1,909 research outputs found

    Argentine stem weevil damage to high sugar ryegrass infected with AR1 under field conditions

    Get PDF
    Previous laboratory based studies indicate that, compared to standard cultivars, high sugar grasses (HSG) can have lower endophyte and peramine concentrations and suggest that N fertilisation may result in further reductions in endophyte and alkaloid. This could reduce the resistance of HSG, particularly at high N inputs, to Argentine stem weevil (ASW), but the interaction needs testing under field conditions. The present objective was to determine the effect of ryegrass cultivar on ASW damage, and possible interactions with N fertiliser. ASW damage, endophyte and peramine concentration were measured in three perennial ryegrass cultivars, (HSG diploid, standard diploid and a tetraploid) containing AR1 endophyte, under high and no N fertiliser application. The proportion of tillers damaged by ASW adults or larvae did not differ significantly between cultivars. However, ASW adults tended (P<0.10) to prefer the standard diploid and tetraploid cultivars over the HSG cultivar. Our results are in keeping with previous observations that higher sugar diploid cultivars may have lower endophyte and peramine content than a STD diploid cultivar, but this does not appear to have reduced resistance to ASW. Lack of differences in N content of herbage leaves, between the N fertiliser treatments, likely due to compensating changes in clover content of pastures, meant little effect of N application was seen in this field trial

    Economic Values for Perennial Ryegrass Traits in New Zealand Dairy Farm Systems

    Get PDF
    Perennial ryegrass (Lolium perenne L.) is the main species used in dairy pastures throughout New Zealand. There are approximately 30 perennial ryegrass cultivars sold commercially in New Zealand, but currently there is no evaluation system which allows farmers to compare the potential impact of different cultivars on the profitability of their farm business. Such an economic evaluation system requires information on performance values (PV) for cultivars which quantifies their performance with respect to the major productivity traits (herbage accumulation (HA, kg DM/ha), nutritive value and persistence) relative to a genetic base, and economic values (EV, Doyle and Elliott 1983) which estimate the additional profit resulting from each unit change in the trait of interest (Equation 1). Economic value = Δ operating profit/Δ trait of interest (1) This paper describes a system modelling approach developed to estimate EV for seasonal HA of pasture in the major dairying regions of New Zealand. This information is used in the DairyNZ Forage Value Index system (www.dairynzfvi.co.nz) which is being developed to include information on all three productivity traits for commercially available ryegrass cultivars

    Allometric scaling of skin thickness, elasticity, viscoelasticity to mass for micro-medical device translation:From mice, rats, rabbits, pigs to humans

    Get PDF
    Abstract Emerging micro-scale medical devices are showing promise, whether in delivering drugs or extracting diagnostic biomarkers from skin. In progressing these devices through animal models towards clinical products, understanding the mechanical properties and skin tissue structure with which they interact will be important. Here, through measurement and analytical modelling, we advanced knowledge of these properties for commonly used laboratory animals and humans (~30 g to ~150 kg). We hypothesised that skin’s stiffness is a function of the thickness of its layers through allometric scaling, which could be estimated from knowing a species’ body mass. Results suggest that skin layer thicknesses are proportional to body mass with similar composition ratios, inter- and intra-species. Experimental trends showed elastic moduli increased with body mass, except for human skin. To interpret the relationship between species, we developed a simple analytical model for the bulk elastic moduli of skin, which correlated well with experimental data. Our model suggest that layer thicknesses may be a key driver of structural stiffness, as the skin layer constituents are physically and therefore mechanically similar between species. Our findings help advance the knowledge of mammalian skin mechanical properties, providing a route towards streamlined micro-device research and development onto clinical use

    Systems analysis of bioenergetics and growth of the extreme halophile Halobacterium salinarum

