ABSTRACT
Lysophosphatidylcholine (LPC) is a major bioactive lipid that is enzymatically generated by phospholipase A(2) (PLA(2)). Previously, we showed that LPC is present in the saliva of the blood-sucking hemipteran Rhodnius prolixus and modulates cell-signaling pathways involved in vascular biology, which aids blood feeding. Here, we show that the saliva of the predator insect Belostoma anurum contains a large number of lipids with LPC accounting for 25% of the total phospholipids. A PLA(2) enzyme likely to be involved in LPC generation was characterized. The activity of this enzyme is 5-fold higher in Belostoma saliva than in other studied hemipterans, suggesting a close association with the predator feeding habits of this insect. Belostoma employs extra-oral digestion, which allows for ingestion of larger prey than itself, including small vertebrates such as amphibians and fish. Therefore, prey immobilization during digestion is essential, and we show here that Belostoma saliva and B. anurum saliva purified LPC have paralytic activity in zebrafish. This is the first evidence that lysophospholipids might play an important role in prey immobilization, in addition to contributing to blood feeding, and might have been an evolutionary acquisition that occurred long before the appearance of hematophagy in this animal group.
Subject(s)
Heteroptera/metabolism , Heteroptera/pathogenicity , Lysophosphatidylcholines/metabolism , Lysophosphatidylcholines/toxicity , Predatory Behavior/physiology , Animals , Cells, Cultured , Immobilization , In Vitro Techniques , Mice , Neurons/drug effects , Paralysis/chemically induced , Phospholipases A2/metabolism , Phrenic Nerve/drug effects , Rats , Saliva/metabolism , Species Specificity , ZebrafishSubject(s)
Evolution, Molecular , Lysophospholipids/toxicity , Venoms/chemistry , Animals , Fatty Acids/chemistry , Fatty Acids/toxicity , Lysophospholipids/chemistry , Lysophospholipids/physiology , Mice , Phospholipases A2/chemistry , Phospholipases A2/physiology , Phospholipases A2/toxicity , Xenopus laevis , ZebrafishABSTRACT
The neuromuscular system of Drosophila melanogaster has been studied for many years for its relative simplicity and because of the genetic and molecular versatilities. Three main types of striated muscles are present in this dipteran: fibrillar muscles, tubular muscles and supercontractile muscles. The visceral muscles in adult flies and the body wall segmental muscles in embryos and larvae belong to the group of supercontractile muscles. Larval body wall muscles have been the object of detailed studies as a model for neuromuscular junction function but have received much less attention with respect to their mechanical properties and to the control of contraction. In this review we wish to assess available information on the physiology of the Drosophila larval muscular system. Our aim is to establish whether this system has the requisites to be considered a good model in which to perform a functional characterization of Drosophila genes, with a known muscular expression, as well as Drosophila homologs of human genes, the dysfunction of which, is known to be associated with human hereditary muscle pathologies.
