Overexpression of the isolated protease domain of the Nudel protein does not affect Dorsal-Ventral polarity determination in Drosophila

Abstract

Most of living organisms begin life from one-cell egg. Generally, an egg begins developments after it gets fertilized. From very early stages, however, depending on the locations in an embryo, each embryonic cell undergoes specific patterns of differentiation. Therefore, the determination and recognition of spatial coordination within an embryo are important before any other developmental events can occur. Due to the lack of zygotic genome, many embryos initially use maternal materials to generate the axes of head-to-tail (Anterior-Posterior, AP) and back-to-belly (Dorsal-Ventral, DV). Also, the environmental surroundings, such as the presence of an egg shell structure, can also influence the axes. In Drosophila, the existence of follicle cells surrounding the egg during its formation, which provide nutrition and genetic materials to an egg, generates asymmetrical egg shape. With the ability to distinguish specific region in the egg, researchers found the localization of maternal genetic materials at particular sites within the egg, and showed them to be responsible for the determination of the axes. Those maternal genes were identified to work as switches that will turn on and off zygotic genes we need to be expressed at a specific region or at the specific timing during development. Although the individual functions of maternal genes have been studies in artificial conditions, the combinatorial activities of those materials in living cells are still not fully understood. Mutations affecting the Nudel protein, one of the maternal gene products involved in development, produce an abnormal dorsal-ventral polarity in an embryo or an embryo with aberrant eggshell structure, depending on the position of the mutation within the protein. The unusually large size of protein Nudel is composed of several parts showing different functions. The increasing amount of one portion of protein Nudel, which has a function as an enzyme, does not affect the determination of DV axis or development of eggshell structure. Further research should address the functionality of Nudel protease whether it requires direct activities of Nudel protein or it has the correct construct to express the protease.