Distinguishing mechanisms for the evolution of co-operation

The existence of co-operation between species has been cast as a problem to the selfish-gene view of evolution: why does co-operation persist, when it would seem that individual selection should favor the unco-operative individual who exploits the co-operative tendencies of its partner and gives nothing in return? The recent literature has emphasized one type of model as underlying the evolution and stability of interspecific co-operation, which we term the "partner-fidelity" model, and which is typified by the game theory model known as the iterated Prisoner's Dilemma game. Under this mechanism, individuals are associated with the same partner(s) during an indefinite sequence of interactions. Individuals who at any time fail to co-operate with their partner can be penalized by those same partners in subsequent trials, hence the co-operation can be evolutionarily stable. Many examples of biological co-operation that have been offered appear to conform to this model. However, a few examples appear instead to fit a different and unrecognized mechanism, termed "partner-choice". Under partner-choice, individuals are associated for just one interaction, but an asymmetry enables one member to differentially reward co-operative vs. unco-operative partners in advance of any possible exploitation. Possible examples of co-operation maintained through partner-choice mechanisms are provided by the yucca/yucca moth system and the fig/fig wasp system.     

INvestigation of the basis of reduced metabolic cooperation in mec- cells.

The basis for the apparent loss of metabolic co-operation in a line of mec^? cells derived by selection from a mec⁺ line has been investigated. The results indicate that the loss of pyrimidine deoxyribonucleotide co-operation in these cells is due neither to the dilution of transferred nucleotides by enlarged endogenous pools nor to the failure of distinct internal pools to equilibrate, but rather to a deficiency of intercellular junctions. This deficiency can be reversed by treatment of the cells with db-cAMP and theophylline which results in the restoration of co-operation for TdR nucleotides. The results also indicate that the residual junctional sites in mec^? cells can transfer TdR nucleotides under conditions where the mec⁺ donor pools are expanded.     

Rat Sertoli cells in culture undergo metabolic co-operation with each other and with fibroblasts

Metabolic co-operation between Sertoli cells from adult rats was detected by adding one group of cells, which were the recipients, to a second group of cells, which had been labelled for 3 h with [3H]uridine and were the donors. Metabolic co-operation also was studied by co-culturing Sertoli cells, which were the donors, with human or Chinese hamster HGPRT- fibroblasts (recipients) in the presence of [3H]hypoxanthine. With both techniques the recipients in contact with donors had significantly more radioactive grains than did the recipients alone. In all cases the proportion of interactions that were positive for metabolic co-operation was greater than 80%.     

Genetic complementation in hybrid cells derived from two metabolic co-operative defective mammalian cell lines

A series of hybrid clones have been isolated following the somatic cell fusion of two mammalian cell lines, each defective in junctional transfer of metabolites. One of these parental lines is a variant isolated by selection from the metabolic co-operation competent embryonal carcinoma line PC13TG8. The other parent is LMTK^? in which inability to transfer was found to be a pre-existing property. Hybrids between these two cell lines are restored in their ability to co-operate, indicating the existence of at least two genetically distinct lesions affecting metabolic co-operation, each of which is recessive. This is the first demonstration that more than one locus is involved in junctional communication.     

Genetic complementation in hybrid cells derived from two metabolic co-operation defective mammalian cell lines

A series of hybrid clones have been isolated following the somatic cell fusion of two mammalian cell lines, each defective in junctional transfer of metabolites. One of these parental lines is a variant isolated by selection from the metabolic co-operation competent embryonal carcinoma line PC13TG8. The other parent is LMTK⁻ in which inability to transfer was found to be a pre-existing property. Hybrids between these two cell lines are restored in their ability to co-operate, indicating the existence of at least two genetically distinct lesions affecting metabolic co-operation, each of which is recessive. This is the first demonstration that more than one locus is involved in junctional communication.     

