Lack of Galactose or Galacturonic Acid in <i>Bradyrhizobium japonicum</i> USDA 110 Exopolysaccharide Leads to Different Symbiotic Responses in Soybean

Exopolysaccharide (EPS) and lipopolysaccharide (LPS) from Bradyrhizobium japonicum are important for infection and nodulation of soybean (Glycine max), although their roles are not completely understood. To better understand this, we constructed mutants in B. japonicum USDA 110 impaired in galactose or galacturonic acid incorporation into the EPS without affecting the LPS. The derivative LP 3010 had a deletion of lspL-ugdH and produced EPS without galacturonic acid whereas LP 3013, with an insertion in exoB, produced EPS without galactose. In addition, the strain LP 3017, with both mutations, had EPS devoid of both galactosides. The missing galactosides were not replaced by other sugars. The defects in EPS had different consequences. LP 3010 formed biofilms and nodulated but was defective in competitiveness for nodulation; and, inside nodules, the peribacteroid membranes tended to fuse, leading to the merging of symbiosomes. Meanwhile, LP 3013 and LP 3017 were unable to form biofilms and produced empty pseudonodules but exoB suppressor mutants were obtained when LP 3013 plant inoculation was supplemented with wild-type EPS. Similar phenotypes were observed with all these mutants in G. soja. Therefore, the lack of each galactoside in the EPS has a different functional effect on the B. japonicum-soybean symbiosis.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

A novel low-cost Safe System-aligned treatment for regional and remote intersections

An intersection active warning system aiming to improve vehicle safety at intersections has been developed and trialled. This system, named RJAWS Lite, is an advisory variation of the existing mandatory-speed based RJAWS and provides two major visual warnings: (i) speed advisory on major approaches and (ii) run-through prevention on the minor approach. A controlled before-after analysis conducted on speed data from a trial at six rural intersections in South Australia indicates that RJAWS Lite can provide substantial safety benefits, albeit to a lesser degree than the full version of the RJAWS. Nonetheless, the RJAWS Lite involves considerably lower equipment and installation costs, combined with less restrictive regulations, than the mandatory full version of the RJAWS and so could be expected to be suitable for more widespread installation, which could therefore effectively increase road safety at a larger number of rural junctions. Future streamlining of the current large billboard-style RJAWS signage may likely contribute to improve driver compliance with the advised speed and therefore further increase the predicted safety benefits.Mongiardini M., Stokes C.S

Profile of crashes at intersections in South Australia

Intersections represent one of the most safety critical parts of the road network. They are characterised by a high risk of collisions with large impact angles and high speeds. In 2019, 20% of fatal crashes in metropolitan areas occurred at intersections. Knowledge of both the types and relative incidence of intersection crashes should assist in identifying effective treatments aimed at reducing the risk of casualty crashes (fatal, injury) in this critical part of the road network. Therefore, the objective of this report was to provide a broad overview of the various types of crashes occurring at intersections in South Australia. A top-down analysis was carried out on police reported road crashes that occurred in South Australia between 2013 and 2019 (inclusive). After an initial overview of all crashes at intersections, a more specific analysis was carried out on casualty crashes at intersections. Finally, a specific analysis was conducted on pedestrian-related casualty crashes at intersections. At each level of this top-down approach, a breakdown analysis was conducted to further examine the role of relevant factors such as type of control (signalised, priority, roundabouts), road environment (urban or rural) and speed limit. Results are presented in the form of various graphs and cover three major geographical areas: (i) the entire state, (ii) Adelaide metropolitan area only, (iii) outside of Adelaide metropolitan area. This information can be used to support and inform future research activities as well as the selection of appropriate countermeasures to improve safety at intersections.M Mongiardini, ME Elsegood, CS Stoke

Evaluation of Centreline ATLM along Curves in Mountainous Roads

Centreline Audio Tactile Line Marking (ATLM) was installed on a popular narrow road in the Adelaide foothills. A before-after evaluation was conducted to assess the ATLM potential for influencing lane position/crossing and speed along four trial curves. Vehicle lane position and speed at those curves, and between-site travel times were analysed. . Post treatement, all vehicle types tended to safely shift towards the edgeline along right-hand curves. However, variability along left-hand curves existed amongst the four sites. Generally, the treatment did not appear to reduce lane crossing frequency on curves, except at one site. Centreline ATLM did not appear to induce a speed decrease along curves. Nonetheless, a slight reduction of the average travel speed along the treated route may indicate a generalised speed calming effect. The study suggests merit for centreline ATLM along curves regarding lane positioning, but a limited effect on voluntary lane crossing and speed.Mongiardini, M., Stokes, C., Woolley, J

Preliminary evaluation of Rural Junction Activated Warning System (RJAWS) in rural South Australia

