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M Solursh

Publications and source records attributed to M Solursh.

At least 19 recordsLinked to original sources
PubMed1999

Significant role of adhesion properties of primary osteoblast-like cells in early adhesion events for chondroitin sulfate and dermatan sulfate surface molecules.

The purpose of this study was to characterize the role of cell surface adhesive macromolecules through enzyme modulation and metabolic recovery prior to and during a kinetic cell adhesion assay. Primary rat calvarial osteoblast-like cells were derived from Sprague-Dawley calvarial plates. Cell adhesion kinetics was evaluated with the definition of first-order adhesion kinetics. Osteoblasts were incubated in an adhesion buffer for 1 h prior to a cell attachment assay using various enzymes to remove cell surface glycosaminoglycans (GAGs). A subtractive adhesion analysis was performed by plating cells at 5 x 10(4)/well for variable periods through 2 h. The medium was collected, the well surface washed and pooled, and the number of cells enumerated with a Coulter Counter. Cell adhesion demonstrated first-order logarithmic adhesion kinetics in the first 60 min. Scatchard analysis demonstrated a linear relationship. Preexposure of cells to various enzyme combinations demonstrated that 50% of the equilibrium adhesion was dependent on chondroitin sulfate or dermatan sulfate surface macromolecules. These results were confirmed with pretreatment with a metabolic inhibitor of GAG synthesis (beta-D-xyloside). These results suggest an important role for cell associated chondroitin sulfate and dermatan sulfate in cell adhesion in addition to Arg-Gly-Asp or integrin mediated adhesion events.

Animals↗
PubMed1997

Production of a monoclonal antibody by in vitro immunization that recognizes a native chondroitin sulfate epitope in the embryonic chick limb and heart.

We report the production of a monoclonal antibody (d1C4) by in vitro immunization that has immunoreactivity with a native chondroitin sulfate epitope in embryonic chick limb and heart. Murine lymphocytes were stimulated by direct exposure to unfixed, unsolubilized precartilage mesenchymal aggregates in high-density micromass culture derived from Stage 22-23 chick limb buds. Specificity of d1C4 reactivity was demonstrated by sensitivity of immunohistochemical staining to pretreatment with chondroitinase ABC or AC, preferential immunoreactivity with chondroitin-6-sulfate glycosaminoglycan (CS-C GAG) in ELISA, and competition of immunohistochemical staining with CS-C GAG. Immunohistochemical analysis of the expression of the d1C4 epitope revealed a striking localization of immunoreactivity in the extracellular matrix (ECM) of precartilage aggregates of chick limb mesenchyme in high-density micromass culture by 16 hr and the prechondrogenic limb core at Stage 23 in vivo. Immunoreactivity in both cultured limb mesenchyme and the embryonic limb continued through differentiation of prechondrogenic condensations into cartilage tissue. In the developing chick heart, d1C4 staining was found throughout the ECM of atrioventricular cushion tissue by Stage 25, but was localized to mesenchyme adjacent to the myocardium in the outflow tract cushions. There was an abrupt demarcation between d1C4-reactive intracardiac mesenchyme and unreactive extracardiac mesenchyme of the dorsal mesocardium in the Stage 22 embryo. This study demonstrates the efficacy of in vitro immunization of lymphocytes for the production of MAbs to native ECM constituents, such as CS-GAGs. Immunohistochemical data utilizing d1C4 suggest that CS-GAGs bearing this epitope may be important in early morphogenetic events leading to cartilage differentiation in the limb and valvuloseptal morphogenesis in the heart.

Animals↗
PubMed1997

Comparative analysis of fibrillar and basement membrane collagen expression in embryos of the sea urchin, Strongylocentrotus purpuratus.

The time of appearance and location of three distinct collagen gene transcripts termed 1 alpha, 2 alpha, and 3 alpha, were monitored in the developing S. purpuratus embryo by in situ hybridization. The 1 alpha and 2 alpha transcripts of fibrillar collagens were detected simultaneously in the primary (PMC) and secondary (SMC) mesenchyme cells of the late gastrula stage and subsequently expressed in the spicules and gut associated cells of the pluteus stage. The 3 alpha transcripts of the basement membrane collagen appeared earlier than 1 alpha and 2 alpha, and were first detected in the presumptive PMC at the vegetal plate of the late blastula stage. The PMC exhibited high expression of 3 alpha at the mesenchyme blastula stage, but during gastrulation the level of expression was reduced differentially among the PMC. In the late gastrula and pluteus stages, both PMC and SMC expressed 3 alpha mRNA, and thus at these stages all three collagen genes displayed an identical expression pattern by coincidence. This study thus provides the first survey of onset and localization of multiple collagen transcripts in a single sea urchin species.