Trade-off between reciprocal mutualists: local resource availability-oriented interaction in fig/fig wasp mutualism

1. The mechanisms that prevent competition (conflict) between the recipient and co-operative actor in co-operative systems remain one of the greatest problems for evolutionary biology. Previous hypotheses suggest that self-restraint, dispersal or spatial constraints can prevent direct competition for local resources or any other common resources, thereby maintaining stable co-operation interactions. In this study, we use the obligate fig-fig-wasp mutualism to examine whether the above mechanisms can maintain stable co-operation sufficiently between figs and fig wasps. 2. Our data on obligate co-operation between figs (Ficus racemosa Linn.) and fig wasps (Ceratoslen fusciceps Mayr) show that the number of viable seeds of figs is positively correlated with the number of pollinator offspring when the number of vacant female flowers is high while the foundress number is low (two foundresses). Meanwhile, they are negatively correlated when the number of vacant female flowers is low and the number of foundresses is increased manually (eight foundresses). The correlation coefficient between viable seeds and wasp offspring (galls) depends on vacant female flower availability. 3. Our data suggest that the interaction between figs and fig wasps is conditional, and that they co-operate when local resource availability is plentiful but are in conflict when local resource availability is limited. The self-restraint, dispersal and spatial heterogeneity previously hypothesized in maintaining stable co-operation cannot sufficiently prevent the symbionts from utilizing more local resources at the expense of the recipients. The conflict, which can disrupt the co-operation interaction, exists after the local resource is saturated with symbionts. The repression of symbiont increase, therefore repressing the utilization of local resources in the conflict period, is crucial in the maintenance and evolution of co-operation.     

Understanding deficient emotional self-regulation in adults with attention deficit hyperactivity disorder: a controlled study

While symptoms of deficient emotional self-regulation (DESR) such as low frustration tolerance, temper outbursts, emotional impulsivity, and mood lability are commonly associated with attention deficit hyperactivity disorder (ADHD), little is known about their nature. The main aim of this post hoc study was to examine the correlates of DESR in a large sample of adults with and without ADHD. Subjects were 206 adults with ADHD and 123 adults without ADHD from a family study of ADHD. Emotional impulsivity was operationalized using items from the Barkley Current Behavior Scale. Subjects were comprehensively assessed for psychiatric comorbidity using structured diagnostic interview methodology. We used the Quality of Life, Enjoyment, and Satisfaction Questionnaire-Short Form (QLES-Q-SF) and Social Adjustment Scale-Self-report (SAS-SR) to assess quality of life and psychosocial functioning. DESR was more common among ADHD compared with non-ADHD adults, and 55 % of adults with ADHD reported extreme DESR of greater severity than 95 % of control subjects. The association of ADHD and DESR was not entirely accounted for by either current or lifetime comorbid disorders. DESR was also associated with significant functional impairment as evaluated by the QLES-Q-SF and SAS-SR, and with reduced marital status, as well as higher risk for traffic accidents and arrests. DESR adversely impacts quality of life in adults with ADHD. More work is needed to further evaluate DESR in clinical and investigational studies of subjects with ADHD.     

The role of root system architecture and root hairs in promoting anchorage against uprooting forces in Allium cepa and root mutants of Arabidopsis thaliana.

The role played by lateral roots and root hairs in promoting plant anchorage, and specifically resistance to vertical uprooting forces has been determined experimentally. Two species were studied, Allium cepa (onion) which has a particularly simple root system and two mutants of Arabidopsis thaliana, one without root hairs (rhd 2-1) and another with reduced lateral root branching (axr 4-2). Maximum strength of individual onion roots within a plant increased with plant age. In uprooting tests on onion seedlings, resistance to uprooting could be resolved into a series of events associated with the breakage of individual roots. Peak pulling resistance was explained in a regression model by a combination of a measure of plant size and the extent to which the uprooting resistance of individual roots was additive. This additive effect is termed root co-operation. A simple model is presented to demonstrate the role played by root co-operation in uprooting resistance. In similar uprooting tests on Arabidopsis thaliana, the mutant axr 4-2, with very restricted lateral development, showed a 14% reduction in peak pulling resistance when compared with the wild-type plants of similar shoot dry weight. The uprooting force trace of axr 4-2 was different to that of the wild type, and the main axis was a more significant contributor to anchorage than in the wild type. By contrast, the root hair-deficient mutant rhd 2-1 showed no difference in peak pulling resistance compared with the wild type, suggesting that root hairs do not normally play a role in uprooting resistance. The results show that lateral roots play an important role in anchorage, and that co-operation between roots may be the most significant factor.     

