Milk replacer feeding once or twice a day did not change the ruminal metabolomic profile and the microbial diversity of dairy calves from birth to weaning.

In commercial dairy production systems, feeding calves once a day could be an alternative to reduce labor expenses. Several studies comparing once (OAD) versus twice (TAD) a day milk feeding systems have not evidenced differences in calf growth, rumen development, blood parameters or health scores, but impact on ruminal microbiota remains to be investigated. The objective of this study was to determine the effects of OAD or TAD on the establishment of the ruminal microbiota and its metabolic activity. Sixteen male calves (45.9 ± 5.7 kg at birth) were involved in the trial from birth to weaning (63 d). After the colostrum phase, 2 feeding programs based on a milk replacer were tested and calves were allocated to these programs on d 5. To study the establishment of the bacterial community, ruminal fluid was obtained from each calf one hour after the morning meal at 7 (d 7), 35 (d 35) and 63 (d 63) days of age. The ruminal metabolome was evaluated at a 7 d interval from d 1 to d 63. Ruminal microbiota and metabolite profiles were characterized by 16 S rRNA gene sequencing- and by H-NMR spectroscopy, respectively. Our results showed that feeding milk replacer once or twice a day did not change the ruminal microbiota and metabolites of dairy calves from birth to weaning. Microbial data showed that diversity and richness increased with age, suggesting a shift from an heterogeneous and less diverse community after birth (d 7) to a more diverse but homogeneous community at 35 and 63 d. These findings suggest that feeding milk once a day can be successfully applied to a calf feeding system without compromising microbial establishment and functions.

Genotoxicity of aflatoxins and their precursors in human cells.

Aflatoxins are found as food contaminant and some of them demonstrate a carcinogenic effect. The aflatoxins biosynthetic pathway involves 15 successive steps. The aim of this study was to compare the toxicity of aflatoxins and their precursors in three human cell lines. We tested the four aflatoxins and two of their metabolites; three early metabolic precursors and two late biosynthetic precursors. Cyclopiazonic acid, synthesized in parallel with aflatoxins, was also tested. The cytotoxicity and the genotoxicity was evaluated with the γH2AX assay in three human cell lines with different bioactivation capacities. Our results indicated that the most genotoxic chemicals in the three cell lines were in decreasing order sterigmatocystin (ST), aflatoxin B1 (AFB1), aflatoxicol (AFL), aflatoxin G1 (AFG1) and versicolorin A (VERA). Aflatoxin M1 (AFM1) demonstrated genotoxic property in only one cell line. The other tested compounds did not demonstrate any genotoxic activity. Overall, our results suggested different genotoxic mechanisms of action for the tested compounds, involving specific bioactivation pathways. Moreover, some metabolic precursors of aflatoxins demonstrated genotoxic potential equivalent or greater to AFB1. This should be taking into account for the development of new strategies intended to reduce the aflatoxins exposure and for human risk assessment.

Dietary exposure to a low dose of pesticides alone or as a mixture: the biological metabolic fingerprint and impact on hematopoiesis.

Consumers are exposed to a mixture of pesticides through their food intake. These compounds are considered risk factors for human health, and the impact of dietary exposure to low doses of pesticide mixtures remains poorly understood. For this study we developed a mouse model to mimic consumer exposure in order to compare the effect of pesticides both alone or combined at doses corresponding to their Acceptable Daily Intake value. Female mice were exposed to pesticides throughout gestation and lactation. After weaning pups were fed the same pesticide-enriched diet their mothers had received for an additional 11 weeks. A metabonomic approach using (1)H NMR-based analysis of plasma showed that exposure to each pesticide produced a specific metabolic fingerprint in adult offspring. Discriminant metabolites between groups were glucose or lactate, choline, glycerophosphocholine and phosphocholine. Interestingly, metabolite differences were observed as early as weaned animals that had not yet been directly exposed themselves. Studies of the hematopoietic system revealed that dietary exposure to one particular pesticide, endosulfan, produced a significant decrease in red blood cell and hemoglobin levels, consistent with hemolytic anemia. Moreover, cell signaling profiles of bone marrow progenitors were also clearly affected. Expression of cell signaling proteins such as P35, CDC27, FAK, P38 MAP kinase, calcineurin and caspase as well as proteins involved in the stability or structure of the cytoskeleton (vinculin, MAP2) was changed upon dietary exposure to pesticides. Finally, we found that dietary exposure to a mixture of pesticides had effects that differed and were often lesser or equal to that of the most efficient pesticide (endosulfan), suggesting that the effect of pesticide mixtures cannot always be predicted from the combined effects of their constituent compounds.

Phenotypic prediction based on metabolomic data for growing pigs from three main European breeds.

