Iodine ages of pore water at Hydrate Ridge, Cascadian continental margin

Hydrate Ridge off the coast of Oregon, USA, is a prime example for gas hydrate occurrences in active margin settings. It is part of the Cascadia Margin and was the focus of Ocean Drilling Program (ODP) Leg 204, which successfully recovered fluids from nine sites from the southern part of the ridge. Iodide concentrations in pore fluids associated with gas hydrates are strongly enhanced, by factors up to 5000 compared to seawater, which allows the use of this biophilic element as tracer for organic source regions. We applied the cosmogenic isotope 129I (T1/2=15.7 Ma) system to determine the age of the organic source formation responsible for the iodide enrichment. In all sites at ODP Leg 204, 129I/I ratios were found to decrease with depth to values around 250x10**-15, corresponding to minimum ages of 40 Ma, but in several sites, maxima in the 129I/I ratios point to the local addition of young iodide. The results indicate that a large amount of iodide was derived from deep accreted sediments of Eocene age, and that additional source regions provide iodide of Late Miocene age. The presence of old iodide in the pore waters suggests that fluid pathways are open to allow transport over large distances into the gas hydrate fields. The strong correlation between iodide and methane in hydrate fields coupled with the similarity in transport parameters in aqueous solutions suggests that a large fraction of methane in gas hydrates also has old sources and is transported into the present locations from source regions of Eocene age.

Seven-membered Rings Through Metal-free Rearrangement Mediated By Hypervalent Iodine.

A versatile and metal-free approach for the synthesis of carbocycles and of heterocycles bearing seven- and eight-membered rings is described. The strategy is based on ring expansion of 1-vinylcycloalkanols (or the corresponding silyl or methyl ether) mediated by the hypervalent iodine reagent HTIB (PhI(OH)OTs). Reaction conditions can be easily adjusted to give ring expansion products bearing different functional groups. A route to medium-ring lactones was also developed.

Congada, corpo e cultura na 125ª festa em louvor a Nossa Senhora do Rosario

Universidade Estadual de Campinas. Faculdade de Educação Fisica

Metal-free synthesis of indanes by iodine(III)-mediated ring contraction of 1, 2-dihydronaphthalenes

A metal-free protocol was developed to synthesize indanes by ring contraction of 1, 2-dihydronaphthalenes promoted by PhI(OH)OTs (HTIB or Koser's reagent). This oxidative rearrangement can be performed in several solvents (MeOH, CH3CN, 2 , 2, 2-trifluoroethanol (TFE), 1 , 1, 1, 3, 3, 3-hexafluoroisopropanol (HFIP), and a 1:4 mixture of TFE:CH2Cl2) under mild conditions. The ring contraction diastereoselectively gives functionalized trans-1, 3-disubstituted indanes, which are difficult to obtain in synthetic organic chemistry

High Iodine Concentration Attenuates RET/PTC3 Oncogene Activation in Thyroid Follicular Cells

Background: Papillary thyroid carcinoma (PTC) is frequently associated with a RET gene rearrangement that generates a RET/PTC oncogene. RET/PTC is a fusion of the tyrosine kinase domain of RET to the 50 portion of a different gene. This fusion results in a constitutively active MAPK pathway, which plays a key role in PTC development. The RET/PTC3 fusion is primarily associated with radiation-related PTC. Epidemiological studies show a lower incidence of PTC in radiation-exposed regions that are associated with an iodine-rich diet. Since the influence of excess iodine on the development of thyroid cancer is still unclear, the aim of this study is to evaluate the effect of high iodine concentrations on RET/PTC3-activated thyroid cells. Methods: PTC3-5 cells, a rat thyroid cell lineage harboring doxycycline-inducible RET/PTC3, were treated with 10(-3) M NaI. Cell growth was analyzed by cell counting and the MTT assay. The expression and phosphorylation state of MAPK pathway-related (Braf, Erk, pErk, and pRet) and thyroid-specific (natrium-iodide symporter [Nis] and thyroid-stimulating hormone receptor [Tshr]) proteins were analyzed by Western blotting. Thyroid-specific gene expression was further analyzed by quantitative reverse transcription (RT)-polymerase chain reaction. Results: A significant inhibition of proliferation was observed, along with no significant variation in cell death rate, in the iodine-treated cells. Further, iodine treatment attenuated the loss of Nis and Tshr gene and protein expression induced by RET/PTC3 oncogene induction. Finally, iodine treatment reduced Ret and Erk phosphorylation, without altering Braf and Erk expression. Conclusion: Our results indicate an antioncogenic role for excess iodine during thyroid oncogenic activation. These findings contribute to a better understanding of the effect of iodine on thyroid follicular cells, particularly how it may play a protective role during RET/PTC3 oncogene activation.

Implication of the visual system in the regulation of activity cycles in the absence of solar light: 2-[I-125]iodomelatonin binding sites and melatonin receptor gene expression in the brains of demersal deep-sea gadiform fish

Relative eye size, gross brain morphology and central localization of 2-[I-125]iodomelatonin binding sites and melatonin receptor gene expression were compared in six gadiform fish living at different depths in the north-east Atlantic Ocean: Phycis blennoides (capture depth range 265-1260 m), Nezumia aequalis (445-1512 m), Coryphaenoides rupestris (706-1932 m), Trachyrincus murrayi (1010-1884 m), Coryphaenoides guentheri (1030 m) and Coryphaenoides (Nematonurus) armatus (2172-4787 m). Amongst these, the eye size range was 0.15-0.35 of head length with a value of 0.19 for C.(N.) armatus, the deepest species. Brain morphology reflected behavioural differences with well-developed olfactory regions in P.blennoides, T.murrayi and C. (N.) armatus and evidence of olfactory deficit in N. aequalis, C. rupestris and C. guentheri. All species had a clearly defined optic tectum with 2-[I-125] iodomelatonin binding and melatonin receptor gene expression localized to specific brain regions in a similar pattern to that found in shallow-water fish. Melatonin receptors were found throughout the visual structures of the brains of all species. Despite living beyond the depth of penetration of solar light these fish have retained central features associated with the coupling of cycles of growth, behaviour and reproduction to the diel light-dark cycle. How this functions in the deep sea remains enigmatic.