No abstract

In a previous paper (Henry and Friedman, 1937) we confirmed the works of Dyrmont (1886) and Virtanen and Pulkki (1933) which showed that little difference exists in the water content of vegetative cells and spores of a given species. of bacteria. These results indicated that the commonly accepted idea that a low water content in the spore form is responsible for the observed heat resistance of this type of cell was not justified.Virtanen and Pulkki advanced the theory that the enzymes present in the bacterial spore were in an inactive or resistant form. We suggested that the resistance, whether it concerned the enzymes or the bacterial protoplasm proper, might be due to differences in the percentage of bound water in the two types of cells. This suggestion was based on the report of Newton and Martin (1930) which shows that the resistance of certain plants to drought and freezing is, in part, due to their relatively high percentages of bound water.The present paper is a report of the relative amount of bound water found in the vegetative cells and spores of Bacillus mycoides, Bacillus megatherium and Bacillus subtilis, as determined by the cryoscopic method (Newton and Gortner, 1922). This method was chosen because of its relative simplicity and because of the similarity of our problem to that of Skovholt and Bailey (1935) when they determined the bound water in flour. The procedure is based on the assumption that bound water does not alter the freezing point of a given solution of sucrose, and therefore if a weighed quantity of bacterial cells with a known water

This investigation was supported in part by the State of Washington fund for medical and biological research. 2 Portion of a dissertation presented by the senior author as partial fulfillment of the requirements for the degree Doctor of Philosophy at the University of Washington.

Mitochondria are dynamic organelles that undergo rounds of fission and fusion and exhibit a wide range of morphologies that contribute to the regulation of different signaling pathways and various cellular functions. It is important to understand the differences between mitochondrial structure in health and disease so that therapies can be developed to maintain the homeostatic balance of mitochondrial dynamics. Mitochondrial disorders are multisystemic and characterized by complex and variable clinical pathologies. The dynamics of mitochondria in mitochondrial disorders is thus worthy of investigation. Therefore, in this study, we performed a comprehensive analysis of mitochondrial dynamics in ten patient-derived fibroblasts containing different mutations and deletions associated with various mitochondrial disorders. Our results suggest that the most predominant morphological signature for mitochondria in the diseased state is fragmentation, with eight out of the ten cell lines exhibiting characteristics consistent with fragmented mitochondria. To our knowledge, this is the first comprehensive study that quantifies mitochondrial dynamics in cell lines with a wide array of developmental and mitochondrial disorders. A more thorough analysis of the correlations between mitochondrial dynamics, mitochondrial genome perturbations, and bioenergetic dysfunction will aid in identifying unique morphological signatures of various mitochondrial disorders in the future.

The explanation most usually offered for the resistance of bacterial spores to temperatures which will destroy the vegetative cells of the same species is based on the fact that the water content of protein materials determines the coagulation temperature. From a survey of the literature on this subject it would appear that the statements made by the authors of bacteriological texts that bacterial spores contain from 10 to 15 per cent water are based on speculation. It is true that such a difference in the water content of vegetative and spore forms of a bacterial species would help to explain the proven difference in heat resistance between these two types of cells. It is equally true, however, that the only record, which we have been able to discover, of an actual determination of the water content of bacterial spores made prior to 1933 (Dyrmont (1886)) reports 85 per cent water in the spores of Bacillus anthracis. More recent work by Virtanen