bluuebunny/crossref_metadata_2025_split huggingface dataset:
N‐cadherin mediates sertoli cell‐spermatogenic cell adhesion
Authors: Newton Sean C. , Blaschuk Orest W. , Millette Clarke F. 
Published: February 2005

AbstractThe complex topological association of Sertoli cells and spermatogenic cells in the testis suggests the existence of cell surface adhesion molecules that regulate cellular interactions within the seminiferous epithelium. The recent report of N‐cadherin mRNA expression in the mouse testis implies the involvement of this known adhesion molecule in testicular cell binding. Accordingly, here we report that (1) N‐cadherin is found on the surface membranes of rat spermatogenic cells and on Sertoli cells, and (2) that N‐cadherin is a partial mediator of Sertoli cell‐germ cell adhesion as tested in an in vitro cell‐cell binding assay. Antiserum directed against the N‐cadherin cell adhesion recognition sequence was used for Western blot analysis of purified plasma membranes from Sertoli cells and from spermatogenic cells. Both membrane preparations exhibited reactivity at an appropriate Mr of about 130 kDa. In addition, immunofluorescence assays demonstrated that both germ cells and Sertoli cells were labeled by anti‐N‐cadherin. Finally, the antiserum was included in a cytometer‐assisted cell‐cell binding test to determine its inhibitory ability. The antiserum consistently reduced specific testicular cell‐cell adhesion by 30%–50%. This is the first demonstration that antibodies directed against the cadherin cell adhesion recognition sequence are capable of inhibiting cell‐cell interactions. Pre‐incubation of either rat Sertoli cells or spermatogenic cells alone was sufficient to achieve statistically significant inhibition of intercellular adhesion. We conclude, therefore, that N‐cadherin is expressed by both Sertoli cells and spermatogenic cells and that N‐cadherin is one of a number of regulatory molecules mediating local cellular associations in the mammalian seminiferous tubule. © 1993 Wiley‐Liss, Inc.
Differential expression of thrombospondin 1, 2, and 3 during murine development
Authors: Iruela‐Arispe M. Luisa , Liska DeAnn J. , Sage E. Helene , Bornstein Paul 
Published: February 2005

AbstractThrombospondin 1 is a secreted, trimeric glycoprotein that mediates interactions between cells and extracellular matrix and exhibits cell‐specific effects on migration and proliferation. Recently, two additional thrombospondin genes (thrombospondin 2 and 3) have been identified. To study the functions of these proteins, we have used in situ hybridization and RNAse protection assays to compare the expression of the genes encoding thrombospondin 1, 2, and 3 during murine embryogenesis. Thrombospondin mRNAs were associated with ossification, neuronal organogenesis, and lung development, although transcripts were differentially expressed. Thrombospondin 1 was predominant from days 10 to 13. During this period, high but transient levels of expression were observed in the neural tube, head mesenchyme, and cardiac cushions. In contrast, a more constant level of thrombospondin 1 mRNA was apparent in resident megakaryocytes of the liver, as well as in circulating megakaryocytes; neither thrombospondin 2 nor 3 was detected in these cells. Thrombospondin 1 was also produced by cells of the developing kidney and gut. The expression of thrombospondin 2 was confined principally to organized connective tissue that included pericardium, pleura, perichondrium, periosteum, meninges, ligaments, and reticular dermis. Thrombospondin 2 was also produced by differentiating skeletal myoblasts and by cells of the kidney and gut. Moreover, high levels of expression were detected in blood vessels. Thrombospondin 3 mRNA was restricted to brain, cartilage, and lung. Although thrombospondin 1, 2, and 3 belong to a family of structurally related genes, the differences observed in the spatiotemporal distribution of the corresponding mRNAs indicate unique functions for these secreted proteins. © 1993 Wiley‐Liss, Inc.
Developmental analysis of the external granular layer in the Meander tail mutant mouse: Do cerebellar microneurons have independent progenitors?
Authors: Napieralski Julie A. , Eisenman Leonard M. 
Published: February 2005

