Judul: Analisis Sekuen DNA yang Terlibat dalam Patogenesitas dan Perancangan Primer PCR Spesifik untuk Xanthomonas axonopodis pv. glycines
Abstrak: Xanfhomonas axompodis pv, glycines (Xag) causes bacterial pustules an susceptible soybean cultivars. Therefore, understanding on the? mechanism of pathogenicity and soybean - Xag interaction are paramount impartant to develop strategy far disease control and as a model system fur a similar phenomenon. The objectives of this work are: (i) to identify pathogenicity gene(s) of Xag as an approach to understand the mechanism underlying specific pathogsnicrty in this group of bacteria, and (ii) to design specific PCR primers for Xag. A non-pathogenic Xag mutant derived from the wild type strain Xag YR32, designated M715, was constructed employing a mini-Tn5 transpusan. We have cloned a 1.8 kb-Pstl DNA fragment from Xag YR32. DNA sequence analysis indicated that the gene inactivated by the transposon in M"7 5 encoded a TonB-dependent receptor which is invofved in uptake of ferric-siderophore into the cell. Introduction of a broad-host range plasmid harboring a corresponding DNA fragment from the Xag YR32 into MY1 5 restored, albeit partially, pathogenicity of the mutant. We have designed two specific PCR primers for Xag, i.e., EttyOl (5'-TTgCggCgATTg-3') and EttyQ2 (5'- CgCATgCCATTg-3'). Arnpfificatian af Xag genornic DNA employing these specific primers generated a 436-bp amplimn. Southern hybridization analysis of five pathavars of Xanfhomonas and five wild types of Xag from Indonesia and Taiwan indicated that the pathogenicity gene was unique to Xag.
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Judul: Pemetaan Fisik Dan Genetik KromosomXanthomonas Campestris pv. Glycines YR32
Abstrak: Selain mempelajari pola penyebaran, distribusi galur-galur dan epidemiologi penyakit sebagai upaya untuk menanggulangi penyakit pustul bakteri, mempelajari mekanisme patogenesis serta interaksi antara bakteri dengan tanaman inang merupakan suatu cara lain yang diharapkan dapat menanggulangi penyebaran penyakit yang disebabkan oleh Xanthomonas campestris pv. glycines tersebut. Mekanisme patogenesis bakteri terhadap tanaman inang bersifat sangat kompleks dan sampai saat kinipun masih sedikit sekali dimengerti. Hal ini disebabkan karena banyak faktor yang berperan pada proses patogenesis yang tidak hanya melibatkan gen-gen tertentu pada proses tersebut baik secara langsung maupun tidak langsung, tapi juga faktor- faktor eksternal lain seperti reaksi dari tanaman inang, sistem pertahanan inang terhadap serangan bakteri, sinyal lingkungan seperti senyawa eksudat tanaman yang dapat dikenali oleh bakteri, dan masih banyak lagi faktor-faktor lainnya. Dengan menggunakan Xanthomonas campestris pv. glycines sebagai model, yang sampai saat ini masih sedikit sekali pengetahuan kita mengenai struktur genomnya, dilakukan penelitian ini yang bertujuan untuk mengkonstruksi peta fisik kromosom Xanthomonas campestris pv. glycines galur YR32 serta lokalisasi beberapa gen spesifik untuk peta genetiknya…dst
Keyword: Bakteri Patogen Tanaman, Patogenesis Molekular, Pemetaan Fisik, Genetik DNA Genom

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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