Relationship of plasma leptin and adiponectin concentrations with menopausal status in Tunisian women

To evaluate the effect of menopausal status and body mass index (BMI) on circulating leptin and adiponectin concentrations and investigate whether there is an influence of menopausal transition on the relationships of these adipokines and leptin to adiponectin (L/A) ratio with lipid profile and insulin resistance in a sample of Tunisian women. One hundred ninety-six premenopausal (mean age 35.3 ± 7.6 years) and 180 postmenopausal women (mean age 53.4 ± 6.2 years) were included in the study. Participants were stratified into obese and normal weight groups based upon their baseline BMI. Fasting glucose, HDL-cholesterol (HDL-C), triglycerides (TG), total cholesterol (TC), insulin, leptin, and adiponectin concentrations were measured. Homeostasis model assessment of insulin resistance (HOMA-IR) was calculated. Premenopausal women had significantly higher leptin and L/A ratio and lower adiponectin levels than postmenopausal women. Menopause had no effect on the mean values of BMI, insulin or HOMA-IR, HDL-C, and TG. Using a multiple linear regression model, menopausal status was identified, as significant independent predictor for leptin and adiponectin levels. Irrespective of the menopausal status, obese women exhibited higher leptin and L/A ratio and lower adiponectin levels compared to those with normal weight. Comparison between the two menopausal stages in obese and normal weight groups showed that leptin and L/A ratio decreased, while adiponectin increased from pre- to postmenopausal stage only in obese group. The L/A ratio correlated better with lipid profile and HOMA-IR in postmenopausal stage. The present study showed a significant interaction between menopause and BMI on leptin and adiponectin secretion. Menopausal transition affects the relationships of these adipokines with lipids and insulin resistance.     

Alkaline xylanases from Bacillus mojavensis A21: Production and generation of xylooligosaccharides

Medium composition and culture conditions for the xylanases production by Bacillus mojavensis A21 were optimized using two statistical methods: Plackett-Burman design applied to find the key ingredients and conditions for the best yield of enzyme production and Box-Behnken design used to optimize the value of the four significant variables: barley bran, NaCl, agitation, and cultivation time. The optimal conditions for higher production of xylanases were barley bran 18.66g/l, NaCl 1.04g/l, speed of agitation 176rpm and cultivation time 34.08h. Under these conditions, the xylanase experimental yield (7.45U/ml) closely matched the yield predicted by the statistical model (7.23U/ml) with R(2)=0.98. The medium optimization resulted in a 6.83-fold increase in xylanase production compared to that of the initial medium. Best xylanase activity was observed at the temperature of 50°C and at pH 8.0. The enzyme retained more 96% of its activity after 24h at pH ranges from 7.0 to 90.0. The enzyme preserved more 80% of its initial activity after 60min of pre-incubation from 30°C to 60°C. The main hydrolysis products yielded from corncob extracted xylan were xylobiose and xylotriose, suggesting the good potential of strain A21 in xylooligosaccharides production.     

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.     

Effects of hexavalent chromium on reproductive functions of male adult rats

Hexavalent chromium is an environmental contaminant which may be associated with reproductive abnormalities in male rats. In the present study, we examined the effect of hexavalent chromium on male reproductive function of rats. Male Wistar rats received a daily intraperitoneal injection of potassium dichromate (1 or 2 mg/kg body weight) for fifteen consecutive days. A decrease in testis weight and an increase in seminal vesicles and prostate weights were demonstrated after chromium treatment. Moreover, a dose-dependent increase in blood and testis chromium levels as well as an increase in FSH and a decrease in LH and testosterone serum levels were detected in treated rats. Histological analysis revealed pronounced morphological alterations with enlarged intracellular spaces, tissue loosening and dramatic loss of gametes in the lumen of the seminiferous tubules of treated rats. In addition, a decreased sperm motility and number of epididymal spermatozoa together with an increased sperm abnormality rate was found in chromium-treated rats in comparison to controls. In rats receiving the higher chromium dose, histological images presented considerably increased areas filled with seminal vesicle and prostate secretions. The mucosal crypts of seminal vesicles and the typical invaginations of prostate were altered. The results suggest that subacute treatment of potassium dichromate promotes reproductive system toxicity and affects testicular function of adult male rats.     

Chitin and chitosan preparation from shrimp shells using optimized enzymatic deproteinization

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.     

Domain structure of the HSC70 cochaperone, HIP.

The domain structure of the HSC70-interacting protein (HIP), a 43-kDa cytoplasmic cochaperone involved in the regulation of HSC70 chaperone activity and the maturation of progesterone receptor, has been probed by limited proteolysis and biophysical and biochemical approaches. HIP proteolysis by thrombin and chymotrypsin generates essentially two fragments, an NH2-terminal fragment of 25 kDa (N25) and a COOH-terminal fragment of 18 kDa (C18) that appear to be well folded and stable as indicated by circular dichroism and recombinant expression in Escherichia coli. NH2-terminal amino acid sequencing of the respective fragments indicates that both proteases cleave HIP within a predicted alpha-helix following the tetratricopeptide repeat (TPR) region, despite their different specificities and the presence of several potential cleavage sites scattered throughout the sequence, thus suggesting that this region is particularly accessible and may constitute a linker between two structural domains. After size exclusion chromatography, N25 and C18 elute as two distinct and homogeneous species having a Stokes radius of 49 and 24 A, respectively. Equilibrium sedimentation and sedimentation velocity indicate that N25 is a stable dimer, whereas C18 is monomeric in solution, with sedimentation coefficients of 3.2 and 2.3 S and f/f(o) values of 1.5 and 1.1 for N25 and C18, respectively, indicating that the N25 is elongated whereas C18 is globular in shape. Both domains are able to bind to the ATPase domain of HSC70 and inhibit rhodanese aggregation. Moreover, their effects appear to be additive when used in combination, suggesting a cooperation of these domains in the full-length protein not only for HSC70 binding but also for chaperone activity. Altogether, these results indicate that HIP is made of two structural and functional domains, an NH2-terminal 25-kDa domain, responsible for the dimerization and the overall asymmetry of the molecule, and a COOH-terminal 18-kDa globular domain, both involved in HSC70 and unfolded protein binding.     

