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Slow Isoforms (slow + isoform)
Selected AbstractsA new technique, which clearly distinguishes fibre types in fixed muscle tissueNEUROPATHOLOGY & APPLIED NEUROBIOLOGY, Issue 2 2002W. M. H. Behan Aims:, A method of distinguishing between type 1 and 2 skeletal muscle fibres in wax-embedded tissue is needed. The ATPase method is the basis for fibre identification on frozen tissue and a new method should not give significantly different results. Isoforms of myosin and myofibrillar ATPase are known to correlate. Materials and methods:, We devised an immunohistochemical double-labelling (IHC) protocol using monoclonal antibodies to fast and slow myosin. We compared results in the two methods by morphometric analysis of frozen muscle and then applied the method to paraffin-embedded tissue. Results:, On frozen sections there were no significant differences (P = 0.57) in the percentages of type 1 (46% IHC method vs. 48% ATPase) or type 2 fibres (54% vs. 52%) and 2a and 2b subtypes were distinguished easily. Cross-sectional area (in µm2), diameter (µm) and form factor were all similar. Various diagnostic samples of wax embedded tissue were then examined. These gave excellent results with clear colour contrast: type 1 fibres, black and type 2 fibres, red (see examples). Conclusion:, An IHC method based on the fast and slow isoforms of myosin gives similar results to the ATPase method while providing an important advantage in its applicability to wax-embedded muscle. [source] Muscle type-specific effect of myostatin deficiency on myogenic regulatory factor expression in adult double-muscled Japanese Shorthorn cattleANIMAL SCIENCE JOURNAL, Issue 6 2009Susumu MUROYA ABSTRACT To clarify muscle type-specific effect of myostatin on myogenic regulatory factors (MRFs), we examined mRNA expression of MRFs in five skeletal muscles of normal (NM) and myostatin-deficient double-muscled (DM) adult Japanese Shorthorn cattle by quantitative reverse-transcribed PCR. Among the four MRFs, namely, Myf5, MyoD, myogenin, and MRF4, MyoD expression was different among the muscles of the DM cattle (P < 0.01) but not of the NM cattle. Meanwhile, MyoD expression was significantly elevated only in masseter (MS) muscle in the DM cattle due to the myostatin deficiency (P < 0.05). Myf5 and MRF4 expression in semitendinosus (ST) was higher in the DM than in the NM cattle (P < 0.05). According to analysis of myosin heavy chain (MyHC) isoform expression, more MyHC-2x and -2a and less -slow isoforms were expressed in the longissimus and ST muscles compared to the MS muscle in both cattle (P < 0.05), but no significant difference in MyHC expression was observed between the NM and DM cattle. Taken together, myostatin has influences on Myf5 and MRF4 expression in faster-type muscles and on MyoD expression in slower-type muscles, suggesting a possible muscle type-specific effect of myostatin in skeletal muscle growth and maintenance. [source] Human 18 kDa phosphotyrosine protein phosphatase (ACP1) polymorphism: studies of rare variants provide evidence that substitutions within or near alternatively spliced exons affect splicing resultANNALS OF HUMAN GENETICS, Issue 2 2000L. RUDBECK The mammalian low molecular weight phosphotyrosine protein phosphatase is expressed as two distinct isoforms. The human ,fast' and ,slow' isoforms differ only in the sequence of an internal segment of 34 residues, and the ACP1 gene contains two adjacent exons (E3F and E3S) which encode these segments. We have previously suggested that the fast and slow isoforms are generated by mutually exclusive pre-mRNA splicing of E3F and E3S. The common alleles ACP1*A, *B and *C express the fast and slow isoforms in different ratios. The *A and *C alleles differ from *B by C , T transitions in E3S and E3F respectively. To test the idea that the fast:slow ratio is determined by nucleotide substitutions in the E3F-I3F-E3S region, four groups of rare ACP1 variants with unusual fast : slow ratios and the rare *E and *R alleles, expressing fast : slow ratios similar to *C and *B, respectively, were analysed. Gene segments of the I2-I3S region were amplified by PCR and analysed by SSCP and variant bands were excised and sequenced. For each of the rare isozymic variants one of six different nucleotide substitutions in E3F (nts+42, +85, +109, +110), I3F (nt+1) and I3S (nt+8) was observed. The *E and *R alleles showed C and B sequence, respectively, in accordance with the fast : slow ratio. The results support the hypothesis that the fast : slow ratio is constitutive. [source] | ||||||||||