Parasite manipulation of brain monoamines in California killifish (Fundulus parvipinnis) by the trematode Euhaplorchis californiensis

California killifish (Fundulus parvipinnis) infected with the brain-encysting trematode Euhaplorchis californiensis display conspicuous swimming behaviours rendering them more susceptible to predation by avian final hosts. Heavily infected killifish grow and reproduce normally, despite having thousands of cysts inside their braincases. This suggests that E. californiensis affects only specific locomotory behaviours. We hypothesised that changes in the serotonin and dopamine metabolism, essential for controlling locomotion and arousal may underlie this behaviour modification. We employed micropunch dissection and HPLC to analyse monoamine and monoamine metabolite concentrations in the brain regions of uninfected and experimentally infected fish. The parasites exerted density-dependent changes in monoaminergic activity distinct from those exhibited by fish subjected to stress. Specifically, E. californiensis inhibited a normally occurring, stress-induced elevation of serotonergic metabolism in the raphae nuclei. This effect was particularly evident in the experimentally infected fish, whose low-density infections were concentrated on the brainstem. Furthermore, high E. californiensis density was associated with increased dopaminergic activity in the hypothalamus and decreased serotonergic activity in the hippocampus. In conclusion, the altered monoaminergic metabolism may explain behavioural differences leading to increased predation of the infected killifish by their final host predators

Multiple alleles encoding a virus-like particle protein in the ichneumonid endoparasitoid Venturia canescens

Hymenopteran endoparasitoids produce nuclear secretions from ovarian glands, which are deposited into the host insect together with the egg, protecting the developing parasitoid against the host's defence reactions. In the ichneumonid Venturia canescens, virus-like particles (VLPs), are attached to the egg surface and provide passive protection against encapsulation by the host. One of the four major particle proteins (p40) is expressed not only in the calyx gland but also in tissues that are not involved in particle production. The p40 coding DNA from V. canescens was cloned and sequenced. Within the coding DNA a tandem repeat sequence, coding for a putative proteolytic cleavage site of the PEST type, is rearranged in a significant portion of the wasp population. A corresponding polymorphism was also detected in the protein. The amino-terminal region of the deduced protein contains a putative type II transmembrane domain. The carboxy-terminal region shows similarity to the phospholipid hydroxyperoxide glutathione peroxidase (PHGPX) of vertebrates. A peroxidase function of the p40, although not ruled out, is unlikely due to the absence of a reactive centre which is typical for many vertebrate peroxidases. The overall conservation of the hydropathic region is discussed in the context of the formation of the viral envelope and its possible function in the immune protection

Proteome changes in the plasma of Pieris rapae parasitized by the endoparasitoid wasp Pteromalus puparum *

Parasitism by the endoparasitoid wasp Pteromalus puparum causes alterations in the plasma proteins of Pieris rapae. Analysis of plasma proteins using a proteomic approach showed that seven proteins were differentially expressed in the host pupae after 24-h parasitism. They were masquerade-like serine proteinase homolog (MSPH), enolase (Eno), bilin-binding protein (BBP), imaginal disc growth factor (IDGF), ornithine decarboxylase (ODC), cellular retinoic acid binding protein (CRABP), and one unknown function protein. The full length cDNA sequences of MSPH, Eno, and BBP were successfully cloned using rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR). Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis indicated that the transcript levels of MSPH and BBP in the fat bodies of host pupae were inducible in response to the parasitism and their variations were consistent with translational changes of these genes after parasitism, while the transcript levels of Eno and IDGF were not affected by parasitism. This study will contribute to the better understanding of the molecular bases of parasitoid-induced host alterations associated with innate immune responses, detoxification, and energy metabolism