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Papers by Asmaa El-Shershaby

Research paper thumbnail of Detection of immune effects of the Mannheimia haemolytica gamma irradiated vaccine in sheep

Veterinary Research Communications

Research paper thumbnail of Comparative assessment of homemade ELISA and lateral flow assay (LFA)in the rapid, specific and sensitive detection of SARS-CoV-2 anti-nucleocapsid protein in sera of Egyptian patients

Journal of Immunoassay and Immunochemistry

Research paper thumbnail of Assessment of specific human antibodies against recombinant SARS-CoV-2 receptor binding domain by rapid in-house ELISA

Human Antibodies

BACKGROUND: The recently emerged SARS-CoV-2 caused a global pandemic since the last two years. Th... more BACKGROUND: The recently emerged SARS-CoV-2 caused a global pandemic since the last two years. The urgent need to control the spread of the virus and rapid application of the suitable health measures raised the importance of available, rapid, and accurate diagnostic approaches. OBJECTIVE: The purpose of this study is to describe a rapid in-house optimized ELISA based on the expression of the receptor binding domain (RBD) of the SARS-CoV-2 spike protein in a prokaryotic system. METHODS: We show the expression of the 30 kDa recombinant SARS-CoV-2 RBD-6×His in five different E. coli strains (at 28∘C using 0.25mM IPTG) including the expression strain E. coli BL21 (DE3) Rosetta Gami. SARS-CoV-2 rRBD-6×His protein was purified, refolded, and used as an antigen coat to assess antibody response in human sera against SARS-CoV-2 infection. RESULTS: The assessment was carried out using a total of 155 human sero-positive and negative SARS-CoV-2 antibodies. The ELISA showed 69.5% sensitivity, 88...

Research paper thumbnail of Functional diversification of tomato HsfA1 factors is based on DNA binding domain properties

Gene, 2019

Let K be a field which is complete for a discrete valuation. We prove a logarithmic version of th... more Let K be a field which is complete for a discrete valuation. We prove a logarithmic version of the Néron-Ogg-Shafarevich criterion: if A is an abelian variety over K which is cohomologically tame, then A has good reduction in the logarithmic setting, i.e. there exists a projective, log smooth model of A over O K. This implies in particular the existence of a projective, regular model of A, generalizing a result of Künnemann. The proof combines a deep theorem of Gabber with the theory of degenerations of abelian varieties developed by Mumford, Faltings-Chai et al.

Research paper thumbnail of Characterization of subclass A1 heat stress transcription factors in tomato

Heat stress transcription factors (Hsfs) have an essential role in heat stress response (HSR) and... more Heat stress transcription factors (Hsfs) have an essential role in heat stress response (HSR) and thermotolerance by controlling the expression of hundreds of genes including heat shock proteins (Hsps) with molecular chaperone functions. Hsf family in plants shows a striking multiplicity, with more than 20 members in many species. In Solanum lycopersicum HsfA1a was reported to act as the master regulator of the onset of HSR and therefore is essential for basal thermotolerance. Evidence for this was provided by the analysis of HsfA1a co-suppression (A1CS) transgenic plants, which exhibited hypersensitivity upon exposure to heat stress (HS) due to the inability of the plants to induce the expression of many HS-genes including HsfA2, HsfB1 and several Hsps. Completion of tomato genome sequencing allowed the completion of the Hsf inventory, which is consisted of 27 members, including another three HsfA1 genes, namely HsfA1b, HsfA1c and HsfA1e. Consequently, the suppression effect of the...

Research paper thumbnail of The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato

Plant, cell & environment, Jan 6, 2018

Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as cen... more Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as central regulators of heat stress (HS) response in tomato (Solanum lycopersicum). HsfA1a regulates the initial response, and HsfA2 controls acquired thermotolerance. HsfB1 is a transcriptional repressor but can also act as co-activator of HsfA1a. Currently, the mode of action and the relevance of the dual function of HsfB1 remain elusive. We examined this in HsfB1 overexpression or suppression transgenic tomato lines. Proteome analysis revealed that HsfB1 overexpression stimulates the co-activator function of HsfB1 and consequently the accumulation of HS-related proteins under non-stress conditions. Plants with enhanced levels of HsfB1 show aberrant growth and development but enhanced thermotolerance. HsfB1 suppression has no significant effect prior to stress. Upon HS, HsfB1 suppression strongly enhances the induction of heat shock proteins due to the higher activity of other HS-induced Hs...

Research paper thumbnail of The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato

Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as cen... more Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as central regulators of heat stress (HS) response in tomato (Solanum lycopersicum). HsfA1a regulates the initial response, and HsfA2 controls acquired thermotolerance. HsfB1 is a transcriptional repressor but can also act as co-activator of HsfA1a. Currently, the mode of action and the relevance of the dual function of HsfB1 remain elusive. We examined this in HsfB1 overexpression or suppression transgenic tomato lines. Proteome analysis revealed that HsfB1 overexpression stimulates the co-activator function of HsfB1 and consequently the accumulation of HS-related proteins under non-stress conditions. Plants with enhanced levels of HsfB1 show aberrant growth and development but enhanced thermotolerance. HsfB1 suppression has no significant effect prior to stress. Upon HS, HsfB1 suppression strongly enhances the induction of heat shock proteins due to the higher activity of other HS-induced Hsfs, resulting in increased thermotolerance compared with wild-type. Thereby, HsfB1 acts as co-activator of HsfA1a for several Hsps, but as a transcriptional repressor on other Hsfs, including HsfA1b and HsfA2. The dual function explains the activation of chaperones to enhance protection and regulate the balance between growth and stress response upon deviations from the homeostatic levels of HsfB1.

