ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Drosophila  (741)
  • Evolution  (687)
  • Springer  (1.411)
  • Frontiers Media SA  (6)
  • 1
    Publikationsdatum: 2024-04-05
    Beschreibung: The brain functions within an internal environment that is determined and controlled by morphological structures and cellular mechanisms present at interfaces between the brain and the rest of the body. In vertebrates these interfaces are across cerebral blood vessels (blood-brain barrier) choroid plexuses (blood-cerebrospinal fluid barrier) and pia-arachnoid. There is a CSF-brain barrier in the neuroepithelium lining the ventricular system that is only present in embryos. There is now substantial evidence that many brain barrier mechanisms develop early and that in some cases they are functionally more active and even more specialized compared to adult barriers. Therefore barriers in developing brain should be viewed as adapted appropriately for the growing brain and not, as is still widely believed, immature. Considerable advances in our understanding of these barrier mechanisms have come from studies of the developing brain and invertebrates. A striking aspect, to be highlighted in this special edition, is that many of the molecular mechanisms in these very diverse species are similar despite differences in the cellular composition of the interfaces. This Frontiers Topic comprises articles in three sections: Original studies, Reviews and Myths & Misconceptions. Original articles provide new information on molecular and cellular barrier mechanisms in developing brains of primates, including human embryos (Brøchner et al., Ek et al., Errede et al.), rodents (Bauer et al., Liddelow, Strazielle & Ghersi-Egea, Saunders et al., Whish et al.), chick (Bueno et al.) and zebrafish (Henson et al.) as well as studies in drosophila (Hindle & Bainton, De Salvo et al., Limmer et al.). The Reviews section includes evolutionary perspectives of the blood-brain and blood-CSF barriers (Bueno et al., Bill & Korzh). There are also detailed reviews of the current state of understanding of different interfaces and their functional mechanisms in developing brain (Bauer et al., Strazielle & Gjersi-Egea, Liddelow, Richardson et al., Errede et al., Henson et al., Brøchner et al.) and in invertebrates (Hindle & Bainton, De Salvo et al., Limmer et al). Different aspects of the relationship between properties of the internal environment of the brain and its development are discussed. (Stolp & Molnar, Johansson, Prasongchean et al.). A neglected area, namely barriers over the surface of the brain during development is also covered (Brøchner et al.). Clinically related perspectives on barrier disruption in neonatal stroke are provided by Kratzer et al. and other aspects of dysfunction by Morretti et al. and by Palmeta et al. on the continuing problem of bilirubin toxicity. Progress in this field is hampered by many prevailing myths about barrier function, combined with methodologies that are not always appropriately selected or interpreted. These are covered in the Misconceptions, Myths and Methods section, including historical aspects and discussion of the paracellular pathway, a central dogma of epithelial and endothelial biology (Saunders et al.) and a review of markers used to define brain barrier integrity in development and in pathological conditions (Saunders et al.). Use of inappropriate markers has caused considerable confusion and unreliable interpretation in many published studies. Torbett et al. deal with the complexities of the new field of applying proteomics to understanding blood-brain barrier properties as do Huntley at al. with respect to applying modern high throughput gene expression methods (Huntley et al.). The Editorial summarizes the contributions from all authors. This includes mention of some the main unanswered but answerable questions in the field and what the impediments to progress may be.
    Schlagwort(e): RC321-571 ; Q1-390 ; zebra fish ; development ; Influx mechanisms ; Tight Junctions ; Drosophila ; Efflux mechanisms ; blood-CSF barrier ; Choroid Plexus ; Blood-Brain Barrier ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    facet.materialart.
    Unbekannt
    Springer Nature | Springer
    Publikationsdatum: 2024-04-05
    Beschreibung: This open access book offers the first comprehensive account of the pan-genome concept and its manifold implications. The realization that the genetic repertoire of a biological species always encompasses more than the genome of each individual is one of the earliest examples of big data in biology that opened biology to the unbounded. The study of genetic variation observed within a species challenges existing views and has profound consequences for our understanding of the fundamental mechanisms underpinning bacterial biology and evolution. The underlying rationale extends well beyond the initial prokaryotic focus to all kingdoms of life and evolves into similar concepts for metagenomes, phenomes and epigenomes. The book’s respective chapters address a range of topics, from the serendipitous emergence of the pan-genome concept and its impacts on the fields of microbiology, vaccinology and antimicrobial resistance, to the study of microbial communities, bioinformatic applications and mathematical models that tie in with complex systems and economic theory. Given its scope, the book will appeal to a broad readership interested in population dynamics, evolutionary biology and genomics.
    Schlagwort(e): Microbial Genetics and Genomics ; Evolutionary Biology ; Genetics and Population Dynamics ; Microbial Ecology ; Human Genetics ; Genetics and Genomics ; Comparative genomics ; Metagenomics ; Microbial Population Analysis ; Pangenome Profile ; Supra-Genome Analysis ; Adaptive Evolution ; Computational Tools ; Bioinformatic Genomics ; Core Dispensable Genome ; Selection, Recombination, Composition ; Acquired Resistance ; Bacterial Species Concept ; Genomic Diversity ; Bacterial Ecology, Microevolution ; Open Access ; Pan-metagenomics ; Pan-microbiomics ; Pan-epigenome ; Gene Transfer ; Pan-phenomes ; Microbiology (non-medical) ; Genetics (non-medical) ; Evolution ; Applied mathematics ; Ecological science, the Biosphere ; Medical genetics ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSG Microbiology (non-medical) ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAJ Evolution ; thema EDItEUR::P Mathematics and Science::PB Mathematics::PBW Applied mathematics ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAF Ecological science, the Biosphere ; thema EDItEUR::M Medicine and Nursing::MF Pre-clinical medicine: basic sciences::MFN Medical genetics ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAK Genetics (non-medical)
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    facet.materialart.
    Unbekannt
    Frontiers Media SA
    Publikationsdatum: 2024-04-05
    Beschreibung: This Frontiers Research Topic on ‘Neural Circuits: Japan’ explores the diversity of neural circuit research occurring across Japan by innovative researchers using cutting-edge approaches. This issue has brought together papers revealing the development, structure, and physiology of neuronal circuits involved in sensory perception, sleep and wakefulness, behavioral selection, and motor command generation in a range of species from the nematode to the primate. Like the USA and Europe, Japan is now making a strong effort to elucidate neural circuit function in diverse organisms by taking advantages of optogenetics and innovative approaches for gene manipulation, traditional physiological and anatomical approaches, and neural pathway-selective inactivation techniques that have recently been developed in Japan.
    Schlagwort(e): RC321-571 ; Q1-390 ; Cerebellum ; C. elegans ; Drosophila ; Olfactory Bulb ; Basal Ganglia ; Hypothalamus ; Neocortex ; Hippocampus ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    facet.materialart.
    Unbekannt
    Frontiers Media SA
    Publikationsdatum: 2023-12-20
    Beschreibung: A link between inflammation and cancer was initially made by Rudolf Virchow back in the 19th century. Nowadays many cancers are considered dependent on inflammatory responses to microbial and damaged-self stimuli and both arms of immunity, innate and adaptive, are playing a role in promoting cancer. Moreover, besides environmental factors, opportunistic pathogens contribute to inflammation and cancer. Nevertheless, microbial influence on chronic disease is sometimes difficult to discern, especially in the context of polymicrobial communities, such as those found in the digestive tract. In this light, model organisms provide important insights into immune and growth signals that promote cancer, and suggest therapies that will selectively target potentially harmful microbes or modulate host responses. A number of review and opinion articles in this series address novel aspects and paradigms of the interactions between the microbiota and the host in relation to inflammation and cancer.
    Schlagwort(e): Q1-390 ; RC109-216 ; microbiota ; mouse ; innate immunity ; Drosophila ; diet ; aging ; human ; Hologenome ; bic Book Industry Communication::G Reference, information & interdisciplinary subjects::GP Research & information: general
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Publikationsdatum: 2024-04-05
    Beschreibung: Since Erspamer and Boretti, 1951 first described the biogenic amine octopamine in the octopus salivary gland as a molecule with “adrenaline-like” action, decades of extensive studies demonstrated the important role octopamine and its precursor tyramine play in invertebrate physiology and behavior. This book contains the latest original research papers on tyramine/octopamine and their receptors in different neuronal and non-neuronal circuits of insects. 〈/p〉Additonally, this book elucidates in detail the latest research on the function of other biogenic amines and their receptors, such as dopamine and serotonin in insects and mice. The reviews in this book summarize the most recent research on the role of biogenic amines in insect antennae, synaptic development, and behavioral modulation by spontaneous dopamine release in Drosophila. Finally, one perspective paper discusses the evolution of social behavior and biogenic amines. 〈br〉〈br〉We recommend this book for all scholars interested in the latest advanced research on the role of biogenic amines in animal behavior. 〈br〉〈br〉ITS dedicates the topic to her teacher, Plotnikova Svetlana Ivanovna (1922-2013).
    Schlagwort(e): RC321-571 ; Q1-390 ; octopamine ; Apis mellifera ; olfactory learning and memory ; serotonin ; G-protein coupled receptors (GPCR) ; type I and II synaptic boutons ; Drosophila ; neural circuits ; tyramine ; dopamine ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAN Neurosciences
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Publikationsdatum: 2024-04-05
    Beschreibung: During their life cycle plants undergo a wide variety of morphological and developmental changes. Impinging these developmental processes there is a layer of gene, protein and metabolic networks that are responsible for the initiation of the correct developmental transitions at the right time of the year to ensure plant life success. New omic technologies are allowing the acquisition of massive amount of data to develop holistic and integrative analysis to understand complex processes. Among them, Microarray, Next-generation Sequencing (NGS) and Proteomics are providing enormous amount of data from different plant species and developmental stages, thus allowing the analysis of gene networks globally. Besides, the comparison of molecular networks from different species is providing information on their evolutionary history, shedding light on the origin of many key genes/proteins. Moreover, developmental processes are not only genetically programed but are also affected by internal and external signals. Metabolism, light, hormone action, temperature, biotic and abiotic stresses, etc. have a deep effect on developmental programs. The interface and interplay between these internal and external circuits with developmental programs can be unraveled through the integration of systematic experimentation with the computational analysis of the generated omics data (Molecular Systems Biology). This Research Topic intends to deepen in the different plant developmental pathways and how the corresponding gene networks evolved from a Molecular Systems Biology perspective. Global approaches for photoperiod, circadian clock and hormone regulated processes; pattern formation, phase-transitions, organ development, etc. will provide new insights on how plant complexity was built during evolution. Understanding the interface and interplay between different regulatory networks will also provide fundamental information on plant biology and focus on those traits that may be important for next-generation agriculture.
    Schlagwort(e): QK1-989 ; Q1-390 ; Plant Development ; Omics ; Molecular Systems Biology ; Evolution ; Gene Regulatory Networks ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PST Botany and plant sciences
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    facet.materialart.
