The use of nanoparticles in medicine is an attractive proposition. In the present study, zinc oxide and silver nanoparticles were evaluated for their antidiabetic activity. Fifty male albino rats with weight 120 ± 20 and age 6 months were used. Animals were grouped as follows: control; did not receive any type of treatment, diabetic; received a single intraperitoneal dose of streptozotocin (100 mg/kg), diabetic + zinc oxide nanoparticles (ZnONPs), received single daily oral dose of 10 mg/kg ZnONPs in suspension, diabetic + silver nanoparticles (SNPs); received a single daily oral dose of SNP of 10 mg/kg in suspension and diabetic + insulin; received a single subcutaneous dose of 0.6 units/50 g body weight. Zinc oxide and silver nanoparticles induce a significant reduced blood glucose, higher serum insulin, higher glucokinase activity higher expression level of insulin, insulin receptor, GLUT-2 and glucokinase genes in diabetic rats treated with zinc oxide, silver nanoparticles and insulin. In conclusion, zinc oxide and sliver nanoparticles act as potent antidiabetic agents.

This study was carried out to determine the LC50 of zinc oxide nanoparticles (ZnONPs) on Oreochromis niloticus and to investigate the effect of vitamin E and C on hematological and biochemical alterations induced by two sublethal concentrations (1 and 2 mg/L) of ZnONPs. One hundred and eighty fish were used for studying the lethal concentrations of ZnONPs. For sublethal study two hundred and twenty-five males of O. niloticus were equally divided into five groups, control, the second and the third were treated with 1 and 2 mg/L ZnONPs respectively. The fourth and fifth were exposed to the same concentrations of ZnONPs plus vitamins E and C. The results revealed that the 96 h LC50 of ZnONPs was 3.1 ± 0.4 mg/L. The sublethal study revealed the presence of normocytic normochromic anemia in groups (2, 3 and 5) along the experiment period. The 4th group showed normocytic normochromic anemia at the 7th day and microcytic hypochromic anemia at the 15th day. Leukocytosis, heterophilia, lymphopenia and monocytopenia were recorded at the 7th day in all treated groups compared with the normal control. At the 15th day heteropenia, lymphopenia and monocytopenia were reported in all treated groups. A significant increase in the serum levels of alkaline phosphatase, aminotransferases, urea, creatinine and erythrocytic nuclear and morphological abnormalities along the experimental periods in all treated groups compared with the normal control. Serum total protein and albumin levels were significantly decreased at the same period in the same groups. Addition of vitamin E and C to the diet (groups 4 and 5) significantly improved all measured parameters compared with groups (2 and 3) which treated with ZnONPs only.

The Australian intertidal ant, Polyrhachis sokolova lives in mudflat habitats and nests at the base of mangroves. They are solitary foraging ants that rely on visual cues. The ants are active during low tides at both day and night and thus experience a wide range of light intensities. We here ask the extent to which the compound eyes of P. sokolova reflect the fact that they operate during both day and night. The ants have typical apposition compound eyes with 596 ommatidia per eye and an interommatidial angle of 6.0°. We find the ants have developed large lenses (33 µm in diameter) and wide rhabdoms (5 µm in diameter) to make their eyes highly sensitive to low light conditions. To be active at bright light conditions, the ants have developed an extreme pupillary mechanism during which the primary pigment cells constrict the crystalline cone to form a narrow tract of 0.5 µm wide and 16 µm long. This pupillary mechanism protects the photoreceptors from bright light, making the eyes less sensitive during the day. The dorsal rim area of their compound eye has specialised photoreceptors that could aid in detecting the orientation of the pattern of polarised skylight, which would assist the animals to determine compass directions required while navigating between nest and food sources.

