Subtle effect of Xenos vesparum (Xenidae, Strepsiptera) on the reproductive apparatus of its male host: Parasite or parasitoid?

Parasitic castration is an adaptive strategy where parasites usurp the hosts' reproductive physiology to complete their life cycle. The alterations in the host traits vary in their magnitude, from subtle changes in the host morpho-physiology and behaviour to the production of complex aberrant phenotypes, which often depend on the host gender. The strepsipteran macroparasite Xenos vesparum induces dramatic behavioural and physiological changes in its female host, the paper wasp Polistes dominula, while its effect on the male phenotype is largely unknown. In this study we investigated how a single X. vesparum parasite influences the functional morphology of P. dominula male reproductive apparatus. We performed morphometry and ultrastructure characterization of corpora allata, testes, seminal vesicles and accessory glands in parasitized and unparasitized males, and also in young and old males to control for the effect of age on the natural deterioration of these organs. Our results show that age significantly affects the development of male reproductive apparatus. A low parasite load - one parasite per host is the common prevalence in the field - has only a marginal impact on the reproductive morphology of P. dominula males, affecting quantitatively but not qualitatively the protein content of male accessory glands. Thus, in male P. dominula wasps, X. vesparum appears to behave as a true "parasite", in clear opposition to the role of "parasitoid" that it takes in female hosts where castration causes the reproductive death.

Sequences of two cDNA clones from the medfly Ceratitis capitata encoding antibacterial peptides of the cecropin family.

Using a back translated oligodeoxyribonucleotide probe, encoding a conserved motif in insect antibacterial peptides, we have isolated two cDNA clones from the medfly, Ceratitis capitata. Sequence determination shows that the cDNAs encode two closely related peptides which are members of the cecropin family.

Purification and primary structure of ceratotoxin A and B, two antibacterial peptides from the female reproductive accessory glands of the medfly Ceratitis capitata (Insecta:Diptera).

In the present article we report the purification and the amino acid sequence of two antibacterial peptides present in the secretion of the female reproductive accessory glands of the dipteran insect Ceratitis capitata. Both peptides consist of 29 amino acid residues, are heat stable, strongly basic and differ from each other for the substitution of two amino acids. Their primary sequence and predicted secondary structure are related to other families of peptides known to have lytic and/or antibacterial activity. We propose the name ceratotoxins (from Ceratitis) for these antibacterial peptides.

The genes encoding the antibacterial sex-specific peptides ceratotoxins are clustered in the genome of the medfly Ceratitis capitata.

Ceratotoxins are antibacterial peptides produced in the female reproductive accessory glands of the medfly Ceratitis capitata. Their expression is not affected by bacterial infection, but is enhanced after mating and is modulated by juvenile hormone. Three different peptides, named ceratotoxins A, B and C, have been previously purified from the female accessory gland secretion and their amino acid and cDNA sequences have been determined. We report here the complete nucleotide sequences of four genes encoding closely related ceratotoxin peptides. One of them encodes a novel peptide, which we named ceratotoxin D. Restriction and nucleotide sequence analysis indicate that these ceratotoxin genes are organized in a large cluster spanning more than 26 kilobases of DNA. All ceratotoxin genes are coordinately expressed. Ceratotoxin transcripts appear in 2-3 day old adult females, and they reach a maximum in 6-7 day old females. The presence of highly conserved motifs in the upstream regions of all the sequenced ceratotoxin genes suggests the presence of common regulatory elements for all ceratotoxins.

Abnormal centrosomes in cold-treated Drosophila embryos.

In this study we examine the effect on the centrosomes of cold treatment of early Drosophila embryos. Prolonged cold treatment during the mitotic divisions which lead to the formation of the blastoderm causes arrest at metaphase of the nuclear divisions. When examined with immunofluorescence microscopy the mitotic spindles show marked pole splitting with the formation of supernumerary and irregularly sized centers, all able to nucleate microtubules. In embryos recovered for longer periods the additional organizing centers become ring-shaped and lose their nucleating properties. Cold treatment of embryos during the cellularization of the blastoderm results in marked fragmentation of the centrosomes, but nucleating capacity is preserved. Sometimes the centrioles come away from the pericentriolar material and their structure is seen to be modified.

The novel antibacterial peptide ceratotoxin A alters permeability of the inner and outer membrane of Escherichia coli K-12.

Ceratotoxins are antibacterial 3-kDa amphiphilic peptides isolated from the female reproductive apparatus of the medfly Ceratitis capitata. The antibacterial activity of a chemically synthesized ceratotoxin A (ctx A) has been investigated. Ctx A was mainly active against Gram-negative organisms, and it had a lytic effect on nongrowing Escherichia coli K-12. Data showed that ctx A alters both the outer and the inner membrane of E.coli K-12 cells.

Ultrastructure of the male reproductive accessory glands in the medfly Ceratitis capitata (Diptera: Tephritidae) and preliminary characterization of their secretions.

