Species-specific Defense Research Articles

Associative learning in the box jellyfish Tripedalia cystophora

Associative learning, such as classical or operant conditioning, has never been unequivocally associated with animals outside bilatarians, e.g., vertebrates, arthropods, or mollusks. Learning modulates behavior and is imperative for survival in the vast majority of animals. Obstacle avoidance is one of several visually guided behaviors in the box jellyfish, Tripedalia cystophora Conant, 1897 (Cnidaria: Cubozoa), and it is intimately associated with foraging between prop roots in their mangrove habitat. The obstacle avoidance behavior (OAB) is a species-specific defense reaction (SSDR) for T.cystophora, so identifying such SSDR is essential for testing the learning capacity of a given animal. Using the OAB, we show that box jellyfish performed associative learning (operant conditioning). We found that the rhopalial nervous system is the learning center and that T.cystophora combines visual and mechanical stimuli during operant conditioning. Since T.cystophora has a dispersed central nervous system lacking a conventional centralized brain, ourwork challenges the notion that associative learning requires complex neuronal circuitry. Moreover, since Cnidaria is the sister group to Bilateria, it suggests the intriguing possibility that advanced neuronal processes, like operant conditioning, are a fundamental property of all nervous systems.

Social Behavior Deficiencies in Captive American Alligators (Alligator mississippiensis)

Understanding how the behavior of captive American alligator (Alligator mississippiensis) congregations compares to wild congregations is essential to assessing the welfare of alligators in captivity. Wild alligator congregations perform complex social behaviors, but it is unknown if such behaviors occur in captive congregations as frequently. We observed the behaviors of a captive and wild congregation of American alligators in Florida, USA in January 2021. Social behaviors were, on average, 827% more frequent in the wild congregation than the captive, and the wild congregation had a richer repertoire of social behaviors, with growling and HOTA (head oblique tail arched) behaviors being particularly common. High walking, a nonsocial behavior, dominated the behavioral repertoire of the captive congregation (94% of behaviors, excluding feeding) and may be a stereotypy that can be used as an indicator of welfare. Both congregations experienced human disturbance and displayed flushing as a species-specific defense reaction. Captive environments differ from the wild with respect to size, structure, stocking density, resource availability, and human presence. These differences translate into behavioral differences between wild and captive congregations. We identified important behavioral differences between wild and captive alligator congregations that can serve as a platform for more detailed investigations of alligator welfare in captivity.

Chemical signature of Eurois occulta L. outbreaks in the xylem cell wall of Salix glauca L. in Greenland

Insect defoliations are a major natural disturbance in high-latitude ecosystems and are expected to increase in frequency and severity due to current climatic change. Defoliations cause severe reductions in biomass and carbon investments that affect the functioning and productivity of tundra ecosystems. Here we combined dendro-anatomical analysis with chemical imaging to investigate the direct and lagged effects of insect outbreaks on carbon investment.We analysed the content of lignin vs. holocellulose, i.e. unspecified carbohydrates in xylem samples of Salix glauca L. collected at Iffiartarfik, Nuuk fjord, Greenland, featuring two outbreak events of the moth Eurois occulta L. Cross sections of the growth rings corresponding to both outbreaks ±3 years were analysed using confocal Raman imaging to identify possible chemical signatures related to insect defoliation on fibres, vessels, and ray parenchyma cells and to get insight into species-specific defence responses.Outbreak years with narrower rings and thinner fibre cell walls are accompanied by a change in the content of cell-wall polymers but not their underlying chemistry. Indeed, during the outbreaks the ratio between lignin and carbohydrates significantly increased in fibre but not vessel cell walls due to an increase in lignin content coupled with a reduced content of carbohydrates. Parenchyma cell walls and cell corners did not show any significant changes in the cell-wall biopolymer content.The selective adjustment of the cell-wall composition of fibres but not vessels under stressful conditions could be related to the plants priority to maintain an efficient hydraulic system rather than mechanical support. However, the higher lignin content of fibre cell walls formed during the outbreak events could increase mechanical stiffness to the thin walls by optimizing the available resources.Chemical analysis of xylem traits with Raman imaging is a promising approach to highlight hidden effects of defoliation otherwise overlooked with classical dendroecological methods.

Feeding performance of fleas on different host species: is phylogenetic distance between hosts important?