AbstractThe cerebellum of the meander tail mutant mouse (mea/mea) is characterized by an apparently normal cytoarchitecture posteriorly with an abrupt transition to an abnormal anterior region. Anteriorly, there is abnormal folition, a drastic reduction in the granule cells (GC) population, disorganization of the Purkinje cells (PC), and a virtual absence of Bergmann glial processes. In this paper we analyze the prenatal and postnatal development of the cerebellum in the mea/mea and attempt to determine the phenotypic onset of the mutation in the anterior region. Hematoxylin and eosin stained sections reveal a morphological difference in the cerebellum of the mea/mea as early as embryonic day 16 characterized by a reduction in the external granule cell layer (EGL). The reduction in the EGL becomes increasingly apparent as development proceeds. This deficit in the EGL most probably results in the absence of GC, but it is unclear at this point whether reduced migration, proliferation, and/or increased cell death is the major factor. Interestingly, immunohistochemical staining with a monoclonal antibody against parvalbumin reveals that the basket and stellate cells, which are also thought to arise from the EGL, are present in the anterior region of the mea/mea cerebellum. These results suggest that the lack of GC in the meander tail is due to an early expressed abnormality of the EGL. However, the presence of the basket and/or stellate cells raises some interesting questions concerning the lineage of the cerebellar microneurons. © 1993 Wiley‐Liss, Inc.
Cellular origin of the dermal‐epidermal basement membrane
Authors: Marinkovich M. Peter , Keene Douglas R. , Rimberg Clytie S. , Burgeson Robert E. 
Published: February 2005

AbstractThe basement membrane underlying epithelium of skin is generally believed to be of epithelial origin, but a mesenchymal contribution to the basement membrane has not been directly examined. The purpose of this study was to directly evaluate both epithelial and mesenchymal contributions to the basement membrane. Fetal bovine keratinocytes cultured on the surface of collagen gels in the absence of fibroblasts did not produce an ultrastructurally recognizable basement membrane; however, when these cells were cultured in the presence of dermal fibroblasts a basement membrane at the keratinocyte‐fibroblast interface was produced after 1 week which was very similar in biochemical composition and ultrastructural appearance to dermal‐epidermal basement membrane in human skin. When dual species cultures of bovine keratinocytes and human fibroblasts were analyzed by indirect immunofluorescent microscopy (IF)1 with human specific antibodies against basement membrane components, dermal fibroblasts were shown to synthesize and deposit type IV collagen, type VII collagen, and laminin in a linear manner into the basement membrane zone. Fetal bovine keratinocytes cultured in the presence or absence of fibroblasts synthesized and deposited type IV collagen, type VII collagen, laminin, K‐laminin, kalinin, and basement membrane associated heparan sulfate proteoglycan (HSPG) into the underlying basement membrane zone. In organ culture, a subpopulation of fibroblasts initially migrating from human foreskin explants was found to stain strongly for types VII and IV collagen and laminin by IF whereas after subculture all cells showed a uniform low staining. Based on these observations we propose that differentiated fibroblasts exist adjacent to epithelial tissues in vivo which produce basement membrane components and assist in basement membrane components and assist in basement membrane assembly. © 1993 Wiley‐Liss, Inc.
Effect of epidermal growth factor on expression of transforming growth factor‐β1 mRNA in stellate reticulum cells of rat mandibular molars
Authors: Lin Fan , Wise Gary E. 
Published: February 2005

AbstractCultured stellate reticulum cells isolated from rat mandibular molars respond to incubation in EGF by increasing their level of expression of TGF‐β1 mRNA. Northern blots showed that incubation in EGF for 6 hours stimulated over a two‐fold increase in TGF‐β1 mRNA in the cells. In contrast, indicating that TGF‐β1 does not have an autocrine effect on these cells. Immunocytochemistry showed that EGF receptor was present on the surface of many but not all of the cultured stellate reticulum cells. Because EGF does stimulate premature eruption of teeth, it is possible that its effect on the stellate reticulum region of the enamel organ would be to stimulate synthesis of TGF‐β1 mRNA which, in turn, could lead to increased synthesis of TGF‐β1 by these cells. The cells do contain the TGF‐β1 protein as revealed by immunocytostaining. The newly synthesized TGF‐β1 may exert its effect on the adjacent dental follicle to either initiate the onset of the cellular events of tooth eruption or to increase the secretion of extracellular matrix proteins by the follicle for formation of the periodontal ligament. © 1993 Wiley‐Liss, Inc.
Expression of Xenopus snail in mesoderm and prospective neural fold ectoderm
Authors: Essex Linda J. , Mayor Roberto , Sargent Michael G. 
Published: February 2005

