Study of the influence of plasmids on the arbitrary primer polymerase chain reaction fingerprint of Escherichia coli strains

Abstract To study the effect of plasmids on the arbitrary primer-polymerase chain reaction fingerprint of bacterial strains, the Escherichia coli strains DH5, Top10, and W3110 were transformed with plasmids of different sizes: respectively, pUC19, pCEP and two clinically important plasmids carrying resistance to several antibiotics. Total DNA, i.e. both chromosomal and plasmid DNA, was prepared from transformed cells by boiling the cell suspensions and by phenol-chloroform extraction; chromosomal DNA was prepared by the same methods from the non-transformed, plasmid-free strains; plasmid DNA of pUC19 was purchased; plasmid DNA of pCEP was purified from the transformed strains by caesium chloride density gradient centrifugation. Arbitrarily primed polymerase chain reaction was carried out for all of these preparations. Amplification carried out independently with three different primers resulted in similar patterns for the chromosomal preparations whether or not plasmid was present. Amplification of plasmid DNA gave different patterns, characterized by fragments larger than those obtained when total or chromosomal DNA were used as the target. These data illustrate that the plasmids studied here do not influence the chromosomal arbitrarily primed PCR fingerprint, although plasmids alone are amplified in the absence of chromosomal DNA. Experiments comparing different relative concentrations of plasmid and chromosomal DNA indicate that under natural conditions the amount of chromosomal DNA per cell is sufficient to inhibit observable amplification of the plasmid(s) present.     

Cephalopod neural networks

Cephalopods have arguably the largest and most complex nervous systems amongst the invertebrates; but despite the squid giant axon being one of the best studied nerve cells in neuroscience, and the availability of superb information on the morphology of some cephalopod brains, there is surprisingly little known about the operation of the neural networks that underlie the sophisticated range of behaviour these animals display. This review focuses on a few of the best studied neural networks: the giant fiber system, the chromatophore system, the statocyst system, the visual system and the learning and memory system, with a view to summarizing our current knowledge and stimulating new studies, particularly on the activities of identified central neurons, to provide a more complete understanding of networks within the cephalopod nervous system.     

Evaluation of three essential oils as potential sources of botanical fungicides

In previous study, thirty essential oils were evaluated in vitro against two citrus pathogens namely Penicillium italicum Wehmer and Penicillium digitatum Sacc. Essential oils of Cinnamomum zeylanicum, Cinnamomum verum and Eugenia caryophyllus were selected because of their high inhibitory activities against both pathogens. The present study was undertaken to evaluate the in vivo activity of these essential oils. Fresh orange fruits were wounded and treated with different concentrations of essential oil (0.5, 1, and 5%) before being infected at the wound site with conidia suspensions of the tested pathogens. When applied at 5%, essential oils tested controlled totally the infections. Among the three essential oils tested, C. zeylanicum seems particularly interesting because of its high protection activity at 1% compare to the others. It reduced the disease incidence from 40 to 70% and the disease severity from 65 to 82%. Moreover no visible damage burn induced on the orange cuticle or skin was observed up to 5% of essential oil. These results strengthen the potential use of essential oils in postharvest disease management of citrus fruit as alternative to chemical fungicides.     

Functional and ultrastructural changes in Pseudomonas aeruginosa and Staphylococcus aureus cells induced by Cinnamomum verum essential oil