Animals↗
PubMed1996

Identification and localization of a novel zinc finger gene in developing chick skin and feather buds.

We have cloned and sequenced a cDNA encoding a novel zinc finger protein (Fzf-1) containing two tandem repeats of zinc finger motifs of the C2H2 type. The cDNA is 3.0 Kb long and has an open reading frame which codes for a protein of 789 amino acids. The expression pattern of the zinc finger gene was studied in chick embryonic skin and feathers by in situ hybridization. The expression of the gene is found to be temporally and spatially regulated. In stage 38 chick embryos, the transcripts are localized to the epidermis but in 10-day-old embryos, the signal is localized to the forming dermis. In 12-day-old chick, the transcripts are localized to the mesenchymal region of the elongated feather buds. Reverse transcription followed by Polymerase Chain Reaction (RT-PCR) did not detect the transcripts in any other tissues.

Amino Acid Sequence↗
PubMed1996

Osteogenic protein-1 is required for mammalian eye development.

Osteogenic Protein-1 (OP-1/BMP-7) is a bone morphogenetic protein in the transforming growth factor-beta superfamily and has been shown to be expressed temporally and spatially during epithelial-mesenchymal interactions mediating tissue morphogenesis in early embryogenesis. In order to identify the primary role(s) for OP-1 in development, we carried out whole rat embryo cultures, over a 72-h period from primitive streak stages to early limb bud stages, in rat sera containing either OP-1 blocking antibodies (10 micrograms/ml) or nonreactive IgG. Rat embryos cultured with control antibodies developed normally, while those cultured with anti-OP-1 antibodies consistently exhibited over-all reduced size and absence of eyes. Histological sections revealed a greater reduction in neural retina development in the embryos treated with anti-OP-1 blocking antibodies. In situ hybridization and immunolocalization analyses indicate that OP-1 is expressed in the neuroepithelium of the optic vesicle at E11.5, is limited to the presumptive neural retina and developing lens placode, and is subsequently expressed in the neural retina, lens and developing cornea at E12.5-E13.5. Our results indicate that OP-1 mediates the inductive signals involved in mammalian eye development.

Animals↗
PubMed1996

Differential displaying of mRNAs from the atrioventricular region of developing chicken hearts at stages 15 and 21.

In an effort to isolate novel genes that may be involved in the development of the cardiac cushions and then the formation of cardiac valves and septa, we utilized the differential mRNA display method in conjunction with the whole-mount in situ hybridization. The total RNAs used to differentially display were prepared from atrioventricular (AV) canal regions of stage 15 and stage 21 chicken hearts because critical events known to be important for the AV valve and septum formation occur during this period of the development. We have successfully obtained 14 potential candidate genes. Three examples, 15H16 (phospholamban), E13 (skeletal alpha-tropomyosin) and 21C (a novel gene), are discussed here. Levels of mRNA expression in developing hearts were determined by Northern blot analysis and their expression patterns were revealed and compared using whole-mount in situ hybridization. Both phospholamban and skeletal alpha-tropomyosin messages in the myocardium of the AV canal region showed significant decrease during this period of the development. The 21C differential display product detects a novel 9.5 Kb message whose expression is cardiac-specific at early stages of development. The expression level of the 21C gene appeared to be increased from stage 15 to stages 21 and 25 as determined by both Northern blot analysis and in situ hybridization. From these data, we demonstrate that the differential display method together with the whole-mount in situ hybridization could be an effective means for the isolation of novel and differentially expressed genes.

Animals↗
PubMed1996

The role of transforming growth factor alpha in rat craniofacial development and chondrogenesis.

