Quantitative Determination of Phytate and Inorganic Phosphorus for Maize Breeding

Phytate is the dominant storage form of phosphorus (P) in mature cereal and oil grains. Phosphorus bound in phytate is nutritionally unavailable to monogastric animals and thus contributes to water pollution because it is excreted in the waste. Also, phytate can chelate certain minerals and exacerbate human mineral deficiencies. Our primary objective was to develop a rapid and inexpensive method of measuring phytate and inorganic P (Pi) concentrations in maize (Zea mays L.). The procedure reported herein was derived from previously published assays and used to screen 50 inbred lines to determine its potential in a selection program. Grain yield, protein, oil, methionine, lysine, tryptophan, and kernel weight were also measured. Field repeatability values for phytate and Pi (0.78 and 0.91, respectively) suggest that our protocol can be used to make heritable measurements on both traits. Phytate measurements taken with the procedure reported herein matched closely those obtained through ion exchange. The combination of adequate precision and simplicity make this method ideal for breeders interested in improving Pi and phytate levels simultaneously. The positive phytate:protein correlation reported commonly was also detected in this study. A relationship between phytate and kernel weight indicates that selection for low phytate may result in larger kernels

Genetic Variation and Breeding Potential of Phytate and Inorganic Phosphorus in a Maize Population

Seed P is predominantly bound in the organic compound phytate, which makes the bioavailability of P low for monogastric animals fed maize (Zea mays L.)-based diets. Decreasing phytate and increasing inorganic P (Pi, an available form of P) concentrations in maize grain would be desirable to help ameliorate environmental problems associated with high P in feces. Our objective was to investigate the potential of improving the P profile of maize grain through breeding and selection. Ninety S1 families from the BS31 population were evaluated at two locations for phytate, Pi, and other grain quality and agronomic traits. Phytate concentrations ranged from 1.98 to 2.46 g kg−1, and the broad-sense heritability (H) was relatively low (0.60). Both genetic variance and H (0.84) were much greater for Pi Few unfavorable genetic correlations were observed between either Pi or phytate and other key economic traits. Also, selection differentials of multiple trait indices indicated that the P profile of maize grain and grain yield and moisture could be improved simultaneously. Many cycles of selection will be needed, however, to reach desirable phytate and Pi concentrations, especially when selecting for multiple traits. Regardless, our results are encouraging given that the families evaluated were related S1 families and the number of families was relatively small

Inositol 1,3,4,5,6-pentakisphosphate 2-kinase is a distant IPK member with a singular inositide binding site for axial 2-OH recognition

Inositol phosphates (InsPs) are signaling molecules with multiple roles in cells. In particular Graphic (InsP6) is involved in mRNA export and editing or chromatin remodeling among other events. InsP6 accumulates as mixed salts (phytate) in storage tissues of plants and plays a key role in their physiology. Human diets that are exclusively grain-based provide an excess of InsP6 that, through chelation of metal ions, may have a detrimental effect on human health. Ins(1,3,4,5,6)P5 2-kinase (InsP5 2-kinase or Ipk1) catalyses the synthesis of InsP6 from InsP5 and ATP, and is the only enzyme that transfers a phosphate group to the axial 2-OH of the myo-inositide. We present the first structure for an InsP5 2-kinase in complex with both substrates and products. This enzyme presents a singular structural region for inositide binding that encompasses almost half of the protein. The key residues in substrate binding are identified, with Asp368 being responsible for recognition of the axial 2-OH. This study sheds light on the unique molecular mechanism for the synthesis of the precursor of inositol pyrophosphates

Quantitative trait loci conferring grain mineral nutrient concentrations in durum wheat 3 wild emmer wheat RIL population

Mineral nutrient malnutrition, and particularly deficiency in zinc and iron, afflicts over 3 billion people worldwide. Wild emmer wheat, Triticum turgidum ssp. dicoccoides, genepool harbors a rich allelic repertoire for mineral nutrients in the grain. The genetic and physiological basis of grain protein, micronutrients (zinc, iron, copper and manganese) and macronutrients (calcium, magnesium, potassium, phosphorus and sulfur) concentration was studied in tetraploid wheat population of 152 recombinant inbred lines (RILs), derived from a cross between durum wheat (cv. Langdon) and wild emmer (accession G18-16). Wide genetic variation was found among the RILs for all grain minerals, with considerable transgressive effect. A total of 82 QTLs were mapped for 10 minerals with LOD score range of 3.2–16.7. Most QTLs were in favor of the wild allele (50 QTLs). Fourteen pairs of QTLs for the same trait were mapped to seemingly homoeologous positions, reflecting synteny between the A and B genomes. Significant positive correlation was found between grain protein concentration (GPC), Zn, Fe and Cu, which was supported by significant overlap between the respective QTLs, suggesting common physiological and/or genetic factors controlling the concentrations of these mineral nutrients. Few genomic regions (chromosomes 2A, 5A, 6B and 7A) were found to harbor clusters of QTLs for GPC and other nutrients. These identified QTLs may facilitate the use of wild alleles for improving grain nutritional quality of elite wheat cultivars, especially in terms of protein, Zn and Fe

