Unexpected Accumulation of ncm\u3csup\u3e5\u3c/sup\u3eU and ncm\u3csup\u3e5\u3c/sup\u3es\u3csup\u3e2\u3c/sup\u3eU in a \u3cem\u3etrm9\u3c/em\u3e Mutant Suggests an Additional Step in the Synthesis of mcm\u3csup\u3e5\u3c/sup\u3eU and mcm\u3csup\u3e5\u3c/sup\u3es\u3csup\u3e2\u3c/sup\u3eU

Background Transfer RNAs are synthesized as a primary transcript that is processed to produce a mature tRNA. As part of the maturation process, a subset of the nucleosides are modified. Modifications in the anticodon region often modulate the decoding ability of the tRNA. At position 34, the majority of yeast cytosolic tRNA species that have a uridine are modified to 5-carbamoylmethyluridine (ncm5U), 5-carbamoylmethyl-2′-O-methyluridine (ncm5Um), 5-methoxycarbonylmethyl-uridine (mcm5U) or 5-methoxycarbonylmethyl-2-thiouridine (mcm5s2U). The formation of mcm5 and ncm5 side chains involves a complex pathway, where the last step in formation of mcm5 is a methyl esterification of cm5 dependent on the Trm9 and Trm112 proteins. Methodology and Principal Findings Both Trm9 and Trm112 are required for the last step in formation of mcm5 side chains at wobble uridines. By co-expressing a histidine-tagged Trm9p together with a native Trm112p in E. coli, these two proteins purified as a complex. The presence of Trm112p dramatically improves the methyltransferase activity of Trm9p in vitro. Single tRNA species that normally contain mcm5U or mcm5s2U nucleosides were isolated from trm9Δ or trm112Δ mutants and the presence of modified nucleosides was analyzed by HPLC. In both mutants, mcm5U and mcm5s2U nucleosides are absent in tRNAs and the major intermediates accumulating were ncm5U and ncm5s2U, not the expected cm5U and cm5s2U. Conclusions Trm9p and Trm112p function together at the final step in formation of mcm5U in tRNA by using the intermediate cm5U as a substrate. In tRNA isolated from trm9Δ and trm112Δ strains, ncm5U and ncm5s2U nucleosides accumulate, questioning the order of nucleoside intermediate formation of the mcm5 side chain. We propose two alternative explanations for this observation. One is that the intermediate cm5U is generated from ncm5U by a yet unknown mechanism and the other is that cm5U is formed before ncm5U and mcm5U

Electronic Tuning of Mixed Quinoidal‐Aromatic Conjugated Polyelectrolytes: Direct Ionic Substitution on Polymer Main‐Chains

The synthesis of conjugated polymers with ionic substituents directly bound to their main chain repeat units is a strategy for generating strongly electron-accepting conjugated polyelectrolytes, as demonstrated through the synthesis of a series of ionic azaquinodimethane (iAQM) compounds. The introduction of cationic substituents onto the quinoidal para-azaquinodimethane (AQM) core gives rise to a strongly electron-accepting building block, which can be employed in the synthesis of ionic small molecules and conjugated polyelectrolytes (CPEs). Electrochemical measurements alongside theoretical calculations indicate notably low-lying LUMO values for the iAQMs. The optical band gaps measured for these compounds are highly tunable based on structure, ranging from 2.30 eV in small molecules down to 1.22 eV in polymers. The iAQM small molecules and CPEs showcase the band gap reduction effects of combining the donor-acceptor strategy with the bond-length alternation reduction strategy. As a demonstration of their utility, the iAQM CPEs so generated were used as active agents in photothermal therapy

11β,17,21-Trihydr­oxy-6α-methyl-3,20-dioxopregna-1,4-dien-21-yl 3-carboxy­propionate

The mol­ecule of the title compound, C26H34O8, a prednisolone derivative, contains three six-membered rings (A, B and C) and one five-membered ring (D). Ring A is planar and rings B and C adopt chair conformations, while ring D adopts an envelope conformation with the C atom bonded to the methyl group at the flap. The crystal structure is stabilized by intermolecular O—H⋯O hydrogen bond

Control and Cooptation in Mexican Politics

The authors identify a structure of widely-shared,interrelated goals, including political stability, economic growth, public welfare, and economic nationalism in contemporary Mexico. They relate those goals to the contemporary structure of Mexican governments. They also describe patterns of oligarchy, cooptation, dissent, and repression, and relate those patterns to the goal structure

Rank Equilibration and Political Behavior

The authors develop theoretical ideas in Technical Report #7 and outline links to political behavior. Technical Report #9 is more abstract than TR #8. This paper develops a theoretical argument about social comparison processes involved in political behavior

On the Balance of a Set of Ranks

This theoretical paper addresses what was then called “status consistency” or “status crystallization.” Discrepant ranks on different characteristics such as income, occupational prestige, education, race, and religion were thought to be a source of strain and a motivation to bring the ranks into line. This formal exploration was presented in 1966

Achieving efficiency in capacity procurement

This paper studies a capacity procurement problem in which a buyer meets an uncertain demand using a combination of spot purchases and supply options that are offered by a number of competing suppliers. The specific setting we consider involves the suppliers each owning a block of capacity and the buyer restricted to reserving the entire block or none. For this setting, we are interested in understanding the buyer's optimal procurement strategy and the suppliers' competitive bidding behavior in the supply option market. To this end, we first examine the buyer's optimal decision given a set of supply options, and then study the suppliers' optimal bidding strategies in equilibrium. We find that it is optimal for suppliers to set execution price at cost and hence make a profit only through the reservation payment. We also prove that when all the blocks have the same size the buyer's optimal profit as a function of supplier set is submodular. This property allows us to characterize an equilibrium in which the supply chain optimum is achieved, each supplier makes a profit equal to their marginal contribution to the supply chain and the buyer takes the remaining profit. When the blocks have different sizes, we develop a recursive procedure to characterize a class of equilibria in which the supply chain efficiency is achieved