Research paper thumbnail of Detection of immune effects of the Mannheimia haemolytica gamma irradiated vaccine in sheep

Veterinary Research Communications

Research paper thumbnail of Comparative assessment of homemade ELISA and lateral flow assay (LFA)in the rapid, specific and sensitive detection of SARS-CoV-2 anti-nucleocapsid protein in sera of Egyptian patients

Journal of Immunoassay and Immunochemistry

Research paper thumbnail of Assessment of specific human antibodies against recombinant SARS-CoV-2 receptor binding domain by rapid in-house ELISA

Human Antibodies

BACKGROUND: The recently emerged SARS-CoV-2 caused a global pandemic since the last two years. Th... more BACKGROUND: The recently emerged SARS-CoV-2 caused a global pandemic since the last two years. The urgent need to control the spread of the virus and rapid application of the suitable health measures raised the importance of available, rapid, and accurate diagnostic approaches. OBJECTIVE: The purpose of this study is to describe a rapid in-house optimized ELISA based on the expression of the receptor binding domain (RBD) of the SARS-CoV-2 spike protein in a prokaryotic system. METHODS: We show the expression of the 30 kDa recombinant SARS-CoV-2 RBD-6×His in five different E. coli strains (at 28∘C using 0.25mM IPTG) including the expression strain E. coli BL21 (DE3) Rosetta Gami. SARS-CoV-2 rRBD-6×His protein was purified, refolded, and used as an antigen coat to assess antibody response in human sera against SARS-CoV-2 infection. RESULTS: The assessment was carried out using a total of 155 human sero-positive and negative SARS-CoV-2 antibodies. The ELISA showed 69.5% sensitivity, 88...

Research paper thumbnail of Functional diversification of tomato HsfA1 factors is based on DNA binding domain properties

Gene, 2019

Let K be a field which is complete for a discrete valuation. We prove a logarithmic version of th... more Let K be a field which is complete for a discrete valuation. We prove a logarithmic version of the Néron-Ogg-Shafarevich criterion: if A is an abelian variety over K which is cohomologically tame, then A has good reduction in the logarithmic setting, i.e. there exists a projective, log smooth model of A over O K. This implies in particular the existence of a projective, regular model of A, generalizing a result of Künnemann. The proof combines a deep theorem of Gabber with the theory of degenerations of abelian varieties developed by Mumford, Faltings-Chai et al.

Research paper thumbnail of Characterization of subclass A1 heat stress transcription factors in tomato

Heat stress transcription factors (Hsfs) have an essential role in heat stress response (HSR) and... more Heat stress transcription factors (Hsfs) have an essential role in heat stress response (HSR) and thermotolerance by controlling the expression of hundreds of genes including heat shock proteins (Hsps) with molecular chaperone functions. Hsf family in plants shows a striking multiplicity, with more than 20 members in many species. In Solanum lycopersicum HsfA1a was reported to act as the master regulator of the onset of HSR and therefore is essential for basal thermotolerance. Evidence for this was provided by the analysis of HsfA1a co-suppression (A1CS) transgenic plants, which exhibited hypersensitivity upon exposure to heat stress (HS) due to the inability of the plants to induce the expression of many HS-genes including HsfA2, HsfB1 and several Hsps. Completion of tomato genome sequencing allowed the completion of the Hsf inventory, which is consisted of 27 members, including another three HsfA1 genes, namely HsfA1b, HsfA1c and HsfA1e. Consequently, the suppression effect of the...

Research paper thumbnail of The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato

Plant, cell & environment, Jan 6, 2018

Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as cen... more Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as central regulators of heat stress (HS) response in tomato (Solanum lycopersicum). HsfA1a regulates the initial response, and HsfA2 controls acquired thermotolerance. HsfB1 is a transcriptional repressor but can also act as co-activator of HsfA1a. Currently, the mode of action and the relevance of the dual function of HsfB1 remain elusive. We examined this in HsfB1 overexpression or suppression transgenic tomato lines. Proteome analysis revealed that HsfB1 overexpression stimulates the co-activator function of HsfB1 and consequently the accumulation of HS-related proteins under non-stress conditions. Plants with enhanced levels of HsfB1 show aberrant growth and development but enhanced thermotolerance. HsfB1 suppression has no significant effect prior to stress. Upon HS, HsfB1 suppression strongly enhances the induction of heat shock proteins due to the higher activity of other HS-induced Hs...

Research paper thumbnail of The repressor and co-activator HsfB1 regulates the major heat stress transcription factors in tomato

Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as cen... more Plants code for a multitude of heat stress transcription factors (Hsfs). Three of them act as central regulators of heat stress (HS) response in tomato (Solanum lycopersicum). HsfA1a regulates the initial response, and HsfA2 controls acquired thermotolerance. HsfB1 is a transcriptional repressor but can also act as co-activator of HsfA1a. Currently, the mode of action and the relevance of the dual function of HsfB1 remain elusive. We examined this in HsfB1 overexpression or suppression transgenic tomato lines. Proteome analysis revealed that HsfB1 overexpression stimulates the co-activator function of HsfB1 and consequently the accumulation of HS-related proteins under non-stress conditions. Plants with enhanced levels of HsfB1 show aberrant growth and development but enhanced thermotolerance. HsfB1 suppression has no significant effect prior to stress. Upon HS, HsfB1 suppression strongly enhances the induction of heat shock proteins due to the higher activity of other HS-induced Hsfs, resulting in increased thermotolerance compared with wild-type. Thereby, HsfB1 acts as co-activator of HsfA1a for several Hsps, but as a transcriptional repressor on other Hsfs, including HsfA1b and HsfA2. The dual function explains the activation of chaperones to enhance protection and regulate the balance between growth and stress response upon deviations from the homeostatic levels of HsfB1.