For richer, for poorer: Financial behaviors, power (im)balance, and relational aggression among different-gender newlyweds in the U.S.

Guided by an intersectional feminism framework, we used three-wave, dyadic survey data from a nationally representative sample of 1625 U.S. different-gender newlywed couples to test three research questions. First, as balanced power is considered a key concept for relational well-being in feminism, we examined developmental trajectories in husbands' and wives' perception of power (im)balance. Second, considering money as a major influence on power and aggression, we examined how financial behaviors relate to power (im)balance and in turn relational aggression-a type of intimate partner violence that is controlling and manipulative in nature. Third, informed by the intersectionality between gender and socioeconomic status (SES), we examined gender differences and SES disparities in the associations among financial behaviors, developmental trajectories of perception of power (im)balance, and relational aggression. Our findings demonstrate that newlywed different-gender couples are experiencing power struggles, where two partners diminish each other's influence over time. We also found that healthy financial behaviors are associated with balanced power and, in turn, less relational aggression (especially for wives and in lower-SES households). Taken collectively, we continue calling for efforts to facilitate money management skills and promote balanced marital power.

Change in Retirement Plans Among Midlife Couples During an Economic Recession.

OBJECTIVE: Although research has investigated financial planning for retirement, less is known about how adults plan their retirement activities. Even less is known about couples' congruence and incongruence in retirement activities planning. The authors examined husband and wife reports of retirement plans across a 5-year period that involved a U.S. economic recession. METHOD: Using data from 335 midlife couples who participated in the Flourishing Families project, retirement plans were grouped into five categories-family, leisure, volunteer, work, and uncertain. We estimated probit dyadic structural equation models to explore longitudinal predictors of retirement plans. RESULTS: Results indicated mean differences in retirement plans between husbands and wives, and also across time that might have been influenced by surrounding economics. Wife poor health, number of children, both spouses working, and financial assets were linked with the likelihood of reporting certainty in retirement plans. Greater retirement uncertainty was predicted by lower marital quality, higher financial adjustments, lower education, and ethnic diversity. CONCLUSION: Husband and wife reports of retirement plans are not always congruent, and plans in retirement can be affected by large scale changes in the U.S. economy.

Mutant fibrinogen cleared from the endoplasmic reticulum via endoplasmic reticulum-associated protein degradation and autophagy: an explanation for liver disease.

The endoplasmic reticulum (ER) quality control processes recognize and remove aberrant proteins from the secretory pathway. Several variants of the plasma protein fibrinogen are recognized as aberrant and degraded by ER-associated protein degradation (ERAD), thus leading to hypofibrinogenemia. A subset of patients with hypofibrinogenemia exhibit hepatic ER accumulation of the variant fibrinogens and develop liver cirrhosis. One such variant named Aguadilla has a substitution of Arg375 to Trp in the gamma-chain. To understand the cellular mechanisms behind clearance of the aberrant Aguadilla gamma-chain, we expressed the mutant gammaD domain in yeast and found that it was cleared from the ER via ERAD. In addition, we discovered that when ERAD was saturated, aggregated Aguadilla gammaD accumulated within the ER while a soluble form of the polypeptide transited the secretory pathway to the trans-Golgi network where it was targeted to the vacuole for degradation. Examination of Aguadilla gammaD in an autophagy-deficient yeast strain showed stabilization of the aggregated ER form, indicating that these aggregates are normally cleared from the ER via the autophagic pathway. These findings have clinical relevance in the understanding of and treatment for ER storage diseases.

Expression and localization of proteoglycans during limb myogenic activation.

