[A delay in the development of auditory sensitivity in nestlings and the reorganization of their feeding behavior].
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An outbreak of aspergillosis with the death of six birds in the North Carolina Zoological Park R. J. Reynolds Forest Aviary in the spring of 1993 led to an investigation of the concentration of Aspergillus fumigatus spores in the air. No Aspergillus sp. was found in the facility through use of the drop plate method (gravitometric sampling) along with swab-sampling of selected surfaces within the exhibit and plating of food samples and nesting material onto petri dishes of nutrient media. A number factors that could stress the avian population were identified. These included excessive heat in the upper portion of the aviary due to the failure of an air handling system, a malfunctioning cooling tower, and large numbers of visitors to the facility (an average of 3,500/day). In addition, the outbreak occurred during a period of increased nesting behavior. Sampling of the fungal population of the air was conducted 1 year later, when no disease was noted, to compare the sensitivity of the commonly used drop plate method (open plates of nutrient media) with a volumetric impaction method (Andersen N-6 Air Sampler). The volumetric method delivered quantitative as well as qualitative data and exhibited more sensitivity for fungal spores of size similar to those of Aspergillus sp.
In lactating female rats bilateral parasagittal cuts transecting the dorsolateral neural connections of the medial preoptic area (MPOA) abolished nest building and retrieving components of maternal behavior, while crouching and nursing were unaffected. While few animals with these cuts were suckled when presented with pups the prolactin secretion response was undiminished when suckling did occur. Whereas previous studies have demonstrated that extensive surgical separation of the medial preoptic area-anterior hypothalamic continuum from the lateral preoptic area-lateral hypothalamus disrupts all aspects of maternal behavior, the present study has determined more specifically the zone of fibers essential for the active components of maternal behavior, i.e., nest building and retrieving. These fibers appear to enter/leave MPO dorsolaterally beneath the crossing of the anterior commissure in the region of the bed nucleus of the stria terminalis. These neural connections are not the same as those that regulate prolactin secretion in the lactating rat.
Both younger (60-day-old) and older (365-day-old) male, heterogeneous stock mice were exposed to either a 0.5% lead acetate solution or water as their sole source of fluid for four weeks prior to testing their nest building and consummatory behavior in a temperature chamber. During the three weeks in the temperature chambers lead and water maintenance were continued, and fluid and food consumption, body weight and nest building were monitored. Temperature in the chambers was 21 degrees C during the first week, then reduced to 5 degrees C during the second week, and returned to 21 degrees C in the last week of testing. In general, younger animals responded more rapidly and more intensely than older mice to changes in temperature as reflected in consummatory behavior, but lead ingestion decreased the magnitude of the change in fluid intake. Lead ingestion also altered the pattern of change in food ingestion of older mice as a function of the reduced temperature challenge. The complexity of nests built increased when temperatures were lowered from 21 degrees C to 5 degrees C, but this measure was unaffected by lead ingestion or age.
The role of ovarian hormones in the induction of nest-building (tucking) and incubation behavior in female doves (Streptopelia risoria) was determined by systemic injections of estrogen, or progesterione, or estrogen combined with progesterone, or oil in reproductively experienced ovariectomized females. Combined estrogen and progesterone treatment was the most effective hormone regimen for eliciting both behavior patterns in females and also facilitated these behaviors in their untreated mates. Differences in role of the gonadal progesterone in male and female doves were discussed.
The behaviour of laying hens housed in 'welfare-improved' cages fitted with one nest per hen was investigated with manipulations of group size (two or four birds), spatial allowance excluding the nests (600 cm2 or 1200 cm2 per bird) and perch provision (presence or absence). More time was spent in the nests by birds housed at 600 cm2 than at 1200 cm2, and by birds housed in pairs than in four. Perch provision had no significant effect on time spent in the nest but resulted in reduced nest soiling by birds housed at 1200 cm2, and increased 'comfort' behaviour by some groups.
