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  • 1995-1999  (3)
  • 1985-1989  (7)
  • 1965-1969  (7)
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  • 1
    Buch
    Buch
    Lawrence, Kan.
    Materialart: Buch
    Seiten: IX, 629 S. , überw. Ill., graph. Darst.
    ISBN: 0935868135
    DDC: 593.1012
    Sprache: Englisch
    Anmerkung: Literaturangaben
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1089-7682
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: In support of the spiral wave theory of reentry, simulation studies and animal models have been utilized to show various patterns of spiral wave tip motion such as meandering and drifting. However, the demonstration of these or any other patterns in cardiac tissues have been limited. Whether such patterns of spiral tip motion are commonly observed in fibrillating cardiac tissues is unknown, and whether such patterns form the basis of ventricular tachycardia or fibrillation remain debatable. Using a computerized dynamic activation display, 108 episodes of atrial and ventricular tachycardia and fibrillation in isolated and intact canine cardiac tissues, as well as in vitro swine and myopathic human cardiac tissues, were analyzed for patterns of nonstationary, spiral wave tip motion. Among them, 46 episodes were from normal animal myocardium without pharmacological perturbations, 50 samples were from normal animal myocardium, either treated with drugs or had chemical ablation of the subendocardium, and 12 samples were from diseased human hearts. Among the total episodes, 11 of them had obvious nonstationary spiral tip motion with a life span of 〉2 cycles and with consecutive reentrant paths distinct from each other. Four patterns were observed: (1) meandering with an inward petal flower in 2; (2) meandering with outward petals in 5; (3) irregularly concentric in 3 (core moving about a common center); and (4) drift in 1 (linear core movement). The life span of a single nonstationary spiral wave lasted no more than 7 complete cycles with a mean of 4.6±4.3, and a median of 4.5 cycles in our samples. Conclusion: (1) Patently evident nonstationary spiral waves with long life spans were uncommon in our sample of mostly normal cardiac tissues, thus making a single meandering spiral wave an unlikely major mechanism of fibrillation in normal ventricular myocardium. (2) A tendency toward four patterns of nonstationary spiral tip motion was observed. © 1998 American Institute of Physics.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: .Attention, perhaps overdue, is drawn to the extent and significance of endosymbionts (xenosomes sensu lato) in the cytoplasm and nuclei of many protozoa from diverse taxonomic groups. Even more importantly, recent advances in the study of such intimate associations are reviewed and discussed and their impact on broader problems of cell biology and evolution are stressed. Workers inside and especially outside the fields of protozoology and parasitology have often neglected such data, failing to appreciate their relevance to significant problems in their own fields of investigation. The major topics covered by speakers in the Symposium (to which this paper serves only as an introduction) include the following, in order of their presentation: terminology for the symbiont-host relationship and a brief overview of the field; the evolutionary problem of the origin of contemporary associations, including cell organelles such as mitochondria and plastids; the adaptive value of endosymbionts to their protozoan hosts; mechanisms of establishment, maintenance, and integration of such foreign bodies/invaders in their unicellular eukaryotic host cells; and the extent of algal and bacterial endosymbioses in diverse protozoan groups. In all papers, the principal relatively well studied complexes used as examples are the following: various kinds of algae in the larger foraminifera and in ciliates, radiolarians, and acantharians; the several types of bacteria in the cytoplasm of Amoeba and of Pelomyxa; the endonuclear bacterial symbionts of Paramecium; the cytoplasmic prokaryotes in Paramecium and in Parauronema; and the methanogenic bacteria of certain ciliates.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: .It is generally accepted that in symbiotic systems involving algal species as cellular endobionts there is some positive benefit to the host organisms. In this paper special consideration is given to the larger foraminifera, protozoa that serve as very useful model systems for the study of aspects of inter/intracellular integration and adaptation—living, as they do, in nutrient-limited but well illuminated shallow tropical seas and containing endosymbiotic algae in abundance. A considerable amount of information is now available on physiological as well as morphological adaptations of the host species to pigmented protists representing diverse algal divisions (phyla). Brief mention is also made of bacterial endosymbionts of certain ciliates.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Long neglected has been the extensive and more or less intimate association of protozoa with a wide variety of other cells, either prokaryotic or eukaryotic in nature. Yet study of such relationships can provide important information concerning certain basic aspects of cellular evolution in general. A survey is offered here of the whole range of such symbiotic associations (i.e. with species of protozoa serving as hosts) with the purposes of drawing attention to the exciting possibilities of such research and of reviewing significant findings made to date. Because of the vastness of the overall field, examples and discussion are primarily limited to consideration of the following major studies: methanogenic bacteria in certain ciliates, bacterial endosymbionts of the large freshwater amoeba Pelomyxa palustris (itself an amazing organism from an evolutionary/phylogenetic point of view), the rod-shaped bacteria found in Amoeba proteus, the “Greek-letter” prokaryotes of Paramecium species, the xenosomes (sensu stricto) of the marine scuticociliate Parauronema acutum, and the diverse algal endosymbionts of similarly diverse protozoan taxa–ciliates, flagellates, radiolarians, acantharians, and foraminifera.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 32 (1985), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: .Protozoa may be thought of as preadapted to serve as hosts for cellular endosymbionts by virtue of their widespread ability to take up particles by endocytosis. The absence of the cell wall so characteristic of plants and fungi and the commonly large size of most protozoa are additional factors favoring protozoan cells for endosymbioses. The conversion of symbiont into a cellular organelle (e.g. a mitochondrion or chloroplast) is more complicated, especially since the latter do not code for all of their own proteins. Thus, such conversions are held to be rare. Among protozoa, numerous foraminifera appear to have characteristics making them very favorable as hosts for certain algae. Such adaptations, both physiological and morphological in nature, are discussed. Also discussed in this paper are the ways by which (present-day) chloroplasts and mitochondria may have been derived from early endosymbionts: a single ancestral cyanobacterium, in the first case, and a single ancestral purple-nonsulfur bacterium, in the second. Mechanisms for insertion of proteins into and across the organellar membranes had to be evolved for all genes transferred from the symbionts into the host nucleus.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 13 (1966), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SYNOPSIS. Tracer technic has proved to be an excellent tool in the study of predator-prey relationships among the foraminifera. More than fifty axenic species of protists including diatoms, dinoflagellates, chlorophytes, chrysophytes, cyanophytes, bacteria and yeasts were tested as potential food for Allogromia sp (NF), A. laticollaris, Am. monia beccarii, Quinqueloculina spp, Rosalina floridana, Anomalina sp, Elphidium sp, Spiroloculina hyalina, Globigerina bulloides, and Globorotalia truncatulinoides. Although many types of potential food are present in the environment, foraminifera select only certain organisms. The yeasts, cyanophytes, dinoflagellates, chrysophytes and most bacteria tested were not eaten. Selected species of diatoms, chlorophytes and bacteria were eaten in large quantity. Three additional factors affect feeding: the “age” of the food organism, the “age” of the foraminifer or its position in the life cycle, and the concentration of the food. Feeding by foraminifera on most food is erratic below a concentration of 103 organisms and is approximately directly proportional to concentration within a range of 103-106 organisms per 10 ml experimental tube. A natural bloom of Protelphidium tisburyensis was analyzed. A high concentration of 6 species of diatoms characterized the community. A “bloom”-feeder hypothesis for foraminiferal nutrition is presented.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    ISSN: 1546-1718
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Medizin
    Notizen: [Auszug] The RP14 autosomal recessive Retinitis pigmentosa (arRP) locus has been mapped to a 2cM region of chromosome 6p21.3 (refs 1–3). TULP1 (the gene encoding tubby-like protein 1) is a candidate target for the disease mutation because it maps to the RP14 minimum genetic region and because a ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 13 (1966), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SYNOPSIS. Peranema trichophorum remained vigorous at least a year in milk-lecithin media and 3 months in a nearly defined autoclavable biphasic agar medium fortified with the fat-soluble antioxidant butylated hydroxytoluene. The only undefined substance in the present “defined” medium is crude soybean lecithin; 0.001% lecithin suffices in the presence of a mixture of long-chain saturated and unsaturated fatty acids. Linoleic acid may be indispensable. Histidine is an absolute requirement as well as a favored substrate. Cholesterol, not ergosterol, satisfied the sterol requirement. Voracity is retained in these media as shown by engorgement on plastic latex particles.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of eukaryotic microbiology 16 (1969), S. 0 
    ISSN: 1550-7408
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: SYNOPSIS. Bacteria were required for the sustained reproduction of 4 species of foraminifera in gnotobiotic culture. None of the species of algae tested, singly or in combination, supported continuous reproduction of the foraminifera in bacteria-free gnotobiotic culture. It is inferred that bacteria have some nutritional factor required by the foraminifera that is either unavailable or unavailable in sufficient quantity in an exclusively algal diet.Gnotobiotic clones of Quinqueloculina lata, Spiroloculina hyalina, Rosalina leei, and Allogromia laticollaris were established on bacteria + algae (usually 1 or 2 species). In balanced gnotobiotic cultures neither light nor foraminiferan density (organisms/ml) were limiting. As cultures aged, pH shifted and limited growth. When waste products were removed by washing, reproductive rates were higher.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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