After arriving at the limb bud, migrating myogenic precursor cells express transcription factors responsible for the induction of terminal skeletal muscle differentiation. One such factor is myogenin, a member of the basic helix-loop-helix family, known to activate the expression of muscle-specific genes. The extracellular signals involved in activating the myogenic program in the muscle precursor cells that reach the limb in vivo are not known. However, in vitro, it has been shown that proteoglycans, macromolecules composed of a core protein and glycosaminoglycan chains, modulate the triggering of myogenin activity. To understand the role of proteoglycans during limb muscle development, we assessed the synthesis of proteoglycans in limb bud explants at 10.5 days post coitum, when migrating cells arrive, evaluated the expression and nature of these macromolecules during in vivo early limb bud formation, and determined the colocalization of myoblasts expressing myogenin with specific proteoglycans. We found that the expression of myogenin was temporally and spatially coincident with the expression of syndecan-3 and decorin, two essential proteoglycans in the modulation of skeletal muscle differentiation. This article is the first report of myogenic activation and proteoglycan expression during limb muscle formation.

Antisense inhibition of decorin expression in myoblasts decreases cell responsiveness to transforming growth factor beta and accelerates skeletal muscle differentiation.

Decorin is a member of the family of the small leucine-rich proteoglycans. In addition to its function as an extracellular matrix organizer, it has the ability to activate the epidermal growth factor receptor, and it forms complexes with various isoforms of transforming growth factor beta (TGF-beta). Decorin is expressed during skeletal muscle differentiation and is up-regulated in dystrophic muscle. In this study we investigated the role of decorin in TGF-beta-dependent inhibition of myogenesis. To probe the function of decorin during myogenesis, C(2)C(12) myoblasts were stably transfected with a plasmid expressing antisense decorin mRNA. The resulting inhibition of decorin expression led to the expression of myogenin, a master transcription factor for muscle differentiation, under growth conditions and accelerated skeletal muscle differentiation as determined by the expression of creatine kinase. In contrast myogenin expression was inhibited by adenovirally induced decorin expression or by adding exogenous decorin. Reduced synthesis of decorin resulted in a 7-fold decreased sensitivity to TGF-beta-mediated inhibition of myogenin expression. In contrast, adenovirally induced decorin expression in wild type cells resulted in a 5-fold increased sensitivity to TGF-beta-mediated inhibition of myogenin expression. Transfection studies with the TGF-beta-dependent promoter of the plasminogen activator inhibitor-1 coupled with luciferase revealed that the transducing receptors for TGF-beta1 and TGF-beta2 were involved in the different responses of wild type and antisense decorin myoblasts. These results demonstrate that a reduction of decorin expression or of decorin availability results in a decreased responsiveness to TGF-beta. These findings strongly suggest a new role for decorin during skeletal muscle terminal differentiation by activating TGF-beta-dependent signaling pathways.

Synthesis of proteoglycans is augmented in dystrophic mdx mouse skeletal muscle.

Mdx mice uniquely recover from degenerative dystrophic lesions through an intense myoproliferative response. The onset and progression of this process are controlled by a complex set of interactions between myoblasts and their environment. The presence of the extracellular matrix is essential for normal myogenesis. Proteoglycans are abundant components of the extracellular matrix. The synthesis of proteoglycans in mdx mice during skeletal muscle regeneration was evaluated. Incorporation of radioactive sulfate demonstrated a significant increase in the synthesis of several types of proteoglycans in mdx animals compared to age-matched controls. The size and charge of proteoglycans synthesized by the mdx mice remained unchanged. In particular, one of the up-regulated proteoglycans, the small chondroitin/dermatan sulfate proteoglycan decorin which is known to bind and to sequester transforming growth factor-beta, was investigated. Immunocytolocalization and in situ hybridization studies showed that decorin mainly accumulated in the endomysium, i.e. around individual skeletal muscle fibers from M. tibialis anterior and diaphragm.

Antisense inhibition of syndecan-3 expression during skeletal muscle differentiation accelerates myogenesis through a basic fibroblast growth factor-dependent mechanism.

