Digestive enzyme activities in larvae of sharpsnout seabream (Diplodus puntazzo)

The ontogenesis and specific activities of pancreatic and intestinal enzymes were investigated in sharpsnout sea bream, Diplodus puntazzo, during larval development until the end of weaning on day 50. The green-water technique was carried out for larval rearing in triplicate. Trypsin was first detected as early as hatching and sharply increased related to age and exogenous feeding until day 25, but a sharp decrease was observed towards the end of the experiment. Amylase was determined 2 days after hatching (DAH) and sharply increased to 10 DAH. Afterwards, slight decreases were found between 10 and 20 DAH and then slow alterations were continued until end of the experiment. Lipase was measured for the first time on day 4, and then slight increase was found to 25 DAH. After this date, slow variations were maintained until end of the experiment. Pepsin was firstly assayed 32 DAH related with stomach formation and sharply increased to 40 DAH. Then it was fluctuated until end of the experiment. Enzymes of brush border membranes, alkaline phosphatase and aminopeptidase N, showed similar pattern on specific activities during the first 10 days. Thereafter, while specific activity of alkaline phosphatase slightly decreased to 15 DAH and fluctuated until 20 DAH, aminopeptidase N activity slowly declined to 20 DAH. Afterwards, activity of alkaline phosphatase and aminopeptidase N were sharply increased to 30 DAH, showing maturation of the intestinal digestive process and also these activities continued to slight increase until end of the experiment. The specific activity of cytosolic peptidase, leucine-alanine peptidase sharply increased to on day 8, then suddenly declined to 12 DAH and further decreased until 20 DAH. After this date, in contrast to enzymes of brush border membranes, it sharply decreased to 25 DAH and continued to gradually decline until the end of the experiment. These converse expressions were indicative of a maturation of enterocytes and the transition to an adult mode of digestion.     

Blink test results in patients with central sleep apnea syndrome

Sleep and Biological Rhythms - The aim of the study was to evaluate whether there was a problem in the interneuronal junctions of patients with central sleep apnea using the blink reflex test....     

Convergence in plant traits between species within grassland communities simplifies their monitoring

Plant trait measurement is a very powerful and promising method for assessing the effects of land use change on ecosystem behavior in grasslands, but it is very time-consuming. Hence we pose the following questions for simplifying diagnosis and monitoring: (i) are plant traits (PTs) similar between plant life forms (PLF: grasses, rosettes, upright forbs, legumes) within a plant community? (ii) is it possible to define the main plant community characteristics by measuring traits on one PLF or a limited number of dominant species?Six PTs known for their ability to characterize the capacity of species to exploit resource-rich or -poor environments and for their competitive dominance in response to disturbance (specific leaf area (SLA), leaf dry matter content (LDMC), plant height (H), C and N contents, flowering time) were measured on the species of 18 plant communities located in Central Pyrenees. The experiment combined 2 fertility levels and 3 defoliation regimes (cutting, grazing). Comparisons were made between the weighted values at community, PLF and two dominant species levels. Regression analysis shows that there were significant correlations between grasses and rosettes for 4 PTs. For H, N and C:N ratio, data for both grass and rosette PLFs were close to the bisecting line. The largest difference in the intercept was observed for LDMC. On the basis of plant traits weighted for all the species, plant communities were ranked in similar ways for SLA and H (Spearman r > 0.93; p < 0.001) and to a lesser extent for LDMC (r = 0.72; p < 0.001). Convergence in weighted plant traits for different PLFs within a plant community mean that in the studied grasslands, defoliation regime and nutrient availability act as strong filters that impose, at least at PLF level, very similar PFTs. This determines a specific local community structure and composition. An application of this result in managed grasslands is the possibility of focusing on one PLF or a limited number of species for vegetation diagnosis and monitoring.     

Beta1-Adrenoceptor Polymorphism Predicts Flecainide Action in Patients with Atrial Fibrillation

Background

Antiarrhythmic action of flecainide is based on sodium channel blockade. Beta₁-adrenoceptor (β₁AR) activation induces sodium channel inhibition, too. The aim of the present study was to evaluate the impact of different β₁AR genotypes on antiarrhythmic action of flecainide in patients with structural heart disease and atrial fibrillation.

Methodology/Principal Findings

In 145 subjects, 87 with atrial fibrillation, genotyping was performed to identify the individual β₁AR Arg389Gly and Ser49Gly polymorphism. Resting heart rate during atrial fibrillation and success of flecainide-induced cardioversion were correlated with β₁AR genotype. The overall cardioversion rate with flecainide was 39%. The Arg389Arg genotype was associated with the highest cardioversion rate (55.5%; OR 3.30; 95% CI; 1.34–8.13; p = 0.003) compared to patients with Arg389Gly (29.5%; OR 0.44; 95% CI; 0.18–1.06; p = 0.066) and Gly389Gly (14%; OR 0.24; 95% CI 0.03–2.07; p = 0.17) variants. The single Ser49Gly polymorphism did not influence the conversion rate. In combination, patients with Arg389Gly-Ser49Gly genotype displayed the lowest conversion rate with 20.8% (OR 0.31; 95% CI; 0.10–0.93; p = 0.03). In patients with Arg389Arg variants the heart rate during atrial fibrillation was significantly higher (110±2.7 bpm; p = 0.03 vs. other variants) compared to Arg389Gly (104.8±2.4 bpm) and Gly389Gly (96.9±5.8 bpm) carriers. The Arg389Gly-Ser49Gly genotype was more common in patients with atrial fibrillation compared to patients without atrial fibrillation (27.6% vs. 5.2%; HR 6.98; 95% CI; 1.99–24.46; p<0.001).

