122 research outputs found

    Lag and mixing during sediment transfer across the Tian Shan piedmont caused by climate-driven aggradation-incision cycles

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    Transient sediment storage and mixing of deposits of various ages during transport across alluvial piedmonts alter the clastic sedimentary record. We quantify buffering and mixing during cycles of aggradation–incision in the north piedmont of the Eastern Tian Shan. We complement existing chronologic data with 20 new luminescence ages and one cosmogenic radionuclide age of terrace abandonment and alluvial aggradation. Over the last 0.5 Myr, the piedmont deeply incised and aggraded many times per 100 kyr. Aggradation is driven by an increased flux of glacial sediment accumulated in the high range and flushed onto the piedmont by greater water discharge at stadial–interstadial transitions. After this sediment is evacuated from the high range, the reduced input sediment flux results in fluvial incision of the piedmont as fast as 9 cm year−1 and to depths up to 330 m. The timing of incision onset is different in each river and does not directly reflect climate forcing but the necessary time for the evacuation of glacial sediment from the high range. A significant fraction of sediments evacuated from the high range is temporarily stored on the piedmont before a later incision phase delivers it to the basin. Coarse sediments arrive in the basin with a lag of at least 7–14 kyrs between the first evacuation from the mountain and later basinward transport. The modern output flux of coarse sediments from the piedmont contains a significant amount of recycled material that was deposited on the piedmont as early as the Middle Pleistocene. Variations in temperature and moisture delivered by the Westerlies are the likely cause of repeated aggradation–incision cycles in the north piedmont instead of monsoonal precipitation. The arrival of the gravel front into the proximal basin is delayed relative to the fine-grained load and both are separated by a hiatus. This work shows, based on field observations and data, how sedimentary systems respond to climatic perturbations, and how sediment recycling and mixing can ensue

    Successful Long-Term Preservation of Rat Sperm by Freeze-Drying

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    Background: Freeze-drying sperm has been developed as a new preservation method where liquid nitrogen is no longer necessary. An advantage of freeze-drying sperm is that it can be stored at 4uC and transported at room temperature. Although the successful freeze-drying of sperm has been reported in a number of animals, the possibility of long-term preservation using this method has not yet been studied. Methodology/Principal Findings: Offspring were obtained from oocytes fertilized with rat epididymal sperm freeze-dried using a solution containing 10 mM Tris and 1 mM EDTA adjusted to pH 8.0. Tolerance of testicular sperm to freeze-drying was increased by pre-treatment with diamide. Offspring with normal fertility were obtained from oocytes fertilized with freeze-dried epididymal sperm stored at 4uC for 5 years. Conclusions and Significance: Sperm with –SS – cross-linking in the thiol-disulfide of their protamine were highly tolerant to freeze-drying, and the fertility of freeze-dried sperm was maintained for 5 years without deterioration. This is the first report to demonstrate the successful freeze-drying of sperm using a new and simple method for long-term preservation

    Mutations involving the SRY-related gene SOX8 are associated with a spectrum of human reproductive anomalies

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    SOX8 is an HMG-box transcription factor closely related to SRY and SOX9. Deletion of the gene encoding Sox8 in mice causes reproductive dysfunction but the role of SOX8 in humans is unknown. Here, we show that SOX8 is expressed in the somatic cells of the early developing gonad in the human and influences human sex-determination. We identified two individuals with 46,XY disorders/differences in sex development (DSD) and chromosomal rearrangements encompassing the SOX8 locus and a third individual with 46,XY DSD and a missense mutation in the HMG-box of SOX8. In-vitro functional assays indicate that this mutation alters the biological activity of the protein. As an emerging body of evidence suggests that DSDs and infertility can have common etiologies, we also analyzed SOX8 in a cohort of infertile men (n = 274) and two independent cohorts of women with primary ovarian insufficiency (POI; n = 153 and n = 104). SOX8 mutations were found at increased frequency in oligozoospermic men (3.5%; p<0.05) and POI (5.06%; p=4.5x10-5) as compared to fertile/normospermic control populations (0.74%). The mutant proteins identified altered SOX8 biological activity as compared to the wild-type protein. These data demonstrate that SOX8 plays an important role in human reproduction and SOX8 mutations contribute to a spectrum of phenotypes including 46,XY DSD, male infertility and 46,XX POI

    Structure-Based Analysis of Five Novel Disease-Causing Mutations in 21-Hydroxylase-Deficient Patients