We asked if and how feeding performance of fleas on an auxiliary host is affected by the phylogenetic distance between this host and the principal host of a flea. We investigated the feeding of 2 flea species, Parapulex chephrenis and Xenopsylla ramesis, on a principal (Acomys cahirinus and Meriones crassus, respectively) and 8 auxiliary host species. We predicted that fleas would perform better (higher proportion of fleas would feed and take larger bloodmeals) on (a) a principal rather than an auxiliary host and (b) auxiliary hosts phylogenetically closer to a principal host. Although feeding performance of fleas differed among different hosts, we found that: (1) fleas did not always perform better on a principal host than on an auxiliary host; and (2) flea performance on an auxiliary host was not negatively correlated with phylogenetic distance of this host from the principal host. In some cases, fleas fed better on hosts that were phylogenetically distant from their principal host. We concluded that variation in flea feeding performance among host species results from interplay between (a) inherent species-specific host defence abilities, (b) inherent species-specific flea abilities to withstand host defences and (c) evolutionary tightness of association between a particular host species and a particular flea species.

A transcriptional profile of metallophyte Viola baoshanensis involved in general and species-specific cadmium-defense mechanisms

Viola baoshanensis Shu, Liu et Lan is a newly identified metallophyte, and its defensive strategies against heavy metals are still unclear. In the present study, we firstly constructed a root cDNA library of the plant subjected to 300muM Cd for 48h by using suppression subtractive hybridization (SSH), and 43 unique cDNA fragments were further isolated from the library. Sequence homology analysis showed that half of the identified genes were involved in general stress defense, such as antioxidative enzymes, protein degradation and stress signal transduction. After RT-PCR and RACE analysis, a Cd-responsive gene Vb40 was identified, which could deduce a novel cysteine-rich mini-protein. Meanwhile, five cyclotide precursor genes (VbCP1-VbCP5) were also identified. The Vb40 and the VbCP1-VbCP5 were further investigated by yeast expression analysis, and they could improve copper (Cu) tolerance in hosted yeast, indicating that these species-specific genes possibly functioned in V. baoshanensis heavy metals tolerance. Our results suggested that heavy metal tolerance in V. baoshanensis relied on both general and species-specific defense.

Plant species specific defense signal communication differentially regulates glutathione S-transferase activity and gene expression in the Helicoverpa armigera (Hubner)

Plants produce a wide variety of secondary compounds that serve as defensive agents against herbivores. In response to plant defenses, herbivores increase their production of enzymes that detoxify allelochemicals, including Glutathione S-transferases (GST). Glutathione S-transferases in insects play an important role in the detoxification of many substances including allelochemicals from plants and are involved in the adaptation of insects to host plants. In previous studies, we found that plant defense signal communication is species specific between tomato and tobacco plants. In this study, the results showed that the species special defense signal communication differentially regulated glutathione S-transferases gene expression and enzymatic activity in the Cotton bollworm Helicoverpa armigera (Hubner). In the tomato system, the glutathione S-transferases activity and gene expression in the cotton bollworm reared on the tomato is stronger than that reared on the tobacco; in the tobacco system, the glutathione S-transferases activity and gene expression in the cotton bollworm reared on the tobacco is stronger than that reared on the tomato. The results could help us better understand the delicate and profound interaction and inter-adaptation between insects and plants.

Defensive aspects of burrowing behavior in rats (Rattus Norvegicus): A descriptive and correlational study

Several burrowing behavioral characteristics of five different, genetically-biased, strains of rats ( Rattus norvegicus), with each showing various defensive and open-field behaviors, were investigated to examine the defensive aspects of burrowing behavior. The strains used were the Tsukuba High- and Low-Emotional (THE and TLE), F344/DuCrj (F344), Long Evans (LE), and the Wistar-Imamichi/lar (WI). The THE and LE strains showed significantly shorter burrowing latency, more digging activity, and longer length burrows, with most rats escaping into their burrows at a loud crash sound. On the other hand, the TLE and WI stains displayed significantly longer burrowing latency, less digging activity, and shorter length burrows, with only a few rats escaping. These findings showed the consistency among the burrowing characteristics and a close relationship between burrowing and escape. The F344 strain, on the contrary, showed a shorter burrowing latency and more digging activity than the TLE and WI strains (although similar length burrows), yet few rats escaped. Digging, burying, open-field defecation, and re-emergency latency after escape correlated highly with each other, possibly suggesting their defensive nature. In conclusion, it is possible that burrowing behavior is a species-specific defense reaction (SSDR), yet factors involved in burrowing seem to be complicated, with more extensive studies therefore required.

