Using phenology of eucalypts to determine environmental watering regimes for the River Murray floodplain South Australia

Trees on the River Murray floodplain in South Australia, particularly river red gum and black box (Myrtaceae: Eucalyptus camaldulensis, E. largiflorens), are increasingly water-stressed as the period since effective overbank flows extends to six years. As a result of declining health and dry conditions, recruitment rates in these species are insufficient to maintain populations. This study examined phenological cycles to determine the potential for timing environmental flows to promote recruitment. Results indicate a relatively consistent pattern in river red gums, which would benefit from watering in summer (December-February) to reinforce bud set, flowering and germination during peak seed rain from aerial seed banks. Present environmental flow programs may not provide water to black box on elevated areas of the floodplain, but this species would benefit from watering to reinforce bud set and flowering either in summer (December- February) or winter (May-July), depending on the phenological cycle of the trees to be watered. The possibility of watering to support seedlings in autumn, following above-average rainfall in the previous spring, warrants more study.Anne Jensen, Keith Walker and David Pato

Overlapping functionality of the Pht proteins in zinc homeostasis of streptococcus pneumoniae

Streptococcus pneumoniae is a globally significant pathogen that causes a range of diseases, including pneumonia, sepsis, meningitis, and otitis media. Its ability to cause disease depends upon the acquisition of nutrients from its environment, including transition metal ions such as zinc. The pneumococcus employs a number of surface proteins to achieve this, among which are four highly similar polyhistidine triad (Pht) proteins. It has previously been established that these proteins collectively aid in the delivery of zinc to the ABC transporter substrate-binding protein AdcAII. Here we have investigated the contribution of each individual Pht protein to pneumococcal zinc homeostasis by analyzing mutant strains expressing only one of the four pht genes. Under conditions of low zinc availability, each of these mutants showed superior growth and zinc accumulation profiles relative to a mutant strain lacking all four genes, indicating that any of the four Pht proteins are able to facilitate delivery of zinc to AdcAII. However, optimal growth and zinc accumulation in vitro and pneumococcal survival and proliferation in vivo required production of all four Pht proteins, indicating that, despite their overlapping functionality, the proteins are not dispensable without incurring a fitness cost. We also show that surface-attached forms of the Pht proteins are required for zinc recruitment and that they do not contribute to defense against extracellular zinc stress

Randomised field trial to evaluate serological response after foot-and-mouth disease vaccination in Turkey

AbstractDespite years of biannual mass vaccination of cattle, foot-and-mouth disease (FMD) remains uncontrolled in Anatolian Turkey. To evaluate protection after mass vaccination we measured post-vaccination antibodies in a cohort of cattle (serotypes O, A and Asia-1). To obtain results reflecting typical field protection, participants were randomly sampled from across Central and Western Turkey after routine vaccination. Giving two-doses one month apart is recommended when cattle are first vaccinated against FMD. However, due to cost and logistics, this is not routinely performed in Turkey, and elsewhere. Nested within the cohort, we conducted a randomised trial comparing post-vaccination antibodies after a single-dose versus a two-dose primary vaccination course.Four to five months after vaccination, only a third of single-vaccinated cattle had antibody levels above a threshold associated with protection. A third never reached this threshold, even at peak response one month after vaccination. It was not until animals had received three vaccine doses in their lifetime, vaccinating every six months, that most (64% to 86% depending on serotype) maintained antibody levels above this threshold. By this time cattle would be >20 months old with almost half the population below this age. Consequently, many vaccinated animals will be unprotected for much of the year. Compared to a single-dose, a primary vaccination course of two-doses greatly improved the level and duration of immunity. We concluded that the FMD vaccination programme in Anatolian Turkey did not produce the high levels of immunity required. Higher potency vaccines are now used throughout Turkey, with a two-dose primary course in certain areas.Monitoring post-vaccination serology is an important component of evaluation for FMD vaccination programmes. However, consideration must be given to which antigens are present in the test, the vaccine and the field virus. Differences between these antigens affect the relationship between antibody titre and protection

The first histidine triad motif of phtd is critical for zinc homeostasis in Streptococcus pneumoniae

