Effect of nitrogen supply on frost resistance, nitrogen metabolism and carbohydrate content in white clover (Trifolium repens)

Effects of mineral nitrogen (2, 4, 6 and 8 m M NH₄NO₃) and nodulation with Rhizobium on frost hardiness in seedlings of white clover ( Trifolium repens ) have been studied. Seedlings of a population from Bodø (67°N lat.) were grown in Leonard jars under controlled conditions in a phytotron. For induction of frost hardening, plants were first exposed to 12 h photoperiod conditions for 2 weeks at 18°C, then for 2 weeks at 6°C and finally for 2 weeks at 0.5°C. Frost hardiness after treatments at 6 and 0.5°C was significantly enhanced by increasing nitrogen supply and was positively correlated with total nitrogen content of the stolons. Frost hardiness of nodulated plants correlated to the tissue nitrogen concentration. Content of soluble proteins in stolons decreased during hardening at 6°C but did not change during treatment at 0.5°C. There were minor changes in total amount of free amino acids during hardening. Both absolute and relative amounts of proline and arginine increased, and those of asparagine decreased during hardening. Absolute amounts of all free amino acids increased with increasing nitrogen supply, but the changes during hardening were similar in all treatments. There was a significant increase in the content of soluble carbohydrates during hardening. However, this increase was inversely related to nitrogen supply.     

Selenoprotein P Status Correlates to Cancer-Specific Mortality in Renal Cancer Patients

Selenium (Se) is an essential trace element for selenoprotein biosynthesis. Selenoproteins have been implicated in cancer risk and tumor development. Selenoprotein P (SePP) serves as the major Se transport protein in blood and as reliable biomarker of Se status in marginally supplied individuals. Among the different malignancies, renal cancer is characterized by a high mortality rate. In this study, we aimed to analyze the Se status in renal cell cancer (RCC) patients and whether it correlates to cancer-specific mortality. To this end, serum samples of RCC patients (n = 41) and controls (n = 21) were retrospectively analyzed. Serum Se and SePP concentrations were measured by X-ray fluorescence and an immunoassay, respectively. Clinical and survival data were compared to serum Se and SePP concentrations as markers of Se status by receiver operating characteristic (ROC) curve and Kaplan-Meier and Cox regression analyses. In our patients, higher tumor grade and tumor stage at diagnosis correlated to lower SePP and Se concentrations. Kaplan-Meier analyses indicated that low Se status at diagnosis (SePP<2.4 mg/l, bottom tertile of patient group) was associated with a poor 5-year survival rate of 20% only. We conclude that SePP and Se concentrations are of prognostic value in RCC and may serve as additional diagnostic biomarkers identifying a Se deficit in kidney cancer patients potentially affecting therapy regimen. As poor Se status was indicative of high mortality odds, we speculate that an adjuvant Se supplementation of Se-deficient RCC patients might be beneficial in order to stabilize their selenoprotein expression hopefully prolonging their survival. However, this assumption needs to be rigorously tested in prospective clinical trials.     

Seroprevalence of <Emphasis Type="Italic">Borrelia burgdorferi</Emphasis> sensu lato and <Emphasis Type="Italic">Anaplasma phagocytophilum</Emphasis> in Danish horses

Background

Borrelia burgdorferi sensu lato and Anaplasma phagocytophilum are able to infect horses. However, the extend to which Danish horses are infected and seroconvert due to these two bacteria is unknown. The aim of the present study was to evaluate the seroprevalence of B. burgdorferi sensu lato and A. phagocytophilum in Danish horses.

Methods

A total of 390 blood samples collected from all major regions of Denmark and with a geographical distribution corresponding to the density of the Danish horse population were analyzed. All samples were examined for the presence of antibodies against B. burgdorferi sensu lato and A. phagocytophilum by the use of the SNAP^®4DX ^® ELISA test.

Results

Overall, 29.0% of the horses were seropositive for B. burgdorferi sensu lato whereas 22.3% were seropositive for A. phagocytophilum.