Projections from the periaqueductal gray (PAG) to the periambigual area: Relation to cholinergic vago-cardiac neurons

Activation of the midbrain periaqueductal gray (PAG) elicits species specific defense reactions and marked autonomic adjustments. In agreement with recent studies by Bandler and colleagues in the cat, we found that activation of rostrocaudally-oriented, longitudinally organized columns in PAG elicit differential cardiovascular and behavioral responses. Activation of dorsolateral/lateral PAG produces aggressive/flight behaviors accompanied by pressor responses while stimulation of ventrolateral PAG produces immobility and depressor responses. The pathways mediating these selective behavioral and autonomic responses are poorly understood.The projection from PAG to the sympathoexcitatory zone in the rostral ventrolateral medulla is a likely substrate for PAG-evoked pressor responses. However, circuits mediating PAG-evoked depressor responses are not known. The present studies have identified a robust, focal projection from PAG to the nucleus ambiguus (NA), a potent depressor area in the ventral medulla. In addition, we have used tract tracing techniques and immunocytochemistry to examine the organization of PAG projections in relation to cholinergic preganglionic parasympathetic NA neurons that innervate the heart.

Cross-generalization between an ecologically relevant stimulus and a pentylenetetrazole-discriminative cue

Twelve male Sprague-Dawley rats were trained in a two-choice pentylenetetrazole vs. saline drug discrimination (DD) task under an FR10 schedule of food reinforcement. Two-minute reinforced test sessions with the two training stimuli engendered exclusive injection-appropriate responding. Rats were injected with saline and then exposed for 20 min to the presence of a domestic cat pretreated with catnip. Immediately following the predator exposure, rats were tested for stimulus generalization in the DD task. The predator/prey interaction engendered 92% PTZ-appropriate responding. These data suggest that the interoceptive state associated with species-specific defense reactions in rats is similar to the cues produced by a pharmacological agent within a behavioral assay which has been suggested as an animal model of human anxiety.

The avoidance barpress problem: Effects of enhanced reinforcement and an SSDR-congruent lever

Four experiments addressed the unresolved problem of signaled avoidance barpress learning in the rat. The role of two variables was investigated. Reinforcement: whether or not the subject entered a safe compartment immediately after an escape or avoidance barpress. Because the subjects were automatically displaced back to the danger compartment for the start of a new trial, the task was a one-way barpress. Congruity between the location of the lever and the subject's species-specific defense reactions: This variable was manipulated in two ways. These were whether the lever was mounted near the chamber's top opening or at a much lower level, and whether the lever was adjacent to a safe place or away from it. The results indicated that each variable plays a crucial role, and a combination of the two variables eliminates the usual barpress avoidance difficulty.

Reinforcement versus species-specific defense reactions as determinants of avoidance barpressing.

Reinforcement versus species-specific defense reactions as determinants of avoidance barpressing.

Reinforcement versus species-specific defense reactions as determinants of avoidance barpressing.

Reinforcement versus species-specific defense reactions as determinants of avoidance barpressing.

A rapidly acquired one-way conditioned avoidance procedure in rats as a primary screening test for antipsychotics: influence of shock intensity on avoidance performance

Antipsychotics selectively disrupt relatively weak responses maintained by conditioned stimuli compared with stronger responses maintained by unconditioned stimuli. The present study describes an easily taught and rapidly acquired (within one 15-trial session) one-way conditioned avoidance procedure for rats suitable for screening of drugs for potential antipsychotic activity. This was achieved by using an easily acquired response (running, part of the species-specific defense reaction repertoire), a clearly discriminated conditioned stimulus and determination of the appropriate strength of the unconditioned stimulus (i.e. shock level) for this procedure. Behavior acquired under these described conditions resulted in stable performance over long retest periods. By using either a low or high intensity of shock level under which the animals were trained and tested, the difference between the dose of haloperidol and chlorpromazine able to disrupt avoidance and that which disrupted escape response rates was increased. This effect was also observed for morphine, which inhibited both avoidance and escape responses at similar dose levels only under low shock conditions. At a high shock condition morphine more selectively inhibited avoidance responding. Diazepam did not affect avoidance behavior under the conditions described here.

