Bioproduction of cytochalasin D by endophytic fungus Xylaria sp. DAP KRI-5

Recently, endophytic fungi have attracted attention due to their ability to produce a variety of bioactive metabolites. Inthe course of our study on endophytic fungi associated with Albertisia papuana Becc, it has been found the endophyticfungus Xylaria sp. DAP KRI-5 produce cytochalasin D. Isolation of cytochalasin D was conducted by using anopen column chromatography method. The chemical structure of cytochalasin D was deduced from 1 dimension, 2dimension nuclear magnetic resonance, and ultra-performance liquid chromatography quadrupole time of flight massspectrometry analyses and also compared with the published data. The bioproduction capacity of cytochalasin D bythe fungus Xylaria sp. DAP KRI-5 was 0.05763 g/l.

Bioproduction of cytochalasin D by endophytic fungus Xylaria sp. DAP KRI-5

Recently, endophytic fungi have attracted attention due to their ability to produce a variety of bioactive metabolites. Inthe course of our study on endophytic fungi associated with Albertisia papuana Becc, it has been found the endophyticfungus Xylaria sp. DAP KRI-5 produce cytochalasin D. Isolation of cytochalasin D was conducted by using anopen column chromatography method. The chemical structure of cytochalasin D was deduced from 1 dimension, 2dimension nuclear magnetic resonance, and ultra-performance liquid chromatography quadrupole time of flight massspectrometry analyses and also compared with the published data. The bioproduction capacity of cytochalasin D bythe fungus Xylaria sp. DAP KRI-5 was 0.05763 g/l.

The dynamic structure of Spitzenkörpers of Trichosporon asahii examined by the fluorescent probe FM4-64

Abstract The Spitzenkörper is a dynamic and specialized multicomponent cell complex present in the tips of hyphal cells. The amphiphilic styryl dye FM4-64 was found to be ideal for imaging the dynamic changes of the apical vesicle cluster within growing hyphal tips. It is widely used as a marker of endocytosis and to visualize vacuolar membranes. Here we performed uptake experiments using FM4-64 to study the dynamic of the Spitzenkörper in Trichosporon asahii. We observed that Spitzenkörpers were present at the tip of the budding site of the spore, blastospore, and the germ tube of T. asahii. We also found that Spitzenkörpers were present at the tip of the hyphae as well as the subapical regions. Cytochalasin D, an inhibitor of actin polymerization, leads to abnormal Spitzenkörper formation and loss of cell polarity.

Antibacterial, antifungal and cytotoxic activities exhibited by endophytic fungi from the Brazilian marine red alga Bostrychia tenella (Ceramiales)

Abstract Marine environment is one of the most important sources regarding natural products research. Besides, marine microorganisms have been denominated as a talented natural source for discovery of new leads. Although the association of macroalgae and fungi has been described regarding ecological issues, there is a lack of studies about marine seaweed endophytic fungi. In this context, the goal of this study was to evaluate cytotoxic, antifungal and antibacterial activities of endophytic fungi isolated from the Brazilian marine seaweed Bostrychia tenella (J.V. Lamouroux) J. Agardh (Ceramiales, Rhodophyta). Forty-five endophytic microorganism strains were isolated from B. tenella. Crude extracts and organic fractions of ten selected strains were obtained after growth in rice medium. Samples were evaluated for cytotoxicity, antifungal and antibacterial assays. Penicillium strains showed positive results in a diversity of assays, and other five strains were active in at least one test. In addition, cytochalasin D was isolated from Xylaria sp. This alga is composed of a microbiological potential, since its endophytic strains exhibited remarkable biological properties. Moreover, cytochalasin D isolation has confirmed chemical potential of marine endophytic strains. This is the first study in which cultured fungi isolates from the Brazilian macroalga B. tenella were evaluated concerning biological properties. Results corroborated that this species could be a pharmaceutical source from marine environment. Furthermore, Acremonium implicatum is being firstly described as marine endophyte and Xylaria sp., Trichoderma atroviride and Nigrospora oryzae as marine seaweed endophytes. Thus, this work reports the first study relating detailed isolation, cultivation and biological evaluation (cytotoxic, antifungal and antibacterial) of endophytes Penicillium decaturense and P. waksmanii from the Brazilian marine red alga B. tenella. We are also reporting the isolation of cytochalasin D, a known antitumor and antibiotic compound, from Xylaria sp. strain. Despite widespread prevalence in terrestrial and marine habitats, this present work describes the first occurrence of cytochalasin D as a metabolite from marine seaweed endophyte.