Standing on the shoulders of tech giants: Media delivery, streaming television, and the rise of global suppliers

This article uses the case study of Internet Protocol (IP) delivery for streaming television to demonstrate how technology and globalization combine to change what media firms do, how they create value, and with whom. Media delivery - the sum of the value-adding tasks necessary to transfer content from source to audience - has become a mosaic of technologies that sustain a complex and fast-evolving video ecosystem. Broadcasters had been in charge of the full transmission process once, of tasks deemed core to their business. Today, media delivery is externalized to the market and devolved to a network of suppliers. These suppliers are no ordinary firms, but tech giants that have developed deep global capabilities. They gain further leverage by being cross-sectoral, serving clients across multiple industries. Who are these suppliers? What makes them unique? And what are the implications for the television industry

Restricting digital sites of dissent: commercial social media and free expression

The widespread use of commercial social media platforms by protesters and activists has enhanced protest mobilisation and reporting but it has placed social media providers in the intermediary role as facilitators of dissent and has thereby created new challenges. Companies like Google and Facebook are increasingly restricting content that is published on or distributed through their platforms; they have been subject to obstruction by governments; and their services have been at the core of large-scale data collection and surveillance. This article analyses and categorises forms of infrastructure-based restrictions on free expression and dissent. It shows how private intermediaries have been incorporated into state-led content policies; how they set their own standards for legitimate online communication and intervene accordingly; and how state-based actions and commercial self-regulation intersect in the specific area of online surveillance. Based on a broad review of cases, it situates the role of social media in the wider trend of the privatisation of communications policy and the complex interplay between state-based regulation and commercial rule-making

The diversity of population responses to environmental change

This is the final version. Available from Wiley via the DOI in this record.Data available from the Dryad Digital Repository: https:// doi.org/10.5061/dryad.d5f54s7The current extinction and climate change crises pressure us to predict population dynamics with ever-greater accuracy. Although predictions rest on the well-advanced theory of age-structured populations, two key issues remain poorly explored. Specifically, how the age-dependency in demographic rates and the year-to-year interactions between survival and fecundity affect stochastic population growth rates. We use inference, simulations and mathematical derivations to explore how environmental perturbations determine population growth rates for populations with different age-specific demographic rates and when ages are reduced to stages. We find that stage- vs. age-based models can produce markedly divergent stochastic population growth rates. The differences are most pronounced when there are survival-fecundity-trade-offs, which reduce the variance in the population growth rate. Finally, the expected value and variance of the stochastic growth rates of populations with different age-specific demographic rates can diverge to the extent that, while some populations may thrive, others will inevitably go extinct.Max Planck Society, Marie Curie FellowshipERCGerman Research FoundationSwiss National Science FoundationNational Science FoundationNational Institute of AgingRamon y Cajal Research GrantWenner-Gren FoundationLeakey FoundationNational Geographic SocietyZoological Society of San DiegoUniversity of PennsylvaniaArgentinean National Council of Researc

Down-regulation of the myo-inositol oxygenase gene family has no effect on cell wall composition in Arabidopsis

The enzyme myo-inositol oxygenase (MIOX; E.C. 1.13.99.1) catalyzes the ring-opening four-electron oxidation of myo-inositol into glucuronic acid, which is subsequently activated to UDP-glucuronic acid (UDP-GlcA) and serves as a precursor for plant cell wall polysaccharides. Starting from single T-DNA insertion lines in different MIOX-genes a quadruple knockdown (miox1/2/4/5-mutant) was obtained by crossing, which exhibits greater than 90% down-regulation of all four functional MIOX genes. Miox1/2/4/5-mutant shows no visible phenotype and produces viable pollen. The alternative pathway to UDP-glucuronic acid via UDP-glucose is upregulated in the miox1/2/4/5-mutant as a compensatory mechanism. Miox1/2/4/5-mutant is impaired in the utilization of myo-inositol for seedling growth. The incorporation of myo-inositol derived sugars into cell walls is strongly (>90%) inhibited. Instead, myo-inositol and metabolites produced from myo-inositol such as galactinol accumulate in the miox1/2/4/5-mutant. The increase in galactinol and raffinose family oligosaccharides does not enhance stress tolerance. The ascorbic acid levels are the same in mutant and wild type plants

Food fight: conflicting language ideologies in English and French news and social media

Although social media provide new opportunities for minority language use and communication, the extent to which they differ from mainstream news media requires more investigation. This paper addresses this issue by comparing French and English language ideologies in Canadian news media and on Twitter. These ideologies are investigated using a specific case study where an Italian restaurant owner in French-speaking Canada was challenged for using Italian words on a menu. This generated extensive media coverage and Twitter activity. A corpus-assisted discourse study sheds insight on the complex dynamics of language politics and how they play out on different media platforms. It also indicates that minoritised groups are under growing pressure to translate linguistic cultures into English and globalised, market-driven contexts