Effect of titanium dioxide concentration on the survival of Pseudomonas stutzeri during irradiation with near ultraviolet light

Cells of Pseudomonas stutzeri in suspensions of TiO₂ ranging in concentration from 0.5 to 4.0 g l^-1 were irradiated with a blacklight blue u.v. source displaying peak emissivity at approximately 370 mm. Irradiation under these conditions is known to result in the generation of lethal free radicals. During irradiation the suspensions were agitated, using a specially modified laboratory shaker, to ensure efficient exposure of the TiO₂. A u.v. radiation dose of 175 kJ m^-2 resulted in cell fractional survival ranging from 5.5 times 10^-5, at the lowest TiO₂ concentration, to 1.0 times 10^-6, at the highest TiO₂ concentration. The advantages of contactors employing TiO₂ suspensions are briefly compared to immobilized TiO₂ systems.     

Large DNA inversions,deletions, and TaqI site mutations in severe haemophilia A

Large DNA inversions caused by an intrachromosomal recombination between homologous regions located in intron 22 and 5 of the factor VIII gene have recently been identified in patients with severe haemophilia A. To evaluate better the prevalence of this large inversion and to estimate the overall sensitivity of the Southern blot/hybridization method we analysed the factor VIII gene of 49 unrelated patients with severe haemophilia A. All patients were screened for the inversion mutation, TaqI site mutations, and deletions. Mutations were identified in 31 (63%) patients, and comprised 24 large inversions, 4 partial deletions, and 3 point mutations. Three different haplotypes were characterised in the patients presenting the inversion mutation, confirming its independent origin. Two novel deletions are reported: a large one spanning from intron 14 to intron 22 and a deletion of 86 bp comprising the 3 region of exon 1 and 39–41 bp of intron 1. DNA sequencing of the deletion junction showed no significant homology between normal 5 and 3 sequences around the breakpoints. A novel missense mutation is also reported: CGAGGA, Arg-2209 to Gly. These results confirm that the inversion mutation is the most common cause of severe haemophilia A and indicate that the Southern blot/hybridization assay should be used as the first method for screening of mutations in severe haemophilia A.     

Morphogenetic potential and in vitro micropropagation of endangered plant species Leucojum aestivum L. and Lilium rhodopaeum Delip.

Summary The present work deals with the in vitro methods for rapid propagation, and morphogenetic potential of the rare and endangered bulb species Leucojum aestivum L., Amaryllidaceae, and Lilium rhodopaeum Delip., Liliaceae. The morphogenetic potential of different plant organs (bulb, stem, leaves and ovaries) was studied. Leaves of Leucojum aestivum L. and basal parts of the bulb in Lilium rhodopaeum Delip. possess the highest regeneration activity. Murashige and Skoog (MS) medium + 1 mg/l 6-benzylaminopurine (BAP) + 1 mg/l kinetin and Linsmaier and Skoog (LS) medium + 0.5 mg/l 1-naphthaleneacetic acid (NAA) + 0.1 mg/l kinetin were favourable for direct organogenisis from these explants. A stimulating effect of alow gamma-irradiation dose (5 Gy) upon the quantity and growth intensity of the bulbs formed by the explants in in vitro conditions is observed.     

How does the G protein,Gi2, transduce mitogenic signals?

Serpentine receptors coupled to the heterotrimeric G protein, G_i2, are capable of stimulating DNA synthesis in a variety of cell types. A common feature of the G_i2-coupled stimulation of DNA synthesis is the activation of the mitogen-activated protein kinases (MAPKs). The regulation of MAPK activation by the G_i2-coupled thrombin and acetylcholine muscarinic M₂ receptors occurs by a sequential activation of a network of protein kinases. The MAPK kinase (MEK) which phosphorylates and activates MAPK is also activated by phosphorylation. MEK is phosphorylated and activated by either Raf or MEK kinase (MEKK). Thus, Raf and MEKK converge at MEK to regulate MAPK. G_i2-coupled receptors are capable of activating MEK and MAPK by Raf-dependent and Raf-independent mechanisms. Pertussis toxin catalyzed ADP-ribosylation of α_i2 inhibits both the Raf-dependent and-independent pathways activated by G_i2-coupled receptors. The Raf-dependent pathway involves Ras activation, while the Raf-independent activation of MEK and MAPK does not involve Ras. The Raf-independent activation of MEK and MAPK most likely involves the activation of MEKK. The vertebrate MEKK is homologous to the Ste11 and Byr2 protein kinases in the yeast Saccharomyces cerevisiae and Schizosaccharomyces pombe, respectively. The yeast Ste11 and Byr2 protein kinases are involved in signal transduction cascades initiated by pheromone receptors having a 7 membrane spanning serpentine structure coupled to G proteins. MEKK appears to be conserved in the regulation of G protein-coupled signal pathways in yeast and vertebrates. Raf represents a divergence in vertebrates from the yeast pheromone-responsive protein kinase system. Defining MEKK and Raf as a divergence in the MAPK regulatory network provides a mechanism for differential regulation of this system by G_i2-coupled receptors as well as other receptor systems, including the tyrosine kinases.     

Increased shikonin production by hairy roots of Lithospermum erythrorhizon in two phase bubble column reactor

Summary Plant hairy root cultures of Lithospermum erythrorhizon were carried out to produce shikonin derivatives by employing in situ extraction with n-hexadecane in a shake flask and a bubble column bioreactor. Over 95 % shikonin produced was recovered in the n-hexadecane layer. In flask cultures the maximum concentration of shikonin with n-hexadecane extraction was 3 times higher than that obtained without extraction. In the two phase bubble column reactor, 572.6 mg/L of shikonin and 15.6 g/L of dry cell mass were obtained after 54 days. Shikonin was produced at a constant level of 10.6 mg/L day during this period.     

