Bull Trout (Salvelinus confluentus) can detect conspecific pheromones in a two choice Y-maze

Two stocks of Bull Trout (Salvelinus confluentus) were tested in a two choice Y-maze to determine if they could detect pheromones from the same natal population (population specific pheromones PSP) or from a different (conspecific) population of Bull Trout (CSP). Fish from the Pack River (PR), Idaho and the Metolius River (MR), Oregon were transferred to a fish hatchery where Y-maze studies were conducted. The Y-maze was constructed to supply well water at 12°C (blank) to both arms with the temperature and discharge of each arm matched to within 0.1°C and 0.01 l/s. One arm was randomly selected to be supplied with pheromones from fish held in stock tanks. Four types of tests were conducted with each stock: 1) blank supplied to both arms; 2) PSP + blank in one arm; 3) CSP + blank in one arm; 4) PSP + blank in one arm and CSP + blank in the other. Chi Square (χ²) Goodness of Fit tests with two degrees of freedom were used to compare the frequency at which fish entered each arm to the theoretical distribution that assumed they randomly selected an arm. Both stocks exhibited no preference when blank water only was present [PR: (χ²=4.79; p=0.091; n=28); MR: (χ²=4.67; p=.097; n=27)]. Both stocks preferred the PSP arm over the blank arm during PSP tests [PR: (χ²=14.00; p\u3c0.001; n=27); MR: (χ²=21.94; p\u3c0.001; n=28)]. Both stocks preferred the CSP arm over the blank arm during CSP tests [PR: (χ²=15.07; p\u3c0.001; n=26); MR: (χ²=16.72; p\u3c0.001; n=31)]. During the PSP vs. CSP tests, both PR and MR spent equivalent frequency in PSP and CSP arms therefore exhibited no preference [PR: (χ²=2.96; p=0.227; n=29); MR: (χ²=4.90; p=0.086; n=31)]. These results showed Bull Trout could detect pheromones from other Bull Trout but could not differentiate between PSPs and CSPs

Kinetic and Thermodynamic Approaches for the Efficient Formation of Mechanical Bonds

Among the growing collection of molecular systems under consideration for nanoscale device applications, mechanically interlocked compounds derived from electrochemically switchable bistable [2]rotaxanes and [2]catenanes show great promise. These systems demonstrate dynamic, relative movements between their components, such as shuttling and circumrotation, enabling them to serve as stimuli-responsive switches operated via reversible, electrochemical oxidation−reduction rather than through the addition of chemical reagents. Investigations into these systems have been intense for a number of years, yet limitations associated with their synthesis have hindered incorporation of their mechanical bonds into more complex architectures and functional materials. We have recently addressed this challenge by developing new template-directed synthetic protocols, operating under both kinetic and thermodynamic control, for the preparation of bistable rotaxanes and catenanes. These methodologies are compatible with the molecular recognition between the π-electron-accepting cyclobis(paraquat-p-phenylene) (CBPQT4+) host and complementary π-electron-donating guests. The procedures that operate under kinetic control rely on mild chemical transformations to attach bulky stoppering groups or perform macrocyclizations without disrupting the host−guest binding of the rotaxane or catenane precursors. Alternatively, the protocols that operate under thermodynamic control utilize a reversible ring-opening reaction of the CBPQT4+ ring, providing a pathway for two cyclic starting materials to thread one another to form more thermodynamically stable catenaned products. These complementary pathways generate bistable rotaxanes and catenanes in high yields, simplify mechanical bond formation in these systems, and eliminate the requirement that the mechanical bonds be introduced into the molecular structure in the final step of the synthesis. These new methods have already been put into practice to prepare previously unavailable rotaxane architectures and novel complex materials. Furthermore, the potential for utilizing mechanically interlocked architectures as device components capable of information storage, the delivery of therapeutic agents, or other desirable functions has increased significantly as a result of the development of these improved synthetic protocols

Efficient Templated Synthesis of Donor−Acceptor Rotaxanes Using Click Chemistry

The mild reaction conditions, remarkable functional group compatibility, and complete regioselectivity of the Cu-catalyzed Huisgen 1,3-dipolar cycloaddition (“click chemistry”) between organic azides and terminal alkynes have led to a threading-followed-by-stoppering approach to the synthesis of donor−acceptor rotaxanes incorporating cyclobis(paraquat-p-phenylene) (CBPQT^(4+)) as the π-accepting ring component. Rotaxane formation is initiated by reacting azide-functionalized pseudorotaxanes containing π-donating 1,5-dioxynaphthalene (DNP) recognition units with appropriate alkyne-functionalized stoppers. The high yields obtained in this efficient, kinetically controlled post-assembly covalent modification, as well as the excellent convergence of the synthetic protocol, are demonstrated by the preparation of [2]-, [3]-, and [4]rotaxanes containing multiple DNP/CBPQT^(4+) donor−acceptor recognition motifs

