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Exploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self‐assembly systems and materials. Herein, for the first time, we demonstrate a unique visible‐light‐switchable telluro‐triazole/triazolium‐based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo‐derived ChB receptors and the halide anions (Cl−, Br−) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis‐bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans‐monodentate receptors. In particular, the telluro‐triazolium‐based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB‐assisted halide abstraction in a Friedel–Crafts alkylation benchmark reaction. [ABSTRACT FROM AUTHOR]

Exploring new noncovalent bonding motifs with reversibly tunable binding affinity is of fundamental importance in manipulating the properties and functions of supramolecular self‐assembly systems and materials. Herein, for the first time, we demonstrate a unique visible‐light‐switchable telluro‐triazole/triazolium‐based chalcogen bonding (ChB) system in which the Te moieties are connected by azobenzene cores. The binding strengths between these azo‐derived ChB receptors and the halide anions (Cl−, Br−) could be reversibly regulated upon irradiation by visible light of different wavelengths. The cis‐bidentate ChB receptors exhibit enhanced halide anion binding ability compared to the trans‐monodentate receptors. In particular, the telluro‐triazolium‐based ChB receptor can achieve both high and significantly photoswitchable binding affinities for halide anions, which enable it to serve as an efficient photocontrolled organocatalyst for ChB‐assisted halide abstraction in a Friedel–Crafts alkylation benchmark reaction. [ABSTRACT FROM AUTHOR]

A photo‐switchable hetero‐complementary quadruple H‐bonding array, which consists of an azobenzene‐derived ureidopyrimidinone (UPy) module (Azo‐UPy) and a nonphotoactive diamidonaphthyridine (DAN) derivative (Napy‐1), is constructed based on a reversible photo‐locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo‐switchable quadruple H‐bonded dimerization between Azo‐UPy and Napy‐1 can be achieved with exhibiting 4.8×104‐fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo‐controlled macroscopic self‐assembly behavior can be fabricated by introducing such quadruple H‐bonding array as photo‐regulable noncovalent interfacial connections. [ABSTRACT FROM AUTHOR]

The E2F1 transcription factor is a well known regulator of cell proliferation and apoptosis, but its role in response to DNA damage is less clear. 8-Chloro-adenosine (8-Cl-Ado), a nucleoside analog, can inhibit proliferation in a variety of human tumor cells. However, it is still elusive how the agent acts on tumors. Here we show that A549 and H1299 cells formed DNA double-strand breaks after 8-Cl-Ado exposure, accompanied by E2F1 upregulation at protein level. Overexpressed wild-type (E2F1-wt) colocalized with double-strand break marker γ-H2AX and promoted G2/M arrest in 8-Cl-Ado-exposed A549 and H1299, while expressed S31A mutant of E2F1 (E2F1-mu) significantly reduced ability to accumulate at sites of DNA damage and G2/M arrest, suggesting that E2F1 is required for activating G2/M checkpoint pathway upon DNA damage. Transfection of either E2F1-wt or E2F1-mu plasmid promoted apoptosis in 8-Cl-Ado-exposed cells, indicating that 8-Cl-Ado may induce apoptosis in E2F1-dependent and E2F1-independent ways. These findings demonstrate that E2F1 plays a crucial role in 8-Cl-Ado-induced G2/M arrest but is dispensable for 8-Cl-Ado-induced apoptosis. These data also suggest that the mechanism of 8-Cl-Ado action is complicated. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, the reproductive toxicity of male mice treated with Microcystis aeruginosa cell extracts containing microcystins was examined. In contrast to the control group, male mice exposed intraperitoneally to 3.33 or 6.67μg microcystins/kg body weight for 14 days had decreased mean body weight, and the mean absolute weight of the testes and epididymides was decreased. However, the mean relative weight of the testes increased compared to the controls. In addition, histological examination of microcystin-treated mice indicated that the testes were damaged and the space between the seminiferous tubules was more pronounced compared to control mice. The quality of mature sperm in the seminiferous tubules was also decreased in treated mice compared with the control group. Further studies showed that motility and viability of the sperm from microcystin-treated mice were reduced, but no significant difference was found in the concentration and abnormality of the sperm from treated mice compared to the control. This study indicated that microcystins had numerous toxic effects on the reproductive system of male mice. [Copyright &y& Elsevier]

