The Role of Mitochondrial Electron Transport in Tumorigenesis and Metastasis
The role of electron transport in metastasis (formation of secondary tumors) and tumorigenesis (the creation of cancer cells) is poorly understood. This review collects evidence to suggest that there exists a bioenergetic landscape (bell curve) for malignancy in tumors, which must optimise glycolysis versus oxidative phosphorylation (OXPHOS) as a means of energy production. Glycolysis is an anaerobic respiration pathway, which produces less energy than mitochondrial oxidative phosphorylation, but produces many reactive oxygen species and activates malignancy pathways. On the other hand, OXPHOS correlates with more differentiated tumor cells but also anchorage independent cell growth (anoikis resistance) and metastatic potential. This highlights the need for a cancer cell to balance OXPHOS and glycolytic energy production.
Wednesday, 30 October 2013
Tuesday, 22 October 2013
Coastal Physical Features in West Africa Shape the Genetic Structure of the Bonga Shad
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793960/
In this paper the genetic diversity of the fish E. Fimbriata that lives along the west coast of Africa is studied. In total 480 fish are sampled and their nuclear DNA is extracted. They then studied the variability in seven loci using an EPIC (exon-primed, intron-crossing polymerase chain reaction) method and used MCMC methods to find the number of parental populations.
The results they found were somewhat different from earlier studies on these fish in the same regions. In an earlier study, they had looked at variability in mtDNA. This study using mtDNA found three genetically different groups: 1) a northern group extending from Mauritania to Guinea, 2) a central group distributed from Côte d’Ivoire to Cameroon, and 3) a southern group with populations extending from Gabon to Angola. Also, they found a correlation between geographical distance and genetic differentation (the larger the geographical distance, the more genetic differences).
The study in this paper found genetic differentiation at finer scale, so within the three groups found in the mtDNA study, they found genetically distinct samples whereas these samples appeared genetically the same using the mtDNA markers. Also, this paper found no correlation between the geographical distance and genetic differentation. Sam suggested that this might be because maybe only the male fish move away from where they are born. If the females of a certain population tend not to migrate then the mtDNA of that population will not mix with that of a different population and so you expect to see more difference in mtDNA as the geographical distances become larger. The nuclear DNA of different populations then does mix because of the migrating males.
In this paper the genetic diversity of the fish E. Fimbriata that lives along the west coast of Africa is studied. In total 480 fish are sampled and their nuclear DNA is extracted. They then studied the variability in seven loci using an EPIC (exon-primed, intron-crossing polymerase chain reaction) method and used MCMC methods to find the number of parental populations.
The results they found were somewhat different from earlier studies on these fish in the same regions. In an earlier study, they had looked at variability in mtDNA. This study using mtDNA found three genetically different groups: 1) a northern group extending from Mauritania to Guinea, 2) a central group distributed from Côte d’Ivoire to Cameroon, and 3) a southern group with populations extending from Gabon to Angola. Also, they found a correlation between geographical distance and genetic differentation (the larger the geographical distance, the more genetic differences).
The study in this paper found genetic differentiation at finer scale, so within the three groups found in the mtDNA study, they found genetically distinct samples whereas these samples appeared genetically the same using the mtDNA markers. Also, this paper found no correlation between the geographical distance and genetic differentation. Sam suggested that this might be because maybe only the male fish move away from where they are born. If the females of a certain population tend not to migrate then the mtDNA of that population will not mix with that of a different population and so you expect to see more difference in mtDNA as the geographical distances become larger. The nuclear DNA of different populations then does mix because of the migrating males.
The Role of Dynamin-Related Protein 1, a Mediator of Mitochondrial Fission, in Apoptosis
The Role of Dynamin-Related Protein 1, a Mediator of Mitochondrial Fission, in Apoptosis
Apoptosis is a form of programmed cell-death, where a cell decides to kill itself in a controlled manner following a stress signal. A number of physiological changes occur inside the cell during apoptosis, one of which is the fragmentation of the mitochondrial network. Drp1 is an important protein involved in mitochondrial fission and can be seen to translocate from the cytosol to the outer membrane of mitochondria before fission. This paper finds that, in the COS-7 immortalized monkey kidney cell line, blocking the function of Drp1 prevents: mitochondrial fragmentation; the loss of mitochondrial membrane potential; the leaking of cytochrome c into the cytoplasm; and crucially, can block apoptosis itself.
Apoptosis is a form of programmed cell-death, where a cell decides to kill itself in a controlled manner following a stress signal. A number of physiological changes occur inside the cell during apoptosis, one of which is the fragmentation of the mitochondrial network. Drp1 is an important protein involved in mitochondrial fission and can be seen to translocate from the cytosol to the outer membrane of mitochondria before fission. This paper finds that, in the COS-7 immortalized monkey kidney cell line, blocking the function of Drp1 prevents: mitochondrial fragmentation; the loss of mitochondrial membrane potential; the leaking of cytochrome c into the cytoplasm; and crucially, can block apoptosis itself.
Tuesday, 15 October 2013
Evolution of mitochondrial gene content: gene loss and transfer to the nucleus
Evolution of mitochondrial gene content: gene loss and transfer to the nucleus
adams2003mitochondrialhttp://www.ncbi.nlm.nih.gov/pubmed/14615181
Eukaryotic relationships with mitochondria are largely accepted to be the result of an endosymbiotic event between an ancestral eukaryote and a "proto-mitochondrion". Since this event, genes encoding functional aspects of the mitochondrion have been transferred to the eukaryotic nucleus -- for reasons that are unclear but may be related to increased genetic control and/or stability. This review describes current understanding of this process, including the different extents to which it has occurred in different lineages across life. Rickettsia looks perhaps a bit like a precursor mitochondrion; Reclinomonas americana has retained more (67) mitochondrial protein genes than other organisms; animals seem to have stabilised at 13 protein and 22 tRNA genes.
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