Review on Artemia as Ultimate model for Genomic research

 

Peter Marian. M 1,2

 

1 Marine Biotechnology Laboratory, ICAS of M.S University, Rajakkamangalam, Kanyakumari District, Tamil

Nadu, South India 

2 Institute for Artemia Research and Training, M.S University, Rajakkamangalam, Kanyakumari District, Tamil

Nadu, South India

Abstract This review claims attention of genomic researchers about a tiny crustacean Artemia. Apart from serving as livefeed in aquaulture industries, Artemia seems to be the ultimate model for several genomic puzzles. Genomic research on Artemia at the molecular level is still in its infancy and a complete genomic analysis is needed. Artemia has proved to be a potential model for classical genetic studies in the past and molecular level approaches are yet to be iniated such as functional genomics, population genomics etc. Artemia shows well developed gene regulatory system for its survival even under extreme conditions. Artemia seems to be a promising system for stress response studies as observed in our laboratory since it shows a swift adaptation to harsh environments. A variety of Heat shock proteins (HSPs) were expressed which when characterized will give a detailed information about its stress tolerance. The cryptobiotic cysts of Artemia can remain viable for long period in abnormal conditions like -irradiation, temperature, salinity and long-term anoxia. Available data from genetic databases are also reviewed in this paper and the status of Artemia genomic research in Indian subcontinent is also discussed. 

 

Life Cycle 18-24 days

Haploid genome size 0.9 x 1012 bp

Number of Chromosome 42 bisexual / parthenogenetic Artemia46 in Artemia persimilis

Number of Mapped Markers Parthenogenetic 94 RAPDBisexual – 27 RAPD 70 RAPD Primers43 AFLP

Number of Cloned Genes 348

Mode of Reproduction bisexual / parthenogenetic

Transgenesis No

Mitochontrial genome size 15822 bp

Total Ribosomal rRNA gene copies 320 (18S + 26S)

Gene Bank Entries 508

IImportance of Artemia Genome project (ArGP)         Extremophilic eukaryote lives comfortable in normal conditions also        Will lay Foundation for Genetic improvement programme        Swift adaptations to harsh and normal conditions which can contribute enormous data to medical field.        To develop knowledge base on stress proteins and molecular chaperones for human welfare        Can contribute gene resource for saline stress proteins to other eukaryotes

Gene expressions in abnormal conditions yet characterized         In Quiescent embryos of the Artemia the level of aminoacylation of tRNA is low and the expression of tRNA genes are dramatically reduced (Brandsma et al., 1997).         Expression of P26 genes, (a family of HSPs) (Liang, et al., 1997)         Lower expression of cytochrome c oxidase (COX 1) in anoxia which can be activates by previous measures of COX1 catalytic activities (Hardewiz et al., 1996).         Very low expression of Na+ / K(+) ATPase and Ca(2+) dependent ATPase sense in Cryptobiosis         Reduced level of polysomes profiles for translational regulation         In continious anoixia protein P26 also behaves as GTPase to regulate Diguanosine nuclecotide metabolism (Warner and Glegg, 2001).

Comparitive genomics of Artemia with other eukaryotes         The mitochordrial genome of Artemia has the same coding capacity as most animal mitochondrial genomes, and its overall organization is similar to that of Drosophila (Carrodeguas and Vallego, 1997).         Five intrance sequence 14 kb genomic clone of Ca(2+) – ATPase genome of Drosophila melunegater are same position in Artemia SERCA, Ca(2+) ATPase genes. (Maggar et al., 1995).        The comparision of Artemia sequence with both vertebrate and invertebrate mitochondial 16S rDNA sequences has shown the existence of regions of high similarity with them (Palmero et al., 1988).         Similarity of the Artemia gene to insect rRNA in size, sequence and secondary structure, the G + C content of the Artemia gene (42%) is closes to that of mammals than the insect genes.

FFuture perspectives of Artemia genome research in IART         Developing mitochondrial Genome data base for various species of Artemia•AArtemia Gene Bank        Expression profiling of cyst inducing genes        Stress biochemistry and gene profile studies for chemical stresses        Application of Microarray technology for High through put screnning and expression of Genes in Artemia at abnormal conditions.

On going proteomic research at IART in Artemia on 

-         saline stresses-         cold shock, proteins-         naturally and artificially induced cyst formation-         strain characterization through molecular markers-         cross breeding and genetic improvement programme

Conclusion 

The molecular characterization of Artemia genome is poised on the edge of a new era. The large collections of Artemia mutants and practical breeding stocks are valuable resources that have only begun to be exploited to full potential. The well-studied gene resources of Artemia make it a ideal reference for the Insecta where comparative genetics and genomics can work together to elucidate conserved evolutionary pathways and their divergence due to extreme adaptations, identify new genes and gene systems as targets for transgenesis. Besides, it leads to basic research on new genome based approaches for exploitation of other species. Artemia genome project should be initiated for development of tools for targeted knockouts.