Mood induction in depressive patients: a comparative multidimensional approach

Anhedonia, reduced positive affect and enhanced negative affect are integral characteristics of major depressive disorder (MDD). Emotion dysregulation, e.g. in terms of different emotion processing deficits, has consistently been reported. The aim of the present study was to investigate mood changes in depressive patients using a multidimensional approach for the measurement of emotional reactivity to mood induction procedures. Experimentally, mood states can be altered using various mood induction procedures. The present study aimed at validating two different positive mood induction procedures in patients with MDD and investigating which procedure is more effective and applicable in detecting dysfunctions in MDD. The first procedure relied on the presentation of happy vs. neutral faces, while the second used funny vs. neutral cartoons. Emotional reactivity was assessed in 16 depressed and 16 healthy subjects using self-report measures, measurements of electrodermal activity and standardized analyses of facial responses. Positive mood induction was successful in both procedures according to subjective ratings in patients and controls. In the cartoon condition, however, a discrepancy between reduced facial activity and concurrently enhanced autonomous reactivity was found in patients. Relying on a multidimensional assessment technique, a more comprehensive estimate of dysfunctions in emotional reactivity in MDD was available than by self-report measures alone and this was unsheathed especially by the mood induction procedure relying on cartoons. The divergent facial and autonomic responses in the presence of unaffected subjective reactivity suggest an underlying deficit in the patients' ability to express the felt arousal to funny cartoons. Our results encourage the application of both procedures in functional imaging studies for investigating the neural substrates of emotion dysregulation in MDD patients. Mood induction via cartoons appears to be superior to mood induction via faces and autobiographical material in uncovering specific emotional dysfunctions in MDD.     

Adiponectin and negative mood in healthy premenopausal and postmenopausal women

Negative mood and stress are associated with cardiovascular and metabolic disease. There are likely many physiological mechanisms underlying the poor health outcomes. The relationship of psychological states (negative mood, life stress, and stress-responsive hormones) and adiponectin, an adipokine that promotes insulin sensitivity, was investigated in two separate studies. The two groups of participants included 52 healthy, premenopausal women, and 63 postmenopausal women with a range of stress levels. The relationship between adiponectin and psychological state (perceived stress and negative mood) was examined cross-sectionally in both groups of participants, but also prospectively (1 year later) in the group of postmenopausal women.In premenopausal women, negative mood and nocturnal urinary epinephrine were significantly related to adiponectin, independent of BMI. In postmenopausal women, negative mood was not associated with adiponectin cross-sectionally, but negative mood was a significant predictor for lower levels of adiponectin 1 year later, independent of initial adiponectin concentrations and changes in body mass index. Lastly, having a depressive disorder was related to lower adiponectin. As adiponectin levels are associated with insulin resistance, obesity, and diabetes mellitus, these findings suggest there may be an adiponectin-mediated pathway explaining in part how negative mood affects metabolic health. Mechanistic studies are needed to explore this potential relationship further.     

How Self-Generated Thought Shapes Mood—The Relation between Mind-Wandering and Mood Depends on the Socio-Temporal Content of Thoughts

Recent work has highlighted that the generation of thoughts unrelated to the current environment may be both a cause and a consequence of unhappiness. The current study used lag analysis to examine whether the relationship between self-generated thought and negative affect depends on the content of the thoughts themselves. We found that the emotional content could strongly predict subsequent mood (e.g. negative thoughts were associated with subsequent negative mood). However, this direct relationship was modulated by the socio-temporal content of the thoughts: thoughts that were past- and other-related were associated with subsequent negative mood, even if current thought content was positive. By contrast, future- and self-related thoughts preceded improvements of mood, even when current thought content was negative. These results highlight the important link between self-generated thought and mood and suggest that the socio-temporal content plays an important role in determining whether an individual''s future affective state will be happy or sad.     

