13,161 research outputs found

    Trisomy 21 alters DNA methylation in parent-of-origin-dependent and independent manners

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    The supernumerary chromosome 21 in Down syndrome differentially affects the methylation statuses at CpG dinucleotide sites and creates genome-wide transcriptional dysregulation of parental alleles, ultimately causing diverse pathologies. At present, it is unknown whether those effects are dependent or independent of the parental origin of the nondis-joined chromosome 21. Linkage analysis is a standard method for the determination of the parental origin of this aneuploidy, although it is inadequate in cases with deficiency of samples from the progenitors. Here, we assessed the reliability of the epigenetic 5(m)CpG imprints resulting in the maternally (oocyte)-derived allele methylation at a differentially methylated region (DMR) of the candidate imprinted WRB gene for asserting the parental origin of chromosome 21. We developed a methylation-sensitive restriction enzyme-specific PCR assay, based on the WRB DMR, across single nucleotide polymorphisms (SNPs) to examine the methylation statuses in the parental alleles. In genomic DNA from blood cells of either disomic or trisomic subjects, the maternal alleles were consistently methylated, while the paternal alleles were unmethylated. However, the supernumerary chromosome 21 did alter the methylation patterns at the RUNX1 (chromosome 21) and TMEM131 (chromosome 2) CpG sites in a parent-of-origin-independent manner. To evaluate the 5(m)CpG imprints, we conducted a computational comparative epigenomic analysis of transcriptome RNA sequencing (RNA-Seq) and histone modification expression patterns. We found allele fractions consistent with the transcriptional biallelic expression of WRB and ten neighboring genes, despite the similarities in the confluence of both a 17-histone modification activation backbone module and a 5-histone modification repressive module between the WRB DMR and the DMRs of six imprinted genes. We concluded that the maternally inherited 5(m)CpG imprints at the WRB DMR are uncoupled from the parental allele expression of WRB and ten neighboring genes in several tissues and that trisomy 21 alters DNA methylation in parent-of-origin-dependent and -independent manners

    The Proto-Lolo-Burmese and old Burmese sources of written Burmese -AC*

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    It is a notable fact that some Written Burmese (WrB) morphemes in -ac are rather consistently spelt with -at when the initials are, or are interpretable as, with medial -y-. Thus WrB hrac ‘eight’ is written in some early Pagan inscriptions as hyat or het. Similarly, we find Old Burmese (OB) ñhat for WrB hñac ‘to squeeze’, OB cat for WrB cac ‘to examine, investigate’, OB khyat for WrB khyac ‘to love’ and OB mryat for WrB mrac ‘root’. On the other hand, the majority of the WrB morphemes in -ac are more consistently spelt with -ac or -ec. To give only a few examples, OB phlac, phlec for WrB phrac ‘to be become’, OB tac, tec or even tic for WrB tac or ta- (in composition with classifiers and in some other phrases) ‘one’, OB nhac or nhec for WrB hnac or hna- (in composition with classifiers) ‘two’, OB (Ɂa-)nhac for WrB (Ɂa-) hnac ‘year’, OB nhac for WrB hnac ‘heart’, OB Ɂac- or Ɂec- for WrB Ɂac- (‘older sibling’) in WrB Ɂac-kúi ‘elder brother’ and Ɂac-ma ‘elder sister’. Side by side, with OB hyat or het and OB khyat, however, we encounter variant spellings such as OB rhec and OB khyac. Likewise, phlet and Ɂat- are variant forms of OB phlac ~ phlec and OB Ɂac- ~ Ɂec-. In spite of this, it is not inconceivable that WrB -ac would be the result of merger of two distinct OB finals

    THE WORLD REFERENCE BASE FOR SOIL RESOURCES (WRB) WITH THE EXAMPLES OF ITS USE IN CROATIA

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    Svjetska referentna osnovica za tlo (World Reference Base for Soil Resources, WRB) je klasifikacijski sustav tla kojeg je prihvatilo Međunarodno pedološko društvo, a čija je konačna verzija završena 2006. Cilj izrade navedene klasifikacije bio je da se, kroz korelaciju nacionalnih s WRB klasifikacijom, omogući sporazumijevanje znanstvenika iz područja sistematike tla u Svijetu. Potreba za informacijama o korelaciji nacionalnih klasifikacija u odnosu na WRB, svakim danom je sve izraženija. Zbog toga se nedavno i u Hrvatskoj započelo sa sustavnim terenskim i laboratorijskim istraživanjima tala sukladno novim kriterijima i normativima prema WRB klasifikaciji. S obzirom na veliku važnost spomenute klasifikacije za širi krug znanstvenika, kojima je tloznanstvo područje od posebnog interesa, u prvom dijelu rada prikazuju se osnovne informacije o WRB-u te načela, ključ i pravila, kojih se treba pridržavati pri razvrstavanju tala. U drugom dijelu rada, daju se primjeri razvrstavanja tri karakteristična tipa tla prema važećoj klasifikaciji tala u Hrvatskoj te njihova korelacija prema WRB klasifikaciji. Na kraju se ukazuje na moguće probleme prilikom uporabe WRB klasifikacije, odnosno na uočene nedostatke pri razvrstavanju tala, te se daju prijedlozi za njezino poboljšanje.The World Reference Base for Soil Resources (WRB) is a soil classification system accepted by the International Union of Soil Sciences (IUSS). Its final version was published in 2006. The main purpose of constructing this system was to correlate national soil classifications with the WRB, in order to make communication between scientists in the field of soil classification in the World possible. The need for informations concerning correlations of national soil classifications with the WRB is pronounced more and more every day. Because of that, systematic field and laboratory soil research, in accordance to the new criteria and regulations given by the WRB, has recently begun in Croatia. Because of the WRB´s great importance for a wide array of scientists with a special interest in soil science, basic informations about the WRB, as well as the principles, key and rules, which have to be followed when classifying soils, are presented in the first part of this article. In its second part, the examples of classification of three characteristic soil types according to the Croatian soil classification and their correlation with the WRB are shown. Some possible problems which may occur while using the WRB classification system and some flaws detected in the classification process, as well as some suggestions for improvement of the WRB, are given in the end