    Get PDF
    Halobacterium salinarum is a bioenergetically flexible, halophilic microorganism that can generate energy by respiration, photosynthesis, and the fermentation of arginine. In a previous study, using a genome-scale metabolic model, we have shown that the archaeon unexpectedly degrades essential amino acids under aerobic conditions, a behavior that can lead to the termination of growth earlier than necessary. Here, we further integratively investigate energy generation, nutrient utilization, and biomass production using an extended methodology that accounts for dynamically changing transport patterns, including those that arise from interactions among the supplied metabolites. Moreover, we widen the scope of our analysis to include phototrophic conditions to explore the interplay between different bioenergetic modes. Surprisingly, we found that cells also degrade essential amino acids even during phototropy, when energy should already be abundant. We also found that under both conditions considerable amounts of nutrients that were taken up were neither incorporated into the biomass nor used as respiratory substrates, implying the considerable production and accumulation of several metabolites in the medium. Some of these are likely the products of forms of overflow metabolism. In addition, our results also show that arginine fermentation, contrary to what is typically assumed, occurs simultaneously with respiration and photosynthesis and can contribute energy in levels that are comparable to the primary bioenergetic modes, if not more. These findings portray a picture that the organism takes an approach toward growth that favors the here and now, even at the cost of longer-term concerns. We believe that the seemingly "greedy" behavior exhibited actually consists of adaptations by the organism to its natural environments, where nutrients are not only irregularly available but may altogether be absent for extended periods that may span several years. Such a setting probably predisposed the cells to grow as much as possible when the conditions become favorable

    TQM implementation: An empirical examination and proposed generic model

    Get PDF
    Total quality management (TQM) is considered by many as an important quality and business performance improvement tool. The popularity of the concept has led to an explosion of TQM related literature. A careful review of the literature suggests that most publications recount the experiences or perceptions of the authors or deal with single case organisations. Furthermore, there is a dearth of empirical research and literature dealing with TQM's implementation process. This paper reports the findings of a research project that empirically examined the process of TQM implementation in a sample of organisations widely regarded as leading exponents of TQM. The paper presents a non-prescriptive model of the TQM implementation process derived from the findings and proposes an "outcome driven" approach as an alternative to the more commonplace TQM implementation strategies

    Development of a Forage Evaluation System for Perennial Ryegrass Cultivar and Endophyte Combinations in New Zealand Dairy Systems

    Get PDF
    An economic index for perennial ryegrass (Lolium perenne L.) cultivars is a relatively new concept, although recently introduced in Ireland (McEvoy et al. 2011). By contrast, in dairy cattle breeding, the concept of an economic index rating animals and economic values underlying that index is well entrenched (Philipson et al. 1994; Veerkamp, 1998). Historically, forage evaluation data for individual cultivars were either displayed using absolute numbers for seasonal dry matter production within a season or across all seasons with a notation to indicate statistical differences, or percentage values where a reference cultivar is 100. The adoption of an economic index and routine evaluation approach for perennial ryegrass provides a method to identify traits of economic importance to focus plant breeding efforts better and to provide clarity for farmers around predicting cultivars that will maximise farm profit. It also allows for routine tracking of genetic gain of individual traits and the economic index. In this paper, the economic based forage evaluation techniques now used in New Zealand for perennial ryegrass cultivar/endophyte combinations are presented

    On mapping seafloor mineral deposits with central loop transient electromagnetics

    Get PDF
    Electromagnetic methods are commonly employed in exploration for land-based mineral deposits. A suite of airborne, land, and borehole electromagnetic techniques consisting of different coil and dipole configurations have been developed over the last few decades for this purpose. In contrast, although the commercial value of marine mineral deposits has been recognized for decades, the development of suitable marine electromagnetic methods for mineral exploration at sea is still in its infancy. One particularly interesting electromagnetic method, which could be used to image a mineral deposit on the ocean floor, is the central loop configuration. Central loop systems consist of concentric transmitting and receiving loops of wire. While these types of systems are frequently used in land-based or airborne surveys, to our knowledge neither system has been used for marine mineral exploration. The advantages of using central loop systems at sea are twofold: (1) simplified navigation, because the transmitter and receiver are concentric, and (2) simplified operation because only one compact unit must be deployed. We produced layered seafloor type curves for two particular types of central loop methods: the in-loop and coincident loop configurations. In particular, we consider models inspired by real marine mineral exploration scenarios consisting of overburdens 0 to 5 m thick overlying a conductive ore body 5 to 30 m thick. Modeling and resolution analyses showed that, using a 50 m(2) transmitting loop with 20 A of current, these two configurations are useful tools to determine the overburden depth to a conductive ore deposit and its thickness. In the most extreme case, absolute voltage errors on the order of 10 nV are required to resolve the base of a 30 m thick ore deposit. Whether such noise floors can be achieved in real marine environments remains to be seen