Syndecan-3 is a member of a family of transmembrane proteoglycans that posses highly homologous cytoplasmic and transmembrane domains and function as extracellular matrix receptors and low-affinity receptors for signaling molecules such as basic fibroblasts growth factor (FGF-2). Syndecan-3 is transiently expressed in developing limb bud and absent in adult skeletal muscle. In this study we investigated the expression of syndecan-3 and its role on FGF-2-dependent inhibition of myogenesis. Syndecan-3 expression was down-regulated during skeletal muscle differentiation of C(2)C(12) myoblasts, as determined by Northern blot analyses and immunoprecipitation. To probe the function of syndecan-3 during myogenesis, C(2)C(12) myoblasts were stably transfected with a plasmid coding for antisense syndecan-3 mRNA. The resulting inhibition of syndecan-3 expression caused accelerated skeletal muscle differentiation, as determined by expression of creatine kinase and myosin and myoblast fusion. Expression of a master transcription factor for muscle differentiation, myogenin, was also accelerated in antisense syndecan-3-transfected myoblasts compared with control transfected and wild type cells. Reduced expression of syndecan-3 resulted in a 13-fold decrease in sensitivity to FGF-2-dependent inhibition of myogenin expression. Addition of heparin partially reversed this effect. These results demonstrate that syndecan-3 expression is down-regulated during differentiation and the level of expression of membrane-bound heparan sulfate on myoblast surface is critical for fine modulation of responsiveness to FGF-2. These findings strongly suggest a role for syndecan-3 in regulation of skeletal muscle terminal differentiation.

Interaction of skeletal muscle cells with collagen type IV is mediated by perlecan associated with the cell surface.

We have previously shown that the expression of perlecan, a heparan sulfate proteoglycan localized on the myoblast surface, is down-regulated during terminal differentiation of skeletal muscle myoblasts (Larraín et al. [1997] Exp. Cell Res. 234:405-412). In this study, we have evaluated the biochemical characteristics of perlecan, its association with the myoblast surface, and its involvement in C(2)C(12) myoblast adhesion to different substrates. Perlecan associated with myoblasts was solubilized by Triton X-100, whereas heparin, high salt, and RGD peptides were unable to solubilize perlecan. Pre-incubation of myoblasts with [(35)S]-Na(2)SO(4), followed by solubilization with Triton X-100 and immunoprecipitation with antibodies against murine perlecan, demonstrated that this proteoglycan present on the cell surface has a heterogeneous size profile with a K(av) value of 0.45, determined by Sepharose CL-4B chromatography. Myoblasts were found to adhere with decreasing affinities to collagen type IV, type I, laminin, fibronectin, perlecan, and matrigel. We found that cell adhesion to collagen type IV was inhibited by blocking this substrate with exogenous perlecan prior to cell plating, whereas no effect was observed for laminin. Furthermore, adhesion of myoblasts to collagen type IV was inhibited by the perlecan core protein obtained by treatment of perlecan with heparitinase, as well as by pre-incubation of the cells with antibodies against murine perlecan. These data support the idea that skeletal muscle cells interact with collagen type IV through the perlecan core protein present on the surface of undifferentiated myoblasts.

Syndecan-1 expression inhibits myoblast differentiation through a basic fibroblast growth factor-dependent mechanism.

Expression of syndecan-1, a cell-surface heparan sulfate proteoglycan, is down-regulated during skeletal muscle differentiation (Larraín, J., Cizmeci-Smith, G., Troncoso, V., Stahl, R. C., Carey, D. J., and Brandan, E. (1997) J. Biol. Chem. 272, 18418-18424). We examined the role of syndecan-1 in basic fibroblast growth factor (bFGF)-dependent inhibition of myogenesis. C2C12 myoblasts were stably transfected with an expression plasmid containing the rat syndecan-1 coding region cDNA. Constitutive syndecan-1 expression resulted in a strongly diminished capacity of the transfected clones to differentiate and to express skeletal muscle-specific markers such as fusion, creatine kinase, and myosin. The expression of myogenin, a master transcription factor for muscle differentiation, was also reduced and delayed. Analysis of the induction of a myogenin promoter-driven reporter revealed that syndecan-1 expression resulted in a 6-7-fold increase in sensitivity to bFGF-dependent inhibition of myogenin expression. Transfecting the cells with a plasmid containing myogenin cDNA reversed the inhibition of myogenin transcriptional activation and myosin expression in syndecan-1-transfected cells; however, cell fusion was not observed. These results demonstrate that syndecan-1 expression enhances cell responsiveness to bFGF and inhibits myoblast fusion and suggest that muscle terminal differentiation is regulated by syndecan-1 expression.

