Effect of cortisol on bovine oocytes maturation and further embryonic development after in vitro fertilization

Dissertação de Mestrado, Engenharia Zootécnica, 07 de dezembro de 2018, Universidade dos Açores.A maturação meiótica dos ovócitos e o posterior desenvolvimento embrionário após a fertilização são importantes requisitos fisiológicos para a sobrevivência das espécies. Desta forma, o objetivo do presente estudo foi avaliar os efeitos da hormona relacionada com o stress, cortisol, na maturação nuclear e desenvolvimento embrionário de oócitos bovinos após fecundação in vitro. Esta hormona (C₂₁H₃₀O₅) é um corticosteroide da família de esteroides, produzido pela parte superior da glândula supra-renal libertada quando um organismo está sob stress. Vários estudos demonstraram que o cortisol desempenha um papel vital inibindo as quinases extracelulares reguladas por sinal, necessárias para a progressão da prófase meiótica, essenciais para o início de eventos iniciais de maturação do ovócito de maturação meiótica (retomada da meiose), ovulação e posterior desenvolvimento embrionário. No presente estudo, para avaliar o efeito do cortisol na maturação dos ovócitos bovinos e desenvolvimento embrionário, foram recolhidos um total de 1439 óculos de vacas e novilhas púberes, abatidas em matadouros e maturados in vitro durante 24 horas com diferentes concentrações de cortisol (0 (controlo); 50 μM; 150 μM; 250 μM). Posteriormente, 412 oócitos foram desnudados, corados com aceto-orceína, sendo avaliado o desenvolvimento meiótico. Os outros 1027 foram submetidos à fecundação in vitro (FIV) e cultivados durante 9 dias, sendo avaliados nos dias 2, 6 e 9, para clivagem, mórula e blastocisto, respetivamente. No controlo, 85% dos oócitos atingiram a metáfase II, diminuindo para 49, 32 e 15% para a concentração do cortisol (50, 150 e 250 μM, respetivamente). Para os embriões obtidos a partir dos oócitos submetidos à FIV, no grupo controlo, 28,3 ± 4,8% atingiram o estágio do blastocisto, enquanto que para as concentrações de cortisol esse valor diminuiu para 22,1 ± 5,4%, 15,4 ± 6,0% e 6,5 ± 2,1 % para 50, 150 e 250 μM de cortisol, respetivamente). Os resultados do presente estudo demonstraram claramente que o stress do animal e particularmente altas concentrações de cortisol prejudicam a maturação nuclear bovina, bem como o desenvolvimento embrionário posterior após a FIV.ABSTRACT: Oocyte meiotic maturation and further embryonic development after fertilization is the important physiological requirements for species survival. Herein, the aim of the study was to evaluate the effects of the stressful hormone, cortisol, on the nuclear maturation and embryo development of bovine oocytes after in vitro fertilization (IVF). This hormone (C₂₁H₃₀O₅) is a corticosteroid of the steroid family, produced by the upper part of the adrenal gland released when an organism is stressed. Therefore, several studies demonstrated that cortisol plays a vital role inhibiting the extracellular signal-regulated kinases, necessary for meiotic prophase progression, essential for onset of early events of meiotic maturation oocyte maturation (resumption of meiosis), ovulation and further embryo development. In the present study, to evaluate the effect of cortisol on bovine oocyte maturation and further embryonic development, a total of 1439 immature oocytes were collected from slaughtered cows and matured in vitro for 24 hours with different concentrations of cortisol (0 (control); 50 μM; 150 μM; 250 μM). Afterwards, 412 oocytes were denuded, dyed with aceto-orcein and evaluated for meiotic development. The other 1027 were submitted to IVF and cultured for 9 days, being evaluated on day 2, 6 and 9, for cleavage, morula and blastocyst, respectively. In the control, 85 % of oocytes reached Metaphase II, decreasing to 49, 32 and 15 % for the concentration of the cortisol (50, 150, and 250 μM, respectively). For the embryos, obtained from the oocytes submitted to IVF, in the control group, 28.3 ± 4.8% reached the stage of blastocyst, while for the concentrations of cortisol this value decreased to 22.1 ± 5.4%, 15.4 ± 6.0% and 6.5 ± 2.1% for 50, 150 and 250 μM of cortisol, respectively). Results of the present study clearly demonstrated that animal’s stress and particularly high concentrations of cortisol impair bovine nuclear maturation as well as the further embryonic development after IVF

Prevalence rates of sleep Paralysis among the AUC undergraduate students: an investigation of a hypothesized relation between sleep Paralysis occurrence rates and exam days and the effect of sleep Paralysis on academic performance

