The ultrastructure of the spermatheca of Mordellistena brevicauda (Coleoptera, Tenebrionoidea) and the associated bacterial cells

The ultrastructural study on the female reproductive system of the beetle M. brevicauda (Mordellidae) confirmed the positive correlation between the length of the sperm and the size of the female seminal receptacle (Spermatheca). The spermatheca of the species is characterized by an apical bulb-like structure where the spermathecal duct forms numerous folds filled with sperm. At this level many bacterial cells are present intermingled with the duct folds. Some are organized in large structures, such as bacteriomes, while other are single bacteriocytes. The latter are often found near the basal lamina of duct epithelium. In addition, some bacteria are visible in the cytoplasm of the duct epithelial cells. Interestingly, bacterial cells have never been observed in the duct lumen. The possible function of the bacterial cells is discussed

The sperm structure of the Scraptiidae (Coleoptera; Tenebrionoidea)

The sperm ultrastructure of two members of the Scraptiidae Anaspis pulicaria and A. lurida was studied. The results confirm the general organization of the sperm in the superfamily Tenebrionoidea. The sperm bundles at the end of the spermiogenesis show the same peculiar antiparallel distribution at the two opposite poles of the germ cyst, observed in other Tenebrionoidea. The sperm have a bi-layered acrosome, a long cylindrical nucleus with two infoldings at its basal region, two elliptical equal mitochondrial derivatives and two triangular accessory bodies. The flagellar axoneme has the common 9 + 9 + 2 microtubular pattern that at the tail end results disorganized. All these sperm characteristics are quite similar to those found in Pythidae, a closely related family, according to molecular data

Fine structure of the female genital system of diving beetle Stictonectes optatus (Seidlitz, 1887) (Dytiscidae-Hydroporinae) and evidence of mating plug formation

The general organization of the female genital system of the diving beetle Stictonectes optatus was studied, clarifying the complex structure of the spermatheca and spermathecal gland. The two structures adhere closely to each other, sharing a small area of their cuticular epithelium. A long duct connects the bursa copulatrix to the spermatheca, where the sperm are stored. The sperm reach the common oviduct, where egg fertilization occurs, via a fertilization duct. The spermathecal gland cells have extracellular cisterns where secretions are stored. Thin ducts composed of duct-forming cells transport these secre-tions to the apical gland region and into the spermathecal lumen. Soon after mating, the bursa copulatrix is almost completely occupied by a plug secreted by the male accessory glands. The secretions of the bursa epithelium seem to contribute to plug formation. Later this plug becomes large and spherical, obstructing the bursa copulatrix. (c) 2023 Elsevier Ltd. All rights reserved

Sperm structure of the diving beetle Deronectes moestus incospectus (Leprieur, 1876) (Hydroporinae, Dytiscidae) and considerations on extracellular material surrounding sperm bundles

The sperm cells of the diving beetle Deronectes moestus incospectus are characterized by sperm conjugation leading to the formation of sperm bundles of 64 units each. These bundles are formed at the end of spermatocyte cell divisions occurring in the testes and can be detected in the anterior region of the deferent ducts (first type of sperm conjugation). Fusions of some sperm bundles can occur at the end of the deferent ducts. The sperm bundles show sperm-head stacks (sperm rouleaux) and are surrounded by a cup of extracellular material secreted by the epithelial cells of the deferent ducts. This material extends posteriorly around the sperm bundle to cover the nuclei and the initial region of the sperm flagella. The cup extracellular material consists of fine tubules, and is no longer visible in sperm bundles at the posterior end of the deferent ducts. The sperm cells of D. moestus incospectus have an axoneme with a 9 + 9 + 2 pattern and unusual mitochondrial derivatives having a matrix showing dense dots and a small crystallized domain. Two thin elongated accessory bodies are located between the mitochondrial derivatives and the axoneme. The extracellular material can have different morphologies in the various families of Adephaga, but all are produced by the epithelium of the deferent ducts. Thus it is reasonable to assume that it has the same function in the different groups

The Sperm Ultrastructure of the Nitidulidae Meligethes flavimanus (Stephens, 1830) and of the Phalacridae Olibrus affinis (Sturm. 1807) (Coleoptera Cucujoidea)