    Unbekannt
    Frontiers Media SA
    Publikationsdatum: 2024-04-04
    Beschreibung: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact
    Schlagwort(e): Carrion ; Mass Mortality ; Organic Matter ; Decomposition ; Resource Subsidy ; Disturbance ; Pulse ; Necrobiome ; Evolution ; Food Webs ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::P Mathematics and Science::PS Biology, life sciences::PSA Life sciences: general issues::PSAF Ecological science, the Biosphere
    Sprache: Englisch
    Format: image/jpeg
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 7 (1994), S. 87-94 
    ISSN: 1432-2145
    Schlagwort(e): Evolution ; Microtubules ; Polarity Pollen ; Mitosis ; Orchids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Pollen mitosis in the slipper orchid Cypripedium fasciculatum was studied using correlated methods of immunofluorescence and transmission electron microscopy. Unlike the more highly evolved orchids, the cypripedioid orchids shed pollen as monosulcate monads. Prior to pollen mitosis, the microspore nucleus migrates to a proximal position opposite the aperture, as is typical of monocotyledons. There is no distinct generative pole microtubule system (GPMS) like that recently reported in development of pollen polarity in the vandoid moth orchid Phalaenopsis. Instead, microtubules in early prophase are concentrated around the nucleus and extend into the cytoplasm toward the future generative pole. Once the nucleus has migrated to the continuous surface opposite the aperture, microtubules surround the nucleus evenly and show no tendency to be more concentrated in the generative domain. The mitotic spindle, which develops from the perinuclear microtubules, is asymmetrically placed in the microspore and is cone-shaped. The generative pole is broad and closely appressed to the continuous spore surface, while the vegetative pole is pointed and located in the interior of the microspore. As the chromosomes move poleward, microtubules proliferate in the interzone and a phragmoplast develops. The phragmoplast expands in a hemispherical path beyond the interzone following an array of microtubules that radiates from the generative nucleus. Data from this study indicate that evolution of pollen in orchids includes a shift in location of the generative cell from proximal to distal and the evolution of a GPMS, in addition in the well-known trend toward increased pollen aggregation and loss of exine.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 9 (1996), S. 357-361 
    ISSN: 1432-2145
    Schlagwort(e): Self-incompatibility ; Evolution ; S-RNases ; Solanaceae ; Rosaceae ; Scrophulariaceae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract This review summarises current understanding of the evolution of self-incompatibility inferred from DNA sequence analysis. Self-incompatibility in many plant families is controlled by a single, highly polymorphicS-locus which, in the Solanaceae, encodes an allelic series of stylar ribonucleases known as the S-RNases. PCR approaches are a convenient way to examine the diversity of S-RNase sequences within and between wild populations of a self-incompatible species and provide a unique view into the species' current and historic population structure. Similar molecular appoaches have also been used to show that S-RNases are involved in self-incompatibility in families other than the Solanaceae. A model for the evolution of ribonuclease-based self-incompatibility systems is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 3 (1993), S. 199-224 
    ISSN: 1432-1386
    Schlagwort(e): Technological change ; Institutions ; Evolution ; Games ; C71 ; 017 ; 031
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract In this paper, we study a co-evolutionary model of economic change at two hierarchical levels. At the lower level, “institutions” are given and the focus is on how resources are allocated and innovation produced in response to the pay-off structure induced by prevailing institutions. At the higher level, it is the institutions themselves that change as the outcome of a process of social bargaining. The main objective of the paper is to study the interaction between these two levels of change, attempting to provide some insight on issues like technological/institutional divergence, technological dead-end, institutional inertia, etc.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 11
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 6 (1996), S. 1-30 
    ISSN: 1432-1386
    Schlagwort(e): Innovation ; Technology ; Master equation ; Survival probability ; Evolution ; O3
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract Technological innovations have been investigated by means of substitution and diffusion as well as evolution models, each of them dealing with different aspects of the innovation problem. In this paper we follow the well known research traditions on self-organisation models of complex systems. For the first time in the literature we show the existence of a specific niche effect, which may occur in the first stage of establishment of a new technology. Using a stochastic Master equation approach, we obtain analytical expressions for the survival probabilities of a new technology in smaller or larger ensembles. As a main result we demonstrate how a hyperselection situation might be removed in a stochastic picture and thresholds against the prevailing of a new technology in a step-by-step process can be overcome.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 12
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 7 (1997), S. 339-353 
    ISSN: 1432-1386
    Schlagwort(e): Key words: Market organisation ; Network ; Communication ; Evolution ; Learning ; JEL-classification: C70; D23; D40; L11
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. The purpose of this paper is to suggest a view of the economy as a network of links between the individuals involved. One approach is to consider the structure of links as fixed as is the case with spatial models in which agents are situated on a lattice, another is to regard all links as possible but stochastic. If the probability of any of the links existing is uniform we have the situation familiar from the “population games” of evolutionary game theory. The basic idea here is to allow the network to evolve and to make the probability of each of the links dependent on the experience of the agents involved. Such analysis can give rise to interesting behaviour on the aggregate level which is very different from that which might have been predicted by looking at the individuals in isolation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 13
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 9 (1999), S. 109-133 
    ISSN: 1432-1386
    Schlagwort(e): Key words: Discontinuity ; Evolution ; Logistic diffusion ; Non-linearity ; Non-stationarity ; Self-organisation ; Spectral methods ; JEL-classification: C4; C5; N1; N2
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. This paper offers an econometric methodology for the detection of self-organisational change (defined in terms of the presence of time irreversibility, structural change and fundamental uncertainty) in economic processes that follow logistic diffusion growth paths in historical time. The approach we adopted is built upon recent developments in `moving window' spectral methods which are applied to the scaled residuals generated by estimated logistic diffusion models. We illustrate the use of such methods by examining the case of a financial instrument, namely, the Australian Building Society Deposit, which experienced logistic growth in its market share until bank deregulation was enacted in the 1980s. We show that there is clear evidence that self-organisational change is present over the historical period considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 9 (1999), S. 367-371 
    ISSN: 1432-1386
    Schlagwort(e): Key words: Bertrand ; Oligopoly ; Evolution ; Evolutionary stability ; JEL-classification: D43 ; L13 ; C72
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. It is shown that the equilibrium notion of an evolutionary stable strategy (ESS) does have predictive power for standard models of Bertrand competition. This is in contrast to a recent claim by Qin and Stuart (1997). The claim is based on the observation that the solution concept ESS behaves discontinuously when finite (discrete) action games approach an infinite (continuous) action game in the limit. Furthermore, it is argued that from a model-theoretic point of view evolutionary stability in prices (i.e. in the Bertrand model) is quite different from evolutionary stability in quantities (i.e. in the Cournot model).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 15
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 21 (1984), S. 77-95 
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; quantitative inheritance ; random matrix theory ; morphological integration
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A quantitative genetic model of “random pleiotropy” is introduced as reference model for detecting the kind and degree of organization in quantitative genetic variation. In this model the genetic dispersion matrix takes the form of G = BB T, where B is a general, real, Gaussian random matrix. The eigenvalue density of the corresponding ensemble of random matrices (ℰG) is considered. The first two moments are derived for variance-covariance matrices G as well as for correlation matrices R, and an approximate expression of the density function is given. The eigenvalue distribution of all empirical correlation matrices deviates from that of a random pleiotropy model by a very large leading eigenvalue associated with a “size factor”. However the frequency-distribution of the remaining eigenvalues shows only minor deviations in mammalian skeletal data. A prevalence of intermediate eigenvalues in insect data may be caused by the inclusion of many functionally unrelated characters. Hence two kinds of deviations from random organization have been found: a “mammal like” and an “insect like” organization. It is concluded that functionally related characters are on the average more tightly correlated than by chance (= “mammal like” organization), while functionally unrelated characters appear to be less correlated than by random pleiotropy (“insect like” organization).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 16
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 18 (1983), S. 13-23 
    ISSN: 1432-1416
    Schlagwort(e): Ecosystem ; Evolution ; Autonomous oscillations ; issipative structure ; Bifurcation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The interrelation between autonomous oscillations in local systems and stable dissipative structures in spatially distributed systems is analyzed. Darwinian evolution in populations comprising the ecosystem is shown to be able to cause the qualitative rearrangements of dynamic modes and smooth appearance of oscillations in local systems. The same evolutionary mechanisms analyzed within bilocal systems, may lead to appearance of dissipative structures (both smooth and sharp).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 21 (1985), S. 299-306 
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; punctuated equilibria ; projection pursuit ; Brownian motion ; pattern recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The evolution of a species can be viewed as a trajectory in multidimensional space. What we perceive is only a low dimensional projection from the total dimensionality necessary to fully describe a species. Motivated by the phenomenon of punctuated equilibria, it is shown that there are projections of gradualistic evolution which will have a punctuated character. However, whether our eyes and minds would choose such a projection of the total phenotype is not resolved.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 25 (1987), S. 393-409 
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; Evolutionary stable states ; Games theory ; Linear programming ; Convex polyhedra ; Linear complementarity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract The problem of finding an Evolutionary Stable Strategy (ESS) for an animal species is defined. It is shown how such strategies are a subset of the equilibrium solutions for a particular non-zero sum game. These equilibrium solutions are then shown to arise from the vertices of a particular convex polyhedron. A method of finding these equilibrium solutions through the vertices and then the ESS solutions is given. This is illustrated by a number of numerical examples taken from the literature. Finally an alternative approach based on solving a Linear Complementarity Problem is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 26 (1988), S. 347-357 
    ISSN: 1432-1416
    Schlagwort(e): Transposable elements ; Evolution ; Branching processes ; Population genetics ; Mobile genetic elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract A discrete-time multitype branching process model is presented for the evolution of transposable elements in haploid populations. An individual is classified as type i if it possesses i copies of the TE, i⩾0. The general model incorporates copy-dependent selection and transposition, and recursion relations are derived for the distribution of the number of individuals of the various types. The asymptotic relative proportions of individuals of the different types is studied in the neutral case. The behavior of this equilibrium distribution is examined for various patterns of regulated transposition and deletion.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 20
    ISSN: 1432-1424
    Schlagwort(e): Drosophila ; per mutants ; pertransgenic ; Lucifer Yellow injections ; Gap junctions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract Larval salivary gland cells of Drosophila melanogaster were injected with a fluorescent dye to assess strengths of intercellular communication among such cells, as influenced by mutations at the period locus and by a per transgene. This clock gene had been reported to increase the extent of dye transfer when mutated such that it shortens the period of biological rhythms; the previous study also showed that a per-null mutant decreased the strength of transfer among salivary gland cells. Our re-examination of this feature of larval physiology—in observer-blind analyses, using the per s and per o mutants as well as two per-normal strains—revealed no appreciable differences in extents of dye transfer among these four genotypes. These results are discussed in the context of emerging findings which suggest that the period gene's product controls pacemaker functioning as an intracellularly acting entity.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 21
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 185 (1999), S. 199-205 
    ISSN: 1432-1351
    Schlagwort(e): Key words Hearing ; Orthoptera ; Phaneropteridae ; Cercal system ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The unusual morphology of a sound-activated plurisegmental ascending interneurone (AN5-AG7) in an insect (Ancistrura nigrovittata, Ensifera, Phaneropteridae) is described. This neurone's soma is located in the penultimate abdominal ganglion. The most prominent arborisations with smooth endings are found in the prothoracic ganglion. The neurone terminates with numerous beaded endings in the brain (protocerebrum). All abdominal ganglia including the penultimate contain only tiny side branches of beaded appearance. The neurone's morphology is compared to the morphology of a `typical' sound-activated plurisegmental neurone of bushcrickets with its soma in the prothorax. In the prothoracic ganglion and in the brain the arborisations of the two cells are very similar. Graded potentials and action potentials are generated in the prothoracic portion of both neurones. Both receive excitation mainly by ultrasound, and inhibition by soma-ipsilateral stimuli. Neither wind, substrate vibration nor touch of the abdomen evoke responses in AN5-AG7. It is assumed that early in evolution this neurone had its dendrites in the ganglion which houses the cell body (like cercal interneurones of this neuromere). Profound evolutionary changes probably have taken place to bring about this neuron's modern morphology.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 22
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 2 (1992), S. 1-16 
    ISSN: 1432-1386
    Schlagwort(e): Evolution ; Innovation ; Selection ; Technology ; JEL classification numbers: 036, 112
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract Virtually all models of economic change are based on a Darwinian picture of a world where change is gradual, smooth, and where economic survival depends on being more efficient. This paper, drawing from current controversies in evolutionary biology, presents a broader interpretation of evolutionary change in which competitive selection is only one possible reason for economic survival. Economic change is presented as a hierarchical process. At one level, change takes place through the accumulation of small changes based on competitive selection at the margin, as described by standard economic theory. At higher levels, survival depends on processes over which the agent being selected has no control.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 23
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 4 (1994), S. 243-260 
    ISSN: 1432-1386
    Schlagwort(e): Innovation ; Evolution ; Survival and growth ; O ; O3
