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Biomedical subjects

G E Robinson

Publications and source records attributed to G E Robinson.

At least 37 records · Page 2Linked to original sources
PubMed2001

Behavioral rhythmicity, age, division of labor and period expression in the honey bee brain.

Young adult honey bees work inside the beehive "nursing" brood around the clock with no circadian rhythms; older bees forage for nectar and pollen outside with strong circadian rhythms. Previous research has shown that the development of an endogenous rhythm of activity is also seen in the laboratory in a constant environment. Newly emerging bees maintained in isolation are typically arrhythmic during the first few days of adult life and develop strong circadian rhythms by about a few days of age. In addition, average daily levels of period (per) mRNA in the brain are higher in foragers or forager-age bees (> 21 days of age) relative to young nest bees (approximately 7 days of age). The authors used social manipulations to uncouple behavioral rhythmicity, age, and task to determine the relationship between these factors and per. There was no obligate link between average daily levels of per brain mRNA and either behavioral rhythmicity or age. There also were no differences in per brain mRNA levels between nurse bees and foragers in social environments that promote precocious or reversed behavioral development. Nurses and other hive-age bees can have high or low levels of per mRNA levels in the brain, depending on the social environment, while foragers and foraging-age bees always have high levels. These findings suggest a link between honey bee foraging behavior and per up-regulation. Results also suggest task-related differences in the amplitude of per mRNA oscillation in the brain, with foragers having larger diurnal fluctuation in per than nurses, regardless of age. Taken together, these results suggest that social factors may exert potent influences on the regulation of clock genes.

Aging↗
PubMed2001

Changes in neuronal acetylcholinesterase gene expression and division of labor in honey bee colonies.

Division of labor in honey bee colonies is highlighted by adult bees making a transition at 2-3 wk of age from working in the hive to foraging for nectar and pollen outside. This behavioral development involves acquisition of new tasks that may require advanced learning capabilities. Because acetylcholinesterase (AChE) hydrolyzes acetylcholine, a major neurotransmitter associated with learning in the insect brain, we searched for changes in AChE expression in the brain during bee behavioral development. Biochemical aspects of the AChE protein were similar in foragers and "nurse" bees that work in the hive tending brood. However, catalytic AChE activity was significantly lower in foragers. Cloning of bee AChE cDNA enabled mRNA analysis, which demonstrated that the forager-related decrease in AChE activity was associated with decreased AChE mRNA levels. This was particularly apparent in the mushroom bodies, a brain region known to be involved with olfactory and visual learning and memory. In addition, treatment with the AChE-inhibitor metrifonate improved performance in an olfactory-learning assay. These findings demonstrate long-term, naturally occurring developmental downregulation of AChE gene expression in the bee brain, and suggest that this genomic plasticity can contribute to facilitated learning capabilities in forager bees.

Acetylcholinesterase↗
PubMed2001

Psychotic and mood disorders associated with the perimenopausal period: epidemiology, aetiology and management.

Contrary to widely held beliefs, menopause is not associated with an increase in psychiatric illness. Although just prior to menopause there is a slight increase in minor psychological symptoms, prevalence rates of depression fall postmenopause. Hypotheses for the occurrence of depression in some perimenopausal women include: a pre-existing sensitivity to the change in the gonadal hormones leading to decreases in neural transmitters; reactions to the physiological changes associated with menopause such as night sweats, or the influence of a multitude of negative attitudes and expectations concerning menopause. The loss of the protective effects of estrogen may be related to the slight increase in the incidence of schizophrenia in women at menopause. The role of hormone replacement therapy (HRT) in treating psychiatric symptoms remains poorly understood. In nondepressed women, HRT may improve well-being either as a direct effect or as a consequence of reduced physical symptoms and fear of aging. In women with moderate to severe depressions, HRT alone does not appear to be beneficial. HRT may have some beneficial effects on short term memory. More research is needed to assess the possible role of HRT in augmenting the effects of antidepressant and antipsychotic medications.

Affective Disorders, Psychotic↗
PubMed2001

The disconnect: infertility patients' information and the role they wish to play in decision making.

