Browsing by Author "TORRES, JC"

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    NEURAL 16S ACETYLCHOLINESTERASE IS SOLUBILIZED BY HEPARIN
    (1983) TORRES, JC; BEHRENS, MI; INESTROSA, NC
    The effect of heparin, a sulfated glycosaminoglycan, on the solubilization of rat sciatic-nerve acetylcholinesterase (acetylcholine acetylhydrolase; AChE; EC 3.1.1.7) was studied. Heparin solubilized esterase activity from ligated nerves. Sedimentation analysis revealed this activity to be mainly the 16S form. Chondroitin sulfate did not solubilize AChE activity, and protamine eliminated the solubilizng effect. The results suggest the involvement of sulfated glycosaminoglycans in the intra-axonal localization and transport of 16S AChE.
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    SLOW AXOPLASMIC-TRANSPORT - A FICTION
    (1985) ALVAREZ, J; TORRES, JC
    Ribosomes have not been observed in axoplasm. This had led to the notions that the perikaryon is the only source of neuronal proteins and that the axoplasm is supplied by a (slow) transport mechanism. These 2 notions were questioned because they are unable to give an account of real neurones in accordance with the body of biological knowledge. For example, the synthetic rate of perikarya or the life span of axoplasmic proteins should be beyond known ranges for animal cells and a uniform axon is unlikely to result if it is fed from one end. An alternative view was proposed for the maintenance of the axon which accepts the controversial idea of axoplasmic synthesis of proteins; as a result, the slow transport becomes unnecessary. This view gives a qualitative account of the observations dealing with the maintenance of the axoplasm. To account for the phenomenology in a more quantitative fashion, a computer simulation was carried out where the equations of the program provided only for axoplasmic synthesis of proteins; the set of curves retrieved were in good agreement with experimental findings believed so far to support the notion of slow transport. The notion of slow axoplasmic transport has been a misinterpretation of good observations because the frame of reference was incomplete in not providing for axoplasmic synthesis of proteins.
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    VEGETATIVE RESPONSES TO DEFOLIATION OF 2 CHILEAN MATORRAL SHRUBS
    (1980) TORRES, JC; GUTIERREZ, JR; FUENTES, ER
    Two common matorral species: Lithraea caustica and Colliguaya odorifera were experimentally defoliated, L. caustica and C. odorifera are the matorral species previously shown to exhibit the highest and lowest levels of natural defoliation by browsing. Experimental defoliation was performed at 4 levels: 0% (controls), 25, 66 and 100%. C. odorifera exhibited vegetative responses stronger than controls only in the 2 highest levels of defoliation (66 and 100%); L. caustica responded vigorously at the 25 and 100% levels. The results are related to the observed position of both species in the matorral community and their relative defoliation risks by natural and introduced herbivores.