Judul: Genetic Characteristic of Giant Featherback (Chitala lopis) from Sumatra and Borneo using COI Gene
Abstrak: Ikan belida (Chitala lopis) merupakan salah satu jenis ikan air tawar yang memiliki nilai ekonomis tinggi di Indonesia. Ikan belida merupakan ikan konsumsi dan ikan hias karena tampilannya unik. Adanya aktivitas penangkapan (overfishing) dan perubahan lingkungan maupun kerusakan lingkungan perairan, dapat menyebabkan kelestarian ikan ini terancam punah. Salah satu upaya untuk menjaga kelestrian, yaitu dengan upaya konservasi genetik berdasarkan analisis gen mtDNA. Salah satu gen mtDNA yang sering digunakan yaitu gen Cytochrome Oxidase subunit I (COI), karena banyak digunakan sebagai DNA barcoding, identifikasi spesies, karakterisasi, pengelompokan spesies dari berbagai taksa dan menentukan sebaran populasi hewan. Tujuan dari penelitian ini adalah untuk mengkaji karakteristik genetik ikan Belida (Chitala lopis) dari sebaran pulau Sumatra dan Kalimantan berdasarkan gen COI DNA Mitokondria. Sebanyak 10 individu ikan belida (Lampung 3, Riau 1, Kalimantan Barat 3, Kalimantan Selatan 3) digunakan dalam penelitian ini serta tambahan 3 sekuens pembanding (ingroup dan outgroup) dari GenBank. Analisis yang digunakan meliputi perhitungan jarak genetik, variasi nukleotida, polimorfisme, dan rekonstruksi pohon filogenetik menggunakan software MEGA 7.0. Hasil produk PCR dari 10 sampel ikan belida diperoleh sekuens dengan Panjang 707 pb. Hasil BLAST-n menunjukan percent identity 97.60% – 99.15% dengan nilai query cover sebesar 100% untuk semua sampel. Karakter gen COI ikan belida menunjukan hasil situs konservatif sebesar 687 pb (97.17%), situs variasi 20 pb (2.83%), situs parsimoni 17 pb (2.40%), dan singleton 2 pb (0.28%). Ditemukannya 13 situs polimorfisme bervariasi atau Single Nucleotide Polymorphism (SNP) pada populasi Sumatra dan Kalimantan. Sampel Kalimantan memiliki dua situs nukleotida spesifik geografik yang membedakan dengan sampel Sumatra. Kalimantan Barat memiliki dua situs nukleotida spesifik. Pada sampel Kalimantan Selatan menunjukan nukleotida spesifik yang lebih bervariasi dengan 9 situs nukleotida spesifik. Berdasarkan jarak genetik, perbedaan terbesar terletak pada sampel Kalimantan Selatan (1.63%) dibandingkan dengan semua sampel. Hasil rekonstruksi pohon filogenetik menunjukan bahwa sampel Kalimantan Selatan berada pada group yang berbeda. Sampel Kalimantan Barat menunjukan kekerabatan lebih dekat dengan group Sumatra.
Keyword: Belida, COI, DNA Barcode, SNP

Judul: Variasi Gen Cyt b Mitokondria pada ikan belida
Abstrak: Knife fish is freshwater fish belonging to the Notopteridae famili distributed across India, Pakistan, Bangladesh, Sri Lanka, Nepal, Thailand and western part of Indonesia. This fish is very popular for consumption and ornamental fish. Studies of freshwater fishes, especially in the protected freshwater fish form is an important aspect of biogeographical studies, because they do not disperse easily through saltwater areas, and thus their evolution may be tightly linked to the geological histories. This study aimed to analyze cyt b gene sequence variation of knife fish from the Mahakam River (Borneo) and Indragiri River (Sumatra) as a base for studying their population and phylogenetic position. Samples of 38 fish samples taken from two rivers, nine samples from the Mahakam River and 29 samples from the Indragiri River. Cyt b gene amplification succeeded in seven samples (KALTIM02, TU02, TU06, TU07, KCO001, KCO005, dan PP03). Phylogeny analysis performed using Kimura-2-parameter based on the first two bases of each codon and amino acid. Both topography show that six samples are in the same clade with Chitala lopis, whereas one sample of the Indragiri River separate from the other. The knife fish from Indragiri River have higher diversity than Mahakam River and closest intrapopulation relationship found in Mahakam River population.
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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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