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Abstract
The neritid snail Theodoxus fluviatilis has formed regional subgroups in northern Europe, where it appears in both freshwater (FW) and brackish water (BW) in coastal areas of the Baltic Sea. These ecotypes show clear differences in osmotolerance and in the modes of accumulating organic osmolytes under hyperosmotic stress. We reasoned that the expression patterns of soluble proteins in the two ecotypes may differ as well. BW snails have to deal with a higher salinity (up to 20‰) than FW snails (0.5‰) and also cope with frequent fluctuations in environmental salinity that occur after heavy rains or evaporation caused by extended periods of intense sunshine. Therefore, the protein expression patterns of specimens collected at five different FW and BW sites were analyzed using 2D SDS‐PAGE, mass spectrometry, and sequence comparisons based on a transcriptome database for Theodoxus fluviatilis. We identified 89 differentially expressed proteins. The differences in the expression between FW and BW snails may be due to phenotypic plasticity, but may also be determined by local genetic adaptations. Among the differentially expressed proteins, 19 proteins seem to be of special interest as they may be involved in mediating the higher tolerance of BW animals towards environmental change compared with FW animals.
Renal drug transporters such as the organic cation transporters (OCTs), organic anion
transporters (OATs) and multidrug resistance proteins (MRPs) play an important role in the tubular
secretion of many drugs influencing their efficacy and safety. However, only little is known about
the distinct protein abundance of these transporters in human kidneys, and about the impact of
age and gender as potential factors of inter-subject variability in their expression and function.
The aim of this study was to determine the protein abundance of MDR1, MRP1-4, BCRP, OAT1-3,
OCT2-3, MATE1, PEPT1/2, and ORCTL2 by liquid chromatography-tandem mass spectrometry-based
targeted proteomics in a set of 36 human cortex kidney samples (20 males, 16 females; median age
53 and 55 years, respectively). OAT1 and 3, OCT2 and ORCTL2 were found to be most abundant
renal SLC transporters while MDR1, MRP1 and MRP4 were the dominating ABC transporters.
Only the expression levels of MDR1 and ORCTL2 were significantly higher abundant in older donors.
Moreover, we found several significant correlations between different transporters, which may
indicate their functional interplay in renal vectorial transport processes. Our data may contribute to
a better understanding of the molecular processes determining renal excretion of drugs.