AbstractExpression of the Xzna gene during Xenopus laevis embryogenesis has been analysed by in situ hybridisation. Like its homologue snail in Drosophila, Xsna is expressed zygotically in all early mesoderm. Expression starts during stage 9 in the dorsal marginal zone and spreads to the ventral side by stage 10. During gastrulation, each cell begins to express as it involutes so that cells newly expressing Xsna are added to the forming mesoderm mantle in an anterior‐to‐posterior progression. Xsna expression is then down‐regulated in a tissue‐specific fashion that reveals the subdivision of the mesoderm before its derivatives are overtly differentiated; e.g., the appearance of the notochord, myotomes, and pronephroi are preceded by the disappearance of Xsna mRNA, while undifferentiated mesoderm remins labelled, even into tadpole stages. Xsna is expressed in the suprablastoporal endoderm during gastrultion and in its derivatives, the prechordal and sub‐notochordal endoderm, during neurulation. Relationships between Xbra, Xtwi and Xsna expression are examined.Xsna is also expressed in the prospective neural fold ectoderm from stage 11 in a low arc above the dorsal marginal zone, precisely identifying a distinct band of cells that surrounds the prospective neural plate that we designate the neural plate border. The anterior transverse neural fold, which becomes forebrain, ceases Xsna expression during neurulation. In the longitudinal neural folds, the deep and superficial ectoderm compartments labelled by Xsna expression are the prospective neural crest and prospective roof of the neural tube, respectively. Xsna expression persists in the neural crest during migration and in some derivatives at least until metamorphosis but ceases in the roof of the neural tube soon after neurulation. © 1993 Wiley‐Liss, Inc.
Collagen type VI in neural crest development: Distribution in situ and interaction with cells in vitro
Authors: Perris Roberto , Kuo Heuy‐Ju , Glanville Robert W. , Bronner‐Fraser Marianne 
Published: February 2005

AbstractWe have examined the spatiotemporal distribution of collagen type VI (Col VI) during neural crest development in vivo and its ability to promote neural crest cell attachment and migration in vitro. An affinity purified antiserum and chain‐specific monoclonal antibodies against chicken Col VI were employed to immunolocalize the collagen in tissue sections and by immunoblotting. At stages of initial neural crest cell migration, the α1(VI) and α2(VI) chains were immunolocalized in apposition with basement membrances of the neural tube, somites, notochord and ectoderm, whereas no immunoreactivity was seen for the α3(VI) chain. Immunoblotting analysis confirmed the expression of α1(VI) and α2(VI) chains and the lack of detectable immunoreactivity for the α3(VI) chain at these early phases of neural crest development. Conversely, at advanced phases of migration and following gangliogenesis, expression of α3(VI) chain coincided with that of α1(VI) and α2(VI) chains in apposition with basement membrances, around the dorsal root ganglia, and in fibrillar arrangements within the developing dermis and ventral sclerotome. The ability of Col VI to promote neural crest cell attachment and migration was tested in vitro using quantitative assays for these processes. Both native microfilaments and isolated tetramers of Col VI strongly promoted neural crest cell attachment and migration. Optimal stimulation of neural crest cell adhesion and migration was dependent upon structural integrity of Col VI since unfolded and disassembled α chains only weakly promoted cell attachment and were virtually inactive in supporting cell movement. The importance of a native macromolecular organization of Col VI further was analyzed in experiments in which dissociated tetramers were reassociated by Ca2+‐ and temperature‐dependent self‐aggregation. In contrast to native microfilaments, these oligomeric complexes were less effective in promoting neural crest cell movement, but still retained the ability to stimulate maximal cell attachment. The results indicate that Col VI is a primary component of the extracellular matrix deposited along neural crest migratory pathways, where it may participate in the regulation of cell movement by functioning as a migratory substrate. The ability of Col VI to promote neural crest cell adhesion and motility is highly dependent upon maintainance of a native macromolecular arrangement. © 1993 Wiley‐Liss, Inc.
Expression of the dystrophin‐related protein (utrophin) gene during mouse embryogenesis
Authors: Schofield Julian , Houzelstein Denis , Davies Kay , Buckingham Margaret , Edwards Yvonne H. 
Published: February 2005

