Metallothioneins in Earthworms: The Journey So Far

Abstract

Earthworms play important roles in terrestrial ecosystems including evaluating the health status of the soil in environmental studies. Its regulation and detoxifi cation of metallic metals and the non-essential metal ion are associated with the possession of Metallothioneins (MTs). Three isoforms of MTs are induced in some species of earthworms under stress in the soil; wMT1, wMT2, and wMT3 (found in cocoons). Though reports on the nucleotide sequences, mechanisms of action and entire functions of two earthworm MTs isoforms exist, the precise mechanism of action and entire functions of wMT3 are still obscure. Metals and stress are known inducers of MTs in earthworms. In recent times, Contaminants of Emerging Concerns (CECs) and the advent of nanotechnology has occasioned a handful of studies evaluating their effect in the environment using biomarkers like metallothioneins. More research focusing on CECs' and nanoparticles' ecotoxicological impact in the environment by monitoring biomarkers like earthworm metallothioneins is encouraged. The detection and quantifi cation of MTs involve a wide array of techniques including analytical, instrumentation and molecular analyses which remains the most commonly used. This review evaluates the various methods and highlights their pros and cons.

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“…Entering cells, heavy metals bind mainly to functional groups of proteins and others (for example, the formation of metallothioneins or compounds involved in biotransformation (Kim et al, 2019;Aemere et al, 2020;Samuel et al, 2021), which may be related to detoxification mechanisms. Therewith, this is the cause of metabolic disorders and an explanation of the high toxicity of heavy metals ( The interaction of metals entering the cell can cause antagonism, synergy, and affect to a certain extent the content of individual metals in cells and, accordingly, in tissues.…”

Medicinal Perspective of Antibacterial Bioactive Agents in Earthworms (Clitellata, Annelida): A Comprehensive Review

“…MTs are heat resistant, ubiquitous proteins and composed of 70 amino acids with nearly 30％ thiol containing cysteine rich amino acid residues 15) . The synthesis of MTs are regulated through a multigene family which induces its response by various inducers including glucocorticoids, oxidants, heavy metals, hormones, strenuous exercise, hydroxyl radicals and superoxide 16,17) . These are abundantly found in a large range from simplest microbes to complex mammals and are also reported in invertebrate including annelids.…”

“…Although data on the mechanism of action, nucleotide sequences, and whole functions of two MTs isoforms earthworm exist while for MT3, method of action and complete functions are still doubtful. So, the stress and metals are important inducers in earthworm for production of MTs 16) . Role of these proteins is well documented in the medical field.…”