TY - JOUR
T1 - O2 binding and CO2 sensitivity in haemoglobins of subterranean African mole rats
AU - Weber, Roy E.
AU - Jarvis, Jennifer U. M.
AU - Fago, Angela
AU - Bennett, Nigel C.
PY - 2017
Y1 - 2017
N2 - Inhabiting deep and sealed subterranean burrows, mole rats exhibit a remarkable suite of specializations, including eusociality (living in colonies with single breeding queens), extraordinary longevity, cancer immunity and poikilothermy, and extreme tolerance of hypoxia and hypercapnia. With little information available on adjustments in haemoglobin (Hb) function that may mitigate the impact of exogenous and endogenous constraints on the uptake and internal transport of O2, we measured haematological characteristics, as well as Hb-O2 binding affinity and sensitivity to pH (Bohr effect), CO2, temperature and 2,3-diphosphoglycerate (DPG, the major allosteric modulator of Hb-O2 affinity in red blood cells) in four social and two solitary species of African mole rats (family Bathyergidae) originating from different biomes and soil types across Central and Southern Africa. We found no consistent patterns in haematocrit (Hct) and blood and red cell DPG and Hb concentrations or in intrinsic Hb-O2 affinity and its sensitivity to pH and DPG that correlate with burrowing, sociality and soil type. However, the results reveal low specific (pH independent) effects of CO2 on Hb-O2 affinity compared with humans that predictably safeguard pulmonary loading under hypoxic and hypercapnic burrow conditions. The O2 binding characteristics are discussed in relation to available information on the primary structure of Hbs from adult and developmental stages of mammals subjected to hypoxia and hypercapnia and the molecular mechanisms underlying functional variation in rodent Hbs.
AB - Inhabiting deep and sealed subterranean burrows, mole rats exhibit a remarkable suite of specializations, including eusociality (living in colonies with single breeding queens), extraordinary longevity, cancer immunity and poikilothermy, and extreme tolerance of hypoxia and hypercapnia. With little information available on adjustments in haemoglobin (Hb) function that may mitigate the impact of exogenous and endogenous constraints on the uptake and internal transport of O2, we measured haematological characteristics, as well as Hb-O2 binding affinity and sensitivity to pH (Bohr effect), CO2, temperature and 2,3-diphosphoglycerate (DPG, the major allosteric modulator of Hb-O2 affinity in red blood cells) in four social and two solitary species of African mole rats (family Bathyergidae) originating from different biomes and soil types across Central and Southern Africa. We found no consistent patterns in haematocrit (Hct) and blood and red cell DPG and Hb concentrations or in intrinsic Hb-O2 affinity and its sensitivity to pH and DPG that correlate with burrowing, sociality and soil type. However, the results reveal low specific (pH independent) effects of CO2 on Hb-O2 affinity compared with humans that predictably safeguard pulmonary loading under hypoxic and hypercapnic burrow conditions. The O2 binding characteristics are discussed in relation to available information on the primary structure of Hbs from adult and developmental stages of mammals subjected to hypoxia and hypercapnia and the molecular mechanisms underlying functional variation in rodent Hbs.
KW - Bohr effect
KW - Carbon dioxide
KW - Hypoxia
KW - Hypercapnia
KW - Oxygen transport
KW - HIGH-ALTITUDE ADAPTATION
KW - N-TERMINAL ACETYLATION
KW - DEER MOUSE HEMOGLOBIN
KW - SPALAX-EHRENBERGI
KW - CRYPTOMYS-HOTTENTOTUS
KW - VERTEBRATE HEMOGLOBINS
KW - OXYGEN-TRANSPORT
KW - CARBON-DIOXIDE
KW - RESPIRATORY PROPERTIES
KW - PHENOTYPIC PLASTICITY
UR - http://www.scopus.com/inward/record.url?scp=85032702487&partnerID=8YFLogxK
U2 - 10.1242/jeb.160457
DO - 10.1242/jeb.160457
M3 - Journal article
C2 - 28851819
SN - 0022-0949
VL - 220
SP - 3939
EP - 3948
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
IS - 21
ER -