In vivo photopharmacology with light-activated opioid drugs

Traditional methods for site-specific drug delivery in the brain are slow, invasive, and difficult to interface with recordings of neural activity. Here, we demonstrate the feasibility and experimental advantages of in vivo photopharmacology using "caged" opioid drugs that are activated in the brain with light after systemic administration in an inactive form. To enable bidirectional manipulations of endogenous opioid receptors in vivo, we developed photoactivatable oxymorphone (PhOX) and photoactivatable naloxone (PhNX), photoactivatable variants of the mu opioid receptor agonist oxymorphone and the antagonist naloxone. Photoactivation of PhOX in multiple brain areas produced local changes in receptor occupancy, brain metabolic activity, neuronal calcium activity, neurochemical signaling, and multiple pain- and reward-related behaviors. Combining PhOX photoactivation with optical recording of extracellular dopamine revealed adaptations in the opioid sensitivity of mesolimbic dopamine circuitry in response to chronic morphine administration. This work establishes a general experimental framework for using in vivo photopharmacology to study the neural basis of drug action.

Mu Opioid Receptor-Expressing Neurons in the Dorsal Raphe Nucleus Are Involved in Reward Processing and Affective Behaviors

BACKGROUND

Mu opioid receptors (MORs) are key for reward processing, mostly studied in dopaminergic pathways. MORs are also expressed in the dorsal raphe nucleus (DRN), which is central for the modulation of reward and mood, but MOR function in the DRN remains underexplored. Here, we investigated whether MOR-expressing neurons of the DRN (DRN-MOR neurons) participate in reward and emotional responses.

METHODS

We characterized DRN-MOR neurons anatomically using immunohistochemistry and functionally using fiber photometry in responses to morphine and rewarding/aversive stimuli. We tested the effect of opioid uncaging on the DRN on place conditioning. We examined the effect of DRN-MOR neuron optostimulation on positive reinforcement and mood-related behaviors. We mapped their projections and selected DRN-MOR neurons projecting to the lateral hypothalamus for a similar optogenetic experimentation.

RESULTS

DRN-MOR neurons form a heterogeneous neuronal population essentially composed of GABAergic (gamma-aminobutyric acidergic) and glutamatergic neurons. Calcium activity of DRN-MOR neurons was inhibited by rewarding stimuli and morphine. Local photo-uncaging of oxymorphone in the DRN produced conditioned place preference. DRN-MOR neuron optostimulation triggered real-time place preference and was self-administered, promoted social preference, and reduced anxiety and passive coping. Finally, specific optostimulation of DRN-MOR neurons projecting to the lateral hypothalamus recapitulated the reinforcing effects of total DRN-MOR neuron stimulation.

CONCLUSIONS

Our data show that DRN-MOR neurons respond to rewarding stimuli and that their optoactivation has reinforcing effects and promotes positive emotional responses, an activity which is partially mediated by their projections to the lateral hypothalamus. Our study also suggests a complex regulation of DRN activity by MOR opioids, involving mixed inhibition/activation mechanisms that fine-tune DRN function.

In vivo photopharmacology with a caged mu opioid receptor agonist drives rapid changes in behavior

Photoactivatable drugs and peptides can drive quantitative studies into receptor signaling with high spatiotemporal precision, yet few are compatible with behavioral studies in mammals. We developed CNV-Y-DAMGO-a caged derivative of the mu opioid receptor-selective peptide agonist DAMGO. Photoactivation in the mouse ventral tegmental area produced an opioid-dependent increase in locomotion within seconds of illumination. These results demonstrate the power of in vivo photopharmacology for dynamic studies into animal behavior.

In vivo photopharmacology with light-activated opioid drugs

Traditional methods for site-specific drug delivery in the brain are slow, invasive, and difficult to interface with recordings of neural activity. Here, we demonstrate the feasibility and experimental advantages of in vivo photopharmacology using "caged" opioid drugs that are activated in the brain with light after systemic administration in an inactive form. To enable bidirectional manipulations of endogenous opioid receptors in vivo , we developed PhOX and PhNX, photoactivatable variants of the mu opioid receptor agonist oxymorphone and the antagonist naloxone. Photoactivation of PhOX in multiple brain areas produced local changes in receptor occupancy, brain metabolic activity, neuronal calcium activity, neurochemical signaling, and multiple pain- and reward-related behaviors. Combining PhOX photoactivation with optical recording of extracellular dopamine revealed adaptations in the opioid sensitivity of mesolimbic dopamine circuitry during chronic morphine administration. This work establishes a general experimental framework for using in vivo photopharmacology to study the neural basis of drug action.

Highlights

A photoactivatable opioid agonist (PhOX) and antagonist (PhNX) for in vivo photopharmacology. Systemic pro-drug delivery followed by local photoactivation in the brain. In vivo photopharmacology produces behavioral changes within seconds of photostimulation. In vivo photopharmacology enables all-optical pharmacology and physiology.

Suboptimal sleep and incident cardiovascular disease among African Americans in the Jackson Heart Study (JHS)

BACKGROUND

Suboptimal sleep, including insufficient/long sleep duration and poor sleep quality, is a risk factor for cardiovascular disease (CVD) common but there is little information among African Americans, a group with a disproportionate CVD burden. The current study examined the association between suboptimal sleep and incident CVD among African Americans.

METHODS

This study included 4,522 African Americans without CVD at baseline (2000-2004) of the Jackson Heart Study (JHS). Self-reported sleep duration was defined as very short (<6 h/night), short (6 h/night), recommended (7-8 h/night), and long (≥9 h/night). Participants' self-reported sleep quality was defined as "high" and "low" quality. Suboptimal sleep was defined by low quality sleep and/or insufficient/long sleep duration. Incident CVD was a composite of incident coronary heart disease and stroke. Associations between suboptimal sleep and incident CVD were examined using Cox proportional hazards models over 15 follow-up years with adjustment for predictors of CVD risk and obstructive sleep apnea.

RESULTS

Sample mean age was 54 years (SD = 13), 64% female and 66% reported suboptimal sleep. Suboptimal sleep was not associated with incident CVD after covariate adjustment [HR(95% CI) = 1.18(0.97-1.46)]. Long [HR(95%CI) = 1.32(1.02-1.70)] and very short [HR(95% CI) = 1.56(1.06-2.30)] sleep duration were associated with incident CVD relative to recommended sleep duration. Low quality sleep was not associated with incident CVD (p = 0.413).