Durational Control of Defensive Burying in Rats: An Investigation of a Species-Specific Defense Reaction

Durational Control of Defensive Burying in Rats: An Investigation of a Species-Specific Defense Reaction

Barpress escape responses in the rat: A topographic analysis

By means of stroboscopic photography, barpress escape learning by rats was studied using two different schedules of negative reinforcement: fixed ratio 1 and variable ratio 2.5. The results showed two different topographies of barpressing: with FR-1, the rat hit the bar with the foreleg in an intentional movement; however, when the schedule was changed, the response of the rat changed to a series of jumps on the bar. These results bear on the relation between the theory of species-specific defense reactions and escape behavior.

The Effects of Shock Intensity and Respose-Shock Interval upon Avoidance Learning of Rats in a Rotating Cage

Compared to lever-press avoidance learning, easy and quick learning is expected when a running response which is a part of the “Species-specific defense reactions (SSDRs)” (1) i.e., fleeing, is used as an avoidance response (4, 5). However, even in the running-wheel situation, some rats were discarded due to failure to respond (2). Rats might avoid a shock by crouching to the same pole of the grid, because a nonscrambled shock generated by a slipring commutator was used. This suggested the possibility of promoting avoidance learning if a scrambled shock is introduced. However, such studies using a running response in a rotating cage have been little attempted, because of the complexity of the mechanism to transmit a scrambled shock to the rotating grid.Recently, ISO (3) attempted to improve the rotating cage, and reported effective Sidman-avoidance learnings in rats. A newly designed shock-transmitter mechanism was attached to the cage, and the scrambled shock was delivered on the grid. In the three experiments, response-shock (R-S) interval was 20 sec, shock-shock (S-S) interval was 5 sec, a shock duration was 0.5 sec and the shock intensity was 200 V AC. Then, in experiment 1, the magnitude of rotation to be counted as a response was tested in three times of 1 hr sessions. Rats learned more quickly in a quarter turn condition than a half condition. In experiment 2, the maintenance of learning over sessions was tested. Rats showed some superior maintenance of avoidance response without over-night decrement for consecutive 8 days. In experiment 3, the continuation of avoidance responses through a long session was examined. Avoidance responses were continued until the end of the session over 6 hours, and rats ran a mean of 1544 m with a mean of 42 shocks during 6 hours. Such results indicated the utility of the rotating cage for the avoidance learning in rats.Then, in the present experiment, the effects of shock intensity and R-S interval which are the basic variables to affect the avoidance learning, on Sidman-avoidance learning in rats are tested using the same apparatus as ISO (3).Sidman-avoidance learning of Wistar rats as a function of shock intensities (100, 200 and 300 V AC) and response-shock (R-S) intervals (10 and 20 sec) was examined in a newly designed rotating cage [ISO (3)]. The shock-shock (S-S) interval was fixed at 5 sec with a shock duration of 0.5 sec. One habituation, two avoidance trainings and one extinction were continued for one hour each. Such sessions were split weekly. All the rats learned avoidance responses easily, especially well in the condition of 20 sec R-S interval with a shock intensity of 200 V.

Naloxone, preshock, and defensive burying.

Rats were injected with naloxone hydrochloride (3 mg/kg) or saline and subjected to preshock or no preshock prior to receiving a test shock that elicited defensive burying. Preshock was administered in a context different from, or the same as, that in which the test shock was delivered. The combination of naloxone and preshock led to more defensive burying than did saline and preshock. This was the case regardless of preshock context, a result suggesting that fear and/or analgesia may not always be critical ingredients in the preshock-naloxone interaction. Interpretative matters notwithstanding, the pattern of results for defensive burying was in basic agreement with that of other research on naloxone and defensive behavior and represents an extension of the literature to a new species-specific defense reaction.

