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PubMed2005

The effects of ants on the entomophagous butterfly caterpillar Feniseca tarquinius, and the putative role of chemical camouflage in the Feniseca-ant interaction.

Butterfly caterpillars in the lycaenid subfamily Miletinae are predators of ant-tended Homoptera, yet they lack specialized secretory and call-production organs crucial to ant association in other lycaenids. Here, we address the question of how miletine caterpillars have invaded the ant-Homoptera symbiosis through a study of the only New World miletine, Feniseca tarquinius, a predator of the wooly aphid Prociphilus tesselatus. Previous interpretations have suggested that F. tarquinius and other miletine caterpillars avoid ant aggression by concealing themselves under silken webs. In contrast, our field data indicate that F. tarquinius caterpillars are less likely to be concealed in the presence of the ants Camponotus pennsylvanicus and Formica obscuriventris than in the absence of ants, although caterpillar and ant behaviors vary between years. Chemical analysis and behavioral assays suggest that chemical camouflage, not physical concealment, is responsible for the ants' failure to detect and remove F. tarquinius caterpillars from aphid colonies. Analyses by gas chromatography indicate that the cuticular lipid composition of caterpillars are similar to that of their aphid prey, although it varies with prey species. Behavioral assays confirm that solvent extracts of F. tarquinius caterpillars and P. tesselatus aphids evoke similar behavioral responses in C. pennsylvanicus ants. Chemical camouflage is well known in social parasites of ants, but the present study represents one of a few documented cases where chemical deceit is important to interactions with ants outside the nest.

Animals↗

PubMed2003

Neonatal social isolation alters both maternal and pup behaviors in rats.

The development of emotional behavior is dependent on the early experiences of the infant and the quality of maternal care. In these experiments, the effects of social isolation during the preweaning period on both pup behavior and maternal responsivity were examined. In the first study, the number of ultrasonic vocalizations (USVs) emitted after brief maternal separation was measured in neonatal rats with differing histories of social isolation. The social isolation procedure consisted of 5 days of daily separation from the dam and littermates for either 3 or 6 hr. At both ages tested, socially isolated pups vocalized significantly less than control pups. In the second study, the effects of prior isolation either daily for 5 previous days (Chronic Isolation) or for 4 hr prior to testing (Acute Isolation) were examined in a T-maze choice test. Pup vocalizations in the presence of the dam and dams' maternal behavior were assessed. When the dam was confined to the start box or during the maternal free access period, both Chronic and Acute Isolates vocalized less than pups that had never left the home nest. Dams spent more time with and licked and groomed more frequently and for a longer time both Chronic and Acute Isolates compared to pups that had always been with dams in the home nest. These results suggest that early isolation experience can alter subsequent responses to separation stress in neonatal rats and that maternal behavior is sensitive to the prior experiences of offspring.

Animals↗

PubMed2001

High-temperature symmetry breaking in the electronic band structure of the quasi-one-dimensional solid NbSe3.

The electronic band structure of the Peierls compound NbSe3 has been explored for its symmetries with microspot synchrotron photoemission. The Fermi level crossings and deviations from one-dimensional behavior are identified. Density-functional calculations of the Fermi surfaces confirm the nesting conditions relevant for the two phase transitions. The instability along the chains with superstructure periodicity q = 0.44 A(-1) induces a backfolding of the electronic bands, and the Fermi level crossings appear suppressed. This broken symmetry is observed in the fluctuation regime at more than twice the critical temperature, where the correlation length is strongly reduced.

Journal Article↗

PubMed2006

Superconductivity in lithium, potassium, and aluminum under extreme pressure: a first-principles study.

Extreme pressure strongly affects the superconducting properties of "simple" elemental metals, such as Li, K, and Al. Pressure induces superconductivity in Li (as high as 17 K) while suppressing it in Al. We report first-principles investigations of the superconducting properties of dense Li, K, and Al based on a recently proposed, parameter-free, method. Our results show an unprecedented agreement with experiments, assess the predictive power of the method over a wide range of densities and electron-phonon couplings, and provide predictions for K, where no experiments exist so far. More importantly, our results help uncover the physics of the different behaviors of Li and Al in terms of phonon softening and Fermi surface nesting in Li.

Journal Article↗

PubMed1993

Relationship of population density, territorial interaction and plasma levels of gonadal steroids in spawning male demoiselles Chromis dispilus (Pisces: Pomacentridae).

