966 resultados para Gems, Ancient
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Gonadotropin-releasing hormone (GnRH) is known and named for its essential role in vertebrate reproduction. Release of this decapeptide from neurons in the hypothalamus controls pituitary gonadotropin levels which, in turn, regulate gonadal state. The importance of GnRH is underscored by its widespread expression and conservation across vertebrate taxa: five amino acids are invariant in all nine known forms, whereas two others show only conservative changes. In most eutherian mammals, only one form, expressed in the hypothalamus, is thought to exist, although in a recent report, antibody staining in developing primates suggests an additional form. In contrast, multiple GnRH forms and expression loci have been reported in many non-mammalian vertebrates. However, evidence based on immunological discrimination does not always agree with analysis of gene expression, since GnRH forms encoded by different genes may not be reliably distinguished by antibodies. Here we report the expression of three distinct GnRH genes in a teleost fish brain, including the sequence encoding a novel GnRH preprohormone. Using in situ hybridization, we show that this form is found only in neurons that project to the pituitary and exhibit changes in soma size depending on social and reproductive state. The other two GnRH genes are expressed in other, distinct cell populations. All three genes share the motif of encoding a polypeptide consisting of GnRH and a GnRH-associated peptide. Whereas the GnRH moiety is highly conserved, the GnRH-associated peptides are not, reflecting differential selective pressure on different parts of the gene. GnRH forms expressed in nonhypothalamic regions may serve to coordinate reproductive activities of the animal.
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We report characterization of a human T-cell lymphotropic virus type II (HTLV-II) isolated from an interleukin 2-dependent CD8 T-cell line derived from peripheral blood mononuclear cells of a healthy, HTLV-II-seropositive female Bakola Pygmy, aged 59, living in a remote equatorial forest area in south Cameroon. This HTLLV-II isolate, designated PYGCAM-1, reacted in an indirect immunofluorescence assay with HTLV-II and HTLV-I polyclonal antibodies and with an HTLV-I/II gp46 monoclonal antibody but not with HTLV-I gag p19 or p24 monoclonal antibodies. The cell line produced HTLV-I/II p24 core antigen and retroviral particles. The entire env gene (1462 bp) and most of the long terminal repeat (715 bp) of the PYGCAM-1 provirus were amplified by the polymerase chain reaction using HTLV-II-specific primers. Comparison with the long terminal repeat and envelope sequences of prototype HTLV-II strains indicated that PYGCAM-1 belongs to the subtype B group, as it has only 0.5-2% nucleotide divergence from HTLV-II B strains. The finding of antibodies to HTLV-II in sera taken from the father of the woman in 1984 and from three unrelated members of the same population strongly suggests that PYGCAM-1 is a genuine HTLV-II that has been present in this isolated population for a long time. The low genetic divergence of this African isolate from American isolates raises questions about the genetic variability over time and the origin and dissemination of HTLV-II, hitherto considered to be predominantly a New World virus.
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Universal trees based on sequences of single gene homologs cannot be rooted. Iwabe et al. [Iwabe, N., Kuma, K.-I., Hasegawa, M., Osawa, S. & Miyata, T. (1989) Proc. Natl. Acad. Sci. USA 86, 9355-9359] circumvented this problem by using ancient gene duplications that predated the last common ancestor of all living things. Their separate, reciprocally rooted gene trees for elongation factors and ATPase subunits showed Bacteria (eubacteria) as branching first from the universal tree with Archaea (archaebacteria) and Eucarya (eukaryotes) as sister groups. Given its topical importance to evolutionary biology and concerns about the appropriateness of the ATPase data set, an evaluation of the universal tree root using other ancient gene duplications is essential. In this study, we derive a rooting for the universal tree using aminoacyl-tRNA synthetase genes, an extensive multigene family whose divergence likely preceded that of prokaryotes and eukaryotes. An approximately 1600-bp conserved region was sequenced from the isoleucyl-tRNA synthetases of several species representing deep evolutionary branches of eukaryotes (Nosema locustae), Bacteria (Aquifex pyrophilus and Thermotoga maritima) and Archaea (Pyrococcus furiosus and Sulfolobus acidocaldarius). In addition, a new valyl-tRNA synthetase was characterized from the protist Trichomonas vaginalis. Different phylogenetic methods were used to generate trees of isoleucyl-tRNA synthetases rooted by valyl- and leucyl-tRNA synthetases. All isoleucyl-tRNA synthetase trees showed Archaea and Eucarya as sister groups, providing strong confirmation for the universal tree rooting reported by Iwabe et al. As well, there was strong support for the monophyly (sensu Hennig) of Archaea. The valyl-tRNA synthetase gene from Tr. vaginalis clustered with other eukaryotic ValRS genes, which may have been transferred from the mitochondrial genome to the nuclear genome, suggesting that this amitochondrial trichomonad once harbored an endosymbiotic bacterium.