CONCLUSIONS

Long and very short self-reported sleep duration but not self-reported sleep quality were associated with increased hazard of incident CVD.

0784 Associations Of Sleep Regularity And Chronotype With Hypertension Among African Americans In The Jackson Heart Sleep Study

Introduction

Emerging evidence suggests that disparities in sleep regularity, a marker of circadian disruption, contributes to hypertension disparities; however, data among African Americans are limited. We examined associations of sleep regularity and chronotype with hypertension among African Americans in the Jackson Heart Sleep Study (JHSS).

Methods

Participants underwent 7-day actigraphy, completed questionnaires, and had seated blood pressure (BP) measured as part of the JHSS (2012 - 2016). Sleep regularity was defined as the standard deviation (SD) of actigraphy-measured sleep onset timing or sleep duration. Chronotype was assessed by the Morningness-Eveningness Questionnaire. Prevalent hypertension was defined as either a systolic BP ≥ 130 mmHg or diastolic BP ≥ 80mmHg, antihypertensive medication use, or self-report of diagnosed hypertension. Multivariable logistic regression models were fit to estimate the prevalence odds ratio (OR) and 95% confidence intervals for the associations of hypertension with sleep regularity measures (SD of sleep onset timing and sleep duration) and chronotype adjusted for covariates.

Results

Participants (n=830) on average were 63.4 years (SD:10.7), mostly female (66.3%) and hypertensive (85.8%). Compared to individuals with sleep onset SD &lt; 30 minutes, higher adjusted odds of hypertension was observed with increasing variability: OR:1.87 (CI:0.99-3.56); OR:2.16 (1.06-4.39), and OR:2.41 (1.12-5.20), for SD &gt; 30 & ≤ 60, &gt; 60 & ≤ 90 and &gt; 90 minutes, respectively. Among non-shift workers, definite morning and evening types compared to intermediates had higher adjusted odds of hypertension, OR:1.71 (1.04-2.83) and OR:2.56 (1.12-5.84), respectively. There were no observed associations for the SD of sleep duration with hypertension.

Conclusion

Increased sleep onset variability and extreme chronotypes were associated with prevalent hypertension, supporting interventions targeting sleep hygiene recommendations promoting regular sleep. Future research is needed to understand sleep patterns and risk of cardiovascular disease according to chronotype.

Support

NHLBI K01HL138211 and HL110068-03S1

1097 Sleep Disturbances, Sleep Burden, And Depressive Symptoms In US Hispanics/Latinos: Results From The HCHS/SOL Sueño Study

Introduction

While sleep disturbances and depression often co-occur, these associations are understudied among Hispanics/Latinos. We examined the associations of sleep disturbances and sleep burden with depressive symptoms among Hispanic/Latino adults in the United States.

Methods

We used cross-sectional data from the Hispanic Community Health Study/Study of Latinos Sueño Ancillary study (2010-2013). The study enrolled 2072 adults (ages 18-64; 51.5% females) who completed one-week wrist-actigraphy and sleep questionnaires. Sleep burden was operationalized as the total count of sleep disturbances across six domains (duration, efficiency, midpoint, variability, insomnia, sleepiness). Depressive symptoms were assessed using the Center for Epidemiological Studies Depression scale (CESD-10). We used weighted survey linear regressions to evaluate the association of sleep disturbances and sleep burden with elevated depressive symptoms (CESD≥10) in individual models adjusted for age, gender, site, heritage, nativity, education, income, and employment. Sensitivity analyses further adjusted for behavioral health risk factors and apnea-hypopnea index.

Results

An estimated 28.3% had elevated depressive symptoms, 8.0% had short sleep duration (&lt;6 hours of sleep), 10.9% had long sleep duration (&gt;9 hours), 45.2% exhibited a later sleep midpoint (≥4:00AM), 38.4% had high sleep timing variability (upper third tertile for between day sleep midpoint), 15.3% had insomnia (ISI≥10), 17.3% had excessive daytime sleepiness (ESS ≥10), 21.5% had poor sleep efficiency (&lt;85%), and 77.4% had a total sleep burden count of ≥0. Insomnia (ß=0.49,95%CI:.43,.56), later sleep timing (ß=0.10,95%CI:.04,.16), excessive daytime sleepiness (ß=0.19,95%CI:.11,.27), poor sleep efficiency (ß=0.09,95%CI:.02,.17), high variability (ß=0.07, 95%CI:.01,.12), and sleep burden (ß=0.11,95%CI:.09,.13), were each positively associated with elevated depressive symptoms in individual adjusted models and sensitivity analyses. Extreme sleep durations were not associated with elevated depressive symptoms.

Conclusion

Multiple inter-related sleep disturbances, particularly those pertaining to sleep quality and timing, are associated with depression and may be targets for future interventions aimed at improving mood among Hispanics/Latinos.

Support

HL127307, HL098927, HL125748

1007 Sociodemographic, Lifestyle and Dietary Correlates of Actigraphy-Measured Irregular Sleep Schedules in the Multi-Ethnic Study of Atherosclerosis

Introduction

Increasing evidence links daily variability in sleep schedules to increased cardiometabolic risk. Little is known, however, regarding sociodemographic and behavioral correlates of irregular sleep schedules that may help identify causes or consequences of irregular sleep.

Methods

Among 1,946 participants from the Multi-Ethnic Study of Atherosclerosis, we examined the cross-sectional associations of irregular sleep schedules with sociodemographic, lifestyle, dietary factors, and actigraphy-based indices of rest-wake rhythms using multiple linear regression with adjustment for age, sex, race/ethnicity, education, income, marital status and work schedules. Sleep regularity was assessed using standard deviations (SD) in actigraphy-measured sleep duration and sleep onset timing across 7 days.

