ABSTRACT
The aim of this work was to develop a screening method for MRP2 efflux substrates using the well-characterized, human-based intestinal Caco-2 cell model as a platform. MRP2 has a significant role in drug absorption and disposition and is known to co-operate with phase II metabolic enzymes. Caco-2 cells grown in a 96-well plate were loaded with non-fluorescent CDCFDA (diacetate ester of 5(6)-carboxy-2',7'-dichlorofluorescein), which is hydrolyzed to fluorescent CDCF by intracellular esterases. De-esterification in Caco-2 was comparable to that in porcine liver esterases. CDCFDA enters the cells passively, while CDCF is effluxed out of the cells by the apically localized MRP2 and/or basolateral MRPs. The method was optimized with regard to several factors. In the concluding protocol, Caco-2 cells are grown on clear 96-well plates for 8 days. The loading conditions were optimized to 10 min incubation with 5 microM CDCFDA. The highest responses were obtained for samples taken at t=30 min. The samples were analyzed in black 96-well plates with a fluorescence plate reader. The Caco-2 based method utilizing the probe pair CDCFDA/CDCF provides a fast screening tool for MRP2 substrates and/or inhibitors, along with compounds having metabolites formed in Caco-2 that interact with MRP2.
Subject(s)
Fluoresceins/metabolism , Models, Biological , Multidrug Resistance-Associated Proteins/metabolism , Biological Transport , Caco-2 Cells , Fluorescent Dyes/metabolism , Humans , Multidrug Resistance-Associated Protein 2 , Multidrug Resistance-Associated Proteins/drug effects , Pharmaceutical Preparations/metabolismABSTRACT
Most dioecious plants do not exhibit discernible sexual dimorphism before sexual maturity. Therefore, it is impossible to address any sex-related questions during the prereproductive phase unless a genetic sex marker is available for gender determination. The aim of the present study was to develop a genetic sex marker for the moss Pseudocalliergon trifarium to allow gender and sex ratio determination at any stage in the life cycle. A high proportion of P. trifarium populations do not express sex. The screening of genomic DNA with inter simple sequence repeat (ISSR) primers was used to discover sex-specific polymerase chain reaction (PCR) amplification products. A presumably female-specific band was found, excised from the gel, cloned, and sequenced. A sequence-walking method was used to characterize the same region in males. A primer pair was designed to allow the amplification of a 159-bp portion of the female-specific DNA region. All tested material, up to 16-year-old herbarium specimens, provided unambiguous amplification products. This study successfully provides, for the first time in a moss, a sex-specific DNA marker. It allows reliable determination of gender and sex ratios. The short length of the amplification product is an advantage as satisfactory PCR products are more likely when the targeted sequence is short. The amount of variation in the DNA region shared by both sexes was relatively high. If the male sequence can be better characterized, the sex-specific regions could possibly be used to evaluate sex-specific phylogeographic patterns.
