|
|
Laboratory cycles of schistosomes, breeding of intermediate snail hosts and their ecological requirements
Nečasová, Monika ; Mikeš, Libor (advisor) ; Horák, Petr (referee)
The Schistosomatidae family is an important group of blood flukes, including serious human and livestock animal pathogens. With regard to reproduction, they are gonochoristic parasites. Their life cycle has two stages - asexual reproduction in an intermediary host (fresh water and sea gastropods) and sexual reproduction in the definitive host (mammals and birds). With regard to their pathogenicity at the definitive hosts, the blood fluke life cycle is abundantly maintained in laboratories. To preserve the whole cycle, the intermediary host gastropods are very important, They can include, without limitation, representatives of the Lymnaeidae family. However, their sensitivity to parasitism by blood flukes varies significantly by species. Floats were classified into several genera according to various parameters in the past. The systematics was most frequently based on anatomic and morphological differences. However, the most precise taxonomies are based on molecular data and mutual phylogenetic relationships of Lymnaeidaegastropods remain a subject of research. It is a fresh water family of gastropods with specific ecological and nutritional requirements. Summary information about their ecology estimate that the float gastropods are highly sensitive to the presence of heavy metals in water, such as...
|
|
|
Determination of gastropods of the genus Radix, the intermediate hosts of trematodes
Mikešová, Kateřina ; Beran, Luboš (referee)
Lymnaeid snails of the genus Radix are common freshwater molluscs of Europe. Formerly, the following species have been reported from the Czech Republic according to the morphology of the shell: R. auricularia, R. peregra, R. ovata and R. ampla. However, recent studies involving molecular data revealed that species determination based on traditional approaches employing morphology of the shell and gonads can be more complicated, confusing and not fully reliable. The shape of the shell is affected by particular life conditions of the snails and proves to be highly variable. The characteristics that can be found on gonads are dependent on the reproductive phase of the snail, and sometimes also on the presence of trematode larval stages, which can cause parasitic castration. Recently, molecular taxonomy is the most reliable approach, especially when a combination of sequences of mitochondrial and nuclear DNA is used. As molecular analyses are relatively time-consuming and expensive, some authors try to find some additional morphological features that could be used for determination of Radix snails in the field, without the need of demanding equipment. Problems in taxonomy and systematics of members of the genus Radix have a practical point in studies of trematode life cycles. From the view of human and...
|
guest ::
