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Streptomyces platensis je bakterija iz rodu Streptomyces. V rod Streptomyces spadajo nitaste bakterije, ki jih najdemo v prsti. Bakterije Streptomyces uspevajo pri pH 6,5 – 8,0 in v temperaturnem območju med 25 °C in 35 °C. Za S. platensis je značilna proizvodnja zunajceličnih encimov, ki se uporabljajo za industrijske namene. Namen magistrske naloge je bil ugotoviti kako sprememba pH v celični suspenziji S. platensis vpliva na maso celic S. platensis, aktivnost encima transglutaminaza in koncentracijo skupnih proteinov v bakterijski suspenziji S. platensis. Celično suspenzijo S. platensis smo inkubirali v inkubacijskem stresalniku 8 dni pri temperaturi 28 °C in ob rahlem stalnem stresanju. Naredili smo 3 izvedbe, pri katerih smo v procesu inkubiranja celične suspenzije S. platensis spreminjali pogoje pH. Pri vseh 3 izvedbah inkubiranja celične suspenzije S. platensis v odvisnosti od inkubacijskega časa smo ugotovili, da medtem ko se je pH celične suspenzije zniževal, so koncentracija proteinov, aktivnost transglutaminaze in prirast suhe mase celic naraščale. Po treh različnih izvedbah se je izkazalo, da je za gojenje celične suspenzije S. platensis najugodnejši začetni pH 6,7 in inkubiranje pri temperaturi 28 °C ob rahlem stresanju ter brez dodatnega spreminjanja pH. Spreminjanje oziroma uravnavanje pH na začetku procesa ali med celotnim procesom inkubiranja celične suspenzije S. platensis ni ugodno za uspešno gojenje bakterije S. platensis, saj se celoten proces pospeši in bakterije hitreje propadejo. Streptomyces platensis is bacteria from the genus of Streptomyces. Part of the genus Streptomyces are thread-like bacteria, which are found in the soil. Bacteria Streptomyces thrive at pH 6,5 – 8,0 and in the temperature range between 25 and 35 °C. S. platensis are known for the production of extracellular enzymes, which are being used for industrial purposes. The purpose of this master thesis was to find out how changes of pH in the cellular suspension of S. platensis affect the mass of cells of S. platensis, how they affect the activity of transglutaminase enzyme and how they affect the concentration of total proteins in bacterial suspension. We have incubated cellular suspension of S. platensis in an incubator shaker for 8 days at a temperature of 28 °C and constant mild shaking. We have performed three trials, during which we have been changing pH conditions in the process of incubation of cellular suspension of S. platensis. At all three trials of incubation of the cellular suspension of S. platensis we have discovered in respect to the incubating time that while the pH of the cellular suspension was dropping, the concentration of proteins, the activity of transglutaminase and the growth of the dry mass of cells were rising. After three different trials it has turned out, that for the growth of the cellular suspension of S. platensis it is ideal to have a starting value of pH to be 6,7 and for incubating to occur at 28 °C with constant mild shaking and without additional altering of the pH value. Changing the value of pH either at the start or during the process of incubation of the cellular suspension of S. platensis is not beneficial for the successful growth of the bacteria S. platensis as the entire process is being accelerated and bacteria decay faster.

International audience; The scanning transmission ion microscope (STIM) has been used to determine the intracellular mass of human cultured cells. A 4He+ microbeam of 2.0 MeV energy was chosen to obtain enhanced ion-energy-loss sensitivity through the micron-thick freeze-dried cells. Local sample mass calculation, based on energy-loss conversion by use of appropriate matrix stopping powers, was performed by use of dedicated software. The method was validated with epoxy resin sections and polymer foil as analogues of biological samples in the range of (intra) cellular thickness, 150 to 3000 nm. STIM analysis resulted in less than 5% error in mass determination. 4He+ energy-loss micro-spectrometry was performed on freezedried human ovarian cancer cells, the mean areal mass obtained was 120 µg cm–2 (200 µg cm–2 in the nucleus and 250 µg cm–2 in nucleoli). This method is particularly useful for mass normalization of X-ray fluorescence yields resulting from particle-induced X-ray emission microanalysis (micro-PIXE). When performed successively these two ion-beam micro-analytical methods enable the mapping of true element concentrations within single cells.

Clinical studies have demonstrated that circulating tumor cells (CTCs) are present in the blood of cancer patients with known metastatic disease across the major types of epithelial malignancies. Recent studies have shown that the concentration of CTCs in the blood is prognostic of overall survival in breast, prostate, colorectal and non-small cell lung cancer. This study characterizes CTCs identified using the high-definition (HD)-CTC assay in an ovarian cancer patient with stage IIIC disease. We characterized the physical properties of 31 HD-CTCs and 50 normal leukocytes from a single blood draw taken just prior to the initial debulking surgery. We utilized a non-interferometric quantitative phase microscopy technique using brightfield imagery to measure cellular dry mass. Next we used a quantitative differential interference contrast microscopy technique to measure cellular volume. These techniques were combined to determine cellular dry mass density. We found that HD-CTCs were more massive than leukocytes: 33.6 ± 3.2 pg (HD-CTC) compared to 18.7 ± 0.6 pg (leukocytes), p < 0.001; had greater volumes: 518.3 ± 24.5 fL (HD-CTC) compared to 230.9 ± 78.5 fL (leukocyte), p