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21.
Endosulfan is one of the persistent organochlorinated pesticides used extensively throughout the world, particularly in the developing countries. Its microbial metabolic transformation product endosulfan sulphate is more toxic and persistent than the parent compound itself. In order to completely mineralize endosulfan, augmentation of soil microbial community with efficient endosulfan degradation properties could a potentially viable option. In the present study, endosulfan degrading bacterium was isolated from the agriculture-contaminated soil of Shujaabad, Multan, Pakistan by using enrichment technique. The isolated bacterial strain EN-1 (Endosulfan-1) was identified as S. maltophilia by 16S rRNA sequencing and biochemical analysis. EN-1 has demonstrated the ability to utilize endosulfan as sole sulfur source. Kinetics of endosulfan degradation was studied at various initial concentrations ranges from 5 mg/L to 100 mg/L by growth dependent and growth independent kinetic models. Biodegradation kinetics revealed that the bacterium was highly efficient in endosulfan degradation. The average values of kinetic constants i.e. Ks, and µmax were 13.73 mg/L and 0.210 h?1 respectively, while µmax/Ks ratio was 0.015. Addition of sulfur decreased the rate of degradation as the µmax/Ks was observed to reduce. GC-MS analysis revealed that the bacterium metabolised the endosulfan into non-toxic metabolite i.e. endosulfan diol. The study instigates a complete elucidation of degradation process for commercial applications. 相似文献
22.
Toxicological Study and Oxidative Stress Evaluation for Safety Assessment of Xylanase Preparations in Wistar Rats 下载免费PDF全文
Dorra Driss Najla Soudani Tahia Boudawara Najiba Zeghal Semia Ellouze Chaabouni 《Journal of biochemical and molecular toxicology》2014,28(11):490-500
Acute and 90‐day subchronic oral toxicity studies were conducted to establish the safety evaluation of xylanases preparations. A potential oxidative stress evaluation was also performed through testing the generation of oxidative radicals, depletion of antioxidants via oxidative modification of lipids, proteins and DNA of organ cells. During the subchronic oral toxicity study, no mortality was observed, obvious treatment‐related clinical signs and urinalysis parameters were in normal range. Differences in some hematological parameters, biochemistry, relative organ weight, and histopathology examinations between the treated group and the control group were not judged to be adverse. Our results indicated that the no‐observed‐adverse‐effect level for xylanases was 1,500 TXU/kg/day and the plasma antioxidant assays showed that these xylanases did not produce free‐radicals nor oxidative injuries. On the basis of the bacterial reverse mutation assay data, it is concluded that the expressed xylanase in Pichia pastoris do not present any mutagenic potential when tested in relevant genotoxicological assays. 相似文献
23.
Lamia Hila Hédia Tébourbi Leila Abaied Imène Rejeb Lamia Ben Jemaa Habiba Chaabouni 《Biochemical genetics》2009,47(9-10):727-733
Subtelomeric rearrangements significantly contribute to idiopathic mental retardation and result in several mental retardation syndromes; however, most subtelomeric defects lack a characteristic phenotype. Thirty patients with unexplained mental retardation, a normal R banded karyotype at the 550 band, and no clinically recognizable syndrome were screened by Multiplex ligation-dependent probe amplification (MLPA). Four anomalies were identified: deletion 17q, duplications (4q), and associated duplications 15q and Xq. This duplication was found in two sisters of the proband. Anomalies were unidentified by the conventional technique. The prevalence of subtelomeric imbalances in our cohort of moderate to severe mental retardation is around 13% and is consistent with the literature. The sensitivity of the MLPA technique was characterized on cytogenetically verified positive and negative controls. MLPA is a fast, reliable, and relatively inexpensive technique to detect subtelomeric rearrangement in comparison with the fluorescence in situ hybridization (FISH) technique. 相似文献
24.
Mohamed Guerfali Moncef Chaabouni Ali Gargouri Hafedh Belghith 《Applied microbiology and biotechnology》2010,85(5):1361-1372
This study is an application of an experimental design methodology for the optimization of the culture conditions of α-l-arabinofuranosidase production by Talaromyces thermophilus. Wheat bran and yeast extract were first selected as the best carbon and nitrogen sources, respectively, for enzyme production.
A Plackett–Burman design was then used to evaluate the effects of eight variables. Statistical analyses showed that while
pH had a negative effect on α-l-arabinofuranosidase production, wheat bran and MgSO4 had a significantly positive effect. The values of the latter three parameters were further optimised using a central composite
design and a response surface methodology. The experimental results were fitted to a second-order polynomial model that yielded
a determination coefficient of R
2 = 0.91. The statistical output showed that the linear and quadric terms of the three variables had significant effects. Using
optimal conditions, the experimental value of α-l-arabinofuranosidase activity produced was very close to the model-predicted value. The optimal temperature and pH of enzyme
activity were 55 °C and 7.0, respectively. This enzyme was very stable over a considerable pH range from 4 to 9. The crude
enzyme of T. thermophilus rich in α-l-arabinofuranosidase was also used for saccharification of lignocellulosic materials and arabinose production. 相似文献
25.
