Biology subjects

Cameron, R.

Publications and source records attributed to Cameron, R..

5 recordsLinked to original sources

bioRxiv2021

Germaphobia! Does our Relationship with, and Knowledge of Biodiversity Affect our Attitudes Towards Microbes?

Germaphobia -- a pathological aversion to microorganisms -- could be contributing to an explosion in human immune-related disorders via mass sterilisation of surfaces and reduced exposure to biodiversity. Loss of biodiversity and our connectedness to nature, along with poor microbial literacy may be augmenting the negative consequences of germaphobia on ecosystem health. In this study, we created an online questionnaire to acquire data on attitudes towards, and knowledge of microbes. We collected data on nature connectedness and interactions with nature and explored the relationships between these variables. We found a significant association between attitudes towards microbes and both duration and frequency of visits to natural environments. A higher frequency of visits to nature per week, and a longer duration spent in nature per visit, significantly associated with positive attitudes towards microbes. We found no association between nature connectedness and attitudes towards microbes. We found a significant relationship between knowledge of lesser known microbial groups (e.g., identifying that fungi, algae, protozoa, and archaea are microbes) and positive attitudes towards microbes. However, we also found that people who correctly identified viruses as being microbes expressed less positive views of microbes overall -- this could potentially be attributed to a COVID-19 effect. Our results suggest that basic microbial literacy and nature engagement may be important in reducing/preventing germaphobia. The results also suggest that a virus-centric phenomenon (e.g., COVID-19) could increase broader germaphobia. As the rise of immune-related disorders and mental health conditions have been linked to germaphobia, reduced biodiversity, and non-targeted sterilisation, our findings point to a feasible strategy to potentially help ameliorate these negative consequences. A greater emphasis on microbial literacy and promoting time spent in nature could be useful in promoting resilience in human health and more positive/constructive attitudes towards the foundations of our ecosystems - the microorganisms.

scientific communication and education↗

bioRxiv2020

Exposure to Airborne Bacteria Depends upon Vertical Stratification and Vegetation Complexity

Exposure to biodiverse aerobiomes may support human health, but it is unclear which ecological factors influence exposure. Few studies have investigated near-surface green space aerobiome dynamics, and no studies have investigated aerobiome vertical stratification in different green spaces. We used columnar sampling and next generation sequencing of the bacterial 16S rRNA gene, combined with geospatial and network analyses to investigate aerobiome spatio-compositional dynamics. We show a strong effect of habitat on bacterial diversity and network complexity. We observed aerobiome vertical stratification and network complexity that was contingent on habitat type. Tree density, closer proximity, and canopy coverage associated with greater aerobiome alpha diversity. Grassland aerobiomes exhibited greater proportions of putative pathogens compared to scrub, and also stratified vertically. We provide new insights into the urban ecosystem with potential importance for public health, whereby the possibility of differential aerobiome exposures appears to depend on habitat type and height in the airspace.

ecology↗

bioRxiv2020

Population analysis of Legionella pneumophila reveals the basis of resistance to complement-mediated killing

Legionella pneumophila is the most common cause of the severe respiratory infection known as Legionnaires disease. L. pneumophila is typically a symbiont of free-living amoeba, and our understanding of the bacterial factors that determine human pathogenicity is limited. Here we carried out a population genomic study of 900 L. pneumophila isolates from human clinical and environmental samples to examine their genetic diversity, global distribution and the basis for human pathogenicity. We found that although some clones are more commonly associated with clinical infections, the capacity for human disease is representative of the breadth of species diversity. To investigate the bacterial genetic basis for human disease potential, we carried out a genome-wide association study that identified a single gene (lag-1), to be most strongly associated with clinical isolates. Molecular evolutionary analysis showed that lag-1, which encodes an O-acetyltransferase responsible for lipopolysaccharide modification, has been distributed horizontally across all major phylogenetic clades of L. pneumophila by frequent recent recombination events. Functional analysis revealed a correlation between the presence of a functional lag-1 gene and resistance to killing in human serum and bovine broncho-alveolar lavage. In addition, L. pneumophila strains that express lag-1 escaped complement-mediated phagocytosis by neutrophils. Importantly, we discovered that the expression of lag-1 confers the capacity to evade complement-mediated killing by inhibiting deposition of classical pathway molecules on the bacterial surface. In summary, our combined population and functional analyses identified L. pneumophila genetic traits linked to human disease and revealed the molecular basis for resistance to complement-mediated killing, a previously elusive trait of direct relevance to human disease pathogenicity. SignificanceLegionella pneumophila is an environmental bacterium associated with a severe pneumonia known as Legionnaires disease. A small number of L. pneumophila clones are responsible for a large proportion of human infections suggesting they have enhanced pathogenicity. Here, we employed a large-scale population analysis to investigate the evolution of human pathogenicity and identified a single gene (lag-1) that was more frequently found in clinical isolates. Functional analysis revealed that the lag-1-encoded O-acetyltransferase, involved in modification of lipopolysaccharide, conferred resistance to the classical pathway of complement in human serum. These findings solve a long-standing mystery in the field regarding L. pneumophila resistance to serum killing, revealing a novel mechanism by which L. pneumophila may avoid immune defences during infection.

