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  • Springer  (48)
  • 1995-1999  (11)
  • 1990-1994  (31)
  • 1980-1984  (6)
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  • 11
    Electronic Resource
    Electronic Resource
    Host-parasite dynamics and the evolution of host immunity and parasite fecundity strategies (1997)
    Springer
    Bulletin of mathematical biology 59 (1997), S. 427-450 
    Details
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract We explore evolutionarily stable co-evolution of host-macroparasite interactions in a discrete-time two-species population dynamics model, in which the dynamics may be stable, cyclic or chaotic. The macroparasites are assumed to harm host individuals through decreased reproductive output. Hosts may develop costly immune responses to defend themselves against parasites. Parasites compete with conspecifics by adjusting their fecundities. Overall, the presence of both parasites and the immune response in hosts produces more stable dynamics and lower host population sizes than that observed in the absence of the parasites. In our evolutionary analyses, we show that maximum parasite fecundity is always an evolutionarily stable strategy (ESS), irrespective of the type of population interaction, and that maximum parasite fecundity generally induces a minimum parasite population size through over-exploitation of the host. Phenotypic polymorphisms with respect to immunity in the host species are common and expected in ESS host strategies: the benefits of immunication depend on the frequency of the immune hosts in the population. In particular, the steady-state proportions of immune hosts depend, in addition to all the parameters of the parasite dynamics only on the cost of immunity and on the virulence of parasites in susceptible hosts. The implicit ecological dynamics of the host-parasite interaction affect the proportion of immune host individuals in the population. Furthermore, when changes in certain population parameters cause the dynamics of the host-parasite interaction to move from stability to cyclicity and then to chaos, the proportion of immune hosts tends to decrease; however, we also detected counter-examples to this result. As a whole, incorporating immunological and genetic aspects, as well as life-history trade-offs, into host-macroparasite dynamics produces a rich extension to the patterns observed in the models of ecological interactions and epidemics, and deserves more attention than is currently the case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02459459
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  • 12
    Electronic Resource
    Electronic Resource
    Transgenic analysis of the 5′- and 3′-flanking regions of the NADH-dependent hydroxypyruvate reductase gene from Cucumis sativus L. (1995)
    Springer
    Plant molecular biology 28 (1995), S. 821-836 
    Details
    ISSN: 1573-5028
    Keywords: cucumber ; light-regulated gene expression ; NADH-dependent hydroxypyruvate reductase ; organ-specific gene expression ; peroxisome ; photorespiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The 5′- and 3′-flanking regions of HPRA, a cucumber gene that encodes hydroxypyruvate reductase, were evaluated for regulatory activity with respect to light responsiveness and organ specificity. To define the functional regions of the 5′-flanking region of HPRA, a series of deletions was generated and the remaining portions fused to the β-glucuronidase (GUS) reporter gene (uidA) containing a minimal 35S promoter truncated at −90. The region from −66 to +39 was found to be necessary for light-regulated expression of the uidA reporter gene, while the region from −382 to −67 was found to be necessary for its leaf-specific expression. Further deletion of the HPRA 5′ flanking region to −590 resulted in high levels of root expression, suggesting the presence of a negative regulatory element responsible for silencing root expression of the HPRA gene between −590 and −383. The 3′-flanking region of the HPRA gene downstream of the polyadenylation site contains several sequence motifs resembling regulatory elements present in the promoters of several light-responsive genes. An 823 bp portion of the HPRA 3′-flanking region containing these putative regulatory elements enhanced GUS expression in leaves when placed downstream of the uidA reporter gene in the forward orientation, but not in the reverse orientation. When placed 5′ of the −90 35S promoter, the 823 bp fragment enhanced slightly, independently of orientation, the root tip-specific expression pattern intrinsic to the −90 35S promoter, indicating that in some cases this region can act as a transcriptional enhancer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00042068
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  • 13
    Electronic Resource
    Electronic Resource
    Interaction of DNA-binding proteins with the 5′-flanking region of a cytokinin-responsive cucumber hydroxypyruvate reductase gene (1998)
    Springer
    Plant molecular biology 38 (1998), S. 713-723 
