Local and regional drivers of the African coffee white stem borer (Monochamus leuconotus) in Uganda

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Relationships between transposable elements based upon the integrase-transposase domains: Is there a common ancestor?

The integrase domain of RNA-mediated elements (class I) and the transposase domain of DNA-mediated transposable elements (class II) were compared. A number of elements contain the DDE signature, which plays an important role in their integration. The possible relationships between mariner-Tc1 and IS elements, retrotransposons, and retroviruses were analyzed from an alignment of this region. The mariner-Tc1 superfamily, and LTR retrotransposons and retroviruses were found to be monophyletic groups. However, the IS elements of bacteria were found in several groups. These results were used to propose an evolutionary history that suggests a common ancestor for some integrases and transposases. Received: 3 July 1995 / Accepted: 9 October 1995     

Enhanced stability of carboxypeptidase from Sulfolobus solfataricus at high pressure

Carboxypeptidase from the archaebacterium Sulfolobus solfataricus is heat stable with an optimal enzyme activity at 85 °C (Colombo et al., 1992). However in the absence of glycerol and beta-mercaptoethanol, at 50 °C, the enzyme undergoes a slow thermal inactivation upon dilution in an aqueous buffer at pH 6.5. This loss of activity can be inhibited when the enzyme is maintained at high pressure. At higher temperatures, higher pressures (up to 400 MPa) are required to maintain the enzyme in its active state.Dedicated to Dr. Andrea Villa, who deceased accidentally in the course of this work.     

Furoquinoline alkaloid accumulation in Fagara zanthoxyloides cell cultures is highly dependent on the presence of exogenous benzylaminopurine

Culturing a non-habituated cell line of Fagara zanthoxyloides Lam. (Rutaceae) in either auxin-free medium or cytokinin-free medium led to opposite effects on furoquinoline accumulation. It appeared that production of skimmianine and -fagarine in the cells was strongly correlated with the presence of exogenous BAP: the levels of both alkaloids were 9 times lower when cells were cultured without cytokinin than in the control culture. NAA removal induced a slight stimulation of skimmianine and -fagarine accumulations, 1.2 and 1.9 times respectively. Culturing the cells in a PGR-free medium generated skimmianine and -fagarine levels that were 3.5 and 2.1 times lower, respectively, confirming the opposite effects of BAP and NAA on furoquinoline accumulation. Growth was only slightly inhibited when cells were cultured for one passage in the PGR-modified media.Abbreviations BAP 6-benzylaminopurine - MS Murashige-Skoog - NAA -naphtaleneacetic acid - PGR plant growth regulator     

Synthesis and conformational analysis of AzAsx-containing oligopeptides

Summary For the sake of improving synthetic methods and evaluating the conformational perturbation induced by the substitution of AzAsx for the Asx residue in the cognate dipeptide R-CO-Asx-Pro-NHR, we prepared the AzAsx-dipeptide sequence by making use of the crystalline triphosgene. This reagent allows, in situ and under very mild experimental conditions, both the carbonylation and the activation of the properly substituted and N-protected hydrazine before coupling with the proline partner. With regard to conformational behaviour, the azadipeptide sequence displays a -fold, unlike the cognate dipeptide which adopts an Asx-turn.     

Micronutrient composition of xylem sap and needles as a result of P-fertilization in maritime pine

Xylem sap and foliar compositions (P, Cu, Zn, Mn) were examined over 4 months in control and P-fertilized maritime pine in a 7-year-old plantation. The absorption of copper, zinc, and boron appears to be reduced by phosphate fertilization. Manganese concentrations are positively related to P-supply increase. Foliar analysis and sap provides the same type of information in terms of antagonism or synergism between elements but the response to treatment is more often significant with sap throughout the seasons and is completely non-existent on a single classical autumn diagnosis with foliar concentration (i.e. Zn and Cu). In consequence foliar analysis is not sensitive enough for copper or zinc deficiency diagnoses in young plantations where nutritional growth disorders appear in a short period of spring, and xylem chemistry appears to be a convenient tool in monitoring micronutrient disorders in pine plantations.     

Treatment of PC12 cells by nerve growth factor,dexamethasone, and forskolin

Several lines of anatomical, neurochemical, electrophysiological, and behavioral evidence suggest the existence of physiological interactions between neurotensin (NT) and the brain dopaminergic systems. Thus, NT has been shown to exert a neuroleptic-like action and could be implicated in the pathogenesis and treatment of schizophrenia. It is thus of particular importance to develop in vitro cell culture systems as models to study such interactions. Rat adrenal pheochromocytoma PC12 cells, which expressed high levels of tyrosine hydroxylase, were used in the present study. In contrast to rat brain cells in primary cultures, PC12 cells did not express functional NT receptors. However, they were able to express both NTmRNA and NT in response to NGF, forskolin, and dexamethasone. Those neurochemical modifications furthermore may be related to changes in the morphology of the PC12 cells in response to NGF, forskolin, and dexamethasone alone or in combination. These data suggest that PC12 cells may provide a useful model to study in vitro the regulation of both catecholamine and neurotensin phenotypes.     

Genetic analysis of new French X-linked juvenile retinoschisis kindreds using microsatellite markers closely linked to the RS locus: further narrowing of the RS candidate region

The gene involved in juvenile retinoschisis (RS) has previously been localized, by genetic linkage analyses, to Xp22.1-p22.2, between DXS274 and DXS43/ DXS207; it is closely linked to the latter markers. From our recent data, this interval represents a genetic distance of approximately 10 cM. In the present study, we have studied 14 French families with X-linked juvenile RS by using four CA polymorphisms that are closely linked to the RS locus and that have recently been included in an Xp22.1-p22.2 high-resolution map. Complete cosegregation with the disease locus was observed for three of them, DXS207, DXS418, and DXS999, which further confirms the locus homogeneity for RS and the close linkage to this region. One recombinant was found with the most proximal marker, AFM291wf5, thereby defining this marker as the new proximal boundary of the candidate region for RS. Under the assumption that DXS207 and DXS43 constitute the distal boundary, the present study further reduces the region containing the disease gene to a interval of 3–4 cM. The results reported here should facilitate the eventual cloning of the RS gene.     

Enhanced secretion through the Shigella flexneri Mxi-Spa translocon leads to assembly of extracellular proteins into macromolecular structures

Genes required for entry of Shigella flexneri into epithelial cells in vitro are clustered in two adjacent loci, one of which encodes secretory proteins, the IpaA–D proteins, and the other their dedicated secretion apparatus, the Mxi–Spa translocon. Ipa secretion, which is induced upon contact of bacteria with epithelial cells, is prevented during growth in vitro. Here, we show that ipaB and ipaD mutations lead to enhanced secretion of a set of about 15 proteins. These extracellular proteins and some Ipas associate in organized structures consisting of extended sheets. Growth of the wild-type strain in the presence of Congo red is shown to induce protein secretion through the Mxi–Spa translocon. Cultures grown to stationary phase in the presence of Congo red contain extracellular filaments whose composition and morphology are similar to those produced by the hyper-secreting ipaB and ipaD mutants.