Identifikasi Gen Non Molting Dwarf (nmd) pada Mutan Ulat Sutera (Bombyx mori) Strain a47 Jepang dengan Metode Positional Cloning.

Abstract

Persilangan antar strain ulat sutera seringkali menimbulkan individu mutan gagal molting. Kejadian mutan non molting dwarf (nmd) mengakibatkan kematian pada sebagian populasi di usaha persuteraan alam. Mutan tersebut terjadi pada populasi larva instar pertama B. mori. Penelitian ini bertujuan mengidentifikasi ekspresi gen dan lokasi pasangan basanya yang bertanggung jawab terhadap pembentukan mutan nmd pada larva B. mori. Ulat sutera strain normal (p50T) disilangkan dengan ulat sutera mutan nmd (a47) Jepang hingga didapatkan generasi F2 melaui metode positional cloning. Karakterisasi basa DNA dianalisis langkah demi langkah melalui tahap purifikasi DNA hingga analisis PCR. Penerapan primer spesifik dapat mempersempit lokasi pasang basa DNA yang mengekspresikan mutasi nmd. Hasil penelitian menunjukkan bahwa lokasi ekspresi gen mutasi nmd berada pada kromosom 9 dengan kisaran pasangan basa 9330803 bp - 12075121 bp (2.7 mb) yang mencakup 89 kandidat gen di dalamnya. Satu gen kandidat diprediksi penyebab mutasi nmd, adalah KWMTBOMO05189. Gen tersebut diduga berkaitan dengan dn-Ras yang menghambat pengaturan pelepasan hormon ekdison.

Crosses between silkworm strains usually emerged new mutant individuals that have non-molting conditions. The incidence of non-molting dwarf mutants (nmd) resulted in population mortality of up to half of population on natural silk factory. This nmd mutant was found in the population of first instar larvae of B. mori. This study aims to identify the gene expression and location of the base pairs that are responsible for the condition of the nmd mutant in B. mori larvae. Normal strain silkworms (p50T) were crossed with Japanese nmd (a47) mutant silkworms to obtain F2 generation through the positional cloning method. DNA base pairs characterization was analyzed step by step through the DNA purification phase to PCR analysis. The application of specific primers can narrow down the location of the DNA base pairs which express the nmd mutation. The results showed that the location of the nmd mutation gene expression was on chromosome 9 with a base pair range of 9330803 bp - 12075121 bp (2.7 Mb) which included 89 candidate genes on that range. One candidate gene predicted to express the nmd mutation is KWMTBOMO05189. This gene is thought to be related to dn-Ras which inhibits the regulation of ecdysone hormone.