Conclusions

Antibodies against B burgdorferi sensu lato and A. phagocytophilum are commonly found among Danish horses thus showing that Danish horses are frequently infected by these organisms.

     

Control of respiration in proteoliposomes containing cytochrome aa3. I. Stimulation by valinomycin and uncoupler

1. Both valinomycin and p-trifluoromethoxy carbonyl cyanide phenylhydrazone (FCCP) are required for full release of respiration by cytochrome c oxidase-containing proteoliposomes (prepared by sonicating beef heart cytochrome aa₃ in salt solution with 4 parts phosphatidylcholine, 4 parts phosphatidylethanolamine and 2 parts cardiolipin) in the presence of external ascorbate and cytochrome c. In the absence of valinomycin the response to FCCP is rather sluggish, as reported by Wrigglesworth et al. (1976) (Abstracts, 10th Int. Congr. Biochem., No. 06-6-230).2. The K_m for cytochrome c in 67 mM, pH 7.4, phosphate buffer with ascorbate as substrate, was 9 μM in both absence and presence of valinomycin and FCCP. Energization thus acts non-competitively towards cytochrome c oxidation.3. The apparent K_m for oxygen is greater in the energized than in the deenergized state; double reciprocal plots of respiration rate versus oxygen concentration are concave downward in the absence of uncouplers, as found with intact mitochondria. Energization thus acts “competitively” towards oxygen.4. Despite the lack of a functional ATPase system, all the kinetic features of energization found in intact mitochondria can be mimicked in the reconstituted liposomes. This supports the chemiosmotic idea that electrical and perhaps H⁺ gradients modify the oxidase activity in reconstituted vesicles.     

Epstein-Barr virus-encoded BILF1 is a constitutively active G protein-coupled receptor

Both beta- and gammaherpesviruses encode G protein-coupled receptors (GPCRs) with unique pharmacological phenotypes and important biological functions. An example is ORF74, the gamma2-herpesvirus Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded GPCR, which is highly constitutively active and considered the key oncogene in Kaposi's sarcoma pathogenesis. In contrast, the current annotation of the Epstein-Barr virus (EBV) genome does not reveal any GPCR homolog encoded by this human oncogenic gamma1-herpesvirus. However, by employing bioinformatics, we recognized that the previously established EBV open reading frame BILF1 indeed encodes a GPCR. Additionally, BILF1 is a member of a new family of related GPCRs exclusively encoded by gamma1-herpesviruses. Expression of hemagglutinin-tagged BILF1 in the HEK293 epithelial cell line revealed that BILF1 is expressed as an approximately 50-kDa glycosylated protein. Immunocytochemistry and confocal microscopy revealed that BILF1 localizes predominantly to the plasma membrane, similar to the localization of KSHV ORF74. Using chimeric G proteins, we found that human and rhesus EBV-encoded BILF1 are highly potent constitutively active receptors, activating Galphai. Furthermore, BILF1 is able to inhibit forskolin-triggered CREB activation via stimulation of endogenous G proteins in a pertussis toxin-sensitive manner, verifying that BILF1 signals constitutively through Galphai. We suggest that EBV may use BILF1 to regulate Galphai-activated pathways during viral lytic replication, thereby affecting disease progression.     

What is the best reference RNA? And other questions regarding the design and analysis of two-color microarray experiments

The reference design is a practical and popular choice for microarray studies using two-color platforms. In the reference design, the reference RNA uses half of all array resources, leading investigators to ask: What is the best reference RNA? We propose a novel method for evaluating reference RNAs and present the results of an experiment that was specially designed to evaluate three common choices of reference RNA. We found no compelling evidence in favor of any particular reference. In particular, a commercial reference showed no advantage in our data. Our experimental design also enabled a new way to test the effectiveness of pre-processing methods for two-color arrays. Our results favor using intensity normalization and foregoing background subtraction. Finally, we evaluate the sensitivity and specificity of data quality filters, and we propose a new filter that can be applied to any experimental design and does not rely on replicate hybridizations.     

