C. Unlike the intact aggrecan and its major chondroitin sulfate and core protein components, disaccharide units from chondroitinase degradation of the aggrecan and small (〈3kg/mol molecular weight) fragments from protease digestion of the core structure were found to be only weakly inhibitory toward mineral formation. Corresponding reductions in Ca2+-binding indicate that these fragments were unable to adsorb to active sites on the apatite surface for long enough periods to significantly hinder crystal growth. The data suggest that controlled enzymatic breakdown of aggrecan may be one possible mechanism by which the calcification of growth plate cartilage is allowed to advance in vivo.
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    Stimulation of human osteoblast differentiation and function by ipriflavone and its metabolites (1994)
    Springer
    Calcified tissue international 55 (1994), S. 356-362 
    Details
    ISSN: 1432-0827
    Keywords: Osteoblasts ; Matrix proteins ; Collagen ; Cell differentiation ; Calcification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10-5 M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.
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    URL: http://dx.doi.org/10.1007/BF00299315
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    Effect of 1α-vitamin D3 on bone strength and composition in growing rats with and without corticosteroid treatment (1994)
    Springer
    Calcified tissue international 55 (1994), S. 443-450 
    Details
    ISSN: 1432-0827
    Keywords: Bone mechanics ; Bone composition ; Vitamin D3 ; Corticosteroid ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of 1α-vitamin D3 were studied for 6 months in 2-month-old male and female rats on a moderately low calcium diet with or without low-dose prednisolone treatment. Both cortical bone mechanical and biochemical properties were examined. Femoral bone specimens were subjected to torsional loading tests. With age, bone strength and stiffness increased in both sexes, accompanied by an increased degree of mineralization (bone ash and calcium concentrations). During growth, strength and stiffness increased more in male than in female rats. When 1α-vitamin D3 (0.5 μg/kg/day) was given alone, bone mechanical competence improved significantly whereas insulin-like growth factor-I (IGF-I) and calcium concentrations in the bone matrix were significantly reduced. Treatment with low-dose prednisolone (0.5 mg/kg/day) alone did not influence bone mechanical properties compared with intact control rats (without prednisolone) although a significant reduction in calcium concentration and an increased phosphorus concentration were measured. A combined therapy with prednisolone and 1α-vitamin D3 significantly increased bone strength, toughness, and stiffness compared with control bones. Both mineralization degree (ash and calcium concentration) and IGF-I concentration were decreased. We conclude that (1) mechanical properties of rat cortical bones improve relatively more in males compared with agematched females during growth which is related to increased bone mass and size, (2) low-dose prednisolone treatment does not change mechanical properties in males, and altered them only nonsignificantly in females despite a change in mineralization degree in both sexes; (3) treatment with 1α-vitamin D3 results in a consistent increase in mechanical competence of the bone accompanied by a significant decrease in IGF-I concentration in the bone matrix.
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    URL: http://dx.doi.org/10.1007/BF00298558
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    Comparison of larval and adult P-450 activity levels for alkaloid metabolism in desertDrosophila (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 1893-1906 
    Details
    ISSN: 1573-1561
    Keywords: Drosophila ; Diptera ; Drosophilidae ; cytochrome P-450 ; poly-substrate monooxygenase ; cactus ; alkaloids ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The cytochrome P-450 monooxygenase system has been implicated in plant utilization by at least three species ofDrosophila (D. nigrospiracula, D. mettleri, andD. mojavensis) that are endemic to the Sonoran Desert of the southwestern United States and northwestern Mexico. Basal and induced levels of total cytochrome P-450 were determined for third-instar and decapitated 2- to 5-day post eclosion adults of the three desert species. Total P-450 levels, both basal and induced for all species assayed, were significantly higher for adults than for larvae by up to 20-fold. On a per organism basis, the levels of in vitro metabolism of the cactus alkaloid, carnegine, and patterns of response to induction by cactus tissue for adult desertDrosophila approximated those of larvae. Induction by phenobarbital, however, resulted in levels of in vitro carnegine metabolism that were up to 5.6-fold higher in adults than in larvae.
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    Alterations in flightin phosphorylation inDrosophila flight muscles are associated with myofibrillar defects engendered by actin and myosin heavy-chain mutant alleles (1994)
    Springer
    Biochemical genetics 32 (1994), S. 301-314 
    Details
    ISSN: 1573-4927
    Keywords: flightin ; Drosophila ; insect flight muscle ; phosphoprotein ; actin ; myosin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Flightin is a 20-kD myofibrillar protein found in the stretch-activated flight muscles ofDrosophila melanogaster. Nine of the eleven isoelectric variants of flightin are generatedin vivo by multiple phosphorylations. The accumulation of these isoelectric variants is affected differently by mutations that eliminate thick filaments or thin filaments. Mutations in the myosin heavy-chain gene that prevent thick filament assembly block accumulation of all flightin variants except N1, the unphosphorylated precursor, which is present at much reduced levels. Mutations in the flight muscle-specific actin gene that block actin synthesis and prevent thin filament assembly disrupt the temporal regulation of flightin phosphorylation, resulting in premature phosphorylation and premature accumulation of flightin phosphovariants. Cellular fractionation of fibers that are devoid of thin filaments show that flightin remains associated with the thick filamentrich cytomatrix. These results suggest that flightin is a structural component of the thick filaments whose regulated phosphorylation is dependent upon the presence of thin filaments.
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    Translational regulation of the heat shock response (1994)
    Springer
    Molecular biology reports 19 (1994), S. 211-220 
    Details
    ISSN: 1573-4978
    Keywords: Drosophila ; eIF-2 ; eIF-4F ; heat shock ; mRNA translation regulation ; phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract All organisms from bacteria to man respond to an exposure to higher than physiological temperatures by reprogramming their gene expression, leading to the increased synthesis of a unique set of proteins termed heat shock proteins (hsps). The hsps function as molecular chaperones in both normal and stressed cells. The rapid and efficient synthesis of hsps is achieved as a result of changes occurring at gene transcription, RNA processing and degradation, and mRNA translation. With regard to the translational regulation, the emerging picture is that the two key steps of polypeptide chain initiation, namely mRNA binding and Met-tRNA i binding to ribosomes, are regulated in heat-shocked mammalian cells. InDrosophila, mRNA binding is regulated by a structural feature of the leader of heat shock mRNAs and by the inactivation of eukaryotic initiation factor- (eIF-) 4F. No clear evidence for changes in Met-tRNA i binding has been obtained yet.
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    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light- and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrophs. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
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    URL: http://dx.doi.org/10.1007/s004410050253
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    Occurrence of osteoblast necroses during ossification of long bone cortices in mouse fetuses (1994)
    Springer
    Cell & tissue research 275 (1994), S. 345-353 
    Details
    ISSN: 1432-0878
    Keywords: Osteogenesis ; Ossification ; Mineralization ; Calcification ; Cell necroses ; Mouse (NMRI)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Previous investigations concerned with in vitro osteogenesis and mineralization have revealed some indication of a participation of cell necroses in the course of calcification. These observations were confirmed by in vivo investigations on desmoid ossification in fetal mouse calvariae, where abundant necrotic osteoblasts were found at the mineralization border and in the osteoid. In the present study, ossification of long bone cortices from fetal mice was investigated by use of electron microscopy. Specimens obtained from the collection of the Institute of Anatomy, Free University of Berlin (mouse fetuses, forearm; rat fetuses, forearm) were reinvestigated for control purposes. In all cases, mineralization of osteoid was accompanied by cell necroses. Cell degeneration was characterized by swelling of the endoplasmic reticulum and loss of the plasma membrane resulting in freely distributed vesicular structures. Cell debris was incorporated within the mineral. Initially, cell necroses in the perichondrium occurred in the region surrounding the hypertrophic cartilage and the matrix of which showed spots of endochondral mineralization. Necrotic osteoblasts occurred simultaneously with mineralization of the osteoid. During further ossification of the long bone cortices, the number of necrotic cells increased markedly. In addition to necrotic cells, healthy osteoblasts, osteocytes and perichondral tissue were present, indicating that an artifact can be excluded. The importance of cell necroses in the process of mineralization is as yet unclear. Possibly, the cells act as calcium and/or phosphate stores, which are liberated by cell death to increase the amount of mineral constituents at sites of mineralization.
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    URL: http://dx.doi.org/10.1007/BF00319433
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    Expression of the α-subunit of glycoprotein hormones in the pars tuberalis-specific glandular cells in rat, mouse and guinea-pig (1994)
    Springer
    Cell & tissue research 278 (1994), S. 617-624 
    Details
    ISSN: 1432-0878
    Keywords: Pituitary ; Pars tuberalis ; α-Subunit ; Immunocytochemistry ; In situ hybridization ; Rat ; Mouse ; Guinea-pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The nature of the hormone(s) secreted by the pars tuberalis (PT) is still unknown. This pituitary lobe is mainly formed by specific glandular cells that differ in their ultrastructural features from the other adenohypophysial cell types. Data from the literature indicate the presence of thyroid-stimulating hormone immunoreactivity in the PT-specific cells of the rat and the Djungarian hamster but not of other species, including the mouse and guinea-pig. The PT also encloses variable numbers of pars distalis cells, essentially gonadotrophs that are mainly dispersed in its caudal area. We studied the expression of the glycoprotein hormone α-subunit in the PT of the rat, mouse and guinea-pig by in situ hybridization and immunocytochemistry. In situ hybridization, using an oligonucleotide probe complementary to rat cDNA sequence 196–237 revealed the expression of the α-subunit gene throughout the PT of the rat and the mouse; in the guinea-pig, the probe labelled no pituitary cells. Light-and electron-microscopic immunocytochemistry demonstrated α-subunit immunoreactivity in the secretory granules of the PT-specific cells in the three species examined. These cells did not react with a specific antibody against the β-subunit of luteinizing hormone, an antibody that labelled scattered gonadotrops. The present data suggest that hormone(s) produced by the PT-specific glandular cells are, at least partly, related to glycoprotein hormones.