Results

Compared to Whites, the 7-day sleep duration SD (95% CI) was 17.4min (12.6, 22.2) higher in African-Americans, 10.4min (4.8, 16.0) higher in Hispanics and 7.9min (1.3, 14.4) higher in Chinese. Shift versus regular work was associated with 11.4min (5.1, 17.7) higher sleep duration SD. Irregular sleep duration was associated with lower income (p=0.006), higher depressive symptoms (p&lt;0.0001), higher BMI (p=0.004) and current smoking (p=0.06). Higher sleep duration variability was associated with lower Alternative Healthy Eating Index (p=0.01), mainly due to suboptimal intakes of fruits, whole grains and nuts/legumes. No associations were observed for age, sex, education, marital status or number of meals per day. While sleep duration variability was not associated with self-reported physical activity level or actigraphy-measured 7-day mean activity count, sleep duration SD was inversely associated with relative amplitude (difference between the most versus the least active period; p&lt;0.0001) and inter-daily stability (synchronization between rest-activity patterns and environmental zeitgebers; p&lt;0.0001) of 24-h rest-activity patterns. Similar results were observed for sleep onset timing SD.

Conclusion

Substantial differences by sociodemographic factors exist regarding the consistency of day-to-day sleep schedules. Irregular sleep schedules are associated with overall circadian disruption across the day and some unhealthy lifestyle behaviors. Future studies are needed to understand temporal relationships of the observed associations.

Support

NIH grants K01HL143034, R35HL135818

Susceptibility of Weedy Hosts from Pacific Northwest Potato Production Systems to Crop-Aggressive Isolates of Verticillium dahliae

Verticillium wilt, caused by Verticillium dahliae, is a disease of dicotyledonous crops such as potato and has a wide host range and persistent, long-term survival structures called microsclerotia that can persist in soil for up to 14 years. Some V. dahliae isolates are particularly aggressive on a specific plant host while retaining the ability to infect a wide range of other hosts. Weeds can serve as hosts for V. dahliae but whether they serve as sources of inoculum for aggressive isolates of V. dahliae to crop hosts is unknown. The goal of this research was to quantify V. dahliae microsclerotia obtained from 16 weeds which were grown in the greenhouse. Potting medium was infested with one of eight V. dahliae isolates from potato, mint, sugar beet, sunflower, tomato, and watermelon. The isolates from mint and potato were aggressive on the host from which they were originally isolated. All 16 weeds were infected by at least one V. dahliae isolate, although the number of microsclerotia produced from some infections was relatively low (≤5 microsclerotia/g of dry plant). Black nightshade yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in three of four trials in the greenhouse (second trial false discovery rate, adjusted P ≤ 0.0158; third trial, P ≤ 0.0264; and fourth trial, P ≤ 0.0193). Litchi tomato yielded greater numbers of microsclerotia of the V. dahliae potato isolate than any other isolate in one of four trials (first trial, P ≤ 0.0149). A V. dahliae isolate from tomato yielded greater numbers of microsclerotia in large crabgrass and wild oat in a second trial (P ≤ 0.0158). Weeds, depending on the species, grown during and between potato crop rotations may increase the number of microsclerotia of the potato-aggressive isolates of V. dahliae.

Evaluation of Solanum sisymbriifolium as a Potential Inoculum Source of Verticillium dahliae and Colletotrichum coccodes

Solanum sisymbriifolium, the litchi tomato, is a perennial herbaceous plant from South America that is used as a trap crop to reduce soilborne populations of the pale cyst nematode Globodera pallida, an important potato pathogen. Possible interactions of soilborne potato pathogens Verticillium dahliae and Colletotrichum coccodes with litchi tomato are unknown, yet important for potato production if litchi tomato is to be planted as a trap crop. The goal of this research was to quantitatively assess if litchi tomato is a potential inoculum source for C. coccodes and V. dahliae by comparing colony forming units (CFU) observed in litchi tomato to susceptible and resistant potato cultivars. The potato cvs. Alturas (P = 0.0003), Ranger Russet (P = 0.0193), and Russet Norkotah (P = 0.0022) produced more CFUs of the potato pathotype of V. dahliae than litchi tomato the first of two years of greenhouse trials. Significantly more CFUs of the potato pathotype of V. dahliae were quantified from stems and roots of only cv. Russet Norkotah compared with litchi tomato (P = 0.0001) in the second year. The CFUs for C. coccodes varied between litchi tomato and the potato cvs., perhaps due to varying levels of resistance since litchi tomato is from a selected intermated seed source. Based on these data, the effect of litchi tomato in rotation with potato is likely to have limited effect on the proliferation of V. dahliae or C. coccodes populations in the soil when compared with a susceptible potato cultivar.

Verticillium dahliae Infects, Alters Plant Biomass, and Produces Inoculum on Rotation Crops

Verticillium wilt, caused by Verticillium dahliae, reduces yields of potato and mint. Crop rotation is a potential management tactic for Verticillium wilt; however, the wide host range of V. dahliae may limit the effectiveness of this tactic. The hypothesis that rotation crops are infected by V. dahliae inoculum originating from potato and mint was tested by inoculation of mustards, grasses, and Austrian winter pea with eight isolates of V. dahliae. Inoculum density was estimated from plants and soil. Typical wilt symptoms were not observed in any rotation crop but plant biomass of some crops was reduced, not affected, or increased by infection of specific isolates. Each isolate was host-specific and infected a subset of the rotation crops tested but microsclerotia from at least one isolate were observed on each rotation crop. Some isolates were host-adapted and differentially altered plant biomass or produced differential amounts of inoculum on rotation crops like arugula and Austrian winter pea, which supported more inoculum of specific isolates than potato. Evidence of asymptomatic and symptomatic infection and differential inoculum formation of V. dahliae on rotation crops presented here will be useful in designing rotations for management of Verticillium wilt.

Five Reasons to Consider Phytophthora infestans a Reemerging Pathogen

Phytophthora infestans has been a named pathogen for well over 150 years and yet it continues to "emerge", with thousands of articles published each year on it and the late blight disease that it causes. This review explores five attributes of this oomycete pathogen that maintain this constant attention. First, the historical tragedy associated with this disease (Irish potato famine) causes many people to be fascinated with the pathogen. Current technology now enables investigators to answer some questions of historical significance. Second, the devastation caused by the pathogen continues to appear in surprising new locations or with surprising new intensity. Third, populations of P. infestans worldwide are in flux, with changes that have major implications to disease management. Fourth, the genomics revolution has enabled investigators to make tremendous progress in terms of understanding the molecular biology (especially the pathogenicity) of P. infestans. Fifth, there remain many compelling unanswered questions.

