DNA and RNA Damage, Protection, and Repair in Desiccation-Tolerant Metazoans

Area of Science:

• * Molecular Biology
• * Stress Physiology
• * Evolutionary Biology

Background:

• * Desiccation, radiation, and oxidative stress threaten nucleic acid integrity.
• * Water loss causes molecular crowding and ROS accumulation; rehydration can worsen oxidative injury.
• * Stress-tolerant animals must protect, monitor, and restore nucleic acid integrity.

Purpose of the Study:

• * Review how tardigrades, rotifers, Artemia, nematodes, and insects preserve genomic and transcriptomic integrity.
• * Compare conserved defense systems and lineage-specific innovations.
• * Propose a framework for understanding stress biology in extremotolerant metazoans.

Main Methods:

• * Comparative review of existing literature.
• * Analysis of conserved defense mechanisms (antioxidant enzymes, trehalose, LEA proteins, heat shock proteins, DNA repair pathways).
• * Examination of lineage-specific innovations (e.g., tardigrade proteins Dsup, TDR1, TRID1, bdelloid genome plasticity).

Main Results:

• * Conserved systems include antioxidant enzymes, trehalose, LEA proteins, HSPs, and core DNA repair pathways (BER, NER, HR, NHEJ).
• * Lineage-specific innovations enhance protection, such as tardigrade-specific proteins and bdelloid genome plasticity.
• * A framework distinguishing damage prevention (drying) from repair/recovery (rehydration) is proposed.

Conclusions:

• * Extremotolerant metazoans employ diverse strategies to maintain nucleic acid integrity under stress.
• * These organisms serve as valuable models for studying oxidative damage, redox defense, and radioprotection.
• * Understanding dry-state preservation mechanisms is crucial for various biological and biotechnological applications.