The ultrastructure of the peculiar synspermia of some Dysderidae (Araneae, Arachnida)

The present study reports on the ultrastructure features of spermatozoa and spermatogenesis of several species of Dysderidae (Dysdera crocata, Dysdera erythrina, Dysdera ninnii, Harpactea arguta, Harpactea piligera, Dasumia taeniifera). Dysderid spiders are known to possess a peculiar sperm transfer form known as synspermia, characterized by fused spermatozoa surrounded by a secreted sheath. Until now the exact mode of formation of the synspermia is unknown. The present study demonstrates that the spermatids are connected via narrow cell bridges during the entire spermiogenesis as is usual, although in Dysderidae they do not separate at end of the spermiogenesis. Instead, they fuse completely within the testes shortly after the spermatid has coiled to get a spherical shape. The number of fusing sperm cells is different in the different observed species. The species of the genus Harpactea thus have synspermia consisting of two fused spermatozoa; whereas in the species of the genus Dysdera four sperm cells are fused and in D. taeniifera at least three spermatozoa are fused. In contrast with other known families with this peculiar form transfer of sperm, the synspermia in Dysderidae are mainly characterized by a conspicuous vesicular area which extends through the entire synspermium surrounding the cell organelles. Thus, all main cell components (e.g., nucleus, acrosomal vacuole, and axoneme) are covered by the vesicular membrane. The vesicular area seems to be functional and probably it is important during sperm activation in female genital system. Simultaneously to the extension of the vesicular area, the synspermium accumulates large amounts of glycogen. The glycogen is mainly located around the centriolar adjunct and along the axoneme accompanying the postcentriolar elongation of the nucleus. A further peculiar feature is the extremely elongated acrosomal vacuole, which seems to be synapomorphic trait for sperm cells of dysderids. Interestingly, spermatogenesis, including the fusion, exclusively occurs within the testes (in contrast to the formation of coenospermia). In the vas deferens only synspermia were found. The secreted sheath surrounding the spermatozoa is finally synthesized in the parts of the vasa deferentia, which are close to the genital opening where numerous vacuoles and microvilli are seen in the epithelial cells.

On the occurrence of coenospermia in mesothelid spiders (Araneae: Heptathelidae)

Two species of the early derivative spider family Heptathelidae (Heptathela kimurai yanbaruensis and Ryuthela nishihirai nishihirai) have been investigated with respect to spermiogenesis, focussing on late events during which peculiar transfer forms are developed. It is shown, for the first time in detail, that these spiders produce coenospermia. The coenospermia of these species are large aggregates containing more than 20 individual encapsulated spermatozoa. The coenospermia possess a likely flexible envelope formed by a thick multilayered secretion, which protects the spermatozoa during transfer to the female genital system and storage in the receptacula. In addition, a short description of the main cell components of the individual spermatozoa is given as a complement to previous studies. With the observation presented here, the suggestion that coenospermia are an ancestral character in the Araneae is further confirmed, and plesiomorphic features of spider sperms are consolidated.

Ultrastructural observations of spermatozoa and spermiogenesis in Wandella orana Gray, 1994 (Araneae: Filistatidae) with notes on their phylogenetic implications

Spermatozoa and spermiogenesis of the prithine filistatid spider Wandella orana are described. The spider produces coenospermia, i.e. sperm aggregations that include several single sperm cells commonly surrounded by a secretion sheath. One sectioned coenospermium in W. orana contains at least five spermatozoa. During copulation many coenospermia are transferred into the female. Coenospermia are regarded as a peculiar transfer form of sperm which occurs in early derivative spiders such as Liphistiomorphae and Mygalomorphae. The only exception which was found in Araneomorphae until now was the filistatine spider Filistata insidiatrix. Our observation is the second case and supports the view that Filistatidae represent an early derivative taxon. Furthermore, the individual sperm cells show characteristics which also may be regarded as being plesiomorphic. There is a cone-shaped acrosomal vacuole, a very long acrosomal filament, a rather stout nucleus and a small implantation fossa. The axoneme shows the 9x2+3 pattern of microtubules which is synapomorphic in Megoperculata (Uropygi, Amblypygi and Araneae). The finding of coenospermia in two distant taxa of Filistatidae may have consequences for phylogenetic and systematic considerations.

Ultrastructural investigations of testes and spermiogenesis in two species of halacarid mites (Halacaridae, Actinedida, Actinotrichida): Thalassarachna basteri from the Baltic Sea and Halacarellus thomasi from McMurdo Sound (Antarctica)

Testes and sperm cells of two species of halacarid mites, Thalassarachna basteri from the Baltic Sea and Halacarellus thomasi from McMurdo Sound (Antarctica), were investigated. Testes are paired structures, composed of a glandular and a germinal part. The testicular lumen is filled with a very complex secretion that contributes to sperm cell aggregates. Early spermatids of T. basteri display unusual chromatin condensation within the nucleus, but the formation of an acrosomal complex with a small acrosomal vesicle and a long acrosomal filament can be regarded as typical for the group. Tubular invaginations of the plasmalemma occur at the cell periphery. A deep, ring-like infold divides the cell into one part containing the chromatin body and another containing mainly the invaginations and the acrosomal complex. The mature sperm cell is ovoid, aflagellate and surrounded by a distinct secretion sheath. In H. thomasi only a limited number of spermiogenesis stages were observable. Chromatin condensation was rather similar and peripheral invaginations also occurred. However, no acrosomal complex was observed in the early stages. The division of the mature sperm cells into two halves was even more pronounced in H. thomasi, since one half of the cell contained masses of convoluted structures. The same half also contained a structure that remotely resembled an acrosomal complex. The observed differences between T. basteri and H. thomasi sperms support the placing of the two halacarids in separate genera.

