Detection of nodavirus in seawater from rearing facilities for Atlantic halibut Hippoglossus hippoglossus larvae

We used (1) ultracentrifugation followed by RT-PCR and (2) real-time RT-PCR to detect and quantify nodaviruses in seawater in which Atlantic halibut Hippoglossus hippoglossus larvae/fry had been held at rearing facilities. Evaluated against in vitro propagated viruses, the viral concentration corresponded to 1.6 x 10(4) TCID50 (50% tissue culture infectious dose) ml(-1). Evaluated against in vitro transcribed RNA, the concentration was estimated at 2 x 10(7) virus particles ml(-1) seawater.     

Annexin A1 and A2: roles in retrograde trafficking of Shiga toxin

Annexins constitute a family of calcium and membrane binding proteins. As annexin A1 and A2 have previously been linked to various membrane trafficking events, we initiated this study to investigate the role of these annexins in the uptake and intracellular transport of the bacterial Shiga toxin (Stx) and the plant toxin ricin. Once endocytosed, both toxins are retrogradely transported from endosomes to the Golgi apparatus and the endoplasmic reticulum before being targeted to the cytosol where they inhibit protein synthesis. This study was performed to obtain new information both about toxin transport and the function of annexin A1 and annexin A2. Our data show that depletion of annexin A1 or A2 alters the retrograde transport of Stx but not ricin, without affecting toxin binding or internalization. Knockdown of annexin A1 increases Golgi transport of Stx, whereas knockdown of annexin A2 slightly decreases the same transport step. Interestingly, annexin A1 was found in proximity to cytoplasmic phospholipase A2 (cPLA(2)), and the basal as well as the increased Golgi transport of Stx upon annexin A1 knockdown is dependent on cPLA(2) activity. In conclusion, annexin A1 and A2 have different roles in Stx transport to the trans-Golgi network. The most prominent role is played by annexin A1 which normally works as a negative regulator of retrograde transport from the endosomes to the Golgi network, most likely by complex formation and inhibition of cPLA(2).     

A Complex Interaction between Rickettsia conorii and Dickkopf-1 – Potential Role in Immune Evasion Mechanisms in Endothelial Cells

The pathophysiological hallmark of spotted fever group rickettsioses comprises vascular inflammation. Based on the emerging importance of the wingless (Wnt) pathways in inflammation and vascular biology, we hypothesized that Dickkopf-1 (DKK-1), as a major modulator of Wnt signaling, could be involved in the pathogenesis in rickettsial infections. Our major findings were: (i) While baseline concentration of DKK-1 in patients with R. conorii infection (n = 32) were not different from levels in controls (n = 24), DKK-1 rose significantly from presentation to first follow-up sample (median 7 days after baseline). (ii) In vitro experiments in human umbilical vein endothelial cells (HUVECs) showed that while heat-inactivated R. conorii enhanced the release of interleukin-6 (IL-6) and IL-8, it down-regulated the release of endothelial-derived DKK-1 in a time- and dose-dependent manner. (iii) Silencing of DKK-1 attenuated the release of IL-6, IL-8 and growth-related oncogene (GRO)α in R. conorii-exposed HUVECs, suggesting inflammatory effects of DKK-1. (iv) Silencing of DKK-1 attenuated the expression of tissue factor and enhanced the expression of thrombomodulin in R. conorii-exposed HUVECs suggesting pro-thrombotic effects of DKK-1. The capacity of R. conorii to down-regulate endothelial-derived DKK-1 and the ability of silencing DKK-1 to attenuate R. conorii-induced inflammation in endothelial cells could potentially reflect a novel mechanism by which R. conorii escapes the immune response at the site of infection.     

A major imprinted gene involved in hydatidiform mole is not located in 2q31.2-qter or 5q34-qter

Introduction

Hydatidiform mole is an abnormal human pregnancy, characterised by absent or abnormal embryonic differentiation, vesicular chorionic villi and trophoblastic hyperplasia. Although the mole phenotype has hereto not been correlated to mutations in the molar genome, the aetiology for hydatidiform moles clearly is genetic: Most molar genomes analysed either have had a relative excess of paternal genome sets relative to maternal genome sets, or a global error in maternally imprinted genes, giving them a “paternal pattern”. However it remains yet to be specified which gene(s) in the molar genome actually causes the molar phenotype when present in a state of “paternal excess” or “maternal deficiency”.

Material and methods

A molar pregnancy in a woman with a balanced translocation (t(2;5) was subjected to histopathological evaluation and genetic analyses of ploidy and parental origin of the genome.

Results

Morphology: Partial hydatidiform mole. Karyotyping of metaphase chromosomes: 69,XXY,der(5)t(2;5)(q23;q33)mat. SNP array analysis mapped the breakpoints to 2q31.2 (genome position 179 Mb) and 5q34 (genome position 165 Mb). DNA microsatellite marker analysis showed that for the regions not involved in the translocation, the conceptus had two paternal and one maternal allele(s). Telomeric to the breakpoint on chromosome 2, the mole had two paternal and two maternal alleles and telomeric to the breakpoint on chromosome 5 the mole had paternal alleles, exclusively.

