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

Gene expression, metabolic regulation and stress tolerance during diapause

Decapsulation of Artemia cysts: A simple technique for the improvement of the use of brine shrimp in aquaculture

3 – Reproduction and Its Control

Encysted brine-shrimp gastrulae bring their metabolism to a reversible standstill during diapause and quiescence, demonstrating a remarkable resistance to unfavourable environmental conditions. For example, mortality of Artemia embryos under normal temperature and hydration is very low, even after two years of anoxia, and embryos commonly experience complete desiccation as part of their developmental program. Previous evidence from our laboratories indicated that p26, an abundant low-molecular-mass cyst-specific protein capable of translocation into the nucleus, may have a protective function in Artemia cysts. p26 was purified to apparent homogeneity and a continuous sequence of 141 of its amino acids was determined by peptide sequencing, revealing that it is a member of the small-heat-shock/α-crystallin family of proteins. As determined by molecular-sieve chromatography and sucrose-density-gradient centrifugation, native p26 is a multimer of about 27 monomers with a molecular mass of approximately 700 kDa. Inactivation of citrate synthase was less when the enzyme was heated in the presence rather than the absence of p26. Additionally, the renaturation of heat-inactivated citrate synthase was promoted by p26. These results indicated that p26 possesses molecular-chaperone activity, a property of other small heat-shock/u-crystallin proteins. Our findings demonstrate that p26 has the potential to protect the macromolecular components of Artemia embryos, either as they encyst or upon exposure to environmental extremes. Protection may depend upon the ability of p26 to function as a molecular chaperone.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1997.0225a.x

J.H. Lochhead

Papers

The origin and structure of the tertiary envelope in thick-shelled eggs of the brine shrimp, Artemia.