Gerd Alberti

The 70 kD heat shock protein (hsp 70) in soil invertebrates: A possible tool for monitoring environmental toxicants

The expression of hsp 70 after heat shock or exposure to heavy metals/molluscicides was investigated by fluorography or immunoblot in three diplopods (Glomeris marginata, Cylindroiulus punctatus, Tachypodoiulus niger), two slugs (Deroceras reticulatum, Arion ater), and one isopod (Oniscus asellus). In O. asellus, hsp 70 expression occurred after heat shock and also after lead treatment, whereby a solution of 100 mg/kg Pb2+ was sufficient. Animals of the same species taken from a heavy metal polluted site in the vicinity of a lead/zinc smelter also showed the presence of hsp 70. The comparision of laboratory and field experiments demonstrated the suitability of O. asellus for monitoring tests. In contrast, the blot pattern after contamination with 1,000 mg/kg Pb2+ (in the mentioned diplopods) or different concentrations of the molluscicide Cloethocarb (BASF, FRG) (slugs) showed no differences compared to the respective control group.

Cellular hepatopancreatic reactions in Porcellio scaber (Isopoda) as biomarkers for the evaluation of heavy metal toxicity in soils

Abstract Following three weeks exposure to the heavy metals Cd, Pb or Zn from a contaminated substrate/food the accumulation of these elements in the body of the woodlouse, Porcellio scaber was measured. In both cell types of the hepatopancreas of this isopod species, heavy metal exposure led to ultrastructural alterations, the degree of which was found to be dose-dependent. Low metal concentrations caused reactions of distinct organelles, whilst comparably higher concentrations resulted in pathological changes in the epithelium of the hepatopancreas. Most probably, the adverse effect of high metal concentrations on the apical cell membrane resulting in a diminished absorption of nutrients together with the induction of metal detoxification processes are the reasons for a general energy deficiency which is mirrored by various symptoms of starvation in the hepatopancreatic tissue. The observed effects could be used as biomarkers for an assessment of the adverse impact of subchronic heavy metal exposure.

Fine structure of spermatozoa of some labidognath spiders (Filistatidae, Segestriidae, Dysderidae, Oonopidae, Scytodidae, Pholcidae; Araneae; Arachnida) with remarks on spermiogenesis

The present study reports on the spermiogenesis and spermatozoa of seven labidognath spiders: Filistata insidiatrix (Filistatidae), Segestria senoculata (Segestriidae), Dysdera sp., Harpactea hombergi (Dysderidae), Oonops domesticus (Oonopidae), Scytodes thoracica (Scytodidae), and Pholcus phalangioides (Pholcidae). Filistata insidiatrix is the first cribellate spider whose spermatology is described electron microscopically. A common characteristic of the spermatozoa of the cribellate spider and the remaining species, often referred to as haplogyne spiders, is the coiling process that occurs at the end of spermiogenesis. As a result of coiling, an elongated spermatid is converted into a lens‐shaped structure with the flagellum bearing a 9 × 2 + 3 axoneme becoming incorporated into the cell body. Remarkable differences regarding the main components (shape of nucleus, acrosomal vacuole, implantation fossa, and centriolar complex) probably reflect systematic relationships.

Metal accumulation strategies in saprophagous and phytophagous soil invertebrates: a quantitative comparison

To quantitatively reveal accumulation patterns of environmentally relevant heavy metals in selected saprophagous or phytophagous soil invertebrates, adults of the species Porcellio scaber (Isopoda), Tetrodontophora bielanensis (Collembola), Julus scandinavius (Diplopoda), and Deroceras reticulatum (Gastropoda) were exposed to lead-, cadmium-, or zinc-contaminated food and soil for three weeks. The heavy metal concentrations in the food, the substrate, and the bodies of the invertebrates were measured by atomic absorption spectrophotometry (AAS). The investigated species were found to differ in their metal accumulation strategies, which is interpreted as a consequence of different detoxification mechanisms.

