Judul: Molecular Identification of Sea Urchins in Kepulauan Seribu Based on COI and 16S rRNA Genes as a Basis for Resource Management
Abstrak: Secara ekologis, bulu babi berperan penting dalam ekosistem terumbu karang. Beberapa jenis bulu babi banyak dimanfaatkan dalam industri pangan dan farmasi. Namun, beberapa spesies bulu babi memiliki karakter penciri yang mirip secara morfologi dan berpotensi diidentifikasi sebagai spesies yang sama. Hal ini dapat berdampak pada pengelolaan dan pemanfaatannya. Penelitian ini bertujuan memastikan spesies bulu babi yang ditemukan di Kepulauan Seribu. Spesies bulu babi dipastikan secara molekuler menggunakan marka gen COI dan 16S rRNA. Berdasarkan ciri morfologi, diduga enam spesimen mewakili tiga spesies. Hasil BLASTn menunjukkan validasi enam spesimen sebagai Diadema setosum dan Echinothrix calamaris dengan kisaran 98,93-99,69% dan 95,55-99,23% oleh gen COI. Sementara itu, berdasarkan gen 16S rRNA, kisaran hasil validasi, yaitu 99,83% dan 99,66-100%. Validasi tersebut diperkuat dengan jarak genetik yang memiliki nilai rendah. Kedua jenis bulu babi yang ditemukan di Kepulauan Seribu menunjukkan hubungan kekerabatan yang dekat., Ecologically, sea urchins play an important role in coral reef ecosystems. Some types of sea urchins are widely utilized in the food and pharmaceutical industries. However, some sea urchin species have morphologically similar characteristics and could be identified as similar. This could have an impact on their management and utilization. This study aims to confirm sea urchin species found in Kepulauan Seribu. Sea urchin species were confirmed molecularly using COI and 16S rRNA gene markers. Based on morphological characteristics, six specimens were suspected to represent three species. BLASTn results validated the six specimens as Diadema setosum and Echinothrix calamaris with a range of 98.93-99.69% and 95.55-99.23% by the COI gene. Meanwhile, based on the 16S rRNA gene, the range of validation results was 99.83% and 99.66-100%. The genetic distance strengthens the validation, which has a low value. The two types of sea urchins found in Kepulauan Seribu show a close relationship.
Keyword: 16S rRNA, COI, Cryptic spesies, identifikasi molekuler, identifikasi morfologi

Judul: Genetic Characteristics of Starfish on Pramuka  Island Based on COI and 16S rRNA Gene Markers
Abstrak: Identifikasi molekuler bintang laut masih sangat terbatas, sehingga perlu adanya identifikasi genetik sebagai dasar informasi bintang laut agar bisa dimanfaatkan secara tepat guna dan optimal. Tujuan penelitian ini adalah untuk mengetahui kepastian spesies bintang laut berdasarkan marka gen COI dan 16S rRNA di perairan Pulau Pramuka, Kepulauan Seribu, DKI Jakarta sebagai dasar pengelolaan biota tersebut. Tahap identifikasi molekuler meliputi preparasi sampel, isolasi dan ekstraksi DNA, amplifikasi dan visualisasi DNA, uji kualitas DNA serta sekuensing. Analisis data berupa validasi basa nukleotida gen COI dan 16S rRNA, jarak genetik, konstruksi pohon filogenetik, dan polimorfisme. Hasil menunjukkan bahwa sampel bintang laut tervalidasi sebagai dua spesies yang berbeda, yaitu Archaster typicus dan Ophiocoma scolopendrina dengan persentase identifikasi lebih dari 97%. Sekuen nukleotida sampel bintang laut bersifat konservatif pada level spesies dengan nilai rata-rata conserved pada gen COI sebesar 98,87%, sedangkan pada gen 16S rRNA sebesar 99,14%. Keragaman haplotype bintang laut termasuk dalam kategori tinggi., Molecular identification of starfish is still very limited, therefore genetic identification is needed to provide information about starfish, enabling them to be utilized effectively and optimally. The aim of this research is to determine the species certainty of starfish based on the COI and 16S rRNA gene markers in the waters of Pramuka Island, Seribu Islands, DKI Jakarta. The molecular identification process includes sample preparation, DNA isolation and extraction, DNA amplification and visualization, DNA quality testing, and sequencing. Data analysis involves validation of COI and 16S rRNA gene nucleotide bases, genetic distance, construction of a phylogenetic tree, and polymorphism. The results showed that the starfish samples were validated as two different species, namely Archaster typicus and Ophiocoma scolopendrina with an identification percentage of over 97%. The nucleotide sequences of the starfish samples were conserved at the species level, with an average conserved value of 98,87% for the COI gene and 99,14% for the 16S rRNA gene. The haplotype diversity of starfish is categorized as high.
Keyword: 16S rRNA, COI, genetic, starfish

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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