Fen Edebiyat Fakültesi / Faculty of Letters and Science

Permanent URI for this collectionhttps://hdl.handle.net/11727/1396

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20202

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Author: search.filters.author.Kayihan, CeyhunSubject: search.filters.subject.Oxidative stress

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    Higher nisin yield is reached with glutathione and pyruvate compared with heme in Lactococcus lactis N8
    (2020) Ersoy, Zeynep Girgin; Kayihan, Ceyhun; Tunca, Sedef; 0000-0003-1684-4147; 31898248; Q-4515-2016
    There are different studies that aim to enhance the production of nisin by Lactococcus lactis since its chemical synthesis is not possible. In this study, glutathione (GSH) and pyruvate, which are known to reduce the oxidative stress of cells, have been shown to trigger the production of nisin at both transcriptional and translational levels in L. lactis cells grown under aerobic condition. Presence of GSH and pyruvate caused more nisin yield than the heme-supplemented medium. Moreover, the expression of genes that encode stress-related enzymes were apparently upregulated in the presence of GSH and pyruvate. It can be concluded that GSH and pyruvate contribute to the defense system of L. lactis cells and so that higher biomass was obtained which in turn enhance nisin production. Antioxidant effect of GSH and pyruvate was known; however, their stimulating effect on nisin production was shown for the first time in this study.
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    The role of microRNAs in recovery rates of Arabidopsis thaliana after short term cryo-storage
    (2020) Ekinci, Muhammad Hamit; Kayihan, Doga Selin; Kayihan, Ceyhun; Ciftci, Yelda Ozden; 0000-0003-1684-4147; Q-4515-2016
    Key message The alteration of expression levels of cold- and oxidative stress-induced genes related-miRNAs play a crucial role in development of successful cryopreservation protocols. Cryopreservation is a safe and cost-effective long-term storage technique which helps to conserve plant germplasm in liquid nitrogen (LN). However, up to now, the molecular regulatory mechanisms that effect survival after cryopreservation have not been satisfactorily elucidated in plants. Thus, the aim of the study concerned to reveal out microRNA (miRNA)-based post-transcriptional regulations during different stages of cryopreservation in 48-h and 72-h in vitro germinated Arabidopsis thaliana since miRNAs not only regulate gene expression in developmental process of plants, but also control transcription in stress conditions by post-transcriptional degradation. Among the screened 10 miRNAs and their selected target genes, differential expression levels were detected in two tested germination time according to exposure of cryopreservation stages, as 6 miRNAs (miR393, miR397, miR398, miR159, miR169 and miR172) showed a mixed pattern in 48-h germinated seedlings while 6 miRNAs (miR397, miR398, miR159, miR169, miR172 and miR408) were significantly down-regulated in OD (Osmoprotection-Dehydration) and LD (Liquid nitrogen-Dilution) samples in comparison to control in 72-h germinated ones. The most striking expression change was obtained in miR393 as it was up-regulated 15-fold in LN treated 48-h seedlings while relatively lower amount induction (twofold) was recorded in cryopreserved 72-h seedlings. The concominant down-regulation of its target TIR1 and HOS1 expression and up-regulation of CBF1 and CBF3 and their downstream genes (COR15 and COR47) were also observed in cryopreserved 48-h germinated seedlings. Thus, the alteration of expression levels of cold-induced genes related-miRNAs plays a crucial role for successful cryopreservation.