Hatchery selection promotes boldness in newly hatched brown trout (Salmo trutta): implications for dominance

By using newly hatched (approximately 2 weeks old) brown trout(Salmo trutta) from six families of wild and six families ofsea-ranched origin (seventh generation), we tested the hypothesesthat (1) the hatchery environment selects for increased boldness,and (2) boldness predicts dominance status. Sea-ranched troutspend their first 2 years in the hatchery before being releasedinto the wild at the onset of seaward migration. Trout werepresented with a novel object (tack) and with food (brine shrimp),and their responses were measured and scored in terms of boldness.Siblings with increasing difference in boldness were then pairedin dyadic contests. Fish of sea-ranged origin were on averagebolder than were fish of wild origin, and bolder individualswere more likely to become dominant regardless of origin. Boldnesswas not related to RNA levels, indicating that bold behaviorwas not a consequence of higher metabolism or growth rate. Neitherwas size a predictor of bold behavior or the outcome of dyadiccontests. These results are consistent with studies on olderlife stages showing increased boldness toward predators in hatchery-selectedfish, which suggests that behavioral consequences of hatcheryselection are manifested very early in life. The concordancebetween boldness and dominance may suggest that these behaviorsare linked in a risk prone-aggressive phenotype, which may bepromoted by hatchery selection. However, we also found significantvariation in behavioral and growth-related traits among families,suggesting that heritable variation has not been exhausted bysea-ranching procedures.     

Aggressiveness and kinship in brown trout (Salmo trutta) parr

In a series of experiments, kin-biased behavior of young browntrout (Salmo trutta) was observed. The aggressiveness shownby groups of familiar siblings (siblings reared together sincefertilization) and groups of unfamiliar siblings (siblings rearedapart since fertilization) was significantly lower comparedto that of mixed groups of two unrelated sibling groups (offspringof two different pairs of parents). The evolution of kin-biasedbehavior, as shown by a reduction in aggressiveness, is assumedto have evolved through a kin-selective mechanism.[Behav Ecol7: 445-450 (1996)]     

Effects of Sustained Sleep Restriction on Mitogen-Stimulated Cytokines,Chemokines and T Helper 1/ T Helper 2 Balance in Humans

Background

Recent studies suggest that acute sleep deprivation disrupts cellular immune responses by shifting T helper (Th) cell activity towards a Th2 cytokine profile. Since little is known about more long-term effects, we investigated how five days of sleep restriction would affect pro-inflammatory, chemotactic, Th1- and Th2 cytokine secretion.

Methods

Nine healthy males participated in an experimental sleep protocol with two baseline sleep-wake cycles (sleep 23.00 – 07.00 h) followed by 5 days with restricted sleep (03.00 – 07.00 h). On the second baseline day and on the fifth day with restricted sleep, samples were drawn every third hour for determination of cytokines/chemokines (tumor necrosis factor alpha (TNF-α), interleukin (IL) -1β, IL-2, IL-4 and monocyte chemoattractant protein-1 (MCP-1)) after in vitro stimulation of whole blood samples with the mitogen phytohemagglutinin (PHA). Also leukocyte numbers, mononuclear cells and cortisol were analysed.

Results

5-days of sleep restriction affected PHA-induced immune responses in several ways. There was a general decrease of IL-2 production (p<.05). A shift in Th1/Th2 cytokine balance was also evident, as determined by a decrease in IL2/IL4 ratio. No other main effects of restricted sleep were shown. Two significant interactions showed that restricted sleep resulted in increased TNF-α and MCP-1 in the late evening and early night hours (p’s<.05). In addition, all variables varied across the 24 h day.

Conclusions

5-days of sleep restriction is characterized by a shift towards Th2 activity (i.e. lower 1L-2/IL-4 ratio) which is similar to the effects of acute sleep deprivation and psychological stress. This may have implications for people suffering from conditions characterized by excessive Th2 activity like in allergic disease, such as asthma, for whom restricted sleep could have negative consequences.     

