A Model for Sclerotinia sclerotiorum Infection and Disease Development in Lettuce,Based on the Effects of Temperature,Relative Humidity and Ascospore Density

The plant pathogen Sclerotinia sclerotiorum can cause serious losses on lettuce crops worldwide and as for most other susceptible crops, control relies on the application of fungicides, which target airborne ascospores. However, the efficacy of this approach depends on accurate timing of these sprays, which could be improved by an understanding of the environmental conditions that are conducive to infection. A mathematical model for S. sclerotiorum infection and disease development on lettuce is presented here for the first time, based on quantifying the effects of temperature, relative humidity (RH) and ascospore density in multiple controlled environment experiments. It was observed that disease can develop on lettuce plants inoculated with dry ascospores in the absence of apparent leaf wetness (required for spore germination). To explain this, the model conceptualises an infection court area containing microsites (in leaf axils and close to the stem base) where conditions are conducive to infection, the size of which is modified by ambient RH. The model indicated that minimum, maximum and optimum temperatures for ascospore germination were 0.0, 29.9 and 21.7°C respectively and that maximum rates of disease development occurred at spore densities >87 spores cm⁻². Disease development was much more rapid at 80–100% RH at 20°C, compared to 50–70% RH and resulted in a greater proportion of lettuce plants infected. Disease development was also more rapid at 15–27°C compared to 5–10°C (85% RH). The model was validated by a further series of independent controlled environment experiments where both RH and temperature were varied and generally simulated the pattern of disease development well. The implications of the results in terms of Sclerotinia disease forecasting are discussed.     

The Prevalence and Implications of Human–Animal Co-Sleeping in an Australian Sample

Sleep research is characterized by an interest in humans, with the realm of animal sleep left largely to ethologists and animal scientists. However, the lives of sleep-study participants and those with sleep problems frequently involve animals. For the majority of the population in developed countries who own pets, their waking lives are impacted by the duties of animal care and ownership. For many, their sleeping lives are also impacted through sharing their bedrooms or their beds with pets. Yet, little is known about the prevalence of human–animal co-sleeping relationships or their impact on sleep. The aim of this study was to determine the prevalence and implications of human–animal co-sleeping in an Australian sample. The study uses data collected from the 2012 Sealy Sleep Census, a national online survey of sleep wellness that included a sample of 10,128 after data cleaning. The population of respondents (aged 18–74) who co-slept with pets (n = 1,018 or 10% of the sample) was then matched to a sample of respondents who did not co-sleep with pets, according to gender and age. Those who co-slept with pets took longer to fall asleep (p = 0.029), were more likely to wake up tired (p = 0.025), and although they were not more likely to wake up due to a disturbance, those who did had a greater chance of being disturbed by dog barking/animals making noises (p < 0.001). However, there were no significant differences found in total self-reported sleep length or feelings of tiredness during the day. The continued practice of co-sleeping with pets suggests that there may be some benefits such as social support and social interaction, and increased feelings of personal security. The survey provides a preliminary understanding of the prevalence and implications of human–animal co-sleeping, and highlights areas for further examination of its implications on sleep research and clinical practice.     

Exercise-induced muscle damage: effects of light exercise on damaged muscle.

The effects of performing light eccentric exercise (LB) during the period of recovery from a heavy eccentric exercise bout (HB) were studied. An experimental and a control group, each consisting of nine college age volunteers (seven women, two men) performed two HB--HB1 and HB2--14 days apart, using the elbow flexor and extensor muscles of one arm. The experimental group performed an additional LB on the day following the first HB. HB1 resulted in muscle soreness, muscle weakness, changes in elbow joint flexibility, and large delayed increases in serum creatine kinase (CK) activity. The HB2 produced smaller changes in all parameters, indicating that adaptation to the effects of eccentric exercise had occurred in the muscle. The LB did not alter muscle soreness, strength or elbow flexibility, but did reduce or delay CK activity increase after HB1. The LB had no apparent effect on adaptation to HB2.     