Fine structure of the female genital system in phytoseiid mites with remarks on egg nutrimentary development, sperm-access system, sperm transfer, and capacitation (Acari, Gamasida, Phytoseiidae)

The fine structure of the female genital system is described in two phytoseiid species: Phytoseiulus persimilis Athias-Henriot (mating females) and Typhlodromus rhenanoides Athias-Henriot (overwintering females). The female genital tract is composed of an unpaired gonad, the uterus (oviduct I), and the vaginal duct (oviduct II). The latter leads to the vagina (genital atrium), into which a pair of vaginal glands opens. The gonad (ovary s.l.) has two components: the ovary (s.str) where germ cells develop and the lyrate organ serving as a nutrimentary compartment. In the ovary (s.str.), somacells and germ cells are observed. The germ cells surround a central tissue, to which they have direct contact with a nutritive cord at least in the previtellogenic phase during oogenesis. In fertilized females, cells likely representing capacitated sperm cells are also found in the ovary. The lyrate organ has two arms that extend anteriorly but join in their posterior part in front of the ovary (s.str.). The lyrate organ is composed of a somatic (supporting) and a nutritive tissue. The nutritive tissue, which is a syncytium, is continuous with the central tissue. The uterus starts from the ventral region of the central tissue. Finally, the ultrastructure of the sperm-access system, composed of paired solenostomes, major and minor ducts, emboli, calyces, and vesicles, is reported and functional aspects are discussed. The minor ducts end in the somatic tissue of the ovary s.str. However, because of its extremely reduced lumen and the peculiar morphology of its beginning, it seems unlikely that the minor duct lumen serves as a simple route for the sperm towards the ovary.

Effects of fire on the state of several elements in some soils of Sardinia

In order to individuate the modifications induced in the soil by fires relatively to the mobility of metals and rare earth three soils of Sardinia which differ in their mineralogical and physico-chemical characteristics were sampled. The analytical results obtained on the samples drawn at different depths (0-5 and 10-30 cm) three months after a fire and on the tests indicate that only the surface layer underwent significant modifications. The dynamics of metals and the distribution of the rare earths were found to depend, besides the amount and quality of the burned material, on the different behaviour of elements towards leaching. The diffractometric analysis showed that the soil surface layer of all the samples did not exceed 400 degrees C.

Fine structure of the spermatophore and spermatozoa in inseminated females of Pergamasus mites (Acari: Gamasida: Pergamasidae)

This study describes the spermatophore of Pergamasus mites after transfer into the female endogynial sac and modifications of the structure of the female-penetrating spermatozoa. The spermatophore is saccular and contains largely unmodified spermatozoa and variously structured secretions. The spermatozoa that leave the spermatophore reach the inner (proximal) end of the vaginal duct where they presumably escape from the genital tract to continue their route through the hemocoel into the ovarian tissue where fertilization occurs. During this transit, the structure of such spermatozoa changes considerably, in particular when in contact with the ovary. These alterations include modifications of the cell periphery and of certain inclusion bodies. Furthermore, the spermatozoa form protrusions that fit into corresponding invaginations of the somatic tissue of the ovary.

Shaping Solid-State Supramolecular Cavities: Chemically Induced Accordionlike Movement of gamma-Zirconium Phosphate Containing Polyethylenoxide Pillars

The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space.

Molecular basis of open-angle glaucoma in Italy

Glaucoma is a group of ocular diseases characterized by an optic neuropathy in which degeneration of retinal ganglion cells leads to a characteristic excavation of the optic nerve head. Primary open-angle glaucoma (POAG) can be subdivided into two groups according to age of onset:- 1. the more common middle- to late-age onset, chronic open-angle glaucoma (COAG) diagnosed after the age of 40 years; 2. the rarer juvenile open-angle glaucoma (JOAG), which is diagnosed between the age of 3 years and early adulthood. Recently, the gene coding for the trabecular meshwork-induced glucocorticoid response protein (TIGR), located in chromosome 1 (1q23-25), was found mutated in patients affected by POAG. In this work we describe the clinical and molecular genetic features of several Italian families affected by autosomal dominant POAG, collected in various regions of Italy.

Mechanism of the Topotactic Formation of gamma-Zirconium Phosphate Covalently Pillared with Diphosphonate Groups

The topotactic reaction of gamma-ZrPO(4)[O(2)P(OH)(2)].2H(2)O (gamma-ZrP) with benzenediphosphonic acid was examined in water and in acetone-water mixtures. This reaction was found to take place in water only on the external surface of the microcrystals, and pillared compounds were never obtained, even after very long reaction times. On the contrary, covalently pillared compounds were quickly obtained in acetone-water mixtures. The mechanism of the latter topotactic reaction was investigated by determining the rate of the phosphate groups released and the rate of the benzenediphosphonates taken up by gamma-ZrP over a long time (50 days). These data showed that pillared derivatives of gamma-ZrP can be obtained because colloidal dispersions of exfoliated lamellae are formed in acetone-water mixtures. The diphosphonate group acts initially as a monovalent species, replacing only one dihydrogen phosphate group on the surface of the exfoliated gamma-lamellae. The colloidal and partially derivatized lamellae thus formed can interact with each other by forming polylamellar pillared systems. When the number of pillared lamellae exceeds a given value (usually 5-6), flocculation of the colloidal gamma-ZrP takes place. Topotactic reactions between packets of pillared lamellae may also continue in the flocculated system. Therefore, the average number of the pillared lamellae slowly increases over time.