Ozgur Cakir

Selenium Metabolism in Plants: Molecular Approaches

Selenium (Se) is placed in Group VIA of the Periodic Table. Its chemistry is similar to sulfur (S). Practically all small organic selenium compounds are isologues of corresponding sulfur compounds. With a few exceptions, they are also isologues of sulfur amino acids or derivatives thereof. Selenium plays an indispensable role for humans, animals and microorganisms. It is beneficial for the metabolism at lower concentrations, whereas at higher concentrations it becomes toxic. In other words, the range between deficiency and toxicity is very narrow. Short-term consumption of high levels of Se by human and animals may cause nausea, vomiting, and diarrhea, whereas chronic consumption of high concentrations of Se compounds can result in a disease called selenosis (Goldhaber, 2003). Excess selenium in the environment can be the result of either natural geological processes or industrialization.

Detection of genetically modified organisms in soy products sold in Turkish market

PCR-based technique for GMO detection is the most reliable choice because of its high sensitivity and specificity. As a candidate of the European union, Turkey must comply with the rules for launching into the market, traceability, and labeling of GMOs as established by Eu legislation. Therefore, the objective of this study is to assess soybean products in the Turkish market to verify compliance with legislation using qualitative Polymerase Chain Reaction (PCR) assay to detect the presence of GM soybean and to quantify its amount of GM soybean in the samples tested positive using real-time PCR. DNA extracted by the modified CTAB method was properly used for PCR amplification of food materials. The amplification of a 118 bp DNA fragment of the lectin gene from soybean by PCR was successfully achieved in all samples. The GMO screening was based on the detection of 35S promoter and NOS terminator sequences. The GM positive samples were subjected to detection of Roundup Ready TM soybean (RR) using quantitative real-time PCR. It was found that 100% of the tested food samples contained less than 0.1 per cent of EPSPS gene.

Selenium induced selenocysteine methyltransferase gene expression and antioxidant enzyme activities in Astragalus chrysochlorus

Abstract Astragalus sp. are used in folk medicine because of their biological activities and are known for the ability to accumulate high levels of selenium (Se). The purpose of this study was to explore gene expression of selenocysteine methyltransferase (SMT), responsible for forming MeSeCys, and activities of ascorbate peroxidase (APX), peroxidase (POX), catalase (CAT) and glutathione reductase (GR) enzymes in callus tissues of Astragalus chrysochlorus growing in different Se-containing media. Quantitative real-time polymerase chain reaction assay was done for quantification of SMT gene transcript and it was normalized to actin gene. It was found that transcript level of callus tissues grown at 5.2 μM and 26.4 μM Se-enriched media was lower than that of the control callus. In contrast, a high level of Se (132.3 μM) in the medium caused an approximately 4.26 times higher level of SMT transcript in callus than the control. APX, POX, CAT and GR enzymes were all effected by different Se concentrations. While POX and APX activities were higher then control, CAT and GR activities decreased. These results show that an increase of SMT gene expression led to a rise in APX and POX, but a suppression of CAT and GR enzymes activities in Astragalus chrysochlorus. This suggests that Se could be involved in the antioxidant metabolism in Astragalus chrysochlorus.

Manipulating Selenium Metabolism in Plants: A Simple Twist of Metabolic Fate Can Alter Selenium Tolerance and Accumulation

Selenium (Se) is a micronutrient for many organisms including humans. But like many trace elements, Se can be toxic at high concentrations and become a public health concern if it accumulates in soils or groundwater. Although higher plants don’t require Se, plants can still accumulate and metabolize Se via the sulfur assimilatory pathway. Genetic manipulation of plant selenium metabolism primarily stems from two areas of interest: it has the potential to improve the phytoremediation of Se in contaminated areas, and it may aid the development of Se-containing phytochemical compounds that possess health benefits. This review highlights studies that have successfully altered Se metabolism in plants, and concludes by focusing on novel genes and pathways that might be targeted to manipulate Se metabolic processes.

miRNA Profiling in Plants: Current Identification and Expression Approaches

MicroRNAs (miRNAs) are the members of small noncoding RNA molecules in eukaryotes that regulate the posttranscriptional gene expression of target mRNAs positively or negatively via their degradation and/or translational inhibition. miRNAs play a crucial role in biological processes such as growth, development, maturation, cell differentiation, and response to various abiotic and biotic stress factors. Therefore, miRNA discovery and determining the functional aspects of miRNA expressions and their targets are important for breeding strategies and plant biotechnology. There are several computational and experimental approaches to identify miRNAs and reveal the expression patterns such as cloning, homology-based approaches, high-throughput deep sequencing, quantitative real-time PCR (qRT-PCR) and hybridization-based methods such as microarray and northern blot. Here, we describe these recent approaches for miRNA profiling on some model and non-model plant species following brief information about miRNA evolution and biogenesis.

Detection of Genetically Modified Organisms in Feed

Animal feeds originating from plants produced by genetic engineering technologies are increasing day after day. It is a legal obligation to produce these feeds under strict rules and to track them in order to determine the effects of genetically modified organisms (GMOs) to human health, animal health, and the environment. For this reason, it is necessary to detect, identify, and investigate the legal conformity of GMOs in feeds. Within this scope, as fast and robust methods, polymerase chain reaction (PCR)-based techniques are preferred in most laboratories due to their efficiency and specificity. Moreover, the development of new animal feed products from next generation GM plants, unauthorized and antibiotic resistance gene-free transgenics, will lead to the present techniques failing to satisfy in the upcoming years. Therefore, it is essential to develop reliable, sensitive, reproducible, and high-throughput technologies. The most promising technologies are biosensing, lab-on-a-chip, array-based and sequencing approaches. In this chapter we summarize PCR methods, the most reliable technique to detect GMOs in feeds today to provide an insight to researchers.