Aims: To study cellular damage induced by Cinnamomum verum essential oil in Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 29213. Methods and Results: The effect of cinnamon bark essential oil on these two strains was evaluated by plate counts, potassium leakage, flow cytometry and transmission electron microscopy (TEM). Exposure to this oil induced alterations in the bacterial membrane of Ps. aeruginosa, which led to the collapse of membrane potential, as demonstrated by bis‐oxonol staining, and loss of membrane‐selective permeability, as indicated by efflux of K⁺ and propidium iodide accumulation. Thus, respiratory activity was inhibited, leading to cell death. In Staph. aureus, cells treated with the oil entered a viable but noncultivable (VNC) state. The oil initially caused a considerable decrease in the metabolic activity and in the replication capacity of these bacterial cells. The loss of membrane integrity appeared later, as indicated by bis‐oxonol and Propidium iodide (PI) staining. Data provided by TEM showed various structural effects in response to cinnamon essential oil. In Ps. aeruginosa cells, coagulated cytoplasmic material was observed, and intracellular material was seen in the surrounding environment, while oil‐treated Staph. aureus showed fibres extending from the cell surface. Conclusions: Cinnamon essential oil damages the cellular membrane of Ps. aeruginosa, which leads to cell death. There is evidence of VNC Staph. aureus after exposure to the oil. Significance and Impact of the Study: Cinnamon essential oil shows effective antimicrobial activity and health benefits and is therefore considered a potential food additive. To use this oil as a natural food preservative, especially in combination with other preservation methods, a thorough understanding of the mechanism through which this oil exerts its antibacterial action is required.     

Multiregional Periodic Matrix for Modeling the Population Dynamics of Sardine (<Emphasis Type="Italic">Sardina pilchardus</Emphasis>) Along the Moroccan Atlantic Coast: Management Elements for Fisheries

In this paper, we present a deterministic time discrete mathematical model based on multiregional periodic matrices to describe the dynamics of Sardina pilchardus in the Central Atlantic area of the Moroccan coast. This model deals with two stages (immature and mature) and three spatial zones where sardines are supposed to migrate from one zone to another. The population dynamics is described by an autonomous recurrence equation N(t + 1) = A.N(t), where A is a positive matrix whose entries are estimated using data collected during biannual acoustic surveys carried out from 2001 to 2003 onboard the Norwegian research vessel “Dr Fridtjof Nansen”. The dominant eigenvalue λ of A that gives the long-term growth rate of fish population is smaller than one. This agrees with the stock decrease observed in the data collected. We show that λ is highly sensitive to the recruitment rate and much less sensitive to the reproduction rate. These results can clearly be used to define an efficient scenario in order to fight for instance against a stock decrease.     

Dynamics of a disabled population in Morocco

Background  

The disabled population constitutes a class of people needing special care and necessitating important economic and social effort.     

Effects of the microbial secondary metabolites pyrrolnitrin, phenazine and patulin on INS-1 rat pancreatic β-cells

The effects on pancreatic β-cell viability and function of three microbial secondary metabolites pyrrolnitrin, phenazine and patulin were investigated, using the rat clonal pancreatic β-cell line, INS-1. Cells were exposed to 10-fold serial dilutions (range 0-10 μg mL(-1)) of the purified compounds for 2, 24 and 72 h. After 2 h exposure, only patulin (10 μg mL(-1)) was cytotoxic. All compounds showed significant cytotoxicity after 24 h. None of the compounds altered insulin secretion with 2 and 20 mM glucose after 2 h. However, after 24 h treatment, phenazine and pyrrolnitrin (10 and 100 ng mL(-1)) potentiated insulin production and glucose-stimulated insulin secretion, whereas patulin had no effect. Exposure (24 h) to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 ng mL(-1)) caused similar increases in the Ca(2+) content of INS-1 cells. The outward membrane current was inhibited after 24 h exposure to either phenazine (100 ng mL(-1)) or pyrrolnitrin (10 or 100 ng mL(-1)). This study presents novel data suggesting that high concentrations of pyrrolnitrin and phenazine are cytotoxic to pancreatic β-cells and thus possibly diabetogenic, whereas at lower concentrations these agents are nontoxic and may be insulinotropic. The possible role of such agents in the development of cystic fibrosis-related diabetes is discussed.     

