Crosslisted asset valuation in information asymmetry context : case of european companies crosslisted on Nasdaq

L’intercotation au Nasdaq est une bonne opportunité à l’entreprise européenne de se développer aux Etats-Unis et d’accéder à un marché liquide. Elargir sa base d’investisseurs, lever des fonds à un coût moindre pour réaliser de nouveaux projets et réduire les barrières géographiques et législatives, sont parmi les principaux avantages de l’intercotation. A travers un modèle théorique et une étude empirique sur un échantillon d’entreprises en provenance de pays européens et intercotées au Nasdaq, nous étudions l’impact de l’intercotation sur la performance des entreprises. D’un point de vue investisseur, le titre intercoté représente une opportunité de diversification et permet d’atténuer l’effet « home bias ». L’intercotation est une preuve de compétitivité de l’entreprise. La cotation au Nasdaq procure à l’entreprise plus de visibilité et lui permet d’attirer de nouveaux investisseurs. Les caractéristiques spécifiques à l’entreprise tels que la taille ou le secteur d’activité influencent les bénéfices de la l’intercotation.Cross-listing is a good opportunity for European firms to grow and to have access to a liquid market. Widening the investor base, raising funds at a lower cost to implement new projects and reducing geographical barriers and laws, are among the main advantages of cross-listing. Through a theoretical and an empirical study on a sample of firms from European countries and cross-listed on Nasdaq, we study the impact of cross-listing on corporate performance. For investors, the crosslisted securities represents a diversification opportunity and helps mitigate the home bias effect. The crosslisting provides the company greater visibility and allows it to attract new investors. The firm-specific characteristics such as size or industry influence the benefits of cross-listing

Secretion of cyclodextrin glucanotransferase in <i>E. coli</i> using <i>Bacillus subtilis</i> lipase signal peptide and optimization of culture medium

72-79The cyclodextrin glycosyltransferase (CGTase) of Paenibacillus pabuli US132 was fused to the secretive lipase signal peptide of B. subtilis. This leads to an efficient secretion of the recombinant enzyme into the culture medium of E. coli as an active and soluble form contrasting with the native construction leading to a periplasmic production. In order to enhance the yield of CGTase production, an experimental design methodology was applied for the optimization of the culture composition. Hence, the media components were submitted to preliminary screening using a Plakett-Burman design. The concentrations of the major operating ones were then optimized to enhance the secretion of CGTase using response surface methodology. The findings revealed that concentrations of 0.5% potato starch, 3% yeast extract, 3% tryptone, 1.5% casein hydrolysate, 0.5% NaCl, 0.2% KH2PO4, and 0.02% MgSO4 were the optimal conditions for CGTase production. The experimental value (9.43 U/ml) obtained for CGTase activity was very close to the predicted value (9.27 U/ml)

A New Endophytic Fusarium Oxysporum Gibberellic Acid: Optimization of Production Using Combined Strategies of Experimental Designs and Potency on Tomato Growth under Stress Condition

This study reports the potential of the endophytic fungi identified as a Fusarium oxysporum to produce gibberellic acid (GA3). The GA3 production was confirmed by high performance liquid chromatography. To improve the production of this phytohormone under solid state fermentation (SSF), successive optimization strategies were used. Firstly, Plackett-Burman design was applied for screening medium components and culture condition. Under the optimized condition, GA3 yield (7.14 g/kg) was 2.62-fold higher than by the use of the initial condition (2.72 g/kg). The concentration of the most influential parameters and their interaction were optimized with a Box-Behnken experimental design. The optimized condition led to a 1.14-fold enhancement in GA3 production, reaching 8.16 g/kg. The GA3 crude extract obtained by SSF was then used to study its ameliorative role on adverse salinity effect on tomato plants (Solanum lycopersicum L.). The interactive effects of different GA3 concentrations were examined on morphological and physiological parameters of tomato plants. The application of GA3 (10-6 M) under salt stress condition (100 mM) was found to improve growth and physiological parameters including plant height, total chlorophyll, starch, and proline contents. The exogenous application of GA3 is a potent strategy to reverse abiotic stress that affect the agricultural productivity and limit plant growth and yield

