Judul: Detemination Heavy Metal Contamination and Species Identification in Shark Products Using DNA Barcoding
Abstrak: Hiu merupakan konsumen tingkat tinggi (apex predator) yang dapat mengakumulasi logam berat melalui sumber makanannya. Hiu olahan yang mengandung logam berat dalam jumlah tinggi dapat membahayakan manusia. Hiu olahan dijual dalam bentuk potongan kecil dan sulit diidentifikasi spesiesnya, sehingga memerlukan metode molekuler berbasis DNA. Penelitian bertujuan menentukan cemaran logam berat pada olahan hiu, mengidentifikasi spesies menggunakan metode DNA barcoding serta menentukan korelasi antar faktor dalam produksi ikan hiu asap di 3 wilayah Pantura. Metode penelitian ini meliputi uji logam berat, isolasi DNA, amplifikasi DNA dengan marka gen COI, sekuensing, dan penyebaran kuesioner. Spesies yang teridentifikasi meliputi C. sealei, C. tjutjot, C. limbatus, S. lewini, dan R. springeri. Kelima sampel mengandung logam berat merkuri terutama spesies C. limbatus dan S. lewini yang jumlahnya melebihi 1 mg/kg. Hiu olahan masih banyak diminati masyarakat Indonesia khususnya wilayah Pantura dengan volume penjualan rata rata lebih dari 1 kuintal per minggu. Pendidikan dan pendapatan produsen berkorelasi positif dengan volume penjualan hiu di wilayah Pantura., Sharks are high-level consumers (apex predators) that can accumulate heavy metals through their food sources. Processed sharks containing high amounts of heavy metals can harm humans. Processed sharks are sold in the market in the form of small pieces, making it difficult to identify the species, requiring DNA-based molecular methods. The aims of the study were to determine heavy metal contamination in processed sharks, to identify species using the DNA barcoding method and to determine the correlation between factors in smoked shark production in 3 regions of Pantura. The research methods included DNA isolation, DNA amplification with COI gene markers, electrophoresis, sequencing, heavy metal testing, and distributing questionnaires. The identified species include C. sealei, C. tjutjot, C. limbatus, S. lewini, and R. springeri. The five samples contained the heavy metal mercury, especially the species C. limbatus and S. lewini whose amount exceeded 1 mg/kg. Processed sharks are still in great demand by the people of Indonesia, especially in Pantura, with an average sales volume of more than 1 quintal per week. The sales volume of sharks is positively correlated with the education and income of producers in the Pantura.
Keyword: amplifikasi, DNA barcoding, logam berat, amplification, heavy metals

Judul: Authentication of Shark Processed Product using High-Throughput Sequencing Technique
Abstrak: Tingginya permintaan produk hiu di pasaran dapat berakibat pada kelangkaan spesies-spesies hiu tertentu di alam. Autentikasi pada produk-produk olahan hiu diperlukan untuk mendeteksi jenis spesies hiu yang digunakan pada suatu produk. Tujuan dari penelitian ini yaitu mengidentifikasi spesies hiu langka pada produk hiu olahan yang berasal dari Lombok, Nusa Tenggara Barat dengan teknik High-Throughput Sequencing. Identifikasi spesies dilakukan dengan pengurutan basa nukleotida dari campuran isolat DNA sampel dengan teknik High-Throughput Sequencing, yang kemudian dilakukan analisis bioinformatika. Hasil identifikasi spesies dari produk olahan sate hiu yang berasal dari Lombok, Nusa Tenggara Barat terdeteksi menggunakan hiu diantaranya Carcharhinus falciformis yang terdaftar sebagai salah satu jenis hiu dilindungi. Sekuen yang didapatkan memiliki kemiripan tertinggi 99,35% dengan sekuen Carcharhinus falciformis yang terdaat pada GenBank., The high demand for shark products in the market increases the threat of shark species in the wild. Authentication for processed shark products is required in order to detect the shark species used in a product. The aim of this research was to identify threatened shark species in processed shark products originated from Lombok, West Nusa Tenggara using a high-throughput sequencing technique. Species identification was carried out by sequencing from a mixture of DNA isolate samples using the High-Throughput Sequencing technique, which was then carried out by bioinformatics analysis. Species used on satay products originated from Lombok, West Nusa Tenggara was detected as Carcharhinus falciformis that is listed as one of the threatened shark species. The sequence has 99,35% of percent identity with the C. falciformis sequence available in GenBank.
Keyword: Autentikasi, Carcharhinus, High throughput sequencing, Pengurutan basa nukleotida, Produk olahan ikan hiu

Judul: Bifurkasi Hopf pada Model Siklus Bisnis Kaldor Kalecki tanpa dan dengan Waktu Tunda
Abstrak: Business cycle model is one of dynamical system models in economic. One of the business cycles model is Kaldor-Kalecki model. Kaldor-Kalecki business cycle model that is written in delayed defferential equations, is a business cycle model that involves gross product and capital stock of a company. In this paper Kaldor-Kalecki business cycle model is analyzed using both nondelay and delay in time of capital stock. By Taylor expansion for the time delayed model, an analysis of stability around the fixed points has been done. Furthermore, by using Hopf bifurcation theorem, it can be shown that there exists periodic orbits and limit cycle. In the nondelayed model, changing the parameter of goods market could lead to the occurrence of Hopf bifurcation and the existence of limit cycle. Similarly, for the delayed model, it has been shown that changing the time delay parameter may result in the occurrence of Hopf bifurcation and limit cycle.
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