Journal Articles
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Item Regional patterns of mtDNA diversity in Styela plicata, an invasive ascidian, from Australian and New Zealand marinas(CSIRO PUBLISHING, 7/03/2013) Torkkola J; Riginos C; Liggins LThe ascidian Styela plicata is abundant in harbours and marinas worldwide and has likely reached this distribution via human-mediated dispersal. Previous worldwide surveys based on mitochondrial cytochrome oxidase one (COI) sequences have described two divergent clades, showing overlapping distributions and geographically widespread haplotypes. These patterns are consistent with recent mixing among genetically differentiated groups arising from multiple introductions from historically distinct sources. In contrast, a study of Australian S. plicata using nuclear markers found that population differentiation along the eastern coast related to geographic distance and no evidence for admixture between previously isolated genetic groups. We re-examined the genetic patterns of Australian S. plicata populations using mtDNA (CO1) to place their genetic patterns within a global context, and we examined New Zealand populations for the first time. We found that the haplotypic compositions of Australian and New Zealand populations are largely representative of other worldwide populations. The New Zealand populations, however, exhibited reduced diversity, being potentially indicative of a severely bottlenecked colonisation event. In contrast to results from nuclear markers, population differentiation of mtDNA among Australian S. plicata was unrelated to geographic distance. The discrepancy between markers is likely to be a consequence of non-equilibrium population genetic processes that typify non-indigenous species. © 2013 CSIRO.Item Evaluating edge-of-range genetic patterns for tropical echinoderms, Acanthaster planci and Tripneustes gratilla, of the Kermadec Islands, southwest Pacific(ROSENSTIEL SCH MAR ATMOS SCI, 1/01/2014) Liggins L; Gleeson L; Riginos CEdge-of-range populations are often typified by patterns of low genetic diversity and high genetic differentiation relative to populations within the core of a species range. The "core-periphery hypothesis," also known as the "central-marginal hypothesis," predicts that these genetic patterns at the edge-of-range are a consequence of reduced population size and connectivity toward a species range periphery. It is unclear, however, how these expectations relate to high dispersal marine species that can conceivably maintain high abundance and high connectivity at their range edge. In the present study, we characterize the genetic patterns of two tropical echinoderm populations in the Kermadec Islands, the edge of their southwest Pacific range, and compare these genetic patterns to those from populations throughout their east Indian and Pacific ranges. We find that the populations of both Acanthaster planci (Linnaeus, 1758) and Tripneustes gratilla (Linnaeus, 1758) are represented by a single haplotype at the Kermadec Islands (based on mitochondrial cytochrome oxidase C subunit I). Such low genetic diversity concurs with the expectations of the "core-periphery hypothesis." Furthermore, the haplotypic composition of both populations suggests they have been founded by a small number of colonists with little subsequent immigration. Thus, local reproduction and self-recruitment appear to maintain these populations despite the ecologically marginal conditions of the Kermadec Islands for these tropical species. Understanding rates of self-recruitment vs reliance on connectivity with populations outside of the Kermadec Islands has implications for the persistence of these populations and range stability of these echinoderm species.© 2014 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.Item Formation of nano-fibrils from the A, B and C variants of bovine beta-lactoglobulin(ELSEVIER SCI LTD, 1/02/2015) Dave, AC; Loveday, SM; Anema, SG; Jameson, GB; Singh, HItem Validating a measure of children's monitoring-blunting coping styles in dental situations(Routledge Taylor & Francis Group, 2012) Williams MN; Jones LMThe monitoring-blunting theory of coping suggests that when faced with a threatening situation, individuals can respond by either monitoring or avoiding (blunting) threatening information. The current study sought to validate a scale of children's preferences for monitoring or blunting in dental situations (the Monitoring Blunting Dental Scale or MBDS). The psychometric characteristics of the scale were assessed in a sample of 240 New Zealand children aged 11-13. Reliability was adequate for both monitoring (α = 0.74) and blunting (α = 0.76) subscale scores. Convergent validity was indicated by strong correlations (>0.6) between the measure's subscales and those of a related scale, although discriminant validity with respect to dental anxiety was problematic for the blunting subscale. Exploratory factor analysis supported a two-factor monitoring-blunting model, although