Streptococcus pneumoniae is the world's foremost human pathogen. Acquisition of the first row transition metal ion zinc is essential for pneumococcal colonization and disease. Zinc is acquired via the ATP-binding cassette transporter AdcCB and two zinc-binding proteins, AdcA and AdcAII. We have previously shown that AdcAII is reliant upon the polyhistidine triad (Pht) proteins to aid in zinc recruitment. Pht proteins generally contain five histidine (His) triad motifs that are believed to facilitate zinc binding and therefore play a significant role in pneumococcal metal ion homeostasis. However, the importance and potential redundancy of these motifs have not been addressed. We examined the effects of mutating each of the five His triad motifs of PhtD. The combination of in vitro growth assays, active zinc uptake, and PhtD expression studies show that the His triad closest to the protein's amino terminus is the most important for zinc acquisition. Intriguingly, in vivo competitive infection studies investigating the amino- and carboxyl-terminal His triad mutants indicate that the motifs have similar importance in colonization. Collectively, our new insights into the contributions of the individual His triad motifs of PhtD, and by extension the other Pht proteins, highlight the crucial role of the first His triad site in zinc acquisition. This study also suggests that the Pht proteins likely play a role beyond zinc acquisition in pneumococcal virulence

Microstructural penetrometry of asteroid regolith analogues and Titan’s surface

We investigate essential aspects of penetrometer design required to measure particle properties on asteroids using a combination of laboratory analogue regoliths and spaceflight data returned by the Huygens probe from Titan. Penetrometry in granular material is complicated due to multiple and interdependent mechanical processes that occur during penetration. A numerical impact model is developed that simulates the behaviour of a penetrometer and its force sensor in a granular medium. The model is based on the Huygens ACC-E instrument that successfully returned penetrometry data from the surface of Titan. Penetrometry measurements are made in analogue asteroid regoliths using a laboratory copy of ACC-E. The average particle size in the targets ranged from 0.1 to 0.9 of the penetrometer tip diameter. To describe the structure seen in the data a number of metrics are defined to characterise the peaks seen in the returned signal. The significance of the variation of the metrics (such as peak height or width) with particle mass and radius are analysed in terms of penetrometer properties such as impact velocity, elastic properties and data logging parameters. We find the penetrometer can be used to measure average particle radius and mass adequately for a mid-range of particle radii. Electronic noise effects mostly the results from very small and very large particles. For high mass particles there is evidence that particle–particle impacts, within the target are being felt by the tip that make any straight forward interpretations using peak frequency a challenge. Using our numerical model the Huygens penetrometry data from Titan is analysed. A particle diameter, of around half a centimetre, is found to be consistent with the penetrometry data returned by Huygens. Recommendations and lessons learned, regarding data interpretation techniques are made for asteroid penetrometry (or any other extraterrestrial surface) when using this instrument

Where is my sink? Reconstruction of landscape development in 1 southwestern Africa since the Late Jurassic

Quantifying the rates and timing of landscape denudation provides a means to constrain sediment flux through time to offshore sedimentary basins. The Late Mesozoic evolution of drainage basins in southern Africa is poorly constrained despite the presence of several onshore and offshore sedimentary basins. A novel approach has been developed to calculate the volume of material eroded since the Late Jurassic at different time steps by constructing structural cross-sections and extrapolating thicknesses of eroded material. Using different assumptions, the calculated volumes of material eroded from southwestern Africa range from 2.52x10⁶ km³ (11.3 km of vertical thickness removed) to 8.87 x10⁵ km³ (4.0 km of vertical thickness removed). For the southward draining systems alone, the calculated removal of 7.81 x10⁵ – 2.60 x10⁵ km³ of material is far greater than the volumes of sediment recorded in offshore sedimentary basins (268 500 km³). Reconstruction of the drainage systems using geomorphic indicators and clast provenance of the Uitenhage Group, as well as extrapolated surface exposure ages, indicate the southern draining systems were active from the Late Jurassic with coeval activity in axial and transverse drainage systems. The calculated volumes are tied to published apatite fission track (AFT) dates to constrain the changes in exhumation rate through time (using multiple scenarios), which indicate a significant amount of Early Cretaceous exhumation (up to 1.26 x10⁶ km³, equivalent to 5.70km of vertical thickness). For the first time, this has permitted long-term landscape evolution to be used to support the interpretation that some of the ‘missing’ sediment was deposited in sedimentary basins on the Falkland Plateau as it moved past southern Africa during the Early Cretaceous. This implies that in this instance, the sinks are separated from their source areas by ~6000 km