Prevalence and seasonal variations of six bee viruses in Apis mellifera L. and Varroa destructor mite populations in France

A survey of six bee viruses on a large geographic scale was undertaken by using seemingly healthy bee colonies and the PCR technique. Samples of adult bees and pupae were collected from 36 apiaries in the spring, summer, and autumn during 2002. Varroa destructor samples were collected at the end of summer following acaricide treatment. In adult bees, during the year deformed wing virus (DWV) was found at least once in 97% of the apiaries, sacbrood virus (SBV) was found in 86% of the apiaries, chronic bee paralysis virus (CBPV) was found in 28% of the apiaries, acute bee paralysis virus (ABPV) was found in 58% of the apiaries, black queen cell virus (BQCV) was found in 86% of the apiaries, and Kashmir bee virus (KBV) was found in 17% of the apiaries. For pupae, the following frequencies were obtained: DWV, 94% of the apiaries; SBV, 80% of the apiaries; CBPV, none of the apiaries; ABPV, 23% of the apiaries; BQCV, 23% of the apiaries; and KBV, 6% of the apiaries. In Varroa samples, the following four viruses were identified: DWV (100% of the apiaries), SBV (45% of the apiaries), ABPV (36% of the apiaries), and KBV (5% of the apiaries). The latter findings support the putative role of mites in transmitting these viruses. Taken together, these data indicate that bee virus infections occur persistently in bee populations despite the lack of clinical signs, suggesting that colony disease outbreaks might result from environmental factors that lead to activation of viral replication in bees.     

Phagocytic and macropinocytic activity in MARCKS-deficient macrophages and fibroblasts

Macrophages express high levels of the myristoylated,alanine-rich, C kinase substrate (MARCKS), an actin cross-linkingprotein. To investigate a possible role of MARCKS in macrophagefunction, fetal liver-derived macrophages were generated from wild-type and MARCKS knockout mouse embryos. No differences between the wild-typeand MARCKS-deficient macrophages with respect to morphology (Wright'sstain) or actin distribution (staining with rhodamine-phalloidin, underbasal conditions or after treatment with phorbol esters, lipopolysaccharide, or both) were observed. We then evaluated phagocytosis mediated by different receptors: Fc receptors tested withIgG-coated sheep red blood cells, complement C3b receptors tested withC3b-coated yeast, mannose receptors tested with unopsonized zymosan,and nonspecific phagocytosis tested with latex beads. We also studiedfluid phase endocytosis in macrophages and mouse embryo fibroblasts byusing FITC-dextran to quantitate this process. In most cases, therewere no differences between the cells derived from wild-type andMARCKS-deficient mice. However, a minor but significant andreproducible difference in rates of zymosan phagocytosis at 45-60min was observed, with lower rates of phagocytosis in theMARCKS-deficient cells. Our data indicate that MARCKS deficiency maylead to slightly decreased rates of zymosan phagocytosis.

     

Lack of alterations on meiotic chromosomes and morphological characteristics of male germ cells in mice exposed to a 60 Hz and 2.0 mT magnetic field

The effect of in vivo exposure of mice to a 60 Hz sinusoidal magnetic field (MF) at 2.0 mT on male germ cells was studied. The cytological endpoints measured included meiotic chromosome aberrations in spermatocytes and sperm morphology. Three independent experiments were carried out: (a) animals exposed for 72 h, (b) 10 days/8 h daily, and (c) 72 h exposure to MF plus 5 mg/kg of Mitomycin-C. No statistically significant differences indicative of MF effects were observed between MF exposed and control animals. In addition, an opposite effect between MF exposure and Mitomycin-C treatment in terms of chromosomal aberrations and sperm morphology was observed.     

Loss of SHP-1 phosphatase alters cytokine expression in the mouse hindbrain following cochlear ablation

Inflammatory cytokines in the central nervous system are largely modulated by glial cells and influence neuronal responses to CNS injury. The protein tyrosine phosphatase SHP-1, an intracellular regulator of many cytokine signaling pathways, has been implicated in mediating the activation of glia. There is a direct correlation between abnormally activated microglia and neuron loss within the SHP-1 deficient motheaten (me/me) mouse auditory brainstem after afferent injury. In order to determine whether loss of SHP-1 creates an aberrant cytokine environment driving the abnormal activation of me/me microglia, the expression of interleukin-4 (IL-4), interleukin-10 (IL-10), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma) was examined by enzyme-linked immunosorbent assay (ELISA). Normal uninjured me/me mice showed lower IL-10 but higher IL-1beta levels compared to wild-type. Following unilateral cochlear ablation, there is decreased expression of IL-4 and IL-10 in me/me brains compared to wild-type, but IL-1beta is significantly increased. These findings indicate that decreases in anti-inflammatory cytokines, in combination with increased expression of the pro-inflammatory cytokine IL-1beta, may initiate a robust inflammatory reaction within the me/me brain contributing to the neuronal degeneration in the deafferented me/me auditory brainstem. SHP-1 may therefore play a role in limiting CNS inflammation following injury and disease.     

Effects of variations in intragastric volume on blood pressure and splanchnic blood flow during intraduodenal glucose infusion in healthy older subjects

The postprandial reduction in blood pressure (BP) is triggered by the interaction of nutrients with the small intestine and associated with an increase in splanchnic blood flow. Gastric distension may attenuate the postprandial fall in BP. The aim of this study was to determine the effects of differences in intragastric volume, including distension at a low (100 ml) volume, on BP and superior mesenteric artery (SMA) blood flow responses to intraduodenal glucose in healthy older subjects. BP and heart rate (HR; automated device), SMA blood flow (Doppler ultrasound), mesenteric vascular resistance (MVR), and plasma norepinephrine of nine male subjects (65-75 yr old) were measured after an overnight fast on 4 separate days in random order. On each day, subjects were intubated with a nasoduodenal catheter, incorporating a duodenal infusion port, and orally with a second catheter, incorporating a barostat bag, positioned in the fundus. Each subject received a 60-min (t = 0-60 min) intraduodenal glucose infusion (3 kcal/min) and gastric distension at a volume of 1) 0 ml (V0), 2) 100 ml (V100), 3) 300 ml (V300), or 4) 500 ml (V500). Systolic BP fell (P < 0.05) during V0, but not during V100, V300, or V500. In contrast, HR (P < 0.01) and SMA blood flow (P < 0.001) increased and MVR decreased (P < 0.05) comparably on all 4 days. Plasma norepinephrine rose (P < 0.01) in response to intraduodenal glucose, with no difference between the four treatments. There was a relationship between the areas under the curve for the change in systolic BP from baseline with intragastric volume (r = 0.60, P < 0.001). In conclusion, low-volume (≤100 ml) gastric distension has the capacity to abolish the fall in BP induced by intraduodenal glucose in healthy older subjects without affecting SMA blood flow or MVR. These observations support the concept that nonnutrient gastric distension prior to a meal has potential therapeutic applications in the management of postprandial hypotension.     

Monitoring toxicity associated with parenteral sodium stibogluconate in the day-case management of returned travellers with New World cutaneous leishmaniasi

Background

Patients with New World cutaneous leishmaniasis (NWCL) caused by Leishmania Viannia are treated with parenteral sodium stibogluconate (SbV) to reduce the risk of development of mucocutanous leishmaniasis. Our centre manages patients with NWCL on an outpatient-basis. This study was conducted to assess the safety and efficacy of this approach.

Methodology

We reviewed records of 67 consecutive NWCL patients, aged 17–61 years, treated as day-cases with 20 mg/kg/day SbV for up to 28 days at our UK centre. Data had been collected in a standardised format at the time of treatment using a care-record tool. Patients reported adverse-effects daily using a structured questionnaire. Blood tests and electrocardiograms were performed twice weekly to monitor for toxicity.

Principal Findings

Parenteral SbV treatment was associated with an early, significant suppression of mean lymphocyte and platelet counts. By day four of treatment, lymphocytes reduced by 0.53×10⁹/L (CI 0.29×10⁹/L to 0.76×10⁹/L, p<0.001), and platelets by 31,000/µL (CI 16,000/µL to 46,000/µL, p<0.001). SbV was further associated with significant elevation of serum alanine transaminase concentrations, with a mean peak rise of 107 iu/L by day 13 (CI 52 iu/L to 161 iu/L, p<0.001). These disturbances were temporary and did not result in adverse clinical events. Patient-described symptoms were cumulative and at three weeks of treatment, 59.6% of patients experienced myalgia and 29.8% malaise. Treatment adherence and clinical outcomes were comparable to inpatient treatment studies. A total of 1407 individual doses of SbV resulted in only 26 nights'' hospital admission, a saving of 1381 bed-days compared to inpatient treatment.

Conclusions/Significance

In specialist centres, NWCL patients aged below 65 years and without co-morbidities can be safely and effectively treated without hospital admission. This reduces the cost of treatment, and is much preferred by patients. Twice weekly blood and electrocardiographic monitoring may be surplus to requirement in clinically well, low-risk patients.     

