Inter-Individual and Inter-Strain Variations in Zebrafish Locomotor Ontogeny

Zebrafish exhibit remarkable alterations in behaviour and morphology as they develop from early larval stages to mature adults. In this study we compare the locomotion parameters of six common zebrafish strains from two different laboratories to determine the stability and repeatability of these behaviours. Our results demonstrate large variability in locomotion and fast swim events between strains and between laboratories across time. These data highlight the necessity for careful, strain-specific controls when analysing locomotor phenotypes and open up the possibility of standardising the quantification of zebrafish behaviour at multiple life stages.     

Circadian Locomotor Activity Rhythm During Ontogeny in Crayfish Procambarus Clarkii

The characteristics of the circadian rhythm of locomotor activity in the crayfish Procambarus clarkii during ontogeny under constant darkness and light-dark (LD 12:12) conditions were studied in 132 juvenile crayfish, aged 10-140 days, divided in four groups. All animals were individually monitored with a motor activity recording system. Activity was quantitatively and qualitatively analyzed. All ages showed a circadian rhythm, although the probability of its appearance increased with age. Period values oscillated between 25.0 h in group I (2-4-week-old animals) and 24.3 h in group IV (16-20-week-old animals with more than 6 molts), but always with a high standard deviation. Groups II (5-10-week-old animals) and IV showed a statistically significant bimodal nonrandom synchrony of phases. The activity/ rest relationship diminishes as development progresses and is most uniform in group IV. We discuss the possibility that the pacemaker system responsible for this rhythm might be present from the moment of eclosion, but the coupling strength of this system with the effectors might change along development. The results presented in this work seem to indicate that the central pacemakers responsible for the activity and the ERG rhythm are not the same.     

The Hormonal Control of Ultrasonic Communication in Rodents

SYNOPSIS. The production of high-frequency vocalizations duringsexual and agonistic interactions is widespread among rodents.The ubiquity of these signals suggests that they play importantroles as social communications in rodent reproduction and populationregulation. Furthermore, the consistent association of "ultrasound"production with hormone-dependent sexual andagonistic behaviorssuggests that hormones help to coordinate this form of communicationwith other behavioral and physiological preparations for reproduction.Experiments testing this hypothesis have shown clearly thatultrasound rates depend on gonadal hormones. In addition, theability of animals to elicit ultrasounds from conspecifics,and their inclination to respond to conspecific ultrasounds,both seem to depend on pituitary or gonadal hormones. This varietyof types of hormonal effects on ultrasonic communication increasesthe extent to which these signals can be integrated with stimuliof other modalities in hormone-dependent chains of communicationscontrolling reproductive success.     

Effects of Substantia Nigra Lesions on the Locomotor and Stereotypy Responses to Amphetamine

IT is usually supposed that amphetamine produces behavioural effects which include an increase of spontaneous motor activity and the elicitation of stereotyped behaviours¹, by causing a release of endogenous catecholamines in the central nervous system². This view is, for example, supported by the observation that amphetamine can release the catecholamines noradrenaline (NA) and dopamine (DA) from the central nervous system in vitro² and in vivo^{3, 4} and that inhibition of catecholamine biosynthesis blocks the amphetamine effect⁵. Anatomical studies of the distribution of neurones containing catecholamine however, raise, questions about the general applicability of this hypothesis⁶.     

Importance of Nest Predation by Alien Rodents and Avian Poxvirus in Conservation of Oahu Elepaio

