Differing preferences of Antarctic soil nematodes for microbial prey

We tested the preferences of three nematode taxa, Geomonhystera villosa, Plectus spp. and Teratocephalus spp., extracted from moss at Signy Island in the Maritime Antarctic, for two microalgae, three microfungi and six heterotrophic bacteria, each also from soils at Signy Island. Choice test experiments on water agar medium, in which nematodes were enumerated in wells containing microbes at 24 and 48 h, indicated that there were differing preferences between nematodes for distinct prey. G. villosa was significantly attracted to the alga Chlorella cf. minutissima and the fungus Mortierella hyalina, and was more attracted to all algae and fungi than either of the other two nematodes. Both G. villosa and Teratocephalus spp. were attracted to an actinobacterium. Plectus spp. were significantly attracted to the alga Stichococcus bacillaris and bacteria with close taxonomic affinities to Arthrobacter, Pseudomonas and Polaromonas. Experiments using 0.5 μm diameter fluorescent beads indicated significantly increased ingestion by nematodes in the presence of each of these microbes compared with controls, except by Plectus spp. in the presence of S. bacillaris. We conclude that complex trophic interactions may occur in apparently simple Antarctic soil food webs

The importance of contrast sensitivity testing in children

Aim: To discuss the information contrast sensitivity (CS) testing can provide over visual acuity testing, and review the literature relating to CS deficits in children to determine whether there is an optimum test available. Methods: A literature search of databases available through the University of Liverpool library was performed. All searches related to the importance of CS in children, paediatric conditions affecting CS and current clinical tests available for the assessment of CS. Results: Many paediatric conditions exist where CS is defective, often despite ‘normal’ visual acuity (VA): for example, optic pathway gliomas, myopia and primary congenital glaucoma. The finding of a loss of CS has been found to be more prominent and disturbing to an individual than a loss of VA, emphasising the importance of CS assessments in children. Therefore, the clinical assessment of CS in children is valuable in terms of strategies to support the child and establishing the individual’s functional level of vision. Unfortunately, current paediatric clinical tests of CS have failed to demonstrate the same standards and repeatability and reliability as adult tests for the assessment of CS. Conclusions: The range of functional deficits that accompany paediatric ocular disease require more assessments for full evaluation of visual function than standard VA tests. However, reliable assessments for paediatric CS are limited. A new paediatric CS test may be of clinical value

Fiat Lux: the effect of illuminance on acuity testing

PURPOSE: To determine the effect of changing illuminance on visual and stereo acuity. METHODS: Twenty-eight subjects aged 21 to 60 years were assessed. Monocular visual acuity (ETDRS) of emmetropic subjects was assessed under 15 different illuminance levels (50–8000 lux), provided by a computer controlled halogen lighting rig. Three levels of myopia (−0.50DS, −1.00DS & 1.50DS) were induced in each subject using lenses and visual acuity (VA) was retested under the same illuminance conditions. Stereoacuity (TNO) was assessed under the same levels of illuminance. RESULTS: A one log unit change in illuminance level (lx) results in a significant change of 0.060 LogMAR (p < 0.001), an effect that is exacerbated in the presence of induced myopic refractive error (p < 0.001). Stereoacuity scores demonstrate statistically significant overall differences between illuminance levels (p < 0.001). CONCLUSIONS: The findings of this study demonstrate that changes in illuminance have a statistically significant effect on VA that may contribute to test/retest variability. Increases in illuminance from 50 to 500 lx resulted in an improved VA score of 0.12 LogMAR. Differences like these have significant clinical implications, such as false negatives during vision screening and non-detection of VA deterioration, as the full magnitude of any change may be hidden. In research where VA is a primary outcome measure, differences of 0.12 LogMAR or even less could affect the statistical significance and conclusions of a study. It is recommended that VA assessment always be performed between 400 lx and 600 lx, as this limits any effect of illuminance change to 0.012 LogMAR

Tackling Poverty in a Changing Climate: Bridging Concepts and Practice for Low Carbon Climate Resilient Development

The Learning Hub is a transformative way of learning and sharing, bridging academic knowledge with invaluable insights from frontline practical experience. The Hub’s second learning cycle focused on perhaps the overarching challenge at the heart of climate change and development. How do we ensure that we tackle poverty and its root causes in ways that are adaptive and low-carbon? The two main ways that were used to explore this question were a) the framing paper and b) the learning event, held in Addis Ababa in March 2011. The purpose of this paper is to bridge the thinking and learning that came out of the framing paper and the debates sparked by it at the learning event

