Genes and associated peptides involved with aestivation in a land snail.

Some animals can undergo a remarkable transition from active normal life to a dormant state called aestivation; entry into this hypometabolic state ensures that life continues even during long periods of environmental hardship. In this study, we aimed to identify those central nervous system (CNS) peptides that may regulate metabolic suppression leading to aestivation in land snails. Mass spectral-based neuropeptidome analysis of the CNS comparing active and aestivating states, revealed 19 differentially produced peptides; 2 were upregulated in active animals and 17 were upregulated in aestivated animals. Of those, the buccalin neuropeptide was further investigated since there is existing evidence in molluscs that buccalin modulates physiology by muscle contraction. The Theba pisana CNS contains two buccalin transcripts that encode precursor proteins that are capable of releasing numerous buccalin peptides. Of these, Tpi-buccalin-2 is most highly expressed within our CNS transcriptome derived from multiple metabolic states. No significant difference was observed at the level of gene expression levels for Tpi-buccalin-2 between active and aestivated animals, suggesting that regulation may reside at the level of post-translational control of peptide abundance. Spatial gene and peptide expression analysis of aestivated snail CNS demonstrated that buccalin-2 has widespread distribution within regions that control several physiological roles. In conclusion, we provide the first detailed molecular analysis of the peptides and associated genes that are related to hypometabolism in a gastropod snail known to undergo extended periods of aestivation.

Differential peptide expression in the central nervous system of the land snail Theba pisana, between active and aestivated.

Hypometabolism is a physiological state of dormancy entered by many animals in times of environmental stress. There are gaps in our understanding of the molecular components used by animals to achieve this metabolic state. The availability of genomic and transcriptome data can be useful to study the process of hypometabolism at the molecular level. In this study, we use the land snail Theba pisana to identify peptides that may be involved in the hypometabolic state known as aestivation. We found a total of 22 neuropeptides in the central nervous system (CNS) that were differentially produced during activity and aestivation based on mass spectral-based neuropeptidome analysis. Of these, 4 were upregulated in active animals and 18 were upregulated in aestivation. A neuropeptide known to regulate muscle contractions in a variety of molluscs, the small cardioactive peptide A (sCAPA), and a peptide of yet unknown function (termed Aestivation Associated Peptide 12) were chosen for further investigation using temporal and spatial expression analysis of the precursor gene and peptide. Both peptides share expression within regions of the CNS cerebral ganglia and suboesophageal ganglia. Relative transcript abundance suggests that regulation of peptide synthesis and secretion is post-transcriptional. In summary, we provide new insights into the molecular basis of the regulation of aestivation in land snails through CNS peptide control.