Plant extract supplementation as a strategy for substituting dietary antibiotics in broiler chickens exposed to low ambient temperature

ABSTRACT

The present study was conducted to investigate the effects of two plant extracts as alternatives to dietary antibiotics in broiler chickens exposed to low ambient temperature. A total of 300 one-day-old male broiler chickens were randomly assigned to four dietary treatments (5 replicate pens; 15 broiler chickens each) which consisted of starter (d 0 to 10), and grower (d 10 to 28) diets. Dietary treatments included a basal diet (negative control, NC) and three similar diets that were either supplemented with 200 mg/kg of Prosopis farcta extract (PFE), Rhus coriaria L. extract (RCE) or an antibiotic premix containing oxytetracycline (positive control, PC). In order to simulate low ambient temperature, room temperature was maintained at 32°C during the first 3 d of the trial and afterwards, the temperature was gradually reduced by approximately 1.5°C each day to 14°C on d 21. PFE and PC treatments exerted a significant effect on body weight gain at d 28. Diet PFE was effective in reducing mortality when compared with diet NC (p < 0.05). Furthermore, diet PFE caused increases in ileal digestibility of gross energy, dry matter and organic matter when compared with diet NC (p < 0.05). Diets PFE and PC decreased coliforms, total aerobic bacteria and total anaerobic bacteria loads in the caeca when compared with diet NC (p < 0.05). Moreover, the addition of PFE to the diet improved villous height in all small intestinal segments as well as villous height:crypt depth ratio in the duodenum when compared with diet NC (p < 0.05). The results indicated that PFE is not only a valid alternative to oxytetracycline under cold stress conditions, with no antibiotic resistance, but also has the potential to increase the resistance of broiler chickens against ascites syndrome. Moreover, the addition of RCE at the concentration of 200 mg/kg to the diet was not sufficient to improve the performance of broiler chickens (similar to diet PC) but maybe more effective at higher concentrations.     

Isoarnottinin 4′-glucoside, a glycosylated coumarin from Prangos uloptera, with biological activity

Coumarins are a well-known group of natural products distributed in the plant kingdom especially in the family Apiaceae with various biological activities. Isoarnottinin 4′-glucoside is a simple glycosylated coumarin found previously in a few genera of Apiaceae, and its biological activities have not been previously described in details. In the present paper, the compound was isolated from Prangos uloptera (Apiaceae) leaves using HPLC techniques. Antimicrobial, phytotoxic and cytotoxic activities of the compound were evaluated by disk diffusion, lettuce assay and MTT method. Our results indicated that the compound has high antibacterial effect against Erwinia carotovora, a common plant pathogen with MIC value of 100 μg/ml. The compound also exhibited significant phytotoxic activity against lettuce and modest cytotoxic activity against HeLa cell line with IC₅₀ of 0.84 mg/ml. It could be concluded that isoarnottinin 4′-glucoside may play phytoalexin or allelopathic role for plant and may be a candidate for an antibacterial agent or a bioherbicide.     

Comparative study of the expression of the native,modified, and hybrid <Emphasis Type="Italic">cry</Emphasis>3a genes of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> in prokaryotic and eukaryotic cells

The cry3a gene of Bacillus thuringiensis was cloned. Based on sequence analysis of this gene, a modified gene, cry3aM, was constructed, which has the optimal codon composition for effective expression in eukaryotic cells. Hybrid genes cry3a-licBM2 and cry3aM-licBM2 were constructed, in which the sequences of the native and modified genes are fused with the reporter gene for thermostable lichenase in the reading frame. We have shown that the expression levels of hybrid genes cry3a-licBM2 and cry3aM-licBM2 in Escherichia coli are comparable, being 5% of those for reporter gene licBM2. In cells of a lower eukaryote Saccharomyces cerevisiae, the expression of hybrid gene cry3aM-licBM2, which contains the modified gene, considerably exceeded the level of expression of cry3a-licBM2 containing the native gene. The presence of lichenase in the composition of hybrid proteins was shown to facilitate selection and analysis of the expression level of hybrid proteins in transgenic organisms.Translated from Genetika, Vol. 41, No. 2, 2005, pp. 171–177.Original Russian Text Copyright © 2005 by Salehi Jozani, Komakhin, Piruzian.     