N-person games and the evolution of co-operation: a model based on predator inspection in fish

Two N-person game theoretical models examining the evolution of co-operation during predator inspection in fish are presented. Predator inspection occurs in small shoals of fish, in which one to a few individuals, the "inspectors" (co-operators) break away from the shoal and cautiously approach a predator to obtain information on this potential danger. In the models presented here, remaining with the shoal and not inspecting is considered an act of defection. Both model I and II produce a stable internal polymorphism of inspectors and noninspectors. While the equilibrial frequency of inspectors can be low (i.e. less than 10%) at large shoal size, the proportion of shoals containing any inspectors--and therefore exhibiting the inspection behavior--is much greater. Both models presented here, and N-person games in general are equivalent to intrademic group selection models of evolution in structured populations, in which shoals are trait groups and co-operation evolves by between-shoal selection. While the results are cast in terms of predator inspection, the model itself is general and applies to any multi-group scenario where co-operators benefit entire groups at their own expense. The results presented here add to the mounting theoretical and empirical evidence that co-operation is frequently not a pure evolutionarily stable strategy, and that many metapopulations should be polymorphic for both co-operators and defectors.     

DEPRESSED MOOD IN THE WORKING POPULATION: ASSOCIATIONS WITH WORK SCHEDULES AND WORKING HOURS

The impact of working time arrangements (WTA) on health has been studied extensively. Still, little is known about the interrelation between work schedules, working hours, and depressed mood. For work schedules, the underlying assumptions regarding depressed mood refer to a disturbance of social and biological rhythms, whereas for working hours, the assumptions relate to workload and work capacity. Conversely, depressed mood may urge an employee to adjust his/her work schedule and/or number of working hours/week (h/wk). The aim of this study was to assess the association between work schedule and working hours with depressed mood. Using baseline data from the Maastricht Cohort Study, depressed mood in day work was compared with depressed mood in different shiftwork schedules (n?=?8843). Within day work, several categories of working h/wk were studied in association with depressed mood (n?=?7217). The association between depressed mood and several aspects of overtime was assessed separately. Depressed mood was measured with a dichotomous item: “Did you feel down every day over the last two weeks?” Separate logistic regression analyses were conducted for men and women, with adjustments for potential confounders. The odds ratio (OR) for depressed mood was greater for men involved in shiftwork than for men only involved in day work (three-shift OR?=?2.05 [95% confidence interval, CI 1.52–2.77]; five-shift OR?=?1.34 [95% CI 1.00–1.80]; irregular-shift OR?=?1.79 [95% CI 1.27–2.53]). In female employees, five-shift work was associated with a higher prevalence of depressed mood (OR?=?5.96 [95% CI 2.83–12.56]). Regarding the number of working h/wk, men working <26?h/wk had a higher prevalence of depressed mood than men working 36–40?h/wk (OR?=?2.73 [95% CI 1.35–5.52]). After conducting trend analyses, a significant decreasing trend was found in men, whereas an increasing trend was found in women working a high number of hours. Furthermore, a dose-response relationship was present in men regarding the number of overtime h/wk. This study showed that different work schedules and working hours are associated with depressed mood. Shiftwork was related to a higher prevalence of depressed mood than day work. The association was more pronounced for male employees. Regarding the number of working h/wk, male and female employees showed an opposite trend in depressed mood. Because of the possibility of a healthy worker effect and the possibility of a reciprocal relationship between WTA and depressed mood, the reported relation might be underestimated. This study has illustrated that occupational physicians, who deal with depressed mood among workers, should carefully consider the impact of WTA. (Author coorespondence: Karolien.Driesen@epid.unimaas.nl)     

