310 research outputs found

    Potential impacts of climatic warming on glacier-fed river flows in the Himalaya

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    The Himalayan region is one of the most highly glacierised areas on Earth. Regarded as the “water towers” of Asia, the Himalayas are the source of several of the world’s major rivers. The region is inhabited by some 140 million people and ten times as many (~1.4 billion) live in its downstream river basins. Freshwater from the mountains is vital for the region’s economy and for sustaining the livelihoods of a fast-growing population. Climatic warming and the rapid retreat of Himalayan glaciers over recent decades have raised concerns about the future reliability of mountain melt-water resources, leading to warnings of catastrophic water shortages. Several previous studies have assessed climate change impacts on specific glacier-fed rivers, usually applying meso-scale catchment models for short simulation periods during which glacier dimensions remain unchanged. Few studies have attempted to estimate the effects on a regional scale, partly because of the paucity of good quality data across the Himalaya. The aim of this study was to develop a parsimonious grid-based macro-scale hydrological model for the Indus, Ganges and Brahmaputra basins that, in order to represent transient melt-water contributions from retreating glaciers, innovatively allowed glacier dimensions to change over time. The model initially was validated over the 1961-90 standard period and then applied in each basin with a range of climate-change scenarios (sensitivity analysis- and climate-model-based) over a 100-year period, to gain insight on potential changes in mean annual and winter flows (water availability proxies) at decadal time-steps. Plausible results were obtained, showing impacts vary considerably across the region (catchments in the east appear much less susceptible to glacier retreat effects than those in the west, due to the influence of the summer monsoon), and, in central and eastern Himalayan catchments, from upstream to downstream (effects diminish rapidly downstream due to higher runoff from non-glaciated parts)

    Monorail/Foxa2 regulates floorplate differentiation and specification of oligodendrocytes, serotonergic raphe neurones and cranial motoneurones

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    In this study, we elucidate the roles of the winged-helix transcription factor Foxa2 in ventral CNS development in zebrafish. Through cloning of monorail (mol), which we find encodes the transcription factor Foxa2, and phenotypic analysis of mol(-/-) embryos, we show that floorplate is induced in the absence of Foxa2 function but fails to further differentiate. In mol(-/-) mutants, expression of Foxa and Hh family genes is not maintained in floorplate cells and lateral expansion of the floorplate fails to occur. Our results suggest that this is due to defects both in the regulation of Hh activity in medial floorplate cells as well as cell-autonomous requirements for Foxa2 in the prospective laterally positioned floorplate cells themselves. Foxa2 is also required for induction and/or patterning of several distinct cell types in the ventral CNS. Serotonergic neurones of the raphe nucleus and the trochlear motor nucleus are absent in mol(-/-) embryos, and oculomotor and facial motoneurones ectopically occupy ventral CNS midline positions in the midbrain and hindbrain. There is also a severe reduction of prospective oligodendrocytes in the midbrain and hindbrain. Finally, in the absence of Foxa2, at least two likely Hh pathway target genes are ectopically expressed in more dorsal regions of the midbrain and hindbrain ventricular neuroepithelium, raising the possibility that Foxa2 activity may normally be required to limit the range of action of secreted Hh proteins

    Effects of gestational age at birth on cognitive performance : a function of cognitive workload demands

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    Objective: Cognitive deficits have been inconsistently described for late or moderately preterm children but are consistently found in very preterm children. This study investigates the association between cognitive workload demands of tasks and cognitive performance in relation to gestational age at birth. Methods: Data were collected as part of a prospective geographically defined whole-population study of neonatal at-risk children in Southern Bavaria. At 8;5 years, n = 1326 children (gestation range: 23–41 weeks) were assessed with the K-ABC and a Mathematics Test. Results: Cognitive scores of preterm children decreased as cognitive workload demands of tasks increased. The relationship between gestation and task workload was curvilinear and more pronounced the higher the cognitive workload: GA2 (quadratic term) on low cognitive workload: R2 = .02, p<0.001; moderate cognitive workload: R2 = .09, p<0.001; and high cognitive workload tasks: R2 = .14, p<0.001. Specifically, disproportionally lower scores were found for very (<32 weeks gestation) and moderately (32–33 weeks gestation) preterm children the higher the cognitive workload of the tasks. Early biological factors such as gestation and neonatal complications explained more of the variance in high (12.5%) compared with moderate (8.1%) and low cognitive workload tasks (1.7%). Conclusions: The cognitive workload model may help to explain variations of findings on the relationship of gestational age with cognitive performance in the literature. The findings have implications for routine cognitive follow-up, educational intervention, and basic research into neuro-plasticity and brain reorganization after preterm birth

