An accreted continental terrane in Northwestern Peru

Cet article présente une étude paléomagnétique des échantillons de plusieurs formations du bassin de Lancones (province de Piura). Les auteurs formulent l'hypothèse de l'accrétion d'une terrane sur la marge péruvienne au cours du Néocomien. Un régime de cisaillement aurait également produit des rotations in situ. L'évolution géodynamique du nord du Pérou est donc comparable aux processus observés sur les Andes septentrionales, en Equateu

Magnetic dating of the Holocene monogenetic Tkarsheti volcano in the Kazbeki region (Great Caucasus)

The radiocarbon technique is widely used to date Late Pleistocene and Holocene lava flows. The significant difference with palaeomagnetic methods is that the 14C dating is performed on the organic matter carbonized by the rock formation or the paleosols found within or below the lava flow. On the contrary, the archaeomagnetic dating allows to date the moment when the lava is cooling down below the Curie temperatures. In the present study, we use the paleomagnetic dating to constrain the age of the Tkarsheti monogenetic volcano located within the Kazbeki Volcanic Province (Great Caucasus). A series of rock-magnetic experiments including the measurement of hysteresis curves, isothermal remanence, back-field and continuous thermomagnetic curves were applied. These experiments indicated that Pseudo-Single-Domain Ti-poor titanomagnetite is responsible for remanence. A characteristic remanent magnetization was obtained for all twenty analyzed samples yielding a stable single magnetization component observed upon both thermal and alternating field treatments. Comparison of the mean directions obtained (Inc = 48.6º, Dec = 6.4º, A95 = 4.0° and K = 67) with the SCHA.DIF.14k model yielded two main time intervals (4740–4650 or 4427– 4188 BC) as the best age estimate of the Lesser Tkarsheti lava flow. These results suggest an earlier age (between approximately 200 and 700 years) for this monogenetic lava flow than expected from the estimated age provided by a former 14C dating obtained in 1973 on woody remains. This first attempt to use the archaeomagnetic technique in the Caucasus indicates that the SCHA.DIF.14k geomagnetic model may be successfully used for dating purposes in the region.Projects BU0066U16 and BU235P18 (Junta de Castilla y Leon, Spain) and the European Regional Development Fund (ERDF). AG is grateful for financial support of CONACyT 252149 and UNAM-PAPIIT project 101717. MC-R and AC acknowledge the financial support given by the Junta de Castilla y León (project BU235P18) and the European Regional Development Fund (ERD)

Microbial Dysbiosis in Colorectal Cancer (CRC) Patients

The composition of the human intestinal microbiota is linked to health status. The aim was to analyze the microbiota of normal and colon cancer patients in order to establish cancer-related dysbiosis

Siah1 proteins enhance radiosensitivity of human breast cancer cells

<p>Abstract</p> <p>Background</p> <p>Siah proteins play an important role in cancer progression. We evaluated the effect of Siah1, its splice variants Siah1L and the Siah1 mutant with the RING finger deleted (Siah1ΔR) on radiosensitization of human breast cancer cells.</p> <p>Methods</p> <p>The status of Siah1 and Siah1L was analysed in five breast cancer cell lines. To establish stable cells, SKBR3 cells were transfected with Siah1, Siah-1L and Siah1ΔR. Siah1 function was suppressed by siRNA in MCF-7 cells. The impact of Siah1 overexpression and silencing on apoptosis, proliferation, survival, invasion ability and DNA repair was assessed in SKBR3 and MCF-7 cells, also in regards to radiation.</p> <p>Results</p> <p>Siah1 and Siah1L mRNA expression was absent in four of five breast cancer cells lines analysed. Overexpression of Siah1 and Siah1L enhanced radiation-induced apoptosis in stable transfected SKBR3 cells, while Siah1ΔR failed to show this effect. In addition, Siah1 and Siah1L significantly reduced cell clonogenic survival and proliferation. Siah1L sensitization enhancement ratio values were over 1.5 and 4.0 for clonogenic survival and proliferation, respectively, pointing to a highly cooperative and potentially synergistic fashion with radiation. Siah1 or Siah1L significantly reduced invasion ability of SKBR3 and suppressed Tcf/Lef factor activity. Importantly, Siah1 siRNA demonstrated opposite effects in MCF-7 cells. Siah1 and Siah1L overexpression resulted in inhibition of DNA repair as inferred by increased levels of DNA double-strand breaks in irradiated SKBR3 cells.</p> <p>Conclusion</p> <p>Our results reveal for the first time how overexpression of Siah1L and Siah1 can determine radiosensitivity of breast cancer cells. These findings suggest that development of drugs augmenting Siah1 and Siah1L activity could be a novel approach in improving tumor cell kill.</p

miR-135A Regulates Preimplantation Embryo Development through Down-Regulation of E3 Ubiquitin Ligase Seven in Absentia Homolog 1A (SIAH1A) Expression

Background: MicroRNAs (miRNAs) are small non-coding RNA molecules capable of regulating transcription and translation. Previously, a cluster of miRNAs that are specifically expressed in mouse zygotes but not in oocytes or other preimplantation stages embryos are identified by multiplex real-time polymerase chain reaction-based miRNA profiling. The functional role of one of these zygote-specific miRNAs, miR-135a, in preimplantation embryo development was investigated. Methodology/Principal Findings: Microinjection of miR-135a inhibitor suppressed first cell cleavage in more than 30% of the zygotes. Bioinformatics analysis identified E3 Ubiquitin Ligase Seven In Absentia Homolog 1A (Siah1a) as a predicted target of miR-135a. Western blotting and 3′UTR luciferase functional assays demonstrated that miR-135a down-regulated the expression of Siah1 in HeLa cells and in mouse zygotes. Siah1a was expressed in preimplantation embryos and its expression pattern negatively correlated with that of miR-135a. Co-injection of Siah1a-specific antibody with miR-135a inhibitor partially nullified the effect of miR-135a inhibition. Proteasome inhibition by MG-132 revealed that miR-135a regulated proteasomal degradation and potentially controlled the expression of chemokinesin DNA binding protein (Kid). Conclusions/Significance: The present study demonstrated for the first time that zygotic specific miRNA modulates the first cell cleavage through regulating expression of Siah1a. © 2011 Pang et al.published_or_final_versio