The Role of Viral Systems in Nutrient Cycling

The Te Arawa/Rotorua lakes located in the central North Island of New Zealand have significant cultural, historic, social and economic value. Anthropogenic changes in land use have led to a decline in water quality in some lakes. A number of lakes have accelerated eutrophication with recurring cyanobacterial blooms and periods of bottom-water anoxia. Whilst there has been extensive research undertaken on phytoplankton dynamics in freshwater lakes there is little information on the abundance and activity of viral-like particles (VLPs) and bacteria. VLPs are the most abundant biological entities in aquatic environments and play an important role in carbon and nutrient cycling, reproducing either by cell lysis or replication in the host cell. Bacterial community structure is thought to be closely linked to the viral community and bacterial taxa have a key role in biochemical cycling in freshwater systems. Two Te Arawa/Rotorua monomictic lakes differing in their trophic status; oligotrophic Lake Tikitapu and eutrophic Lake Okaro, were sampled over a 12-month period at the surface (epilimnion) and bottom (hypolimnion) and through a discrete layer of the thermocline during stratification. The thermocline is a region where there may be steep clines in physiochemical parameters (e.g., dissolved oxygen) which may strongly affect the distribution of, and environmental factors that influence, prokaryotes, protozoa and viruses. Physiochemical variables, nutrients, microbiological and molecular analyses were undertaken on samples in order to compare and contrast changes occurring within and between the two lakes. Both lakes were strongly stratified for c. 8 months from September 2009 to June 2010 as indicated by Schmidt stability values > 1, which contributed to well-lit but nutrient-limited surface waters for phytoplankton productivity. With increasing duration of stratification a deep chlorophyll maximum formed in both lakes with Chlorophyta and Euglenophyta the dominant phytoplankton. Viral-like particle abundance in both lakes exceeded bacterial abundance by a factor of c. 100, with maximum VLP and bacterial abundances in both lakes c. 10⁸ cells mL-¹ and 10⁶ cells mL-¹, respectively. Bacterial abundance in both lakes was similar in the epilimnion and hypolimnion during stratification with the exception of a peak (2 x 10⁷ cells mL-¹) in the epilimnion of Lake Okaro in February 2010 (and in the hypolimnion (9.74 x 10⁶ cells mL-¹) in March 2010 of in Lake Tikitapu. Viral-like particle abundance was variable but the epilimnion and hypolimnion tracked in both lakes between August 2009 and January 2010 after which Lake Okaro epilimnion and hypolimnion remained steady with Lake Tikitapu hypolimnion showing considerably higher VLP abundance than the epilimnion before tracking together in June 2010. The abundance of the following bacterial functional genes was monitored through the study; nifH (encoding the nitrogenase reductase protein), dsrA (encoding the sulphate reductase protein), mcrA (encoding the methyl coenzyme M reductase protein), amoA (encoding the ammonium oxidising protein and nosZ (encoding for the nitrous oxide reductase protein). The occurrence of the nifH gene correlated with increased abundance of cyanobacteria capable of fixing nitrogen in the epilimnion of both lakes while the dsrA gene was more abundant in Lake Okaro, likely due to higher organic matter concentrations and greater duration and spatial extent of reducing conditions in that lake. Abundance of mcrA was expected to be high in the anoxic waters of the nutrient rich sediment of Lake Okaro but there was very low abundance. The amoA genes were detected when concentrations of ammonium were elevated in the bottom waters of both lakes. Both lakes showed the presence nosZ genes with high abundance occurring in Lake Okaro in December 2009 through all levels and also in December 2009 in Lake Tikitapu in the epilimnion and hypolimnion. With denitrification reliant on the availability of nitrate (NO3-N) and dissolved organic carbon levels and performed by obligate and facultative anaerobes, conditions need to be precise for the process to occur

