All diatoms are not equal in the biological carbon pump

International audienc

Quality and Export Performance Evidence from Cheese Industry

The paper questions the impact of quality label on firm export competitiveness in the cheese and cream industry. We use firm level data from the French custom and an original dataset of firms and products concerned by protected designations of origin (PDO). Our econometric estimations shows that PDO labelling impacts both the extensive margin (the number of destinations) and the intensive margin of trade (the value of trade), and increases the average export unit value. The role of label in export performance varies with the market of destination and is more important when exporting to EU countries

Depot-specific regulation of autotaxin with obesity in human adipose tissue.

International audienceAutotaxin (ATX) is a lysophospholipase D involved in synthesis of a bioactive mediator: lysophosphatidic. ATX is abundantly produced by adipocytes and exerts a negative action on adipose tissue expansion. In both mice and humans, ATX expression increases with obesity in association with insulin resistance. In the present study, fat depot-specific regulation of ATX was explored in human. ATX mRNA expression was quantified in visceral and subcutaneous adipose tissue in obese (BMI > 40 kg/m(2); n = 27) and non-obese patients (BMI < 25 kg/m(2); n = 10). Whatever the weight status of the patients is, ATX expression was always higher (1.3- to 6-fold) in subcutaneous than in visceral fat. Nevertheless, visceral fat ATX was significantly higher (42 %) in obese than in non-obese patients, whereas subcutaneous fat ATX remained unchanged. In obese patients, visceral fat ATX expression was positively correlated with diastolic arterial blood pressure (r = 0.67; P = 0.001). This correlation was not observed with subcutaneous fat ATX. Visceral fat ATX was mainly correlated with leptin (r = 0.60; P = 0.001), inducible nitric oxide synthase (r = 0.58; P = 0,007), and apelin receptor (r = 0.50; P = 0.007). These correlations were not observed with subcutaneous fat ATX. These results reveal that obesity-associated upregulation of human adipose tissue ATX is specific to the visceral fat depot

Comparative Functional Analysis of <em>ZFP36</em> Genes during <em>Xenopus</em> Development

<div><p>ZFP36 constitutes a small family of RNA binding proteins (formerly known as the TIS11 family) that target mRNA and promote their degradation. In mammals, ZFP36 proteins are encoded by four genes and, although they show similar activities in a cellular RNA destabilization assay, there is still a limited knowledge of their mRNA targets and it is not known whether or not they have redundant functions. In the present work, we have used the <em>Xenopus</em> embryo, a model system allowing gain- and loss-of-function studies, to investigate, whether individual ZFP36 proteins had distinct or redundant functions. We show that overexpression of individual amphibian zfp36 proteins leads to embryos having the same defects, with alteration in somites segmentation and pronephros formation. In these embryos, members of the Notch signalling pathway such as <em>hairy2a</em> or <em>esr5</em> mRNA are down-regulated, suggesting common targets for the different proteins. We also show that mouse Zfp36 protein overexpression gives the same phenotype, indicating an evolutionary conserved property among ZFP36 vertebrate proteins. Morpholino oligonucleotide-induced loss-of-function leads to defects in pronephros formation, reduction in tubule size and duct coiling alterations for both <em>zfp36</em> and <em>zfp36l1</em>, indicating no functional redundancy between these two genes. Given the conservation in gene structure and function between the amphibian and mammalian proteins and the conserved mechanisms for pronephros development, our study highlights a potential and hitherto unreported role of <em>ZFP36</em> gene in kidney morphogenesis.</p> </div

<i>Zfp36</i> mRNA overexpression induces somites segmentation defects.

<p>250 pg of mouse <i>zfp36</i> mRNA (a, b) or <i>Xenopus zfp36</i> (d, e), <i>zfp36l1</i> (I, j), <i>zfp36l2</i> (k, l) <i>or zfp36l4</i> (m, n) mRNA were injected into one blastomere of two-cell stage embryos and developing embryos were fixed at stage 28 before immunhistochemistry analysis with the somite specific marker 12/101. Embryos were embedded in paraffin then sectioned longitudinally (c, f) or treated for scanning electronic microscopy (g, h). The arrows mark the alteration of segmentation on the injected side (Inj) by comparison with the uninjected side (Uninj). no, notochord; so, somite.</p

<i>Zfp36</i> and <i>zfp36l1</i> morpholino knock down induces pronephros alterations.

