Differences in motor output and fiber composition of the opener muscle in lobster dimorphic claws

✍ Scribed by Govind, C. K. ;Stephens, Philip J. ;Trinkaus-Randall, V.

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 726 KB
• Volume: 218
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402180307

✦ Synopsis

Abstract

The structural and biochemical properties of the opener muscle and the impulse pattern of its single excitatory motoneuron differed between the paired cutter and crusher claws in the lobster, Homarus americanus. The soma of the opener excitor (OE) motoneuron was physiologically identified in an isolated claw‐ganglion preparation and its responsiveness to sensory stimulation of the first and second nerve roots monitored. The OE soma to the crusher claw had a higher spike frequency and burst duration than its counterpart to the cutter claw. The OE axon to the cutter claw fatigues much more readily than that to the crusher claw at 50 and 100 Hz stimulation in isolated claws. The mean sarcomere length of 8 and 10μm, in fibers of the cutter and crusher opener muscles was significantly different. The electrophoretic pattern of myosin extracted from the cutter opener muscle revealed four bands not found in the crusher opener muscle and a single band in the crusher not seen in the cutter. Thus properties of the opener muscle and its motoneuron differ on the two sides in keeping with the dimorphic nature of the claws.