OBJECTIVE: To determine the preferred role in medical decision making of women undergoing fertility treatments and to establish whether their knowledge of treatments is adequate to inform their choices. METHODS: Self-report survey of 404 women undergoing fertility treatments in 2 university hospitals and a private fertility clinic in Canada. RESULTS: The women had been in fertility treatment for 2.3 +/- 2.6 years; 67.8% reported taking fertility drugs. Most (61.7%) women wanted to share knowledge equally with their doctors about possible fertility treatments. However, about half wanted to decide alone or mostly by themselves about the acceptability of treatment risks and benefits (56%), what treatments should be selected (49.8%), and when to conclude treatments (54.3%). In addition, 55.1% of the women did not know their personal eventual chances of pregnancy with fertility treatment or thought it was 50% or greater. Over half of the women (57.2%) who had taken fertility drugs were unaware of a possible link between fertility drugs and increased ovarian cancer risk. The majority of women (61.8%) who knew of this possible association reported that they learned about it from the print media. Women who knew of the association had a poor understanding of the strength of the evidence or the ability to detect or treat ovarian cancer successfully, and 88.3% thought they could reduce cancer risk by following their doctors' advice. CONCLUSIONS: Despite these women's wishes to actively participate in fertility treatment decisions, they lacked the necessary information to do so meaningfully. Public health policymakers, professional and advocacy organizations, physicians, other healthcare providers, and women themselves must find ways to improve the general public's and patients' understanding about fertility treatment outcomes and risks.

Female↗
PubMed2000

Changes in period mRNA levels in the brain and division of labor in honey bee colonies.

Previous research showed that age-related division of labor in honey bees is associated with changes in activity rhythms; young adult bees perform hive tasks with no daily rhythms, whereas older bees forage with strong daily rhythms. We report that this division of labor is also associated with differences in both circadian rhythms and mRNA levels of period, a gene well known for its role in circadian rhythms. The level of period mRNA in the brain oscillated in bees of all ages, but was significantly higher at all times in foragers. Elevated period mRNA levels cannot be attributed exclusively to aging, because bees induced to forage precociously because of a change in social environment had levels similar to normal age foragers. These results extend the regulation of a "clock gene" to a social context and suggest that there are connections at the molecular level between division of labor and chronobiology in social insects.

Animals↗
PubMed2000

Ontogeny of orientation flight in the honeybee revealed by harmonic radar.

Cognitive ethology focuses on the study of animals under natural conditions to reveal ecologically adapted modes of learning. But biologists can more easily study what an animal learns than how it learns. For example, honeybees take repeated 'orientation' flights before becoming foragers at about three weeks of age. These flights are a prerequisite for successful homing. Little is known about these flights because orienting bees rapidly fly out of the range of human observation. Using harmonic radar, we show for the first time a striking ontogeny to honeybee orientation flights. With increased experience, bees hold trip duration constant but fly faster, so later trips cover a larger area than earlier trips. In addition, each flight is typically restricted to a narrow sector around the hive. Orientation flights provide honeybees with repeated opportunities to view the hive and landscape features from different viewpoints, suggesting that bees learn the local landscape in a progressive fashion. We also show that these changes in orientation flight are related to the number of previous flights taken instead of chronological age, suggesting a learning process adapted to changes in weather conditions, flower availability and the needs of bee colonies.

Animal Communication↗
PubMed2000

Juvenile hormone paces behavioral development in the adult worker honey bee.

Behavioral development in the adult worker honey bee (Apis mellifera), from performing tasks inside the hive to foraging, is associated with an increase in the blood titer of juvenile hormone III (JH), and hormone treatment results in precocious foraging. To study behavioral development in the absence of JH we removed its glandular source, the corpora allata, in 1-day-old adult bees. The age at onset of foraging for allatectomized bees in typical colonies was significantly older compared with that of sham-operated bees in 3 out of 4 colonies; this delay was eliminated by hormone replacement in 3 out of 3 colonies. To determine the effects of corpora allata removal on sensitivity to changes in conditions that influence the rate of behavioral development, we used "single-cohort" colonies (composed of only young bees) in which some colony members initiate foraging precociously. The age at onset of foraging for allatectomized bees was significantly older compared with that of sham-operated bees in 2 out of 3 colonies, and this delay was eliminated by hormone replacement. Allatectomized bees initiated foraging at significantly younger ages in single-cohort colonies than in typical colonies. These results demonstrate that JH influences the pace of behavioral development in honey bees, but is not essential for either foraging or altering behavioral development in response to changes in conditions.

Aging↗
PubMed2000

The critical period for caste determination in Bombus terrestris and its juvenile hormone correlates.

The critical period for caste determination and its juvenile hormone (JH III) correlates were studied in Bombus terrestris. Larvae of known age and instar were taken from young colonies, in which they would have been reared as workers, and placed into groups of queenless workers. Under these conditions the critical age for caste determination was 5 days, during the second instar. Endocrine correlates of caste determination were obtained by determining profiles of juvenile hormone titer and juvenile hormone biosynthesis, measured by chiral-specific radioimmunoassay and the in vitro radiochemical assay, respectively. By the middle of the second instar prospective queen larvae had significantly higher rates of juvenile hormone biosynthesis and juvenile hormone titer than prospective worker larvae. Based on the coincidence of timing of both the critical period and the appearance of caste-specific juvenile hormone titer, we suggest that juvenile hormone plays a role in the mechanisms that control caste determination in B. terrestris.

