90 research outputs found
Five naturally bioactive molecules including two rhamnopyranoside derivatives isolated from the Streptomyces sp strain TN58
No full textExtraction of 25 L fermentation broth of the newly isolated Streptomyces sp. strain TN58 and various separation and purification steps led to the isolation of five bioactive metabolites, namely brevianamide F (C1), reported from a streptomycete for the first time, N-acetyltryptamine (C2), thiazolidomycin (C3), and two rhamnopyranosides (C4 and C5). These two rhamnopyranosides were produced directly, without precursor addition. The chemical structure of these five active compounds was established on the basis of 1H, 13C/APT and 2D NMR spectra, ESI and EI-MS data, and by comparison with data from the literature. According to the biological studies, we show in this work that the compounds C1, C2, C4 and C5 possess antimicrobial activities
Bioactive Secondary Metabolites from a New Terrestrial Streptomyces sp. TN262
No full textDuring our search for Streptomyces spp. as new producers of bioactive secondary metabolites, the ethyl acetate extract of the new terrestrial Streptomyces isolate TN262 delivered eight antimicrobially active compounds. They were identified as 1-acetyl-beta-carboline (1), tryptophol (2), cineromycin B (3), 2,3-dihydrocineromycin B (4), cyclo-(tyrosylprolyl) (5), 3-(hydroxyacetyl)-indole (6), brevianamide F (7), and cis-cyclo-(l-prolyl-l-leucyl) (8). Three further metabolites were detected in the unpolar fractions using GC-MS and tentatively assigned as benzophenone (9), N-butyl-benzenesulfonamide (10), and hexanedioic acid-bis-(2-ethylhexyl) ester (11). This last compound is known as plasticizer derivatives, but it has never been described from natural sources. In this article, we describe the identification of the new Streptomyces sp. isolate TN262 using its cultural characteristics, the nucleotide sequence of the corresponding 16S rRNA gene and the phylogenetic analysis, followed by optimization, large-scale fermentation, isolation of the bioactive constituents, and determination of their structures. The biological activity of compounds (2), (3), (4), and those of the unpolar fractions was addressed as well.Tunisian-Egyptian project "MELLOULI/SHAABAN
Non-classical human leukocyte antigen class I in Tunisian children with autism
No full textAutism spectrum disorders (ASD) are one of the most common childhood morbidities characterized by deficits in communication and social skills. Increasing evidence has suggested associations between immune genes located in the human leukocyte antigen (HLA) complex and etiology of autism.In this study, we investigated whether the non-classical class I HLA-G, -E, and -F polymorphisms are associated with genetic predisposition to autism in Tunisia. We aimed to find a correlation between HLA-G genotypes and soluble HLA-G (sHLA-G) levels. We have analyzed the HLA-G, -E, and -F genotypes of 15 autistic children and their parents. DNA typing of HLA class I genes was performed using PCR-SSP and PCR-RFLP methods. Also, we evaluated the serum levels of HLA-G (1 and 5) by a validated ELISA technique in autistic probands and their parents.No association was found between any polymorphism and autism in the study subjects. Additionally, we found no correlation between sHIA-G1 and sHLA-G5 and autism. Also, no significant difference in sHIA-G testing in parents and offspring was found. However, parents carrying [GG] genotype presented a higher sHLA-G levels than those carrying ([CC]+[GC]) genotypes (p = 0.037).From this preliminary study, we conclude that the investigated polymorphisms of HLA-G, -E, and -F genes did not lead to autism susceptibility in Tunisian children. However, the CGTIGA haplotype was found to be associated with the disease
A Deep Neural Network for Vessel Segmentation of Scanning Laser Ophthalmoscopy Images
No full textPublisher Copyright: © Springer International Publishing AG 2017.Retinal vessel segmentation is a fundamental and well-studied problem in the retinal image analysis field. The standard images in this context are color photographs acquired with standard fundus cameras. Several vessel segmentation techniques have been proposed in the literature that perform successfully on this class of images. However, for other retinal imaging modalities, blood vessel extraction has not been thoroughly explored. In this paper, we propose a vessel segmentation technique for Scanning Laser Opthalmoscopy (SLO) retinal images. Our method adapts a Deep Neural Network (DNN) architecture initially devised for segmentation of biological images (U-Net), to perform the task of vessel segmentation. The model was trained on a recent public dataset of SLO images. Results show that our approach efficiently segments the vessel network, achieving a performance that outperforms the current state-of-the-art on this particular class of images.This work is financed by the North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, and the European Regional Development Fund (ERDF), within the project “NanoSTIMA: Macro-to-Nano Human Sensing: Towards Integrated Multimodal Health Monitoring and Analytics/NORTE-01-0145-FEDER-000016”.Peer reviewe
Integrative gene cloning and expression system for Streptomyces sp. US 24 and Streptomyces sp. TN 58 bioactive molecule producing strains
