The success of Mycobacterium tuberculosis (Mtb) as a pathogen depends on the redundant and complex mechanisms it has evolved for resisting nitrosative and oxidative stresses inflicted by host immunity. Improving our understanding of these defense pathways can reveal vulnerable points in Mtb pathogenesis. In this study, we combined genetic, structural, computational, biochemical, and biophysical approaches to identify a novel enzyme class represented by Rv2466c. We show that Rv2466c is a mycothiol-dependent nitroreductase of Mtb and can reduce the nitro group of a novel mycobactericidal compound using mycothiol as a cofactor. In addition to its function as a nitroreductase, Rv2466c confers partial protection to menadione stress.

This paper describes the first reversible, heat-set organogel based on the supramolecular interactions of beta-cyclodextrin (beta-CD). The gel was prepared by interaction of diphenylamine (DPA) with beta-CD and lithium chloride in N,N-dimethylformamide (DMF). In this gel system, DPA could be gelated in DMF as the temperature increased and then dissolved again as the temperature decreased. In the microscopic structure of gel, beta-CDs play a key role in the formation of nanorods and microfibers. Some important features of the gel were observed. (1) The system is a multicomponent solution, in which each of the four components is required for the organogelation property. (2) The system is a reversible, thermo-responsive organogel composed of small organic molecules. When the temperature is lower than T(gel), the gel transforms back into a solution. The reversible thermo-transition was confirmed by differential scanning calorimetry (DSC). The gel system is responsive to the concentration of LiCl. No gel was formed without LiCl. The stimuli responses of the system with other salts such as KCl and NaCl were weaker than with LiCl. (4) The system is responsive to the addition of guest molecules. The structures and sizes of the guest molecules could influence the gel formation. Generally, T(gel) decreased by adding guest molecules in the gel system, but some guest molecules, whose structures are exactly fitted to the cavity of CDs, could prevent gel formation. This work may provide new avenues in delivery of functional molecules as well as design of intelligent materials and biomaterials.

The most prevalent primary brain tumors are gliomas, which start in the glial cells. Although there have been significant technological advances in surgery and radio-chemotherapy, the prognosis and survival of patients with malignant gliomas remain poor. For routine diagnosis of glioma, computed tomography and magnetic resonance imaging primarily depend on anatomical changes and fail to detect the cellular changes that occur early in the development of malignant gliomas. Therefore, it is urgent to find effective molecular diagnostic tools to detect early stages of malignant gliomas. Currently, cell-based Systematic Evolution of Ligands by EXponential enrichment (cell-SELEX) technology is one effective tool to obtain DNA or RNA aptamers capable of differentiating the molecular signatures among different types of cell lines. Using cell-SELEX, we generated and characterized an aptamer, termed S6-1b, that can distinguish the molecular differences between glioma cell line SHG44 and human astrocytes. Under the conditions of 4 and 37 °C, respectively, the dissociation constants of aptamer−cell interaction were both measured in the low nanomolar range. The aptamer S6-1b also exhibited excellent selectivity, making it suitable for use in a complex biological environment. Furthermore, the aptamer can effectively target glioma cells for in vivo fluorescence imaging of tumors. The target type of aptamer S6-1b was identified as a cell membrane protein. Our work indicates that aptamer S6-1b has diagnostic and therapeutic potential to specifically deliver imaging or therapeutic agents to malignant gliomas.