Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 2004. Sectio Biologiae. (Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 25)

Mustárdy, L.: Tree-dimensional Organization of Thylakoid System in Granal Chloroplasts and its Functional Role

Three Dimensional Organisation of Thylakoid System. 105 originally proposed for the illustration of the lateral heterogeneity. In this model, the stacking is thought to originate from invaginations. According to the model, stroma thylakoids do not directly continue the granum thylakoids. Instead, they form a 'fork': their 'upper' and 'lower' membranes are considered to originate from a layer 'above' and a layer 'below' the stacked pair of membranes. Such an arrangement, i.e. the interconnection of two granum compartments by a stroma thylakoid, can in fact, albeit rarely, be seen in electron micrographs. The reason for the appearance of 'forks' will be clear from the model based on serial sections. The main problem with this model is that, as ultrastructural studies on developing chloroplasts have revealed, the initiation of grana can be accounted for by the formation of multiple perforations, and by the overlapping of thylakoids at these slits, rather than invagination. It is still the model that is most frequently used in reviews and research papers; also available in a more elaborated form as a 3D computer model (Arvidsson and Sundby 1999). Acknowledgement This work was supported by research grant OTKA T042696.