In Silico and Cellular Differences Related to the Cell Division Process between the A and B Races of the Colonial Microalga Botryococcus braunii

Botryococcus braunii produce liquid hydrocarbons able to be processed into combustion engine fuels. Depending on the growing conditions, the cell doubling time can be up to 6 days or more, which is a slow growth rate in comparison with other microalgae. Few studies have analyzed the cell cycle of B. braunii. We did a bioinformatic comparison between the protein sequences for retinoblastoma and cyclin-dependent kinases from the A (Yamanaka) and B (Showa) races, with those sequences from other algae and Arabidopsis thaliana. Differences in the number of cyclin-dependent kinases and potential retinoblastoma phosphorylation sites between the A and B races were found. Some cyclin-dependent kinases from both races seemed to be phylogenetically more similar to A. thaliana than to other microalgae. Microscopic observations were done using several staining procedures. Race A colonies, but not race B, showed some multinucleated cells without chlorophyll. An active mitochondrial net was detected in those multinucleated cells, as well as being defined in polyphosphate bodies. These observations suggest differences in the cell division processes between the A and B races of B. braunii.

Molecular and atomic analysis of uranium complexes formed by three eco-types of Acidithiobacillus ferrooxidans

A combination of EXAFS, transmission electron microscopy and energy-dispersive X-ray was used to conduct a molecular and atomic analysis of the uranium complexes formed by Acidithiobacillus ferrooxidans. The results demonstrate that this bacterium accumulates uranium as phosphate compounds. We suggest that at toxic levels when the uranium enters the bacterial cells, A. ferrooxidans can detoxify and efflux this metal by a process in which its polyphosphate bodies are involved.

A STEM-EDX Study of the Sequestration of Heavy Metal in Different Cell Components by Pseudomonas Aeruginosa

Cells of Pseudomonas aeruginosa were exposed to six different heavy metals, Al, Cd, Cu, Mn, Pb, Zn, exposure was done at the same concentrations of 20 ppm, except for the Cd which was done at 5 ppm. The cells were then analyzed using the STEM mode of a transmission electron microscope in conjunction with a PGT IMIX energy dispersive xray spectrometer. The data was then analyzed using a bulk sample analysis program (ZAF method) in standardless mode (w/w). We analyzed the cell wall the cytoplasm and polyphosphate bodies. Approximately 20 cells were analyzed per treatment and averages of the elements present were calculated. The cells of Pseudomonas aeruginosa were grown in nutrient broth and then embedded in Epon according to Luft's procedure. Quantitative analysis of the three different parts of the cell revealed that in cells exposed to Al, the wall contained on average 0(55%), C(20%) P( 8.0%) K(10%) Cl(2%) S(5.0%),Al(2.0%), the cytoplasm contained on average, 0(53%) C(20%) P(5.0%) Ca(4.0%) K(12%) Cl(4.0%) Al(2.0%).

Quantitative Analysis of Metal Sequestering in Different Cell Components of Gloeocapsa alpicola in the Overplus Phase

The elemental composition of polyphosphate bodies (PPB's) and other components of the cell have previously been determined by using energy dispersive X-ray spectrometers(EDX). In this present study we perform a quantitative analysis of normally grown cells and cells that were grown in the overplus phenomenon.Cells of Gloeocapsa alpicola were grown in modified Fitzgerald's media and harvested after a logarithmic growth phase of 14 days. The overplus cells were grown, as has been previously described. The cells were exposed to 20ppm of Al, Cd, Cu, Mn, Ni, Pb, and Zn, as well as a control, for one hour. The cells were then air dried on formvar coated grids or fixed and embedded in EPON according to Luft's procedure.For Xn-ay analysis cells were first located using the TEM mode, and then the microscope was switched to the STEM mode. Analyses of cell components were carried out using the spot mode (75Kv).