Structural modeling and functional analysis of the essential ribosomal processing protease Prp from Staphylococcus aureus

In Firmicutes and related bacteria, ribosomal large subunit protein L27 is encoded with a conserved N-terminal extension that is removed to expose residues critical for ribosome function. Bacteria encoding L27 with this N-terminal extension also encode a sequence-specific cysteine protease, Prp, which carries out this cleavage. In this work, we demonstrate that L27 variants with an un-cleavable N-terminal extension, or lacking the extension (pre-cleaved), are unable to complement an L27 deletion in Staphylococcus aureus. This indicates that N-terminal processing of L27 is not only essential but possibly has a regulatory role. Prp represents a new clade of previously uncharacterized cysteine proteases, and the dependence of S. aureus on L27 cleavage by Prp validates the enzyme as a target for potential antibiotic development. To better understand the mechanism of Prp activity, we analyzed Prp enzyme kinetics and substrate preference using a fluorogenic peptide cleavage assay. Molecular modeling and site-directed mutagenesis implicate several residues around the active site in catalysis and substrate binding, and support a structural model in which rearrangement of a flexible loop upon binding of the correct peptide substrate is required for the active site to assume the proper conformation. These findings lay the foundation for the development of antimicrobials that target this novel, essential pathway

Dietary flavonoid intakes and CVD incidence in the Framingham Offspring Cohort

This study examines the relationship between long-term intake of six flavonoid classes and incidence of CVD and CHD, using a comprehensive flavonoid database and repeated measures of intake, while accounting for possible confounding by components of a healthy dietary pattern. Flavonoid intakes were assessed using a FFQ among the Framingham Offspring Cohort at baseline and three times during follow-up. Cox proportional hazards regression was used to characterise prospective associations between the natural logarithms of flavonoid intakes and CVD incidence using a time-dependent approach, in which intake data were updated at each examination to represent average intakes from previous examinations. Mean baseline age was 54 years, and 45 % of the population was male. Over an average 14·9 years of follow-up among 2880 participants, there were 518 CVD events and 261 CHD events. After multivariable adjustment, only flavonol intake was significantly associated with lower risk of CVD incidence (hazard ratios (HR) per 2·5-fold flavonol increase = 0·86, Ptrend = 0·05). Additional adjustment for total fruit and vegetable intake and overall diet quality attenuated this observation (HR = 0·89, Ptrend = 0·20 and HR = 0·92, Ptrend = 0·33, respectively). There were no significant associations between flavonoids and CHD incidence after multivariable adjustment. Our findings suggest that the observed association between flavonol intake and CVD risk may be a consequence of better overall diet. However, the strength of this non-significant association was also consistent with relative risks observed in previous meta-analyses, and therefore a modest benefit of flavonol intake on CVD risk cannot be ruled out

You Can’t Teach Wildlife and Fisheries Online, Can You? A Comparison of Student Learning and Satisfaction in Two Online and Face-to-Face Courses

Criticisms of online science courses are rooted in the lack to of hands-on learning experiences only available in the face-to-face (f2f) environment. Very few studies have compared student learning outcomes (e.g., assignment, exam, and final grades; level of learning achieved) and student satisfaction between online and f2f courses in the science curriculum, and none of these studies has been done for applied natural resources courses. We are currently conducting a quasi-experiment to compare student learning outcomes and satisfaction for online and f2f versions of two introductory wildlife and fisheries sciences course at South Dakota State University (WL 220: Introduction to Wildlife and Fisheries and WL 230: Wildlife and Fisheries Techniques). To date, we have documented demographic differences between online and face-to-face students in the two courses. Online students tend to be older, have full-time employment, be more experienced in the online environment, and identify themselves more as visual learners than f2f students. Some differences in learning outcomes have been associated with time spent in learning activities within each environment. In the online WL 230 course, the average time spent per week on course tasks was positively associated with overall course grade and individual scores received on assignments related to applying, analyzing, and evaluating information. Time spent outside of class was negatively related to overall course grade in the f2f environment, but class attendance was positively related to course grade and scores on individual assignments that emphasized applying, analyzing, and evaluating information. Insights gleaned from this study may be used to improve and expand online applied natural resources courses. Expansion of these courses may be vital as applied natural resources curricula have been lost nationwide, but these types of knowledge are still very much in demand

The Value of Values-Based Supply Chains: Farmer Perspective

In the last few decades, the emergence of mid-scale, intermediated marketing channels that fall between commodity and direct markets has attracted growing interest from scholars for their potential to preserve small and mid-sized farms while scaling up alternative agrifood sourcing. When such mid-scale supply chains are formed among multiple business partners with shared ethics or values related to the qualities of the food and the business relationships along the supply chain, they may be termed values-based supply chains (VBSCs). Most of the research on VBSCs to date has relied primarily on a case study approach that investigates the performance of VBSCs from the perspective of VBSC founders or leaders. In contrast, this research seeks out the perspectives of farmers who participate in VBSCs. A nationwide farmer survey conducted in 2017 offers original insights on farmer motivations for participating in VBSCs and how they are being used by farmers relative to other marketing channels. We find that VBSCs serve farms of all sizes. Overall, smaller farms were more likely to market a higher percentage of overall sales through their VBSC and more likely to rank their VBSC as one of the top three marketing channels in their portfolio. But it was the larger farms that were more likely to perceive VBSC-specific benefits. Our findings confirm that while there is a limited volume of product that such regional supply chains can currently handle, farmers view VBSCs as a valuable marketing option that aligns with their own values and preserves their product\u27s identity