Nest defense behavior was examined in wild female house mice (Mus domesticus) that were derived from a stock initially trapped in Alberta, Canada. The first objective was to determine whether behavior toward pups prior to mating was related to the intensity of postpartum aggression in a variety of social situations. Therefore, prior to the experiments we screened virgin females for their behavior toward a newborn pup [60% of the females exhibited infanticide and 40% were noninfanticidal: 7% were parental (retrieved and hovered over the pup) and 33% ignored the pup]. Infanticidal and noninfanticidal females were then mated with males and used in four experiments. In Experiment 1 the females were housed individually prior to deliver, while in Experiment 2 the females were allowed to remain with their mates; in both situations all females successfully reared litters of similar sizes. Male and female intruders (that had all exhibited infanticide when previously tested with a pup) were placed separately into a test cage containing a lactating female during the first four days after delivery. Regardless of the presence of the stud male, previously infanticidal females were more aggressive (exhibited more attacks per min) toward both male and female intruders than were previously noninfanticidal females; infanticidal females also exhibited more of both forms of attack (offensive and defensive) and also attacked with greater intensity than did noninfanticidal females. The number of attacks toward intruders of both sexes increased for both infanticidal and noninfanticidal females between Day 1-4 postpartum, but very high rates of attack were observed on all days by the lactating females, including the day of delivery. In Experiments 3 and 4 only the most aggressive (previously infanticidal) females were tested. In Experiment 3, two unrelated, unfamiliar females were mated separately and then were housed together just prior to delivery, which was planned to occur 3-4 days apart. In 5 of the 15 cages, all pups disappeared on the day of delivery of the second female to deliver her litter. In the remaining 10 cages, it appeared that none of the pups produced by the 20 females were killed. Thus, in this experiment, 66% of pups survived to Day 4 postpartum. In Experiment 4, two previously infanticidal female siblings, which had been housed together since birth, were placed together with a stud male. In all 9 cages only one female became pregnant and delivered pups, but only 3 litters survived to Day 4 (no litters were observed being attacked during intruder tests).(ABSTRACT TRUNCATED AT 400 WORDS)
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Arg8-vasopressin (AVP), a circadian clock-controlled gene product, is released from the hypothalamic suprachiasmatic nuclei (SCN) in mice in a circadian fashion. Previously reported differences in two mouse lines, initially selected for thermoregulatory nest-building behavior (building small nests (S-mice) or big nests (B-mice)) with different circadian organization of behavior and in number of SCN-AVP immunoreactive neurons, were further investigated. We confirmed and expanded the finding that S-mice exhibited constant high levels of SCN-AVP content with no apparent circadian rhythmicity, whereas B-mice had lower numbers of AVP positive cells which varied with time of day. We found that AVP mRNA expression levels at midnight and midday were similar in both lines, as established by in situ hybridization. When AVP transport and release were blocked by colchicine, SCN-AVP immunoreactivity was similar in both lines. This suggests that differences in SCN-AVP content depend on transport or release. Organotypic SCN cultures of B-mice showed more AVP release per neuron than cultures of S-mice. These results reveal that on a mechanistic level the mouse lines differed in transport and/or release of AVP in the SCN, rather than differential regulation of AVP gene transcription or number of AVP immunoreactive neurons.
The functional significance of the suprachiasmatic nucleus (SCN) in circadian rhythm control of mammals has been well documented. The role of protein phosphorylation mediated by protein kinase C (PKC), however, is not well known. We report the immunocytochemical localization of three Ca(2+)-dependent PKC isoforms (alpha, betaI, betaII) within the SCN of selected house mouse lines that differ in behavioral circadian rhythm parameters. Optical density measurements revealed that the adult mice selected for low levels of nest-building behavior (small nest-builders) had more than threefold higher PKCbetaI immunostaining in the SCN than the mice selected for high levels of nest-building behavior (big nest-builders). A similar twofold difference between the adult small and big nest-builders was observed for the number of PKCbetaI-containing cells in the SCN. The non-selected control lines were intermediate. Ten-day-old pups revealed similar differences in PKCbetaI immunostaining in the SCN between the small and big nest-builders. PKCalpha and PKCbetaII immunostaining in the SCN was not different among the lines. PKCbetaI immunostaining was not different among the selected lines in the lateroanterior hypothalamic nucleus (LA) and the cornu ammonis field 1 (CA1) of the dorsal hippocampus and confirms the specificity of the difference in PKCbetaI immunostaining in the SCN among the selected lines. The significance of these findings is discussed in the context of differences among the lines in arginine-vasopressin (AVP) and light-induced Fos expression in the SCN, behavioral phase-delay responses to 15-min light pulses in constant darkness, and measures of the strength of the circadian activity rhythm expressed.