Staurosporine and cytochalasin D induce chondrogenesis by regulation of actin dynamics in different way

Actin cytoskeleton has been known to control and/or be associated with chondrogenesis. Staurosporine and cytochalasin D modulate actin cytoskeleton and affect chondrogenesis. However, the underlying mechanisms for actin dynamics regulation by these agents are not known well. In the present study, we investigate the effect of staurosporine and cytochalasin D on the actin dynamics as well as possible regulatory mechanisms of actin cytoskeleton modulation. Staurosporine and cytochalasin D have different effects on actin stress fibers in that staurosporine dissolved actin stress fibers while cytochalasin D disrupted them in both stress forming cells and stress fiber-formed cells. Increase in the G-/F-actin ratio either by dissolution or disruption of actin stress fiber is critical for the chondrogenic differentiation. Cytochalasin D reduced the phosphorylation of cofilin, whereas staurosporine showed little effect on cofilin phosphorylation. Either staurosporine or cytochalasin D had little effect on the phosphorylation of myosin light chain. These results suggest that staurosporine and cytochalasin D employ different mechanisms for the regulation of actin dynamics and provide evidence that removal of actin stress fibers is crucial for the chondrogenic differentiation.

The Role of Intracellular Receptor NODs for Cytokine Production by Macrophages Infected with Mycobacterium leprae

The nucleotide-oligomerization domain (NOD) proteins are members of the NOD-like receptor (NLR) family, which are intracellular and cytoplasmic receptors. We analyzed the role of NODs for cytokine production by macrophages infected with intracellular pathogen M. leprae, the causative agent of leprosy. Production of pro-inflammatory cytokines such as IL-1beta and TNF-alpha was inhibited in the presence of cytochalasin D, an agent blocking phagocytosis, suggesting that intracellular signaling was, partially, required for macrophage activation to M. leprae infection. Next, we investigated the role of NOD1 and NOD2 proteins on NF-kappaB activation and cytokine expression. Treatment with M. leprae significantly increased NF-kappaB activation and expression of TNF-alpha and IL-1beta in NOD1- and NOD2-transfected cells. Interestingly, their activation and expression were inhibited by cytochalasin D, suggesting that stimulation of NOD proteins may be associated with the enhancement of cytokine production in host to M. leprae.

Effect of calcium channel blockers and actin depolymerizing/stabilizing agents on the survival of Schistosoma japonicum treated with praziquantel in vitro / 中国人兽共患病学报

To explore the action target of praziquantel (PZQ) and its underlying mechanism of action, adult male worms of Schistosoma japonicum were collected from the hepatic vein of Kunming mice infected at least 6 or more weeks previously with single-sex cercariae of S.japonicum by perfusion method. These worms were subjected to the action of calcium channel blockers (CCBs) or actin depolymerizing/stabilizing agents interfering with function of the calcium channel. The adult male worms in DMEM culture medium were co-cultivated with near-lethal dose of PZQ(14 μmol/L) overnight(16 hours).Then, the parasites were washed 3 times with sterile physiologic saline next morning after cultivation, re-suspended in new and drug-free medium and then observed under stereo-microscopy during the following 5 days. The experimental results showed that majority of adult male worms of S.japonicum were killed by the action of PZQ in a dose of 14 μmol/L in vitro under normal condition; while the worms pre-incubated with the actin depolymerizing agent cyto chalasin D (CyD) were able to survive in the condition containing 14 μmol/L of PZQ with a survival rate of 100%, and the worms pre-incubted with CCBs, such as nitrendipine and nifedipineu showed a survival rate of about 50% under the same condition. The results of this study suggest that the calcium channel of Schistosomes may be involved in the action target of PZQ and its underlying mechanism.

