Toxicity, inflammatory and antioxidant genes expression, and physiological changes of green synthesis silver nanoparticles on Nile tilapia (Oreochromis niloticus) fingerlings.

The rapid increase of incorporating silver nanoparticles (Ag-NPs) in different anthropogenic and industrial activities increased the discharge of these particles in the aquatic ecosystem. The environmental impact of Ag-NPs, especially the green synthesized is still not completely understood on fish. Therefore, this study aimed to investigate the effects of exposure to graded series of starch-mediated Ag-NPs at levels of 0, 3.31, 6.63, 13.25, and 26.50 mg L-1 representing 0, 6.25, 12.5, 25, and 50% of LC50 on Nile tilapia (O. niloticus), respectively. Fish with initial weight 37.63 ± 0.41 g were maintained in 70 L glass aquaria and exposed to starch-mediated Ag-NPs (average particle size 40 nm) for 28 days. The results revealed that starch-mediated Ag-NPs induced severe changes in the mRNA levels of toxicity (CYP1A and Hsp70) and inflammatory (TNF-α and TGF-ß) genes. The expression of antioxidant genes (SOD and CAT) was significantly suppressed, and the activities of their enzymes were inhibited significantly upon exposure. Simultaneously, the malondialdehyde level increased significantly with increasing the exposure levels of starch-mediated Ag-NPs. The red blood cells, hemoglobin, hematocrit and white blood cell values were decreased significantly with doses over 3.31 mg L-1 of Ag-NPs. In addition, the total protein and globulin decreased significantly with increasing Ag-NPs in a dose-dependent manner. The liver function enzymes and kidney function indicators revealed severe toxicity with Ag-NPs exposure. In conclusion, the effect of starch-mediated Ag-NPs in doses over 3.31 mg L-1 induced obvious toxicity in the molecular and proteomic levels in Nile tilapia fingerlings.

Age-related ultrastructural characterizations of the teeth of the white grouper (Epinephelus aeneus) in the different three age-stages.

This study represents the first attempt to describe ultrastructural features of teeth in different three ages of white grouper (Epinephelus aeneus) grossly and by the aid of the electron microscope. The current study depends on 18 oropharyngeal cavity of E. aeneus from each age-stages. There are common and special characterization between each age. Five teeth bands in the roof (incisive, canine, upper molar, palatine, and vomer), while two bands in the floor (incisive, molar). The apical teeth part resembles the arrowhead that bordered by groove distally. In 5 cm age, small upper incisive teeth had two appearance (straight and curved), and vomer teeth arranged in triangular in only one row (while, in 12 cm fish arranged in two rows and in 15 cm fish arranged in more than two rows), the palatine teeth began rostrally as one row then two rows and terminated by one row, while in other two ages began by two, then three and ended by two rows. There is no canine teeth in lower jaw in all age. In 12 cm fish, the rostral row of lower incisive teeth usually contain small straight teeth, while the posterior row mainly contain large with some medium upper incisive teeth. In 18 cm fish, upper incisive teeth located within two incisive fossa that separated from each other by longitudinal part of T-shaped upper incisive ridge and small incisive teeth had two appearance (straight and curved), and each canined teeth group contain four teeth (while in other two ages each group contain only two canine teeth).

The impacts of seasonal variation on the immune status of Nile tilapia larvae and their response to different immunostimulants feed additives.

Few data are available on the thermal tolerance of Nile tilapia fish larvae in relation to their immune status and survival. The aims of this work were to evaluate the immune status of one day old Nile tilapia (Oreochromis niloticus) larval stage collected at the beginning (March), middle (August) and at the end (October) of hatching season through morphometric assessment of the larvae parameters including yolk sac diameter, body length and width as well as the expression of some immune-related genes (rag, sacs and tlr), inflammatory (il1b and il8) and stress related genes (hsp27, hsp70). Also, to compare the effect of three different immunostimulants (ß-glucan, Vitamin C, and methionine/lysine amino acids mix) on the expression of the studied genes at two variant temperatures (23 ± 1 °C and 30 ± 1 °C) in experimental study for 21 days. The immune status of Nile tilapia is affected by thermal fluctuation throughout the hatching season reflected by altered yolk sac size, length, and expression of the immune and stress related genes of the larvae, the best performances was observed at the beginning of the hatching season (March). High temperature (30 °C) suppress immune and stress responses throughout downregulation of all the genes under study, mask any effects for the immunostimulants, increased mortality in fish larvae suggesting narrow thermal tolerance range for the larvae compared with the adult fish. We recommend the use of amino acid mix as immunostimulant for Nile tilapia larvae, it reduces the mortality percentage and improve cellular response. Also, the use of ß-glucan should be prohibited during this developmental stage of larvae, it induced the highest mortality percentage.

Association of MHC IIA polymorphisms with disease resistance in Aeromonas hydrophila-challenged Nile tilapia.

The major histocompatibility complex (MHC) genes show high polymorphisms in vertebrates depending on animal immunity status. Herein, MHC class IIA gene in Aeromonas hydrophila-challenged Nile tilapia was screened for presence of polymorphisms using sequencing. Twelve nucleotides deletion polymorphism was determined with a PCR product size of 267 bp in the resistant fish and 255 bp in the control and susceptible/diseased fish. Additionally, a non-synonymous right frameshift c.712 T > G (P. 238 * > G) SNP was detected at the stop codon (*). SNP-susceptibility association analysis revealed that fish carrying GG genotype and allele G were high susceptible (risk) for A. hydrophila, and had lower immune response as indicated by significant reduction in non-specific immune parameters (total protein, globulin, IgM, phagocytic activity, phagocytic index, and lysosome activity) and mRNA level of MHC IIA, interleukin 1 beta (IL1ß), tumor necrosis factor alfa (TNFα), and toll-like receptor 7 (TLR7) in the spleen and head kidney. Thus, G allele could be considered as a risk (recessive or mutant) allele for c. 712 T > G (P. 238 * > G) SNP and so selection of Nile tilapia with protective allele (T) for this SNP could improve the disease resistant of the fish.

