Rational heteroatom engineering is applied to develop high-performance electron-transporting naphthalenediimide copolymers. Top-gate field-effect transistors fabricated from selenophene-containing polymers achieve an ultrahigh electron mobility of 8.5 cm V s and excellent air-stability. The results demonstrate that the incorporation of selenophene heterocycles into the polymers can improve the film-forming ability, intermolecular interaction, and carrier transport significantly.

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By screening Drosophila mutants that are potentially defective in synaptic transmission between photoreceptors and their target laminar neurons, L1/L2, (lack of electroretinogram on/off transients), we identified ort as a candidate gene encoding a histamine receptor subunit on L1/L2. We provide evidence that the ort gene corresponds to CG7411 (referred to as hclA), identified in the Drosophila genome data base, by P-element-mediated germ line rescue of the ort phenotype using cloned hclA cDNA and by showing that several ort mutants exhibit alterations in hclA regulatory or coding sequences and/or allele-dependent reductions in hclA transcript levels. Other workers have shown that hclA, when expressed in Xenopus oocytes, forms histamine-sensitive chloride channels. However, the connection between these chloride channels and photoreceptor synaptic transmission was not established. We show unequivocally that hclA-encoded channels are the channels required in photoreceptor synaptic transmission by 1) establishing the identity between hclA and ort and 2) showing that ort mutants are defective in photoreceptor synaptic transmission. Moreover, the present work shows that this function of the HCLA (ORT) protein is its native function in vivo.

Mitochondrial complex I is central to the pathological reactive oxygen species (ROS) production that underlies cardiac ischemia–reperfusion (IR) injury. ND6-P25L mice are homoplasmic for a disease-causing mtDNA point mutation encoding the P25L substitution in the ND6 subunit of complex I. The cryo-EM structure of ND6-P25L complex I revealed subtle structural changes that facilitate rapid conversion to the “deactive” state, usually formed only after prolonged inactivity. Despite its tendency to adopt the “deactive” state, the mutant complex is fully active for NADH oxidation, but cannot generate ROS by reverse electron transfer (RET). ND6-P25L mitochondria function normally, except for their lack of RET ROS production, and ND6-P25L mice are protected against cardiac IR injury in vivo. Thus, this single point mutation in complex I, which does not affect oxidative phosphorylation but renders the complex unable to catalyse RET, demonstrates the pathological role of ROS production by RET during IR injury.

Adenosine triphosphate (ATP), the cellular energy currency, is essential for life. The ability to provide a constant supply of ATP is therefore crucial for the construction of artificial cells in synthetic biology. Here, we describe the bottom-up assembly and characterization of a minimal respiratory system that uses NADH as a fuel to produce ATP from ADP and inorganic phosphate, and is thus capable of sustaining both upstream metabolic processes that rely on NAD + , and downstream energydemanding processes that are powered by ATP hydrolysis. A detergent-mediated approach was used to co-reconstitute respiratory mitochondrial complex I and an F-type ATP synthase into nanosized liposomes. Addition of the alternative oxidase to the resulting proteoliposomes produced a minimal artificial "organelle" that reproduces the energy-converting catalytic reactions of the mitochondrial respiratory chain: NADH oxidation, ubiquinone cycling, oxygen reduction, proton pumping, and ATP synthesis. As a proof-of-principle, we demonstrate that our nanovesicles are capable of using an NAD + -linked substrate to drive cell-free protein expression. Our nanovesicles are both efficient and durable and may be applied to sustain artificial cells in future work.

A non-conjugated polymer acceptor PF1-TS4 was firstly synthesized by embedding a thioalkyl segment in the mainchain, which shows excellent photophysical properties on par with a fully conjugated polymer, with a low optical band gap of 1.58 eV and a high absorption coefficient > 10 5 cm À1 , a high LUMO level of À3.89 eV, and suitable crystallinity. Matched with the polymer donor PM6, the PF1-TS4-based all-PSC achieved a power conversion efficiency (PCE) of 8.63 %, which is % 45 % higher than that of a device based on the small molecule acceptor counterpart IDIC16. Moreover, the PF1-TS4-based all-PSC has good thermal stability with % 70 % of its initial PCE retained after being stored at 85 8C for 180 h, while the IDIC16-based device only retained % 50 % of its initial PCE when stored at 85 8C for only 18 h. Our work provides a new strategy to develop efficient polymer acceptor materials by linkage of conjugated units with non-conjugated thioalkyl segments.

During cytokinesis, most bacteria assemble a ring-like structure that is composed of the tubulin homolog FtsZ. The mechanisms regulating assembly and organization of FtsZ molecules into rings are not fully understood. Here, we express bacterial FtsZ in the fission yeast Schizosaccharomyces pombe and find that FtsZ filaments assemble into cytoplasmic rings. Investigation of the Escherichia coli FtsZ revealed that ring assembly occurred by a process of closure and/or spooling of linear bundles. We conclude that FtsZ rings can assemble in the absence of all other bacterial cytokinetic proteins and that the process might involve hydrolysis of FtsZ-bound GTP and lateral associations between FtsZ filaments.Supplemental material is available at http://www.genesdev.org. February 7, 2008; revised version accepted May 5, 2008. Cytokinesis in a majority of bacteria requires the function of the prokaryotic ancestor of tubulin, FtsZ (Lutkenhaus et al. 1980;Lowe and Amos 1998;Errington et al. 2003;Erickson 2007). FtsZ is the first protein to localize to the mid-cell site, where it plays a critical role in the recruitment of a dozen other proteins that are required for assembly of the division septum (Bi and Lutkenhaus 1991;Weiss 2004;Goehring and Beckwith 2005). FtsZ has been shown to be a GTPase capable of forming a variety of polymeric structures in vitro (de Boer et al. 1992;RayChaudhuri and Park 1992;Bramhill and Thompson 1994;Mukherjee and Lutkenhaus 1994;Erickson et al. 1996;Romberg and Levin 2003). In vivo it localizes to the division site to form a ring-like structure (termed the FtsZ-ring or the Z-ring) and remains at the leading edge of the septum throughout cytokinesis (Bi and Lutkenhaus 1991;Wang and Lutkenhaus 1993;Ma et al. 1996). We previously established the fission yeast as a cellular model for studying prokaryotic cytoskeletal proteins (Srinivasan et al. 2007). In this study, we express wildtype and mutant versions of E. coli FtsZ (EcFtsZ) in fission yeast. Surprisingly, we find that EcFtsZ assembles into ring-like structures in fission yeast in a mechanism involving closure and/or spooling of linear cables. Received Results and DiscussionPrevious studies have shown that EcFtsZ expressed in fission yeast assembles into spot-like structures and cables (Fig. 1A, panels i,ii; Srinivasan et al. 2007), which are largely abolished upon coexpression of SulA (Srinivasan et al. 2007), a known inhibitor of FtsZ polymerization in bacterial cells. These spot-like structures were very similar in appearance to the spots observed when FtsZ was expressed in mammalian cells lines by Cabral and coworkers (Yu et al. 1999). In addition, as in fission yeast cells, FtsZ expressed in mammalian cells was also observed to form a filamentous network interconnecting the dots (Yu et al. 1999). Fluorescence recovery after photobleaching experiments (FRAP) revealed that FtsZ turns over with a recovery half-time t 1/2 of ∼11 sec (n = 22), which is very close to the FtsZ turnover rates determined in bacterial cells (Anderson et al. 200...

Benefiting from the high electrochemical surface area brought by 2D nanosheet structure, MoS2 has received great research attention for hydrogen evolution reaction (HER). Recently it has demonstrated that by constructing...