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract A dynamic framework based on the process of firm selection and industry evolution is used to analyse the post-entry performance of new firms. In particular, it is hypothesized that, based on the stylized fact that virtually all new firms start at a very small scale of output, firm growth and survival are shaped by the need to attain an efficient level of output. The post-entry performance of more than 11,000 U.S. manufacturing firms established in 1976 is tracked throughout the subsequent tenyear period. Firm growth is found to be negatively influenced by firm size but positively related to the extent of scale economies, capital intensity, innovative activity, and market growth. By contrast, the likelihood of survival is identified as being positively influenced by firm size, market growth, and capital intensity, but negatively affected by the degree of scale economies in the industry. When viewed through the dynamic framework of firm selection and industry evolution, the empirical results shed considerable light on several paradoxes in the industrial organization literature, such as the continued persistence over time of an asymmetrical firm-size distribution consisting predominantely of suboptimal scale firms, and the failure of capital intensity and scale economies to substantially deter the entry and start-up of new firms.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 24
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 6 (1996), S. 239-260 
    ISSN: 1432-1386
    Schlagwort(e): Synergetics ; Self-organisation ; Time-irreversibility ; Evolution ; Structural change ; O30 ; O31 ; C60 ; C63
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract This paper deals with synergetic methods, which have developed as a sub-field of the self-organisation approach in the natural sciences. Such methods have been used successfully to model structural transitions in physio-chemical contexts. The synergetic approach is explained in a non-technical way and the main elements of the synergetic methodology are introduced. The extent to which such methods can be applied in the presence of historical time series data, which are subject to underlying processes of evolutionary economic change, is assessed. Proposals, concerning more appropriate synergetic methods for evolutionary economic application, are considered.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 25
    Digitale Medien
    Digitale Medien
    Springer
    Journal of evolutionary economics 8 (1998), S. 67-87 
    ISSN: 1432-1386
    Schlagwort(e): Key words: Bounded rationality ; Cognitive rationality ; Game equilibrium ; Evolution ; Learning ; JEL-classification: B 41; C 73; D 83; D 84
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Wirtschaftswissenschaften
    Notizen: Abstract. In game theory, four dynamic processes converging towards an equilibrium are distinguished and ordered by way of agents' decreasing cognitive capacities. In the eductive process, each player has enough information to simulate perfectly the others' behavior and gets immediately to the equilibrium. In epistemic learning, each player updates his beliefs about others' future strategies, with regard to their sequentially observed actions. In behavioral learning, each player modifies his own strategies according to the observed payoffs obtained from his past actions. In the evolutionary process, each agent has a fixed strategy and reproduces in proportion to the utilities obtained through stochastic interactions. All along the spectrum, longer term dynamics makes up for weaker rationality, and physical relations substitute for mental interactions. Convergence, if any, is towards an always stronger equilibrium notion and selection of an equilibrium state becomes more sensitive to context and history. The processes can be mixed if associated to different periods, agents or mechanisms and deepened if obtained by formal reasoning principles.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 26
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 14 (1982), S. 327-353 
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; Molecular evolution ; Dynamical system ; Neo-Darwinian evolution ; Non-Darwinian evolution ; Neutral theory
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract In order to understand generally how the biological evolution rate depends on relevant parameters such as mutation rate, intensity of selection pressure and its persistence time, the following mathematical model is proposed: dN n (t)/dt=(m n (t-μ)N n (t)+μN n-1(t) (n=0,1,2,3...), where N n (t) and m n (t) are respectively the number and Malthusian parameter of replicons with step number n in a population at time t and μ is the mutation rate, assumed to be a positive constant. The step number of each replicon is defined as either equal to or larger by one than that of its parent, the latter case occurring when and only when mutation has taken place. The average evolution rate defined by $$\upsilon _\infty \equiv {\text{ lim}}_{t \to \infty } \sum _{n = 0}^\infty nN_n (t)/t\sum _{n = 0}^\infty N_n (t)$$ is rigorously obtained for the case (i) m n (t)=m n is independent of t (constant fitness model), where m n is essentially periodic with respect to n, and for the case (ii) $$m_n (t) = {\text{ }}s( - 1)^{n + [1/\tau ]} $$ (periodic fitness model), together with the long time average m ∞ of the average Malthusian parameter $$\bar m \equiv \sum _{n = 0}^\infty m_n (t)N_n (t)/\sum _{n = 0}^\infty N_n (t)$$ . The biological meaning of the results is discussed, comparing them with the features of actual molecular evolution and with some results of computer simulation of the model for finite populations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 27
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 34 (1996), S. 556-578 
    ISSN: 1432-1416
    Schlagwort(e): Key words: Dynamical systems ; Evolution ; Game theory ; Asymptotic stability ; Population dynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract.  Evolution takes place in an ecological setting that typically involves interactions with other organisms. To describe such evolution, a structure is needed which incorporates the simultaneous evolution of interacting species. Here a formal framework for this purpose is suggested, extending from the microscopic interactions between individuals – the immediate cause of natural selection, through the mesoscopic population dynamics responsible for driving the replacement of one mutant phenotype by another, to the macroscopic process of phenotypic evolution arising from many such substitutions. The process of coevolution that results from this is illustrated in the context of predator–prey systems. With no more than qualitative information about the evolutionary dynamics, some basic properties of predator–prey coevolution become evident. More detailed understanding requires specification of an evolutionary dynamic; two models for this purpose are outlined, one from our own research on a stochastic process of mutation and selection and the other from quantitative genetics. Much of the interest in coevolution has been to characterize the properties of fixed points at which there is no further phenotypic evolution. Stability analysis of the fixed points of evolutionary dynamical systems is reviewed and leads to conclusions about the asymptotic states of evolution rather different from those of game-theoretic methods. These differences become especially important when evolution involves more than one species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 28
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 185 (1999), S. 419-425 
    ISSN: 1432-1351
    Schlagwort(e): Key wordsCydia pomonella ; Adoxophyes orana ; Sex pheromone ; Interspecific interruption ; Evolution ; AbbreviationsZ9-14:Ac (Z9)-tetradecenylacetate Z11-14:Ac (Z11)-tetradecenylacetate ; E8, E10-12:OH (E8, E10)-dodecadienol
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Male moths responding to their species-specific sex pheromone, may cease their upwind flight when pheromone components of sympatric species are added to the mixture. The interspecific interaction between the pheromone response of the tortricid moths Cydia pomonella and Adoxophyes orana was investigated in field-trapping and wind-tunnel studies. Addition of the A. orana pheromone [(Z9)-tetradecenylacetate and (Z11)-tetradecenylacetate] to a source containing the C. pomonella pheromone [(E8, E10)-dodecadienol] resulted in a significant inhibition of attraction by male C. pomonella. It is demonstrated that this behavioural antagonist for C. pomonella must be emitted from the same point source to induce this inhibitory effect. A spatial separation of the two interspecific pheromones (at 14 cm, 5 cm and 0.5 cm crosswind) restored the attraction of the conspecific pheromone for male C. pomonella. In contrast to C. pomonella, male A. orana were not inhibited by point sources releasing both the C. pomonella and A. orana pheromone. We suggest that the discrepancy in the interspecific pheromone interaction between these two tortricids can be explained if we consider the evolutionary ecology of interspecific pheromone communication in C. pomonella and A. orana.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 29
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 19 (1984), S. 329-334 
    ISSN: 1432-1416
    Schlagwort(e): Evolution ; ESS ; games ; game dynamics ; n-person games ; strategies
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract This note contains a generalization of the definition of an evolutionary stable strategy and of the corresponding game dynamics from 2-person to n-person games. This broader framework also allows modelling of several interacting populations or of populations containing different “types” of individuals, for example males and females.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 30
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 183 (1998), S. 635-650 
    ISSN: 1432-1351
    Schlagwort(e): Key words Olfactory receptors ; Multigene families ; Pseudogenes ; Vertebrate species ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In species representing different levels of vertebrate evolution, olfactory receptor genes have been identified by molecular cloning techniques. Comparing the deduced amino-acid sequences revealed that the olfactory receptor gene family of Rana esculenta resembles that of Xenopus laevis, indicating that amphibians in general may comprise two classes of olfactory receptors. Whereas teleost fish, including the goldfish Carassius auratus, possess only class I receptors, the `living fossil' Latimeria chalumnae is endowed with both receptor classes; interestingly, most of the class II genes turned out to be pseudogenes. Exploring receptor genes in aquatic mammals led to the discovery of a large array of only class II receptor genes in the dolphin Stenella Coeruleoalba; however, all of these genes were found to be non-functional pseudogenes. These results support the notion that class I receptors may be specialized for detecting water-soluble odorants and class II receptors for recognizing volatile odorants. Comparing the structural features of both receptor classes from various species revealed that they differ mainly in their extracellular loop 3, which may contribute to ligand specificity. Comparing the number and diversity of olfactory receptor genes in different species provides insight into the origin and the evolution of this unique gene family.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 31
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 185 (1999), S. 367-372 
    ISSN: 1432-1351
    Schlagwort(e): Key words Cortical magnification ; Somatosensory cortex ; Development ; Evolution ; Behavior
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract The star-nosed mole (Condylura cristata) has a snout surrounded by 22 fleshy and mobile appendages. This unusual structure is not an olfactory organ, as might be assumed from its location, nor is it used to manipulate objects as might be guessed from its appearance. Rather, the star is devoted to the sense of touch, and for this purpose the appendages are covered with thousands of small mechanoreceptive Eimer's organs. Recent behavioral studies find that the star acts much like a tactile eye, having a small behavioral focus, or “fovea” at the center – used for detailed explorations of objects of interest. The peripheral and central nervous systems of the mole reflect these behavioral specializations, such that the small behavioral focus on the nose is more densely innervated in the periphery, and has a greatly enlarged representation in the somatosensory cortex. This somatosensory representation of the tactile fovea is not correlated with anatomical parameters (innervation density) as found in other species, but rather is highly correlated with patterns of behavior. The many surprising parallels between the somatosensory system of the mole, and the visual systems of other mammals, suggest a convergent and perhaps common organization for highly developed sensory systems.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 32
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 181 (1997), S. 367-382 
    ISSN: 1432-1351
    Schlagwort(e): Key words Stomatogastric ganglion ; Penaeus ; Pyloric circuit ; Neurotransmitter ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Pyloric pattern-generating neurons that control the pyloric region of the foregut were identified in the stomatogastric ganglion of the most primitive decapod genus Penaeus. Five types of motor neurons and one interneuron are involved in generation of pyloric motor pattern. One cell type of motor neurons innervates muscles of both the gastric mill and the pylorus like the gastric motor neurons in Cancer, but unlike those in Panulirus. These identified neurons are connected to each other either by electrical or inhibitory chemical synapses to construct the neural circuit. This pyloric circuit is similar to the homologous circuit of other crustacean species though some differences are seen in synaptic connections, supporting the hypothesis that the basic design of the neural circuit has been conserved during evolution of the Malacostraca, and that differences have occurred in the synaptic connectivity as the foregut structure has become complex. The motor neurons use either acetylcholine or glutamate as a neurotransmitter like in reptantians. The foregut structure, the number of the pyloric cells, muscle innervation, neurotransmitters, and circuitry are compared among malacostracan crustaceans to provide insight into how the neural circuits change and evolve to produce the motor patterns mediating behaviour.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 33
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 181 (1997), S. 477-483 
    ISSN: 1432-1351
    Schlagwort(e): Key words Insects ; Bats ; Ears ; Evolution ; Neotropics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Assuming that bat-detection is the primary function of moth ears, the ears of moths that are no longer exposed to bats should be deaf to echolocation call frequencies. To test this, we compared the auditory threshold curves of 7 species of Venezuelan day-flying moths (Notodontidae: Dioptinae) to those of 12 sympatric species of nocturnal moths (Notodontidae: Dudusinae, Noctuidae and Arctiidae). Whereas 2 dioptines (Josia turgida, Zunacetha annulata) revealed normal ears, 2 (J. radians, J. gopala) had reduced hearing at bat-specific frequencies (20–80 kHz) and the remaining 3 (Thirmida discinota, Polypoetes circumfumata and Xenorma cytheris) revealed pronounced to complete levels of high-frequency deafness. Although the bat-deaf ears of dioptines could function in other purposes (e.g., social communication), the poor sensitivities of these species even at their best frequencies suggest that these moths represent a state of advanced auditory degeneration brought about by their diurnal life history. The phylogeny of the Notodontidae further suggests that this deafness is a derived (apomorphic) condition and not a retention of a primitive (pleisiomorphic), insensitive state.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 34
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 184 (1999), S. 543-551 
    ISSN: 1432-1351
    Schlagwort(e): Key words Auditory physiology ; Insect ; Frequency discrimination ; Evolution ; Song recognition
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Peripheral auditory frequency tuning in the ensiferan insect Cyphoderris monstrosa (Orthoptera: Haglidae) was examined by comparing tympanal vibrations and primary auditory receptor responses. In this species there is a mis-match between the frequency of maximal auditory sensitivity and the frequency content of the species' acoustic signals. The mis-match is not a function of the mechanical properties of the tympanum, but is evident at the level of primary receptors. There are two classes of primary receptors: low-tuned and broadly tuned. Differences in the absolute sensitivity of the two receptor types at the male song frequency would allow the auditory system to discriminate intraspecific signals from sounds containing lower frequencies. Comparisons of tympanal and receptor tuning indicated that the sensitivity of the broadly tuned receptors did not differ from that of the tympanum, while low-tuned receptors had significantly narrower frequency tuning. The results suggest that the limited specialization for the encoding of intraspecific signals in the auditory system of C. monstrosa is a primitive rather than a degenerate condition. The limited specialization of C. monstrosa may reflect the evolutionary origin of communication-related hearing from a generalized precursor through the addition of peripheral adaptations (tympana, additional receptors) to enhance frequency sensitivity and discrimination.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 35
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 180 (1997), S. 245-255 
    ISSN: 1432-1351