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    URL: http://dx.doi.org/10.1007/BF00331382
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    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: Key words: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of mid-pachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
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    URL: http://dx.doi.org/10.1007/BF00414179
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    Selective association of nerve fibres immunoreactive for substance P or bombesin with putative cholinergic neurons of the male rat major pelvic ganglion (1994)
    Springer
    Cell & tissue research 278 (1994), S. 589-594 
    Details
    ISSN: 1432-0878
    Keywords: Autonomic ganglia ; Neuropeptides ; Pelvic plexus ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The male rat major pelvic ganglion contains both sympathetic and parasympathetic neurons that supply the lower urinary and digestive tracts, and the reproductive organs. The aim of this study was to describe the distribution and identify potential targets of sensory and intestinofugal axons in this ganglion. Two putative markers of these projections were chosen, substance P for primary sensory axons and bombesin for myenteric intestinofugal projections. Varicose substance P-immunoreactive axons were associated only with non-noradrenergic (putative cholinergic) somata, and most commonly with those that contained vasoactive intestinal peptide. Immunoreactivity for substance P was also present in a small group of non-noradrenergic somata, many of which were immunoreactive for enkephalins, neuropeptide Y or vasoactive intestinal peptide. Bombesin immunoreactivity was found only in preterminal and terminal (varicose) axons, the latter of which were exclusively associated with non-noradrenergic somata that contain neuropeptide Y-immunoreactivity. Some varicose axons containing either substance P-or bombesin-immunoreactivity were intermingled with clumps of small, intensely fluorescent cells. These studies indicate that substance P-and bombesin-immunoreactive axons are likely to connect with numerically small, but discrete, populations of pelvic neurons.
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    URL: http://dx.doi.org/10.1007/BF00331378
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    Zona glomerulosa of the adrenal gland in a transgenic strain of rat: a morphologic and functional study (1994)
    Springer
    Cell & tissue research 278 (1994), S. 21-28 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Adrenal cortex ; Renin-angiotensin system ; Steroidogenesis ; Electron microscopy ; Morphometry ; Rat ; transgenic (mRen2) 27
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Transgenic rats for the murine Ren-2 gene display high blood pressure, low circulating levels of angiotensin II, and high renin content in the adrenal glands. Moreover, transgenic rats possess an increased aldosterone secretion (maximal from 6 to 18 weeks of age), paralleling the development of hypertension. To investigate further the cytophysiology of the adrenal glands of this strain of rats, we performed a combined morphometric and functional study of the zona glomerulosa of 10-week-old female transgenic rats. Morphometry did not reveal notable differences between zona glomerulosa cells of transgenic and age- and sex-matched Sprague-Dawley rats, with the exception of a marked accumulation of lipid droplets, in which cholesterol and cholesterol esters are stored. The volume of the lipid-droplet compartment underwent a significant decrease when transgenic rats were previously injected with angiotensin II or ACTH. Dispersed zona glomerulosa cells of transgenic rats showed a significantly higher basal aldosterone secretion, but their response to angiotensin II and ACTH was similar to that of Sprague-Dawley animals. Angiotensin II-receptor number and affinity were not dissimilar in zona glomerulosa cells of transgenic and Sprague-Dawley rats. These data suggest that the sustained stimulation of the adrenal renin-angiotensin system in transgenic animals causes an increase in the accumulation in zona glomerulosa cells of cholesterol available for steroidogenesis, as indicated by the expanded volume of the lipid-droplet compartment and the elevated basal steroidogenesis. However, the basal hyperfunction of the zona glomerulosa in transgenic animals does not appear to be coupled with an enhanced responsivity to its main secretagogues, at least in terms of aldosterone secretion.
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    URL: http://dx.doi.org/10.1007/BF00305774
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    The immunolocalization of small nuclear ribonucleoprotein particles in testicular cells during the cycle of the seminiferous epithelium of the adult rat (1994)
    Springer
    Cell & tissue research 278 (1994), S. 363-378 
    Details
    ISSN: 1432-0878
    Keywords: snRNPs ; Testis ; Spermatocytes ; Spermatids ; Immunocytochemistry ; Chromatoid body ; Intermitochondrial nuage ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The objective of this study was to determine the cellular and subcellular distribution of small nuclear ribonucleoprotein particles (snRNPs) in the adult rat testis in relation to the different cell types at the various stages of the cycle of the seminiferous epithelium. The distribution of snRNPs in the nucleus and cytoplasm of germ cells was quantitated in an attempt to correlate RNA processing with morphological and functional changes occurring during the development of these cells. Light-microscopic immunoperoxidase staining of rat testes with polyclonal anti-Sm and monoclonal anti-Y12 antibodies localized spliceosome snRNPs in the nuclei and cytoplasm of germ cells up to step 10 spermatids. Nuclear staining was intense in Sertoli cells, spermatogonia, spermatocytes, and in the early steps of round spermatid development. Although comparatively weaker, cytoplasmic staining for snRNPs was strongest in mid and late pachytene spermatocytes and early round spermatids. Quantitative electron-microscopic immunogold labeling of Lowicryl embedded testicular sections confirmed the light-microscopic observations but additionally showed that the snRNP content peaked in the cytoplasm of midpachytene spermatocytes and in the nuclei of late pachytene spermatocytes. The immunogold label tended to aggregate into distinct loci over the nuclear chromatin. The chromatoid body of spermatids and spermatocytes and the finely granular material in the interstices of mitochondrial aggregates of spermatocytes were found to be additional sites of snRNP localization and were intensely labeled. This colocalization suggests that these dense cytoplasmic structures may be functionally related. Anti-U1 snRNP antibodies applied to frozen sections showed the same LM localization pattern as spliceosome snRNPs. Anti-U3 snRNP antibodies applied to frozen sections stained nucleoli of germ cells where pre-rRNA is spliced.
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    URL: http://dx.doi.org/10.1007/BF00414179
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    Determination of triamterene in urine by HPLC using fluorescence detection and column-switching (1994)
    Springer
    Chromatographia 38 (1994), S. 29-34 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column-switching ; Determination of triamterene ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic method incorporating column-switching and fluorimetric detection for the determination of triamterene in untreated urine, is described. The urine samples (5 μL) were directly introduced onto an Hypersil ODS-C18, 30 μm (20 mm×2.1 mm I.D.) pre-column. Polar urinary compounds were removed by flushing the pre-column with water for 1 min, and the analyte was then switched onto an HP-LiChrospher RP C18,5 μm (125 mm×4mm ID) analytical column using an acetonitrile/phosphate buffer gradient elution. Fluorescence detection was performed at 230 nm excitation and 430 nm emission wavelengths. The recovery of drug was 102±2% in the 0.10–20.0 μg/mL concentration range, the limit of detection being 5 ng/mL. A validation of the usefulness of this procedure was accomplished by analysing urine extracts obtained from real samples.
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    URL: http://dx.doi.org/10.1007/BF02275723
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    Statistical evaluation of the validity of a method for characterizing stationary phases for reversed-phase liquid chromatography based on retention of homologous series (1994)
    Springer
    Chromatographia 38 (1994), S. 137-146 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Characterization of reversed phases ; Column hydrophobicity ; Column hydrophylicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The validity of a method for characterizing stationary phases for reversed-phase, liquid chromatography, based on the use of homologous series, has been evaluated. The method is based on a retention model which describes the dependence of the logarithm of the capacity factor on mobile phase composition and the carbon number of specific homologous series. A first-order as well as a second-order version of this model was investigated. The second-order model proved to be a significant improvement on the first-order model, even for smaller mobile-phase ranges. Nevertheless both models showed a significant lack of fit, reflecting the incompleteness of these models. Therefore, it is very questionable whether this method is suitable to describe HPLC-column characteristics like hydrophobicity and hydrophylicity.
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    URL: http://dx.doi.org/10.1007/BF02290326
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    Control of adsorption and solubility in gradient high performance liquid chromatography. Part 3. Sudden-transition gradient elution of styrene/ acrylonitrile copolymers (1994)
    Springer
    Chromatographia 38 (1994), S. 749-755 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Copoly(styrene/acrylonitrile) ; Gradient elution ; Precipitation chromatography of polymers ; Solubility of polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copolymers from styrene and acrylonitrile could be separated according to composition by gradient elution through methanol after injection inton-heptane and sudden addition of 50, 60, or 70 vol% tetrahydrofuran. The peak sequence was the same as with a common binary gradientn-heptane/tetrahydrofuran, i.e., retention increased with acrylonitrile content of the samples. With copolymers containing 37, 31, or 26% acrylonitrile, the elution characteristics in the ternary systems could be logically extrapolated towards the points measured in the corresponding binary gradient system.