Animals↗
PubMed2000

Brain biogenic amines and reproductive dominance in bumble bees (Bombus terrestris).

To begin to explore the role of biogenic amines in reproductive division of labor in social insects, brain levels of dopamine, serotonin, and octopamine were measured in bumble bee (Bombus terrestris) workers and queens that differ in behavioral and reproductive state. Levels of all three amines were similar for mated and virgin queens. Young workers that developed with or without a queen had similar amine levels, but in queenright colonies differences in biogenic amine levels were associated with differences in behavior and reproductive physiology. Dominant workers had significantly higher octopamine levels compared with workers of lower dominance status but of similar size, age, and ovary state. High dopamine levels were associated with the last stages of oocyte development irrespective of worker social status and behavior. These results suggest that biogenic amines are involved in behavioral and physiological aspects of regulation of reproduction in bumble bees.

Animals↗
PubMed2000

The interaction of R(+)- or S(-)-2,2'-diamino-1,1'-binaphthalene with a Pd/silica catalyst in tetrahydrofuran.

The interaction of 2,2'-diamino-1,1'-binaphthalene over a Pd/silica catalyst and its interaction with hydrogen in the system and with the solvent tetrahydrofuran, (THF) has been investigated. Three interactions have been identified, i) conversion of amine groups to hydroxy groups, ii) hydrogenation of one or more of the aromatic rings, and iii) reaction between the amine group(s) and the THF solvent.

Catalysis↗
PubMed1999

Larval and pupal development of the mushroom bodies in the honey bee, Apis mellifera.

The mushroom bodies are paired neuropils in the insect brain that act as multimodal sensory integration centers and are involved in learning and memory. Our studies, by using 5-bromo-2-deoxyuridine incorporation and the Feulgen technique, show that immediately before pupation, the brain of the developing honey bee (Apis mellifera) contains approximately 2,000 neuroblasts devoted to the production of the mushroom body intrinsic neurons (Kenyon cells). These neuroblasts are descended from four clusters of 45 or fewer neuroblasts each already present in the newly hatched larva. Subpopulations of Kenyon cells, distinct in cytoarchitecture, position, and immunohistochemical traits, are born at different, but overlapping, periods during the development of the mushroom bodies, with the final complement of these neurons in place by the mid-pupal stage. The mushroom bodies of the adult honey bee have a concentric arrangement of Kenyon cell types, with the outer layers born first and pushed to the periphery by later born neurons that remain nearer the center of proliferation. This concentricity is further reflected in morphologic and immunohistochemical traits of the adult neurons, and is demonstrated clearly by the pattern of expression of Drosophila myocyte enhancer factor 2 (DMEF2)-like immunoreactivity. This is the first comprehensive study of larval and pupal development of the honey bee mushroom bodies. Similarities to patterns of neurogenesis observed in the mushroom bodies of other insects and in the vertebrate cerebral cortex are discussed.

Animals↗
PubMed1999

Biogenic amines and division of labor in honey bee colonies.

Brain levels of dopamine, serotonin, and octopamine were measured in relation to both age-related division of labor and inter-individual differences in task specialization independent of age in honey bee colonies. The only differences among similarly aged bees performing different tasks were significantly lower levels of dopamine in food storers than comb builders and significantly lower levels of octopamine in soldiers than foragers, but soldiers also were slightly younger than foragers. Differences associated with age-related division of labor were stronger. Older bees, notably foragers, had significantly higher levels of all three amines than did younger bees working in the hive. Using social manipulations to unlink chronological age and behavioral status, octopamine was found to exhibit the most robust association between behavior and amine level, independent of age. Octopamine levels were significantly lower in normal-age nurses versus precocious foragers and overage nurses versus normal-age foragers, but not different in reverted nurses versus reversion colony foragers. Dopamine levels were significantly lower in normal-age nurses versus precocious foragers, but higher in reverted nurses versus reversion colony foragers. Serotonin levels did not differ in any of these comparisons. These correlative results suggest that octopamine is involved in the regulation of age-related division of labor in honey bees.

Aging↗
PubMed1999

Biogenic amines and division of labor in honey bee colonies: behaviorally related changes in the antennal lobes and age-related changes in the mushroom bodies.

