MiRNome variations in milk fractions during feed restrictions of different intensities in dairy cows.

BACKGROUND: In dairy cows, diet is one factor that can affect their milk production and composition. However, the effect of feed restriction on milk miRNome has not yet been described. Indeed, milk is the body fluid with the highest RNA concentration, which includes numerous microRNA. Its presence in the four different milk fractions, whole milk, fat globules, mammary epithelial cells and extracellular vesicles, is still poorly documented. This study aimed to describe the effects of different feed restrictions on the miRNome composition of different milk fractions. RESULTS: Two feed restrictions were applied to lactating dairy cows, one of high intensity and one of moderate intensity. 2,896 mature microRNA were identified in the different milk fractions studied, including 1,493 that were already known in the bovine species. Among the 1,096 microRNA that were sufficiently abundant to be informative, the abundance of 1,027 of them varied between fractions: 36 of those were exclusive to one milk fraction. Feed restriction affected the abundance of 155 microRNA, with whole milk and milk extracellular vesicles being the most affected, whereas milk fat globules and exfoliated mammary epithelial cells were little or not affected at all. The high intensity feed restriction led to more microRNA variations in milk than moderate restriction. The target prediction of known microRNA that varied under feed restriction suggested the modification of some key pathways for lactation related to milk fat and protein metabolisms, cell cycle, and stress responses. CONCLUSIONS: This study highlighted that the miRNome of each milk fraction is specific, with mostly the same microRNA composition but with variations in abundance between fractions. These specific miRNomes were affected differently by feed restrictions, the intensity of which appeared to be a major factor modulating milk miRNomes. These findings offer opportunities for future research on the use of milk miRNA as biomarkers of energy status in dairy cows, which is affected by feed restrictions.

Milk proteins as a feed restriction signature indicating the metabolic adaptation of dairy cows.

Milk production in dairy cows is affected by numerous factors, including diet. Feed restriction is known to have little impact on milk total protein content but its effect on the fine protein composition is still poorly documented. The objective of this study was to describe the effects of two feed restriction trials of different intensities on the milk protein composition of Holstein cows. One restriction trial was of high intensity (H: 8 mid-lactation Holstein cows) and the second of moderate intensity (M: 19 peak lactation Holstein cows). Feed restriction decreased the milk protein yield for caseins under the M trial and of all six major milk proteins under the H trial. These decreased yields lead to lower concentrations of αs1-, αs2- and ß-caseins during the H trial. The milk proteome, analyzed on 32 milk samples, was affected as a function of restriction intensity. Among the 345 proteins identified eight varied under the M trial and 160 under the H trial. Ontology analyses revealed their implication in carbohydrate, lipid and protein metabolisms as well as in the immune system. These proteins reflected adaptations of the animal and mammary gland physiology to feed restriction and constituted a signature of this change.

Characterization of Holstein and Normande whole milk miRNomes highlights breed specificities.

The concept of milk as a healthy food has opened the way for studies on milk components, from nutrients to microRNAs, molecules with broad regulatory properties present in large quantities in milk. Characterization of these components has been performed in several species, such as humans and bovine, depending on the stages of lactation. Here, we have studied the variation in milk microRNA composition according to genetic background. Using high throughput sequencing, we have characterized and compared the milk miRNomes of Holstein and Normande cattle, dairy breeds with distinct milk production features, in order to highlight microRNAs that are essential for regulation of the lactation process. In Holstein and Normande milk, 2,038 and 2,030 microRNAs were identified, respectively, with 1,771 common microRNAs, of which 1,049 were annotated and 722 were predicted. The comparison of the milk miRNomes of two breeds allowed to highlight 182 microRNAs displaying significant differences in the abundance. They are involved in the regulation of lipid metabolism and mammary morphogenesis and development, which affects lactation. Our results provide new insights into the regulation of molecular mechanisms involved in milk production.

Comparison of isogenic lines provides evidence that phenotypic plasticity is under genetic control in rainbow trout Oncorhynchus mykiss.