Cadmium and lead in rice grains and wheat breads in Isfahan (Iran) and human health risk assessment

This study was conducted to survey the levels of cadmium (Cd) and lead (Pb) in the main foods of Isfahan province (central Iran). The rice grains and wheat breads were collected from Isfahan city and villages around the Isfahan and Mobarakeh Steel companies. The food samples were wet-ashed by heating in the presence of concentrated nitric acid and hydrogen peroxide. The concentrations of Cd and Pb were determined by inductively coupled plasma-optical emission spectrometer (ICP-OES). The potential exposure risks were then estimated. Levels of Cd in the rice grains and Pb in the investigated foods (except Sangak beard) were above the maximum levels as set by the Codex Alimentarius and National standards of Iran. The wheat bread samples in Isfahan city and Mobarakeh Steel regions presented higher estimated weekly intake (EWI) of Pb (40.93 and 35.35 µg kg^–1 body weight, respectively) compared to other foods. The EWI for Cd and Pb in most samples was considerably above than the provisional tolerable weekly intake. In most cases, the target hazard quotients values were above one and consequently the consumption of foods in the investigated regions was a potentially serious health risk caused by exposure to the crops contaminated with Cd and Pb.     

A fast model of voltage-dependent NMDA receptors

NMDA receptors are among the crucial elements of central nervous system models. Recent studies show that both conductance and kinetics of these receptors are changing voltage-dependently in some parts of the brain. Therefore, several models have been introduced to simulate their current. However, on the one hand, kinetic models—which are able to simulate these voltage-dependent phenomena—are computationally expensive for modeling of large neural networks. On the other hand, classic exponential models, which are computationally less expensive, are not able to simulate the voltage-dependency of these receptors, accurately. In this study, we have modified these classic models to endow them with the voltage-dependent conductance and time constants. Temperature sensitivity and desensitization of these receptors are also taken into account. We show that, it is possible to simulate the most important physiological aspects of NMDA receptor’s behavior using only three to four differential equations, which is significantly smaller than the previous kinetic models. Consequently, it seems that our model is both fast and physiologically plausible and therefore is a suitable candidate for the modeling of large neural networks.     

Nano silver: a novel nanomaterial for removal of bacterial contaminants in valerian (Valeriana officinalis L.) tissue culture

Bacterial contamination is a serious problem in plant tissue culture procedures. An experiment was conducted to evaluate the potential of nano silver (NS) to remove bacterial contaminants of valerian nodal explants. This experiment was conducted as a completely randomized design in a factorial arrangement with four replications and each replicate with ten explants. Treatments involved NS at two stages (before and after surface sterilization along with control) with three rates (25, 50 and 100 mg l⁻¹) at three times of soaking (30, 60 and 180 min). Explants were cultured on MS medium supplemented with 5 mg l⁻¹ Kin and 0.1 mg l⁻¹ NAA. Results showed that using 100 mg l⁻¹ of NS solution after surface sterilization resulted in the highest percentage (89%) of disinfected explants. Nano silver solution did not affect the characters measured. On the basis of the data obtained in this experiment, it was concluded that NS had a good potential for removing of the bacterial contaminants in plant tissue culture procedures. As this is the first report on application of NS in in vitro culture techniques, further investigations on other plant species are needed to clarify the effectiveness of NS for the removal of bacterial contaminants in tissue culture of other crops.     

Stimulation of neurotrophic factors and inhibition of proinflammatory cytokines by exogenous application of triiodothyronine in the rat model of ischemic stroke

There is a positive relation between decreases of triiodothyronine (T3) amounts and severity of stroke. The aim of this study was to evaluate the effect of exogenous T3 application on levels of neurogenesis markers in the subventricular zone. Cerebral ischemia was induced by middle cerebral artery occlusion in male Wistar rats. There were 4 experimental groups: sham, ischemic, vehicle, and treatment. Rats were injected with T3 (25 μg/kg, IV injection) at 24 hours after ischemia. Animals were sacrificed at day 7 after ischemia. There were high levels of brain‐derived neurotrophic factor, nestin, and Sox2 expressions in gene and protein levels in the T3 treatment group (P ≤ .05 vs ischemic group). Treatment group showed high levels of sera T3 and thyroxine (T4) but low levels of thyrotropin (TSH), tumor necrosis factor‐α, and interleukin‐6 (P ≤ .05 vs ischemic group) at day 4 after ischemia induction. Findings of this study revealed the effectiveness of exogenous T3 application in the improvement of neurogenesis possibly via regulation of proinflammatory cytokines.