Petra Navrátilová

Does invasive Chondrostoma nasus shift the parasite community structure of endemic Parachondrostoma toxostoma in sympatric zones

BackgroundThe composition of parasite communities in two cyprinid species in southern France – native and threatened Parachondrostoma toxostoma and introduced Chondrostoma nasus – was investigated. In sympatry, these two species form two hybrid zones in the Durance and Ardeche Rivers. Due to their different feeding preference and habitat positions in allopatry, we supposed a difference in parasite communities between fish species. We expected more similar parasite communities in sympatric zones associated with habitat overlap (facilitating the transmission of ectoparasites) and similar feeding (more generalist behaviour when compared to allopatry, facilitating the transmission of endoparasites) in both fish species. Finally, we investigated whether P. toxostoma x C. nasus hybrids are less parasitized then parental species.MethodsOne allopatric population of each fish species plus two sympatric zones were sampled. Fish were identified using cytochrome b gene and 41 microsatellites loci and examined for all metazoan parasites.ResultsA high Monogenea abundance was found in both allopatric and sympatric populations of C. nasus. Trematoda was the dominant group in parasite communities of P. toxostoma from the allopatric population. In contrast, the populations of P. toxostoma in sympatric zones were parasitized by Dactylogyrus species found in C. nasus populations, but their abundance in endemic species was low. Consequently, the similarity based on parasite presence/absence between the sympatric populations of P. toxostoma and C. nasus was high. Sympatric populations of P. toxostoma were more similar than allopatric and sympatric populations of this species. No difference in ectoparasite infection was found between P. toxostoma and hybrids, whilst C. nasus was more parasitized by Monogenea.ConclusionsThe differences in endoparasites between P. toxostoma and C. nasus in allopatry are probably linked to different feeding or habitat conditions, but host-parasite evolutionary associations also play an important role in determining the presence of Chondrostoma-specific monogeneans. Our findings suggest that Dactylogyrus expanded with the source host C. nasus into introduced areas and that P. toxostoma became infected after contact with C. nasus. Although the genotype of P. toxostoma and recombinant genotypes of hybrids are susceptible to Dactylogyrus transmitted from C. nasus, the intensity of infection is low in these genotypes.

COGNITIVE DEFICIT IN SCHIZOPHRENIA AND ITS REMEDIATION

Schizophrenia is a severe mental disorder characterized by a variety of signs and symptoms. Since its earliest conception as “dementia praecox“ (i.e. early onset dementia), impaired cognitive function has also been considered a core feature. Research into cognition and schizophrenia over the past years has recently been growing. Cognitive deficit is a virtually omni-present component of schizophrenic psychopathology, independent of other aspects of schizophrenia. It underlays other symptoms of schizophrenia and affects the success of therapy, ability of social adaptation and patients’ quality of life. Cognitive skills in schizophrenia predict social functioning and may serve as outcome measures in the development of effective treatment strategies. One of the possibilities of non-pharmacological improvement of cognitive function is remediation using computer rehabilitation software. It has been proved as an effective method. In our study we found global positive effect of aproximately bimonthly (20sessions) training of cognitive function in patients with schizophrenia using computer rehabilitation software PSS CogRehab. Except verbal fluency, which appears stationary during training of cognitive function, all others domains of cognitive function improved during rehabilitation using computer training of cognitive function. The biggest improvement we located in these domains: psychomotor speed, auditive reaction time and verbal learning and memory, where improvement in neuropsychological tests reached statistically significant difference.

LONGITUDINAL STUDY OF COGNITIVE DEFICIT IN THE FIRST EPISODE SCHIZOPHRENIA

Abstrakta referujici o dlouhodobem sledovani kognitivnich funkci u pacientů s prvni epizodou schizofrenie.