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    URL: http://dx.doi.org/10.1007/BF02269631
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    Chiral recognition of structurally related aminoalkylphosphonic acid derivatives on an acetylated beta-cyclodextrin bonded phase (1994)
    Springer
    Chromatographia 38 (1994), S. 771-775 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral recognition ; Aminoalkylphosphonic acid derivatives ; β-cyclodextrin bonded phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An acetylated β-cyclodextrin column was used to analyse the enantiomeric resolution of a number of aminophosphonic acids. Effects of the structure of these compounds on the extent of separation was examined. Molecular modelling studies were also carried out in an attempt to relate any interaction between the amino and phosphonic acid groups to chiral recognition by the stationary phase.
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    URL: http://dx.doi.org/10.1007/BF02269635
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    Interaction of cyclodextrins with drugs. Chromatographic investigation using a cyclodextrin bonded-phase and its application to chiral separations (1994)
    Springer
    Chromatographia 38 (1994), S. 381-385 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Association constants ; Frontal analysis ; Cyclodextrin bonded-phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction between cyclodextrin and the drug (1R,2S,3S,4S)-(5Z)-7-(3-((phenylsulfonyl)amino)bicyclo[2.2.1]hept-2-yl)hept-5-enoic acid ((+)-S-145), was studied using α-, β-, and γ-cyclodextrin bonded-phase columns. Retention behavior of (+)-S-145 on these columns revealed that the strength of inclusion was β→γ→α-cyclodextrin. Interaction between β-cyclodextrin and (+)-S-145 was found to increase as the proportion of carboxylic ion in the (+)-S-145 molecule increased. Comparison of binding capacities of these bondedsilica gels obtained by frontal analysis and surface coverage indicated that availability of the immobilized β- and γ-cyclodextrin was 20–25%. The synthesized β-cyclodextrin bonded-phase column was superior to that of commercial columns in terms of chiral separation of (±)-S-145. A typical usage of the β-cyclodextrin column is discussed for separation of (±)-S-145 in plasma samples.
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    URL: http://dx.doi.org/10.1007/BF02269784
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    Reverse phase high-performance liquid chromatographic determination of primary and secondary aliphatic alcohols as phthalate monoesters by UV detection (1994)
    Springer
    Chromatographia 38 (1994), S. 417-420 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Primary and secondary aliphatic alcohols ; Aqueous derivatization ; Phthalic acid monoesters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Determination of primary and secondary aliphatic alcohols in aqueous and nonaqueous solutions by high-performance liquid chromatography (HPLC) is described. The alcohol is derivatized with phthalic anhydride to yield the corresponding monophthalate. Separation of the derivative is achieved on an ODS-10 reverse phase (RP) column by elution with an appropriate isocratic mobile phase of acetonitrile and aqueous phosphoric acid (0.1%). Detection is accomplished by UV absorption at 230 nm or 280 nm giving linear calibration plots, for alcohols in aqueous solution from 0.05% to 0.50% (w/v) and in pyridine solution from 0.0025% to 0.0250% (w/v).
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    URL: http://dx.doi.org/10.1007/BF02269829
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    Solute-micelle association constants of some polynuclear aromatic hydrocarbons by micellar liquid chromatography with alcohol additives to mobile phase (1994)
    Springer
    Chromatographia 38 (1994), S. 342-348 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hybrid mobile phases containing alcohols ; Solute-micelle association constants ; Polynuclear aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interaction between some polynuclear aromatic hydrocarbons of environmental concern, and sodium dodecylsulphate and hexadecyltrimethylammonium bromide in the presence of methanol, 2-propanol and n-butanol has been evaluated by high-performance liquid chromatography using micellar mobile phases. Solute-micelle association constants have been determined for the compounds investigated. The results show that the addition of the alcohol to the mobile phase decreases the association constant values, methanol 〈2-propanol 〈n-butanol, relative to those in the absence of any additive.
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    URL: http://dx.doi.org/10.1007/BF02269778
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    Solid phase extraction applied to the determination of biogenic amines in wines by HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 571-578 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Wine ; Biogenic amines ; Solid-phase extraction ; Derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method suitable for the determination of 19 biogenic amines in wine has been developed. The method involves derivatization of amines by treatment with dansyl chloride and solid-phase extraction of the derivatives. Prior to the derivatization procedure, clean-up of the wine sample with polyvinylpyrrolidone is carried out. Reversed-phase gradient elution HPLC with UV detection at 250 nm was used to determine these compounds. Some consideration was given to the effect of temperature on the separation process. Linearity of derivatization was obtained for amounts of all the biogenic amines ranging from 500 μg·L−1 to 20 mg·L−1. Limits of detection (signal-to-noise ratio=3) of the amines were similar for all the dansylderivatives (between 50 and 150 μg·L−1). Addition of standard amines was used for the determination of amine recoveries. These were better than 85% for ethanolamine, tryptamine, phenetylamine, putrescine, cadaverine and histamine. The overall process was succesfully applied to identify and quantify biogenic amines in white and red wines.
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    Enantiomer separaton of tifluadom and analogues by liquid chromatography with cellulose-based chiral stationary phases (1994)
    Springer
    Chromatographia 38 (1994), S. 629-632 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral/enantiomeric iseparation ; Cellulose-based chiral phases ; Tifluadom analogues ; 2-acylaminomethyl-1,4-benzodiazepines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of nine recamic mixtures of tifluadom analogues has been evaluated using the chiral stationary phases Chiralcel OD and Chiralcel OJ. The separation was performed on an analytical scale to optimize the conditions for chiral resolution, approaching baseline separation, of the two enantiomers. Eight racemates were baseline separated on Chiralcel OJ using a mobile phase of hexane/2-propanol.
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    Comparative study of solid-phase extraction of phenolic compounds. Influence of the ion pair reagent (1994)
    Springer
    Chromatographia 38 (1994), S. 579-584 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenolic compounds ; Ion-pair solid-phase extraction ; Comparison of sorbents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A comparative study of the solid phase extraction of phenolic compounds in water was carried out. Three different sorbents, C18, CH and PLRP-S, were tested for the preconcentration process in order to determine phenolic compounds in water at μg l−1 levels by reversed-phase LC separation and diode-array detection. The addition of an ion-pair reagent in the extraction process was also studied in order to increase the breakthrough volume of some compounds. Using the optimized conditions the limit of detection was less than 0.5 μg l−1, the maximum admissible concentration (MAC) in drinking water. The method was applied to determine phenolic compounds in Ebro river water however no phenols were found within the detection limits of the method.
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    Extraction of basic drugs from whole blood and determination by high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 617-623 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Extraction-determination ; Basic drugs ; Blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the extraction of basic drugs from whole blood based on the use of a buffered protein precipitating reagent at pH9, to form NiWO4 in biological fluids and a ternary organic extracting phase of density below 1 is proposed. The extract is analysed by high performance liquid chromatography using a Hypersil C8 column and detection at 230 nm; the mobile phases used consist of binary mixtures of acetonitrile and aqueous solutions containing 20 mmol/l ofn-propylamine at pH 5 andn-hexylamine at pH 4, as blockers of the free silanol groups. The proposed method was applied to the determination of 16 basic drugs including narcotics, analgesics, cocaine-related compounds and adulterants, as well as 8 benzodiazepines, in whole blood.
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    URL: http://dx.doi.org/10.1007/BF02277164
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    Determination of imazethapyr and imazapyr residues in soil by coupled-column liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 62-66 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Imidazolinone herbicides in soil ; Imazethapyr ; Imazapyr
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A column-switching method using two separation columns combined with UV detection at 260 or 236 nm has been used to determine the imidazolinone herbicides imazethapyr and imazapyr in soils. The residues were extracted from the soil with 0.1 M aqueous sodium carbonate solution and, after adjusting the pH to 2.0, the solution was partitioned with dichloromethane. Limits of determination for imazethapyr and imazapyr were 3 μg/kg. Recoveries were from 55 to 75% for both imidazolinone herbicides in the range 3–100 μg/kg in soil.
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    URL: http://dx.doi.org/10.1007/BF02320459
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    A novel derivatisation procedure for inorganic mercury(II) for HPLC analysis (1994)
    Springer
    Chromatographia 39 (1994), S. 246-248 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mercury ; Diphenylethynylmercury
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new procedure for derivatisation of inorganic mercury(II) to diphenylethynylmercury with simultaneous extraction into dichloromethane is proposed. The organomercury derivative is effectively analysed by HPLC using UV detection. The calibration curve is linear over three orders of magnitude (0.02–50 mg L−1 Hg); the detection limit is 0.1 ng Hg. A preliminary study of the effect of potential interfering agents, in particular Cu(II), Zn(II), Cd(II), Pb(II), and cysteine, and applications of the present methodology to real environmental samples are presented.
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    URL: http://dx.doi.org/10.1007/BF02274507
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    Determination of short chain aliphatic acids in silage effluents by ion exclusion chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 43-51 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exclusion ; Alipathic acids ; Silage effluents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Short chain aliphatic acids are important components of the dissolved organic matter in silage effluents. Although ion exclusion chromatography offers some advantages for the analysis of these compounds, no attempt has yet been made to prove the suitability of this method for silage effluent analysis. In order to gain experience in this field, the separation characteristics of a Dionex ion exclusion column (IonPac-ICE As5) have been evaluated, the separation conditions have been improved, and several sample clean-up methods have been checked. Ten effluents generated during silaging of five different crops were collected from Bavarian farms and analyzed. Lactic and acetic acids were the predominant aliphatic acids. Pyruvic, formic, propionic, and succinic acid were detected in all samples, whereas glyceric and iso-citric acid were found in a few samples only. If some restrictions of substance specificity and separation efficiency can be accepted, the analytical method presented will be a reliable tool for the analysis of carboxylic acids in silage effluents.
