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  • 1
    ISSN: 1573-4919
    Keywords: particulate guanylate cyclase ; ANP receptors ; rat lung ; PK1 cells ; physical characteristics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary A line of kidney cells (PK,) which does not possess measurable ANP binding but has an active particulate guanylate cyclase has been identified. The physical characteristics of this enzyme were compared with those of particulate guanylate cyclase and ANP receptors isolated from rat lung. Although receptor and enzyme appear to reside on the same protein in the lung while the cyclase from PK1 cells does not possess ANP binding activity, these proteins exhibit identical physical characteristics. Guanylate cyclase from PK1 cells and rat lung and ANP receptor from lung co-eluted during gel filtration chromatography, with a Stokes radius of 6.1 nm. Also, these activities co-migrated through sucrose density gradients with S20,w values of 10.4 to 10.9. Using these parameters, a molecular weight of about 270 kD was estimated for all three activities. Furthermore, these enzyme activities exhibited similar mobilities in isoelectric focusing gels, with a pI of 6.1. Thus, although particulate guanylate cyclase from lung presumably possesses receptor binding activity, it is physically identical to a form of this enzyme associated with no measurable binding activity. Possible explanations for these observations are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biology and philosophy 3 (1988), S. 293-315 
    ISSN: 1572-8404
    Keywords: Scientific discovery ; theories of evolution ; John Herschel ; vera causae ; Charles Darwin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Philosophy
    Notes: Abstract Traditional logical empiricist and more recent historicist positions on the logic of discovery are briefly reviewed and both are found wanting. None have examined the historical detail now available from recent research on Darwin, from which there is evidence for gradual transition in descriptive and explanatory concepts. This episode also shows that revolutionary research can be directed by borrowed metascientific objectives and heuristics from other disciplines. Darwin's own revolutionary research took place within an ontological context borrowed from non evolutionary predecessors with methodological objectives borrowed from and justified by their success in Newton's physics. The logic of discovery is not a special form of inference from observation to theory, but rather a theory of the rationality of research, including principles bearing upon the rational choice of problems, or epistemic objectives, and heuristic, or means to solving the problems. Such choices can be justified only locally in the context of a relatively stable background ontology and substantive epistemology, not globally for all science.
    Type of Medium: Electronic Resource
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