Position of Pharyngeal Gland Outlets in Monhysteridae (Nemata)

In this study an attempt was made to determine the position of the outlets and nuclei of the pharyngeal glands in four monhysterid genera. Five Eumonhystera spp., seven Monhystera spp., and eight Monhystrella spp. were studied under the light microscope. Longitudinal sections of an undescribed Monhystera sp. and cross sections of Geomonhystera disjuncta were also studied under the scanning and transmission electron microscope, respectively. The results of the light microscopic studies were inconclusive about the position of the outlets but showed a number of nuclei in the basal part of the pharynx. The scanning and transmission electron microscopic studies revealed five pharyngeal glands and their outlets; their position was as follows: dorsal gland outlet at the base of buccal tooth, first pair of ventrosublateral gland outlets halfway along the pharynx, and second pair of ventrosublateral gland outlets close to the base of the pharynx. It is concluded that at least three, and possibly five, nuclei are in the basal part of the pharynx. This pattern, in the position of the outlets and nuclei, is similar to that in Caenorhabditis elegans (Maupas, 1900) Dougherty, 1953 and may well be the basic plan in the Class Chromadorea (including Secernentia as a subclass).     

Ultrastructure of the excretory system of the marine nematode Monhystera disjuncta

The excretory system of Monhystera disjuncta is a single ventral gland in the pharyngo-intestinal region. Its ultrastructural morphology is described. The posterior part is swollen, contains the nucleus and many secretory granules. This part gradually narrows anteriorly to form the cell neck, in the apical part of which a valve structure is differentiated. This pear-shaped valve structure opens into a cuticular duct which is embedded in an accompanying cytoplasmic sheath. The cuticular duct opens to the exterior by a pore between the two subventral inner labial papillae.     

Glypican-6, a new member of the glypican family of cell surface heparan sulfate proteoglycans.

The glypicans compose a family of glycosylphosphatidylinositol-anchored heparan sulfate proteoglycans. Mutations in dally, a gene encoding a Drosophila glypican, and in GPC3, the gene for human glypican-3, implicate glypicans in the control of cell growth and division. So far, five members of the glypican family have been identified in vertebrates. By sequencing expressed sequence tag clones and products of rapid amplifications of cDNA ends, we identified a sixth member of the glypican family. The glypican-6 mRNA encodes a protein of 555 amino acids that is most homologous to glypican-4 (identity of 63%). Expression of this protein in Namalwa cells shows a core protein of approximately 60 kDa that is substituted with heparan sulfate only. GPC6, the gene encoding human glypican-6, contains nine exons. Like GPC5, the gene encoding glypican-5, GPC6 maps to chromosome 13q32. Clustering of the GPC5/GPC6 genes on chromosome 13q32 is strongly reminiscent of the clustering of the GPC3/GPC4 genes on chromosome Xq26 and suggests GPCs arose from a series of gene and genome duplications. Based on similarities in sequence and gene organization, glypican-1, glypican-2, glypican-4, and glypican-6 appear to define a subfamily of glypicans, differing from the subfamily comprising so far glypican-3 and glypican-5. Northern blottings indicate that glypican-6 mRNA is widespread, with prominent expressions in human fetal kidney and adult ovary. In situ hybridization studies localize glypican-6 to mesenchymal tissues in the developing mouse embryo. High expressions occur in smooth muscle cells lining the aorta and other major blood vessels and in mesenchymal cells of the intestine, kidney, lung, tooth, and gonad. Growth factor signaling in these tissues might in part be regulated by the presence of glypican-6 on the cell surface.     

Tissue treatment for whole mount internal lectin staining in the nematodes Caenorhabditis elegans,Panagrolaimus superbus and Acrobeloides maximus

Four different fixation schemes, using ten fluorescent-labelled lectins, were investigated for whole mount internal staining of three rhabditid nematodes: Caenorhabditis elegans, Panagrolaimus superbus and Acrobeloides maximus. Acetone-only fixation was found to give strong and reproducible staining, which could be prevented either by periodate treatment of the organisms or by specific inhibitory sugars of the lectins under investigation. Whereas the use of either phosphate or TRIS buffers had no effect on the staining pattern or the fluorescence intensity, the incubation time as well as the incubation temperature affected the staining reaction. The best results were obtained upon overnight incubation at 4° C: the lectin staining could be inhibited in all cases, except for the intestinal brush border of C. elegans by the lectin of Lens culinaris.     

