Search

A two-fold integrated research study was conducted, firstly, to understand the effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus, secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover in wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg L&minus, 1) and Zn (0.5 and 1.5 mg L&minus, 1) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD, catalase, CAT, glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. A low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to the control, but the addition of duckweed prevented weight loss. Furthermore, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, the results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs.

A two-fold integrated research study was conducted; firstly, to understand effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus; secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover from wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg/L) and Zn (0.5 and 1.5 mg/L) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. Low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to control, but addition of duckweed prevented weight loss. Further, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs.

Water blooms are a serious environmental problem affecting fresh and marine ecosystem. Application of probiotic bacteria has been introduced as an emerging and eco-friendly tool to regulate or inhibit cyanobacterial blooms. In the present study, we have isolated and morphologically identified cyanobacteria from El Manzala Lake. Afterward, we examined the use of probiotic lactic acid bacteria MT2 (Lactobacillus sakei) isolated from Nile Tilapia (Oreochromis niloticus) intestine in controlling Anabaena sp. and Oscillatoria sp., isolated from El Manzala Lake. Measuring chlorophyll, phycocyanin and biomass concentration were conducted in a co-culture experiment between the selected cyanobacterial isolates and probiotic lactic acid bacteria (MT2). Chlorophyll content, phycocyanin content and biomass concentration of Anabaena sp., and Oscillatoria sp., were decreased significantly in the co-culture experiment with MT2 bacteria. Also, the microscopic examinations showed that MT2 bacterium was able to lysis and degrade the selected cyanobacterial cells under microscope. We concluded that the use of MT2 (Lactobacillus sakei) is potentially effective against some cyanobacteria especially Anabaena sp. and Oscillatoria sp.

Pollution of lakes and seas in Egypt become a severe problem as it produces a lot of wastes and toxic chemicals. The water pollution induces a lot of endocrine disruptions in aquatic organisms. Several endocrine organs are influencing by pollution such as testes, ovaries, pituitary, hypothalamus, thyroid, and adrenal organs. Propositions of upsetting endocrine chemicals (EDCs) can meddle with fish larval advancement affecting the delicate balance of the biological ecosystem. Endocrine disruption effects on reproductive cycles may affect reproductive behaviour and the development of secondary sexual characteristics. So the main objective of this research is to use marine algae, Dunaliella salina, extract in fish immunity enhancement against pollutants. Nile tilapia fish were exposed to Dioxin (as the main pollutant in the Egyptian environment) after feeding on algae extracts for one month. The results revealed that Dunaliella salina was able to protect the fish against pollution as it enhances the immune capability of Nile tilapia fish due to increase the levels of the antioxidant enzymes and decrease the protein oxidation. Additionally, Dunaliella salina extract was able to decrease the alteration in the expression of genes encoding endocrine hormones such as LH and FSH in the pituitary of Nile tilapia exposed to Dioxin in comparison to control fish. Moreover, the Dunaliella salina extract decreased significantly the DNA damage in brain tissues of Nile tilapia exposed to Dioxin compared with control fish. The results conclude that Dunaliella salina could be used as ameliorative compounds against toxicity of Dioxin.

We have developed an original in vitro bioassay using teleost scale, that has osteoclasts, osteoblasts, and bone matrix as each marker: alkaline phosphatase (ALP) for osteoblasts and tartrate-resistant acid phosphatase (TRAP) for osteoclasts. Using this scale in vitro bioassay, we examined the effects of seawater polluted with highly concentrated polycyclic aromatic hydrocarbons (PAHs) and nitro-polycyclic aromatic hydrocarbons (NPAHs) on osteoblastic and osteoclastic activities in the present study. Polluted seawater was collected from two sites (the Alexandria site on the Mediterranean Sea and the Suez Canal site on the Red Sea). Total levels of PAHs in the seawater from the Alexandria and Suez Canal sites were 1364.59 and 992.56 ng/l, respectively. We were able to detect NPAHs in both seawater samples. Total levels of NPAHs were detected in the seawater of the Alexandria site (12.749 ng/l) and the Suez Canal site (3.914 ng/l). Each sample of polluted seawater was added to culture medium at dilution rates of 50, 100, and 500, and incubated with the goldfish scales for 6 hrs. Thereafter, ALP and TRAP activities were measured. ALP activity was significantly suppressed by both polluted seawater samples diluted at least 500 times, but TRAP activity did not change. In addition, mRNA expressions of osteoblastic markers (ALP, osteocalcin, and the receptor activator of the NF-κB ligand) decreased significantly, as did the ALP enzyme activity. In fact, ALP activity decreased on treatment with PAHs and NPAHs. We conclude that seawater polluted with highly concentrated PAHs and NPAHs influences bone metabolism in teleosts. © 2016 Zoological Society of Japan., Embargo Period 12 months