Content, absorption quantities and intracellular storage sites of heavy metals in Diplopoda (Arthropoda)

By means of atomic absorption spectrophotometry, concentrations of more than 2500 mg kg−1 Pb, 150 mg kg−1 Zn, and 320 mg kg−1 Cd could be detected in the intestine tissues of diplopods from a lead and silver smelters spoil bank. While only small portions of the ingested lead and cadmium are absorbed in the midgut of these diplopods, the zinc uptake into the midgut epithelium reaches 33.8–37.5% of the zinc content in the food pulp when the animals were contaminated acutely. However, after long-term contamination with zinc, absorption and excretion of this metal balanced one another. Absorbed lead and cadmium are predominantly stored in the midgut cells of the diplopods; unspecific precipitation of heavy metal showed the spherites of the resorptive epithelial cells to be the main accumulation sites. Zinc is for the most part localized in or near the cuticle; electron energy loss spectroscopy and ESI electron spectroscopic imaging, however, showed this metal to be present also in the spherites of the midguts resorption cells. These spherites are assigned to belong to the ‘type A granule’ group since (i) they are concentrically structured, (ii) they are shown to contain great amounts of calcium and (iii) copper, a class B metal, could not be detected in these deposits.

Fine structure of the genital system in the bee parasite,Varroa jacobsoni (Gamasida: Dermanyssina) with remarks on spermiogenesis, spermatozoa and capacitation

The female genital tract ofVarroa jacobsoni is composed of a sperm-access system comprising paired solenostomes located between coxa III and IV, paired tubules, paired rami, an unpaired sperm duct, and an unpaired spermatheca. Another part of the female genital system is confined to egg development and oviposition. It is composed of an ovary (s.str.), in which oocytes mature, and a lyrate organ functioning as a nutrimentary structure. Both compartments, regarded as parts of the gonad, are connected by a region named the camera spermatis. This part is also in continuity with the oviduct I, which is provided with a muscular layer and numerous nerve endings. The following cuticle-lined oviduct II leads to the genital orifice through which the eggs are deposited. The fine structure of all these parts is described. Attention is drawn especially to the peculiar spermatheca which contains the “inner cells” which are thought to connect by way of free cells with a specialized region of the camera spermatis, thus establishing a “cellular bridge” through which penetration of capacitated spermatozoa into the ovary s.str. may occur. Lyrate organ and oocytes are connected via intercellular bridges/nutritive cords and are thus comparable to the telotrophic ovarioles of certain insects.The male genital system, composed of unpaired testis, paired vasa deferentia, unpaired accessory gland and ductus ejaculatorius, is described ultrastructurally. Spermiogenesis occurs in cysts and spermatozoa belong to the “ribbon type”. The vasa deferentia are provided with a muscular layer. For the first time receptors are detected in the proximal part or the ductus ejaculatorius. The accessory gland produces a proteinaceous secretion.Spermatozoa were observed in the female rami and spermatheca. Only in the latter were elongated, capacitated spermatozoa seen.

Mineral congregations, “spherites” in the midgut gland ofCoelotes terrestris (Araneae): Structure, composition and function

SummarySpherites in the digestive and secretory cells of the midgut gland of the agelenid spiderCoelotes terrestris were studied by electron microscopy and histochemical methods. Spherites measured 1–6 μm in diameter and were characterized by alternating layers of electron dense and electron lucent material. The main-components of spherites were calcium phosphates and calcium carbonates. Guanine and barium, as well as aminopeptidase and alkaline phosphatase were also present. The matrix consisted of proteins and carbohydrates. Numerous spherites were found together with excretory products within the excretory vacuoles of the digestive cells.Spiders fed with food containing lead, showed deposition of the metall in the spherites. It is then proposed that spherites, aside from their role in storing calcium and other ions, may function in detoxification of heavy metals.

