308 research outputs found
Perspectives of University Students and Faculty on remote education experiences during COVID-19- a qualitative study
Owing to COVID-19 the Ministry of Education in the United Arab Emirates mandated educational institutions to shift to remote learning. In this study the perspectives on remote learning, of both students and faculty, from the Science major, in a public university in Dubai have been explored. A qualitative research was conducted through focus group discussions using a semi-structured interview guide. All discussions were recorded and transcribed verbatim. Thematic content analysis was carried out following coding and analyzing content using NVivo 12. Recurrent, emerging and diverging views were identified and represented under themes. Participants believed that altered human interaction was a major consideration in remote learning. Assessments were modified to reduce cheating however increasing students’ accountability and prudent use of questions was suggested as a more effective strategy. Challenges associated with technology, changes to the learning environment, wellbeing and institutional policies were highlighted. Advantages of remote learning included more inclusivity, flexibility, availability of recorded sessions and time efficiency. Also, remote learning had compelled faculty to enhance their technological skills. Including class participation as a graded component of courses, clear institutional guidelines on assessments, use of recordings and methods of communication were recommended. It was evident that students’ stances for learning were based on courses and disciplines, with a preference for synchronous lessons. Culture influenced interaction, assessments, acceptability, and accessibility of remote education. The views from this research will contribute to improving the adoption and outcomes of digital education in higher education in the field of science, while considering the sociocultural influences of the region
Epidemiology of brain tumors in the United Arab Emirates: A National Registry Cross-sectional Study
© 2020 The Author(s). Background: Cancer is the third leading cause of death in the United Arab Emirates (UAE); brain cancer ranks 10th among the cancers, with 2.9% of the primary cancers originating from the nervous system. The epidemiology of brain cancers has not been explored. The unique population dynamics of UAE make it a fertile ground for analyzing the epidemiology of brain cancer. In this study, we aim to look at the frequency patterns and distribution of malignant primary brain tumors in the UAE. Methods: A cross sectional study was carried out using data obtained from the Tawam Hospital Cancer Registry for the years 1984-2017. The sample size included 756 diagnosed cases of malignant primary brain tumors in the UAE. Using SPSS and Excel software, frequencies, mean ages, histological type frequencies, average annual crude incidence rates and average annual age adjusted incidence rates were analyzed. Results: The expatriate population had higher percentage of brain tumors (72%) than the locals. The mean age at diagnosis was 33.48 years (± 21.14 years) with a male to female ratio of 1.69. Diffuse astrocytic and oligodendroglial tumors were the most commonly diagnosed tumors overall. Older adults had more cases of lymphoma while embryonal and ependymal tumors were most commonly seen in younger age groups. The overall average annual crude incidence rate for 2013-2016 for all primary brain tumors was 0.56 per 100,000 population. Conclusion: This is the first cancer registry study in the UAE that describes histological types of primary brain tumors based on the WHO 2016 classification of brain tumors and highlights their incidence rates. Through this study, several patterns of incidence trends for brain tumors in the UAE, according to histological types, sex and age groups have been recognized. Comparative studies would help identify the influence of potential changes in lifestyle, environmental or occupational risk factors on primary brain tumors
Horizontal gene transfer between Wolbachia and the mosquito Aedes aegypti
BACKGROUND: The evolutionary importance of horizontal gene transfer (HGT) from Wolbachia endosymbiotic bacteria to their eukaryotic hosts is a topic of considerable interest and debate. Recent transfers of genome fragments from Wolbachia into insect chromosomes have been reported, but it has been argued that these fragments may be on an evolutionary trajectory to degradation and loss. RESULTS: We have discovered a case of HGT, involving two adjacent genes, between the genomes of Wolbachia and the currently Wolbachia-uninfected mosquito Aedes aegypti, an important human disease vector. The lower level of sequence identity between Wolbachia and insect, the transcription of all the genes involved, and the fact that we have identified homologs of the two genes in another Aedes species (Ae. mascarensis), suggest that these genes are being expressed after an extended evolutionary period since horizontal transfer, and therefore that the transfer has functional significance. The association of these genes with Wolbachia prophage regions also provides a mechanism for the transfer. CONCLUSION: The data support the argument that HGT between Wolbachia endosymbiotic bacteria and their hosts has produced evolutionary innovation
The Hexapeptide and Linker Regions of the AbdA Hox Protein Regulate Its Activating and Repressive Functions
AbstractThe Hox family transcription factors control diversified morphogenesis during development and evolution. They function in concert with Pbc cofactor proteins. Pbc proteins bind the Hox hexapeptide (HX) motif and are thereby thought to confer DNA binding specificity. Here we report that mutation of the AbdA HX motif does not alter its binding site selection but does modify its transregulatory properties in a gene-specific manner in vivo. We also show that a short, evolutionarily conserved motif, PFER, in the homeodomain-HX linker region acts together with the HX to control an AbdA activation/repression switch. Our in vivo data thus reveal functions not previously anticipated from in vitro analyses for the hexapeptide motif in the regulation of Hox activity
