[Abstract unavailable

Glycine is a major amino acid in mammals and other animals. It is synthesized from serine, threonine, choline, and hydroxyproline via inter-organ metabolism involving primarily the liver and kidneys. Under normal feeding conditions, glycine is not adequately synthesized in birds or in other animals, particularly in a diseased state. Glycine degradation occurs through three pathways: the glycine cleavage system (GCS), serine hydroxymethyltransferase, and conversion to glyoxylate by peroxisomal D-amino acid oxidase. Among these pathways, GCS is the major enzyme to initiate glycine degradation to form ammonia and CO2 in animals. In addition, glycine is utilized for the biosynthesis of glutathione, heme, creatine, nucleic acids, and uric acid. Furthermore, glycine is a significant component of bile acids secreted into the lumen of the small intestine that is necessary for the digestion of dietary fat and the absorption of long-chain fatty acids. Glycine plays an important role in metabolic regulation, anti-oxidative reactions, and neurological function. Thus, this nutrient has been used to: (1) prevent tissue injury; (2) enhance anti-oxidative capacity; (3) promote protein synthesis and wound healing; (4) improve immunity; and (5) treat metabolic disorders in obesity, diabetes, cardiovascular disease, ischemia-reperfusion injuries, cancers, and various inflammatory diseases. These multiple beneficial effects of glycine, coupled with its insufficient de novo synthesis, support the notion that it is a conditionally essential and also a functional amino acid for mammals (including pigs and humans).

Amino acids (AA) have enormous physiological importance, serving as building blocks for proteins and substrates for synthesis of low-molecular-weight substances. Based on growth or nitrogen balance, AA were traditionally classified as nutritionally essential or nonessential for animals. Although those AA that are not synthesized in eukaryotes (nutritionally essential AA, EAA) must be present in animal diets, nutritionally nonessential AA (NEAA) have long been ignored for all species. Emerging evidence shows that nonruminants cannot adequately synthesize NEAA or conditionally essential AA (CEAA) to realize their growth or anti-infection potential. Likewise, all preformed AA are needed for high-producing cows and rapidly growing ruminants. Many NEAA and CEAA (e.g., arginine, glutamine, glutamate, glycine, and proline) and certain EAA (e.g., leucine and tryptophan) participate in cell signaling, gene expression, and metabolic regulation. Thus, functions of AA beyond protein synthesis must be considered in dietary formulations to improve efficiency of nutrient use, growth, development, reproduction, lactation, and well-being in animals.

Pt single sites are highly attractive due to their high atom economy and can be generated on CeO2 by an oxidative high-temperature treatment. However, their location and activity are strongly debated. Furthermore, reaction-driven structural dynamics have not been addressed so far. Here, we were able to evidence Ptinduced CeO2 surface restructuring, locate Pt single sites on CeO2 and track the variation of the active state under reaction conditions using a complementary approach of density functional theory calculations, in situ infrared spectroscopy, operando high-energy-resolution fluorescence detected X-ray absorption spectroscopy and catalytic CO (as well as C3H6 and CH4) oxidation. We find that the onset of CO oxidation is linked to the migration of Pt single sites from four-fold hollow sites to form small clusters containing few Pt atoms. This demonstrates that operando studies on single sites are essential to assess their fate and the resulting catalytic properties. a promise as they lower the noble metal content significantly as all atoms are potentially active species. [5][6][7][8][9] Exploiting the strong noble metal support interaction between Pt and CeO2, metallic Pt particles can be formed orin contrast to weakly interacting supports like Al2O3redispersed, with tremendous impact on the catalyst activity. [10][11][12][13] The preparation of SAC has been demonstrated for Pt, which can be atomically dispersed when using CeO2 as a support through an oxidizing treatment at 800 °C. 14 However, the exact structure of the single sites, their reactivity and, particularly, their state and dynamics during reaction are still unknown and heavily debated. 4,15,16 The location of Pt single sites is claimed to range from surface adsorbates on {111} ceria steps, 17,18 {111}, 19 {110} 20,21 or {100} 6,22,23 ceria facets to surface 21,24,25 or bulk Ce substitutes [26][27][28] forming Ce1-XPt 2+ XO2-Y-composites. During change of the gas atmosphere and of the temperature, the structure of the single sites may strongly change resulting in a new and more active state. For example, after a high temperature treatment strong Pt-O-Ce bonds are reported to over-stabilize the single sites which are thus less active. 29 During the catalytic oxidation, oxygen is suggested to be provided by the support, while the reactant e.g. CO is adsorbed directly on Pt, 22,25 similar to Pt nanoparticles on CeO2. 30 Bera et al. correlated the intensity of the Pt-O-Ce bond observed by Extended X-ray Absorption Fine Structure (EXAFS) measurements with the catalytic activity for Ce1-XPt 2+ XO2-Y, 31 and Nie et al. 24demonstrated that the catalytic activation of a Pt single atom catalyst can be increased by steam treatment. It is suggested that this treatment leads to the formation of Ce1-XPt 2+ XO2-YH-OH species that are catalytically more active than Ce1-XPt 2+ XO2-Y. 24 In contrast, other studies report an increase in catalytic activity after a reductive treatment at temperatures below 300 °C. 9,32-34 Importantly, such

Analysis across the genome of patterns of DNA methylation reveals a rich landscape of allele-specific epigenetic modification and consequent effects on allele-specific gene expression.