Early development and plasticity in brown algae: Dictyota's Dilemma's

Master Thesis subject (30 ECTS)
Oceans and Lakes
During embryogenesis of plant systems the basic body plan of the organism is laid down. In a first step, the sides of the zygote that will develop into the basal attachment structure and the apical photosynthetic organs are determined in a process called cell polarisation. Because of practical advantages over land plant zygotes, the brown alga Fucus serves already for more than 150 years as a research model for cell polarization and early development in plant systems. Egg cells are liberated as radial symmetrical ‘soccer ball-shaped’ cells. After fertilization the cell is polarized according to the direction of the incoming light in a single step. Recent developments show a totally different image for embryogenesis in the common genus Dictyota. The spherical ‘soccer ball-shaped’ egg cells are also liberated in the surrounding medium, but elongate immediately after fertilization into a ‘rugby ball-shaped’ cell. In contrast to Fucus and most animal systems the embryo is polarized in two steps and the determination of the attachment pole can be postponed long after the first cell division. This suggest an unseen degree of developmental plasticity in the establishment of the apical-basal axis and asymmetric cell division. It is hypothesized that on basis of the accumulation of one or more pheromones and kairomones in the surrounding medium the zygote can determine whether it should postpone the development of its attachment structure, possibly promoting colonization of new habitats and inhibiting competition. In this research, it is envisaged to acquire more insights in the mechanisms that can influence the timing of polarization with the help of molecular tools, lab experiments and field work. The subject is diverse and can be reoriented in different directions depending on the personal interest of the student.
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Reference Number: RP-48981