Regulation of soluble and membrane-bound trehalase activity and expression of the enzyme in the larval midgut of the bamboo borer Omphisa fuscidentalis
Regulation of soluble and membrane-bound trehalase activity and expression of the enzyme in the larval midgut of the bamboo borer Omphisa fuscidentalis
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DOI：
10.1016/j.ibmb.2008.05.003
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发表时间：
2008-08-01
影响因子：
3.8
通讯作者：
Sakurai, Sho
中科院分区：
文献类型：
--
作者：
Tatun, Nujira;Singtripop, Tippawan;Sakurai, Sho
fuscidentalis滞育幼虫在中肠中含有可溶性和膜结合海藻糖酶。可溶性海藻糖酶活性占中肠匀浆中总海藻糖酶活性的四分之三。滞育幼虫暴露于幼虫激素类似物（JHA）诱导化蛹，并伴随可溶性海藻酶活性在蛹前期的增加。注射20-羟基蜕皮激素（20E）后5天可溶性海藻酶活性水平呈剂量依赖性增加。相反，在相同的条件下，膜结合海藻糖酶活性没有增加。我们分别克隆了O. fuscidentalis海藻酶-1 （OfTreh-1）和海藻酶-2 （OfTreh-2）可溶性和膜结合形式海藻酶的cdna。Treh-1编码581-aa蛋白，Treh-2编码648-aa蛋白，在c端附近有一个推测的跨膜结构域。在滞育幼虫中肠中Treh-1的mRNA表达量是Treh-2的27倍。滞育幼虫暴露于JHA后，Treh-1 mRNA表达量逐渐升高，至蛹前显著升高；Treh-2的mRNA表达维持在初始水平。同样，20E上调Treh-1的表达，但对Treh-2的表达没有影响。综上所述，这些结果表明，化蛹时可溶性海藻酶活性的增加是由Treh-1基因的上调引起的。此外，膜结合海藻糖酶似乎不参与在幼虫-蛹转化过程中发生的血淋巴海藻糖浓度的动态变化。(c) 2008 Elsevier Ltd.版权所有。
Diapausing larvae of Omphisa fuscidentalis contain soluble and membrane-bound trehalase in the midgut. Soluble trehalase activity accounts for three-fourths of the total trehalase activity in midgut homogenates. The exposure of diapausing larvae to juvenile hormone analog (JHA) induced pupation, accompanied by an increase in soluble trehalase activity at the beginning of the prepupal period. Injection of 20-hydroxyecdysone (20E) increased the level of soluble trehalase activity 5 days postinjection in a dose-dependent manner. In contrast, no increase in membrane-bound trehalase activity was observed under the same conditions. We cloned the cDNAs that encode the soluble and membrane-bound forms of trehalase in O. fuscidentalis trehalase-1 (OfTreh-1) and trehalase-2 (OfTreh-2), respectively. Treh-1 encodes a 581-aa protein while Treh-2 encodes a 648-aa protein with one putative transmembrane domain near the C-terminus. The mRNA expression level of Treh-1 was 27-fold higher than that of Treh-2 in diapausing larval midgut. Following the exposure of diapausing larvae to JHA, Treh-1 mRNA expression increased gradually until the prepupal period whereupon it increased dramatically; in contrast, the mRNA expression of Treh-2 remained at its initial level. Similarly, 20E upregulated Treh-1 expression but had no effect on Treh-2 expression. Taken together, these results suggest that an increase in the soluble trehalase activity at pupation is caused by upregulation of Treh-1 gene. Moreover, membrane-bound trehalase does not appear to be involved in the dynamic changes in the hemolymph trehalose concentration that occur during the larval-pupal transformation. (c) 2008 Elsevier Ltd. All rights reserved.