    Details
    ISSN: 1573-5028
    Keywords: cucumber ; cytokinin-responsive ; DNA-binding proteins ; hydroxypyruvate reductase ; transcription
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transcription of the cucumber hpr-A gene is responsive to cytokinin and light. To investigate the molecular basis for transcriptional regulation by cytokinin, we have identified DNA sequences and proteins that may be involved in the regulation of hpr-A gene expression. Transient expression assays in etiolated cucumber cotyledons indicate that the 315 bp fragment (−382 to −67) contains sequences necessary for cytokinin responsiveness of the luciferase reporter gene. Band shift assays detected cytokinin-enhanced and -reduced protein binding sites in a 97 bp fragment (−382 to −285) upstream of the hpr-A gene. DNase I footprinting identified two protein-protected sites, a 15 bp sequence, 5′-AAATGACGAAAATGC-3′, that contains an as-1 TGACG motif found in other plant promoters, and a 13 bp sequence, 5′-AAGATTGATTGAG-3′, of unknown function. Two-dimensional band shift analysis of the cytokinin-responsive DNA protein complex revealed the presence of six DNA protein interactions. Band shift assays showed that cytokinin and light have different effects on the interaction of nuclear proteins to the 97 bp fragment of the hpr-A gene. These data suggest that cytokinin and light do not share identical signal transduction pathways in regulating hpr-A gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006034932322
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  • 14
    Electronic Resource
    Electronic Resource
    Characterization of genes encoding hydroxypyruvate reductase in cucumber (1991)
    Springer
    Plant molecular biology 17 (1991), S. 941-947 
    Details
    ISSN: 1573-5028
    Keywords: hydroxypyruvate reductase ; light regulation ; peroxisomal enzymes ; photorespiration ; plant gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Several clones corresponding to the gene encoding NADH-dependent hydroxypyruvate reductase have been isolated from a cucumber genomic library. Restriction mapping indicates the presence of two HPR genes, hpr-A and hpr-B, in the cucumber genome. Examination of the DNAs of individual plants suggests that hpr-A and hpr-B are most likely alleles at a single locus. The sequence of a 6.7 kb genomic fragment that includes the entire transcribed region, 2.2 kb of 5′ flanking sequence, and about 0.8 kb of 3′ flanking sequence reveals the presence of 12 introns in hpr-A. These introns are AT-rich relative to the exons. The donor sequence at the 5′ end of the sixth intron contains an unusual dinucleotide, GC, rather than the nearly invariant GT. Primer extension analysis maps the transcription initiation site to 61 nucleotides upstream of the translation initiation codon. An AT-rich stretch is centered at position −31 with respect to the transcription initiation site, and a potential CCAAT box is centered at position −138. Several elements that are homologous to regulatory elements of other plant genes have been identified in the flanking regions of hpr-A.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00037078
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  • 15
    Electronic Resource
    Electronic Resource
    G. R. Carmichael, G. E. Folk and J. L. Schnoor (eds.): 1995, Preparing for Global Change: A Midwestern Perspective (1997)
    Springer
    Climatic change 37 (1997), S. 569-573 
    Details
    ISSN: 1573-1480
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005330330263
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  • 16
    Electronic Resource
    Electronic Resource
    The Student Integration Survey: Development of an early alert assessment and reporting system (1993)
    Springer
    Research in higher education 34 (1993), S. 513-531 
    Details
    ISSN: 1573-188X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract This study describes efforts to develop a self-report rating scale (Student Integration Survey: SIS) that provides diagnostic information about students with academic and/or social integration difficulties. Data obtained from administration of the SIS to incoming freshmen at a postsecondary technical institution for the deaf in the fall of 1990 and 1991 were subjected to Rasch rating scale analysis. Fit of data to the measurement model resulted in a set of 28 positive and negative statements that empirically defined the concept of “institutional integration” in terms of their calibration hierarchy. This type of instrument calibration has the potential of providing person measures and item scale values that are invariant over a useful range of comparisons. The early alert reporting system provides an evaluation and diagnosis of observed responses relevant to expected responses for individual respondees. The substance and methods employed may provide a model for other integration assessment efforts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00991858
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  • 17
