Modifying the stereochemistry of an enzyme-catalyzed reaction by directed evolution

Aldolases have potential as tools for the synthesis of stereochemically complex carbohydrates. Here, we show that directed evolution can be used to alter the stereochemical course of the reaction catalyzed by tagatose-1,6-bisphosphate aldolase. After three rounds of DNA shuffling and screening, the evolved aldolase showed an 80-fold improvement in k-cat/K-m toward the non-natural substrate fructose 1,6-bisphosphate, resulting in a 100-fold change in stereospecificity. (31)P NMR spectroscopy was used to show that, in the synthetic direction, the evolved aldolase catalyzes the formation of carbon—carbon bonds with unnatural diastereoselectivity, where the >99:<1 preference for the formation of tagatose 1,6-bisphosphate was switched to a 4:1 preference for the diastereoisomer, fructose 1,6-bisphosphate. This demonstration is of considerable significance to synthetic chemists requiring efficient syntheses of complex stereoisomeric products, such as carbohydrate mimetics

Achimota Pararubulavirus 3: A New Bat-Derived Paramyxovirus of the Genus Pararubulavirus

Bats are an important source of viral zoonoses, including paramyxoviruses. The paramyxoviral Pararubulavirus genus contains viruses mostly derived from bats that are common, diverse, distributed throughout the Old World, and known to be zoonotic. Here, we describe a new member of the genus Achimota pararubulavirus 3 (AchPV3) and its isolation from the urine of African straw-coloured fruit bats on primary bat kidneys cells. We sequenced and analysed the genome of AchPV3 relative to other Paramyxoviridae, revealing it to be similar to known pararubulaviruses. Phylogenetic analysis of AchPV3 revealed the failure of molecular detection in the urine sample from which AchPV3 was derived and an attachment protein most closely related with AchPV2—a pararubulavirus known to cause cross-species transmission. Together these findings add to the picture of pararubulaviruses, their sources, and variable zoonotic potential, which is key to our understanding of host restriction and spillover of bat-derived paramyxoviruses. AchPV3 represents a novel candidate zoonosis and an important tool for further study

Self-reported testing and treatment histories among older Australian men and women who may be at risk of a sexually transmissible infection

Background: Rates of sexually transmissible infections (STIs) are increasing among older adults in many countries. Little is known about the testing and treatment histories of these populations. Correlates of testing in the past 5 years among older adults who may be at risk of a STI were examined. Methods: A cross-sectional survey of 2137 Australians aged 60+ years that involved questions on STIs and STI testing was conducted in 2015. To help inform potential education campaigns, analyses focused on those who may have been at risk of a STI (n = 805, 38%). Results: Less than one in three reported a STI test in the past 5 years (n = 241, 30%) while 6% (n = 51) reported a STI diagnosis. Those diagnosed typically received treatment from a family doctor or general practitioner. Among men, lower testing rates were associated with older age, identifying as heterosexual, lower educational attainment, not using online dating and reporting one partner in the past 5 years. For women, lower rates of testing were found among those who did not use a condom at their most recent sexual encounter and those with one partner in the past 5 years. Conclusions: STI testing rates were low. This study indicates that consideration should be given to the way targeted education campaigns are formulated, such as emphasising the importance of STI testing to older people who are at risk, as well as encouraging healthcare professionals to discuss sexual health with their older patients

Safer sex in later life: Qualitative interviews with older Australians on their understandings and practices of safer sex

Rates of sexually transmitted infections (STIs) are increasing in older cohorts in Western countries such as Australia, the U.K. and the U.S., suggesting a need to examine the safer sex knowledge and practices of older people. This article presents findings from 53 qualitative interviews from the study “Sex, Age & Me: a National Study of Sex and Relationships Among Australians aged 60+.” Participants were recruited through an online national survey. We consider how participants understood “safer sex,” the importance of safer sex to them, the safer sex practices they used (and the contexts in which they used them), and the barriers to using safer sex. Older adults had diverse understandings, knowledge, and use of safer sex practices, although participants tended to focus most strongly on condom use. Having safer sex was strongly mediated by relationship context, trust, perceived risk of contracting an STI, concern for personal health, and stigma. Common barriers to safer sex included erectile difficulties, embarrassment, stigma, reduced pleasure, and the lack of a safer sex culture among older people. The data presented has important implications for sexual health policy, practice, and education and health promotion campaigns aimed at improving the sexual health and wellbeing of older cohorts

The Importance of Sex and the Meaning of Sex and Sexual Pleasure for Men Aged 60 and Older Who Engage in Heterosexual Relationships: Findings from a Qualitative Interview Study

That many older individuals continue to engage in various forms of sexual expression well into later life is now well established in the literature. To date, however, only a small body of qualitative research has examined older men’s experiences and understandings of sex in later life. Likewise, the ways in which older men’s discussions on sex may be used as an avenue for “doing” masculinity remain underexplored. Older men are particularly interesting in this regard, as they inhabit an increasingly subordinated position in relation to hegemonic masculine ideals because of their age. To what extent might this limit or, alternatively, open up the possibilities for sexual expression and subjectivity in later life? Drawing on a subset of findings from Sex, Age, and Me: A National Study with Australian Women and Men Aged 60 and Older, data from qualitative interviews with 27 Australian men were explored in this article. The first Australian study of its kind, we argue that older men who engage in heterosexual relationships draw on a diverse and complex array of discursive positions regarding sex, relationships, and masculinity in making sense of their experiences of sex in later life. Older men are a heterogeneous group, and their experiences and understandings of sex do not simplistically follow “decline” or “success” narratives of aging. The findings of this research build upon and extend emerging research illustrating the centrality of intimacy to older men’s sexual lives, while simultaneously highlighting the ways in which the body and discursive constructions of sex intersect to shape older men’s sexual subjectivities

Sexually active older Australian's knowledge of sexually transmitted infections and safer sexual practices.

