Purification, partial characterization and role in lipid transport to developing oocytes of a novel lipophorin from the cowpea weevil, Callosobruchus maculatus

Abstract

Lipid transport in arthropods is achieved by highly specialized lipoproteins, which resemble those described in vertebrate blood. Here we describe purification and characterization of the lipid-apolipoprotein complex, lipophorin (Lp), from adults and larvae of the cowpea weevil Callosobruchus maculatus. We also describe the Lp-mediated lipid transfer to developing oocytes. Lps were isolated from homogenates of C. maculatus larvae and adults by potassio bromide gradient and characterized with respect to physicochemical properties and lipid content. The weevil Lp (465 kDa) and larval Lp (585 kDa), with hydrated densities of 1.22 and 1.14 g/mL, contained 34 and 56% lipids and 9 and 7% carbohydrates, respectively. In both Lps, mannose was the predominant monosaccharide detected by paper chromatography. SDS-PAGE revealed two apolipoproteins in each Lp with molecular masses of 225 kDa (apolipoprotein-I) and 79 kDa (apolipoprotein-II). The lipids were extracted and analyzed by thinlayer chromatography. The major phospholipids found were phosphatidylserine, phosphatidylcholine and phosphatidylethanolamine in adult Lp, and phosphatidylcholine, phosphatidylethanolamine and sphingomyelin in larval Lp. Hydrocarbons, fatty acids and triacylglycerol were the major neutral lipids found in both Lps. Lps labeled in the protein moiety with radioactive iodine ( 125 I-iodine) or in the lipid moiety with fluorescent lipids revealed direct evidence of endocytic uptake of Lps in live oocytes of C. maculatus.

Lipoprotein mediated lipid uptake in oocytes of polychaetes (Annelida)

“…For the vitellin (the final storage form of vitellogenin in the oocyte) of two polychaetes, a lipid content of 16% and 50% has been reported (Baert et al 1984;Lee et al 2005). On the other hand, the non-sexspecific lipoproteins among the large lipid transfer proteins have also been shown to contribute to egg yolk, at least in crustacean (Lubzens et al 1997;Ravid et al 1999), insect Telfer et al 1991;Ximenes et al 2008), and chicken eggs (Steyrer et al 1990). In oocytes of some vertebrates (i.e., trout, frog, and hen) and in some insects, the incorporation of both yolk and lipoproteins is also evident from the presence of the corresponding receptors (Steyrer et al 1990;Cheon et al 2001 and references cited therein).…”

Two apolipoproteins in salmon louse (Lepeophtheirus salmonis), apolipoprotein 1 knock down reduces reproductive capacity

“…Lipoproteins from adult male (n=50) and female (n=25) lice were purified according to the procedure previously described in [ 22 , 56 , 57 ]. Briefly, male and female animals were homogenized separately in ice cold phosphate buffer saline (PBS; 0.10 M sodium phosphate, pH 7.0, and 0.15 M NaC1) in the presence of protease-inhibitor cocktail (Sigma-Aldrich).…”

The Effect of Temperature and Nutrient on Developmental Biology and Physiology of Stored-Product Species of Coleoptera

“…Thus, they may have higher total lipid percentages than males, although it varies by species. Ximenes et al [104] with radioactive labeling studies, found fatty acids were used in egg production in C. maculatus females, Nwanze et al [94] found females contain more total lipids and triglycerides than males. It was determined that the total fatty acid amount in A. grandis adults was very low in the first four days of adult life and then increased with age [96], while the amount of lipids in the ovaries of T. molitor females increased during the first three days of adult life and then decreased [99].…”