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: Molecular Identification of the Freshwater Stingrays Based on COI Gene Markers in Musi River, Palembang, South Sumatera
Abstrak: Ikan pari dari famili Dasyatidae memiliki karakteristik yang hampir mirip, sehingga diperlukan metode yang akurat dalam validasi spesiesnya. Selain itu, ketersediaan informasi dan data ilmiah mengenai genetik ikan pari air tawar masih minim di Indonesia. Oleh karena itu, penelitian ini bertujuan untuk mengidentifikasi spesies, kekerabatan genetik, dan keragaman genetik ikan pari air tawar berdasarkan variasi basa nukleotida Gen COI di Sungai Musi, Sumatera Selatan. Pengambilan sampel dilakukan pada bulan Februari hingga Mei 2023 di Sungai Musi. Analisis laboratorium dilakukan pada bulan Juni hingga September 2023. Ekstraksi DNA sampel menghasilkan 12 DNA total. Hasil penelitian menunjukkan dua spesies ikan pari air tawar berhasil divalidasi, yaitu Fluvitrygon signifer dan Pastinachus stellurostris dengan kemiripan 99,30% hingga 100%. Sementara itu, pari tutul (kode B) dan pari sungai tepi putih moncong panjang (kode C) belum tervalidasi secara genetik, dengan tingkat kemiripan 89,24% hingga 89,70%.Keragaman genetik ikan pari air tawar di Sungai Musi tergolong rendah, dengan rentang nilai haplotype Hd 0-0,667. Hasil konstruksi pohon filogeni menunjukkan Fluvitrygon signifer dan Pastinachus stellurostris memiliki kekerabatan jauh dengan pari tutul dan pari tepi putih moncong panjang., Stingrays from the family Dasyatidae have almost similar characteristics, so accurate methods are needed to validate the species. Apart from that, the availability of scientific information and data about the genetics of freshwater stingrays is still minimal in Indonesia. Therefore, this study aims to identify species, genetic relationships and genetic diversity of freshwater stingrays based on nucleotide base variations of the COI gene in the Musi River, South Sumatra. Sampling was carried out from June to September 2023. DNA extraction of the samples produced 12 DNAs in total. The research results showed species freshwater stingrays were successfully validated, namely Fluvitrygon signifer and Pastinachus stellurostris with 99,30% to 100% similarity. The spotted ray (code B) and the long-snouted white edge ray (code C) have not been genetically validated yet, with a similarity level of 89,24% to 89,70%. The genetic diversity of freshwater stingrays in the Musi River is relatively low, with a range of haplotype Hd values of 0-0,667. The results of the phylogenetic tree construction show Fluvitrygon signifer and Pastinachus stellurostris distantly related to marbled whipray and long-snouted white edge ray.
Keyword: COI, identifikasi morfologi, pari air tawar, sungai musi

Judul: Natrium lignosulfonat sebagai agen pendispersi pada mortar
Abstrak: Lignosulphonate, a modification product of lignin waste from pulp and paper industry can be used as water reducer in mortar mixture. This substance can influence the mechanical characteristic of mortar such as diameter of flow, flexural strength, compressive strength, and setting time of cement paste. Lignosulphonate shows it function as dispersant on cement hydration at 3 days that analyzed with x-ray difractometer. Research result show that flow of fresh mortar rise with increase concentration (from weight of cement) of synthetic sodium lignosulphonate (NaLS). It show that mortar homogenity also increasing. The result of flexural strength and compressive strength test use synthetic NaLS 0.1-0.3% from weight of cement show that addition synthetic NaLS 0.2% is the best result because it has the biggest of flexural strenght and compressive strength value. Initial setting time of cement paste increase, about 50% with addition of synthetic NaLS 0.2%. Whereas the final setting time decrease, about 8%. Cement hydration test show increase hydration product peak, Ca(OH)2 dan calcium silicate hydrate (C-S-H).
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