Judul: Genetic structure and variation of five Shorea leprosula natural populations based on microsatellite marker
Abstrak: Shorea leprosula is an economically and ecologically important timber species and one of the most common tropical lowland rain forest tree species in Southeastern Asia. Eleven microsatellites DNA loci were used to investigate the genetic structure and diversity among five natural populations from Sumatera (CS and NS), Peninsular Malaysia (SM) and Borneo (WKa and WKb). Results indicated that expected mean heterozygosity (He) was high (0.721) with values ranging from 0.542 to 0.788, with the highest values found in the populations from west Kalimantan (WKb). Most of the populations showed high and positive fixation indices indicating excess of homozygotes. This implies a high level of inbreeding which may be caused by selfing or/and mating among relatives. A gene diversity analysis showed that 89.9% of the variation was harbored within populations and 11.1% (FST= 0.111) was due to differences among populations. STRUCTURE analysis showed that five natural populations were clustered into two main groups namely: i) Sumatera-Peninsular Malaysia, and ii) Borneo. Mean gene flow (Nm) was high (2.00) indicating extensive gene flow in the past among the natural populations. Three populations (WKb, NS and SM) were identified to be genetically unique and we recommended for further consideration in formulation of genetic conservation strategies.
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Judul: Variasi DNA Kloroplas Shorea spp (Shorea acuminata Dyer, Shorea leprosula Miq dan Shorea parvifolia Dyer) Berdasarkan Penanda Mikrosatelit.
Abstrak: Shorea acuminata, Shorea leprosula, and Shorea parvifolia are members of the Diptecarpaceae family. They are ecologically and commercially important in the Southeast Asia region. In this present study, we used chloroplast microsatellites (cpSSR) to study the variation within and among Shorea species populations and the distribution of chloroplast DNA haplotypes of Shorea species. Based on chloroplast microsatellite analysis, the following diagnostic haplotypes were detected; namely haplotype A, C, and D for S. leprosula, S. parvifolia, and S. acuminata, respectively. In general, haplotype variation of cpSSR was low in this studies. The highest within population variation of cpSSR was observed in S. acuminata. The highest genetic differentiation was detected in S. parvifolia (Gst = 0.58) followed by S. acuminata (Gst = 0.31) and S. leprosula (Gst = 0.14). The haplotypes distribute evenly among different populations and between islands, and do not correspond with geographical separation among populations and islands. Some haplotypes from one species were shared by other species, indicating the possibility of gene flow via interspecific hybridization, that occurred currently and/or in the past. Introgressive hybridization probably occurred among Shorea species due to co-existance in the forest stands and overlapping flowering times.
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Judul: Pemanasan Sekunder Reaksi Fusi Plasma dengan Menggunakan Radio Frequency
Abstrak: Plasma merupakan bentuk ke-empat dari materi setelah padat, cair dan gas yang terbentuk dari proses ionisasi gas. Plasma dapat digunakan dalam reaksi fusi, yaitu reaksi penggabungan dua inti atom ringan menjadi inti atom yang lebih berat sambil melepaskan energi. Untuk mendapatkan energi dari reaksi fusi, inti yang akan direaksikan harus dipanaskan pada temperatur yang sangat ekstrem tingginya. Salah satu cara agar dapat mencapai kondisi ini adalah memberikan pemanasan tambahan atau pemanasan sekunder kepada plasma dalam reaksi fusi tersebut. Nilai daya serap rata-rata ion Deuterium yang sesuai dengan selang nilai daya dari data ITER adalah daya yang menggunakan frekuensi 50 MHz sampai dengan 60 MHz. Dengan menggunakan frekuensi 60 Hz diperoleh nilai daya rata-rata yang diserap sebesar 1,235.10-12 W.
Keyword: gelombang radio, pemanasan sekunder, plasma, reaksi fusi