Transgenic Arabidopsis plants can accumulate polyhydroxybutyrate to up to 4% of their fresh weight

 Transgenic Arabidopsis thaliana (L.) Heynh. plants expressing the three enzymes encoding the biosynthetic route to polyhydroxybutyrate (PHB) are described. These plants accumulated more than 4% of their fresh weight (≈40% of their dry weight) in the form of PHB in leaf chloroplasts. These very high producers were obtained and identified following a novel strategy consisting of a rapid GC-MS analysis of a large number of transgenic Arabidopsis plants generated using a triple construct, thus allowing the parallel transfer of all three genes necessary for PHB synthesis in a single transformation event. The level of PHB produced was 4-fold greater than previously published values, thus demonstrating the large potential of plants to produce this renewable resource. However, the high levels of the polymer produced had severe effects on both plant development and metabolism. Stunted growth and a loss of fertility were observed in the high-producing lines. Analysis of the metabolite composition of these lines using a GC-MS method that we have newly developed showed that the accumulation of high levels of PHB was not accompanied by an appreciable change in either the composition or the amount of fatty acids. Substantial changes were, however, observed in the levels of various organic acids, amino acids, sugars and sugar alcohols. Received: 2 February 2000 / Accepted: 31 March 2000     

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A hydrothermal vent mite (Halacaridae,Acari) with a new Corynophrya species (Suctoria,Ciliophora), description of the suctorian and its distribution on the halacarid mite

Copidognathus nautilei Bartsch, 1997, from a hydrothermal vent field of the Mid-Atlantic Ridge at about 13°N, 45°W and 4090 m depth, was infested with the suctorian Corynophrya abyssalis n. sp., with up to 58 epizoans per mite. The new suctorian has a sacciform body with seven longitudinal ribs, a compact macronucleus and up to 40 non-retractile tentacles. The budding is exogenous. The systematic position of the new species and the genus Corynophrya is discussed, as well as infestation rates and sites of suctorians on their halacarid hosts.     

Viral Dose and Immunosuppression Modulate the Progression of Acute BVDV-1 Infection in Calves: Evidence of Long Term Persistence after Intra-Nasal Infection

Bovine viral diarrhoea virus (BVDV) infection of cattle causes a diverse range of clinical outcomes from being asymptomatic, or a transient mild disease, to producing severe cases of acute disease leading to death. Four groups of calves were challenged with a type 1 BVDV strain, originating from a severe outbreak of BVDV in England, to study the effect of viral dose and immunosuppression on the viral replication and transmission of BVDV. Three groups received increasing amounts of virus: Group A received 10^2.55TCID₅₀/ml, group B 10^5.25TCID₅₀/ml and group C 10^6.7TCID ₅₀/ml. A fourth group (D) was inoculated with a medium dose (10^5.25TCID₅₀/ml) and concomitantly treated with dexamethasone (DMS) to assess the effects of chemically induced immunosuppression. Naïve calves were added as sentinel animals to assess virus transmission. The outcome of infection was dose dependent with animals given a higher dose developing severe disease and more pronounced viral replication. Despite virus being shed by the low-dose infection group, BVD was not transmitted to sentinel calves. Administration of dexamethasone (DMS) resulted in more severe clinical signs, prolonged viraemia and virus shedding. Using PCR techniques, viral RNA was detected in blood, several weeks after the limit of infectious virus recovery. Finally, a recently developed strand-specific RT-PCR detected negative strand viral RNA, indicative of actively replicating virus, in blood samples from convalescent animals, as late as 85 days post inoculation. This detection of long term replicating virus may indicate the way in which the virus persists and/or is reintroduced within herds.     

Differences in Energy Balance-Related Behaviours in European Preschool Children: The ToyBox-Study

Background

The aim of the current study was to compare levels of energy balance-related behaviours (physical activity, sedentary behaviour, and dietary behaviours (more specifically water consumption, sugar-sweetened beverage consumption and unhealthy snacking)) in four- to six-year-old preschoolers from six European countries (Belgium, Bulgaria, Germany, Greece, Poland, and Spain) within the ToyBox cross-sectional study.

Methods

A sample of 4,045 preschoolers (4.77 ± 0.43 years; 52.2% boys) had valid physical activity data (steps per day), parents of 8,117 preschoolers (4.78 ± 0.46 years; 53.0% boys) completed a parental questionnaire with questions on sedentary behaviours (television viewing, computer use, and quiet play), and parents of 7,244 preschoolers (4.77 ± 0.44 years; 52.0% boys) completed a food frequency questionnaire with questions on water consumption, sugar-sweetened beverage consumption and unhealthy snacking.

