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- ItemAgrobacterium Mediated Transfer Of Bacillus Thuringiensis 6E Cry Gene To Ixora Odorata(University of Peradeniya, 2003) Bamunuarachchige, T. C.Ixora species are quite popular among landscape architects and gardeners as hedge plants and potted ornamentals. However, infestations by pests such as Ixora leaf webber, flower webber, green horned caterpillar and looper caterpillar have become a threat to the commercial exporter, especially with strict quarantine regulations under which presence of a single pest egg may spell disaster. Most chemical methods adopted have hazardous effects on the environment and other beneficial insects and therefore, are unpopular among the buyers. As an alternative Ixora odorata var. vulcan was transformed with the cry gene of Bacillus thuringiensis strain 6e by Agrobacterium mediated gene transfer. In the process, an effective plant regeneration procedure and a gene transfer system were developed. The cry gene of Bacillus thuringiensis strain 6e was isolated, purified and cloned into the Xbal site of the T-DNA region of the Agrobacterium vector pLG121Hm via an adapter. Recombinant pLG121Hm was transferred to Agrobacterium strain LBA4404 by electroporation. Positive cry clones were confirmed by Dot blot analysis of the plasmid DNA (extracted from the electroporated strains) with Dig labeled cry probe. In vitro grown Ixora odorata shoot tips (2cm) were co-cultivated with LBA4404, harboring the Bt 6e cry cloned binary vector pLG121Hm. Co-cultivated explants were transferred to shoot multiplication medium ('/2 MS with 2mg/l BAP and 500mg/l cefotaxime) and incubated at 25001ux with a 16h photoperiod. After 4 weeks the axillary shoots were screened on selective medium (Vz MS supplemented with 200mg/l hygromycin). Hygromycin positive plants were used for the PCR analysis and Southern blot analysis. PCR analysis of the putative transformants, carried out with gits specific primers, produced the expected 1.680kb fragment in all the hygromycin positive transformants. Southern blot analysis of these with the Dig labeled Bt 6e cry probe produced positive results. The positive results of both, the PCR analysis and the Southern blot confirmed genomic integration of the Bt 6e cry gene. The transformation efficiency was 20% for the shoot tips whereas it was 40% and 30% for callus and leaf disk transformations respectively but the inability of proper regeneration made both these techniques redundant.
- ItemTeaching environment related activities at key stage one to help children in developing science process skills to attain scientific literacy in future(University of Peradeniya, 2006) Vitharana, P. R. K. A.Today we live in a world filled with scientific innovations due to the advancement of science and technology. Therefore society is complex and rapidly changing than ever before. In order to face the dynamic nature of the 21ˢᵗ century, an individual should possess multiple skills. The developed countries like USA are aiming to produce scientifically literate citizens to succeed challenging situations in the world. Although we are a developing nation we have to face the global society. However, this cannot be achieved within one or two years and it should start from primary level. According to the primary education reforms introduced in 1997, the primary - cycle of education has been divided into three key stages as key stage one — grades 1 and 2, key stage two ~ grades 3 and 4 and key stage three — grade five. Primary curriculum consists of four main subjects and science is integrated in Environment Related Activities (ERA.) The aim of this study was to help children in key stage one to develop science process skills through the subject ERA, that are required to be a Scientifically literate adult in future. In order to achieve the aim of the study it was conducted in three phases. In the first phase data were collected relating to ERA using classroom observation, interviews and diagnostic questionnaire. In the classroom observation twelve teachers from three schools were observed while teaching ERA and detailed fieldnotes were prepared for each lesson. With the help of the fieldnotes detailed transcripts were made with the objective of understanding the real situation in the classrooms. During the second phase, activities were planned in different themes of ERA to develop process skills of children. In the third phase those activities were piloted in three selected classrooms. Classroom observation was conducted and fieldnotes were prepared. The necessary improvements were made with the data obtained from observation and the feedback obtained from teachers. Data obtained from different sources were analysed and identified the weaknesses in teaching ERA, the types of activities suitable for developing process skills and how children developed process skills through suggested activities. It was evident from the study that many teachers had difficulties in teaching sciencerelated components of ERA due to the lack of subject matter knowledge and it led children to develop misconceptions. The students’ active participation, which is expected in the student-centred teaching, was not observed in most of the classrooms. Almost all the teachers had weaknesses in the area of professional skills. Among the most prominent of those were the introducing lessons, questioning, planning lessons, organizing groupwork and use of teaching aids. 85% of teachers were not competent in developing process skills of children especially due to the weaknesses in professional skills. Children enjoyed and actively participated in introduced activities. Children developed process skills when they engaged in simple activities with the proper guidance of the teacher. Teachers’ responses towards suggested activities indicated that children were very interested in learning through such activities and teachers motivated children to be inquisitive and investigative. Children in key stage one developed misconceptions due to the limited science background of teachers. Although there were number of Opportunities in the ERA syllabus to develop science process skills of students, they were rarely given proper guidance for that which is required to be a scientifically literate adult in future. The subject matter knowledge as well as the professional skills of primary teachers should be strengthened through workshops, allowing them to actively involve in activities where they could understand their own misconceptions and weaknesses.
