家蚕不同茧色品种中尿苷二磷酸-葡萄糖基转移酶(UGT)基因的表达差异

Differential Expression of UDP-glucosyltransferase Genes in Bombyx mori Varieties that Spin Cocoons of Different Colors

尿苷二磷酸-葡萄糖基转移酶(UGT)是动物糖基化作用的关键酶。黄酮类色素是家蚕天然彩色茧中主要色素之一,桑叶中的黄酮色素在蚕体内需通过糖基化修饰才能够进行生物转化。为了研究UGT对家蚕茧色的影响,选取在家蚕绿色茧品种大造丝腺或中肠中有表达的7个家蚕UGT基因(UGT59、UGT30、UGT60、UGT34、UGT86、UGT89、UGT65),用RT-PCR方法对这些基因在白茧品种C108和皓月、绿茧品种大造和G1、黄茧品种Y12和黄茧限性品种Ys的丝腺、中肠和生殖腺组织中的表达进行了定性与定量分析。结果显示,上述品种中UGT89和UGT65基因只在丝腺特异表达;UGT86基因在丝腺的表达量最高,无茧色特异性;UGT60和UGT34基因在有色茧品种的中肠组织特异性表达;UGT59和UGT30基因在绿茧品种的丝腺和中肠组织特异性高量表达,UGT30基因在不同茧色品种还存在mRNA转录本的差异,显示出茧色特异性。对限性黄茧品种Ys的调查显示,UGT60和UGT86基因的表达在生殖腺存在性别差异,而在丝腺和中肠组织没有性别差异。提示UGT60和UGT34基因的表达与天然彩色茧色素在中肠的吸收有关,UGT59和UGT30基因表达与绿茧色形成有关,而UGT60和UGT86基因在生殖腺的差异表达与性别可能存在关联。

UDP-glycosyltransferase（UGT） is a key enzyme involved in glycosylation in animals.In Bombyx mori,it has been found that flavonoid compounds constitute the major pigments in the filaments of natural colorful cocoon and the flavonoid compounds from mulberry leaf need to undergo glycosylation before biotransformation can occur in Bombyx mori larvae.In order to investigate the influence of UGT on Bombyx mori cocoon color,seven UGT genes namely UGT59,UGT30,UGT60,UGT34,UGT86,UGT89 and UGT65 of which expression were observed in silk gland or midgut of Dazao,a Bombyx mori strain that spins green cocoons,were selected and analyzed both qualitatively and quantitatively by RT-PCR for their expressions in silk gland,midgut and gonad tissues from white cocoon varieties C108 and Haoyue,green cocoon varieties Dazao and G1,yellow cocoon variety Y12 and yellow cocoon sex-limited strain Ys.The results showed that UGT89 and UGT65 were only expressed in silk gland.The expression of UGT86 in silk gland is obviously higher than that in midgut and ingonad.UGT60 and UGT34 were highly expressed in the midgut tissues of color cocoon varieties.UGT59 and UGT30 were highly expressed in silk gland and midgut tissues of green cocoon varieties and mRNA transcript of UGT30 varied with the varieties of different cocoon colors,showing a typical cocoon color specific expression pattern.Investigations to yellow cocoon sex-limited strain Ys indicated that the expression of UGT60 and UGT86 was different in gonads of different sexes but had no difference in silk gland and midgut tissues of different sexes.The above results suggest that UGT60 and UGT34 genes are involved in pigment uptake in the midguts of natural colorful cocoon varieties,UGT30 and UGT59 genes are related to the formation of green cocoon color,and the differential expressions of UGT60 and UGT86 genes in gonads could be sex-linked.