Decorin core protein fragment Leu155-Val260 interacts with TGF-beta but does not compete for decorin binding to type I collagen.

It has been shown that small proteoglycans containing leucine-rich repeats in their core proteins can form complexes with TGF-beta. Decorin, a ubiquitously found molecule of the extracellular matrix, is the best-studied example. Therefore, binding domains on its core protein were investigated using recombinant decorin fragments generated as fusion proteins in prokaryotes. The peptide Leu155-Val260 immobilized by the polyhistidine tag on a nickel chelate column bound TGF-beta1 and -beta2 almost as effectively as the largest fragment (Asp45-Lys359) studied. Other peptides were less effective. For the two peptides Asp45-Lys359 and Leu155-Val260 dissociation constants in the nanomolar range for high-affinity binding sites were calculated in a solid-phase assay with immobilized TGF-beta2. Peptide Asp45-Lys359 also contained a lower affinity binding site. Domains with lower affinity were also found in peptides Asp45-Leu155 and Arg63-Gly190. Peptide Leu155-Val260 also formed complexes with TGF-beta in the liquid phase as determined by equilibrium gel filtration. Furthermore, F(ab') fragments of polyclonal antibodies against peptide Leu155-Val260 interfered with TGF-beta binding to peptide Asp45-Lys359 in a dose-dependent manner. Peptide Leu155-Val260, however, is only a weak competitor of the binding of wild-type decorin to reconstituted type I collagen fibrils. Therefore, independent binding sites of decorin for TGF-beta and type I collagen should exist. In support of this hypothesis saturable binding of TGF-beta1 and TGF-beta2 to collagen-bound native decorin could be demonstrated. The bound cytokine could be released in a biologically active form by collagenase treatment. Thus, decorin may play a biological role in storing this cytokine temporarily in the extracellular matrix and in thereby modulating an interaction of TGF-beta with its signaling receptors.

Expression of perlecan, a proteoglycan that binds myogenic inhibitory basic fibroblast growth factor, is down regulated during skeletal muscle differentiation.

Heparan sulfate proteoglycans (HSPG) have been shown to be involved in the activation of tyrosine kinase receptors by basic fibroblasts growth factor (bFGF), a strong inhibitor of skeletal muscle differentiation. Skeletal muscle fibers contact extracellular matrix (ECM) that surrounds individual fibers (endomysium) and bundles of several fibers (perimysium). Perlecan is a HSPG present in the majority of basement membranes. In this study we evaluated the expression and localization of perlecan during differentiation of C2C12 skeletal muscle cells. C2C12 myoblasts incubated with [35S]Na2SO4 synthesize a HSPG that can be specifically immunoprecipitated with antibodies against murine perlecan. The immunoprecipitated HSPG eluted from a Sepharose CL-4B with a Kav of 0.44. Analysis of the core protein of the HSPG immunoprecipitated from [35S]methionine-labeled C2C12 after treatment with heparitinase revealed two polypeptides of 170 and over 300 kDa. The amount of polypeptides immunoprecipitated decreased with muscle differentiation. Immunocytolocalization studies indicate that perlecan is localized on the myoblast surface and by immunogold staining we have demonstrated that it is associated with patches of incipient extracellular matrix. The expression of perlecan mRNA decreased substantially during skeletal muscle differentiation, in contrast to the increase in transcripts for specific skeletal muscle proteins such as myogenin and creatine kinase. By immunofluorescence microscopy almost no perlecan staining associated with the surface of myotubes was observed. All these results suggests that perlecan, a HSPG that binds myogenic inhibitory bFGF, normally associated with basement membranes in adult tissues is present on the surface of myoblasts and its expression is down regulated during skeletal muscle differentiation.

Ethodin: pharmacological evidence of the interaction between smooth muscle and mast cells in the myometrium.