Short-term fluctuations in steroid hormones such as estradiol (E2) and progesterone (P) can affect the concentration of hippocampal dendritic spines in adult, cycling nulliparous female rats. Pregnancy is characterized by a significantly longer duration of substantially elevated E2 and P compared to the estrous cycle. Thus, even greater changes than those reported during estrus may be evident. In two experiments, we examined the extent to which reproductive and hormonal state altered the concentration of apical neuronal dendritic spines of the CA1 region of the hippocampus in the following age-matched groups (N's = 7-10/group) of rats: in Exp. 1., CA1 dendritic spine density was examined in nulliparous diestrus (DES), proestrus (PRO), and estrus (ES) females, and late-pregnant (LP) (day 21) and lactating (day 5-6; LACT) females. In Exp. 2, the effects on spine density of a regimen mimicking pregnancy (and that stimulates maternal behavior) were examined, using ovariectomized, no hormone-exposed (OVX-minus) vs. sequential P&E(2)-treated (OVX + P&E2) groups. For both experiments, brains were removed, Golgi-Cox-stained and the most lateral tertiary branches of the apical dendrite of completely-stained hippocampal CA1 pyramidal neurons were traced with oil-immersion at x 1600 and dendritic spine density (# spines/10 micro dendritic segment) recorded. In Exp. 1, spine density was increased in LP and LACT females (which were not different) compared to the other virgin groups, including PRO females, who had more spines than DES and ES. In Exp. 2, OVX + P&E2 displayed significantly more dendritic spines per 10 micro than OVX-minus females (and had numbers that were similar to those of LP and LACT from Exp. 1). Pregnancy and its attendant hormonal fluctuations, therefore, may alter hippocampal neurons that regulate some non-pup-directed components of maternal behavior (e.g., nest building) or behaviors that support maternal behavior (e.g., foraging, associative memory).
This study takes the first step toward testing a Y chromosomal effect on both aggression and thermoregulatory nest-building behavior in mouse lines either bidirectionally selected for short (SAL) and long (LAL) attack latency or high (HIGH) and low (LOW) nest-building behavior. Using reciprocal crosses between SAL and LAL, and between HIGH and LOW, we found no indications for Y chromosomal effects on thermoregulatory nest-building behavior. As for aggression, we confirmed earlier studies on SAL and LAL, i.e., the origin of the Y chromosome influences attack latency, i.e., aggression. However, we did not find indications for a Y chromosomal effect on aggression in the HIGH and LOW lines. Since aggression and nest-building behavior have been shown to be characteristic parameters of two fundamentally different behavioral strategies, the present data underline the improbability of Y chromosomal genes underlying the genetic architecture of alternative behavioral strategies.
To investigate the roles of gonadotropin-releasing hormone (GnRH) types in reproductive behaviors, antisera against GnRH1, GnRH2 and GnRH3 were stereotaxically administered into the intracerebroventricular region to neutralize the three native GnRH types in the brain of male tilapia Oreochromis niloticus. Reproductive behaviors (nest-building and aggressive behaviors), and morphological changes of the three GnRH systems were investigated by immunocytochemistry. GnRH1, GnRH2 and GnRH3 immunoreactive fibers were significantly decreased following injections of GnRH antisera indicating successful neutralization of their respective endogenous GnRH peptides. GnRH1- and GnRH2-immunoneutralization did not inhibit reproductive behaviors but GnRH3-immunoneutralization significantly decreased nest-building ability (Saline: 26.5 +/- 3.7%/day versus GnRH3: 6.1 +/- 2.9%/day, P < 0.001), nest size (Saline: 0.67 +/- 0.09 points versus GnRH3: 0.10 +/- 0.05 points, P < 0.0002) and aggressive behavior (Saline: 2.34 +/- 0.19 points versus GnRH3 1.06 +/- 0.12 points, P < 0.0001). These observations provide evidence that GnRH3 is a potent neuromodulator of reproductive behaviors in male tilapia.