Microbial transformation of sucrose and glucose to erythritol

Summary Two strains of osmophilic yeast which were isolated from honey-comb, produced good yields of erythritol as a main product. These strains were identified as Trichosporonoides sp., 150-5 and 331-1.From the fermentation studies with these strains using glucose and sucrose as substrate, strain 331-1 produced more erythritol as the sole polyhydric product,with trace quantities of glycerol, than strain 150-5.     

Studies on the Role of B-50 (GAP-43) in the Mechanism of Ca2+-Induced Noradrenaline Release: Lack of Involvement of Protein Kinase C After the Ca2+ Trigger

Abstract: The involvement of B-50, protein kinase C (PKC), and PKC-mediated B-50 phosphorylation in the mechanism of Ca²⁺-induced noradrenaline (NA) release was studied in highly purified rat cerebrocortical synaptosomes permeated with streptolysin-O. Under optimal permeation conditions, 12% of the total NA content (8.9 pmol of NA/mg of synaptosomal protein) was released in a largely (>60%) ATP-dependent manner as a result of an elevation of the free Ca²⁺ concentration from 10^?8 to 10^?5M Ca²⁺ The Ca²⁺ sensitivity in the micromolar range is identical for [³H]NA and endogenous NA release, indicating that Ca²⁺-induced [³H]NA release originates from vesicular pools in noradrenergic synaptosomes. Ca²⁺-induced NA release was inhibited by either N- or C-terminal-directed anti-B-50 antibodies, confirming a role of B-50 in the process of exocytosis. In addition, both anti-B-50 antibodies inhibited PKC-mediated B-50 phosphorylation with a similar difference in inhibitory potency as observed for NA release. However, in a number of experiments, evidence was obtained challenging a direct role of PKC and PKC-mediated B-50 phosphorylation in Ca²⁺-induced NA release. PKC pseudosubstrate PKC_19-36, which inhibited B-50 phosphorylation (IC₅₀ value, 10^?5M), failed to inhibit Ca²⁺-induced NA release, even when added before the Ca²⁺ trigger. Similar results were obtained with PKC inhibitor H-7, whereas polymyxin B inhibited B-50 phosphorylation as well as Ca²⁺-induced NA release. Concerning the Ca²⁺ sensitivity, we demonstrate that PKC-mediated B-50 phosphorylation is initiated at a slightly higher Ca²⁺ concentration than NA release. Moreover, phorbol ester-induced PKC down-regulation was not paralleled by a decrease in Ca²⁺-induced NA release from streptolysin-O-permeated synaptosomes. Finally, the Ca²⁺- and phorbol ester-induced NA release was found to be additive, suggesting that they stimulate release through different mechanisms. In summary, we show that B-50 is involved in Ca²⁺-induced NA release from streptolysin-O-permeated synaptosomes. Evidence is presented challenging a role of PKC-mediated B-50 phosphorylation in the mechanism of NA exocytosis after Ca²⁺ influx. An involvement of PKC or PKC-mediated B-50 phosphorylation before the Ca²⁺ trigger is not ruled out. We suggest that the degree of B-50 phosphorylation, rather than its phosphorylation after PKC activation itself, is important in the molecular cascade after the Ca²⁺ influx resulting in exocytosis of NA.     

THE CALCAREOUS RESTING CYST OF PENTAPHARSODINIUM TYRRHENICUM COMB. NOV. (DINOPHYCEAE)1

While investigating dinoflagellate cyst assemblages in surface sediments of the Gulfs of Naples and Salerno (Mediterranean Sea), we found a new calcareous resting cyst. This cyst has a round to oval body surrounded by a thick mineral layer, which gives it the shape of a Napoleon hat, with a flat, oval face bearing the archeopyle and a convex keel on the opposite side. The cyst shape is variable in both natural samples and clonal cultures. The organic membrane underlying the calcareous covering is resistant to acetolysis, thus demonstrating the presence of sporopolleninlike material. The cyst germinated into a motile stage having the same morphological features and thecal plate pattern as Peridinium tyrrhenicum Balech. We believe the validity of the genus Pentapharsodinium Indelicato & Loeblich should be accepted. Based on the comparative examination of the species we collected and of a similar species, Pentapharsodinium trachodium Indelicato & Loeblich, we propose Pentapharsodinium tyrrhenicum as a new combination for Peridinium tyrrhenicum. The genus Pentapharsodinium also includes P. dalei Indelicato & Loeblich (= Peridinium faeroense Dale), which produces spiny, organic-walled cysts. The presence of species forming calcareous cysts and species producing noncalcareous cysts in the same genus raises questions about maintaining the family Calciodinellaceae. This family should only include calcareous cyst-forming peridinioids, in order to maintain a unified system of classification of fossil and recent dinoflagellates.     

Linkage analysis of schizophrenia with five dopamine receptor genes in nine pedigrees

Alterations in dopamine neurotransmission have been strongly implicated in the pathogenesis of schizophrenia for nearly 2 decades. Recently, the genes for five dopamine receptors have been cloned and characterized, and genetic and physical map information has become available. Using these five loci as candidate genes, we have tested for genetic linkage to schizophrenia in nine multigenerational families which include multiple affected individuals. In addition to testing conservative disease models, we have used a neurophysiological indicator variable, the P50 auditory evoked response. Deficits in gating of the P50 response have been shown to segregate with schizophrenia in this sample and may identify carriers of gene(s) predisposing for schizophrenia. Linkage results were consistently negative, indicating that a defect at any of the actual receptor sites is unlikely to be a major contributor to schizophrenia in the nine families studied.