Judul: Keragaman Rice ragged stunt virus dan Rice grassy stunt virus berdasarkan analisis sikuen nukleotida
Abstrak: nfeksi virus merupakan kendala penting dalam produksi padi di Indonesia. Tiga penyakit utama yang disebabkan oleh virus pada padi adalah tungro, kerdil rumput, dan kerdil hampa, masing-masing penyakit disebabkan oleh virus tungro, Rice grassy stunt virus (RGSV), dan Rice ragged stunt virus (RRSV). Kejadian penyakit kerdil rumput dan kerdil hampa masih jarang ditemukan, sedangkan penyakit tungro telah diketahui menyebabkan epidemi di beberapa daerah. Penelitian ini bertujuan untuk mempelajari keragaman RGSV dan RRSV berdasarkan sikuen nukleotida. Fragmen spesifik virus diamplifikasi dengan metode polymerase chain reaction menggunakan primer spesifik untuk RGSV (RGSV-S3-F/RGSV-S3-R), dan RRSV (RRSV-S9-F/RRSV-S9-R). Fragmen DNA spesifik RGSV dan RRSV berhasil diamplifikasi dari sampel Subang, Jawa Barat dan Klaten, Jawa Tengah. Sikuen nukleotida yang diperoleh dari produk PCR dan analisis sikuen menunjukkan homologi yang tinggi (> 99%) antara isolat Subang dan Klaten, baik untuk RGSV maupun RRSV. Analisis lebih lanjut yang melibatkan sikuen di Genbank menunjukkan bahwa homologi antara isolat RRSV dan RGSV dari Asia Tenggara sangat tinggi, yaitu masing-masing mencapai 91-99% dan 95-99%.
Keyword: polymerase chain reaction, sequence homology, specific primers

Judul: Keragaman Gen Protein Selubung Isolat Rice tungro bacilliform tungrovirus (RTBV) dan Rice grassy stunt tenuivirus (RGSV) dari beberapa Kabupaten di Pulau Jawa, Keragaman Gen Protein Selubung Isolat Rice tungro bacilliform tungrovirus (RTBV) dan Rice grassy stunt tenuivirus (RGSV) dari beberapa Kabupaten di Pulau Jawa
Abstrak: Indonesia is the largest consumer of rice in the world. International Rice Research Institute (IRRI) estimated that Indonesia may require an increase in rice production for the next 25 years. Among many constrains in rice production increement is plant diseases including tungro and grassy stunt diseases. Tungro disease is caused by infection of two viruses, Rice tungro bacilliform tungrovirus (RTBV) and Rice tungro spherical waikavirus (RTSV). These viruses are transmitted by the rice leaf hopper vectors which mainly is green leafhoppers (Nephotettix virescens). RTBV is a determinant of the disease symptoms eventhough it could not infect rice without the presence of RTSV. Infected plants showed typical tungro symptoms involving stunting, yellow or orange-yellow discoloration of the leaves, reduced number of tillers and rust-colored spots on the leaves. In 2006 a new symptoms was found in paddy crop in Indonesia, i.e. yellow-orange discoloration of the leaves, reduced number of tillers without any reduction in plant height. It was reported that the disease is caused by infection of Rice grassy stunt tenuivirus (RGSV) the cause of grassy stunt disease. Symptoms similarity of tungro and RGSV infection may cause difficulty in disease diagnosis and cause confusion in determining diseases control strategies. Therefore research on symptoms and genetic diversity of RTBV and RGSV is necessary to determine the appropriate control strategy. The genetic diversity of RTBV isolates from South Asia and Southeast Asia as well as from some tungro endemic area in Indonesia based on the symptoms variation and diversity of coat protein gene have been reported. The genetic diversity of the isolates RGSV from two areas in Taiwan and Philippines based on symptoms variation have also been reported. Genetic and symptoms diversity of RTBV and RGSV could be analysed through the diversity of coat protein gene. Coat protein gene is known as a determinant factor of infection, virulence, and symptoms induction. The research is conducted to study the diversity of symptoms and coat protein gene of RTBV and RGSV from several districts in Java. The areas in Bogor, Subang, Pandeglang, Klaten, Batang, Sleman, Jember and Banyuwangi were selected as disease survey location because these regions were reported as endemic areas for tungro disease and brown leafhopper. The study includes three main activities, i.e. observation of symptoms in the field and sampling of infected plants, detection of RTBV and RGSV, and analysis of diversity of coat protein gene of RTBV and RGSV. Most infected plants in the fields showed tungro-like symptoms. Two variations of symptoms can be classified by the number of tillers and plant height. These symptoms variations can be caused by RTBV or RGSV infection or mix infection of RTBV and RGSV as indicated by detection results using PCR. Identification of total 64 samples showed infection of RTBV in 13 samples, RGSV in 36 samples and mix of RTBV and RGSV in 2 samples. The results showed that tungro-like symptoms were positive from infection of RGSV. Therefore identification of diseases based only on symptoms are not sufficient. The whole coat protein gene of RTBV was amplified using DA-F and DA-R primers with the amplicon
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Judul: Kekonsistenan Hamiltonian pada Gerak Gelombang Interfacial
Abstrak: The interfacial wave is an internal wave that occurs at boundary of two layers fluid. It appears because there is difference of mass density between the two layers. The objective of this thesis is to formulate the motion of internal wave with flat base and flat as well as free upper bound surface. The motion equation obtained is a Hamiltonian system. The Hamiltonian in this system is expressed by variable of wave deviation and horizontal component of potential velocity. Under assumption that interfacial wave moves only in one direction, it can be shown that the Hamiltonian depends on the solution of the wave motion equation. The coefficients of the equation depend on the physical characteristics of the two layers of fluid, i.e. thickness and mass density. The numerical results show that Hamiltonian in the system is constant. It is consistent with Hamiltonian characteristic, which does not depend on time.
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