Probing enzyme promiscuity of SGNH hydrolases

Several hydrolases of the SGNH superfamily, including the lipase SrLip from Streptomyces rimosus (Q93MW7), the acyl-CoA thioesterase I TesA from Pseudomonas aeruginosa (Q9HZY8) and the two lipolytic enzymes EstA (from P. aeruginosa, O33407) and EstP (from Pseudomonas putida, Q88QS0), were examined for promiscuity. These enzymes were tested against four chemically different classes of a total of 34 substrates known to be hydrolysed by esterases, thioesterases, lipases, phospholipases, Tweenases and proteases. Furthermore, they were also analysed with respect to their amino acid sequences and structural homology, and their phylogenetic relationship was determined. The Pseudomonas esterases EstA and EstP each have an N-terminal domain with catalytic activity together with a C-terminal autotransporter domain, and so the hybrid enzymes EstA(N)-EstP(C) and EstP(N)-EstA(C) were constructed by swapping the corresponding N- and C-terminal domains, and their hydrolytic activities were compared. Interestingly, substrate specificity and kinetic measurements indicated a significant influence of the autotransporter domains on the catalytic activities of these enzymes in solution. TesA, EstA and EstP were shown to function as esterases with different affinities and catalytic efficacies towards p-nitrophenyl butyrate. Of all the enzymes tested, only SrLip revealed lipase, phospholipase, esterase, thioesterase and Tweenase activities.     

Anoxic mineralization of biogenic debris in near-shore marine sediments (Gulf of Trieste, northern Adriatic)

Anoxic degradation of sedimentary biogenic debris using closed incubation experiments was studied at two sampling stations in the Gulf of Trieste (northern Adriatic). Production rates of dissolved inorganic carbon (DIC), NH4+, PO(4)3- and dissolved Si (dSi), and reduction rates of SO(4)2- were measured and anoxic mineralization rates were modeled using a first order G-model and multi-G approach. The depth profiles of these rates revealed an exponential decrease indicating that the largest fraction of mineralization of biogenic debris and SO(4)2- reduction occurs in the surficial sediment layer and on the sediment surface. Comparing the depth-integrated anoxic mineralization rates at both stations with benthic fluxes of DIC, NH4+, PO(4)3- and dSi measured at the in situ temperature in the dark, it appears that the DIC and PO(4)3- fluxes are higher because the mineralization mostly occurs at the sediment-water interface, and that besides SO(4)2- reduction, other electron acceptors are involved in the organic matter decomposition pathway in these surficial sediments. The NH4+ production was higher than the benthic fluxes because of NH4+ oxidation. The production of dSi was in good agreement with benthic fluxes implying that temperature is the main factor of dSi production and benthic fluxes in these sediments.     

Nutritional pork meat compounds as affected by ham dry-curing

This work is focused on the determination of compounds of nutritional interest that are naturally present in pork meat and how they are affected during the processing of dry-cured ham. Such compounds are creatine, creatinine, coenzyme Q₁₀, glutathione, carnosine, anserine, carnitine, taurine, cystine, cysteine and the essential amino acids. Their antioxidant and antyhipertensive functions were evaluated. Of all the assayed substances, only glutathione decreased totally during processing. Carnosine, creatinine, anserine and glutathione showed antioxidant, while cysteine, glutathione and carnosine showed antyhipertensive activity. So, dry-cured ham constitutes an excellent source of essential amino acids (all essential amino acids exhibited a large increase during processing) and other nutritionally interesting compounds such as cystine, cysteine, carnosine, anserine, taurine, carnitine and coenzyme Q₁₀.     

Brain Metastases from Lung Cancer Show Increased Expression of DVL1, DVL3 and Beta-Catenin and Down-Regulation of E-Cadherin

The susceptibility of brain to secondary formation from lung cancer primaries is a well-known phenomenon. In contrast, the molecular basis for invasion and metastasis to the brain is largely unknown. In the present study, 31 brain metastases that originated from primary lung carcinomas were analyzed regarding over expression of Dishevelled-1 (DVL1), Dishevelled-3 (DVL3), E-cadherin (CDH1) and beta-catenin (CTNNB1). Protein expressions and localizations were analyzed by immunohistochemistry. Genetic alterations of E-cadherin were tested by polymerase chain reaction (PCR)/loss of heterozygosity (LOH). Heteroduplex was used to investigate mutations in beta-catenin. DVL1 and DVL3 showed over expression in brain metastasis in 87.1% and 90.3% of samples respectively. Nuclear staining was observed in 54.8% of cases for DVL1 and 53.3% for DVL3. The main effector of the Wnt signaling, beta-catenin, was up-regulated in 56%, and transferred to the nucleus in 36% of metastases. When DVL1 and DVL3 were up-regulated the number of cases with nuclear beta-catenin significantly increased (p = 0.0001). Down-regulation of E-cadherin was observed in 80% of samples. Genetic analysis showed 36% of samples with LOH of the CDH1. In comparison to other lung cancer pathologies, the diagnoses adenocarcinoma and small cell lung cancer (SCLC) were significantly associated to CDH1 LOH (p = 0.001). Microsatellite instability was detected in one metastasis from adenocarcinoma. Exon 3 of beta-catenin was not targeted. Altered expression of Dishevelled-1, Dishevelled-3, E-cadherin and beta-catenin were present in brain metastases which indicates that Wnt signaling is important and may contribute to better understanding of genetic profile conditioning lung cancer metastasis to the brain.     