Territorial male demoiselles Chromis dispilus were captured and bloodsampled underwater by scuba divers, from reef areas of low, medium, and high population density, over five spawning seasons. Measurements of densities of territory-holding males and the water-column population (females and nonterritory-holding males) were made from the same sites. Behavior of territory-holding males was assessed in relation to phase of the reproductive cycle and population density, using a remote underwater video system. Plasma levels of testosterone, 11-ketotestosterone (11KT), and 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta P) were measured by RIA. Territory density was found to be proportional to population size. Males from high density sites spent more time chasing conspecifics and spawning during the phase of courtship display and spawning (spawning phase), but there were no differences in behavior between males from different density sites during periods of egg-brooding and defence (nesting phase). Plasma levels of all three steroids were elevated during the spawning phase, and low during the nesting phase. Absolute levels of gonadal steroids were higher in fish from areas of high population density during the spawning phase, than in fish from lower population densities. In one case, plasma 11KT and 17,20 beta P were also elevated at high density during the nesting phase. The results of the study indicate that steroid hormone levels are labile in response to changes in population density, and frequency of territorial interaction. Changes in levels of plasma androgens are consistent with the "challenge" hypothesis of social regulation of territorial aggression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed2005

Seasonal plasticity of brain aromatase mRNA expression in glia: divergence across sex and vocal phenotypes.

Although teleost fishes have the highest levels of brain aromatase (estrogen synthase) compared to other vertebrates, little is known of its regulation and function in specific brain areas. Previously, we characterized the distribution of aromatase in the brain of midshipman fish, a model system for identifying the neural and endocrine basis of vocal-acoustic communication and alternative male reproductive tactics. Here, we quantified seasonal changes in brain aromatase mRNA expression in the inter- and intrasexually dimorphic sonic motor nucleus (SMN) and in the preoptic area (POA) in males and females in relation to seasonal changes in circulating steroid hormone levels and reproductive behaviors. Aromatase mRNA expression was compared within each sex throughout non-reproductive, pre-nesting, and nesting periods as well as between sexes within each season. Intrasexual (male) differences were also compared within the nesting period. Females had higher mRNA levels in the pre-nesting period when their steroid levels peaked, while acoustically courting (type I) males had highest expression during the nesting period when their steroid levels peaked. Females had significantly higher levels of expression than type I males in all brain areas, but only during the pre-nesting period. During the nesting period, non-courting type II males had significantly higher levels of aromatase mRNA in the SMN but equivalent levels in the POA compared to type I males and females. These results demonstrate seasonal and sex differences in brain aromatase mRNA expression in a teleost fish and suggest a role for aromatase in the expression of vocal-acoustic and alternative male reproductive phenotypes.

Analysis of Variance↗

PubMed1991

An attempt at reciprocal crosses between laboratory strains of large and small musk shrews (Suncus murinus)--influence of body-weight difference between sexes on mating success.

We conducted mating experiments between two laboratory strains of musk shrews (Suncus murinus), the large-sized shrews (BAN strain) originating from Bangladesh and the small-sized animals (NAG strain) from Nagasaki, Japan. In the 16 mating trials between 12 BAN females (mean body weight of 87.9 g) and 11 NAG males (52.3 g), highly aggressive fighting behaviors of the BAN females toward the NAG males were observed. The BAN females stayed in nest boxes in cages, whereas the NAG males kept out during the mating trials. No pregnant females were found in the trials. Their pregnancies were diagnosed by palpation on the day about 16 days after the separation of the pairs. Contrastively, in 6 of the 11 trials between 8 NAG females (34.2 g) and 6 BAN males (145.9 g), the viable and fertile F1 hybrids of 8 females and 8 males were produced. The F1, subsequent F2 and backcross progenies appeared neither external nor behavioral abnormalities. Various types of crosses using the F1, F2, and the two parental shrews showed that mating success was in a condition that females were nearly as heavy as males, or lighter. Although body weights of musk shrews from different geographical areas were reported to vary from 43.5 to 147.3 g in males and from 26.0 to 82.0 g in females, males in respective localities were constantly about 1.7 times heavier than the corresponding females. These results therefore suggest that body-weight differences between sexes paired greatly affect mating success in the cross between the strains of induced ovulatory shrews.

