The nervous and muscular systems in the free-living flatworm Castrella truncata (Rhabdocoela): an immunocytochemical and phalloidin fluorescence study

In order to broaden the information about the organisation of the nervous system in the Plathelminthes, an immunocytochemical (ICC) study of the free-living flatworm Castrella truncata (Dalyellioida) has been performed. This is the first time a representative of the taxon Rhabdocoela has been studied with the ICC technique. Antibodies to 5-HT and FMRF-amide and confocal scanning laser microscope were used. 5-HT and FMRF-amide immunoreactivity was observed in the neuropile of the brain, in the cerebral neurones, in the three pairs of longitudinal nerve cords and the adjoining neurones, in the pharyngeal nerve ring and in twelve neurones associated with the pharynx. 5-HT and FMRF-amide immunoreactivity occurs in separate sets of neurones. Only FMRF-amide immunoreactivity was observed in a peculiar ellipse-shaped structure in the brain, and in the genital plexus. The type of orthogon is discussed. Staining of the muscular system with TRITC conjugated phalloidin revealed muscle patterns that have not been described previously.     

Plasminogen activator and collagenase production by cultured capillary endothelial cells

Cultured bovine capillary endothelial (BCE) cells produce low levels of collagenolytic activity and significant amounts of the serine protease plasminogen activator (PA). When grown in the presence of nanomolar quantities of the tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA), BCE cells produced 5-15 times more collagenolytic activity and 2-10 times more PA than untreated cells. The enhanced production of these enzymes was dependent on the dose of TPA used, with maximal response at 10(-7) to 10(-8) M. Phorbol didecanoate (PDD), an analog of TPA which is an active tumor promoter, also increased protease production. 4-O-methyl-TPA and 4α-PDD, two analogs of TPA which are inactive as tumor promoters, had no effect on protease production. Increased PA and collagenase activities were detected within 7.5 and 19 h, respectively, after the addition of TPA. The TPA-stimulated BCE cells synthesized a urokinase-type PA and a typical vertebrate collagenase. BCE cells were compared with bovine aortic endothelial (BAE) cells and bovine embryonic skin (BES) fibroblasts with respect to their production of protease in response to TPA. Under normal growth conditions, low levels of collagenolyic activity were detected in the culture fluids from BCE, BAE, and BES cells. BCE cells produced 5-13 times the basal levels of collagenolytic activity in response to TPA, whereas BAE cells and BES fibroblasts showed a minimal response to TPA. Both BCE and BAE cells exhibited relatively high basal levels of PA, the production of which was stimulated approximately threefold by the addition of TPA. The observation that BCE cells and not BAE cells produced high levels of both PA and collagenase activities in response to TPA demonstrates a significant difference between these two types of endothelial cells and suggests that the enhanced detectable activities are a property unique to bovine capillary and microvessel and endothelial cells.     

Palatability and feeding preferences of Uresiphita maorialis (Lepidoptera: Crambidae) for three Sophora species

In a three-hour bioassay, we tested the palatability and feeding preferences of Uresiphita maorialis (kōwhai moth) for Sophora tetraptera, Sophora microphylla and Sophora prostrata. Palatability tests showed no differences among the Sophora species. Feeding preferences, on the other hand, showed that S. tetraptera and S. microphylla leaves are preferred over S. prostrata leaves. Our results support our field observations in Wellington city parks and gardens showing that S. tetraptera and S. microphylla plants frequently have higher densities of larvae than S. prostrata.     

Inhibition of interferon secretion by vinblastine

The plant alkaloids vinblastine and colchicine are known to arrest cells in mitosis by virtue of their binding to spindle protein. These drugs are also capable of binding to microtubule protein and causing these structures to disaggregate into nonfunctional subunits (1, 2). Microtubular structures are thought to be involved in the secretory process of a number of proteins including insulin (7), collagen (4), and thyroid hormone (12). In this report we present our findings on the effects of these two drugs on the synthesis and secretion of interferon in a high producing human foreskin fibroblast strain (FS-4) (11).     