Ethodin has been used to induce labor through a mechanism that does not involve the estrogen-preparatory process being postulated as necessary for ensuring the events in a normal labor. The cellular mechanisms involved in that process are unknown. We used an isolated organ bath preparation for mouse uterine horns and a primary culture of mouse myometrial smooth muscle cells to analyze the cellular mechanisms involved in the contractile action of this drug in the myometrium. Ethodin at a concentration of 10 microM and Compound 48/80 (1 microg/ml) evoked contractions of uterine horns in an isolated organ bath preparation. Uterine contractile responses showed a transient increase in contractile tension that lasted 2 to 3 min. Tachyphylaxis was observed after four or five successive stimuli, which consisted in additions and washings of the drug at an interval of 10 min. The primary smooth muscle mouse myometrium cells contained a high proportion of relaxed cells that varied widely in length (5-160 microm). Cell lengths decreased in response to the application of serotonin (10 microM) and oxytocin (0.1 microM) but were not affected after the addition of ethodin (10 microM). However, the cells contracted after a purified fraction of mast cells that had been degranulated by the action of the drug ethodin, which was added to the culture medium. These results provide some evidence related to the mechanism of myometrial contractile action of ethodin and support the hypothesis that mast cells may be involved in the regulation of myometrium contractility.

Syndecan-1 expression is down-regulated during myoblast terminal differentiation. Modulation by growth factors and retinoic acid.

Syndecan-1 is an integral membrane proteoglycan involved in the interaction of cells with extracellular matrix proteins and growth factors. It is transiently expressed in several condensing mesenchymal tissues after epithelial induction. In this study we evaluated the expression of syndecan-1 during skeletal muscle differentiation. The expression of syndecan-1 as determined by Northern blot analyses and immunofluorescence microscopy is down-regulated during differentiation. The transcriptional activity of a syndecan-1 promoter construct is also down-regulated in differentiating muscle cells. The decrease in syndecan-1 gene expression is not dependent on the presence of E-boxes, binding sites for the MyoD family of transcription factors in the promoter region, or myogenin expression. Deletion of the region containing the E-boxes or treatment of differentiating cells with sodium butyrate, an inhibitor of myogenin expression, had no effect on syndecan-1 expression. Basic fibroblast growth factor and transforming growth factor type beta, which are inhibitors of myogenesis, had little effect on syndecan-1 expression. When added together, however, they induced syndecan-1 expression. Retinoic acid, an inducer of myogenesis, inhibited syndecan-1 expression and abolished the effect of the growth factors. These results indicate that syndecan-1 expression is down-regulated during myogenesis and that growth factors and retinoic acid modulate syndecan-1 expression by a mechanism that is independent of myogenin.

Interaction between Alzheimer's disease beta A4 precursor protein (APP) and the extracellular matrix: evidence for the participation of heparan sulfate proteoglycans.

The interaction between the Alzheimer amyloid precursor protein (APP) and an intact extracellular matrix (ECM), matrigel, obtained from Engelbreth-Holm-Swarm tumors was evaluated. Based on quantitative analyses of the binding data obtained from solid phase binding assays, two binding sites on the ECM were identified for [125I]-APP (with apparent Kd1 of 1.0 x 10(-11) M and Kd2 of 1.6 x 10(-9) M respectively). Over 70% of [125I]-APP was displaced by heparin and N-desulfated heparin but not by chondroitin sulfate. Pretreatment of matrigel with heparitinase decreased the binding of [125I]-APP by 80%. beta-amyloid peptides (residues 1-40, 1-28, and 1-16) containing a heparin binding domain also displaced 80% of bound [125I]-APP, which was totally displaced by intact APP. The binding of [125I]-APP to matrigel increased by 210% with a decrease in the pH. These observations suggest that [125I]-APP interacts mainly with heparan sulfate proteoglycan present in the ECM. The binding of [125I]-APP to individual ECM components was also analyzed. [125I]-APP was found to bind laminin and collagen type IV but not fibronectin. However, when these ECM constituents were combined, the extent of APP-binding decreased significantly, to levels comparable to those obtained with intact matrigel, suggesting that multiple interactions may occur between ECM constituents and [125I]-APP. The results are discussed in terms of APP function and amyloidogenesis.