Animals↗

PubMed2004

The nest architecture of the Florida harvester ant, Pogonomyrmex badius.

The architecture of the subterranean nests of the Florida harvester ant, Pogonomyrmex badius, was studied through excavation and casting. Nests are composed of two basic units: descending shafts and horizontal chambers. Shafts form helices with diameters of 4 to 6 cm, and descend at an angle of about 15-20 degrees near the surface, increasing to about 70 degrees below about 50 cm in depth. Superficial chambers (< 15 cm deep) appear to be modified shafts with low angles of descent, and are distinct from deeper chambers. In larger nests, they have a looping, connected morphology. Chambers begin on the outside of the helix as horizontal-floored, circular indentations, becoming multi-lobed as they are enlarged. Chamber height is about 1 cm, and does not change with area. Chamber area is greatest in the upper reaches of the nest, and decreases with depth. Vertical spacing between chambers is least in the upper reaches and increases to a maximum at about 70 to 80% of the maximum depth of the nest. The distribution of chamber area is top-heavy, with about half the total area occurring in the top quarter of the nest. Each 10% depth increment of the nest contains 25 to 40% less area than the decile above it, no matter what the size of the nest. Nests grow by simultaneous deepening, addition of new chambers and/or shafts and enlargement of existing chambers. As a result, the vertical spacing between chambers is similar at all nest sizes, and the relative distribution of chamber area with relative nest depth did not change during colony growth (that is, the size-free nest shape was the same at all colony sizes). Total chamber area increased somewhat more slowly than the population of workers excavating the nest. The branching of shafts was consistently shallow (< 40 cm), somewhat more so in large nests than small. Large colonies rarely had more than 4 shaft/chamber series. Each new series contributed less to the total chamber area because its chambers were smaller. Incipient colonies were usually 40 to 50 cm deep while mature colonies were commonly 2.5 to 3.0 m deep. Workers captured near the top of a mature nest (and therefore older) and penned in escape proof enclosures, excavated larger nests than did young workers captured from the bottom of the nest. Most of this difference was due to a larger fraction of older workers engaging in digging, rather than an increase in their rate of work. All ages of workers produced similar top-heavy nests. When different ages of workers from different levels of a mature colony were allowed to re-assort themselves in a vertical test apparatus buried in the soil, older workers moved upward to assume positions in the upper parts of the nest, much as in the colonies from which they were taken. The vertical organization of workers based on age is therefore the product of active movement and choice. A possible template imparting information on depth is a carbon dioxide gradient. Carbon dioxide concentrations increased 5-fold between the surface and the depths of the nest. A preference of young workers for high carbon dioxide concentrations, and a tendency for workers to dig more under low carbon dioxide concentrations could explain both the vertical age-distribution of workers, and the top-heaviness of the nest's architecture.

Aging↗

PubMed1984

Intrasexual interactions among female golden hamsters (Mesocricetus auratus) over the estrous cycle.

Social interactions of cycling female golden hamsters paired with ovariectomized animals in large enclosures were primarily agonistic over the 4-day estrous cycle. These aggressive interactions were intense as indicated by frequent occurrences of chase and flight behavior. Dominant and subordinate social ranks were established in the majority of pairs (96%) tested, and even females in sexual heat were capable of attacking and dominating their rivals. Furthermore, cycling females exhibited significantly more aggressive acts than ovariectomized opponents 1 day prior to sexual receptivity. No differences in fighting patterns were found between animals on the other 3 days of the estrous cycle. Additional analyses revealed clear differences in agonistic elements, including flank marking, between dominant and subordinate females regardless of whether they were gonadectomized or intact. These analyses also showed that dominant individuals frequently chased and bit opponents during encounters within their nesting area. The data are examined for implications on the adaptive organization of female hamster agonistic behavior and the neuroendocrine regulation of species-typical behavior over the estrous cycle.

Aggression↗

PubMed1993

Evidence of commingling in human eating behavior.

