Three dimensional typological studies using scanning electron microscopy for characterization of Termitomyces pellets obtained from submerged growth conditions

There are gaps in existing understanding of fungal pellet growth dynamics. We used scanning electron microscopy (SEM) for morphological characterization of the biomass organization of Termitomyces pellets for seven species: T. microcarpus (TMI1), T. albuminosus (TAL1, TAL2), T. striatus (TSTR), T. aurantiacus (TAUR), T. heimii (THE1, THE2), T. globulus (TGLO) and T. clypeatus (TCL1, TCL2, TCL3, TCL4, TCL5). We assessed the utility of SEM for morphological and structural characterization of Termitomyces spp. in three dimensional (3D) pellet form to identify ideal pellet morphology for industrial use. Typological classification of Termitomyces species was based on furrows, isotropy, total motifs and fractal dimensions. The pellets formed were entangled and exhibited highly compacted mycelial mass with microheterogeneity and microporosity. The mean density of furrows of Termitomyces species was between 10,000 and 11,300 cm/cm², percentage isotropy was 30?80 and total motifs varied from 300 to 2500. TGLO exhibited the highest furrow mean density, 11243 cm/cm², which indicated a compact, cerebroid structure with complex ridges and furrows, whereas TAL2 exhibited the lowest furrow density. TMI1a exhibited a high percentage isotropic value, 74.6, TSTR exhibited the lowest, 30.9. Total motif number also was used as a typological classification parameter. Fractal values were 2.64?2.78 for various submerged conditions of Termitomyces species. TAL1 exhibited the highest fractal dimension and TAL2 the lowest, which indicates the complexity of branching patterns. Three-dimensional SEM image analysis can provide insight into pellet micromorphology and is a powerful tool for exploring topographical details of pellets.     

Sea urchin Hox genes: insights into the ancestral Hox cluster

We describe the Hox cluster in the radially symmetric sea urchin and compare our findings to what is known from clusters in bilaterally symmetric animals. Several Hox genes from the direct-developing sea urchin Heliocidaris erythrogramma are described. CHEF gel analysis shows that the Hox genes are clustered on a < or = 300 kilobase (kb) fragment of DNA, and only a single cluster is present, as in lower chordates and other nonvertebrate metazoans. Phylogenetic analyses of sea urchin, amphioxus, Drosophila, and selected vertebrate Hox genes confirm that the H. erythrogramma genes, and others previously cloned from other sea urchins, belong to anterior, central, and posterior groups. Despite their radial body plan and lack of cephalization, echinoderms retain at least one of the anterior group Hox genes, an orthologue of Hox3. The structure of the echinoderm Hox cluster suggests that the ancestral deuterostome had a Hox cluster more similar to the current chordate cluster than was expected Sea urchins have at least three Abd-B type genes, suggesting that Abd-B expansion began before the radiation of deuterostomes.      

Staphylococcus haemolyticus. Bacterial resistance to teicoplanin and associated morpho-structural aspects

To improve our understanding of the bases of teicoplanin resistance we studied a "one-step" mutant of S. haemolyticus from a morphological point of view. The results show that the organization of peptidoglycan is altered in the resistant S. haemolyticus strain. It is suggested that the alterations, including the spongier cell wall structure, may prevent the teicoplanin from reaching its target.     

Taurolithocholate-induced inhibition of biliary lipid and protein excretion in the rat.

Taurolithocholate (TLC), a natural bile salt, induces selective impairment on canalicular membrane of the hepatocyte, which seems to be a major determinant of its cholestatic effect in experimental animals. In order to extend existing studies about the effects of TLC on bile secretion, we examined in TLC-treated rats the biliary excretion of compounds that are transported to canalicular membrane via vesicles, such as lipids and proteins. The single intravenous injection of TLC (3 mumol/100 g body wt.) inhibited transiently the biliary bile salt excretion, while the biliary excretion of lipids (i.e., cholesterol and phospholipids) and proteins remained inhibited even though the biliary excretion and composition of bile salts were normalized. Under such a condition, TLC also inhibited the transcellular vesicular pathway to the exogenous protein horseradish peroxidase entry into bile, without altering the paracellular biliary access of the protein. The hepatic uptake of horseradish peroxidase was unaffected by TLC-treatment. The results indicate that TLC can inhibit the biliary excretion of compounds that reach the canaliculus via a vesicular pathway, such as lipids and proteins, by a mechanism not related to a defective bile salt excretion. Possible explanations for these findings are discussed.     