Current and novel polymeric biomaterials for neural tissue engineering

The nervous system is a crucial component of the body and damages to this system, either by of injury or disease, can result in serious or potentially lethal consequences. Restoring the damaged nervous system is a great challenge due to the complex physiology system and limited regenerative capacity.Polymers, either synthetic or natural in origin, have been extensively evaluated as a solution for restoring functions in damaged neural tissues. Polymers offer a wide range of versatility, in particular regarding shape and mechanical characteristics, and their biocompatibility is unmatched by other biomaterials, such as metals and ceramics. Several studies have shown that polymers can be shaped into suitable support structures, including nerve conduits, scaffolds, and electrospun matrices, capable of improving the regeneration of damaged neural tissues. In general, natural polymers offer the advantage of better biocompatibility and bioactivity, while synthetic or non-natural polymers have better mechanical properties and structural stability. Often, combinations of the two allow for the development of polymeric conduits able to mimic the native physiological environment of healthy neural tissues and, consequently, regulate cell behaviour and support the regeneration of injured nervous tissues.Currently, most of neural tissue engineering applications are in pre-clinical study, in particular for use in the central nervous system, however collagen polymer conduits aimed at regeneration of peripheral nerves have already been successfully tested in clinical trials.This review highlights different types of natural and synthetic polymers used in neural tissue engineering and their advantages and disadvantages for neural regeneration.     

The epidemiology of fasciolosis in the inter-Andean valley of Cajamarca, Peru

Fasciolosis is recognised as a major problem in dairy cattle in parts of Peru. A longitudinal study of dairy cattle in Cajamarca, Peru was used to determine the annual pattern of infection with Fasciola hepatica. After a gradual increase from January, peak egg production occurred in August/September and then dropped rapidly. Indirect indicators of infection, eosinophil counts and serum liver-enzyme activities, indicated that the major period of new infection in cattle occurred from December to May each year. Examination of snails demonstrated that, although there was no clear annual cycle in snail abundance, the majority of snails infected with cercariae were found between January and March. Climatological data indicated that there was sufficient moisture for development of the parasite during a limited period each year, coinciding with the period of maximum abundance of cercaria-infected snails, but that irrigation could substantially alter the amount of water available. Infections in tracer-calves decreased from December to September, with little or no infection occurring between June and August, but suggesting that there could be significant infection prior to December. Thus a defined annual cycle of infection was observed, where cattle acquired infection from December to May and this infection matured to produce peak egg counts in August/September which were then available to infect the intermediate host for the next cycle of infection.     

Flux Analysis of Glucose Metabolism in Rhizopus oryzae for the Purpose of Increasing Lactate Yields

A flux analysis of glucose metabolism in the filamentous fungus Rhizopus oryzae was achieved using a specific radioactivity curve-matching program, TFLUX. Glycolytic and tricarboxylic acid cycle intermediates labeled through the addition of extracellular [U-14C]glucose were isolated and purified for specific radioactivity determinations. This information, together with pool sizes and the rates of glucose utilization and end product production, provided input for flux maps of the metabolic network under two different experimental conditions. Based upon the flux analysis of this system, a mutant of R. oryzae with higher lactate and lower ethanol yields than the parent was sought for and found.     

Growth requirement for N as a criterion to assess the effects of physical manipulation on nitrate uptake fluxes in spinach

The effects of physical manipulation of hydroponically grown plants of spinach (Spinacia oleracea L., cvs Subito and Glares) on nitrate uptake fluxes were studied in a long-term experiment (3 days), and in short-term label experiments (2 h) with ¹³N-nitrate and ¹⁵N-nitrate. In the long-term experiment, net nitrate uptake rate (NNUR) was measured by following the nitrate depletion in the uptake solution, which was replaced at regular intervals. In the short-term experiments, NNUR and nitrate influx were measured by simultaneous application of ¹³N-nitrate and ¹⁵N-nitrate. Plants were gently transferred into the labelled uptake solution, as is usually done in nutrient uptake studies. In addition, a more severe physical manipulation was carried out, including blotting of the roots, to mimic pretreatments which involve more handling of the plants prior to uptake measurements. Nitrate influx was measured immediately after physical manipulation and after 2 h of recovery. To assess the impact of the physical manipulation the experimentally determined nitrate uptake fluxes were compared with the N demand for growth, defined as relative growth rate (RGR) times plant nitrogen concentration (PNC) of parallel plants, which were left undisturbed. Nitrate influx and efflux were both subject to changes after physical manipulation of the plants. Physical handling, however, did not always result in an alteration of NNUR, which complicates the determination of the length of the recovery period. The impact of the handling and the time course of the recovery depended on the severity of the disturbance and were independent of the light conditions during the experiments. Even after a gentle transfer of the plants, recovery, in most cases, was not complete within 2 h. The data emphasise the need for minimal disturbance of plants during the last hours prior to nutrient uptake measurements.