In Vivo Systematic Analysis of Candida albicans Zn2-Cys6 Transcription Factors Mutants for Mice Organ Colonization

The incidence of fungal infections in immuno-compromised patients increased considerably over the last 30 years. New treatments are therefore needed against pathogenic fungi. With Candida albicans as a model, study of host-fungal pathogen interactions might reveal new sources of therapies. Transcription factors (TF) are of interest since they integrate signals from the host environment and participate in an adapted microbial response. TFs of the Zn2-Cys6 class are specific to fungi and are important regulators of fungal metabolism. This work analyzed the importance of the C. albicans Zn2-Cys6 TF for mice kidney colonization. For this purpose, 77 Zn2-Cys6 TF mutants were screened in a systemic mice model of infection by pools of 10 mutants. We developed a simple barcoding strategy to specifically detect each mutant DNA from mice kidney by quantitative PCR. Among the 77 TF mutant strains tested, eight showed a decreased colonization including mutants for orf19.3405, orf19.255, orf19.5133, RGT1, UGA3, orf19.6182, SEF1 and orf19.2646, and four an increased colonization including mutants for orf19.4166, ZFU2, orf19.1685 and UPC2 as compared to the isogenic wild type strain. Our approach was validated by comparable results obtained with the same animal model using a single mutant and the revertant for an ORF (orf19.2646) with still unknown functions. In an attempt to identify putative involvement of such TFs in already known C. albicans virulence mechanisms, we determined their in vitro susceptibility to pH, heat and oxidative stresses, as well as ability to produce hyphae and invade agar. A poor correlation was found between in vitro and in vivo assays, thus suggesting that TFs needed for mice kidney colonization may involve still unknown mechanisms. This large-scale analysis of mice organ colonization by C. albicans can now be extended to other mutant libraries since our in vivo screening strategy can be adapted to any preexisting mutants

Cis- and trans-acting elements determining induction of the genes of the gamma-aminobutyrate (GABA) utilization pathway in Saccharomyces cerevisiae.

In S. cerevisiae, gamma-aminobutyrate (GABA) induces transcription of the UGA genes required for its utilization as a nitrogen source. Analysis of the 5' region of the UGA1 and UGA4 genes led to the identification of a conserved GC-rich sequence (UASGABA) essential to induction by gamma-aminobutyrate. Alone, this UASGABA element also supported some levels of reporter gene transcription in the presence of gamma-aminobutyrate. To be effective, UASGABA requires two positive-acting proteins that both contain a Cys6-Zn2 type zinc-finger motif, namely pathway-specific Uga3p and pleiotropic Uga35p(Dal81p/DurLp). Further analysis of the UGA4 gene revealed that Gln3p, a global nitrogen regulatory protein containing a GATA zinc-finger domain, is required in order to reach high levels of gamma-aminobutyrate-induced transcription. The Gln3p factor exerts its function mainly through a cluster of 5'-GAT(A/T)A-3'(UASGATA) situated just upstream from UASGABA. The role of Gln3p is less predominant in UGA1 than in UGA4 gene expression. We propose that tight coupling between the UASGABA and UASGATA elements enables the cell to integrate, according to its nitrogen status, the induced expression levels of UGA4

A numerical algorithm for computing the inverse of a Toeplitz pentadiagonal matrix

In the current paper, we present a computationally efficient algorithm for obtaining the inverse of a pentadiogonal toeplitz matrix. Few conditions are required, and the algorithm is suited for implementation using computer algebra systems

Antioxidant activity, phenols and flavonoids contents and antibacterial activity of some Moroccan medicinal plants against tomato bacterial canker agent

Medicinal and aromatic plants (MAP) belonging to 16 species, currently used in southern Moroccan traditional medicine, were evaluated here, firstly, for the action of their aqueous extracts against the bacterial canker agent of tomato in vitro. Then the phenolic contents, flavonoids contents and antioxidant capacities of these MAP extracts were estimated. Results obtained show that tested species exhibited biological activity toward the pathogen studied here; the inhibition zone diameter was between 0.5 and 4.88 cm. Furthermore, tested species exhibited a board range of phenolic contents varying from 55.58 ± 5.07 to 3.98 ± 0.16 mg of Cafeic acid equivalents (CAE) per gram of dry weight (DW). The flavonoids contents varied from 19.82 ± 0.65 to 1.74 ± 0.34 mg of Rutine equivalents (RE) per g of DW. Significant and positive linear correlations were found between total phenolic contents (R = 0.87 and R2 = 0.76), flavonoids contents (R = 0.96 and R2 = 0.93) and the biologic activity (IZ diameters) of the aqueous extracts. The antioxidant capacity expressed as Trolox equivalents antioxidant capacity (TEAC) varied from 550.67 to 1.18 mM per 100 g dry weight. Significant and positive linear correlation was found also between antioxidant capacities and both phenolic and flavonoids contents. These results proved that the richness of MAP with phenols and flavonoids was involved in there antibacterial activity and there antioxidant capacity. This finding is useful and can contribute to the development of potent and natural bio pesticides in the future for the control of bacterial canker of tomato as well as other phytopathogens by exploiting MAP compounds accepted by consummators and environmentalists.Keywords: Bacterial canker, tomato, medicinal plants, biological control, flavonoids, Trolox equivalents antioxidant capacity (TEAC), 2,2-diphenyl-1-picrylhydrazyl (DPPH).African Journal of Biotechnology, Vol 13(49) 4515-452

Ethnobotanical utilization of Alhagi maurorum Medik. in traditional recipes of Algerian Sahara Illizi Wilaya

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