Isolation, partial characterization, and localization of the A and B proteins from the tubular accessory gland of male Tenebrio molitor

Transfer and fate of seminal fluid molecules in the beetle, Diaprepes abbreviatus: implications for the reproductive biology of a pest species

Molecules transferred from males to females via seminal fluids are important to the study of insect reproduction because they affect female physiology, reproductive behavior, and longevity. These molecules (seminal fluid molecules or SFMs) interest applied entomologists because of their potential use in insect control. SFMs are also interesting because of their relatively rapid evolution and important role in post-mating sexual selection. We studied SFMs in Diaprepes abbreviatus, a major pest of numerous plant species of economic importance. Using radiolabeled-methionine (35S), we found that D. abbreviatus males synthesized proteins de novo in their reproductive tissues after mating. Males that were fed radiolabeled methionine transferred radioactivity to females beginning within the first 10 min of mating. Male-derived substances are absorbed from the female's reproductive tract into the hemolymph and circulated throughout the body, but are found primarily in the eggs and ovaries. As a result, SFMs may be a useful means of both horizontal (to mates) and vertical transfer (to offspring) of control agents between conspecifics.

Male-predominant carboxylesterase expression in the reproductive system of molluscs and insects: immunochemical and biochemical similarity between Mytilus male associated polypeptide (MAP) and Drosophila sex-specific esterase S

We suggested that sexual differentiation of the reproductive system in gonochoric species of invertebrates can be characterized by common molecular mechanisms in spite of high morphological divergences of reproductive tract organs in different animal groups. The present study focused on this problem and report our observations on biochemical characteristics of male-associated polypeptide (MAP) identified in the gonad tissue of bivalve molluscs, Mytilus galloprovincialis, in comparison to those of male-specific carboxylesterase (esterase S) of Drosophila virilis ejaculatory bulbs. We provide evidences for the immunochemical similarity of Mytilus MAP and Drosophila esterase S. We also show that MAP is characterized by esterase activity toward both, alpha- and beta-naphthyl acetates. Using immunofluorescence, we found MAP in the gonad (mantle) connective tissue, membranes of follicles and around gonad ducts but not in sperm cells. Nevertheless, the levels of MAP expression depend on presence or absence of ripe spermatozoa in the gonad follicles. In mature gonads before spawning, MAP is expressed at high level, while in the spent gonads only traces of this polypeptide could be detected. Using Western immunoblot, MAP was not observed in spermatozoa obtained by biopsy of gonad follicles. In contrast, we found this protein in spawned sperm cells. Thus, we suggest that spawning may be required to establish the trafficking mechanisms that control whether MAP is retained or excreted by the gonad. Taken together, the results indicate that MAP of M. galloprovincialis is structurally and functionally related to esterase S of D. virilis ejaculatory bulbs.

Structure of a D-protein gene and amino-acid sequences of the highly repetitive D-proteins secreted by the accessory glands of the mealworm beetle

The D-group proteins form the major component of the proteinaceous secretion of the tubular accessory glands of the yellow mealworm beetle, Tenebrio molitor. In a previous paper, we reported the sequence of two D-protein cDNAs and their inferred translation products. Both proteins contain three highly repetitive domains (A, A' and B). In this paper, we present the cDNA-inferred sequences of 8 more D-proteins, none of which contains an A' domain. We also present the structure of a D-protein gene. Southern analysis suggests that genes coding for an A' domain are relatively rare. Genes with a total of 7 or 8 (A + B domain) repeats seem most common.

The B proteins secreted by the tubular accessory sex glands of the male mealworm beetle, Tenebrio molitor, have sequence similarity to moth pheromone-binding proteins

B proteins represent one of the four major protein groups secreted by the tubular accessory glands of adult, male mealworm beetles. They are acidic proteins with an apparent molecular mass of 18.8 kDa. In this paper we present the deduced amino-acid sequences of two, almost identical B proteins, termed B1 and B2. The mature proteins are 118 amino acids long. They contain 11 (B2) or 12 (B1) possible phosphorylation sites and are rich in glutamic acid (16%). Lectin binding experiments indicate the presence of asparagine linked carbohydrate. The secondary structure of the B proteins is predicted to be almost completely alpha-helical. The B proteins show significant sequence resemblance to a group of pheromone- and odorant-binding proteins in moths and Drosophila, suggesting a role as carrier proteins for lipids.

cDNA-inferred amino-acid sequence of a C protein, a heparin-binding, basic secretion product of the tubular accessory sex glands of the mealworm beetle, Tenebrio molitor

C proteins represent one of the four major protein groups secreted by the tubular accessory glands of male mealworm beetles (Tenebrio molitor). They are basic proteins with an apparent molecular mass of 21.9 kDa. In this paper we present the deduced amino-acid sequence of two, almost identical C proteins, termed C1 and C2. The C proteins contain a consensus sequence for a heparin-binding site, and they are efficiently purified from accessory gland homogenates by heparin-affinity chromatography. No sequence resemblance was found with other proteins in the databases, but their high avidity for heparin suggests a possible involvement of the C proteins in sperm capacitation.