Turfgrass species response exposed to increasing rates of glyphosate application

To investigate the response of nine turfgrass species exposed to increasing rates of glyphosate application, the dry matter production, visual leaf injury symptoms (e.g., chlorosis and necrosis) and the concentrations of shikimate and mineral nutrients were determined in shoots. The rates of foliar glyphosate application were 0%, 5% (1.58 mM), and 20% (6.32mM) of the recommended application rate for weed control. In general, there was a negative and weak correlation between the intensity of visual injury and relative decreases in shoot dry matter production caused by glyphosate application. The decreases in shoot dry matter production and the severity of leaf damage pronounced by increasing glyphosate rate showed a substantial variation among the turfgrass species. Of the turfgrass species tested, Festuca arundinacea ‘Falcon’ and Buchloe dactyloides ‘Bowie’were selected as the most tolerant and sensitive species to applied sublethal rates of glyphosate as judged from visual injury ratings, respectively. At the highest glyphosate rate, shoot dryweightwas decreased by 4-fold in Bowie and only 1.6-fold in Falcon. When glyphosatewas not applied, shoot shikimate concentration of all species was very low and below 2.8mol g−1 FW (fresh weight). Glyphosate applications resulted in increases in shoot shikimate concentration with substantial variations among species. At 6.32mM glyphosate treatment, shikimate concentration ranged between 156.1mol g−1 (F. rubra, Ambrose) and 16.5mol g−1 FW (F. rubra, Cindy Lou). However, the highly sensitive and the tolerant genotypes were not different in shoot shikimate concentrations. Even, in the case of some genotypes, high glyphosate tolerance is accompanied by higher shoot concentrations of shikimate. Depending on the turfgrass species and mineral nutrients tested, increasing glyphosate application either did not affect or reduced mineral nutrient concentrations. In the case of decreases in shoot concentration of mineral nutrients, the decreases in Ca, Mg, Mn and Fe were most distinct. The results obtained indicate existence of a large genetic variation in tolerance to glyphosate toxicity among the turfgrass species. This differential variation in tolerance to glyphosate could not be explained by the changes in shoot concentrations of shikimate and mineral nutrients

N-Asetiltransferaz ve glutatyon S-transferaz teta polimorfizminin meme kanserri ile olan ilişkilerinin araştırılması

Biyolojik asetilasyon ve S-konjugasyon reaksiyonları, insan ve hayvan türlerinin ana konjugasyon reaksiyonlarından en önemli iki tanesidir. Bu çalışmada, insan meme dokusuna özel asetil koenzim A'ya bağımlı arilamin N-asetiltransferaz (E.C.2.3.1.5) ve glutatyon-S-transferaz (E.C.2.5.1.18) enzim aktiviteleri çalışılmış ve dokulardaki asetilasyon ile glutatyon transferi arasındaki ilişki incelenmiştir. Bu amaçla, meme kanserli 22 kadın hastada, N-asetiltransferaz (NAT1 ve NAT2) ve glutatyon-S-transferaz-teta-2-2 (GSTT2-2) enzim aktiviteleri, kanserli ve normal dokularda tayin edilmiştir. Normal ve kanserli dokularda ortalama değerler, sırasıyla NAT1 için 0,014$\pm$0,01 ve 0,019±0,01 nmol/dak/mg protein; NAT2 için 0,010$\pm$0,01 ve 0,034$\pm$0,03 nmol/dak/mg protein; GSTT2-2 için 0,272$\pm$0,29 ve 0,424$\pm$0,37 nmol/dak/mg protein olarak bulunmuştur.İstatistiksel analizler sonucunda , GSTT2-2 ortalama aktivitesinin kanserli dokularda kontrollere göre daha yüksek olduğu belirlenmiş; kanserli dokularda NAT1 ve GSTT2-2 aktiviteleri arasında negatif bir korelasyon olduğu gözlenmiştir. NAT1'e oranla NAT2 aktivitelerinin meme tümörlerinde belirgin bir şekilde arttığı ve GSTT2-2 aktiviteleri ile pozitif bir korelasyon sergilediği gözlemlenmiştir. Daha önceki çalışmamızda olduğu gibi, kanserli dokularda, kontrol dokularından elde edilen daha yüksek NAT2 ortalama aktivitesi olduğu ve bunun istatiksel olarak anlamlı olduğu tespit edilmiştir