This investigation tested whether distributions of certain aspects of eating behavior were consistent with the notion of a "mixture model;" that is, two or more distinct commingled component distributions, consistent with the possibility of major gene action. Undergraduates (n=901) completed self-report trait measures of hunger, disinhibition, and dietary restraint. Variables were residualized for gender and age and transformed to remove skewness. Residualized transformed distributions were tested for departure from unimodality with Hartigan's dip statistic. The distributions of all three aspects of eating behavior were significantly non-unimodal. Next, component multivariate normal distributions were estimated via maximum likelihood. Likelihood ratio tests were employed to compare nested models. A mixture of four distributions with unequal variance-covariance matrices fit significantly better than any more parsimonious model. In sum, these data strongly suggest that the distributions of several measures of eating behavior are composed of four component distributions. This finding is consistent with the possibility of major gene effects for eating behavior.

Adolescent↗

PubMed1994

Behavioral impairments of lead-injected young herring gulls in nature.

Lead is ubiquitous in the environment, and trace amounts enter the food chain and bioaccumulate in organisms high on the food chain. Although lead levels have been examined in a variety of wild species, effects data are usually from laboratory studies. Thus the relevance of effects to survival and fitness are not directly determined. In the field we compared the behavior of lead-injected young herring gulls (Larus argentatus) to the behavior of their control siblings who received an injection with no lead and to chicks from control nests that received no injections. Lead-injected chicks had significantly lower survival rates than all controls. Lead-injected chicks were less healthy than control chicks as measured by begging and walking scores and by the number of times they stumbled when walking. Control chicks had a higher degree of accuracy when pecking at their parents' bills to stimulate feeding compared to the lead-injected chicks. For all chicks, begging and walking scores improved with age. Behavioral deficits measured in the laboratory are homologous with those observed in the field.

Animals↗

PubMed1989

Malignant melanotic neuroectodermal tumor arising from the pineal body.

A case of a melanotic neuroectodermal tumor arising from pineal region of a 4-year-old girl is presented. The tumor had spread diffusely to the meninges, consistent with malignant behavior. Histologically, the tumor consisted primarily of epithelial elements arranged in tubules, cords and nests separated by fibrous vascular tissue in addition to a small neuroblastomatous focus. Melanin pigment was frequently observed in the epithelial tumor cells, and melanin-laden macrophages were also often observed. No teratoid elements were found. Immunohistochemically, tumor cells were positive for neuron-specific enolase but were nonreactive for S-100 protein, epithelial membrane antigen, glial fibrillary acidic protein, vimentin, alpha-fetoprotein and human chorionic gonadotrophin. Ultrastructurally, the epithelial nature of the tumor cells could be easily demonstrated. In addition, melanosomes in various stages in maturation were observed, indicating melanogenesis of the tumor. On the basis of the tumor location and the histological similarities previously observed for the fetal pineal body, it is very likely that this melanotic epithelial tumor could have originated from the fetal pineal gland.

Brain Neoplasms↗

PubMed2006

Mating system of the European hornet Vespa crabro: male seeking strategies and evidence for the involvement of a sex pheromone.

We describe details of the mate finding strategy of drones of the European hornet, Vespa crabro, and present evidence for the involvement of sex pheromones. Tests were carried out with free flying drones in natural habitats. Males patrolled the nest site itself, as well as nearby nonresource-based sites, without showing territorial behavior. Patrolling was restricted to sunny spots in the vegetation, and thus, the locations changed throughout the day. Drones were attracted to both caged gynes and to dead workers treated with gyne extracts, indicating the presence of a female-produced sex attractant. Treated workers also elicited copulation attempts by the attracted drones. Extracts from gynes, workers, and drones contained exclusively cuticular lipids, and the profile from gynes was much more diverse than that of workers and drones. The most striking differences observed related to the alkenes, monomethyl- and dimethylalkanes. The results provide a lead for potential attracting and copulation-releasing semiochemicals in V. crabro.

Alkanes↗

PubMed1992

Pigmented lesions of the vulva.

Pigmented vulvar lesions, including diffuse hyperpigmentation, are present in 10% to 12% of white women. About 2% of them are nevocellular nevi. In general, nevi on the vulva are identical by morphologic and histopathologic criteria to nevi elsewhere on the body, with the exception of a small subset of nevi in younger women. Nevi in this subset have the unusual features of enlarged junctional nests that are variable in size, shape, and position. The long-term biologic behavior of these nevi has not been determined. Other benign pigmented lesions include lentigines, melanosis, postinflammatory hyperpigmentation, seborrheic keratoses, and warts. Malignant pigmented lesions include some cases of vulvar intraepithelial neoplasia and melanoma. Melanoma of the vulva has a poorer prognosis overall than melanoma on the torso, apparently because of the extent of the disease at the time of diagnosis. Therefore, improving mortality rates depends to some extent on earlier diagnosis. Management of female patients includes careful inspection of the vulva with each full-skin or gynecologic examination, followed by biopsy of any suspicious lesion. The need for excision of benign nevocellular and melanocytic lesions is dependent on the histopathology. Because there are no long-term prospective studies of vulvar melanosis and the group of unusual vulvar nevi, treatment must be individualized.

