Sperm-specific Lactate Dehydrogenase Is Expressed In Somatic Tissues Of Plateau Pika

Plateau pika (Ochotona curzniae) is a hypoxia and low temperature tolerantrodents living at3000–5000m above sea level on Qinghai-Tibet Plateau. Ourprevious study found that LDH isoenzymes showed six bands in the somatic tissues offemale and male plateau pikas, and the LDH isoenzymes expession patterns in thesomatic tissues were same as that in testis. We suggested that LDH-C4express insomatic tissues of plateau pika.To test this hypothesis, we cloned and sequenced Ldh-a, Ldh-b and Ldh-c insomatic tissues of plateau pika by RT-PCR; determined Ldh-a, Ldh-b and Ldh-cmRNA levels by Real time PCR; purified His-tagged LDH-C4protein by prokaryoticexpression system, and located site of somatic tissues LDH-C4in the LDHisoenzymes by native PAGE stained for LDH activity correlated with thermostabilityof LDH isoenzymes.Our results indicated that1. the open reading frame of the plateau pika Ldh-awas999bp, the coding sequence of the plateau pika Ldh-a shared87.89%，88.19%，85.69%，86.29%and88.99%nucleotide sequence homology to that of the cow,human, SD rat, rabbit and mice, respectively; open reading frame of the plateau pikaLdh-b was1005bp, the coding sequence shared88.46%，90.15%，86.67%and86.47%nucleotide sequence homology to that of the cow, human, SD rat and mice,respectively; Ldh-c mRNA was transcribed in heart, liver, lung, kidney, brain, skeletalmuscle, and was identical to that Ldh-c of plateau pika testis; plateau pika Ldh-c ORFshares74%and68%nucleotide sequence homology to that of Ldh-a and Ldh-b ofplateau pika, respectively.2. Expression levels of Ldh-a, Ldh-b decreasedsignificantly (P<0.01) in the piak heart, and expression levels of Ldh-c decreasedinsignificantly (P>0.05) at elevation of4200m than that of3200m. Expression levelsof Ldh-a, Ldh-b decreased insignificantly (P>0.05) in the piak liver, and expressionlevels of Ldh-c decreased significantly (P<0.01) at elevation of4200m than that of3200m. Expression levels of Ldh-a decreased significantly (P<0.05) in the piak lung,and expression levels of Ldh-b, Ldh-c decreased insignificantly (P>0.05) at elevationof4200m than that of3200m; Expression levels of Ldh-a increased insignificantly(P>0.05), expression levels of Ldh-b decreased insignificantly (P>0.05), andExpression levels of Ldh-c decreased significantly (P<0.01) at elevation of4200m than that of3200m in plateau pika kidney. Expression levels of Ldh-a, Ldh-bdecreased significantly (P<0.05and P<0.01, respectively), and expression levels ofLdh-c decreased insignificantly (P>0.05) at elevation of4200m than that of3200min plateau pika brain. Expression levels of Ldh-a decreased insignificantly (P>0.05),and expression levels of Ldh-b, Ldh-c decreased significantly (P<0.05and P<0.01,respectively) at elevation of4200m than that of3200m in plateau pika skeletalmuscle. Expression levels of Ldh-a, Ldh-b and Ldh-c decreased insignificantly(P>0.05) in the piak testis at elevation of4200m than that of3200m.3. Prokaryoticexpression system for expressing LDHC protein was successfully constructed, and wehave purified active LDH-C4of plateau piak.4. The third band from cathode to anodein LDH isoenzymes was LDH-C4in somatic tissues of plateau pika by native PAGEstained for LDH activity correlated with thermostability of LDH isoenzymes. TheLDH-C4enzyme is expressed in somatic tissues of plateau pika and may be involvedin the mechanism for hypoxia adaptation.