Inferring outcrossing in the homothallic fungus Sclerotinia sclerotiorum using linkage disequilibrium decay

The occurrence and frequency of outcrossing in homothallic fungal species in nature is an unresolved question. Here we report detection of frequent outcrossing in the homothallic fungus Sclerotinia sclerotiorum. In using multilocus linkage disequilibrium (LD) to infer recombination among microsatellite alleles, high mutation rates confound the estimates of recombination. To distinguish high mutation rates from recombination to infer outcrossing, 8 population samples comprising 268 S. sclerotiorum isolates from widely distributed agricultural fields were genotyped for 12 microsatellite markers, resulting in multiple polymorphic markers on three chromosomes. Each isolate was homokaryotic for the 12 loci. Pairwise LD was estimated using three methods: Fisher's exact test, index of association (IA) and Hedrick's D'. For most of the populations, pairwise LD decayed with increasing physical distance between loci in two of the three chromosomes. Therefore, the observed recombination of alleles cannot be simply attributed to mutation alone. Different recombination rates in various DNA regions (recombination hot/cold spots) and different evolutionary histories of the populations could explain the observed differences in rates of LD decay among the chromosomes and among populations. The majority of the isolates exhibited mycelial incompatibility, minimizing the possibility of heterokaryon formation and mitotic recombination. Thus, the observed high intrachromosomal recombination is due to meiotic recombination, suggesting frequent outcrossing in these populations, supporting the view that homothallism favors universal compatibility of gametes instead of traditionally believed haploid selfing in S. sclerotiorum. Frequent outcrossing facilitates emergence and spread of new traits such as fungicide resistance, increasing difficulties in managing Sclerotinia diseases.

What does the nr5S DNA multigene family tell us about the genomic relationship between Dasypyrum breviaristatum and D. villosum (Triticeae: Poaceae)?

The genus Dasypyrum contains two species: the annual and widespread D. villosum (2x = 2n = 14) and the perennial and generally rare D. breviaristatum (2x = 2n = 14 and 4x = 2n = 28). The origin of the latter and its genome constitution have been subject of several studies. There is agreement that the genome of the diploid D. villosum (VV) is different from the diploid cytotype of D. breviaristatum (VbVb), but there is no agreement of the constitution of the tetraploid cytotype, specifically whether is it an autotetraploid or an allotetraploid. This is a long-standing disagreement that this study aims to resolve using the 5S nrDNA as a genomic marker. Our studies suggest that the 4x D. breviaristatum is an allotetraploid (VVVbVb).

What does the 5S rRNA multigene family tell us about the origin of the annual Triticeae (Poaceae)?

We have investigated the complex relationships among the annual genera within the tribe Triticeae through phylogenetic analyses of the 5S rRNA multigene family. Cloned sequences were assigned to groups of orthologous sequences, called unit classes, that were subjected to several analyses including BLAST (Basic Local Alignment Search Tool) searches to assess possible ancestral relationships with perennial genera; phylogenetic analyses using parsimony (Pars), maximum likelihood (ML), and Bayesian methods; and minimum reticulation networks from the Pars, ML, and Bayesian trees. In this study, we included genera with both annual and perennial species, such as Dasypyrum, Hordeum, and Secale. BLAST pointed to Pseudoroegneria (carrier of the St genome) and possibly Thinopyrum (carrier of the J genome) as the potential next of kin. However, Thinopyrum and Pseudoroegneria have never fallen together on the individual trees with the former generally associated with Crithopsis, Aegilops, Triticum, and Dasypyrum, while the latter is usually associated with the rest of the genera within Triticeae. The "long" unit classes placed Dasypyrum breviaristatum together with Dasypyrum villosum, whereas the "short" unit classes put them far apart on the trees. None of the gene trees alone was able to summarize the complex relationships among the genera, in line with previous results in the Triticeae. However, the application of tools designed to display phylogenetic networks was able to depict the complex links among the genera based on the short and the long gene trees, including the close link between Thinopyrum and Pseudoroegneria suggested by the phylogenetic analyses. In addition, our analyses provide support for the hypothesis that at least some annual Triticeae taxa are derived from their perennial relatives.

First Report of Blackleg Caused by Leptosphaeria maculans on Canola in Idaho

Canola (Brassica napus L.) is produced in the dryland agriculture areas of eastern Washington State and northern Idaho, often in rotation with cereal cropping systems. Canola is also used as a rotation crop in irrigated circles in the Columbia Basin of Washington and southern Idaho, where potato is the main cash crop. In 2011, 7,700 ha of canola were harvested in Idaho and 4,200 ha in Washington. One of the major diseases of canola around the world is blackleg, caused by Leptosphaeria maculans (aggressive) and L. biglobosa (non-aggressive). Both Washington and Idaho have been considered blackleg-free, and production of canola in Idaho is subject to government regulations. Canola seed originating from outside of Washington and Idaho should have a phytosanitary certificate. This disease is widespread in Canada and the U.S. Northern Plains, Midwest, and South, and is the major disease of canola in these areas. In August 2011, a sample from a canola field in Bonners Ferry, Idaho, was brought for diagnosis to Washington State University. The canola stems showed the typical gray to dark grey lesions with black pycnidia. The pycnidia and conidia were examined microscopically, and found to be similar to descriptions of Phoma lingam, the anamorph of L. maculans (2). Samples were sent to the University of Manitoba for confirmation with PCR. The pathogen was cultured out of stems on V8 juice agar amended with streptomycin and 22 single pynidiospore isolates were made from the cultures. DNA was extracted from the cultures using methods described in Fernando et al. (1) and a multiplex PCR was performed with species-specific primers for L. maculans and L. biglobosa. The reaction should produce a 330-bp amplicon for L. maculans and a 440-bp amplicon for L. biglobosa. Based on this, all 22 isolates were identified as L. maculans. The susceptible cultivar Westar was inoculated with the isolates, by wound inoculating 7-day-old cotyledons with a concentration of 10⁷ spores/ml. Plants were kept in a moist chamber at 23°C. After 14 days, plants were rated for disease with a 0 to 9 scale, where 0 = no infection and 9 = tissue collapse and appearance of pycnidiospores. Isolates with rating ≥5 are considered virulent. All isolates produced a rating of 7 to 9, indicating a high level of virulence. The source of the seed used in the infested fields is not known at this time. This disease is seedborne, and may pose a threat to the two major vegetable and oilseed brassica seed production areas of Washington: the Skagit River valley of western Washington and the Columbia Basin area of central Washington. In addition, the susceptibility of Pacific Northwest varieties of canola and other brassica oilseeds is largely unknown. References: (1) W. G. D. Fernando et al. Plant Dis. 90:1337, 2006. (2) S. Roger Rimmer et al. Compendium of Brassica Diseases, APS Press, 2007.