AbstractThe utrophin (UTRN) locus is the autosomal homologue of the DMD (Duchenne muscular dystrophy) gene and encodes a protein, utrophin which is thought to be upregulated in the absence of dystrophin. In this study the spatial and temporal expression of the UTRN gene has been examined during mouse embryogenesis and compared with that of the DMD gene. The patterns of expression of these two genes are very different. Whilst DMD is expressed largely in mesodermal derivatives such as cardiac and striated muscle, UTRN shows a more widespread distribution and is expressed in neural tube, tissues which originate from neural crest and a variety of other sites of non‐neural origin. In early embryos UTRN transcripts initially accumulate in the mid‐neural plate and thereafter in the caudal neural tube. UTRN mRNA then becomes abundant in a subset of neural crest cell derived tissues, in particular the spinal and facial ganglia and ossifying facial cartilages. UTRN is also expressed in a variety of other sites and organs such as the tendon primordia in the digits, the pituitary, thyroid and adrenal glands, cardiac muscle, kidney and lung, follicies of the vibrissae and the outflow tract of the heart. Several patterns of UTRN expression are apparent and we discuss the possibility that these can be ascribed to a family of mRNAs transcribed from the UTRN gene using alternative promoters. © 1993 Wiley‐Liss, Inc.
Pro‐opiomelanocortin gene is expressed in post‐implantation mouse embryos and enhances growth potential of myogenic cells
Authors: De Angelis L. , Cusella‐De Angelis M. G. , Monaco L. , Raschellá G. , Cossu G. 
Published: February 2005

AbstractWe previously showed that the adrenocorticotropin hormone (ACTH) is a mitogen for myoblasts and is present in post‐implantation mammalian embryos (Cossu et al. [1989] Dev. Biol. 131:331–336; De Angelis et al. [1992] Dev. Biol. 151:446–458). In this paper, we investigated the expression of the corresponding gene, pro‐opiomelanocortin (POMC), by in situ hybridization and polymerase chain reaction. In situ analysis revealed low level expression in the basal layer of 10.5 d.p.c. neural tube and in several discrete areas around the dorsal aorta. By more sensitive Reverse‐transcription polymerase chain reaction (RT‐PCR) analysis, expression was detected also in developing limb buds and in cultured myogenic cells, but not in fibroblasts.To investigate the possible role of POMC gene expression in myogenesis, we induced its over‐expression in proliferating myoblasts. Upon sub‐optimal growth conditions, over‐expressing cells were found to give rise to clones larger than control cells. The differentiation potential of POMC over‐expressing myogenic cells was unchanged. © 1993 Wiley‐Liss, Inc.
Restricted expression of Mov13 mutant α1(I) collagen gene in osteoblasts and its consequences for bone development
Authors: Kratochwil Klaus , Ghaffari‐Tabrizi Nassim , Holzinger Ilse , Harbers Klaus 
Published: February 2005

AbstractCell type‐specific differences in the transcriptional control of the mouse gene coding for theα1 chain of collagen type I (Col1a1) have been revealed previously with the help of the Mov13 mouse strain which carries a retroviral insert in the first intron of the gene. Transcription of this mutant Col1a1 allele is completely blocked in all mesodermal cell types tested so far, with the exception of the odontoblast where it is expressed at an apparently normal rate (Kratochwil et al.[1989] Cell 57:807–816). To define the tissue specificity of the mutant allele more precisely, we have now studied its expression in osteoblasts, another skeletogenic cell type which, like odontoblasts, produces high amounts of collagen I. Evidence for transcription of the Mov13 allele was obtained by in situ hybridization in homozygous (M/M) and heterozygous (M/+) bone tissue, in grafts as well as in vivo. The presence of mouse collagen I and the development of bone tissue were demonstrated in M/M skeletal elements grown on the chick chorioallantoic membrane (CAM). Further support for expression of the mutant gene was obtained from two 16 day M/M fetuses in vivo. Bone tissue of diverse embryological origin (vertebrae and ribs of somitic origin, long bones derived from lateral plate, calvariae from head paraxial mesoderm, and mandibulae from head neural crest) expresses the mutant allele. However, in situ hybridization experiments indicate that only a subpopulation of osteoblasts is capable of transcribing it at a high rate, resulting in severe impairment of bone development in grafts and in vivo. Therefore, osteoblasts, in comparison to odontoblasts and fibroblast‐like cells, assume an intermediate position with respect to transcription of the Mov13 allele. We suggest that this diversity in the utilization of the mutant collagen gene reflects cell type‐specific differences in the transcriptional regulation of the wild type (wt) Col1a1 gene. © 1993 Wiley‐Liss, Inc.
Developmental regulation of Islet‐1 mRNA expression during neuronal differentiation in embryonic zebrafish
Authors: Inoue Akihiro , Takahashi Mika , Hatta Kohei , Hotta Yoshiki , Okamoto Hitoshi 
Published: February 2005

