Gene expression, metabolic regulation and stress tolerance during diapause

Abstract

Diapause entails molecular, physiological and morphological remodeling of living animals, culminating in a dormant state characterized by enhanced stress tolerance. Molecular mechanisms driving diapause resemble those responsible for biochemical processes in proliferating cells and include transcriptional, post-transcriptional and post-translational processes. The results are directed gene expression, differential mRNA and protein accumulation and protein modifications, including those that occur in response to changes in cellular redox potential. Biochemical pathways switch, metabolic products change and energy production is adjusted. Changes to biosynthetic activities result for example in the synthesis of molecular chaperones, late embryogenesis abundant (LEA) proteins and protective coverings, all contributing to stress tolerance. The purpose of this review is to consider regulatory and mechanistic strategies that are potentially key to metabolic control and stress tolerance during diapause, while remembering that organisms undergoing diapause are as diverse as the processes itself. Some of the parameters described have well-established roles in diapause, whereas the evidence for others is cursory.

Fig. 1

Diapause. Regulatory processes triggered by external and internal signals occur in many organisms capable of undergoing diapause, a physiological process characterized by overlapping stages. All diapause organisms exhibit one or more properties, in varying degrees of intensity, which enable survival upon exposure to harsh environments and permit the mixing of genes from temporally separated populations. This review demonstrates underlying similarities between diapauses in organisms that may otherwise appear unrelated and that diapause in different organism is often characterized by shared properties expressed in varying intensities

Fig. 2

Regulation of diapause by ROS and RNS. When produced in excess, ROS and RNS damage macromolecules leading to cell malfunction and death. In contrast, both ROS (H₂O₂) and RNS (NO) act as, or modulate, second messengers resulting in posttranslational modifications which affect protein activity and cell behavior, changes with the potential to influence diapause, although this has yet to be thoroughly investigated at the molecular level

Fig. 3

LEA proteins in animals. LEA proteins, first observed in plants, have been reported in three animals where they may provide tolerance against water stress. Group 3 LEA proteins are found in all three animals, whereas only A. franciscana exhibits group 1 LEA proteins