    Evolution of the Burmese vowel system

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    Tibeto-Burman historical linguistics has relied heavily on the spelling of Burmese and Tibetan words as found in standard modern dictionaries, at the expense of the earliest attested records. This examination of the development of the Burmese vowel system, in the light of early Burmese philological data and comparisons to Old Chinese and Old Tibetan, facilitates a refined understanding of Burmese historical phonology and the reconstruction of Tibeto-Burman

    World reference base for soil resources 2014 International soil classification system for naming soils and creating legends for soil maps

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    The first edition of the World Reference Base for Soil Resources (WRB) was released at the 16th World Congress of Soil Science at Montpellier in 1998. At the same event, it was also endorsed and adopted as the system for soil correlation and international communication of the International Union of Soil Sciences (IUSS). The second edition of the WRB was released at the 18th World Congress at Philadelphia in 2006. After an additional eight years of intensive worldwide testing and data collection, the third edition of the WRB is presented. This publication builds on and reflects the valuable work of the authors of the earlier drafts and editions of the WRB, as well as the experiences and contributions of many soil scientists who participated in the work of the IUSS Working Group on the WRB. The WRB is a soil classification system for naming soils and creating soil map legends. It is hoped that this publication will contribute to the understanding of soil science in the general public and in the scientific community.JRC.H.5-Land Resources Managemen

    Challenges of Soil Taxonomy and WRB in classifying soils: some examples from Iranian soils

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    The two most widely used soil classification are Soil Taxonomy (ST) and World Reference Base for Soil Resources (WRB). The purpose of this paper is to clarify the differences and the similarities between ST and WRB in their current state, with some examples for representative soils in arid and semi-arid regions of Iran. Four representative pedons were classified and soil units from WRB were compared to those obtained by using ST at the family level. WRB could show the status of polluted soils by heavy metals through “toxic” qualifier and its subqualifiers. On the other hand, ST could indicate the status of shallow soils in our studied soils but it was not able to show gleyic conditions and the existence of salic horizon because of the differences of salic horizon criteria with WRB. Special effort should be done to quantify various anthropogenic activities in upcoming editions of both classification systems.

    Gamma-Ray Bursts from tidally spun-up Wolf-Rayet stars?

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    The collapsar model requires rapidly rotating Wolf-Rayet stars as progenitors of long gamma-ray bursts. However, Galactic Wolf-Rayet stars rapidly lose angular momentum due to their intense stellar winds. We investigate whether the tidal interaction of a Wolf-Rayet star with a compact object in a binary system can spin up the Wolf-Rayet star enough to produce a collapsar. We compute the evolution of close Wolf-Rayet binaries, including tidal angular momentum exchange, differential rotation of the Wolf-Rayet star, internal magnetic fields, stellar wind mass loss, and mass transfer. The Wolf-Rayet companion is approximated as a point mass. We then employ a population synthesis code to infer the occurrence rates of the various relevant binary evolution channels. We find that the simple scenario -- i.e., the Wolf-Rayet star being tidally spun up and producing a collapsar -- does not occur at solar metallicity and may only occur with low probability at low metallicity. It is limited by the widening of the binary orbit induced by the strong Wolf-Rayet wind or by the radius evolution of the Wolf-Rayet star that most often leads to a binary merger. The tidal effects enhance the merger rate of Wolf-Rayet stars with black holes such that it becomes comparable to the occurrence rate of long gamma-ray bursts.Comment: 9 pages, 11 figures, accepted for publication in A&

    The World Reference Base for Soil Resources (WRB) as an Instrument for the National and International Communication

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    Whoever studies the WRB in greater detail will know that this system is not intended to replace the individual national soil classification systems, but, as specified in the preface to the WRB, is to be considered as a platform, or “umbrella”, serving to promote international understanding in this special field. It should be added that this system is expected to be finalized during the 18th World Congress of the IUSS to be held in Philadelphia in July 2006. Still, there would be merit even now in giving some thought to this WRB in its 1998 version. In Austria, a new soil classification system has been used since the year 2000 and has yielded good results. However, national soil type classifications need to be supplemented by classifications according to the WRB in order to be accepted by reviewed journals. The difficulties involved are discussed in this report and illustrated by several practical examples. In addition, this report presents several examples of soil classification according to the WRB compared with the Austrian and Croatian classification systems: Pararendzina, Leptosol, Mull-Rendzina, Deponieboden, and Typischer Pseudogley. Using conclusions, this report discusses the favourable effect the WRB has on international understanding in the field of pedology notwithstanding its virtual inability to consider the national peculiarities
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