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    URL: http://dx.doi.org/10.1007/BF02275725
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    Polymer encapsulated packing material for reversed phase liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 756-760 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymer encapsulated packings ; Poly(ethylstyrene-divinylbenzene) ; Preparation and evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A series of polymer-encapsulated packing materials for reversed phase high-performance liquid chromatography was prepared by radical polymerization of ethylstyrene and divinylbenzene with vinyl-modified silica in solution. Some characteristics such as polymer structure, swelling propensity, residual silanols, column efficiency and retention properties were evaluated. Such material is easy to pack and yields high column efficiencies. Its superior performance for the separation of mixtures of aromatic hydrocarbons, amino- and hydroxyl group containing compounds are demonstrated by several examples.
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    URL: http://dx.doi.org/10.1007/BF02269632
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    Application of β-cyclodextrin for the analysis of estrogenic steroids in human urine by high-performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 168-172 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; β-Cyclodextrin in mobile phase ; Estrogens ; Pregnant and non-pregnant women
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure is described for simultaneous determination of estriol, estrone and 17β-estradiol in human urine. After acid hydrolysis of the sulphate conjugates, the estrogens were extracted into diethyl ether. The ether extracts were concentrated and applied directly to an HPLC column. Using a 25 cm C-18 column and acetonitrile-water modified by the addition of β-cyclodextrin as mobile phase, the separation of estriol, estradiol and estrone was achieved within 20 minutes. The extraction of estrogens from the biological matrix is excellent. Estrogens were detected using a UV-detector (280 nm) or a spectrofluorimetric detector (λexc=280nm, λem=312 nm). The latter detection system has been used for the determination of estrogens in the urine of non-pregnant women. The procedure is simple and can be used in clinical practice.
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    URL: http://dx.doi.org/10.1007/BF02290331
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    Convergence of retention for small solutes in reversed-phase liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 158-162 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromatography ; Retention mechanism ; Retention convergence ; Small molecules
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is shown theoretically that when the concentration of organic solvent in the mobile phase increases, or solute size decreases, log k′ values of small solutes in reversed-phase liquid chromatography (RPLC) will tend to have a minimum value called the convergence point. A theoretical model for evaluating the convergent coordinates of small solutes is presented by using a stoichiometric displacement model for retention (SMDR). The physical meaning of the coordinates of each kind of convergence are also elucidated. The convergence points have either two-dimensional coordinates with a common ordinate (the logarithm of the phase ratio of the column, log φ) or threedimensional corrdinates with two common axes: — log φ and the logarithm of the molar concentration of the pure displacing agent in mobile phase, log aD. The other axis relates to the nature of the solutes, such as carbon number of a homolog, van der Waal's surface area, hydrophobic fragment constant etc. for the latter and those and/or concentration axis for the former. The model was tested with published data and found to give a good fit.
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    URL: http://dx.doi.org/10.1007/BF02290329
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    CP/MAS NMR investigations of silica gel surfaces modified with aminopropylsilane (1994)
    Springer
    Chromatographia 38 (1994), S. 283-290 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phase (CBP) ; Silica-gel with aminopropylsilyl ligands ; Physico-chemical characterization ; CP/MAS NMR investigation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aminopropyl chemically bonded phases for high performance liquid chromatography (HPLC) have been prepared using mono- and trifunctional methoxyor ethoxysilanes. Three types of silica gel with different surface characteristics were used as support for the chemically bonded phases (CBPs). Surface characteristics of the packings before and after chemical modification were determined by porosity parameters, elemental analysis and CP/MAS NMR spectroscopy.29Si and13C CP/MAS NMR investigations gave informations about different interactions between aminosilyl ligands and/or these ligands and/or water molecules condensed in the pores of the silica gel surface. With decreasing pore diameter of the silica gel the proportion of protonated aminopropyl ligand increases.
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    URL: http://dx.doi.org/10.1007/BF02269769
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    The application of ‘Z’-shaped UV cells in open-tubular capillary column liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 313-316 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Open-tubular capillary columns ; ‘Z’-shaped UV cells ; Solvent make-up
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary ‘Z’-shaped UV cells for packed capillary columns cannot be used in open-tubular capillary column liquid chromatography (OT-LC) because of their relatively large volume. With post-column solvent make-up, a commercial ‘Z’-shaped cell (volume 100 nl) was used in our OT-LC system, resulting in 9-fold sensitivity increase against on-column UV detection and with little efficiency loss. A small volume (5 nl) ‘Z’-shaped cell allows the direct coupling of the cell to high efficiency columns. For dilute samples, 9-19-fold sensitivity enhancement could be obtained. However, column efficiency decreases with increasing signal level as a result of peak deformation.
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    URL: http://dx.doi.org/10.1007/BF02269773
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    Interconversion of cyclosporin molecular form inducing peak broadening, tailing and splitting during reversed-phase liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 359-364 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclosporin ; Reversible conversion ; Activation energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatography of cyclosporin A, a peptide immunosuppressant, at various temperatures produced remarkably different chromatograms. At 60°C one sharp peak was obtained, at 23°C this became a single broad peak and between 15° and 0°C this became one high sharp peak followed by a tailing or low plateau. Remarkably different chromatograms were produced also by varying the mobile phase flow-rate. The effects of both temperature and flow-rate on the chromatogram could be accounted for by interconversion between two forms of the cyclosporin molecule. Kinetic analysis showed that one form was converted by first-order kinetics with a half-life of 2.0 min at 20°C and that the apparent activation energy for the conversion was about 18 kcal/mol. The other two immunosuppressants, cyclosporin C and D, were also shown to undergo interconversion. This kinetic analysis of the interconversion should be helpful in clarifying the relationship between molecular structure and activity of the immunosuppressants.
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    URL: http://dx.doi.org/10.1007/BF02269781
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    Determination of carbendazime in lettuce samples by SFE-HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 395-399 
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    ISSN: 1612-1112
    Keywords: Supercritical fluid extraction ; Column liquid chromatography ; Carbendazime analysis ; Vegetable samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An SFE-HPLC method for the determination of carbendazime in lettuce leaves is described. The method involves a prior lyophilization of the sample and subsequent extraction with supercritical carbon dioxide containing methanol. The extraction conditions are as follows: amount of lyophilized sample, 1 g; CO2 density, 0.75 g/ml; temperature, 50 °C; flow-rate, 1.8 ml/min; dynamic extraction time, 25 min. Carbendazime is determined with an octadecylsilane column, an acetonitrile/water 30∶70 mobile phase and fluorescence detection at 285/317 nm. Carbendazime recoveries from spiked samples were all close to 100%. A comparison with the results from a conventional method for the determination of carbendazime reveals the new method to be more rapid, simple and reproducible for samples with low concentrations of analyte.
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    URL: http://dx.doi.org/10.1007/BF02269786
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    A photometric flow measurements method for characterisation of HPLC pumps (1994)
    Springer
    Chromatographia 38 (1994), S. 421-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pumps ; Flow control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The measurement of flow constancy and pulsation amplitudes of HPLC pump based on the photoconversion of malachite green leucocyanide is described. The irradiation time and hence the degree of conversion of the leucocyanide is correlated to flow fluctuations of piston driven HPLC pumps. It is possible to measure the amplitude of pulsations and determine the constancy of the flow rate. Most of the pumps show a flow stability better than ±1% measured as relative standard deviation of the flow rate under HPLC conditions (pressure drop 100 bar at 1 ml/min flow rate). The most expensive pump of those tested showed less than ±0.5% flow instability, however, this result was achieved by installation of a large-volume pulsation damper. The method described also allows flow rate measurements under FIA conditions where there is little or no pressure drop at the pump outlet.
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    URL: http://dx.doi.org/10.1007/BF02269830
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    Surface modification by calcium ions—Effect on chromatographic properties of silica (1994)
    Springer
    Chromatographia 39 (1994), S. 29-34 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Calcium modified silica ; Calcium adsorption isotherms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The modification of silica surfaces by calcium ions has been studied by high-performance liquid chromatography. After treatment at pH 7.0 and 9.0 with calcium hydroxide, the modified silicas were characterised by physical and chemical analysis. From measurements by atomic absorption, the amount of calcium adsorbed was 650 ppm on silica modified at pH 7.0, and 4800 ppm on silica modified at pH 9.0. The amount of calcium on the modified silica was 0.574 groups nm−2 at pH 9.0 (original silica: mean pore diameter 176 Å, specific surface 279 m2 g−1, pore volume 1.23 ml g−1, mean particle size 9.8 μm). On the other hand, the amount of calcium in the original silica was 58 ppm. The separation factor, α for N-methylaniline and N,N-dimethylaniline was 5.2 on silica modified at pH 9.0, but could not be measured on silica modified at pH 7.0 and the original silica, using iso-propyl alcohol—n-hexane (0.5∶99.5) eluent.