ABSTRACT The Oahu elepaio (Chasiempis sandwichensis ibidis) is an endangered forest bird endemic to the Hawaiian island of Oahu (USA) and is threatened by nest predation from alien rodents and mosquito-borne diseases. I investigated importance of these threats and evaluated success of conservation efforts from 1995 to 2008. I controlled rodents with snap-traps and bait stations in 3 valleys and switched sites from non-treatment to treatment over time. I mist-netted and color-banded 91 elepaio, inspected them for symptoms of avian poxvirus (Poxvirus avium), and estimated survival using multistate mark-recapture models. I determined annual fecundity of each breeding pair and monitored success of 212 nests. The oldest known Oahu elepaio was ≥15 years old. Survival of females was higher with rodent control (0.82 ± 0.05) than without (0.55 ± 0.12), but survival of males was not affected by rodent control (0.86 ± 0.02 with vs. 0.84 ± 0.04 without). Survival of elepaio with active or inactive pox-like lesions was 4–10% lower than survival of elepaio with no pox symptoms. Rodent control resulted in higher annual fecundity (0.69 ± 0.05 vs. 0.33 ± 0.06 fledglings/pair) and nest success (62% vs. 33%). Female site-fidelity, mate fidelity, and female encounter probability were lower in the absence of rodent control because more females switched territories and mates after nest failure. Population growth calculated from survival and fecundity estimates was stable with rodent control (1.07 ± 0.04) but declining without rodent control (0.69 ± 0.05). Elepaio numbers have continued to decline despite rodent control, probably because some young birds disperse into adjacent unmanaged areas that act as sinks. The best immediate management strategy for Oahu elepaio is to conduct rodent control over larger areas. Restoration of native forest would benefit elepaio by providing nest sites that are less attractive to rodents. Construction of predator-proof fences and eradication of predators would provide the best long-term protection for elepaio.     

German Yellowjacket (Vespula germanica) Foragers Use Odors Inside the Nest to Find Carbohydrate Food Sources

Prior work has shown that yellowjacket waSPS remember food odors and use them as cues when foraging. There is also evidence they have mechanisms to recruit nest mates to highly rewarding food sources, as naïve individuals are more likely to go to food sources with scents similar to those visited by nest mates. We asked whether recruitment requires behavioral stimulation by returning foragers, as in honey bees, or if sampling the food source inside the nest is sufficient. We tested this by eliminating the behavior of returning foragers by inserting a scented sugar solution directly into a Vespula germanica nest. Exiting foragers were given a choice of the test scent and a control scent. WaSPS were more likely to choose the test scent. We conclude that behavioral interactions with returning foragers are not necessary to stimulate nest mates to associate an odor with a food source and search for a resource bearing that odor, and that experience with the scented reward inside the nest is sufficient to achieve this result.     

Pest Responses to Odors From Predators Fed a Diet of Target Species Conspecifics and Heterospecifics

ABSTRACT Research into the use of predator-odor-based repellents as a management tool has gained momentum during the past 30 years. Some studies have suggested that odors from a predator whose diet includes the target species are more effective than odors from a predator that does not consume the species. To evaluate this management tool in the Australian context and to determine the effect, if any, of predator diet on odor repellence, we tested eutherian and metatherian, predator fecal odors on phylogenetically separated pest species that currently occur in Australia. We evaluated fecal odors from tigers (Panthera tigris) and Tasmanian devils (Sarcophilus harrisii) as repellents for goats (Capra hircus) and eastern grey kangaroos (Macropus giganteus). We fed tigers and Tasmanian devils 2 diets: one of goat and one of eastern grey kangaroo. The test fecal odors were more effective than a control odor of carrier material and solvent at deterring goats (P < 0.001) and kangaroos (P = 0.02) from food. Tiger fecal odor was more effective than Tasmanian devil odor in deterring both goats (P = 0.001)and kangaroos (P = 0.03). We observed a decrease in the number of feeding events for goats when they were exposed to the odor from a tiger fed goat compared with all other predator-diet combinations (P < 0.001). We also observed a decrease in feeding events for kangaroos when exposed to the odor from a tiger fed kangaroo compared with all other predator-diet combinations. We observed signs of desensitization to the test odors in goats and habituation to the test odors in kangaroos over the experimental period. A better understanding of the factors involved in desensitization and habituation may increase the effectiveness of fecal odor-based repellents as a humane and nonlethal management tool for managers.     