confirmatory factor analysis indicated reasonable but imperfect fit for this model, SBχ²(251) = 510.7, p < 0.001, RMSEA = 0.066. We reflect on conceptual issues which may underlie the difficulties experienced here and elsewhere in developing psychometrically sound measures of Miller's blunting construct and suggest that the monitoring subscale of the study scale may be most useful to other researchers.Item Ballistic modeling and pattern testing to prevent separation of New Zealand fertilizer products(American Society of Agricultural and Biological Engineers, 18/06/2015) Grafton MCE; Yule IJ; Robertson BG; Chok SM; Manning MJIn recent years twin disc centrifugal spreaders have become larger with some manufacturers claiming to be able to spread fertilizer products as far as 60 m. To achieve wider spread widths, the fertilizer particle exit velocity off the disc has increased, as a result the ballistic qualities of the product becomes more critical. This case study uses data-mined information from Ravensdown Fertiliser Co-op Ltd, a major fertilizer supplier. This article examines and researches products used by arable and grassland farmers and studies the effect of changes in product characteristics on spread bout width from these newer spreaders. Ballistic modeling, based on particle density, size, and shape was used to test the distance fertilizer particles travel at various velocities. Fertilizer particle velocities were measured by high speed photometry using both common fertilizers and common spreaders found in New Zealand. Spreading equipment was pattern tested using the New Zealand Spreadmark method. Ballistic modeling of particles proved appropriate in ideal conditions. Fertilizer manufacturers believe that spreader operators often fail to take account of physical characteristics of products being spread and target the widest bout width possible. This can lead to an in-field Coefficient of Variation (CV) which is much greater than 15% and leads to sub-optimal utilization of fertilizer, where variations in particle size distribution occur. Similar situations have been experienced when spreading fertilizer blends; where blends previously spread successfully, at narrower bout widths now separate. Ballistic models could provide bout width recommendations for products and blends, for a range of applicators and reduce crop striping.Item Effects of omega 3 and omega 6-polyunsaturated fatty acids on RANKL-induced osteoclast differentiation of RAW264.7 cells: A comparative in vitro study(MDPI, 10/07/2014) Boeyens JCA; Deepak V; Chua W-H; Kruger MC; Joubert A; Coetzee MPolyunsaturated fatty acids (PUFAs) have been reported to have an anabolic effect on bone in vivo, but comparative studies to identify inhibitors of osteoclast formation amongst ω3- and ω6-PUFAs are still lacking. Here we assessed the effects of the ω3-PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the ω6-PUFAs, arachidonic acid (AA) and γ-linolenic acid (GLA) on a RAW264.7 osteoclast differentiation model. The effects of PUFAs on RANKL-induced osteoclast formation were evaluated by counting tartrate resistant acid phosphatase (TRAP)-positive multinucleated cells. PUFAs significantly inhibited RANKL-induced osteoclast formation in a dose-dependent manner with AA- and DHA-mediated inhibition being the strongest. Furthermore, RANKL-induced mRNA- and protein expression of the key osteoclastogenic genes cathepsin K and TRAP were inhibited by AA and more potently by DHA. Owing to the attenuated osteoclastogenesis by DHA and AA, actin ring formation and bone resorptive activity of these cells as evaluated on bone-mimetic plates were severely compromised. Hence, of the tested PUFAs, AA and DHA were found to be the most effective in inhibiting RANKL-induced osteoclast formation with the latter providing the strongest inhibitory effects. Collectively, the data indicates that these PUFAs may play an important role in regulating bone diseases characterized by excessive osteoclast activity.Item Estimating direct N2O emissions from sheep, beef, and deer grazed pastures in New Zealand hill country: accounting for the effect of land slope on N2O emission factors from urine and dung(Elsevier, 2015-03) Saggar SK; Giltrap DL; Davison R; Gibson R; de Klein CAM; Rollo M; Ettema P; Rys GNearly one-half of New Zealand's ruminant livestock graze on hill country pastures where spatial differences in soil conditions are highly variable and excretal deposition is influenced by pasture production, animal grazing and resting behaviour that impact the nitrous oxide (N2O) emission factor from excreta (EF3). New Zealand currently uses country-specific EF3 values for urine and dung of 0.01 and 0.0025, respectively, to estimate direct N2O emissions from excreta. These values have largely been developed from trials on flat pastoral land. The use of the same EF3 for hill pasture with medium and steep slopes has been recognised as a possible source of overestimation of N2O emissions in New Zealand. The objectives of this study were to develop