Oxygen and carbon dioxide fluctuations in burrows of subterranean blind mole rats indicate tolerance to hypoxic-hypercapnic stresses

Imad Shams, Aaron Avivi, Eviatar Nevo

Research output: Contribution to journalArticlepeer-review

Abstract

The composition of oxygen (O2), carbon dioxide (CO2), and soil humidity in the underground burrows from three species of the Israeli subterranean mole rat Spalax ehrenbergi superspecies were studied in their natural habitat. Two geographically close populations of each species from contrasting soil types were probed. Maximal CO2 levels (6.1%) and minimal O2 levels (7.2%) were recorded in northern Israel in the breeding mounds of S. carmeli in a flooded, poor drained field of heavy clay soil with very high volumetric water content. The patterns of gas fluctuations during the measurement period among the different Spalax species studied were similar. The more significant differentiation in gas levels was not among species, but between neighboring populations inhabiting heavy soils or light soils: O2 was lower and CO2 was higher in the heavy soils (clay and basaltic) compared to the relatively light soils (terra rossa and rendzina). The extreme values of gas concentration, which occurred during the rainy season, seemed to fluctuate with partial flooding of the tunnels, animal digging activity, and over-crowded breeding mounds inhabited by a nursing female and her offspring. The gas composition and soil water content in neighboring sites with different soil types indicated large differences in the levels of hypoxic-hypercapnic stress in different populations of the same species. A growing number of genes associated with hypoxic stress have been shown to exhibit structural and functional differences between the subterranean Spalax and the above-ground rat (Rattus norvegicus), probably reflecting the molecular adaptations that Spalax went through during 40 million years of evolution to survive efficiently in the severe fluctuations in gas composition in the underground habitat.

Original languageEnglish
Pages (from-to)376-382
Number of pages7
JournalComparative Biochemistry and Physiology - A Molecular and Integrative Physiology
Volume142
Issue number3
DOIs
StatePublished - Nov 2005

Bibliographical note

Funding Information:
This work was supported by European Union grant QLRT-2001-01548 (to A. A, and E. N.) and the Ancell-Teicher Research Foundation for Genetics and Molecular Evolution. We thank Ms. Alma Joel for technical assistance. All experiments in this study comply with the current laws in Israel.

Keywords

  • Carbon dioxide
  • Evolution
  • Gas in burrows
  • Hypercapnia
  • Hypoxia
  • Oxygen
  • Subterranean Spalax
  • Underground habitat

ASJC Scopus subject areas

  • Molecular Biology
  • Biochemistry
  • Physiology

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