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This dissertation examines ancient historiographic citation methodologies in light of Mikhail Bakhtin’s dichotomy between polyphony and monologization. In particular, this dissertation argues that Eusebius of Caesarea’s Historia ecclesiastica (HE) abandons the monologic citation methodology typical of previous Greek and Hellenistic historiography and introduces a polyphonic citation methodology that influences subsequent late-ancient Christian historiography to varying degrees. Whereas Pre-Eusebian Greek and Hellenistic historiographers typically use citations to support the single authorial consciousness of the historiographer, Eusebius uses citations to counterbalance his own shortcomings as a witness to past events. Eusebius allows his citations to retain their own voice, even when they conflict with his. The result is a narrative that transcends the point of view of any single individual and makes multiple witnesses, including the narrator, available to the reader. Post-Eusebian late-ancient Christian historiographers exhibit the influence of Eusebius’ innovation, but they are not as intentional as Eusebius in their use of citation methodologies. Many subsequent Christian historiographers use both monologic and polyphonic citation methodologies. Their tendency to follow Eusebius’ practice of citing numerous lengthy citations sometimes emphasizes points of view that oppose the author’s point of view. When an opposing viewpoint surfaces in enough citations, a polyphonic citation methodology emerges. The reader holds the two different narrative strands in tension as the author continues to give voice to opposing viewpoints. After illustrating the citation methodologies with passages from numerous Greek, Hellenistic, and late ancient Christian historiographers, this dissertation concludes with a short computational analysis that uses natural language processing to reveal some broad trends that highlight the previous findings and suggest a possibility for future research.
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This paper shows the results of an experimental analysis on the bell tower of “Chiesa della Maddalena” (Mola di Bari, Italy), to better understand the structural behavior of slender masonry structures. The research aims to calibrate a numerical model by means of the Operational Modal Analysis (OMA) method. In this way realistic conclusions about the dynamic behavior of the structure are obtained. The choice of using an OMA derives from the necessity to know the modal parameters of a structure with a non-destructive testing, especially in case of cultural-historical value structures. Therefore by means of an easy and accurate process, it is possible to acquire in-situ environmental vibrations. The data collected are very important to estimate the mode shapes, the natural frequencies and the damping ratios of the structure. To analyze the data obtained from the monitoring, the Peak Picking method has been applied to the Fast Fourier Transforms (FFT) of the signals in order to identify the values of the effective natural frequencies and damping factors of the structure. The main frequencies and the damping ratios have been determined from measurements at some relevant locations. The responses have been then extrapolated and extended to the entire tower through a 3-D Finite Element Model. In this way, knowing the modes of vibration, it has been possible to understand the overall dynamic behavior of the structure.
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by William H. Holmes.
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no.34(1940)
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The hand-sewn notebook contains a 24-page manuscript draft of the second Dudleian lecture, delivered by John Barnard on June 23, 1756. The copy includes a small number of edits and struck-out words adopted in the printed version published by J. Draper of Boston in 1756. The sermon begins with the Biblical text Mark 14:61, 62. The covers are no longer with the item.
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This layer is a georeferenced raster image of the historic paper map entitled: Pianta delle vestigia di Roma, secondo le osservazioni di Antonio de Romanis, ach. e socio dell' accad. di archeol. e di Antonio Nibby profess. di archeologia nell Vniv. di Roma e Socio della Stessa Accademia dallo stesso corretta ed amliata seconodo le vltime scoperte. data in lvce da Venanzio Monaldini Libraio L Anno MDCCCXXVI; Gio Acquaroni dis. e inc. It was published by presso Veanzio Monaldini ... con approvazione e privilegio Pontificio in 1826. Scale [ca. 1:8,769]. Covers area including portion of the modern city of Rome and Vatican City. The image inside the map neatline is georeferenced to the surface of the earth and fit to the "European Datum 1950 UTM Zone 33N" coordinate system. All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. This map shows features of Ancient Rome such as roads, drainage, selected buildings, city walls, gates, and fortifications, arches, and sepulchres. Relief is shown by hachures. Includes index, notes, and insets showing floor plans of selected historical sites.This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.
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by William H. Holmes.
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with a verbal translation and explanatory notes by William Jones.
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The study of vertical distribution of Mo, V, Co, Ni, and Cu in mass of Black Sea sediments showed that maximum concentrations occur in sapropelic muds of ancient Black Sea deposits. A special study of sapropels samples showed a sufficiently clear correlation of Cu, Ni, Mo, and V contents with organic carbon contents; Co contents do not show such a correlation, but show one with contents of pyrite sulfur. A study of fractions of bitumen, free humic and fulvic acids showed that some part of metal contents in the sediments is bound with organic matter. It is shown that increased concentrations of trace elements in sapropels result from removing of dissolved metals from seawater by organic detritus during deposition on the bottom, in vivo concentration of metals in plankton organisms is of secondary importance.
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Mode of access: Internet.
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English and German words with piano accompaniment.
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Mode of access: Internet.