Selective inhibitory effects of experimental potassium depletion on urinary excretion of prostanoids and their possible functional significance

The urinary concentrations of prostaglandins(PG) E2, 6-keto-PGF1 alpha (6KPGF) and thromboxane (Tx) B2 were measured by RIA method during both hypotonic polyuria (oral water load) and subsequent antidiuresis (low-dose infusion of lysine-8-vasopressin). The study was performed on healthy women either in normal potassium balance (N, n = 14) or sustained potassium depletion (D3, n = 6). Potassium depletion (KD) was induced by low potassium dietary intake (less than or equal to 10 mmol/d) and natriuretic treatment over a period of 8 days; the net losses of NaCl and H2O were replaced; the cumulative potassium deficit was 198 +/- 22 mmol. Further studies were performed after indomethacin treatment in both experimental conditions. 1) As compared to normal potassium balance in KD group the urinary prostanoid excretions were reduced even in absence of significant differences in urinary flow rate. The urinary excretion of 6KPGF was more impaired than that of TxB2 in both polyuria and antidiuresis. 2) Indomethacin inhibited the urinary prostanoid excretions in normal potassium balance and KD groups. The urinary excretion of PGE2 was more impaired than that of both 6KPGF and TxB2.     

Pre-eclampsia onset and SPARC: A possible involvement in placenta development

Pre-eclampsia (PE) is a multisystem disorder commonly diagnosed in the latter half of pregnancy and it is a leading cause of intrauterine fetal growth retardation (IUGR). The aim of this study was to investigate the localization and the role of SPARC, secreted protein acidic, and rich in cysteine, in PE and PE–IUGR placentas in comparison with normal placentas. SPARC was mainly expressed in the villous and extravillous cytotrophoblastic cells in first trimester, whereas in PE, PE–IUGR and at term placentas, SPARC immunostaining was visible in both cytotrophoblastic cells and syncytiotrophoblast. SPARC expression significantly decreased in normal placenta from first to third trimester and a further significant reduction was demonstrated in PE and PE–IUGR. The latter downregulation of SPARC depends on hypoxic condition as shown by in vitro models. In conclusion, SPARC can play a pivotal role in PE and PE–IUGR onset and it should be considered as a key molecule for future investigations in such pathologies.     

Morphology of the oral disc of Bufo bufo (Salientia: Bufonidae) tadpoles

The fully developed oral disc of the tadpole of Bufo bufo consists of dorsal and ventral labia bearing, respectively, two and three ridges bearing numerous horny denticles, a horny beak provided with jaw sheath serrations, and large lateral papillae that are borne by two cutaneous plicae. As development progresses toward metamorphosis, these structures gradually regress until they disappear. Each cusped clavate labial denticle adheres, by means of a thin peduncle, to a similar labial denticle fixed in the lip and formed by a group of three or four cells that keratinize gradually and thus present remarkable differences in their morphology. Once all the cells of a group have been converted into horny tissue, the denticle sheds and is replaced by the underlying one. The beak serrations also are horny structures; each consists of a columnar band of cells which undergoes a gradual keratinization. The horny cells that detach themselves at intervals, being replaced by those of the underlying anlagen. The labial denticles and the beak serrations keratinize in two distinct ways. In the former, the desmosomal filaments appear to play an important role whereas, in the latter, the keratin seems to be synthesized “ex novo” by the ribosomes.     

AKAP350 Is involved in the development of apical "canalicular" structures in hepatic cells HepG2

Hepatocytes are epithelial cells whose apical poles constitute the bile canaliculi. The establishment and maintenance of canalicular poles is a finely regulated process that dictates the efficiency of primary bile secretion. Protein kinase A (PKA) modulates this process at different levels. AKAP350 is an A-kinase anchoring protein that scaffolds protein complexes involved in modulating the dynamic structures of the Golgi apparatus and microtubule cytoskeleton, facilitating microtubule nucleation at this organelle. In this study, we evaluated whether AKAP350 is involved in the development of bile canaliculi-like structures in hepatocyte derived HepG2 cells. We found that AKAP350 recruits PKA to the centrosomes and Golgi apparatus in HepG2 cells. De-localization of AKAP350 from these organelles led to reduced apical cell polarization. A decrease in AKAP350 expression inhibited the formation of canalicular structures and impaired F-actin organization at canalicular poles. Furthermore, loss of AKAP350 expression led to diminished polarized expression of the p-glycoprotein (MDR1/ABCB1) at the apical "canalicular" membrane. AKAP350 knock down effects on canalicular structures formation and actin organization could be mimicked by inhibition of Golgi microtubule nucleation by depletion of CLIP associated proteins (CLASPs). Our data reveal that AKAP350 participates in mechanisms which determine the development of canalicular structures as well as accurate canalicular expression of distinct proteins and actin organization, and provide evidence on the involvement of Golgi microtubule nucleation in hepatocyte apical polarization.