Selim Çetiner

Oxidative Stress Is a Mediator for Increased Lipid Accumulation in a Newly Isolated Dunaliella salina Strain

Green algae offer sustainable, clean and eco-friendly energy resource. However, production efficiency needs to be improved. Increasing cellular lipid levels by nitrogen depletion is one of the most studied strategies. Despite this, the underlying physiological and biochemical mechanisms of this response have not been well defined. Algae species adapted to hypersaline conditions can be cultivated in salty waters which are not useful for agriculture or consumption. Due to their inherent extreme cultivation conditions, use of hypersaline algae species is better suited for avoiding culture contamination issues. In this study, we identified a new halophilic Dunaliella salina strain by using 18S ribosomal RNA gene sequencing. We found that growth and biomass productivities of this strain were directly related to nitrogen levels, as the highest biomass concentration under 0.05 mM or 5 mM nitrogen regimes were 495 mg/l and 1409 mg/l, respectively. We also confirmed that nitrogen limitation increased cellular lipid content up to 35% under 0.05 mM nitrogen concentration. In order to gain insight into the mechanisms of this phenomenon, we applied fluorometric, flow cytometric and spectrophotometric methods to measure oxidative stress and enzymatic defence mechanisms. Under nitrogen depleted cultivation conditions, we observed increased lipid peroxidation by measuring an important oxidative stress marker, malondialdehyde and enhanced activation of catalase, ascorbate peroxidase and superoxide dismutase antioxidant enzymes. These observations indicated that oxidative stress is accompanied by increased lipid content in the green alga. In addition, we also showed that at optimum cultivation conditions, inducing oxidative stress by application of exogenous H2O2 leads to increased cellular lipid content up to 44% when compared with non-treated control groups. Our results support that oxidative stress and lipid overproduction are linked. Importantly, these results also suggest that oxidative stress mediates lipid accumulation. Understanding such relationships may provide guidance for efficient production of algal biodiesels.

Gelling agents and culture vessels affect in vitro multiplication of banana plantlets

Agar is the most commonly used gelling agent in media for plant tissue culture. Because of the high price of tissue-culture-grade agar, attempts have been made to identify suitable alternatives. The type of culture vessel and lid also affects the gaseous composition inside the vessel as well as light penetration. In turn, the vessel affects growth parameters, such as shoot elongation, proliferation and fresh weight, as well as hyperhydric degradation processes. We examined the effects of different culture vessels, including commercial glass jars, magenta boxes, and disposable containers, as well as different gelling agents (agar-agar, Agargel, Phytagel, and plant agar) on the micropropagation of Dwarf Cavendish bananas in an effort to find a combination that yields large numbers of high-quality seedlings. The different culture vessels did not significantly affect seedling culture success. The medium significantly affected shoot weight. Phytagel resulted in the highest shoot weight (overall mean = 2.4 g), while agar, Agargel and plant agar resulted in 1.7, 2.2 and 2.2 g, respectively. Disposable container/Phytagel and Magenta/Agargel combinations yielded the highest shoot weights (2.9 and 3.0 g, respectively). Mean shoot length increased progressively with subculture (four subcultures were made). The highest mean shoot length was obtained with Phytagel and Agargel media (6.4 and 6.3 cm, respectively). Shoot number was significantly affected by medium only at subculture 4. Overall, the highest mean shoot length was obtained with the Magenta/Agargel combination (8.5 cm). Phytagel and plant agar gave higher mean shoot number than agar and Agargel (2.1, 2.1 and 1.7 and 1.9, respectively). The costs of the media and of the culture vessels need to be taken into account for final choice of the banana shoot culture system.

A histological analysis of regeneration in watermelon

The optimization of regeneration protocol for different genotypes increases the yield in transformation studies. Cotyledon explants of watermelon [Citrullus lanatus (Thunb) Matsum & Nakai] cv Crimson Sweet were cultured on MS medium containing combinations of benzyl adenine (BA) (0, 5, 10, 20 µM) and indole-3-acetic acid (IAA) (0, 0.5, 5 µM). Maximum shoot growth and subsequent rooting from explants on regeneration medium were obtained from the media containing 10 µM BA + 0.5 µM IAA and 20 µM BA (75 and 78%) by direct organogenesis, respectively. Histological analysis showed that cell division was observed in the epidermal and subepidermal layers. Protuberant structures were observed in tissues between 7 and 12 days in culture. Meristematic structures were observed after 12days in culture which later developed into buds.

Challenges facing European agriculture and possible biotechnological solutions.