    Schlagwort(e): Key words Mole-rat  ;  Vocalization  ;  Acoustic communication  ;  Subterranean mammal  ; Hearing  ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract In captive adult Zambian mole-rats 14 different sounds (13 true vocalizations) have been recorded during different behavioural contexts. The sound analysis revealed that all sounds occurred in a low and middle frequency range with main energy below 10 kHz. The majority of calls contained components of 1.6–2 kHz, 0.63–0.8 kHz, and/or 5–6.3 kHz. The vocalization range thus matched well the hearing range as established in other studies. The frequency content of courtship calls in two species of Zambian Cryptomys was compared with that in naked mole-rats (Heterocephalus glaber) and blind mole-rats (Spalax ehrenbergi) as described in the literature. The frequency range of maximum sound energy is negatively correlated with the body weight and coincides with the frequencies of best hearing in the respective species. In general, the vocalization range in subterranean mammals is shifted towards low frequencies which are best propagated in underground burrows.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 36
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 186 (2000), S. 105-118 
    ISSN: 1432-1351
    Schlagwort(e): Key words Stomatogastric nervous system ; Penaeus ; Motor pattern ; Neural network ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract  Motor patterns of the cardiac sac, the gastric and the pyloric network in the stomatogastric nervous system of the shrimp Penaeus japonicus, the most primitive decapod species, were studied. Single neurons can switch from the gastric or the pyloric pattern to the cardiac sac pattern. Some of the pyloric neurons fire with the gastric pattern. All of the gastric neurons fire with the pyloric pattern, unlike those in reptantians. Proctolin activates and modulates the cardiac sac and the pyloric rhythm, and promotes reconfiguration of the networks. Neurons of the three networks have so many interconnections that they construct a multifunctional neural network like those in Cancer. This network may function in different configurations under the appropriate conditions. Several modes of interactions between the networks found in different reptantian species can apply to the penaeidean shrimp. Such interactions are general features of the stomatogastric nervous system in decapods. Phylogenetic differences among the decapod infraorders are seen in the number and orientation of muscles and the innervation pattern of muscles. The multifunctional networks have existed in the most primitive decapod species, and types of configurations of the networks would have evolved to produce a wide range of motor patterns as the foregut structure has become complex.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 37
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 11 (1981), S. 245-267 
    ISSN: 1432-1416
    Schlagwort(e): Population genetics ; Evolution ; Migration ; Geographical variation ; Habitat choice ; Polymorphism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract For a single autosomal locus with multiple alleles both an island and a multiple-niche model with discrete nonoverlapping generations are formulated for the maintenance of genetic variability. Both models incorporate viability selection in an arbitrary way and allow for genotypic differences in the pertinent migration structure. Random drift is ignored, and mating is at random. A global analysis is given for the island model in the neutral case. For a subdivided population, conditions are derived for the existence of a protected polymorphism, and the model is examined in some special two-niche cases. Of particular consideration is the loss of neutral alleles due solely to population regulation and genotype-dependent migration, and the possible existence of equilibrium clines without selection.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 38
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 28 (1990), S. 237-256 
    ISSN: 1432-1416
    Schlagwort(e): Behavior ; Evolution ; Neural network ; Dynamic optimization
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract One of the main challenges to the adaptionist program in general and the use of optimization models in behavioral and evolutionary ecology, in particular, is that organisms are so constrained' by ontogeny and phylogeny that they may not be able to attain optimal solutions, however those are defined. This paper responds to the challenge through the comparison of optimality and neural network models for the behavior of an individual polychaete worm. The evolutionary optimization model is used to compute behaviors (movement in and out of a tube) that maximize a measure of Darwinian fitness based on individual survival and reproduction. The neural network involves motor, sensory, energetic reserve and clock neuronal groups. Ontogeny of the neural network is the change of connections of a single individual in response to its experiences in the environment. Evolution of the neural network is the natural selection of initial values of connections between groups and learning rules for changing connections. Taken together, these can be viewed as “design parameters”. The best neural networks have fitnesses between 85% and 99% of the fitness of the evolutionary optimization model. More complicated models for polychaete worms are discussed. Formulation of a neural network model for host acceptance decisions by tephritid fruit flies leads to predictions about the neurobiology of the flies. The general conclusion is that neural networks appear to be sufficiently rich and plastic that even weak evolution of design parameters may be sufficient for organisms to achieve behaviors that give fitnesses close to the evolutionary optimal fitness, particularly if the behaviors are relatively simple.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 39
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 6 (1978), S. 169-175 
    ISSN: 1432-1416
    Schlagwort(e): Selection ; Evolution ; Biological macromolecules
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Summary Starting with Eigen's model we discuss some principles pertaining to the selection of biological macromolecules. The principles have a certain analogy to Fisher's fundamental theorem for natural selection.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 40
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 29 (1991), S. 743-761 
    ISSN: 1432-1416
    Schlagwort(e): Transposable element ; Branching-processes ; Population genetics ; Evolution ; Mobile genetic elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract We have formulated a very general mathematical model to analyze the evolution of transposable genetic elements in prokaryotic populations. Transposable genetic elements are DNA sequences able to replicate and insert copies of themselves at new locations in the genome. This work characterizes the equilibrium distribution of copy number under the influence of copy number-dependent selection, transposition and deletion. Our principal results concern the equilibrium distribution of copy number in response to various selective regimes. For particular transposition patterns (e.g. unregulated transposition or copy number-dependent transposition), equilibrium distributions are calculated numerically for a variety of specific selection patterns. Selection is quantified through specification of the expected number of offspring for individuals of each type, which is generally a non-increasing function of copy number, in accord with the usual evolutionary speculations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 41
    Digitale Medien
    Digitale Medien
    Springer
    Journal of mathematical biology 34 (1996), S. 556-578 
    ISSN: 1432-1416
    Schlagwort(e): Dynamical systems ; Evolution ; Game theory ; Asymptotic stability ; Population dynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Mathematik
    Notizen: Abstract Evolution takes place in an ecological setting that typically involves interactions with other organisms. To describe such evolution, a structure is needed which incorporates the simultaneous evolution of interacting species. Here a formal framework for this purpose is suggested, extending from the microscopic interactions between individuals — the immediate cause of natural selection, through the mesoscopic population dynamics responsible for driving the replacement of one mutant phenotype by another, to the macroscopic process of phenotypic evolution arising from many such substitutions. The process of coevolution that results from this is illustrated in the context of predator-prey systems. With no more than qualitative information about the evolutionary dynamics, some basic properties of predator-prey coevolution become evident. More detailed understanding requires specification of an evolutionary dynamics; two models for this purpose are outlined, one from our own research on a stochastic process of mutation and selection and the other from quantitative genetics. Much of the interest in coevolution has been to characterize the properties of fixed points at which there is no further phenotypic evolution. Stability analysis of the fixed points of evolutionary dynamical systems is reviewed and leads to conclusions about the asymptotic states of evolution rather different from those of game-theoretic methods. These differences become especially important when evolution involves more than one species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 42
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 182 (1997), S. 103-113 
    ISSN: 1432-1351
    Schlagwort(e): Key words Constraint ; Electroreception ; Evolution ; Sensory system ; Neural network
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Abstract Modification of an existing neural structure to support a second function will produce a trade-off between the two functions if they are in some way incompatible. The trade-off between two such sensory functions is modeled here in pyramidal neurons of the gymnotiform electric fish's medullar electrosensory lateral line lobe (ELL). These neurons detect two electric stimulus features produced when a nearby object interferes with the fish's autogenous electric field: (1) amplitude modulation across a cell's entire receptive field and (2) amplitude variation within a cell's receptive field produced by an object's edge. A model of sensory integration shows that detection of amplitude modulation and enhancement of spatial contrast involve an inherent mechanistic trade-off and that the severity of the trade-off depends on the particular algorithm of sensory integration. Electrophysiology data indicate that of the two algorithms for sensory integration modeled here for the gymnotiform fish Brachyhypopomus pinnicaudatus, the algorithm with the better trade-off function is used. Further, the intrinsic trade-off within single cells has been surmounted by the replication of ELL into multiple electrosensory map segments, each specialized to emphasize different sensory features.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 43
    Digitale Medien
    Digitale Medien
    Springer
    Journal of comparative physiology 166 (1989), S. 179-187 
    ISSN: 1432-1351
    Schlagwort(e): Blowfly ; Drosophila ; Photoreceptor ; Lanthanum ; trp mutant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin
    Notizen: Summary The effect of lanthanum on the light response of blowfly (Calliphora erythrocephala) photoreceptors was studied. The electrophysiological behaviour of the photoreceptors in the presence of La can be summarized as follows: 1. Upon long stimulation the photoreceptors responded with a ‘transient receptor potential’, i.e. the cells depolarized at the onset of the stimulus and then repolarized to (or below) the resting potential. This effect was dependent on stimulus intensity and occurred only at high intensities. During illumination membrane noise was reduced. 2. The light-induced changes in membrane potential were paralleled by changes in membrane resistance. 3. The time course of the receptor response was slowed down. 4. Light adaptation led to an increase in response latency. 5. The recovery of the receptor response after light adaptation was slowed down. 6. The sensitivity of the receptor cells measured by the response to short light stimuli was reduced. In summary, the electrophysiological behaviour of Calliphora photoreceptors in the presence of La was very similar to that of the photoreceptors of the trp (transient receptor potential) mutant of Drosophila melanogaster. This result suggests that La and trp mutation affect the same cellular processes in the photoreceptors.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 44
    ISSN: 1432-2048
    Schlagwort(e): Acetabularia ; Acicularia ; Chlorophyta ; Chloroplast genome ; Dasycladaceae ; Evolution ; Ribulose-1,5-bisphosphate carboxylase (conservatism)
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In contrast to other plants the plastid genome of Acetabularia is larger in size and shows a high degree of variability. This study on the chloroplast-encoded large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase demonstrates that strongly conserved areas also exist in the plastid genome of the Dasycladaceae. Searching for differences in the amino acid sequence of the large subunit from Acetabularia mediterranea and Acicularia schenckii, proteolytic peptides which differ in their elution behaviour in reverse-phase high-performance liquid chromatography were sequenced. Only six amino acids were found to be exchanged in the large subunit from these two species. Since these two species diverged approx. 150 million years ago, these results imply that 0.84 amino-acid exchanges per 100 amino acids have occurred in 108 years, underlining the strong conservatism of the large subunit.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 45
    Digitale Medien
    Digitale Medien
    Springer
    The visual computer 9 (1993), S. 466-476 
    ISSN: 1432-2315
    Schlagwort(e): Evolution ; Genetic algorithms ; Procedural models
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Informatik
    Notizen: Abstract This paper describes how the evolutionary mechanisms of variation and selection can be used to “evolve” complex equations used by procedural models for computer graphics and animation. An interactive process between the user and the computer allows the user to guide evolving equations by observing results and providing aesthetic information at each step of the process. The computer automatically generates random mutations of equations and combinations between equations to create new generations of results. This repeated interaction between user and computer allows the user to search hyperspaces of posible equations without being required to design the equations by hand or even understand them. Three examples of these techniques have been implemented and are described: procedurally generated pictures and textures, three-dimensional shapes represented by parametric equations, and two-dimensional dynamical systems described by sets of differential equations. It is proposed that these methods have potential as powerful tools for exploring procedural models and achieving flexible complexity with a minimum of user input and knowledge of details.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 46
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 50 (1977), S. 89-101 
    ISSN: 1432-2242
    Schlagwort(e): Incompatibility ; Evolution ; Flowering Plants ; Fungi ; Complementarity
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The restriction of sexual pairing by a specificity gene is considered to be an ancient development in the plant kingdom. The diversity and general parallelism of incompatibility systems seen amongst the phyla at the present time can be rationalized in terms of the association of various derived forms of the ancestral specificity unit with differing spectra of accessory factors controlling sexual physiology in the different phyla. Sexual morphogenesis has become divided into distinct phases under the control of complementary genes. These phases are initiated by a regulatory system of “Co-ordinator genes” which control the order in which groups of morphogenetic genes are expressed during development. The entire sexual cycle will be completed only if all the complementary groups are activated in the appropriate sequence. The present article discusses essential features of the evolution of the breeding locus in different phyla. These features are consistent in themselves with the present data and are not dependent on the proposed ancient origin of the specificity gene. The above hypothesis throws light on the (1) evolution of the complex mating loci in flowering plants and fungi; (2) evolution of complementary incompatibility and heteromorphic incompatibility in flowering plants; (3) anomalous cross-compatibility behaviour of mutants in the fungus Schizophyllum commune; (4) nature of homothallism in higher fungi; (5) mode of origin of new functional self-incompatibility alleles; and (6) “homogenic” and “heterogenic” incompatibility.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 47
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 50 (1977), S. 125-127 
    ISSN: 1432-2242
    Schlagwort(e): Drosophila ; Mutants ; Radiation ; Lethals ; Dose-Response
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The mutagenic efficiency of ionizing radiations has been tested on different lines of Drosophila melanogaster. It has been shown that differential lethal effects are obtained when irradiated females from different lines are mated to flies carrying heterozygous lethal genes. The results seem not to be attributable to differential expression of the lethality in the various crosses performed with the irradiated flies. This might suggest that gene activity is involved in the expression of the mutagenic effects of radiations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 48
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 80 (1990), S. 321-325 
    ISSN: 1432-2242
    Schlagwort(e): Heterosis ; Genetic distance ; Drosophila ; Inbreeding
