Factors Affecting Mitochondrial Development

Both the time of analysis and experimental design may affect the results. An explanation for the increase in adenylates under the conditions of our experiment is still needed. Since both ATP alone and total adenylate concentrations have increased, it does not appear that a shift in phosphorylation can account for the increases. The decrease in photosynthesis and increase in adenylates occur during the same time period and both factors return to normal after 21 hr. From previous research we know that the photosynthetic levels of ozonated pinto bean foliage decrease immediately after ozone exposure even when symptoms do not develop ( ). This does not hold true for the adenylate or respiration responses. Therefore, it appears that the ozone-initiated increase in adenylates is not correlated directly to the photosynthetic response. The increase in respiration persists when adenylate content and photosynthetic rates have returned to normal. Impaired mitochondrial function appears to be a secondary response more closely related to symptom development. 

Leber hereditary optic neuropathy (LHON) is the most common mitochondrial disease and the first linked to maternal inheritance through a mutation in the mtDNA. LHON is characterized by bilateral subacute loss of central vision caused by focal degeneration of the retinal ganglion cell layer and of the optic nerve. After initial symptoms, both eyes are usually affected within 6 months. Approximately 50% to 60% of males and only 8% to 32% of females who possess the mtDNA mutation will actually develop this optic neuropathy. Nuclear-encoded factors that affect mtDNA expression, mtDNA products, or mitochondrial metabolism may modify the phenotypic expression of LHON. Genetic coimseling in LHON is complicated in that the amount of mutant mtDNA transmitted by heteroplasmic females cannot be predicted, and testing cannot predict which individuals will develop visual symptoms. ... 

---