Very-Long-Chain Fatty Acids Are Involved in Polar Auxin Transport and Developmental Patterning in Arabidopsis

Very-long-chain fatty acids (VLCFAs) are essential for many aspects of plant development and necessary for the synthesis of seed storage triacylglycerols, epicuticular waxes, and sphingolipids. Identification of the acetyl-CoA carboxylase PASTICCINO3 and the 3-hydroxy acyl-CoA dehydratase PASTICCINO2 revealed that VLCFAs are important for cell proliferation and tissue patterning. Here, we show that the immunophilin PASTICCINO1 (PAS1) is also required for VLCFA synthesis. Impairment of PAS1 function results in reduction of VLCFA levels that particularly affects the composition of sphingolipids, known to be important for cell polarity in animals. Moreover, PAS1 associates with several enzymes of the VLCFA elongase complex in the endoplasmic reticulum. The pas1 mutants are deficient in lateral root formation and are characterized by an abnormal patterning of the embryo apex, which leads to defective cotyledon organogenesis. Our data indicate that in both tissues, defective organogenesis is associated with the mistargeting of the auxin efflux carrier PIN FORMED1 in specific cells, resulting in local alteration of polar auxin distribution. Furthermore, we show that exogenous VLCFAs rescue lateral root organogenesis and polar auxin distribution, indicating their direct involvement in these processes. Based on these data, we propose that PAS1 acts as a molecular scaffold for the fatty acid elongase complex in the endoplasmic reticulum and that the resulting VLCFAs are required for polar auxin transport and tissue patterning during plant development.     

Earthworm effects on plant growth do not necessarily decrease with soil fertility

Earthworms are known to generally increase plant growth. However, because plant-earthworm interactions are potentially mediated by soil characteristics the response of plants to earthworms should depend on the soil type. In a greenhouse microcosm experiment, the responsiveness of plants (Veronica persica, Trifolium dubium and Poa annua) to two earthworm species (in combination or not) belonging to different functional groups (Aporrectodea. caliginosa an endogeic species, Lumbricus terrestris an anecic species) was measured in term of biomass accumulation. This responsiveness was compared in two soils (nutrient rich and nutrient poor) and two mineral fertilization treatments (with and without). The main significant effects on plant growth were due to the anecic earthworm species. L. terrestris increased the shoot biomass and the total biomass of T. dubium only in the rich soil. It increased also the total biomass of P. annua without mineral fertilization but had the opposite effect with fertilization. Mineral fertilization, in the presence of L. terrestris, also reduced the total biomass of V. persica. L. terrestris did not only affect plant growth. In P. annua and V. persica A. caliginosa and L. terrestris also affected the shoot/root ratio and this effect depended on soil type. Finally, few significant interactions were found between the anecic and the endogeic earthworms and these interactions did not depend on the soil type. A general idea would be that earthworms mostly increase plant growth through the enhancement of mineralization and that earthworm effects should decrease in nutrient-rich soils or with mineral fertilization. However, our results show that this view does not hold and that other mechanisms are influential.     

Cutting edge: Chk1 directs senescence and mitotic catastrophe in recovery from G2 checkpoint arrest

Besides the well‐understood DNA damage response via establishment of G₂ checkpoint arrest, novel studies focus on the recovery from arrest by checkpoint override to monitor cell cycle re‐entry. The aim of this study was to investigate the role of Chk1 in the recovery from G₂ checkpoint arrest in HCT116 (human colorectal cancer) wt, p53^–/– and p21^–/– cell lines following H₂O₂ treatment. Firstly, DNA damage caused G₂ checkpoint activation via Chk1. Secondly, overriding G₂ checkpoint led to (i) mitotic slippage, cell cycle re‐entry in G₁ and subsequent G₁ arrest associated with senescence or (ii) premature mitotic entry in the absence of p53/p21^WAF1 causing mitotic catastrophe. We revealed subtle differences in the initial Chk1‐involved G₂ arrest with respect to p53/p21^WAF1: absence of either protein led to late G₂ arrest instead of the classic G₂ arrest during checkpoint initiation, and this impacted the release back into the cell cycle. Thus, G₂ arrest correlated with downstream senescence, but late G₂ arrest led to mitotic catastrophe, although both cell cycle re‐entries were linked to upstream Chk1 signalling. Chk1 knockdown deciphered that Chk1 defines long‐term DNA damage responses causing cell cycle re‐entry. We propose that recovery from oxidative DNA damage‐induced G₂ arrest requires Chk1. It works as cutting edge and navigates cells to senescence or mitotic catastrophe. The decision, however, seems to depend on p53/p21^WAF1. The general relevance of Chk1 as an important determinant of recovery from G₂ checkpoint arrest was verified in HT29 colorectal cancer cells.