PubMed · 14817259
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
E ARNOLD, G WERNER. 1950. [Separate spirometry in phthisiologic practice].. https://pubmed.ncbi.nlm.nih.gov/14817259/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Explore the source record for details and available documents.
Opposing fission and fusion events maintain the yeast mitochondrial network. Six proteins regulate these membrane dynamics during mitotic growth-Dnm1p, Mdv1p, and Fis1p mediate fission; Fzo1p, Mgm1p, and Ugo1p mediate fusion. Previous studies established that mitochondria fragment and rejoin at distinct stages during meiosis and sporulation, suggesting that mitochondrial fission and fusion are required during this process. Here we report that strains defective for mitochondrial fission alone, or both fission and fusion, complete meiosis and sporulation. However, visualization of mitochondria in sporulating cultures reveals morphological defects associated with the loss of fusion and/or fission proteins. Specifically, mitochondria collapse to one side of the cell and fail to fragment during presporulation. In addition, mitochondria are not inherited equally by newly formed spores, and mitochondrial DNA nucleoid segregation defects give rise to spores lacking nucleoids. This nucleoid inheritance defect is correlated with an increase in petite spore colonies. Unexpectedly, mitochondria fragment in mature tetrads lacking fission proteins. The latter finding suggests either that novel fission machinery operates during sporulation or that mechanical forces generate the mitochondrial fragments observed in mature spores. These results provide evidence of fitness defects caused by fission mutations and reveal new phenotypes associated with fission and fusion mutations.
Plant mitochondria were previously shown to comprise respiratory supercomplexes containing cytochrome c reductase (complex III) and NADH dehydrogenase (complex I) of I(1)III(2) and I(2)III(4) composition. Here we report the discovery of additional supercomplexes in potato (Solanum tuberosum) mitochondria, which are of lower abundance and include cytochrome c oxidase (complex IV). Highly active mitochondria were isolated from potato tubers and stems, solubilized by digitonin, and subsequently analyzed by Blue-native (BN) polyacrylamide gel electrophoresis (PAGE). Visualization of supercomplexes by in-gel activity stains for complex IV revealed five novel supercomplexes of 850, 1,200, 1,850, 2,200, and 3,000 kD in potato tuber mitochondria. These supercomplexes have III(2)IV(1), III(2)IV(2), I(1)III(2)IV(1), I(1)III(2)IV(2), and I(1)III(2)IV(4) compositions as shown by two-dimensional BN/sodium dodecyl sulfate (SDS)-PAGE and BN/BN-PAGE in combination with activity stains for cytochrome c oxidase. Potato stem mitochondria include similar supercomplexes, but complex IV is partially present in a smaller version that lacks the Cox6b protein and possibly other subunits. However, in mitochondria from potato tubers and stems, about 90% of complex IV was present in monomeric form. It was suggested that the I(1)III(2)IV(4) supercomplex represents a basic unit for respiration in mammalian mitochondria termed respirasome. Respirasomes also occur in potato mitochondria but were of low concentrations under all conditions applied. We speculate that respirasomes are more abundant under in vivo conditions.