Alternative final steps in berberine biosynthesis in Coptis japonica cell cultures

In Coptis japonica cell cultures an alternative pathway has been discovered which leads from (S)-tetrahydrocolumbamine via (S)-canadine to berberine. The two enzymes involved have been partially purified. (S)-Tetrahydrocolumbamine is stereospecifically transformed into (S)-canadine under formation of the methylenedioxy bridge in ring A. This new enzyme was named (S)-canadine synthase. (S)-Canadine in turn is stereospecifically dehydrogenated to berberine by an oxidase, (S)-canadine oxidase (COX), which was partially purified (25-fold). This enzyme has many physical properties in common with the already known (S)-tetrahydroprotoberberine oxidase from Berberis but grossly differs from the latter enzyme in its cofactor requirement (Fe) and its substrate specificity. Neither (S)-norreticuline nor (S)-scoulerine serves as substrate for the Coptis enzyme, while both substrates are readily oxidized by the Berberis enzyme. The four terminal enzymes catalyzing the pathway from (S)-reticuline to berberine are housed in Berberis as well as in Coptis in smooth vesicles with a density of =1.14 g/ml. These vesicles have been enriched and characterized by electron microscopy

A comparison of the satiating properties of medium-chain triglycerides and conjugated linoleic acid in participants with healthy weight and overweight or obesity

Purpose Inconsistent evidence exists for greater satiety after medium-chain triglycerides (MCT) or conjugated linoleic acid (CLA) compared to long-chain triglycerides (LCT). Furthermore, the mechanisms are poorly understood and effects in people with a healthy weight and those with overweight/obesity have not been compared. This study aimed to compare appetite responses in these groups and examine the mechanisms behind any differences. Methods Fifteen participants with healthy weight (BMI: 22.7 ± 1.9 kg·m−2) and fourteen participants with overweight/obesity (BMI: 30.9 ± 3.9 kg·m−2) consumed a breakfast containing either 23.06 g vegetable oil (CON), 25.00 g MCT oil (MCT), or 6.25 g CLA and 16.80 g vegetable oil (CLA). Appetite, peptide YY (PYY), total ghrelin (TG), β-hydroxybutyrate, and gastric emptying (GE) were measured throughout. Energy intake was assessed at an ad libitum lunch and throughout the following ~ 36 h. Results Neither MCT nor CLA decreased ad libitum intake; however MCT decreased day 1 energy intake (P = 0.031) and the 48-h period (P = 0.005) compared to CON. MCT delayed GE (P ≤ 0.01) compared to CON, whereas CLA did not. PYY and TG concentrations were not different (P = 0.743 and P = 0.188, respectively), but MCT increased β-hydroxybutyrate concentrations compared to CON (P = 0.005) and CLA (P < 0.001). β-hydroxybutyrate concentrations were higher in participants with overweight/obesity (P = 0.009). Conclusion Consumption of MCT reduces energy intake in the subsequent 48 h, whereas CLA does not. Delayed gastric emptying or increased β-hydroxybutyrate concentrations may mediate this

Diagrammatic Approach for the High-Temperature Regime of Quantum Hall Transitions

We use a general diagrammatic formalism based on a local conductivity approach to compute electronic transport in continuous media with long-range disorder, in the absence of quantum interference effects. The method allows us then to investigate the interplay of dissipative processes and random drifting of electronic trajectories in the high-temperature regime of quantum Hall transitions. We obtain that the longitudinal conductance \sigma_{xx} scales with an exponent {\kappa}=0.767\pm0.002 in agreement with the value {\kappa}=10/13 conjectured from analogies to classical percolation. We also derive a microscopic expression for the temperature-dependent peak value of \sigma_{xx}, useful to extract {\kappa} from experiments.Comment: 4+epsilon pages, 5 figures, attached with Supplementary Material. A discussion and a plot of the temperature-dependent longitudinal conductance was added in the final versio

Palermo’s Promise: Victims’ rights and human trafficking

Response to ATR Debate Proposition: ‘Prosecuting trafficking deflects attention from much more important responses and is anyway a waste of time and money

Leadership Behavior in Virtual Communities

The success of open source software like Apache or Linux not only attracts practitioners of IS to look more thoroughly on the development processes of these communities but also attracts researchers to take a closer look on how these communities work. At first glance open source software development is seemingly chaotic and anarchistic (Kuwabara, 2000). However, successful open source software communities like Apache or Linux do have strong leadership, management, and governance structures (apache.org, 2003; Bretthauer, 2002; Fielding, 1999). In these communities single individuals or a group of participants exercise leadership functions and are in charge of the project direction and survival. Currently, a strong focus of the open source software (OSS) literature is especially on the motivation of participants who spend a lot of time and effort without getting a direct monetary compensation. So far, only little is known about how these communities are organized, managed, and governed. This paper will concentrate on successful practices of effective leadership in OSS communities as an example of virtual communities. Specifically, we will look how leadership behaviors influence project performance. A conceptual model of how leadership behaviors influences project performance considering several contingencies will be developed, presented and propositions as well as testable hypotheses will be derived

Learning and Teaching Online: Structuring Computer-Mediated Communication Systems to Support Interaction at a Distance

The aim of this thesis is to investigate the effects and benefits of different ways of structuring conferences in Computer Mediated Communication (CMC) environments for learning. To this end, the thesis uses two studies of a conventional distance learning course in undergraduate computer science which was supplemented with a structured CMC environment. The research was undertaken over a period of twenty months. Tile first theme of the thesis is an investigation of the possibilities of using conference structures to improve navigation and organisation. The second theme of the thesis investigates the likely benefits of such structuring. Categorical analysis was used to find out the extent to which this structure was beneficial to students. The effects and benefits of various CMC structures were assessed through analysis of data collected using a variety of techniques- observation, user opinions, and interpretation of naturally occurring online interactions. Categorical analysis was undertaken with rich data on actual behaviour obtained from online conferences and compared with students' perceptions gathered through open responses in interviews and questionnaires. The categorical analysis used an approach influenced by grounded theory. The pilot study revealed the need for a new staff role to support the structured CMC. This role, called the Interactive Media Facilitator (IMF), was created during the course of the study to design the CMC structure and monitor activity within the structure. A conceptual framework consisting of a three-dimensional taxonomy was created and used to guide the IMF in the development of the broad conference structure in the main study. The framework was also used to organise the fine detail of the different discussion areas within the CMC structure. This taxonomy, developed from elements of online interaction types found in the CMC literature, is a generalisable framework, applicable in a distance learning context to any electronically supplemented course