Longitudinal variation in muscle protein expression and contraction kinetics of largemouth bass axial muscle
Tierney M. Thys1,*,
Jason M. Blank2,3,
David J. Coughlin4,
and
Fred Schachat2
1 Department of Zoology, Duke University, Durham, NC 27708, USA;
2 Department of Cell Biology, Duke University, Durham, NC 27710, USA;
3 Hopkins Marine Station, Stanford University, Oceanview Boulevard, Pacific Grove, CA 93950, USA;
4 Department of Biology, Widener University, Chester, PA 19013, USA
* Present address: Sea Studios Foundation, 810 Cannery Row, Monterey, CA 93940, USA
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Fig. 1. Comparison of rostral and caudal arm (A1, A8) and cone (C1, C8) myosin heavy chains (MHC; top). (A) Low percentage (4.75 %) polyacrylamide-SDS gel. There are no readily apparent significant differences between MHC from either the arm and cone sites or the rostral and caudal sites. (B) Cyanogen bromide (CNBr) peptide map comparing proteolytic fragments of rostral arm, cone and mixed samples. There are no readily apparent differences between them.
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Fig. 2. Comparison of longitudinal contractile protein expression of arm sites (A1-A8) with cone sites (C1-C8) (top). (Bottom) 10.5 % polyacrylamide-SDS gels. Note that the protein distributions revealed on the two gels are not significantly different from one another. Both gels, however, do display a similar longitudinal shift in the ratio of TnT-1 to TnT-2. MHC, myosin heavy chain; MLC, myosin light chain; Tm, tropomyosin; TnI, troponin I; TnC, troponin C; TnT, troponin T.
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Fig. 3. (A) 10.5 % SDS gel of rostral (R) and caudal (C) bass myofibrils, demonstrating the position of the troponin proteins relative to the myosin light chains. (B) Tropomyosin purification via hydroxyapatite column chromatography. Note that in the rostral column fraction, the faster migrating isoform, TnT-2, predominates while caudally, the slower migrating isoform, TnT-1, predominates. Abbreviations same as in Fig. 2.
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Fig. 4. Measurement of arm and cone TnT-1 to TnT-2 ratios down the left sides of the body for bass MS01 (240 mm SL), MS02 (224 mm SL) and MS03 (264 mm SL). Note that the arm and cone regions display the same trend: rostral samples (A1–A5 and C6–C8) are composed primarily of TnT-2 while caudal samples (A6–A8 and C6–C8) are composed primarily of TnT-1. The postitions of the samples in the fish are shown at the top.
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Fig. 5. Immunoblot of rostral and caudal arm myofibrillar homogenates revealing parvalbumin. After electrophoresis on 15 % SDS-polyacrylamide gels (A), bass MS02 (224 mm SL) rostral (A1) and caudal (A8) arm myofibrillar homogenates were transferred to nitrocellulose. Monoclonal anti-parvalbumin mouse ascites fluid PA-235 (Sigma 3171) was used to identify parvalbumin in the immunoblot (B). Normalized to actin, the densitometric value of the slower migrating parvalbumin species, parv1, is 21 % greater rostrally than caudally. The faster migrating parvalbumin species, parv2, is 25 % greater rostrally than caudally.
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Fig. 6. Contraction kinetics of largemouth bass white muscle. Time of activation (tA), time of relaxation (tR) and twitch times (tW90 and tW50) are plotted against longitudinal position (see text for definitions). For all four variables, there is a significant effect of position on kinetics, with anterior muscle having the fastest time for activation and relaxation (one-way ANOVA, P<0.01 for the effect of position on each variable).
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© The Company of Biologists Ltd 2001