Conclusions

If the molar phenotype is caused by paternal excess of one gene, only, it is unlikely that this gene is located telomeric to genome position 179 Mb on chromosome 2. And similarly, if the phenotype complete mole is caused by the presence of exclusively paternally imprinted alleles of one gene, this gene is not located telomeric to genome position 165 Mb on chromosome 5.     

Discovery and biological evaluation of benzo[a]carbazole-based small molecule agonists of the thrombopoietin (Tpo) receptor

A novel series of benzo[a]carbazole-based small molecule agonists of the thrombopoietin (Tpo) receptor is reported. Starting from a 3.4 microM high throughput screen hit, members of this series have been identified which are full agonists with functional potency <50 nM and oral bioavailability in mice.     

Gene expression signatures and small-molecule compounds link a protein kinase to Plasmodium falciparum motility

Calcium-dependent protein kinases play a crucial role in intracellular calcium signaling in plants, some algae and protozoa. In Plasmodium falciparum, calcium-dependent protein kinase 1 (PfCDPK1) is expressed during schizogony in the erythrocytic stage as well as in the sporozoite stage. It is coexpressed with genes that encode the parasite motor complex, a cellular component required for parasite invasion of host cells, parasite motility and potentially cytokinesis. A targeted gene-disruption approach demonstrated that pfcdpk1 seems to be essential for parasite viability. An in vitro biochemical screen using recombinant PfCDPK1 against a library of 20,000 compounds resulted in the identification of a series of structurally related 2,6,9-trisubstituted purines. Compound treatment caused sudden developmental arrest at the late schizont stage in P. falciparum and a large reduction in intracellular parasites in Toxoplasma gondii, which suggests a possible role for PfCDPK1 in regulation of parasite motility during egress and invasion.     

Adaptive radiation of island plants: evidence from Aeonium (Crassulaceae) of the Canary Islands

The presence of diverse and species-rich plant lineages on oceanic islands is most often associated with adaptive radiation. Here we discuss the possible adaptive significance of some of the most prominent traits in island plants, including woodiness, monocarpy and sexual dimorphisms. Indirect evidence that such traits have been acquired through convergent evolution on islands comes from molecular phylogenies; however, direct evidence of their selective value rarely is obtained. The importance of hybridization in the evolution of island plants is also considered as part of a more general discussion of the mechanisms governing radiations on islands. Most examples are from the Hawaiian and Canarian floras, and in particular from studies on the morphological, ecological and molecular diversification of the genus Aeonium, the largest plant radiation of the Canarian Islands.     

Parasites of <Emphasis Type="Italic">Harmonia axyridis</Emphasis>: current research and perspectives

Harmonia axyridis (Coleoptera: Coccinellidae) has been introduced widely for biological control of agricultural pests. Harmonia axyridis has established in four continents outside of its native range in Asia and it is considered an invasive alien species (IAS). Despite a large body of work on invasion ecology, establishment mechanisms of IAS and their interactions with natural enemies remain open questions. Parasites, defined as multicellular organisms that do not directly kill the host, could potentially play an important role in regulating host populations. This study presents a review of the parasites of H. axyridis, discussing their distributions and effects on host populations across the host’s native and invasive range. These parasites are: Hesperomyces virescens Thaxt. fungi, Coccipolipus hippodamiae (McDaniel and Morrill) mites, and Parasitylenchus bifurcatus Poinar and Steenberg nematodes.     

The effects of exogenous histamine in isolated rat hearts

The role of histamine in cardiac physiology and pathophysiology is not clarified, but is dependent on species. The effects of exogenous histamine in Langendorff-perfused rat hearts were investigated. 1 mM, 100, 10, 1 and 0.1 M of histamine (n=7 each) as 15 min infusions were employed in a dose-response study, and compared to control perfused hearts (n=7). In another experimental series, 100 M histamine (n=15) was added during reperfusion after 25 min global ischemia, and compared to control ischemia-reperfusion (n=15). The maximal response to histamine in the dose-response study (100 M) was an increase of left ventricular developed pressure to 126±8% of initial value (mean±SEM, p<0.04), and increase of coronary flow to 152+6% (p<0.02) after 5 min infusion. 100 M histamine did not significantly influence heart rate or rhythm. The lowest concentration (0.1 M) did not have effects cardiac performance. Reperfusion with histamine for 2 min after ischemia reduced left ventricular developed pressure to 68±10% of initial value versus 116+17% in ischemic controls (p<0.05), and increased left ventricular end-diastolic pressure to 24±8 mmHg compared to 6±2 mmHg in controls (p<0.04). Left ventricular pressures were similar in hearts reperfused with histamine and in ischemic controls for the rest of the observation. Coronary flow increased during reperfusion in hearts given histamine. Histamine had a dose-dependent positive inotropic and vasodilatory effect in isolated rat hearts. Exogenous histamine had only minor effects on post-ischemic cardiac function.