Improvement of α-l-arabinofuranosidase production by Talaromyces thermophilus and agro-industrial residues saccharification

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.     

Biochemical characterization, cloning, and molecular modelling of chicken pancreatic lipase

Chicken pancreatic lipase (CPL) was purified from delipidated pancreas. Pure CPL was obtained after ammonium sulphate fractionation, then DEAE-cellulose, Sephacryl S-200 gel filtration, and FPLC Mono-Q Sepharose columns. The pure lipase is a glycosylated monomer having a molecular mass of about 50kDa. The 23 N-terminal amino acid residues of CPL were sequenced. The sequence is similar to those of avian and mammalian pancreatic lipases. CPL presents the interfacial activation phenomenon tested with tripropionin or vinyl ester. When CPL was inhibited by synthetic detergent (TX-100) or amphipathic protein (BSA), simultaneous addition of bile salts and colipase was required to restore the full CPL activity. In the absence of colipase and bile salts, CPL was unable to hydrolyse tributyrin emulsion. This enzyme can tolerate, more efficiently than HPL, the accumulation of long-chain free fatty acids at the interface when olive oil emulsion was used as substrate in the absence of bile salts and colipase. The CPL activity, under these conditions, was linear whereas that of HPL decreased rapidly. Anti-TPL polyclonal antibodies cross-reacted specifically with CPL. The gene encoding the mature CPL was cloned and sequenced. The deduced amino acid sequence of the mature lipase shows a high degree of homology with the mammalian pancreatic lipases. A 3D structure model of CPL was built using the HPL structure as template. We have concluded that a slight increase in the exposed hydrophobic residues on the surface of CPL, as compared to HPL, could be responsible for a higher tolerance to the presence of long-chain free fatty acids at the lipid/water interface.     

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.     

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.     

L'éléphantiasis péno-scrotal. A propos d'un cas

Massive scrotal lymphoedema with gross genital deformation is called penoscrotal elephantiasis. It is a rare syndrome outside of filariasis endemic regions. It is usually idiopathic and rarely congenital or secondary. It is both physically disabling and emotionally distressing for the patient. Surgical treatment is often necessary. The authors report a case of a patient with penoscrotal elephantiasis in whom no aetiology could be found. Complete surgical resection of the diseased tissue and scrotum and penile reconstruction were performed with good cosmetic and functional results.     

Crab digestive lipase acting at high temperature: purification and biochemical characterization

In recent years, recovery and characterization of enzymes from fish and aquatic invertebrates have taken place and this had led to the emergence of some interesting new applications of these enzymes. However, much less is known about lipases from crustaceans. A lipolytic activity was located in the crab digestive glands (hepatopancreas), from which a crab digestive lipase (CDL) was purified. Pure CDL has a molecular mass of 65kDa as determined by SDS/PAGE analysis. Unlike known digestive lipases, CDL displayed its maximal activity on long and short-chain triacylglycerols at a temperature of 60 degrees C. A specific activity of 500U/mg or 130U/mg was obtained with TC(4) or olive oil as substrate, respectively. Only 10% of the maximal activity was detected at 37 degrees C. The enzyme retained 80% of its maximal activity when incubated during 10 min at 60 degrees C, and was completely inactivated at a temperature higher than 65 degrees C. Interestingly, neither colipase, nor bile salts were detected in the crab hepatopancreas. Which suggests that colipase evolved in invertebrates simultaneously with the appearance of an exocrine pancreas and a true liver which produce bile salts. No similarity between the 13 N-terminal amino acid residues of CDL was found with those of known other digestive lipases.     

HPLC‐DAD Analysis,Antioxidant and Protective Effects of Tunisian Rhanterium suaveolens against Acetamiprid Induced Oxidative Stress on Mice Erythrocytes

The present study was performed to assess the HPLC‐DAD analysis as well as antioxidant and protective effects of Tunisian Rhanterium suaveolens (Rs) against acetamiprid (ACT) induced oxidative stress on mice erythrocytes. The in vitro assays showed that the methanolic extract of Rs has an impressive antioxidant effect proved by testing the total antioxidant and scavenging activities using BCB, DPPH and ABTS assays, respectively. Moreover, qualitative and quantitative analysis using HPLC‐DAD revealed the richness of Rs in polyphenols where p‐Coumaric, Apigenin‐7‐glucoside and Ferulic acid were detected as the most abundant polyphenols. In the in vivo experiment, ACT, used as a toxicity model, was given to mice at a dose of 20 mg/kg. The latter was the origin of hemolytic anemia characterized by a significant decrease in red blood cells, hemoglobin and hematocrit levels and an increase in bilirubin, LDH, osmotic fragility, reticulocytes and white blood cells number. Characteristic erythrocyte morphological alterations were also determined as spherocytosis, schistocytosis and dacryocystitis. The oxidative status of ACT‐treated mice was also altered manifested by a significant increase in MDA and GSH levels and a decrease in SOD, CAT and GPx activities. When receiving the Rs methanolic extract at a dose of 300 mg/kg, all the parameters cited above were restored in mice. These remarkable corrections could only confirm the important antioxidant effect and the noticeable protective properties that possess Rs owing to its broad range of secondary bioactive metabolites.     

