The Role of Shroom in Xenopus

In the process of the morphogenesis of species as diverse as insects, vertebrates, nematodes, and echinoderms, the apical constriction of the polarized epithelial cells is observed in the bending epithelial sheets. The constricted cells in an apical way, which are primarily seen in the locally bending locations where the neuroepithelium is, have been researched for a long time within the closing neural tube of vertebrate embryos (Haigo, et. Al. 2126). Notably, some separate tissue movements lead to “the closure of the neural tube, and since it has been hard to uncouple them, the apical constriction's particular role in the course of neurulation is still ambiguous” (Haigo, et. Al. 2126). However, the embryological processes in chicks have shown that apical constriction is indeed a dynamic process within neural plate.

In spite its eminence as being a concept for elucidating the epithelial morphogenesis, not much has been known concerning the way the coordination of the apical constriction might be carried out at the molecular and cellular level. For instance, the constriction is continuously correlated with the apically confined actin filaments; however, the vitality of the apical act is still unknown (Haigo et al. 2127). In the same way, only a small number of the molecules have been found out as being the apical constriction regulators within the neural plate; for instance, p190RhoGAP is among these regulators. Even if there is minimal mechanistic comprehending of the apical constriction, a large number of genes needed for the regular closing of the neural tube have been found it. In this regard, one kind of such gene serves to encode the actin binding protein referred to as Shroom. The misexpression of this protein undertakes the recruitment of actin to the ectopic sites within the cultured cells; however, how it affects the epithelial cells' behavior and how it controls the biomechanics of neurulation is still unexplored (Schoenwolf 498). Fundamentally, in this research, the undifferentiated cells of quite early Xenopus embryos is utilized as being a source of the naive and heterologous epithelia cells where to study the Shroom function. Notably, it will be indicated that Shroom expression is adequate to bring about the apical constriction within these cells, which is a new property for any vertebrate protein. Ostensibly, Shroom does not tend to have an effect on the non-polarized cells during the early blastulae. In the course of the normal development, there is the expression of Xenopus Shroom, which is carried out in the cells going through an apical constriction.

Shroom is adequate for inducing apical constriction of the naive epithelial cells. In this regard, to evaluate the Shroom’s activities, there is a need to express the protein within the population of the epithelial cells. The blastomeres' outer layer within the early Xenopus blastula offers the best model epithelium. Just like in most animals, the outer cells of cleavage-stage Xenopus embryo make the epithelium having strong apicobasal polarity dn this shown by the apically contained epithelial junctions, as well as by the apicobasal differences within the membrane adhesive properties together with targeting secretory vesicles and membrane proteins.

In the course of the early development, such epithelial cells are found to be undifferentiated and stay being transcriptionally quiescent for several hours; hence, ectopic protect effect on the behavior of cells serves to represent a direct impact of the protein on the cellular mechanism that is already in place within the naive epithelial cells. Fundamentally, to test the Shroom’s function, there is injecting of the mRNA into the animal pole of some two blastomeres in four cell Xenopus blastulate. After that, there effects are examined before blastomeres differentiation and before the beginning of the zygotic transcription. The expression of the wild-kind mouse Shroom induces a dramatic pigment concentration within undifferentiated blastomeres. Since the pigment granules are localized apically, the cells’ apical constriction brings about an increased pigments granules density. Moreover, to carry out the test on the likelihood that the concentration of the Shroom-induced pigment results from the apical constriction, there is examining of the external shroom-expressing blastulae, in comparison with the cuboidal control cells. The pigment concentrations, as well as apical constriction, are observed after Shroom expression in any external blastomere, irrespective of presumptive fate or position.

When observed from the surface, the cells, which are darkly pigmented, appear to have some smaller surface compared to the neighboring cells that are normally a pigment and this is in line with apical constriction. To authenticate this finding, there is a need to quantify the apical surface are of the Shroom-expressing cells. In this regard, the average surface is of the darkly pigmented outer blastomeres in the Shroom-expressing blastulae is found not to be different from the one of uninjected blastibulae.























Works Cited

Haigo, Saori et al. “Shroom Induces Apical Constriction and Is Required for Hingepoint Formation during Neural Tube Closure.” Current Biology, vol. 13, no. 14, 2003, pp. 2125-2137.

Schoenwolf, Charles. “Microsurgical analyses of avian neurulation: separation of medial and lateral tissues.” J. Comp. Neurol, vol. 276, 1988, pp. 498-507.