The ‘Giant of Ksour’, a Middle Jurassic sauropod dinosaur from Algeria

Continental strata of Early and Middle Jurassic age are seldom-exposed, and little is known of the history of sauropod dinosaurs prior to the neosauropod radiation of the end of the Middle Jurassic. Here, we report, in the Middle Jurassic of the Occidental Saharan Atlas (Algerian High Atlas), the discovery of a skeleton, including cranial material, of a new cetiosaurid sauropod. Chebsaurus algeriensis n. g., n. sp. represents the most complete Algerian sauropod available to date, only few remains were found before. To cite this article: F. Mahammed et al., C. R. Palevol 4 (2005).     

Biological activities of recombinant chicken leptin C4S analog compared with unmodified leptins

The chicken leptin sequence, in contrast to mammalian leptins, contains an unpaired Cys at position 3 of the original cDNA (AF012727). The presence of an extra Cys may confer a different structure and affect the leptin's biological activity. To address this, we studied the effects of wild-type and mutated (C4S) chicken leptins in vitro and in vivo and compared them with mammalian leptin prepared from ovine leptin cDNA. The prokaryotic expression vector pMON, encoding full-size A(-1) chicken leptin (AF012727), was mutated using a mutagenesis kit, yielding the C4S analog. Escherichia coli cells transformed with this vector overexpressed large amounts of chicken leptin C4S upon induction with nalidixic acid. The expressed protein, found in the inclusion bodies, was refolded and purified to homogeneity on a Q-Sepharose column, yielding three electrophoretically pure fractions, eluted from the column by 100, 125, and 150 mM NaCl, respectively. All three fractions showed a single band of the expected molecular mass (16 kDa) and were composed of >95% monomeric protein. Proper refolding was evidenced by comparing the circular dichroism spectrum of the analog with spectra of nonmutated chicken and ovine leptins. The biological activity of the C4S analog was evidenced by its ability to stimulate proliferation of leptin-sensitive BAF/3 cells transfected with a long form of human leptin receptor construct similar to its nonmutated counterpart, indicating that Cys4 plays no role in leptin activity. The in vitro activity of both wild-type and mutated chicken leptins was approximately 10-fold lower than that of ovine leptin. After intravenous or intraperitoneal injections, C4S analog and the nonmutated chicken and ovine leptins all lowered the food intake of starved 9-day-old broiler or 5-wk-old layer male chickens by 11-34%. Monitoring food behavior revealed that the attenuated food intake resulted not from a decreased number of approaches to the feeders but from a decrease in the average time spent eating during each approach.     

Identification of an ABCA1-dependent phospholipid-rich plasma membrane apolipoprotein A-I binding site for nascent HDL formation: implications for current models of HDL biogenesis

It is well accepted that both apolipoprotein A-I (apoA-I) and ABCA1 play crucial roles in HDL biogenesis and in the human atheroprotective system. However, the nature and specifics of apoA-I/ABCA1 interactions remain poorly understood. Here, we present evidence for a new cellular apoA-I binding site having a 9-fold higher capacity to bind apoA-I compared with the ABCA1 site in fibroblasts stimulated with 22-(R)-hydroxycholesterol/9-cis-retinoic acid. This new cellular apoA-I binding site was designated "high-capacity binding site" (HCBS). Glyburide drastically reduced (125)I-apoA-I binding to the HCBS, whereas (125)I-apoA-I showed no significant binding to the HCBS in ABCA1 mutant (Q597R) fibroblasts. Furthermore, reconstituted HDL exhibited reduced affinity for the HCBS. Deletion of the C-terminal region of apoA-I (Delta187-243) drastically reduced the binding of apoA-I to the HCBS. Interestingly, overexpressing various levels of ABCA1 in BHK cells promoted the formation of the HCBS. The majority of the HCBS was localized to the plasma membrane (PM) and was not associated with membrane raft domains. Importantly, treatment of cells with phosphatidylcholine-specific phospholipase C, but not sphingomyelinase, concomitantly reduced the binding of (125)I-apoA-I to the HCBS, apoA-I-mediated cholesterol efflux, and the formation of nascent apoA-I-containing particles. Together, these data suggest that a functional ABCA1 leads to the formation of a major lipid-containing site for the binding and the lipidation of apoA-I at the PM. Our results provide a biochemical basis for the HDL biogenesis pathway that involves both ABCA1 and the HCBS, supporting a two binding site model for ABCA1-mediated nascent HDL genesis.     

