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  • 1
    Electronic Resource
    Electronic Resource
    Analysis of transcriptional isoforms of collagen types IX, II, and I in the developing avian cornea by competitive polymerase chain reaction (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Developmental Dynamics 202 (1995), S. 42-53 
    Details
    ISSN: 1058-8388
    Keywords: Tupe IX collagen ; Type II collagen ; Type I collagen ; Cornea ; Quantitative PCR ; mRNA isoforms ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The genes for the α1(IX), α1(IX), α1(II), and α2(I) collagen chains can give rise to different isoforms of mRNA, generated by alternative promoter usage [for α(IX) and α2(I)] or alternative splicing [for α1(II)]. In this study, we employed competitive reverse transcriptase PCR to quantitate the amounts of transcriptional isoforms for these genes in the embryonic avian cornea from its inception (about 3 1/2 days of development) to 11 days. In order to compare values at different time points, the results were normalized to those obtained for the “housekeeping” enzyme, glycerol-3-phosphate dehydrogenase (G3PDH). These values were compared to those obtained from other tissues (anterior optic cup and cartilage) that synthesize different combinations of the collagen isoforms. We found that, in the cornea, transcripts from the upstream promotor of α1(IX) collagen (termed “long IX”) were predominant at stage 18-20 (about 3 1/2 days), but then fell rapidly, and remained at a low level. By 5 days (just before stromal swelling) the major mRNA isoform of α1(IX) was from the downstream promotor (termed “short IX”). The relative amount of transcript for the short form of type IX collagen rose to a peak at about 6 days of development, and then declined. Throughout this period, the predominant transcriptional isoform of the collagen type II gene was IIA (i.e., containing the alternatively spliced exon 2). This indicates that the molecules of type II collagen that are assembled into heterotypic fibrils with type I collagen possess, at least transiently, an amino-terminal globular domain similar to that found in collagen types I, III, and V. For type I, the “bone/tendon” mRNA isoform of the α2(I) collagen gene was predominant; transcripts from the downstream promotor were at basal levels. In other tissues expressing collagen types IX and II, long IX was expressed predominantly with the IIA form in the anterior optic cup at stage 22/23; in 14 1/2 day cartilage, long IX was expressed predominantly along with the IIB form of α1(II). The downstream transcript of the α2(I) gene (Icart) was found at high levels only in cartilage. © 1995 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1002020105
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  • 2
    Electronic Resource
    Electronic Resource
    Notochord of chick embryos secretes short-form type IX collagen prior to the onset of vertebral chondrogenesis (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 194 (1992), S. 169-176 
    Details
    ISSN: 0002-9106
    Keywords: Collagen ; Notochord ; Type II ; Type IX ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The notochord of embryonic chicks produces type IX collagen, as well as type II collagen, prior to the onset of vertebral chondrogenesis. To address the question of whether the notochord secretes the “long-form” type IX collagen found in cartilage or the “short-form” type IX found in the cornea and vitreous humor, we examined immunoreactivity of the notochordal type IX collagen using two different monoclonal antibodies. The antibody 2C2 recognizes an epitope close to the carboxyl-terminus of the HMW fragment, which is present in both the long- and short-form type IX collagens, whereas another antibody 4D6 recognizes an epitope in the NC4 domain of the long-form type IX collagen, which is absent in the short-form type IX collagen. Therefore, the long-form is recognized by its reaction with both 2C2 and 4D6, while the short-form by its reaction with only 2C2 and no reaction with 4D6. Immunostaining of vertebral sections with 2C2 shows an identical distribution of staining with that for type II collagen, although the staining with 2C2 is less intense. The 2C2-reactive type IX collagen is found within the notochord at stage 14 and in the notochordal sheath at stage 20. Deposition of this collagen in the perinotochordal matrix increases with time and reaches a level comparable with that for type II at stage 31. In contrast, the 4D6-reactive type IX collagen is not found within the notochord nor in the notochordal sheath. The collagen becomes detectable, however, in the perinotochordal matrix at stages 27 to 28 and is markedly increased at stage 29, reaching the levels for the 2C2-reactive type IX at stage 31. A highly sensitive immuno-dot blot assay has confirmed that the notochord from chick embryos at stages 19 to 20 produces type IX collagen that reacts with 2C2 but does not react with 4D6. The present study indicates (1) that the short-form type IX collagen is secreted from the notochord and also from the sclerotome cells, and (2) that the switching in the production from the short-form type IX collagen to the long-form type IX occurs during stage 27 and stage 31 when sclerotome cells differentiate into chondrocytes in the developing vertebral body. © 1992 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001940302
    Location Call Number Limitation Availability
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    Paper (German National Licenses)
    Fulltext
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