ABSTRACT
To explore the adaptive mechanisms of plateau zokor (Myospalax baileyi) to the enduring digging activity in the hypoxic environment and of plateau pika (Ochotona curzoniae) to the sprint running activity, the functional differences of malate-aspartate shuttle system (MA) in liver of plateau zokor and plateau pika were studied. The ratio of liver weight to body weight, the parameters of mitochondria in hepatocyte and the contents of lactic acid in serum were measured; the open reading frame of cytoplasmic malate dehydrogenase (MDH1), mitochondrial malate dehydrogenase (MDH2), and the partial sequence of aspartate glutamate carrier (AGC) and oxoglutarate malate carrier (OMC) genes were cloned and sequenced; MDH1, MDH2, AGC and OMC mRNA levels were determined by real-time PCR; the specific activities of MDH1 and MDH2 in liver of plateau zokor and plateau pika were measured using enzymatic methods. The results showed that, (1) the ratio of liver weight to body weight, the number and the specific surface of mitochondria in hepatocyte of plateau zokor were markedly higher than those of plateau pika (P < 0.01 or P < 0.05), but the content of lactic acid in serum of plateau pika was significantly higher than that of plateau zokor (P < 0.01); (2) MDH1 and MDH2 mRNA levels as well as their enzymatic activities in liver of plateau zokor were significantly higher than those of plateau pika (P < 0.01 or 0.05), AGC mRNA level of the zokor was significantly higher than that of the pika (P < 0.01), while no difference was found at OMC mRNA level between them (P > 0.05); (3) mRNA level and enzymatic activity of MDH1 was significantly lower than those of MDH2 in the pika liver (P < 0.01), MDH1 mRNA level of plateau zokor was markedly higher than that of MDH2 (P < 0.01), but the activities had no difference between MDH1 and MDH2 in liver of the zokor (P > 0.05). These results indicate that the plateau zokor obtains ATP in the enduring digging activity by enhancing the function of MA, while plateau pika gets glycogen for their sprint running activity by increasing the process of gluconeogenesis. As a result, plateau pika converts the lactic acid quickly produced in their skeletal muscle by anaerobic glycolysis and reduces dependence on the oxygen.
Subject(s)
Animals , Adaptation, Physiological , Physiology , Adenosine Triphosphate , Metabolism , Altitude , Aspartic Acid , Metabolism , Cloning, Molecular , L-Lactate Dehydrogenase , Metabolism , Lactic Acid , Blood , Lagomorpha , Classification , Physiology , Liver , Physiology , Malate Dehydrogenase , Genetics , Metabolism , Malates , Metabolism , Membrane Transport Proteins , Genetics , Metabolism , RNA, Messenger , Genetics , MetabolismABSTRACT
Vascular endothelial growth factor (VEGF) plays an important role in tissues angiogenesis. The adaptation of animals to hypoxic environment is relative to the microvessel density (MVD) in tissues. To further explore the adaptation mechanisms of plateau zokor (Myospalax baileyi) to the hypoxic-hypercapnic burrows, the VEGF mRNA and the MVD in cerebral tissues of the plateau zokor were studied. Total RNA was isolated from liver, and VEGF cDNA was obtained by RT-PCR, then the VEGF cDNA was cloned and sequenced. The coding sequence of plateau pika (Ochotona curzniae), rat (Rattus norvegicus) and mouse (Mus musculus) VEGF cDNA are obtained from GenBank, and the nucleotide and amino acid sequence homology of plateau zokor VEGF cDNA coding sequence with that of plateau pika, rat and mouse were analyzed and compared by using of bioinformatics software. The VEGF mRNA was detected by real-time PCR, and the MVDs in cerebral tissues of the plateau zokor, plateau pika and Sprague-Dawley (SD) rat were measured by immunohistochemical staining. The results showed that the open reading frame of the plateau zokor VEGF was 645 bp, and the coding sequence of the plateau zokor VEGF cDNA shared 92.1%, 93.6% and 93.8% nucleotide sequence homology to that of the plateau pika, rat and mouse, respectively. The deduced amino acid sequence of the plateau zokor VEGF cDNA was composed of 188 amino acids and the amino acids from 1 to 26 were signal peptide sequence. The plateau zokor VEGF188 was 90.2%, 94.9% and 94.4% homologous to that of plateau pika, rat and mouse. The level of VEGF mRNA in brain of the plateau zokor was significantly lower than that of SD rat, but there was no obvious difference in VEGF mRNA level between plateau zokor and plateau pika. The MVD in brain of the plateau zokor was markedly higher than that of plateau pika and SD rat. In conclusion, plateau zokor enhances its adaptation to the hypoxic environment by increasing the MVD. The level of VEGF mRNA in the brain of plateau zokor is lower than that of SD rat, which may be as a result of inhibition by the higher concentration of carbon dioxide in the burrow.
Subject(s)
Animals , Rats , Adaptation, Physiological , Physiology , Amino Acid Sequence , Arvicolinae , Physiology , Base Sequence , Brain , Metabolism , Hypoxia , Microvessels , Molecular Sequence Data , RNA, Messenger , Genetics , Metabolism , Rats, Sprague-Dawley , Species Specificity , Vascular Endothelial Growth Factor A , Genetics , MetabolismABSTRACT
<p><b>OBJECTIVE</b>To study the potential aging effect on workers exposed to acrylonitrile (ACN).</p><p><b>METHODS</b>The deletion rates of mitochondrial DNA (mtDNA) in peripheral blood nucleate cells of 47 exposed workers and 47 non-exposed workers (as control), as well as 12 old people and 12 young people were measured with polymerase chain reaction (PCR).</p><p><b>RESULTS</b>The positive rates of mtDNA deletion in peripheral blood nucleate cells were 17.02% in the workers exposed to ACN and 25.00% in group of old people. However, the mtDNA deletion was not detected in the control group and young people.</p><p><b>CONCLUSIONS</b>ACN could induce mtDNA deletion in peripheral blood nucleate cells of the exposed workers. There may be a potential molecular effect of occupational ACN exposure on workers' aging.</p>