Levels of the biogenic amines dopamine, serotonin, and octopamine were measured in different brain regions of adult worker honey bees as a function of age-related division of labor, using social manipulations to unlink age and behavioral state. In the antennal lobes, foragers had higher levels of all three amines than nurses, regardless of age. Differences were larger for octopamine than serotonin or dopamine. In the mushroom bodies, older bees had higher levels of all three amines than younger bees, regardless of behavioral state. These correlative results suggest that increases in octopamine in the antennal lobes may be particularly important in the control of age-related division of labor in honey bees.

Aging↗
PubMed1999

Neuroethology of spatial learning: the birds and the bees.

The discipline of neuroethology integrates perspectives from neuroscience, ethology, and evolutionary biology to investigate the mechanisms underlying the behavior of animals performing ecologically relevant tasks. One goal is to determine if common organizational principles are shared between nervous systems in diverse taxa. This chapter selectively reviews the evidence that particular brain regions subserve behaviors that require spatial learning in nature. Recent evidence suggests that the insect brain regions known as the mushroom bodies may function similarly to the avian and mammalian hippocampus. Volume changes in these brain regions during the life of an individual may reflect both developmental and phylogenetic trends. These patterns may reveal important structure-function relationships in the nervous system.

Animals↗
PubMed1999

Parameters of grieving in spontaneous abortion.

OBJECTIVE: The study's objective was to determine the quality and severity of grief after spontaneous abortion and to statistically determine the effect of significant demographics and social variables such as age, number of previous losses and the effect of perceived family support on the grief experienced. METHODS: Two hundred and ninety-four women who had experienced a miscarriage within the last year were the participants. One hundred and seventy-five had miscarried three months prior to participation in the study; one hundred and nineteen had miscarried one year previously. Ninety-five percent of women approached consented to participate. Standardized psychometric tests and Likert Scales measured elements of grief such as depression, self-esteem, perceived guilt and stress at two time periods in the first year after loss. RESULTS: Women in both time periods after miscarriage had mean depression scores in the "clinical risk for depression" or "in need of treatment" range, i.e., pharmacotherapy or psychotherapy. A majority of women showed negative emotions like self blame and stress. Younger women with multiple miscarriages showed more depression in the early time period after miscarriage than older women (p < .05). However, at one year younger women had the least depression. Marital and family conflict correlated positively with depressive symptomatology (p < .05). CONCLUSIONS: Women assessed in the first year after spontaneous abortion show grief characterized by perceived stress and high levels of depressive symptoms including self-blame. Marital or family problems increase emotional risk to a woman after miscarriage.

Abortion, Spontaneous↗
PubMed1998

Effects of social environment and worker mandibular glands on endocrine-mediated behavioral development in honey bees.

Previous studies suggest that older honey bee workers possess an inhibitory signal that regulates behavioral development in younger bees. To study how this inhibitor is transmitted, bees were reared for 7 days in double-screen cages, single-screen cages, or unrestricted in a typical colony (control bees). Double-screen cages prevented physical contact with colony members while single-screen cages allowed only antennation and food exchange. Bees reared in double-screen cages showed accelerated endocrine and behavioral development; they had significantly higher rates of juvenile hormone biosynthesis and juvenile hormone titers than did control bees and also were more likely to become precocious foragers. Relative to the other two groups, bees reared in single-screen cages showed intermediate juvenile hormone biosynthesis rates and titers, and intermediate rates of behavioral development. These results indicate that physical contact is required for total inhibition. We also began to test the hypothesis that worker mandibular glands are the sources of an inhibitory signal. Old bees with mandibular glands removed were significantly less inhibitory towards young bees than were sham-operated and unoperated bees. These results suggest that an inhibitor is produced by the worker mandibular glands.

Animals↗
PubMed1998

Stalking. Part I: An overview of the problem.

OBJECTIVE: This paper is the first of a 2-part review on the topic of stalking. It outlines the behaviours involved, epidemiology, motivation of offenders, and mental health consequences for the victim. METHOD: Computerized literature searches were used to identify relevant papers from psychiatric and legal journals. Publications by victims' and women's organizations provided additional information. RESULTS: Up to 1 in 20 women will be stalked during her lifetime. The majority of victims are female, while the offenders are usually male. Stalking behaviours range from surveillance to threatening aggressive or violent acts. The majority of stalking relates to failed intimate relationships. Stalkers may also suffer from erotomania or obsessional love with a primary psychiatric diagnosis. Victims may experience anxiety, depression, guilt, helplessness, and symptoms of posttraumatic stress disorder (PTSD). CONCLUSION: Stalking is a serious offence perpetrated by disturbed offenders. It can cause major mental health consequences, which are often poorly understood by society.

Adult↗