Fall hazard control observed on residential construction sites

BACKGROUND: Falls are a leading cause of mortality and morbidity in the construction industry. This study measured fall hazards at residential construction sites. METHODS: Trained carpenters administered the St. Louis Audit of Fall Risks and interviewed carpenters. The prevalence of fall prevention practices meeting safety criteria was counted and correlations explored. RESULTS: We identified a high prevalence of fall hazards at the 197 residential sites audited. Roof sheathing met safety criteria most consistently (81%) and truss setting least consistently (28%). Use of personal fall arrest and monitoring of unguarded floor openings were rare. Safer performance on several scales was correlated. Construction sites of large-sized contractors were generally safer than smaller contractors. Apprentice carpenters were less familiar with their employers’ fall prevention plan than experienced workers. CONCLUSIONS: Safety could be improved with consistent use of recognized fall prevention practices at residential construction sites

Brain‐wide associations between white matter and age highlight the role of fornix microstructure in brain ageing

Unveiling the details of white matter (WM) maturation throughout ageing is a fundamental question for understanding the ageing brain. In an extensive comparison of brain age predictions and age-associations of WM features from different diffusion approaches, we analyzed UK Biobank diffusion magnetic resonance imaging (dMRI) data across midlife and older age (N = 35,749, 44.6–82.8 years of age). Conventional and advanced dMRI approaches were consistent in predicting brain age. WM-age associations indicate a steady microstructure degeneration with increasing age from midlife to older ages. Brain age was estimated best when combining diffusion approaches, showing different aspects of WM contributing to brain age. Fornix was found as the central region for brain age predictions across diffusion approaches in complement to forceps minor as another important region. These regions exhibited a general pattern of positive associations with age for intra axonal water fractions, axial, radial diffusivities, and negative relationships with age for mean diffusivities, fractional anisotropy, kurtosis. We encourage the application of multiple dMRI approaches for detailed insights into WM, and the further investigation of fornix and forceps as potential biomarkers of brain age and ageing.publishedVersio

A large proportion of asymptomatic Plasmodium infections with low and sub-microscopic parasite densities in the low transmission setting of Temotu Province, Solomon Islands: challenges for malaria diagnostics in an elimination setting

Background: Many countries are scaling up malaria interventions towards elimination. This transition changes demands on malaria diagnostics from diagnosing ill patients to detecting parasites in all carriers including asymptomatic infections and infections with low parasite densities. Detection methods suitable to local malaria epidemiology must be selected prior to transitioning a malaria control programme to elimination. A baseline malaria survey conducted in Temotu Province, Solomon Islands in late 2008, as the first step in a provincial malaria elimination programme, provided malaria epidemiology data and an opportunity to assess how well different diagnostic methods performed in this setting

Bio-psycho-social factors’ associations with brain age: a large-scale UK Biobank diffusion study of 35,749 participants

Brain age refers to age predicted by brain features. Brain age has previously been associated with various health and disease outcomes and suggested as a potential biomarker of general health. Few previous studies have systematically assessed brain age variability derived from single and multi-shell diffusion magnetic resonance imaging data. Here, we present multivariate models of brain age derived from various diffusion approaches and how they relate to bio-psycho-social variables within the domains of sociodemographic, cognitive, life-satisfaction, as well as health and lifestyle factors in midlife to old age (N = 35,749, 44.6–82.8 years of age). Bio-psycho-social factors could uniquely explain a small proportion of the brain age variance, in a similar pattern across diffusion approaches: cognitive scores, life satisfaction, health and lifestyle factors adding to the variance explained, but not socio-demographics. Consistent brain age associations across models were found for waist-to-hip ratio, diabetes, hypertension, smoking, matrix puzzles solving, and job and health satisfaction and perception. Furthermore, we found large variability in sex and ethnicity group differences in brain age. Our results show that brain age cannot be sufficiently explained by bio-psycho-social variables alone. However, the observed associations suggest to adjust for sex, ethnicity, cognitive factors, as well as health and lifestyle factors, and to observe bio-psycho-social factor interactions’ influence on brain age in future studies.publishedVersio

Associations between abdominal adipose tissue, reproductive span, and brain characteristics in post-menopausal women