Results

The highest levels of physical activity were found in Spain (12,669 steps/day on weekdays), while the lowest levels were found in Bulgaria and Greece (9,777 and 9,656 steps/day on weekdays, respectively). German preschoolers spent the least amount of time in television viewing (43.3 min/day on weekdays), while Greek preschoolers spent the most time in television viewing (88.5 min/day on weekdays). A considerable amount of time was spent in quiet play in all countries, with the highest levels in Poland (104.9 min/day on weekdays), and the lowest levels in Spain (60.4 min/day on weekdays). Belgian, German, and Polish preschoolers had the lowest intakes of water and the highest intakes of sugar-sweetened beverages. The intake of snacks was the highest in Belgian preschoolers (73.1 g/day) and the lowest in Greek preschoolers (53.3 g/day).

Conclusions

Across six European countries, differences in preschoolers’ energy balance-related behaviours were found. Future interventions should target European preschoolers’ energy balance-related behaviours simultaneously, but should apply country-specific adaptations.     

Energy Expenditure and Metabolic Changes of Free-Flying Migrating Northern Bald Ibis

Many migrating birds undertake extraordinary long flights. How birds are able to perform such endurance flights of over 100-hour durations is still poorly understood. We examined energy expenditure and physiological changes in Northern Bald Ibis Geronticus eremite during natural flights using birds trained to follow an ultra-light aircraft. Because these birds were tame, with foster parents, we were able to bleed them immediately prior to and after each flight. Flight duration was experimentally designed ranging between one and almost four hours continuous flights. Energy expenditure during flight was estimated using doubly-labelled-water while physiological properties were assessed through blood chemistry including plasma metabolites, enzymes, electrolytes, blood gases, and reactive oxygen compounds. Instantaneous energy expenditure decreased with flight duration, and the birds appeared to balance aerobic and anaerobic metabolism, using fat, carbohydrate and protein as fuel. This made flight both economic and tolerable. The observed effects resemble classical exercise adaptations that can limit duration of exercise while reducing energetic output. There were also in-flight benefits that enable power output variation from cruising to manoeuvring. These adaptations share characteristics with physiological processes that have facilitated other athletic feats in nature and might enable the extraordinary long flights of migratory birds as well.     

Relationship of the Perceived Social and Physical Environment with Mental Health-Related Quality of Life in Middle-Aged and Older Adults: Mediating Effects of Physical Activity

Background

Mental health conditions are among the leading non-fatal diseases in middle-aged and older adults in Australia. Proximal and distal social environmental factors and physical environmental factors have been associated with mental health, but the underlying mechanisms explaining these associations remain unclear. The study objective was to examine the contribution of different types of physical activity in mediating the relationship of social and physical environmental factors with mental health-related quality of life in middle-aged and older adults.

Methods

Baseline data from the Wellbeing, Eating and Exercise for a Long Life (WELL) study were used. WELL is a prospective cohort study, conducted in Victoria, Australia. Baseline data collection took place in 2010. In total, 3,965 middle-aged and older adults (55–65 years, 47.4% males) completed the SF-36 Health Survey, the International Physical Activity Questionnaire, and a questionnaire on socio-demographic, social and physical environmental attributes. Mediation analyses were conducted using the MacKinnon product-of-coefficients test.

Results

Personal safety, the neighbourhood physical activity environment, social support for physical activity from family or friends, and neighbourhood social cohesion were positively associated with mental health-related quality of life. Active transportation and leisure-time physical activity mediated 32.9% of the association between social support for physical activity from family or friends and mental health-related quality of life. These physical activity behaviours also mediated 11.0%, 3.4% and 2.3% respectively, of the relationship between the neighbourhood physical activity environment, personal safety and neighbourhood social cohesion and mental health-related quality of life.

Conclusions

If these results are replicated in future longitudinal studies, tailored interventions to improve mental health-related quality of life in middle-aged and older adults should use a combined strategy, focusing on increasing physical activity as well as social and physical environmental attributes.     

Interrelation of Sport Participation,Physical Activity,Social Capital and Mental Health in Disadvantaged Communities: A SEM-Analysis

Background

The Health through Sport conceptual model links sport participation with physical, social and psychological outcomes and stresses the need for more understanding between these outcomes. The present study aims to uncover how sport participation, physical activity, social capital and mental health are interrelated by examining these outcomes in one model.

Methods

A cross-sectional survey was conducted in nine disadvantaged communities in Antwerp (Belgium). Two hundred adults (aged 18–56) per community were randomly selected and visited at home to fill out a questionnaire on socio-demographics, sport participation, physical activity, social capital and mental health. A sample of 414 adults participated in the study.

Results

Structural Equation Modeling analysis showed that sport participation (β = .095) and not total physical activity (β = .027) was associated with better mental health. No association was found between sport participation and community social capital (β = .009) or individual social capital (β = .045). Furthermore, only community social capital was linked with physical activity (β = .114), individual social capital was not (β = -.013). In contrast, only individual social capital was directly associated with mental health (β = .152), community social capital was not (β = .070).

Conclusion

This study emphasizes the importance of sport participation and individual social capital to improve mental health in disadvantaged communities. It further gives a unique insight into the functionalities of how sport participation, physical activity, social capital and mental health are interrelated. Implications for policy are that cross-sector initiatives between the sport, social and health sector need to be supported as their outcomes are directly linked to one another.