and describe an approach that takes into account the effects of slope in estimating hill country N2O emissions from the dung and urine of ruminant animals (sheep, beef cattle, and deer) across different slope classes, and then compare these estimates with current New Zealand inventory estimates. We use New Zealand as a case study to determine the direct N2O emissions between 1990 and 2012 from sheep, beef cattle and deer excreta using updated estimates of EF3 for sloping land, the area of land in different slope classes by region and farm type, and a nutrient transfer model to allocate excretal-N to the different slope classes, and compare the changes between these hill pastures-specific and current inventory estimates. Our findings are significant - the proposed new methodology using New Zealand specific EFs calculated from a national series of hill country experiments resulted in 52% lower N2O estimates relative to using current inventory emission factors, for the period between 1990 and 2012 and reduces New Zealand's total national agricultural N2O greenhouse inventory estimates by 16%. The improved methodology is transparent, and complete, and has improved accuracy of emission estimates. On this basis, the improved methodology of estimating N2O emission is recommended for adoption where hill land grasslands are grazed by sheep, beef cattle and deer.Item Bistability in a metabolic network underpins the De Novo evolution of colony switching in Pseudomonas fluorescens(PUBLIC LIBRARY SCIENCE, 12/03/2015) Gallie J; Libby E; Bertels F; Remigi P; Jendresen CB; Ferguson GC; Desprat N; Buffing MF; Sauer U; Beaumont HJE; Martinussen J; Kilstrup M; Rainey PB© 2015 Gallie et al. Phenotype switching is commonly observed in nature. This prevalence has allowed the elucidation of a number of underlying molecular mechanisms. However, little is known about how phenotypic switches arise and function in their early evolutionary stages. The first opportunity to provide empirical insight was delivered by an experiment in which populations of the bacterium Pseudomonas fluorescens SBW25 evolved, de novo, the ability to switch between two colony phenotypes. Here we unravel the molecular mechanism behind colony switching, revealing how a single nucleotide change in a gene enmeshed in central metabolism (carB) generates such a striking phenotype. We show that colony switching is underpinned by ON/OFF expression of capsules consisting of a colanic acid-like polymer. We use molecular genetics, biochemical analyses, and experimental evolution to establish that capsule switching results from perturbation of the pyrimidine biosynthetic pathway. Of central importance is a bifurcation point at which uracil triphosphate is partitioned towards either nucleotide metabolism or polymer production. This bifurcation marks a cell-fate decision point whereby cells with relatively high pyrimidine levels favour nucleotide metabolism (capsule OFF), while cells with lower pyrimidine levels divert resources towards polymer biosynthesis (capsule ON). This decision point is present and functional in the wild-type strain. Finally, we present a simple mathematical model demonstrating that the molecular components of the decision point are capable of producing switching. Despite its simple mutational cause, the connection between genotype and phenotype is complex and multidimensional, offering a rare glimpse of how noise in regulatory networks can provide opportunity for evolution.Item How to use programme theory to evaluate the effectiveness of schemes designed to improve the work environment in small businesses(IOS Press, 30/10/2012) Olsen K; Legg S; Hasle PDue to the many constraints that small businesses (SBs) face in meeting legislative requirements, occupational health and safety (OHS) regulatory authorities and other OSH actors have developed programmes which can reach out to SBs and motivate and assist them in improving the work environment. A number of conceptual models help to enhance our understanding of OHS interventions in SBs and their effectiveness. However, they have mainly been evaluated on output rather than the process relating to the change theory underlying the intervention, and hence have seldom been rigorously evaluated. Thus little is known about how particular features of SBs can be taken into account when designing and implementing national programmes. This paper shows how realist analysis and programme theory may be used as a framework for evaluating, developing and improving national intervention programmes for the improvement of the work environment and reducing injuries in SBs. It illustrates this for a specific New Zealand intervention: the Workplace Safety Discount scheme and its implementation in the agriculture sector. In practice, realist analysis should be performed during the planning, implementation and management stages so that ongoing findings can be fed back to the participant social actors to help them make appropriate changes to enhance the likelihood of success.Item