<p>20 ng of morpholinos directed against <i>zfp36</i> (a, b) or <i>zfp36l1</i> (c, d) mRNAs or control morpholinos (e, f) were injected into one ventral blastomere of 8-cell stage embryos with 250 pg of <i>lacZ</i> mRNA. In rescue experiments, 100–200 pg of mouse <i>zfp36</i> mRNA were co-injected with 20 ng of MO <i>zfp36</i> (g, h). Developing embryos were fixed at stage 40 before <i>lacZ</i> staining and immunohistochemistry analysis to reveal the expression of pronephros specific markers, 3G8 and 4A6. Arrows and arrowheads in b, d, f and h, mark the pronephros proximal tubule (tu) and duct (du) respectively on injected sides of the embryos. I–p, Close up views of anterior region showing uninjected or injected sides of representative phenotypes for <i>zfp36</i> morphants (i–l) and <i>zfp36l1</i> morphants (m–p).</p

Conservative evolution of vertebrate <i>zfp36</i> genes.

<p>(A) Conserved syntenic regions between human (<i>Hsa</i>), mouse (<i>Mmu</i>) and <i>Xenopus tropicalis</i> (<i>Xtr</i>) chromosome regions containing <i>zfp36</i>, <i>zfp36l1</i> and <i>zfp36l2</i>. Gene names symbols are according to HUGO. Boxes with the same colour correspond to the same gene; white boxes correspond to genes without annotation or without orthologues in the species shown here. The drawing is not to scale to avoid complexity and dashes represent long chromosome regions. (B) Conserved structural organization of vertebrates <i>zfp36</i> genes between evolutionary distant animals. Exons (1, 2) are figured in open boxes and intron as a solid line respectively. Shaded box, untranslated region. TZF, Tandem Zing Finger domain.</p

<i>Zfp36</i> mRNA overexpression does not prevent mesoderm induction nor myogenic factor expression.

<p>(A) Two-cell stage embryos were injected with 250 pg of the different <i>Xenopus zfp36</i> mRNAs or mouse <i>zfp36</i> mRNA (<i>mzfp36</i>) and animal caps were explanted at stage 8.5–9 then treated with 10 ng/ml of activin before analysis by RT-PCR for <i>xbra</i> expression when control embryos reached stage 12. Stage 12 embryo (Emb) or untreated animal caps (-) were assayed by RT-PCR in parallel. <i>Odc</i> was used as control of loading and a reaction was performed in the absence of reverse transcriptase to check for genomic DNA contamination (-RT). (B) 250 pg of <i>Xenopus zfp36</i> (a, b) and <i>zfp36l1</i> (c, d) or mouse <i>Zfp36</i> (<i>mZfp36</i>, e, f) mRNAs were injected in one blastomere of two-cell stage embryos and developing embryos were fixed at stage 28 and analyzed by <i>in situ</i> hybridization for <i>myod</i> expression.</p

mRNA expression of <i>Xenopus zfp36</i> genes during development.

<p>(A) RT-PCR analyses showed that all <i>zfp36</i> genes are maternally expressed. <i>zfp36, zfp36l1</i> and <i>zfp36l2</i> mRNAs are expressed at a constant level throughout development from stage 2 to stage 33 while <i>zfp36l4</i> mRNA level decreases after the mid-blastula transition (MBT, arrow). (B) <i>In situ</i> hybridization showed that all four <i>zfp36</i> mRNA are localized at the animal pole in 4-cell stage (a–d) and morula stage (i–l) embyos. e–h correspond to histological sections from embryos shown in a–d. (C) RT-PCR analysis showed that <i>zfp36</i> mRNAs are preferentially expressed in the animal pole region of blastula embryos. (D) RT-PCR analysis showed that <i>zfp36</i> mRNAs are expressed throughout the embryo at the gastrula stage. An, animal pole; DM, dorsal marginal zone; Emb, whole embryo; Ve, vegetal pole; VM, ventral marginal zone. A control embryo (Emb) assayed by RT-PCR for the expression of control genes <i>chordin</i> and <i>wnt8</i>. <i>odc</i> was used as control of loading and a reaction was performed in the absence of reverse transcriptase to check for genomic DNA contamination (-).</p