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    URL: http://dx.doi.org/10.1007/BF02320454
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    Dual injector solvent elution and focussing technique for the on-line analysis of solid-phase extraction cartridges in HPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 45-50 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Sample preconcentration ; Solid-phase extraction ; Solvent focussing ; Injection techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new dual injector solvent focussing and elution technique developed for high-performance liquid chromatography (HPLC) greatly improves chromatographic efficiency for the on-line analysis of C18 solid-phase extraction (SPE) cartridges. Solutions containing three benzene homologs were used to characterize the dual injector analysis technique and to compare the chromatographic efficiency of this method with conventional SPE analysis methods. Sampling was performed off-line using a glass precolumn cartridge (3 mm i.d. × 30 mm) packed with 15–35 μm C18 silica. On-line cartridge analysis was achieved with two injection valves in either serial or parallel configuration. The injection loop of the first valve contains the eluting solvent, and the cartridge holder is connected in place of the injection loop of the second valve. When an injection is made, both valves are turned to the inject position, and the solvent plug is forced through the cartridge, focussing the analyte at the solvent front as it elutes the cartridge. Solvent focussing at the head of the column, resulting from preconditioning of the column with a small plug of water during injection, further minimizes the variance of the injection plug and improves the chromatographic efficiency. The technique has potential applications to environmental and biological fluid analysis where analyte preconcentration and resolution from the sample matrix components may be difficult with current SPE methods.
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    URL: http://dx.doi.org/10.1007/BF02320457
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    An improved method for the determination of free sphingosine in serum (1994)
    Springer
    Chromatographia 39 (1994), S. 85-90 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Carbopack B ; Free sphingosine in human plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid, sensitive and selective high-performance liquid chromatographic method has been developed for the determination of sphingosine in human serum. After precipitation with methanol, the samples were extracted using Carbopack B disposable columns; the sphingosine was eluted with 0.05 M hydrochloric acid in methanol-dichloromethane (20∶80, v/v) and the extract evaporated to dryness at 40°C. The sample residue was then reconstituted with methanol and reacted with o-phthaldialdehyde reagent to produce a fluorescent compound. Separation was performed using an LC-18 column with 0.05 M phosphate buffer (pH 7)-methanol-acetonitrile (15∶80∶5, v/v) as mobile phase. Fluorescence detection was performed with excitation and emission wavelengths of 340 and 455 nm, respectively. The serum extract was re-analyzed with a cyano LC column to minimize the possibility of false positive results. The possible interference of compounds having a structure similar to that of sphingosine was evaluated. The mean recovery of sphingosine was 〉94.5%. The limit of detection of the assay was 1 ng mL−1. The between-run and within-run coefficients of variation for replicate analyses were 〈4.0% and 〈3.4%, respectively. The levels of free sphingosine in the serum of 40 normal subjects (20 male and 20 female) was investigated; the average level was 81.6±41.1 ng mL−1 (mean ±S.D.) for males and 85.5±33.7 ng mL−1 for females.
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    URL: http://dx.doi.org/10.1007/BF02320464
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    Analysis of thiamine in dried yeast by high-performance liquid chromatography and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (1994)
    Springer
    Chromatographia 39 (1994), S. 91-96 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Atmospheric pressure chemical ionization-mass spectrometry ; Dried yeast ; Thiamine ; Ion-pair extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) and high-performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS) have been applied to the analysis of thiamine in dried yeast. Thiamine was extracted from dried yeast with isobutanol containing sodium 1-octanesulfonate as an ion-pairing agent and determined by HPLC on a reversed phase ODS column with UV detection at 254 nm. Response was linear in the range 25–300 μg/g of thiamine in dried yeast with a coefficient of variation in the reproducibility of 8.0%. Thiamine was recovered in good yield (109.2%, n=5). Identification of the thiamine peak was obtained by the mass spectrum using the HPLC/APCI-MS system. The utility of the selected ion monitoring technique using the HPLC/APCI-MS was also investigated. The results obtained by this method are in good agreement with those obtained by the thiochrome method [1].
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    An improved high-performance liquid chromatographic determination of chlorpropamide in human plasma (1994)
    Springer
    Chromatographia 39 (1994), S. 107-109 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Drug assay ; Chlorpropamide ; Tolbutamide ; Human plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Samples were extracted with dichloromethane and the organic layer evaporated to dryness. The residue was dissolved in methanol, and 10 μl aliquot injected onto the column. Tolbutamide was used as the internal standard for chlorpropamide. The UV detector response was linear over the range 0–200 μg ml−1 with a correlation coefficient of 0.999; detection limit: 0.002 μg ml−1. Within-day and between-day assay variation was generally ≤7%. No interference from endogenous constituents was observed. The utility of the method was demonstrated by determining chlorpropamide in samples from six healthy volunteers following a single oral dose of 250 mg. The procedure is simple and requires small volumes of plasma.
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    The modiffication of alumina, zirconia, thoria and titania for potential use as HPLC stationary phases through a silanization/hydrosilation reaction scheme (1994)
    Springer
    Chromatographia 39 (1994), S. 649-654 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Non-silica based supports ; Hydrosilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A process for bonding a monolayer of silane to the surface of alumina, zirconia, thoria and titania by reaction with the hydrolysis product of triethoxysilane is described. The hydride containing material is then further reacted with a terminal olefin in the presence of a platinum catalyst to produce a chemically modified oxide surface which could be used as a chromatographic stationary phase. The success of this reaction is monitored by diffuse reflectance infrared Fourier transform and cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy as well as by differential scanning calorimetry. On all four oxides both the hydride intermediate and the alkyl bonded product are successfully formed via the silanization/hydrosilation reaction sequence.
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    Studies of some experimental conditions for the polymerization of the continuous beds (cross-linked polyacrylamide gels) in order to improve their chromatographic properties (1994)
    Springer
    Chromatographia 39 (1994), S. 655-662 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Continuous beds ; Compressed beds ; Proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Continous chromatographic beds are synthesized by a simple and cost-effective procedure which does not involve the conventional, time-consuming preparation of beads. The aim of this study was to improve the flow properties of the beds by investigating how they are affected by polymerization temperature, the pH of the buffer in which the polymerization takes place, the nature of the constituents of this buffer, the concentrations of catalyst and accelerator and the concentration of the precipitating agent (ammonium sulfate). The infuence of flow rate and the time constants of the detector and recorder on peak width was also studied.
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    URL: http://dx.doi.org/10.1007/BF02274579
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    Reversed phase C18 packings for the separation of polycyclic aromatic hydrocarbons by high performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 668-672 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Monomeric and oligomeric RP packings ; Preparation of RP stationary phases ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of C18 stationary phases for the separation of polycyclic aromatic hydrocarbons has been investigated. The effect of the pore size of the silica, the endcapping procedure, the amount of reagent and the amount of water in the preparation was also examined. A good correlation between surface coverage and capacity factor was found. The maximum surface coverage available with our preparation method lies between 3–3.5 μmol m−2, slightly depending on the pore size of the silica. Oligomeric not endcapped C18 packing materials are optimal for the separation of polycyclic aromatic hydrocarbons.
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    URL: http://dx.doi.org/10.1007/BF02274581
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    Estimation of phenolic compounds in green pepper berries (Piper nigrum L.) by high-performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 743-746 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenolic compounds ; Green pepper berries
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method is described for the separation and estimation of phenolic compounds in six commercial varieties of green pepper berries. Among these, two phenolic compounds namely 3,4-dihydroxyphenylethanol glucoside and 3,4-dihydroxy-6-(N-ethyl amino)benzamide that served as efficient substrates for pepper phenolase, showed wide qualitative and quantitative variation in their composition within the varieties. Quantitative estimations of these two compounds were carried out using 4-methylcatechol and epinephrine as external standards. This method is suitable for the estimation of phenolic compounds in green pepper berries in one run.
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    URL: http://dx.doi.org/10.1007/BF02274592
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    Analysis of basic hair dyes by HPLC with on-line post-column photochemical derivatisation (1994)
    Springer
    Chromatographia 39 (1994), S. 138-145 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Diode array detection ; Post-column photochemical derivatisation ; Hair dyes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed phase liquid chromatographic method is proposed for the analysis of basic hair dyes (raw materials and colourant formulations). The performance of the method was enhanced by introducing post-column on-line photochemical derivatisation in combination with a Diode Array Detector. On-line photoderivatisation provided an effective way of selectively transforming the analytes to compounds with different spectral properties. For each analyte two characteristic UV-Visible spectra (photoreactor on and off) were obtained with the same mobile phase and this information in combination with the chromatographic data (k' at pH 3.0 and 4.5) enabled the unambiguous identification of both commonly used, approved, and banned basic hair dyes. Additionally, this approach was found useful to improve the method sensitivity, allowing the determination of analytes present in low concentration (0.03%) in complex commercial formulations.
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    Control of adsorption and solubility in gradient high performance liquid chromatography. Part 4. Sudden-transition gradient elution of styrene/ethyl methacrylate copolymers in reversed phase mode (1994)
    Springer
    Chromatographia 39 (1994), S. 170-174 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Copoly(styrene/ethyl methacrylate) ; Gradient elution ; Precipitation chromatography of polymers ; Solubility of polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copolymers from styrene and ethyl methacrylate have been separated according to composition byn-heptane gradients on a C18 bonded phase after injection into acetonitrile and subsequent sudden transition to a concentration of either dichloromethane or tetrahydrofuran between 30 and 50% or 20 and 50%, respectively. Acetonitrile is a polar non-solvent for the copolymers under investigation and ensures proper retention of the samples on a non-polar stationary phase. Dichloromethane and tetrahydrofuran are good solvents of moderate polarity. The addition of, e.g., 30 vol% of one of these solvents increased the dissolution power of the starting eluent but not to the extent necessary for elution. The latter was achieved by the addition ofn-heptane, which is a non-solvent for the polymers investigated. Thus, its eluting power must be understood as the consequence of its modifying effect on the polarity of the eluent mixture. The higher the content of copolymer in ethyl methacrylate the earlier it was eluted. Since acetonitrile andn-heptane are only partly miscible, phase diagrams were measured after the addition of either tetrahydrofuran or dichloromethane as a third component. Homogeneous mixtures were obtained on addition of about 30% solvent (one of both of the latter).
