Lysozymes are bacteriolytic peptides that are implicated in the insect nonspecific innate immune responses. In this study, a full-length cDNA encoding a c-type lysozyme from Schistocerca gregaria (SgLys) has been cloned and characterized from the fat body of immune-challenged 5(th) instar. The deduced mature lysozyme is 119 amino acid residues in length, has a calculated molecular mass of 13.4 kDa and an isoelectric point (Ip) of 9.2. SgLys showed high identities with other insect lysozymes, ranging from 41.5% to 93.3% by BLASTp search in NCBI. Eukaryotic in vitro expression of the SgLys ORF (rSgLys) with an apparent molecular mass of ∼16 kDa under SDS-PAGE is close to the calculated molecular weight of the full-length protein. rSgLys displayed growth inhibitory activity against Gram-negative and Gram-positive bacteria. 3D structure modeling of SgLys, based on comparison with that of silkworm lysozyme, and sequence comparison with the helix-loop-helix (α-hairpin) structure of hen egg white lysozyme (HEWL) were employed to interpret the antibacterial potencies. Phylogenetic alignments indicate that SgLys aligns well with insect c-type lysozymes that expressed principally in fat body and hemocytes and whose role has been defined as immune-related. Western blot analysis showed that SgLys expression was highest at 6-12 h post-bacterial challenge and subsequently decreased with time. Transcriptional profiles of SgLys were determined by semi-quantitative RT-PCR analysis. SgLys transcript was upregulated at the highest level in fat body, hemocytes, salivary gland, thoracic muscles, and epidermal tissue. It was expressed in all developmental stages from egg to adult. These data indicate that SgLys is a predominant acute-phase protein that is expressed and upregulated upon immune challenge.

No abstract

Abstract. The ability of biocontrol agents to overcome the immune defense of pests is a crucial issue. This is the first study of lysozyme activity as an inducible humoral component of the defense of Schistocerca gregaria, which depends on the recognition of the elicitor molecules of pathogens and not on epidermal wounding or a spiking effect. The level of lysozyme activity in fat body, haemocytes and haemolymph plasma of naïve and immunologically challenged 5 th instar S. gregaria was evaluated using the zone of inhibition test against Micrococcus lysodeikticus. Various Gram-positive and Gram-negative bacteria as well as peptidoglycans (PGN) and lipopolysacchrides (LPS) of bacterial cell walls induce and increase in the level of lysozyme activity. Escherichia coli induced an increase in the level of activity of lysozyme in the fat body, haemocytes and plasma, but not in mid gut epithelium, 6-12 h after an immunological challenge and then it decreased to the constitutive level after 72 h. This study revealed that in S. gregaria there is a constitutive and a bacteria-inducible level of lysozyme activity, which protects it against infection by both Gram-negative and Gram-positive bacteria.

We measured in a comet assay the damage of DNA in the hemocytes of various stages of the grasshopper Schistocerca gregaria after exposing them to various doses of Cd and Pb in the food. The mechanisms of Cd and Pb toxicity for grasshopper are discussed. The accumulation of heavy metals and stage of the insect may play important roles in causing the DNA damage. S. gregaria may be considered a valuable bioindicator for evaluation the genotoxicity of environmental pollutants.

Radon concentrations have been measured using Sealed Can Technique with CR-39 detector for twenty collected samples from Hamash gold mine area, South Eastern Desert of Egypt. This area is one of the most important areas of gold-bearing granites in Arabian Nubian Shield and is being used as a gold mine. The average values of radon concentrations, the exhalation rates, annual effective doses, and working levels are found to be 27.18 ± 0.13 kBqm-3 , 3.27 ± 0.03 Bqm-2 h-1 , 686.27 ± 5.15 mSvy-1 and 2.94 ± 0.02 respectively. The results indicate that the radon concentrations in all samples are higher than the recommended world limit given by ICRP and IAEA. The present study can be used to assess any changes in the radioactive background and any harmful radiation effect on the human in this area. Finally, the obtained data are useful when building a radioactivity atlas of radon for Hamash gold mine and its surrounding region.

No abstract

No abstract

The waste products of the fertilizer industry such as heavy metals, but especially phosphates and sulphates, are a serious problem that influences the structure and functioning of ecosystems. The levels of Cd, Pb, Zn, Cu, sulphates and phosphates were measured in soil samples from four sites: a control and sites that were 1, 3 and 6 km (sites A-C) away from the Abu-Zaabal Fertilizer Company. Oxidative stress markers (protein carbonyls, lipid peroxides), antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), polyphenoloxidase (PPO) and ascorbate peroxidase (APOX)) were evaluated in the tissues of Aiolopus thalassinus, collected from the corresponding sites. The highest concentrations of Cu and Zn were found in the soil from site A. The level of protein carbonyls in the brain, thoracic muscles and gut of the males and females from sites A, B and C were 11.82, 4.38, 5.97 (males) and 19.04, 16.65, 7.79 (females) times higher, respectively, compared to the individuals from the control site. Lipid peroxides levels in both sexes were significantly correlated with the distance from the source of the contamination. In the brain, thoracic muscles and gut of the males and females collected from site A, the level of lipid peroxides were 15.41, 23.49, 11.50 (males) and 25.36, 11.34, 15.37 (females) times higher compared to the values of the control animals. The activities of SOD, PPO, CAT and APOX were significantly affected by the environmental pollutants. The enzymatic and non-enzymatic oxidative markers in the Aiolopus thalassinus, a common insect species that inhabits various ecosystems, can also be used as a relevant biomarker of the pollution that is caused by the fertilizer industry.