Enhanced fluorescence quenching in an acridine orange - alizarin red system through matrine and its analytical application

New insights into detecting alizarin from autofluorescence in marked glass eels

Alizarin detection in fish fins is extensively employed because it is easy to use. However, in eels, the eelGFP fluorescent protein may impede the detection of the fluorescent markers in the eel tissues. The study tests the effectiveness of three of the most up-to-date alizarin-detecting technologies on the living body and fins of European glass eels (Anguilla anguilla L.). The findings demonstrated that the control group had a high autofluorescence at alizarin and eelGFP maxima bands. With fluorescence reflectance imaging (FRI), the eel living body autofluorescence impeded the detection of the marked eels. In contrast with experimental excitation-emission-matrix (EEM) fluorescence analyses, 99% of the marked eels were correctly assigned to their group from fluorescence analyses of their fin cellular contents. With epifluorometry (EPI), 100% of the marked eels were detected with the caudal fin tips when excited at 450–490 nm wavelengths due to a weaker autofluorescence signal. EEM and FRI assays unveiled an average fluorescence quenching 60% and 44% of the marked group respectively, in the alizarin and eelGFP maxima bands. The fluorescence quenching observed is discussed. Results will benefit experimental design by examining autofluorescence effects on mark detection and the development of non-invasive detection methods in this critically endangered species.

Matrine compromises mouse sperm functions by a [Ca(2+)]i-related mechanism

Matrine, a bioactive alkaloid widely used in Chinese medicine, inhibits mouse sperm functions in vitro. In this study, we investigated the reproductive toxicity of matrine to male mice in vivo. C57BL/6J mice were administered with daily doses of 0, 1, 10 and 50mg/kg matrine by intraperitoneal injection for 30 days. The results showed that matrine did not affect testis size, testis weight, sperm count and sperm viability, but it significantly inhibited total motility, progressive motility, linear velocity, capacitation and the progesterone-induced acrosome reaction of mouse sperm. Furthermore, the intracellular Ca(2+) concentration ([Ca(2+)]i), a key regulator of sperm function, was reduced in sperm of matrine-exposed mice. The current and gene expression of the sperm specific Ca(2+) channel, CatSper, which modulates Ca(2+) influx in sperm, were decreased in testes of matrine-exposed mice. These results indicate that matrine inhibits mouse sperm functions by a [Ca(2+)]i-related mechanism via CatSper channel.