Shao-Zhong Zhang

Encoding social signals in the mouse main olfactory bulb

Mammalian urine releases complex mixtures of volatile compounds that are used in reproduction, territoriality and conspecific recognition. To understand how such complex mixtures are represented in the main olfactory bulb, we analysed the electrophysiological responses of individual mitral cells to volatile compounds in mouse urine. In both males and females, urine volatile compounds evoke robust responses in a small subset of mitral cells. Fractionation of the volatile compounds using gas chromatography showed that out of the hundreds of compounds present, mitral cells are activated by single compounds. One cohort of mitral cells responded exclusively to male urine; these neurons were activated by (methylthio)methanethiol, a potent, previously unknown semiochemical present only in male urine. When added to urine, synthetic (methylthio)methanethiol significantly enhances urine attractiveness to female mice. We conclude that mitral cells represent natural odorant stimuli by acting as selective feature detectors, and that their activation is largely independent of the presence of other components in the olfactory stimulus.

Crucial role of copper in detection of metal-coordinating odorants

Odorant receptors (ORs) in olfactory sensory neurons (OSNs) mediate detection of volatile odorants. Divalent sulfur compounds, such as thiols and thioethers, are extremely potent odorants. We identify a mouse OR, MOR244-3, robustly responding to (methylthio)methanethiol (MeSCH2SH; MTMT) in heterologous cells. Found specifically in male mouse urine, strong-smelling MTMT [human threshold 100 parts per billion (ppb)] is a semiochemical that attracts female mice. Nonadjacent thiol and thioether groups in MTMT suggest involvement of a chelated metal complex in MOR244-3 activation. Metal ion involvement in thiol–OR interactions was previously proposed, but whether these ions change thiol-mediated OR activation remained unknown. We show that copper ion among all metal ions tested is required for robust activation of MOR244-3 toward ppb levels of MTMT, structurally related sulfur compounds, and other metal-coordinating odorants (e.g., strong-smelling trans-cyclooctene) among >125 compounds tested. Copper chelator (tetraethylenepentamine, TEPA) addition abolishes the response of MOR244-3 to MTMT. Histidine 105, located in the third transmembrane domain near the extracellular side, is proposed to serve as a copper-coordinating residue mediating interaction with the MTMT–copper complex. Electrophysiological recordings of the OSNs in the septal organ, abundantly expressing MOR244-3, revealed neurons responding to MTMT. Addition of copper ion and chelator TEPA respectively enhanced and reduced the response of some MTMT-responding neurons, demonstrating the physiological relevance of copper ion in olfaction. In a behavioral context, an olfactory discrimination assay showed that mice injected with TEPA failed to discriminate MTMT. This report establishes the role of metal ions in mammalian odor detection by ORs.

Liquid sulfur as a reagent: synthesis of polysulfanes with 20 or more sulfur atoms with characterization by UPLC-(Ag+)-coordination ion spray-MS

Diallyl disulfide reacts within minutes with liquid sulfur at 120°C giving a family of diallyl polysulfanes, All2S n (n=3–22), characterized by ultra-performance liquid chromatography-(Ag+)-coordination ion spray-mass spectrometry (UPLC-(Ag+)CIS-MS). Similarly, garlic oil (GO), bis-(2-methyl-2-propenyl), bis-(2-chloro-2-propenyl), bis-(3-methyl-2-butenyl), and bis-(2-cyclohexen-1-yl) disulfides all give families of polysulfanes with up to 22 sequential sulfur atoms. New members of families of silver chelators with up to 10 sulfur atoms were found in GO using UPLC-(Ag+)CIS-MS.

Photooxygenation of 1,5-Thiaselenocane

A direct comparison of photooxygenation at sulfur and selenium centers is reported, and the reactivity of 1,5-thiaselenocane is compared to that of 1,5-dithiacyclooctane.

Options for high index fluids for third generation 193i lithography

Successful fluids for use in 3rd generation 193 nm immersion lithography must have refractive indices of ≥ 1.80 at 193 nm, ≤ 0.15/cm absorbance at 193 nm, and be photochemically inert to 193 nm radiation. Various classes of organic compounds were prepared and evaluated for use as 3rd generation 193 nm immersion fluids. Functional groups that were evaluated included: sulfones, sulfoxides, sulfonic acids, ammonium sulfonate salts, alkanes, alkyl chlorides, alkynes, and nitriles. Several compounds were synthesized including three sulfone and three sulfonic acid compounds. Other commercially available compounds of interest underwent extensive purification prior to evaluation. Although this work did not lead to any specific solutions to the challenge of identifying 3rd generation 193 nm immersion fluids, it can be concluded that high density hydrocarbons based on cubane may have the best chance of meeting these goals.

α,β-Unsaturated α′-Halomethylsulfones: Prepackaged Ramberg–Bäcklund Reagents for Tandem Synthetic Processes

Abstract The synthesis and reactions of several α,β-unsaturated chloromethyl sulfones are presented, for example [(chloromethyl) sulfonyl]-1,3-propadiene, [(chloromethyl) sulfonyl]ethene, [(dichloromethyl)sulfonyl]ethene and (E,Z)-1,2-bis[(chloromethyl)sulfonyl]ethene. These compounds serve as “prepackaged” Ramberg–Bäcklund reagents, which, following an appropriate first step, such as Diels–Alder addition, react with a base, giving Ramberg–Bäcklund products.