Mitochondrial degeneration

Rat myocardium ultrastructurally differed more intensely between 3 and 6 than between 18 and 24 months of age (Welt etal. 2000). Lipid drops and mitochondrial degeneration were more prominent in the older rats. Ageing-related alterations were limited to interfibrillar mitochondria, while subsar-colemmal mitochondria remained unaffected (Fannin et al. 1999). Ageing decreased the rate of oxidative phosphorylation in interfibrillar mitochondria, including when stimulated by electron donors spe-... 

Physiology of immobilised C. fusiformis during long-term semicontinuous cultivation was studied by Kfen et al. (1987b). The immobilised cells maintained the alkaloid production for 770 days. The cells underwent profound morphological changes—vacuolisation, mitochondrial degeneration. The beads remained mechanically stable for the whole time. 

PD affects approximately one million Americans (1% of people over 60 years of age). The average age of onset is 60 years of age, and PD is fairly uncommon in those under age 40. The etiology of PD is unknown, but genetic predisposition, environmental factors, or combinations of these have been proposed to explain why nerve cells in the substantia nigra deteriorate. About 15% of patients with PD have a first-degree relative with the disease. The pathogenesis of cell death (neuron degeneration) may be due to oxidative stress, mitochondrial... 

Friedreich s ataxia is caused by an intronic triplet repeat expansion. Friedreich s ataxia is an autosomal recessive disorder characterized by progressive ataxia, nystagmus, distal sensory polyneuropathy and corticospinal tract degeneration. It is caused by an unstable expanded GAA repeat in intron 1 of the frataxin gene on chromosome 9ql3. This diminishes expression of frataxin, a mitochondrial iron-storage protein that participates in free radical metabolism [71]. 

Geeene, j. C., et ah. Mitochondrial pathology and apoptotic muscle degeneration in Drosophila parkin mutants. Proc Natl Acad Sci USA, 2003, 100(7), 4078-83. 

Degeneration Mitochondrial permeability transition with membrane depolarization, cytochrome c release, and mitochondrial swelling and fragmentation activation of caspases and cell death pathway, endonuclease fragmentation of DNA with chromatin and nuclear condensation phosphatidyserine exposure on cell surface cytoskeletal disruption with membrane blebbing... 

The answer is B. LHON often has an onset in early adulthood. It is a mitochondrial disorder usually resulting from a mutation in one of the proteins of the electron transport chain, particularly complex I, encoded by the mitochondrial genome so there is no chance that the patient can pass the disorder to his children (see Chapter 13). Cataracts would have been detected as opacity in the lenses, and glaucoma would have been identified by an elevated intraocular pressure. Macular degeneration is also associated with central vision loss but is found mainly in patients over age 65. 

Kearns-Sayre syndrome [17] A multisystem disorder characterized by the invariant triad onset before age 20 years, PEO, pigmentary retinal degeneration plus at least one of the following complete heart block, cerebrospinal fluid protein above 100 mg/dl, cerebellar ataxia. Large-scale heteroplasmic mitochondrial DNA deletions are frequently detected in skeletal muscle (rarely in other tissues). 

The outcome of, or perhaps the support for, the endosymbiont transferring its genes to the nucleus was the evolution of new machinery in the eukaryotic cell to send the nuclear-encoded proteins back to the degenerate endosymbiont to allow the latter to function. Moreover, it is of note that the large majority of extant mitochondrial proteins are not of endosymbiotic or a-proteobacterial origin. These proteins have either been recruited... 

Surveys of mitochondrial presequences showed that, though quite common, these above motifs are not found in all of them, and that the primary sequence for the cleavage site is quite degenerate. 

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