Judul: Studi Molekuler untuk Menentukan Kekerabatan Genus Zingiber Varietas Zerumbet
Abstrak: Problems due to opinion differences in medicinal plants classification cause confusion on the use of scientific name of plants. The grouping of plants which based on morphology in some cases is less effective and it is necessary to perform molecular studies used maturase (matK) and Internal Transcribe Spacer (ITS) as molecular markers. The study was aimed to classify members of the Zingiber genus Zerumbet subsection that is Zingiber zerumbet, Zingiber aromaticum, and Zingiber amaricans. Stages of research were isolation of DNA, DNA amplification, DNA sequencing, alignment of DNA sequences, and construction of phylogenetic tree. Results showed that the isolated DNA was of good quality. The size of the amplified DNA with the matK was 2000–3000 bp, while the size of the amplified DNA with the ITS was 900 bp. ITS sequences were of low quality, so that only the matK sequences were used for inference. Based on the results of sequence alignment with data obtained from GenBank differences between members of the genus Zingiber subsection Zerumbet with other types of Zingiber was 1–11 bp and the phylogenetic tree with consistency index (CI)= 0.897 and retention index (RI)= 0.833 shows a very close genetic relationship between the three members of the Zingiber genus Zerumbet subsection with bootstrap (BS)= 59. The third member of the Zingiber genus Zerumbet subsection is spesies kompleks which is under the type of Zingiber zerumbet.
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Judul: Analisis Biomolekuler Gen Internal Transcribed Spacer (ITS) dalam Studi Filogenetik Zingiber loerzingii Valeton (Zingiberaceae)
Abstrak: Zingiberaceae consists of 50 genera and 1400 species distributed in tropical and subtropical areas. The center of the diversity of Zingiberaceae is South Asia and Southeast Asia. Zingiber loerzingii is only found in Sumatera. Unlike other species, this species has not been well studied so the information is still limited, whereas the clarity of plant identity is very crucial. The present study was aimed to determine phylogenetic relationship of Zingiber loerzingii and its relative based on the Internal Transcribed Spacer (ITS) gene. DNA sample was isolated using cetyltrimethylammonium bromide based method of Doyle & Doyle modification. Amplification of ITS region resulted in ± 700 bp amplicon. Sequencing of ITS region of Zingiber loerzingii produced 813 bp DNA sequences that has high rate of evolution. Recontruction of phylogenetic tree was analysed using the Phylogenetic Analysis Using Parsimony program. The results of phylogenetic analysis showed that the genus of Zingiber formed a clade with bootstrap value of 61.9%. The clade consisted of two clades, clade I with bootstrap 62% and clade II with bootstrap 70.8%. Therefore, we conclude that the genus Zingiber is possibly monophyletic. Zingiber loerzingii is nested in clade I with the nearest or sister taxa: Zingiber rubens, Zingiber orbiculatum dan Zingiber fragile.
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Judul: Hamiltonian formulation for linear waves motion in two layers fluid
Abstrak: The surface wave could be considered as a wave that separates two fluids, namely water and air. Based on this assumption, it is introduced the interfacial wave, a wave between two layers of fluid with different density. The formulation of interfacial waves motion begins with deriving the base equation of irrotational ideal fluid. Furthermore, according to irrotational fluid assumption, the base equation can be stated in velocity potential. In this derivation, the fluids domain is assumed to be restricted by rigid lid boundary conditions, both at the upper and lower limit. Therefore, the interfacial waves motion can be explained in a hamiltonian formulation. In the hamiltonian formulation, total energy is defined as the sum of kinetic and potential energy. The hamiltonian system is obtained from reduction of kinetic energy by using the Dirichlet Neumann Operator. The resulted kinetic energy equation is nonlinear. Therefore, this form is linearized by first part of the Taylor expansion. This linearization gives a dispersion relation of linear wave. Based on this dispersion relation, the phase speed of the linear wave depends on the density ratio of the two layers fluid.
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