The Influence of Mark-Recapture Sampling Effort on Estimates of Rock Lobster Survival

Five annual capture-mark-recapture surveys on Jasus edwardsii were used to evaluate the effect of sample size and fishing effort on the precision of estimated survival probability. Datasets of different numbers of individual lobsters (ranging from 200 to 1,000 lobsters) were created by random subsampling from each annual survey. This process of random subsampling was also used to create 12 datasets of different levels of effort based on three levels of the number of traps (15, 30 and 50 traps per day) and four levels of the number of sampling-days (2, 4, 6 and 7 days). The most parsimonious Cormack-Jolly-Seber (CJS) model for estimating survival probability shifted from a constant model towards sex-dependent models with increasing sample size and effort. A sample of 500 lobsters or 50 traps used on four consecutive sampling-days was required for obtaining precise survival estimations for males and females, separately. Reduced sampling effort of 30 traps over four sampling days was sufficient if a survival estimate for both sexes combined was sufficient for management of the fishery.     

The Novel Extracellular Cyclophilin A (CyPA) - Inhibitor MM284 Reduces Myocardial Inflammation and Remodeling in a Mouse Model of Troponin I -Induced Myocarditis

Cyclophilins are a group of highly conserved cytosolic enzymes that have a peptidylprolyl cis/trans isomerase activity. Cyclophilin A (CyPA) can be secreted in the extracellular space by inflammatory cells and upon cell death. The presence of CyPA in patients with non-ischemic cardiomyopathy is associated with poor clinical prognosis. Here, we investigated the inhibition of extracellular CyPA in a mouse model of troponin I-induced autoimmune myocarditis using the strictly extracellular CyPA-inhibitor MM284. Since A/J mice develop severe inflammation and fibrosis after immunization with murine cardiac troponin I (mcTn I), we used this model to analyze the effects of an extracellular CyPA inhibition. As extracellular CyPA-inhibitor we used the recently described CsA-derivate MM284. In vitro studies confirmed that MM284 inhibits CyPA-induced monocytic migration and adhesion. A/J mice immunized with mcTnI were treated with MM284 or vehicle every second day. After 28 days, we found a considerable reduction of myocardial injury and fibrosis. Further analysis revealed a reduced myocardial presence of T-cells and macrophages compared to control treated animals. Whereas MMP-9 expression was reduced significantly by MM284, we observed no significant reduction of inflammatory cytokines such as IL-6 or TNFα. Extracellular CyPA plays an important role in autoimmune myocarditis for myocardial damage and fibrosis. Our data suggest a new pharmacological approach for the treatment of myocardial inflammation and reduction of cardiac fibrosis by inhibition of extracellular CyPA.     

Purification,Characterization, and Substrate Specificity of a Novel Highly Glucose-Tolerant β-Glucosidase from Aspergillus oryzae

