Regulatory Mechanisms, Protein Expression and Biological Activity of Photolyase Gene from Spodoptera littoralis Granulovirus Genome.

One of the most important factor that affects the efficient using of baculoviruses as a biopesticide is their sensitivity to UV irradiation. In this study, a photolyase gene (phr) of 1.4 kbp DNA fragment was cloned and characterized from Spodoptera littoralis granulovirus, an Egyptian isolate (SpliGV-EG1). A sequence of 466 amino acid were deduced when the gene was completely sequenced with a predicted molecular mass of ~ 55 kDa. Transcriptional regulation analyses revealed that phr transcripts were detected early at 6-h post-infection (hpi) and remained detectable until 72 hpi, suggesting their transcriptional regulation from a putative early promoter motif. An approximately ~ 55 kDa protein fragment was expressed from phr-induced bacterial culture and detected by SDS-PAGE and western blotting. In addition, direct exposure to UV irradiation resulted in a twofold decrease in SpliGV-EG1 occlusion bodies activation compared with Spodoptera littoralis nucleopolyhedrovirus (SpliNPV) occlusion bodies which decreased with about 129-fold after exposure to UV irradiation based on median lethal concentration value (LC50). The obtained results suggested that the presence of photolyase gene possibly alters the inactivation of SpliGV-EG1-occluded bodies by UV irradiation. These results support the role and application of the photolyase protein to improve the damaged DNA repair mechanism as well as resistance of SpliGV to UV light inactivation.

Expression of 1B capsid protein of Foot-and-mouth disease virus (FMDV) using baculovirus expression system and its validation in detecting SAT 2- specific antisera.

Foot-and-mouth disease virus (FMDV) is one of the most devastating animal viruses that affect livestock worldwide. The 1B capsid of FMDV has been widely used to detect and confirm the infection. In the present study, the sequence coding for 1B subunit of FMDV capsid was expressed in insect cells using the baculovirus expression system under the polyhedrin (polh) promoter. The expression of 1B capsid protein was validated in the culture filtrate of insect cells using SDS-PAGE and western blotting. The culture filtrate containing recombinant 1B capsid (r1B) was used as a coated antigen in an indirect enzyme-linked immunosorbent assay (ELISA). The antigenicity and specificity of r1B against SAT 2 serotype-specific antibodies were assessed. Our results revealed that a protein concentration as low as 25 ng could detect SAT 2-specific antibodies in ELISA. The results highlight the application of insect cells developed r1B protein in the detection of FMDV. Further studies are required to determine the ability of r1B to detect other FMDV serotypes.

Characterization, cloning, expression and bioassay of vip3 gene isolated from an Egyptian Bacillus thuringiensis against whiteflies.

Throughout the vegetative life of Bacillus thuringiensis, vegetative insecticidal proteins (Vip) are produced and secreted. In the present study, the vip3 gene isolated from Bacillus thuringiensis, an Egyptian isolate, was successfully amplified (2.4 kbp) and expressed using bacterial expression system. The molecular mass of the expressed protein was verified using SDS-PAGE and western blot analysis. Whiteflies were also screened for susceptibility to the expressed Vip3 protein (LC50). In addition, ST50 was determined to assess the kill speed of the expressed Vip3 protein against whiteflies compared to the whole vegetative proteins. The results showed that the potency of whole B. thuringiensis vegetative proteins against whiteflies was slightly higher than the expressed Vip3 protein with 4.7-fold based on LC50 value. However, the ST50 parameter showed no significant difference between both the B. thuringiensis vegetative proteins and the expressed Vip3 alone. The results showed that the vip3 gene was successfully expressed in an active form which showed high susceptibility to whiteflies based on the virulence parameters LC50 and ST50. To our knowledge, this study showed for the first time the high toxicity of the expressed Vip3 proteins of B. thuringiensis toward whiteflies as a hopeful and promising bio-control agent.

Effect of growth hormones on some antioxidant parameters and gene expression in tomato.

Bioregulators have a great effect on vital processes of plant growth and development. Known plant bioregulators include Naphthalene acetic acid (NAA), Indole-3-butyric acid (IBA) and Indole-3-acetic acid (IAA). Natural or synthetic plant bioregulators are organic compounds that affect the physiological processes in the plant, either to control some of these processes or to modify them. For example these bioregulators can affect the nature of the process, either by accelerating or decelerating plant growth, rates of maturation and also by altering the behavior of the plants or their products. Also, enhancement of important nutrients in human diet could be achieved by bioregulators.   This study uses the model crop plant Tomato (Lycopersicon esculentum). Tomato is affected by a group of bioregulators, this group contains compounds which are powerful antioxidants in vitro. The current study aims to find out the effect of some plant bioregulators (IAA, IBA and NAA) on tomato growth, total protein content and enzyme activities of ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT). This study also investigates the effect of the above mentioned bioregulators on the level of RNA expression for SOD, CAT and TPX1 genes. The analytical quantification of target gene expression showed the induced effect of NAA on SOD expression and reducing effect of the other bioregulators (IAA and IBA) on CAT and TPX1 expression. However, at the protein level, we found that IBA and IAA caused a minor effect on total protein content while a significant effect was recorded on the total protein level using NAA. Upon measuring the enzyme activity of ascorbate peroxidase and catalase, we found that both the exogenous NAA and IBA stimulated ascorbate peroxidase activity in tomato while there was no considerable difference detected in IAA treated plants. Also, there was no considerable difference detected in catalase activity of all bioregulator-treated plants compared with the control.