CYTOGENETICS OF ARTEMIA: A COMPREHENSIVE REVIEW

Abstract

The genus Artemia containing brine shrimps, is a landmark model organism in cytogenetics research due to its remarkable adaptability to hypersaline, anoxic and high-altitude environments, as well as its diverse reproductive modes, including bisexual reproduction and parthenogenesis. This exhaustive review reflects progress in Artemia cytogenetics, with a major focus on chromosome scale genome assemblies, karyotypic polymorphisms, sex chromosome evolution, molecular cytogenetic techniques e.g. fluorescence in situ hybridisation (FISH).

 A significant taxonomic update is the recent description of Artemia amati by Asem et al. (2023), a bisexual species native to Kazakhstan (previously "Artemia sp. Kazakhstan"), which provides a new framework for studying Central Asian populations. One of the most important findings is the chromosome-scale genome assembly of the Qinghai-Tibet Plateau species A. tibetiana, which contains 21 pseudochromosomes and provides insights into adaptations to high-altitude stress.

Assemblies of the A. franciscana have defined ZW sex determination systems with differentiated evolutionary strata and possible meiotic silencing pathway. The population-genomic studies of Chinese Artemia define the four different clades, which, in turn, were affected by the geologic uplift, climatic variations, and anthropogenic effects, with high nucleotide diversity in Tibetan populations. Single-nucleus profiling shows that the Z chromosome was repressed in germline oogenesis indicating that the meiotic sex chromosomal inactivation had taken place.

The diapause termination networks controlled by the transcriptional factors include SVP, MYC, RXR, and SMAD6 that regulate cell adhesion, signal transduction, and redox homeostasis. These findings shed light on the evolutionary cytogenetics, stress-adaptation, and biotechnological perspectives of aquaculture and conservation of the species Artemia. Future research needs to capitalize on integrative multi-omics to solve the remaining problems, such as full W chromosome-level resolution and inter-species dynamic-hybridisation.

Keywords: Artemia cytogenetics, Artemia amati, genome assembly, karyotype variation, sex chromosomes, parthenogenesis, population genetics, diapause regulation