Mitochondrial Modulation of Apoptosis Induced by Low-dose Radiation in Mouse Testicular Cells

Objective To investigate whether apoptosis induced by low-dose radiation （LDR） is regulated by mitochondrial pathways in testicular cells. Methods Male mice were exposed to whole-body LDR, and changes in mitochondrial function and in expression of apoptotic factors were analyzed in the testicular cells as follows. Total nitric-oxide synthase （T-NOS） and Na＋/K＋ ATPase activities were biochemically assayed. Reactive oxygen species （ROS） and mitochondrial membrane potential （Adjm） were determined by flow cytometry using fluorescent probes. Levels of mRNAs encoding cytochrome c （Cyt c） and apoptosis-inducing factor （AIF） were quantified by real-time reverse-transcription PCR （RT-PCR）. Expression of Cyt c, AIF, caspase-9, and caspase-3 at the protein level was assessed by western blotting and immunohistochemistry. Results LDR induced an increase in T-NOS activity and ROS levels, and a decrease in Na＋/K~ ATPase activity and mitochondrial A^m, in the testicular cells. The intensity of these effects increased with time after irradiation and with dose. The cells showed remarkable swelling and vacuolization of mitochondria, and displayed a time- and dose-dependent increase in the expression of Cyt c, AIF, procaspase-9, and procaspase-3. Activation of the two procaspases was confirmed by detection of the cleaved caspases. The changes in expression of the four apoptotic factors were mostly limited to spermatogonia and spermatocytes. Conclusion LDR can induce testicular cell apoptosis through mitochondrial signaling pathways

Cellular Fatty Acids as Chemical Markers for Differentiation of Acinetobacter baumannii and Acinetobacter calcoaceticus

Objective Gas chromatography （GC） was used to investigate the cellular fatty acid （CFA） composition of 141 Acinetobacter boumannii and 32 A. calcoaceticus isolates from different locations in China and to find chemical markers to differentiate these two closely related bacteria. Methods Whole cell fatty acid methyl esters （FAMEs） were obtained by saponification, methylation, and extraction for GC analysis, followed by a standardized Microbial Identification System （MIS） analysis. Results All A. baumannii and A. calcoaceticus strains contained some major fatty acids, namely, 18：1 co9c, 16：0, Sum In Feature 3, 12：0, 17：1co8c, 3-OH-12：0, 17：0, Sum In Feature 2, 2-OH-12：0, and 18：0 compounds. Although most of the total CFAs are similar between A. baumannii and A. calcoaceticus strains, the ratios of two pairs of CFAs, i.e., Sum In Feature 3/18：1 co9c versus 16：0/18：1 co9c and Sum In Feature 3/18：1 co9c versus unknown 12.484/18：1 co9c fatty acids, could differentiate these two closely related bacteria. A. baumannii could be easily classified into two subgroups by plotting some ratios such as Sum In Feature 3/16：0 versus 17：0 and Sum In Feature 3/2-OH-12：0 versus17：0 fatty acids. Conclusion The ratios of some CFAs could be used as chemical markers to distinguish A. baumannii from A. colcoaceticus.