Conclusions

The β₁AR Arg389Arg genotype is associated with increased flecainide potency and higher heart rate during atrial fibrillation. The Arg389Gly-Ser49Gly genotype might be of predictive value for atrial fibrillation.     

Effects of red blood cell aggregation on myocardial hematocrit gradient using two approaches to increase aggregation

The normal transmyocardial tissue hematocrit distribution (i.e., subepicardial greater than subendocardial) is known to be affected by red blood cell (RBC) aggregation. Prior studies employing the use of infused large macromolecules to increase erythrocyte aggregation are complicated by both increased plasma viscosity and dilution of plasma. Using a new technique to specifically alter the aggregation behavior by covalent attachment of Pluronic F-98 to the surface of the RBC, we have determined the effects of only enhanced aggregation (i.e., Pluronic F-98-coated RBCs) versus enhanced aggregation with increased plasma viscosity (i.e., an addition of 500 kDa dextran) on myocardial tissue hematocrit in rapidly frozen guinea pig hearts. Although both approaches equally increased aggregation, tissue hematocrit profiles differed markedly: 1) when Pluronic F-98-coated cells were used, the normal transmyocardial gradient was abolished, and 2) when dextran was added, the hematocrit remained at subepicardial levels for about one-half the thickness of the myocardium and then rapidly decreased to the control level in the subendocardial layer. Our results indicate that myocardial hematocrit profiles are sensitive to both RBC aggregation and to changes of plasma viscosity associated with increased RBC aggregation. Furthermore, they suggest the need for additional studies to explore the mechanisms affecting RBC distribution in three-dimensional vascular beds.     

Human cytomegalovirus protein US2 interferes with the expression of human HFE, a nonclassical class I major histocompatibility complex molecule that regulates iron homeostasis

HFE is a nonclassical class I major histocompatibility complex (MHC) molecule that is mutated in the autosomal recessive iron overload disease hereditary hemochromatosis. There is evidence linking HFE with reduced iron uptake by the transferrin receptor (TfR). Using a panel of HFE and TfR monoclonal antibodies to examine human HFE (hHFE)-expressing cell lines, we demonstrate the expression of stable and fully glycosylated TfR-free and TfR-associated hHFE/beta2m complexes. We show that both the stability and assembly of hHFE complexes can be modified by the human cytomegalovirus (HCMV) viral protein US2, known to interfere with the expression of classical class I MHC molecules. HCMV US2, but not US11, targets HFE molecules for degradation by the proteasome. Whether this interference with the regulation of iron metabolism by a viral protein is a means of potentiating viral replication remains to be determined. The reduced expression of classical class I MHC and HFE complexes provides the virus with an efficient tool for altering cellular metabolism and escaping certain immune responses.     

The role of endoplasmic reticulum-associated aminopeptidase 1 in immunity to infection and in cross-presentation

Endoplasmic reticulum-associated aminopeptidase 1 (ERAP1) is involved in the final processing of endogenous peptides presented by MHC class I molecules to CTLs. We generated ERAP1-deficient mice and analyzed cytotoxic responses upon infection with three viruses, including lymphocytic choriomeningitis virus, which causes vigorous T cell activation and is controlled by CTLs. Despite pronounced effects on the presentation of selected epitopes, the in vivo cytotoxic response was altered for only one of several epitopes tested. Moreover, control of lymphocytic choriomeningitis virus was not impaired in the knockout mice. Thus, we conclude that lack of ERAP1 has little influence on antiviral immunohierarchies and antiviral immunity in the infections studied. We also focused on the role of ERAP1 in cross-presentation. We demonstrate that ERAP1 is required for efficient cross-presentation of cell-associated Ag and of OVA/anti-OVA immunocomplexes. Surprisingly, however, ERAP1 deficiency has no effect on cross-presentation of soluble OVA, suggesting that for soluble exogenous proteins, final processing may not take place in an environment containing active ERAP1.     

Dynamics of Ku and bacterial non-homologous end-joining characterized using single DNA molecule analysis

We use single-molecule techniques to characterize the dynamics of prokaryotic DNA repair by non-homologous end-joining (NHEJ), a system comprised only of the dimeric Ku and Ligase D (LigD). The Ku homodimer alone forms a ∼2 s synapsis between blunt DNA ends that is increased to ∼18 s upon addition of LigD, in a manner dependent on the C-terminal arms of Ku. The synapsis lifetime increases drastically for 4 nt complementary DNA overhangs, independently of the C-terminal arms of Ku. These observations are in contrast to human Ku, which is unable to bridge either of the two DNA substrates. We also demonstrate that bacterial Ku binds the DNA ends in a cooperative manner for synapsis initiation and remains stably bound at DNA junctions for several hours after ligation is completed, indicating that a system for removal of the proteins is active in vivo. Together these experiments shed light on the dynamics of bacterial NHEJ in DNA end recognition and processing. We speculate on the evolutionary similarities between bacterial and eukaryotic NHEJ and discuss how an increased understanding of bacterial NHEJ can open the door for future antibiotic therapies targeting this mechanism.