We describe the structural organization of the ommatidium in the compound eye of the fiddler crab, Uca vomeris, at both the light- and the electron-microscopy levels. We pay particular attention to the organization of the optical system, the retinular cells, the rhabdom, and of pigment cells. Although the fiddler crab compound eye is of the apposition type, typical for Brachyuran crabs, we identify a number of novel, functionally relevant aspects of ommatidial organization that have not previously been described. The flat corneal facet lenses provide the main focusing power and therefore must contain a gradient of refractive index. Each ommatidium has the typical set of eight retinular cells, with a distal retinular cell R8 lying close to the proximal tip of the crystalline cone. R8 is shaped into four lobes, which are separated by proximal extensions of the four crystalline cone cells and of distal extensions of retinular cells R1-R7. The microvilli in the R8 rhabdom are not aligned in a uniform direction, while the microvilli of the main rhabdom show the typical crustacean pattern of alternating bands of horizontally (R3, R4, R7) and vertically aligned microvilli (R1, R2, R5, R6). We describe in detail the distribution and structural properties of screening pigment granules in the two types of pigment cells and in the retinular cells in the equatorial eye. We discuss the functional significance of this fine-structural organization of the fiddler crab compound eye in relation to visual processing and visual ecology.

Polarisation sensitivity is based on the regular alignment of dichroic photopigment molecules within photoreceptor cells. In crustaceans, this is achieved by regularly stacking photopigment-rich microvilli in alternating orthogonal bands within fused rhabdoms. Despite being critical for the efficient detection of polarised light, very little research has focused on the detailed arrangement of these microvilli bands. We report here a number of hitherto undescribed, but functionally relevant changes in the organisation of microvilli banding patterns, both within receptors, and across the compound eye of fiddler crabs. In all ommatidia, microvilli bands increase in length from the distal to the proximal ends of the rhabdom. In equatorial rhabdoms, horizontal bands increase gradually from 3 rows of microvilli distally to 20 rows proximally. In contrast, vertical equatorial microvilli bands contain 15-20 rows of microvilli in the distal 30 µm of the rhabdom, shortening to 10 rows over the next 30 µm and then increase in length to 20 rows in parallel with horizontal bands. In the dorsal eye, horizontal microvilli occupy only half the cross-sectional area as vertical microvilli bands. Modelling absorption along the length of fiddler crab rhabdoms suggests that (1) increasing band length assures that photon absorption probability per band remains constant along the length of photoreceptors, indicating that individual bands may act as units of transduction or adaptation; (2) the different organisation of microvilli bands in equatorial and dorsal rhabdoms tune receptors to the degree and the information content of polarised light in the environment.

The effects of zinc oxide nanoparticles (ZnONPs) on antioxidants in Nile tilapia muscles and the protective role of vitamins C and E were examined. Two hundred males of Nile tilapia were held in aquaria (10 fishes/aquarium). Fishes were divided into 5 groups: 40 fishes in each group; the first group was the control; the 2nd and 3rd groups were exposed to 1 and 2 mg/L of ZnONPs, respectively; and the 4th and 5th group were exposed to 1 and 2 mg/L of ZnONPs and treated with a (500 mg/kg diet) mixture of vitamin C and E mixture (250 mg/kg diet of each). Muscles were collected on the 7th and 15th day of treatments. Muscle malondialdehyde, reduced glutathione levels, superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GR), glutathione peroxidase (GPx), and glutathione-S-transferase (GST) activities were measured after treatments. Relative quantification of SOD, CAT, GR, GPx, and GST mRNA transcripts was detected in the muscles. Results showed that MDA and GSH concentration; SOD, CAT, GR, GPx, and GST activities; and mRNA expression were significantly decreased in groups exposed to ZnONPs. Vitamins C and E significantly ameliorated the toxic effects of ZnONPs. In conclusion, vitamins C and E have the ability to ameliorate ZnONP oxidative stress toxicity in Nile tilapia.

Abstract

The current study evaluated the hazards of Zinc oxide nanoparticles (ZnONPs) on Nile Tilapia liver and gill antioxidants enzymes activities and antioxidants genes expressions. The ameliorative action of vitamins E and C mixture was investigated. Two hundred males of Nile Tilapia were exposed to one and two mg L −1 of ZnONPs either with or without vitamin C and E mixture for 7 and 15 days. Glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities and gene expression as well glutathione (GSH) and lipid peroxide (LPO) levels were investigated. The results revealed that the exposure to ZnONPs could induce alterations in the liver and gills antioxidants and LPO of Nile Tilapia . Moreover, the mixture of vitamin E and C highly effective in alleviation the toxic effect of ZnONPs.