The distributions of halocarbons in the Amundsen and Ross Seas ar

The distributions of halocarbons in the Amundsen and Ross Seas are mainly influenced by the presence of sea ice. This is supported by several findings: H 89 nmr halocarbon concentrations in surface waters in ice-covered areas exceeded those of the biologically productive surface layer in the two polynyas; elevated concentrations of halocarbons were measured in brine; and surface waters in open waters were under-saturated with respect to bromoform. The halocarbon distribution in the two seas differed considerably, mainly due to the large

Ross Sea polynya and the formation of high salinity shelf water in the western Ross Sea. Halocarbons were found not to be a homogenous group of compounds, and they could be divided into two groups depending on the halogen involved. Iodinated compounds, with relatively shorter environmental half-lives in sea water, could be related to the abundance of Phaeocystis in the Ross Sea, whereas

brominated forms may be related more to community processes in conjunction with the unique physical environment provided by ice and snow. Saturation anomalies for the sea water/air and ice/brine/air systems also showed that sea ice was a major source of naturally produced halocarbons for the atmosphere, and in particular CHBr3 and CH2ClI. It can be concluded that the surface mixed layer of Antarctic seas acts both as a source and a sink for volatile halogenated organic carbons. The following are the supplementary data related to this article. Supplementary material.   Incubation data from 7 ice stations and absolute limit of detection. We thank the officers and crew of Alectinib solubility dmso the R.V.I.B. Oden for their help during the cruise, as well as our OSO 2007 colleagues. We especially thank Daniel Barrdahl for assistance during the expedition. This research was supported by NSF grants ANT-0741380 and ANT-0836112 to

WOS, the Swedish Research Council, Knut och Alice Wallenbergs Foundation, and the Swedish Polar Research Secretariat. Section plots were made in Ocean Data View ( Schlitzer, 2011). “
“Due to its biological necessity, iron (Fe) is a key resource for marine phytoplankton (Geider and La Roche, 1994) and is considered as the limiting nutrient in a number of oceanic regions (Moore et al., 2013). These include the classic DNA ligase high nutrient low chlorophyll regions of the Southern Ocean (de Baar et al., 1995), equatorial Pacific (Martin et al., 1994), sub-Arctic Pacific (Martin and Fitzwater, 1988) and to a lesser extent seasonally in the North Atlantic (Nielsdóttir et al., 2009). Moreover, Fe can also regulate the rates of nitrogen fixation by diazotrophs in tropical regions (Schlosser et al., 2014). Accordingly most ocean general circulation and biogeochemistry models (OGCBMs) that seek to represent ocean biogeochemical cycling, including those concerned with climate change, represent Fe. The process of organic complexation by molecules known as ligands is a key feature of the ocean Fe cycle.

5 h of batch fermentation For the preliminary fed-batch studies,

5 h of batch fermentation. For the preliminary fed-batch studies, two predetermined feeding profiles, namely exponential and constant feeding were preferred. For each feeding profile, three feeding rates were evaluated: 1, 3 and 6 g

glycerol/L/h for constant feeds and 0.1, 0.2 and 0.3 h−1 for exponential feeds. To achieve the desired rates (1, 3 and 6 g glycerol/L/h), several feed mediums with different glycerol concentrations were prepared. For these assays, the three feeding rates were tested as duplicates (A and B), without induction, so that the growth profiles could be established (Fig. 3). In these fed-batch experiences, glycerol was measured as mentioned in Section 2.2.4 until the end of the feeding see more process. The growth curves for these Apitolisib profiles (Fig. 3) show a maximum OD of about 50 which, as expected, is considerably higher than those obtained in the batch experiments. For the 1 g/L/h constant feeding profile, glycerol concentration was kept close to zero until the end of the fed-batch process, meaning that these cultures were able to consume all of the glycerol provided by the feeding

solution. For the 3 g/L/h constant feeding profile, glycerol concentration reached close to zero values only after about 10 h of fed-batch, meaning that limiting concentrations are not reached during most of the fed-batch process. However, the maximum OD reached (52) was very similar to that of the 1 g/L/h feeding profile. Finally, for the 6 g/L/h feeding profile, glycerol concentrations either increased throughout the experiment (replicate A) or were kept constant at relatively low levels (replicate B). Since glycerol concentrations during the fed-batch phase of the feeding profiles evaluated were very different (from almost 0 g/L to as high as 30 g/L), cytometry assays were used to see if the feeding profile of 1 g/L/h was, in