Overproduction of Glucose Oxidase by Aspergillus tubingensis CTM 507 Randomly Obtained Mutants and Study of Its Insecticidal Activity against Ephestia kuehniella

In order to enhance the production of glucose oxidase (GOD), random mutagenesis of Aspergillus tubingensis CTM 507 was performed using the chemical and physical mutagens: nitric acid and UV irradiation, respectively. The majority of the isolated mutants showed good GOD production, but only some mutants presented a significant overproduction, as compared with the parent strain. The selected mutants (19 strains), showing an overproduction larger than 200%, are quite stable after three successive subcultures. Among these, six strains revealed an important improvement in submerged fermentation. The insecticidal activity of GOD produced by the wild and the selected mutant strains was evaluated against the third larval instars of E. kuehniella. Mutant strains U11, U12, U20, and U21, presenting the most important effect, displayed an LC50 value of 89.00, 88.51, 80.00, and 86.00 U/cm2, respectively, which was 1.5-fold more important than the wild strain (61 U/cm2). According to histopathology observations, the GOD enzyme showed approximately similar damage on the E. kuehniella midgut including rupture and disintegration of the epithelial layer and cellular vacuolization. The data supports, for the first time, the use of GOD as a pest control agent against E. kuehniella

Genetic diversity assessment of Tunisian Mycobacterium bovis population isolated from cattle

Abstract Background The genetic diversity of M. bovis in Tunisia is still underestimated despite the implementation of an eradication program. The lack of data about spatial distribution of the M. bovis population hinders the control of bovine tuberculosis (bTB) progress. This study represents the largest molecular analysis of M. bovis isolates in Tunisia. It is aimed to upgrade the understanding of bTB epidemiology and the geographical distribution of the infection. Tuberculosis research was performed in cattle (n = 149) with TB-compatible lesions collected over 5 months from a slaughterhouse located in Sfax, Tunisia. Results Ninety-four animals were found to be infected by M. bovis and two others by M. caprae. Spoligotyping revealed twenty-five patterns, SB0120, SB0134, and SB0121 being the most prevalent profiles (36.4%, 11.4%, and 7.2%, respectively). Three new spoligotypes were detected: SB2345, SB2344 and SB2343. MIRU-VNTR analysis classified the isolates in seventy-three profiles and showed a large genotypic variety observed within the main spoligotype which was split into several MIRU-VNTR types: 29 in SB0120 (h = 0.983), 10 in SB0134 (h = 0.981) and 7 in SB0121 (h = 1). Genotyping revealed a common pattern in different geographic regions. It also showed that Sfax, located in southern-Tunisia, represents a high-risk area with an elevated genetic diversity. Conclusions Spatial analysis may provide insights into disease transmission, which affects the effectiveness of eradication campaigns in cattle

Screening and Detecting Salmonella in Different Food Matrices in Southern Tunisia Using a Combined Enrichment/Real-Time PCR Method: Correlation with Conventional Culture Method

A combined enrichment/ newly developed invA TaqMan® real-time PCR (qPCR) method as a screening assay to detect Salmonella spp. in 500 naturally food matrices is evaluated. DNA template for qPCR was extracted from an overnight pre-enriched sample in buffered peptone water using lysis–guanidine isothiocyanate method. Heterologous internal amplification control (IAC) was incorporated during qPCR assays and co-amplified with the invA gene of the target pathogen. InvA qPCR exhibited 100% specificity when testing 94 Salmonella strains (inclusivity) and 32 non-Salmonella strains (exclusivity). The qPCR showed a consistent detection of two copies of the invA gene/PCR reaction, a good intra- and inter-run reproducibility with a good PCR efficiency (89.6%). QPCR was sensitive and showed Salmonella detection at 8.5 × 100 CFU mL-1 of artificially spiked poultry meat -BWP solution in less than 40 cycles. When analyzing 500 different food matrices and comparing the results with the ISO 6579:2002 conventional culture method, the sensitivity and specificity were 100 and 76.6%, respectively. QPCR showed Salmonella spp. DNA in raw poultry meat 27/45 (60%), milk 31/93 (33.3%), raw red meat 5/13 (38.5%), and fish 11/46 (23.9%) samples. The prevalence of Salmonella spp. in cakes, dairy, cooked meals, charcuterie products using qPCR was 11/14 (26.8%), 5/22 (22.7%), 32/150 (21.3%), and 5/20 (25%), respectively, compared to 0% as demonstrated by culture. S. Anatum was the most common serovar found associated with red meat compared to S. kentucky isolated from fish and poultry meat. In conclusion, our study is the first to use a combined enrichment/invA qPCR method as a screening assay to detect Salmonella DNA in different types of commercialized food in Southern Tunisia. QPCR results indicate that Salmonella contamination is common in milk and in other types of food samples

