Synaptic plasticity and humoral modulation of neuromuscular transmission in the lobster claw opener during the molt cycle

Schwanke, Mary L.; Cobb, J. Stanley; Kass-Simon, G.

doi:10.1016/0742-8413(90)90185-c

Cited by 9 publications

(6 citation statements)

References 40 publications

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“…Over the course of a molt cycle, the pattern of agonistic behavior in lobsters undergoes a marked series of changes-postmolt lobsters are timid and tend to flee; premolt lobsters are aggressive and tend to fight (Herrick, 1909;Tamm and Cobb, 1978). Consistent with these findings are the studies by Schwanke et al (1990) and Cromarty and Kass-Simon (1998); when pre-molt hemolymph was perfused over the dactyl opener of the claw of intermolt lobsters, there was an increase in the amplitude of excitatory junctional potentials (EJPs) as well as a decrease in the amplitude of inhibitory junctional potentials (IJPs) (Schwanke et al, 1990). In order to establish whether 20E played a specific role in such changes, Cromarty and Kass-Simon (1998) bathed the abdominal flexor muscle and dactyl opener muscle of intermolt lobsters with 20E.…”

Section: Introductionsupporting

confidence: 75%

Exposure to the steroid hormone 20-hydroxyecdysone modulates agonistic interactions in male Homarus americanus

Reinhart

Cromarty

Sipala

et al. 2012

Hormones and Behavior

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Section: Introductionsupporting

confidence: 75%

Exposure to the steroid hormone 20-hydroxyecdysone modulates agonistic interactions in male Homarus americanus

Reinhart

Cromarty

Sipala

et al. 2012

Hormones and Behavior

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“…One of the effects of 20-hydroxyecdysone is to increase the amplitude of excitatory junctional potentials at the claw opener muscle used in aggressive displays [Cromarty et al, 1998]. This is the same effect that we have found to be produced by haemolymph drawn from premolt animals [Schwanke et al, 1990].…”

Section: Discussionsupporting

confidence: 62%

“…Other physiological changes that vary over the molt cycle that have the effect of enhancing an individual animal's aggressiveness just prior to molt and, thus, increase its chances of survival include inherently larger excitatory junctional potentials and smaller inhibitory junctional potentials at the claw opener muscles [Schwanke et al, 1990], and larger excitatory junctional potentials in abdominal muscles [Cromarty and Kass-Simon, 1996] in premolt lobsters.…”

Section: Discussionmentioning

confidence: 99%

Increased aggressiveness in gravid American lobsters, Homarus americanus

Mello¹,

Cromarty²,

Kass‐Simon³

1999

Aggr. Behav.

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Reports in the literature suggest that gravid female lobsters (Homarus americanus) are more aggressive than non-gravid female lobsters. In an earlier study [Cromarty SI et al. 1998. Biol Bull 194:63-71], we showed that, with one exception, gravid females did not respond to an unfamiliar stimulus with escape swimming. Here we present quantitative evidence showing that gravid female lobsters are more aggressive than non-gravid females. Gravid and non-gravid females were allowed to fight against larger, non-gravid female opponents in an enclosed arena. The videotaped behaviors were ranked in a behavioral hierarchy (Rank of Aggression) according to their degree of aggressiveness and intensity. The behaviors were classified and ranked as follows: (1) aggression toward opponent, (2) redirected aggressive behavior (toward arena wall), (3) redirected defensive behavior, (4) defensive behavior against opponent, and (5) avoidance behavior.Gravid lobsters performed more behaviors and more aggressive behaviors than did non-gravid controls. The behaviors of gravid females ranked higher on the Rank of Aggression scale than did non-gravid females. The opponents of gravid females performed more aggressive and more intensely aggressive acts than the opponents of nongravid females; they also performed more defensive acts (i.e., those used to ward off an opponent's attack) than did their non-gravid opponents, although there were no differences in intensity of defensive behaviors between gravid and non-gravid animals. There were no significant differences in the number of avoidance behaviors among the four types of combatants (gravid, non-gravid, gravid opponent, and non-gravid opponent), and none in avoidance tailflipping. However, gravid females were more likely to perform aggressive tailflips and performed significantly more aggressive tailflips than non-gravid animals. Together, this suggests that any physiological inhibition of escape swimming may have been overcome by the heightened intensity of gravid fights and the increased aggressiveness of gravid animals. Aggr. Behav. 25:451-472, 1999.