A commissural brain! The pattern of 5-HT immunoreactivity in Acoela (Plathelminthes)

 In order to solve the question whether Plathelminthes belonging to the taxon Acoela have a brain and an orthogon of the common flatworm type, an immunocytochemical study of the pattern of serotonin (5-HT) in four species was performed. In all species the 5-HT immunoreactivity revealed no ganglionic cell mass typical for other Plathelminthes, only a symmetrical brain-like structure composed of commissural fibres associated with a few cell bodies. 5-HT immunoreactivity was detected in three to five pairs of longitudinal nerve cords, connected by an irregular network of immunoreactive transverse fibres. No regular orthogon was visualised. All the surface sensilla were strongly immunoreactive. The unique commissural brain and cordal nervous system found in Acoela support the view of a deep gap lying between Acoela and other Plathelminthes. Accepted: 15 December 1997     

Rotifer muscles as revealed by phalloidin-TRITC staining and confocal scanning laser microscopy

By combining phalloidin‐TRITC staining with confocal scanning laser microscopy (CSLM), the pattern of the musculature in two species of Rotifera, Euchlanis dilatata unisetata and Brachionus quadridentatus is revealed. The same general muscle pattern prevails in both species. The major components of the body wall musculature are: 1. retractor muscles (5 pairs in E. dilatata unisetata and 3 pairs in B. quadridentatus); 2. Two pairs of dorso‐ventral muscles; 3. Two pairs of perpendicular muscles (in E. dilatata unisetata); 4. retractors of the corona (median, lateral and ventral); 5. Foot retractors. In addition, three pairs of cutaneo‐visceral muscles and visceral muscles (including mastax muscles) are described. The sphincter of the corona was found only in B. quadridentatus. The high degree of muscle differentiation points to a high level of development of rotifer muscular system.     

Influence of a natural and a synthetic inhibitor of factor XIIIa on fibrin clot rheology

We investigated the origins of greater clot rigidity associated with FXIIIa-dependent cross-linking. Fibrin clots were examined in which cross-linking was controlled through the use of two inhibitors: a highly specific active-center-directed synthetic inhibitor of FXIIIa, 1,3-dimethyl-4,5-diphenyl-2[2(oxopropyl)thio]imidazolium trifluoromethylsulfonate, and a patient-derived immunoglobulin directed mainly against the thrombin-activated catalytic A subunits of thrombin-activated FXIII. Cross-linked fibrin chains were identified and quantified by one- and two-dimensional gel electrophoresis and immunostaining with antibodies specific for the alpha- and gamma-chains of fibrin. Gamma-dimers, gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrids were detected. The synthetic inhibitor was highly effective in preventing the production of all cross-linked species. In contrast, the autoimmune antibody of the patient caused primarily an inhibition of alpha-chain cross-linking. Clot rigidities (storage moduli, G') were measured with a cone and plate rheometer and correlated with the distributions of the various cross-linked species found in the clots. Our findings indicate that the FXIIIa-induced dimeric cross-linking of gamma-chains by itself is not sufficient to stiffen the fibrin networks. Instead, the augmentation of clot rigidity was more strongly correlated with the formation of gamma-multimers, alpha(n)-polymers, and alpha(p)gamma(q)-hybrid cross-links. A mechanism is proposed to explain how these cross-linked species may enhance clot rigidity.     

Histological and immunohistochemical effects of Curcuma longa on activation of rat hepatic stellate cells after cadmium induced hepatotoxicity

The liver is a target for toxic chemicals such as cadmium (Cd). When the liver is damaged, hepatic stellate cells (HSC) are activated and transformed into myofibroblast-like cells, which are responsible for liver fibrosis. Curcuma longa has been reported to exert a hepato-protective effect under various pathological conditions. We investigated the effects of C. longa administration on HSC activation in response to Cd induced hepatotoxicity. Forty adult male albino rats were divided into: group 1 (control), group 2 (Cd treated), group 3 (C. longa treated) and group 4 (Cd and C. longa treated). After 6 weeks, liver specimens were prepared for light and electron microscopy examination of histological changes and immunohistochemical localization of alpha smooth muscle actin (αSMA) as a specific marker for activated HSC. Activated HSC with a positive αSMA immune reaction were not detected in groups 1 and 3. Large numbers of activated HSC with αSMA immune reactions were observed in group 2 in addition to Cd induced hepatotoxic changes including excess collagen deposition in thickened portal triads, interlobular septa with hepatic lobulation, inflammatory cell infiltration, a significant increase in Kupffer cells and degenerated hepatocytes. In group 4, we observed a significant decrease in HSC that expressed αSMA with amelioration of the hepatotoxic changes. C. longa administration decreased HSC activation and ameliorated hepatotoxic changes caused by Cd in adult rats.