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    On-line trace enrichment — column liquid chromatography of polar pollutants in surface water using bifunctional membrane-based extraction-disk cartridges (1994)
    Springer
    Chromatographia 39 (1994), S. 239-245 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Membrane-extraction disks ; On-line trace enrichment ; Polar pollutants ; Surface water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An on-line trace-enrichment system, using a bifunctional membrane extraction-disk cartridge, has been combined with a column liquid chromatography separation for the simultaneous determination of basic, neutral and acidic pollutants in surface water. The enrichment device consisted of a specially constructed holder containing both C-18 and cation-exchange disks. The holder can contain up to 25 disks of 0.5 mm thickness and 4.6 mm diameter. Before trace enrichment of 20 ml of surface water (pH 3.0), calcium ions were removed from the sample by means of an oxalic acid precipitation. Desorption of the cartridge was at elevated temperature using reversed-phase gradient elution; detection was performed with a diode-array UV absorbance detector. The detection limits for the test compounds in surface water are typically 0.5–2 μg/l; the calibration graphs are linear from the lower limit of determination up to 50 μg/l.
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    Retention characteristics of fluorinated bonded silica phase in reversed-phase liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 285-293 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fluorinated chemically bonded silica ; Aromatic compounds ; Molecular shape vs. retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fluorinated bonded silica has been evaluated as a packing material in reversed-phase liquid chromatography (RPLC) with polycyclic aromatic hydrocarbons, chlorinated benzenes and substituted benzenes as sample probes. The bonded material is useful as a reversed-phase stationary phase and for polar compounds it offers a specific selectivity not found with octadecylsilica (ODS) phases. The phase also retains non-planar compounds more than planar molecules. The results can be explained by conformational differences between ODS and the fluorinated bonded phase by MM2 calculation.
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    URL: http://dx.doi.org/10.1007/BF02274515
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    Optimization of mobile phases for HPLC of cis-trans carotene isomers (1994)
    Springer
    Chromatographia 39 (1994), S. 346-354 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α-Carotene cis-isomers ; β-Carotene cis-isomers ; Polymer stationary phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Various methanol-based, binary and ternary solvent systems were compared with respect to resolution of cis isomers of α and β-carotene by reversed-phase HPLC. A ternary system: acetonitrile-methanol-methylene chloride (75∶15∶10), or a binary system: acetonitrilemethanol (90∶10 or 5∶95) provided the best separation of β-carotene and its four cis isomers, 9-cis, 13-cis, 15-cis and 13,15-di-cis-β-carotene. The elution order of 9-cis and 13-cis-β-carotene was dependent on the methanol concentration. Methanol-methylene chloride (99∶1) resolved α-carotene and its three cis isomers, 9-cis, 13-cis, and 15-cis-α-carotene. It also proved the best for simultaneous separation of cis isomers of α and β-carotene. Sample solvent can affect the separation efficiency of each isomer. The presence of cis isomers of α and β-carotene in fresh and cooked carrots was also determined.
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    URL: http://dx.doi.org/10.1007/BF02274524
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    Chromatographic determination of D-amino acids as native constituents of vegetables and fruits (1994)
    Springer
    Chromatographia 39 (1994), S. 419-426 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Chirasil-Val ; Amino acid enantiomers ; N-Isobutyryl-cysteine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Free D-amino acids (D-AA) were detected as native constituents in juices of vegetables (cultivars of cabbage, tomato, carrot, garlic) and fruits (organes, clementine, grapefruit, lemon, apples, pear, grapes) using gas chromatography (GC) or high-performance liquid chromatography (LC). For investigation by GC, AA enantiomers were converted into theirN(O)-pentafluoropropionyl 2-propyl esters and resolved on a Chirasil-L-Val capillary column. For determination by LC, precolumn derivatization of AA enantiomers usingo-phthaldialdehyde together with the chiral thiolsN-isobutyryl-L-cysteine orN-isobutyryl-D-cysteine and fluorescence detection of the diastereomeric isoindole derivatives, resolvable on an octadecylsilyl stationary phase, were used. D-Ala (0.6–3.8%) was detected in all freshly pressed plant juices usually in the highest relative amounts. Other D-AA detected were D-Asx (0.1–1.9%), D-Glx (0–1.3%), D-Ser (0–1.7%), D-Arg (0.4–1.2%, in grapes, orange, grapefruit, and clementine) and D-Leu and D-Val (1% in cabbage). Absolute amounts of native D-AA were totally 28–57 μmol L−1 in fruit juices, 14.5 μmol L−1 in a tomato juice and 8.5 μmol L−1 in a carrot juice.
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    URL: http://dx.doi.org/10.1007/BF02278756
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    Temperature effect in separation of fullerene by high-performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 453-459 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fullerenes ; Octadecylsilicas ; Temperature effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The effect of column temperature, especially at low temperatures, on the separation of fullerenes on monomeric and polymeric octadecyl silica (ODS) bonded phases has been studied. Decreasing the column temperature induces an increase in selectivity. The best temperature for the separation of fullerenes was determined for both types of ODS phase with n-hexane eluent. The selectivity for higher fullerenes on monomeric phases becomes similar to that on polymeric phases to low temperature. It has been found that as the carbon content of monomeric phases is increased, the selectivity also becomes similar to polymeric phases.
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    URL: http://dx.doi.org/10.1007/BF02278762
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    A chromatographic and chemometric study of the bark phenolic compounds of two poplar clones with different resistance toDiscosporium populeum (1994)
    Springer
    Chromatographia 39 (1994), S. 481-489 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenolic compounds ; Poplar bark ; Discosporium populeum infection ; Chemometric data evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase high performance liquid chromatography with diode array detection was used to analyze phenolic compounds contained in bark extracts of two different poplar clones known to have different resistance toDiscosporium populeum infection. Statistical treatments both monovariate and multivariate were applied to the results in order to identify regularities useful to discriminate the polar resistance and to check the importance of seasonal and cultivation site related factors. For the two clones examined phenolic compounds showed great discrimination ability not influenced by either sample collection period or cultivation site.
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    URL: http://dx.doi.org/10.1007/BF02278766
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    Determination of catecholamines in urine by micellar liquid chromatography with coulometric detection (1994)
    Springer
    Chromatographia 39 (1994), S. 591-596 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Catecholamines in urine ; Coulometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of catecholamines by HPLC with a sodium dodecyl-sulphate (SDS), micellar mobile phase on a C18 column and with coulometric detection was studied. The eluate was conditioned at +0.25 and +0.00 V, and the current at −0.16V was recorded. A previously developed model which describes the chromatographic behaviour of solutes in HPLC with hybrid, micellar mobile phases was used to optimize the SDS and ethanol concentrations. A mobile phase of 0.15M SDS in a phosphate buffer of pH 3.4 and without ethanol is recommended. The limits of detection were 0.4–0.7 ng ml−1. The procedure was applied to the determination of unconjugated L-dopa, norepinephrine and dopamine in urine. Direct injection of the urine samples gave high results but the unconjugated catecholamines could be determined with a single solid-phase extraction step on an alumina column.
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    URL: http://dx.doi.org/10.1007/BF02268285
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    Improved separation of diastereoisomers in capillary electrophoresis using a mixture of β-cyclodextrin and sodium taurodeoxycholate (1994)
    Springer
    Chromatographia 39 (1994), S. 627-630 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar electrokinetic capillary electrophoresis ; Tetrahydrocarbazole derivatives ; β-Cyclodextrin ; Taurodeoxycholate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 2,3,4,6-tetra-O-acetyl-β-D-glucopranosyl isothiocyanate derivatives of a number of basic compounds, containing one chiral center, have been prepared. The indirect resolution of enantiomers was achieved with a high separation efficiency by capillary electrophoresis, using a sodium taurodeoxycholate/β-cyclodextrin system. This methodology was found to be superior to the resolution of the same derivatives by reversed phase HPLC analysis. A possible mechanism for stereoselectivity is described.
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    URL: http://dx.doi.org/10.1007/BF02268292
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    Calcified structures and calcification in protists (1994)
    Springer
    Protoplasma 181 (1994), S. 78-105 
    Details
    ISSN: 1615-6102
    Keywords: Calcification ; Coccolithophorids ; Coccolithogenesis ; Foraminifera ; Protists ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The diversity of calcified structures found in protists, the mechanisms utilized to form these structures, and the role these structures play in the taxonomy and systematics of the protists are presented. The two most frequently studied orders of protists which produce calcified structures, the coccolithophorids and foraminifera, are featured. However, consideration is given to the less known and least studied organisms.
