Interkingdom competition occurs between hymenopteran parasitoids and insect viruses sharing the same insect hosts. It has been assumed that parasitoid larvae die with the death of the infected host or as result of competition for host resources. Here we describe a gene family, parasitoid killing factor (pkf), that encodes proteins toxic to parasitoids of the Microgastrinae group and determines parasitism success. Pkfs are found in several entomopathogenic DNA virus families and in some lepidopteran genomes. We provide evidence of equivalent and specific toxicity against endoparasites for PKFs found in entomopoxvirus, ascovirus, baculovirus, and Lepidoptera through a mechanism that elicits apoptosis in the cells of susceptible parasitoids. This highlights the evolutionary arms race between parasitoids, viruses, and their insect hosts.
(1R,6R)-2-Succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) synthase, also called MenD, participates in the menaquinone (vitamin K 2 ) biosynthetic pathway. The enzyme is a part of the superfamily of ThDP-dependent enzymes; however, it is the only enzyme known to catalyze a Stetter-like 1,4-addition of a ThDP adduct to the -carbon of an unsaturated carboxylate. This is the first reported crystallization of the apoenzyme and holoenzyme forms of MenD. The apoenzyme crystals were obtained by sitting-drop vapour diffusion with 70% MPD. However, the crystals were too small to collect diffraction data and a search for better conditions was not successful. Single crystals of the holoenzyme with ThDP and Mn 2+ as cofactors were obtained by the hangingdrop vapour-diffusion method with 35% ethylene glycol as precipitant. Diffraction data were collected on a cryocooled crystal to a resolution of 2.0 Å at BioCARS, Advanced Photon Source (APS), Chicago, IL, USA. The crystal was found to belong to space group P2 1 2 1 2 1 , with unit-cell parameters a = 106.86, b = 143.06, c = 156.85 Å , = = = 90 .
The structure of the PA1607 protein from Pseudomonas aureginosa was determined at 1.85 Å resolution using the Se-Met multiwavelength anomalous diffraction (MAD) technique. PA1607 forms a dimer and adopts a winged-helix motif similar to the MarR family of transcription regulators, though it has an unusual dimerization profile. The DNA-binding regions and a putative metal-binding site are not conserved in PA1607.
Cutworms (Lepidoptera: Noctuidae) constitute an important insect pest complex that causes damage to a variety of crops across western Canada and particularly in canola (Brassica napusLinnaeus; Brassicaceae) crops in recent years. However, individual cutworms are very difficult to identify to species based on morphology alone, particularly at the larval stage. Problems with pest identification can lead to difficulties in recommending appropriate management strategies for specific cutworm infestations. In the current study we have developed and applied a single-step multiplex polymerase chain reaction assay, based on the rRNA ITS2 genomic sequence, which can be used to identify, to the species level, individuals of the following five key cutworm species:Agrotis orthogoniaMorrison,Euxoa auxiliaris(Grote),Euxoa ochrogaster(Guenée),Feltia jaculifera(Guenée), andLacinipolia renigera(Stephens). This molecular identification tool will be a valuable asset in agronomic and ecological studies of cutworm infestations in the canola cropping system across western Canada and potentially could be used as a timely identification tool for determining pest infestations to the species level during outbreaks.
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