Nutrient fluxes and sulfur cycling in the organic-rich sediment of Makirina Bay (Central Dalmatia, Croatia)

Fluxes of dissolved nutrients in the organic-rich sediment of Makirina Bay (Croatia) were estimated in in-situ incubation experiments and compared to those calculated from a diagenetic model based on the concentration vs. depth profiles in the pore water extracted from a sediment core at the same sampling site. Benthic fluxes observed in the in-situ experiment were strongly influenced by the decomposition of sedimentary organic matter by bacterial sulfate reduction and precipitation of authigenic pyrite and calcite. Assimilation of dissolved nitrate and ammonia within the sediment resulted in peculiar nitrate and ammonia concentration profiles. Differences between the benthic and diffusive fluxes indicated that the effects of bioturbation and irrigation, which were not taken into account in the model calculation of diffusive fluxes, should not be considered as negligible. They are, however, extremely difficult to estimate because of the heterogeneity of the sediment. Sulfate reduction in the pore water could not be detected, although it was obvious from pyrite precipitation and the isotopic compositions of different sedimentary sulfur species. It is suggested that reoxidation of sulfide and upward diffusion of sulfate from the sediment layer accumulated during past salt production can account for the scattered sulfate vs. depth profile. The distribution and stable isotope compositions of sedimentary sulfur species were studied in more detail. The influx of sulfate was explained by rapid sulfate reduction in the sediment. The sulfate reduction rate was highest in the upper part of the sediment column, as concluded from delta(34)S values. In lower horizons, the concentration of organic sulfur increased, while concentrations of sulfide decreased. The mirror-imaged concentration vs. depth profiles of sulfide and organic sulfur, as well as their stable isotopic compositions, show that they were formed simultaneously, most probably in competitive processes.     

Performance of Block Cosine Image Coding with Adaptive Quantization

Quantizers for block transform image coding systems are typically designed under the assumption of Gaussian statistics for the transform coefficients. While convincing arguments can be provided in support of this approach, empirical evidence is presented demonstrating that, except possibly for the dc term, wide departures from Gaussian behavior can be expected for real-world imagery at typical block sizes. In this paper we describe the performance of a block cosine image coding system with an adaptive quantizer matched to the statistics of the transform coefficients. The adaptive quantizer is based upon a recently developed algorithm which employs a training sequence in the design procedure. At encoding rates of approximately 1 bit/pixel and above, this approach results in significant improvement in reconstructed image quality compared to fixed quantization schemes designed under the Gaussian assumption. For rates much below 1 bit/pixel the relative improvement is negligible.     

Characterization of traditional Istrian dry-cured ham by means of physical and chemical analyses and volatile compounds

The aroma-active compounds of Istrian dry-cured ham were investigated by using headspace-solid phase microextraction and gas chromatography-mass spectrometry (GC-MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics: moisture, protein, fat, ash and NaCl content, a(w) value; colour: L*, a*, b* and oxidation of fat: TBARS test. About 50 volatile compounds were identified and quantified which belonged to several classes of chemical: 5 alcohols, 8 aldehydes, 7 alkanes, 1 ketone, 2 esters, 9 monoterpenes and 15 sesquiterpenes. Except volatile compounds derived from lipolysis and proteolysis the most abundant constituents were terpenes (62.97; 41.43%) that originate from spices added in the salting phase of the production process.     

Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham

The aim of this work was to determine the characteristics of Istrian dry-cured ham by instrumental methods and sensory analysis. The aroma-active compounds of Istrian dry-cured ham from 2010 and 2012 were investigated by using headspace-solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics. 92 volatile aroma compounds of Istrian dry-cured ham were found. Volatile compounds belonged to several chemical groups: aldehydes (51.4; 51.3%), terpenes (16.5; 16.4%), alcohols (15.5; 13.2%), ketones (8.6; 7.4%), alkanes (3.8; 5.7%), esters (1.3; 1.6%), aromatic hydrocarbons (0.8; 3.9%) and acids (0.6; 0.9%). Principal component analysis (PCA) showed that fat content, tenderness and melting texture were positively correlated. Terpenes were strongly correlated with flavour of added spices. Sweet taste and the presence of esters were positively correlated as well as negative odour, raw meat flavour and water content.