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.

     

Exendin-4, but not dipeptidyl peptidase IV inhibition, increases small intestinal mass in GK rats

Long-term treatment with dipeptidyl peptidase IV inhibitors (DPPIV-I) or glucagon-like peptide (GLP)-1 analogs may potentially affect intestinal growth by down- or upregulating the intestinotrophic hormone GLP-2. This study compared the intestinotrophic effects of 12-wk administration of vehicle, exendin-4 (Ex-4; 5 nmol/kg bid sc), or DPPIV-I (NN-7201, 10 mg/kg qd orally) in GK rats. Some animals were observed additionally for 9 wk after the end of treatment. Both treatments lowered glycated hemoglobin A1c at wk 12 vs. control (Ex-4, -0.8%; DPPIV-I, -0.4%). Body weight was reduced by Ex-4 compared with control (361 +/- 4 vs. 399 +/- 5 g; P < 0.001) because of reduced food intake, whereas neither parameter was affected by DPPIV-I. Linear bone growth was unaffected by either treatment. After treatment end, food intake in Ex-4 animals increased, and, by wk 21, body weight was identical in all groups. The small intestine of Ex-4-treated animals was larger at wk 12 compared with control (length, 135.6 +/- 1.6 vs. 124.5 +/- 2.3 cm, P < 0.001; absolute weight, 8.4 +/- 0.2 vs. 6.4 +/- 0.4 g, P < 0.001), being most pronounced proximally, where the absolute cross-sectional area related to body weight increased by 24% because of increased mucosal thickness. These effects were reversible, and 9 wk after the end of treatment, no differences between Ex-4 and control were apparent. Plasma GLP-2 concentrations were unaltered by either treatment, and Ex-4 had no agonistic or antagonistic effects on the transfected GLP-2 receptor. DPPIV-I had no intestinal effects. In conclusion, the continued presence of Ex-4 is necessary to maintain weight loss in GK rats. Effective antihyperglycemic treatment with Ex-4 increases intestinal mass reversibly, whereas DPPIV-I lacks intestinal effects.     

An aminoacyl-tRNA synthetase:elongation factor complex for substrate channeling in archaeal translation

Translation requires the specific attachment of amino acids to tRNAs by aminoacyl-tRNA synthetases (aaRSs) and the subsequent delivery of aminoacyl-tRNAs to the ribosome by elongation factor 1 alpha (EF-1α). Interactions between EF-1α and various aaRSs have been described in eukaryotes, but the role of these complexes remains unclear. To investigate possible interactions between EF-1α and other cellular components, a yeast two-hybrid screen was performed for the archaeon Methanothermobacter thermautotrophicus. EF-1α was found to form a stable complex with leucyl-tRNA synthetase (LeuRS; K_D = 0.7 μM). Complex formation had little effect on EF-1α activity, but increased the k_cat for Leu-tRNA^Leu synthesis ~8-fold. In addition, EF-1α co-purified with the archaeal multi-synthetase complex (MSC) comprised of LeuRS, LysRS and ProRS, suggesting the existence of a larger aaRS:EF-1α complex in archaea. These interactions between EF-1α and the archaeal MSC contribute to translational fidelity both by enhancing the aminoacylation efficiencies of the three aaRSs in the complex and by coupling two stages of translation: aminoacylation of cognate tRNAs and their subsequent channeling to the ribosome.     

Glucagon-like peptide 2 has limited efficacy to increase nutrient absorption in fetal and preterm pigs

Exogenous glucagon-like peptide 2 (GLP-2) prevents intestinal atrophy and increases nutrient absorption in term newborn pigs receiving total parenteral nutrition (TPN). We tested the hypothesis that the immature intestine of fetuses and preterm neonates has a diminished nutrient absorption response to exogenous GLP-2. This was accomplished using catheterized fetal pigs infused for 6 days (87-91% of gestation) with GLP-2 (25 nmol.kg(-1).day(-1) iv; n = 7) or saline (n = 7), and cesarean-delivered preterm pigs (92% of gestation) that received TPN with GLP-2 (25 nmol.kg(-1).day(-1) iv; n = 8) or saline (n = 7) for 6 days after birth. Responses to GLP-2 were assessed by measuring intestinal dimensions, absorption of nutrients (glucose, leucine, lysine, proline) by intact tissues and brush border membrane vesicles, and abundance of sodium-glucose cotransporter mRNA. Infusion of GLP-2 increased circulating GLP-2 levels in fetuses, but did not increase intestinal mass or absorption of nutrients by intact tissues and brush border membrane vesicles, except for lysine. Administration of exogenous GLP-2 to preterm TPN-fed pigs similarly did not increase rates of nutrient absorption, yet nutrient absorption capacities of the entire small intestine tended to increase (+10-20%, P < 0.10) compared with TPN alone due to increased intestinal mass (+30%, P < 0.05). GLP-2 infusion did not increase sodium-glucose cotransporter-1 mRNA abundance in fetuses or postnatal preterm pigs. Hence, the efficacy of exogenous GLP-2 to improve nutrient absorption by the intestine of fetal and preterm pigs is limited compared with term pigs and more mature animals and humans.     