Visual risk factors for falls in older adults: a case-control study

BACKGROUND: Falls are the second leading  cause of accidental deaths worldwide mainly in older people. Older people have poor vision and published evidence suggests that it is a risk factor for falls. Less than half of falls clinics assess vision as part of the multi-factorial assessment of older adults at risk of falls despite vision being an essential input for postural stability. The aim of our study was to investigate the relationship between all clinically assessed visual functions and falls amongst older adults in a prospective observational individually age-matched case control study. METHODS: Visual acuity (VA), contrast sensitivity (CS), depth perception, binocular vision and binocular visual field were measured using routinely used clinical methods in falls participants (N = 83) and non-falls participants (N = 83). Data were also collected on socio-demographic factors, general health, number of medications, health quality, fear of falling and physical activity. Logistic regression analysis was carried out to determine key visual and non-visual risk factors for falls whilst adjusting for confounding covariates. RESULTS: Older adults have an increased risk of experiencing a fall if they have reduced visual function (odds ratio (OR): 3.49, 1.64-7.45, p = 0.001), specifically impaired stereoacuity worse than 85” of arc (OR: 3.4, 1.20-9.69, p = 0.02) and reduced (by 0.15 log unit) high spatial frequency CS (18 cpd) (OR:1.40, 1.12-1.80, p = 0.003). Older adults with a hearing impairment are also at higher risk of falls (OR: 3.18, 95% CI: 1.36-7.40, p = 0.007). The risk decreases with living in a less deprived area (OR: 0.74, 0.64-0.86, <0.001), or socialising more out of the home (OR: 0.75, 0.60-0.93, p = 0.01). CONCLUSIONS: The combination of social, behavioural and biological determinants are significant predictors of a fall. The non-visual risk factors include older adults, living in deprived neighbourhoods, socialising less outside of the home and those who have a hearing impairment. Impaired functional visual measures; depth perception and contrast are significant visual risk factors for falls above visual acuity

Experimental warming increases fungal alpha diversity in an oligotrophic maritime Antarctic soil

The climate of maritime Antarctica has altered since the 1950s. However, the effects of increased temperature, precipitation and organic carbon and nitrogen availability on the fungal communities inhabiting the barren and oligotrophic fellfield soils that are widespread across the region are poorly understood. Here, we test how warming with open top chambers (OTCs), irrigation and the organic substrates glucose, glycine and tryptone soy broth (TSB) influence a fungal community inhabiting an oligotrophic maritime Antarctic fellfield soil. In contrast with studies in vegetated soils at lower latitudes, OTCs increased fungal community alpha diversity (Simpson’s index and evenness) by 102–142% in unamended soil after 5 years. Conversely, OTCs had few effects on diversity in substrate-amended soils, with their only main effects, in glycine-amended soils, being attributable to an abundance of Pseudogymnoascus. The substrates reduced alpha and beta diversity metrics by 18–63%, altered community composition and elevated soil fungal DNA concentrations by 1–2 orders of magnitude after 5 years. In glycine-amended soil, OTCs decreased DNA concentrations by 57% and increased the relative abundance of the yeast Vishniacozyma by 45-fold. The relative abundance of the yeast Gelidatrema declined by 78% in chambered soil and increased by 1.9-fold in irrigated soil. Fungal DNA concentrations were also halved by irrigation in TSB-amended soils. In support of regional- and continental-scale studies across climatic gradients, the observations indicate that soil fungal alpha diversity in maritime Antarctica will increase as the region warms, but suggest that the accumulation of organic carbon and nitrogen compounds in fellfield soils arising from expanding plant populations are likely, in time, to attenuate the positive effects of warming on diversity. Antarctica, climate warming, open top chambers (OTCs), organic carbon, organic nitrogen, soil fungal community diversity, yeastspublishedVersio

Experimental warming increases fungal alpha diversity in an oligotrophic maritime Antarctic soil