Diagnosis, Differential↗

PubMed1995

Non-equilibrium systems theory: some applications for gerontological nursing practice.

1. In terms of NEST, aging can be understood as a process of formative change toward increasing disorder and order in form, pattern, or structure. The person moves toward greater complexity through self-organization processes. 2. Over time, self-organization processes result in increasingly unique perceptions and behavior. As an older person becomes more unique, he or she becomes more different from other older persons. 3. Self-organization processes are an appropriate focus of concern for nursing when NEST is used as a practice framework. The nurse tries to understand older persons' behaviors as outcomes of self-organization processes (attempts to bring order out of disorder).

Adaptation, Psychological↗

PubMed1999

Peripheral encoding of behaviorally relevant acoustic signals in a vocal fish: single tones.

The midshipman fish, Porichthys notatus, generates acoustic signals for intraspecific communication. Nesting males produce long-duration "hums" which attract gravid females and can be effectively mimicked by pure tones. In this study we examine the encoding of tonal signals by the midshipman peripheral auditory system. Single-unit recordings were made from afferents innervating the sacculus while presenting sounds via an underwater loudspeaker. Units were characterized by iso-intensity spike rate and vector strength of synchronization curves, as well as by peristimulus time histograms. Additionally, response-intensity curves and responses to long-duration (up to 10 s) stimuli were obtained. As has been seen in other teleosts, afferents had highly variable activity profiles. Excitatory frequencies ranged from 60 to over 300 Hz with most units responding best around 70 or 140 Hz. Thresholds at 90 Hz ranged from 95 to 145 dB re 1 microPa. Strong synchronization provided a robust temporal code of frequency, comparable to that described for goldfish. Spike rate showed varying degrees of adaptation but high rates were generally maintained even for 10-s stimuli. The midshipman peripheral auditory system is well suited to encoding conspecific communication signals, but nonetheless shares many response patterns with the auditory system of other teleosts.

Acoustic Stimulation↗

PubMed1980

Home-orienting behavior in rat pups surviving postnatal or intergenerational malnutrition.

Growth and home-orienting behavior were studied during the 1st 12 days of life in 3 groups of rat pups: (1) those with intergenerational malnutrition; (2) those with postnatal malnutrition produced by cross-fostering pups born of well-nourished mothers to lactating females maintained on a low-protein diet; and (3) well-nourished control pups. Growth of pups was impaired in both malnourished groups, and eye-opening was similarly delayed. On tests of homing behavior, both malnourished groups were impaired to a similar extent and were less likely to find their way to the nest than were control pups. However, survival rates were significantly lower (50%) in the postnatally malnourished group but not in the intergenerationally malnourished group (73%), as compared with controls (100%). These findings suggest that adaptation occurs in long-term malnutrition with increased survival. However, physical characteristics and homing behavior in early life are not distinguishable in those surviving short- or long-term malnutrition. This is in contrast to the finding of more severe behavioral deficits in later life among rats subjected to many generations of malnutrition than among those malnourished for only 1 generation.

Animals↗

PubMedDate not supplied

Variable selection for QSAR by artificial ant colony systems.

Derivation of quantitative structure-activity relationships (QSAR) usually involves computational models that relate a set of input variables describing the structural properties of the molecules for which the activity has been measured to the output variable representing activity. Many of the input variables may be correlated, and it is therefore often desirable to select an optimal subset of the input variables that results in the most predictive model. In this paper we describe an optimization technique for variable selection based on artificial ant colony systems. The algorithm is inspired by the behavior of real ants, which are able to find the shortest path between a food source and their nest using deposits of pheromone as a communication agent. The underlying basic self-organizing principle is exploited for the construction of parsimonious QSAR models based on neural networks for several classical QSAR data sets.

Algorithms↗