fact, the best choice among the three constant feeding profiles tested. In order to assess cell physiology during the fed-batch experiments, flow cytometry assays were carried out using a PI/BOX dual staining. Dead cells will be stained with both BOX and PI, cells with depolarized membrane will be stained only with BOX and viable cells will not be stained. The results (not shown), indicate that as fermentation time increases, the percentage of dead cells (stained with PI and BOX) also increases. This effect is heightened at Clomifene higher feeding rates, possibly because of the higher glycerol concentrations, which can hamper E. coli growth. In fact, at the end of the fermentation, the average percentages of viable cells were 79.43, 65.84 and 75.61% for 1, 3 and 6 g/L/h, respectively. The three chosen specific growth rates for exponential feeding profiles were 0.1, 0.2 and 0.3 h−1 with feed medium addition speed being calculated according to an equation previously described [14]. For this set of experiments, the three specific growth rates were also performed in duplicates (A and B) without induction (Fig. 4).

This was both in terms of the cell recovery at 24 h post-thaw, an

This was both in terms of the cell recovery at 24 h post-thaw, and minimising differences in doubling time from the non-frozen control. Freezing media consisting of 10% Me2SO and 90% FBS was chosen as the control cryopreservation

media. Media such as this has been widely used in previous studies [23], [36] and [37]. The 24 h cell recovery for the optimum PP-50 concentration (103 ± 4%) was found to be less than that for the Me2SO control (130 ± 14%), AZD0530 although this difference was not statistically significant. In part, this may be explained by proliferation of the SAOS-2 cells during the first 24 h post-thaw. Assuming the cell doubling times remained constant throughout the experiment, the number of viable cells capable of proliferating immediately post-thaw for the PP-50/trehalose and Me2SO protocols was estimated to be comparable (64 ± 5% and 70 ± 11%, respectively). This estimated cryosurvival was similar to that achieved for mesenchymal stem cells by Wang et al. [42]. Hence the cryosurvival of proliferative cells achieved using the PP-50/trehalose treatment may have been comparable to the Me2SO control. It should be noted that MTS assays were not performed on the cells immediately post-thaw, as the presence of early apoptotic cells can yield CT99021 chemical structure misleading results [24],

as could the presence of cells incapable of substrate attachment. The cryosurvival immediately post-thaw was tested further for these protocols, using a flow cytometry based Annexin V/PI assay. The proportion of viable cells for the PP-50/trehalose and

Me2SO protocols were found to be comparable to those calculated above (80 ± 3% and 60 ± 2%, respectively). This could indicate that there is not a significant sub-population of cells for either protocol that appears viable, but is non-proliferative during subsequent culture. As discussed previously, Me2SO is currently the cryoprotectant of choice for most cell culture and therapeutic applications. Although FAD there is scope for improving the number of cells that survive the freezing process, the two most concerning problems associated with the use of Me2SO are loss of cell functionality, and toxicity to patients. Therefore, of the outcome measures tested, the comparison of the cell doubling times to the non-frozen control was thought to be the more important. It was found that the rate of proliferation was abnormally high for the cells cryopreserved using Me2SO compared to non-frozen SAOS-2 cells (Fig. 5). Indeed the cell doubling times were found to be significantly different from the non-frozen control by 41 ± 4%. In contrast, the doubling time for the cells cryopreserved using the optimum PP-50/trehalose protocol did not significantly affect the doubling time (Fig. 6). These data suggest that the normal processes of the cells were affected less when cryopreserved using PP-50/trehalose than Me2SO, while maintaining high cell recovery.

4 × 106 seedlings per hectare The sandy loam soil [Typic Fluvaqu

4 × 106 seedlings per hectare. The sandy loam soil [Typic Fluvaquent, Entisols (US taxonomy)] contains 12.58 g kg− 1

of organic material and 75.19, 45.52 and 99.3 mg kg− 1 of available N, phosphorus and potassium, respectively. Plot dimensions were 4 × 5 m and plots high throughput screening assay were separated by an alley 1 m wide with plastic film inserted into the soil. Each of the treatment had three plots as repetitions in a complete randomized block. The treatment plots received 240 kg ha− 1 at the booting stage. The control plots received no N at the booting stage. All other field conditions and cultivation managements were kept uniform. During the period of wheat anthesis, the anthesis dates were recorded by dotting the glumes and hanging time tags on the wheat plants. Caryopses that bloomed on the same day but developed on different days for the two treatments were chosen for experimentation. Samples were harvested at 15 and 45 DAA. First, 2 mm cubic blocks were