Influence of flexibility and variability of working hours on health and well-being

Flexible working hours can have several meanings and can be arranged in a number of ways to suit the worker and/or employer. Two aspects of “flexible” arrangement of working hours were considered: one more subjected to company control and decision (variability) and one more connected to individual discretion and autonomy (flexibility). The aim of the study was to analyze these two dimensions in relation to health and well-being, taking into consideration the interaction with some relevant background variables related to demographics plus working and social conditions. The dataset of the Third European Survey on working conditions, conducted in 2000 and involving 21,505 workers, was used. Nineteen health disorders and four psycho-social conditions were tested by means of multiple logistic regression analysis, in which mutually adjusted odds ratios were calculated for age, gender, marital status, number of children, occupation, mode of employment, shift work, night work, time pressure, mental and physical workload, job satisfaction, and participation in work organization. The flexibility and variability of working hours appeared inversely related to health and psycho-social well-being: the most favorable effects were associated with higher flexibility and lower variability. The analysis of the interactions with the twelve intervening variables showed that physical work, age, and flexibility are the three most important factors affecting health and well-being. Flexibility resulted as the most important factor to influence work satisfaction; the second to affect family and social commitment and the ability to do the same job when 60 years old, as well as trauma, overall fatigue, irritability, and headache; and the third to influence heart disease, stomachache, anxiety, injury, and the feeling that health being at risk because of work. Variability was the third most important factor influencing family and social commitments. Moreover, shift and night work confirmed to have a significant influence on sleep, digestive and cardiovascular troubles, as well and health and safety at work. Time pressure also showed a relevant influence, both on individual stress and social life. Therefore, suitable arrangements of flexible working time, aimed at supporting workers' coping strategies, appear to have a clear beneficial effect on worker health and well-being, with positive consequences also at the company and social level, as evidenced by the higher “feeling to be able to work until 60 years of age”.     

Flexible working hours, health, and well-being in Europe: some considerations from a SALTSA project

The project brought together researchers from 9 EU-Countries and resulted in a number of actions, in particular the following: (a) There is an urgent need of defining the concept of flexible working hours, since it has been used in many different and even counterintuitive ways; the most obvious distinction is where the influence over the working hours lies, that is between the “company-based flexibility” and the “individual-oriented flexibility”; (b) The review of the Legislation in force in the 15 European countries shows that the regulation of working times is quite extensive and covers (Council Directive 93/104/EC) almost all the various arrangements of working hours (i.e., part-time, overtime, shift, and night work), but fails to provide for flexibility; (c) According to the data of the Third EU Survey on Working Conditions, longer and “irregular” working hours are in general linked to lower levels of health and well-being; moreover, low (individual) flexibility and high variability of working hours (i.e., company-based flexibility) were consistently associated with poor health and well-being, while low variability combined with high autonomy showed positive effects; (d) Six substudies from different countries demonstrated that flexible working hours vary according to country, economic sector, social status, and gender; overtime is the most frequent form of company-based flexibility but has negative effects on stress, sleep, and social and mental health; individual flexibility alleviates the negative effects of the company-based flexibility on subjective health, safety, and social well-being; (e) The literature review was able to list more than 1,000 references, but it was striking that most of these documents were mainly argumentative with very little empirical data. Thus, one may conclude that there is a large-scale intervention ongoing in our society with almost completely unknown and uncontrolled effects. Consequently, there is a strong need for systematic research and well-controlled actions in order to examine in detail what flexible working hours are considered, what and where are their positive effects, in particular, as concerns autonomy, and what regulation seem most reasonable.     

Detecting deletions in families affected by a dominant disease by use of marker data

A method of testing for whether inherited deletions are a cause of a single-locus dominant disease was derived, involving analysis of the marker segregation within the pedigree of a single family that segregates for the disease. It is shown that markers can be used to test deductively for the presence of an inherited deletion. The probabilities of confirming or rejecting the presence of a deletion in an arbitrary pedigree without inbreeding are then derived. The power of the test is shown to be limited in single trios but to increase rapidly as the size of the pedigree increases. For larger pedigrees, the probabilities of confirming or rejecting a deletion are higher than 0.9 for SNPs having a minor allele frequency greater than 0.4. The probabilities are higher using multiallelic markers such as microsatellites, reaching levels as high as 0.9 in even rather small pedigrees. In certain cases the test outcome is not deductive, a deletion being neither confirmed nor rejected. It is shown to still be possible then to employ a statistical test for the presence of a deletion by use of an a priori probability for a deletion.     

