Judul: Cloning Trehalose Synthase Gene And Its Expression In Arabidopsis thaliana
Abstrak: Trehalose is a well known as biological stabilizer functioning as stress protecting agent. It is ubiquitously found in bacteria, fungi, invertebrates, and certain desert-adapted resurrection plants such as Selaginella. In most flowering plants, trehalose is synthesized in amounts nearing the detection limit. Gene(s) encoding trehalose-metabolizing enzymes from E.coli, trehalose synthase and trehalose phosphate phosphatase (OtsA and or OtsB) and the same gene from yeast (TPS1 and or TPP) have been introduced to plants and increased stresses resistance, yet resulted in phenotypic defect, due to accumulation of its intermediate product, trehalose-6-phosphate (T6P). T6P increases along with the increase of trehalose level. This research was aimed to find out if introducing trehalose synthase gene (TreS) which does not produce T6P which prevent phenotypic defect resulted from trehalose accumulation, and whether the presence of TreS in plant improves plant resistance to stresses. The use of TreS as an alternative among non toxic selectable markers was also assessed. For this reason, genes encoding trehalose synthase originated from Thermobifida fusca (TfTreS) and originated from Mycobacterium tuberculosis (MtTreS) had been cloned into plant expression vector (pBIN1935S). TfTreS was isolated from T. fusca using PCR and was inserted to pGemT for sequencing. DNA sequent analysis of the 2 clones, TfTreS within pGemT were identical to the published data yet several silent point mutations occured. TfTreS from these clones were inserted into pBIN19 with CaMV35S promoter. It has been successfully transferred to Arabidopsis thaliana via Agrobacterium mediated transformation. MtTreS readily available in pBlunt TOPO II, was exiced from the plasmid and was inserted to pBin1935S, and transferred to Arabidopsis in the same manner, but it has not been successfully transferred to the plant.
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Judul: Ekspresi Gen Penyandi Asam δ-aminolevulinat Sintase dari Rhodobacter sphaeroides pada Arabidopsis thaliana
Abstrak: Sintesis prekursor senyawa tetrapirol asam δ-aminolevulinat (ALA) di tanaman dimulai dari glutamat dan merupakan biosintesis tergantung pada tRNA yang terdiri atas tiga tahapan enzimatik yang terjadi di plastida. Pada hewan, khamir dan sejumlah bakteri, ALA dibentuk melalui satu tahapan dari suksinil- CoA dan glisin oleh ä-aminolevulinate sintase (ALA-S). Gen yang menyandikan ALA-S (hemA) dari Rhodobacter sphaeroides telah berhasil dikonstruksi di bawah promotor 35S promoter dan diintroduksikan ke dalam genom Arabidopsis thaliana melalui perantaraan Agrobacterium tumefaciens secara in planta. Lima kandidat tanaman transgenik yang dianalisis dengan PCR ternyata empat diantaranya membawa gen hemA dan kanamisin. Hasil analisis transkrip dengan Reverse Transcriptase-PCR menunjukkan keempat tanaman transgenik tersebut terekspresi pada tarap mRNA. Pengukuran berat basah dan berat kering menunjukkan kenaikan tertinggi sebesar 16.8% dan 16.6%. Namun terdapat dua tanaman yang mengalami kelainan yaitu satu mengalami penurunan berat basah dan berat kering akibat perkembangan akar yang jelek (transgenik no 3) sedangkan satu lagi mengalami penurunan jumlah biji dan keterlambatan pembungaan (transgenik no 4). Hasil analisis aktivitas ALAS, total kandungan ALA dan klorofil pada tanaman transgenik no 4 menunjukkan aktivitas sebesar 40.5 nmol.mg-1.h-1, total ALA meningkat 153.6% dan total klorofil meningkat 43% Selain itu juga mengalami peningkatan toleransi terhadap salinitas sampai dengan konsentrasi 200 mM NaCl. Pada penelitian ini juga telah dilakukan kloning gen Chlorophyll A Oxygenase dari Arabidopsis thaliana.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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