A novel fatty acid binding protein produced by teratocytes of the aphid parasitoid Aphidius ervi

Abstract

Aphidius ervi is an endophagous braconid, parasitoid of the pea aphid, Acyrthosiphon pisum. A. ervi teratocytes, deriving from the dissociation of the embryonic serosa, synthesize and release two major proteins into the host haemocoel. The gene of one of these proteins has been cloned and characterized. This gene codes for a 15.8 kDa protein belonging to the fatty acid binding protein (FABP) family, named Ae-FABP (A. ervi-FABP). It is abundantly present in the host haemolymph when the parasitoid larva attains its maximum growth rate. The recombinant Ae-FABP binds to fatty acids in vitro, showing a high affinity to C14-C18 saturated fatty acids and to oleic and arachidonic acid. The possible nutritional role for the parasitoid larva of Ae-FABP is discussed.

Proteomes of the aphid Macrosiphum euphorbiae in its resistance and susceptibility responses to differently compatible parasitoids

“…This parasitoid is well adapted to various aphid hosts, especially the pea aphid (Acyrthosiphon pisum), the immune responses of which it usually can avoid or fight, despite strong host resistance also being known. Research has shown that the wasp venom of A. ervi, and secretions from its serosa-derived teratocytes, contain factors of A. ervi virulence, which modulate host physiology and suitability Digilio et al, Vinson et al, 2001;Falabella et al, 2000Falabella et al, , 2005. Wasp venom causes degeneration of the early embryos of the viviparous host aphid, thus redirecting host nutritional resources to the parasitoid.…”

“…These include activation of proteolytic cascades leading to localized melanization and coagulation (Cerenius and Sö derhä ll, 2004;Park et al, 2005), and hemocytic encapsulation, which is a well-known multicellular defence of insect hosts to parasitoids (Godfray, 1994;Quicke, 1997;Jiravanichpaisal et al, 2006). On the other side, to establish a permissive environment for successful parasitism, well-adapted parasitoids release factors to suppress host immunity, and to alter or even control host physiology and development (Digilio et al, 2000;Falabella et al, 2000Falabella et al, , 2003Falabella et al, , 2005Pennacchio and Strand, 2006;Zhang et al, 2006). These strategies include venom proteins (Digilio et al, 2000) and, for many parasitoids, symbiotic polyDNA viruses (Kroemer and Webb, 2004;Dupuy et al, 2006) injected by female wasps at oviposition, or factors that are secreted in the host by parasitoid embryo-derived free cells, known as teratocytes (Falabella et al, 2000(Falabella et al, , 2005.…”

“…On the other side, to establish a permissive environment for successful parasitism, well-adapted parasitoids release factors to suppress host immunity, and to alter or even control host physiology and development (Digilio et al, 2000;Falabella et al, 2000Falabella et al, , 2003Falabella et al, , 2005Pennacchio and Strand, 2006;Zhang et al, 2006). These strategies include venom proteins (Digilio et al, 2000) and, for many parasitoids, symbiotic polyDNA viruses (Kroemer and Webb, 2004;Dupuy et al, 2006) injected by female wasps at oviposition, or factors that are secreted in the host by parasitoid embryo-derived free cells, known as teratocytes (Falabella et al, 2000(Falabella et al, , 2005. Research on insect host-parasitoid interactions has most frequently focused on hosts such as caterpillars (Lepidoptera) Li et al, 2003;Cô nsoli et al, 2005;Lu et al, 2006) and Drosophila larvae (Diptera) (Sisterson and Averill, 2004;Prevost et al, 2005;Dubuffet et al, 2006).…”

Parasitic wasp responses to symbiont-based defense in aphids

“…Also, fast-growing polyploid cells called teratocytes dissociate from the serosal membrane surrounding the wasp embryo and circulate within the aphid hemocoel during larval development [29]. In A. ervi , teratocytes are known to synthesize and release two proteins that are likely involved in redirecting host resources from aphids to developing wasps: a fatty acid binding protein ( Ae -FABP), and an extracellular enolase ( Ae -ENO), which may degrade aphid tissue [30,31]. If an A. ervi female oviposited twice in a single host, she would then double the quantity of both venom and teratocytes present in the host, potentially increasing the likelihood of successful parasitism in symbiont-defended hosts.…”

Teratocytes and their functions in parasitoids

“…As such, egg pronuclei are diploid and undergo meiosis, but the resulting egg pronucleus can develop into either a male larva if unfertilized or female larva if fertilized. secretory proteins from teratocytes of Aphidius ervi were identified as a fatty acid binding protein and an enolase [51,52] (Figure 2). No specific gene products have been identified from platygastroids although data do suggest that teratocyte secretory products exhibit protease activity consistent with extraoral digestion of host eggs [17].…”