Comparison of nine isogenic lines of rainbow trout Oncorhynchus mykiss kept in the same environment showed significant genetic determinism of phenotypic plasticity assessed through body mass measurements. Ranking of lines differed between two tested environments.

Short communication: Mouse mammary tumor virus driven α-lactalbumin expression effects on lactation and fertility of transgenic mice.

α-Lactalbumin (Alac) is one of the major milk proteins. Its gene expression is restricted to epithelial cells of the lactating mammary gland. The Alac interaction with a uridine 5'-diphosphate-galactosyltransferase induces lactose synthesis, a major osmotic regulator of milk secretion. Other functions attributed to this protein include induction of apoptosis and anti-inflammatory activities. To assess if forced expression of this gene during early gestation or involution could affect mammary physiology, an Alac-encoding minigene was expressed in transgenic mice under the transcriptional regulation of the mouse mammary tumor virus promoter. The mammary expression did not interfere with gestation, resulted in a slight increase in milk yield as indirectly assessed by the 11% increased growth rate of the pups reared by transgenic females compared with that of those reared by control mice, and induced a slight delay in the early involution process, as demonstrated by histological analyses. The use of the mouse mammary tumor virus promoter resulted in Alac expression in several nonmammary tissues, such as the brain, the testis, the ovary, and the uterus. Although it did not affect male reproductive performances, it induced a female subfertile phenotype, characterized by embryonic implantation failure in the transgenic female reproductive tract.

[Infective endocarditis in children without underlying heart disease: a retrospective study analyzing 11 cases]. / Endocardite infectieuse sur coeur sain chez l'enfant: étude rétrospective de 11 cas.

The aim of our study was to determine the different characteristics of infective endocarditis in children without underlying heart disease. This was a descriptive, retrospective study including all cases of infective endocarditis without underlying heart disease occurring in children under 18 years of age, hospitalized at the Timone Children's Hospital in Marseille, France, between 1997 and 2008. The clinical, microbiological, and echocardiography data; treatment; and outcome were reviewed for each case. Over an 11-year period, 26 children were hospitalized with infective endocarditis. Eleven children (7 boys) had no underlying heart disease (42 %). Their mean age was 8 years and 3 months. Underlying conditions including neoplasm, preterm birth, and central venous catheter were found in 6 cases. A heart murmur was observed in 82 % of the children. A microorganism was isolated in 10 children (91 %). Staphylococcus aureus was the most common agent (45 %), followed by fungi (18 %). Echocardiography detected cardiac complications in 7 cases (64 %). Ninety-one percent of the children received intravenous antibiotics for a mean duration of 45 days. Eighty-two percent of our patients required surgical intervention. In our series, 91 % of the patients met the modified Duke criteria defining infective endocarditis. In-hospital mortality was 11 %. Embolic complications were seen in 5 cases (45 %), patients whose cultures yielded S. aureus or fungal organisms were more likely to present complications. Infective endocarditis without heart disease has particular features that differ from those of congenital heart disease. This diagnosis must be considered when predisposing factors are present.

Maize Sh2 gene is constrained by natural selection but escaped domestication.

In Zea mays L., we studied the molecular evolution of Shrunken2 (Sh2), a gene that encodes the large subunits of a major enzyme in endosperm starch biosynthesis, ADP-glucose pyrophosphorylase. We compared 4669 bp of the Sh2 coding region on 50 accessions of maize and teosinte. Very few nucleotide polymorphisms were found when compared with other genes in Z. mays, revealing an effect of purifying selection in the whole species that predates domestication. Additionally, the comparison of Sh2 sequences in all Z. mays subspecies and outgroups Z. diploperennis and Tripsacum dactyloides suggests the occurrence of an ancient selective sweep in the Sh2 3' region. The amount and nature of nucleotide diversity are similar in both maize and teosinte, confirming previous results that suggested that Sh2 has not been involved in maize domestication. The very low level of nucleotide diversity as well as the highly conserved protein sequence suggest that natural selection retained effective Sh2 allele(s) long before agriculture started, making human selection inefficient on this gene.