Allocation of body reserves during winter in eider Somateria mollissima as preparation for spring migration and reproduction

Capital breeders, such as the eider duck Somateria mollissima, accumulate resources before the start of breeding. Eiders preferentially feed on blue mussels Mytilus edulis to build up body condition during winter. We explored how body condition and gizzard mass of wintering eiders relate to mussel quality and quantity, winter climate and body condition of females at the breeding grounds. Body condition during winter (defined as scaled body mass index) of eiders increased during winter and the magnitude of the effect depended on age and mussel quality. Gizzard mass of eiders increased during winter with effects of mussel quality, mussel stocks and sex. Body condition in winter of adult females increased from the first half of January to the second half of February on average by 1.5%, equal to c. 96 g. During the same period gizzard mass of adult females increased by 12.2%, i.e., a nearly ten-fold increase compared to that observed in body condition in winter. Body condition of females at the breeding grounds in Finland (defined as body condition at hatching) was significantly positively correlated with gizzard mass in winter, but not significantly correlated with body condition in winter. Thus, eiders allocate body reserves to increase gizzard mass but less so to increase body condition in winter. This can be considered an adaptive migratory strategy of these eiders, whereby large winter (pre-migratory) gizzards increase food processing capacity, making it possible for eiders to arrive at the breeding grounds with superior body condition and a high reproductive potential.Peer reviewe

Pre- and early-postnatal nutrition modify gene and protein expressions of muscle energy metabolism markers and phospholipid fatty acid composition in a muscle type specific manner in sheep.

We previously reported that undernutrition in late fetal life reduced whole-body insulin sensitivity in adult sheep, irrespective of dietary exposure in early postnatal life. Skeletal muscle may play an important role in control of insulin action. We therefore studied a range of putative key muscle determinants of insulin signalling in two types of skeletal muscles (longissimus dorsi (LD) and biceps femoris (BF)) and in the cardiac muscle (ventriculus sinister cordis (VSC)) of sheep from the same experiment. Twin-bearing ewes were fed either 100% (NORM) or 50% (LOW) of their energy and protein requirements during the last trimester of gestation. From day-3 postpartum to 6-months of age (around puberty), twin offspring received a high-carbohydrate-high-fat (HCHF) or a moderate-conventional (CONV) diet, whereafter all males were slaughtered. Females were subsequently raised on a moderate diet and slaughtered at 2-years of age (young adults). The only long-term consequences of fetal undernutrition observed in adult offspring were lower expressions of the insulin responsive glucose transporter 4 (GLUT4) protein and peroxisome proliferator-activated receptor gamma, coactivator 1α (PGC1α) mRNA in BF, but increased PGC1α expression in VSC. Interestingly, the HCHF diet in early postnatal life was associated with somewhat paradoxically increased expressions in LD of a range of genes (but not proteins) related to glucose uptake, insulin signalling and fatty acid oxidation. Except for fatty acid oxidation genes, these changes persisted into adulthood. No persistent expression changes were observed in BF and VSC. The HCHF diet increased phospholipid ratios of n-6/n-3 polyunsaturated fatty acids in all muscles, even in adults fed identical diets for 1½ years. In conclusion, early postnatal, but not late gestation, nutrition had long-term consequences for a number of determinants of insulin action and metabolism in LD. Tissues other than muscle may account for reduced whole body insulin sensitivity in adult LOW sheep

Automated Fragmentation Polarizable Embedding Density Functional Theory (PE-DFT) Calculations of Nuclear Magnetic Resonance (NMR) Shielding Constants of Proteins with Application to Chemical Shift Predictions

Full-protein nuclear magnetic resonance (NMR) shielding constants based on <i>ab initio</i> calculations are desirable, because they can assist in elucidating protein structures from NMR experiments. In this work, we present NMR shielding constants computed using a new automated fragmentation (<i>J. Phys. Chem. B</i> <b>2009</b>, <i>113</i>, 10380–10388) approach in the framework of polarizable embedding density functional theory. We extend our previous work to give both basis set recommendations and comment on how large the quantum mechanical region should be to successfully compute ¹³C NMR shielding constants that are comparable with experiment. The introduction of a probabilistic linear regression model allows us to substantially reduce the number of snapshots that are needed to make comparisons with experiment. This approach is further improved by augmenting snapshot selection with chemical shift predictions by which we can obtain a representative subset of snapshots that gives the smallest predicted error, compared to experiment. Finally, we use this subset of snapshots to calculate the NMR shielding constants at the PE-KT3/pcSseg-2 level of theory for all atoms in the protein GB3