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    Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is the most frequent inborn error of metabolism, and accounts for 90–95% of CAH cases. The affected enzyme, P450C21, is encoded by the CYP21A2 gene, located together with a 98% nucleotide sequence identity CYP21A1P pseudogene, on chromosome 6p21.3. Even though most patients carry CYP21A1P-derived mutations, an increasing number of novel and rare mutations in disease causing alleles were found in the last years. In the present work, we describe five CYP21A2 novel mutations, p.R132C, p.149C, p.M283V, p.E431K and a frameshift g.2511_2512delGG, in four non-classical and one salt wasting patients from Argentina. All novel point mutations are located in CYP21 protein residues that are conserved throughout mammalian species, and none of them were found in control individuals. The putative pathogenic mechanisms of the novel variants were analyzed in silico. A three-dimensional CYP21 structure was generated by homology modeling and the protein design algorithm FoldX was used to calculate changes in stability of CYP21A2 protein. Our analysis revealed changes in protein stability or in the surface charge of the mutant enzymes, which could be related to the clinical manifestation found in patients

    Clinical relevance of ErbB-2/HER2 nuclear expression in breast cancer

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    <p>Abstract</p> <p>Background</p> <p>The biological relevance of nuclear ErbB-2/HER2 (NuclErbB-2) presence in breast tumors remains unexplored. In this study we assessed the clinical significance of ErbB-2 nuclear localization in primary invasive breast cancer. The reporting recommendations for tumor marker prognostic studies (REMARK) guidelines were used as reference.</p> <p>Methods</p> <p>Tissue microarrays from a cohort of 273 primary invasive breast carcinomas from women living in Chile, a Latin American country, were examined for membrane (MembErbB-2) and NuclErbB-2 expression by an immunofluorescence (IF) protocol we developed. ErbB-2 expression was also evaluated by immunohistochemistry (IHC) with a series of antibodies. Correlation between NuclErbB-2 and MembErbB-2, and between NuclErbB-2 and clinicopathological characteristics of tumors was studied. The prognostic value of NuclErbB-2 in overall survival (OS) was evaluated using Kaplan-Meier method, and Cox model was used to explore NuclErbB-2 as independent prognostic factor for OS.</p> <p>Results</p> <p>The IF protocol we developed showed significantly higher sensitivity for detection of NuclErbB-2 than IHC procedures, while its specificity and sensitivity to detect MembErbB-2 were comparable to those of IHC procedures. We found 33.6% NuclErbB-2 positivity, 14.2% MembErbB-2 overexpression by IF, and 13.0% MembErbB-2 prevalence by IHC in our cohort. We identified NuclErbB-2 positivity as a significant independent predictor of worse OS in patients with MembErbB-2 overexpression. NuclErbB-2 was also a biomarker of lower OS in tumors that overexpress MembErbB-2 and lack steroid hormone receptors.</p> <p>Conclusions</p> <p>We revealed a novel role for NuclErbB-2 as an independent prognostic factor of poor clinical outcome in MembErbB-2-positive breast tumors. Our work indicates that patients presenting NuclErbB-2 may need new therapeutic strategies involving specific blockage of ErbB-2 nuclear migration.</p

    Mutations involving the SRY-related gene SOX8 are associated with a spectrum of human reproductive anomalies.

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    © The Author(s) 2018. Published by Oxford University Press. All rights reserved. SOX8 is an HMG-box transcription factor closely related to SRY and SOX9. Deletion of the gene encoding Sox8 in mice causes reproductive dysfunction but the role of SOX8 in humans is unknown. Here, we show that SOX8 is expressed in the somatic cells of the early developing gonad in the human and influences human sex determination. We identified two individuals with 46, XY disorders/differences in sex development (DSD) and chromosomal rearrangements encompassing the SOX8 locus and a third individual with 46, XY DSD and a missense mutation in the HMG-box of SOX8. In vitro functional assays indicate that this mutation alters the biological activity of the protein. As an emerging body of evidence suggests that DSDs and infertility can have common etiologies, we also analysed SOX8 in a cohort of infertile men (n=274) and two independent cohorts of women with primary ovarian insufficiency (POI; n=153 and n=104). SOX8 mutations were found at increased frequency in oligozoospermic men (3.5%; P < 0.05) and POI (5.06%; P=4.5×10 -5 ) as compared with fertile/normospermic control populations (0.74%). The mutant proteins identified altered SOX8 biological activity as compared with the wild-type protein. These data demonstrate that SOX8 plays an important role in human reproduction and SOX8 mutations contribute to a spectrum of phenotypes including 46, XY DSD, male infertility and 46, XX POI.Link_to_subscribed_fulltex

    Restoration of Cenozoic deformation in Asia and the size of Greater India

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