RNA-Seq Signatures Normalized by mRNA Abundance Allow Absolute Deconvolution of Human Immune Cell Types

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Hrs is a positive regulator of VEGF and insulin signaling

Both VEGF and insulin are implicated in the pathogenesis of diabetic retinopathy. While it has been established for many years that the number of cell surface receptors impacts upon VEGF and insulin action, little is known about the precise machinery and proteins driving VEGF-R2 and IR degradation. Here, we investigate the role of Hepatocyte growth factor-Regulated tyrosine kinase Substrate (Hrs), a regulator of RTK trafficking, in VEGF and insulin signaling. We report that ectopic expression of Hrs increases VEGF-R2 and IR number and tyrosine phosphorylation, leading to amplification of their downstream signaling. The UIM (Ubiquitin Interacting Motif) domain of Hrs is required for Hrs-induced increases in VEGF-R2, but not in IR. Furthermore, Hrs is tyrosine-phosphorylated in response to VEGF and insulin. We show that the UIM domain is required for Hrs phosphorylation in response to VEGF, but not to insulin. Importantly, Hrs co-localizes with both VEGF-R2 and IR and co-immunoprecipitates with both in a manner independent of the Hrs-UIM domain. Finally, we demonstrate that Hrs inhibits Nedd4-mediated VEGF-R2 degradation and acts additively with Grb10. We conclude that Hrs is a positive regulator of VEGF-R2 and IR signaling and that ectopic expression of Hrs protects both VEGF-R2 and IR from degradation.     

Leptin downregulates heat shock protein-70 (HSP-70) gene expression in chicken liver and hypothalamus

Heat shock protein (HSP)-70 is expressed in normal and stressed cells but is highly stress-inducible. Although leptin has long been suggested to be involved in the regulation of stress response, its interaction with the HSP-70 gene is still unknown, under both unstressed and stressed conditions. The present study has aimed to investigate the effect of leptin on HSP-70 gene expression in normal chicken liver, hypothalamus, and muscle. Continuous infusion of recombinant chicken leptin (8 μg/kg per hour) at a constant rate of 3 ml/h for 6 h in 3-week-old broiler chickens significantly (P < 0.05) decreased food intake and HSP-70 mRNA levels in liver and hypothalamus, but not in muscle. In an attempt to discriminate between the effect of leptin and of leptin-reduced food intake on HSP-70 gene expression, we also evaluated the effect of food deprivation on the same cellular responses in two broiler chicken lines genetically selected for low (LL) or high (FL) abdominal fat pad size. Food deprivation for 16 h did not affect HSP-70 gene expression in any of the studied tissues indicating that the effect of leptin was independent of the inhibition of food intake. Regardless of the nutritional status, HSP-70 mRNA levels were significantly (P < 0.05) higher in the hypothalamus of FL compared with LL chickens consistent with higher mRNA levels for hypothalamic corticotropin-releasing factor. To assess, whether the effects of leptin were direct or indirect, we carried out in vitro studies. Leptin treatments did not affect HSP-70 mRNA levels in a leghorn male hepatoma cell line or quail myoblast cell line suggesting that the effect of leptin on HSP-70 gene expression is mediated through the central nervous system. Furthermore, HSP-70 gene expression was gender-dependent with significantly (P < 0.05) higher levels in male than in female chickens. This work was supported by a research grant (G.0402.05) from the FWO-Flanders (Belgium). No conflicts of interest would prejudice impartiality.     

The activities of 210Po and 210Pb in cigarette smoked in Tunisia

Radiation and Environmental Biophysics - In this study, the activity concentration of polonium 210 in cigarette for Tunisian consumers was investigated by alpha spectrometry. After chemical...