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    Recombinant protein expression in aDrosophila cell line: comparison with the baculovirus system (1994)
    Springer
    Cytotechnology 15 (1994), S. 139-144 
    Details
    ISSN: 1573-0778
    Keywords: Baculovirus ; cell culture ; Drosophila ; gene expression ; insect cell ; metallothionein promoter ; recombinant protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In this report, we compare two different expression systems: baculovirus/Sf9 and stable recombinantDrosophila Schneider 2 (S2) cell lines. The construction of a recombinant S2 cell line is simple and quick, and in batch fermentations the cells have a doubling time of 20 hours until reaching a plateau density of 20 million cells/ml. Protein expression is driven by theDrosophila Metallothionein promoter which is tightly regulated. When expressed in S2 cells, the extracellular domain of human VCAM, an adhesion molecule, is indistinguishable from the same protein produced by baculovirus-infected Sf9 cells. Additionally, we present data on the expression of a seven trans-membrane protein, the dopamine D4 receptor, which has been successfully expressed in both systems. The receptor integrates correctly in the S2 membrane, binds [3H]spiperone with high affinity and exhibits pharmacological characteristics identical to that of the receptor expressed in Sf9 and mammalian cells. The general implications for large scale production of recombinant proteins are discussed.
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    URL: http://dx.doi.org/10.1007/BF00762388
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    Molecular heterogeneity of naturally occurringsn-glycerol-3-phosphate dehydrogenase low-activity variants inDrosophila melanogaster (1994)
    Springer
    Biochemical genetics 32 (1994), S. 161-179 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; glycerol-3-phosphate ; dehydrogenase ; low activity ; DNA sequence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Northern analyses of two low-activitysn-glycerol-3-phosphate dehydrogenase(Gpdh) alleles extracted from natural populations ofDrosophila melanogaster showed that one of them,Gpdh ACyg22 , produced wild-type levels of a normal sized (1.7-kb) mRNA but the other,Gpdh AMB5 , had very low levels of a 1.7-kb mRNA together with low levels of a transcript 200 bp larger. The two variant genes were cloned and sequenced. Compared with normal activity alleles, there were two nucleotide differences in the DNA sequence ofGpdh ACyg22 which were in first-codon positions and would be expected to give rise to Asn-13 → Tyr and Arg-272 → Cys substitutions. The second of these changes is most likely to account for the altered properties of the enzyme. In contrast, none of the nucleotide differences inGpdh AMB5 would give rise to amino acid substitutions, but a 76-bp deletion in the 5′ region removed the normal TATA box and there was a 20-bp insertion in the same region. One of the two transcripts was derived from the use of a substitute TATA box sequence in the insertion, but the 1.9-kb transcript had heterogeneous 5′ ends that were not associated with substitute TATA box sequences. The two transcripts either are produced at a lower rate or are less stable than the normal mRNA.
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    Histone H4 acetylated at lysine 16 and proteins of theDrosophila dosage compensation pathway co-localize on the male X chromosome through mitosis (1994)
    Springer
    Chromosome research 2 (1994), S. 398-404 
    Details
    ISSN: 1573-6849
    Keywords: dosage compensation ; Drosophila ; histone acetylation ; nuclear domains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the fruit flyDrosophila, dosage compensation involves several proteins acting in concert to double the transcriptional activity of genes on the single male X chromosome. Three of these proteins, MLE, MSL-1 and histone H4 acetylated at lysine 16 (H4Ac16), have recently been shown to be located almost exclusively on the male X chromosome in interphase (polytene) cells. We show here that in neuroblasts from third instarDrosophila larvae antisera to H4Ac16, MLE and MSL-1 uniquely label the distal, euchromatic region of the male X chromosome through mitosis. The centromere-proximal, heterochromatic region of the male X is not labelled with these antisera, nor are male autosomes or any chromosomes in female cells. That the association of H4Ac16 with the male X chromosome persists, even when the chromosome is maximally compacted and transcriptionally quiescent, argues that this modified histone is an integral component of the dosage compensation pathway. In the nuclei of interphase neuroblasts from male (but never female) larvae, antibodies to H4Ac16 revealed a small, brightly labelled patch against a background of generally weak nuclear staining. In double-labelling experiments, this patch was also labelled, albeit comparatively weakly, with antibodies to MSL-1. These results strongly suggest that the distal, euchromatic region of the X chromosome in male cells occupies a limited and relatively compact nuclear domain.
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    bHLH proteins encoded by theEnhancer of split complex ofDrosophila negatively interfere with transcriptional activation mediated by proneural genes (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 465-473 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Enhancer of split ; Helix-loop-helix protein ; Neurogenesis ; Transcriptional repressors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract TheEnhancer of split complex [E(SPL)-C] ofDrosophila participates in the control of cell fate choice by uncommitted neuroectodermal cells in the embryo. It encodes seven proteins that belong to the basic helix-loop-helix (bHLH) family, six of which are expressed in very similar patterns in the neuroectoderm. Here we describe experiments aimed at unravelling the molecular basis of their function. We found that two products of the complex, HLH-M5 andEnhancer of split, are capable of binding as homo-and heterodimers to a sequence in the promoters of theEnhancer of split andachaete genes, called the N-box, which differs slightly from the consensus binding site (the E-box) for other bHLH proteins. In transient expression assays in cell culture, both proteins were found to attenuate the transcriptional activation mediated by the proneural bHLH proteinslethal of scute anddaughterless at theEnhancer of split promoter.
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    URL: http://dx.doi.org/10.1007/BF00583897
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    Discrimination of related transcribed and non-transcribed repetitive DNA sequences from the Y chromosomes of Drosophila hydei and Drosophila eohydei (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 54-62 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Y chromosome ; Fertility genes Lampbrush loops ; Repetitive DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The short arm of the Y chromosome of Drosophila hydei carries a single male fertility gene, gene Q, which forms the lampbrush loop pair Nooses. Conflicting observations have been reported concerning the identity of the repetitive DNA sequences that are transcribed in this loop pair. It has been claimed by other investigators that the loop transcripts contain repeats of two distinct, but related families of Y-specific repetitive DNA sequences, ayl and YsI. We reinvestigated this issue, using as probes single ayl and YsI repeats which, under stringent conditions, hybridize only to members of their own family. Under non-stringent conditions, both repeats hybridize in situ to Nooses transcripts. However, if hybridization conditions are stringent, only the ayl probe hybridizes to loop transcripts. Hybridizations to Northern blots of testis RNA confirm these results. Further, YsI repeats are not found the closely related species D. eohydei. We conclude that the YsI repeats are not relevant for the function of fertility gene Q.
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    Drosophila GABAergic systems II. Mutational analysis of chromosomal segment 64AB, a region containing the glutamic acid decarboxylase gene (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 555-564 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Glutamic acid decarboxylase ; GAD ; GABA ; Lethal mutations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Drosophila melanogaster Gad gene maps to region 64A3-5 of chromosome 3L and encodes glutamic acid decarboxylase (GAD), the rate-limiting enzyme for the synthesis of the inhibitory neurotransmitter γ-aminobutyric acid (GABA). Because this neurotransmitter has been implicated in developmental functions, we have begun to study the role of GABA synthesis during Drosophila embryogenesis. We show that Gad mRNA is expressed in a widespread pattern within the embryonic nervous system. Similarly, GAD-immunoreactive protein is present during embryogenesis. These results prompted us to screen for embryonic lethal mutations that affect GAD activity. The chromosomal region to which Gad maps, however, has not been subjected to an extensive mutational analysis, even though it contains several genes encoding important neurobiological, developmental, or cellular functions. Therefore, we have initially generated both chromosomal rearangements and point mutations that map to the Drosophila 64AB interval. Altogether, a total of 33 rearrangements and putative point mutations were identified within region 64A3-5 to 64B12. Genetic complementation analysis suggests that this cytogenetic interval contains a minimum of 19 essential genes. Within our collection of lethal mutations are several chromosomal rearrangements, two of which are in the vicinity of the Gad locus. One of these rearrangements, Df(3L)C175, is a small deletion that removes the Gad locus and at least two essential genes; the second, T(2;3)F10, is a reciprocal translocation involving the second and third chromosomes with a break within region 64A3-5. Both of these rearrangements are associated with embryonic lethality and decreased GAD enzymatic activity.
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    URL: http://dx.doi.org/10.1007/BF00284204
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    Transcription of repetitive DNA sequences in the lampbrush loop pair Nooses formed by sterile alleles of fertility gene Q on the Y chromosome of Drosophila hydei (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 653-660 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Fertility genes ; Y chromosome Lampbrush loops ; Repetitive DNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Y chromosomal lampbrush loop-forming male fertility genes of Drosophila consist mainly of repetitive DNA sequences that do not code for proteins. We investigated whether differences in the transcription of these sequences can be detected in male-sterile alleles of male fertility gene Q, which forms the loop pair Nooses. The loop consists, for approximately two-thirds, of repeats of the Y-specific ay1 family of repetitive DNA sequences. Of the remaining one-third, at least one-half is represented by defective retrotransposons of the gypsy family. Both sequence types are interspersed throughout the loop. Using both ay1 and gypsy sequences as probes for transcript in situ hybridization, we show that, at the level of the light microscope, transcription of neither sequence is detectably affected in the loops formed by a male-sterile allele of gene Q. We conclude that the transcription of ay1 and gypsy is required, but not sufficient for the function of gene Q.