The morphology and the ultrastructure of the male accessory glands and ejaculatory duct of Ceratitis capitata were investigated. There are two types of glands in the reproductive apparatus. The first is a pair of long, mesoderm-derived tubules with binucleate, microvillate secretory cells, which contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The narrow lumen of the gland is filled with dense or sometimes granulated secretion, containing lipids. The second type consists of short ectoderm-derived glands, finger-like or claviform shaped. Despite the different shape of these glands, after a cycle of maturation, their epithelial cells share a large subcuticular cavity filled with electron-transparent secretion. The ejaculatory duct, lined by cuticle, has epithelial cells with a limited involvement in secretory activity. Electrophoretic analysis of accessory gland secretion reveals different protein profiles for long tubular and short glands with bands of 16 and 10kDa in both types of glands. We demonstrate that a large amount of accessory gland secretion is depleted from the glands after 30min of copulation.

Presence of antibacterial peptides on the laid egg chorion of the medfly Ceratitis capitata.

Female reproductive accessory glands of the medfly Ceratitis capitata produce a secretion with antibacterial activity mainly ascribed to ceratotoxin peptides. To study whether the secretion from the accessory glands of the female protects the eggs and early larva from microbes, we examined whether ceratotoxins and other accessory gland components could be found on the egg surface. This was found to be the case; a water-soluble material with the same protein and antibacterial pattern as that of the accessory gland secretion was recovered from the laid egg surface and was observed as electrondense, clustered droplets over the outer exochorion. Such material showed the same electrophoretic pattern in both mated and virgin females. These findings indicate that the accessory gland secretion is spread, at oviposition, onto the eggs producing an antibacterial coating, irrespective of fertilization. This is the first report of antimicrobial components recovered from a material layered on insect laid eggs.

FST, a female-specific transcript from the medfly Ceratitis capitata (Diptera: Tephritidae).

We report here the sequence of a novel cDNA clone (FST, female-specific transcript), isolated by differential screening during a search for sexually mature accessory gland-specific transcripts from the medfly Ceratitis capitata. It contains an open reading frame (ORF) with a potential translational start site encoding a putative precursor peptide of 100 amino acids. The FST gene is expressed only in the female reproductive accessory glands. Like the accessory gland-specific antibacterial peptides ceratotoxins, its expression reaches the maximum level when sexual maturity is achieved. However, in contrast to ceratotoxins, it is expressed at a basal level in newly emerged females, and its expression does not increase after mating.

Structural organization of the copulation site in the medfly Ceratitis capitata (Diptera: Tephritidae) and observations on sperm transfer and storage.

The copulation site of the medfly Ceratitis capitata was investigated at anatomical and ultrastructural levels. It consists of the anterior vagina, with a ventral fertilization chamber and a dorsal insemination pocket into which the two spermathecal ducts open. The fertilization chamber is an organ comprised of a number of alveoli that in virgin females are filled with a filamentous secretion, whereas in mated females contain sperm bundles. Through study of the internal morphology of the aedeagus, its position in the anterior vagina, and the direct observation of sperm transfer and storage, we confirmed that sperm are ejaculated through two gonopores at the top of the distiphallus and another at the base of the genital rod. The sperm flow dorsally into the insemination pocket and ventrally into the fertilization chamber. During copulation, the two spermathecae and the fertilization chamber are progressively filled with spermatozoa.

Ceratotoxins: female-specific X-linked genes from the medfly, Ceratitis capitata.

In this paper, we report the chromosomal localization of ceratotoxins, a gene family encoding antibacterial female-specific peptides from the mediterranean fruit fly Ceratitis capitata. The analysis of both polytene and mitotic chromosomes by in situ hybridization shows that ceratotoxins are the first case of female-specific X-linked genes from the medfly C. capitata. Southern blot analysis reveals that the ceratotoxin gene family is not specifically amplified in the female reproductive accessory glands of C. capitata.

cDNA sequence and expression of the ceratotoxin gene encoding an antibacterial sex-specific peptide from the medfly Ceratitis capitata (diptera).

Ceratotoxins are antibacterial 3-kDa molecular mass amphiphilic peptides isolated from the female reproductive accessory glands of the medfly Ceratitis capitata. They are physiologically related to bee melittin and show amino acid sequence homology with magainin peptides. In this paper, we report the complete sequence of cDNA coding for ceratotoxin A and the expression of the gene during the life cycle of the insect. Experimental data show that the ceratotoxin is a gene expressed exclusively in the imaginal stages and that it is female-specific, related to sexual maturity, and stimulated by mating. Differently from most antibacterial insect hemolymph peptides, it is not induced by microbial infection. Western blot analysis using an anti-ceratotoxin antibody indicates the female accessory glands as the only site where the production of the ceratotoxin peptide occurs.

The ceratotoxin gene family in the medfly Ceratitis capitata and the Natal fruit fly Ceratitis rosa (Diptera: Tephritidae).

