Mitochondria nucleic acids

Imaglng/Labeling Applications Bacteria dideoxynucleotides lysosomes mitochondria nucleic acids protein-2 (MRP2, ABCC2) protein-5 (MRP5, ABCC5)13... 

Imaging/Labeling Applications Bacteria cells hairs hepatocytes malaria infected cells, mitochondria nucleic acids P-glycoprotein " sperms ... 

Imaging/Labeiing Appiications mitochondria " nucleic acids ... 

Not all the cellular DNA is in the nucleus some is found in the mitochondria. In addition, mitochondria contain RNA as well as several enzymes used for protein synthesis. Interestingly, mitochond-rial RNA and DNA bear a closer resemblance to the nucleic acid of bacterial cells than they do to animal cells. For example, the rather small DNA molecule of the mitochondrion is circular and does not form nucleosomes. Its information is contained in approximately 16,500 nucleotides that func-tion in the synthesis of two ribosomal and 22 transfer RNAs (tRNAs). In addition, mitochondrial DNA codes for the synthesis of 13 proteins, all components of the respiratory chain and the oxidative phosphorylation system. Still, mitochondrial DNA does not contain sufficient information for the synthesis of all mitochondrial proteins most are coded by nuclear genes. Most mitochondrial proteins are synthesized in the cytosol from nuclear-derived messenger RNAs (mRNAs) and then transported into the mito-chondria, where they contribute to both the structural and the functional elements of this organelle. Because mitochondria are inherited cytoplasmically, an individual does not necessarily receive mitochondrial nucleic acid equally from each parent. In fact, mito-chondria are inherited maternally. 

Fig. 4. In situ hybridization technique. Part of an erythroid precursor cell infected with the human parvovirus B19 and probed for viral DNA. The BI9 nucleic acid is located within the centra electron lucent area of the nucleus (N) and also at nuclear pores (arrowheads). Ch, chromatin M, mitochondrion. A three-step detection protocol was used (see ref. 5 for details). Sheep antidigoxigenin followed by rabbit antisheep Ig and then goat antirabbit Ig conjugated to 10-nm gold. Bar is 0.5 pm.

Another consequence of the failure of electrons to move completely through the ETC is the increased release of reactive oxygen species (ROS) such as superoxide anion (02 ) in the mitochondrion. Such ROS are produced as oxygen molecules react with electrons at the CoQ or RC I stage. The superoxide and other ROS derived from it (H202 and OH ) cause damage to nearby proteins, membranes, and nucleic acids. 

In 1968, my graduate student Charles Walsh and I addressed the following question What are the pyrimidine sources for nucleic acid synthesis by Plasmodium lophurae We found the parasite synthesized pyrimidines de novo (Walsh and Sherman, 1968b). The evidence for a de novo synthesis was the presence of the key enzymes, thymidylate synthetase and oroti-dine-5-monophosphate pyrophosphorylase, as well as the demonstration of the incorporation of 14C-bicarbonate into cytosine, uracil and thymine. Finding a de novo pathway for the synthesis of pyrimidines by the malaria parasite would, in the next three decades, provide a biochemical basis for the mechanism of action of anti-folate anti-malarials as well as contributing to an understanding of the unique properties of the malaria parasite mitochondrion. 

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