The circadian rhythm of core body temperature (Tb) was examined in two mouse lines bidirectionally selected for nest-building behavior (small (SNB) and big nest-builders (BNB)). This selection also resulted in more robust circadian organization of wheel-running activity in the SNB compared to the BNB mice. Tb was measured by an e-mitter implanted in the abdominal cavity. The circadian Tb rhythm of the SNB was more robust compared to the BNB regardless of whether the animals had access to a running wheel or not and regardless of the lighting conditions, i.e., 12 h:12 h light:dark (LD) cycle or constant dark (DD). Wheel-running activity rhythms of SNB were more robust in LD and DD compared to BNB. The amplitude of the circadian Tb rhythm increased significantly in response to wheel access in both mouse lines, but was not significantly different between the BNB and SNB. However, BNB tended to have lower amplitudes of circadian Tb rhythm in the absence of running wheels and a larger increase in the amplitude upon access to a running wheel compared to SNB. No differences were found in LD and DD between the lines in mean Tb and wheel-running activity levels. In addition, no differences between the two mouse lines were found in the free-running period of the Tb or wheel-running activity rhythms in DD. Overall, our findings reveal a more robust circadian phenotype of the SNB compared to the BNB.
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Previous divergent selection for nest-building behavior at 22 +/- 1 degrees C resulted in a 40-fold difference between the high and the low lines in amount of cotton used to build a nest. Correlated responses to selection indicated positive genetic correlations with body weight, nest-building at 4 +/- 1 degrees C, and litter size and negative genetic correlations with food consumption. At generation 46, the replicate high-selected (High 1 x High 2), randomly bred control (Control 1 x Control 2), and low-selected (Low 1 x Low 2) lines were crossed and the F1 showed significant heterosis for nest-building behavior. Regression of the F3 on the F2 generation gave heritability estimates of 0.16 +/- 0.10 for the high and 0.07 +/- 0.10 for the low cross, revealing a potential to break the selection limit (at least in the high direction), which had been reached at about 20 generations of selection. Indeed, renewed selection resulted in responses in both the high and the low directions of nesting, yielding realized heritabilities of 0.29 +/- 0.02 and 0.30 +/- 0.004, respectively. Replicated renewed selection, using the F3 generation as the base population, in the high direction of nesting resulted in correlated increases in nest-building at 4 +/- 1 degrees C, litter size, and food consumption. Body weight did not change. The positive correlation with food consumption is opposite in sign compared to the original selection experiment. This indicates that the evolutionary potential of a population to adapt to a changing environment not only depends on its current genetic variability in one adaptive trait, but may be constrained by genetic correlations changing over the course of selection.
When female Norway rats (Rattus norvegicus) become pregnant at the postpartum estrus they nurse this first litter concurrently with the gestation of a second litter. This second gestation is of variable length (23-31 days in this study) We investigated the behavior of mothers and their older litters around the time the second litter was born. Six female rats gave birth and were mated at the postpartum estrus. Continuous videotaped observation of each female and litter began approximately 3 days before, and continued for 3 days after the birth of the second litter. We found that suckling behavior and nest attendance by the older litter did not necessarily end when the second litter was born. When the gestation length of the second litter was short (23-25 days) older pups continued to spend time in the nest and to nurse along with their newborn siblings. These older pups also spent much time on the nest even in the absence of their mother. When gestation was long (27-31 days) older pups were weaned before the birth of the second litter and spent less time on the nest with the newborns. Stereotyped attacks by the female against her weanling age pups were seen both pre- and postpartum. This maternal aggression did not appear to deter suckling and nest attendance by the weanlings.
Lactating rats were used in experiments to examine the role of the dopamine system in the regulation of ongoing maternal behavior. Administration of haloperidol disrupted retrieval behavior and nest building in a dose-dependent manner but not nursing behavior and pup licking. Feeding behavior including carrying of food pellets to the nest and general locomotor ability were not disrupted by haloperidol. Apomorphine effectively reversed the inhibition caused by dopaminergic blockade. These results indicate a role for dopamine in the motivational regulation of retrieval and nest building during the postpartum phase of maternal behavior.