Browsing by Subject "coral"
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Item Bimodal Signatures of Germline Methylation are Linked with Gene Expression Plasticity in the Coral Acropora Millepora(2014-12) Dixon, Groves B.; Bay, Line K.; Matz, Mikhail V.; Dixon, Groves B.; Matz, Mikhail V.In invertebrates, genes belonging to dynamically regulated functional categories appear to be less methylated than "housekeeping" genes, suggesting that DNA methylation may modulate gene expression plasticity. To date, however, experimental evidence to support this hypothesis across different natural habitats has been lacking. Results: Gene expression profiles were generated from 30 pairs of genetically identical fragments of coral Acropora millepora reciprocally transplanted between distinct natural habitats for 3 months. Gene expression was analyzed in the context of normalized CpG content, a well-established signature of historical germline DNA methylation. Genes with weak methylation signatures were more likely to demonstrate differential expression based on both transplant environment and population of origin than genes with strong methylation signatures. Moreover, the magnitude of expression differences due to environment and population were greater for genes with weak methylation signatures. Conclusions: Our results support a connection between differential germline methylation and gene expression flexibility across environments and populations. Studies of phylogenetically basal invertebrates such as corals will further elucidate the fundamental functional aspects of gene body methylation in Metazoa.Item Coral-based climate reconstructions from a massive Porites coral from Sabine Bank (Vanuatu)(2009-08) Dunn, Elizabeth M., 1984-; Quinn, Terrence M.; Taylor, Frederick W.; Kerans, CharlesA monthly resolved, 133 year record of coral Sr/Ca variations has been developed from a massive Porites coral that was drilled in the shallow waters of a submerged carbonate platform (Sabine Bank, 15.9°S, 166.14°E) located ~50 km west of Espiritu Santo, Vanuatu. This truly open-ocean site, at which daily measurements of temperature and salinity are available for ~ 6 years, permits the reconstruction of local environmental variability using variations in coral skeletal geochemistry. Coral Sr/Ca-SST variations are well matched to variations in local SST, but bear little relation to changes in local SSS indicating little or no influence of salinity on coral Sr/Ca. The complete coral Sr/Ca-SST time series is characterized by abundant inter-annual variability, a strong trend towards warming (i.e., lower Sr/Ca values) from ~1980-2006. Interannual SSTA variations at Sabine Bank correspond reasonably well to SSTA variations from the central Pacific cool tongue (Niño 3.4 region), indicating that coral Sr/Ca variations record ENSO variability in the region.Item High Precision Thorium-230 Dating of Corals Using Thermal Ionization Mass Spectrometry: Applications to Paleoseismology.(Institute for Geophysics, 1987) Edwards, R. Lawrence; Taylor, Frederick W.; Chen, J.H.; Wasserburg, G.J.The recent development of mass spectrometric methods for determining 230Th abundances reduces the analytical error in 230Th ages of corals. Errors of ±3 yrs (2?) for a 17 yr old coral, ±5 yrs at 180 yrs, ±44 yrs at 8,294 yrs, and ±1.1 kyat 123.1 ky (1 ky = 1,000 yrs) were obtained using these techniques. Within the error of the measurements, 230Th ages agree with ages determined by counting of annual growth bands. These measurements indicate that the maximum amount of 230Th incorporated into a coral skeleton during growth is equivalent to the amount of 230Th generated by radioactive decay in <6 yrs. Using these techniques, we have dated two emerged corals from north Malekula Island and two from northwest Santo Island, Vanuatu. By analogy to partially emerged corals that were killed by coseismic uplift on Santo in 1973 (Ms = 7.5) and on Malekula in 1965 (Ms = 7.5), it appears that each pair of emerged corals was killed by an earlier coseismic uplift event. Pairs of emerged coral heads from each of the localities yield similar 230Th ages. This demonstrates that each pair of corals died at the same time and is consistent with the idea that they were killed by the same event (presumed to be coseismic emergence). The 230Th growth dates of the emerged corals (A.D. 1864±4 (2 ?) and A.D. 1865±4 for Santo; A.D. 1729±3 and A.D. 1718±5 for Malekula) in conjunction with the dates of historical earthquakes yield recurrence intervals of 108 yrs for northwest Santo Island and 236 yrs for north Malekula Island. If a slip-predictable model is used, average uplift rates over the past few centuries are similar to uplift rates averaged over the past 6,126 yrs. It may be possible to extend this approach back in time and to other localities because coral features that represent paleoseismic events are preserved in the geologic record and we have the ability to recognize these features in the field. However, the difficulties in recognizing and sampling corals that represent paleoseismic uplifts become increasingly greater with increasing age.Item Letter to H.B. Stenzel from Elvin M. Hurlbut on 1945-06-11(1945-06-11) Hurlbut, Elvin M.Item The Midway group of Texas ; including a chapter on the coral fauna by T. Wayland Vaughan and Willis Parkison Popenoe(University of Texas at Austin, 1933-01-01) Gardner, Julia Anna