Accounting for size-specific predation improves our ability to predict the strength of a trophic cascade.

Predation can influence the magnitude of herbivory that grazers exert on primary producers by altering both grazer abundance and their per capita consumption rates via changes in behavior, density-dependent effects, and size. Therefore, models based solely on changes in abundance may miss key components of grazing pressure. We estimated shifts in grazing pressure associated with changes in the abundance and per capita consumption rates of sea urchins triggered by size-selective predation by sea otters (Enhydra lutris). Field surveys suggest that sea otters dramatically decreased the abundance and median size of sea urchins. Furthermore, laboratory experiments revealed that kelp consumption by sea urchins varied nonlinearly as a function of urchin size such that consumption rates increased to the 0.56 and 0.68 power of biomass for red and green urchins, respectively. This reveals that shifts in urchin size structure due to size-selective predation by sea otters alter sea urchin per capita grazing rates. Comparison of two quantitative models estimating total consumptive capacity revealed that a model incorporating shifts in urchin abundance while neglecting urchin size structure overestimated grazing pressure compared to a model that incorporated size. Consequently, incorporating shifts in urchin size better predicted field estimates of kelp abundance compared to equivalent models based on urchin abundance alone. We provide strong evidence that incorporating size-specific parameters increases our ability to describe and predict trophic interactions.

Oral health-related knowledge, attitudes and self-efficacy of Australian rural older adults.

OBJECTIVE: A cross-sectional study was conducted involving older adults from social clubs within a regional local government area in the state of Victoria, Australia, to identify factors associated with knowledge, and attitudes about oral health, as well as perceived self-efficacy. METHODS: Participants underwent an oral health interview, followed by a comprehensive oral clinical examination. RESULTS: A total of 225 older adults participated in this study. The mean age was 70.7 (range: 55-96) years. The majority was females (62.0%) and had incomplete secondary education or less (56.1%); 34.2% were fully edentulous. The mean oral health knowledge score was 24.7 (SD 3.8). None of the socio-demographic and oral health variables yielded a significant effect on the knowledge score. The attitude score had a mean of 5.0 (SD 1.6). Four variables remained significant in the multivariate analysis [p < 0.0001]. A dentate female, with tertiary education, had better oral health attitudes. Higher oral health knowledge scores were associated with a better attitude. The overall self-efficacy mean value was 83.1% (SD 10.6). Dental visits and oral health knowledge remained significant in the attitudes multivariate analysis [p < 0.01]. CONCLUSION: Findings indicate that there were some misconceptions in oral health among this group of older adults. These are important influences on the success/failure of an oral health programme. Oral health education is needed to increase older adults' oral health knowledge, in particular of oral cancer, and to some extent periodontal disease, and improves attitudes and oral health self-efficacy. Oral health knowledge, attitudes and self-efficacy were minimally explained by socio-demographic and clinical variables.

ATP sequestration by a synthetic ATP-binding protein leads to novel phenotypic changes in Escherichia coli.

Artificial proteins that bind key metabolites with high affinity and specificity hold great promise as new tools in synthetic biology, but little has been done to create such molecules and examine their effects on living cells. Experiments of this kind have the potential to expand our understanding of cellular systems, as certain phenotypes may be physically realistic but not yet observed in nature. Here, we examine the physiology and morphology of a population of Escherichia coli as they respond to a genetically encoded, non-biological ATP-binding protein. Unlike natural ATP-dependent proteins, which transiently bind ATP during metabolic transformations, the synthetic protein DX depletes the concentration of intracellular ATP and ADP by a mechanism of protein-mediated ligand sequestration. The resulting ATP/ADP imbalance leads to an adaptive response in which a large population of bacilli cells transition to a filamentous state with dense lipid structures that segregate the cells into compartmentalized units. A wide range of biochemical and microscopy techniques extensively characterized these novel lipid structures, which we have termed endoliposomes. We show that endoliposomes adopt well-defined box-like structures that span the full width of the cell but exclude the synthetic protein DX. We further show that prolonged DX exposure causes a large fraction of the population to enter a viable-but-non-culturable state that is not easily reversed. Both phenotypes correlate with strong intracellular changes in ATP and ADP concentration. We suggest that artificial proteins, such as DX, could be used to control and regulate specific targets in metabolic pathways.

From palace to hut: the architecture of military and naval medicine.

The walls separating medicine from society break down in this examination of early-British hospital architecture, which stresses the similarities and continuities between the civilian and the military. The hospitals examined include those for sick and wounded in the Empire, and later at home and those built for long-term chronic cases. Stevenson considers how matters of state, as well as medical theory and its changes, affected architecture.