Get PDFStreptomyces sp. US 24 and Streptomyces sp. TN 58, two strains producing interesting bioactive molecules, were successfully transformed using E. coli ET12567 (pUZ8002), as a conjugal donor, carrying the integrative plasmid pSET152. For the Streptomyces sp. US 24 strain, two copies of this plasmid were tandemly integrated in the chromosome, whereas for Streptomyces sp. TN 58, the integration was in single copy at the attB site. Plasmid pSET152 was inherited every time for all analysed Streptomyces sp. US 24 and Streptomyces sp. TN 58 exconjugants under nonselective conditions. The growth, morphological differentiation, and active molecules production of all studied pSET152 integrated exconjugants were identical to those of wild type strains. Consequently, conjugal transfer using pSET152 integration system is a suitable means of genes transfer and expression for both studied strains. To validate the above gene transfer system, the glucose isomerase gene (xylA) from Streptomyces sp. SK was expressed in strain Streptomyces sp. TN 58. Obtained results indicated that heterologous glucose isomerase could be expressed and folded effectively. Glucose isomerase activity of the constructed TN 58 recombinant strain is of about eighteenfold higher than that of the Streptomyces sp. SK strain. Such results are certainly of importance due to the potential use of improved strains in biotechnological process for the production of high-fructose syrup from starch
Targeted gene disruption of the cyclo (L-Phe, L-Pro) biosynthetic pathway in Streptomyces sp US24 strain
Get PDFWe have previously isolated a new actinomycete strain from Tunisian soil called Streptomyces sp. US24, and have shown that it produces two bioactive molecules including a Cyclo (L-Phe, L-Pro) diketopiperazine (DKP). To identify the structural genes responsible for the synthesis of this DKP derivative, a PCR amplification (696 bp) was carried out using the Streptomyces sp. US24 genomic DNA as template and two degenerate oligonucleotides designed by analogy with genes encoding peptide synthetases (NRPS). The detection of DKP derivative biosynthetic pathway of the Streptomyces sp. US24 strain was then achieved by gene disruption via homologous recombination using a suicide vector derived from the conjugative plasmid pSET152 and containing the PCR product. Chromatography analysis, biological tests and spectroscopic studies of supernatant cultures of the wild-type Streptomyces sp. US24 strain and three mutants obtained by this gene targeting disruption approach showed that the amplified DNA fragment is required for Cyclo (L-Phe, L-Pro) biosynthesis in Streptomyces sp. US24 strain. This DKP derivative seems to be produced either directly via a nonribosomal pathway or as a side product in the course of nonribosomal synthesis of a longer peptide
Biopreservative Efficacy of Bacteriocin BacFL31 in Raw Ground Turkey Meat in terms of Microbiological, Physicochemical, and Sensory Qualities
No full textAdversarial Synthesis of Retinal Images from Vessel Trees
No full textPublisher Copyright: © Springer International Publishing AG 2017.Synthesizing images of the eye fundus is a challenging task that has been previously approached by formulating complex models of the anatomy of the eye. New images can then be generated by sampling a suitable parameter space. Here we propose a method that learns to synthesize eye fundus images directly from data. For that, we pair true eye fundus images with their respective vessel trees, by means of a vessel segmentation technique. These pairs are then used to learn a mapping from a binary vessel tree to a new retinal image. For this purpose, we use a recent image-to-image translation technique, based on the idea of adversarial learning. Experimental results show that the original and the generated images are visually different in terms of their global appearance, in spite of sharing the same vessel tree. Additionally, a quantitative quality analysis of the synthetic retinal images confirms that the produced images retain a high proportion of the true image set quality.This work is funded by the ERDF - European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation - COMPETE 2020 Programme, by the FCT - Fundação para a Ciência e a Tecnologia within project CMUP-ERI/TIC/0028/2014 and by the North Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement within the project “NanoSTIMA: Macro-to-Nano Human Sensing: Towards Integrated Multimodal Health Monitoring and Analytics/NORTE-01-0145-FEDER-000016”.Peer reviewe
Relationships Between Textural Modifications, Lipid and Protein Oxidation and Sensory Attributes of Refrigerated Turkey Meat Sausage Treated with Bacteriocin BacTN635
No full textInfluence of Local Soil Conditions on the Damage Distribution in Izmir Bay During the October 30, 2020, Samos Earthquake
No full textOn October 30, 2020, a damaging earthquake of moment magnitude 6.6 struck about 14 km northeast of the island of Samos, Greece, and about 70 km from the center of the city of Izmir in Turkey. Even though the epicenter was relatively far away, the effects of the seismic event in the highly populated city center of Izmir were destructive causing over 100 fatalities and significant structural damage. Multiple failures of high buildings constituted the major source of the fatalities. This paper aims to understand the link between the localized damage distribution and the nature of amplification effects that have been observed in Izmir Bay, starting from collection and data analysis interpretation of seismic records and targeted damage assessment of the built environment, as well as geological and morphological characteristics of the area and the geotechnical properties of soils. Critical analysis of the numerous recorded signals shows the key role of the young alluvium and shallow marine deposits of the basin on which Izmir Bay was growing. The coupling mechanism between the frequency content of the shaking and the fundamental frequencies of the damaged buildings contributed to exacerbating the inertial forces acting on the collapsed buildings. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2022
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