First Report of Pectobacterium wasabiae Causing Aerial Stem Rot of Potato in Washington State

Aerial stem rot of potato (Solanum tuberosum), also known as bacterial stem rot, is often caused by the pectolytic bacteria Pectobacterium (Erwinia) carotovorum subsp. carotovorum, P. atrosepticum, or Dickeya spp. (3). A survey was carried out in August 2008 in 'Russet Burbank' potato fields exhibiting aerial stem rot symptoms in the Columbia Basin of Washington State. One bacterial strain isolated during the survey, PwO405, exhibited pectolytic ability on crystal violet pectate (CVP) agar and potato slices and failed to grow at 37°C, but physiological tests did not conclusively distinguish the bacterium as P. atrosepticum (1). The bacterium was positive for ONPG, N-acetylglucosaminyl transferase, gelatin liquefaction, and acid production from D-galactose, lactose, melibiose, raffinose, citrate, and trehalose. The bacterium was negative for indole production and acid production from maltose, α-methyl-D-glucoside, sorbitol, D-arabitol, inositol, inulin, and melezitose. Molecular identification of the bacterium was performed with 16S rRNA, aconitase (acnA), and malate dehydrogenase (mdh) coding sequences as previously described (2,4). Partial sequences of 16S rRNA (1,408 bp) and acnA (412 bp) genes (GenBank Accession Nos. JQ723958 and JQ723959, respectively) exhibited 99% shared identities with P. wasabiae strain WPP163, while the mdh sequence (435 bp) (GenBank Accession No. JQ723960) exhibited 100% shared identity with mdh sequences from three P. wasabiae strains (NZEC9, NZEC10, and NZEC8974). Maximum parsimony analysis using concatenated acnA and mdh sequences from this study and Pectobacterium sequences previously deposited in GenBank (2,4) clustered strain PwO405 with other P. wasabiae strains. Three 7-week-old 'Russet Norkotah' potato plants were wound-inoculated by inserting a sterile 23 gauge needle just above a central leaf axil at a depth of 1 mm. A 10-μl drop of inoculum (10⁴ CFU) was placed on the wound. Plants were exposed to a 24-h leaf wetness period (90 to 100% RH in a mist chamber) and lesions were measured. All three inoculated plants exhibited aerial stem rot symptoms similar to those observed in the field, including brown water-soaked lesions that spread acropetally and basipetally. Upon drying, the lesions became shriveled and turned dark brown to black. Some plants exhibited hollowing of the stems and unilateral wilt on the side of the lesion. Symptoms were not observed on water-inoculated controls. The bacteria that were reisolated into pure culture from all three inoculated stems caused pitting on CVP and exhibited the same morphology as the original culture and were confirmed as P. wasabiae using 16S rRNA, acnA, and mdh coding sequences, fulfilling Koch's postulates. Stem rot ability of the bacterium was also confirmed on four potato cultivars: 'Ranger Russet,' 'Russet Burbank,' 'Russet Norkotah,' and 'Umatilla Russet' by wound-inoculating six single-stem plants of each cultivar as described above. To our knowledge, this is the first report of aerial stem rot of potato caused by P. wasabiae in Washington State. References: (1) S. De Boer and A. Kelman. Page 56 in: Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd ed. N. Schaad et al., ed. APS Press, St. Paul, 2001. (2) A. Pitman et al. Eur. J. Plant Pathol. 32:211, 2010. (3) M. Powelson and G. Franc. Page 10 in: Compendium of Potato Diseases. W. Stevenson et al., ed. APS Press, St. Paul, 2002. (4) M. Yap et al. Appl. Environ. Microbiol. 70:3013, 2004.

The effect of the steroid sulfatase inhibitor (p-O-sulfamoyl)-tetradecanoyl tyramine (DU-14) on learning and memory in rats with selective lesion of septal-hippocampal cholinergic tract

Dehydroepiandrosterone sulfate (DHEAS), is an excitatory neurosteroid synthesized within the CNS that modulates brain function. Effects associated with augmented DHEAS include learning and memory enhancement. Inhibitors of the steroid sulfatase enzyme increase brain DHEAS levels and can also facilitate learning and memory. This study investigated the effect of steroid sulfatase inhibition on learning and memory in rats with selective cholinergic lesion of the septo-hippocampal tract using passive avoidance and delayed matching to position T-maze (DMP) paradigms. The selective cholinergic immunotoxin 192 IgG-saporin (SAP) was infused into the medial septum of animals and then tested using a step-through passive avoidance paradigm or DMP paradigm. Peripheral administration of the steroid sulfatase inhibitor, DU-14, increased step-through latency following footshock in rats with SAP lesion compared to both vehicle treated control and lesioned animals (p<0.05). However, in the DMP task, steroid sulfatase inhibition impaired acquisition in lesioned rats while having no effect on intact animals. These results suggest that steroid sulfatase inhibition facilitates memory associated with contextual fear, but impairs acquisition of spatial memory tasks in rats with selective lesion of the septo-hippocampal tract.

Expression of polyhydroxybutyric acid as a model for metabolic engineering of soybean seed coats

The feasibility of genetically engineering soybean seed coats to divert metabolism towards the production of novel biochemicals was tested. The genes phbA, phbB, phbC from Ralstonia eutropha each under the control of the seed coat peroxidase promoter were introduced into soybean and the production of polyhydroxybutyrate (PHB) was assayed. The analysis of seed coats arising from 4 independent transformation events demonstrated that PHB was produced at a mean of 0.12% seed coat dried weight with individual values up to 0.36%. These values demonstrate that it is possible to metabolically engineer soybean seed coats.

Systematic review: the burden of disruptive gastro-oesophageal reflux disease on health-related quality of life

BACKGROUND

About one-third of patients with gastro-oesophageal reflux disease (GERD) have frequent and/or severe reflux symptoms ('disruptive GERD'). The relative burden of disruptive GERD on health-related quality of life (HRQL) has not been systematically investigated.

