First published online June 13, 2008
Journal of Experimental Biology 211, 2172-2184 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.016592
Expression of myogenic regulatory factors in the muscle-derived electric organ of Sternopygus macrurus
Jung A. Kim1,*,
Christine Laney1,
Jeanne Curry2 and
Graciela A. Unguez1,
1 Department of Biology, New Mexico State University, Las Cruces, NM 88003,
USA
2 Department of Agronomy and Horticulture, New Mexico State University, Las
Cruces, NM 88003, USA

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Fig. 1. Sequence comparison of the deduced proteins encoded by S. macrurus
myf5 with comparable sequences from mouse (A) and other piscine species
(B). Protein sequences from mouse (M. musculus, GenBank accession
number NP_032682.1), carp (C. carpio, GenBank accession number
BAA33566), zebrafish (D. rerio, GenBank accession number
NP_571651.1), striped seabass (M. saxitilis, GenBank accession number
AF463525_1), rainbow trout (O. mykiss, GenBank accession number
AAV30214) and pufferfish (T. rubripes, GenBank accession number
CAC39208.1) were used. The boxed areas are labeled to indicate the N-terminal,
His/Cys-rich, basic helix-loop-helix (bHLH) and helix III domains. Asterisks
represent amino acid similarities across sequences.
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Fig. 2. Sequence comparison of the deduced protein encoded by S. macrurus
MRF4 with comparable sequences from mouse (A) and other piscine species
(B). Sequences from mouse (M. musculus, GenBank accession number
1604247A), zebrafish (D. rerio, GenBank accession number AAQ67704)
and puffer fish (T. rubripes, GenBank accession number AAR20812) were
used. The boxed areas are labeled to indicate the N-terminal, the
His/Cys-rich, bHLH and Helix III domains. Asterisks represent amino acid
similarities across sequences.
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Fig. 3. Expression of MyoD, myogenin, myf5 and MRF4 transcripts
in adult tissues of S. macrurus by RT-PCR analysis. Total RNAs from
skeletal muscle, EO, liver and brain were reverse transcribed and used for
PCR. PCR products (1.0 µg per lane) were resolved on agarose gels
containing ethidium bromide, and the resultant bands are presented as negative
images of the original gels. Partial cDNA fragments of MyoD (290 bp),
myogenin (312 bp), myf5 (209 bp) and MRF4 (301 bp)
were detected in skeletal muscle and EO, but not in liver or brain. Control
reactions without reverse transcriptase (No RT lanes) were carried out for
muscle (lane 2), EO (lane 4), liver (lane 6) and brain (lane 8) to ensure that
PCR products were RNA dependent and not the result of genomic DNA
amplification. RT-PCR analysis of glyceraldehyde dehydrogenase (GAPDH) was
used as a loading control. Lanes labelled M represent the 1 kb+ DNA
ladder.
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Fig. 5. Expression of Id1, Id2 and MEF2C in adult tissues of
S. macrurus by RT-PCR. Agarose gel showing the expression of partial
Id1 (304 bp), Id2 (101 bp) and MEF2C (265 bp) cDNA
fragments in skeletal muscle, EO, liver, brain and heart of S.
macrurus using RT-PCR. For each transcript, 1 µg of cDNA was used for
the PCR amplification. RT-PCR analysis of GAPDH was used as a loading control.
Lanes labeled M represent the 1 kb+ or 25 bp (Id2) DNA
ladder. Other lanes as in Fig.
3.
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Fig. 6. Expression of Id1, Id2 and MEF2C in adult and 5
week ST muscle and EO by RT-PCR. Agarose gel showing the expression of
Id1, Id2 and MEF2C in skeletal muscle and EO from
control un-operated and 5 week ST fish using RT-PCR. Id1,
Id2 and MEF2C transcripts were detected in all tissues
analyzed. The size of the cDNA fragments for each transcript was the same as
that in Fig. 5; 1 µg of cDNA
was used for PCR amplification. RT-PCR analysis of GAPDH was used as a loading
control. Lanes labeled M represent the 1 kb+ or 25 bp
(Id2) DNA ladder. Other lanes as in
Fig. 3.
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Fig. 7. Genomic Southern blot analysis of the MyoD, myogenin, myf5 and
MRF4 genes. Genomic DNA prepared from S. macrurus adults was
digested with BamHI (lane 1), EcoRI (lane 2),
HindIII (lane 3), BamHI/EcoRI (lane 4),
BamHI/HindIII (lane 5) and EcoRI/HindIII (lane 6), resolved
by 1% agarose gel electrophoresis, and transferred to a nylon membrane.
Genomic DNA was loaded at 5 µg per lane. Blots were hybridized with
32P-labeled probes specific to S. macrurus MyoD,
myogenin, myf5 and MRF4, and washed under high
stringency conditions.
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© The Company of Biologists Ltd 2008