First Biosynthetic pathway of 1-hepten-3-one in Iporangaia pustulosa (Opiliones)

Abstract

Arthropods produce a great variety of natural compounds, many of which have unexplored biosynthesis. Among the armored harvestmen (Arachnida: Opiliones) of the suborder Laniatores, the defensive gland exudates contain vinyl ketones and other constituents of supposed polyketide origin. We have studied the biosynthesis of 1-hepten-3-one in the Neotropical harvestman Iporangaia pustulosa by feeding individuals with 13C-labeled precursors, demonstrating its mixed acetate/propionate origin. 13C NMR spectroscopy showed an unusual labeling pattern suggesting different propionate sources for starting and extender units. Our analysis also indicates the presence of methylmalonyl-CoA mutase, converting acetate into propionyl-CoA via succinyl-CoA, together with other C3 unit routes. This is the first biosynthetic study of alkyl vinyl ketones in arthropods. Our results shed light on the origin and diversification of chemical compounds in a major arthropod group.

Millipedes vs. pathogens: Defensive secretions of some julids (Diplopoda: Julida) as potential antimicrobial agents

“…The biosynthesis of ketones has not yet been studied in millipedes; however, it has been recently shown in another arthropod model system, namely the harvestman Iporangia pustulosa Mello‐Leitao, 1935, that 1‐hepten‐3‐one is derived from a pathway using acetate and propionate as precursors (Rocha, Wouters, Machado, & Marsaioli, ). This suggests that both classes of compounds (alkyl derivatives of p ‐benzoquinone and ketones) may have similar biosynthetic pathways and can be found as concomitants in millipedes that rely on p ‐benzoquinone‐based defensive secretions.…”

Chemosystematics in the Opiliones (Arachnida): a comment on the evolutionary history of alkylphenols and benzoquinones in the scent gland secretions of Laniatores

“…Their results implied benzoquinones to be the ancestral state in gonyleptid secretions, vinyl ketones to be a synapomorphy of gonyleptids of clade “K92,” and alkylphenols to have evolved five times independently in the Gonyleptidae. Several authors have acted on the proposal of a multiple independent evolution of alkylphenols from the ancestral state of benzoquinones and cited this particular situation as given (Rocha et al., ,b; Wouters et al., ). We consider this proposed evolutionary scenario as rather problematic, and show that a few (in our opinion necessary) changes in the original data set of Caetano and Machado as well as in the evaluation method lead to completely different results.…”

Species differences and geographic variation in the communal roosting behavior ofPrionostemmaharvestmen in Central American rainforests

“…Harvestmen have been shown to have spatial associative learning ability (dos Santos et al 2013) and may avoid sites where they have previously been disturbed. Another possible explanation is that captured harvestmen release defensive chemicals (Machado 2002;Machado et al 2002;Eisner 2004;Rocha et al 2013) that persist at the site of disturbance and make it less attractive for roosting. In any case, the decreasing return rate over time (Table 1) suggests that these harvestmen would rapidly abandon a site where they were disturbed repeatedly.…”