This report describes a preliminary evaluation of the potential for the Rural Junction Activated Warning System (RJAWS) to reduce the travel speed of approaching vehicles on the major legs of a three-leg junction when another vehicle is detected on the minor road or turning right from the far-side major leg into the minor leg. When the RJAWS detects any of those two conditions, an electronic sign placed on each approach direction along the major road temporarily indicate a speed limit lower than the default limit. The system has been installed at four rural junctions in South Australia characterised by poor sight distances. At three of the four trial locations, the default and reduced speed limits are 80 km/h and 50 km/h, respectively; whereas at one of the trial locations a default speed of 100 km/h and a reduced speed of 70 km/h applies. Pre and post RJAWS installation speed profiles of vehicles travelling along the major road have been compared. When the temporary speed limit signs are activated, the average travel speed along the major road is reduced by 11.3 km/h to 22.1 km/h. Consequently, the expected average relative risk of a casualty crash at the trialled junctions is reduced by 42% to 65% compared to before the RJAWS installation. Despite a limited compliance with the reduced speed limit, the proportion of drivers travelling through the junction at speeds 20 km/h or higher than the reduced speed limit was considerably low when RJAWS is activated, indicating the system effectiveness in reducing risky behaviour when another vehicle is at the junction. An extension of the RJAWS program to additional junctions is strongly suggested. Also, further investigation should be carried out to confirm the findings of this study through a control-case before/after analysis with a larger and more accurate speed data sample.M Mongiardini, CS Stokes, JE Woolle

Effects of N-starvation and C-source on Bradyrhizobium japonicum exopolysaccharide production and composition, and bacterial infectivity to soybean roots

The exopolysaccharide (EPS) is an extracellular molecule that in Bradyrhizobium japonicum affects bacterial efficiency to nodulate soybean. Culture conditions such as N availability, type of C-source, or culture age can modify the amount and composition of EPS. To better understand the relationship among these conditions for EPS production, we analyzed their influence on EPS in B. japonicum USDA 110 and its derived mutant ΔP22. This mutant has a deletion including the 3′ region of exoP, exoT, and the 5′ region of exoB, and produces a shorter EPS devoid of galactose. The studies were carried out in minimal media with the N-source at starving or sufficient levels, and mannitol or malate as the only C-source. Under N-starvation there was a net EPS accumulation, the levels being similar in the wild type and the mutant with malate as the C-source. By contrast, the amount of EPS diminished in N-sufficient conditions, being poyhydroxybutyrate accumulated with culture age. Hexoses composition was the same in both N-situations, either with mannitol or malate as the only C-source, in contrast to previous observations made with different strains. This result suggests that the change in EPS composition in response to the environment is not general in B. japonicum. The wild type EPS composition was 1 glucose:0.5 galactose:0.5 galacturonic acid:0.17 mannose. In ΔP22 the EPS had no galactose but had galacturonic acid, thus indicating that it was not produced from oxidation of UDP-galactose. Infectivity was lower in ΔP22 than in USDA 110. When the mutant infectivity was compared between N-starved or N-sufficient cultures, the N-starved were not less infective, despite the fact that the amounts of altered EPS produced by this mutant under N-starvation were higher than in N-sufficiency. Since this altered EPS does not bind soybean lectin, the interaction of EPS with this protein was not involved in increasing ΔP22 infectivity under N-starvation.Instituto de Biotecnología y Biología Molecula

Distinguishable DNA methylation defines a cardiac-specific epigenetic clock

Abstract Background The present study investigates whether epigenetic differences emerge in the heart of patients undergoing cardiac surgery for an aortic valvular replacement (AVR) or coronary artery bypass graft (CABG). An algorithm is also established to determine how the pathophysiological condition might influence the human biological cardiac age. Results Blood samples and cardiac auricles were collected from patients who underwent cardiac procedures: 94 AVR and 289 CABG. The CpGs from three independent blood-derived biological clocks were selected to design a new blood- and the first cardiac-specific clocks. Specifically, 31 CpGs from six age-related genes, ELOVL2, EDARADD, ITGA2B, ASPA, PDE4C, and FHL2, were used to construct the tissue-tailored clocks. The best-fitting variables were combined to define new cardiac- and blood-tailored clocks validated through neural network analysis and elastic regression. In addition, telomere length (TL) was measured by qPCR. These new methods revealed a similarity between chronological and biological age in the blood and heart; the average TL was significantly higher in the heart than in the blood. In addition, the cardiac clock discriminated well between AVR and CABG and was sensitive to cardiovascular risk factors such as obesity and smoking. Moreover, the cardiac-specific clock identified an AVR patient's subgroup whose accelerated bioage correlated with the altered ventricular parameters, including left ventricular diastolic and systolic volume. Conclusion This study reports on applying a method to evaluate the cardiac biological age revealing epigenetic features that separate subgroups of AVR and CABG