To explore the possible role of transforming growth factor alpha (TGF-alpha) in craniofacial development, its expression in the craniofacial region of rat embryos from embryonic day (d) 9 to d 20 was examined by in situ hybridisation and immunostaining. The TGF-alpha transcripts were first detected in the neural fold of embryonic d 9 and 10 embryos. In the craniofacial region, the TGF-alpha transcripts were not detected until embryonic d 16 in mesenchyme surrounding the olfactory bulb, within the olfactory bulb, the nasal capsule, vomeronasal organ, and vibrissal follicle. In addition, TGF-alpha message was detected in mesenchyme in the vicinity of Meckel's cartilage, and in the dental epithelium and lamina. This expression pattern of TGF-alpha transcripts persisted until embryonic d 17 but disappeared by d 18. The presence of TGF-alpha protein largely coincided with TGF-alpha message although, unlike the message, it persisted throughout later embryogenesis in the craniofacial region. The possible function of TGF-alpha in chondrogenesis was explored by employing the micromass culture technique. Cartilage nodule formation in mesenchymal cells cultured from rat mandibles in the presence of TGF-alpha was significantly inhibited. This inhibitory effect of TGF-alpha on chondrogenesis was reversed by addition of antibody against the EGF receptor, which crossreacts with the TGF-alpha receptor. The inhibitory effect of TGF-alpha on chondrogenesis in vitro was further confirmed by micromass culture using mesenchymal cells from rat embryonic limb bud. Taken together, these results demonstrate the involvement of TGF-alpha in chondrogenesis during embryonic development, possibly by way of a specific inhibition of cartilage formation from mesenchymal precursor cells.

Animals↗
PubMed1996

Peripheral nerve extract effects on mesenchymal cells.

Several common congenital limb disorders are characterized by normal tissue differentiation but abnormal somatic growth. These include: idiopathic clubfoot, idiopathic leg length discrepancy, hemi-atrophy and hemi-hypertrophy. Both clinical and research studies have suggested that peripheral nerves may be important in regulating somatic growth of limb tissues. To investigate the hypothesis that peripheral nerves convey trophic substances to mesenchymal tissues that are involved in the regulation of growth, we developed an in vitro assay to assess the effect of fractions of peripheral nerve on myoblast and chondroblast growth and differentiation in a mammalian (rat) system. Whole rat sciatic nerve extract was fractionated by ammonium sulfate precipitation and by affinity chromatography. Concavalin A chromatography resolved whole nerve extract into a glycoprotein and a non-glycoprotein fraction. Serial ammonium sulfate precipitation yielded three pellet fractions designated as 35%, 70%, and 100% pellets; corresponding to ammonium sulfate concentrations of 0 to 35%, 35 to 70%, and 70 to 100% saturation, respectively. Dialyzed solutions of these pellets as well as the fractions from Concavalin A chromatography were assayed for biological activity in micromass cultures of rat limb bud mesenchyme, which allowed assessment of both myoblast and chondroblast stimulation. Stimulation of protein synthesis and myoblast proliferation (as measured by MF20 staining) occurred with both 70% and 100% ammonium sulfate fractions. Stimulation of chondroblasts (as measured by the number of alcian blue staining nodules) occurred with the 35% and 100% fractions. The glycoprotein fraction from the affinity chromatography stimulated protein synthesis and myoblast proliferation and inhibited chondroblast development. Stimulation of chondroblasts was seen with the non-glycoprotein fraction. No effect on protein synthesis, myoblast proliferation or chondroblast proliferation was found in cultures treated with rat transferrin (transferrin has been reported to stimulate myoblasts in avian culture systems).

Ammonium Sulfate↗
PubMed1995

Mirror-image duplication of the primary axis and heart in Xenopus embryos by the overexpression of Msx-1 gene.

The Msx-1 gene (formerly known as Hox-7) is a member of a discrete subclass of homeobox-containing genes. Examination of the expression pattern of Msx-1 in murine and avian embryos suggests that this gene may be involved in the regionalization of the medio-lateral axis during earlier development. We have examined the possible functions of Xenopus Msx-1 during early Xenopus embryonic development by overexpression of the Msx-1 gene. Overexpression of Msx-1 causes a left-right mirror-image duplication of primary axial structures, including notochord, neural tube, somites, suckers, and foregut. The embryonic developing heart is also mirror-image duplicated, including looping directions and polarity. These results indicate that Msx-1 may be involved in the mesoderm formation as well as left-right patterning in the early Xenopus embryonic development.

Animals↗
PubMed1995

Comparative study of Msx-1 expression in early normal and vitamin A-deficient avian embryos.