AbstractIslet‐1 (Isl‐1) is a LIM domain/homeodomain‐type transcription regulator that has been originally identified as an insulin gene enhancer binding protein. Isl‐1 is also expressed by subsets of neurons in the central nervous system of rat and chick embryos. We have cloned the Isl‐1 cDNA from zebrafish and examined its expression pattern using in situ hybridization to whole‐mount embryos. Isl‐1 mRNA first appears immediately after gastrulation in the polster, the cranial ganglia, and in Rohon‐Beard neurons and ventromedial cells of the spinal cord. The expression by the ventromedial cells is segmentally repeated and becomes restricted to the one or two cells slightly anterior to the segment borders. Double staining by in situ hybridization and an antibody which stains most axons suggested that these segmentally distributed cells may be either the rostral primary motoneuron (RoP) or middle primary motoneuron (MiP). This raises a possibility that Isl‐1 may be involved during determination of subtype identities of the primary motoneurons. Furthermore, the specific Isl‐1 mRNA expression in the spinal cord is under the control of the somites, since mutant embryo with defective somite failed to maintain this pattern. © 1994 Wiley‐Liss, Inc.
Immunolocalization of S‐crystallins in the developing squid (Loligo opalescens) lens
Authors: West Judith A. , Sivak Jacob G. , Pasternak Jack , Piatigorsky Joram 
Published: February 2005

AbstractS‐crystallins are the predominant soluble proteins of the squid lens. Of these, S‐III crystallin is the major component and S‐I and S‐II crystallin are the minor lens components. The lens has a posterior and anterior segment, each derived from separate groups of ectodermal cells referred to as lentigenic cells. In the present study, the appearance of S‐crystallins during the development of the lens of Loligo opalescens was followed by immuno‐cytochemistry. S‐crystallins of the lens and lentigenic cells were first observed at day 17 (Arnold stage 27) of embryogenesis. S‐crystallins were not confined to a single region, but were present in the middle group (group 2) of lentigenic cells, the posterior lens primordium, and the processes connecting the lentigenic cells and the posterior lens primordium. Two days later (Arnold stage 28), the S‐crystallins were also observed in the anterior group (group 1) of lentigenic cells, the anterior lens primordium, and the processes connecting the cells with the anterior lens primordium. Thus, during development, S‐crystallins accumulate first in the posterior lens primordium and subsequently in the anterior lens primordium and their respective lentigenic cells and connecting lentigenic processes. Incubated sections of the adult lens and lentigenic cells also show specific immuno‐peroxidase staining when compared with controls. This evidence in combination with a recent investigation (West [1993] Ph.D. dissertation), which indicates that the cephalopod lens continues to grow throughout adulthood, suggests that squid lens crystallins are synthesized during adulthood. © 1994 Wiley‐Liss, Inc.
Genetics of nanos localization in Drosophila
Authors: Wang Charlotte , Dickinson Laura K. , Lehmann Ruth 
Published: February 2005

AbstractThe Drosophila gene nanos is required for two processes. During oogenesis, nanos function is required for the continued production of egg chambers, and nanos is expressed in the early germarium. During embryogenesis, nanos is required maternally to specify abdominal segmentation. Nanos shares this latter function with nine other genes, collectively known as the posterior group. Of this group, nanos encodes a determinant, and is localized as an RNA to the posterior pole of early embryos. This RNA is translated to form a gradient of nanos protein with highest concentrations at the posterior. Analysis of the distribution of nanos gene products in embryos mutant for posterior group genes shows that eight of these genes are required for localization, but not stability, of the nanos RNA. Embryos mutant for posterior group alleles which produce weak abdominal phenotypes show reduced amounts of localized nanos RNA. This correlation between nanos RNA localization and abdominal phenotype suggests that nanos acts as a localization‐dependent posterior determinant. Localization of nanos is not affected by mutations in bicoid or torso, confirming that the three maternal systems of anterior‐posterior determination initially act independently. © 1994 Wiley‐Liss, Inc.