sodium-perchlorate and potassium-perchlorate

The hydrogen bond structure of water was examined by comparing the temperature dependent OH-stretching bands of water and aqueous NaClO

Topics: Hydrogen Bonding; Perchlorates; Potassium Compounds; Sodium Compounds; Sulfates; Temperature; Water

The ability of different goitrogens (anti-thyroid agents) to induce precocious metamorphosis in larval sea lampreys (Petromyzon marinus) was assessed in four separate experiments. Two of these goitrogens (propylthiouracil [PTU] and methimazole [MMI]) are inhibitors of thyroid peroxidase-catalyzed iodination, and three (potassium perchlorate [KClO(4)], potassium thiocyanate [KSCN], and sodium perchlorate [NaClO(4)]) are anionic competitors of iodide uptake. Because, theoretically, all of these goitrogens prevent thyroid hormone (TH) synthesis, we also measured their influence on serum concentrations of thyroxine and triiodothyronine. All goitrogens except PTU significantly lowered serum TH concentrations and induced metamorphosis in some larvae. The incidence of metamorphosis appeared to be correlated with these lowered TH concentrations in that KClO(4), NaClO(4), and MMI treatments resulted in the lowest serum TH concentrations and the highest incidence of metamorphosis in sea lampreys. Moreover, fewer larvae metamorphosed in the KSCN and low-KClO(4) treatment groups and their serum TH concentrations tended to be greater than the values in the aforementioned groups. MMI treatment at the concentrations used (0.087 and 0.87 mM) was toxic to 55% of the exposed sea lampreys within 6 weeks. The potassium ion administered as KCl did not alter serum TH concentrations or induce metamorphosis. On the basis of the results of these experiments, we have made the following conclusions: (i) In general, most goitrogens other than PTU can induce metamorphosis in larval sea lampreys, and this induction is coincident with a decline in serum TH concentrations. (ii) The method by which a goitrogen prevents TH synthesis is not directly relevant to the induction of metamorphosis. (iii) PTU has variable effects on TH synthesis and metamorphosis among lamprey species. (iv) Unlike in protochordates, potassium ions do not induce metamorphosis in sea lampreys and are not a factor in the stimulation of this event.

Topics: Animals; Antithyroid Agents; Iodide Peroxidase; Iodides; Lampreys; Larva; Metamorphosis, Biological; Methimazole; Perchlorates; Potassium; Potassium Chloride; Potassium Compounds; Propylthiouracil; Sodium Compounds; Thiocyanates; Thyroid Hormones; Triiodothyronine

The telomeric sequence (T(2)G(4))(4) was platinated in aqueous solutions containing 50 mM LiClO(4), NaClO(4), or KClO(4). The identification of the guanines which reacted with [Pt(NH(3))(3)(H(2)O)](2+) revealed that the same type of folding exists in the presence of the three cations and that the latter determine the relative stabilities of the G-quadruplex structures in the order K(+) > Na(+) >> Li(+). The tri-ammine complex yielded ca. 40--90% of adducts, mono- and poly-platinated, bound to 4 guanines out of the 16 guanines in the sequence, in the decreasing amounts G9 > G15 >> G3 > G21. The formation of these adducts was interpreted with a G-quadruplex structure obtained by restrained molecular dynamics (rMD) simulations which confirms the schematic model proposed by Williamson et al. [(1989) Cell 59, 871--880]. The bifunctional complexes cis- and trans-[Pt(NH(3))(2)(H(2)O)(2)](2+) also first reacted with G9 and G15 and gave cross-linked adducts between two guanines, which did not exceed 5% each of the products formed. Both the cis and trans isomers formed a G3-G15 platinum chelate, and the second also formed bis-chelates at both ends of the G-quadruplex structure: G3-G15/G9-G21 and G3-G15/G9-G24. The rMD simulations showed that the cross-linking reactions by the trans complex can occur without disturbing the stacking of the three G-quartets.

Topics: Base Sequence; Cisplatin; Cross-Linking Reagents; DNA; G-Quadruplexes; Guanine; Lithium Compounds; Nucleic Acid Conformation; Nucleic Acid Denaturation; Oligonucleotides; Perchlorates; Potassium Compounds; Sodium Compounds; Telomere; Thermodynamics