Metabolic regulation of oocyte cell death through the CaMKII-mediated phosphorylation of caspase-2

Vertebrate female reproduction is limited by the oocyte stockpiles acquired during embryonic development. These are gradually depleted over the organism's lifetime through the process of apoptosis. The timer that triggers this cell death is yet to be identified. We used the Xenopus egg/oocyte system to examine the hypothesis that nutrient stores can regulate oocyte viability. We show that pentose-phosphate-pathway generation of NADPH is critical for oocyte survival and that the target of this regulation is caspase-2, previously shown to be required for oocyte death in mice. Pentose-phosphate-pathway-mediated inhibition of cell death was due to the inhibitory phosphorylation of caspase-2 by calcium/calmodulin-dependent protein kinase II (CaMKII). These data suggest that exhaustion of oocyte nutrients, resulting in an inability to generate NADPH, may contribute to ooctye apoptosis. These data also provide unexpected links between oocyte metabolism, CaMKII, and caspase-2.     

Trends in Prevalence of Overweight and Obesity in Danish Infants,Children and Adolescents – Are We Still on a Plateau?

Background

After the worldwide steep increase in child and adolescent overweight and obesity during the last decades, there is now evidence of a levelling off in the prevalence in many countries in the Western world.

Aim

To examine whether there still is a plateau in the prevalence of overweight and obesity in Danish children and adolescents, or whether the prevalence is decreasing or rising again.

Methods

The trends in the prevalence rates were based on three data sets providing comparable repeated estimates: 1) the Danish Health Visitors Child Health Database (DHVCHD) with measurements on infant and childhood height and weight from 2002 to 2011 (n up to 39,984), 2) the Danish National Birth Cohort (DNBC) with maternal reports of measured infant and childhood height and weight from 1998 to 2010 (n up to 56,826) and 3) the Danish part of the Health Behaviour in School-aged Children survey (HBSC) with self-reported information on adolescent height and weight from the years 2002 to 2010 (n = 16,557). Overweight and obesity were categorized according to WHO growth standards. Trends were assessed by repeated point estimates and linear regression analyses providing regression coefficients for changes in per cent per year with 95% confidence intervals (CI).

Results

The prevalence rates of overweight and obesity for infants, children and adolescents showed a mixed pattern of decline, stability and increase (ranging from -1.10 through 0.29 per cent per year with CI’s from -3.10 through 2.37). Overall, there were no consistent statistically significant trends upwards or downwards, although some significant downward trends in childhood and adolescence were observed.

Conclusion

This study, based on data from 1998 through 2011, showed that the prevalence rates of overweight and obesity among Danish infants, children and adolescents were largely still on a plateau with tendencies for a decline among children and adolescents.     

Impairment of the organization of locomotor and exploratory behaviors in bile duct-ligated rats

Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to several problems, including motor impairment. Animal models of chronic liver disease have extensively investigated the mechanisms of this disease. Impairment of locomotor activity has been described in different rat models. However, these studies are controversial and the majority has primarily analyzed activity parameters. Therefore, the aim of the present study was to evaluate locomotor and exploratory behavior in bile duct-ligated (BDL) rats to explore the spatial and temporal structure of behavior. Adult female Wistar rats underwent common bile duct ligation (BDL rats) or the manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent open-field, plus-maze and foot-fault behavioral tasks. The BDL rats developed chronic liver failure and exhibited a decrease in total distance traveled, increased total immobility time, smaller number of rearings, longer periods in the home base area and decreased percentage of time in the center zone of the arena, when compared to the control rats. Moreover, the performance of the BDL rats was not different from the control rats for the elevated plus-maze and foot-fault tasks. Therefore, the BDL rats demonstrated disturbed spontaneous locomotor and exploratory activities as a consequence of altered spatio-temporal organization of behavior.