Apolipoprotein CI enhances the biological response to LPS via the CD14/TLR4 pathway by LPS-binding elements in both its N- and C-terminal helix

Timely sensing of lipopolysaccharide (LPS) is critical for the host to fight invading Gram-negative bacteria. We recently showed that apolipoprotein CI (apoCI) (apoCI_1–57) avidly binds to LPS, involving an LPS-binding motif (apoCI_48–54), and thereby enhances the LPS-induced inflammatory response. Our current aim was to further elucidate the structure and function relationship of apoCI with respect to its LPS-modulating characteristics and to unravel the mechanism by which apoCI enhances the biological activity of LPS. We designed and generated N- and C-terminal apoCI-derived peptides containing varying numbers of alternating cationic/hydrophobic motifs. ApoCI_1–38, apoCI_1–30, and apoCI_35–57 were able to bind LPS, whereas apoCI_1–23 and apoCI_46–57 did not bind LPS. In line with their LPS-binding characteristics, apoCI_1–38, apoCI_1–30, and apoCI_35–57 prolonged the serum residence of ¹²⁵I-LPS by reducing its association with the liver. Accordingly, both apoCI_1–30 and apoCI_35–57 enhanced the LPS-induced TNFα response in vitro (RAW 264.7 macrophages) and in vivo (C57Bl/6 mice). Additional in vitro studies showed that the stimulating effect of apoCI on the LPS response resembles that of LPS-binding protein (LBP) and depends on CD14/ Toll-like receptor 4 signaling. We conclude that apoCI contains structural elements in both its N-terminal and C-terminal helix to bind LPS and to enhance the proinflammatory response toward LPS via a mechanism similar to LBP.     

Ultrastructure of the photoreceptor of Diplolaimella sp. (Nematoda)

The photoreceptor of the free-living marine nematode Diplolaimella sp. is ultrastructurally described. The most prominent feature of the photoreceptor is called the 'ocellar complex' and is composed of three dorso-laterally located parts. (1) The lens is an amorphous half sphere-shaped structure, about 1.5 mum in diameter. (2) The receptoral part is a stack of slightly undulating lamellae, localized just posterior to the lens. (3) The receptoral part is surrounded by a pigment cup containing electron-dense granules of 0.1-0.3 mum diameter. These three parts are embedded in a cell process, which has a more sizeable ventral extension containing the nucleus and cytoplasm characterized by a lot of free ribosomes and broad cisternae of the granular endoplasmic reticulum. This sheath cell is supposed to synthesize the pigment. The above described structure occurs bilaterally paired, some 50 mum from the anterior end.     

The genus Paradorylaimus Andrássy, 1969 (Dorylaimoidea: Nematoda)

Examination of the type specimens of Dorylaimus parafecundus De Coninck, 1935 showed that the cuticle lacks longitudinal ridges. The species is a typical Laimydorus and is herewith redesignated L. parafecundus (De Coninck, 1935) n.comb. As it is the type species of Paradorylaimus Andrássy, 1969, the latter generic name falls as a synonym of Laimydorus Siddiqi, 1969 which has priority of publication. The three other species included originally in Paradorylaimus are dealt with as follows: P. wilhelmschneideri (Andrássy, 1959) is considered incertae sedis; P. heterurus (Schuurmans Stekhoven & Teunissen, 1938) was shown by Mulk et al. (1978) to belong in the genus Roqueus Thorne, 1964; P. filiformis (Bastian, 1865) is herewith returned to Laimydorus. Dorylaimus tenuistriatus Schneider, 1935 is not identical with L. parafecundus: it is more slender; odontostyle, pharynx and spicules are shorter; supplement number is lower; shape of vulva and the arrangement of the pharyngeal gland nuclei are different. The species is transferred to Laimydorus, becoming L. tenuistriatus (Schneider, 1935) n.comb. Lectotypes are designated for L. parafecundus and L. tenuistriatus. Among the material of L. tenuistriatus are specimens of L. pseudostagnalis (Micoletzky, 1927) and L. sp.     

Aquatic nematodes from Ethiopia V

Three species of chromadorids two of which are new to science are described from bottom samples of Lake Tana, L. Ziway and River Abbay, Ethiopia. Achromadora inflata n. sp. and Ethmolaimus zullinii n. sp. are characterized by a uniquely inflated and offset anterior end. The latter is an exception in its genus also by its possession of a well developed dorsal tooth and inconspicuous ventrosublateral denticles. Prodesmodora nurta Zullini, 1988 is reported here for the first time out of its type locality and is described in detail. SEM pictures of Ethmolaimus zullinii n. sp. and Prodesmodora nurta, and complete setae maps of the three species are also presented.Abbreviations used ABE = anterior body end - ABW = anal body width - Amph = amphid - Amph W = amphidial fovea width - CBW = corresponding body width - CSL = cephalic setae length - Ddent = dorsal denticle - GL = gonad length - L = length - LM = light microscope - LRW = lip region width - MBW = maximum body width - n = number of specimens - NR = nerve ring from the anterior end - PBE = posterior body end - Ph L = pharyngeal length (neck length) - PrL = prerectal length - RL = rectal length - SEM = scanning electron microscope - V-A = distance from vulva to anus - Vdent = ventral denticle - W = width     

A putative new hydrostatic skeletal function for the epidermis in Monhysterids (Nematoda)

The ultrastructure of the epidermis of two Monhysterid nematodes (Geomonhystera disjuncta and Diplolaimella dievengatensis) is studied in detail. The epidermis is composed of discrete uninucleated cells. The cytoplasmic layer of the epidermis between the cuticle and the somatic muscles is very thin and contains bundles of filaments that attach the muscles to the cuticle. The epidermal chords are voluminous and contain the nuclei and most of the cell organelles. In the chords many large electron-transparent vacuoles are found. It is hypothesized that these vacuoles fulfill a function as a compartmentalised hydrostatic skeleton.