Fine structure of scorpion spermatozoa (Buthus occitanus; buthidae, scorpiones)

The mature spermatozoa of Buthus occitanus are threadlike in shape and divided into sperm head, middle piece, and end piece. The sperm head is corkscrew shaped anteriorly and in this region bears an unusual acrosomal complex consisting of a ring‐shaped acrosomal vacuole associated with a subacrosomal filament and a perinuclear amorphous component. The subacrosomal filament extends posteriorly into a tube‐like invagination of the elongated nucleus. The middle piece is characterized by elongated mitochondria which spiral around the anterior part of the flagellum in an extended collar separated from the flagellum by an extracellular cleft, termed the central flagellar tunnel. In addition to the usual 9 × 2 + 2 axonemal pattern in flagella, 9 × 2 + 1 and 9 × 2 + 3 patterns also were observed. The end piece is represented by the free flagellum. Similarities and diversities of scorpionid spermatozoa are discussed with respect to systematic relationships.

In situ observation of the Cardinium symbionts of Brevipalpus (Acari: Tenuipalpidae) by electron microscopy

Brevipalpus (Acari: Tenuipalpidae) mites are important pests on a variety of host plant species. The mites damage their hosts directly by feeding and some species also serve as vectors of plant viruses. Among more than 200 described Brevipalpus species, three are recognized as vectors of plant viruses: B. phoenicis, B. californicus and B. obovatus. These species occur worldwide in subtropical and tropical regions. Brevipalpus mites reproduce mostly by thelytokous parthenogenesis and this condition was attributed to a bacterial endosymbiont, recently characterized as a member of the genus Cardinium. The same symbiont infects many other arthropods and is capable of manipulating their host reproduction in various ways. Generally the presence of Cardinium is determined by molecular, PCR based, techniques. In the current work we present visual evidence for the presence of these bacteria by transmission electron microscopy as a complement of previous detection by PCR. Cardinium is easily identified by the presence of a unique array of microtubule-like structures (ML) in the cell. Symbionts have been observed in several organs and eggs from different populations of all three Brevipalpus species known as vector of plant viruses. Cardinium cells were always immersed directly within the cytoplasm of infected cells. Bacteria were observed in all females of all instars, but were absent from all males examined. Females from some Brevipalpus populations were observed to be uninfected by Cardinium. This observation confirmed previous PCR-based results that these populations were aposymbiotic. The observed distribution of the bacteria suggests that these bacteria could have other functions in the mite biology beside feminization.

Fortpflanzungsverhalten und fortpflanzungsorgane der schnabelmilben (Acarina : Bdellidae, Trombidiformes)