Significantly reduced expression of the proteoglycan decorin in Alzheimer's disease fibroblasts.

Aims-To investigate whether proteoglycan synthesis is altered in skin fibroblasts in patients with Alzheimer's disease compared with normal subjects.Methods-Cell lines obtained from donors with Alzheimer's disease and healthy controls were incubated with radioactive sulphate. The proteoglycans synthesised were determined and analysed by chromatographic, sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and glycosaminoglycans-lyase treatment. The amount of decorin synthesised by each cell line was quantified using western blot analysis. Transcripts for human decorin were determined using northern blot analysis.Results-No significant changes in total sulphate incorporation and glycos-aminoglycan (GAG) composition were detected in the incubation media of these cells. However, chromatographic and SDS-PAGE analysis of the proteoglycans secreted by the cell lines showed that a dermatan sulphate proteoglycan of 150-125 kilodaltons was substantially reduced in Alzheimer's disease fibroblasts. The molecular characteristics of this proteoglycan correspond to decorin. Western blot analysis indicated that decorin was reduced in Alzheimer's disease incubation medium compared with normal medium. Northern blotting indicated that in Alzheimer's disease fibroblasts decorin transcripts were significantly reduced compared with normal fibroblasts. Glypican concentrations, a cell surface heparan sulphate proteoglycan, remained the same.Conclusions-These results strongly suggest that the expression and synthesis of decorin is affected in Alzheimer's disease skin fibroblasts.

Synthesis and processing of glypican during differentiation of skeletal muscle cells.

We identified previously a glycosylphosphatidylinositol (GPI)-anchored heparan sulfate proteoglycan (HSPG) releasable by phosphatidylinositol-specific phospholipase C (PI-PLC) on the surface of differentiated skeletal muscle cells (Campos et al., Eur. J. Biochem. 216, 587-595 (1993)) which is homologous to the HSPG synthesized by fibroblasts and Schwann cells called glypican. In this study we have evaluated the processing, location and amount of this HSPG in skeletal muscle cells during differentiation. Immunoprecipitation of incubation medium obtained from differentiated cells incubated with [35S]sulfate by specific antibodies against glypican isolated from Schwann cells demonstrated that the antisera precipitated an intact HSPG. Immunoblot analysis of the proteins released by PI-PLC after heparitinase treatment revealed the presence of a main band of 64 and a faint band of 62 kDa, whereas the sizes of the core proteins for glypican present in the incubation media were 62 and 59 kDa. Pulse-chase experiments indicated that glypican present in the membrane was spontaneously released into the culture medium with a t1/2 of 12 h. The level of expression of glypican was analyzed during in vitro differentiation. The specific amount of the PI-PLC releasable HSPG increased about fourfold during cell differentiation. No changes were detected in the level of the mRNA for glypican. Indirect analysis revealed that in myotubes glypican is present on the cell surface as well as associated with the extracellular matrix (ECM). These results indicate that glypican is present, at least, in two different compartments on the surface of skeletal muscle cells.

Extracellular matrix is required for skeletal muscle differentiation but not myogenin expression.

Skeletal muscle cells are a useful model for studying cell differentiation. Muscle cell differentiation is marked by myoblast proliferation followed by progressive fusion to form large multinucleated myotubes that synthesize muscle-specific proteins and contract spontaneously. The molecular analysis of myogenesis has advanced with the identification of several myogenic regulatory factors, including myod1, myd, and myogenin. These factors regulate each other's expression and that of muscle-specific proteins such as the acetylcholine receptor and acetylcholinesterase (AChE). In order to investigate the role of extracellular matrix (ECM) in myogenesis we have cultured myoblasts (C2C12) in the presence or absence of an exogenous ECM (Matrigel). In addition, we have induced differentiation of myoblasts in the presence or absence of Matrigel and/or chlorate, a specific inhibitor of proteoglycan sulfation. Our results indicated that the formation of fused myotubes and expression of AChE was stimulated by Matrigel. Treatment of myoblasts induced to differentiate with chlorate resulted in an inhibition of cell fusion and AChE activity. Chlorate treatment was also found to inhibit the deposition and assembly of ECM components such fibronectin and laminin. The expression of myogenin mRNA was observed when myoblasts were induced to differentiate, but was unaffected by the presence of Matrigel or by culture of the cells in the presence of chlorate. These results suggest that the expression of myogenin is independent of the presence of ECM, but that the presence of ECM is essential for the formation of myotubes and the expression of later muscle-specific gene products.