Morphological Changes of Cultured Rat Hepatocytes Induced by Phalloidin and Cytochalasin D / 대한해부학회지

The microfilaments of hepatocyte are distributed throughout the vicinity of cell membranes, especially numerous around the region of bile canaliculus, and provide the maintenance of cell shape, cellular wall tension, canalicular motility, the secretion for bile, etc. To evaluate the relationship between the microfilament and alteration of cell shape, we examined the morphological changes of cultured rat hepatocytes, following treatments with phalloidin or cytochalasin D with fluorescent and electron microscopes. 1. In the fluorescent micrographs, actin microfilament was distributed near the plasma membrane and bile canaliculus. 2. Both drugs, phalloidin or cytochalasin D, produce the cytoplasmic protrusions from the surface. Their shapes were pedunculated with narrow neck or bulged with broad base, respectively. 3. In the phalloidin treated group, cytoplasmic protrusion was seperated from the internal cytoplasm by microfila-ments networks at the narrow base. In contrast, in the cytochalasin D treated group, cytoplasm was bulged with broad base and kept in direct continuity with the canalicular ectoplasm. 4. Pericanalicular ectoplasm of phalloidin treated group was widened and accumulated with microfilaments. But, bile canaliculus of cytochalasin D treated group was markedly dilated and devoid of microvilli, and the ectoplasm was almost disappeared. Considering above results, dysfunction of microfilaments leads to the structural changes and inhibition of bile secretion of hepatocytes.

Ultrastructural Changes of the Cultured Hepatocytes in Microfilamentous Dysfunction induced by Drugs / 대한해부학회지

To examine the role of actin microfilaments which are located at beneath the plasma membrane, we observed the ultrastructural changes of rat hepatocyte induced by alteration of the microfilamentous integrity. The isolated hepatocytes from Sprague-Dawley were cultured in the L-15 medium containing phalloidin (agent that cause polymerization of actin) or cytochalasin D (agent that cause depolymerization of actin) for 30 min, 1 hour, 2 hours, 4 hours, 10 hours and 20 hours, respectively. The results observed with scanning and transmission electron microscope were as follows. 1. Following the alteration of actin microfilaments, bile canaliculi were dilated and devoid of microvilli. In phalloidin treated group, the thickening of microfilamentous ectoplasm was more marked than that of cytochalasin D treated group. Whereas, the dilation of bile canaliculi was more marked in cytochalasin D group. 2. Both drugs, phalloidin or cytochalasin D, produced the alteration of cell shape to form cytoplasmic protrusions at the cell surface. In the phalloidin treated group, protrusions were pedunculated, and the microfilament networks were accumulated at the narrow neck region. 3. In cytochalasin D treated group, no microfilament barrier was seen at the broad base of protrusion which exhibit direct continuity with the internal cytoplasm. 4. Single hepatocyte tend to recover their structural integrity as those in vivo. The new bile canaliculus was sealed off at the intercellular space by tight junctions, and intercellular contacts were established by the junctional complexes. The results demonstrated that excessive accumulation or depletion of microfilaments induced by phalloidin or cytochalasin D altered the cell shape different, respectively. The microfilaments of ectoplasm play an important role in the maintenance of the structural integrity of cultured hepatocytes.

THE RESPONSE TO CYTOCHALASIN D SEEN IN PRIMARY CULTURED CARDIOCYTES FROM ADULT HUMAN AND ADULT RAT / 解剖学报

10?m cytochalasin D (CD) was used to treat cardiocytes from adult human atrium and adult rat atrium and ventricle in long-term primary cultures. Durations of treatment were 0.5, 1, 6, 12, 24 and 48h. In some cultures, the medium containing CD was removed at the planned time to be replaced with the medium without CD.These dishes were then cultured for an additional 48h. Control cultures were exposed to dimethyl sulfoxide (DMSO), the vehicle used to dissolve CD. All cultured cells were first stained with rhodamine-labelled phalloidin to show F-actin and then stained with fluoreseein-labelled antitubulin to show microtubles. The freshly isolated and rounded cardiocytes did not respond to CD, while the spreading cells responded apparently. The actin filament bundles in the peripheral zone of spreading cells were cut into segments. Most segments were gathered into aggregates and granules. Some aggregates were lodged on the inner aspect of the sarcolemma. Small vacuoles were seen between the myofibrils or somewhere along the course of the myofibrils. The CD response from the atrial spreading cells, especially the human atrial spreading cells, were more obvious than that from the rat ventricular cells. Cells exposed to CD and then cultured in normal medium for 48h did not return to normal. Microtubules were not directly affected by CD, but in places where vacuolization occured they made way for vacuoles. All the control cultures made no response to DMSO. The above-mentioned results suggest that different sensitivity to CD existed in cultured adult cardiocytes between different species and that a difference also existed in the contractile machinery between the atrial culturing cells and ventricular cultureing cells of the same species.