Isolation of early genes expressed in reproductive organs of the dioecious white campion (Silene latifolia) by subtraction cloning using an asexual mutant

The dioecious white campion (Silene latifolia) has been chosen as a working model for sexual development. In this species, sexual dimorphism is achieved through two distinct developmental blocks: inhibition of carpel development in male flowers, and early arrest of anther differentiation in female flowers. The combined advantages of the dioecious system and the availability of a sexual mutant lacking both male and female reproductive organs have been exploited in a molecular subtraction approach using male and asexual flower buds. This resulted in the cloning of 22 cDNA clones expressed in stamens at distinct stages of development. Fourteen of these clones corresponded to genes whose expression was detected in pre-meiotic stamens, a stage of development for which very little information is presently available. Furthermore, the absence of similarities with database sequences for ten clones suggests that they represent novel genes. Functional analysis of each clone will enable their positioning within the reproductive organ developmental pathway(s). In parallel, these clones are being exploited as developmental markers of early differentiation within the flower.     

Methyl-4 formyl-7 cyclopenta(c)pyranne isole apres hydrolyse acide de Viburnum tinus

Viburtinal (4-methyl-7-formylcyclopenta(c)pyrane), yet unknown, was obtained by acid hydrolysis of the esters extracted from Viburnum tinus. Its structure was deduced by spectroscopic methods.     

Potent and specific blockade by AH 22216 of histamine-H2-receptor-mediated acid secretion in isolated rabbit gastric cells

AH 22216 is a new histamine-H₂-receptor antagonist which possesses a triazole ring. When compared to cimetidine, AH 22216 is about 100 times more potent (Ki = 0.21×10^–8 M) in inhibiting histamine-stimulated acid secretion in isolated rabbit gastric cells. These two antihistamines have no effect on carbachol-stimulated acid secretion in the system. The data indicate that AH 22216 interacts directly and specifically on the gastric H₂-receptor of the parietal cell and are consistent with the reported pharmacological potencies of AH 22216 and cimetidine on histamine-induced gastric-acid secretion in vivo. AH 22216 could thus be a useful therapeutic agent in patients with peptic ulcers.     

v-myb Transformation of Xeroderma pigmentosum human fibroblasts: Overexpression of the c-Ha-ras oncogene in the transformed cells

Human Xeroderma pigmentosum “normal” fibroblasts AS16 (XP4 VI) were transformed after transfection with a recombinant v-myb clone. In this clone (pKXA 3457) derived from avian myeloblastosis virus (AMV), the expression of the oncogene sequences is driven by the AMV U-5 LTR promoter. The transformed cells (ASKXA), which have integrated a rearranged v-myb oncogene, grow in agar, are not tumorigenic in nude mice, and express a 45-kDa v-myb protein. The HMW DNA of these cells transform chicken embryo fibroblasts. The c-Ha-ras oncogene is overexpressed in the ASKXA cells but not in the parental “normal” AS16 cells and a revertant clone (ASKXA Cl 1.1 G). Our results lead to the conclusion that the XP fibroblasts are phenotipically transformed by the presence of the transfected v-myb oncogene, which is able to induce an overexpression of the c-Ha-ras gene.     

Specific and sensitive quantitation of 2,2′-dichlorodiethyl sulphide (sulphur mustard) in water, plasma and blood: application to toxicokinetic study in the rat after intravenous intoxication

A sensitive and specific capillary gas chromatographic method has been developed to measure trace amounts of 2,2′-dichlorodiethyl sulphide (sulphur mustard) in environmental or biological samples. Sulphur mustard was isolated from water or plasma by a solid-phase extraction procedure and from blood by liquid—liquid extraction. The accuracy and precision of the methods were demonstrated using replicate analyses of spiked water, plasma or blood: within-run and between-run variabilities were less than 20%. These analytical methods were used to evaluate the rate of sulphur mustard degradation in water or plasma. Good linear calibration curves, with a detection limit of 45 ng/ml, were obtained for quantitation and determination of sulphur mustard in blood following its intravenous administration to rats. Initial toxicokinetic data were obtained.     

All-or-none control of the bursting properties of the pacemaker neurons of the labster pyloric pattern generator

In Crustacea the central pattern generator for the pyloric motor rhythm (filtration to the midgut) is known to be located within the stomatogastric ganglion (STG); its cycling activity is known to be organized by three endogenous burster neurons acting as pacemakers and driving 11 follower neurons. In Homarus, recordings from the isolated stomatogastric nervous system (Fig. 1) indicate that (1) the pyloric output can be generated only when the STG is afferented (i.e., connected to the more rostral oesophageal and commissural ganglia) (Fig. 2) and (2) the deafferntation of the STG results in a complete loss of the bursting properties of the pacemaker neurons (Fig. 4). Manipulation of the STG inputs responsible for unmasking the properties of the pacemakers strongly suggests that (1) they are not phasic inputs (Fig. 5) and (2) they are long-term acting inputs (Fig. 6). These results provide evidence for a neural all-or-none control of the bursting properties of the pacemaker neurons of a motor pattern generator.     

Gene silencing with RNA interference in the human pathogenic fungus Aspergillus fumigatus

Aspergillus fumigatus is an opportunistic pathogenic fungus which causes fatal invasive aspergillosis among immunocompromised patients. To obtain a better understanding of the key elements involved in A. fumigatus virulence and to identify possible drug targets, it is necessary to be able to generate gene-deletion strains. Unfortunately, the molecular techniques available do not include a rapid method to disrupt and identify essential genes. RNA interference, a process in which the presence of double-stranded RNA homologous to a gene of interest results in specific degradation of the corresponding message, has been successfully tested on A. fumigatus. We have shown that expression of double stranded RNA corresponding to portions of the ALB1/PKSP and FKS1 genes results in reduced mRNA levels for those genes, with phenotypic consequences similar to that of gene disruption. The two genes could also be subjected to simultaneous interference through expression of chimeric double-stranded RNA. Use of RNA interference in Aspergillus will allow easier examination of the phenotypic consequences of reducing expression of a gene of interest, especially for essential genes.