The climate of maritime Antarctica has altered since the 1950s. However, the effects of increased temperature, precipitation and organic carbon and nitrogen availability on the fungal communities inhabiting the barren and oligotrophic fellfield soils that are widespread across the region are poorly understood. Here, we test how warming with open top chambers (OTCs), irrigation and the organic substrates glucose, glycine and tryptone soy broth (TSB) influence a fungal community inhabiting an oligotrophic maritime Antarctic fellfield soil. In contrast with studies in vegetated soils at lower latitudes, OTCs increased fungal community alpha diversity (Simpson’s index and evenness) by 102–142% in unamended soil after 5 years. Conversely, OTCs had few effects on diversity in substrate-amended soils, with their only main effects, in glycine-amended soils, being attributable to an abundance of Pseudogymnoascus. The substrates reduced alpha and beta diversity metrics by 18–63%, altered community composition and elevated soil fungal DNA concentrations by 1–2 orders of magnitude after 5 years. In glycine-amended soil, OTCs decreased DNA concentrations by 57% and increased the relative abundance of the yeast Vishniacozyma by 45-fold. The relative abundance of the yeast Gelidatrema declined by 78% in chambered soil and increased by 1.9-fold in irrigated soil. Fungal DNA concentrations were also halved by irrigation in TSB-amended soils. In support of regional- and continental-scale studies across climatic gradients, the observations indicate that soil fungal alpha diversity in maritime Antarctica will increase as the region warms, but suggest that the accumulation of organic carbon and nitrogen compounds in fellfield soils arising from expanding plant populations are likely, in time, to attenuate the positive effects of warming on diversity. Antarctica, climate warming, open top chambers (OTCs), organic carbon, organic nitrogen, soil fungal community diversity, yeastspublishedVersio

Experimental warming increases fungal alpha diversity in an oligotrophic maritime Antarctic soil

The climate of maritime Antarctica has altered since the 1950s. However, the effects of increased temperature, precipitation and organic carbon and nitrogen availability on the fungal communities inhabiting the barren and oligotrophic fellfield soils that are widespread across the region are poorly understood. Here, we test how warming with open top chambers (OTCs), irrigation and the organic substrates glucose, glycine and tryptone soy broth (TSB) influence a fungal community inhabiting an oligotrophic maritime Antarctic fellfield soil. In contrast with studies in vegetated soils at lower latitudes, OTCs increased fungal community alpha diversity (Simpson’s index and evenness) by 102–142% in unamended soil after 5 years. Conversely, OTCs had few effects on diversity in substrate-amended soils, with their only main effects, in glycine-amended soils, being attributable to an abundance of Pseudogymnoascus. The substrates reduced alpha and beta diversity metrics by 18–63%, altered community composition and elevated soil fungal DNA concentrations by 1–2 orders of magnitude after 5 years. In glycine-amended soil, OTCs decreased DNA concentrations by 57% and increased the relative abundance of the yeast Vishniacozyma by 45-fold. The relative abundance of the yeast Gelidatrema declined by 78% in chambered soil and increased by 1.9-fold in irrigated soil. Fungal DNA concentrations were also halved by irrigation in TSB-amended soils. In support of regional- and continental-scale studies across climatic gradients, the observations indicate that soil fungal alpha diversity in maritime Antarctica will increase as the region warms, but suggest that the accumulation of organic carbon and nitrogen compounds in fellfield soils arising from expanding plant populations are likely, in time, to attenuate the positive effects of warming on diversity. Antarctica, climate warming, open top chambers (OTCs), organic carbon, organic nitrogen, soil fungal community diversity, yeastspublishedVersio

Relationship between soil fungal diversity and temperature in the maritime Antarctic

Soil fungi have pivotal ecological roles as decomposers, pathogens and symbionts1, 2. Alterations to their diversity arising from climate change could have substantial effects on ecosystems, particularly those undergoing rapid warming that contain few species3, 4. Here, we report a study using pyrosequencing to assess fungal diversity in 29 soils sampled from a 1,650 km climatic gradient through the maritime Antarctic, the most rapidly warming region in the Southern Hemisphere5, 6. Using a ‘space-for-time’ substitution approach, we show that soil fungal diversity is higher in warmer habitats, with increases of 4.7 (observed) and 11.3 (predicted) fungal taxa per degree Celsius rise in surface temperature along the transect. Among 22 predictor variables, air temperature was the strongest and most consistent predictor of diversity. We propose that the current rapid warming in the maritime Antarctic (0.34 °C per decade6) will facilitate the colonization of soil by a wider diversity of fungi than at present, with data from regression models suggesting 20–27% increases in fungal species richness in the southernmost soils by 2100. Such increases in diversity, which provide a sentinel for changes at lower latitudes, are likely to have substantial effects on nutrient cycling and, ultimately, productivity in the species-poor soils of maritime Antarctica