cut by cross-sectioning from wheat caryopses harvested at 15 DAA. The specimens were then fixed with 2.5% glutaraldehyde and 1% paraformaldehyde in a 0.05 mol L− 1 cacodylate buffer solution (pH 7.2) and post-fixation treatment in 1% osmic acid in a 0.15 mol L− 1 sodium cacodylate buffer solution (pH 7.2) for 3 h was applied. The blocks were washed, dehydrated through an ethanol series of 30%–100%, and embedded ERK inhibitor in Spurr’s low-viscosity embedding medium. Sections of 1 μm thick were cut with a glass knife on a Leica Ultracut R (Leica Microsystems, Inc., Wetzlar, Germany), and stained with 0.5% toluidine blue O for 5 min. The sections were visualized and photographed with a Leica Dmls microscope (Leica Microsystems, Inc.). To reflect the nature of caryopsis structure, the findings were compared and confirmed in numerous sections made from

developing grains. Five representative regions of transverse sections of the endosperm were observed for every specimen: subaleurone in dorsal endosperm (SDE), center in dorsal endosperm (CDE), modified aleurone (MA), subaleurone in ventral endosperm (SVE), and center in ventral endosperm (CVE), using three replications O-methylated flavonoid and 20 micrographs representing ten blocks from different regions. Mature grains were harvested at 45 DAA and fractured by applying slight pressure on the middle of the caryopsis with a razor blade. The sample thickness was ~ 3 mm. Caryopses were mounted with the fractured surface facing upwards on a specimen stub and sputter-coated with gold before viewing with a scanning electron microscope (XL30 ESEM, Philips, The Netherlands) at 20 kV to observe the distribution of SGs. The samples at 15 DAA were used to determine the numbers and percentages of SGs. SGs observed in the image were first marked with a specified color using Photoshop CS4 software (Adobe, U.S.A.) and the image was then analyzed to determine the numbers and percentages of SGs using software Image-Pro Plus 6.0 (Media Cybernetics, U.S.A.).

In the Netherlands, postal area code can be linked to aggregated

In the Netherlands, postal area code can be linked to aggregated data on income level, education and type of occupation of Dutch citizens (based on data from Statistics Netherlands) [1]. At the time of the trial, the Netherlands did not have a population-based colorectal cancer screening program. Bleomycin price Invitees were

only allowed to undergo the allocated screening modality. Ethical approval was obtained before study initiation from the Dutch Health Council (2009/03WBO, The Hague, The Netherlands). The trial was registered in the Dutch trial register: NTR1829 ( With the invitation, colonoscopy and CT colonography screening invitees received identically designed leaflets with information on colorectal cancer and colorectal cancer screening. These leaflets were derived from similar leaflets used in previous colorectal cancer screening

pilots. The information leaflet for colonoscopy invitees contained specific information on benefits and risks of colonoscopy, while the information leaflet of CT colonography invitees contained information on benefits and risks of CT colonography. Both leaflets contained information on follow-up in case of a positive test result (e.g. follow-up colonoscopy in case of a positive CT colonography result). Invitees who responded to the invitation were scheduled for a standardized consultation with a research fellow or research nurse to inform them about the bowel preparation and the procedure itself. In the CT colonography group all invitees were invited for a prior consultation by telephone, while in the colonoscopy group ZD1839 order half of invitees were invited for a prior consultation at the outpatient clinic [28]. Data on differences between the two colonoscopy groups were recently published by Stoop et al. [29]. Responders were excluded from participation

when they had undergone a full colonic examination in the previous five years, when they had a life expectancy of less than 5 years, from or when they had been previously scheduled for surveillance colonoscopy because of a personal history of colorectal cancer, adenomatous polyps or inflammatory bowel disease. CT colonography responders were also excluded when they had been exposed to ionizing radiation for research purposes within the previous 12 months or when they had hyperthyroidism or iodine contrast allergy. All invitees received a questionnaire containing previously validated measures of knowledge and an attitude measure based on Marteau’s Multidimensional Measure of Informed Choice [18], [19], [30], [31] and [32]. Screenees received the questionnaire within 4 weeks before the screening procedure with the appointment confirmation, and were asked to return the questionnaire by mail or to bring the questionnaire to the hospital. All invitees who actively declined the invitation received the same questionnaire, as well as those invitees that did not respond within 4 weeks after the initial invitation (together with a reminder letter).