Behavioral Responses of Concholepas concholepas (Bruguière, 1789) Larvae to Natural and Artificial Settlement Cues and Microbial Films.

The behavioral responses of veliger larvae of the gastropod Concholepas concholepas were studied in the presence of different natural and artificial settlement cues and microbial films. Early pre-competent larvae stopped swimming, sank (due to ciliary arrests, retraction of the velum into the shell, or both), and remained inactive on the substratum when exposed to conspecific mucus and hemolymph. In both cases the effect was time-dependent and the number of larvae showing these behaviors decreased over time. Larvae exposed to NH4Cl (ammonium ion) showed a similar time- and dose-dependent response. A positive and time-dependent response was also observed when larvae were exposed to different extracellular matrix (ECM) components (i.e., collagen, gelatin, and fibronectin) and sulfated polysaccharides (i.e., carrageenan, heparin, and chondroitin sulfate). In this case the larvae remained attached to the substratum. However, the effect of sulfated polysaccharides on C. concholepas larval behavior was faster than that observed with other ECM molecules. We also studied the responses of premetamorphic C. concholepas larvae exposed to different microbial films. In chemotaxis experiments with different films, with glass as the substratum, larvae showed a significant preference for multispecific and diatoms films. When shells of C. concholepas were used as the substratum, the preference for multispecific films was clear and significant. Likewise, larvae showed velar contractions in the presence of all the films tested. Larvae exposed to multispecific films and to the microalga Prasinocladus marinus showed an increased ciliar movement. The finding that mucus and hemolymph of conspecific adults and ECM molecules (mainly sulfated polysaccharides) induce the cessation of swimming of C. concholepas larvae suggests a possible role for cell-surface receptors in mediating the larval response of marine organisms. Likewise, the positive chemotaxis responses of C. concholepas larvae to different microbial films suggest that microorganisms may have a role in bringing larvae close to settlement inducers on the marine benthos.

Proteoglycans in skeletal muscle.

1. Proteoglycans are macromolecules composed of a protein and one or more chains of sulfated carbohydrates, the glycosaminoglycans. Proteoglycans are found on the cell surface and in the extracellular matrix participating in the cell-cell and cell-extracellular matrix interaction. In this review I present the information accumulated in the past years regarding the presence, characteristics, localization, control of expression and alteration in some pathological states of skeletal muscle proteoglycans. 2. This review presents and discusses current information in this area and some projections for the future in four sections: first, the proteoglycans present in embryonic cells and cell lines from skeletal muscle. Second, the presence of proteoglycans in adult skeletal muscles. Third, the regulation of the expression of skeletal muscle proteoglycans, and fourth, skeletal muscle proteoglycans in pathological conditions.

Proteoglycans in skeletal muscle

1. Proteoglycans are macromolecules composed of a protein and one or mor chains of sulfated carbohydrates, the glycosaminoglycans. Proteoglycans are found on the cell surface and in the extracellular matrix participating in the cell-cell-extracellular matrizx interaction. In this review I present the information accumulated in the past years regarding the presence, characteristics, localization, control of expression and alteration in some pathological states of skeletal muscle proteoglycans. 2. This review presents and discusses current information in this area and some projections for the future in four sections: first, the proteoglycans present in embryonic cells and cell lines from skeletal muscle. Second, the presence of proteoglycans in adult skeletal muscles. Third, the regulation of the expression of skeletal muscle proteoglycans, and fourth, skeletal muscle proteoglycans in pathological conditions