Project description:Hybrid generations usually face either a heterosis advantage or a breakdown that can be expressed by the level of parasite infection in hybrid hosts. Hybrids are less infected by parasites than parental species (especially F1 generations) or more infected than parental species (especially post-F1 generations). We performed the experiment with blood-feeding gill parasite Paradiplozoon homoion (Monogenea) infecting leuciscid species, Abramis brama and Rutilus rutilus, their F1 generation, and two backcross generations. Backcross generations tended to be more parasitized than parental lines and the F1 generation. The number of differentially expressed genes (DEGs) was lower in F1 hybrids and higher in backcross hybrids when compared to each of the parental lines. The main groups of DEGs were shared among lines, however, Abramis brama and Rutilus rutilus differed in some of the top gene ontology (GO) terms. DEG analyses revealed the role of heme binding and erythrocyte differentiation after infection by blood-feeding P. homoion. Two backcross generations shared some of the top GO terms representing mostly downregulated genes associated with P. homoion infection. KEGG analysis revealed the importance of disease-associated pathways. The majority of them were shared by two backcross generations. Our study revealed the most pronounced DEGs associated with monogenean infection in backcross hybrids, potentially explained by hybrid breakdown. The gene expression of F1 hybrids was little affected by P. homoion, suggesting the hybrid advantage.
Project description:Data on total weight and standard length of freshwater bream and perch, two of the most abundant fish species in the Volga River basin, were collected monthly from April 2016 to May 2017. Fish were caught using gill-nets with 50 and 80 mm mesh sizes. Linear regression analysis of log-transformed values was performed. Regression slope and intercept were used to obtain length-weight relationships and mean condition factors. The data can be used for calculation of the relative weights of given species and further efforts to develop a mathematical model for the Volga River ecosystem.
Project description:The main fish host reaction to an infection with third stage anisakid nematode larvae is a response in which host immune cells (macrophages, granulocytes, lymphocytes) in affected internal organs initially are attracted to the parasite whereafter fibroblasts may enclose the parasite forming granuloma. Generally, the reaction is non-lethal to the parasite which may survive for years in the fish host retaining infectivity to the final host. This may also apply for the anisakid nematode Contracaecum rudolphii (having the adult stage in cormorants, using copepods as first intermediate/paratenic host and zooplankton feeding fish as paratenic hosts). The present study has shown that most Contracaecum rudolphii larvae survive in bream (Abramis brama) (from Lake Balaton, Hungary) whereas the majority of the nematode larvae die in Cyprinus carpio (from Lake Hévíz, directly connected to Lake Balaton). Both cyprinid host species interacted with the nematode larvae through establishing a marked cellular encapsulation around them but with different effects. The differential survival in common carp and bream may theoretically be explained by ecological factors, such as the environmental temperature which either directly or indirectly affect the development of nematode larvae, and/or intrinsic host factors, such as differential immune responses and host genetics.
