Small, beautiful and essential

Article Abstract:

Mammalian (including human) cells contain small subcellular structures (organelles) known as mitochondria, which are responsible for metabolic processes that require oxygen (aerobic). Mitochondria are inherited exclusively from the mother and contain their own DNA (mtDNA), which contains the genetic information necessary to control their replication. Recently a number of hereditary diseases that are passed along maternal lines have been associated with specific mtDNA defects. These discoveries have, in some instances, been able to explain diseases that were heretofore problematic. Among the pathologies found to be due to mitochondrial DNA defects are Leber's hereditary optic neuropathy, which produces blindness, and encephalomyopathy, a form of epilepsy that is also associated with muscle deterioration. Recent research has concentrated attention on the replication of mtDNA, which is a cyclic molecule and appears to have the ability of repairing spontaneous breaks or mutations at a rate that is 10-12 times faster than nuclear DNA, although the true rate of mutation is probably much higher as well. When mutation occur in normal somatic cells changes are not as noticeable as with embryonic cells. This model suggests that tissues with high metabolic requirements such as muscle and neurological tissues are most affected by mutation. It is also hypothesized that some late-onset diseases associated with aging may be the result of mutations in mitochondrial DNA that accumulate over an entire lifetime. If specific mitochondrial defects (i.e. particular proteins and enzymes) can be linked to a disease and isolated, the possibility of treatment with cofactors and drug agents is highly likely.

Genetic aspects, Neuromuscular diseases

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Mitochondria and male disease

Article Abstract:

Males are more susceptible to certain mitochondrial diseases and mutations as compared to females. The maternally inherited Leber's hereditary optic neuropathy affects males more seriously and also has an earlier age of onset in males. Inherited mitochondrial diseases and somatic mitochondrial DNA are related to reduced sperm motility and poor male fertility. The detrimental effects of the increased equilibrium frequency of germline mitochondrial mutations depend on their correlated fitness effects when in females. The causes of male-female asymmetry in the mitochondrial diseases are discussed.

Diseases, Mutation (Biology), Mutation, Males

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New frog family from India reveals an ancient biogeographical link with the Seychelles

Article Abstract:

Research reports of a discovery of a burrowing frog from India, which is designated as the sister taxon of Sooglossidae based on mitochondrial and nuclear DNA analyses. Molecular clock data indicate that both Sooglossidae and Neobatrachia split very early from the crown-group Neobatrachia. The new frog is recognized as a new family.

Belgium, India, Comparative analysis, Identification and classification, Frogs, Phylogeny, Species, Species (Biology), Biogeomorphology

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