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Recent advances in the evolutionary genetics of sex determination indicate that DMRT1 may be a vertebrate equivalent of the Drosophila melanogaster master sex regulator gene, doublesex. The role of DMRT1 seems to be confined to some aspects of male sex differentiation, whereas in Drosophila, doublesex has wider developmental effects in both sexes. This(More)
Biosemiotics is the idea that life is based on semiosis, i.e., on signs and codes. This idea has been strongly suggested by the discovery of the genetic code, but so far it has made little impact in the scientific world and is largely regarded as a philosophy rather than a science. The main reason for this is that modern biology assumes that signs and(More)
Systems Biology and the Modern Synthesis are recent versions of two classical biological paradigms that are known as structuralism and functionalism, or internalism and externalism. According to functionalism (or externalism), living matter is a fundamentally passive entity that owes its organization to external forces (functions that shape organs) or to an(More)
It is shown that information and meaning can be defined by operative procedures, and that we need to recognize them as new types of natural entities. They are not quantities (neither fundamental nor derived) because they cannot be measured, and they are not qualities because they are not subjective features. Here it is proposed to call them nominable(More)
The standard approach to the definition of the physical quantities has not produced satisfactory results with the concepts of information and meaning. In the case of information we have at least two unrelated definitions, while in the case of meaning we have no definition at all. Here it is shown that both information and meaning can be defined by operative(More)
New methods of inducing ribosome crystals in chick embryos are described, and it is shown that a close relationship exists between cell stress and ribosome crystallization. The formation of ribosome crystals in the nucleus and/or in the cytoplasm depends on the type of treatment and on the temperature of incubation, but in all cases the key event that(More)
The intracellular localizations of phosphatidylinositol 4,5-bisphosphate (PIP2) and of its hydrolyzing enzyme phospholipase C (PLC; in this case the beta 1 isoform) have been evaluated by electron microscope immunocytochemistry in cells exposed to mitogenic or differentiating agents. These cells have been previously demonstrated to present a signal(More)