The mast cells of the mammalian central nervous system

Summary The uptake and turnover of the precursors of heparin and heparan sulphate (³⁵S), and of serotonin (³H-5-hydroxytryptophan; ³H-5-HTP) by mast cells (MCs) and neurolipomastocytoid cells (NLMs) of the mammalian CNS were studied. Rats of varying age from 1 day to early adulthood were injected with ³⁵S (as a solution of sodium sulphate) and ³H-5-HTP, and allowed to survive for different periods. Several fixatives, as well as lengths of exposure to photographic emulsion, were tested. The monoamine oxidase inhibitor, nialamide, needed to be given before uptake of ³H-5-HTP could be adequately demonstrated especially in the CNS. ³⁵S was taken up by structures known to contain a great deal of sulphate, viz., cartilage and goblet cells, as well as by MCs of adult liver and thymus, but not by MCs of adult CNS. All of these structures, including the MCs of CNS, took it up much more avidly in babies than in adults. ³H-5-HTP had a similar effect in that the MCs of younger animals took it up more strongly than did those of adults. In the MCs of the CNS uptake seemed to increase up to 15 days of age but then to decrease as maturity was reached. The MCs are located in the leptomeninges of the cerebral hemispheres as well as the choroid fissures and dorsal thalamus. The NLMs, ubiquitously distributed in the leptomeninges as well as perivascularly, showed less radioactivity with both markers in fewer cells and only in babies. The possible significance of these results is discussed. It is concluded that MCs, and to a lesser extent NLMs, of the CNS do permit entry of these markers, and that the more immature the cells, the heavier the load that enters. Adult cells do not seem to take up precursor suggesting little or no turnover.Supported in part by a grant from the Incentive Plan of the Medical School, American University of Beirut, and by Research Support Grant MA-004 from the College of Graduate Studies, University of Kuwait     

Light inside sponges

Sponges are the most basal metazoan organisms. As sessile filter feeders in marine or freshwater habitats, they often live in close association with phototrophic microorganisms. Active photosynthesis by the associated microorganisms has been believed to be restricted to the outer tissue portion of the sponge hosts. However, phototrophic microorganisms have also been detected in deeper tissue regions. In many cases they are found around spicules, siliceous skelettal elements of demosponges and hexactinellids. The finding of phototrophic organisms seemingly assembled around spicules led to the hypothesis of a siliceous light transmission system in sponges. The principle ability to conduct light was already shown for sponge derived, explanted spicules. However it was not shown until now, that in deed sponges have a light transmission system, and can harbour photosynthetically active microorganisms in deeper tissue regions.Here we show for the first time, that, as hypothesized 13 year ago, sponge spicules in living specimens transmit light into deeper tissue regions. Our results demonstrate that in opposite to the actual opinion, photosynthetically active microorganisms can also live in deeper tissue regions, and not only directly beneath the surface, when a light transmission system (spicules) is present.Our results show the possibility of massive or globular sponges being supplied with photosynthetic products or pathways throughout their whole body, implying not only a more important role of these endobioses. Our findings also elucidate the in-situ function of a recently more and more interesting biomaterial, which is unique not only for its mechanical, electrical and optical properties. Biosilica is of special interest for the possibility to produce it enzymatically under environmental conditions.     

The responses of central octavolateralis cells to moving sources

Mechanosensory lateral line units recorded from the medulla (medial octavolateralis nucleus) and midbrain (torus semicircularis) of the bottom dwelling catfish Ancistrus sp. responded to water movements caused by an object that passed the fish laterally. In terms of peak spike rate or total number of spikes elicited responses increased with object speed and sometimes showed saturation (Figs. 7, 14). At sequentially greater distances the responses of most medullary lateral line units decayed with object distance (Fig. 11). Units tuned to a certain object speed or distance were not found. The signed directionality index of most lateral line units was between –50 and +50, i.e. these units were not or only slightly sensitive to the direction of object motion (Figs. 10, 17). However, some units were highly directionally sensitive in that the main features of the response histograms and/or peak spike rates clearly depended on the direction of object movement (e.g. Fig. 9C, D and Fig. 16). Midbrain lateral line units of Ancistrus may receive input from more than one sensory modality. All bimodal lateral line units were OR units, i.e., the units were reliably driven by a unimodal stimulus of either modality. Units which receive bimodal input may show an extended speed range (e.g. Fig. 18).Abbreviations MON medial octavolateralis nucleus - MSR mean spike rate - PSR peak spike rate - p-p peak-to-peak - SDI signed directionality index     

First reported occurrence of wewokellid sponges (Calcarea, Heteractinida) from the Permian of central Iran

The new calcisponges Regispongia fluegeli n. sp., and Iranospongia circulara n. gen. n. sp., are described from central Iran. These are the first heteractinid sponges reported from the Permian of the region. These wewokellid sponges are large, irregularly cylindrical forms with a distinct axial spongocoel. The calcareous spicular skeletons of both taxa have been overgrown and are recrystallized. However, the preserved skeleton of Regispongia fluegeli does include large polyactines in the main endosomal layer and small octactines and possibly other polyactine spicules in both the relatively massive dermal layer and the distinct, delicately spiculed, gastral layer. Iranospongia is characterized by a discontinuous ring of vertical exhalant canals interior to the dense dermal layer, and by an interior skeleton net that includes common coarse vertical fibers. Individual spicules in Iranospongia are commonly obscured, but locally some remnants of possible polyactines occur in outer parts of the skeleton.     

