Monitoring of enzymatic reactions using capillary electrophoresis with conductivity detection

Capillary electrophoresis combined with contactless conductivity detection allows to separate and detect the ionic species, which are neither UV absorbing nor fluorescent. This thesis focuses on the applications of this method on enzymatic reactions in different analytical tasks. First, the non-ionic species ethanol, glucose, ethyl acetate and ethyl butyrate were made accessible for analysis by capillary electrophoresis via charged products or byproducts obtained in enzymatic conversions using hexokinase, glucose oxidase, alcohol dehydrogenase and esterase. The conversion of glucose and that of ethylacetate were also successfully demonstrated on a microchip-device. Quantification of ethyl acetate, was found possible with a detection limit of approximately 7 μM. Then the model of urea catalyzed by urease was chosen for the study of the enzymatic mechanism, the effect of substrate concentration and pH value as well as the Michaelis-Menten constant. The determination of urea in human blood as clinical application of this enzymatic reaction was tested. 10 human blood samples were collected from a hospital and analyzed. The results were comparable with the established methods. The method was then extended to proteome analysis; identification of proteins is generally achieved through proteolytic digestion with enzymes such as pepsin and trypsin. Protein digestion with pepsin and trypsin was successfully monitored by capillary electrophoresis. Minigastrin I, myoglobin, cytochrome C, human serum albumin and bovine serum album were the model proteins digested by pepsin, cytochrome C and myoglobin were the model proteins digested by trypsin. Electrophoretically mediated micro-analysis (EMMA) technique is employed for the tryptic digestion of cytochrome C and apomyoglobin. Finally, the enantioselective hydrolysis of esters of amino acids with lipase was monitored. Porcine pancreas lipase was found to have a better efficiency on hydrolysis and enantioselectivity than wheat germ lipase. L-threonine methyl ester demonstrated stronger enantioselectivity than L-serine methyl ester. Acetylcholinesterase inhibitors can be used as drug against Alzheimer disease or nerve agents. Three compounds, namely galantamine, paraoxon and Huperzine-A, were the model inhibitors to study the behavior and kinetics of the inhibitors. The values of IC50 were obtained through graphical plot. Their dependence on the time course was monitored and graphically illustrated

DNA Sequence-Mediated, Evolutionarily Rapid Redistribution of Meiotic Recombination Hotspots: Commentary on Genetics 182: 459–469 and Genetics 187: 385–396

Hotspots regulate the position and frequency of Spo11 (Rec12)-initiated meiotic recombination, but paradoxically they are suicidal and are somehow resurrected elsewhere in the genome. After the DNA sequence-dependent activation of hotspots was discovered in fission yeast, nearly two decades elapsed before the key realizations that (A) DNA site-dependent regulation is broadly conserved and (B) individual eukaryotes have multiple different DNA sequence motifs that activate hotspots. From our perspective, such findings provide a conceptually straightforward solution to the hotspot paradox and can explain other, seemingly complex features of meiotic recombination. We describe how a small number of single-base-pair substitutions can generate hotspots de novo and dramatically alter their distribution in the genome. This model also shows how equilibrium rate kinetics could maintain the presence of hotspots over evolutionary timescales, without strong selective pressures invoked previously, and explains why hotspots localize preferentially to intergenic regions and introns. The model is robust enough to account for all hotspots of humans and chimpanzees repositioned since their divergence from the latest common ancestor

Tubiclavoides striatum gen. nov et sp nov (Cnidaria : Hydrozoa) a new bathyal hydroid from the Gulf of Cadiz, north-east Atlantic Ocean

Tubiclavoides striatum, a new species of an athecate hydroid, was found on mud volcanoes, inactive carbonate clumneys, and cold-water coral stands in the Gulf of Cadiz (south-western Iberian Peninsula, Atlantic Ocean). The new family Tubiclavoididae and the new genus Tubiclavoides are proposed to accommodate the new species. The new hydroid is characterized by scattered filiform tentacles, sporosacs developing among the tentacles and hydrocauli covered with striated perisarc, often subdivided into imbricating cones. A full description and illustrations are provided, as well as some notes on the ecology and distribution of the new species

10 Points in Dimension 4 not Projectively Equivalent to the Vertices of a Convex Polytope

AbstractUsing oriented matroids, and with the help of a computer, we have found a set of 10 points inR4 not projectively equivalent to the vertices of a convex polytope. This result confirms a conjecture of Larman [6] in dimension 4

A holistic perspective on continuing care for substance use and dependence: Results and implications from an in-depth study of a Norwegian continuing care establishment

This article explores, systematically and in depth, users’ perceptions of participating in a Norwegian non-profit establishment that provides a continuing care programme for substance use and dependence. Identified results are linked to a holistic system perspective, where human, technology, and organisation (HTO), as well as external environment, are viewed as intertwined. At the establishment level, i.e., where the continuing care programme is delivered, we find that a clear holistic and user-oriented profile – comprising combined interventions including physical and social activities – can create a safe and stable environment that exerts a positive mental and physical influence on the user and thereby promotes abstinence from substances. However, our results suggest that the internal environment needs to connect more strongly with the external environment, such as a substance-free network, close family, and working life. At the establishment level, we conclude that there is a need to develop an explicit strategy and practice for collaborating with the external environment, built on systemisation and application of individual users’ insights into the design of the current interventions. Further research should explore the presence and absence of interplays between elements of human, technology, and organisation and the external environment, and the associated consequences for intervention processes and users’ health outcomes. Our holistic system model, empirically informed by data from a Norwegian context, can represent a starting point for such endeavours. The holistic system model also constitutes an original and novel contribution to research on continuing care interventions.publishedVersio

Identification of the polyp stage of three leptomedusa species using DNA barcoding

DNA sequence data of hydromedusae and hydroids collected in the fjords near Bergen, Norway, permitted to connect three leptomedusae to three thecate hydroids with hitherto unknown life cycles. For all three species pairs, identical 16S and 18S sequences could be found. For comparisons, estimates of intraspecifi c variation of 16S sequences of other leptomedusa species were determined by comparing specimens collected at different localities. The sequence comparisons allowed us to conclude that Ptychogena crocea Kramp & Dumas, 1925 is the medusa stage of the hydroid Stegopoma plicatile (M. Sars, 1863), Earleria quadrata (Hosia & Pages, 2007) the medusa of Racemoramus panicula (G.O. Sars, 1874), and Cyclocanna welshi Bigelow, 1918 the medusa of Egmundella producta (G.O. Sars, 1874). Due to non-matching geographic distribution patterns of the medusa and hydroid phases, as well as the possibility that other related medusa species may have morphologically identical hydroids, the identities of Stegopoma plicatile and Racemoramus panicula are considered ambiguous. These nominal species likely refer to species complexes. Their names are therefore considered as partial synonyms of the medusa-based names and the latter should remain in use despite being more recent. Cyclocanna welshi and Egmundella producta are recognised as synonyms, and the species should from now on be referred to as Cyclocanna producta (G.O. Sars, 1874) n. comb.publishedVersio