microbiology↗

bioRxiv2020

Vertical Stratification in Urban Green Space Aerobiomes

Exposure to a diverse environmental microbiome is thought to play an important role in ‘educating’ the immune system and facilitating competitive exclusion of pathogens to maintain human health. Vegetation and soil are known to be key sources of airborne microbiota––the aerobiome. Only a limited number of studies have attempted to characterise the dynamics of the aerobiome, and no studies to date have investigated these dynamics from a vertical perspective simulating human exposure. Studies of pollution and allergenic pollen show vertical stratification at various scales, and present an expectation that such vertical stratification may also be present in the aerobiome. Such stratification could have important implications for public health and for the design, engineering and management of urban green spaces. For example, do children receive the same exposure to airborne microbiota as taller adults, and what are the downstream implications for health? In this study, we combine an innovative columnar sampling method at soil level, 0.0, 0.5, 1.0, and 2.0 m together with high-throughput sequencing of the bacterial 16S rRNA gene to assess whether significant vertical stratification of the aerobiome occurred in a parkland habitat in Adelaide, South Australia. Our results provide evidence of vertical stratification in both alpha and beta (compositional) diversity of airborne bacterial communities, with diversity increasing roughly with height. We also found significant vertical stratification in known pathogenic and beneficial bacterial taxa, suggesting potentially different exposure attributes between adults and children. These results could have important implications for public health and urban planning, potentially informing ways to optimise the design and management of health-promoting urban green spaces.Competing Interest StatementThe authors have declared no competing interest.View Full Text

ecology↗

bioRxiv2019

A neuronal signature for monogamous reunion

Pair bond formation depends vitally on neuromodulatory signaling within the nucleus accumbens, but the neuronal dynamics underlying this behavior remain unclear. Using in vivo Ca2+ imaging in monogamous prairie voles, we found that pair bonding does not elicit differences in overall nucleus accumbens Ca2+ activity. Instead, we identified distinct neuronal ensembles in this region recruited during approach to either a partner or novel vole. The partner-approach neuronal ensemble increased in size following bond formation and differences in the size of approach ensembles for partner and novel voles predicts bond strength. In contrast, neurons comprising departure ensembles do not change over time and are not correlated with bond strength indicating that ensemble plasticity is specific to partner approach. Further, the neurons comprising partner and novel approach ensembles are non-overlapping while departure ensembles are more overlapping than chance, which may reflect another key feature of approach ensembles. We posit that the features of the partner approach ensemble and its expansion upon bond formation make it a potential key substrate underlying bond formation and maturation.\n\nHighlightsO_LIWe performed in vivo Ca2+ in the nucleus accumbens of pair bonded prairie voles\nC_LIO_LIOverall nucleus accumbens activity did not differ during partner versus stranger interaction\nC_LIO_LIDistinct approach neurons exist for the partner and for the stranger\nC_LIO_LIPartner-approach ensemble increases as partner preference emerges\nC_LIO_LIWe identify a putative neuronal substrate underlying bond formation and maturation\nC_LI

neuroscience↗