Methods to Study the Biogenesis of Mitoribosomal Proteins in Yeast

The biogenesis of mitoribosomes is an intricate process that relies on the coordinated synthesis of nuclear-encoded mitoribosomal proteins (MRPs) in the cytosol, their translocation across mitochondrial membranes, the transcription of rRNA molecules in the matrix as well as the assembly of the roughly 80 different constituents of the mitoribosome. Numerous chaperones, translocases, processing peptidases, and assembly factors of the cytosol and in mitochondria support this complex reaction. The budding yeast Saccharomyces cerevisiae served as a powerful model organism to unravel the different steps by which MRPs are imported into mitochondria, fold into their native structures, and assemble into functional ribosomes.In this chapter, we provide established protocols to study these different processes experimentally. In particular, we describe methods to purify mitochondria from yeast cells, to import radiolabeled MRPs into isolated mitochondria, and to elucidate the assembly reaction of MRPs by immunoprecipitation. These protocols and the list of dos and don'ts will enable beginners and experienced scientists to study the import and assembly of MRPs.

Preparation of "Functional" Mitochondria: A Challenging Business

As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during in vitro handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.

Toxicity of Manganese Titanate on Rat Vital Organ Mitochondria

The TiO2, which is a main material in the field of photocatalytic reactions, includes rutile and anatase phase. Titanium dioxide has possessed notice due to its promising applications in the environmental photocatalytic degradation of pollutants of organic compound in waste water and utilization of solar energy. The nanosized manganese titanate (pyrophanite) MnTiO3 was collected by oxidation of Mn(OH)2 with TiO2 powder in cetyltrimethylammonium bromide (CTAB) micelle solutions and the calcinations of the produced powders. Therefore, it was decided to determine the Mechanistic mitochondria toxicity of nanoparticles towards liver, kidney, heart, and brain via new and reliable methods. Our results showed that nanoparticles induced mitochondria dysfunction via an increase in ROS production and membrane potential collapse, correlated to cytochrome c release. Also, increased disturbance in oxidative phosphorylation was also shown by the decrease in ATP. Recent studies have suggested that nanoparticles leading to cytosolic release of lysosomal content, and ultimately apoptosis. This study suggests that mitochondrial oxidative stress and impairment of oxidative phosphorylation in vital organ Mitochondria may play a key role in manganese titanate toxicity.