Olfactory and Thermal Influences on Ultrasonic Vocalization During Development in Rodents

Ultrasounds are emitted by developing rodents, and changes withage in several parameters of vocalization have been reportedfor numerous myomorphs. In this paper I integrate with ultrasonicvocalization several behaviors which change during development.Included are studies controlling stimulation by olfactory, thermal,and tactile cues as well as detailed studies of specific responsessuch as movement, suckling, grooming, and huddling. Developmentis analyzed in well-known species, such as the rat (Rattus norvegicus),and in less familiar species, especially the pine vole (Microtuspinetorum). Lacking the capacity for physiological thermoregulation, altricialrodent pups with their mother use several behavioral strategieswhich facilitate thermoregulation. Inside the nest, pups adjustthe temperature by changing their huddling. The mother regulatesthe length of suckling bouts according to her body temperature.When a pup is removed from the warm nest, vocalizations of thepup can increase the likelihood of retrieval by the mother andthereby indirectly facilitate thermoregulation. In several species which have been studied, vocalization ratesare highest when pups begin to move into and out of nests andexhibit olfactory-directed movement. As olfactory preferencesbecome established and movement is coordinated, a decline invocalization appears in rat, mouse, hamster, spiny mouse, andpine vole. In the gerbil, however, the decline precedes competencein olfactory-directed movement. In the presence of home shavings, young rats emit low ratesof vocalization, while pine vole young emit calls at a highrate. This contrast may relate to the intensive attachment ofyoung pine voles to the mother in early life.     

The Ontogeny of Social Behaviour in Four Conilurine Rodents (Muridae) of Australia

This paper describes the ontogeny of social behaviour in 4 closely related rodents from diverse habitats. These rodents, Notomys alexis, Pseudomys albocinereus, P. shortridgei and P. desertor exemplify 4 different social organizations. The young were observed daily under semi-natural conditions until weaning, and subsequently at intervals of one week until sexual maturity. Relationships between the young and their families were determined from the relative frequencies of attracting (amicable) and repelling (agonistic) behaviour. The social behaviour of the young is correlated with the social behaviour of adults. Social interactions experienced from birth throughout sub-adulthood appear to prepare these species for their adult social life.     

Ontogeny of the Locomotor Activity Rhythm in the Common Marmoset (Callithrix jacchus)

The ontogeny of locomotor activity rhythm in the common marmoset was studied in three animals, observed during infant and juvenile stages, and in adult age. Animals were kept with their families in outdoor cages under natural temperature, humidity and light cycles. Data were collected from sunrise to sunset, three consecutive days a week, at 5 min intervals randomly distributed in the clock hours, and were recorded as the total of arbitrary cage sections traveled by the animal each interval. Animal 3 was observed continuously one day a week in order to detect less than 2 h period harmonic components. Animals' weekly data series were analyzed by Fourier analysis and Siegel's test to detect significant harmonic components. Results showed a main 24 h period com ponent for all records and a secondary 8 h period component in at least 34% of animal's week data series. The power content of the 24 h component showed an increase with age, reaching some stability near the 16th week of life suggesting that this component is mature at the end of the animal's infant stage. However, for the 8 h component an oscillating pattern was observed following the environmental annual temperature cycle; this may indicate a seasonal modulation of daily locomotor activity profiles.     

Ontogeny of the Locomotor Activity Rhythm in the Common Marmoset (Callithrix jacchus)

The ontogeny of locomotor activity rhythm in the common marmoset was studied in three animals, observed during infant and juvenile stages, and in adult age. Animals were kept with their families in outdoor cages under natural temperature, humidity and light cycles. Data were collected from sunrise to sunset, three consecutive days a week, at 5 min intervals randomly distributed in the clock hours, and were recorded as the total of arbitrary cage sections traveled by the animal each interval. Animal 3 was observed continuously one day a week in order to detect less than 2 h period harmonic components. Animals' weekly data series were analyzed by Fourier analysis and Siegel's test to detect significant harmonic components. Results showed a main 24 h period com ponent for all records and a secondary 8 h period component in at least 34% of animal's week data series. The power content of the 24 h component showed an increase with age, reaching some stability near the 16th week of life suggesting that this component is mature at the end of the animal's infant stage. However, for the 8 h component an oscillating pattern was observed following the environmental annual temperature cycle; this may indicate a seasonal modulation of daily locomotor activity profiles.     