Shuttlebox avoidance programs for the 6502

Two programs were written in assembly language for the 6502 microprocessor to control a wide variety of learning procedures for a shuttlebox. Both programs can control two shuttleboxes simultaneously. The first program includes routines for the traditional discrete-trial avoidance procedures, including operant level (CS only), avoidance, punishment, and Pavlovian conditioning (US presentation independent of the response). Session parameters (number of trials, durations of the CS, US, and IT!) may be set over a wide range of values, and response-contingent CS termination is an option. Session-identification data, the latency of the first response on each trial, and the total number of intertrial responses are both printed and stored in memory. Latencies, rather than just the occurrence of a response, are measured. Bolles (1979) argued that the failure of the response latencies to change over time is evidence that the animal is showing a species-specific defense reaction rather than avoidance learning. The second program controls the linear presentation procedure described by Zerbolio (1981). This method was developed with the thought that the traditional shuttlebox avoidance procedures do not provide unambiguous evidence for the acquisition of a discriminated avoidance response in goldfish. In the typical avoidance learning experiment, an increase in response rate is taken as evidence for learning. Goldfish present a problem in that they are known to increase their rate of responding not only in the situation in which there is response-contingent shockomission, but also under a large variety of procedures, including no US presentation (Steiner, 1971) and Pavlovian procedures (Woodard & Bitterman, 1971). Zerbolio's procedure provides a parallel to the response requirements of a Y maze. In the shuttlebox, each trial begins with a trial-start stimulus. If the fish responds, by shuttling to the other end of the tank, either an S+ or an Sstimulus is presented on a randomized basis. Ifthe fish makes additional responses on this trial, the S+ and Sstimuli alternate. At the end of the trial, the fish receives the US if the trial-start or S stimuli are in effect. To avoid the

Avoidance, classical, and pseudoconditioning as a function of species-specific defense reactions in high- and low-avoider rat strains

Rats of the Australian High Avoider (AHA) and Australian Low Avoider (ALA) strains and their reciprocal crosses were exposed to 50 trials of one of three shuttlebox procedures. The avoidance group received pairings of a tone and shock. If the animals shuttled during the tone, they avoided the shock. If they waited until the shock came on, they could then escape it. The classical group received pairings of the tone and a brief inescapable shock. If they shuttled during the tone, the tone ceased and they immediately received the shock. If they did not shuttle, they received the brief shock at the termination of the tone. The pseudoconditioning group received the tone and the shock explicitly unpaired. If they shuttled during either the tone or the shock, the stimulus was terminated. There was no acquisition of anticipatory responding under the pseudoconditioning procedure. All groups evidenced an increase in anticipatory responding over trials under the classical procedure. The AHAs acquired the response faster and reached a higher asymptote than did the ALAs. Performance of the two reciprocal crosses fell in between. A similar pattern was observed under the avoidance procedure, albeit at slightly higher response levels. Subsequent studies established that the AHAs acquired a one-way avoidance response quickly, but were impaired on a passive avoidance task, whereas the reverse was the case for the ALAs. The reciprocal crosses were proficient at both tasks. These results suggest that shuttlebox avoidance is largely accounted for by classical conditioning of the predominant defensive response. When that response is compatible with performance on the task, acquisition is rapid (AHAs), and when it is not, acquisition is slow (ALAs).

Shock-induced analgesia on the formalin test: effects of shock severity, naloxone, hypophysectomy, and associative variables.

Rats were exposed to three shocks, spaced 20 s apart, at two different levels of severity, low (.75 s, 1 mA) and high (3 s, 4 mA). Both shock levels produced a similar suppression of the recuperative behavior elicited by an injection of formalin into a rat's hind paw. Naloxone fully reversed the analgesia produced by the low-severity shock but only partially reversed the analgesia produced by the high-severity shock (Experiment 1). Hypophysectomy did not alter the level of analgesia (Experiment 2). When the rats were tested in a chamber different from the one they were shocked in, both analgesias were totally reversed (Experiment 3). However, imposing a delay between shock and analgesia testing did not reduce analgesia (Experiment 4). These results suggest that analgesia is not directly elicited by the shock but by apparatus stimuli associated with shock. Further support for this position was obtained when it was found that a Pavlovian extinction procedure could completely eliminate analgesia (Experiment 5). In all of the experiments, the freezing response, one of the rat's species-specific defense reactions, was monitored simultaneously with recuperative behavior. A parallel was found between analgesia and this defensive response, a result suggesting that an animal's endogenous analgesic systems may be activated along with the animal's defensive motivational system. The results point to the critical nature of associative variables in the control of endogenous analgesic systems. They also suggest that shock severity is a determinant of analgesia's sensitivity to naloxone.