LiRecDT1-GFP binding was evaluated as described above, except tha

LiRecDT1-GFP binding was evaluated as described above, except that B16-F10 cells (0.5 × 103 cells) were incubated

with 10 μg/mL of the recombinant fluorescent toxin (5 h, 37 °C). Non-specific binding of GFP alone to the cells was evaluated as a negative control. For binding competition assays, the fluorescence protocol was the same as described above, except that B16-F10 cells were previously incubated with an excess of LiRecDT1 (100 μg/mL) for 1 h at 37 °C Cyclopamine purchase and then with 10 μg/mL LiRecDT1-GFP. The samples were observed using a Zeiss Axio Observer.Z1 inverted microscope (Carl Zeiss, Germany). Single images were obtained using a 63× oil lens for differential interface contrast (DIC) microscopy and a monochromatic camera (AxioCam HRm, Carl Zeiss) to examine fluorescence intensity. Finally, AxioVision LE software was used for image processing and morphometric measurements in the Zeiss image format ABT 888 (ZVI). B16-F10 cells (1 × 108 cells/mL) were prepared in Ringer’s Solution (122.5 mM NaCl, 5.4 mM KCl, 0.8 mM MgCl2, 10 mM HEPES, 11 mM glucose, 1 mM NaH2PO4, pH 7.4) containing 5 mM CaCl2 and treated according to Kaestner et al. (2006) and Haase et al. (2009). B16-F10 cells were loaded with Fluo-4 AM (10 μM) in buffer with Pluronic F-127 (0.01%) for 30 min at 37 °C. This indicator exhibits high-affinity binding to Ca2+ (Kd = 345 nM)

and shows a large increase in fluorescence intensity in response to Ca2+ binding (>100 fold). Subsequently, the cells were washed not twice with Ringer’s Solution and equilibrated for de-esterification for 30 min at room temperature. Then, the cells were incubated with 25 μg/mL recombinant phospholipase-D (LiRecDT1) for 5, 15, 30, 45, 60 or 90 min.

Cells incubated under the same laboratory conditions but in the absence of phospholipase-D for 90 min were used as a control. Following this reaction, the cells were transferred to Black 96-well plates at a density of 1 × 106 cells/well in a total volume of 200 μL, and the resulting fluorescence was recorded on a Tecan Infinite M200 spectrofluorometer (Tecan) using an excitation wavelength of 485 nm and measuring emission at 535 nm. Additionally, Fluo-4 dye-loaded B16-F10 cells were allowed to settle onto coverslips, and images of calcium-dependent fluorescence were obtained using an Axio Observer.Z1 inverted microscope Zeiss (Carl Zeiss, Germany). Fluo-4 AM was excited at 488 nm, with emission detected using an LP 505 nm filter (green channel). Single images were obtained using a 63× oil lens for differential interface contrast (DIC) microscopy and a monochromatic camera (AxioCam HRm, Zeiss, Carl Zeiss, Germany) to measure the fluorescence intensity. Finally, AxioVision LE software was used for image processing and to perform morphometric measurements in the Zeiss image format (ZVI).

In contrast, Davila et al 100 showed that exosomes, defined as ve

In contrast, Davila et al.100 showed that exosomes, defined as vesicles with a diameter of less than 100 nm, contribute to the overall procoagulant activity of tumor cell derived vesicles. They showed that approximately 20% of the TF coagulant activity was still present after filtration through a 0.1 μm filter, which would indicate a role for exosomes Pirfenidone concentration in coagulation

activation. Unfortunately, they did not investigate whether filtration enables removal of all vesicles larger than 0.1 μm, or whether larger vesicles are fragmented by such a procedure, making the distinction between exosomes and small MVs uncertain. Vesicles act at two levels regarding waste management. Vesicles can contain redundant intracellular components, thus acting as cellular waste disposal bags by their extrusion from the cell. In turn, such vesicles may be removed from the circulation by phagocytosis by other cells. It is tempting to speculate that EVs containing cellular waste are especially equipped to facilitate their clearance, e.g. by exposing