- ItemTaxonomy and natural history of bees in selected areas of Sri Lanka(University of Peradeniya, 2004) Karunaratne, InokaPrior to this study, taxonomic work on bees of Sri Lanka had been conducted entirely by overseas scientists commencing in 1897 and leading to the Smithsonian Surveys (1975-1986). These studies have documented 137 bee species in 27 genera. Information on their natural history is completely lacking and only a few specimens have been deposited in Sri Lanka. In the present study (a) bees collected from several districts, agroecological regions and habitats were identified (b) their floral relationships and nesting habits were recorded, (c) the subfamily Nomiinae was reviewed, (d) and bees diversity was determine in selected sites. A total of 137 bee species in 35 genera and 3 families were recorded. These included 20 previously unrecorded species and 5 genera and a species new to Science. Based on the location of the 29 collection sites, the Low Country Dry Zone, middle peneplain, and the agricultural habitats harboured the highest number of species. Floral hosts consisted of 167 species in 115 genera and 44 families. Weeds were the most preferred hosts (129 spp.) followed by crops and trees. Flowers of 6 naturalized plant species attracted an unusual number (> 20 species) of bees. According to pollen relationships, 131 bee species are generalists and 7 species are pollen specialists. Twelve species of bees are buzz pollinators of crops whose pollen is concealed in anthers. Pollen from 69 floral hosts in 27 plant families when microscopically examined and grouped into 12 pollen classes. Several stem nesting (16 spp.), ground nesting (13 spp.) and hive building (4 spp.) bees were recorded, Certain species were recorded only from their nests. Review of the subfamily Nomiinae resulted’ in 22 species in 11 genera. Sampling in different locations/habitats of the Knuckles Forest Reserve gave the highest Shannon Diversity Index for agricultural habitat in the Semi Evergreen Climatic Zone. Descriptions. identification keys, locality details and floral hosts are given for the 137 bee species recorded.
