Cloning The Ultrabithorax And Its Expression In Embryo Of Locusta Migratoria Manilensis (Meyen)

Locusta migratoria manilensis (Meyen), belonging to the order of Orthoptera, is apaurometabolous insect that has well-developed wings and strong flight capability. Thefact that this insect is capable of grouping together and long-distance migration ismainly responsible for its ability to cause great damages and economic loss.Ultrabithorax (Ubx) gene, a member of Hox gene family, is mainly involved incontrolling the development of the body parts from the mesothorax to the first segmentof abdomen in insects, and thus plays important roles in the differentiation of metameres,the degeneration of abdominal appendages, and the formation of wings. In recent years,studies of the Ubx gene conducted in a number of species such as Drosophilamelanogaster, Tribolium castaneum, Junonia coenia, Bombyx mori, Oncopeltusfasciatus, have shown that the Ubx gene is implicated in causing the morphologicaldifferences between forewings and hindwings in these species. However, few similarstudies have been conducted in species in the order of Orthoptera that have a relativelylow phylogenetic status, including Locusta migratoria manilensis (Meyen). Therefore, acomparison of the Ubx gene between Locusta migratoria manilensis (Meyen) and otherspecies will not only contribute to understanding the molecular mechanism by whichthe morphological differences between forewings and hindwings is caused, but alsoprovide molecular basis for studying the evolution of the Ubx gene.In the present study, the embryonic expression of the Ubx gene in Locustamigratoria manilensis (Meyen) was studied using cloning, semi-quantitative PCR andreal-time quantitative PCR, and an immunohistochemical analysis was also performedto study the expression of the Ubx gene in forewings and hingwings of this insect. Theroles of the Ubx gene in causing the morphological differences between forewings andhingwings of this insect are discussed. Results are summarized as follow:①Cloning of a conserved segment of the Ubx geneA conserved segment was identified by aligning the published sequences of theUbx gene, and a conserved segment, termed "LmUbx", which is225bp in size and encodes74amino acids, was then cloned from the Ubx gene of Locusta migratoriamanilensis (Meyen) using RT-PCR. LmUbx, which contains two domains, YPWM andHomdomain, exhibits a higher similarity to IVa than the other5Ubx isoforms ofDrosophila.②Embryonic Expression of LmUbxEmbryonic Expression of LmUbx was analyzed using semi-quantitative PCR andreal-time quantitative PCR. Transient high expression of LmUbx was observed in theearly embryo, followed by decreased expression. However, from dAEL4, theexpression increased gradually until it peaked on dAEL8, and in subsequent embryonicdevelopment, the expression decreased and then remained stable.③Differential Expression of LmUbx between Forewings and HindwingsUsing the monoclonal antibody FP6.87, which recognizes Ubx and abd-A, theimmunohistochemical analysis was performed on embryos at various developmentalstages. LmUbx was found to be expressed mainly in T3and A1, with its weakexpression detected in T2, consistent with results obtained with Ubx genes of otherinsects. The observation that LmUbx was significantly differentially expressed betweenforewings and hindwings suggests that this gene could be implicated in causing themorphological differences between forewings and hindwings in Locusta migratoriamanilensis (Meyen).