Directional control and the functional organization of defensive responses inAplysia

Walters, Edgar T.; Erickson, Mark

doi:10.1007/bf00603980

Cited by 83 publications

(72 citation statements)

References 34 publications

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“…Among molluscs, cephalopods have the greatest visual acuity and the fastest locomotion; thus, anti-predator defenses differ from those of other molluscs. For example, the sea hare Aplysia, the subject of many studies of nociceptive sensitization, lacks image-forming eyes so its primary means of defense (directed release of ink, balling up to make grasping more difficult and escape locomotion) usually do not occur until there has been noxious contact with a predator (Nolen et al, 1995;Walters and Erickson, 1986). Physical contact is required for the behavioral expression of tactile sensitization; thus, this form of sensitization necessarily functions during the most vulnerable stage of a predation encounter.…”

Section: Fitness Consequences Of Visual Versus Tactile Sensitization mentioning

confidence: 99%

Peripheral injury induces long-term sensitization of defensive responses to visual and tactile stimuli in the squid Loligo pealeii, Lesueur 1821

Crook

Lewis

Hanlon

et al. 2011

Journal of Experimental Biology

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SUMMARYSurvivable injuries are a common yet costly experience. The ability to sense and respond to noxious stimuli is an almost universal trait, and prolonged behavioral alterations, including sensitization to touch and other stimuli, may function to ameliorate fitness costs associated with injury. Cephalopods can modify their behavior by learned association with noxious electric shock, but nonassociative alterations of behavioral responses after tissue injury have not been studied. The aim of this study was to make the first systematic investigations in any cephalopod of behavioral responses and alterations elicited by explicit, minor injury. By testing responsiveness in the longfin squid, Loligo pealeii, to the approach and contact of an innocuous filament applied to different parts of the body both before and after injury to the distal third of one arm, we show that a cephalopod expresses behavioral alterations persisting for at least 2 days after injury. These alterations parallel forms of nociceptive plasticity in other animals, including general and site-specific sensitization to tactile stimuli. A novel finding is that hyper-responsiveness after injury extends to visual stimuli. Injured squid are more likely to employ crypsis than escape in response to an approaching visual stimulus shortly after injury, but initiate escape earlier and continue escape behaviors for longer when tested from 1 to 48h after injury. Injury failed to elicit overt wound-directed behavior (e.g. grooming) or change hunting success. Our results show that longlasting nociceptive sensitization occurs in cephalopods, and suggest that it may function to reduce predation risk after injury.

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Section: Fitness Consequences Of Visual Versus Tactile Sensitization mentioning

confidence: 99%

Peripheral injury induces long-term sensitization of defensive responses to visual and tactile stimuli in the squid Loligo pealeii, Lesueur 1821

Crook

Lewis

Hanlon

et al. 2011

Journal of Experimental Biology

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“…The name LCM has been used for the analogous muscle of Aplysia (Cook and Carew, 1989;Kuenzi and Carew, 1994), which has also been called the lateral longitudinal muscle (Bablanian et al, 1987). In Aplysia, this muscle mediates the horizontal component of headwaving behavior (Cook and Carew, 1989;Kuenzi and Carew, 1994) and may also mediate, at least partially, appetitive head turning (Teyke et al, 1990) and directional defensive responses (Walters and Erickson, 1986).…”

Section: Longitudinal Muscles Of the Body Wall And Footmentioning

confidence: 99%

Directional Avoidance Turns Encoded by Single Interneurons and Sustained by Multifunctional Serotonergic Cells