SummaryAn investigation of the biology and anatomy of the mite family Bdellidae (Trombidiformes) included a study of the mating behaviour and the genital system of ten species.1.In the Bdellids insemination takes place with the aid of spermatophores. Spermatophores of species of all four subfamilies were observed. Cyla latirostris (Cytinae) forms simple spermatophores, each with a non-covered sperm drop on its top. Two other types of spermatophores are described, i.e. those of a) Spinibdellinae, and b) Bdellinae and Odontoscirinae. In both types the sperm liquid is covered by a secretion similar to the material forming the stalk of the spermatophore. In Bdellinae and Odontoscirinae a “penis” is extruded during deposition of the spermatophores.2.The eggs of Bdellids are deposited at sheltered places by means of an ovipositor. Spiny globular and reddish eggs have been observed in all subfamilies. The eggs of Biscirus (flat, lenticular), Spinibdella cronini (thin-shelled, globular, with a spun protective covering) and Bdellodes longirostris (globular, tuberculated, whitish) are different. The eggs of these species have no spines.3.A comparative study of the complicated male genital system is given. Striking anatomical differences distinguish the group of Bdellinae and Odontoscirinae from the group of Cytinae and Spinibdellinae. The shape of the sperm cells is also different in the two groups. The secretion produced in the genital tract or accessory glands is formed to a specific spermatophore by means of the so-called penis, which in Biscirus, Bdellinae and Odontoscirinae acts as a matrix to build up the head of the spermatophores.4.The genital system of the female is described. After entering pouches (“follicles”) which are built up by the ovarian epithelium, yolk and yolk-shell can be observed in the oocytes. The secreta of the external eggshell are produced in the unpaired oviduct, which is divided into two parts (oviduct I and II). The mature eggs are stored in the oviduct I until deposition. The development of the eggs reaches this state even without previous insemination. The sperm is taken up by the female by means of the ovipositor, which has a specific receptaculum seminis (Cyla latirostris excl.) at the distal end. There is no communication between receptacle and oviduct. In the opisthosoma of the adult Bdellid female lateral groups of basophil staining cells similar to those described in several trombiforme mites were observed. The function of these cells is still unknown.ZusammenfassungIm Rahmen einer Arbeit fiber Bionomie und Anatomie der Milbenfamilie Bdellidae (Trombidiformes) wurde das Fortpflanzungsverhalten sowie der Ban der Geschlechtsorgane an zehn Arten untersucht.1.Bei den Bdelliden ist die indirekte Spermaübertragung mit Hilfe von Spermatophoren ausgebildet. Es konnten Spermatophoren von Arten aus allen vier Unterfamilien beobachtet werden. Cyta latirostris (Cytinae) bildet Tröpfchenspermatophoren. Bei den übrigen Arten wird das Spermatröpfchen von Sekret umgeben: Kammertyp bei Biscirus silvaticus (Spinibdellinae), Endfadentyp bei Bdellinae und Odontoscirinae. Bei Bildung der Endfadenspermatophore wird ein penisartiges Organ ausgestülpt2.Die Eier der Bdelliden werden mit Hilfe eines Ovipositors an geschützten Stellen abgesetzt. In allen Unterfamilien kommen kugelige, bestachelte und gelbbis rotbraun gefärbte Eier vor. Abweichend sind die Eier von Biscirus (abgeflacht, linsenförmig), Spinibdella cronini (diinnschalig, kugelig, mit Schutzgespinst) und Bdellodes longirostris (kugelig, mit Höckern, weißlich) ausgebildet. Die Eier dieser Tiere sind unbestachelt.3.Der komplizierte männliche Genitaltrakt wird vergleichend untersucht. Die Bdellinae und Odontoscirinae können aufgrund deutlicher anatomischer Unterschiede von den Cytinae und Spinibdellinae abgegrenzt werden. Auch die Form der Spermien unterscheidet sich in beiden Gruppen. Der sogenannte Penis ist ein Organ, welches das im Genitaltrakt bzw. in den akzessorischen Drüsen abgegebene Sekret zur artspezifisch ausgebildeten Spermatophore formt. Dabei wird das Köpfchen der Endfaden- bzw. Kammerspermatophore in einer Gußform vorgebildet.4.Der weibliche Genitaltrakt wird beschrieben. Nachdem die Oozyten in vom Ovarepithel gebildeten Taschen (“Follikel”) geriickt sind, treten Dotter und Dotterhaut auf. Die Sekrete der äußeren Eihülle werden im unpaaren, in zwei Abschnitte gegliederten Ovidukt (Ovidukt I und II) abgeschieden. Die reifen Eier werden im Ovidukt I bis zur Eiablage gespeichert. Auch ohne Spermaaufnahme läuft die Oogenese bis zu diesem Stadium. Die Spermaaufnahme durch das ♀ erfolgt mit Hilfe des Ovipositors, der distal ein von Art zu Art unterschiedlich strukturiertes Receptaculum seminis trägt. Eine Verbindung zwischen Receptaculum und Ovidukt besteht nicht. Das Receptaculum fehlt bei Cyta latimstris. Bei adulten Bdelliden-♀♀ konnten die auch von anderen trombidiformen Milben bekannten und in ihrer Funktion umstrittenen lateralen Zellgruppen (“aterale Zellen”) nachgewiesen werden.