Mechanism of Incorporation and Repair of Uracil at Highly Transcribed Genes In Saccharomyces Cerevisiae

Recombination and mutagenesis are elevated by high levels of transcription. The correlation between transcription and genome instability is largely explained by the topological and structural changes in DNA and the associated physical obstacles generated by the transcription machinery. However, such explanation does not directly account for the unique types of mutations originating from the non-canonical residues such as uracil, which are also elevated at highly transcribed regions. Apurinic/Apyrimic or Abasic (AP) sites derived from uracil excision, accumulate at a higher rate in actively transcribed regions of the genome in S. cerevisiae and are primarily repaired by base excision repair (BER) pathway. I have demonstrated that transcription-coupled nucleotide excision repair (NER) pathway can functionally replace BER to repair those AP sites located on the transcribed strand much like the strand specific repair of UV-induced pyrimidine dimers. This thesis reveals that the DNA composition can be modified to include higher uracil-content through the non-replicative, repair-associated DNA synthesis. I show here a positive correlation between the level of transcription and the density of uracil residues in the yeast genome indirectly through the mutations generated by the glycosylase that excise undamaged cytosine as well as uracil. The higher uracil-density at actively transcribed regions is confirmed by the long-amplicon qPCR analysis. I also show that the uracil- associated mutations at highly transcribed regions are elevated by the induced DNA damage and reduced by the overexpression of a dUTP-catalyzing enzyme, Dut1, in G1- or G2-phases of the cell cycle. Additional roles of transcription elongation factor Dst1 and RNAPII degradation factor Def1 in AP induced transcription arrest is also revealed. I report that Def1 directs NER to AP lesions on the transcribed strand of an actively transcribed gene but that its function is dependent on metabolic state of the yeast cells. I additionally show that Dst1, a homolog of mammalian transcription elongation factor TFIIS, interferes with NER-dependent repair of AP lesions while suppressing homologous recombination pathway. In summary, this thesis elucidates a novel mechanism of introducing uracil into DNA during damage-induced repair synthesis and provides further insights onto how AP sites on the transcribed DNA strand are repaired

Meeting Demands of Vision 2030 and Globalisation: Some Reforms and Innovations Necessary in Curriculum under Kenyan Sky

The current world is operating in an economy that values creativity and innovation for scientific and technological development. The future seems to be destined for cutting edge research, technology and global competitiveness for the scarce resources. Achieving and sustaining such growth is dependent on robust education and skills development systems that upgrade creativity, innovations and problem solving skills in our youth. In this endeavour, transforming the curriculum to meet the demands of vision 2030 and millennium development goals (MDG’s) become critical under the Kenyan sky. This paper presents and discusses some of the reforms necessary in the Kenyan curriculum that could enable the country transform herself to an economy that is capable of competing at the global level. Keywords: Teacher education, curriculum, creativity, innovativeness, technological developmen