The sperm ultrastructure of two members of Cucujoidea was described. The Nitidulidae Meligethes flavimanus sperm are long cells extending along the cyst cell with a series of helicoidal tracts. Each sperm cell has a bi-layered acrosome, a cylindrical nucleus and two mitochondrial derivatives of unequal sizes, the one on the right side larger than the opposite one. The axoneme has the common 9+9+2 microtubule pattern and is flanked by two accessory bodies. The one on the right side has an extension of electron-dense material (a puff-like body) reaching the smaller mitochondrial derivative. The cytoplasm of the sperm cyst hosts numerous bacteria. The sperm of the Phalacridae Olibrus affinis are very long cells that form numerous foldings throughout the cyst. The sperm cell has a long bi-layered acrosome, a cylindrical nucleus and a conventional 9+9+2 axoneme. As in the previous species, two mitochondrial derivatives of different sizes are present, the one on the right side larger than the second one, only 1/3 of the other. Two accessory bodies are on both sides of the axoneme. That on the right side is very large, triangular shaped, while on the opposite side a small electron-dense dot is present. The study performed on the two species of Cucujoidea confirms a close phylogenetic relationship between this superfamily and those of Chrysomeloidea and Curculionoidea, a finding also supported by molecular data

Helicobacter pylori toxin VacA is transferred to host cells via a novel contact-dependent mechanism.

Summary Helicobacter pylori is the causative agent of peptic ulcer disease. A major virulence factor of H. pylori is VacA, a toxin that causes massive vacuolization of epithelial cell lines in vitro and gastric epithelial erosion in vivo. Although VacA is exported over the outer membrane and is released from the bacteria, a portion of the toxin remains associated with the bacterial surface. We have found surface-associated toxin to be biologically active and spatially organized into distinct toxin-rich domains on the bacterial surface. Upon bacterial contact with host cells, toxin clusters are transferred directly from the bacterial surface to the host cell surface at the bacteria–cell interface, followed by uptake and intoxication. This contact-dependent transfer of VacA represents a cost-efficient route for delivery of VacA and potentially other bacterial effector molecules to target cells

When a parasite breaks all the rules of a colony:morphology and fate of wasps infected by a strepsipteran endoparasite

The macroparasite Xenos vesparum affects both the behaviour and the physical traits of its host, the social wasp Polistes dominulus. Female wasps, if parasitized, do not perform any social tasks and desert the colony to gather at specific sites, where the parasite mates; at the end of summer they form prehibernating clusters joined by healthy future queens to overwinter. Parasitized wasps become highly gregarious. In April, healthy wasps leave the aggregations to found new colonies, while parasitized wasps remain in overwintering groups and release parasites to infect wasp larvae only later in the season. We studied the prolonged gregarious behaviour of parasitized wasps and analysed the morphology of parasitized and healthy wasps in aggregations collected over a 7-year period to determine whether the parasite affects host size, wing symmetry, ovarian development and lipid stores. All parasitized wasps were smaller and had undeveloped ovaries and more wing fluctuating asymmetry than unparasitized wasps, irrespective of time of year, parasite load and parasite sex. If infected only by one or two X. vesparum females, the wasps had large fat bodies, which could facilitate their overwintering. In contrast, wasps infected by at least one male parasite had little lipid and died at the end of the summer. Thus, X. vesparum, may play a role in the fate of its host, by exploiting wasps' tendency to form aggregations outside the colony and by altering its caste system, nutrient allocation, diapause timing and life span to achieve its own reproduction and dispersal. © 2011 The Association for the Study of Animal Behaviour

Ultrastructure of the female reproductive organs of the diving beetle Deronectes moestus incospectus (Leprieur, 1876) (Dytiscidae, Hydroporinae)

: We describe the ultrastructure of the female reproductive organs of Deronectes moestus (Dytiscidae Hydroporinae). The long spermathecal duct has a simple epithelium lined internally by a thin cuticle and externally by a thick layer of muscle cells. The wide duct lumen contains electron-dense material, among which remnants of extracellular material are visible. This material consists of tubular structures assembled around sperm bundles previously described in the male deferent ducts. The so-called gland, disposed along the spermathecal duct, is a structure with epithelial cells lined by an irregular cuticle bearing a rich system of microvilli. Many mitochondria are visible in the apical cytoplasm of the epithelial cells, and a few spheroidal bodies are close to the basal nuclei. Since the epithelial ultrastructure of the gland suggests it is involved in fluid uptake from the lumen rather than secretory activity, the term gland, coined by other authors to describe this organ, is inappropriate. The spermatheca is a large structure with a complex epithelium showing secretory and duct-forming cells. The lumen of this organ contains sperm with the distinctive ultrastructural features of those described in the male deferent ducts, namely having a mitochondrial matrix with a small crystallized area and electron-dense dots. Because to its overall organization, the spermatheca of D. moestus can be considered a more integrated organ than those in previously studied hydroporine species

A Strepsipteran parasite extends the lifespan of workers in a social wasp

Acknowledgements The authors are grateful to Rita Cervo, Stefano Turillazzi and the members of the Florence Group for the Study of Social Wasps for their assistance during this study, both in the field and in the laboratory. The authors would also like to thank two anonymous reviewers for their helpful comments on the manuscript.Peer reviewedPublisher PD