- ItemTaxonomy and distribution of hard ticks (Ixodidae) in selected areas in Sri Lanka and significance of the transmission of tick borne diseases(University of Peradeniya, 2014) Liyanaarachchi, D. R.Ticks are the most important ecto parasites of animals that cause great economic losses in several ways including the transmission of diseases. They are constantly having interactions with their natural environment affecting the risk of infection by tick-borne pathogens. Polymerase chain reaction is used to identify causative agents of tick borne diseases.The objectives of this study were to assess the distribution, host preference of tick species on domestic and wild animals and in humans of Sri Lanka providing detail description of taxonomical characters of each adult male and female tick species collected from this study with identification keys to all tick species reported in Sri Lanka. Moreover, to assess the questing tick diversity in forests and domestic environments and their abundance in forest area in Kandy district in relation to ambient temperature, relative humidity and rain fall.Further, to identify tick vectors for spotted fever and Babesia canis. Ticks were collected from animals by field visits, wild life parks, animal clinics, and through civilians. Flagging method was . carried out to collect questing ticks from Randenigala and Hantana forests and adjoining pastures, also from pastures in villages. Moreover, ticks infesting in human body were collected from Kandy district.Twenty six species were identified infesting on animals and questing on ground. PCR was conducted to spotted fever and B. canis. Taxonomical characters of adult tick species were illustrated and identification keys were prepared. Some species showed host preference and number of tick species on animals was higher than recorded. Ticks had expanded their geographical boundaries and host range. Dermacentor auratus, Haemaphysalis turturis, H aculeata, H hystricis, and H kyasanurensis , which were previously recorded only on wild animals were recorded on domestic animals. Immature D. auratus and Amblyomma testudinarium were abundant on humans and questing on human habitats . Spotted fever was positive from A. testudinarium, A. clypeolatum, A. javanense of wild animals and Rhipicephalus sanguine us of a dog, following Babesia canis from R. microplus and R. sanguineus. Wild animals could serve as natural hosts for zoonoses and dogs are significant agents to spread ticks between wild and domestic environments. This gives an alarming warning that even pathogens of diseases which unidentified yet in Sri Lanka could be introduced to humans via these animals.
- ItemSynthesis of monomers and polymers based on metal [Pd(II), Pt(II). Ni(II) and Ci(II) functionalised 3,4- Ethylenedioxythiophene complexes and their characterization(University of Peradeniya, 2010) Velauthamurty, KuhamoorthyRuthenium, palladium and platinum metals with phosphine ligands are known to have applications in various fields of catalysis, including hydrogenation, isomerization and hydroformylation reactions. The application of metal phosphine and metal-cyclam functionalised EDOT complexes in some exciting new areas currently opening up to inorganic chemists, for example modified electrodes and conducting polymers. Functionalisations of electrodes with the redox—active and catalytically active metal complexes are of particular interest, since these have potential applications in sensing, electrocatalysis and especially in electrochromics. More recently, a range of new EDOT derivatives functionalised with phosphine ligands, either pendant from the ethylene bridge (59 and 63) or attached directly to the thiophene 2- position (50) were investigated. Stable Pd(I), Pt(I) and Ru(II) complexes with these ligands were prepared. Normally tetraazamacrocycle complexes of 3d metals are electrocatalytically active. As such the synthesis and characterization of EDOT derivatives functionalised with 1,4,8,11-tetraazacyclo tetradecane (cyclam) ligand pendant to the ethylene bridge and prepared stable Cu(II) and Ni(II) complexes with these ligands were investigated. Further stable Pt(II), Pd(II) and Ru(II) bis-EDOT derivatives functionalized with phosphines (69) were prepared. Interestingly these complexes succeed in making copolymers containing intact complexes, whereas the corresponding EDOT complexes failed to give the polymer. Using the co-polymerization technique, all the complexes of copolymers were prepared. The functionalised PEDOT copolymer films were formed using electrolyte solutions containing functionalised EDOT complexes and EDOT (1:5 mole ratio; 0.01 M total monomer concentration), using repetitive scan cyclic voltammetry, on Pt, G.C, Au and ITO coated glass electrodes. The copolymer was characterized by using electrochemical methods such as cyclic voltammetry, electrochemical impedance spectroscopy, X-Ray photoelectron spectroscopy, X-Ray fluorescence spectroscopy, and Electron dispersive spectroscopy. These characterization techniques established that the polymers made in the presence of [MCI ₂(50)₂] consisted only of poly-(3,4-ethylenedioxythiophene), whereas polymers made in the presence of other meta! complexes were genuine co-polymers containing Ru(II), Pd(Il, Pt(lI) complexes. This represents a new technique for depositing catalytically-active metal complexes of functionalised PEDOT-phosphine and PEDOT-cyclam matrices, for instance, on array supports for high-throughput synthetic devices or microfluidic systems. The successful polymerization of metal-cyclam functionalised EDOT further opens up the possibility of using the electrogenerated polymers as electrocatalysts in the reduction of alkyl halides. Also it was found that this method affords a better control of the metals concentration in the polymer matrix.