Thalassomonhystera traesti n.sp., Eumonhystera andrassyi and three Monhystrella species (Monhysteridae: Nematoda) from Li River, China

A new Thalassomonhystera species, i.e. T. traesti n.sp., and a new subspecies, Monhystrella lepidura chinensis n. subsp., together with Eumonhystera andrassyi (Biró, 1969) Andrássy, 1981, Monhystrella macrura (de Man, 1880) Andrássy, 1981 and Monhystrella iranica Schiemer, 1965 are described from Li River at Guiling, China. Thalassomonhystera traesti n.sp. is characterised by a combination of the following characters: expanded lip region, large and anteriorly situated amphids, prominent inner labial sensilla, and slender spicules and tube-like gubernaculum in males. Monhystrella lepidura chinensis n. subsp. belongs to Monhystrella lepidura (Andrássy, 1963) Andrássy, 1968 but differs from the three hitherto described subspecies in its possession of a pharynx that posteriorly expands into a double bulb. Monhystrella macrura, M. iranica and Eumonhystera andrassyiare reported here for the first time from China.     

Aquatic nematodes from Ethiopia II

Eight species of the genus Monhystrella, six of which are new to science, are described from bottom samples collected from three lakes, two rivers and a hot spring in Ethiopia. Monhystrella hoogewijsi n. sp. is identified by a distinctive bulge on the lip region, position of the amphids, offset and well developed single pharyngeal terminal bulb, tail shorter than vulva-anus distance, tail elongate-conoid for two-thirds of its length, and by the shape and size of the spinneret outlet; M. jacobsi n. sp. by its slender body, distinctively offset and distended lip region, indistinct and weakly expanding single terminal pharyngeal bulb, and shape and size of the tail and spinneret outlet; M. arsiensis n. sp. by its single terminal pharyngeal bulb, position of amphids, shape and length of tail and spinneret outlet; M. woitorum n. sp. by its hemispherical lip region, double terminal pharyngeal bulb, shape and length of the spinneret outlet, and shape and length of tail; M. ethiopica n. sp. by its bipartite stoma, size of amphid in relation to corresponding body width, filiform tail and shape and length of spinneret outlet. M. atteae n. sp. differs from all known Monhystrella species in having an inflated cap-like lip region and fine crystalloid bodies. M. macrura (de Man, 1880) Andrássy, 1981 and M. lepidura altherri (Juget, 1969) Jacobs, 1987 are reported from Ethiopia for the first time. Crystalloid bodies in the genus Monhystrella is reported here for the first time. Also the presence of a hyaline coelomocyte next to the germinal zone of the reproductive system is reported for the first time in the genus here in all eight species. The structures used in the taxonomy of the genus are reviewed.     

Ultrastructure of sperm cells in the female gonoduct of Xiphinema

The ultrastructure of the sperm cells in the female gonoduct of the nematodes Xiphinema theresiae and X. pinoides is described. The nucleus of the sperm cells is composed of several electron-dense clumps of chromatin that is not surrounded by a nuclear envelope. A layer of mitochondria, in which the mitochondrial cristae are only rarely visible, lies around the nuclear material. In the surrounding cytoplasm packets of electron-dense fibres are abundant. The sperm in the uterus have the following surface differentiations: highly intertwined protrusions between adjacent sperm cells, protrusions coinciding with the plication of the inner uterine wall and a slightly undulated surface towards the uterine lumen. It is argued that in the uterus, the sperm cells actively move in proximal direction by a mechanism resembling pseudopodial movement, in which the packets of fibres are involved. In the oviduct, the sperm cells loose their surface protrusions and the packets of fibres gradually become less abundant. Since the oviduct has no pre-formed lumen, the sperm cells appear to wedge their way along by forcing oviduct cells apart.     

Regulation of Circadian and Acute Activity Levels by the Murine Suprachiasmatic Nuclei

The suprachiasmatic nuclei (SCN) coordinate the daily sleep-wake cycle by generating a circadian rhythm in electrical impulse frequency. While period and phase of the SCN rhythm have been considered as major output parameters, we propose that the waveform of the rhythm of the SCN also has significance. Using implanted micro-electrodes, we recorded SCN impulse frequency in freely moving mice and manipulated its circadian waveform by exposing mice to light-dark (LD) cycle durations ranging from 22 hours (LD 11∶11) to 26 hours (LD 13∶13). Adaptation to long T-cycles (>24 h) resulted in a trough in electrical activity at the beginning of the night while in short T-cycles (<24 h), SCN activity reached a trough at the end of night. In all T-cycle durations, the intensity of behavioral activity was maximal during the trough of SCN electrical activity and correlated negatively with increasing levels of SCN activity. Interestingly, small changes in T-cycle duration could induce large changes in waveform and in the time of trough (about 3.5 h), and accordingly in the timing of behavioral activity. At a smaller timescale (minutes to hours), we observed a negative correlation between SCN activity and behavioral activity, and acute silencing of SCN neurons by tetrodotoxin (TTX) during the inactive phase of the animal triggered behavioral activity. Thus, the SCN electrical activity levels appear crucially involved in determining the temporal profile of behavioral activity and controls behavior beyond the circadian time domain.     

