Description: Tolerance of organisms towards heterogeneous and variable environments is highly related to physiological flexibility. An effective strategy to enhance physiological flexibility is the expression of polymorphic enzymes. This seems to be the case in the brown shrimp Crangon crangon. It shows high reproduction rates, feeds opportunistically on endo- and epibenthic organisms, and is apparently well adapted to variable environmental conditions. Previous electrophoretic studies revealed a high level of polymorphism and no consistent phenotype of digestive enzymes between individuals. In order to understand the underlying biochemical processes, we carried out a transcriptome-based study of digestive enzymes of C. crangon. Detailed sequence analyses of triacylglycerol lipase, phospholipase A2, alpha amylase, chitinase, trypsin and cathepsin L were performed to identify putative isoforms. The number of isoforms, and thus the degree of polymorphism varied among enzymes: lipases and carbohydrases showed higher numbers of isoforms in enzymes that besides their extracellular function also have diverse intracellular functions. Furthermore, cysteine proteinases showed a lower polymorphism than serine proteinases. We suggest that the expression of enzyme isoforms improves the efficiency of C. crangon in gaining energy from different food sources.

Description: Molecular technologies are more frequently applied in Antarctic ecosystem research and the growing amount of sequence-based information available in databases adds a new dimension to understanding the response of Antarctic organisms and communities to environmental change. We apply molecular techniques, including fingerprinting, and amplicon and metagenome sequencing, to understand biodiversity and phylogeography to resolve adaptive processes in an Antarctic coastal ecosystem from microbial to macrobenthic organisms and communities. Interpretation of the molecular data is not only achieved by their combination with classical methods (pigment analyses or microscopy), but furthermore by combining molecular with environmental data (e.g., sediment characteristics, biogeochemistry or oceanography) in space and over time. The studies form part of a long-term ecosystem investigation in Potter Cove on King-George Island, Antarctica, in which we follow the effects of rapid retreat of the local glacier on the cove ecosystem. We formulate and encourage new approaches to integrate molecular tools into Antarctic ecosystem research, environmental conservation actions, and polar ocean observatories.

Description: Transcriptional regulation constitutes a rapid response of marine organisms facing stressful environmental conditions, such as the concomitant exposure to warming, ocean acidification and hypoxia under climate change. In previous studies, we investigated whole-organism physiological patterns and cellular metabolism in gill and muscle of the marine gastropod Haliotis fulgens in response to increasing temperature (18 °C to 32 °C at +3 °C per day) under hypoxia (50% air saturation), hypercapnia (1000 μatm pCO2) and both factors combined. Here, we report investigations of the molecular responses of H. fulgens to temperature and identify mechanisms concomitantly affected by hypoxia and hypercapnia. A de novo transcriptome assembly with subsequent quantitative PCR and correlation network analysis of genes involved in the molecular response were used to unravel the correlations between gene expression patterns under the different experimental conditions. The correlation networks identified a shift from the expression of genes involved in energy metabolism (down-regulated) to the up-regulation of Hsp70 during warming under all experimental conditions in gill and muscle, indicating a strong up-regulation of damage prevention and repair systems at sustained cellular energy production. However, a higher capacity for anaerobic succinate production was evicted in gill, matching with observations from our previous studies indicating succinate accumulation in gill but not in muscle. Additionally, warming under hypoxia and hypercapnia kept mRNA levels of citrate synthase in both tissues unchanged following a similar pattern as muscle enzyme capacity from a previous study, suggesting an emphasis on maintaining rather than down-regulating mitochondrial activity. Keywords: Cellular stress response; Climate change; Gastropod; Gene expression; qPCR