PubMed · 14789229
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H H RODIN. 1951. Sensitivity to cold.. https://pubmed.ncbi.nlm.nih.gov/14789229/
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During fed-batch cultivation of Escherichia coli K-12, the proteomic response to a temperature downshift from 37 to 20 degrees C was quantitatively monitored and analyzed by using two-dimensional electrophoresis. When the temperature of exponentially growing E. coli K-12 culture was downshifted to 20 degrees C, the synthesis level of 57 intracellular proteins showed significant changes for a prolonged period of time, compared to the fed-batch culture controlled at 37 degrees C. Thus, these proteins are regarded as important stress proteins responsive to cold shock, which were analyzed by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and identified using the E. coli SWISS-2DPAGE database. Most of the identified proteins were shown to be involved in energy metabolism, several cellular molecule biosynthetic pathways and catabolism, cell processes, flagellar biosynthesis and motility, and protein translation and folding. The systematic approach to the monitoring of proteomic responses and the detailed analysis results reported in this article would be useful in understanding the metabolic adaptation to lowered culture temperature and designing efficient fermentation strategies for the production of recombinant proteins and metabolites using E. coli strains.
The aim of this work is to study the irradiation of iron salts in solid state (heptahydrated ferrous sulfate) and in frozen acid solutions. The study is focused on finding their possible use as dosimeters for low temperature irradiations and high doses. The analysis of the samples was made by UV-visible and Mössbauer spectroscopies. The output signal was linear from 0 to 10 MGy for the solid samples, and 0-600 Gy for the frozen solutions. The obtained data is reproducible and easy to handle. For these reasons, heptahydrate iron sulfate is a suitable dosimeter for low temperature and high irradiation doses, in solid state, and in frozen solution.
Exposure to adverse environmental conditions causes oxidative stress in many organisms, leading either to disease and debilitation or to response and tolerance. Mitochondria are a key site of oxidative stress and of cellular response and play important roles in cell survival. We analyzed the response of mitochondria in pea (Pisum sativum) plants to the common stresses associated with drought, cold, and herbicides. These treatments all altered photosynthetic and respiratory rates of pea leaves to various extents, but only herbicides significantly increased lipid peroxidation product accumulation. Mitochondria isolated from the stressed pea plants maintained their electron transport chain activity, but changes were evident in the abundance of uncoupling proteins, non-phosphorylating respiratory pathways, and oxidative modification of lipoic acid moieties on mitochondrial proteins. These data suggest that herbicide treatment placed a severe oxidative stress on mitochondria, whereas chilling and particularly drought were milder stresses. Detailed analysis of the soluble proteome of mitochondria by gel electrophoresis and mass spectrometry revealed differential degradation of key matrix enzymes during treatments with chilling being significantly more damaging than drought. Differential induction of heat shock proteins and specific losses of other proteins illustrated the diversity of response to these stresses at the protein level. Cross-species matching was required for mass spectrometry identification of nine proteins because only a limited number of pea cDNAs have been sequenced, and the full pea genome is not available. Blue-native separation of intact respiratory chain complexes revealed little if any change in response to environmental stresses. Together these data suggest that although many of the molecular events identified by chemical stresses of mitochondria from a range of model eukaryotes are also apparent during environmental stress of plants, their extent and significance can vary substantially.