First-time detection and identification of the Mycobacterium tuberculosis Complex members in extrapulmonary tuberculosis clinical samples in south Tunisia by a single tube tetraplex real-time PCR assay.

Tunisia has one of the highest burdens of extrapulmonary tuberculosis (EPTB) among tuberculosis (TB) cases but the contribution of MTBC-mediated human EPTB is unknown. EPTB diagnosis is challenging due to the paucibacillary nature of clinical samples. Therefore, a need of a simplified molecular method for sensitive and specific TB detection and differentiation of MTBC members caused EPTB remains a priority to an early diagnosis, optimize successful anti-TB treatment and minimize transmission. We evaluated the performance of a single tube tetraplex Taq Man real time PCR for EPTB detection and differentiation between MTBC members directly on extrapulmonary samples.Extrapulmonary samples obtained from clinically suspected EPTB patients from 2013 to April 2015 were tested by Ziehl Neelsen Staining, mycobacterial culture and qPCR assay for RD1, RD9, RD12 and ext-RD9 targets (MTBC-RD qPCR). The performance of qPCR was compared to a reference standard based on MTBC culture and/or at least two criteria of a composite reference standard (CRS) including clinical, radiological, histopathological and therapeutic findings.EPTB was identified in 157/170 (92.4%) of included patients of whom 99 (63%) were confirmed by culture and 58 (36.9%) by CRS criteria. The sensitivity and specificity of qPCR, in comparison to the reference standard were 100% (157/157) and 92.3% (12/13), respectively. The sensitivity of qPCR was statistically significant as compared to culture and smear microscopy (P< 0.001). QPCR results showed M. bovis identification in 77.1% of extrapulmonary samples in occurrence to lymphadenitis infection. M. tuberculosis and M.bovis BCG were detected in 21.6% and 1.3% of cases, respectively.MTBC-RD qPCR proved to be a rapid and sensitive assay for simultaneously TB detection and MTBC members identification on extrapulmonary samples within 1.5 days after sample receipt. Its high sensitivity could make this method a useful tool in diagnosing TB in addition to routine conventional methods and TB clinical parameters

Molecular characterization of Mycobacterium tuberculosis strains resistant to isoniazid

Objective/background: Tuberculosis is a major public health problem and the emergence of drug resistance complicates the situation even more. It is therefore crucial to implement all conclusions from the studies that aim at a better understanding of the molecular mechanisms which govern the emergence and the evolution of drug resistance. The aim of this study is to assess the degree of involvement of the inhA and katG genes in the acquisition of isoniazid resistance in clinical strains of Mycobacterium tuberculosis. Methods: The inhA and katG genes were sequenced in 21 strains of M. tuberculosis with different resistance profiles and from different regions. Results: Analysis of the sequences obtained by comparison to those of the reference strain H37Rv showed that 95.2% had mutations. KatG S315T was the most common mutation (85.7%). The mutation katG T275A was revealed in two strains (9.5%). Two different point mutations in the inhA gene and its promoter region were identified as C-15T and G56A at a frequency equal to 14% and 10%, respectively. The G56A mutation is a new silent mutation. Our study showed no correlation between found mutations and multidrug resistance. Among the 21 strains studied, only one strain showed no mutations. Conclusion: In terms of this study, we characterized the mutations involved in resistance to isoniazid. katG S315T was by far the most frequent mutation, followed by C-15T. The frequency of these mutations was concordant with those reported in literature including those in intermediate tuberculosis endemic countries