OBJECTIVE: Rates of sexually transmitted infections (STIs) are rising among older Australians. We conducted a large survey of older people's knowledge of STIs and safer sexual practices. METHODS: A total of 2,137 Australians aged 60 years and older completed the survey, which included 15 questions assessing knowledge of STIs and safer sexual practices. We examined both levels of knowledge and factors associated with an overall knowledge score. RESULTS: In total, 1,652 respondents reported having sex in the past five years and answered all knowledge questions. This group had good general knowledge but poorer knowledge in areas such as the protection offered by condoms and potential transmission modes for specific STIs. Women had better knowledge than men. Men in their 60s, men with higher education levels, and men who thought they were at risk of STIs reported better knowledge than other men. Knowledge was also better among men and women who had been tested for STIs or reported 'other' sources of knowledge on STIs. CONCLUSIONS: Many older Australians lack knowledge of STIs and safer sexual practices. Implications for public health: To reverse current trends toward increasing STI diagnoses in this population, policies and education campaigns aimed at improving knowledge levels may need to be considered

Absence of MERS-CoV antibodies in feral camels in Australia: Implications for the pathogen's origin and spread

Middle East respiratory syndrome coronavirus (MERS-CoV) infections continue to be a serious emerging disease problem internationally with well over 1000 cases and a major outbreak outside of the Middle East region. While the hypothesis that dromedary camels are the likely major source of MERS-CoV infection in humans is gaining acceptance, conjecture continues over the original natural reservoir host(s) and specifically the role of bats in the emergence of the virus. Dromedary camels were imported to Australia, principally between 1880 and 1907 and have since become a large feral population inhabiting extensive parts of the continent. Here we report that during a focussed surveillance study, no serological evidence was found for the presence of MERS-CoV in the camels in the Australian population. This finding presents various hypotheses about the timing of the emergence and spread of MERS-CoV throughout populations of camels in Africa and Asia, which can be partially resolved by testing sera from camels from the original source region, which we have inferred was mainly northwestern Pakistan. In addition, we identify bat species which overlap (or neighbour) the range of the Australian camel population with a higher likelihood of carrying CoVs of the same lineage as MERS-CoV. Both of these proposed follow-on studies are examples of "proactive surveillance", a concept that has particular relevance to a One Health approach to emerging zoonotic diseases with a complex epidemiology and aetiology

A comparison of numerical surface topography calculations in geodynamic modelling: an evaluation of the ‘sticky air' method

Calculating surface topography in geodynamic models is a common numerical problem. Besides other approaches, the so-called ‘sticky air' approach has gained interest as a free-surface proxy at the top boundary. The often used free slip condition is thereby vertically extended by introducing a low density, low viscosity fluid layer. This allows the air/crust interface to behave in a similar manner to a true free surface. We present here a theoretical analysis that provides the physical conditions under which the sticky air approach is a valid approximation of a true free surface. Two cases are evaluated that characterize the evolution of topography on different timescales: (1) isostatic relaxation of a cosine perturbation and (2) topography changes above a rising plume. We quantitatively compare topographies calculated by six different numerical codes (using finite difference and finite element techniques) using three different topography calculation methods: (i) direct calculation of topography from normal stress, (ii) body-fitting methods allowing for meshing the topography and (iii) Lagrangian tracking of the topography on an Eulerian grid. It is found that the sticky air approach works well as long as the term (ηst/ηch)/(hst/L)3 is sufficiently small, where ηst and hst are the viscosity and thickness of the sticky air layer, and ηch and L are the characteristic viscosity and length scale of the model, respectively. Spurious lateral fluctuations of topography, as observed in some marker-based sticky air approaches, may effectively be damped by an anisotropic distribution of markers with a higher number of markers per element in the vertical than in the horizontal directio

A transdisciplinary and community-driven database to unravel subduction zone initiation

Subduction zones are pivotal for the recycling of Earth’s outer layer into its interior. However, the conditions under which new subduction zones initiate are enigmatic. Here, we constructed a transdisciplinary database featuring detailed analysis of more than a dozen documented subduction zone initiation events from the last hundred million years. Our initial findings reveal that horizontally forced subduction zone initiation is dominant over the last 100 Ma, and that most initiation events are proximal to pre-existing subduction zones. The SZI Database is expandable to facilitate access to the most current understanding of subduction zone initiation as research progresses, providing a community platform that establishes a common language to sharpen discussion across the Earth Science community

The Sex, Age, and Me Study: Recruitment and sampling for a large mixed-methods study of sexual health and relationships in an older Australian population

Older people are often excluded from large studies of sexual health, as it is assumed that they are not having sex or are reluctant to talk about sensitive topics, and are therefore difficult to recruit. We outline the sampling and recruitment strategies from a recent study on sexual health and relationships among older people. Sex, Age and Me was a nationwide Australian study that examined sexual health, relationship patterns, safer-sex practices, and STI knowledge of Australians aged 60 years and over. The study used a mixed-methods approach to establish baseline levels of knowledge and to develop deeper insights into older adult’s understandings and practices relating to sexual health. Data collection took place in 2015, with 2,137 participants completing a quantitative survey and 53 participating in one-on-one semi-structured interviews. As the feasibility of this type of study has been largely untested until now, we provide detailed information on the study’s recruitment strategies and methods. We also compare key characteristics of our sample with national estimates to assess its degree of representativeness. This study provides evidence to challenge the assumptions that older people will not take part in sexual health-related research and details a novel and successful way to recruit participants in this area