Mathematical modelling in animal nutrition: a centenary review

A centenary review presents an opportunity to ponder over the processes of concept development and give thought to future directions. The current review aims to ascertain the ontogeny of current concepts, underline the connection between ideas and people and pay tribute to those pioneers who have contributed significantly to modelling in animal nutrition. Firstly, the paper draws a brief portrait of the use of mathematics in agriculture and animal nutrition prior to 1925. Thereafter, attention turns towards the historical development of growth modelling, feed evaluation systems and animal response models. Introduction of the factorial and compartmental approaches into animal nutrition is noted along with the particular branches of mathematics encountered in various models. Furthermore, certain concepts, especially bioenergetics or the heat doctrine, are challenged and alternatives are reviewed. The current state of knowledge of animal nutrition modelling results mostly from the discernment and unceasing efforts of our predecessors rather than serendipitous discoveries. The current review may stimulate those who wish for greater understanding and appreciation

A review of mathematical functions for the analysis of growth in poultry

Poultry industries face various decisions in the production cycle that affect the profitability of an operation. Predictions of growth when the birds are ready for sale are important factors that contribute to the economy of poultry operations. Mathematical functions called ‘growth functions’ have been used to relate body weight (W) to age or cumulative feed intake. These can also be used as response functions to predict daily energy and protein dietary requirements for maintenance and growth (France et al., 1989). When describing growth versus age in poultry, a fixed point of inflexion can be a limitation with equations such as the Gompertz and logistic. Inflexion points vary depending on age, sex, breed and type of animal, so equations such as the Richards and López are generally recommended. For describing retention rate against daily intake, which generally does not exhibit an inflexion point, the monomolecular would appear the function of choice

The pro-region of the Kex2 endoprotease of Saccharomyces cerevisiae is removed by self-processing

AbstractWe have produced in the baculovirus/insect cells expression system a soluble secreted form of the Saccharomyces cerevisiae Kex2 endoprotease. This secreted enzyme was purified and its NH2-terminal sequence determined. The NH2-terminal sequence started at residue Leu109 of the sequence deduced from the KEX2 gene nucleotide sequence, showing that the Kex2 enzyme is produced as a proenzyme. Residue Leu109 is preceded by a pair of basic amino acid residues (Lys107-Arg108) which is a potential processing site for the Kex2 endopeptidase. Futhermore, expression of an inactive form of this truncated enzyme resulted in the production of a protein with a higher molecular weight. These observations suggest that the pro-region of Kex2 endoprotease is removed by a self-processing event

High-throughput gene-expression quantification of grapevine defense responses in the field using microfluidic dynamic arrays

Background The fight against grapevine diseases due to biotrophic pathogens usually requires the massive use of chemical fungicides with harmful environmental effects. An alternative strategy could be the use of compounds able to stimulate plant immune responses which significantly limit the development of pathogens in laboratory conditions. However, the efficiency of this strategy in natura is still insufficient to be included in pest management programs. To understand and to improve the mode of action of plant defense stimulators in the field, it is essential to develop reliable tools that describe the resistance status of the plant upon treatment.[br/][br/] Results We have developed a pioneering tool (“NeoViGen96” chip) based on a microfluidic dynamic array platform allowing the expression profiling of 85 defense-related grapevine genes in 90 cDNA preparations in a 4 h single run. Two defense inducers, benzothiadiazole (BTH) and fosetyl-aluminum (FOS), have been tested in natura using the “NeoViGen96” chip as well as their efficacy against downy mildew.[br/] BTH-induced grapevine resistance is accompanied by the induction of PR protein genes (PR1, PR2 and PR3), genes coding key enzymes in the phenylpropanoid pathway (PAL and STS), a GST gene coding an enzyme involved in the redox status and an ACC gene involved in the ethylene pathway.[br/] FOS, a phosphonate known to possess a toxic activity against pathogens and an inducing effect on defense genes provided a better grapevine protection than BTH. Its mode of action was probably strictly due to its fungicide effect at high concentrations because treatment did not induce significant change in the expression level of selected defense-related genes.[br/] [br/] Conclusions The NeoViGen96” chip assesses the effectiveness of plant defense inducers on grapevine in vineyard with an excellent reproducibility. A single run with this system (4 h and 1,500 €), corresponds to 180 qPCR plates with conventional Q-PCR assays (Stragene system, 270 h and 9,000 €) thus a throughput 60–70 times higher and 6 times cheaper. Grapevine responses after BTH elicitation in the vineyard were similar to those obtained in laboratory conditions, whereas our results suggest that the protective effect of FOS against downy mildew in the vineyard was only due to its fungicide activity since no activity on plant defense genes was observed. This tool provides better understanding of how the grapevine replies to elicitation in its natural environment and how the elicitor potential can be used to reduce chemical fungicide inputs

