Production of methionine γ- lyase in recombinant Citrobacter freundii bearing the hemoglobin gene

The production of antileukemic enzyme methionine γ-lyase (MGL) in distinctly related bacteria, Citrobacter freundii and in their recombinants expressing the Vitresocilla hemoglobin (VHb) has been studied. This study concerns the potential of Citrobacter freundii expressing the Vitreoscilla hemoglobin gene (vgb) for the methionine γ- liyase production. Methionine γ- liyase production by Citrobacter freundii and its vgb(-) and vgb(+) bearing recombinant strain was studied in shake-flasks under 200 rpm agitation, culture medium and 30 °C in a time-course manner. The vgb(+) and especially the carbon type had a dramatic effect on methionine γ- liyase production. The vgb(+) strain of C. freundii had about 2-fold and 3.1-fold higher levels of MGL than the host and vgb(-) strain, respectively.     

Diverse action of acrylamide on cytochrome P450 and glutathione S-transferase isozyme activities,mRNA levels and protein levels in human hepatocarcinoma cells

Humans are exposed to acrylamide in their diet and cigarette smoke. Acrylamide is metabolized into glycidamide by CYP2E1. However, very few studies regarding the effects of acrylamide on cytochrome P450 and Glutathione S-Transferase (GST) isozymes have been pursued. The aim of this study is to elucidate the effects of acrylamide on cytochrome P450 and GST isozymes in HepG2 cell line. Treatment with 1.25 and 2.5 mM acrylamide caused 9.5- and 3.7-fold increases and 4.0- and 3.3-fold increases in CYP1A-associated ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) activities, respectively. These increases were consistent with increases in mRNA and protein levels of these isozymes. Similarly, CYP2E1-associated aniline 4-hydroxylase (ANH) activity, protein levels, and mRNA levels increased 2.1- and 2.6-fold, 2.4- and 3.2-fold, and 1.4- and 1.9-fold following 1.25 and 2.5 mM acrylamide treatments, respectively. In addition, GST-mu activity was increased 2.4- and 5.1-fold by acrylamide. Moreover, GST-mu mRNA and protein levels increased twofold as a result of acrylamide treatment. In contrast, GST-pi protein and mRNA levels decreased significantly. In conclusion, human cell exposure to acrylamide causes an increase in the levels of carcinogenicity and toxicity and a disturbance in drug metabolism, possibly due to complex effects on P450 and GST isozymes.     

Resveratrol ameliorates oxidative DNA damage and protects against acrylamide-induced oxidative stress in rats

Acrylamide (ACR), used in many fields from industrial manufacturing to laboratory personnel work is also formed during the heating process through interactions of amino acids. Therefore ACR poses a significant risk to human health. This study aimed to elucidate whether resveratrol (RVT) treatment could modulate ACR-induced oxidative DNA damage and oxidative changes in rat brain, lung, liver, kidney and testes tissues. Rats were divided into four groups as control (C); RVT (30 mg/kg i.p. dissolved in 0.9% NaCl), ACR (40 mg/kg i.p.) and RVT + ACR groups. After 10 days rats were decapitated and tissues were excised. 8-hydroxydeoxyguanosine (8-OHdG) is a biomarker of oxidative DNA damage. 8-OHdG content in the extracted DNA solution was determined by enzyme-linked immunosorbent assay method. Malondialdehyde (MDA), glutathione (GSH) levels and myeloperoxidase activity (MPO) were determined in tissues, while oxidant-induced tissue fibrosis was determined by collagen contents. Serum enzyme activities, cytokine levels, leukocyte apoptosis were assayed in plasma. As an indicator of oxidative DNA damage, 8-OHdG levels significantly increased in ACR group and this was reversed significantly by RVT treatment. In ACR group, GSH levels decreased significantly while the MDA levels, MPO activity and collagen content increased in the tissues suggesting oxidative organ damage. In RVT-treated ACR group, oxidant responses reversed significantly. Serum enzyme activities, cytokine levels and leukocyte late apoptosis which increased following ACR administration, decreased with RVT treatment. Therefore supplementing with RVT can be useful in individuals at risk of ACR toxicity.     

