+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Genomics of Adaptation to Multiple Concurrent Stresses: Insights from Comparative Transcriptomics of a Cichlid Fish from One of Earth's Most Extreme Environments, the Hypersaline Soda Lake Magadi in Kenya, East Africa



Genomics of Adaptation to Multiple Concurrent Stresses: Insights from Comparative Transcriptomics of a Cichlid Fish from One of Earth's Most Extreme Environments, the Hypersaline Soda Lake Magadi in Kenya, East Africa



Journal of Molecular Evolution 81(3-4): 90-109



The Magadi tilapia (Alcolapia grahami) is a cichlid fish that inhabits one of the Earth's most extreme aquatic environments, with high pH (~10), salinity (~60% of seawater), high temperatures (~40 °C), and fluctuating oxygen regimes. The Magadi tilapia evolved several unique behavioral, physiological, and anatomical adaptations, some of which are constituent and thus retained in freshwater conditions. We conducted a transcriptomic analysis on A. grahami to study the evolutionary basis of tolerance to multiple stressors. To identify the adaptive regulatory changes associated with stress responses, we massively sequenced gill transcriptomes (RNAseq) from wild and freshwater-acclimated specimens of A. grahami. As a control, corresponding transcriptome data from Oreochromis leucostictus, a closely related freshwater species, were generated. We found expression differences in a large number of genes with known functions related to osmoregulation, energy metabolism, ion transport, and chemical detoxification. Over-representation of metabolism-related gene ontology terms in wild individuals compared to laboratory-acclimated specimens suggested that freshwater conditions greatly decrease the metabolic requirements of this species. Twenty-five genes with diverse physiological functions related to responses to water stress showed signs of divergent natural selection between the Magadi tilapia and its freshwater relative, which shared a most recent common ancestor only about four million years ago. The complete set of genes responsible for urea excretion was identified in the gill transcriptome of A. grahami, making it the only fish species to have a functional ornithine-urea cycle pathway in the gills--a major innovation for increasing nitrogenous waste efficiency.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 057937573

Download citation: RISBibTeXText

PMID: 26345661

DOI: 10.1007/s00239-015-9696-6


Related references

Eco-morphological differentiation in Lake Magadi tilapia, an extremophile cichlid fish living in hot, alkaline and hypersaline lakes in East Africa. Molecular Ecology 25(7): 1610-1625, 2016

A comparative allometric study of the morphometry of the gills of an alkalinity adapted cichlid fish, Oreochromis alcalicus grahami, of Lake Magadi, Kenya. International Journal of Salt Lake Research 52: 131-156, 1996

A comparative allometric study of the morphometry of the gills of an alkalinity adapted cichlid fish,Oreochromis alcalicus grahami, of Lake Magadi, Kenya. International Journal of Salt Lake Research 5(2): 131-156, 1996

Soda ash deposits, Lake Magadi, Kenya. U S, 1981

Isolation and Initial Study of M3-16, a Bacteriophage Infecting an Alkaliphilic Vibrio metschnikovii Isolate from Lake Magadi, a Soda Lake in Kenya's Great Rift Valley. Microscopy and Microanalysis 17(S2): 350-351, 2011

Lake level fluctuations and speciation in rock-dwelling cichlid fish in Lake Tanganyika, East Africa. Grant, P R Evolution on islands 225-240, 1998

Genetic distinction of four haplochromine cichlid fish species in a satellite lake of Lake Victoria, East Africa. Journal of Zoological Systematics and Evolutionary Research 50(1): 51-58, 2012

Pronounced genetic differentiation of small, isolated and fragmented tilapia populations inhabiting the Magadi Soda Lake in Kenya. Hydrobiologia 739(1): 55-71, 2014

A revision of the cichlid fish genus petrochromis from lake tanganyika east africa with description of a new species. Japanese Journal of Ichthyology 30(2): 129-141, 1983

Validation of the periodicity of increment formation in the otoliths of a cichlid fish from Lake Tanganyika, East Africa. Journal of Fish Biology ; 64(5): 1272-1284, 2004

Fluoride levels in water and fish from lake magadi kenya. Hydrobiologia 234(2): 123-127, 1992

Bacteria and Archaea diversity within the hot springs of Lake Magadi and Little Magadi in Kenya. Bmc Microbiology 16(1): 136, 2016

Magadiite and Magadi chert; a critical analysis of the silica sediments in the Lake Magadi Basin, Kenya. Special Publication - Society for Sedimentary Geology 73: 257-273, 2002

Record of seismotectonic events in siliceous cyanobacterial sediments (Magadi cherts), Lake Magadi, Kenya. International Journal of Earth Sciences 89(2): 268-283, 2000

Metagenomic Insights into the Uncultured Diversity and Physiology of Microbes in Four Hypersaline Soda Lake Brines. Frontiers in Microbiology 7: 211, 2016