Dataset Information

Adaptive evolution of small heat shock protein/alpha B-crystallin promoter activity of the blind subterranean mole rat, Spalax ehrenbergi.

ABSTRACT: Blind mole rats have degenerated subcutaneous eyes that are visually nonfunctional. In this investigation, we have compared the tissue specificity of the small heat shock protein (shsp)/alphaB-crystallin promoter of the mole rat superspecies, Spalax ehrenbergi, with that of the mouse. Earlier experiments showed that mouse shsp/alphaB-crystallin promoter/enhancer activity is high in the lens and moderate in the heart and skeletal muscle of transgenic mice. Here, we show in transgenic mouse experiments using the firefly luciferase reporter gene that, despite relatively few changes in sequence, the mole rat shsp/alphaB-crystallin promoter/enhancer has selectively lost lens activity after 13.5 days of embryogenesis (E13.5). The ratios of mole rat/mouse promoter activity were 0.01 for lens, 1.7 for heart, and 13.6 for skeletal muscle in 8-wk-old transgenic mice. Our data indicate that the shsp/alphaB-crystallin promoter/enhancer has undergone adaptive changes corresponding to the subterranean evolution of the blind mole rat. We speculate that selective pressures on metabolic economy may have contributed to these tissue-specific modifications of promoter/enhancer function during adaptation to life underground.

SUBMITTER: Hough RB

PROVIDER: S-EPMC123035 | biostudies-literature | 2002 Jun

REPOSITORIES: biostudies-literature

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Adaptive evolution of small heat shock protein/alpha B-crystallin promoter activity of the blind subterranean mole rat, Spalax ehrenbergi.

Hough R B RB Avivi A A Davis J J Joel A A Nevo E E Piatigorsky J J

Proceedings of the National Academy of Sciences of the United States of America 20020601 12

Blind mole rats have degenerated subcutaneous eyes that are visually nonfunctional. In this investigation, we have compared the tissue specificity of the small heat shock protein (shsp)/alphaB-crystallin promoter of the mole rat superspecies, Spalax ehrenbergi, with that of the mouse. Earlier experiments showed that mouse shsp/alphaB-crystallin promoter/enhancer activity is high in the lens and moderate in the heart and skeletal muscle of transgenic mice. Here, we show in transgenic mouse experi ...[more]

PMID: 12060761

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Project description:BackgroundConcealing coloration in rodents is well established. However, only a few studies examined how soil color, pelage color, hair-melanin content, and genetics (i.e., the causal chain) synergize to configure it. This study investigates the causal chain of dorsal coloration in Israeli subterranean blind mole rats, Spalax ehrenbergi.MethodsWe examined pelage coloration of 128 adult animals from 11 populations belonging to four species of Spalax ehrenbergi superspecies (Spalax galili, Spalax golani, Spalax carmeli, and Spalax judaei) and the corresponding coloration of soil samples from the collection sites using a digital colorimeter. Additionally, we quantified hair-melanin contents of 67 animals using HPLC and sequenced the MC1R gene in 68 individuals from all four mole rat species.ResultsDue to high variability of soil colors, the correlation between soil and pelage color coordinates was weak and significant only between soil hue and pelage lightness. Multiple stepwise forward regression revealed that soil lightness was significantly associated with all pelage color variables. Pelage color lightness among the four species increased with the higher southward aridity in accordance to Gloger's rule (darker in humid habitats and lighter in arid habitats). Darker and lighter pelage colors are associated with darker basalt and terra rossa, and lighter rendzina soils, respectively. Despite soil lightness varying significantly, pelage lightness and eumelanin converged among populations living in similar soil types. Partial sequencing of the MC1R gene identified three allelic variants, two of which were predominant in northern species (S. galili and S. golani), and the third was exclusive to southern species (S. carmeli and S. judaei), which might have caused the differences found in pheomelanin/eumelanin ratio.Conclusion/significanceDarker dorsal pelage in darker basalt and terra rossa soils in the north and lighter pelage in rendzina and loess soils in the south reflect the combined results of crypsis and thermoregulatory function following Gloger's rule.

Project description:Oxidative metabolism is fine-tuned machinery that combines two tightly coupled fluxes of glucose and glutamine-derived carbons. Hypoxia interrupts the coordination between the metabolism of these two nutrients and leads to a decrease of the system efficacy and may eventually cause cell death. The subterranean blind mole rat, Spalax, is an underexplored, underground, hypoxia-tolerant mammalian group which spends its life under sharply fluctuating oxygen levels. Primary Spalax cells are an exceptional model to study the metabolic strategies that have evolved in mammals inhabiting low-oxygen niches. In this study we explored the metabolic frame of glutamine (Gln) homeostasis in Spalax skin cells under normoxic and hypoxic conditions and their impacts on the metabolism of rat cells. Targeted metabolomics employing liquid chromatography and mass spectrometry (LC-MS) was used to track the fate of heavy glutamine carbons (13C5 Gln) after 24 h under normoxia or hypoxia (1% O2). Our results indicated that large amounts of glutamine-originated carbons were detected as proline (Pro) and hydroxyproline (HPro) in normoxic Spalax cells with a further increase under hypoxia, suggesting a strategy for reduced Gln carbons storage in proteins. The intensity of the flux and the presence of HPro suggests collagen as a candidate protein that is most abundant in animals, and as the primary source of HPro. An increased conversion of αKG to 2 HG that was indicated in hypoxic Spalax cells prevents the degradation of hypoxia-inducible factor 1α (HIF-1α) and, consequently, maintains cytosolic and mitochondrial carbons fluxes that were uncoupled via inhibition of the pyruvate dehydrogenase complex. A strong antioxidant defense in Spalax cells can be attributed, at least in part, to the massive usage of glutamine-derived glutamate for glutathione (GSH) production. The present study uncovers additional strategies that have evolved in this unique mammal to support its hypoxia tolerance, and probably contribute to its cancer resistance, longevity, and healthy aging.

Dataset Information

Adaptive evolution of small heat shock protein/alpha B-crystallin promoter activity of the blind subterranean mole rat, Spalax ehrenbergi.

Publications

Adaptive evolution of small heat shock protein/alpha B-crystallin promoter activity of the blind subterranean mole rat, Spalax ehrenbergi.

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