Evolution of rural-urban health gaps in Morocco: 1992-2011

ABSTRACT: BACKGROUND: Moroccan authorities carry out regular surveys on population and family health (NSFFP 1980, NSPH 1992, SPFH 2004, NSPFH 2011). These surveys constitute valuable resources for monitoring socio-economic and health indicators. They provide an evidence base for health decision makers to help them to optimize health strategies in order to improve the health conditions of the whole population. They also provide updated measures on geographic disparities, socio-economic inequalities and health inequity. The most recent Moroccan population and family health survey (NSPFH 2011) was carried out between November 2010 and March 2011. The final report and the database are not yet accessible, but a preliminary report was released early March 2012. This report does not allow for a complete evaluation of the present health situation in Morocco. A partial equity analysis can, however, be devoted to the comparison of health indicators especially in terms of rural-urban gaps. RESULTS: The 2011 survey shows that Moroccan population is in the last phase of the demographic transition. The total fertility rate decreased from 5.6 children per woman in 1980 to 2.5 per woman in 2011. The mean age of first marriage increased from 24 years for men and 17.5 years for women in 1960 to 31.5 years and 26.3 years in 2011 for men and women, respectively. The age structure shows a trend of ageing population. A comparison with the 1992 NSPH indicates that adult illiteracy has decreased from 53% in 1992 to 37.6% in 2011. During the same time period, women's access to maternal care and health services improved significantly. For instance, the proportion of deliveries assisted by skilled health personnel increased from 31% in 1992 to 73.6% in 2011. Between 1992 and 2011, neonatal, postnatal, infant and under-five mortality rates were reduced by 44%, 65%, 54% and 64%, respectively. CONCLUSION: This paper shows that average health indicators improved noticeably during the last two decades but rural-urban disparities are still a challenge for health decision makers. Socio-economic indicators, like illiteracy rate and unemployment, also demonstrate large gender inequalities. This preliminary analysis is designed to assist Moroccan health authorities to evaluate the current health situation in order to adopt cost-effective strategies that improve "health for all" and reduce the gaps between advantaged and disadvantaged populations.     

Taxus sp. cell, tissue and organ cultures as alternative sources for taxoids production: a literature survey

The literature concerning the tissue culture of Taxus sp. as an alternative source for taxoid production is reviewed. The aim of this review is to summarize and discuss the progress achieved with the approaches and methods used for the establishment of various Taxus culture systems, the methods used for the evaluation of taxoid production, the multiple factors which control taxoid production and the feasibility of the in vitro production of taxoids on a commercial scale.     

Comparison of bacteriostatic and bactericidal activity of 13 essential oils against strains with varying sensitivity to antibiotics

Aims:  To compare the bacteriostatic and bactericidal activity of 13 chemotyped essential oils (EO) on 65 bacteria with varying sensitivity to antibiotics.
Methods and Results:  Fifty-five bacterial strains were tested with two methods used for evaluation of antimicrobial activity (CLSI recommendations): the agar dilution method and the time-killing curve method. EO containing aldehydes ( Cinnamomum verum bark and Cymbopogon citratus ), phenols ( Origanum compactum , Trachyspermum ammi , Thymus satureioides , Eugenia caryophyllus and Cinnamomum verum leaf) showed the highest antimicrobial activity with minimum inhibitory concentration (MIC) <2% (v/v) against all strains except Pseudomonas aeruginosa . Alcohol-based EO ( Melaleuca alternifolia , Cymbopogon martinii and Lavandula angustifolia ) exhibited varying degrees of activity depending on Gram status. EO containing 1·8-cineole and hydrocarbons ( Eucalyptus globulus , Melaleuca cajeputii and Citrus sinensis ) had MIC_90% ≥ 10% (v/v). Against P. aeruginosa , only C. verum bark and O. compactum presented MIC ≤2% (v/v). Cinnamomum verum bark, O. compactum , T. satureioides , C. verum leaf and M. alternifolia were bactericidal against Staphylococcus aureus and Escherichia coli at concentrations ranging from to 0·31% to 10% (v/v) after 1 h of contact. Cinnamomum verum bark and O. compactum were bactericidal against P. aeruginosa within 5 min at concentrations <2% (v/v).
Conclusions:  Cinnamomum verum bark had the highest antimicrobial activity, particularly against resistant strains.
Significance and Impact of the Study:  Bacteriostatic and bactericidal activity of EO on nosocomial antibiotic-resistant strains.