Pontine A5 region modulation of the cardiorespiratory response evoked from the midbrain dorsolateral periaqueductal grey

Journal of Physiology and Biochemistry - Connections between the midbrain dorsolateral periaqueductal grey (dlPAG) and the pontine A5 region have been shown. The stimulation of both regions evokes...     

The biology and feeding ecology of Arctic charr in the Kerguelen Islands

Subsequent to their introduction in the 1950s, Arctic charr Salvelinus alpinus have been able to establish a self-sustaining population that has adapted to the unique conditions of the sub-Antarctic Kerguelen Islands. Here, 48 individuals (198–415 mm) were caught with gillnets and their basic biology and feeding ecology were examined using stable isotope analysis. The Lac des Fougères population split use of littoral and pelagic resources evenly, although larger fish relied more heavily on littoral production and appear to follow the size-dependent life history habitat template seen in many Scandinavian lakes where smaller sized individuals occupy the pelagic zone and larger individuals dominate the littoral habitat. In Kerguelen, Arctic charr mature at the same ages (5.6 years) as Arctic charr in both sub-Arctic and Arctic lakes. Although mortality was average in comparison to comparator sub-Arctic lakes, it was high in comparison to Arctic lakes. Maximal age (>7+) was at the lower end of the range typically seen in sub-Arctic lakes. Although they inhabit a resource-poor environment, Kerguelen Arctic charr showed no evidence of cannibalism. Thus, while Arctic charr can survive and reproduce in the relatively unproductive Kerguelen lake environments, survival and growth nevertheless appear to be traded off against survival and longevity. The uniqueness of the population location and the recency of its introduction suggest that further monitoring of the population has the potential to yield valuable insights into both the adaptability of the species and its likely responses to ongoing large-scale environmental change as represented by climate change.     

Understorey plant community assemblage of Australian Eucalyptus woodlands under elevated CO2 is modulated by water and phosphorus availability

水分和磷调控的澳大利亚桉树林林下植物群落组合对二氧化碳浓度升高的响应 鉴于林下植物群落具有的关键性功能作用和全球范围内巨大的森林覆盖面积,研究林下群落对 CO₂浓度升高(eCO₂)的响应以及土壤资源在这些响应中的作用,对于了解CO₂浓度升高对森林生态系统造成的影响非常重要。本研究评估了在澳大利亚东部磷有限的桉树林林下群落中,两种限制性的资源(即水分和磷)在发芽、物候、覆盖率、群落组成和叶片性状等方面对eCO₂响应的作用。我们收集了含有当地土壤种子库的土壤,在温室条件下种植实验性的林下植物群落。研究结果表明,添加磷提高了植物的总体覆盖率,特别是在生长期的最初4 周以及水分含量高的条件下,而且该响应是由植物群落中的类禾本科植物所驱动。然而,随着实验的进行,不同处理方法之间的差异逐渐减小,所有处理在大约11周后均达到了80%左右的植物覆盖率。相反,植物覆盖率并未受到eCO₂ 的影响。多元分析结果反映出植物群落组成随时间的变化,盆栽从以裸土为主变为以高覆盖率的多样化群落为主。但是在实验过程中,磷的添加以及水分可利用性和CO₂之间的相互作用都对植物群落随时间的变化轨迹有所影响。CO₂浓度的升高也增加了群落水平的比叶面积,这表明植物群落对eCO₂的功能适应可能发生在成分响应开始之前。鉴于我们用种子库培育的林下群落对eCO₂ 的响应随着时间的推移而有 所变化,并且受到与磷和水分可利用性的相互作用的调节。我们的结果表明,在水分含量有限的系统中, 特别是在土壤养分可利用性低所导致的生产力响应受限的情况下,CO₂浓度的升高在塑造植物群落方面作用有限。     

Control of (Multi)Drug Resistance and Tuberculosis Incidence over 23 Years in the Context of a Well-Supported Tuberculosis Programme in Rural Malawi

Background

The rise in tuberculosis (TB) incidence following generalized HIV epidemics can overwhelm TB control programmes in resource-limited settings, sometimes accompanied by rising rates of drug resistance. This has led to claims that DOTS-based TB control has failed in such settings. However, few studies have described the effect of a sustained and well-supported DOTS programme on TB incidence and drug resistance over a long period. We present long-term trends in incidence and drug resistance in rural Malawi.

Methods

Karonga District in northern Malawi has an adult HIV prevalence of ∼10%. A research group, the Karonga Prevention Study, collaborates with the National Tuberculosis Programme to support core TB control activities. Bacteriological, demographic and clinical (including HIV status) information from all patients starting TB treatment in the District have been recorded since 1988. During that period isolates from each culture-positive TB patient were exported for drug sensitivity testing. Antiretroviral therapy (ART) has been widely available since 2005.

Results

Incidence of new smear-positive adult TB peaked at 124/100,000/year in the mid-90s, but has since fallen to 87/100,000/year. Drug sensitivity information was available for 95% (3132/3307) of all culture-positive cases. Initial resistance to isoniazid was around 6% with no evidence of an increase. Fewer than 1% of episodes involved a multi-drug resistant strain.

Discussion

In this setting with a generalised HIV epidemic and medium TB burden, a well-supported DOTS programme enhanced by routine culture and drug sensitivity testing may well have reduced TB incidence and maintained drug resistance at low levels.     

Sedentary Behaviours in Mid-Adulthood and Subsequent Body Mass Index

Objectives

It is unclear whether sedentary behaviour, and the domain in which it occurs, is related to body mass index (BMI) change. We aim to elucidate whether sedentary behaviour is prospectively related to BMI change using markers from three domains (leisure, work and commuting).

