Judul: Analysis of Cu-SOD Gene Expression as Candidates for Molecular Marker Selection for Nitrite Stress-Resistant Catfish (Clarias gariepinus)
Abstrak: Nitrit merupakan salah satu zat toksik yang secara alami berada dalam perairan. Paparan nitrit dapat menginduksi produksi reactive oxygen species (ROS) yang bisa merusak fisiologi sel dalam tubuh ikan. Sekuens gen Cu-SOD adalah gen yang mengodekan regulasi kerja enzim antioksidan untuk mereduksi dampak ROS. Penelitian ini bertujuan untuk menganalisis kinerja ekspresi gen Cu-SOD benih lele terhadap paparan nitrit pada uji tantang LC70. Metode yang digunakan adalah lethal concentration 70 (LC70). Sesuai hasil penentuan konsentrasi LC70, benih ikan lele diberi paparan nitrit sebesar 32,3 mg/L. Terdapat dua jenis sampel yaitu ikan yang aktif dan lemas yang masing-masing diambil pada jam 6, 12, dan 24. Pada jam ke-0, 4 ikan perlakuan nitrit diambil sebagai sampel awal. Sampel ikan diambil pada bagian ventral, tepatnya organ dan otot badan di bawah insang hingga mendekati ekor. Pengambilan sampel kualitas air dilakukan pada jam 0, 12, dan 24. Ekspresi relatif gen Cu-SOD pada benih lele yang aktif dari jam ke-0 hingga 12 relatif sama dan meningkat secara signifikan pada jam ke-24. Pada benih lele yang lemas, ekspresi gen jam ke-0 dan 6 tidak menunjukkan perbedaan yang signifikan antara keduanya, kemudian menurun pada jam ke-12 yang menunjukkan berbeda nyata, dan pada jam ke-24 meningkat secara signifikan. Perbedaan nyata pada ekspresi gen Cu-SOD antara ikan yang aktif dan lemas hanya terjadi pada jam ke-6. Dengan demikian, gen Cu-SOD berpotensi digunakan sebagai marka dengan membandingkan sekuen DNA ikan yang aktif dan lemas pada jam ke-6 paska tantang nitrit., Nitrite is a toxic substance that naturally occurs in waters. Nitrite exposure can induce the production of reactive oxygen species (ROS) which can damage the physiology of cells in the fish body. Cu-SOD gene sequences are genes that encode the regulation of antioxidant enzymes to reduce the impact of ROS. This study aims to analyze the performance of Cu-SOD gene expression of catfish fry against nitrite stress in the LC70 challenge test. The method used were lethal concentration 70 (LC70). According to the results of determining the concentration of LC70, catfish fry were given exposure to nitrite of 32.3 mg / L. There were two types of samples, namely active and limp fish, which were taken at 6, 12, and 24 hours respectively. At 0 hours, 4 fish treated with nitrite were taken as initial samples. Fish samples were taken in the ventral part, to be precise about organ and body muscle under the gills to approach the tail. Water quality samples were taken at 0, 12, and 24 hours. Relative expression of Cu-SOD gene in active catfish fry from 0 to 12 hours was relatively the same and increased significantly at 24 hours. In limp catfish fry, gene expression at 0 and 6 hours did not show a significant difference between the two, then decreased at 12 hours which showed significantly different, and at 24 hours increased significantly. The real difference in Cu-SOD gene expression between active and limp fish only occurred at the 6th hour. Thus, the Cu-SOD gene could potentially be used as a marker by comparing the DNA sequences of active and limp fish at 6 hours post nitrite
Keyword: Expression, Nitrite, LC70, ROS, Cu-SOD

Judul: Survival of second-generation catfish (Clarias  gariepinus) carrying SNP2 Lys-C gene marker under nitrite stress
Abstrak: Budidaya intensif dapat menimbulkan senyawa beracun seperti nitrit. Ikan lele yang memiliki marka single nucleotide polymorphism 2 (SNP2) gen Lys-C merupakan hasil pemuliaan dengan ketahanan terhadap Aeromonas hydrophila. Namun, ikan ini belum dianalisis kelangsungan hidupnya terhadap cekaman nitrit. Penelitian ini bertujuan menganalisis kelangsungan hidup ikan lele generasi kedua yang membawa marka SNP2 gen Lys-C terhadap cekaman nitrit. Ikan lele bergenotipe TT disilangkan dan dipelihara sampai mencapai ukuran 8-9 cm. Analisis pewarisan genotipe dilakukan dengan metode polymerase chain reaction. Uji cekaman dilakukan dengan nitrit konsentrasi 10 ppm sebanyak 20 ekor per perlakuan dengan 3 kali ulangan dari 3 persilangan TT⨯TT dan satu persilangan induk sangkuriang sebagai pembanding. Parameter yang diamati yaitu tingkat kelangsungan hidup, kualitas air, jumlah eritrosit, dan kadar glukosa. Hasil menunjukkan bahwa persilangan TT⨯TT memiliki keturunan 100% bergenotipe TT, sedangkan lele sangkuriang memiliki 3 genotipe berbeda. Tingkat kelangsungan hidup pasca cekaman nitrit berkisar 55,00-68,33%, lebih rendah dibandingkan sangkuriang (73,33%)., Intensive cultivation can produce toxic compounds such as nitrite. Catfish with a single nucleotide polymorphism 2 (SNP2) marker in the Lys-C gene are the result of breeding for resistance against Aeromonas hydrophila. However, the survival of these fish under nitrite stress has not been analyzed. This study aims to analyze the survival of second-generation catfish carrying the SNP2 marker in the Lys-C gene under nitrite stress. Catfish with the TT genotype were crossed and reared until they reached a size of 8-9 cm. Genotype inheritance analysis was performed using the polymerase chain reaction method. Nitrite stress tests were conducted with a concentration of 10 ppm on 20 individuals per treatment, with 3 replications of the TT⨯TT cross and one replication of the Sangkuriang parental cross as a comparison. The parameters observed were survival rate, water quality, erythrocyte count, and glucose level. The results showed that the TT⨯TT cross had offspring that were 100% TT genotype, while Sangkuriang catfish had three different genotypes. The post-nitrite stress survival rate ranged from 55.00 to 68.33%, which was lower than that of Sangkuriang catfish (73.33%).
Keyword: Genotipe, Kelangsungan hidup, Nitrit, Resistan, SNP

Judul: Penggunaan Teorema Homeomorphy 2-Manifold dan Teorema Euler Poincare pada Torus 𝑇�� dan Simplicial Complex 𝐾��
Abstrak: Two dimensional topological spaces are said to be homeomorphic if they have the same topological invariant, where one of topological invariant used is an Euler characteristic. Homeomorphy 2-Manifold’s Theorem and Euler Poincare’s Theorem are used to distinguish two topological spaces. Homeomorphy 2-Manifold’s Theorem uses Euler characteristic to identify two dimensional topological spaces. Euler Poincare’s Theorem is an alternative way to find Euler characteristic with Betti number, which is topological invariant as well. The objective of this paper is to investigate the homeomorphism of torus 𝑇����� and simplicial complex 𝐾�����. Topological space torus and simplicial complex 𝐾����� have the same Euler characteristic, which is two. Based on Homeomorphy 2-Manifold’s Theorem topological space torus 𝑇����� and simplicial complex 𝐾����� is homeomorphic.
Keyword: simplicial, torus, Euler, homeomorphism, topology