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The aim of the experiment was to determine if the estimated genetic distance between two populations could be used to predict the amount of heterosis that would occur when they were crossed. Eight lines of known relatedness to each other were produced by eight generations of sib mating and sub-lining. This produced lines that varied in coefficient of coancestry from zero to 0.78. Fourteen reciprocal crosses of these lines were used to measure heterosis for larval viability and adult fecundity. Gene frequencies at six polymorphic enzyme loci were used to estimate the genetic distances between lines, which were then compared with the known degrees of coancestry. The estimated genetic differences were poorly correlated with the known coancestry coefficients (r=0.4), possibly due to the small number of loci typed. Also genetic distances were only about 1/3 of what was expected. Selection acting on blocks of genes linked to the enzyme loci probably prevented the expected increase in homozygosity. Coancestry coefficient was correlated with heterosis (r=0.44–0.71). This level of correlation implied differences in heterosis among parent lines with the same level of coancestry. This variability is expected if a small number of loci explain most of the heterosis. The average level of heterosis was less than expected after eight generations of sib mating. This is most likely due to selection opposing the increase in homozygosity caused by inbreeding. The combination of these two imperfect correlations resulted in no significant correlation between genetic distance estimated from markers and heterosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 49
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 123-127 
    ISSN: 1432-2242
    Schlagwort(e): Inbreeding depression ; Drosophila ; Natural selection
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary This experiment was designed to study the relationship between rate of inbreeding and observed inbreeding depression of larval viability, adult fecundity and cold shock mortality in Drosophila melanogaster. Rates of inbreeding used were full-sib mating and closed lines of N=4 and N=20. Eight generations of mating in the N=20 lines, three generations in the N=4 lines and one generation of full-sib mating were synchronised to simultaneously produce individuals with an expected level of inbreeding coefficient (F) of approximately 0.25. Inbreeding depression for the three traits was significant at F=0.25. N=20 lines showed significantly less inbreeding depression than full-sib mated lines for larval viability at approximately the same level of F. A similar trend was observed for fecundity. No effect of rate of inbreeding depression was found for cold shock mortality, but this trait was measured with less precision than the other two. Natural selection acting on loci influencing larval viability and fecundity during the process of inbreeding could explain these results. Selection is expected to be more effective with slow rates of inbreeding because there are more generations and greater opportunity for selection to act before F=0.25 is reached. Selection intensities seem to have been different in the three traits measured. Selection was most intense for larval viability, less intense for fecundity and, perhaps, negligible at loci influencing cold shock mortality.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 50
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 253-259 
    ISSN: 1432-2242
    Schlagwort(e): Heterosis ; Selection ; Drosophila ; Genotype x environment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Experiments were designed to examine whether heterosis would occur in crosses of Drosophila melanogaster populations adapted to 18 °C or 28 °C environments. Crosses were examined in parental environments, an intermediate environment (23 °C) and a mixed environment (alternating 18°/28°C). Parental populations did not show divergence for larval viability, cold shock or high temperature mortalities when tested in a common environment. However, the 28 °C population was less fecund than the 18 °C population, but had higher larval competitive ability and higher adult longevity. Heterosis for viability, cold shock mortality and high temperature mortality occurred in crosses between a population adapted to 18 °C and another adapted to 28 °C, but not in crosses between two populations adapted to the same temperature. The results suggest that, in the absence of drift, heterosis is expected in crosses between lines or populations with different histories of selection but not between lines with the same selection histories.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 51
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 77 (1989), S. 689-700 
    ISSN: 1432-2242
    Schlagwort(e): Triticum ; Homoeoalleles ; Evolution ; Dough ; Gene library
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Two high-molecular-weight subunit (HMWS) glutenin genes from the A and B genomes of the hexaploid bread wheat Triticum aestivum L. cv Cheyenne have been isolated and sequenced. Both of these genes are of the high Mr class (x-type) of HMW glutenins, and have not been previously reported. The entire set of six HMW genes from cultivar Cheyenne have now been isolated and characterized. An analysis of the Ax and Bx sequences shows that the Ax sequence is similar to the homoeologous gene from the D genome, while the Bx repeat structure is significantly different. The repetitive region of these proteins can be modelled as a series of interspersed copies of repeat modifs of 6, 9, and 15 amino acid residues. The evolution of these genes includes single-base substitutions over the entire coding region, plus insertion/deletions of single or blocks of repeats in the central repetitive domain.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 52
    ISSN: 1432-2242
    Schlagwort(e): Wheat aneuploids ; Null forms ; Storage proteins ; Gliadins ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Electrophoretical analyses of the gliadin fraction extracted from seeds of the intervarietal substitution lines of T. aestivum ssp. spelta in the T. aestivum ssp. vulgare cv ‘Chinese Spring’ for the homoeologous groups 1 and 6 and substitution lines of 6D chromosome of ‘Chinese Spring’ in the durum wheat cv ‘Langdon’ allowed the identification of seeds without gliadin proteins controlled by genes on chromosome 6A and 6B. A gliadin component of ‘Chinese Spring’, not previously assigned to any specific chromosome, is controlled by chromosome 6D in the 6D (6A) and 6D (6B) disomic substitution lines of ‘Langdon’. Additional genes controlling the synthesis of this component may be present on other chromosomes, very likely 6A and 6B, since the analysis of the ‘Chinese Spring’ compensating nullisomic-tetrasomics involving the 6D chromosome does not show the loss of this component or any apparent change in staining intensity. Chromosomal location data and two-dimensional gliadin maps reveal close homologies between the two hexaploid wheats, ‘Chinese Spring’ (T. aestivum ssp. vulgare) and T. aestivum ssp. spelta, belonging to different subspecies in the hexaploid group of genomic formula AABBDD. The comparison of gliadin electrophoretic patterns aiding in the identification of evolutionary pathways in wheat is stressed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 53
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 80 (1990), S. 569-575 
    ISSN: 1432-2242
    Schlagwort(e): Heterosis ; Genetic distance ; Drosophila
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary An experiment was performed to test the hypothesis that the genetic distance between populations estimated from enzyme loci could be used to predict the amount of heterosis that would occur in crosses between these populations. A partial diallel cross using 11 populations of Drosophila melanogaster from the AustralianPacific region and from England was carried out. Heterosis for larval viability, fecundity, cold shock mortality, and an index of these three traits was recorded. When two populations originating from the same location were crossed, no heterosis occurred, but otherwise heterosis was significant for all traits. For larval viability, a similar low level of heterosis occurred in all crosses. For cold shock mortality, the level of heterosis varied widely and fecundity showed a pattern intermediate between these two. The geographic distance between the sites from which populations originated was not correlated with the amount of heterosis in their crosses. There was a tendency for populations from ecologically different environments to show heterosis in crosses. Genetic distance based on ten enzyme loci was correlated with heterosis for cold shock mortality and the combined trait index. These results can be explained by the hypothesis that genes affecting larval viability are subject to strong, uniform selection in all populations, which limits the extent to which gene frequencies can drift apart. However, genes affecting cold shock mortality and the enzyme loci are subject to different selection pressures in different environments. This divergent selection combined with genetic drift causes divergence in gene frequency and heterosis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 54
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 80 (1990), S. 635-640 
    ISSN: 1432-2242
    Schlagwort(e): Pinus ; Species hybridization ; Allozymes ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Allozyme differentiation at 13 loci was studied in populations of Pinus tabulaeformis, P. densata, and P. yunnanensis from China. It was previously suggested that P. densata represents a Tertiary hybrid between P. tabulaeformis and P. yunnanensis. The observed levels of allozyme variation within and among the investigated species were comparable to those of other conifers. P. tabulaeformis differed markedly from P. yunnanensis with respect to allozyme frequencies, while P. densata was intermediate between the two putative parents. There was evidence of homozygote excess in embryos from all investigated species, as compared to Hardy-Weinberg expectations. The observed allozyme composition of P. densata conformed to earlier morphological and molecular evidence indicating hybrid origin of this taxon. It was proposed that fusion of gene pools from P. tabulaeformis and P. yunnanensis has led to adaptive evolution of a new species, P. densata.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 55
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 81 (1991), S. 13-20 
    ISSN: 1432-2242
    Schlagwort(e): Potato ; Chloroplast DNA ; Sequence comparison ; Nucleotide substitution rate ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A deletion specific to chloroplast (ct) DNA of potato (Solanum tuberosum ssp. tuberosum) was determined by comparative sequence analysis. The deletion was 241 bp in size, and was not flanked by direct repeats. Five small, open reading frames were found in the corresponding regions of ctDNAs from wild potato (S. tuberosum ssp. andigena) and tomato (Lycopersicon esculentum). Comparison of the sequences of 1.35-kbp HaeIII ctDNA fragments from potato, tomato, and tobacco (Nicotiana tabacum) revealed the following: the locations of the 5′ ends of both rubisco large subunit (rbcL) and ATPase beta subunit (atpβ) mRNAs were probably the same as those of spinach (Spinacia oleracea); the promoter regions of the two genes were highly conserved among the four species; and the 5′ untranslated regions diverged at high rates. A phylogenetic tree for the three potato cultivars, one tomato cultivar, and one tobacco cultivar has been constructed by the maximum parsimony method from DNA sequence data, demonstrating that the rate of nucleotide substitution in potato ctDNA is much slower than that in tomato ctDNA. This fact might be due to the differences in the method of propagation between the two crops.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 56
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 82 (1991), S. 57-64 
    ISSN: 1432-2242
    Schlagwort(e): Cultivated rice ; Wild rice ; RFLP ; Satellite DNA ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A 352-bp EcoRI fragment from rice DNA was cloned and shown to be a member of a tandem repeat. Sequence determination revealed homologies with human alpha satellite DNA and maize knob heterochromatin specific repeat. This 352-bp sequence is highly specific for the AA genome of rice. However, copy number and sequence organization are variable, depending on the accession analyzed. Several examples of amplification were observed in O. rufipogon and O. longistaminata. Use of resolutive polyacrylamide gel electrophoresis and 4-bp cutter enzymes allowed one to distinguish between the Indica and Japonica subtypes of O. sativa. The same method also discriminates between two groups of O. rufipogon, the presumed ancestor of O. sativa, suggesting that the present day Indica and Japonica subtypes originated independently from two O. rufipogon distinct populations.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 57
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 83 (1992), S. 821-826 
    ISSN: 1432-2242
    Schlagwort(e): Drosophila ; Balancers ; Inversions ; Translocations ; Meiosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We used a screen for maternally generated late embryonic lethals as a new method for the isolation of inversions that are suitable for the balancing of mutations in Drosophila hydei. The recovery of several inversions by this method demonstrates that female meiosis in D. hydei apparently differs from meiosis in female D. melanogaster, since in D. hydei the defective chromosomes which are generated by a single crossing-over within a paracentric inversion can be recovered via the egg nucleus. In addition, the classic method of crossingover suppression was used in order to isolate more inversions and to improve the balancing capacities of inversions. We succeeded in constructing chromosomes that allow the balancing of mutations on nearly the whole genome of D. hydei. We discuss here whether or not this method is suited for application to other organisms.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 58
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 86 (1993), S. 159-165 
    ISSN: 1432-2242
    Schlagwort(e): Allozymes ; Chloroplast DNA ; Introgression ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Allozyme variation was examined in 22 populations of Pinus densiflora (Sieb, et Zucc.) and four geographic varieties of P. sylvestris (L.): var ‘lapponica’ (Fries, Hartman), var ‘armena’ (Komarov), var ‘mongolica’ (Litvinov) and var ‘sylvestriformis’ (Takenouchi). In addition, we developed paternal chloroplast (cp) DNA markers that distinguish P. densiflora from var ‘lapponica’, var ‘armena’ and var ‘mongolica’. UPGMA cluster analysis based on Nei's distances between all pairwise combinations of the 22 populations revealed patterns corresponding strictly to geographic origin and taxonomic status. Analysis of allozyme variation in var ‘lapponica’, var ‘armena’ and var ‘mongolica’ demonstrated a high level of intrapopulational variability but a low level of interpopulational differentiation. It appears that the late Pleistocene blending of genetically diverse populations was responsible for the observed variation patterns. The constructed phylogenetic trees also showed late divergence of these three varieties. The var ‘sylvestri formis’ was genetically distinct from the other three P. sylvestris varieties. The genetic distances separating var ‘sylvestriformis’ from P. densiflora and the other taxa lend support to a separate taxonomic status for var ‘sylvestriformis’ and a close relation with P. densiflora. We found that var ‘sylvestriformis’ harbors admixtures of allozymes and cpDNA from both P. sylvestris and P. densiflora, which suggests an introgressive nature of this variety. Levels of intrapopulational variability were similar in P. sylvestris and P. densiflora, but interpopulational differentiation was much higher in P. densiflora. In the constructed phylogenetic trees, populations of this species were characterized by relatively long internode distances and branch lengths. The present results suggest that P. densiflora has a more advanced evolutionary age than P. sylvestris.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 59
    ISSN: 1432-2242
    Schlagwort(e): Sugar beet ; Beta species ; DNA “finger-printing” ; Cluster analysis ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Forty-one accessions of the genusBeta representing wild and cultivated species of all sections were analyzed by DNA “fingerprinting”. Four sugar beet minisatellite DNA probes revealed characteristic banding patterns with Southern-hybridizedBeta DNA restricted withHindIII. A total of 111 polymorphic RFLP bands were scored across all accessions. Cluster analysis based on genetic similarity estimates for all 820 combinations of accessions revealed the following results. (1) All accessions could unambiguously be identified by a characteristic RFLP banding pattern. (2) The sugar beet cultivars examined displayed a low level of genetic diversity; they showed high similarity toB. Vulgaris ssp.maritima but low genetic similarity to the other wild species of section I. (3) In most cases, the present taxonomic classification of the genusBeta was confirmed. Species of sections II, III, and IV were clearly distinguishable from those of section I except forB. Macrocarpa, which showed high similarity to wild species of section II. In a second experiment, 108 single-copy RFLP probes from sugar beet were Southern hybridized withB. procumbens DNA. A surprisingly low degree of homology (34%) was found. The results are discussed with regard to the taxonomic classification of the genusBeta.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 60
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 89 (1994), S. 959-963 
    ISSN: 1432-2242
    Schlagwort(e): Sugarcane ; Polyploidy ; Genetics ; Evolution ; Breeding ; DNA markers ; Arbitrarily primed PCR ; RAPD markers
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Recent work has revealed random chromosome pairing and assortment in Saccharum spontaneum L., the most widely distributed, and morphologically and cytologically variable of the species of Saccharum. This conclusion was based on the analysis of a segregating population from across between S. spontaneum ‘SES 208’ and a spontaneously-doubled haploid of itself, derived from anther culture. To determine whether polysomic inheritance is common in Saccharum and whether it is observed in a typical biparental cross, we studied chromosome pairing and assortment in 44 progeny of a cross between euploid, meiotically regular, 2n=80 forms of Saccharum officinarum ‘LA Purple’ and Saccharum robustum ‘ Mol 5829’. Papuan 2n=80 forms of S. robustum have been suggested as the immediate progenitor species for cultivated sugarcane (S. officinarum). A total of 738 loci in LA Purple and 720 loci in Mol 5829 were amplified and typed in the progeny by arbitrarily primed PCR using 45 primers. Fifty and 33 single-dose polymorphisms were identified in the S. officinarum and S. robustum genomes, respectively (χ 2 at 98%). Linkage analysis of single-dose polymorphisms in both genomes revealed linkages in repulsion and coupling phases. In the S. officinarum genome, a map hypothesis gave 7 linkage groups with 17 linked and 33 unlinked markers. Four of 13 pairwise linkages were in repulsion phase and 9 were in coupling phase. In the S. robustum genome, a map hypothesis gave 5 linkage groups, defined by 12 markers, with 21 markers unlinked, and 2 of 9 pairwise linkages were in repulsion phase. Therefore, complete polysomic inheritance was not observed in either species, suggesting that chromosomal behavior is different from that observed by linkage analysis of over 500 markers in the S. spontaneum map. Implications of this finding for evolution and breeding are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 61
    ISSN: 1432-2242
    Schlagwort(e): Endosperm development ; Evolution ; Imprinting ; Incompatibility ; Reciprocal crosses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The Endosperm Balance Number (EBN) and the polar-nuclei activation (PNA) hypotheses have been developed to interpret, explain and predict interspecific and interploidy crossabilities in the Solanums and the Gramineae, respectively. Although these two hypotheses evolved independently, they share a number of common features. Assignment of EBNs and ‘activation/response values’ (AVs/RVs) depend on plumpness, size, and germinability of hybrid seeds. Also, both hypotheses emphasize the importance of a balanced parental genic contribution for the normal development of endosperm. However, in the EBN hypothesis a 2 maternal∶1 paternal EBN ratio is a prerequisite for successful interspecific crossability, while the PNA hypothesis is based on the stimulative strength of the male nuclei to initiate mitotic divisions in the primary endosperm nucleus and is idependent on a 2∶1 ratio between the RV of the polar nuclei and the AV of the male gamete. Differences and similarities betweeen the EBN and PNA hypotheses are summarized and contrasted. It is proposed that EBN and PNA be considered as the same concept.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 62
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 89 (1994), S. 969-974 
    ISSN: 1432-2242
    Schlagwort(e): Evolution ; rDNA ; Internal transcribed spacers ; Picea
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The structure and variation of nuclear ribosomal DNA (rDNA) units of Picea abies, (L.) Karst. was studied by restriction mapping and Southern hybridization. Conspicuous length variation was found in the internal transcribed spacer (ITS) region of P. abies, although the length of this region is highly conserved both within and among most of the plant species. Two types of ITS variants (A and B), displaying a size difference of 0.5 kb in the ITS2 region, were present within individuals of P. abies from Sweden, Central Europe and Siberia. A preliminary survey of 14 additional Eurasian and North American species of Picea suggested that length variation in the ITS region is widespread in this genus. Alltogether three length variants (A, B and C) were identified. Within individuals of eight Picea species, two length variants were present within the genome (combinations of A and B variants in P. glehnii, P. maximowiczii, P. omorika, P. polita and P. sitchensis and variants B and C in P. jezoensis, P. likiangensis and P. spinulosa). Within individuals from five species, however only one rDNA variant was present in their genome (variant A in P. aurantiaca, P. engelmannii, P. glauca, P. koraiensis and P. koyamai; variant B in P. bicolor). The ITS length variation will be useful as a molecular marker in evolutionary studies of the Picea species complex, whose phylogeny is controversial. The presence of intraindividual variation in, and shared polymorphism of the, ITS length variants raises questions about the occurrence of interspecific hybridization during the evolutionary history of Picea.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 63
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 92 (1996), S. 1108-1111 
    ISSN: 1432-2242
    Schlagwort(e): Evolution ; Tobacco ; Telomeres ; Ribosomal genes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to investigate possible interactions between parental genomes in the composite genome of Nicotiana tabacum we have analyzed the organization of telomeric (TTTAGGG)n and ribosomal gene (rDNA) repeats in the progenitor genomes Nicotiana sylvestris and Nicotiana tomentosiformis or Nicotiana otophora. Telomeric arrays in the Nicotiana species tested are heterogeneous in length ranging from 20 to 200 kb in N. sylvestris, from 20 to 50 kb in N. tomentosiformis, from 15 to 100kb in N. otophora, and from 40 to 160kb in N. tabacum. The patterns of rDNA repeats (18S, 5.8S, 25S RNA) appeared to be highly homogeneous and speciesspecific; no parental rDNA units corresponding to N. sylvestris, N. tomentosiformis or N. otophora were found in the genome of N. tabacum by Southern hybridization. The results provide evidence for a species-specific evolution of telomeric and ribosomal repeats in the tobacco composite genome.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 64
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 92 (1996), S. 1003-1008 
    ISSN: 1432-2242
    Schlagwort(e): Fraxinus ; Evolution ; rDNA ; IGS structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The 6.8-kb rDNA intergenic spacer region of F. excelsior was isolated from a CsCl/actinomycin-D gradient and cloned into pUC18 for further characterization. We observed the presence of subrepeats delimited by HaeIII enzyme sites. These subrepeats were sub-cloned and 11 clones were sequenced. These corresponded to subrepeated elements of either 32 bp or 41 bp that shared a 23-bp common sequence in the 5′ end. Within each family of subrepeats, the percentage of common nucleotides was 84.4% for the 5 32-bp subrepeats and 67.4% for the 640-bp subrepeats. Non-repeated HaeIII fragments of 450 bp and 650 bp were also sub-cloned. To compare homology at the IGS region between the rDNA spacers of F. excelsior and the three related species (F. oxyphylla, F. americana, F. ornus), we conducted Southern hybridization analyses using each member of the 32-bp and 40-bp subrepeat families and the unique 450-bp and 650-bp fragments as probes. These analyses indicated that (1) the American ash is more genetically distant from the other three species that the latter are from each other and (2) F. oxyphylla and F. excelsior are more closely related to each other than to F. ornus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 65
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 98 (1999), S. 744-750 
    ISSN: 1432-2242
    Schlagwort(e): Key words Chromosome pairing ; Translocations ; T. timopheevii ; T. turgidum ; T. aestivum ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract.  Chromosome pairing at metaphase-I was analyzed in F1 hybrids among T. turgidum (AABB), T. aestivum (AABBDD), and T. timopheevii (AtAtGG) to study the chromosome structure of T. timopheevii relative to durum (T. turgidum) and bread (T. aestivum) wheats. Individual chromosomes and their arms were identified by means of C-banding. Homologous pairing between the A-genome chromosomes was similar in the three hybrid types AAtBG, AAtBGD, and AABBD. However, associations of B-G were less frequent than B-B. Homoeologous associations were also observed, especially in the AAtBGD hybrids. T. timopheevii chromosomes 1At, 2At, 5At, 7At, 2G, 3G, 5G, and 6G do not differ structurally from their counterpart in the A and B genomes. Thus, these three polyploid species inherited translocation 5AL/4AL from the diploid A-genome donor. Chromosome rearrangements that occurred at the tetraploid level were different in T. turgidum and T. timopheevii. Translocation 4AL/7BS and a pericentric inversion of chromosome 4A originated only in the T. turgidum lineage. The two lines of T. timophevii studied carry four different translocations, 6AtS/1GS, 1GS/4GS, 4GS/4AtL, and 4AtL/3AtL, which most likely arose in that sequence. These structural differences support a diphyletic origin of polyploid wheats.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 66
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 99 (1999), S. 203-209 
    ISSN: 1432-2242
    Schlagwort(e): Key words Homeobox gene ; KNOTTED1 ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Homeobox genes encode a family of DNA-binding regulatory proteins which are crucial for development. The first plant homeobox gene identified was knotted1 which plays a major role in leaf development. The knotted1 gene has a homeobox which encodes a homeodomain (HD) and HD proteins have been shown to function as transcription factors. A phylogenetic classification of the KNOTTED1 HD is presented. Here, we report six kn1 HDs from the cereals oat, barley, wheat, rye and rice. The KN1 class-I and -II genes can be divided into two distinct clades. Further, we hypothesize that KN1 and BELL1/MEIS HDs, (the closest non-KN1 class HDs) evolved from a common ancestor after divergence from the common precursor of all the homeobox genes. Our analysis clearly shows the presence of an ancestral KN1 HD from which all the known plant kn1 class of genes evolved.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 67
    ISSN: 1432-1939
    Schlagwort(e): Nested subsets ; Drosophila ; Community structure ; Species-area relationships
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Nested subset structure has been studied in archipelagoes and fragmented habitats, and has been attributed to differential colonization and extinction rates among species and nested environmental tolerances. In this experiment, we tested for nestedness in assemblages of mycophagous fly larvae. Twenty mushrooms in each of three size classes (4.8–6.0 g, 10–15 g, 21–32 g) were placed on moist potting soil in experimental cups. The cups were placed in oak and pine forests in Greenville, S.C., USA for 5 days, where they were available to ovipositing flies. Upon collection, the mushrooms were incubated in the laboratory for 3 weeks and all emerging flies were sorted by species, counted, and weighed. A random placement analysis was conducted to determine whether the species richness pattern was a sampling artifact of the species abundance distributions. The actual species richness pattern did not conform to the random placement model; most mushrooms contained significantly fewer species than predicted by random sampling. The communities were strongly nested as measured by two different indices, and the nestedness pattern was related to mushroom size. Small mushrooms usually produced no flies or a single species, Dohrniphora sp. (Phoridae). Medium and large mushrooms typically produced more species-rich communities that usually contained the phorid and Drosophila putrida, D. tripunctata, and Leucophenga varia. This core guild was nested within a more diverse assemblage that included D. falleni, Mycodrosophila dimidiata, a muscid, and two Leptocera sp. (sphaeroceridae). These patterns are tentatively explained in the context of nested desiccation tolerances, mediated by differences in mushroom size.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 68
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 108 (1996), S. 262-272 
    ISSN: 1432-1939
    Schlagwort(e): Drosophila ; Temperature performance ; Life history ; Thermal environment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The variability of morphological and lifehistory traits in Drosophila melanogaster and D. subobscura, two sympatric Drosophila species of different climatic origin, were investigated with regard to seasonal and daily temperature and humidity fluctuations to assess thermal sensitivity and the responses of freeliving organisms to oscillating temperatures. Temperature and humidity were measured continuously at the site where Drosophila were observed throughout the day, and thus represent a realistic picture of the temperature environment of these animals. A phenotypic model (gaussian curve) of temperature performance was fitted to daily fecundities and provided estimates of the position of temperature optimum and of the maximum and the breadth of performance for both species. D. melanogaster had a higher optimum temperature than D. subobscura. A trade-off between the maximum and the breadth of performance was detected both within and between the species.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 69
    Digitale Medien
    Digitale Medien
    Springer
    Oecologia 108 (1996), S. 552-561 
    ISSN: 1432-1939
    Schlagwort(e): Drosophila ; Colonization ; Ecology ; Succession ; Guild
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The guild of “cosmopolitan” Drosophila coexist almost worldwide and yet the mechanisms that underlie this coexistence are unknown. The larval resource of the guild is decaying fruit and vegetables, but the species show little specialization and can coexist on a single resource, such as oranges. In southern California the guild includes D. simulans (SIM), D. melanogaster (MEL), D. pseudoobscura (OBS), D. immigrans (IMM), D. hydei (HYD) and D. busckii (BUS). These species show consistent differences in their colonization of decaying organges, differences that may promote their coexistence. This study tested whether the colonization pattern of a species is determined primarily by attraction to specific resource types (decayed or fresh organges), by ability to colonize new resource patches, or by dependence on a successional sequence of Drosophila species. The experiments compared oranges that were pre-aged prior to a colonization period and showed that the colonization pattern of each species (except OBS) was driven primarily by its decay-dependent attraction to oranges. While OBS exhibited a pattern of colonization independent of pre-aging, the remaining species all showed some preference for older (7-day pre-aged) over fresh oranges. Their overall pattern of attraction, ordered by high relative abundance on fresher organges, was SIM〉MEL=IMM〉HYD=BUS. BUS, a specialist on decaying plant material, was the only species that showed a preference for 11-day over 7-day oranges. Pre-aging the oranges under covers, to prevent prior colonization by Drosophila, did not change the interspecific pattern of colonization, indicating that microbial decay was driving the changes in attraction. The patterns of attraction separated two ecologically similar pairs (SIM from MEL; IMM from HYD) and published data on ethanol tolerance show that, in each pair, the earliest colonizer has the lower tolerance. This suggests an important interplay between colonization patterns and physiological optima.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 70
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 30 (1990), S. 333-346 
    ISSN: 1432-1432
    Schlagwort(e): Protamine ; Evolution ; Nuclear protein ; DNA condensation ; Sperm proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The availability of the amino acid sequence for nine different mammalian P1 family protamines and the revised amino acid sequence of the chicken protamine galline (Oliva and Dixon 1989) reveals a much close relationship between mammalian and avian protamines than was previously thought (Nakano et al. 1976). Dot matrix analysis of all protamine genes for which genomic DNA or cDNA sequence is available reveals both marked sequence similarities in the mammalian protamine gene family and internal repeated sequences in the chicken protamine gene. The detailed alignments of the cis-acting regulatory DNA sequences shows several consensus sequence patterns, particularly the conservation of a cAMP response element (CRE) in all the protamine genes and of the regions flanking the TATA box, CAP site, N-terminal coding region, and polyadenylation signal. In addition we have found a high frequency of the CA dinucleotide immediately adjacent to the CRE element of both the protamine genes and the testis transition proteins, a feature not present in other genes, which suggests the existence of an extended CRE motif involved in the coordinate expression of protamine and transition protein genes during spermatogenesis. Overall these findings suggest the existence of an avian-mammalian P1 protamine gene line and are discussed in the context of different hypotheses for protamine gene evolution and regulation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 71
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 30 (1990), S. 409-424 
    ISSN: 1432-1432
    Schlagwort(e): Phylogeny ; Tetrapods ; Morphology ; Cladistics ; Divergence ; Evolution ; Amphibians ; Reptiles ; Birds ; Mammals
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The phylogeny of the major groups of tetrapods (amphibians, reptiles, birds, and mammals) has until recently been poorly understood. Cladistic analyses of morphological data are producing new hypotheses concerning the relationships of the major groups, with a focus on the identification of monophyletic groups. Molecular phylogenies support some of these views and dispute others. Geological dates of the major evolutionary branching points are recalculated on the basis of the cladograms and new fossil finds.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 72
    ISSN: 1432-1432
    Schlagwort(e): Histone H2A ; Histone variant ; Intron position ; Drosophila ; Tetrahymena