Methods

Among employed 1958 British birth cohort members (n = 6,562), we analysed whether TV-viewing, work sitting (six categories: 0 h/d to >4 h/d) and motorised commuting (at 45 y) were related to BMI (at 45 y and 50 y) and BMI change 45–50 y, after adjusting for lifestyle and socioeconomic factors.

Results

Per category higher TV-viewing, 45 y and 50 y BMI were higher by 0.69 kg/m² (95% CI: 0.59,0.80) and 0.75 kg/m² (0.64,0.86) respectively. A category higher TV-viewing was associated with 0.11 kg/m² (0.06,0.17) increased BMI 45–50 y, attenuating to 0.06 kg/m² (0.01,0.12) after adjustment. There was no trend for work sitting with 45 y or 50 y BMI, nor, after adjustment, for BMI change. However, those sitting 2–3 h/d had greater BMI gain by 0.33 kg/m² (0.10,0.56) compared to those sitting 0–1 h/d. Associations between TV-viewing and BMI change were independent of work sitting. Motorised commuting was associated with 45 y, but not 50 y BMI or change.

Conclusions

TV-viewing is associated with BMI gain in mid-adulthood; evidence is weaker for other sedentary behaviours.     

Disability Affects the 6-Minute Walking Distance in Obese Subjects (BMI>40 kg/m2)

Introduction

In obese subjects, the relative reduction of the skeletal muscle strength, the reduced cardio-pulmonary capacity and tolerance to effort, the higher metabolic costs and, therefore, the increased inefficiency of gait together with the increased prevalence of co-morbid conditions might interfere with walking. Performance tests, such as the six-minute walking test (6MWT), can unveil the limitations in cardio-respiratory and motor functions underlying the obesity-related disability. Therefore the aims of the present study were: to explore the determinants of the 6-minute walking distance (6MWD) and to investigate the predictors of interruption of the walk test in obese subjects.

Methods

Obese patients [body mass index (BMI)>40 kg/m²] were recruited from January 2009 to December 2011. Anthropometry, body composition, specific questionnaire for Obesity-related Disabilities (TSD-OC test), fitness status and 6MWT data were evaluated. The correlation between the 6MWD and the potential independent variables (anthropometric parameters, body composition, muscle strength, flexibility and disability) were analysed. The variables which were singularly correlated with the response variable were included in a multivariated regression model. Finally, the correlation between nutritional and functional parameters and test interruption was investigated.

Results

354 subjects (87 males, mean age 48.5±14 years, 267 females, mean age 49.8±15 years) were enrolled in the study. Age, weight, height, BMI, fat mass and fat free mass indexes, handgrip strength and disability were significantly correlated with the 6MWD and considered in the multivariate analysis. The determination coefficient of the regression analysis ranged from 0.21 to 0.47 for the different models. Body weight, BMI, waist circumference, TSD-OC test score and flexibility were found to be predictors of the 6MWT interruption.

Discussion

The present study demonstrated the impact of disability in obese subjects, together with age, anthropometric data, body composition and strength, on the 6-minute walking distance.     

Estimation of Parameters Influencing Waterborne Transmission of Infectious Hematopoietic Necrosis Virus (IHNV) in Atlantic Salmon (Salmo salar)

Understanding how pathogenic organisms spread in the environment is crucial for the management of disease, yet knowledge of propagule dispersal and transmission in aquatic environments is limited. We conducted empirical studies using the aquatic virus, infectious hematopoietic necrosis virus (IHNV), to quantify infectious dose, shedding capacity, and virus destruction rates in order to better understand the transmission of IHN virus among Atlantic salmon marine net-pen aquaculture. Transmission of virus and subsequent mortality in Atlantic salmon post-smolts was initiated with as low as 10 plaque forming units (pfu) ml⁻¹. Virus shedding from IHNV infected Atlantic salmon was detected before the onset of visible signs of disease with peak shed rates averaging 3.2×10⁷ pfu fish⁻¹ hour⁻¹ one to two days prior to mortality. Once shed into the marine environment, the abundance of free IHNV is modulated by sunlight (UV A and B) and the growth of natural biota present in the seawater. Virus decayed very slowly in sterilized seawater while rates as high as k =  4.37 d⁻¹ were observed in natural seawater. Decay rates were further accelerated when exposed to sunlight with virus infectivity reduced by six orders of magnitude within 3 hours of full sunlight exposure. Coupling the IHNV transmission parameter estimates determined here with physical water circulation models, will increase the understanding of IHNV dispersal and provide accurate geospatial predictions of risk for IHNV transmission from marine salmon sites.     

Phytoextraction of high value elements and contaminants from mining and mineral wastes: opportunities and limitations

Plant and Soil - Phytoextraction is an in situ technique that can be applied to minerals and mining wastes using hyperaccumulator plants to purposely bio-concentrate high levels of metals or...     

Rice yield formation under high day and night temperatures—A prerequisite to ensure future food security

Increasing temperatures resulting from climate change dramatically impact rice crop production in Asia. Depending on the specific stage of rice development, heat stress reduces tiller/panicle number, decreases grain number per plant and lower grain weight, thus negatively impacting yield formation. Hence improving rice crop tolerance to heat stress in terms of sustaining yield stability under high day temperature (HDT), high night temperature (HNT), or combined high day and night temperature (HDNT) will bolster future food security. In this review article, we highlight the phenological alterations caused by heat and the underlying molecular-physiological and genetic mechanisms operating under different types of heat conditions (HDT, HNT, and HDNT) to understand heat tolerance. Based on our synthesis of HDT, HNT, and HDNT effects on rice yield components, we outline future breeding strategies to contribute to sustained food security under climate change.