Judul: Respon Kamper (Dryobalanops sumatrensis) pada Dua Media Tumbuh Berbeda: Indeks Perkembangan Daun, Laju Fotosintesis dan Profil Metabolit.
Abstrak: Dryobalanops sumatrensis (J. F. Gmel.) Kosterm atau kamper merupakan jenis pohon langka. Pemanfaatan jenis ini lebih berfokus terhadap penggunaan kayu dan resin, sedangkan bagian lainnya seperti daun belum dimanfaatkan secara optimal. Penelitian ini bertujuan untuk menentukan pengaruh respon kamper (D. sumatrensis) pada dua media tumbuh berbeda berdasarkan indeks perkembangan daun, laju fotosintesis dan profil metabolit. Parameter perkembangan daun diukur secara morfologi dengan plastochron index, pengukuran laju fotosintesis menggunakan instrument LICOR LI-6800 Portable Photosynthesis System, dan identifikasi metabolit dilakukan dengan kromatografi cair-spektrometri massa (LC-MS/MS). Hasil penelitian menunjukkan presentase usia LPI ≥ 5 pada media gambut lebih sedikit dibandingkan dengan media mineral yaitu 8 % dan 12 %. Laju fotosintesis D. sumatrensis berkisar antara 1-9 μmol m⁻² s⁻¹. Analisis metabolomik menunjukkan sebanyak 23 metabolit yang didominasi golongan senyawa flavanoid berhasil teridentifikasi dalam ekstrak daun.
Keyword: Dryobalanops sumatrensis, LC-MS/MS, metabolites, photosynthesis rate, plastochron index (PI)

Judul: Trancriptomic Analysis of Kamper (Dryobalanops aromatica) Grown in Peat Media and Mineral Soil
Abstrak: Dryobalanops aromatica is a highly economic value resin-producing tree. It has been known as an essential international trade commodity widely used in the perfume, cosmetics, medicine, and wood industries. In natural habitats, this adaptive species has been found to grow well on peatland and mineral soils. The information regarding adaptive genes in Indonesian native trees to abiotic stress is still very limited. The research was conducted to analyse the differential gene expression (DGEs) that can elucidate the role of several up-regulated and down-regulated genes under peat media and mineral soil treatments. DGE analysis was carried out using R software, Bioconductor package 'edgeR'. Using the Benjamini and Hochberg approach to control FDR (false discovery rate) with the value of FDR is 0.05), with a log2FC (log2 fold change) with minimal value 2 and p-value of 0.05, showed 320 contigs were up-regulated, and 439 contigs were down-regulated, while 58129 contigs were not significantly expressed. Furthermore, this study also presents an overview of the genes involved in different pathways, such as photosynthesis, carbon and energy metabolism, phytohormone-related genes, nitrogen metabolism, reactive oxygen species, and transcription factor. This information will be helpful in understanding D. aromatica molecular responses to stress conditions that may be useful for selecting genotypes in the breeding programs or peatlands restoration. We found that genes involved in plant stress phytohormone biosynthesis, such as JA (jasmonic acid), ET (ethylene), GB (gibberellic acid), were up-regulated. In contrast, genes involved in ABA and IAA showed down-regulated on peat media treatment. Further, genes encode biological functions of the cell wall, and molecular functions as metal ion binding were up-regulated. Genes that function as antibiotics and ROS scavengers such as Peroxidase and Superoxide dismutase [Fe]2, chloroplastic were also found up-regulated. The transcription factors MYB26, NAC43, and NAC73 are thought to be transcription factors involved in the defense responses to D. aromatica in peat stress treatment. Molecular phylogeny analysis was carried out on the sequences of genes related to the adaptability of D. aromatica to the peat media stress to determine the evolutionary history, kinship relationships, and related gene functions. Homologous genes show different expression up-/down-regulations patterns. However, the alignment and phylogenetic analysis results showed an identity matrix and a distance matrix showing differences between up-regulated and down-regulated homologous genes. The differences between these genes are thought to be due to differences in the specific motifs of their constituent bases.
Keyword: adaptation, Dryobalanops, phylogenetic, Transcriptome, RNA-seq

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
Keyword: