Characterization of membrane-bound prolyl endopeptidase from brain

Prolyl oligopeptidase (POP) is a serine protease that cleaves small peptides at the carboxyl side of an internal proline residue. Substance P, arginine-vasopressin, thyroliberin and gonadoliberin are proposed physiological substrates of this protease. POP has been implicated in a variety of brain processes, including learning, memory, and mood regulation, as well as in pathologies such as neurodegeneration, hypertension, and psychiatric disorders. Although POP has been considered to be a soluble cytoplasmic peptidase, significant levels of activity have been detected in membranes and in extracellular fluids such as serum, cerebrospinal fluid, seminal fluid, and urine, suggesting the existence of noncytoplasmic forms. Furthermore, a closely associated membrane prolyl endopeptidase (PE) activity has been previously detected in synaptosomes and shown to be different from the cytoplasmic POP activity. Here we isolated, purified and characterized this membrane-bound PE, herein referred to as mPOP. Although, when attached to membranes, mPOP presents certain features that distinguish it from the classical POP, our results indicate that this protein has the same amino acid sequence as POP except for the possible addition of a hydrophobic membrane anchor. The kinetic properties of detergent-soluble mPOP are fully comparable to those of POP; however, when attached to the membranes in its natural conformation, mPOP is significantly less active and, moreover, it migrates anomalously in SDS/PAGE. Our results are the first to show that membrane-bound and cytoplasmic POP are encoded by variants of the same gene.     

How to derive biological information from the value of the normalization constant in allometric equations

Allometric equations are widely used in many branches of biological science. The potential information content of the normalization constant b in allometric equations of the form Y = bX(a) has, however, remained largely neglected. To demonstrate the potential for utilizing this information, I generated a large number of artificial datasets that resembled those that are frequently encountered in biological studies, i.e., relatively small samples including measurement error or uncontrolled variation. The value of X was allowed to vary randomly within the limits describing different data ranges, and a was set to a fixed theoretical value. The constant b was set to a range of values describing the effect of a continuous environmental variable. In addition, a normally distributed random error was added to the values of both X and Y. Two different approaches were then used to model the data. The traditional approach estimated both a and b using a regression model, whereas an alternative approach set the exponent a at its theoretical value and only estimated the value of b. Both approaches produced virtually the same model fit with less than 0.3% difference in the coefficient of determination. Only the alternative approach was able to precisely reproduce the effect of the environmental variable, which was largely lost among noise variation when using the traditional approach. The results show how the value of b can be used as a source of valuable biological information if an appropriate regression model is selected.     

Modelling the hydro-geochemistry of acid-sensitive catchments in Finland under atmospheric deposition and biomass harvesting scenarios

The dynamic hydro-geochemical Model of Acidification of Groundwater in Catchments (MAGIC) was used to predict the response of 163 Finnish lake catchments to historic and future atmospheric deposition (1880–2100) and future tree harvesting practices. Deposition was assumed to follow current legislated European emission reduction policies (CLe) and a scenario based on maximum (technically) feasible reductions (MFR). Future harvesting was assumed to shift from stem-only harvesting (SOH) to whole-tree harvesting (WTH) owing to the potential increased utilisation of biofuels. Despite the modest changes in atmospheric deposition under CLe (compared to current day), these reductions are predicted to halt the decline in soil base saturation; however, further reductions are required to improve soil and lake water chemistry. The MFR scenario predicted a significant long-term improvement in soil base saturation leading to continued long-term recovery in surface waters (all lakes with ANC > 0 by 2100). However under the WTH scenario, significant long-term impacts (re-acidification) were predicted for soil and surface water chemistry (14 lakes with ANC < 0 by 2100). To some extent the long-term negative impacts were reduced under MFR, indicating that increased utilisation of biofuels will necessitate ‘trading emissions for timber’, or soil amendment, to maintain ecosystem quality and sustainable forest growth. The current practice of SOH is close to the sustainable maximum harvesting under current (legislated) atmospheric deposition in Finland.     

Effect of elevated [CO2] on stem wood properties of mature Norway spruce grown at different soil nutrient availability

The objective of the present study was to investigate the interactive effects of elevated [CO₂] and soil nutrient availability on secondary xylem structure and chemical composition of 41‐year‐old Norway spruce (Picea abies (L.) Karst.) trees. The nonfertilized and irrigated‐fertilized trees were, for 3 years, continuously exposed to elevated [CO₂] in whole‐tree chambers. Elevated [CO₂] decreased concentrations of soluble sugars, acid‐soluble lignin and nitrogen in stem wood, but the effects were not consistent between sampling height and/or fertilization. The effect of 2*ambient [CO₂] on wood structure depended on the exposure year and/or fertilization. Radial lumen diameter decreased and annual ring width increased in the second year of exposure (1999) in elevated [CO₂]. In the latter, the CO₂ effect was significant only in the nonfertilized trees. Stem wood chemistry and structure were significantly affected by fertilization. Fertilization increased the concentrations of nitrogen and gravimetric lignin, annual ring width, and radial lumen diameter. Fertilization decreased C/N ratio, mean ring density, earlywood density, latewood density, cell wall thickness, cell wall index, and latewood percentage. We conclude that elevated [CO₂] had only minor effects on wood properties while fertilization had more marked effects and thus may affect ecosystem processes and suitability of wood for different end‐use purposes.     

Discarding multidrug resistance inducers, the possible role of a biosensing reporter in antimicrobial discovery.

The aim of the present work was to determine whether the luminescence-based reporter plasmid pQacLux could be applied to drug discovery in order to discard compounds with defined properties. Non-pathogenic Staphylococcus aureus RN4220 cells bearing pQacLux were incubated with different concentrations of a disinfectant of common use in hospitals. The in vivo light emission response of the plasmid to the given stimuli was then quantified and compared to a negative control for the construction of dose-response curves. The selected disinfectant provided a convenient model for the activity of quaternary ammonium compounds. In spite of the use of a raw model solution, the system revealed high levels of sensitivity. According to the results obtained, pQacLux could be conveniently used in the first steps of drug development in order to discard all possible multidrug resistance inducers.     

Organisational downsizing,sickness absence,and mortality: 10-town prospective cohort study

Objective To examine whether downsizing, the reduction of personnel in organisations, is a predictor of increased sickness absence and mortality among employees.Design Prospective cohort study over 7.5 years of employees grouped into categories on the basis of reductions of personnel in their occupation and workplace: no downsizing (< 8% reduction), minor downsizing (8-18%), and major downsizing (> 18%).Setting Four towns in Finland.Participants 5909 male and 16 521 female municipal employees, aged 19-62 years, who kept their jobs.Main outcome measures Annual sickness absence rate based on employers'' records before and after downsizing by employment contract; all cause and cause specific mortality obtained from the national mortality register.Results Major downsizing was associated with an increase in sickness absence (P for trend < 0.001) in permanent employees but not in temporary employees. The extent of downsizing was also associated with cardiovascular deaths (P for trend < 0.01) but not with deaths from other causes. Cardiovascular mortality was 2.0 (95% confidence interval 1.0 to 3.9) times higher after major downsizing than after no downsizing. Splitting the follow up period into two halves showed a 5.1 (1.4 to 19.3) times increase in cardiovascular mortality for major downsizing during the first four years after downsizing. The corresponding hazard ratio was 1.4 (0.6 to 3.1) during the second half of follow up.Conclusion Organisational downsizing may increase sickness absence and the risk of death from cardiovascular disease in employees who keep their jobs.     

Functional interaction of caveolin-1 with Bruton's tyrosine kinase and Bmx.

Bruton's tyrosine kinase (Btk), a member of the Tec family of protein-tyrosine kinases, has been shown to be crucial for B cell development, differentiation, and signaling. Mutations in the Btk gene lead to X-linked agammaglobulinemia in humans and X-linked immunodeficiency in mice. Using a co-transfection approach, we present evidence here that Btk interacts physically with caveolin-1, a 22-kDa integral membrane protein, which is the principal structural and regulatory component of caveolae membranes. In addition, we found that native Bmx, another member of the Tec family kinases, is associated with endogenous caveolin-1 in primary human umbilical vein endothelial cells. Second, in transient transfection assays, expression of caveolin-1 leads to a substantial reduction in the in vivo tyrosine phosphorylation of both Btk and its constitutively active form, E41K. Furthermore, a caveolin-1 scaffolding peptide (amino acids 82--101) functionally suppressed the autokinase activity of purified recombinant Btk protein. Third, we demonstrate that mouse splenic B-lymphocytes express substantial amounts of caveolin-1. Interestingly, caveolin-1 was found to be constitutively phosphorylated on tyrosine 14 in these cells. The expression of caveolin-1 in B-lymphocytes and its interaction with Btk may have implications not only for B cell activation and signaling, but also for antigen presentation.     

Polymorphic microsatellite DNA markers in the ant Formica exsecta

Highly polymorphic genetic markers provide a useful tool for estimating important genetic parameters in studies of the evolution of sociality in insects. Here we report 14 polymorphic microsatellite markers developed in the ant Formica exsecta. The number of alleles found ranged between 3 and 18 per locus. These markers were developed for studying genetic population structure and mating structure in F. exsecta populations with varying social organizations (monogyne and polygyne types of societies). Cross‐species amplification indicated that some of the markers might be usable even in species belonging to different subfamilies.     

Reduced natriuretic response to acute sodium loading in COMT Gene deleted mice

Background  

The intrarenal natriuretic hormone dopamine (DA) is metabolised by catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO). Inhibition of COMT, as opposed to MAO, results in a potent natriuretic response in the rat. The present study in anaesthetized homozygous and heterozygous COMT gene deleted mice attempted to further elucidate the importance of COMT in renal DA and sodium handling. After acute intravenous isotonic sodium loading, renal function was followed.     

Effects of growth differences due to geographic location and N-fertilisation on wood chemistry of Norway spruce

We studied the effect of long-term nitrogen fertilisation on wood chemistry at two boreal sites in Finland: the northern site (Kemijärvi) and the southern site (Heinola). N-fertilisation was repeated in five-year intervals from the 1960s. Norway spruce (Picea abies L. Karst.) trees that had been planted in 1938 and 1954, in the northern and the southern site, respectively, were harvested in October 2002. Altogether 20 trees, in five different size classes, either unfertilised or fertilised, were felled. Wood sections at breast height, consisting of five consecutive annual rings, from six (Kemijärvi) or five (Heinola) points with different distances from the pith were examined. Differences in growth between the northern and southern sites were marked in favour of the southern site. In the northern site fertilisation had clearly increased the diameter growth, while in the southern site fertilisation had no effect. Nitrogen fertilisation resulted in slight changes in wood chemistry that included increased nitrogen concentrations in the northern site and extractives in the southern site. Stem wood had higher concentrations of extractives, starch, and uronic acids, and lower concentration of cellulose, in the northern than in the southern site. Changes in the stem wood chemistry along radial axis were marked. The changes in wood chemistry are discussed in relation to the physiological function and also how the changes can influence the suitability of wood for different end-use purposes.