PS, thereby becoming easy targets for phagocytes. There is evidence that the spleen is involved in the clearance of MVs in vivo.100 Thirty minutes after injection click here of PS-exposing MVs from breast or pancreatic cancer cell lines into mice, both TF antigen and TF activity decreased by 72% and 90%, respectively, becoming undetectable 2 h after injection. Already 5 min after injection, the TF antigen was Amisulpride detectable in the spleen. In contrast, in splenectomized mice most of the human TF antigen was still detectable 30 min after injection, and 30% of the splenectomized mice did not survive 2 h after injection. In

humans, clearance of circulating vesicles exposing coagulant TF is extremely fast and efficient. We showed that human wound (pericardial) blood from patients undergoing open heart surgery contains exceptionally high levels of coagulant TF-exposing vesicles that trigger coagulation in vitro91 and thrombus formation in vivo.92 When this wound blood is retransfused, the TF-coagulant activity becomes undetectable in peripheral blood already after 20–30 min, revealing that also in humans clearance of vesicles must be very efficient.101 In pathological conditions, the waste management may not function properly. This could happen because of the failure of the phagocytes to recognize the danger signal[102] and [103] or because these phagocytes are impaired (apoptotic/necrotic).[104], [105] and [106] The consequence is that EVs containing redundant and unwanted biomolecules are not rapidly cleared from the circulation. Thus, these EVs are likely to play a role in the pathological conditions. Monocytes are phagocytes which expose a PS-specific receptor that recognizes PS-exposing vesicles.107 In an in vitro study, human monocytic leukemia cells (THP-1 cells) showed signs of apoptosis or possibly even necrosis after incubation with PS-exposing PMVs containing caspase 3.

In addition, early epithelialization and moderate stricture were

In addition, early epithelialization and moderate stricture were observed by a number of transplanted cell sheets. These endoscopic delivery devices for cell sheet would enable easily transplantation of cell sheets onto the lumen

of the esophagus. Additionally, anti-CTLA-4 antibody a number of allogeneic epidermal cell sheets might be useful for prevention of stricture as well as autologous one. Figure options Download full-size image Download high-quality image (181 K) Download as PowerPoint slide Figure options Download full-size image Download high-quality image (212 K) Download as PowerPoint slide “
“The accepted palliative treatment for malignant gastric outlet obstruction (GOO) is surgical bypass or placement of self-expandable metal stents. Surgical gastrojejunostomy causes morbidity of about 30%. In endoscopic stent placement, because of recurrent obstruction, many have to go through re-intervention. So we developed a safe and durable endoscopic gastrojejunostomy with a fully covered, lumen-apposing metal stent using a porcine model. Under general anesthesia, 11 female Yorkshire pigs underwent gastrojejunostomy PI3K activity with a 4-cm length lumen-apposing metal stent. After gastrotomy formation using a needle knife, the jejunum was drawn into the stomach with alligator forceps. A jejunotomy was then performed in the gastric cavity, which was followed by deployment of a lumen-apposing metal stent

under fluoroscopic guidance. Next, the first portion of the duodenum was resected by an endoscopic linear stapler via laparoscopy, thereby creating the GOO model. Oral feeding was resumed 24 h after the procedure, and animals were euthanized at 1, 2, and 4 weeks after the operation. Side-to-side gastrojejunostomy was successfully completed endoscopically in 10/11

animals. One case failed due to jejunal perforation during jejunotomy. The mean gastrojejunostomy procedure time was 41 min (range 15-94 min). No pigs died before the planned sacrifice date. At the end of 4 weeks, two pigs showed significant weight gain with a maximum increase of 101% from their initial body weight. Histological examination revealed adequate submucosal apposition without evidence of necrotic changes in all 10 experimental pigs. Creating a gastrojejunostomy ever endoscopically using a lumen-apposing metal stent seems to be a safe, feasible, durable, and reproducible method. Schematic diagram of the endoscopic gastrojejunostomy technique by transgastric endoluminal insertion of the GJ stent. “
“With the remarkable growth of disability- and rehabilitation-related research in the last decade, it is imperative that we support the highest quality research possible. With cuts in research funding, rehabilitation research is now under a microscope like never before, and it is critical that we put our best foot forward.