Syndecan-syntenin-ALIX regulates the biogenesis of exosomes

The biogenesis of exosomes, small secreted vesicles involved in signalling processes, remains incompletely understood. Here, we report evidence that the syndecan heparan sulphate proteoglycans and their cytoplasmic adaptor syntenin control the formation of exosomes. Syntenin interacts directly with ALIX through LYPX(n)L motifs, similarly to retroviral proteins, and supports the intraluminal budding of endosomal membranes. Syntenin exosomes depend on the availability of heparan sulphate, syndecans, ALIX and ESCRTs, and impact on the trafficking and confinement of FGF signals. This study identifies a key role for syndecan-syntenin-ALIX in membrane transport and signalling processes.     

Libri novi

Ohne Zusammenfassung     

Localization of lead and fluoride in cultured tooth germs by laser microprobe mass analysis

Trace elements can influence dental health, possibly by altering tooth resistance during preeruptive development. Therefore, it was investigated whether lead and fluoride would be incorporated into the calcifying matrices or the cellular parts of tooth germs in vitro. Using laser microprobe mass analysis, the localization of lead and fluoride was studied in the different layers or tooth germs that had been cultured in a medium to which PbCl₂ of NaF had been added in different concentrations. Both elements could only be detected in the dentine layer. Hence, the enamel organ in the secretory stage of tooth development excludes lead and fluoride from the enamel, even when enamel formation by the ameloblasts is visibly disturbed. Furthermore, there seemed to be a process of saturation in the accumulation of lead and fluoride in the dentine.     

Ultrastructural Variation of Cuticular Layers in Cephalobinae (Nemata: Rhabditida)

The ultrastructure of the body wall cuticle in Acrobeles complexus, Cervidellus alutus, and Zeldia punctata was studied as a step toward understanding biological diversity within Cephalobinae, and to discover new characters for phylogeny-based classification of the suborder. In each species the cuticle consists of cortical, median, and basal layers. The cortical layer includes an external trilaminate and internal granular zone; the basal layer is striated. In Z. punctata the median layer is electron-lucent, vacuolar, and penetrates the cortical layer; it also includes periodically dense columns that apparently correspond to punctuations visible with light microscopy. In contrast, the median layer of the body wall cuticle in A. complexus and C. alutus is bisected by a zone that undulates parallel to the nematode surface and with periodicity corresponding to annuli. Phylogenetic analysis, using derived cuticle patterns of Cephalobinae, requires an understanding of ecological pressures that could result in convergent evolution of cuticle characters.     

Characterization of syntenin, a syndecan-binding PDZ protein, as a component of cell adhesion sites and microfilaments

Syntenin is a PDZ protein that binds the cytoplasmic C-terminal FYA motif of the syndecans. Syntenin is widely expressed. In cell fractionation experiments, syntenin partitions between the cytosol and microsomes. Immunofluorescence microscopy localizes endogenous and epitope-tagged syntenin to cell adhesion sites, microfilaments, and the nucleus. Syntenin is composed of at least three domains. Both PDZ domains of syntenin are necessary to target reporter tags to the plasma membrane. The addition of a segment of 10 amino acids from the N-terminal domain of syntenin to these PDZ domains increases the localization of the tags to stress fibers and induces the formation of long, branching plasma membrane extensions. The addition of the complete N-terminal region, in contrast, reduces the localization of the tags to plasma membrane/adhesion sites and stress fibers, and reduces the morphotypical effects. Recombinant domains of syntenin with the highest plasma membrane localization display the lowest nuclear localization. Syndecan-1, E-cadherin, beta-catenin, and alpha-catenin colocalize with syntenin at cell-cell contacts in epithelial cells, and coimmunoprecipitate with syntenin from extracts of these cells. These results suggest a role for syntenin in the composition of adherens junctions and the regulation of plasma membrane dynamics, and imply a potential role for syntenin in nuclear processes.     

Aquatic nematodes from Ethiopia VIII; Enoplids,with descriptions of Brevitobrilus fesehai n.sp. and B. tsalolikhini n.sp. (Enoplida: Nematoda)

Two new and one known species of the genus Brevitobrilus, Epitobrilus setosus, Tripyla glomerans, and Ironus ignavus and I. sphincterus are described from sediments of LakesShala, Tana and Ziway, and River Abbay, Ethiopia. Brevitobrilus fesehai n. sp. can be recognized by acombination of characteristics: in having a narrowanterior end, short cephalic and outer labial setae,long and bow-shaped spicules, the posteriormostsupplement at a distance of less than a spicule lengthfrom cloacal opening, numerous micropapillae, andterminal and subterminal setae. B. tsalolikhinin.sp. can also easily be differentiated from allknown species in the genus in having a combination ofcharacteristics: long cephalic and outer labial setae,short spicules without median stiffening piece, theposteriormost supplement situated very close to thecloacal opening, supplements with straight duct thatmerges with the dorsal wall of the ampulla, andelongate spermatozoa. The remaining five species aredescribed in detail. Also scanning electronmicroscopic pictures of B. fesehai n.sp., B. tsalolikhini n.sp., Epitobrilus setosus andTripyla glomerans are presented.