Antagonistic interaction between oxygenation-linked lactate and CO2 binding to human hemoglobin

Oxygen binding to hemoglobin (Hb) depends on allosteric effectors (CO(2), lactate and protons) that may increase drastically in concentration during exercise. The effectors share common binding sites on the Hb molecules, predicting mutual interaction in their effects on Hb (de)oxygenation. We analysed the effects of lactate and CO(2), separately and in combination, on O(2) binding of purified human Hb at 37 degrees C and physiological pH and chloride values. We demonstrate pH-dependent, inhibitory interactions between lactate binding and CO(2) binding (carbamate formation); at pH 7.4, physiological CO(2) tension ( approximately 43 mm Hg) reduced lactate binding more markedly ( approximately 75%), than lactate (50 mM) inhibited carbamate formation ( approximately 25%). In contrast to previous studies on blood and Hb solutions, we moreover find that added lactate neither 'reverses' oxylabile carbamate formation (resulting in lower carbamate levels in deoxyHb than in oxyHb) nor exerts greater allosteric effects on Hb-O(2) affinity than equal increases in chloride ion concentrations.     

Characterization of bromadiolone resistance in a danish strain of Norway rats, Rattus norvegicus, by hepatic gene expression profiling of genes involved in vitamin K-dependent gamma-carboxylation

The present study characterizes the anticoagulant resistance mechanism in a Danish bromadiolone-resistant strain of Norway rats (Rattus norvegicus), with a Y139C VKORC1 mutation. We compared liver expression of the VKORC1 gene, which encodes a protein of the vitamin K 2,3-epoxide reductase complex, the NQO1 gene, which encodes a NAD(P)H quinone dehydrogenase and the Calumenin gene between bromadiolone-resistant and anticoagulant-susceptible rats upon saline and bromadiolone administration. Additionally, we established the effect of bromadiolone on the gene expression in the resistant and susceptible phenotype. Bromadiolone had no effect on VKORC1 and NQO1 expression in resistant rats, but induced significantly Calumenin expression in the susceptible rats. Calumenin expression was similar between the resistant and the susceptible rats upon saline administration but twofold lower in resistant rats after bromadiolone treatment. These results indicate that Danish bromadiolone resistance does not involve an overexpression of calumenin. Independent of the treatment, we observed a low VKORC1 expression in resistant rats, which in conjugation with the Y139C polymorphism most likely explains the low VKOR activity and the enhanced need for vitamin K observed in Danish resistant rats. Furthermore the bromadiolone resistance was found to be associated with a low expression of the NQO1 gene.     

The planarian <Emphasis Type="Italic">nanos</Emphasis>-like gene Smednos is expressed in germline and eye precursor cells during development and regeneration

Planarians are highly regenerative organisms with the ability to remake all their cell types, including the germ cells. The germ cells have been suggested to arise from totipotent neoblasts through epigenetic mechanisms. Nanos is a zinc-finger protein with a widely conserved role in the maintenance of germ cell identity. In this work, we describe the expression of a planarian nanos-like gene Smednos in two kinds of precursor cells namely, primordial germ cells and eye precursor cells, during both development and regeneration of the planarian Schmidtea mediterranea. In sexual planarians, Smednos is expressed in presumptive male primordial germ cells of embryos from stage 8 of embryogenesis and throughout development of the male gonads and in the female primordial germ cells of the ovary. Thus, upon hatching, juvenile planarians do possess primordial germ cells. In the asexual strain, Smednos is expressed in presumptive male and female primordial germ cells. During regeneration, Smednos expression is maintained in the primordial germ cells, and new clusters of Smednos-positive cells appear in the regenerated tissue. Remarkably, during the final stages of development (stage 8 of embryogenesis) and during regeneration of the planarian eye, Smednos is expressed in cells surrounding the differentiating eye cells, possibly corresponding to eye precursor cells. Our results suggest that similar genetic mechanisms might be used to control the differentiation of precursor cells during development and regeneration in planarians. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.