QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 4, 2005
Journal of Experimental Biology 208, 4243-4253 (2005)
Published by The Company of Biologists 2005
doi: 10.1242/jeb.01904

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Toniolo, L. Articles by Reggiani, C. Search for Related Content PubMed PubMed Citation Articles by Toniolo, L. Articles by Reggiani, C.

Expression of eight distinct MHC isoforms in bovine striated muscles: evidence for MHC-2B presence only in extraocular muscles

L. Toniolo¹, L. Maccatrozzo², M. Patruno², F. Caliaro², F. Mascarello^2,* and C. Reggiani¹

¹ Dipartimento di Anatomia e Fisiologia Umana, Università di Padova, Italy
² Dipartimento di Scienze Sperimentali Veterinarie, Università di Padova, Italy

View larger version (64K): [in a new window]   Fig. 1. MHC isoform expression in bovine muscles. (A) Electrophoretic separation of MHC isoforms in various adult bovine muscles: M, masseter; D, diaphragm; Ld, longissimus dorsi; Ecr, extensor carpi radialis; P, pectoralis; Rb, retractor bulbi; Rl, rectus lateralis. (B) RT-PCR analysis of MHC isoform expression in the same muscles as in A. S, size standard. (C) Electrophoretic separation of MHC isoforms in foetal diaphragm (D-f) compared with adult masseter and longissimus dorsi muscle.

View larger version (19K): [in a new window]   Fig. 2. Electrophoretic analysis of the expression of and ß MHC isoforms in atrial myocardium (A), ventricular myocardium (V) and masseter (M).

View larger version (76K): [in a new window]   Fig. 3. Immunohistochemistry on a composite block of longissimus dorsi (Ld) and rectus lateralis (Rl) muscles. Serial sections are stained with anti-neonatal MHC (a), anti-2B MHC (b) and anti-extraocular MHC (c) antibodies. In one skeletal muscle (Ld), all fibres are negative whereas in extraocular muscle (Rl) some fibres are positive to the antibodies tested. The `hybrid' fibres are numerous and positive either to all antibodies (asterisk) or to two of them (circle); only a few fibres are `pure' and positive with anti-2B MHC antibody (hash mark). Scale bar, 100 µm.

View larger version (59K): [in a new window]   Fig. 4. MHC isoform expression in bundles of fibres from rectus lateralis (7Rl) and from retractor bulbi (7Rb, 10Rb) and in two larger samples of retractor bulbi muscle (Rb). The same MHC isoforms were detected by RT-PCR (A) and SDS-PAGE (B). Two samples of Rb are shown because it is not possible to detect all six bands in the same sample due to the different proportion of each isoform and to the distribution of the isoforms inside the muscle. S, size standards.

View larger version (45K): [in a new window]   Fig. 5. MHC isoform expression in bovine laryngeal muscles. (A) RT-PCR using specific primers for MHC-2B, MHC-Eo and MHC-Neo. (B) Electrophoretic separation of MHC isoforms; the migration order is (from top to bottom): MHC-2A, MHC-Emb, MHC-2X and MHC-Neo (comigration), MHC-2B, MHC-1. Cd, cricoarytenoideus dorsalis; At, arytenoideus transverses; T, thyreoarytenoideus [Tvr, Tvc (pars rostralis and caudalis of ventricular part) and Tvo (pars vocalis)]; Rb, retractor bulbi (used as a control; note that MHC-1 is not detectable in this sample).

View larger version (31K): [in a new window]   Fig. 6. Single fibre analysis in bovine masseter. (A) Distribution of maximum shortening velocity (v0) values of 35 fibres isolated from masseter and studied for their mechanical properties and their MHC isoform composition. Each dot corresponds to a single fibre: first column shows all fibres together; second column shows fibres expressing only MHC-ß/slow; third column shows fibres also expressing MHC-. (B) Examples of electrophoretic separation of MHC isoforms in bovine masseter fibres: S-F, single fibre; V, ventricular myocardium (expressing MHC-ß); A, atrial myocardium (expressing mainly MHC-).

View larger version (14K): [in a new window]   Fig. 7. Mean values (+ S.E.M.) of cross-sectional area (A), isometric tension (B) and maximum shortening velocity (C) in five fibre types from bovine muscles. Variance analysis showed that (1) cross-sectional area values of 2A and 2X fibres were significantly different from those of type 1, 1-2A and fibres, (2) isometric tension of 1 and types was significantly different from that of 1-2A, 2A and 2X, (3) maximum shortening velocity values of each fibre type were significantly different from those of all other types, except and 1-2A.

View larger version (27K): [in a new window]   Fig. 8. Interspecies variations of maximum shortening velocity (v0) and isometric tension (P0). (A) Relationship between v0 (expressed in µm hs-1 s-1, where hs is half sarcomere, for correct comparison among species) and body size. (B) Values of P0 measured in various fibre types in six animal species. Data for mouse, rat, rabbit and human come from Pellegrino et al. (2003); data for pig come from Toniolo et al. (2004).