Judul: Deteksi dan identifikasi fitoplasma yang berasosiasi dengan penyakit layu kelapa di Pulau Derawan Kalimantan Timur
Abstrak: Coconut as a main commodity in Derawan Island has two functions, i.e. farmer’s income source and beach plant aesthetics. The occurrence of coconut wilt disease resulted in eradication of about 10% of the palm in 2010. The objectives of this study were: (1) to describe morphological and histopathological symptoms of coconut wilt disease in Derawan island, (2) to detect the presence of phytoplasmas associated with coconut wilt disease in Derawan island using nested-PCR (n-PCR) technique, (3) to identify and classify phytoplasmas associated with coconut wilt disease based on 16S rRNA gene sequences, (4) to detect the presence of phytoplasmas from leafhoppers (Hemiptera: Cicadellidae) and love vein (Cassytha filiformis) (Laurales: Lauraceae), which expected to have ability to transmit the pathogen. The methods in this research included visual and microscopic observation, detection of phytoplasmas with n-PCR method, cloning of the nPCR products, sequencing, analysis of sequencing results using BLAST, construction of phylogenetic tree, and in silico RFLP analysis. The results showed that the suspected phytoplasmas reside in phloem tissues and were detected with both microscopic and molecular techniques. Phytoplasmas associated with coconut wilt disease in Derawan island belong to 16SrII (witches’ broom phytoplasma) and 16SrXI (Ca. Phytoplasma oryzae) groups. The use of nPCR employing R16F2n/R16R2 primer pair with expected amplicon at size of about 1.25 kb are positive not only for particular strain of phytoplasmas but also other bacterial species that mainly belong to Gram Positive group. Phytoplasmas that belong to 16SrII are also detected in some leafhoppers and C. filliformis.
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Judul: Deteksi dan identifikasi pineapple mealybug wiltassociated virus penyebab penyakit layu pada tanaman nanas di Indonesia
Abstrak: Field surveys on pineapple wilt disease were conducted on pineapple production areas in Subang, West Java, Indonesia. The disease was characterized by severe tip dieback, downward curling, reddening, and wilting of the leaves which can lead to total collapse of the plant. The objective of the research is to identify the viruses causing wilt disease on pineapple in Indonesia. Tissue blot immunoassays (TBIAs) using two different antibodies specific to either Pineapple mealybug wilt-associated virus-1 (PMWaV-1) or PMWaV-2 (Agdia Inc., USA) successfully detected the viruses in leaf tissues from both symptomatic and asymptomatic pineapple plants. A reverse transcription-polymerase chain reaction (RT-PCR) assays using oligonucleotide primers specific to HSP 70 gene of PMWaV-1 and PMWaV-2 were also successfully amplified the regions succesfully. These finding indicated that both closteroviruses were associated with wilt disease on pineapple plants in Indonesia. Protein analysis by using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) revealed that the viruses have a major structural protein with molecular mass of approximately kDa. Flexuous filamentous particles were also observed in electron microscopy preparations from infected plants. These results were in agreement with characteritics of the closteroviruses. Aligments of partial nucleotide sequences of the viral genomes exhibited 96 to 98% homology with that of PMWaV-1 and PMWaV-2 Hawaiian isolates as previously reported by Sether et al. (2001), respectively. Phylogenetic analysis revealed that Indonesian and Hawaiian virus isolates were belong to mealybugtransmitted closterovirus and closely related to Grapevine leafroll-associated virus-3 (GLRaV-3)., Penelitian ini bertujuan untuk mendeteksi dan mengidentifikasi PMWaV yang berasosiasi dengan penyakit layu pada tanaman nanas di Indonesia. Diharapkan penelitian ini dapat memberikan informasi dan laporan pertama mengenai keberadaan PMWaV yang berasosiasi dengan penyakit layu nanas di Indonesia. Hasil deteksi secara serologi dengan metode Tissue blot immunoassays (TBIA) menggunakan dua antibodi monoklonal spesifik terhadap PMWaV-1 maupun PMWaV-2 (Agdia Inc., USA) berhasil mendeteksi keberadaan PMWaV- 1 dan PMWaV-2 pada jaringan daun tanaman nanas yang menunjukkan maupun dari yang tidak menunjukkan gejala layu. Pendeteksian secara molekuler dengan metode reverse transcription-polymerase chain reaction (RT-PCR) menggunakan dua primer yang spesifik terhadap PMWaV-1 dan PMWaV-2 berhasil mengamplifikasi gen Heat Shock Protein 70 (HSP 70) pada kedua virus. Penemuan ini mengindikasikan bahwa PMWaV-1 dan PMWaV-2 berasosiasi dengan penyakit layu nanas yang terjadi di Indonesia. Analisis protein menggunakan sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDSPAGE) menunjukkan adanya sebuah struktural protein besar dengan perkiraan ukuran sebesar 23 kDa. Keberadaan partikel virus berbentuk batang lentur juga teramati pada preparasi mikroskop elektron yang berasal dari tanaman nanas yang terinfeksi virus. Hasil pengamatan menggunakan mikroskop elektron ini sesuai dengan ciri-ciri virus dari anggota Closterovirus. Analisis parsial genom HSP 70 virus layu nanas isolat Indonesia menunjukkan kisaran homologi sebesar 96 hingga 98% dengan PMWaV-1 dan PMWaV-2. Selain itu, analisis filogenetik menunjukkan bahwa isolat PMWaV Indonesia dan Hawaii merupakan anggota Closterovirus yang ditularkan oleh kutu putih, dan memiliki hubungan kekerabatan yang dekat dengan Grapevine leafroll-associated virus-3 (GLRaV-3).
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Judul: Analysis of M/G/1 Queue Model with Two Phases of Service and Bernoulli Feedback System
Abstrak: Model antrean M/G/1 dengan sistem feedback Bernoulli adalah model antrean dengan proses kedatangan mengikuti proses Poisson. Pada karya ilmiah ini dibahas sistem antrean M/G/1 dengan dua fase layanan. Setelah layanan pertama selesai, pelanggan dapat memilih untuk meninggalkan sistem dengan peluang ... dst, The M/G/1 queueing model with the Bernoulli feedback system is a queueing model with the arrival process following the Poisson process. In this manuscript M/G/1 queueing system with two phases of service is discussed. After the first service is completed, the customer can choose to leave the system with probability ... dst
Keyword: queue, Bernoulli, probability generating function, expected value