Homeobox-containing genes may play an important role in establishing embryonic patterns during development of vertebrates. Retinoic acid is able to induce expression of Hox genes in cells in culture and to alter expression patterns in the developing vertebrate embryos. Using wholemount in situ hybridization, we have examined and compared the expression patterns of a homeobox-containing gene, Msx-1, in early normal and vitamin A-deficient quail embryos. At gastrulation stage, Msx-1 is primarily expressed in the posterior half of both normal and vitamin A-deficient embryos. However, the gene is expressed wider and stronger in the vitamin A-deficient embryos. At neurulation stages, Msx-1 is continuously expressed in the posterior region up to Hensen's node and in the edge of the neural fold in both normal and vitamin A-deficient embryos. Notably, in the vitamin A-deficient embryos, Msx-1 is expressed more strongly and is also expressed ectopically in the anterior and precardiac regions. These results provide evidence that endogenous retinoids are involved in the normal expression of Msx-1 in avian embryo and that the expression of Msx-1 is downregulated by endogenous and physiological retinoids in vivo during early avian embryogenesis.

Animals↗
PubMed1995

Relationship between fibronectin expression during gastrulation and heart formation in the rat embryo.

By utilizing myosin immunostaining, we were able to identify early rat myocardium as a thin epithelial sheet and realized that its cohesive movement toward the midline leads to the straight heart tube formation. Localization study of fibronectin mRNA and protein was, therefore, carried out to investigate its tissue origin and possible roles in facilitating mesoderm migration and heart formation. Fibronectin mRNAs were first detected throughout the mesoderm during the early primitive streak stage, suggesting that the mesoderm is the source of fibronectin. By pre-head fold (pre-somite) and head fold (early somite) stages, the mesoderm became largely down-regulated for fibronectin mRNAs, while it was also at these stages when myosin-positive myocardium formed itself into the epithelium and was subsequently folding toward the midline. Thus, there appears to be little fibronectin synthesis during and directly relevant to early heart tube formation. Later, during the early straight heart tube stage (5 somite and older), endocardium became highly positive for fibronectin mRNAs, suggesting that the endocardium is the major source of fibronectin for the cardiac jelly. Based on the results, we present a map for the early mammalian heart in which the heart is a single crescentic band lying in front of the prechordal plate. We also suggest a process for heart tube formation based on the cohesive movement of the myocardial epithelium. During heart tube formation, fibronectin protein had been deposited previously by the mesoderm and was found uniformly in the ECM and not newly produced by any adjacent tissue. The data contradict the endodermal guidance of heart migration by fibronectin gradient and suggest, instead, a permissive role for the fibronectin substrate.

Animals↗
PubMed1995

Phylogenetic conservation and physical mapping of members of the H6 homeobox gene family.

Homeobox genes represent a class of transcription factors that play key roles in the regulation of embryogenesis and development. Here we report the identification of a homeobox-containing gene family that is highly conserved at both the nucleotide and amino acid levels in a diverse number of species. These species encompass both vertebrate and invertebrate phylogenies, ranging from Homo sapiens to Drosophila melanogaster. In humans, at least two homeobox sequences from this family were identified representing a previously reported member of this family as well as a novel homeobox sequence that we physically mapped to the 10q25.2-q26.3 region of human Chromosome (Chr) 10. Multiple members of this family were also detected in three additional vertebrate species including Equus caballus (horse), Gallus gallus (Chicken), and Mus musculus (mouse), whereas only single members were detected in Tripneustes gratilla (sea urchin), Petromyzon marinus (lamprey), Salmo salar (salmon), Ovis aries (sheep), and D. melanogaster (fruit fly).

Amino Acid Sequence↗
PubMed1994

The murine decorin. Complete cDNA cloning, genomic organization, chromosomal assignment, and expression during organogenesis and tissue differentiation.

Decorin, a proteoglycan known to interact with collagen and growth factors, may play key roles during ontogenesis, tissue remodeling, and cancer. We have deciphered the complete protein sequence of the murine decorin by cDNA cloning, elucidated its gene structure and chromosomal location, and investigated its expression in the developing embryo. The decorin protein and the gene were highly conserved vis à vis the human counterpart; however, the murine gene lacked a leader exon, exon Ib, which was found only in the human. Using interspecific backcrossing, we assigned the gene to chromosome 10 just proximally to the Steel gene locus. In situ hybridization studies of developing mouse embryos showed a distinct pattern of expression with a progressive increase of decorin mRNA during ontogenesis. At early stages (day 11 postconception), decorin was detectable only in the floor plate region. Subsequently (days 13-16 postconception), decorin expression was especially prominent in the meninges and mesothelial linings of pericardium, pleura, and coelomic cavity, as well as in the dermis and subepithelial layers of the intestine and urinary bladder. In contrast, the major parenchymal organs were only weakly positive for decorin mRNA. These findings suggest that decorin may play a role in epithelial/mesenchymal interactions during organ development and shaping.