Variation of steroid concentrations during the reproductive cycle of the clam Ruditapes decussatus: a one year study in the gulf of Gabès area

Progesterone, testosterone and estradiol-17beta were measured by radio-immunoassay (RIA) in the gonads of the clam Ruditapes decussatus. The reproductive cycle was also investigated. Our study covered a period of one year, from September 2003 to August 2004. The chosen site "Kerkennah", located out of industrial effluents, belongs to the gulf of Gabès area (Tunisia). Steroids varied from 178 to 2459 pg g(-1) wet mass for progesterone, from 40 to 326 pg g(-1) wet mass for testosterone and from 10 to 235 pg g(-1) wet mass for estradiol-17beta in females. However in males, these steroids ranged from 304 to 2303 pg g(-1) wet mass for progesterone, from 81 to 381 pg g(-1) wet mass for testosterone and from 48 to 168 pg g(-1) wet mass for estradiol-17beta. The reproductive cycle of R. decussatus, investigated by histological examination of gonadic sections, showed that gametogenesis occurred from April to February in males and from April to November in females. Progesterone and testosterone increased at the end of gametogenesis in both sexes. The highest estradiol-17beta was recorded at the beginning of vitellogenesis in females. Fluctuations in the levels of sex steroids during the reproductive cycle suggest their possible role as endogenous modulators of gametogenesis in R. decussatus. Although this species is considered as gonochoristic, 0.83% of hermaphrodites were observed.     

Time-dependent effects of exposure to static magnetic field on glucose and lipid metabolism in rat

In the following study, we investigate the effects of static magnetic field (SMF) (128 mT, 1 h/day during 5 or 15 consecutive days) on anthropometric parameters, glucose and lipid metabolism in rats. Exposure to SMF during 5 days induced a decrease (-8%, p < 0.05) in relative liver weight and serum insulin concentration (-56%, p < 0.001), while blood glucose level was increased (+10%, p < 0.001). By contrast, the same treatment failed to alter body weight, relative kidney weight and levels of lactate, cholesterol, triglycerides and phospholipids. Exposure to SMF during 15 days induced a decrease (-15 %, p < 0.001) in body weight, liver weight (-15 %, p < 0.05), insulin concentration (-63%, p < 0.001), plasmatic lactate level (-55%, p < 0.05) and increased glucose (+24%, p < 0.001), cholesterol (+30%, p < 0.01,) and phospholipids levels (+58%, p < 0.001), whereas, triglycerides decreased (-28%, p < 0.001). These results showed that SMF effects on glucose and lipid metabolism are time-dependent.     

Leberagin-C,A disintegrin-like/cysteine-rich protein from Macrovipera lebetina transmediterranea venom,inhibits alphavbeta3 integrin-mediated cell adhesion

Leberagin-C, a new member of the disintegrin-like/cysteine-rich (D/C) family, was purified to homogeneity from the venom of Tunisian snake Macrovipera lebetina transmediterranea. It is a monomeric protein with a molecular mass of 25,787 Da. Its complete sequence of 205 amino acid residues was established by cDNA cloning. The leberagin-C shows many conserved sequences with other known D/C proteins, like the SECD binding sites and a pattern of 28 cysteines. It is the first purified protein from M. lebetina transmediterranea with only two disintegrin-like/cysteine-rich domains. Leberagin-C is able to inhibit platelet aggregation induced by thrombin and arachidonic acid with IC₅₀ of 40 and 50 nM respectively. It was also able to inhibit the adhesion of melanoma tumour cells on fibrinogen and fibronectin, by interfering with the function of alphavbeta3 and, to a lesser extent, with alphavbeta6 and alpha5beta1 integrins. To our knowledge, leberagin-C is the sole described D/C protein that does not specifically interact with the alpha2beta1 integrin. Structure–activity relationship study of leberagin-C suggested that there are some important amino acid differences with jararhagin, the most studied PIII metalloprotease from Bothrops jararaca, notably around the SECD motif in its disintegrin-like domain. Other regions implicated in leberagin-C specificities could not be excluded.