A Push-Button Molecular Switch

The preparation, characterization, and switching mechanism of a unique single-station mechanically switchable hetero[2]catenane are reported. The facile synthesis utilizing a “threading-followed-by-clipping” protocol features Cu^(2+)-catalyzed Eglinton coupling as a mild and efficient route to the tetrathiafulvalene-based catenane in high yield. The resulting mechanically interlocked molecule operates as a perfect molecular switch, most readily described as a “push-button” switch, whereby two discrete and fully occupied translational states are toggled electrochemically at incredibly high rates. This mechanical switching was probed using a wide variety of experimental techniques as well as quantum-mechanical investigations. The fundamental distinctions between this single-station [2]catenane and other more traditional bi- and multistation molecular switches are significant

Mechanically Stabilized Tetrathiafulvalene Radical Dimers

Two donor−acceptor [3]catenanes—composed of a tetracationic molecular square, cyclobis(paraquat-4,4′-biphenylene), as the π-electron deficient ring and either two tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) containing macrocycles or two TTF-butadiyne-containing macrocycles as the π-electron rich components—have been investigated in order to study their ability to form TTF radical dimers. It has been proven that the mechanically interlocked nature of the [3]catenanes facilitates the formation of the TTF radical dimers under redox control, allowing an investigation to be performed on these intermolecular interactions in a so-called “molecular flask” under ambient conditions in considerable detail. In addition, it has also been shown that the stability of the TTF radical-cation dimers can be tuned by varying the secondary binding motifs in the [3]catenanes. By replacing the DNP station with a butadiyne group, the distribution of the TTF radical-cation dimer can be changed from 60% to 100%. These findings have been established by several techniques including cyclic voltammetry, spectroelectrochemistry and UV−vis−NIR and EPR spectroscopies, as well as with X-ray diffraction analysis which has provided a range of solid-state crystal structures. The experimental data are also supported by high-level DFT calculations. The results contribute significantly to our fundamental understanding of the interactions within the TTF radical dimers

Supramolecular guests in solvent driven block copolymer assembly: from internally structured nanoparticles to micelles

Supramolecular interactions between different hydrogen-bonding guests and poly(2-vinylpyridine)-block-poly(styrene) can be exploited to prepare remarkably diverse self-assembled nanostructures in dispersion from a single block copolymer (BCP). The characteristics of the BCP can be efficiently controlled by tailoring the properties of a guest which preferentially binds to the P2VP block. For example, the incorporation of a hydrophobic guest creates a hydrophobic BCP complex that forms phase separated nanoparticles upon self-assembly. Conversely, the incorporation of a hydrophilic guest results in an amphiphilic BCP complex that forms spherical micelles in water. The ability to tune the self-assembly behavior and access dramatically different nanostructures from a single BCP substrate demonstrates the exceptional versatility of the self-assembly of BCPs driven by supramolecular interactions. This approach represents a new methodology that will enable the further design of complex, responsive self-assembled nanostructures

AVID: An integrative framework for discovering functional relationships among proteins

BACKGROUND: Determining the functions of uncharacterized proteins is one of the most pressing problems in the post-genomic era. Large scale protein-protein interaction assays, global mRNA expression analyses and systematic protein localization studies provide experimental information that can be used for this purpose. The data from such experiments contain many false positives and false negatives, but can be processed using computational methods to provide reliable information about protein-protein relationships and protein function. An outstanding and important goal is to predict detailed functional annotation for all uncharacterized proteins that is reliable enough to effectively guide experiments. RESULTS: We present AVID, a computational method that uses a multi-stage learning framework to integrate experimental results with sequence information, generating networks reflecting functional similarities among proteins. We illustrate use of the networks by making predictions of detailed Gene Ontology (GO) annotations in three categories: molecular function, biological process, and cellular component. Applied to the yeast Saccharomyces cerevisiae, AVID provides 37,451 pair-wise functional linkages between 4,191 proteins. These relationships are ~65–78% accurate, as assessed by cross-validation testing. Assignments of highly detailed functional descriptors to proteins, based on the networks, are estimated to be ~67% accurate for GO categories describing molecular function and cellular component and ~52% accurate for terms describing biological process. The predictions cover 1,490 proteins with no previous annotation in GO and also assign more detailed functions to many proteins annotated only with less descriptive terms. Predictions made by AVID are largely distinct from those made by other methods. Out of 37,451 predicted pair-wise relationships, the greatest number shared in common with another method is 3,413. CONCLUSION: AVID provides three networks reflecting functional associations among proteins. We use these networks to generate new, highly detailed functional predictions for roughly half of the yeast proteome that are reliable enough to drive targeted experimental investigations. The predictions suggest many specific, testable hypotheses. All of the data are available as downloadable files as well as through an interactive website at . Thus, AVID will be a valuable resource for experimental biologists

Mesostructured Block Copolymer Nanoparticles: Versatile Templates for Hybrid Inorganic/Organic Nanostructures

We present a versatile strategy to prepare a range of nanostructured poly(styrene)-block-poly(2-vinyl pyridine) copolymer particles with tunable interior morphology and controlled size by a simple solvent exchange procedure. A key feature of this strategy is the use of functional block copolymers incorporating reactive pyridyl moieties which allow the absorption of metal salts and other inorganic precursors to be directed. Upon reduction of the metal salts, well-defined hybrid metal nanoparticle arrays could be prepared, whereas the use of oxide precursors followed by calcination permits the synthesis of silica and titania particles. In both cases, ordered morphologies templated by the original block copolymer domains were obtained