The single mitochondrion of the kinetoplastid parasite Crithidia fasciculata is a dynamic network

Abstract

MLP) ¶ These authors contributed equally to this work. AbstractMitochondria are central organelles in cellular metabolism. Their structure is highly dynamic, allowing them to adapt to different energy requirements, to be partitioned during cell division, and to maintain functionality. Mitochondrial dynamics, including membrane fusion and fission reactions, are well studied in yeast and mammals but it is not known if these processes are conserved throughout eukaryotic evolution. Kinetoplastid parasites are some of the earliest-diverging eukaryotes to retain a mitochondrion. Each cell has only a single mitochondrial organelle, making them an interesting model for the role of dynamics in controlling mitochondrial architecture. We have investigated the mitochondrial division cycle in the kinetoplastid Crithidia fasciculata. The majority of mitochondrial biogenesis occurs during the G1 phase of the cell cycle, and the mitochondrion is divided symmetrically in a process coincident with cytokinesis.Mitochondrial division was not inhibited by the putative dynamin inhibitor mdivi-1, although mitochondrial membrane potential and cell size were affected. Live cell imaging revealed that the mitochondrion is highly dynamic, with frequent changes in the topology of the branched network. These remodeling reactions include tubule fission, fusion, and sliding, as well as new tubule formation. We hypothesize that the function of this dynamic remodeling is to homogenize mitochondrial contents and to facilitate rapid transport of mitochondria-encoded gene products from the area containing the mitochondrial nucleoid to other parts of the organelle.

Biomimetic nanoporous aerogels from branched aramid nanofibers combining high heat insulation and compressive strength

“…In addition to the high stiffness of the aramid nanofibers, 46 thinner segments of the branches can wrap around the thicker ones, substantially strengthening the contacts that are also taking place in many biological tissues based on nanofibers 47 . At the molecular scale, multiple and reconfigurable hydrogen bonds 48,49 at the junctions provide strong connections between BANFs replicating, in fact, nanoscale junctions known from biology 50,51 . The BANF aerogel obtained has a density of 0.0081 g/cm 3 while its specific compressive strength reaches up to 102 MPa·cm 3 /g, which is much higher than that of other aerogels.…”