Dioxins have global concerns because of the bioaccumulation tendency and persistency in the environment. Water, seabream Pagrus auratus and seabass Dicentrarchus labrax samples were collected from Abu Qir, Alexandria to evaluate the concentration of dioxin. Fourier Transform Infrared Spectrometer (FTIR) and molecular modeling was applied for elucidating the molecular structure of fish samples. Furthermore, HPLC with UV detection was used to determine the concentration of dioxins (2,8-dichloro dibenzo-p-dioxin). RT-PCR assay was conducted to verify the expression of some immune genes in the fish species as a result of water pollution. The average detected concentrations varied from 0.2 to 1.3μg/l. Gene expression revealed that MHC class 1 and C3 were highly upregulated in liver and muscle of seabass and seabream while T2BP was highly regulated in seabass liver and seabream muscle and seabass muscle for transferrin, FTIR and molecular modeling indicate that dioxin finds its way to fish protein.

Mediterranean fish species living along Italian (Gaeta) and Egyptian (Alexandria) coasts were analyzed using DNA barcodes for molecular identification. Mitochondrial Cytochrome c Oxidase subunit 1 (COI) gene was sequenced from 31 different marine species to test whether the morphology-based assignment of individuals into 19 families, 6 orders was supported by DNA-based species delimitation and Neighbour Joining cladogram. All COI rRNA gene barcodes were matched with reference sequences of expected species, according to morphological identification. Neighbour joining tree was drawn based on COI rRNA gene and the majority of specimens clustered in agreement with their taxonomic classification. Our results updated Mediterranean edible fish knowledge providing graphical resources, taxonomical and bioinformatics references, improving the genetic fish database and the basic molecular information to strengthen the science–policy interface for biodiversity and ecosystem services as conservation, blue economy, and long-term human well-being.

The aim of the present work was to assess, by rapid approach, the detoxification capacity and the genotoxicity caused by exposure of some marine fish to polluted waters. The fish species selected for the study: white sea bream (Diplodus sargus, Linnaeus 1758) and sardine (Sardine pilchardus, Walbaum 1792) were collected from different sites of Alexandria, El-Max bay and Bahary, in Egypt. Results of heavy metals analysis in sediment were: Al>Fe>Cr>Pb>Hg>Cd. Concerning detoxification analysis, fish collected from El-Max bay encounter the highest liver enzyme activity of Glutathione S-Transferase. Also, genotoxicity was evaluated in liver, gills and muscle of fishes collected and the results indicated that fish collected from El-Max bay has the highest levels of comets (DNA damage) when compared to the other sites selected as reference. It can be concluded from our results that the different tissues examined have alteration of level of detossification and comets as result of different degree of oxidative pollution insult. These biological responses may be considered for rapid extimation of food oxidative damage as well as for environmental quality.

The increase of seawater temperature as a result of global climate variation elucidates a major challenge for marine organisms survival in addition to consumers safety. Spotted grouper (Epinephelus coioides) and Seabream (Sparus aurata) were collected in water with different temperature variations at Suez Canal and Alexandria (Suez and Abu Qir bay) in Egypt with the aim to assess expression levels of heat shock proteins such as HSP47, HSP70 and HSP90 genes in addition to antioxidants value through enzymes activity: Glutathione-S-Transferase (GST) and Glutathione Peroxidase (GPx). Research results revealed that expression of the HSP47, HSP70a and HSP90 genes increased in marine fishes tissues collected from Suez Canal, with higher water temperature (23:28ºC), compared with those collected from Alexandria (19:24°C) whereas the content of GPx and GST decreased. Our results show alteration of the marker examined suggesting that the increase of heat shock protein genes expression levels of fish collected from Suez Canal might be exposed mainly to thermal oxidative stress response more than those collect from Alexandria. The increase of heat shock protein-related genes expression could be considered as a factor in prohibiting the heat shock transcription factor that may lead to stimulation of heat-inducible genes in addition to heat acclimation. Thus, warming of water is also likely to alter the composition and abundance of food resources, e.g. fish muscles, available to higher trophic level consumers.