Aspergillus oryzae was found to secrete two distinct β-glucosidases when it was grown in liquid culture on various substrates. The major form had a molecular mass of 130 kDa and was highly inhibited by glucose. The minor form, which was induced most effectively on quercetin (3,3′,4′,5,7-pentahydroxyflavone)-rich medium, represented no more than 18% of total β-glucosidase activity but exhibited a high tolerance to glucose inhibition. This highly glucose-tolerant β-glucosidase (designated HGT-BG) was purified to homogeneity by ammonium sulfate precipitation, gel filtration, and anion-exchange chromatography. HGT-BG is a monomeric protein with an apparent molecular mass of 43 kDa and a pI of 4.2 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing polyacrylamide gel electrophoresis, respectively. Using p-nitrophenyl-β-d-glucoside as the substrate, we found that the enzyme was optimally active at 50°C and pH 5.0 and had a specific activity of 1,066 μmol min⁻¹ mg of protein⁻¹ and a K_m of 0.55 mM under these conditions. The enzyme is particularly resistant to inhibition by glucose (K_i, 1.36 M) or glucono-δ-lactone (K_i, 12.5 mM), another powerful β-glucosidase inhibitor present in wine. A comparison of the enzyme activities on various glycosidic substrates indicated that HGT-BG is a broad-specificity type of fungal β-glucosidase. It exhibits exoglucanase activity and hydrolyzes (1→3)- and (1→6)-β-glucosidic linkages most effectively. This enzyme was able to release flavor compounds, such as geraniol, nerol, and linalol, from the corresponding monoterpenyl-β-d-glucosides in a grape must (pH 2.9, 90 g of glucose liter⁻¹). Other flavor precursors (benzyl- and 2-phenylethyl-β-d-glucosides) and prunin (4′,5,7-trihydroxyflavanone-7-glucoside), which contribute to the bitterness of citrus juices, are also substrates of the enzyme. Thus, this novel β-glucosidase is of great potential interest in wine and fruit juice processing because it releases aromatic compounds from flavorless glucosidic precursors.β-Glucoside glucohydrolases, commonly called β-glucosidases, catalyze the hydrolysis of alkyl- and aryl-β-glucosides, as well as diglucosides and oligosaccharides. These enzymes are widely used in various biotechnological processes, including the production of fuel ethanol from cellulosic agricultural residues (4, 27, 48) and the synthesis of useful β-glucosides (21, 38). In the flavor industry, β-glucosidases are also key enzymes in the enzymatic release of aromatic compounds from glucosidic precursors present in fruits and fermentating products (13, 39). Indeed, many natural flavor compounds, such as monoterpenols, C-13 norisoprenoids, and shikimate-derived compounds, accumulate in fruits as flavorless precursors linked to mono- or diglycosides and require enzymatic or acidic hydrolysis for the liberation of their fragrances (41, 45). Finally, β-glucosidases can also improve the organoleptic properties of citrus fruit juices, in which the bitterness is in part due to a glucosidic compound, naringin (4′,5,7-trihydroxyflavanone-7-rhamnoglucoside), whose hydrolysis requires, in succession, an α-rhamnosidase and a β-glucosidase (33).It is now well-established that certain monoterpenols of grapes (e.g., linalol, geraniol, nerol, citronelol, α-terpineol, and linalol oxide), which are linked to diglycosides, such as 6-O-α-l-rhamnopyranosyl-, 6-O-α-l-arabinofuranosyl-, and 6-O-β-d-apiofuranosyl-β-d-glucosides, contribute significantly to the flavor of wine (15, 44). The enzymatic hydrolysis of these compounds requires a sequential reaction; first, an α-l-rhamnosidase, an α-l-arabinofuranosidase, or a β-d-apiofuranosidase cleaves the (1→6) osidic linkage, and then, the flavor compounds are liberated from the monoglucosides by the action of a β-glucosidase (18, 19). Unlike acidic hydrolysis, enzymatic hydrolysis is highly efficient and does not result in modifications of the aromatic character (16). However, grape and yeast glucosidases exhibit limited activity on monoterpenyl-glucosides during winemaking, and a large fraction of the aromatic precursors remains unprocessed (9, 16, 35). The addition of exogenous β-glucosidase during or following fermentation has been found to be the most effective way to improve the hydrolysis of the glycoconjugated aroma compounds in order to enhance wine flavor (2, 14, 39, 40). The ideal β-glucosidase should function and be stable at a low pH value (pH 2.5 to 3.8) and should be active at a high concentration of glucose (10 to 20%) and in the presence of 10 to 15% ethanol. However, most microbial β-glucosidases are very sensitive to glucose inhibition (4, 12, 47), as well as to inhibition by glucono-δ-lactone, another powerful β-glucosidase inhibitor produced by grape-attacking fungi which can be found in wine must at concentrations up to 2 g/liter (10).The need for more suitable enzymes has led us and other workers to search for novel β-glucosidases with the desired properties. Recently, we showed that an extracellular glucose-tolerant and pH-stable β-glucosidase can be produced by Aspergillus strains (17). However, the enzyme of interest represented only a minor fraction of total β-glucosidase activity, and the major form was highly sensitive to glucose inhibition. Aspergillus oryzae appeared to be the best producer of the minor form when it was grown on quercetin (3,3′,4′,5,7-pentahydroxyflavone), a phenolic flavonoid found in plant cell walls. This paper presents further data on the production and characterization of this novel highly glucose-tolerant β-glucosidase (designated HGT-BG) purified from the extracellular culture filtrate of A. oryzae grown on quercetin.     

嗜盐细菌中四氢嘧啶和羟基四氢嘧啶的生物合成及其生物学功能

在嗜盐细菌盐适应中,四氢嘧啶(1,4,5,6-四氢-2-甲基-4-嘧啶羧酸)和羟基四氢嘧啶(1,4,5,6-四氢-2-甲基-5-羟基-4-嘧啶羧酸)发挥着十分重要的作用.四氢嘧啶的生物合成以L-天冬氨酸-β-半醛(ASA)为底物,依次由2,4.二氨基丁酸转氨酶(EctB),2,4--氨基丁酸乙酰基转移酶(EctA)和四...     

Biotransformation of C13-norisoprenoids and monoterpenes by a cell suspension culture of cv. Gamay (Vitis vinifera)

A cell suspension culture of cv. Gamay was studied for its ability to metabolize two different C₁₃-norisoprenoidic volatiles, β-ionone and dehydrovomifoliol, together with monoterpenes, geraniol and linalool, biogenetically common pathways sharing compounds. β-Ionone was totally metabolized leading to fourteen norisoprenoidic volatiles oxygenated mainly at carbons 3 or 4 of the cyclohexane ring or reduced at side chain. The biotransformation of dehydrovomifoliol was at a lesser extent, giving rise to oxygenated and reduced derivatives. The norisoprenoidic metabolites were present both under free and glycosylated forms. Geraniol and linalool were also metabolized, leading to several free and glycosylated compounds. S. Mathieu, J. Wirth contributed equally to the work and should be considered joint first authors. A short part of this paper was published at the proceedings of the 10th Weurman Flavour Research Symposium, Flavour Research at the Dawn of the Twenty-first Century, J.-L.Le Quere, P.-X.Etievant, Editors; Lavoisier,2003/Intercept Ltd, 2003.