Ceratotoxins (Ctxs) are a family of antibacterial sex-specific peptides expressed in the female reproductive accessory glands of the Mediterranean fruit fly Ceratitis capitata. As a first step in the study of molecular evolution of Ctx genes in Ceratitis, partial genomic sequences encoding four distinct Ctx precursors have been determined. In addition, anti-Escherichia coli activity very similar to that of the accessory gland secretion from C. capitata was found in the accessory gland secretion from Ceratitis (Pterandrus) rosa. SDS-PAGE analysis of the female reproductive accessory glands from C. rosa showed a band with a molecular mass (3 kDa) compatible with that of Ctx peptides, also slightly reacting with an anti-Ctx serum. Four nucleotide sequences encoding Ctx-like precursors in C. rosa were determined. Sequence and phylogenetic analyses show that Ctxs from C. rosa fall into different groups as C. capitata Ctxs. Our results suggest that the evolution of the ceratotoxin gene family might be viewed as a combination of duplication events that occurred prior to and following the split between C. capitata and C. rosa. Genomic hybridization demonstrated the presence of multiple Ctx-like sequences in C. rosa, but low-stringency Southern blot analyses failed to recover members of this gene family in other tephritid flies.

A mammalian-like lipase gene is expressed in the female reproductive accessory glands of the sand fly Phlebotomus papatasi (Diptera, Psychodidae).

A lipase-like protein (PhpaLIP) was identified as the major protein component in the secretion of the female reproductive accessory glands of the sand fly Phlebotomus papatasi. The full-length cDNA encoding this protein was isolated and its nucleotide sequence determined. The deduced translational product of the gene contains a GFSFG motif, consistent with a GXSXG consensus, which is shared by most bacterial and eukaryotic hydrolases. Transcriptional analysis of the PhpaLIP gene showed that its expression is female-specific, and is also detectable in districts other than accessory glands, suggesting that it might play different functions. Taken together with the observation of sequence similarity shared by PhpaLIP and mammalian lipases, the demonstration of the presence of lipase activity in the accessory gland secretion suggests a possible biological role of PhpaLIP gene product.

Juvenile hormone regulates the expression of the gene encoding ceratotoxin a, an antibacterial peptide from the female reproductive accessory glands of the medfly Ceratitis capitata.

Ceratotoxin A is an antibacterial peptide produced by the reproductive female accessory glands of the medfly Ceratitis capitata. To investigate whether ceratotoxin A gene expression was affected by juvenile hormone, which has gonadotropic functions in adult insects, newly emerged female medflies were treated with precocene II, an antiallotropin compound capable of inhibiting juvenile hormone biosynthesis. Daily treatment of newly emerged flies with precocene II blocked ceratotoxin A gene expression in a dose-dependent manner. Ceratotoxin A gene expression could be recovered after withdrawl of precocene II treatment. Moreover, the effect of precocene II on ceratotoxin A gene expression could be countered by simultaneous treatment with methoprene, a juvenile hormone analogue. The effects of precocene II and methoprene treatments on the growth of both ovaries and accessory glands was also investigated. Our data suggest that ceratotoxin A gene expression is modulated by juvenile hormone.

CD and NMR structural characterization of ceratotoxins, natural peptides with antimicrobial activity.

Antibacterial properties of the secretion from the female reproductive accessory glands of medfly Ceratitis capitata are mostly ascribed to the presence of two peptides, ceratotoxin A and B, which exhibit a strong activity against gram-positive and gram-negative bacterial strains, and show sequence and function homology with cecropins, melittin, and magainins. CD experiments performed in different solvents indicate the presence of a significant content of helical structures in organic solvent. Two-dimensional nmr results for ceratotoxin A in methanol show a helical behavior for the 8-25 region of the peptide. A ramachandran classification of each residue for the structures obtained from distance geometry calculations lead to the definition of four structural families in which the central segment 10-19 is always helical and differences refer to residues 8-9 and 19-23. A sequence analysis of the two ceratotoxins and a systematic search on the protein data bank revealed the occurrence of a KX-hydrophobic-hydrophobic-P motif that seems to be important for helix stabilization.

Molecular characterization of ceratotoxin C, a novel antibacterial female-specific peptide of the ceratotoxin family from the medfly Ceratitis capitata.

Ceratotoxins A and B are antibacterial peptides produced by the sexually mature females of Ceratitis capitata. The gene expression is restricted to the female reproductive accessory glands, and is not affected by bacterial infection, but is enhanced by mating. We report here the purification and the amino acid sequence of ceratotoxin C, a novel member of the ceratotoxin family, the cloning of its cDNA and the analysis of its expression. Ceratotoxin C is coordinately expressed with the other members of the ceratotoxin family. Its antibacterial activity is directed against both Gram-negative and Gram-positive bacterial strains but it is lower than that of ceratotoxin A. We demonstrate in the genome of C. capitata the presence of at least three ceratotoxin genes which express, in the female accessory glands, a set of peptides presumably involved in the protection of the genital tract during fertilization.