Responses of the Circadian Locomotor Activity Rhythm of Mus Booduga to Shifts in LD Schedules

The responses of the field mouse Mus booduga to shifts in schedules of LD cycles were monitored and the results were interpreted with the help of a PRC constructed for the same species. The results reveal that, M. booduga reentrained faster with a lesser number of transients after delay shifts than advance shifts, thus exhibiting “asymmetry effect.” A positive correlation was observed between the number of transients and the number of hours of shift. In most of the shifts, the sign of the transients (negative for delaying transients and positive for advancing transients) coincided with the direction of the shift. Interestingly, 11 and 12 h of advance shifting resulted in delaying transients. An 11-h advance shift can also be interpreted as a 13-h delay. Reentrainment through delaying transients is faster as compared to reentrainment through advancing transients. Thus, this animal might have taken a “shorter route,” as proved by the fact that an 11-h advance shift has evoked delaying transients. But a 13-h advance shift evoked only advancing transients. This prompts us to speculate that there may be a “phase jump” in M. booduga. Further, irrespective of whether L or D has been doubled in a 12-h shift, both evoked only delaying transients.     

Meal Duration as a Measure of Orofacial Nociceptive Responses in Rodents

A lengthening in meal duration can be used to measure an increase in orofacial mechanical hyperalgesia having similarities to the guarding behavior of humans with orofacial pain. To measure meal duration unrestrained rats are continuously kept in sound attenuated, computerized feeding modules for days to weeks to record feeding behavior. These sound-attenuated chambers are equipped with chow pellet dispensers. The dispenser has a pellet trough with a photobeam placed at the bottom of the trough and when a rodent removes a pellet from the feeder trough this beam is no longer blocked, signaling the computer to drop another pellet. The computer records the date and time when the pellets were taken from the trough and from this data the experimenter can calculate the meal parameters. When calculating meal parameters a meal was defined based on previous work and was set at 10 min (in other words when the animal does not eat for 10 min that would be the end of the animal''s meal) also the minimum meal size was set at 3 pellets. The meal duration, meal number, food intake, meal size and inter-meal interval can then be calculated by the software for any time period that the operator desires. Of the feeding parameters that can be calculated meal duration has been shown to be a continuous noninvasive biological marker of orofacial nociception in male rats and mice and female rats. Meal duration measurements are quantitative, require no training or animal manipulation, require cortical participation, and do not compete with other experimentally induced behaviors. These factors distinguish this assay from other operant or reflex methods for recording orofacial nociception.     

Differential Responses to Same and Opposite Sex Odors by Adult House Mice Are Associated with Anogenital Distance

Intrauterine position (IUP) of female and male fetuses in litter-bearing mammals can affect their physiology, morphology and behavior. The relationship between anogenital distance (AGD) and IUP was used as a bioassay for the degree of exposure of female and male fetuses to hormones in utero . Based on laboratory work in several rodent species, the following predictions were made for house mice ( Mus musculus domesticus ): (1) female mice should prefer odors from males with larger AGDs because such males are more aggressive, could protect more resources, and are better parents than males with smaller AGDs; (2) male mice should prefer odors from females with smaller AGDs because these females produce more offspring and are better parents than females with larger AGDs. We also tested the prediction that within sexes, mice should avoid odors from mice with larger AGDs because such mice are more aggressive. Responses to odors in traps were used to test these predictions for house mice living in outdoor enclosures using odor-baited traps. Both predictions were confirmed. Furthermore, mice of both sexes tended to avoid odor cues from individuals of the same sex that had larger AGDs, probably to decrease chances of an aggressive encounter that could result in injury.     

