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: Identification of Shark and Stingray Species in Processed Seafood Products using the Long-read Sequencing Method
Abstrak: Tren konsumsi daging hiu dan pari yang semakin meningkat tiap tahunnya serta tingginya eksploitasi menyebabkan jumlah populasi hiu dan pari di alam semakin mengalami penyusutan. Identifikasi produk olahan ikan hiu dan pari menggunakan teknik metabarcoding berbasis Long-read Sequencing perlu dilakukan untuk menganalisis berbagai spesies dalam sampel olahan. Penelitian ini bertujuan mengidentifikasi spesies hiu dan pari sebagai bahan baku produk olahan hasil perikanan komersial mengggunakan teknologi Long-read Sequencing dan Sanger Sequencing. Sampel yang digunakan adalah produk hiu dan pari olahan yang didapat dari daerah Perairan Utara Pulau Jawa. Proses sekuensing dilakukan dengan menggunakan Long-read Sequencing dan diverifikasi dengan Sanger Sequencing. Metode Long-read Sequencing berhasil mengidentifikasi 9 spesies dalam produk campuran (mixed-species). Hasil identifikasi dengan Sanger Sequencing berhasil mengidentifikasi 14 spesies, berupa 7 jenis hiu dan 7 jenis pari. Hasil spesies yang teridentifikasi tersebut menunjukkan terdapat 8 spesies yang terdaftar sebagai terancam keberlanjutannya berdasarkan IUCN Red List. Enam spesies yang teridentifikasi juga terdaftar dalam Apendiks II CITES., The increasing trend in the consumption of shark and ray meat each year, and high exploitation rates, have led to a significant decline in shark and ray populations. Identifying processed shark and ray products using metabarcoding techniques based on Long-read Sequencing is necessary to analyze species in processed samples. This study aimed to identify sharks and rays species used as raw materials in commercial fishery products using Long-read Sequencing and Sanger Sequencing technologies. The samples used included processed shark and ray products obtained from the Northern Waters of Java Island. The sequencing process was carried out using Long-read Sequencing and verified with Sanger Sequencing. The Long-read Sequencing method successfully identified 9 species in mixed products. Identification results with Sanger Sequencing successfully identified 14 species, comprising 7 shark species and 7 ray species. The identified species indicated that 8 species are listed as threatened according to the IUCN Red List. Additionally, 6 of the identified species are listed in Appendix II CITES.
Keyword: sequencing, hiu, long-read, pari, sanger

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.
Keyword: