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: Keragaman Genetik Shore laevis Ridl. di Kalimantan Berdasarkan Penanda Mikrosatelit
Abstrak: Shorea laevis Ridl. is one member of commercial species from Dipterocarpaceae family. This species is also as one of the important trees in tropical rain forest, based on ecological and economic evaluation. In general, S. laevis distributes naturally in Peninsular Myanmar and Thailand, Peninsular Malaysia, Sumatera, Aceh, and Borneo Island. The objective of this study was to cross species amplify microsatellites and to estimate genetic variation within and among populations. This study used nuclear microsatellite analysis based on observed alleles and polymorphic loci. Results showed that S. laevis had moderate value of genetic variation within population (He) = 0,4443. In general, this value of genetic variation was smaller if compared to other Shorea species that also analysed by the same method. The closest genetic relationship (smallest distance) was possessed by S. laevis populations of Bukit Bangkirai and PT. ITCIKU, while the furthermost relationship (largest distance) was possessed populations of Batu Ampar and PT. Sari Bumi Kusuma.
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Judul: Katalis Zink Ferit Tersubstitusi Cu untuk Oksidasi Benzil Alkohol
Abstrak: Katalis berperan dalam menurunkan energi aktivasi. Katalis ZnFe2O4 dan ZnFe2O4 tersubstitusi Cu disintesis menggunakan metode kopresipitasi untuk digunakan dalam oksidasi benzil alkohol. Katalis dicirikan dengan spektrofotometer inframerah (FTIR) dan difraktometer sinar-X. Spektrum FTIR menunjukkan puncak serapan dari ikatan Zn-O dan Fe-O masing-masing pada rentang 559‒575 cm-1 dan 419‒447 cm-1. Difraktogram menunjukkan terbentuknya fase tunggal Zn0.6Cu0.4Fe2O4 pada katalis ZnFe2O4 tersubstitusi Cu 20%. Benzil alkohol dioksidasi dengan sistem refluks. Konversi benzil alkohol meningkat dengan meningkatnya suhu. Kadar benzaldehida yang dihasilkan dengan katalis ZnFe2O4 tersubstitusi Cu 20% lebih tinggi dibandingkan dengan katalis ZnFe2O4 yang tidak tersubstitusi dan yang tersubstitusi Cu 60 dan 80%. Hal tersebut menunjukkan bahwa katalis ZnFe2O4 tersubstitusi Cu 20% memiliki kinerja yang lebih baik dalam oksidasi benzil alkohol menjadi benzaldehida dengan kadar benzaldehida 8.763%.
Keyword: Benzil alkohol, katalis, oksidasi, ZnFe2O4