Two proteases defining a melanization cascade in the immune system of Drosophila
The melanization reaction is used as an immune mechanism in arthropods to encapsulate and kill microbial pathogens. In Drosophila, the serpin Spn27A regulates melanization apparently by inhibiting the protease that activates phenoloxidase, the key enzyme in melanin synthesis. Here, we have described the genetic characterization of two immune inducible serine proteases, MP1 and MP2, which act in a melanization cascade regulated by Spn27A. MP1 is required to activate melanization in response to both bacterial and fungal infection, whereas MP2 is mainly involved during fungal infection. Pathogenic bacteria and fungi may therefore trigger two different melanization cascades that use MP1 as a common downstream protease to activate phenoloxidase. We have also shown that the melanization reaction activated by MP1 and MP2 plays an important role in augmenting the effectiveness of other immune reactions, thereby promoting resistance of Drosophila to microbial infection
A serpin that regulates immune melanization in the respiratory system of Drosophila
Epithelial tissues facing the external environment are essential to combating microbial infection. In addition to providing a physical barrier, epithelial tissues mount chemical defenses to prevent invasion of internal tissues by pathogens. Here, we describe that the melanization reaction implicated in host defense is activated in the respiratory system, the trachea, of Drosophila. Tracheal melanization can be activated by the presence of microorganisms but is normally blocked by Spn77Ba, a protease inhibitor in the serpin family. Spn77Ba inhibits a protease cascade involving the MP1 and MP2 proteases that activates phenol oxidase, a key enzyme in melanin biosynthesis. Unexpectedly, we found that tracheal melanization resulting from Spn77Ba disruption induces systemic expression of the antifungal peptide Drosomycin via the Toll pathway. Such signaling between local and systemic immune responses could represent an alarm mechanism that prepares the host in case a pathogen breaches epithelial defenses to invade internal tissues
Shavenbaby protein isoforms orchestrate the self-renewal versus differentiation of Drosophila intestinal stem cells
Drosophila Serpin-28D regulates hemolymph phenoloxidase activity and adult pigmentation
In insects the enzyme phenoloxidase (PO) catalyzes melanin deposition at the wound site and around parasitoid eggs. Its proenzyme prophenoloxidase (proPO) is proteolytically cleaved to active phenoloxidase by a cascade consisting of serine proteases and inhibited by serpins. The Drosophila genome encodes 29 serpins, of which only two, Serpin-27A (Spn27A) and Necrotic, have been analyzed in detail. Using a genetic approach, we demonstrate that the so far uncharacterized Serpin-28D (Spn28D, CG7219) regulates the proPO cascade in both hemolymph and tracheal compartments. spn28D is the serpin gene most strongly induced upon injury. Inactivation of spn28D causes pupal lethality and a deregulated developmental PO activation leading to extensive melanization of tissues in contact with air and pigmentation defects of the adult cuticle. Our data also show that Spn28D regulates hemolymph PO activity in both larvae and adults at a different level than Spn27A. Our data support a model in which Spn28D confines PO availability by controlling its initial release, while Spn27A is rather limiting the melanization reaction to the wound site. This study further highlights the complexity of the proPO cascade that can be differentially regulated in different tissues during development
Cellular Immune Response to Parasitization in Drosophila Requires the EBF Orthologue Collier
Drosophila immune response involves three types of hemocytes (‘blood cells’). One cell type, the lamellocyte, is induced to differentiate only under particular conditions, such as parasitization by wasps. Here, we have investigated the mechanisms underlying the specification of lamellocytes. We first show that collier (col), the Drosophila orthologue of the vertebrate gene encoding early B-cell factor (EBF), is expressed very early during ontogeny of the lymph gland, the larval hematopoietic organ. In this organ, Col expression prefigures a specific posterior region recently proposed to act as a signalling centre, the posterior signalling centre (PSC). The complete lack of lamellocytes in parasitized col mutant larvae revealed the critical requirement for Col activity in specification of this cell type. In wild-type larvae, Col expression remains restricted to the PSC following parasitization, despite the massive production of lamellocytes. We therefore propose that Col endows PSC cells with the capacity to relay an instructive signal that orients hematopoietic precursors towards the lamellocyte fate in response to parasitization. Considered together with the role of EBF in lymphopoiesis, these findings suggest new parallels in cellular immunity between Drosophila and vertebrates. Further investigations on Col/EBF expression and function in other phyla should provide fresh insight into the evolutionary origin of lymphoid cells
Invertebrate Post-Segregation Distorters: A New Embryo-Killing Gene
Cytoplasmic incompatibility induced by inherited intracellular bacteria of arthropods, and Medea elements found in flour beetles, are both forms of postsegregation distortion involving the killing of embryos in order to increase the ratio of progeny that inherit them. The recently described peel-zeel element of Caenorhabditis elegans also uses this mechanism; like Medea the genes responsible are in the nuclear genome but it shares a paternal mode of action with the bacteria. The peel-1 gene has now been shown to encode a potent toxin that is delivered by sperm, and rescued by zygotic transcription of the linked zeel-1. The predominance of self-fertilization in C. elegans has produced an unusual distribution pattern for a selfish genetic element; further population and functional studies will shed light on its evolution. The element might also have potential for use in disease control
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