Phytoalexins from crucifers : structures, syntheses and biosyntheses

The search for antifungal secondary metabolites from cruciferous plants exhibiting resistance to pathogenic fungi led to the investigation of Eruca sativa (rocket). Chemical analysis of extracts showed arvelexin (51) as the only inducible component. Bioassay guided isolation (FCC, PTLC) and characterization (NMR, MS) led to the identification of two phytoanticipins, 4-methylthiobutyl isothiocyanate (166) and bis(4-isothiocyanatobutyl)disulfide (167). Compounds 166 and 167 inhibited the germination of spores of Cladosporium cucumerinum in TLC biodetection assays.Next, isotopically labeled compounds containing 2H and 34S at specific sites were synthesized for use in studying of the biosynthetic pathway of crucifer phytoalexins and indolyl glucosinolates. Among the synthesized precursors, [4',5',6',7'-2H4]indolyl-3-[34S]acetothiohydroxamic acid (174a), the first sulfur-34 containing indolyl derivative was synthesized. In addition, non-isotopically labeled compounds (containing 1-methyl, 1-boc and 1-acetyl groups), that is, substrates used for precursor-directed biosynthesis, were also prepared.With the precursors in hand, the biosynthetic pathway(s) and biogenetic relationship between phytoalexins was investigated using the tuberous crucifers, Brassica napus L. ssp rapifera (rutabaga) and B. rapa (turnip), and detached leaves of Erucastrum gallicum (dog mustard). The biosynthetic relationship between indolyl glucosinolates and phytoalexins was investigated in rutabaga and turnip. The indolyl moiety of the phytoalexins cyclobrassinin (28), rutalexin (33), spirobrassinin (34), brassicanate A (43), and rapalexin A (53), as well as indolyl glucosinolates glucobrassicin (70), 4-methoxyglucobrassicin (156), and neoglucobrassicin (199) was confirmed to derive from L-tryptophan (78). The 1-methoxy-containing phytoalexins, erucalexin (38) and 1-methoxyspirobrassinin (35) were shown to derive from indolyl-3-acetaldoxime (112) through 1-methoxyindolyl-3-acetaldoxime (116). The 1-methoxy substituent of neoglucobrassicin was also shown to derive from 1-methoxyindolyl-3-acetaldoxime (116).The incorporation of indolyl-3-acetothiohydroxamic acid (174) into the phytoalexins cyclobrassinin, rutalexin, brassicanate A, rapalexin A, and spirobrassinin, and into the glucosinolate glucobrassicin is reported for the first time. On the other hand, incorporation of 174 into 4-methoxyglucobrassicin and neoglucobrassicin was not detected under current experimental conditions. Cyclobrassinin was incorporated into spirobrassinin among the NH-containing phytoalexins, whereas sinalbin B (31) [biosynthesized from 1-methoxybrassinin (18)] was incorporated into erucalexin and 1-methoxyspirobrassinin. The efficient metabolism of [SC2H3]brassicanal A into [SC2H3]brassicanate A suggested a biogenetic relationship between these two phytoalexins, whereas absence of incorporation of indolyl-3-acetonitrile (49) into rutabaga phytoalexins or indolyl glucosinolates indicated that 49 is not a precursor of these secondary metabolites under the current experimental conditions.The rutabaga and turnip tubers separately metabolized 1-methylindolyl-3-acetaldoxime (170) and 1-methylindolyl-3-acetothiohydroxamic acid (178) into 1-methylglucobrassicin (201); however, no 1-methyl-containing phytoalexins were detected in the extracts. Rutabaga tissues metabolized 1-(tert-butoxycarbonyl)indolyl-3-methylisothiocyanate (180) into 1-(tert-butoxycarbonyl)brassinin (181) and 1-(tert-butoxycarbonyl)spirobrassinin (196), whereas 1-acetylbrassinin (184) was the only detectable metabolic product of 1-acetylindolyl-3-methylisothiocyanate (183) in both rutabaga and turnip root tissues.In conclusion, indolyl-3-acetothiohydroxamic acid (174) seems to be the branching point between brassinin and glucobrassicin. The biosynthetic pathway of NH-containing crucifer phytoalexins was mapped and follows the sequence L-tryptophan, indolyl-3-acetaldoxime, indolyl-3-acetothiohydroxamic acid, brassinin (possibly through indolyl-3-methylisothiocyanate), and other phytoalexins. The biosynthetic pathway of 1-methoxy-containing phytoalexins follows a similar sequence through 1-methoxyindolyl-3-acetaldoxime (biosynthesized from indolyl-3-acetaldoxime)

Design and implementation of a microprocessor based room illumination control system

This paper describes the development of a microprocessor based room illumination control system that offers advantage of improved efficiency in the use of electrical energy and reduced cost of electricity over manually controlled lighting systems. This system is developed to regulate the intensity of light from direct current (DC) bulbs when the presence of a person(s) is detected in the room so that ambient light is always maintained between 135 lux and 300 lux. Lights are however completely turned OFF if the ambient light level is beyond this range. At the heart of this system is an Intel 8085 microprocessor which controls all operations of the system. The infrared and the passive infrared (PIR) sensors are used to detect the occupancy status of the room while the visible light sensor is used to detect the ambient light level in the room. The PIR sensor is mounted at a height of about 2 m which prevents the system from detecting the presence of animals like cats and dogs in the room and therefore avoids turning the lights ON falsely. Analog signals are produced as outputs from the three sensors and are fed to the microprocessor unit (MPU) for processing through the analog-to-digital converter (ADC). The MPU is then capable of controlling all operations and automating the system. The entire hardware functioning is coordinated by a software program written in low level 8085 assembly language and stored in the erasable programmable read only memory (EPROM). Implementing this system improves efficiency in the use of electrical energy and reduces the cost of electricity.Key words: Microprocessor based system, occupancy dependent, illumination control, PIR Sensor, visible light senso

Applying a multilayer construct of social adaptability skills within talent development

