Browsing by Author "GONZALEZ, M"

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    A HIGH-MOLECULAR-WEIGHT PROTEOGLYCAN IS DIFFERENTIALLY EXPRESSED DURING DEVELOPMENT OF THE MOLLUSK CONCHOLEPAS-CONCHOLEPAS (MOLLUSCA, GASTROPODA, MURICIDAE)
    (1992) BRANDAN, E; GONZALEZ, M; INESTROSA, NC; TREMBLAY, C; URREA, R
    Incorporation of radioactive sulfate to hatched veliger larvae of the gastropod muricid Concholepas concholepas indicated that over 87% of the sulfated macromolecules were found in the detergent insoluble fraction, rich in extracellular matrix (ECM) components. The sulfated material was solubilized with guanidine salt followed by urea dialysis and fractionated by DEAE-Sephacel chromatography. Three sulfated compounds eluting at 0.7, 1.1, and 3.0 M NaCl, called peaks I, II, and III, respectively, were obtained. The sulfated compound present in peak I was degraded by pronase or sodium alkaline treatment to a small sulfated resistant material, suggesting the presence of a proteoglycan (PG). Filtration analysis on Sephacryl S-500 and SDS-PAGE of the intact PG indicates that it has a high molecular weight (360,000 to over 1 X 10(6)). Monoclonal antibodies (mAb) against this PG were produced. The specificity of one mAb, the 6H2, was demonstrated by size chromatography and ELISA analysis. The epitope recognized by this mAb seems to be present in the core protein of the PG. Both the extent of sulfation and the presence of different sulfated species of PGs were evaluated during the development of this mollusc. A twelvefold increase in the incorporation of sulfate to PGs per milligram of protein was found in veliger larvae compared to blastula-glastula stages. This change correlated well with the differential expression of the sulfated PG present in peak I. Biochemical and immunological analysis indicate that high levels of this PG are found in veliger and trocophore larvae in comparison with blastula-gastrula and early juveniles. These results indicate that a high molecular weight PG probably of the ECM is differentially expressed during the development of the gastropod Concholepas concholepas.
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    HIGH-DOSE INTRAVENOUS METHYLPREDNISOLONE THERAPY ASSOCIATED WITH OSTEONECROSIS IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS
    (1992) MASSARDO, L; JACOBELLI, S; LEISSNER, M; GONZALEZ, M; VILLARROEL, L; RIVERO, S
    Osteonecrosis is related to the use of steroids in patients with systemic lupus erythematosus (SLE); its association with the use of 'pulses' of methylprednisolone (PMP) is not clear at present. In a retrospective analysis of 190 patients with SLE we found that 19% of 36 patients treated with PMP had osteonecrosis compared with 6% of 154 patients without that treatment (P < 0.04). Risk factors associated with osteonecrosis were PMP treatment, cushingoid appearance, steroid doses greater-than-or-equal-to 40 mg/day during the first month of treatment, a ratio of steroid dose in grams/year greater-than-or-equal-to 12, hematuria and proteinuria. In a stepwise regression model, when cushingoid appearance was excluded, PMP became the only significant factor (P = 0.045).
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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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    ISOLATION OF PROTEOGLYCANS SYNTHESIZED BY RAT-HEART - EVIDENCE FOR THE PRESENCE OF SEVERAL DISTINCT FORMS
    (1992) GONZALEZ, R; URREA, R; GONZALEZ, M; INESTROSA, NC; BRANDAN, E
    1. The proteoglycans (Ps) synthesized by auricle and ventricle from adult rat
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    METAMORPHOSIS OF CONCHOLEPAS-CONCHOLEPAS (BRUGUIERE, 1789) INDUCED BY EXCESS POTASSIUM
    (1993) INESTROSA, NC; GONZALEZ, M; CAMPOS, EO
    Planktonic larvae of Concholepas concholepas Bruguiere underwent complete metamorphosis in response to excess K+. The effect was dose-dependent and optimal at approximately double the normal concentration of K+ in 0.45 um membrane-filtered seawater. Increasing concentration over 25 mM K+ produced a decline in survival, suggesting toxicity. Metamorphosis began with propodium attachment to the substratum and subsequent deciliation and destruction of the velum, followed by the emergence of cephalic tentacles from the larval shell margin. Velar loss, induced by K+, began with the detachment of large ciliated cells at the velar margin. Field-collected larvae, from different localities along the Chilean coast, presented a positive response to excess K+, and almost 80% of the larvae metamorphosed in 1 to 2 days. The induction of metamorphosis of Concholepas concholepas larvae by K+, provides a useful biotechnological tool for the cultivation of this socio-economically important marine resource of the southeastern Pacific Ocean.