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“…Other factors such as central (Kravitz et al, 1984;Kravitz, 1988;Yeh et al, 1996Yeh et al, , 1997Hörner et al, 1997) and peripheral modulations (Kravitz et al, 1980;Kravitz, 1990;Schwanke et al, 1990) are likely to affect molt-cycle behavior. We have recently found that 20-hydroxyecdysone (20-HE), the active steroid regulating the molt, also alters the neuromuscular properties of the claw-opener and phasic flexor systems in intermolt animals (Cromarty, 1995;, in a way that is consistent with molt-determined behavioral differences (Tamm and Cobb, 1978;Cromarty et al, 1991).…”

Section: Discussionmentioning

confidence: 99%

Molt-related and size-dependent differences in the escape response and post-threat behavior of the American lobster, Homarus americanus

Cromarty

Mello

Kass-Simon

2000

The Biological Bulletin

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Videotaped recordings of adult lobsters of different molt stages were analyzed. The escape response of adults was compared with that of juveniles recorded in an earlier study. Juvenile lobsters always respond to a threat with escape behavior irrespective of their molt stage, but in adults the probability of eliciting a response was a function of molt stage: more hard-shelled (intermolt stage C) and (premolt stage D) animals tailflipped than did soft-shelled (postmolt stages A and B) animals. The number, frequency, and duration of tailflips, and the average distance swum by animals in each molt stage were measured for the entire escape response, for the initial power swim, and for the subsequent swims. These measurements were used to compute several parameters: velocity, acceleration, force, and work; average distance traveled in a tailflip for each kilogram of body weight (distance/kg/tailflip); and average distance traveled for each bodylength (distance/bodylength). Among adults, intermolt (stage C) lobsters traveled significantly farther and faster than postmolt animals (stages A and B). Among juveniles, late postmolt (stage B) animals traveled farther. Among adults, although the total number of tailflips and the duration of the response were not significantly different among molt stages, the number of tailflips/second (frequency) and distance traveled/kg/tailflip were greater for intermolt animals. In juvenile intermolts, however, frequency and distance/kg/tailflip were markedly lower than in the premolt stages. Although values were lower than intermolts and premolts, postmolt adults sustained their swimming frequency, distance/kg/tailflip, and distance/bodylength for the entire escape distance (as did postmolt juveniles). These parameters then dropped off sharply for both adult and juvenile intermolt and premolt animals in the second half of the escape distance. Post-threat behaviors reveal that stage D animals have the highest aggression index and often attack the presented stimulus, whereas stage A animals are the least likely to approach the stimulus and typically back away in a non-aggressive posture. Thus, although effects of the molt cycle on adult and juvenile escape behavior are similar in some ways, other physical characteristics of adults, such as weight, allometry, and physiology, seem to become important in determining the likelihood of escape behavior and the characteristics of the escape swim in each molt stage.

show abstract

Synaptic plasticity and humoral modulation of neuromuscular transmission in the lobster claw opener during the molt cycle

Cited by 9 publications

References 40 publications

Exposure to the steroid hormone 20-hydroxyecdysone modulates agonistic interactions in male Homarus americanus

Exposure to the steroid hormone 20-hydroxyecdysone modulates agonistic interactions in male Homarus americanus

Increased aggressiveness in gravid American lobsters, Homarus americanus

Molt-related and size-dependent differences in the escape response and post-threat behavior of the American lobster, Homarus americanus

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