Parasitic castration by the digenian trematode Allopodocotyle sp. alters gene expression in the brain of the host mollusc Haliotis asinina

Abstract

Infection of molluscs by digenean trematode parasites typically results in the repression of reproduction -the so-called parasitic castration. This is known to occur by altering the expression of a range of host neuropeptide genes. Here we analyse the expression levels of 10 members of POU, Pax, Sox and Hox transcription factor gene families, along with genes encoding FMRFamide, prohormone convertase and b-tubulin, in the brain ganglia of actively reproducing (summer), non-reproducing (winter) and infected Haliotis asinina (a vetigastropod mollusc). A number of the regulatory genes are differentially expressed in parasitised H. asinina, but in only a few cases do expression patterns in infected animals match those occurring in animals where reproduction is normally repressed.

Consumo de oxígeno en Perumytilus purpuratus según el parasitismo por Digenea, y efectos de la temperatura y del ciclo de emersión-inmersión sobre la liberación de cercarias

“…El hecho de que todos los individuos parasitados presentaran escaso o nulo desarrollo gonadal sugiere que el parásito deriva sus demandas del presupuesto reproductivo del hospedador, lo que coincide con diversos autores que señalan que la presencia de digeneos provoca en el huésped la castración total o parcial (Oliva & Díaz 1988, Arakelova et al 2003, Fredensborg et al 2005, Rice et al 2006. En otros sistemas Digenea-Gastropoda, se ha observado que la ausencia de diferencias en la tasa metabólica de hospedadores parasitados y no parasitados ocurre sólo cuando la infección es adquirida en una etapa tardía de la ontogenia de los hospedadores, ya que los individuos que habían adquirido la parasitosis en edades tempranas, mostraban mayor consumo de oxígeno que los no parasitados (Arakelova et al 2003).…”

Phylogenetic studies explain the discrepant host distribution of Allopodocotyle heronensis sp. nov. (Digenea, Opecoelidae) in Great Barrier Reef serranids

“…This represents the first named opecoelid for which an intermediate host is known on the Great Barrier Reef. Rice et al (2006) described patterns of modified gene expression associated with infection of a species of Allopodocotyle in Haliotis asinina at Heron Island, but the study did not distinguish whether it was the present species or a second morphologically indistinguishable species, described by Lucas et al (2005), that is so far known only from its cercaria, also in Haliotis asinina. …”

Chytrid infection reduces thoracic beat and heart rate of Daphnia pulicaria

“…Parasitism increases predation risk as some endoparasitic infections make the organisms more opaque leading to a higher incidence of predation (Bakker et al, 1997;Ebert et al, 2000;Decaestecker et al, 2005;Johnson et al, 2006a;Baldauf et al, 2007). Most studies dealing with zooplankton diseases have focused on changes in survival and reproduction rates (Stirnadel & Ebert, 1997;Ebert et al, 2000;Wolinska et al, 2004;Rice et al, 2006), yet the sublethal repercussions of infection on physiology and metabolism warrant further study.…”