Jing

Gillette

2003

J. Neurosci.

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Avoidance turns in the sea slug Pleurobranchaea are responses to noxious stimuli and replace orienting turns to food stimuli after avoidance conditioning or satiation. Avoidance turns proved to be centrally patterned behaviors, the fictive expression of which could be elicited in reduced preparations and the isolated CNS. Activity in one of a bilateral interneuron pair, the A4 cells, was necessary and sufficient to drive the avoidance turn toward the contralateral side. Single A4 cells appeared to encode both turn direction and angle, in contrast to directional behaviors of other animals in which displacement angle is usually encoded by multiple units.The As1-4 cells, bilateral serotonergic cell clusters, excited the prolonged A4 burst during the turn through electrical and chemical coupling. However, during the escape swim, As1-4 became integral elements of the swim motor network, and A4 activity was entrained to the swim rhythm by alternating excitatory-inhibitory inputs, with only weak spiking. This provides a likely mechanism for the previously observed suppression of the avoidance turn by escape swimming. These observations add significant new aspects to the multiplying known functions of As1-4 and their homologs in other molluscs and point to a pivotal role of these neurons in the organization of gastropod behavior.Simple functional models predict (1) the essential actions of inhibitor neurons in the directionality of the turning network motor output and (2) an integrating role for As1-4 in the behavioral switch between turning avoidance and swimming escape, on the basis of their response to increasing stimulus intensity.

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“…The other is opaline, a whitish and extremely viscous substance produced by the opaline gland. These two secretions are released into the mantle cavity -usually, but not always, simultaneously -and pumped out of the siphon toward the attacker (Walters and Erickson, 1986; reviewed by Johnson and Willows, 1999).…”

Section: Introductionmentioning

confidence: 99%

Packaging of chemicals in the defensive secretory glands of the sea hareAplysia californica

Johnson

Kicklighter

Schmidt

et al. 2006

Journal of Experimental Biology

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SUMMARY Sea hares protect themselves from predatory attacks with several modes of chemical defenses. One of these is inking, which is an active release of a protective fluid upon predatory attack. In many sea hares including Aplysia californica and A. dactylomela, this fluid is a mixture of two secretions from two separate glands, usually co-released: ink,a purple fluid from the ink gland; and opaline, a white viscous secretion from the opaline gland. These two secretions are mixed in the mantle cavity and directed toward the attacking predator. Some of the chemicals in these secretions and their mechanism of action have been identified. In our study,we used western blots, immunocytochemistry, amino acid analysis, and bioassays to examine the distribution of these components: (1) an l-amino acid oxidase called escapin for A. californica and dactylomelin-P for A. dactylomela, which has antimicrobial activity but we believe its main function is in defending sea hares against predators that evoke its release; and (2) escapin's major amino acid substrates - l-lysine and l-arginine. Escapin is exclusively produced in the ink gland and is not present in any other tissues or secretions. Furthermore, escapin is only sequestered in the amber vesicles of the ink glandand not in the red-purple vesicles, which contain algal-derived chromophores that give ink its distinctive purple color. The concentration of escapin and dactylomelin-P in ink, both in the gland and after its release, is as high as 2 mg ml-1, or 30 μmol ml-1, which is well above its antimicrobial threshold. Lysine and arginine (and other amino acids) are packaged into vesicles in the ink and opaline glands, but arginine is present in ink and opaline at <1 mmol l-1 and lysine is present in ink at <1 mmol l-1 but in opaline at 65 mmol l-1. Our previous results showed that both lysine and arginine mediate escapin's bacteriostatic effects, but only lysine mediates its bactericidal effects. Given that escapin's antimicrobial effects require concentrations of lysine and/or arginine >1 mmol l-1, our data lead us to conclude that lysine in opaline is the primary natural substrate for escapin in ink. Furthermore, packaging of the enzyme escapin and its substrate lysine into two separate glands and their co-release and mixing at the time of predatory attack allows for the generation of bioactive defensive compounds from innocuous precursors at the precise time they are needed. Whether lysine and/or arginine are substrates for escapin's antipredatory functions remains to be determined.

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Directional control and the functional organization of defensive responses inAplysia

Cited by 83 publications

References 34 publications

Peripheral injury induces long-term sensitization of defensive responses to visual and tactile stimuli in the squid Loligo pealeii, Lesueur 1821

Peripheral injury induces long-term sensitization of defensive responses to visual and tactile stimuli in the squid Loligo pealeii, Lesueur 1821

Directional Avoidance Turns Encoded by Single Interneurons and Sustained by Multifunctional Serotonergic Cells

Packaging of chemicals in the defensive secretory glands of the sea hareAplysia californica

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