This study aimed at finding the prevalence rates of sleep paralysis among the undergraduates of the American University in Cairo. In addition, it tested a hypothesis that the AUC undergraduates will be more likely to experience sleep paralysis during exam days compared to normal days. Furthermore, it investigated whether there is a relation between sleep paralysis and academic performance or not. An online Google form survey was conducted and 170 undergraduate students from the AUC participated in the survey. It was found that 35% of the participants experienced sleep paralysis at least once in their lives. Moreover, even though some participants did report experiencing sleep paralysis more often during or around exam days, sleep paralysis was in general not frequently occurring during exam days as hypothesized. Also, no correlation was found between sleep paralysis and academic performance. This study added to the knowledge available on sleep paralysis among college undergraduates which provides an increased understanding of the nature of sleep paralysis among university undergraduates. Further, it is one of the few studies which investigated the possibility of a correlation between sleep paralysis and academic performance

Conservation and Restoration of the House of Butehamon 21st Dynasty 1054 BC - The Medinet Habu Temple Precinct

Understanding the original materials and techniques used in objects not only provides insights into its history of construction but may also shed light on the nature of past and current deterioration problem

ONLINE APPROXIMATION ASSISTED MULTIOBJECTIVE OPTIMIZATION WITH HEAT EXCHANGER DESIGN APPLICATIONS

Computer simulations can be intensive as is the case in Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). The computational cost can become prohibitive when using these simulations with multiobjective design optimization. One way to address this issue is to replace a computationally intensive simulation by an approximation which allows for a quick evaluation of a large number of design alternatives as needed by an optimizer. This dissertation proposes an approach for multiobjective design optimization when combined with computationally expensive simulations for heat exchanger design problems. The research is performed along four research directions. These are: (1) a new Online Approximation Assisted Multiobjective Optimization (OAAMO) approach with a focus on the expected optimum region, (2) a new approximation assisted multiobjective optimization with global and local metamodeling that always produces feasible solutions, (3) a framework that integrates OAAMO with multiscale simulations (OAAMOMS) for design of heat exchangers at the segment and heat exchanger levels, and (4) applications of OAAMO combined with CFD for shape design of a header for a new generation of heat exchangers using Non-Uniform Rational B-Splines (NURBS). The approaches developed in this thesis are also applied to optimize a coldplate used in electronic cooling devices and different types of plate heat exchangers. In addition many numerical test problems are solved by the proposed methods. The results of these studies show that the proposed online approximation assisted multiobjective optimization is an efficient approach that can be used to predict optimum solutions for a wide class of problems including heat exchanger design problems while reducing significantly the computational cost when compared with existing methods

Investigating Reading Comprehension Problems Encountered by Sudanese Secondary School Students: Teachers Perspective

This study aimed to investigate reading comprehension problems encountered by Sudanese EFL secondary school students. To achieve the purpose of the study, the researcher used an analytical descriptive method and a questionnaire as a tool. The sample of the study consisted of 30 teachers who were randomly selected from Kenana secondary schools in White Nile State, and responded to the items of the questionnaire. The findings of the study showed that Sudanese Secondary School students face problems in reading and answering comprehension questions. The main causes of these problems were attributed to students’ lack of vocabulary and motivation. English language curriculum and lack of teachers’ training were also considered as causes of this difficulty. The researcher suggested some recommendations for both teachers and syllabus designers. As a recommendation for both sides; teachers and students, the researcher recommended that English language teachers should be trained to improve students’ levels in reading comprehension.  Teachers should also motivate their students to have more interest in learning English language. In addition to that, they should encourage their students to read extensively so as to improve their level of comprehension, and syllabus designers should provide good reading material with adequate exercises besides English language literature

The Cruciality of Using Literature to Enhance Reading Comprehension Skills

This paper attempted to shade the light upon “The cruciality of teaching Literature to enhance reading comprehension skills”, is conducted to find out the role and importance of teaching literature in developing comprehension skills in tertiary level. The researcher adopted descriptive analysis method, the population of this study of (30) English language teachers from different Sudanese universities. Date was gathered by questionnaire. The researcher used a statistical package for social studies (SPSS package). The study comes up with followings: Teaching literature in language courses helps students to develop Reading Comprehension skills, teaching literature in reading lessons helps students to develop skimming and scanning techniques, literature presents valuable material to teach reading comprehension lesson, literature is a good way to practice acquiring quick information from the texts, and teaching literature develops students’ interpretative abilities.&nbsp

Ground Improvement Methods Recently Practiced to Solve the Geotechnical Engineering Problems in Bangladesh

The field performance of the foundation systems recently practiced in the soft ground of Khulna region to solve the geotechnical engineering problems is described in this paper. The foundation systems adopted to construct the structures in Khulna Medical College, Khulna University, BIT Khulna and a Six-vent regulator on Passur River at Fakirhat are considered for study. In Khulna Medical College project, a shallow foundation system using Geotextilies at the foundation base was employed, while in Khulna University and BIT Khulna, a foundation system using replacing the soft compressible soil layer by compacted sand was used. The soft compressible soil at the site of the constructed six-vent regulator on Passur River at Fakirhat was improved by the installation of sand piles by drydisplacement method. The performance was measured in terms of the improvement of ground strength and the long-term settlement monitored in the field. It is observed that the performance of the adopted systems is quite satisfactory. However, in some cases the foundation systems do not work as per design and requirements