Anthony H. Taylor Muna S. Abbas Marwan A. Habiba Justin C. Konje 《Histochemistry and cell biology》2010,133(5):557-565
Plasma anandamide (AEA) levels fluctuate throughout the menstrual cycle and in early pregnancy in a pattern suggesting its
involvement in implantation and early pregnancy maintenance through mechanisms that might involve its binding to cannabinoid
receptors CB1 and CB2. Plasma AEA levels are maintained by the actions of the enzymes fatty acid amide hydrolase (FAAH) and
N-acylphosphatidylethanolamine-phospholipase D (NAPE-PLD). All of these component parts of the ‘endocannabinoid system’ have
been demonstrated in rodent but not in human uteri. This study aimed to demonstrate the presence of the endocannabinoid system
in the human uterus and catalogue its modulation. Immunohistochemical techniques were employed to localise and determine the
distribution of immunoreactive CB1, CB2, FAAH, and NAPE-PLD in well-characterised menstrual cycle biopsy samples. Immunoreactive
CB1 and CB2 were widely distributed throughout the uterine tissue. In the myometrium and endometrium, smooth muscle cells
were immunoreactive, although the vascular smooth muscle cells in both tissues were more so. In the endometrium, CB1 and CB2
immunoreactivity was primarily restricted to the glandular epithelium and expression was unrelated to the phase of the cycle.
FAAH immunoreactivity in the endometrium was highest in the mid-proliferative gland and mid-secretory stroma, whilst NAPE-PLD
immunoreactivity was down-regulated in the secretory epithelial gland compared to the proliferative epithelial gland and unaffected
in the stroma. These data indicate that elements of the ‘endocannabinoid system’ coexist in many cell types within the uterus
and may provide insight into the sites of action of endogenous and exogenous cannabinoids during endometrial transformation. 相似文献
26.
M. Messedi M. Frigui Kh. Chaabouni M. Turki M. Neifer A. Lahiyani M. Messaouad Z. Bahloul F. Ayedi K. Jamoussi 《Gene》2013
Background
Behcet's disease (BD) is a chronic, relapsing, multi-systemic inflammatory disorder of unknown causes. This disease is mainly characterized by mucocutaneous, ocular, vascular, and central nervous system manifestations. The aim of this study is to investigate the associations between C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene and the plasma homocysteine (Hcy), folate, and B12 levels in a relatively large cohort of Tunisian patients with BD.Methods
The study included 142 patients with BD and 172 healthy controls. The C677T and A1298C polymorphisms were genotyped using PCR-RFLP. Serum Hcy level was determined using a fluorescence polarization immunoassay. Serum folate and vitamin B12 levels were measured by electrochemiluminescence immunoassay.Results
Genotype and allele frequencies of the two studied MTHFR polymorphisms did not show any significant differences among BD patients compared to controls. Patient carriers of the 677TT variant and the 677 T allele displayed significantly higher Hcy concentration. Moreover, no significant association was found between neither A1298C polymorphism nor the C allele and Hcy, folate, and B12 levels. In multivariate analyses, we reported that 677 T allele, male gender, and creatinine level were independent risk factors for hyperhomocysteinemia (HHC).Conclusions
In the present study, we report the absence of any significant differences between genotype and allele frequencies for both studied polymorphisms among BD patients compared to healthy controls. Besides, we showed that the T allele of MTHFR C677T polymorphism influenced the Hcy level which is an independent risk factor for HHC in Tunisian BD patients. 相似文献27.
Nahiduzzaman M Mahbubul Hassan M Habiba Khanam U Mamun SN Hossain MA Tiersch TR 《Cryobiology》2011,62(1):62-67
The present study focused on development of a sperm cryopreservation protocol for the critically endangered olive barb Puntiussarana (Hamilton, 1822) collected from two stocks within Bangladesh and reared in the Fisheries Field Laboratory, Bangladesh Agricultural University (BAU). The sperm were collected in Alsever’s solution prepared at 296 mOsmol kg−1. Sperm were activated with distilled water (24 mOsmol kg−1) to characterize motility. Maximum motility (90%) was observed within 15 s after activation, and sperm remained motile for 35 s. Sperm activation was evaluated in different osmolalities and motility was completely inhibited when osmolality of the extender was ?287 mOsmol kg−1. To evaluate cryoprotectant toxicity, sperm were equilibrated with 5%, 10% and 15% each of dimethyl sulfoxide (DMSO) and methanol. Sperm motility was noticeably reduced within 10 min, when sperm were equilibrated with 15% DMSO, indicating acute toxicity to spermatozoa and therefore this concentration was excluded in further trials. Sperm were cryopreserved using DMSO at concentrations of 5% and 10% and methanol at 5%, 10% and 15%. The one-step freezing protocol (from 5 °C to −80 °C at 10 °C/min) was carried out in a computer-controlled freezer (FREEZE CONTROL® CL-3300; Australia) and 0.25-ml straws containing spermatozoa were stored in liquid nitrogen for 7–15 days at −196 °C. The highest motility in thawed sperm 61 ± 8% (mean ± SD) was obtained with 10% DMSO. The fertilization and hatching rates were 70% and 37% for cryopreserved sperm, and 72% and 62% for fresh sperm. The protocol reported here can be useful for hatchery-scale production of olive barb. The use of cryopreserved sperm can facilitate hatchery operations, and can provide for long-term conservation of genetic resources to contribute in the recovery of critically endangered fish such as the olive barb. 相似文献
28.
