Aggressive behaviour of African catfish clarias gariepinus juveniles under different light intensities and light wavelengths

The survival and growth rates of African catfish (Clarias gariepinus) were reported to be affected by light conditions. One of the methods to understand the effects of light conditions on fish survival and growth rates is through analysing the aggressive behaviour of the fish. The objective of the present study was to analyse the aggressive behaviours of African catfish juveniles under different light intensities and light wavelengths. For this purpose, the behaviour of African catfish juveniles (average body weight = 0.45 ± 0.19; average total length = 35.2 ± 5.0) was observed under three light intensities (0.0014, 0.014, and 1.40 μmoles/m²/s) and five light wavelengths (white, blue, green, yellow, and red). The results showed that the aggressive behaviour of the fish was significantly affected by light intensities and light wavelengths. Among the three light intensities, the juveniles showed less aggressive behaviour under 0.0014 μmoles/m²/s. Furthermore, the juveniles also showed less aggressive behaviour under the yellow light. Therefore, the rearing of African catfish juveniles under of 0.0014 μmoles/m²/s and yellow light wavelength is recommended

Sensitive Conjugated-Polymer-Based Fluorescent ATP Probes and Their Application in Cell Imaging

Three cationic conjugated polyelectrolytes (CPEs) with a common poly­(<i>p</i>-phenylene ethynylene terthiophene) backbone and side chains of different lengths, named as PPET3-N1, PPET3-N2, and PPET3-N3, were designed and synthesized. The UV–vis absorption and fluorescence spectra of the polymers vary strongly with solvent composition, suggesting that the polymers are strongly aggregated in H₂O. In addition, the spectroscopic properties of the polymers are affected by small-molecule ATP, characterized by significant fluorescence intensity decreases and red shifts of their absorption bands. Further application of these polymers in cell imaging was studied by confocal fluorescence microscopy, which demonstrated that all of the polymers were localized on the cell membrane and partially inside of cells and that the staining effect gradually increased with the length of the polymer side chains. On the basis of the low cytotoxicity and efficient quenching of PPET3-N2 by ATP, the dose and time effects of ATP on PPET3-N2 imaging were studied, and the results indicated that this polymer might have potential in cell imaging for ATP semiquantification in vivo

Light-Induced Translocation of a Conjugated Polyelectrolyte in Cells: From Fluorescent Probe to Anticancer Agent

Dual-functional probes, which not only enable visualization of diseased cells but also induce therapeutic cellular responses, are essential to biological studies. In the current work, a conjugated polyelectrolyte, PPET3-N2, was designed and synthesized as a dual-functional probe. The poly­(phenylene ethynylene) terthiophene polymer backbone contributes to the polymer’s light-harvesting property to ensure the strong fluorescence as well as photosensitization, whereas quantanary ammonium side chains interact with target organelle for localization. As a fluorescent probe, PPET3-N2 was endocytosed to lysosomes through clathrin-mediated endocytosis (CME) and macropinocytosis (MPC) pathways. Colocalization of the probe with commercial fluorescent lysosome labels confirmed that this probe localized on lysosomes with high specificity and photostability. Real-time monitoring of autolysosome formation in autophagic cells was also demonstrated, providing a viable platform for cell-based screening of autophagy inhibitors. Finally, as a photosensitizer, PPET3-N2 can efficiently generate singlet oxygen in living cells upon irradiation of white light, leading to the destruction of lysosome membrane and release of ROS and lysosomal enzymes in cytoplasma, causing cell death