The Personal and Contextual Contributors to School Belongingness among Primary School Students

School belongingness has gained currency among educators and school health professionals as an important determinant of adolescent health. The current cross-sectional study presents the 15 most significant personal and contextual factors that collectively explain 66.4% (two-thirds) of the variability in 12-year old students’ perceptions of belongingness in primary school. The study is part of a larger longitudinal study investigating the factors associated with student adjustment in the transition from primary to secondary school. The study found that girls and students with disabilities had higher school belongingness scores than boys, and their typically developing counterparts respectively; and explained 2.5% of the variability in school belongingness. The majority (47.1% out of 66.4%) of the variability in school belongingness was explained by student personal factors, such as social acceptance, physical appearance competence, coping skills, and social affiliation motivation; followed by parental expectations (3% out of 66.4%), and school-based factors (13.9% out of 66.4%) such as, classroom involvement, task-goal structure, autonomy provision, cultural pluralism, and absence of bullying. Each of the identified contributors of primary school belongingness can be shaped through interventions, system changes, or policy reforms.     

Relationship between sleep stages and short‐term changes in rectal temperature in humans

Abstract

Sixteen volunteers have been studied during 3–4 control nights and eight of these subjects again during four successive sleeps on 30‐h “days”;. The experiments took place in a comfortable environment provided by an isolation chamber. Rectal temperature and the sleep EEG were measured throughout. The relationship between sleep stages, particularly SWS and REM sleep, and short‐term changes in rectal temperature has been investigated during both protocols. Care was taken to correct for or remove those temperature changes that could be attributed to circadian rhythmicity or the effects of loss of masking due to being awake. Results showed that there was a small but significant effect of sleep stages, with SWS producing a fall and REM sleep a rise in rectal temperature after a delay of about 30–48 minutes. It is concluded that such spontaneous changes in sleeping subjects accord with the results of other studies which indicate that thermoregulatory reflexes to hot or cold stimuli alter in different sleep stages.     

Dental microwear texture analysis: technical considerations

Dental microwear analysis is commonly used to infer aspects of diet in extinct primates. Conventional methods of microwear analysis have usually been limited to two-dimensional imaging studies using a scanning electron microscope and the identification of apparent individual features. These methods have proved time-consuming and prone to subjectivity and observer error. Here we describe a new methodological approach to microwear: dental microwear texture analysis, based on three-dimensional surface measurements taken using white-light confocal microscopy and scale-sensitive fractal analysis. Surface parameters for complexity, scale of maximum complexity, anisotropy, heterogeneity, and textural fill volume offer repeatable, quantitative characterizations of three-dimensional surfaces, free of observer measurement error. Some results are presented to illustrate how these parameters distinguish extant primates with different diets. In this case, microwear surfaces of Cebus apella and Lophocebus albigena, which consume some harder food items, have higher average values for complexity than do folivores or soft fruit eaters.     

Extended driving impairs nocturnal driving performances

Though fatigue and sleepiness at the wheel are well-known risk factors for traffic accidents, many drivers combine extended driving and sleep deprivation. Fatigue-related accidents occur mainly at night but there is no experimental data available to determine if the duration of prior driving affects driving performance at night. Participants drove in 3 nocturnal driving sessions (3-5 am, 1-5 am and 9 pm-5 am) on open highway. Fourteen young healthy men (mean age [+/-SD] = 23.4 [+/-1.7] years) participated Inappropriate line crossings (ILC) in the last hour of driving of each session, sleep variables, self-perceived fatigue and sleepiness were measured. Compared to the short (3-5 am) driving session, the incidence rate ratio of inappropriate line crossings increased by 2.6 (95% CI, 1.1 to 6.0; P<.05) for the intermediate (1-5 am) driving session and by 4.0 (CI, 1.7 to 9.4; P<.001) for the long (9 pm-5 am) driving session. Compared to the reference session (9-10 pm), the incidence rate ratio of inappropriate line crossings were 6.0 (95% CI, 2.3 to 15.5; P<.001), 15.4 (CI, 4.6 to 51.5; P<.001) and 24.3 (CI, 7.4 to 79.5; P<.001), respectively, for the three different durations of driving. Self-rated fatigue and sleepiness scores were both positively correlated to driving impairment in the intermediate and long duration sessions (P<.05) and increased significantly during the nocturnal driving sessions compared to the reference session (P<.01). At night, extended driving impairs driving performances and therefore should be limited.