Circulating hemocytes from larvae of the paper wasp Polistes dominulus (Hymenoptera, Vespidae)

Circulating hemocytes from larval stages of the paper wasp Polistes dominulus were characterized by light and transmission electronmicroscopy. Three types were identified: prohemocytes, plasmatocytes and granulocytes. The first two are agranular cells while the latterpresent typical cytoplasmic inclusions called granules. Plasmatocytes differ from prohemocytes being larger, showing lower nucleus/cytoplasmratio and they possess many phagolysosomes. The substantial uniformity of most subcellular features and the presence of \u201cintermediate forms\u201d support the \u201csingle-cell theory\u201d i.e., there is only one cell line that originates from the prohemocyte and leads to the granular cell passing through the plasmatocyte. This hypothesis seems to be confirmed by functional tests. Indeed, most part of cells adheres to the glass and is able to phagocytize fluorescent microspheres

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

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 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

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

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

Isomin: a novel cytoplasmic intermediate filament protein from an arthropod species

<p>Abstract</p> <p>Background</p> <p>The expression of intermediate filaments (IFs) is a hallmark feature of metazoan cells. IFs play a central role in cell organization and function, acting mainly as structural stress-absorbing elements. There is growing evidence to suggest that these cytoskeletal elements are also involved in the integration of signalling networks. According to their fundamental functions, IFs show a widespread phylogenetic expression, from simple diblastic animals up to mammals, and their constituent proteins share the same molecular organization in all species so far analysed. Arthropods represent a major exception in this scenario. Only lamins, the nuclear IF proteins, have so far been identified in the model organisms analysed; on this basis, it has been considered that arthropods do not express cytoplasmic IFs.</p> <p>Results</p> <p>Here, we report the first evidence for the expression of a cytoplasmic IF protein in an arthropod - the basal hexapod <it>Isotomurus maculatus</it>. This new protein, we named it isomin, is a component of the intestinal terminal web and shares with IFs typical biochemical properties, molecular features and reassembly capability. Sequence analysis indicates that isomin is mostly related to the Intermediate Filament protein C (IFC) subfamily of <it>Caenorhabditis elegans </it>IF proteins, which are molecular constituents of the nematode intestinal terminal web. This finding is coherent with, and provides further support to, the most recent phylogenetic views of arthropod ancestry. Interestingly, the coil 1a domain of isomin appears to have been influenced by a substantial molecular drift and only the aminoterminal part of this domain, containing the so-called helix initiation motif, has been conserved.</p> <p>Conclusions</p> <p>Our results set a new basis for the analysis of IF protein evolution during arthropod phylogeny. In the light of this new information, the statement that the arthropod phylum lacks cytoplasmic IFs is no longer tenable.</p> <p>See commentary article: <url>http://www.biomedcentral.com/1741-7007-9-16</url>.</p