Despite this evidence, an individual's Social Adaptability Skills (SAS) and their appropriate deployment are overlooked in Talent Identification and Development models (Vaeyens et al., 2008). Reflecting this importance, the aim of this article is to provide a theoretical model that encompasses the various psychological processes included in (SAS). Our reflection is guided first by the overview of the limits and resources of the current constructs accepted in TID and TDE's. We suggest the need for an integrative model combined in the SAS with the continuity of the athlete's identity as well as the integration of the inevitable situated and dynamical fluctuations. We subsequently examine the relevance of McAdams (2009) framework by inductively exploring meaningful testimonies of elite players transitions

Growth rate of African catfish (Clarias Gariepinus) and plankton diversity in ponds under organic and inorganic fertilization

Aquaculture offers the opportunity for safeguarding local and global food security in the face of declining capture fisheries. However, the form of aquaculture that is commonly practised in Kenya is characterized by the use of agrochemicals such as fertilizers that negatively impact biodiversity especially when effluents from fish ponds drain into water bodies. This study aimed to determine differences in growth rate of Clarias gariepinus, an important aquaculture fish in Kenya, to assess plankton diversity, and to identify phytoplankton species associated with pollution under organic and inorganic fertilization regimens using chicken manure, Diammonium phosphate and urea, respectively. Average growth rate calculated per day was higher in the organically-fertilized ponds at 0.06 cm/day, followed by inorganically-fertilized ponds at 0.05cm/day and then, the control at 0.04 cm/day. Average weight gain was higher in organically-fertilized ponds at 0.08 g/day followed by ponds fertilized with inorganic fertilizer at 0.07 g/day and the control, at 0.06g/day. There were significant differences in growth rate across fertilization regimens (length: F2, 264 = 24.06, p = 0.0399; weight: F2, 264 = 20.89, p = 0. 0457). Specifically, although differences in growth rate of fish in organically and inorganically fertilized ponds were not significant, fish in fertilized ponds were on average, longer and weighed more than those in the control pond. Jaccard’s similarity index for phytoplankton was highest (0.38) between organically fertilized ponds and control but lowest (0.25) between inorganically-fertilized ponds and control. Use of chicken manure produced the highest diversity of zooplankton (Shannon-Weiner’s H in organically-fertilized pond = 1.886; inorganic = 1.044, and control = 0.935). The use of DAP and urea produced the highest proportion of phytoplankton species associated with pollution. These results do not support the commonly reported notion that ponds fertilized using inorganic fertilizers are more productive. Findings suggest that the use of inorganic fertilizers may threaten biodiversity in aquatic ecosystems through the production of toxic algae

Teachers` gender and primary school pupils` achievement in Mathematics in Kenya

This descriptive causal comparative study examined the relationship between teacher’s gender and in primary schools pupils’ performance in mathematics in Kenya. The study objective was to investigate the effect of teachers’ gender on primary schools pupils’ mathematics achievement in Vihiga district Kenya. The study was conducted through an ex-post facto research design. A total of 46 mathematics teachers were sampled from 153 schools. Data was collected using a Mathematics Teacher’s Questionnaire (MTQ). Results of a Mathematics Achievement Test (MAT) were used as a measure of teachers’ contribution towards pupils’ academic achievement. Mathematics education experts reviewed the MTQ for content, face and construct validity. A pilot study was also carried out in 2 primary schools outside the district of study. The data collected was translated into frequency counts which were presented in pie and bar charts. Chi square statistic was then used to establish whether there was a relationship between teachers’ gender and its contribution towards pupils’ achievement in mathematics. The findings of the study showed that there was a significant relationship between teachers` gender and pupils` achievement in primary mathematics. The results of this study suggest that more female teachers be trained and deployed to teach mathematics at upper primary school levels since their contribution towards pupils’ performance is profound. Keywords: teachers` gender, primary school, pupil’s achievement in mathematic

Effects of prescribed physical therapy exercises on blood glucose, metabolic and HbA1c profiles in pre-diabetes at Moi Teaching and Referral Hospital in Uasin Gishu County, Kenya