The menopause transition involves changes in oestrogens and adipose tissue distribution, which may influence female brain health post-menopause. Although increased central fat accumulation is linked to risk of cardiometabolic diseases, adipose tissue also serves as the primary biosynthesis site of oestrogens post-menopause. It is unclear whether different types of adipose tissue play diverging roles in female brain health post-menopause, and whether this depends on lifetime oestrogen exposure, which can have lasting effects on the brain and body even after menopause. Using the UK Biobank sample, we investigated associations between brain characteristics and visceral adipose tissue (VAT) and abdominal subcutaneous adipose tissue (ASAT) in 10,251 post-menopausal females, and assessed whether the relationships varied depending on length of reproductive span (age at menarche to age at menopause). To parse the effects of common genetic variation, we computed polygenic scores for reproductive span. The results showed that higher VAT and ASAT were both associated with higher grey and white matter brain age, and greater white matter hyperintensity load. The associations varied positively with reproductive span, indicating more prominent associations between adipose tissue and brain measures in females with a longer reproductive span. The effects were in general small, but could not be fully explained by genetic variation or relevant confounders. Our findings indicate that associations between abdominal adipose tissue and brain health post-menopause may partly depend on individual differences in cumulative oestrogen exposure during reproductive years, emphasising the complexity of neural and endocrine ageing processes in females

Dissecting unique and common variance across body and brain health indicators using age prediction

Ageing is a heterogeneous multisystem process involving different rates of decline in physiological integrity across biological systems. The current study dissects the unique and common variance across body and brain health indicators and parses inter‐individual heterogeneity in the multisystem ageing process. Using machine‐learning regression models on the UK Biobank data set (N = 32,593, age range 44.6–82.3, mean age 64.1 years), we first estimated tissue‐specific brain age for white and gray matter based on diffusion and T1‐weighted magnetic resonance imaging (MRI) data, respectively. Next, bodily health traits, including cardiometabolic, anthropometric, and body composition measures of adipose and muscle tissue from bioimpedance and body MRI, were combined to predict ‘body age’. The results showed that the body age model demonstrated comparable age prediction accuracy to models trained solely on brain MRI data. The correlation between body age and brain age predictions was 0.62 for the T1 and 0.64 for the diffusion‐based model, indicating a degree of unique variance in brain and bodily ageing processes. Bayesian multilevel modelling carried out to quantify the associations between health traits and predicted age discrepancies showed that higher systolic blood pressure and higher muscle‐fat infiltration were related to older‐appearing body age compared to brain age. Conversely, higher hand‐grip strength and muscle volume were related to a younger‐appearing body age. Our findings corroborate the common notion of a close connection between somatic and brain health. However, they also suggest that health traits may differentially influence age predictions beyond what is captured by the brain imaging data, potentially contributing to heterogeneous ageing rates across biological systems and individuals

Social stratification without genetic differentiation at the site of Kulubnarti in Christian Period Nubia

Relatively little is known about Nubia’s genetic landscape prior to the influence of the Islamic migrations that began in the late 1st millennium CE. Here, we increase the number of ancient individuals with genome-level data from the Nile Valley from three to 69, reporting data for 66 individuals from two cemeteries at the Christian Period (~650–1000 CE) site of Kulubnarti, where multiple lines of evidence suggest social stratification. The Kulubnarti Nubians had ~43% Nilotic-related ancestry (individual variation between ~36–54%) with the remaining ancestry consistent with being introduced through Egypt and ultimately deriving from an ancestry pool like that found in the Bronze and Iron Age Levant. The Kulubnarti gene pool – shaped over a millennium – harbors disproportionately female-associated West Eurasian-related ancestry. Genetic similarity among individuals from the two cemeteries supports a hypothesis of social division without genetic distinction. Seven pairs of inter-cemetery relatives suggest fluidity between cemetery groups. Present-day Nubians are not directly descended from the Kulubnarti Nubians, attesting to additional genetic input since the Christian Period.K.A.S. was supported by a Doctoral Dissertation Research Improvement Grant from the National Science Foundation (BCS-1613577). D.R. was funded by NSF HOMINID grant BCS-1032255; NIH (NIGMS) grant GM100233; the Allen Discovery Center program, a Paul G. Allen Frontiers Group advised program of the Paul G. Allen Family Foundation; the John Templeton Foundation grant 61220; and the Howard Hughes Medical Institute