Abstract Agriculture faces many challenges to maximize yields while it is required to operate in an environmentally sustainable manner. In the present study, we analyze the major agricultural challenges identified by European farmers (primarily related to biotic stresses) in 13 countries, namely Belgium, Bulgaria, the Czech Republic, France, Germany, Hungary, Italy, Portugal, Romania, Spain, Sweden, UK and Turkey, for nine major crops (barley, beet, grapevine, maize, oilseed rape, olive, potato, sunflower and wheat). Most biotic stresses (BSs) are related to fungi or insects, but viral diseases, bacterial diseases and even parasitic plants have an important impact on yield and harvest quality. We examine how these challenges have been addressed by public and private research sectors, using either conventional breeding, marker-assisted selection, transgenesis, cisgenesis, RNAi technology or mutagenesis. Both national surveys and scientific literature analysis followed by text mining were employed to evaluate genetic engineering (GE) and non-GE approaches. This is the first report of text mining of the scientific literature on plant breeding and agricultural biotechnology research. For the nine major crops in Europe, 128 BS challenges were identified with 40% of these addressed neither in the scientific literature nor in recent European public research programs. We found evidence that the private sector was addressing only a few of these “neglected” challenges. Consequently, there are considerable gaps between farmer’s needs and current breeding and biotechnology research. We also provide evidence that the current political situation in certain European countries is an impediment to GE research in order to address these agricultural challenges in the future. This study should also contribute to the decision-making process on future pertinent international consortia to fill the identified research gaps.

Cytotoxic effect of extract from Dunaliella salina against SH-SY5Y neuroblastoma cells.

Cytotoxic effects of essential oils extracted from Dunaliella salina on SH-SY5Y human neuroblastoma cells were investigated in this study. GC-MS analysis was used for determination of the composition of essential oils found in Dunaliella salina extract. All experimented concentrations of Dunaliella salina extract on SH-SY5Y human neuroblastoma cells were significantly more cytotoxic than the tested concentrations of the extract on ECV304 human endothelial cells used as a control. Fifthy compounds were detected in GC-MS analysis of the extract, and five major compounds were predominantly found as follows: octadecanoic acid, methyl ester (27.43%); hexadecanoic acid, methyl ester (Cas) methyl palmitate (24.82%); 9,12,15-octadecatrienoic acid, ethyl ester, (Z,Z,Z)- (7.39%); octadecanoic acid (5.03%), pentadecanoic acid (3.60%). The cytotoxic activity of Dunaliella salina extract on SH-SY5Y human neuroblastoma cells might be due to high concentrations of octadecanoic acid and hexadecanoic acid. Furthermore, results indicate that the extract demonstrates some proliferative effect on ECV304 cells in a dose-dependent manner between 0.25 and 5 μg/ml. These results suggest that Dunaliella salina may have anticancer potential against human neuroblastoma cells.

Screening of new antileukemic agents from essential oils of algae extracts and computational modeling of their interactions with intracellular signaling nodes

Microalgae are very rich in bioactive compounds, minerals, polysaccharides, poly-unsaturated fatty acids and vitamins, and these rich constituents make microalgae an important resource for the discovery of new bioactive compounds with applications in biotechnology. In this study, we studied the antileukemic activity of several chosen microalgae species at the molecular level and assessed their potential for drug development. Here we identified Stichococcus bacillaris, Phaeodactylum tricornutum, Microcystis aeruginosa and Nannochloropsis oculata microalgae extracts with possible antileukemic agent potentials. Specifically we studied the effects of these extracts on intracellular signal nodes and apoptotic pathways. We characterized the composition of essential oils of these fifteen different algae extracts using gas chromatography-mass spectrometry (GC-MS). Finally, to identify potential molecular targets causing the phenotypic changes in leukemic cell lines, we docked a selected group of these essential oils to several key intracellular proteins. According to results of rank score algorithm, five of these essential oils analyzed might be considered as in silico plausible candidates to be used as antileukemic agents.

