Plant defense elicitors fail to protect Viburnum dentatum from herbivory by viburnum leaf beetle (Coleoptera: Chrysomelidae)

Pyrrhalta viburni (Paykull) (Coleoptera: Chrysomelidae), a new landscape pest in the United States, feeds in both the larval and adult stages on foliage of plants in the genus Viburnum. A field trial was conducted from 2004 to 2006 to examine the impact of several elicitors of plant defense on ability of arrowwood viburnum (Viburnum dentatum L.) to resist attack by P. viburni in both larval and adult stages. The treatments included jasmonic acid (JA), harpin, and paclobutrazol. For comparison, imidacloprid and untreated controls were included in the trial. The soil-applied treatments (paclobutrazol and imidacloprid) were applied once during the trial (spring 2004), and the foliarly applied treatments (JA and harpin) were applied each spring. Herbivory by viburnum leaf beetle larvae and adults was measured yearly in spring and summer, respectively, and plant height was recorded at the end of each growing season. The only treatment that decreased feeding by viburnum leaf beetle was imidacloprid; these plants were virtually untouched throughout the duration of the trial. Plants treated with JA and harpin actually suffered greater feeding damage at the end of the second growing season; other than this observation, the elicitors had no impact on viburnum leaf beetle. As expected, plant height was decreased for the shrubs treated with paclobutrazol, a plant growth regulator, and unaffected by JA and harpin. Plant height was increased for the shrubs treated with imidacloprid. These shrubs also seemed to be protected from viburnum leaf beetle after residues dropped below lethal levels.     

Variation in Prokaryotic Community Composition as a Function of Resource Availability in Tidal Creek Sediments

In anaerobic coastal sediments, hydrolytic and/or fermentative bacteria degrade polymeric material and produce labile intermediates, which are used by terminal metabolizers to complete the conversion of organic material to CO₂. We used molecular approaches to evaluate the response of two bacterial terminal metabolizer groups from a coastal tidal creek sediments, sulfate reducers and methanogens, to controlled changes in carbon resource supply. Tidal creek sediment bioreactors were established in April and August 2004. For each date, intact sediment sections were continuously supplied with flowthrough seawater that was either unamended or amended with the high-molecular-weight polysaccharide dextran. Biogeochemical data indicate that the activity of fermenting bacteria and the terminal metabolizers was limited by organic carbon supply during both experiments, with a significant increase in net volatile fatty acid (VFA) production and rates of sulfate reduction and methanogenesis following dextran addition. Community composition (measured by using terminal restriction fragment length polymorphism analysis, and functional gene [dsrA, mcrA] clone libraries) changed from April to August. However, community composition was not different between amended and unamended cores within each month, despite the change in resource level. Moreover, there was no relationship between community richness and evenness with resource level. This lack of variation in community composition with C addition could be attributed to the dynamic environment these sediment communities experience in situ. Fluctuations in VFA concentrations are most likely very high, so that the dominant bacterial species must be able to outcompete other species at both high and low resource levels.     

Influence of estradiol on the secretion of oxytocin and prostaglandin F2 alpha during luteolysis in the ewe.

Twenty ewes of mixed breeds were randomly assigned in equal numbers to one of four groups in a 2 x 2 factorial design. The factors were x-irradiation to destroy ovarian follicles or sham irradiation and the administration of estradiol-containing or empty (placebo) implants. Surgery for irradiation was performed on Day 8 of the cycle. Blood samples were withdrawn from jugular catheters at 1.5-h intervals from Day 10 to Day 17. Luteolysis was not observed by Day 17 in 4 of 5 placebo-treated ewes after destruction of ovarian follicles. Luteolysis was observed in 4 of 5 ewes of the sham-irradiated, placebo-treated group and in all ewes that received estradiol whether or not ovarian follicles had been destroyed. The longest (p less than 0.07) interval between peaks of 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) was observed in the x-irradiated, placebo-treated group, whereas the administration of estradiol reduced (p less than 0.01) the interval between PGFM peaks. These findings indicate that a short interpulse interval in the secretion of prostaglandin F2 alpha (PGF2 alpha) is associated with luteolysis. It is possible that the reduced interpulse interval was either an effect of estradiol that caused luteolysis or a secondary event resulting from luteolysis. The administration of estradiol decreased (p less than 0.05) the number of episodes of oxytocin secretion during luteolysis and increased (p less than 0.01) the interval between episodes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Abnormal T cells from MRL/Mp-lpr/lpr mice do not respond to anti-T-cell-receptor antibody or tumor promoter and calcium ionophore A23187 despite the presence of the T-cell-receptor complex and protein kinase c

Abnormal T cells from autoimmune MRL/Mp-lpr/lpr mice express T-cell-receptor complexes on their surfaces. These receptors are nonfunctional, since monoclonal anti-T-cell-receptor antibody-conjugated beads, which normally activate receptor-bearing T cells, were unable to activate these abnormal T cells. In addition, these abnormal T cells are unresponsive to the synergistic effect of phorbolmyristate acetate (PMA) and calcium ionophore A23187, as quantitated by proliferation, interleukin-2(IL-2) production, and the expression of IL-2 receptors. The failure of abnormal T cells to respond to PMA is not due to the absence of PMA receptors since Scatchard plot analysis reveals that there are 1-1.5 X 10(5) PMA-binding sites/cell with a Kd of 6-10 nM on these abnormal T cells. Similar to normal T lymphocytes, protein kinase c activity can be readily detected in the cytosolic fraction of these abnormal T cells. More importantly, in vitro culture of the abnormal T cells with PMA results in translocation of protein kinase c activity from the cytosolic fraction to the membrane fraction. From these experiments we concluded that the defect in the signal-transducing machinery in MRL/Mp-lpr/lpr T cells is not due to the lack of PMA receptors or the absence of protein kinase c activity, but may result from events which occur after the activation and translocation of protein kinase c. However, whether defects in response to a physiological stimulus (i.e., anti-receptor antibody) could occur in a step prior to protein kinase c activation remains to be determined.     

Application of airline pilots' hours to junior doctors.

OBJECTIVE--To determine the staff required if the rules for airline pilots'' hours of work are applied to junior doctors. DESIGN--Junior anaesthetists recorded their workload from 1 March 1988 to May 31 1988. SETTING--District general hospital. SUBJECTS--Two groups of three junior anaesthetists sharing a one in three rota to provide continuous emergency cover. INTERVENTIONS--By using the guidelines published by the Civil Aviation Authority in The Avoidance of Excessive Fatigue in Aircrews schedules were drawn up to cover the hours that junior doctors had been on duty. RESULTS--Each anaesthetist provided emergency and routine cover for 48-112 (mean 75) hours each week. To cover the work of six junior anaesthetists on an annual basis would require 26 doctors if they were working within the Civil Aviation Authority''s guidelines. CONCLUSIONS--Junior anaesthetists'' hours are much longer than those of airline pilots. Both professions entail considerable periods of monitoring interspersed with episodes of high demands on physical and cognitive skills. Errors induced by fatigue made by anaesthetists and pilots could result in death. The medical profession should define rules similar to those of the aviation authority to prevent junior doctors having to work unsafe numbers of hours.     

Mouse mutants provide new insights into the role of extracellular matrix in cell migration and differentiation

Migratory cell populations in the developing embryo disperse, localize and eventually differentiate in environments rich in extracellular matrix material. The extracellular matrix provides both a substratum for migration and a source of differentiative cues for the developing cells. Mutations in mice and other animals that alter embryonic interstitial environments are now providing information about the role of the extracellular matrix in these early developmental processes.