Predicting phenotypes is a statistical and biotechnical challenge, both in medicine (predicting an illness) and animal breeding (predicting the carcass economical value on a young living animal). High-throughput fine phenotyping is possible using metabolomics, which describes the global metabolic status of an individual, and is the closest to the terminal phenotype. The purpose of this work was to quantify the prediction power of metabolomic profiles for commonly used production phenotypes from a single blood sample from growing pigs. Several statistical approaches were investigated and compared on the basis of cross validation: raw data vs. signal preprocessing (wavelet transformation), with a single-feature selection method. The best results in terms of prediction accuracy were obtained when data were preprocessed using wavelet transformations on the Daubechies basis. The phenotypes related to meat quality were not well predicted because the blood sample was taken some time before slaughter, and slaughter is known to have a strong influence on these traits. By contrast, phenotypes of potential economic interest (e.g., lean meat percentage and ADFI) were well predicted (R(2) = 0.7; P < 0.0001) using metabolomic data.

Gender-linked haematopoietic and metabolic disturbances induced by a pesticide mixture administered at low dose to mice.

Defining the impact on health of exposure to a low-dose pesticide mixture via food intake is a topical question since epidemiological studies suggest that this may increase the risk of pathologies and particularly haematopoietic malignancies. Here we investigated on the haematopoietic system of mice, the effect of a mixture of six pesticides frequently ingested through the intake of fruits and vegetables produced in France (alachlor, captan, diazinon, endosulfan, maneb, mancozeb). The mixture was administered repeatedly by gavage to mice for 4 weeks at levels derived from the human Acceptable Daily Intake (ADI) level adapted to the mean weight of mice. Using a NMR-based metabonomic approach, we show that this treatment led to specific gender-linked variations in the level of hepatic metabolites involved in oxidative stress and in the regulation of glucose metabolism, indicating a metabolic signature for this repeated administration. Interestingly, exposure to the low-dose pesticide mixture induced significant changes in the blood cell counts with modifications in the clonogenic and differentiating capacities of haematopoietic progenitors showing abnormalities in the granulocytic and monocytic lineages in female and male mice, respectively. From a molecular point of view, the changes induced by the pesticide treatment correlated with modifications of the PI 3-kinase/Akt signalling pathway, the tyrosine kinase Pyk2 and the c-Myc transcription factor, which are involved in the balance between self-renewal and differentiation of haematopoietic stem cells. Our results point to a significant effect of a very low dose of a mixture of commonly used pesticides on mice metabolism and haematopoietic system with major differences between males and females.

Metabolism of [14C]-2,4,6-trinitrotoluene in tobacco cell suspension cultures.

The metabolism of 2,4,6-trinitrotoluene (TNT) was investigated in tobacco cell suspension cultures amended with [14C]-TNT. Five metabolites were purified and characterized. Temporal evolution of metabolites was monitored during a 120 h incubation period. Metabolites structure was identified by acid and enzymatic hydrolysis, followed by electrospray ionization mass spectrometry and 1H and 13C NMR spectroscopy analyses. The majority of metabolites were conjugates formed by glycose conjugation on the hydroxylamine group of either 2-hydroxylamino-4,6-dinitrotoluene (2-HADNT) or 4-hydroxylamino-2,6-dinitrotoluene (4-HADNT), which led to monoglycoside then to diglycoside. Various diglycosides were observed with gentiobioside or sophoroside formation. Bound residues represented a small fraction (<10% of initial 14C) irrespective of the interval after TNT amendment. Free ADNT was detected only in the medium. This study highlights the central role played by HADNT in the TNT metabolic pathway in tobacco cell suspension culture, and the key role of these compounds and of glycosyltransferases in TNT phytoremediation processes.

Filtering of spinning sidebands in 1D MAS NMR spectra.

Spinning sidebands (SSBs) in the MAS NMR spectrum of a polycrystalline solid are related to the principal values of the chemical shift or quadrupole coupling tensors. At present, 2D methods are widely used to sort out the SSBs for each isotropic peak. Here a simple and efficient method for separating the SSBs in 1D MAS NMR spectra is described. It is based on finding the optimal spinning rate with a mathematical algorithm and subsequently treating the spectra with filtering functions.

Diastereomeric Shape Recognition Using NMR Spectroscopy in a Chiral Liquid Crystalline Solvent.

Unambiguous assignment of the resonances of different diastereomers in a nonracemic mixture is possible with (1)H-decoupled (2)H NMR spectroscopy in a chiral liquid crystalline solvent. This is demonstrated with, for example, the alpha,alpha'-dideuterated diol shown in the picture. Even diastereomers with centers of chirality up to nine bonds apart can be discriminated.