Bathyal sponges from the late Early Miocene of the Vienna Basin (central Paratethys,Slovakia)

Here we report, for the first time, a very rich and diversified sponge assemblage from late Early Miocene deposits of a central part of the Vienna Basin (Paratethys) in Slovakia. Bodily preserved sponges are described as a new genus and species Paracinachyrella fossilis (Tetiliidae, Demospongiae). Dissociated spicules reveal the presence of the “soft” demosponges that belong to families Tetillidae, Theneidae, Geodiidae, Samidae, Thrombidae, Thoosidae, Agelasidae, Myxillidae, Bubaridae, and Tedaniidae, the lithistid family Pleromidae, and an undetermined rhizoclone-bearing lithistid. Fragments of dictyonal skeleton indicate the presence of hexactinellid sponges that belong to the families Farreidae and Euretidae, and lychniscosan sponges. We estimate that at least 16–19 different species of siliceous sponges inhabited this region of the Central Paratethys during the latest Burdigalian. Most of these sponges are reported for the first time from the Miocene of the Paratethys. This sponge fauna has clear Tethyan affinities and indicates the existence of connection between Paratethys and Tethys during the latest Burdigalian, as well as the presence of open marine, deep-water, bathyal conditions in this part of the Vienna Basin.     

Evagination of cells controls bio-silica formation and maturation during spicule formation in sponges

The enzymatic-silicatein mediated formation of the skeletal elements, the spicules of siliceous sponges starts intracellularly and is completed extracellularly. With Suberites domuncula we show that the axial growth of the spicules proceeds in three phases: (I) formation of an axial canal; (II) evagination of a cell process into the axial canal, and (III) assembly of the axial filament composed of silicatein. During these phases the core part of the spicule is synthesized. Silicatein and its substrate silicate are stored in silicasomes, found both inside and outside of the cellular extension within the axial canal, as well as all around the spicule. The membranes of the silicasomes are interspersed by pores of ≈ 2 nm that are likely associated with aquaporin channels which are implicated in the hardening of the initial bio-silica products formed by silicatein. We can summarize the sequence of events that govern spicule formation as follows: differential GENETIC READOUT (of silicatein) → FRACTAL ASSOCIATION of the silicateins → EVAGINATION of cells by hydro-mechanical forces into the axial canal → and finally PROCESSIVE BIO-SILICA POLYCONDENSATION around the axial canal. We termed this process, occurring sequentially or in parallel, BIO-INORGANIC SELF-ORGANIZATION.     

Horny sponges and their affairs: on the phylogenetic relationships of keratose sponges

The demosponge orders Dictyoceratida and Dendroceratida are historically assigned to the keratose (or "horny") sponges, which are mostly devoid of primary skeletal elements, but possess an elaborate skeleton of organic fibres instead. This paucity of complex mineral skeletal elements makes their unambiguous classification and phylogenetic reconstruction based on morphological features difficult. Here we present the most comprehensive molecular phylogeny to date for the Dendroceratida, Dictyoceratida, and also other sponge orders that largely lack a mineral skeleton or skeletal elements at all (i.e. Verongida, Halisarcida, Chondrosida), based on independent mitochondrial and nuclear markers. We used molecular data to validate the coherence of all recognised orders, families and subfamilies that are currently defined using morphological characteristics. We discussed the significance of morphological and chemotaxonomic characters for keratose sponges, and suggested adapted definitions for the classification of dendroceratid, dictyoceratid, and verongid higher taxa. Also, we found that chondrosid sponges are non-monophyletic with respect to Halisarcida. Verongida and Dendroceratida were monophyletic, however most of their classically recognised families were not recovered. This indicated that the current distinction between dendritic and mesh-like fibre skeletons is not significant at this level of classification. Dysideidae were found to be the sister-group to the remaining Dictyoceratida. Irciniidae formed a distinct clade, however Thorectidae and Spongiidae could not be separated with the molecular markers used. Finally, we are establishing the name Verongimorpha for the clade combining verongid, chondrosid and halisarcid taxa and readjust the content of its sister-clade Keratosa.     