AIM

To assess the burden of disruptive vs. nondisruptive GERD on HRQL.

METHODS

Systematic searches were conducted in PubMed and Embase. To be included, studies had to have used validated questionnaires to assess HRQL.

RESULTS

Nineteen studies were included. Data on the comparative burden of frequent (ranging from daily to ≥weekly) and severe reflux symptoms were provided in eight and 13 studies respectively; six reported on the additional burden of nocturnal symptoms. Compared with individuals with nondisruptive GERD, those with disruptive GERD had 2.4-times and 1.5-times higher mean rates of absenteeism and presenteeism respectively (five studies), 1.5-times lower sleep quality scores (three studies), 1.1-times lower mean summary scores for physical and mental health (five studies) and 1.3-times lower mean scores for psychological and general well-being (four studies). Increasing symptom frequency and severity both increased the burden of disease to a similar extent. The presence of nocturnal symptoms in addition to daytime symptoms led to worsening of physical health, but their effect on mental health and work productivity was less clear.

CONCLUSIONS

Disruptive GERD is associated with a high burden of disease compared with occasional or mild reflux symptoms. Disease management needs to vary across the GERD spectrum and should be tailored to patients' requirements for optimal therapeutic outcomes.

Phylogenetic relationships among the polyploid and diploid Aegilops species inferred from the nuclear 5S rDNA sequences (Poaceae: Triticeae)

Phylogenetic inferences of the polyploid Aegilops taxa were drawn based upon the analysis of 909 nuclear 5S rDNA sequences obtained from 15 Aegilops polyploid taxa (531 sequences new to this paper) and 378 sequences from our previous study on the diploid taxa. The 531 sequences can be split into two orthologous groups (unit classes), the long AE1 and short AE1 previously identified in the diploid set. An examination of the relationships between unit classes and their associated haplomes suggests that U haplome sequences found in Ae. umbellulata are the closest to the T sequences found in Amblyopyrum muticum and that sequences of the polyploid species expected to be the M type found in Ae. comos are more similar to the T haplome sequences, except in the three hexaploids Ae. glumiaristata, Ae. juvenalis, and Ae. vavilovii and the tetraploid Ae. crassa where they are found to be similar to the M haplome sequences. These three hexaploid taxa likely originated from the tetraploid Ae. crassa (DM), while the closest taxon to the fourth hexaploid, Ae. recta, is the tetraploid Ae. neglecta (UM). Based upon the distribution of the unit classes, several reticulate phylogenies depicting evolutionary relationships among diploid, tetraploid, and hexaploid taxa were constructed; however, none of these widely used methods could depict the expected reticulate relationship as previously drawn from cytogenetic analyses in this group of allopolyploid species. These results suggest that evolutionary relationships derived from models based upon the assumption of bifurcating species require careful interpretation when these same models are applied to species with reticulate evolution.

Race affects healing of erosive oesophagitis in patients treated with proton pump inhibitors

BACKGROUND

Erosive oesophagitis appears to be more common in white vs. nonwhite patients with gastro-oesophageal reflux disease (GERD).

AIM

To evaluate the association between race and erosive oesophagitis healing in patients with GERD treated with once-daily proton pump inhibitors (PPIs).

METHODS

Data from five double-blind trials of once-daily treatment with esomeprazole 40mg vs. omeprazole 20mg or lansoprazole 30mg for erosive oesophagitis healing (evaluated at weeks 4 and 8 by endoscopy) were pooled and stratified by baseline race and Los Angeles (LA) severity grade. Multiple logistic regression models were fit with erosive oesophagitis healing (dependent variable) and race (independent variable), with adjustments for treatment, study, baseline LA grade, age, gender, BMI, Helicobacter pylori status, hiatal hernia and interactions of these factors with race.

RESULTS

Of 11,027 patients, 91% were white. Nonwhite (n=978) and black (n=613) patients were less likely to have severe baseline erosive oesophagitis (LA grade C or D) than white patients [adjusted OR: 0.69 (95% CI, 0.61-0.79) and 0.67 (0.57-0.78), respectively; P<0.0001]. At week 8, nonwhite and black patients had lower healing rates than white patients [OR: 0.75 (0.63-0.89) and 0.67 (0.54-0.83), respectively; P≤0.001]. Greater odds of healing were associated with less severe baseline LA grade, increasing age, hiatal hernia, esomeprazole treatment (vs. lansoprazole or omeprazole) and lansoprazole treatment (vs. omeprazole) (all P≤0.0009); no factor interacted significantly with race.

CONCLUSIONS

Nonwhite patients with GERD had less severe baseline erosive oesophagitis, but were less likely than white patients to have erosive oesophagitis healing after 8-week PPI therapy.

Randomised clinical trial: a novel rabeprazole extended release 50 mg formulation vs. esomeprazole 40 mg in healing of moderate-to-severe erosive oesophagitis - the results of two double-blind studies

BACKGROUND

Current PPIs may not achieve desired outcomes in some GERD patients due to limited duration of acid inhibition.

AIM

To evaluate a novel rabeprazole extended release (ER), which provides longer duration of drug exposure and acid suppression, in healing and symptomatic resolution of moderate-severe erosive oesophagitis.

METHODS

Patients with LA grade C or D oesophagitis were randomised to rabeprazole-ER 50 mg or esomeprazole 40 mg once daily in two identical 8-week double-blind trials (N = 2130). Two primary endpoints were tested sequentially: (1) healing by 8 weeks [hypothesis: rabeprazole-ER non-inferior to esomeprazole (non-inferiority margin = 8%)], (2) healing by 4 weeks [hypothesis: rabeprazole-ER superior to esomeprazole (P < 0.05)]. The secondary endpoint was sustained heartburn resolution at 4 weeks.

RESULTS

Rabeprazole-ER was non-inferior to esomeprazole in week-8 healing (80.0% vs. 75.0%; 77.5% vs. 78.4%). Week-4 healing (54.8% vs. 50.3%; 50.9% vs. 50.7%) and sustained heartburn resolution (48.3% vs. 48.2%; 53.2% vs. 52.5%) were not significantly different. Post hoc combined results for grade D revealed rabeprazole-ER vs. esomeprazole differences in week-8 healing = 10.4% (95% CI: -1.4%, 22.2%) and week-4 healing = 12.0% (P = 0.048).