Developing reflective practice in teacher candidates through program coherence

In this study, we explored the role of reflection at three stages of preparation across a teacher education program. Reflection has long been considered an essential aspect of professional practice for teaching; however, reflection is often vague and undefined. Through an examination of the opportunities we provided for our students to reflect, and systematic analysis of the levels of reflection our students engaged in, we found that the development of reflective practices could be understood and aligned across a professional preparation program. Furthermore, we considered our own pedagogical practices related to modality, prompting, scaffolding, assignment structure, and feedback in our analysis of a variety of student reflection artifacts, in order to understand the potential impact of our own pedagogical decisions across the program. Findings suggest that the program provided modeling and structures for reflection early on, encouraged the inclusion of multiple perspectives in relation to professional practice, and supported a synthesis of student learning of theory and practice as preservice teachers approached program completion. This article offers reflection as a tool for exploring issues of professional growth across a continuum of development

Developing reflective practice in teacher candidates through program coherence

In this study, we explored the role of reflection at three stages of preparation across a teacher education program. Reflection has long been considered an essential aspect of professional practice for teaching; however, reflection is often vague and undefined. Through an examination of the opportunities we provided for our students to reflect, and systematic analysis of the levels of reflection our students engaged in, we found that the development of reflective practices could be understood and aligned across a professional preparation program. Furthermore, we considered our own pedagogical practices related to modality, prompting, scaffolding, assignment structure, and feedback in our analysis of a variety of student reflection artifacts, in order to understand the potential impact of our own pedagogical decisions across the program. Findings suggest that the program provided modeling and structures for reflection early on, encouraged the inclusion of multiple perspectives in relation to professional practice, and supported a synthesis of student learning of theory and practice as preservice teachers approached program completion. This article offers reflection as a tool for exploring issues of professional growth across a continuum of development

Riskometer—Voting with Your Feet

As Extension professionals, we are faced with the need to educate youth and adults about risk and to assess their preference for risk; however, many find the concepts difficult to illustrate. This article lays out a simple technique that can be used to illustrate how personal attitudes toward risk change with changes in situations. Youth and adults who participate in the exercise will have a better understanding of risk and their attitudes about risk, which will lead them to make personal choices that are right for them

Building in Integrated Pest Management network in cooperation with Iowa fruit and vegetable growers

Fifty-one commercial growers of apples, strawberries, tomatoes, and/or watermelons cooperated with Iowa State University (ISU) Extension specialists in a three-year program to evaluate IPM control techniques. Scouts and growers monitored pest infestations and diseases such as codling moth on apples, tarnished plant bugs on strawberries, and anthracnose on tomatoes and melons. Growers sprayed only when pest populations or disease risk values reached levels capable of doing crop damage. Weather conditions were monitored for periods favorable to pest outbreaks. On average, ISU researchers estimate that growers applied from 25 to 55 percent fewer insecticide and fungicide sprays (depending on the year and the particular pest) by using IPM methods in comparison to their usual practices. For the growers, this meant decreased input costs, a better bottom line, and enhanced competitiveness

Habitat Persistence Underlies Intraspecific Variation in the Dispersal Strategies of Planthoppers

Dispersal is considered a vital life history characteristic for insects exploiting temporary habitats, and life history theorists have often hypothesized an inverse relationship between dispersal capability and habitat persistence. Most often, this hypothesis has been tested using interspecific comparisons of dispersal capability and qualitative estimates of habitat persistence. Consequently, most assessments have failed to control for possible phylogenetic nonindependence and they also lack quantitative rigor. We capitalized on existing intraspecific variation on the dispersal capability of Prokelisia planthoppers to examine the relationship between habitat persistence and dispersal, thereby minimizing possible phylogenetic effects. Two congeneric species (Prokelisia marginata and P. dolus) occur in the intertidal marshes of North America, where they feed exclusively on cordgrasses (Spartina). Because these planthoppers exhibit wing dimorphism, flight-capable adults (macropters with fully developed wings). Thus, dispersal capability can be readily estimated by the percentage of macropters in a population. At a regional spatial scale, we found a highly significant negative relationship between dispersal capability (present macroptery) and habitat persistence. In this system, habitat persistence is influenced by a combination of marsh elevation, winter severity, and tidal range, which interact to determine the ability of planthoppers to endure through winter in their primary habitat for development. P. marginata develops primarily in low-marsh habitats during summer, habitats that can be subjected to pronounced winter disturbance due to ice scouring and/or extensive tidal inundation. Levels of winter disturbance of the low marsh are extreme along the Atlantic coast, intermediate along the Pacific, and low along the Gulf. Both the failure of P. marginata populations to remain through winter in the habitat, and the dispersal ability of these populations (92%, 29%, and 17% macroptery, respectively), are correlated with levels of disturbance. Thus, in regions where winter disturbance is high, levels of dispersal are correspondingly high to allow for recolonization of extirpated habitats from overwintering sites on the high marsh. Unlike P. marginata, P. dolus develops primarily in high-marsh habitats, which are much less disturbed on all coasts during winter. Consequently, this species remains year-round in its primary habitat for development, and most populations exhibit relatively low levels of macroptery (\u3c10%). When raised under common garden conditions, many more macropters of both species were produced from Atlantic compared to Gulf populations. Thus the proportion of macropters produced from the populations used in this experiment paralleled the incidence of macroptery measured in the field, providing evidence that the geographic variation in dispersal capability in both species has in part a genetic basis. The results of this study provide strong intraspecific evidence for an inverse relationship between the dispersal capability of insects and the persistence of their habitats