High-level constitutive expression of xylanase GH11 from Penicillium occitanis Pol6 termed PoXyn2 was achieved using the methylotrophic yeast Pichia pastoris. The PoXyn2 cDNA encoding for a mature xylanase of 320 amino acids was subcloned into the pGAPZαA vector, to construct recombinant xylanse with six histidine residues at the N-terminal and further integrated into the genome of P. pastoris X-33 under the control of the glyceraldehyde 3-phosphate dehydrogenase (GAP) constitutive promoter. Activity assay and SDS-PAGE demonstrate that the His-tagged xylanase was extracellularly expressed in P. pastoris and purified to homogeneity by a simple, one-step purification protocol using immobilized metal affinity chromatography (Ni-NTA resin). The purified PoXyn2 showed a single band on SDS-PAGE with an apparent molecular weight of 30 kDa. The xylanase activity was optimal at pH 3.0 and 50°C. The specific activity measured for Oat Spelt Xylan was 8549.85 U mg(-1). The apparent The K(M) and V(max) values were 8.33±0.7 mg ml(-1)and 58.82±0.9 μmol min(-1) ml(-1), respectively, as measured on Oat Spelt Xylan. This is the first report demonstrating the possibility of mass production of P. occitanis xylanase using P. pastoris. 相似文献
29.
Doliba NM Qin W Najafi H Liu C Buettger CW Sotiris J Collins HW Li C Stanley CA Wilson DF Grimsby J Sarabu R Naji A Matschinsky FM 《American journal of physiology. Endocrinology and metabolism》2012,302(1):E87-E102
It was reported previously that isolated human islets from individuals with type 2 diabetes mellitus (T2DM) show reduced glucose-stimulated insulin release. To assess the possibility that impaired bioenergetics may contribute to this defect, glucose-stimulated respiration (Vo(2)), glucose usage and oxidation, intracellular Ca(2+), and insulin secretion (IS) were measured in pancreatic islets isolated from three healthy and three type 2 diabetic organ donors. Isolated mouse and rat islets were studied for comparison. Islets were exposed to a "staircase" glucose stimulus, whereas IR and Vo(2) were measured. Vo(2) of human islets from normals and diabetics increased sigmoidally from equal baselines of 0.25 nmol/100 islets/min as a function of glucose concentration. Maximal Vo(2) of normal islets at 24 mM glucose was 0.40 ± 0.02 nmol·min(-1)·100 islets(-1), and the glucose S(0.5) was 4.39 ± 0.10 mM. The glucose stimulation of respiration of islets from diabetics was lower, V(max) of 0.32 ± 0.01 nmol·min(-1)·100 islets(-1), and the S(0.5) shifted to 5.43 ± 0.13 mM. Glucose-stimulated IS and the rise of intracellular Ca(2+) were also reduced in diabetic islets. A clinically effective glucokinase activator normalized the defective Vo(2), IR, and free calcium responses during glucose stimulation in islets from type 2 diabetics. The body of data shows that there is a clear relationship between the pancreatic islet energy (ATP) production rate and IS. This relationship was similar for normal human, mouse, and rat islets and the data for all species fitted a single sigmoidal curve. The shared threshold rate for IS was ~13 pmol·min(-1)·islet(-1). Exendin-4, a GLP-1 analog, shifted the ATP production-IS curve to the left and greatly potentiated IS with an ATP production rate threshold of ~10 pmol·min(-1)·islet(-1). Our data suggest that impaired β-cell bioenergetics resulting in greatly reduced ATP production is critical in the molecular pathogenesis of type 2 diabetes mellitus. 相似文献
30.
Islem Younes Olfa Ghorbel-Bellaaj Rim Nasri Moncef Chaabouni Marguerite Rinaudo Moncef Nasri 《Process Biochemistry》2012,47(12):2032-2039
Different crude microbial proteases were applied for chitin extraction from shrimp shells. A Box–Behnken design with three variables and three levels was applied in order to approach the prediction of optimal enzyme/substrate ratio, temperature and incubation time on the deproteinization degree with Bacillus mojavensis A21 crude protease. These optimal conditions were: an enzyme/substrate ratio of 7.75 U/mg, a temperature of 60 °C and an incubation time of 6 h allowing to predict 94 ± 4% deproteinization. Experimentally, in these optimized conditions, a deproteinization degree of 88 ± 5% was obtained in good agreement with the prediction and larger than values generally given in literature. The deproteinized shells were then demineralized to obtain chitin which was converted to chitosan by deacetylation and its antibacterial activity against different bacteria was investigated. Results showed that chitosan dissolved at 50 mg/ml markedly inhibited the growth of most Gram-negative and Gram-positive bacteria tested. 相似文献