The evolutionary origins of mood and its disorders

The term 'mood' in its scientific usage refers to relatively enduring affective states that arise when negative or positive experience in one context or time period alters the individual's threshold for responding to potentially negative or positive events in subsequent contexts or time periods. The capacity for mood appears to be phylogenetically widespread and the mechanisms underlying it are highly conserved in diverse animals, suggesting it has an important adaptive function. In this review, we discuss how moods can be classified across species, and what the selective advantages of the capacity for mood are. Core moods can be localised within a two-dimensional continuous space, where one axis represents sensitivity to punishment or threat, and the other, sensitivity to reward. Depressed mood and anxious mood represent two different quadrants of this space. The adaptive function of mood is to integrate information about the recent state of the environment and current physical condition of the organism to fine-tune its decisions about the allocation of behavioural effort. Many empirical observations from both humans and non-human animals are consistent with this model. We discuss the implications of this adaptive approach to mood systems for mood disorders in humans.     

Use of standardised patients in the evaluation of a residency mood disorders curriculum: a brief report

Background and objectives The purpose of this paper is to describe the use of resident performance on an observed structured clinical examination (OSCE) as a tool to refine a mood disorders curriculum, and to disseminate a mood disorders OSCE for use in other residency settings.Methods A depression-focused OSCE and a direct observation evaluation tool were developed and implemented. A total of 24 first-year family medicine residents (PGY1) participated in the OSCE, and their performance was used to direct changes in a mood disorders curriculum.Results Residents performed well on general interview behaviours, and 67% were able to uncover depression in a patient presenting with headaches. Less than 50% of the residents asked about suicidal ideation and recreational drug use. Curriculum was added that addressed the latter deficiencies.Conclusions Tracking of resident performance on specific behaviours during OSCE sessions can be used for curriculum evaluation purposes. The mood disorders curriculum in additional family medicine residency programmes can now be evaluated using our depression-focused OSCE and Clinical Performance Checklist.     

Effects of Depressed Affect on Diurnal and Ultradian Variations in Mood in a Healthy Sample

The study investigated diurnal and ultradian variations in cheerful and depressed mood in a healthy sample, and examined whether these variations were related to severity of depressed affect. Thirty employed volunteers used a pocket computer to complete self-rating scales of depression and cheerfulness every 2 h for 14 days except during sleep periods. They also completed the Beck Depression Inventory (BDI) and the General Health Questionnaire (GHQ). Analysis of variance of depressed mood showed a significant interaction between time of day and BDI/GHQ, in which only the mood of the high BDI/GHQ groups got worse during the day. The low BDI group showed a diurnal variation in cheerful mood in which mood was at its best in the early evening. Cosinor and “binfit” analysis of raw and residual time-series showed that more than half of the participants had significant fitting ultradian rhythms in mood in the range 3-9 h. However, only the number of significant fits for residual cheerful mood was substantially above the level of chance. The amplitudes of the ultradian rhythms in raw depressed mood were greater in participants scoring higher on the BDI/GHQ scales, but this seemed to reflect an increase in serial dependency between depressed mood states. The results are discussed in relation to circadian rhythms in mood and depression.     

Differential behaviour of chromosomes in Scilla

Conclusion While the cause of the differential behaviour is not known we can with some confidence specify the conditions affecting its consequences. In the first place particular chromosomes respond to the abnormal conditions within the cell in different ways. InScilla it was shown that long chromosomes were more frequently retarded than short ones. A specific chromosome response was also deduced byJain inLolium, from the disproportionate preponderance of unsynchronised cells with one or two advanced bivalents. This kind of specificity may or may not be simply related to length, for example the minimum requirements for condensation may be greater for longer chromosomes. There is no evidence either way. A second condition, along with the first, would certainly appear to be the spatial relations of chromosome material within the nucleus, a factor recently discussed in general terms byDarlington (1957). On this basis the abnormal cells could be regarded as containing nuclei where co-operation was restricted, uncharacteristically, over limited distances. As suggested earlier the initial cause of this is most reasonably attributed to differences in the cytoplasm, which in normal cells permits general co-operation within nuclei, but which in abnormal cells with genetically identical nuclei, does not.     