Analgesic activity of dipeptide Tyr-Pro

The effect of dipeptide Tyr-Pro, present in representatives of most families of opioid peptides, and two its analogs, Tyr-Pro-NH₂ and Tyr-Pro-OMe, on analgesic activity was studied in different tests (tail-flick test, tail pinch (Haffner’s) test, formalin test, and acetic acid writing test) describing different organization levels of pain sensitivity. Intraperitoneal administration of the dipeptide decreased the pain threshold in all above-mentioned tests. Coadministration of the dipeptide and naloxone or naloxone methiodide insignificantly decreased the dipeptide analgesic effect in the tail-flick and acetic acid writing tests. Its analogs Tyr-Pro-NH₂ and Tyr-Pro-OMe demonstrated a similar analgesic activity in the tail-flick test and a higher activity in the acetic acid writing test. Administration of individual amino acids (Tyr or Pro) or their mixture had no effect on the pain threshold.     

P19-dependent and P19-independent reversion of F1-V gene silencing in tomato

As a part of a project to develop a plant-made plague vaccine, we expressed the Yersinia pestis F1-V antigen fusion protein in tomato. We discovered that in some of these plants the expression of the f1-v gene was undetectable in leaves and fruit by ELISA, even though they had multiple copies of f1-v according to Southern-blot analysis. A likely explanation of these results is the phenomenon of RNA silencing, a group of RNA-based processes that produces sequence-specific inhibition of gene expression and may result in transgene silencing in plants. Here we report the reversion of the f1-v gene silencing in transgenic tomato plants through two different mechanisms. In the P19-dependent Reversion or Type I, the viral suppressor of gene silencing, P19, induces the reversion of gene silencing. In the P19-independent Reversion or Type II, the f1-v gene expression is restored after the substantial loss of gene copies as a consequence of transgene segregation in the progeny. The transient and stable expression of the p19 gene driven by a constitutive promoter as well as an ethanol inducible promoter induced a P19-dependent reversion of f1-v gene silencing. In particular, the second generation plant 3D1.6 had the highest P19 protein levels and correlated with the highest F1-V protein accumulation, almost a three-fold increase of F1-V protein levels in fruit than that previously reported for the non-silenced F1-V elite tomato lines. These results confirm the potential exploitation of P19 to substantially increase the expression of value-added proteins in plants.     

Column study on the adsorption of Cr(III) and Cr(VI) using Pumice, Yarikkaya brown coal, Chelex-100 and Lewatit MP 62

In the present study, adsorption of Cr(III) and Cr(VI) on Pumice (Pmc), Yarikkaya (YK) brown coal, Chelex-100, and Lewatit MP 62 is examined at room temperature and at initial chromium concentration of 1.0 x 10(-3) mol/L. Column method was carried out as a function of pH, concentration of Cr(III) and Cr(VI) ions, volume of samples and flow rate. The experimental data were evaluated by Freundlich and Langmuir isotherm models. The dynamic breakthrough capacities of the adsorbents for Cr(III) and Cr(VI) were calculated. The maximum chromium sorption occurred at 5 mL/min flow rate and 25 mL volume for all adsorbents. The results showed that the two readily available adsorbents namely Pmc and YK, were suitable for removing chromium from aqueous solution.     

Fertility of ovulated oocytes after their short-term storage in water in several species of marine tropical fishes

Fertilizing ability of ovulated oocytes of Zebrasoma scopas (Acanthuridae), Dascyllus trimaculatus, and Abudefduf sexfasciatus (Pomacentridae) is assessed after their short-term storage in marine water. The proportion of eggs exhibiting normal cleavage is not decreased after the storage of oocytes for 5, 40, and 15 min, respectively. The storage of oocytes in water for a longer time leads to a lower fertilization rate and to increasing number of eggs with abnormal cleavage characterized by a low adhesion between cells and appearance of cells with unclear margins with subsequent cell degradation. Morphological changes in the oocytes accompanied by the decrease of their fertility are analyzed.