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Genomic clones ofDrosophila andTetrahymena histone H2A variants were isolated using the corresponding cDNA clones, (van Daal et al. 1988; White et al. 1988). The site corresponding to the initiation of transcription was defined by primer extension for bothDrosophila andTetrahymena genomic sequences. The sequences of the genomic clones revealed the presence of introns in each of the genes. TheDrosophila gene has three introns: one immediately following the initiation codon, one between amino acids 26 and 27 (gln and phe), and one between amino acids 64 and 65 (glu and val). TheTetrahymena gene has two introns, the positions of which are identical to the first two introns of theDrosophila gene. The chicken H2A.F variant gene has been recently sequenced and it contains four introns (Dalton et al. 1989). The first three of these are in the same positions as the introns in theDrosophila gene. The fourth intron interrupts amino acid 108 (gly). In all cases the sizes and the sequences of the introns are divergent. However, the fact that they are in conserved positions suggests that at least two of the introns were present in the ancestral gene. A phylogenetic tree constructed from the sequences of the variant and major cell cycle-regulated histone H2A proteins from several species indicates that the H2A variant proteins are evolutionarily separate and distinct from the major cell cycle-regulated histone H2A proteins. The ancestral H2A gene must have duplicated and diverged before fungi and ciliates diverged from the rest of the eukaryote lineage. In addition, it appears that the variant histone H2A proteins analyzed here are more conserved than the major histone H2A proteins.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 73
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 30 (1990), S. 489-492 
    ISSN: 1432-1432
    Schlagwort(e): Actinomyces ; Phosphotransferase ; Aminoglycoside ; Phylogenetic tree ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The protein sequences of seven 3′-aminoglycoside phosphotransferases falling into the six identified types and three 6′-aminoglycoside phosphotransferases were analyzed to give a rooted phylogenetic tree. This tree supports the origin of these groups of enzymes in an ancestor closely related to the actinomycetes, and that horizontal transfer of the resistance genes occurred, possibly via transposons. The implications for genetic engineering of a novel antibiotic are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 74
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 1 (1972), S. 270-272 
    ISSN: 1432-1432
    Schlagwort(e): DNA Sequences ; Evolution ; Repetition ; Phylogenesis ; Ageing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 75
    ISSN: 1432-1432
    Schlagwort(e): Nucleotide sequence ; Evolution ; Methanogens ; Extreme halophiles ; Eubacteria ; Eukaryotes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The sequence of the small-subunit rRNA from the thermoacidophilic archaebacteriumSulfolobus solfataricus has been determined and compared with its counterparts from halophilic and methanogenic archaebacteria, eukaryotes, and eubacteria. TheS. solfataricus sequence is specifically related to those of the other archaebacteria, to the exclusion of the eukaryotic and eubacterial sequences, when examined either by evolutionary distance matrix analyses or by the criterion of minimum change (maximum parsimony). The archaebacterial 16S rRNA sequences all conform to a common secondary structure, with theS. solfataricus structure containing a higher proportion of canonical base pairs and fewer helical irregularities than the rRNAs from the mesophilic archaebacteria.S. solfataricus is unusual in that its 16S rRNA-23S rRNA intergenic spacer lacks a tRNA gene.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 76
    ISSN: 1432-1432
    Schlagwort(e): Actin-coding regions ; Sequence divergence ; Conversion ; Codon usage ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have determined the sequences of three recombinant cDNAs complementary to different mouse actin mRNAs that contain more than 90% of the coding sequences and complete or partial 3′ untranslated regions (3′UTRs): pAM 91, complementary to the actin mRNA expressed in adult skeletal muscle (αsk actin); pAF 81, complementary to an actin mRNA that is accumulated in fetal skeletal muscle and is the major transcript in adult cardiac muscle (αc actin); and pAL 41, identified as complementary to a β nonmuscle actin mRNA on the basis of its 3′UTR sequence. As in other species, the protein sequences of these isoforms are highly (〉93%) conserved, but the three mRNAs show significant divergence (13.8–16.5%) at silent nucleotide positions in their coding regions. A nucleotide region located toward the 5′ end shows significantly less divergence (5.6–8.7%) among the three mouse actin mRNAs; a second region, near the 3′ end, also shows less divergence (6.9%), in this case between the mouse β and αsk actin mRNAs. We propose that recombinational events between actin sequences may have homogenized these regions. Such events distort the calculated evolutionary distances between sequences within a species. Codon usage in the three actin mRNAs is clearly different, and indicates that there is no strict relation between the tissue type, and hence the tRNA precursor pool, and codon usage in these and other muscle mRNAs examined. Analysis of codon usage in these coding sequences in different vertebrate species indicates two tendencies: increases in bias toward the use of G and C in the third codon position in paralogous comparisons (in the order αc), and in orthologous comparisons (in the order chicken 〈 rodent 〈 man). Comparison of actin-coding sequences between species was carried out using the Perler method of analysis. As one moves backward in time, changes at silent sites first accumulate rapidly, then begin to saturate after −(30–40) million years (MY), and actually decrease between −400 and −500 MY. Replacements or silent substitutions therefore cannot be used as evolutionary clocks for these sequences over long periods. Other phenomena, such as gene conversion or isochore compartmentalization, probably distort the estimated divergence time.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 77
    ISSN: 1432-1432
    Schlagwort(e): Retroposon ; Salmonid ; +RNA ; Evolution ; Average sequence divergence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary An in vitro runoff transcription assay of total genomic DNA was developed. As an example of use of this assay, analysis of a highly repetitive sequence in the cherry salmon (Oncorhynchus masou) is described. Total genomic DNA of the cherry salmon was completely digested with Hpa 1, whose site is known to be in the tRNA-unrelated region of the cherry salmon Hpa 1 family. On transcription of the digested DNA in a HeLa cell extract, a discrete-sized RNA of about 100 nucleotides, constituting 70% of the transcripts, was produced, whereas on transcription of the undigested total DNA, only smeared RNA was obtained. In a fingerprint, the oligonucleotides of the discrete transcript from the digested total DNA were very distinct and exactly corresponded to those of a transcript from an Hpa 1 digest of a cloned DNA, but with few extra oligonucleotides. These results showed that the cherry salmon Hpa 1 family constitutes a major repetitive family in the genome of the cherry salmon. For determination of the distribution of the salmonid Hpa 1 family in other salmonid species, the same analysis was applied to DNAs from the chum salmon (Oncorhynchus keta), brown trout (Salmo trutta), Japanese common charr (Salvelinus leucomaenis pluvius), and Japanese huchen (Hucho perryi). The results showed that the salmonid Hpa 1 family is widespread in the genomes of salmonid species. A method and equations are also presented for estimating the relationship between the ratio of a given repetitive family to all the Pol III genes and its average sequence divergence by calculating the molar ratio of the runoff transcript to all the in vitro Pol III transcripts.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 78
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 13 (1979), S. 295-304 
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Restriction endonuclease mappings and mitochondrial DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A new estimate of the sequence divergence of mitochondrial DNA in related species using restriction enzyme maps is constructed. The estimate is derived assuming a simple Posisson-like model for the evolutionary process and is chosen to maximize an expression which is a reasonable approximation to the true likelihood of the restriction map data. Using this estimate, four sets of mitochondrial DNA data are analyzed and discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 79
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 33 (1991), S. 133-141 
    ISSN: 1432-1432
    Schlagwort(e): Y-chromosome ; DNA ; Human ; Primate ; Evolution ; PUPPY sequence ; Alu element
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A Y-chromosomal DNA fragment has been isolated from a human Y-Charon 21A recombinant library. Evolutionary analysis of 1F5 indicates that the size and sequence of this fragment have been conserved in higher primates. Deletion mapping and in situ hybridization analysis have localized 1F5 to the middle euchromatic portion of the long arm of the human Y chromosome at Yq11.2. Sequence analysis revealed the presence of an atypical Alu element and two regions rich in polypyrimidine-polypurine residues.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 80
    ISSN: 1432-1432
    Schlagwort(e): Lagomorphs ; Rabbit ; Mitochondrial DNA ; Heteroplasmy ; Restriction site polymorphism ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A characterization was conducted on mitochondrial DNA (mtDNA) molecules extracted separately from 107 European rabbits (Oryctolagus cuniculus) both wild and domestic, 13 European hares (Lepus capensis), and 1 eastern cottontail (Sylvilagus floridanus). Experimentally this study took into account restriction site polymorphism, overall length variation of the noncoding region, and numbers of repeated sequences. Nucleotide divergences indicate that the mtDNAs from the three species derived from a common ancestor some 6–8 million years (Myr) ago. Every animal appeared heteroplasmic for a set of molecules with various lengths of the noncoding region and variable numbers of repeated sequences that contribute to them. This systematic heteroplasmy, most probably generated by a rate of localized mtDNA rearrangements high enough to counterbalance the cellular segregation of rearranged molecules, is a shared derived character of leporids. The geographic distribution of mtDNA polymorphism among wild rabbit populations over the western European basin shows that two molecular lineages are represented, one in southern Spain, the second over northern Spain, France, and Tunisia. These two lineages derived from a common ancestor some 2 Myr ago. Their present geographical distribution may be correlated to the separation of rabbits into two stocks at the time of Mindel glaciation. Finally the distribution of mtDNA diversity exhibits a mosaic pattern both at inter- and intrapopulation levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 81
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 33 (1991), S. 175-178 
    ISSN: 1432-1432
    Schlagwort(e): Aspergillus ; 5S rRNA genes ; 5S rRNA pseudogenes ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary We have cloned and determined the nucleotide sequence of 18 DNA fragments hybridizing to 5S rRNA from twoAspergillus species-A. wentii andA. awamori. Four of the analyzed sequences were pseudogenes. The gene sequences of these two species were very similar and differed fromAspergillus nidulans at both constant and microheterogeneous sites.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 82
    ISSN: 1432-1432
    Schlagwort(e): Bacteria ; Sugars ; Phosphotransferase system ; Transport proteins ; Evolution ; Sequence comparisons ; NADH dehydrogenase ; Mitochondria
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The amino acid sequences of 15 sugar permeases of the bacterial phosphoenolpyruvatedependent phosphotransferase system (PTS) were divided into four homologous segments, and these segments were analyzed to give phylogenetic trees. The permease segments fell into four clusters: the lactose-cellobiose cluster, the fructose-mannitol cluster, the glucose-N-acetylglucosamine cluster, and the sucrose-β-glucoside cluster. Sequences of the glucitol and mannose permeases (clusters 5 and 6, respectively) were too dissimilar to establish homology with the other permeases, but short regions of statistically significant sequence similarities were noted. The functional and structural relationships of these permease segments are discussed. Some of the homologous PTS permeases were found to exhibit sufficient sequence similarity to subunits 4 and 5 of the eukaryotic mitochondrial NADH dehydrogenase complex to suggest homology. Moreover, subunits 4 and 5 of this complex appeared to be homologous to each other, suggesting that these PTS and mitochondrial proteins comprise a superfamily. The integral membrane subunits of the evolutionarily divergent mannose PTS permease, the P and M subunits, exhibited limited sequence similarity to subunit 6 of the mitochondrial F1F0-ATPase and subunit 5b of cytochrome oxidase, respectively. These results suggest that PTS sugar permeases and mitochondrial proton-translocating proteins may be related, although the possibility of convergent evolution cannot be ruled out.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 83
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 33 (1991), S. 207-208 
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Vesicle ; Biogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The earliest fossil stromatolites present evidence of a complex ecosystem of photosynthetic organisms. Because the origin of present life can be dated within a few hundred million years prior to these fossils, their complexity poses a problem. A heuristic model outlines the first radiation leading to the universal ancestor.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 84
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 15 (1980), S. 149-159 
    ISSN: 1432-1432
    Schlagwort(e): Genes ; REH theory ; Genetic distance ; Evolution ; mRNA ; Nucleic acids
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is shown how REH theory in conjunction with mRNA or gene sequence data can be used to obtain estimates of the fixation intensity, the number of varions, and the total mutations fixed between homologous pairs of nucleic acids. These estimates are more accurate than those that can be derived from amino acid sequence data. The method is illustrated forα andβ hemoglobin genes and these improved estimates are compared with those made from the amino acid sequences for which those genes code. Significant differences are found between the estimates made by these two methods. For theβ hemoglobin gene sequences examined here, the fixation intensity is some-what less than the protein data had suggested, and the number of rations is considerably greater. Depending on the gene sequences examined, between 62 and 83% of the codons appear able to fix mutations during the divergences considered. This reflects the constraints of natural selection on acceptable mutations. The total number of base replacements separating the genes for human, mouse, and rabbitβ hemoglobin varies from 61 to 105 depending on the pair examined. Rabbitα andβ hemoglobin are separated by at least 290 fixed mutations. For such distantly related sequences estimates made from protein and mRNA data differ less, reflecting the higher quality of information from the many observed changes in primary structure. The effects of nonrandom gene structure on these evolutionary estimates and the fact that various genetic events are not equiprobable are discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 85
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 28 (1988), S. 98-112 
    ISSN: 1432-1432
    Schlagwort(e): rRNA ; Evolution ; Sequence comparison ; Parsimony ; Bootstrap
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Sequences of small subunit (SSU) and large subunit (LSU) ribosomal RNA genes from archaebacteria, eubacteria, and the nucleus, chloroplasts, and mitochondria of eukaryotes have been compared in order to identify the most conservative positions. Aligned sets of these positions for both SSU and LSU rRNA have been used to generate tree diagrams relating the source organisms/organelles. Branching patterns were evaluated using the statistical bootstrapping technique. The resulting SSU and LSU trees are remarkably congruent and show a high degree of similarity with those based on alternative data sets and/or generated by different techniques. In addition to providing insights into the evolution of prokaryotic and eukaryotic (nuclear) lineages, the analysis reported here provides, for the first time, an extensive phylogeny of the mitochondrial lineage.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 86
    ISSN: 1432-1432
    Schlagwort(e): Aspergillus nidulans ; 5S rRNA ; Pseudogenes ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary AllAspergillus nidulans 5S rRNA pseudogenes known so far are the result of integration of an approx. 0.2-kbp-long DNA sequence into the 5S rRNA genes. This sequence, called block C, is present in at least five copies in theA. nidulans genome and seems to be associated either with 5S rRNA genes or pseudogenes. In contrast to the 78% sequence conservation of the C-block in pseudogenes, the truncated 5′ halves of the pseudogenes are very highly conserved (96.9–100%). We postulate that the 5S rRNA pseudogenes are still a subject of concerted evolution. The C-block sequence shows similarity to the switch region of the mouse heavy chain immunoglobulin gene. A characteristic motif GGGTGAG is repeated several times in both sequences; the sequence conservation is 63%.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 87
