Seasonal proteome variation in intertidal shrimps under a natural setting: connecting molecular networks with environmental fluctuations

Abstract

The ability of intertidal organisms to maintain their performance via molecular and physiological adjustments under low tide, seasonal fluctuations and extreme events ultimately determines population viability. Analyzing this capacity in the wild is extremely relevant since intertidal communities are under increased climate variability owing to global changes. We addressed the seasonal proteome signatures of a key intertidal species, the shrimp Palaemon elegans, in a natural setting. Shrimps were collected during spring and summer seasons at low tides and were euthanized in situ. Environmental variability was also assessed using hand-held devices and data loggers. Muscle samples were taken for 2D gel electrophoresis and protein identification through mass spectrometry. Proteome data revealed that 55 proteins (10.6% of the proteome) significantly changed between spring and summer collected shrimps, 24 of which were identified. These proteins were mostly involved in cytoskeleton remodelling, energy metabolism and transcription regulation. Overall, shrimps modulate gene expression leading to metabolic and structural adjustments related to seasonal differences in the wild (i.e. abiotic variation and possibly intrinsic cycles of reproduction and growth). This potentially promotes performance and fitness as suggested by the higher condition index in summer-collected shrimps. However, inter-individual variation (% coefficient of variation) in protein levels was quite low (min-max ranges were 0.6-8.3% in spring and 1.2-4.8% in summer), possibly suggesting reduced genetic diversity or physiological canalization. Protein plasticity is relevant to cope with present and upcoming environmental variation related to anthropogenic forcing (e.g. global change, pollution) but low inter-individual variation may limit evolutionary potential of shrimp populations.