Aversive Responses of Female Mice to the Odors of Parasitized Males: Neuromodulatory Mechanisms and Implications for Mate Choice

The detection and avoidance of parasitized conspecifics is proposed to have important consequences for the behavior of animals, especially as related to mate choice. A reduction in pain sensitivity (i.e. analgesia) is a major correlate of exposure to real or potential danger and threatening stimuli, facilitating the expression of various active (e.g. fleeing) and passive (e.g. immobilization) defense responses. The present study examined pain sensitivity (latency of a foot-lifting response to 50 ° C thermal surface) of female mice, Mus musculus, that were exposed to the urine and other odor secretions of male mice subclinically infected with the naturally occurring, enteric, sporozoan parasite, Eimeria vermiformis. A 30-min exposure to the odors of a parasitized male induced an analgesia in the female mice that was found to be mediated by the increased activity of endogenous opioid peptide systems. A brief 1-min exposure to the male odors induced a shorter duration and lower amplitude analgesia of a non-opioid (serotonergic) nature. Maximum analgesic responses were induced by the odors of pre-infective [5 days post-infection (PI)] and infective (day 10 PI) males, with significantly lower responses elicited by the odors of post-infective (day 17 PI) male mice. Exposure to the odors of unparasitized males had no significant effects on the pain sensitivity of female mice. These results indicate that female mice can distinguish between the odors of parasitized and non-parasitized male mice, and find the odors of parasitized males threatening and/or stressful. These odor-induced analgesic responses and their neurohormonal correlates may be part of an adaptive preparatory defense mechanism that facilitates the detection and avoidance of parasitized males by female mice and contributes to female mate choice.     

Ontogeny of a Simple Locomotor System: Role of the Periphery in the Development of Central Nervous Circuitry

The development of locomotor systems in the lobster Homarusamericanus is described. The tail—flip escape responseis fully developed when the larvae hatch, and occurs withoutthe participation of giant fibers. The abdominal swimmeretsare undifferentiated at hatching, but are fully developed twoto three weeks later when the animals molt to the fourth larvalstage. Forward locomotion in the pelagic larvae is achievedusing thoracic swimming appendages until the fourth larval stage,when these degenerate and the swimmerets assume the locomotorrole. The hypothesis that peripheral structures specify the centralnervous connections of motoneurons during ontogeny was testedin the swimmeret system. Presumptive swimmeret appendages, includingprospective muscle and sense organs, were extirpated prior totheir differentiation in newly hatched larvae. The correspondingswimmeret motoneurons nevertheless grew and formed normal centralconnections, as evidenced by the appearance of normal patternsof rhythmic locomotor discharge and normal reflexes at the usualtime. Moreover, swimmeret motoneurons retained normal patternsof motor output even when the regeneration of their target appendageswas prevented for as long as two months. Therefore, the formationof normal motor output patterns during ontogeny is not dependentupon feedback from differentiated target muscle nor from senseorgans which normally monitor the results of the motor activity.     

Using Nest Temperature to Estimate Nest Attendance of Piping Plovers

Abstract: Recent technological innovations allow remote monitoring of avian nest temperature that minimizes disturbance and expense without altering clutch sizes. However, the efficacy of such techniques has not been determined for ground-nesting birds. We compared the efficacy of 2 techniques, iButton® data loggers (Maxim/Dallas Semiconductor Corp., Sunnyvale, CA) and custom-built thermocouples, to measure nest temperature of piping plovers (Charadrius melodus) relative to nest attendance at Cape Cod National Seashore, Massachusetts, USA. Neither technique affected hatching success (U = 389.5, P = 0.874) or rates of predation of nests containing devices (P = 0.894). We estimated nest attendance successfully with thermocouples in nests as long as air and surface temperatures were <29° Cand 43° C, respectively. Although iButtons could not be used to determine duration of on-bouts and off-bouts of incubating piping plovers, they were effective at determining when nests were abandoned or predated. We recommend the use of thermocouples for studying nest attendance of ground-nesting birds, in general, and of threatened and endangered species, in particular, where disturbance should be minimized and altering clutch sizes is not feasible.