In vitro plant regeneration derived from leaf and stem explants of endemic Thermopsis turcica

This plant tissue study of micropropagation identifies the selective medium saving for rapid propagation in cultivated Thermopsis turcica, an endangered germplasm of the family Fabaceae. The aim is to obtain the optimum growth medium of T. turcica by enabling the in vitro propagation of this endemic. In this study, the leaves and stems of T. turcica were cultured on a Murashige and Skoog’s medium supplemented with various concentrations (0.5, 1.0 and 2.0 mg L−1 1-Naphthaleneacetic acid) of auxin and (0.2 and 0.5 mg L−1 Zeatin) (1.0 and 2.0 mg L−1 Benzylaminopurine) of cytokinins. Previous research focused on the regeneration from the seed of T. turcica Eber population; we concentrated upon the regeneration of different plant parts (leaf and stem) of T. turcica Aksehir population. In addition, according to the literature on T. turcica that to date the effects of Zeatin on the regeneration has not been performed. The most promising regeneration and growth were obtained from leaf explants cultured on the media with 2.0 mg L−1 1-Naphthaleneacetic acid and 0.5 mg L−1Zeatin (93.3%). The regenerated plantles were rooted on the media containing 2.0 mg L−1 Indole-3-butyric acid. Rooted plantlets were transplanted into potting of sterilized soil. The present study reports on the sufficient in vitro regeneration protocol through organogenesis in T. turcica. The findings presented here have implications for in vitro protection and use of this endemic endangered species in further biotechnological research.

Rediscovery of historical Vitis vinifera varieties from the South Anatolia region by using amplified fragment length polymorphism and simple sequence repeat DNA fingerprinting methods

Anatolia played an important role in the diversification and spread of economically important Vitis vinifera varieties. Although several biodiversity studies have been conducted with local cultivars in different regions of Anatolia, our aim is to gain a better knowledge on the biodiversity of endangered historical V. vinifera varieties in the northern Adana region of southern Anatolia, particularly those potentially displaying viticulture characteristics. We also demonstrate the genetic relatedness in a selected subset of widely cultivated and commercialized V. vinifera collection cultivars, which were obtained from the National Grapevine Germplasm located at the Institute of Viticulture, Turkey. In the present study, microsatellites were used in narrowing the sample size from 72 accessions down to a collection of 27 varieties. Amplified fragment length polymorphisms were then employed to determine genetic relatedness among this collection and local V. vinifera cultivars. The unweighted pair group method with arithmetic mean cluster and principal component analyses revealed that Saimbeyli local cultivars form a distinct group, which is distantly related to a selected subset of V. vinifera collection varieties from all over Turkey. To our knowledge, this is the first study conducted with these cultivars. Further preservation and use of these potential viticultural varieties will be helpful to avoid genetic erosion and to promote continued agriculture in the region.

The Effects of Different Combinations and Varying Concentrations of Growth Regulators on the Regeneration of Selected Turkish Cultivars of Melon

Cucurbits are an economically important family of plants. The majority of the vegetable production in Turkey, for example, derives from the species beloning to the family Cucurbitaceae. Despite the importance of cucurbits among vegetable crops worldwide, the development of genomic tools in these species has been rather limited. Although melon production has been improved by conventional plant breeding methods, output is still insufficient. One useful technique in overcoming such problems in melon is functional genomics’ studies, and the other one is abiotic stress resistance and improved fruit quality has been gene transfer via Agrobacterium tumefaciens mediated transformation. The availability of an optimized plant regeneration system is crucial for genetic transformation techniques as well as obtaining an entire plant. Although Hasanbey and Cinikiz in Turkey, for example, are important commercial melon cultivars used in the breeding programs and molecular biology of fruit ripening and genetic mapping of melons, there is no study to date on the regeneration of these cultivars.

Floral development in Thermopsis turcica, an unusual multicarpellate papilionoid legume

The vast majority of the species of family Leguminosae have an apocarpous monomerous gynoecium. However, only a few taxa regularly produce multicarpellate gynoecia. The only known species of papilionoid legumes which has both a typical “flag blossom” and more than one carpel is Thermopsis turcica (tribe Thermopsideae). We studied the floral ontogeny of T. turcica with special reference to its gynoecium initiation and development. Flowers arise in simple terminal racemes in a helical order and are subtended by bracts. Bracteoles are initiated but then suppressed. Sepals appear more or less simultaneously. Then, petals emerge and remain retarded in development until later stages. The gynoecium usually includes three carpels with an abaxial one initiating first and two adaxial carpels arising later and developing somewhat asynchronously. The abaxial carpel appears concomitant with the outer stamens and is always oriented with its cleft toward the adaxial side, while the adaxial carpels face each other with their clefts and have them slightly turned to the adaxial side. Rarely uni-, bi- or tetracarpellate flowers arise. Seed productivity of T. turcica is on approximately the same level as in unicarpellate species of Thermopsis hence supporting the fact that the multicarpellate habit is adaptive or at least not harmful in this species.