3T3 Cells↗
PubMed1994

Identification of a cell lineage-specific gene coding for a sea urchin alpha 2(IV)-like collagen chain.

We report the isolation of several overlapping cDNAs from an embryonic library of Strongylocentrotus purpuratus coding for a novel sea urchin collagen chain. The conceptual amino acid translation of the cDNAs indicated that the protein displays the structural features of a vertebrate type IV-like collagen alpha chain. In addition to a putative 31-residue signal peptide, the sea urchin molecule contains a 14-residue amino-terminal non-collagenous segment, a discontinuous 1,477-amino acid triple helical domain, and a 225-residue carboxyl-terminal domain rich in cysteines. The amino- and carboxyl-terminal non-collagenous regions of the echinoid molecule are remarkably similar to the 7 S and carboxyl-terminal non-collagenous (NC1) domains of the alpha 1 and alpha 2 chains of vertebrate type IV collagen. The sequence similarity and distinct structural features of the 7 S and NC1 domains strongly suggest that the sea urchin polypeptide is evolutionarily related to the alpha 2(IV) class of collagen chains. Finally, in situ hybridizations revealed that expression of this collagen gene is restricted to the mesenchyme cell lineage of the developing sea urchin embryo.

Amino Acid Sequence↗
PubMed1994

Type II collagen is transiently expressed during avian cardiac valve morphogenesis.

We present new evidence of the temporal and spatial expression of type II collagen in the embryonic chick heart during the very early stages of its development. In particular, we emphasize the distribution of its mRNA and protein during valve formation. Type II collagen as well as several other fibrillar collagens (types I, III, and V) are present in stage 18 endocardial cushion mesenchymal cells. At stage 23, alpha 1 (II) collagen transcripts and the cognate polypeptide colocalize in the atrioventricular valves. As development proceeds, the relative abundance of alpha 1 (II) collagen transcripts decreases during the stages studied (stages 22 to 45; day 3.5 to day 19) as assayed by RNA blotting of extracts of whole hearts. Type II collagen protein was immunologically undetectable in stage 38 (day 12) hearts, although collagens I, III, and V persisted and localize in the valve regions, in the endothelial lining of the heart, and in the epicardium. In keeping with other observations of type II collagen expression in non-chondrogenic regions of a variety of vertebrate embryos, the avian heart also exhibits transient type II collagen expression.

Animals↗
PubMed1994

Elastic extracellular matrix of the embryonic chick heart: an immunohistological study using laser confocal microscopy.

The "elastic matrix" constitutes a specialized component of the extracellular matrix which confers resiliency to tissues and organs subjected to repeated deformations. The role of the elastic matrix in living organisms appears to be of key importance since diseases characterized by expression of defective inherited genes which encode components of the elastic matrix lead to premature death. While the elastic matrix of adult organs has received a great deal of attention, little is known about when it first appears in embryonic tissues or its possible role in developing organs. In the present study we have performed an immunohistochemical study of the distribution of elastin and three additional components often associated with elastic matrices in adult tissues (i.e., fibrillin, emilin, and type VI collagen) during the development of the chicken embryonic heart. The three-dimensional arrangement of these components was established through the observation of whole-amount specimens with scanning laser confocal microscopy. Our results revealed three different periods of heart development regarding the composition of the elastic matrix. Prior to stage 21 the embryonic heart lacks elastin but exhibits a matrix scaffold of fibrillin and emilin associated with the endocardium and the developing cardiac jelly. Between stages 22 and 29 the heart shows a transient elastic scaffold in the outflow tract which contains elastin, fibrillin, and emilin. Elastin-positive fibrillar material is also observed during these stages in the base of the atrioventricular cushion adjacent to the myocardial wall. In addition, emilin-positive material appears to be associated with the zones of formation of ventricular trabeculae. Collagen type VI was not detected during these early stages. From stage 30 to stage 40 a progressive modification of the pattern of distribution of elastin, fibrillin, emilin, and collagen type VI is observed in association with the formation of the definitive four-chambered heart. The distribution of the elastic scaffold in the outflow tract appears to be rearranged and becomes restricted to the roots of the main arteries. Each of the components studied here is also deposited at increasing levels in the developing valvular apparatus including the valve leaflets and the chordae tendinea. The components are also present in the subendocardial space where they form aligned fibrillar tracts, an arrangement suggestive of a role in ventricular contractile function. The epicardium constitutes an additional region of elastic matrix deposition during these later stages and contains elastic, fibrillin, and collagen type VI.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