    Electronic Resource
    Electronic Resource
    Avoiding metric monsters: A design metrics approach (1995)
    Springer
    Annals of software engineering 1 (1995), S. 43-55 
    Details
    ISSN: 1573-7489
    Keywords: Design metrics ; design metrics analyzer ; metrics model ; software metrics ; software quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Metric monsters are stumbling blocks that prevent software metrics-guided methodologies from attaining product and process improvement. Metric monsters can occur during the identification, collection or application of software metrics. In our research, we have developed and tested our design metrics over a five-year period and have found them to be excellent predictors of error-prone modules. Based on this research, we will identify some of the monsters that occur in the quantitative analyses of software and its development processes, and present our approach in formulating a design metrics model that avoids these monsters. This model consists of software tools, guidelines and actions for the application of software design metrics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02249045
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  • 18
    Electronic Resource
    Electronic Resource
    Changes in soil organic matter with cropping as measured by organic carbon fractions and 13C natural isotope abundance (1993)
    Springer
    Plant and soil 155-156 (1993), S. 399-402 
    Details
    ISSN: 1573-5036
    Keywords: carbon-13 ; cropping systems ; δ13C ; KMnO4 oxidation ; soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The decline in soil organic matter with cropping is a major factor affecting the sustainability of cropping systems. Changes in total C levels are relativelyinsensitive as a sustainability measure. Oxidation with different strength KMnO4 has been shown to be a more sensitive indicator of change. The relative size of soil C fractions oxidised by 333 mM KMnO4 declined with cropping, whilst the relative size of the unoxidised fraction increased. Changes in δ13C ratio have been used to measure C turnover in systems which include C3 and C4 species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025067
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  • 19
    Electronic Resource
    Electronic Resource
    An inclusive fitness model for the evolutionary advantage of sibmating (1994)
    Springer
    Evolutionary ecology 8 (1994), S. 61-69 
    Details
    ISSN: 1573-8477
    Keywords: sibmating ; inbreeding depression ; haplodiploid ; inclusive fitness ; one-locus genetic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We construct an inclusive fitness model of the relative selective advantage of sibmating and outbreeding behaviour, under the assumption that inbred offspring pay a fitness penalty. We are particularly interested in the question of whether such inbreeding depression is enough to generate a stable phenotypic polymorphism, with both kinds of breeding observed. The model predicts that, under diploidy, such a polymorphism is never found, but under haplodiploidy, it exists for a narrow range of parameter values. The inclusive fitness argument is technically interesting because care must be taken with reproductive values. We also present a corrected version of a one-locus genetic model for sibmating and find that the inclusive fitness and genetic models give identical results when selection is weak.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237666
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  • 20
    Electronic Resource
    Electronic Resource
    Metaphysiological and evolutionary dynamics of populations exploiting constant and interactive resources:R—K selection revisited (1993)
    Springer
    Evolutionary ecology 7 (1993), S. 287-305 
    Details
    ISSN: 1573-8477
    Keywords: evolutionary dynamics ; populations ; interactive resources
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary I begin by reviewing the derivation of continuous logistic growth and dynamic consumer—resource interaction equations in terms of specific resource extraction and biomass conversion functions that are considered to hold at a population level. Evolutionary stable strategy (ESS) methods are discussed for analysing populations modelled by these equations. The question of selection trade-offs is then considered, particularly in the context of populations being efficient at extracting resources versus converting resources to their own biomass. Questions relating to single populations with high versus low conversion rates and interacting populations with high versus low self-interference rates are also considered. The models discussed here demonstrate conclusively that self-interference is an essential part of any consumption process: without it population growth and interaction processes do not make any sense. The analysis clarifies concepts relating to the somewhat discredited notion ofr—K selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237746
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