Studies on the ecology of actinomycetes in an agricultural soil amended with organic residues: II. Assessment of enzymatic activities of <Emphasis Type="Italic">Actinomycetales</Emphasis> isolates

The main objective of this investigation was to study the enzymatic activities of Actinomycetales strains isolated from an agricultural soil amended with different amounts of municipal solid waste compost (MSWC) or farmyard manure (FM). For this purpose, the hydrolytic activities of carboxymethyl cellulase, xylanase, pectinase, amylase, chitinase and protease were tested for 75 isolates of Sterptomyces, Amycolatopsis and Nocardioides from different sources (unamended soil, amended soil with FM or MSWC, FM and MSWC) at temperature ranging between 30 and 50°C. It was shown that the highest rate of enzymes producer’s strains was registered at 30°C, and decreased gradually to annul at 50°C, with the exception of the MSWC strains origin. It was also shown that the percentage of strains producers of enzymes isolated from soil amended with MSWC appeared higher than the one registered for those isolated from control and amended with FM soils. Application of MSWC increases the number of enzymes producer-actinomycetes in the soil and then it improves its fertility.     

Lack of association between human leukocyte antigen-E alleles and nasopharyngeal carcinoma in Tunisians

Nasopharyngeal carcinoma (NPC), a cancer with a remarkable geographical and worldwide ethnic distribution, has been strongly associated with human leukocyte antigen (HLA) class I genes. The presence of additional HLA risk factors has been suggested by several reports. In the present study, we analyzed the implication of HLA-E gene polymorphisms in NPC susceptibility in Tunisians, a population characterized by an intermediate incidence of NPC with specific clinical features. Peripheral blood DNA was obtained from 185 patients with NPC and 177 matched controls. Genotyping for three single-nucleotide polymorphisms, codon 83Gly/Arg, codon 157Arg/Gly, and codon 107Arg/Gly, was performed using the polymerase chain reaction method. The HLA-E*01:01 and HLA-E*01:03 were the only alleles found among Tunisians. The HLA-E*01:03 allele had a slight increase in patients with NPC (43%) compared with controls (37%), but the difference did not reach a statistical significance. Our results show the lack of association between HLA-E alleles and NPC in the Tunisian population. This is not in agreement with the previous studies, suggesting a potential implication of HLA-E gene polymorphisms in the susceptibility to NPC among populations with high-risk incidence. Our study further supports the dissimilarity of NPC between populations with different NPC incidence.     

Two Tunisian patients with Peters plus syndrome harbouring a novel splice site mutation in the B3GALTL gene that modulates the mRNA secondary structure

Peters plus syndrome is an autosomal recessive rare disorder comprising ocular anterior segment dysgenesis, short stature, hand abnormalities, distinctive facial features, and often other major/minor additional defects. Peters plus syndrome is related to mutations in the B3GALTL gene with only seven recently reported mutations, leading to the inactivation of the B1, 3-glucosyltransferase. In this study, we screened the B3GALTL gene in two unrelated patients with typical Peters plus syndrome. A novel homozygous c.597-2A>G mutation was identified in both patients. Bioinformatic analyses showed that this mutation modulates the pre mRNA secondary structure of the gene, and decreases the score value related to the formation of splicing loops. Moreover, the c.597-2A>G mutation is located in a CpG Island of the B3GALTL gene, suggesting a potential epigenetic role of this position including gene's methylation and regulation. These data confirm an important role of the B3GALTL gene test that provides diagnosis confirmation and improves genetic counseling for the families.     

Polymorphisms of glutathione S-transferases M1, T1, P1 and A1 genes in the Tunisian population: an intra and interethnic comparative approach

Genetic polymorphisms in glutathione S-transferases (GSTs) genes might influence the detoxification activities of the enzymes predisposing individuals to cancer risk. Owing to the presence of these genetic variants, inter-individual and ethnic differences in GSTs detoxification capacity have been observed in various populations. Therefore, the present study was performed to determine the prevalence GSTM1 0/0, GSTT1 0/0, GSTP1 Ile(105)Val, and GSTA1 A/B polymorphisms in 154 healthy individuals from South Tunisia, and to compare them with those observed in North and Centre Tunisian populations and other ethnic groups. GSTM1 and GSTT1 polymorphisms were analyzed by a Multiplex-PCR approach, whereas GSTP1 and GSTA1 polymorphisms were examined by PCR-RFLP. The frequencies of GSTM10/0 and GSTT1 0/0 genotypes were 53.9% and 27.9%, respectively. The genotype distribution of GSTP1 was 47.4% (Ile/Ile), 40.9% (Ile/Val), and 11.7% (Val/Val). For GSTA1, the genotype distribution was 24.7% (A/A), 53.9% (A/B), and 21.4% (B/B). The combined genotypes distribution of GSTM1, GSTT1, GSTP1 and GSTA1 polymorphisms showed that thirty one of the 36 possible genotypes were present in our population; eight of them have a frequency greater than 5%. To the best of our knowledge, this is the first report of GSTs polymorphisms in South Tunisian population. Our findings demonstrate the impact of ethnicity and reveal a characteristic pattern for Tunisian population. The molecular studies in these enzymes provide basis for further epidemiological investigations in the population where these functional polymorphisms alter therapeutic response and act as susceptibility markers for various clinical conditions.     