Exploring dynamic bonds and their applications in fabricating dynamic materials has received great attention. A photoinduced [2]rotaxane‐based dynamic mechanical bond (DMB) features visible‐light‐triggered dynamic bonding behavior that is essentially distinguished from conventional dynamic chemical bonds. In this DMB, a photoisomerizable ortho‐fluoroazobenzene unit is introduced as a steric‐controllable stopper, the visible‐light‐induced dynamic wagging movement of which enables the photoregulated threading of the macrocycle. This allows reversible in situ de‐/reforming of the mechanical bond without involving dynamic chemical linkage. The DMB‐cross‐linked polymeric gel shows interesting photoinduced degradation behavior upon visible light irradiation. Benefiting from the distinctive dual dynamic nature of reversible bonding behavior and mechanical interlocked structure, this DMB is expected to serve as a new type of dynamic bond that can be applied in designing dynamic soft materials. [ABSTRACT FROM AUTHOR]

Exploring dynamic bonds and their applications in fabricating dynamic materials has received great attention. A photoinduced [2]rotaxane‐based dynamic mechanical bond (DMB) features visible‐light‐triggered dynamic bonding behavior that is essentially distinguished from conventional dynamic chemical bonds. In this DMB, a photoisomerizable ortho‐fluoroazobenzene unit is introduced as a steric‐controllable stopper, the visible‐light‐induced dynamic wagging movement of which enables the photoregulated threading of the macrocycle. This allows reversible in situ de‐/reforming of the mechanical bond without involving dynamic chemical linkage. The DMB‐cross‐linked polymeric gel shows interesting photoinduced degradation behavior upon visible light irradiation. Benefiting from the distinctive dual dynamic nature of reversible bonding behavior and mechanical interlocked structure, this DMB is expected to serve as a new type of dynamic bond that can be applied in designing dynamic soft materials. [ABSTRACT FROM AUTHOR]

Heavy metals are frequently encountered as mixtures of essential and non-essential elements. Therefore, evaluation of their toxic effects individually does not offer a realistic estimate of their impact on biological processes. We studied effects of exposure to mixtures of essential and toxic metals (Cr, Cd and Pb) on biochemical, immunotoxicity level and morphological characteristics of the various tissues of a biomarker freshwater fish common carp using environmentally relevant concentrations. Fish were exposed to metal mixture through tank water for 7, 15 and 30 days, under controlled laboratory conditions. Tissue accumulation of the metals was measured using Atomic Absorption Spectrophotometric techniques. Chromium, cadmium and lead accumulation in muscle, gills, liver, kidney and intestine, tissue of common carp exposed to mixture metals for 30 days increased significant compared with control group (p < 0.001). However, the activity of antioxidant enzymes such as catalase (CAT) and superoxide dismutase (SOD) levels was significant altered in various tissues of exposed fish. Besides, the lipid peroxidation (LPO) was significant (p < 0.001) increased. Moreover, the tumor necrosis factor - α (TNF-α), interleukin (IL-6), and interferon-γ (IFN-γ) contents in tissues of muscle, gills, liver, kidney and intestine were increased significant compared with control fish (p < 0.001). In addition, microscopic examination of the main alterations in general morphology of fish gills included spiking and fusion of secondary lamellae, formation of club-shaped filaments epithelium in the interlamellar regions and hepatocytes showed damage of central vein and rupture of irregular hepatic plate with more number of vacuoles in the fish exposed to metal mixture for a longer duration (30 days). These results of this study clearly demonstrate that concentration individual and mixtures of metals in aquatic systems will greatly influence the cytokine alterations may result in an immune suppression or excessive activation in the treated common carp as well as may cause immune dysfunction or reduced immunity. In conclusion, toxicity of multiple metal mixtures of Cr, Cd and Pb has antioxidant and immunotoxic effects on C. carpio. [ABSTRACT FROM AUTHOR]