CONCLUSIONS

Rabeprazole-ER is as effective as esomeprazole in healing moderate-severe oesophagitis and achieves similar rates of heartburn resolution. Subgroup analysis suggests the possibility of benefit in severe oesophagitis, but this requires further evaluation (ClinicalTrials.gov: NCT00658528 and NCT00658775).

A model of healing of Los Angeles grades C and D reflux oesophagitis: is there an optimal time of acid suppression for maximal healing?

BACKGROUND

In patients with Los Angeles (LA) grade C or D oesophagitis, a positive relationship has been established between the duration of intragastric acid suppression and healing.

AIM

To determine whether there is an apparent optimal time of intragastric acid suppression for maximal healing of reflux oesophagitis.

METHODS

Post hoc analysis of data from a proof-of-concept, double-blind, randomized study of 134 adult patients treated with esomeprazole (10 or 40 mg od for 4 weeks) for LA grade C or D oesophagitis. A curve was fitted to pooled 24-h intragastric pH (day 5) and endoscopically assessed healing (4 weeks) data using piecewise quadratic logistic regression.

RESULTS

Maximal reflux oesophagitis healing rates were achieved when intragastric pH >4 was achieved for approximately 50-70% (12-17 h) of the 24-h period. Acid suppression above this threshold did not yield further increases in healing rates.

CONCLUSION

After 4 weeks' acid-suppressive therapy for LA grade C or D oesophagitis, successful healing appears to reach a threshold above which improvements are unlikely to be achieved despite an increase in number of hours with intragastric pH >4.

Hourglass cell development in the soybean seed coat

BACKGROUND AND AIMS

Hourglass cells (HGCs) are prominent cells in the soybean seed coat, and have potential use as 'phytofactories' to produce specific proteins of interest. Previous studies have shown that HGCs initiate differentiation at about 9 d post-anthesis (dpa), assuming their characteristic morphology by 18 dpa. This study aims to document the structural changes in HGCs during this critical period, and to relate these changes to the concurrent development of a specific soybean peroxidase (SBP) encoded by the Ep gene.

METHODS

Pods were collected from plants at specific growth stages. Fresh material was processed for analysis of Ep peroxidase activity. Tissues were processed for scanning and transmission electron microscopy, as well as extracted for western blotting. A null variety lacking expression of Ep peroxidase was grown as a control.

KEY RESULTS AND CONCLUSIONS

At 9 dpa, HGCs are typical undifferentiated plant cells, but from 12-18 dpa they undergo rapid changes in their internal and external structure. By 18 dpa, they have assumed the characteristic hourglass shape with thick cell walls, intercellular air spaces and large central vacuoles. By 45 dpa, all organelles in HGCs have been degraded. Additional observations indicate that plasmodesmata connect all cell types. SBP activity and SBP protein are detectable in the HGC before they are fully differentiated (approx. 18 dpa). In very early stages, SBP activity appears localized in a vacuole as previously predicted. These results increase our understanding of the structure and development of the HGC and will be valuable for future studies aimed at protein targeting to components of the HGC endomembrane systems.

First Report of Tobacco etch virus Infection in Coleus in the United States

Virus-like disease symptoms consisting of foliar and veinal necrosis similar to those caused by Coleus vein necrosis virus (CVNV) (2) were observed in plants of coleus (Coleus blume Benth.) 'Rustic Orange' obtained from retail greenhouse outlets in Missouri and Minnesota. Flexuous, filamentous, 750 to 770 nm virus-like particles (vlps) were observed by transmission electron microscopy in negatively stained partially purified leaf tissue extracts from symptomatic 'Rustic Orange' leaf tissue. No other virus-like particles were observed and none were detected in extracts from asymptomatic leaves. These vlps were longer than those of CVNV (640 nm) (2) and were not detected by immunosorbent electron microscopy (ISEM) using antibodies to CVNV (2). Degenerate potyvirus primers PNIbF1 (5'GGBAAYAATAGTGGNCAACC3') and PCPR1 (5'GGGGAGGTGCCGTTCTCDATRCACCA3') (1) and total RNA extracted from 'Rustic Orange' leaf tissue with a Qiagen RNeasy Kit were used for reverse transcription-PCR with Ready-To-Go RT-PCR Beads (GE Healthcare). A 950-bp amplicon was obtained from total RNA from diseased but not from healthy leaf tissue. The nucleotide sequence of the amplicon (GenBank Accession No. GQ268818) had levels of identity to published Tobacco etch virus (TEV) sequences comprising portions of the nuclear inclusion body (NIb) and coat protein (CP) gene regions ranging from 89% (L38714) to 93% (M15239, M11458). The identity of the virus occurring in 'Rustic Orange' was further confirmed by ISEM. Virions were trapped and decorated by antibodies to TEV (ATCC PVAS 32). Systemically infected leaf tissue from Datura stramonium in which the coleus TEV isolate was propagated was used to mechanically inoculate Carborundum-dusted leaves of virus-free test plants of 'Rustic Orange' (Park Seed, Greenwood, SC). Inoculated plants developed foliar necrosis symptoms similar to those observed originally, and the presence of TEV was confirmed by ISEM and RT-PCR and nucleotide sequence analysis as described above. To our knowledge, this is the first report of a disease of coleus caused by TEV. Many of approximately 30 'Rustic Orange' plants in one nursery in Minnesota showed similar necrotic foliar symptoms and randomly selected plants tested positive for TEV by ISEM. This suggests that TEV infection in this variety may be spread by vegetative propagation from infected stock plants. References: (1) Y.-C. Hsu et al. J. Virol. Methods 128:54. 2005. (2) D. S. Mollov et al. Plant Dis. 91:754. 2007.

Fast-Growing Rhizobium japonicum That Effectively Nodulates Several Commercial Glycine max L. Merrill Cultivars

Several isolates of fast-growing Rhizobium japonicum that nodulate the wild soybean Glycine soja have been recently described (Keyser et al., Science 215:1631-1632, 1982). We demonstrate that one of these isolates, designated PRC 440 or USDA 191, has a wider host range than that previously reported and is able to nodulate several commercial Glycine max cultivars as effectively as does slow-growing R. japonicum 61A76. Electron microscopic examination revealed no obvious differences between strain 61A76- and strain USDA 191-induced nodules.

