Judul: Karakterisasi Gen Odorant Receptor (OR) Parsial Serangga Penggerek Batang Padi Kuning Scirpophaga incertulas (Walker)
Abstrak: Yellow rice stem borer S. incertulas (Lepidoptera: Crambidae) is an important insect causes the damage of the rice crop. The females of S. incertulas naturally release sex pheromones and then captured by pheromone binding protein (PBP) in the haemolymph of male antennaes; subsequently sent to the odorant receptor proteins located on the olfactory sensory neuron dendrites on the antennae sensillae membrane which detect the chemical stimuli. The aim of this study was to characterize the odorant receptor (OR) gene that mediates the chemical information systems on the mating behavior of S. incertulas. RNA was extracted from male and female imago antennaes collected from Karawang and from rearing in Indonesian Centre for Agricultural Biotechnology and Genetic Resources Research and Development (BB-BIOGEN). The OR gene amplification from cDNA was performed by standard PCR, touchdown PCR and nested-touchdown PCR. The characterization of partial OR gene of S. incertulas male successfully performed by using touchdown-nested PCR. The OR partial gene sequence of S. incertulas revealed 133 bp size was homolog to the OR gene sequence of Ostrinia nubilalis (Lepidoptera: Crambidae) OnubOR7a (GenBank Accession No. AB597005.1). The homologous part showed that 133 bp sequence of S. incertulas was a candidate of OR genes that mediated the chemical information systems on the mating behavior of yellow rice stem borer. This study also successfully amplified beta-actin gene sequence 681 bp size from both male and female insects as the verification to the success of RNA extraction.
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Judul: Identification of Pheromone Binding Protein Gene of Yellow Rice Stem Borer Scirpophaga Incertulas (Walker) (Lepidoptera: Crambidae)
Abstrak: The yellow rice stem borers (YRSB) moth, Scirpophaga incertulas (Walker) (Lepidoptera: Crambidae), is known as the most major rice stem borer in tropical Asia. Pesticides are not effective to control the population of these insects due to almost entire larvae phase and pupae are in the rice stem. Hence, other control technique is needed such as based on the mating behaviour. Pheromone binding protein (PBP) in male S. incertulas antennae plays a role in the recognition of sex pheromone produced by the female, therefore influenced in their mating behavior. The aim of this study was to identify PBP gene of S. incertulas. For the purpose to collect imagoes as DNA source, S. incertulas were reared. Touchdown PCR and touchdown-nested PCR were the main techniques conducted to identify genomic of PBP gene from S. incertulas and revealed 700 and 600 bp amplicons, respectively. Those amplicons strongly expected as PBP gene. Sequence analysis of S. incertulas from touchdown-nested amplicon identified 575 bp which was consisted of 169 bp of exon 3 and 406 bp of intron 2. This study revealed putative amino acid sequences of exon 3 from S. incertulas has one conserved cysteine while other Lepidopterans PBP have three conserved cysteine. In phylogenetic analysis, the putative amino acid sequences obtained, showed a phylogenetic signal i.e. by clustering with PBPs from other Crambidae moths. The result of this study is important as a basic data for PBP expression analysis in female or male S. incertulas as the initial step to develope new insect biocontrol.
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Judul: Formulasi Hamilton Untuk Menggambarkan Deformasi Gelombang Soliter Dengan Dasar Tidak Rata Pada Fluida Dua Lapisan
Abstrak: Gelombang internal adalah suatu gelombang yang muncul di bawah permukaan laut sehingga gelombang ini tidak teramati secara kasat mata. Formulasi Hamilton dirumuskan untuk menjelaskan gerak gelombang ini. Dalam hal ini diasumsikan bahwa fluida yang ditinjau terdiri atas dua lapisan dengan masing-masing lapisan memiliki rapat massa yang konstan. Selain itu, diasumsikan pula fluida yang ditinjau berupa fluida tak mampat (incompressible) dan tak kental (invicid). Formulasi Hamilton dilakukan dengan meninjau fluida dua lapisan yang berada pada domain yang dibatasi oleh batas atas yang rata dan batas bawah yang tidak rata. Hamilton (energi total)-nya didefinisikan sebagai penjumlahan antara energi kinetik dan energi potensialnya. Karena energi kinetik tidak secara eksplisit dinyatakan dalam peubah fisis, maka digunakan metode asimtotik untuk menentukan energi totalnya. Dalam hal ini diasumsikan bahwa gelombang interfacial yang ditinjau cukup panjang, dan amplitudo yang cukup kecil. Persamaan Korteweg de- Vries (KdV) diperoleh, jika disumsikan bahwa gelombang interfacial hanya merambat pada satu arah, sedangkan jika gelombang tersebut merambat ke dua arah, diperoleh persamaan Boussinesq.
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