Schistosoma mansoni: germ-line transformation approaches and actin-promoter analysis.

Towards germ-line transformation miracidia were biolistically transformed with GFP reporter gene constructs and successfully reintroduced into the schistosome cycle. By PCR and confocal microscopy the presence and the expression of GFP were confirmed in cercariae or adults of the F(0) and F(1) generations. This indicated the presence of the constructs in the germ-line, although no evidence for genome integration was obtained.

Biolistic transformation of Schistosoma mansoni with 5' flanking regions of two peptidase genes promotes tissue-specific expression.

The gene-regulatory elements controlling peptidase expression in Schistosoma mansoni are unknown. A genomic DNA library was constructed from which 5' flanking fragments of the cathepsins F (SmCF; 649 bp) and B2 (SmCB2; 810 bp) peptidase genes were isolated. These were cloned into a GFP-expression vector for biolistic transformation of schistosomes.

Transplantation of in vitro-generated Schistosoma mansoni mother sporocysts into Biomphalaria glabrata.

Specific studies on schistosome gene functions require both access to the parasite stages, preferably the larvae, and to complete the life cycle. In the present study, we investigated whether short-term in vitro cultivation of sporocysts and surgical transplantation into snails could be combined to produce cercariae. Miracidia were maintained in vitro in the presence of Biomphalaria glabrata embryonic (Bge) cells or, alternatively, in Bge-cell-conditioned medium.

The uptake of Texas Red-BSA in the excretory system of schistosomes and its colocalisation with ER60 promoter-induced GFP in transiently transformed adult males.

The excretory system of schistosomes has focused some attention during the last years since accumulating evidence suggests that it plays an important role in the host-parasite interaction. Signalling molecules such as phosphatases, but also proteases have been localised in the excretory system. To some extent, however, localisation studies are limited by the fact that sections of fixed specimens are used.

Characterisation of the cysteine protease ER60 in transgenic Schistosoma mansoni larvae.

Proteinases have been found to play important roles in parasites. They are involved in developmental processes and facilitate invasion of host tissues as well as the digestion of host molecules for nutrition. The cysteine protease ER60 from Schistosoma mansoni, originally characterised in adults to be expressed in excretory organs, was analysed in larval stages.

HSP70-controlled GFP expression in transiently transformed schistosomes.

Among the parasitic helminths schistosomes are of high medical and economic importance. Despite of the world-wide relevance of this parasite, very little is known about the cellular mechanisms controlling its development and concerning the host-parasite interaction. Within the last decade a great effort has been made in this blood fluke to identify genes which play important roles during these processes.