    Арап ŃĐ»ĐžŃ„Đ±Đ”ŃĐžĐœĐŽĐ” ĐœĐ”ŃˆĐžŃ€ ŃŃ‚ĐžĐ»ŃŒĐłĐ”Đœ ĐșŃŠŃ‹Ń€Ń‹ĐŒŃ‚Đ°Ń‚Đ°Ń€ ĐłŃ€Đ°ĐŒĐŒĐ°Ń‚ĐžĐșĐ°Đ»Đ°Ń€ĐœŃ‹ĐœŃŠ Ń‚Đ”ĐœŃŠĐ”ŃˆŃ‚ĐžŃ€ĐŒĐ” талОлО

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    Статья ĐżĐŸŃĐČŃŃ‰Đ”ĐœĐ° ŃĐŸĐżĐŸŃŃ‚Đ°ĐČĐžŃ‚Đ”Đ»ŃŒĐœĐŸĐŒŃƒ Đ°ĐœĐ°Đ»ĐžĐ·Ńƒ ĐžĐŒĐ”ĐœĐž ŃŃƒŃ‰Đ”ŃŃ‚ĐČĐžŃ‚Đ”Đ»ŃŒĐœĐŸĐłĐŸ Đž ĐłĐ»Đ°ĐłĐŸĐ»Đ° ĐČ Đ°Ń€Đ°Đ±ĐŸĐłŃ€Đ°Ń„ĐžŃ‡Đ”ŃĐșох ĐłŃ€Đ°ĐŒĐŒĐ°Ń‚ĐžĐșах ĐșŃ€Ń‹ĐŒŃĐșĐŸŃ‚Đ°Ń‚Đ°Ń€ŃĐșĐŸĐłĐŸ ŃĐ·Ń‹ĐșĐ°.Стаття просĐČŃŃ‡Đ”ĐœĐ° ĐżĐŸŃ€Ń–ĐČĐœŃĐ»ŃŒĐœĐŸĐŒŃƒ Đ°ĐœĐ°Đ»Ń–Đ·Ńƒ Ń–ĐŒĐ”ĐœĐœĐžĐșĐ° і ĐŽŃ–Ń”ŃĐ»ĐŸĐČĐ° ĐČ Đ°Ń€Đ°Đ±ĐŸĐłŃ€Đ°Ń„Ń–Ń‡ĐœĐžŃ… ĐłŃ€Đ°ĐŒĐ°Ń‚ĐžĐșах ĐșŃ€ĐžĐŒŃŃŒĐșĐŸŃ‚Đ°Ń‚Đ°Ń€ŃŃŒĐșĐŸŃ— ĐŒĐŸĐČĐž.The article annotation is devoted to the comparative analysis of the noun and the verb in arabographis grammars of the Crimean Tatar language

    DMSO and Betaine Greatly Improve Amplification of GC-Rich Constructs in De Novo Synthesis

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    In Synthetic Biology, de novo synthesis of GC-rich constructs poses a major challenge because of secondary structure formation and mispriming. While there are many web-based tools for codon optimizing difficult regions, no method currently exists that allows for potentially phenotypically important sequence conservation. Therefore, to overcome these limitations in researching GC-rich genes and their non-coding elements, we explored the use of DMSO and betaine in two conventional methods of assembly and amplification. For this study, we compared the polymerase (PCA) and ligase-based (LCR) methods for construction of two GC-rich gene fragments implicated in tumorigenesis, IGF2R and BRAF. Though we found no benefit in employing either DMSO or betaine during the assembly steps, both additives greatly improved target product specificity and yield during PCR amplification. Of the methods tested, LCR assembly proved far superior to PCA, generating a much more stable template to amplify from. We further report that DMSO and betaine are highly compatible with all other reaction components of gene synthesis and do not require any additional protocol modifications. Furthermore, we believe either additive will allow for the production of a wide variety of GC-rich gene constructs without the need for expensive and time-consuming sample extraction and purification prior to downstream application

    A New Basal Sauropod Dinosaur from the Middle Jurassic of Niger and the Early Evolution of Sauropoda

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    The early evolution of sauropod dinosaurs is poorly understood because of a highly incomplete fossil record. New discoveries of Early and Middle Jurassic sauropods have a great potential to lead to a better understanding of early sauropod evolution and to reevaluate the patterns of sauropod diversification.A new sauropod from the Middle Jurassic of Niger, Spinophorosaurus nigerensis n. gen. et sp., is the most complete basal sauropod currently known. The taxon shares many anatomical characters with Middle Jurassic East Asian sauropods, while it is strongly dissimilar to Lower and Middle Jurassic South American and Indian forms. A possible explanation for this pattern is a separation of Laurasian and South Gondwanan Middle Jurassic sauropod faunas by geographic barriers. Integration of phylogenetic analyses and paleogeographic data reveals congruence between early sauropod evolution and hypotheses about Jurassic paleoclimate and phytogeography.Spinophorosaurus demonstrates that many putatively derived characters of Middle Jurassic East Asian sauropods are plesiomorphic for eusauropods, while South Gondwanan eusauropods may represent a specialized line. The anatomy of Spinophorosaurus indicates that key innovations in Jurassic sauropod evolution might have taken place in North Africa, an area close to the equator with summer-wet climate at that time. Jurassic climatic zones and phytogeography possibly controlled early sauropod diversification

