Yusuf Menemen

Induction of triacylglycerol production in Chlamydomonas reinhardtii: Comparative analysis of different element regimes

In this study, impacts of different element absence (nitrogen, sulfur, phosphorus and magnesium) and supplementation (nitrogen and zinc) on element uptake and triacylglycerol production was followed in wild type Chlamydomonas reinhardtii CC-124 strain. Macro- and microelement composition of C. reinhardtii greatly differed under element regimes studied. In particular, heavy metal quotas of the microalgae increased strikingly under zinc supplementation. Growth was suppressed, cell biovolume, carbohydrate, total neutral lipid and triacylglycerol levels increased when microalgae were incubated under these element regimes. Most of the intracellular space was occupied by lipid bodies under all nutrient starvations, as observed by confocal microscopy and transmission electron micrographs. Results suggest that sulfur, magnesium and phosphorus deprivations are superior to nitrogen deprivation for the induction triacylglycerol production in C. reinhardtii. On the other hand, FAME profiles of the nitrogen, sulfur and phosphorus deprived cells were found to meet the requirements of international standards for biodiesel.

A taxonomic revision of the genus Pastinaca L. (Umbelliferae)

A taxonomic revision of the genus Pastinaca L. was carried out with respect to fruitmacro- and micro-morphology, anatomy, palynology, and phytochemistry. The study covers the world distribution of the genus, confined to Europe and Asia, except for Pastinaca sativa L. subsp. sativa (parsnip) cultivated all over the world. Pollen studies showed that the pollen of the genus could be described as cerebroid. Three flavonoid compounds were detected in the genus. Pastinaca is represented with eight species and four subspecies in the world. P. latifolia DC. is regarded as a subspecies of P. sativa.

Centaurea species in Turkey (A): Centaurea odyssei Wagenitz (Asteraceae) in Kazdagi (Mt. Ida) National Park

Kazdagi (Mt. Ida: 1774 m) is in northwestern Turkey. The rock type is mainly schist, and the soil is brown forest soil without lime. For these reasons, Kazdagi is one of the most important floristic areas in Turkey. With regard to genetic resources, this area is of major importance for in situ conservation of plant genetic diversity. Centaurea odyssei Wagenitz is a threatened very local endemic species, growing only in three small areas on Kazdagi. These populations are under heavy grazing stress. Morphological, anatomical and palynological studies are described and autecological and conservation aspects of the species are discussed.

Comparative fruit studies in a group of tribe Peucedaneae (Umbelliferae)

Comparative fruit studies (macro- and micro-morphology and anatomy) have been undertaken in a group of tribe Peucedaneae (Umbelliferae) (Malabaila Hoffm.,Pastinaca L., Heracleum L., Stenotaenia Boiss., Opopanax W.D.J. Koch, andGrafia Rchb.). A multivariate analysis was carried out using Simple Matching Coefficient and UPGMA (unweighted pair group method using arithmetic averages)and WPGMA (weighted pair group method using arithmetic averages) clustering methods. Two types of dorsal mericarp surface and margin sufaces were detected:(1) reticulate with a smooth surface, (2) reticulate with a striate surface. On the dorsal surface of the mericarps, three hair shapes and four hair surface types were seen. These hairs are treated as having systematic significance. For instance, a very short triangular hair with a papillose surface is unique to Pastinaca. The shapes of the mericarp and mericarp apex at the base of stylopodium are significant features for generic delimitation. Malabaila is distinguished by its c...

Centaurea species in Turkey (B): Comparative studies of two closely related species, C. kurdica Reichardt and C. sclerolepis Boiss

Morphological, anatomical, palynological, achene structure, and ecological features of two endemic Centaurea L. species, C. kurdica Reichardt and C. sclerolepis Boiss., were studied in detail. Pollen studies showed that the pollen grains of the species could be described as prolate-spheroidal in C. kurdica, and prolate in C. sclerolepis. The SEM study of achene surfaces showed that the cell wall in C. kurdica is thicker than that of C. sclerolepis, especially on the margins. It was determined that the soil in which C. sclerolepis grows is richer in organic matter and Ca++ and Mg++ ions than that below C. kurdica. It was also found that the root anatomy shows significant variations between the species and can be used to differentiate them.

Antioxidant response of Chlamydomonas reinhardtii grown under different element regimes

Nutrient stress is one of the most favorable ways of increasing neutral lipid and high value‐added output production by microalgae. However, little is known about the level of the oxidative damage caused by nutrient stress for obtaining an optimal stress level for maximum production of specific molecules. In this study, the antioxidant response of Chlamydomonas reinhardtii grown under element deprivation (nitrogen, sulfur, phosphorus and magnesium) and supplementation (nitrogen and zinc) was investigated. All element regimes caused a decrease in growth, which was most pronounced under N deprivation. Element deprivation and Zn supplementation caused significant increases in H2O2 and lipid peroxidation levels of C. reinhardtii. Decrease in total chlorophyll level was followed by an increase of total carotenoid levels in C. reinhardtii under N and S deprivation while both increased under N supplementation. Confocal imaging of live cells revealed dramatic changes of cell shape and production of neutral lipid bodies accompanied by a decrease of chlorophyll clusters. Antioxidant capacity of cells decreased under N, S and P deprivation while it increased under N and Zn supplementation. Fluctuation of antioxidant enzyme activities in C. reinhardtii grown under different element regimes refers to different metabolic sources of reactive oxygen species production triggered by a specific element absence or overabundance.

Pastinaca erzincanensis (Apiaceae), A New Species from Eastern Turkey and Its Phylogenetic Position within Tordylieae

Pastinaca erzincanensis Menemen & Kandemir (Apiaceae) is described as a new species, restricted to a single location in Erzincan Province, Turkey. To describe the species and assess its phylogenetic placement, field-collected and herbarium specimens were examined for morphological, fruit anatomical/micromorphological and palynological variation and included in a molecular phylogenetic study. Comparisons of leaf morphology, palynology and fruit anatomy suggest an affinity with Pastinaca (Tordylieae tribe Tordyliinae), although the presence of vittae in the fruit ribs is unique within the genus. Maximum parsimony and maximum likelihood analyses of nrDNA ITS sequences from representative members of tribe Tordylieae show that P. erzincanensis nests within a well-supported clade comprising members of Pastinaca, Malabaila and Trigonosciadium. Within a poorly supported Pastinaca s. lato clade, P. erzincanensis is sister group to M. pastinacifolia, with P. pimpinellifolia, P. yildizii and M. brachytaenia placed as successive sister taxa. Pastinaca erzincanensis differs from M. pastinacifolia, P. pimpinellifolia, P. yildizii and M. brachytaenia by having nine vittae on its dorsal mericarp surface (four vallecular and five rib vittae) and no commissural vittae. Based on characters of leaf morphology, palynology and fruit anatomy, and the molecular phylogenetic analysis results, we recognize the new species as belonging to the genus Pastinaca.