Li W C, Riddiford L M
Department of Zoology, University of Washington, Seattle 98195.
Nucleic Acids Res. 1994 Aug 11;22(15):2945-50. doi: 10.1093/nar/22.15.2945.
Two gene-specific probes were generated from the unique sequences in the 3' non-coding regions of the two insecticyanin genes, ins-a and ins-b to study the developmental expression of these genes in Manduca sexta. Both genes were initially transcribed in the freshly hatched first instar larvae and then expressed in the epidermis and to a lesser degree in the fat body during every larval feeding stage. In the epidermis of the 4th and 5th instar larvae, both mRNAs appeared shortly before ecdysis and accumulated to maximal levels within a day. As the larval epidermis became pupally committed on day 3 of the 5th (final) instar, INS-a mRNA quickly decreased, whereas INS-b mRNA showed a second peak of accumulation. In the fat body, both genes showed a similar expression pattern within the 4th instar to that of the epidermis except that levels were lower and ins-b mRNA dominated. In the final instar, only ins-b mRNA was present in significant amount. These findings not only reveal that the two duplicated insecticyanin genes have diverged in their expression pattern but also demonstrate, for the first time, that fat body also expresses insecticyanin genes.
从两种昆虫蓝蛋白基因ins-a和ins-b的3'非编码区的独特序列中制备了两种基因特异性探针，以研究这些基因在烟草天蛾中的发育表达情况。这两种基因最初在刚孵化的一龄幼虫中被转录，然后在每个幼虫取食阶段在表皮中表达，在脂肪体中的表达程度较低。在四龄和五龄幼虫的表皮中，两种mRNA在蜕皮前不久出现，并在一天内积累到最高水平。当五龄（最后一龄）幼虫的第三天幼虫表皮开始向蛹转变时，INS-a mRNA迅速减少，而INS-b mRNA出现第二个积累峰值。在脂肪体中，这两种基因在四龄幼虫中的表达模式与表皮相似，只是水平较低，且ins-b mRNA占主导。在最后一龄幼虫中，只有大量的ins-b mRNA存在。这些发现不仅揭示了两个重复的昆虫蓝蛋白基因在表达模式上已经发生了分化，而且首次证明脂肪体也表达昆虫蓝蛋白基因。