Sterols from some sponges

The sterol composition of four sponges was determined by a combination of gas chromatography and mass spectrometry. Cliona viridis and Chondrosia reniformis contained mainly C₂₇-C₂₉Δ⁵ mono- and di-unsaturated sterols. Halichondria bowerbanki and Hymeniacidon sanguinea contained stanols and Δ⁵-sterols. Cholestanol was the major component of the sterol mixtures.     

Body structure of marine sponges

Summary The Mediterranean sponges Reniera mucosa, Haliclona mediterranea, Reniera fulva, Dendroxea lenis and Reniera sarai and the Caribbean species Callyspongia sp., Niphates digitalis, Niphates sp. and Amphimedon compressa are the subjects of this study of the arrangement of the choanocyte chambers between the canal systems and their relation to the mesenchymal tissue. The phylogenetic significance of the different organizational features is discussed.Dedicated to Prof. Dr. Norbert Weissenfels on the occasion of his 60th birthday     

Body structure of marine sponges

Summary Specimens of Haliclona elegans (Bowerbank, 1866) are covered by a thin, double layered dermal membrane extending over large subdermal spaces. The pores in the dermal membrane are formed by single porocytes with one or sometimes several pores in the center of the cell. The subjacent tissue shows a faintly developed mesenchyme and numerous big choanocyte chambers projecting into lacunar spaces of the incurrent canal system. The outer surface of the chambers is directly covered by the pinacocyte epithelium of the incurrent canal wall, which also separates them completely from the mesenchyme. Water influx into the chambers is guaranteed by prosopylar openings in the pinacocyte cover at the outer chamber surface. The chambers are connected to the excurrent canal system in the eurypylous way by wide apopyles, each of which is surrounded by a small ring of flagellated cone cells. About 15% of the choanocyte chambers in H. elegans contain central cells, which are thought to derive from migrating pinacocytes of the canal systems.     

The sterols of calcareous sponges (Calcarea, Porifera)

Sponges are sessile suspension-feeding organisms whose internal phylogenetic relationships are still the subject of intense debate. Sterols may have the potential to be used as independent markers to test phylogenetic hypotheses. Twenty representative specimens of calcareous sponges (class Calcarea, phylum Porifera) with a broad coverage within both subclasses Calcinea and Calcaronea were analysed for their sterol content. Two major pseudohomologous series were found, accompanied by some additional sterols. The first series encompassing conventional C(27) to C(29)Delta(5,7,22) sterols represented the major sterols, with ergosterol (ergosta-5,7,22-trien-3beta-ol, C(28)Delta(5,7,22)) being most prominent in many species. The second series consisted of unusual C(27) to C(29)Delta(5,7,9(11),22) sterols. Cholesterol occurred sporadically, mostly in trace amounts. The sterol patterns did not resolve intraclass phylogenetic relationships, namely the distinction between the subclasses, Calcinea and Calcaronea. This pointed towards major calcarean lipid traits being established prior to the separation of subclasses. Furthermore, calcarean sterol patterns clearly differ from those found in Hexactinellida, whereas partial overlap occurred with some Demospongiae. Hence, sterols only partly reflect the phylogenetic separation of Calcarea from both of the other poriferan classes that was proposed by recent molecular work and fatty acid analyses.     

The inhibitory properties of various sponges on Listeria spp.

Various retail and environmental sponges were tested for inhibitory properties against Listeria species and several other bacterial genera. Sterile sponges, unrinsed and rinsed in sterile distilled water or sterile neutralizing buffer, were placed on seeded plates of tryptic soy agar with 0.6% yeast extract. Plates were incubated at 30°C for 24 h and zones of inhibition measured.
The Systems Plus environmental sponge and the Technical Service Consultants Ltd sponge (sTc)© proved to be the only sponges which consistently demonstrated no inhibitory properties. Results using scanning electron microscopy showed considerable bacterial attachment to the Systems Plus sponge, further corroborating these findings.     

Differentiation of PC12 cells in three-dimensional collagen sponges with micropatterned nerve growth factor

Micropatterning of biological cues is important for the guided formation of neuronal outgrowth and neuronal differentiation. Nerve growth factor (NGF) was micropatterned in a three-dimensional collagen sponges by using micropatterned ice lines that were composed of collagen and NGF. The micropatterned ice lines were prepared by a dispersing machine. PC12 cells were cultured in the NGF-micropatterned collagen sponges and showed micropatterned neurite outgrowth. The neurite outgrowth followed the micropattern of NGF with more neurite outgrowth in the collagen/NGF lines than in the regions between the collagen/NGF lines. The micropattern of the NGF and the neurite network of the PC12 cells can be manipulated by controlling the micropattern of the NGF. The three-dimensional porous scaffolds prepared by this method will have a potential application for the regeneration and repair of the nervous system.