    Wolbachia-Induced Unidirectional Cytoplasmic Incompatibility and Speciation: Mainland-Island Model

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    Bacteria of the genus Wolbachia are among the most common endosymbionts in the world. In many insect species these bacteria induce a sperm-egg incompatibility between the gametes of infected males and uninfected females, commonly called unidirectional cytoplasmic incompatibility (CI). It is generally believed that unidirectional CI cannot promote speciation in hosts because infection differences between populations will be unstable and subsequent gene flow will eliminate genetic differences between diverging populations. In the present study we investigate this question theoretically in a mainland-island model with migration from mainland to island. Our analysis shows that (a) the infection polymorphism is stable below a critical migration rate, (b) an (initially) uninfected “island” can better maintain divergence at a selected locus (e.g. can adapt locally) in the presence of CI, and (c) unidirectional CI selects for premating isolation in (initially) uninfected island populations if they receive migration from a Wolbachia-infected mainland. Interestingly, premating isolation is most likely to evolve if levels of incompatibility are intermediate and if either the infection causes fecundity reductions or Wolbachia transmission is incomplete. This is because under these circumstances an infection pattern with an infected mainland and a mostly uninfected island can persist in the face of comparably high migration. We present analytical results for all three findings: (a) a lower estimation of the critical migration rate in the presence of local adaptation, (b) an analytical approximation for the gene flow reduction caused by unidirectional CI, and (c) a heuristic formula describing the invasion success of mutants at a mate preference locus. These findings generally suggest that Wolbachia-induced unidirectional CI can be a factor in divergence and speciation of hosts

    Lung transplantation for pulmonary fibrosis in dyskeratosis congenita: Case Report and systematic literature review

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    <p>Abstract</p> <p>Background</p> <p>Dyskeratosis congenita (DC) is a progressive, multi-system, inherited disorder of telomere biology with high risks of morbidity and mortality from bone marrow failure, hematologic malignancy, solid tumors and pulmonary fibrosis. Hematopoietic stem cell transplantation (HSCT) can cure the bone marrow failure, but it does not eliminate the risks of other complications, for which life-long surveillance is required. Pulmonary fibrosis is a progressive and lethal complication of DC.</p> <p>Case presentation</p> <p>In this report, we describe a patient with DC who developed pulmonary fibrosis seven years after HSCT for severe aplastic anemia, and was successfully treated with bilateral lung transplantation. We also performed a systematic literature review to understand the burden of pulmonary disease in patients with DC who did or did not receive an HSCT. Including our patient, we identified 49 DC patients with pulmonary disease (12 after HSCT and 37 without HSCT), and 509 with no reported pulmonary complications.</p> <p>Conclusion</p> <p>Our current case and literature review indicate that pulmonary morbidity is one of the major contributors to poor quality of life and reduced long-term survival in DC. We suggest that lung transplantation be considered for patients with DC who develop pulmonary fibrosis with no concurrent evidence of multi-organ failure.</p

    The anticancer activity of lytic peptides is inhibited by heparan sulfate on the surface of the tumor cells

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    <p>Abstract</p> <p>Background</p> <p>Cationic antimicrobial peptides (CAPs) with antitumor activity constitute a promising group of novel anticancer agents. These peptides induce lysis of cancer cells through interactions with the plasma membrane. It is not known which cancer cell membrane components influence their susceptibility to CAPs. We have previously shown that CAPs interact with the two glycosaminoglycans (GAGs), heparan sulfate (HS) and chondroitin sulfate (CS), which are present on the surface of most cells. The purpose of this study was to investigate the role of the two GAGs in the cytotoxic activity of CAPs.</p> <p>Methods</p> <p>Various cell lines, expressing different levels of cell surface GAGs, were exposed to bovine lactoferricin (LfcinB) and the designer peptide, KW5. The cytotoxic effect of the peptides was investigated by use of the colorimetric MTT viability assay. The cytotoxic effect on wild type CHO cells, expressing normal amounts of GAGs on the cell surface, and the mutant pgsA-745, that has no expression of GAGs on the cell surface, was also investigated.</p> <p>Results</p> <p>We show that cells not expressing HS were more susceptible to CAPs than cells expressing HS at the cell surface. Further, exogenously added heparin inhibited the cytotoxic effect of the peptides. Chondroitin sulfate had no effect on the cytotoxic activity of KW5 and only minor effects on LfcinB cytotoxicity.</p> <p>Conclusion</p> <p>Our results show for the first time that negatively charged molecules at the surface of cancer cells inhibit the cytotoxic activity of CAPs. Our results indicate that HS at the surface of cancer cells sequesters CAPs away from the phospholipid bilayer and thereby impede their ability to induce cytolysis.</p
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