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Gad, A., J. M. Sánchez, J. A. Browne, L. Nemcova, J. Laurincik, R. Prochazka, and P. Lonergan, "Plasma extracellular vesicle miRNAs as potential biomarkers of superstimulatory response in cattle", Scientific Reports, vol. 10, no. 1: Nature Publishing Group UK, pp. 1–16, dec, 2020. AbstractWebsite

The ability to predict superstimulatory response would be a beneficial tool in assisted reproduction. Using small RNAseq technology, we profiled extracellular vesicle microRNA (EV-miRNA) abundance in the blood plasma of heifers exhibiting variable responses to superstimulation. Estrous synchronized crossbred beef heifers (n = 25) were superstimulated and blood samples were collected from each heifer on Day 7 of consecutive unstimulated (U) and superstimulated (S) cycles. A subset of high (H) and low (L) responders was selected depending on their response to superstimulation and EV-miRNA profiles were analysed at both time-points in each heifer. Approximately 200 known miRNAs were detected in each sample with 144 commonly detected in all samples. A total of 12 and 14 miRNAs were dysregulated in UH vs. UL and in SH vs. SL heifers, respectively. Interestingly, miR-206 and miR-6517 exhibited the same differential expression pattern in H compared to L heifers both before and after superstimulation. Pathway analysis indicated that circadian rhythm and signaling pathways were among the top pathways enriched with genes targeted by dysregulated miRNAs in H vs. L responding heifers. In conclusion, heifers with divergent ovarian responses exhibited differential expression of plasma EV-miRNAs which may be used as a potential biomarker to predict superstimulation response.

El-Rashidy, A. A., G. Waly, A. Gad, A. A. Hashem, P. Balasubramanian, S. Kaya, A. R. Boccaccini, and I. Sami, "Preparation and in vitro characterization of silver-doped bioactive glass nanoparticles fabricated using a sol-gel process and modified Stöber method", Journal of Non-Crystalline Solids, vol. 483: North-Holland, pp. 26-36, 2018. Abstract
Gad, A., S. Abu Hamed, M. Khalifa, A. Amin, A. El-Sayed, S. A. Swiefy, and S. El-Assal, "Retinoic acid improves maturation rate and upregulates the expression of antioxidant-related genes in in vitro matured buffalo (Bubalus bubalis) oocytes", International Journal of Veterinary Science and Medicine, vol. 6, issue 2: Elsevier, pp. 279–285, sep, 2018. AbstractWebsite

Retinoic acid, vitamin A metabolite, plays a role in oocyte development and maturation in different ways including gene expression alteration and/or prohibiting oxidative stress. The objective of this study was to examine the effect of 9-cis-retinoic acid (9-cisRA) on the quality and maturation rate of buffalo oocytes. Cumulus-oocyte complexes (COCs, n = 460) were collected from ovaries of slaughtered buffalos. Varying concentrations of 9-cisRA (0, 5, 50, and 200 nM) were added to the maturation medium, and the following parameters were analyzed: (i) maturation and cleavage rates, (ii) mitochondrial activity and reactive oxygen species (ROS) levels, (iii) expression level of antioxidant-related genes (PRDX1, SOD1, CAT, HOMX1, and GPX4) using RT-qPCR. Maturation rate was significantly improved in 5 nM 9-cisRA oocyte group (95.8{%}, P {\textless} .05) compared to control and other treatment groups (86.7{%} in control group). The same oocyte group exhibited significantly higher mitochondrial membrane potential activity and lower ROS accumulation level compared to other treatment groups. Antioxidant-related genes were up-regulated in oocytes matured with 5 or 50 nM 9-cisRA compared to control and 200 nM 9-cisRA groups. In contrast, 200 nM of 9-cisRA showed a clear down-regulation for antioxidant-related genes except for PRDX1. In conclusion, supplementation of 9-cisRA with a lower concentration (5 nM) to the buffalo oocytes maturation media promotes maturation rate through a protection mechanism that maintains adequate levels of antioxidant-related transcripts and improves mitochondrial activity. However, 9-cisRA has no significant effect on the cleavage rate of the treated oocytes.

Gunawan, A., S. Sahadevan, C. Neuhoff, C. Große-Brinkhaus, A. Gad, L. Frieden, D. Tesfaye, E. Tholen, C. Looft, M. J. Uddin, et al., "RNA deep sequencing reveals novel candidate genes and polymorphisms in boar testis and liver tissues with divergent androstenone levels.", PloS one, vol. 8, issue 5, pp. e63259, 2013. Abstract

Boar taint is an unpleasant smell and taste of pork meat derived from some entire male pigs. The main causes of boar taint are the two compounds androstenone (5α-androst-16-en-3-one) and skatole (3-methylindole). It is crucial to understand the genetic mechanism of boar taint to select pigs for lower androstenone levels and thus reduce boar taint. The aim of the present study was to investigate transcriptome differences in boar testis and liver tissues with divergent androstenone levels using RNA deep sequencing (RNA-Seq). The total number of reads produced for each testis and liver sample ranged from 13,221,550 to 33,206,723 and 12,755,487 to 46,050,468, respectively. In testis samples 46 genes were differentially regulated whereas 25 genes showed differential expression in the liver. The fold change values ranged from -4.68 to 2.90 in testis samples and -2.86 to 3.89 in liver samples. Differentially regulated genes in high androstenone testis and liver samples were enriched in metabolic processes such as lipid metabolism, small molecule biochemistry and molecular transport. This study provides evidence for transcriptome profile and gene polymorphisms of boars with divergent androstenone level using RNA-Seq technology. Digital gene expression analysis identified candidate genes in flavin monooxygenease family, cytochrome P450 family and hydroxysteroid dehydrogenase family. Moreover, polymorphism and association analysis revealed mutation in IRG6, MX1, IFIT2, CYP7A1, FMO5 and KRT18 genes could be potential candidate markers for androstenone levels in boars. Further studies are required for proving the role of candidate genes to be used in genomic selection against boar taint in pig breeding programs.

El-Gendy, E. A., A. Y. Gad, and A. Mostageer, "Sperm-mediated gene transfer in poultry 1. The relationship with cock sperm viability", Arab Journal of Biotechnology, vol. 10, issue 1, pp. 1-12, 2007. Abstract


Sakr, O. G., A. Gad, M. Rodríguez, P. G. Rebollar, and P. Millán, "Superoxide dismutase mimics improves semen quality during chilled preservation of rabbit spermatozoa", Livestock Science, vol. 221: Elsevier, pp. 70-76, jan, 2019. AbstractWebsite

In rabbit farms, artificial insemination is usually undertaken using semen preserved around 18ºC. However, increased reactive oxygen species levels during preservation produce sperm dysfunction. Our aim was to evaluate the effect of adding superoxide dismutase (SOD) antioxidant mimics (Tempo and TempoL) to the extenders of rabbit semen on quality parameters, total lipid peroxidation (LPO) and SOD level. Ejaculates from 12 sexually mature males were diluted with an extender containing 0 (control), 0.5, 1 or 2 mM of Tempo or TempoL, respectively. Semen samples were cooled till 18ºC and stored for 0, 6 or 24 h. Sperm motility, velocity parameters, viability, plasma membrane integrity, SOD activity and level of thiobarbituric acid reactive substances (TBARS) were determined. Results showed that, in general, SOD antioxidant mimics significantly improved sperm motility compared to control after 6 and 24 h storage. Moreover, at 24 h, Tempo treatments showed motility rates higher than 80{%} whilst the control group showed the lowest motility rate among all treatments (58.5{%}, P {\textless} 0.05). Sperm viability showed no significant differences between treatments at 6 h and 24 h of storage. At 24 h, most SOD antioxidant mimics treatments significantly improved both curvilinear and mean velocity parameters, but only Tempo treatments improved linear velocity parameter. Also, SOD mimics protected sperm cells decreasing TBARS concentration at 6 and 24 h compared to 0 h. In conclusion, the addition of SOD antioxidant mimics during conservation at 18ºC and storage of semen until 24 h reduces lipid peroxidation and preserves rabbit semen quality.

a. Gad, K. Schellander, M. Hoelker, and D. Tesfaye, "Transcriptome profile of early mammalian embryos in response to culture environment", Animal Reproduction Science, vol. 134, issue 2010: Elsevier B.V., pp. 76-83, 2012. Abstract


El-Sayed, A., G. Ashour, M. Khalifa, and A. Gad, "Vitrification assessment of buffalo (Bubalus bubalis) oocytes: morphological and molecular aspects", Egyptian J. Anim. Prod, vol. 52, pp. 1-7, 2015. Abstract