Browsing by Subject "Live cell"
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Item Open Access Differential effects of nitrogen and sulfur deprivation on growth and biodiesel feedstock production of Chlamydomonas reinhardtii(2012) Cakmak, T.; Angun P.; Demiray, Y.E.; Ozkan, A.D.; Elibol, Z.; Tekinay, T.Biodiesel production from microalgae is a promising approach for energy production; however, high cost of its process limits the use of microalgal biodiesel. Increasing the levels of triacylglycerol (TAG) levels, which is used as a biodiesel feedstock, in microalgae has been achieved mainly by nitrogen starvation. In this study, we compared effects of sulfur (S) and nitrogen (N) starvation on TAG accumulation and related parameters in wild-type Chlamydomonas reinhardtii CC-124 mt(-) and CC-125 mt(+) strains. Cell division was interrupted, protein and chlorophyll levels rapidly declined while cell volume, total neutral lipid, carotenoid, and carbohydrate content increased in response to nutrient starvation. Cytosolic lipid droplets in microalgae under nutrient starvation were monitored by three-dimensional confocal laser imaging of live cells. Infrared spectroscopy results showed that relative TAG, oligosaccharide and polysaccharide levels increased rapidly in response to nutrient starvation, especially S starvation. Both strains exhibited similar levels of regulation responses under mineral deficiency, however, the degree of their responses were significantly different, which emphasizes the importance of mating type on the physiological response of algae. Neutral lipid, TAG, and carbohydrate levels reached their peak values following 4 days of N or S starvation. Therefore, 4 days of N or S starvation provides an excellent way of increasing TAG content. Although increase in these parameters was followed by a subsequent decline in N-starved strains after 4 days, this decline was not observed in S-starved ones, which shows that S starvation is a better way of increasing TAG production of C. reinhardtii than N starvation. © 2012 Wiley Periodicals, Inc.Item Open Access Gauss tabanlı modelleme kullanarak canlı hücre görüntülerinin öğreticisiz bölütlenmesi(2011-04) Arslan, Salim; Durmaz, İrem; Çetin-Atalay, Rengül; Gündüz-Demir, ÇiğdemThe first step of targeted cancer drug development is to screen and determine drug candidates by in vitro measuring the effectiveness of the drugs. The tests developed for this purpose can be time consuming due to their procedures and cannot be conducted in every laboratory due to the required hardwares. On the other hand, an image-based screening test has a potential to be less time consuming since it can directly be carried out on the live cell images and to be more extensively used because of the availability of its required equipments and their relatively less expensive cost. With such an image-based test, it is possible to quantify the cell death by finding cellular regions and comparing it against the control group. In this work, we propose a new method that automatically locates the cellular regions by the unsupervised segmentation of live cell images. This method relies on approximately locating cellular regions and the background with gradient-based thresholding and morphological operators and then finding the final boundaries by modeling the gradient of these regions with Gaussians. Working on the images of different cell lines captured with different magnifications, our experiments show that the proposed method leads to promising results. © 2011 IEEE.