Induction of DNA fragmentation, chromosome aberrations and micronuclei by cisplatin in rat bone-marrow cells: protective effect of recombinant human erythropoietin

Cisplatin (Cisp) is one of the most effective chemotherapeutic agents. However, at higher doses several side effects may occur. Recombinant human erythropoietin (rhEPO), a glycoprotein regulating haematopoiesis, has recently been shown to exert an important cyto-protective effects in many tissues. The purpose of this study was to explore whether rhEPO protects against Cisp-induced genotoxicity in rat bone-marrow cells. Adult male Wistar rats were divided into six groups of 18 animals each: control group, rhEPO-alone group, Cisp-alone group and three rhEPO+Cisp-groups (pre-, co- and post-treatment condition, respectively). Our results show that Cisp induced a noticeable genotoxic effect in rat bone-marrow cells. In all types of treatment, rhEPO significantly decreased the frequency of micronuclei, the percentage of chromosome aberrations and the level of DNA damage. The protective effect of rhEPO was more efficient when it was administrated 24h before exposure to Cisp.     

Hematotoxicity and Genotoxicity of Mercuric Chloride Following Subchronic Exposure Through Drinking Water in Male Rats

Erythrocytes are a convenient model to understand the subsequent oxidative deterioration of biological macromolecules in metal toxicities. The present study examined the variation of hematoxic and genotoxic parameters following subchronic exposure of mercuric chloride via drinking water and their possible association with oxidative stress. Male rats were exposed to 50 ppm (HG1) and 100 ppm (HG2) of mercuric chloride daily for 90 days. A significant dose-dependent decrease was observed in red blood cell count, hemoglobin, hematocrit, and mean cell hemoglobin concentration in treated groups (HG1 and HG2) compared with controls. A significant dose-dependent increase was observed in lipid peroxidation; therefore, a significant variation was found in the antioxidant enzyme activities, such as superoxide dismutase, catalase, and glutathione peroxidase. Interestingly, mercuric chloride treatment showed a significant dose-dependent increase in frequency of total chromosomal aberration and in percentage of aberrant bone marrow metaphase of treated groups (p < 0.01). The oxidative stress induced by mercury treatment may be the major cause for chromosomal aberration as free radicals lead to DNA damage. These data will be useful in screening the antioxidant activities of natural products, which may be specific to the bone marrow tissue.     

Purification and Biochemical Characterization of an Organic-Solvent-Tolerant Thioredoxin from Dromedary Pancreas

We purified to homogeneity and characterized a heat stable thioredoxin which catalyzes thiol/disulfide exchange reaction, for the first time from dromedary pancreas. The purification involved heat and acidic treatment (90 °C; pH 2.5), precipitation by ammonium sulphate and ethanol, respectively followed by sequential column chromatography reverse HPLC column, and it resulted in an apparently pure protein after a 217-fold purification with a final yield of 55% of the initial thioredoxin activity. The thioredoxin preparation obtained was homogeneous as judged by polyacrylamide gel electrophoresis and the presence of valine as the only NHt-terminal amino acid. MALDI-TOF mass spectrometry revealed that the protein has a molecular mass of 11,302.9 Da. The first 40 amino-acid residues at the N-terminal extremity of purified DrTrx was determined by automatic Edman degradation and showed a high sequence homology with known Thioredoxin. It contained he tetrapeptide-Cys-Gly-Pro-Cys-, which constitutes the active site of mammalian thioredoxins. DrTrx activity was compatible with the presence of organic solvents and the maximum activity appeared at pH 7.5 using the insulin precipitation assay. Thioredoxin stability in the presence of organic solvents, as well as in acidic and alkaline pHs and at high temperatures makes it a good candidate for its application in pharmaceutical and food industry.     

Emergence of β-rhizobia as new root nodulating bacteria in legumes and current status of the legume–rhizobium host specificity dogma

World Journal of Microbiology and Biotechnology - Landfills are repository for complex microbial diversity responsible for bio-degradation of solid waste. To elucidate this complexity, samples from...