A-D-G-J: ultrastructural analyses of the kinetoplast in the different developmental stages of T. cruzi. The kinetoplast of intermediate forms (G) is larger than the bar-shaped kinetoplast of selleck screening library epimastigotes (A) and amastigotes (D). The trypomastigotes (J) present a more relaxed kDNA organization, contained within a rounded kinetoplast. TcKAP4 (B-E-H-K) was distributed throughout the kinetoplast DNA network in epimatigotes (B) and amastigotes (E-arrow). In intermediate forms (H)

and in trypomastigotes (K), TcKAP4 was distributed mainly at the periphery of the kDNA. The same result was observed for TcKAP6 (C-F-I-L). A homogenous distribution for all kinetoplast was observed in epimastigotes (C) and amastigotes (F-arrows), while Trichostatin A solubility dmso a more peripherical distribution was seen in intermediate forms (I) and trypomastigotes (L). Bars = 0.25 μm. k = kinetoplast, n = nucleus, bb = basal body. In this work we showed for the first time that the distribution of TcKAPs in different developmental stages of T. cruzi is related to the kinetoplast format: in disk-shaped structures, like those found in epimastigotes and amastigotes, proteins are seen dispersed through the

kDNA network. Conversely, in intermediate and rounded kinetoplasts, like those observed in intermediate forms and trypomastigotes, KAPs are mainly located at the kDNA periphery. Taken together, these data indicate that the kDNA rearrangement that takes place during the T. cruzi differentiation process, is accompanied by TcKAP4 and TcKAP6 redistribution within the kinetoplast. It means that TcKAPs could determine, at least in part, the distinct topological organization of the kDNA networks. Although much information is available concerning the kinetoplast-associated proteins in C. fasciculata, it is still unknown how KAPs and other proteins interact with the DNA molecules to condense and determine the tridimensional arrangement of the kDNA network in trypanosomatids. Further studies using gene knockout to inhibit the expression of KAPs or assays to over-express these proteins, 4��8C would help us understand

the biological function of TcKAPs in T. cruzi and their involvement (or not) in the topological rearrangements of kDNA during the parasite morphogenetic development. Conclusion TcKAPs are candidate proteins for kDNA packaging and organization in T. cruzi. The trypanosomatid genomes sequenced to date have several sequences that share some degree of similarity with CfKAPs studied so far (CfKAP1–4). We have organized these sequences according to coding and syntenic information and have identified two potentially novel KAPs in these organisms, KAP6 and KAP7. Additionally, we have characterized two KAPs in T. cruzi, TcKAP4 and TcKAP6, which are small and basic proteins that are expressed in proliferative and non-proliferative stages of the parasite.