Objectives: To investigate the metabolic parameters of pre-diabetes and to provide evidence of prescribed physical therapy exercises that can be quantified and reproduced.Design: A controlled experimental studySetting: Moi Teaching and Referral Hospital and physical therapy gymnasium of Moi University orthopaedics and rehabilitation department in Uasin Gishu County, Kenya.Subjects: Two comparison groups, Experimental Group (EG) and Control Group (CG) with each group having the same size of subjects (17 each).Results: Exercise reduces Fasting Blood Glucose (FBG) by 5% and 13%, in 6 and 12 weeks, respectively. It also showed High Density Lipoprotein (HDL) were significantly higher in the experimental than in the control group during post-training (z= -3.20.17, p=0.001). On the other hand, the level of Low-Density Lipoprotein (LDL) decreased in the experimental group during both mid-training and post-training period relative to pre-training (z= -2.908.18, p=0.001). There was a significant reduction of HbA1c (of 3%) after six weeks and an even more marked drop (8%) after 12 weeks in EG compared to CG in which there was no drop in HbA1c levels. High correlation was found between FBG and HbA1c(r=0.95). All parameters at pre, mid and post training were not significantly different between males and females.Conclusion: Prescribed Physical Therapy Exercises (PPTE) exerted improvement on FBG, metabolic and HbA1c profiles in pre-diabetes. The knowledge of how much exercise is needed to impact change in disease progression would inform the prescription of exercise by physiotherapists to their clients

The need for effective study skills under the 21st century: a case of USA and KENYA

Paper presented at the 2nd Strathmore International Mathematics Conference (SIMC 2013), 12 - 16 August 2013, Strathmore University, Nairobi, Kenya.The current world is operating in an economy that values creativity and innovation for scientific and technological development. Education gives people appropriate skills and knowledge they need to address their social problems. Mathematics and Science education is at the centre of this and needs to be at the forefront to connect the present to the future. The fact that a new generation of learners is in our classrooms requiring a paradigm shift in pedagogy is indisputable. Teaching in the same old way and emphasis on examinations, grades, certificates as well as lack of basic facilities have affected learning by generation Y students. As a result, Kenya like the United States of America faces a myriad of problems despite the fact that the youth is a reach reservoir for development. More than 50 per cent of the world's gold reserves, diamond, manganese, chromium, and cobalt are in Africa yet Africans live in the poorest situations imaginable. The United States, despite being the most powerful nation on the planet has, in general, have poor test scores in mathematics if results of international comparative studies are anything to go by. This paper argues in addition to poor teaching methods, strategies, and techniques, the assumption that stu- dents know how to study mathematics once in secondary school, college, and university and the failure to teach the same is partly to blame since year after year, students either drop out, receive poor grades, fail to attend classes and or don't take mathematics seri- ously. Millennials therefore need to be taught study skills in mathematics to ensure quality mathematics learning for creativity and innovativeness in the citizens. This will ensure education empowers Kenya, Africa, and the United States for global competitiveness. In particular, this paper intends to address the following current issues in Kenyan and Unites States schools: 1. Describe the Millennial Student, 2. Ramifications for Kenya and the United States, 3. Kenyan and United States curricula, 4. How to teach effective study skills, 5. What is needed of educators, and 6. What to do in the future.The current world is operating in an economy that values creativity and innovation for scientific and technological development. Education gives people appropriate skills and knowledge they need to address their social problems. Mathematics and Science education is at the centre of this and needs to be at the forefront to connect the present to the future. The fact that a new generation of learners is in our classrooms requiring a paradigm shift in pedagogy is indisputable. Teaching in the same old way and emphasis on examinations, grades, certificates as well as lack of basic facilities have affected learning by generation Y students. As a result, Kenya like the United States of America faces a myriad of problems despite the fact that the youth is a reach reservoir for development. More than 50 per cent of the world's gold reserves, diamond, manganese, chromium, and cobalt are in Africa yet Africans live in the poorest situations imaginable. The United States, despite being the most powerful nation on the planet has, in general, have poor test scores in mathematics if results of international comparative studies are anything to go by. This paper argues in addition to poor teaching methods, strategies, and techniques, the assumption that stu- dents know how to study mathematics once in secondary school, college, and university and the failure to teach the same is partly to blame since year after year, students either drop out, receive poor grades, fail to attend classes and or don't take mathematics seri- ously. Millennials therefore need to be taught study skills in mathematics to ensure quality mathematics learning for creativity and innovativeness in the citizens. This will ensure education empowers Kenya, Africa, and the United States for global competitiveness. In particular, this paper intends to address the following current issues in Kenyan and Unites States schools: 1. Describe the Millennial Student, 2. Ramifications for Kenya and the United States, 3. Kenyan and United States curricula, 4. How to teach effective study skills, 5. What is needed of educators, and 6. What to do in the future