Filed studies on some probiotics to minimize hazard effects of prevailing heavy metals contamination for improving immunity and growth performance of Oreochromis niloticus.

AIM: The objective of the present study was to determine the effect of some types of probiotics to minimize the hazard effect of cadmium on Oreochromis niloticus (O. niloticus) and to determine the influence of probiotics on the growth performance and immune status of O. niloticus. METHODS: Fish were divided into four groups, the first one was fed on a diet without any additives (control group), and the second group was fed on diet with the addition of 0.1 from (LC50) of cadmium 32 ppm in water. The third group was fed on a diet containing 1 gm/kg of Lactobacillus acidophilus. The fourth group was fed on a diet containing 1 gm/kg of L. acidophilus with 0.1 addition from (LC50) of cadmium 32 ppm. RESULTS: The experiment lasted about 60 days which resulted in an improvement in growth performance, with a decrease in the number of micronucleus formation in the group which received the probiotic. The group which was affected with cadmium showed decrease in the growth performance with increase in the number of micronucleus formation while the group which received probiotics and treated with cadmium had significant improvement in growth performance and decreased in the number of micronucleus formation. CONCLUSIONS: Probiotics decrease cadmium pollution.

Morphological characterization of the oral cavity of the gilthead seabream (Sparus aurata) with emphasis on the teeth-age adaptation.

Gilthead sea bream with different age groups that collected from Seawater fisheries, Ismailia Governorate, Egypt, were examined by gross anatomy and scanning electron microscopy to assess the morphological characteristics of the oral cavity. Teeth patterns showed that the gilthead sea bream is adapted to the feeding pattern according to age development, as it modified from spiny form teeth in young fishes to obelisk-like teeth and flat dome-like teeth in growing fishes, with differentiation of teeth into three pairs of canine and conical teeth, that later differentiated to small and large flat teeth. With development, the apical pouch also showed morphological differentiation from curve-like in small fishes to Y-letter shape in medium-sized fishes, which later grow to completely covering the lower jaw in grown adult fishes. Tongue papillae, on the other hand, showed some differentiation being smoother in growing fishes than adult ones. Consistent with development differentiation, the palatine region of young fishes appeared separated from the palate by deep palatine fissure, while that the same palatine region was continuous with the palate with a remnant of palatine fissure as shallow groove was noticed in grown big fishes. Taste buds were characterized in the oral cavity of small and large fishes however in large fishes; the taste buds were more prominent especially at the palate and palatine folds. These and other morphological features of the oral cavity and the feeding habits in small and large gilthead sea bream fishes were recorded.

Lead poisoning in Nile tilapia (Oreochromis niloticus): oxidant and antioxidant relationship.

Selenium and vitamin E are very effective antioxidant agents which play important roles in improving and development of aquaculture sector. This study was conducted to determine the protective and treatment effects of vitamin E and selenium against lead toxicity. Administration of both vitamin E and selenium ameliorated the adverse effects of lead acetate toxicity through significant increase in hemoglobin, packed cell volume, RBC count, WBC count, and lymphocytes compared to lead acetate-exposed groups especially after the 10th week. Also, it is revealed that severe decrease of total protein, calcium, phosphorous, and magnesium in lead acetate intoxicated group. On contrary, significant increase of blood parameters upon addition of vitamin E and selenium combined with/without lead. On the other hand, insignificant decreases of sAST, sALT, urea, and creatinine in group fed on vitamin E and selenium, while increase in lead acetate intoxicated group. Lead acetate caused increasing of lipid peroxidation level (malondialdehyde) and decreasing of superoxide dismutase activity and reduced glutathione level. From these results, it is concluded that exposure to lead acetate is considered as hepatotoxic environmental pollutant. Exposure to lead acetate induced significant effects on antioxidant status. Antioxidants (vitamin E and selenium) showed important roles to protect body against lipid peroxidation, which considered as the first step of cell membrane damage, in addition to the improvement of the endogenous antioxidant enzyme activities.

Cloning, characterization, and expression analysis of Toll-like receptor-7 cDNA from common carp, Cyprinus carpio L.

The Toll-like receptor 7 (TLR7) is activated by single strand RNA and RNA-like compounds (imidazoquinoline), and it induces interferon production. We identified and described carp TLR7 cDNA and its mRNA expression. The full-length cDNA of carp TLR7 gene is 3427 bp, encoding 1049 amino acids (AB553573). The similarities of carp TLR7 with zebrafish, rainbow trout, fugu, and human TLR7 were 89.6, 83.4, 80.6 and 74.6%, respectively, at the amino acid sequence level. Furthermore, the expression of TLR7 mRNA was investigated in normal tissues of carp by semi-quantitative RT-PCR analysis. Carp TLR7 expression was exhibited in healthy tissues (kidney, brain, spleen, skin, intestine, muscle, liver, gills and heart) and though the expression level in each tissue varied among healthy fish. Carp TLR7 expression was significantly increased in head kidney stimulated with TLR7 agonist, imiquimod, at 8, 24 and 48 h in vitro when compared to expression in the control group. Moreover, carp head kidney leukocytes produced elevated levels of pro-inflammatory and type 1 interferon cytokine mRNA in response to imiquimod stimulation.