Conceiving of addicted pleasures: A ‘modern’ paradox

Drawing on research with people who inject drugs in London, UK, this article will explore how participants conceived of pleasure, and try to understand some of the tensions that ensued. There is a strong sense in participants’ accounts that drug use is at points pleasurable but it should not, or rather, could not be conceived of in this way. As such, the article will reflect on several situations in which pleasure came up during fieldwork but was quickly redirected towards addiction using terms such as ‘denial’. Trying to make sense of this seemingly paradoxical dynamic, in which pleasure can be addictive, but addiction cannot be pleasurable, I turn to some of the practices that actively keep pleasure and addiction apart, indeed, in some areas of the addiction sciences, antithetical. That is, a singular account of pleasure is produced as freely chosen (of the ‘free’ subject) in opposition to the determined nature of addiction (of the automated brain or object). These realities materialise in participants’ accounts, but due to their constructed nature they also collapse and multiply. This ‘hybridisation’ is what Bruno Latour refers to as the paradox of the Moderns. Considering pleasure, however, as both natural and cultural, it is better conceived of as always in tension, expressed by participants as ‘mixed feelings’, ‘love/hate’, ‘sweet and sour’, ‘good things and bad things’. Against a backdrop of neglect, especially within the context of injecting drug use, such conceptualisation can help acknowledge pleasure where it is least conceivable and yet perhaps has the most to offer

CO Adsorption on Supported Gold Nanoparticle Catalysts: Application of the Temkin Model

The adsorption of CO on the supported gold nanoparticle catalysts Au/TiO2, Au/Fe2O3, and Au/ZrO2 was examined using infrared transmission spectroscopy to quantify the isobaric CO coverage as a function of temperature. The Temkin adsorbate interaction model was then applied to account for the adsorption behavior. To test the general applicability of the Temkin model, this treatment was also applied to three data sets from the literature. This included another real-world catalyst and two model catalysts. All data sets were accurately represented by the Temkin adsorbate interaction model. The resulting thermodynamic metrics are consistent with previous determinations and reflect a particle size-dependence. In particular, the intrinsic adsorption enthalpy at zero CO coverage varies almost linearly with Au particle size, and this trend appears to be correlated with the abundance of low-coordinate Au sites (cf., CN = 6 and 7 for corners and edges, respectively). For very small particles with mostly CN = 6 corner sites, the enthalpy reflects strong binding (cf., −ΔH0 ≈ 78 kJ/mol), while for large particles with mostly CN = 7 edge sites, the enthalpy reflects weaker binding (cf., −ΔH0 ≈ 63 kJ/mol). The results also suggest that these sites are coupled. This study demonstrates that the Temkin adsorbate interaction model accurately represents adsorption data, yields meaningful metrics that are useful for characterizing nanoparticle catalysts, and should be applicable to other adsorption data sets

A New Solution to the Purchasing Power Parity Puzzles: Risk-Aversion, Exchange Rate Uncertainty and the Law of One Price

We argue that even in perfectly frictionless markets risk aversion driven by exchange rate uncertainty may cause a wedge between the domestic and foreign price of a totally homogeneous good. We test our hypothesis using a natural experiment based on a unique micro-data set from a market with minimum imperfections. The empirical findings validate our hypothesis, as accounting for exchange rate uncertainty we are able to explain a substantial proportion of deviations from the law of one price. Overall, our analysis suggests the possibility of a new solution to the purchasing power parity puzzles

Autophosphorylation of Solanum chacoense cytosolic nucleoside diphosphate kinase on Ser117

NDPK catalyses the interconversion of NTPs and NDPs using a phosphohistidine intermediate as part of its catalytic site. Recombinant Solanum chacoense cytosolic NDPK incubated with [gamma-(32)P]ATP was allowed to autophosphorylate and (32)P-labelled P-Ser was identified in an acid hydrolysate of the protein by two-dimensional TLC. Further analysis of (32)P-labelled recombinant NDPK by tryptic digestion followed by automated Edman sequencing of the radioactive peptide allowed the identification of a single and conserved P-Ser residue at position 117. Analysis of site-directed mutants where Ser117 was substituted to Asp indicated that the presence of a negative charge at position 117 dramatically lowered the enzyme's catalytic efficiency. Ser autophosphorylation was markedly reduced with increasing ADP concentrations in the autophosphorylation assay. These findings provide evidence that autophosphorylation of cytosolic NDPK on Ser117 could constitute a regulatory mechanism for this important enzyme and that autophosphorylation of Ser117 is modulated by NDP availabilityNRC publication: Ye

Identification of EaeA protein in the outer membrane of attaching and effacing Escherichia coli O45 from pigs

NRC publication: Ye