Browsing by Author "GONZALEZPLAZA, R"

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    EFFECT OF PHENYTOIN ON CYTOSKELETAL PROTEIN-PHOSPHORYLATION AND NEURONAL STRUCTURE IN THE RAT SENSORY CORTEX
    (1987) RUIZ, G; FLORES, OG; GONZALEZPLAZA, R; INESTROSA, NC
    Phenytoin (PH) is commonly used as an anticonvulsant drug, and it causes several collateral effects including morphological changes in brain cortex neurons and teratogenic lesions in infants of epileptic mothers. Several lines of evidence indicate that PH may exert its action through the modification of phosphorylation patterns of neuronal polypeptides. We have studied the effects of PH on the phosphorylation of cytoskeletal proteins, because this could be related to the structural modifications induced by PH administration. The dendritic pattern of deep layers of the somatosensory cortex is clearly modified by PH but not the cell number, indicating that the drug disturbs the architecture of the neurons examined. In fact, the pattern of phosphorylation in cytoskeletal extracts of brains of 30-day-old rats is changed by PH. In vitro labeling experiments show decrease in the [32P] level of a 43-kDa polypeptide, whereas 38- and 120-kDa polypeptides show increases in their [32P] contents. The 43-kDa polypeptide has been identified as actin by in vitro experiments using a novel approach to determine cytoskeletal polypeptide behavior. We conclude that PH affects the posttranslational phosphorylation of actin and other related cytoskeletal proteins and in this manner may alter the normal morphological layout of dendritic patterns in the somatosensory cortex.
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    INCREASE OF MACROMOLECULE SYNTHESIS AFTER HATCHING OF CONCHOLEPAS-CONCHOLEPAS VELIGER LARVAE - EFFECT OF SULFATE IN THE SYNTHESIS OF PROTEOGLYCANS
    (1990) BRANDAN, E; GONZALEZ, M; GONZALEZPLAZA, R; INESTROSA, NC
    1. The synthesis of proteins, glycoproteins and sulfated macromolecules increase after hatching of the gastropod Concholepas concholepas larvae. 2. Sulfate present in the sea-water, stimulates over 30-fold the sulfation of sulfated macromolecules but not the proteins. 3. Analysis of the sulfated macromolecules indicates that almost 90% are localized in the larval insoluble material, corresponding to a high molecular weight macromolecule, probably a proteoglycan.
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    NEUROTRANSMITTER-RELATED ENZYME ACETYLCHOLINESTERASE IN JUVENILES OF CONCHOLEPAS-CONCHOLEPAS (MOLLUSCA, GASTROPODA, MURICIDAE)
    (1990) GONZALEZ, M; PERELMAN, A; FUENTES, ME; CASTILLA, JC; LABARCA, R; BRANDAN, E; GONZALEZPLAZA, R; INESTROSA, NC
    With the aim of understanding the organization of the nervous systemn in the Prosobranchia gastropod Concholepas concholepas, we studied the properties, specificity, sedimentation coefficient, and solubility of the cholinergic enzyme, acetylcholinesterase (AChE). It was found that 95% of the esterase was inhibited by BW284c51 dibromide but not by iso-OMPA, which is consistent with the specificity of AChE. The calculated Km 0.22 mM is eight to ten times higher than are the Kms for AChE of other invertebrates and similar to the values reported for fish and vertebrates. The AChE shows a maximal activity around 22.degree. C, has a glycoprotein character and presents sedimentation coefficients of 6.5 S and 10.5 S. Most of this AChE activity is soluble under low ionic strength conditions; however, the enzyme aggregates in the absence of detergents. In conclusion, our evidence indicates the presence of a well-recognized molecular marker that could be useful for the study of the development of Concholepas concholepas.