Dietary linoleic acid has no effect on arachidonic acid,but increases n-6 eicosadienoic acid,and lowers dihomo-γ-linolenic and eicosapentaenoic acid in plasma of adult men

High intakes of linoleic acid (LA,18:2n-6) have raised concern due to possible increase in arachidonic acid (ARA, 20:4n-6) synthesis, and inhibition of alpha linolenic acid (ALA, 18:3n-3) desaturation to eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). In healthy men, 10.5% energy compared to 3.8% energy LA with 1% energy ALA increased plasma phospholipid LA and 20:2n-6, the elongation product of LA, and decreased EPA, with no change in ARA. However, LA was inversely related to ARA at both 10.5% energy and 3.8% energy LA, (r=?0.761, r=?0.817, p<0.001, respectively). A two-fold variability in ARA among individuals was not explained by the dietary LA, ARA, ALA, or fish intake. Our results confirm LA requirements for ARA synthesis is low, <3.8% energy, and they suggest current LA intakes saturate Δ-6 desaturation and adversely affect n-3 fatty acid metabolism. Factors other than n-6 fatty acid intake are important modifiers of plasma ARA.     

Large litter size increases maternal energy intake but has no effect on UCP1 content and serum-leptin concentrations in lactating Brandt’s voles (<Emphasis Type="Italic">Lasiopodomys brandtii</Emphasis>)

Lactation is the most energetically demanding period in the female mammal's life. We measured maternal energy intake, uncoupling protein 1 (UCP1) content in brown adipose tissue (BAT), serum-leptin concentration, and litter growth in lactating Brandt's voles (Lasiopodomys brandtii) with different litter sizes. Litter mass was positively related to litter size but there was no difference in pup mass at birth. Maternal gross energy intake at peak lactation was positively correlated with litter size and litter mass. Maternal resting metabolic rate (RMR) was positively correlated with litter mass, but not with litter size. No significant differences were detected in body-fat mass, serum-leptin concentration, or UCP1 in lactating voles with different litter sizes. Serum-leptin concentration was negatively correlated with energy intake during lactation. Our data did not support the hypothesis that there is a trade-off in energy allocation between maternal maintenance and offspring growth in lactating Brandt's voles, but support the idea that if the mothers with ten pups should have less energy available for their maintenance than mothers raising fewer pups. Also, leptin is probably not the only factor that induces the high energy intake in mothers with large litter sizes, although it was involved in the regulation of energy intake during lactation.     

Application of a partitioning procedure based on Rao quadratic entropy index to characterize the temporal evolution of in situ varietal and genetic diversity of bread wheat in France over the period 1981–2006

Key message

We present and highlight a partitioning procedure based on the Rao quadratic entropy index to assess temporal in situ inter-annual varietal and genetic changes of crop diversity.

Abstract

For decades, Western-European agroecosystems have undergone profound changes, among which a reduction of crop genetic diversity. These changes have been highlighted in numerous studies, but no unified partitioning procedure has been proposed to compute the inter-annual variability in both varietal and genetic diversity. To fill this gap, we tested, adjusted and applied a partitioning procedure based on the Rao quadratic entropy index that made possible to describe the different components of crop diversity as well as to account for the relative acreages of varieties. To emphasize the relevance of this procedure, we relied on a case study focusing on the temporal evolution of bread wheat diversity in France over the period 1981–2006 at both national and district scales. At the national scale, we highlighted a decrease of the weighted genetic replacement indicating that varieties sown in the most recent years were more genetically similar than older ones. At the district scale, we highlighted sudden changes in weighted genetic replacement in some agricultural regions that could be due to fast shifts of successive leading varieties over time. Other regions presented a relatively continuous increase of genetic similarity over time, potentially due to the coexistence of a larger number of co-leading varieties that got closer genetically. Based on the partitioning procedure, we argue that a tendency of in situ genetic homogenization could be compared to some of its potential causes, such as a decrease in the speed of replacement or an increase in between-variety genetic similarity over time.