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 28 (1988), S. 145-150 
    ISSN: 1432-1432
    Schlagwort(e): Alcohol dehydrogenase ; Drosophila ; Enzyme kinetics ; Product inhibition ; Microevolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Because natural populations ofDrosophila melanogaster are polymorphic for different allozymes of alcohol dehydrogenase (ADH) and becauseD. melanogaster is more tolerant to the toxic effects of ethanol than its sibling speciesD. simulans, information regarding the sensitivities of the different forms of ADH to the products of ethanol degradation are of ecological importance. ADH-F, ADH-S, ADH-71k ofD. melanogaster and the ADH ofD. simulans were inhibited by NADH, but the inhibition was relieved by NAD+. The order of sensitivity of NADH was ADH-F〈ADH-71k, ADH-S〈ADH-simulans with ADH-F being about four times less sensitive than theD. melanogaster enzymes and 12 times less sensitive than theD. simulans enzyme. Acetaldehyde inhibited the ethanolto-acetaldehyde activity of the ADHs, but at low acetaldehyde concentrations ethanol and NAD+ reduced the inhibition. ADH-71k and ADH-F were more subject to the inhibitory action of acetaldehyde than ADH-S and ADH-simulans, with ADH-71k being seven times more sensitive than ADH-S. The pattern of product inhibition of ADH-71k suggests a rapid equilibrium random mechanism for ethanol oxidation. Thus, although the ADH variants only differ by a few amino acids, these differences exert a far larger impact on their intrinsic properties than previously thought. How differences in product inhibition may be of significance in the evolution of the ADHs is discussed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 88
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 28 (1989), S. 220-224 
    ISSN: 1432-1432
    Schlagwort(e): Drosophila ; Foldback element ; Transposable element
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Foldback elements are a family of transposable elements described inDrosophila melanogaster. The members of this dispersed repetitive family have terminal inverted repeats that sometimes flank a central region. The inverted repeats of all the family members are homologous. The study of the distribution and conservation of the foldback elements in differentDrosophila species shows that this distribution is different from that of the hybrid dysgenesis systems (PM and IR). Sequences homologous to foldback elements were observed by Southern blots and in situ hybridization in all species of themelanogaster subgroup and in some species of themontium andtakahashii subgroups. The element was probably already present before the radiation of these subgroups. No evidence of horizontal transmission of the foldback element could be observed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 89
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 28 (1989), S. 175-184 
    ISSN: 1432-1432
    Schlagwort(e): Sheep ; Globin genes ; Evolution ; Gene duplication
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Domestic sheep have two common alleles at the adult β-globin locus,β A andβ B. Here we report the structure of the β-globin locus of A-haplotype sheep. The locus consists of 12 genes, organized as a triplicated 4-gene set: 5′ ∈I-∈II-ΨβI-βC-∈III-∈IV-ΨβII-βA-∈V-∈VI-ΨβIII-βF 3′. This arrangement is identical to that of the closely related goat locus. Sheep with the B haplotype have a locus arrangement consisting of a duplicated four-gene set, lacking the βC gene as well as three other genes present in A sheep and goats. In order to understand the evolutionary history of the B sheep locus, we have sequenced the βB gene from these sheep, and the βB gene from A-haplotype sheep, and compared the sequences to those of the sheep βA, goat βC, and βA, and cow adult β genes. Our results indicate that the βB gene has diverged recently from the βA gene, and therefore the βB locus structure may have resulted from a recent deletion from a triplicated locus.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 90
    ISSN: 1432-1432
    Schlagwort(e): Evolution ; Multiple sequence alignment ; NTP binding ; Phylogenetic analysis ; Positive-strand RNA viruses
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary NTP-motif, a consensus sequence previously shown to be characteristic of numerous NTP-utilizing enzymes, was identified in nonstructural proteins of several groups of positive-strand RNA viruses. These groups include picorna-, alpha-, and coronaviruses infecting animals and como-, poty-, tobamo-, tricorna-, hordei-, and furoviruses of plants, totalling 21 viruses. It has been demonstrated that the viral NTP-motif-containing proteins constitute three distinct families, the sequences within each family being similar to each other at a statistically highly significant level. A lower, but still valid similarity has also been revealed between the families. An overall alignment has been generated, which includes several highly conserved sequence stretches. The two most prominent of the latter contain the socalled “A” and “B” sites of the NTP-motif, with four of the five invariant amino acid residues observed within these sequences. These observations, taken together with the results of comparative analysis of the positions occupied by respective proteins (domains) in viral multidomain proteins, suggest that all the NTP-motif-containing proteins of positive-strand RNA viruses are homologous, constituting a highly diverged monophyletic group. In this group the “A” and “B” sites of the NTP-motif are the most conserved sequences and, by inference, should play the principal role in the functioning of the proteins. A hypothesis is proposed that all these proteins posses NTP-binding capacity and possibly NTPase activity, performing some NTP-dependent function in viral RNA replication. The importance of phylogenetic analysis for the assessment of the significance of the occurrence of the NTP-motif (and of sequence motifs of this sort in general) in proteins is emphasized.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 91
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 1 (1971), S. 112-114 
    ISSN: 1432-1432
    Schlagwort(e): Nucleotides ; Imidazole ; Condensation ; Evolution ; Prebiotic ; Oligonucleotides ; Phosphodiester
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The condensation of thymidine-5′-monophosphate was carried out in the presence of imidazole in aqueous solutions at neutral pH. Formation of oligo-deoxyribonucleotides up to four units was observed.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 92
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 1 (1972), S. 258-262 
    ISSN: 1432-1432
    Schlagwort(e): Calcitonin ; Evolution ; Genetic Code ; Mutation ; Amino Acid Sequences ; Base Changes ; Phylogeny
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The amino acid replacements in the calcitonins from five different species (human, bovine, ovine, porcine and salmon) have been analyzed according to the genetic code. More mutations separate the presumed common mammal from the artiodactyls than from either salmon or man.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 93
    ISSN: 1432-1432
    Schlagwort(e): Ribosome ; 5S RNA ; Conformation ; Evolution
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Fox and Woese (1975a) have shown that a model of 5S RNA secondary structure similar to the one originally derived forChlorella 5S RNA can be generalized with relatively minor variations to all sequenced 5S RNA molecules, i.e. that corresponding base paired regions can be formed at approximately the same positions. We present experimental data in favour of this hypothesis and show that the points at which ribonucleases T1, T2 and pancreatic ribonuclease cleave six different 5S RNA molecules under ‘mild’ conditions (high ionic strength, low temperature, low RNAase concentration) nearly always fall in the proposed single-stranded regions. We conclude that this model is a good approximation to the conformation of 5S RNA in solution.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 94
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 10 (1977), S. 123-135 
    ISSN: 1432-1432
    Schlagwort(e): Ancestral sequence ; Eye lens protein ; Evolution ; Phylogenetic tree
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The sequences of the A chains of the eye lens proteinα-crystallin from seventeen mammalian species were compared. They showed a generally slow rate of evolution, but with marked variations in different lineages. Most substitutions have occurred in the C-terminal part of the chain, which probably forms part of the surface of theα-crystallin aggregate. The ancestral sequence method of Dayhoff revealed interesting indications about the phylogenetic relationships between the eleven mammalian orders that were represented by the investigated species. Most evident was the divergence of marsupial and placental orders. A notable resemblance between the hyrax and elephant sequences was observed, setting them apart from the ungulates, including whale. Primates, rodents, lagomorphs, insectivores and tupaiids seem to derive from a common stem group. These phylogenetic inferences are discussed in relation to current palaeontological and taxonomical opinions, and compared to evidence from other protein sequence data.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 95
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 11 (1978), S. 109-120 
    ISSN: 1432-1432
    Schlagwort(e): Origin of Life ; Genetic code ; Protein synthesis ; Evolution ; Prebiotic reactions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The fact that proteins contain onlya-amino acids and that protein structure is determined by 3′ → 5′ linked ribonucleotides is postulated to be the result of the copolymerization of these molecules in the prebiotic environment. Ribonucleotides therefore represent partial degradation products and proteins represent a side reaction developing from copolymerization. The basic structural unit of copolymerization is a nucleotide substituted with an amino acid at the 2′ position. Characteristics of modern amino and ribonucleic acid structure are all consistent with and necessary for this hypothesis. The characteristics and individual base assignments of the code also provide strong support for origin from the postulated copolymers. All characteristics of the code can be accounted for by this single hypothesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 96
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 11 (1978), S. 225-231 
    ISSN: 1432-1432
    Schlagwort(e): Phylogenetic denseness ; Phylogenetic trees ; Topology ; Molecular reconstructions ; Evolution ; Paleogenetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The concept of phylogenetic denseness bears critically on the accuracy of evolutionary pathways inferred from experimentally sequenced proteins isolated from extant species. In this paper I develop an objective measure,ρ, of denseness to supplement previous intuitive concepts and which permits one to use this concept in comparing the quality of different evolutionary reconstructions. This measure is used to examine several published phylogenetic trees: insulin, a-hemoglobin,β-hemoglobin, myoglobin, cytochromec, and the parvalbumin family. The paper emphasizes 1) the importance of denseness in accurately estimating the number of nucleotide replacements which separate homologous sequences when this estimation is made by the method of parsimony, 2) the value of this concept in assessing the quality of those estimates, and 3) the use of this concept as a biologically practical heuristic method for identifying poorly studied regions in a phylogenetic tree, whether or not the tree was obtained by the parsimony method.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 97
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 13 (1979), S. 95-101 
    ISSN: 1432-1432
    Schlagwort(e): Oparin Ocean ; Origin of Life ; Evolution ; Runaway greenhouse ; Photosynthesis ; Methanogenesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The widely accepted Oparin thesis for the origin and early evolution of life seems sufficiently far from the true state of affairs as to be considered incorrect. It is proposed that life on earth actually arose in the planet's atmosphere, however an atmosphere very different from the present one. Because of an extremely warm surface, the early earth may have possessed no liquid surface water, its water being partitioned between a molten crust and a fairly dense atmosphere. Early preliving systems are taken to arise in the droplet phase in such an atmosphere. The early earth, which resembled Venus then and to some extent now, underwent a transition to its present condition largely as a result of the evolution of methanogenic metabolism.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 98
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 14 (1979), S. 13-31 
    ISSN: 1432-1432
    Schlagwort(e): Mars ; Evolution ; Planetary geochemistry ; Soil ; Ionizing radiation ; Exobiology
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Physical and chemical considerations permit the division of the near-surface regolith on Mars into at least six zones of distinct microenvironments. The zones are euphotic, duricrust/peds, tempofrost, permafrost, endolithic, and interfacial/transitional. Microenvironments vary significantly in temperature extremes, mean temperature, salt content, relative pressure of water vapor, UV and visible light irradiance, and exposure to ionizing radiation events (100 Mrad) and oxidative molecular species. From what is known of the chemistry of the atmossphere and regolith fines (soil), limits upon the aqueous chemistry of soil pastesmay be estimated. Heat of wetting could reach 45 cal/g dry soil; initial pH is indeterminate between 1 and 10; ionic strength and salinity are predicted to be extremely high; freezing point depression is inadequate to provide quantities of liquid water except in special cases. The prospects for biotic survival are grim by terrestrial standards, but the extremes of biological resiliency are inaccessible to evaluation. Second-generation in situ experiments which will better define Martian microenvironments are clearly possible. Antarctic dry valleys are approximations to Martian conditions, but deviate significantly by at least half-a-dozen criteria.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 99
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 16 (1980), S. 149-150 
    ISSN: 1432-1432
    Schlagwort(e): Exons ; Evolution ; Heme-binding proteins
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary It is known that globin genes contain three exons with the middle exon coding for a four-helical supersecondary structure responsible for heme binding. Since this portion of the globin peptide chain can be structurally superimposed onto the cytochromec and cytochromeb 5 chains (Argos and Rossmann 1979), it can be inferred that the cytochromec gene will contain only one coding sequence while the cytochromeb 5 gene will be composed of three exons as found in the globin gene.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 100
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular evolution 16 (1980), S. 211-267 
    ISSN: 1432-1432
    Schlagwort(e): Nucleic acids ; Proteins ; Natural selection ; Genetics ; Nonrandom molecular divergence ; Nonrandom REH theory ; Evolution ; mRNA ; DNA
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary REH theory is extended by deriving the theoretical equations that permit one to analyze the nonrandom molecular divergence of homologous genes and proteins. The nonrandomicities considered are amino acid and base composition, the frequencies with which each of the four nucleotides is replaced by one of the other three, unequal usage of degenerate codons, distribution of fixed base replacements at the three nucleotide positions within codons, and distributions of fixed base replacements among codons. The latter two distributions turn out to dominate the accuracy of genetic distance estimates. The negative binomial density is used to allow for the unequal mutability of different codon sites, and the implications of its two limiting forms, the Poisson and geometric distributions, are considered. It is shown that the fixation intensity — the average number of base replacements per variable codon - is expressible as the simple product of two factors, the first describing the asymmetry of the distribution of base replacements over the gene and the second defining the ratio of the average probability that a codon will fix a mutation to the probability that it will not. Tables are given relating these features to experimentally observable quantities inα hemoglobin,β hemoglobin, myoglobin, cytochromec, and the parvalbumin group of proteins and to the structure of their corre-sponding genes or mRNAs. The principal results are (1) more accurate methods of estimating parameters of evolutionary interest from experimental gene and protein sequence data, and (2) the fact that change in gene and protein structure has been a much less efficient process than previously believed in the sense of requiring many more base replacements to effect a given structural change than earlier estimation procedures had indicated. This inefficiency is directly traceable to Darwinian selection for the nonrandom gene or protein structures necessary for biological function. The application of these methods is illustrated by detailed consideration of the rabbitα -andβ hemoglobin mRNAs and the proteins for which they code. It is found that these two genes are separated by about 425 fixed base replacements, which is a factor of two greater than earlier estimates. The replacements are distributed over approximately 114 codon sites that were free to accept base mutations during the divergence of these two genes.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...