Surface lipidome of the lone star tick, Amblyomma americanum, provides leads on semiochemicals and lipid metabolism

Abstract

Lipids extracted from the surface of the lone star tick, Amblyomma americanum, were analyzed by high resolution mass spectrometry. Prior to lipid extraction, the adult ticks were either unfed or fed on cattle, and the fed ticks were in groups either containing males and females together, or containing only males or females. Cholesteryl esters were found on the surfaces of fed females, and they may provide a more complete description of the composition of the mounting sex pheromone. Dihydrocholesteryl esters were detected on the surfaces of unfed males and females, suggesting a possible role in survival during host-seeking. Dehydrodeoxyecdysone, found on fed females, could be a component of the genital sex pheromone. The most abundant polar surface lipids detected were acylglycerides. High levels of sphingolipids and glycerophospholipids on males fed separately might be derived, in part, from sperm development. A high level of a 20:4 fatty acid, presumably arachidonic acid, was found on the surface of fed females, indicating that it may be a component of the genital sex pheromone. A high level of docosenamide was found on the surface of fed females. Wax esters were found on the surfaces of fed ticks but not on unfed ticks. These esters could be involved in elasticity of the cuticle of engorged females or in wax coating of eggs. N-acylethanolamines were found on the surfaces of male and female ticks fed together, and on male ticks fed separately, but were absent or at low levels on females fed separately and on unfed ticks. This pattern suggests a possible role as a metabolic coordination primer pheromone.

Identification of Alpha-Gal conjugated Lipids in Saliva of Lone-Star Tick (Amblyomma americanum)

“…Based on the observed size, α-gal bound lipids were discovered in tick saliva via NSI-MS, belonging to Gb3 or Isoglobotriosylceramide (iGb3Cer), a group of lipids (see Table 1), potentially consisting of carbon chains of 16, 18, 22, and 24. Previous research, focusing on the profiling of tick lipids following tick feeding, reported that lipids containing carbon chains of 16, 18, 22, and 24 corresponded to palmitic acid, oleic acid or octadecenoic acid, docosahexaenoic acid or DHA, and nervonic or cis-15tetracosenoic acid, respectively (Shipley et al, 1993;Renthal et al, 2019). Indeed, it was noted that Am.…”

“…Among all lipids, oleic acid (18:1) is the most abundant fatty acid throughout tick feeding (Shipley et al, 1993). The research findings from Renthal et al (2019) reveal that salivary glands undergo notable alterations in mass and fatty acid composition linked to phospholipids during feeding. Specifically, the study identifies phosphatidylcholine (PC) and phosphatidylethanolamine (PE) as the primary phospholipids present, while triglycerides (TGs) emerge as the predominant neutral lipids within the glands.…”

“…Investigating how these alpha-gal structures accumulate in tick saliva poses an interesting aspect of future research. Fundamentally, these tick salivary lipids were marked as important in tick physiology, energy, and reproduction (Renthal et al, 2019;Rees et al, 2004). A study focused on the analysis of lipid profiles following tick feeding revealed that the composition and abundance of salivary gland fatty acids change drastically during feeding.…”

Comparative response of Metarhizium brunneum to the cuticles of susceptible and resistant hosts

“…The cuticular surface of ticks is composed of diverse components with varying functions (Renthal et al, 2019). The presence of antifungal compounds, such as fatty acids, in insect, and tick cuticle inhibits fungal growth (Bogus et al, 2010; Keyhani, 2018; Ment et al, 2010; Ment et al, 2013; Ortiz‐Urquiza & Keyhani, 2013).…”