    Reprogrammable CRISPR/Cas9-based system for inducing site-specific DNA methylation

    Get PDF
    Advances in sequencing technology allow researchers to map genome-wide changes in DNA methylation in development and disease. However, there is a lack of experimental tools to site-specifically manipulate DNA methylation to discern the functional consequences. We developed a CRISPR/Cas9 DNA methyltransferase 3A (DNMT3A) fusion to induce DNA methylation at specific loci in the genome. We induced DNA methylation at up to 50% of alleles for targeted CpG dinucleotides. DNA methylation levels peaked within 50 bp of the short guide RNA (sgRNA) binding site and between pairs of sgRNAs. We used our approach to target methylation across the entire CpG island at the CDKN2A promoter, three CpG dinucleotides at the ARF promoter, and the CpG island within the Cdkn1a promoter to decrease expression of the target gene. These tools permit mechanistic studies of DNA methylation and its role in guiding molecular processes that determine cellular fate

    Parental age effects on neonatal white matter development.

    Get PDF
    OBJECTIVE: Advanced paternal age is associated with poor offspring developmental outcome. Though an increase in paternal age-related germline mutations may affect offspring white matter development, outcome differences could also be due to psychosocial factors. Here we investigate possible cerebral changes prior to strong environmental influences using brain MRI in a cohort of healthy term-born neonates. METHODS: We used structural and diffusion MRI images acquired soon after birth from a cohort (n = 275) of healthy term-born neonates. Images were analysed using a customised tract based spatial statistics (TBSS) processing pipeline. Neurodevelopmental assessment using the Bayley-III scales was offered to all participants at age 18 months. For statistical analysis neonates were compared in two groups, representing the upper quartile (paternal age ≥38 years) and lower three quartiles. The same method was used to assess associations with maternal age. RESULTS: In infants with older fathers (≥38 years), fractional anisotropy, a marker of white matter organisation, was significantly reduced in three early maturing anatomical locations (the corticospinal tract, the corpus callosum, and the optic radiation). Fractional anisotropy in these locations correlated positively with Bayley-III cognitive composite score at 18 months in the advanced paternal age group. A small but significant reduction in total brain volume was also observed in in the infants of older fathers. No significant associations were found between advanced maternal age and neonatal imaging. CONCLUSIONS: The epidemiological association between advanced paternal age and offspring outcome is extremely robust. We have for the first time demonstrated a neuroimaging phenotype of advanced paternal age before sustained parental interaction that correlates with later outcome

    Epigenomic regulation of human T-cell leukemia virus by chromatin-insulator CTCF

    Get PDF
    Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that causes an aggressive T-cell malignancy and a variety of inflammatory conditions. The integrated provirus includes a single binding site for the epigenomic insulator, CCCTC-binding protein (CTCF), but its function remains unclear. In the current study, a mutant virus was examined that eliminates the CTCF-binding site. The mutation did not disrupt the kinetics and levels of virus gene expression, or establishment of or reactivation from latency. However, the mutation disrupted the epigenetic barrier function, resulting in enhanced DNA CpG methylation downstream of the CTCF binding site on both strands of the integrated provirus and H3K4Me3, H3K36Me3, and H3K27Me3 chromatin modifications both up- and downstream of the site. A majority of clonal cell lines infected with wild type HTLV-1 exhibited increased plus strand gene expression with CTCF knockdown, while expression in mutant HTLV-1 clonal lines was unaffected. These findings indicate that CTCF binding regulates HTLV-1 gene expression, DNA and histone methylation in an integration site dependent fashion
    • …
    corecore