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    MOLECULAR-CHANGES INDUCED BY METAMORPHOSIS IN LARVAE OF THE PROSOBRANCH CONCHOLEPAS-CONCHOLEPAS BRUGUIERE (MOLLUSCA, GASTROPODA, MURICIDAE)
    (1993) INESTROSA, NC; GONZALEZ, M; CAMPOS, EO
    Metamorphosis may be the most critical point in the life history of marine molluscs. Excess potassium was used to trigger the metamorphic process in competent larvae of the prosobranch Concholepas concholepas Bruguiere. The specific, irreversible stimulation of complex morphogenetic events by this exogenous factor was used to study some molecular changes that occur during metamorphosis. Results show that metamorphosis entails several molecular changes, including: (1) a modification in the pattern of protein synthesis measured by incorporation of [S-35]methionine to newly synthetized polypeptides, (2) an increase of [S-35]methionine incorporation in heparin-binding proteins or the induction of heparin-binding proteins (i.e. growth factors?), (3) a decrease (20 times) in the larval levels of the second messenger cyclic AMP, and (4) the appearance of a new form of the neurotransmitter-related enzyme, acetylcholinesterase (AChE). To our knowledge this is the first attempt to characterize some of the molecular changes that take place during molluscan metamorphosis.
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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.
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    ROTATIONAL BEHAVIOR IN THE CAT INDUCED BY ELECTRICAL-STIMULATION OF THE PULVINAR LATERALIS POSTERIOR NUCLEUS COMPLEX - ROLE OF THE CHOLINERGIC SYSTEM
    (1983) MOTLES, E; GONZALEZ, M; INFANTE, C
    The involvement of the cholinergic system in the contralateral head-eye-body turning induced in the cat through stimulation of the pulvinar-lateralis posterior nucleus complex (P-LP) was studied. In 17 cats through a cannula aimed at the P-LP, agonists and antagonists of the cholinergic system were injected. The electrical activity of the P-LP could be recorded through the same cannula or through electrodes attached to it. Electrodes were implanted ipsilaterally in the dorsal hippocampus, caudate nucleus, amygdala, and superior colliculus to record through them and through one screw placed on the skull the electrical activity of those structures and of the cortical P-LP projection. Seven days after surgery, carbachol, an agonist of the cholinergic system was injected in the P-LP, and the behavior and electrical activity of the unrestrained cat (previously accustomed to a plastic cage) were recorded. A control volume of 0.9% NaCl was always injected previously. The usual drug volume injected was 1 .mu.l; occasionally, 2 .mu.l were injected. Weekly or biweekly sessions were conducted to determine the threshold for cholinergic activation, the threshold for turning behavior, the blocking effect of local atropine sulfate injected previously, the effect of haloperidol previously injected (locally or systemically), and the effect of dioxolane, an exclusive muscarinic agonist. In 14 of 17 cats, contralateral turning behavior was evoked by carbachol. In 2 of the 3 cats that did not respond to carbachol, dioxolane induced turning. The effect of dioxolane was similar to that of carbachol when tried in 5 cats. Besides turning behavior, carbachol produced numerous symptoms due to cholinergic activation. Atropine blocked the rotational effect of carbachol in all cats, and haloperidol blocked it in 68% of them. Electrolytic coagulation of the dorsal hippocampus surrounding the P-LP did not disturb the effects induced by carbachol. Both systems of the P-LP, cholinergic and catecholaminergic, are involved in the contralateral turning. The effect induced by carbachol is due to activation of muscarinic receptors because it is totally blocked by local atropine sulfate and is reproduced by dioxolane, an exclusive muscarinic agonist.
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    SULFATION IS REQUIRED FOR MOBILITY OF VELIGER LARVAE OF CONCHOLEPAS-CONCHOLEPAS (MOLLUSCA, GASTROPODA, MURICIDAE)
    (1992) URREA, R; GONZALEZ, M; INESTROSA, NC; BRANDAN, E
    The sulfation reaction seems to be a critical biochemical process during early steps of development. We have evaluated the effect of sulfation on the mobility of veliger larvae of the gastropod Concholepas concholepas. It was found that incubation of larvae in low-sulfate artificial sea water had strong inhibitory effect on mobility. The use of sodium chlorate, a specific inhibitor of sulfation, also resulted in a strong inhibition of larval mobility. At the biochemical level, the synthesis of proteoglycans (PGs) and detergent-soluble sulfoproteins and sulfolipids was specifically inhibited by chlorate, without affecting either total protein synthesis or phosphorylation. Intracellular levels of the sulfate donor 3'-phosphoadenosine 5'-phosphosulfate (PAPS) were decreased to 4% by chlorate treatment, indicating that this molecule is also involved in sulfation of marine invertebrates. Both effects of chlorate, the inhibition of sulfation and the larval mobility, were reversible. It is therefore concluded that sulfation is required for larval mobility in the mollusc C. concholepas.