Food cravings, mood, and the menstrual cycle

The primary objective of the present investigation was to document positive changes in food cravings, food consumption, and mood changes over the menstrual cycle and to explore the relation between these factors and dieting habits. A total of 32 female undergraduates completed daily self-reports of food cravings, foods eaten, and mood, for 5 or more weeks. Comparisons of these measures in the 10 days preceding (luteal phase) and 10 days following menstruation onset (follicular phase) revealed that both food cravings and amount eaten were greater in the luteal phase than in the follicular phase. Although women also experienced less positive affect in the luteal phase, there was no correlation between mood and either cravings or amount eaten. Women rated as chronic dieters craved less than those rated an nondieters. The findings on mood and eating confirm previous research, whereas those on cravings extend such research by suggesting that carbohydrate cravings may be augmented by the luteal phase in healthy women.     

The Relationship of Dream Content and Changes in Daytime Mood in Traumatized vs. Non-Traumatized Children

The study examined how the mood changes from night to morning, and how dysphoric dream contents associate with this change among children who live in traumatic environment and their controls from peaceful area. The sample consisted of 413 Palestinian boys and girls of 6–15 years of age, the mean age being 11.22 ± 2.64. The participants filled in a seven-day dream diary in which they recorded their recalled dreams every morning. First, the results, confirmed that mood change from evening to morning is a general dream function: age and gender are not related to the change. The mood chance was rather associated with what and whom the children dreamt about. Second, the hypothesis of the trauma group showing less change in dysphoric dream content and in the intensity of negative morning mood across a period of time of seven days was not confirmed. On the contrary, the results showed that both dreams incorporating dysphoric themes and negative morning mood decreased only among children living in traumatic conditions. Third, it was hypothesized that there is a stronger association between presleep negative mood and dysphoric dreams, as well as between the dysphoric dreams and negative morning mood among children living in traumatic environment than among children from peaceful area. Contrary to the hypothesis, results for the trauma group revealed a reverse association between evening mood and dream contents: the more afraid, angry and worried children felt in the evening, the more Happy recreation dreams they reported, and the happier evening mood they reported, the more Threatening stranger dreams they had. However, concurring with the hypothesis, a direct association was found between dysphoric dreams and negative morning mood in the trauma group. The more children dreamt about Threatening strangers, the more afraid, angry and worried they felt in the morning. The discussion proposes a model of the correcting or balancing dream function that is characterized by an reverse assimilation of incorporating evening mood into dreams, and by a direct accommodation of dream content into morning mood.     

Metabolic coupling, cumulus expansion and meiotic resumption in mouse cumuli oophori cultured in vitro in the presence of FSH or dcAMP, or stimulated in vivo by hCG

The temporal changes of metabolic coupling between the mouse oocyte and the cumulus cells which follow hCG injection in vivo and FSH treatment in vitro were studied by measuring what fraction of [3H]uridine taken up by cumulus cells was transferred to the oocyte. Meiotic resumption and a partial coupling loss (to 35% of the initial value) spontaneously occurred in cumuli cultured in control medium. The addition of 1 microgram FSH/ml in vitro, or the injection of hCG in vivo caused a delay of about 3 h in both phenomena and a near total uncoupling, together with cumulus expansion. FSH caused uncoupling even if cumulus expansion was prevented by the addition of heparin. The presence of 2 mM-dcAMP prevented meiotic resumption in cumulus-enclosed oocytes and maintained a high level of co-operation for at least 6 h. The slow uncoupling observed at later times was due to cumulus expansion, because it was totally prevented by heparin. We suggest that metabolic co-operation with the cumulus oophorus and meiotic resumption are both regulated by FSH through variations of intracellular levels of cAMP.