Fine structural and biochemical studies on the infection of vicia faba l. by uromyces and botrytis

(1) Fine structural and biochemical studies have been made on the infection of Vicia faba L. by Uromyces fabae (obligate parasite) and Botrytis fabae (facultative parasite). (2) Fine structural observations of host cells infected with U. fabae showed that they could be divided into two categories, (a) cells with increased capacity for synthesis (2-8 days after infection), which are characterised by an increase in the volume of the cytoplasm and by an increase in the size of cytoplasmic organelles (i.e. rough endoplasmic reticulum (ER), nucleus, mitochondria); (b) cells with decreased metabolic activities (12-20 days after infection) and characterised by senescence of the cytoplasm and by the reduction in the size of cytoplasmic organelles, especially chloroplasts. Numerous vesicles were found to be associated with the inner membrane of chloroplasts in such infected cells. (3) Electron microscopic observations showed that cells from leaves infected with B. fabae, can also be divided into two categories, (a) cells in the centre of the necrotic lesion which are characterised by blackening and the destruction of the tissues;(b) cells at the periphery of the necrotic lesion, which are characterised by an increase in the volume of the cytoplasm, an increase in the size of cytoplasmic organelles, by the presence of lomasomes, and by the presence of vesicular inclusions in the cytoplasm and electron dense bodies in the extracellular spaces.(4) The fine structure of U. fabae resembles that of other comparable obligate parasites, except for the presence of an electron dense ring in the middle part of the haustorial neck, and vesicular and tubular structures in the vacuoles of this fungus. The growth of B. fabae on the host tissues was found to be relatively limited as compared with its growth on artificial medium. Likewise, the cytoplasm and cytoplasmic organelles of B. fabae were found to be denser when the fungus was grown on artificial media. Lomasomes were found to be common in the cytoplasm of this fungus, and the relation of this structure to the hydrolysis of the host cell wall is discussed. (5) Several biochemical tests were made to assess the significance of some of the structural changes taking place in the host as a result of infection (i.e. amino acid composition, protein synthesis and photochemical activities of isolated chloroplasts). Special emphasis was placed on the effect of both infections on the latter process. The results can be summarised as follows:- (a) infection with U. fabae caused an increase in the rate of the Hill reaction, cyclic phosphorylation (2-10 days after infection), followed by a decrease in such activity (12-20 days after infection). The infection also caused an alteration to ATP:e(^-) ratio. .(b) infection with B. fabae caused a marked reduction in all photochemical activities tested, (i.e. Hill reaction, cyclic and uncyclic phosphorylation).(c) The observed effects were found to be independent of the chlorophyll concentration and the reduction in the photosynthetic area

Effect of Zinc nanoparticles on oxidative stress-related genes and antioxidant enzymes activity in the brain of Oreochromis niloticus and

This study was carried out to determine the median lethal concentrations (LC50) of Zinc nanoparticles (ZnNPs) on Oreochromis niloticus and Tilapia zillii. The biochemical and molecular potential effects of ZnNPs (500 and 2000 μg L−1) on the antioxidant system in the brain tissue of O. niloticus and T. zillii were investigated. Four hundred fish were used for acute and sub-acute studies. ZnNP LC50 concentrations were investigated in O. niloticus and T. zillii. The effect of 500 and 2000 μg L−1 ZnNPs on brain antioxidants of O. niloticus and T. zillii was investigated. The result indicated that 69 h LC50 was 5.5 ± 0.6 and 5.6 ± 0.4 for O. nilotica and T. zillii, respectively. Fish exposed to 500 μg L−1 ZnNPs showed a significant increase in reduced glutathione (GSH), total glutathione (tGSH) levels, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activity and gene expression. On the contrary, malondialdehyde (MDA) levels significantly decreased. Meanwhile, fish exposed to 2000 μg L−1 ZnNPs showed a significant decrease of GSH, tGSH levels, SOD, CAT, GR, GPx and GST activity and gene expression. On the contrary, MDA levels significantly increased. It was concluded that, the 96 h LC50 of ZnNPs was 5.5 ± 0.6 and 5.6 ± 0.4 for O. nilotica and T. zillii, respectively. ZnNPs in exposure concentrations of 2000 μg/L induced a deleterious effect on the brain antioxidant system of O. nilotica and T. zillii. In contrast, ZnNPs in exposure concentrations of 500 μg L−1 produced an inductive effect on the brain antioxidant system of O. nilotica and T. zillii

Toxicity of silver nanoparticles on the brain of Oreochromis niloticus and Tilapia zillii

Background: Silver nanoparticles (Ag-NPs) are widely used nowadays in a variety of commercial applications including medical, health care, textiles and household supplies. Objectives: The current study was designed to determine the median lethal dose (LC50) of Ag-NPs on Oreochromis niloticus and Tilapia zillii. Methods: Acute and sub-acute toxicity study of the Ag-NPs on brain tissues was carried out using different concentrations of the NPs at 2 mg L and 4 mg L. These concentrations were dispersed in deionized water with the exception of the control groups in the experiments. Biochemical and molecular analysis were conducted on tissue homogenates in order to evaluate the potential effects of NPs on the antioxidant system. Results: The Ag-NP acute toxicity (96 h LC50) values of 19.5 ± 2 and 20 ± 2.4 mg/L were reported for O. niloticus and T. zillii respectively. Fish exposed to 2 mg/L Ag-NPs did not show any significant change in the levels of reduced glutathione (GSH), total glutathione (tGSH) levels, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activity or genes expression and malondialdehyde (MDA) level. In contrary, a dose of 4 mg/L showed a significant reduction in the levels all the above-mentioned parameters except in MDA level where it was significantly induced. Conclusion: Results indicate that exposure of O. niloticus and T. zillii to Ag-NPs (4 mg/L) has deleterious effects on brain antioxidant system, whereas a dose of 2 mg/L has no effects. Keywords: Ag-NPs, LC50, Antioxidants, O. nilotica, T. zilli

Alteration in antioxidant genes expression in some fish caught from Jeddah and Yanbu coast as a bio-indicator of oil hydrocarbons pollution

The mRNA expression profile of some antioxidant genes in skin, gills, livers, and muscles of Siganus canaliculatus and Epinephelus morio was used as an indicator of petroleum hydrocarbons pollution in six areas at Jeddah and Yanbu coasts in KSA. Total petroleum hydrocarbons (TPHs) were determined in both sea water and sediments collected from the studied areas. The mRNA expression levels of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were determined. The highest level of total petroleum hydrocarbons was observed in front of the petromine refinery at Jeddah and in S. canaliculatus when compared to E. morio. There was a significant high expression level of studied antioxidant enzymes genes in the polluted areas and the level of the expression profile tended to correlate with the degree of pollution and fish species feed habit. This was confirmed by the level of MDA which in the same way increased with an increase in the level of total hydrocarbons. In conclusion; the expression profile of antioxidant enzymes of S. canaliculatus and E. morio tissues can be used as a strong bio-indicator of total hydrocarbons pollution especially in S. canaliculatus