Quantitative trait loci for grain yield and adaptation of durum wheat (Triticum durum Desf.) across a wide range of water availability

Grain yield is a major goal for the improvement of durum wheat, particularly in drought-prone areas. In this study, the genetic basis of grain yield (GY), heading date (HD), and plant height (PH) was investigated in a durum wheat population of 249 recombinant inbred lines evaluated in 16 environments (10 rainfed and 6 irrigated) characterized by a broad range of water availability and GY (from 5.6 to 58.8 q ha(-1)). Among the 16 quantitative trait loci (QTL) that affected GY, two major QTL on chromosomes 2BL and 3BS showed significant effects in 8 and 7 environments, with R2 values of 21.5 and 13.8% (mean data of all 16 environments), respectively. In both cases, extensive overlap was observed between the LOD profiles of GY and PH, but not with those for HD. QTL specific for PH were identified on chromosomes 1BS, 3AL, and 7AS. Additionally, three major QTL for HD on chromosomes 2AS, 2BL, and 7BS showed limited or no effects on GY. For both PH and GY, notable epistasis between the chromosome 2BL and 3BS QTL was detected across several environments.     

Neutrophil elastase mediates innate host protection against Pseudomonas aeruginosa

According to the widely accepted view, neutrophil elastase (NE), a neutrophil-specific serine protease, is a major contributor to Pseudomonas aeruginosa infection-associated host tissue inflammation and damage, which in severe cases can lead to death. Herein, we provide for the first time compelling evidence that the host rather employs NE to protect itself against P. aeruginosa infection. Using a clinically relevant model of pneumonia, targeted deficiency in NE increased the susceptibility of mice to P. aeruginosa. We found that NE was required for maximal intracellular killing of P. aeruginosa by neutrophils. In investigating the mechanism of NE-mediated killing of P. aeruginosa, we found that NE degraded the major outer membrane protein F, a protein with important functions, including porin activity, maintenance of structural integrity, and sensing of host immune system activation. Consistent with this, the use of an isogenic mutant deficient in outer membrane protein F negated the role of NE in host defense against P. aeruginosa infection.     

UHPLC/HR‐ESI‐MS/MS Profiling of Phenolics from Tunisian Lycium arabicum Boiss. Antioxidant and Anti‐lipase Activities’ Evaluation

This study was performed in the aim to evaluate nine different extracts from Tunisian Lycium arabicum for their total phenolic and total flavonoid contents, phytochemical analyses as well as their antioxidant and anti‐lipase activities. The in vitro antioxidant property was investigated using three complementary methods (DPPH, ferric reducing antioxidant power (FRAP), and β‐carotene‐linoleic acid bleaching assays) while anti‐lipase activity was evaluated using 4‐methylumbelliferyl oleate method. From all of the tested extracts the most potent found to be the polar MeOH extracts especially those of stems and leaves. In order to investigate the chemical composition of these extracts and possible correlation of their constituents with the observed activities, an UHPLC/HR‐ESI‐MS/MS analysis was performed. Several compounds belonging to different chemical classes were tentatively identified such as rutin and kampferol rutinoside, the major constituents of the leaves, and N‐caffeoyltyramine, lyciumide A, N‐dihydrocaffeoyltyramine as well as fatty acids: trihydroxyoctadecadienoic acid and hydroxyoctadecadienoic acid isomers were detected abundantly in the stems. These results showed that the MeOH extracts of stems and leaves of L. arabicum can be considered as a potential source of biological active compounds.     

Identification and natural functions of cyclic lipopeptides from Bacillus amyloliquefaciens An6

Lipopeptides constitute a structurally diverse group of metabolites produced by various bacterial and fungal genera. In the past decades, research on lipopeptides has been fueled by their surfactant activities. However, natural functions of lipopeptides compounds have received considerably less attention. The aim of this study was to isolate and identify the lipopeptides from Bacillus amyloliquefaciens An6, and further evaluate their biological activities. An6 lipopeptides were detected by PCR using degenerated primers and MALDI‐TOF‐MS. An6 strain was found to produce surfactin, fengycin, and bacillomycin. Following their purification, the in vitro antioxidant activity of An6 lipopeptides was studied through different assays. The scavenging effect on 1,1‐diphenyl‐2‐picrylhydrazyl radicals at a dosage of 0.75 mg/mL was 81%. Its reducing power was concentration‐dependant and reached a maximum of 1.07 at 2.5 mg/mL. Moreover, they showed a strong inhibition of β‐carotene bleaching. An6 lipopeptides mixture was also found to display significant antimicrobial activity against several Gram‐positive, Gram‐negative bacteria, and fungal strains. An6 lipopeptides were insensitive to proteolytic enzymes, stable between pH 4.0 and 12.0, and resistant to high temperature. Our results provided enough evidence proving that An6 lipopeptides could be used as functional‐food components.