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    URL: http://dx.doi.org/10.1007/BF00282756
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    The lysozyme locus in Drosophila melanogaster: an expanded gene family adapted for expression in the digestive tract (1994)
    Springer
    Molecular genetics and genomics 242 (1994), S. 152-162 
    Details
    ISSN: 1617-4623
    Keywords: Antibacterial ; Digestive tract ; Drosophila ; Gene family ; Lysozyme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lysozyme has been studied in insects as part of the system of inducible antibacterial defence in the haemolymph. We recently found two Drosophila lysozyme genes that are constitutively expressed in the digestive tract, and are probably involved in the digestion of bacteria in the food. To obtain an overview of the lysozyme genes in this species and their possible roles in immunity and digestion, we have now characterized all six lysozyme genes in the cloned part of the lysozyme locus at 61F, and a seventh gene that maps to the same chromosomal location. The expression of the genes follows four different patterns: firstly, four closely related genes, LysB, C, D and E, are all strongly expressed in the midgut of larvae and adults; secondly, LysP is expressed in the adult salivary gland; thirdly, LysS is expressed mainly in the gastric caecae of larvae; and finally, LysX is primarily expressed in the metamorphosing midgut of late larvae and early pupae. The LysD-like genes and LysS are strongly repressed in artificially infected animals, possibly reflecting a malaise reaction in the digestive tract. None of the genes is expressed in the fat body or haemocytes. Thus rather than being a component of the haemolymph, the Drosophila lysozymes are found mainly in the digestive tract where they are expressed at a high level. Furthermore all genes, except LysP, encode acidic proteins, in contrast to the strongly basic “typical” lysozymes. This is highly reminiscent of the situation in ruminants, where the lysozymes have been recruited for the digestion of symbiotic bacteria in the stomach.
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    Functional relationships between genes of the Shaker gene complex of Drosophila (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 197-204 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; Shaker gene complex Dominant lethality ; K+ channel ; Troponin I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different mutations belonging to the HLI and HLII complementation groups of the haplolethal (HL) region of the Shaker complex (ShC) are described. The HLI complementation group includes viable (hdp), recessive lethals [l(1)1614], semidominant lethals [l(1)8384] and dominant lethals [l(1)5051,l(1)9916, l(1)13193], lack-of-function alleles that affect nervous system, cuticle and muscle development. The HLI complementation group encodes troponin I. HLII lack-of-function mutations [l(1)174 and l(l)4058] affect nervous system development. The semidominant lethal HLI mutation 1(1)8384 shows differential complementation with other mutations in the ME and HL regions of ShC. Thus, heterozygous combinations of l(1)8384 with ME mutations l(1)162 and l(1)387 are poorly viable. The same phenomenon is observed for heterozygotes of l(1)8384 with HL mutations l(1)1199, l(1)2288 and l(1)3014. These specific interactions indicate the existence of functional relationships among the genetic elements of ShC. The implications for the understanding of the functional organization of ShC are discussed.
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    URL: http://dx.doi.org/10.1007/BF00283523
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    Functional interactions between the gene tetanic and the Shaker gene complex of Drosophila (1994)
    Springer
    Molecular genetics and genomics 244 (1994), S. 205-215 
    Details
    ISSN: 1617-4623
    Keywords: Drosophila ; tetanic ; Shaker gene complex ; Maternal effect ; K+ channel modulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Different phenotypes associated with the tetanic (tta) mutation such as appendage contraction, maternal effect and low viability and fertility are enhanced by one extra dose of the Shaker gene complex (ShC). The tta mutation is lethal with two extra doses of ShC. In addition, tta embryos have a defective nervous system. In this paper, I analyse the interaction between tta and ShC to gain insight into their relationship. Aneuploid analysis suggests that the lethality is due to an interaction of the tta mutation with the maternal effect (ME) region of this gene complex. Mutations in the ME region of ShC partially suppress this interaction. Trans-heterozygous combinations of MEI[l(1)305] and MEIII [l(1)459] mutations causes dominant lethality in a tta background. Trans-heterozygous combinations of an MEII [l(1)1359] mutation with the cited MEI and MEIII mutations are lethal in a tta background. Double mutant combinations and gene dosage experiments, suggest that tta also interacts with the viable (V) region of ShC. These specific genetic interactions indicate that tta and the ME and V regions of ShC are functionally related. These results, together with the previous electrophysiological, molecular and biochemical studies on these mutants suggest an interaction at the protein level. Thus, in the case of the V region, the tta gene product may modulate the activity of the K+ channels encoded in this region. Furthermore, the extreme dosage sensitivity of the interaction between tta and ShC suggests a stoichiometric requirement for the different gene products involved, which might be physically associated and form heteromultimers.
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    URL: http://dx.doi.org/10.1007/BF00283524
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    Drosophila melanogaster acetylcholinesterase: Identification and expression of two mutations responsible for cold- and heat-sensitive phenotypes (1994)
    Springer
    Molecular genetics and genomics 243 (1994), S. 699-705 
    Details
    ISSN: 1617-4623
    Keywords: Acetylcholinesterase ; Drosophila ; Thermosensitive mutation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ace IJ29 and Ac IJ40 are cold- and heat-sensitive variants of the gene coding for acetylcholinesterase in Drosophila melanogaster. In the homozygous condition, these mutations are lethal when animals are raised at restrictive temperatures, i.e., below 23° C for Ace IJ29 or above 25° C for Ace IJ40. The coding regions of the gene in these mutants were sequenced and mutations changing Ser374 to Phe in Ace IJ29 and Pro75 to Leu in Ace IJ40 were found. Acetylcholinesterases bearing these mutations were expressed in Xenopus oocytes and we found that these mutations decrease the secretion rate of the protein most probably by affecting its folding. This phenomenon is exacerbated at restrictive temperatures decreasing the amount of secreted acetylcholinesterase below the lethality threshold. In parallel, the substitution of the conserved Asp248 by an Asn residue completely inhibits the activity of the enzyme and its secretion, preventing the correct folding of the protein in a non-conditional manner.
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    URL: http://dx.doi.org/10.1007/BF00279580
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    DPhK-γ, a putative Drosophila kinase with homology to vertebrate phosphorylase kinase γ subunits: molecular characterisation of the gene and phenotypic analysis of loss of function mutants (1994)
    Springer
    Molecular genetics and genomics 245 (1994), S. 588-597 
    Details
    ISSN: 1617-4623
    Keywords: Phosphorylase kinase γ gene ; Kinase ; Drosophila ; Maternal effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Partial and total loss of function mutant alleles of a putative Drosophila homologue (DPhK-γ) of the vertebrate phosphorylase kinase γ-subunit gene have been isolated. DPhK-γ is required in early embryonic processes, such as gastrulation and mesoderm formation; however, defects in these processes are seen only when both the maternal and zygotic components of DPhK-γ expression are eliminated. Loss of zygotic expression alone does not appear to affect normal embryonic and larval development; some pupal lethality is observed but the majority of mutant animals eclose as adults. Many of these adults show defects in their leg musculature (e.g. missing and degenerating muscles), in addition to exhibiting melanised “tumours” on their leg joints. Loss of only the maternal component has no obvious phenotypic consequences. The DPhKγ gene has been cloned and sequenced. It has an open reading frame (ORF) of 1680 by encoding a 560 amino acid protein. The predicted amino acid sequence of DPhK-γ has two conserved domains, the catalytic kinase and calmodulin-binding domains, separated by a linker sequence. The amino acid sequence of DPhK-γ is homologous to that of mammalian PhK-γ proteins but differs in the length and amino acid composition of its linker sequence. The expression of DPhK-γ mRNA is developmentally regulated. We discuss the implications of these observations.
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    URL: http://dx.doi.org/10.1007/BF00282221
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    DrosophilaP element: Transposition, regulation and evolution (1994)
    Springer
    Genetica 93 (1994), S. 61-78 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; transposable elements ; hybrid dysgenesis ; transcriptional regulation ; horizontal transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435240
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    Genome and stresses: Reactions against aggressions, behavior of transposable elements (1994)
    Springer
    Genetica 93 (1994), S. 149-160 
    Details
    ISSN: 1573-6857
    Keywords: environment ; genome ; stress ; transposable elements ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The action of stresses on the genome can be considered as responses of cells or organisms to external aggressions. Stress factors are of environmental origin (climatic or trophic) or of genomic nature (introduction of foreign genetic material, for example). In both cases, important perturbations can occur and modify hereditary potentialities, creating new combinations compatible with survival; such a situation may increase the variability of the genome, and allow evolutive processes to take place. The behavior of transposable elements under stress conditions is thus of particular interest, since these sequences are sources of mutations and therefore of genetic variability; they may play an important role in population adaptation. The survey of the available experimental results suggests that, although some examples of mutations and transposable elements movements induced by external factors are clearly described, environmental injuries or introduction of foreign material into a genome are not systematically followed by drastic genomic changes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01435247
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    Analysis of nucleotide substitutions and amino acid conservation in theDrosophila Adh genomic region (1994)
    Springer
    Genetica 94 (1994), S. 27-36 
    Details
    ISSN: 1573-6857
    Keywords: Adh ; Adh-dup ; Drosophila ; molecular clock ; nucleotide substitution rates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The homologous genomic region that contains two paralogous genes,Adh andAdh-dup, was compared in severalDrosophila species. Sequences were analyzed as follows: a) At the nucleotide level, Ka and Ks values were determined for each pair of species. Ka-Adh and Ka-Adh-dup are not significantly different. However, Ks-Adh values are significantly lower than Ks-Adh-dup, which are more variable. In agreement with other reports, lower Ks values forAdh correlate with a high level of gene expression and relatively high percentage of G+C content in the third codon position, while the opposite applies toAdh-dup. b) At the protein level, amino acid comparisons reveal conserved regions shared by ADH and ADH-DUP, which have been assigned to known functional domains. Key residues for dehydrogenasic function are also found in ADH-DUP, thus pointing to a dehydrogenase activity for ADH-DUP, albeit very different from that of ADH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429217
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