Browsing by Subject "triacylglycerol"

Now showing 1 - 5 of 5

Open Access
Asymmetric dimethylarginine concentrations are elevated in women with gestational diabetes
(2010) Akturk, M.; Altinova, A.; Mert I.; Dincel, A.; Sargin, A.; Buyukkagnici, U.; Arslan, M.; Danisman, N.
As shown in the previous studies, asymmetric dimethylarginine (ADMA) is related to endothelial dysfunction, whereas high-sensitive C-reactive protein (hCRP) is the marker of inflammation. In our study, we investigated ADMA, hCRP, and homocysteine concentrations in women with gestational diabetes mellitus (GDM) and normal glucose tolerance (NGT) during late pregnancy. Fifty-four women with GDM and 69 women with NGT between 32 and 39 weeks of gestation were included in this study. ADMA, hCRP, homocysteine, lipid parameters, glycated hemoglobin (HbA1c) levels, insulin, and homeostasis model assessment for insulin resistance (HOMA-IR) were measured. The plasma ADMA concentrations were significantly higher in GDM patients than in NGT subjects (P = 0.03) and the hCRP levels were also significantly increased in GDM group when compared with those in the NGT group (P = 0.008). However, plasma homocysteine levels did not differ between the groups (P = 0.4), while HOMA-IR, insulin, and triglyceride levels were higher in the GDM group than in the NGT group (P = 0.001, 0.002, and 0.02, respectively). The ADMA concentrations in the third trimester were positively correlated with the glucose levels the 50-g glucose challenge test (GCT) during 24-28 weeks in the whole group (r = 0.21, P = 0.02). Our results demonstrate that ADMA and hCRP are elevated in women with GDM during late pregnancy. Further studies are needed to clarify the significance and the underlying mechanisms of the elevated ADMA and hCRP levels in women with GDM. © 2010 Springer Science+Business Media, LLC.
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.
Open Access
Nitrogen and sulfur deprivation differentiate lipid accumulation targets of chlamydomonas reinhardtii
(2012) Cakmak, T.; Angun P.; Ozkan, A.D.; Cakmak, Z.; Olmez, T.T.; Tekinay, T.
Nitrogen (N) and sulfur (S) have inter-related and distinct impacts on microalgal metabolism; with N starvation having previously been reported to induce elevated levels of the biodiesel feedstock material triacylglycerol (TAG), while S deprivation is extensively studied for its effects on biohydrogen production in microalgae.1,2 We have previously demonstrated that N- and S-starved cells of Chlamydomonas reinhardtii display different metabolic trends, suggesting that different response mechanisms exist to compensate for the absence of those two elements.3 We used C. reinhardtii CC-124 mt(-) and CC-125 mt(+) strains to test possible metabolic changes related to TAG accumulation in response to N and S deprivation, considering that gamete differentiation in this organism is mainly regulated by N.4 Our findings contribute to the understanding of microalgal response to element deprivation and potential use of element deprivation for biodiesel feedstock production using microalgae, but much remains to be elucidated on the precise contribution of both N and S starvation on microalgal metabolism. © 2012 Landes Bioscience.
Open Access
Sustainable production of biological materials for food and agricultural applications
(2013) Angün, Pınar
Microalgae are planet’s primary biological CO2/O2 converters. Today, microalgae are used in a wide range of areas; such as waste-water treatment, production of protein-rich food and feed additives, high value added compounds, carotenoids and biofuels. Nowadays, there is an increasing need for renewable energy sources, specifically biofuels due to the depletion of limited fossil fuels. For this purpose, microalgae have emerged as a promising third-generation biofuel source and present possible solution to energy problems. In the first part of this study, the aim was to determine and compare the effects of sulfur (S) and nitrogen (N) starvation on triacylglycerol (TAG) accumulation, which is used as a biodiesel feedstock, and related parameters in wild type Chlamydomonas reinhardtii CC-124 mt(-) and CC-125 mt(+) strains to improve the biodiesel production capacity. 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 deprivation. Microalgae under nutrient starvation were monitored by threedimensional confocal laser imaging of live cells and by transmission electron microscopy (TEM). FTIR measurement results showed that relative TAG, oligosaccharide and polysaccharide levels increased rapidly in response to nutrient starvation, especially in S starvation. Neutral lipid, TAG and carbohydrate levels reached their peak values following four days of N or S starvation. However considering that four days of S deprivation leads to an increased total biovolume and stimulates more lipid and carbohydrate accumulation, S starvation seems to be a better way of stimulating biodiesel feedstock production of wild type C. reinhardtii compared to N starvation. Carotenoids are lipid soluble compounds that play important role in acting provitamin-A, color materials and antioxidants that protect cells and tissues from free radicals and singlet oxygen. In nature, approximately 700 carotenoids have been isolated and characterized. However, there are some disadvantages of natural carotenoids such as being unsustainable and non-economic. Microalgae could serve sustainable solution to the production of natural carotenoids. The aim of the second part of this study was to identify new sources of natural, sustainable and inexpensive carotenoids and antioxidants from 12 isolated microalgae by determining their total carotenoid contents and antioxidant activity. These 12 microalgae were isolated from different water sources in Turkey. Results of this study demonstrated that among 12 microalgae strains, STA2, STA3 and STA9 contained substantial amounts of carotenoids in their metabolism and these carotenoids extracts showed strong antioxidant activity. With the ease of cultivation and high growth rate, these three microalgae strains have potential to use as natural and sustainable carotenoids for food, dietary supplement, pharmaceutical, cosmetic, feed and other related applications.
Open Access
Visfatin concentration is decreased in women with gestational diabetes mellitus in the third trimester
(2008) Akturk, M.; Altinova, A.E.; Mert I.; Buyukkagnici, U.; Sargin, A.; Arslan, M.; Danisman, N.
Our aim is to investigate visfatin concentration and its relationship to glycated hemoglobin (HbA1c), insulin resistance, lipid parameters, and neonatal birth weight in women with gestational diabetes mellitus (GDM). In our study group, there were 47 women with GDM and 31 women with normal glucose tolerance (NGT) between 33-39 weeks of gestation. Plasma visfatin levels were significantly decreased in pregnant women with GDM compared to those with NGT (p=0.001). Homeostasis model assessment-insulin resistance (HOMA-IR) levels were higher in the GDM group than in the NGT group (p=0.006). In all subjects, plasma visfatin levels were negatively correlated with HOMA-IR, post-prandial blood glucose, triglycerides, and VLDL cholesterol (p<0.05). We did not observe any statistically significant correlation between the plasma visfatin levels and the selected parameters in the GDM group, but in the NGT group plasma visfatin levels were negatively correlated with HOMA-IR (r=-0.36, p=0.04). There was no correlation between visfatin concentrations and fetal birth weight in either group (p>0.05). By regression analysis, having GDM was found to be the only significant determinant (t=3.5, p=0.001) of visfatin concentration (R=0.39, r2=0.15). We conclude that women with GDM have significantly decreased visfatin concentrations in the third trimester. Future studies are required to establish the exact role of visfatin in the pathogenesis of GDM. ©2008, Editrice Kurtis.