, 1996), and broaden-and-build theory (Fredrickson, 1998 and Fred

, 1996), and broaden-and-build theory (Fredrickson, 1998 and Fredrickson, 2001) to develop and test a model that accounts for individual-level information seeking behaviour, and the contingencies that lead to information seeking as a form of procrastination. Information processing styles, typically characterised as tendencies to use analytical or intuitive (heuristic)

approaches to choice (Dane & Pratt, 2007) influence decision processes and outcomes. Analytical processes are required for Selleck VE 822 novel, complex problems whereas intuitive or heuristic processes are applied to numerous daily choices (Bargh et al., 1996 and Epstein et al., 1992). Theories of analytical and heuristic thinking rest on the dual-process concept which proposes two parallel, interactive

systems of thinking (Epstein, 1990 and Epstein et al., 1996). System 1 is intuitive, affect-laden and rapid. System 2 is cognitive, resource intense and requires time. Both systems yield positive outcomes. Analytical thinking is associated with effective decision making due to logical reasoning and fewer decision biases (Stanovich & West, 2002), and ability to focus on important aspects of information relevant to decisions rather than non-relevant contextual information (McElroy & Seta, 2003). Intuitive thinking is associated with expertise (Dreyfus & Dreyfus, 2005) and effectiveness in solving everyday problems (Todd & Gigerenzer, 2007). While the dual-process model has universal application, the extent to which System 1 and System MG-132 order very 2 are applied, and the situational contingencies that influence their use, are subject to individual differences (Epstein et al., 1996). Therefore, theories that rest on dual-process modelling need to take

into account individual-level antecedents and moderating factors. Employing this approach, Griffin et al. (1999) developed the risk information seeking and processing (RISP) model. They proposed information seeking is driven by individual differences in perceived information sufficiency, and continues until the point of sufficiency is reached. Griffin et al. (1999) placed information seeking and information processing together as the dependent variables in their model, and proposed that they combine to produce four decisions styles relating to routine/non routine and heuristic/systematic processing. However, recent research into decision processes, also building on dual process models, has added a second information processing style: regulatory processes that influence whether a decision should be made immediately or delayed Dewberry, Juanchich, and Narendran (2013a) proposed both cognitive information processing (rationality vs. intuition) and regulatory information processing have direct effects on decision outcomes. For example, when faced with a decision about whether to eat food that could harbour harmful bacteria, there are choices about whether to go with past experience, i.e.

Besides the appropriate pH range, for buffers two further criteri

Besides the appropriate pH range, for buffers two further criteria must be considered, the ionic strength and concentration, and the nature of buffer components. The more concentrated a buffer system, the higher its capacity to stabilize the pH. However, most enzymes accept only moderate ionic strength, PF-02341066 manufacturer commonly between 0.05 and 0.2 M, only halophilic and thermophilic enzymes prefer higher concentrations up to 1 M (Vieille and Zeikus, 2001, Rainey and Oren, 2006 and Gerday, 2007). On the other hand, low ionic strength destabilizes the protein structure. It must be further taken into account that each component of the assay mixture, like substrates,

cofactors, and additives like stabilizing factors (e.g. enzymes are frequently stored in concentrated ammonium sulphate solutions) contributes to the overall concentration. Moreover each addition can influence the adjusted pH, for example when a component (substrate, cofactor, or effector) is added in an acid or alkaline form without previous neutralisation. While the buffer neutralizes

low amounts, this need not be the case with higher amounts. Since any deviation from the pH optimum reduces obligatorily the enzyme activity, such an effect can easily be misinterpreted as enzyme inhibition: the more of the particular component is added, the lower the enzyme activity. The enzyme reaction Vincristine mw itself can cause pH shifts and consequently a continuous decrease of the activity, e.g. if an acid

or alkaline component becomes released during a cleavage reaction, like the liberation of fatty acids by lipase. In such cases only short initial reactions should be measured under continuous control of the actual pH in the solution. Alternatively, the pH can be kept constant applying a pH stat with an auto-burette, containing a neutralizing solution. Thiamet G The amount of this solution required for stabilizing the pH is a direct measure of the reaction rate (Taylor, 1985). Ions influence the enzyme activity both by means of their ionic strength and by their nature. The activity of a distinct enzyme can considerably differ when tested in two distinct buffer systems, even if they share the same pH and concentration. Various reasons are responsible for this behaviour. In some cases components of the buffer, like mono- or divalent metal ions influence directly the catalytic process, if required as essential cofactors, or by displacing the intrinsic factors. Complexing agents, like diphosphate (even monophosphate has a weak complexing capacity) can sequester essential ions, e.g. from ATP-dependent reactions, which require Mg2+ as counterions. Since ATP and not Mg2+ is the reacting component, such effects can easily be overlooked. Components of the buffer may have stabilizing or destabilizing influences on the protein structure. Destabilizing effects are incidentally ascribed to the frequently used Tris buffer (tris(hydroxymethyl)aminomethane).