Virtual enriched environments in paediatric neuropsychological rehabilitation following traumatic brain injury: Feasibility, benefits and challenges

A frequent consequence of traumatic brain injury (TBI) is a significant reduction in patients' cerebral activation/arousal, which clinicians agree is not conducive to optimal rehabilitation outcomes. In the context of paediatric rehabilitation, sustained periods of inactivity are particularly undesirable, as contemporary research has increasingly called into question the Kennard principle that youth inherently promotes greater neural plasticity and functional recovery following TBI. Therefore, the onus to create rehabilitation conditions most conducive to harnessing plasticity falls squarely on the shoulders of clinicians. Having noted the efficacy of environmental enrichment in promoting neural plasticity and positive functional outcomes in the animal literature, some researchers have suggested that the emerging technology of Virtual Reality (VR) could provide the means to increase patients' cerebral activation levels via the use of enriched Virtual Environments (VEs). However, 10 years on, this intuitively appealing concept has received almost no attention from researchers and clinicians alike. This paper overviews recent research on the benefits of enriched environments in the injured brain and identifies the potential and challenges associated with implementing VR-based enrichment in paediatric neuropsychological rehabilitation.

Loss of 5S rDNA units in the evolution of Agropyron, Pseudoroegneria, and Douglasdeweya

We have investigated relationships among the three closely related genera Agropyron, Pseudoroegneria, and Douglasdeweya. Based upon grouping of 330 5S rDNA sequences into unit classes, we found that Douglasdeweya, with the genomic constitution PPStSt, has 2 unit classes, the long P1 and short S1, and Pseudoroegneria, with the genomic constitution StSt or StStStSt, has the long S1 and short S1 unit classes. In contrast, only the long P1 unit class was found in species of the genus Agropyron (PP). Having a single unit class is unique among all the genera of the tribe Triticeae investigated so far and may reflect gene loss or lineage sorting during its genesis. The presence of the short S1 and long P1 unit classes confirms the amphiploid origin of Douglasdeweya.

Detection, Quantification, and Vegetative Compatibility of Verticillium dahliae in Potato and Mint Production Soils in the Columbia Basin of Oregon and Washington

Soil samples from 87 fields intended for potato production in the Columbia Basin of Washington and Oregon and 51 fields intended for mint production in Washington were assayed on a semiselective medium to quantify populations of Verticillium dahliae. The pathogen was isolated from 77 (89%) of the fields intended for potato production and 41 (80%) of the fields intended for mint production. Population densities ranged from 0 to 169 propagules/g of air-dried soil in fields intended for potato production and 0 to 75 propagules/g of air-dried soil in fields intended for mint production. Isolates of V. dahliae were recovered from soil assay plates and pure cultures were prepared to provide a collection of isolates for vegetative compatibility analysis. Among fields intended for potato production from which isolates of the fungus were assigned to a vegetative compatibility group (VCG), 93% of the fields were found to contain one or more isolates assigned to VCG 4A, nine (23%) contained one or more isolates assigned to VCG4B, and only one (3%) contained any isolates assigned to VCG 2B. In the case of fields planned for mint production in 1999 from which isolates of the fungus were assigned to a VCG, 13 fields (81%) were found to contain one or more isolates assigned to VCG 4A, 7 (44%) contained one or more isolates assigned to VCG 4B, and 5 (31%) contained one or more isolates assigned to VCG 2B. VCG 4A isolates of V. dahliae are widespread and numerous, particularly following potato production, but cause only mild to moderate symptoms in mint; therefore, this pathotype is unlikely to seriously endanger subsequent plantings of mint. However, planting potato in a field recently used to produce mint may pose a significant risk to the potato crop if high populations of the VCG4A pathotype (highly aggressive to potato) predominate. Preplant assessment of soil populations of V. dahliae without regard for the relative populations of various pathotypes present in a particular sample may lead to information not fully useful in integrated pest management systems.

Regulation of synaptic connections in the rabbit ciliary ganglion

One of the intriguing questions about the establishment of synaptic connections is how appropriate numbers of different axons come to innervate each target neuron. A reorganization of connections in early postnatal life appears to be an important aspect of this process, since many of the axons terminals that initially innervate target cells are subsequently lost. The rabbit ciliary ganglion is a remarkably simple neural ensemble in which to examine this rearrangement of developing synaptic connections. Using this system we have found that a reduction in the number of axons innervating each cell occurs without any change in the number of ciliary ganglion cells or preganglionic neurons; therefore the rearrangement is not based on cell death. The number of different axons that ultimately innervate each cell is, however, influenced in some way by the geometry of individual target neurons. Thus, mature ganglion cells that lack dendrites are generally innervated by a single axon, while neurons with increasingly complex dendritic arbors receive innervation from a commensurate number of different axons. At birth, on the other hand, neurons with or without dendritic processes receive about the same number of preganglionic inputs. These results suggest that the geometry of the target cell influences the competitive interaction between different axons innervating the same neuron. Indeed, an important function of dendrites may be to regulate the number of axons that innervate each nerve cell.

Occurrence of Kluyveromyces marxianus var. marxianus Causing Onion Soft Rot in the Columbia Basin of Washington State

Kluyveromyces marxianus var. marxianus, a causal agent of onion (Allium cepa L.) soft rot, was originally isolated from Walla Walla sweet onion bulbs grown in Oregon and subsequently isolated from onion throughout the southeast Washington onion-growing area, but was not found to be infecting dry bulb storage onions grown in central Washington (1). During September of 2001, a yeast was isolated from dry storage onion bulbs (cv. Teton) grown under sprinkler irrigation in central Washington, exhibiting soft rot symptoms and identified to be K. marxianus var. marxianus (2). Koch's postulate was completed using cv. Teton bulbs surface disinfested with 0.5% NaOCl for 2 min. This isolate and four isolates of Kluyveromyces marxianus var. marxianus (1) were cultured on potato dextrose agar and resuspended to an OD₆₀₀ = 0.3 (approximately 10⁵ CFU/ml). One-half of a milliliter of each isolate was inoculated to onion using the cut bulb method with three replicates and incubated in a moist chamber at 25°C for 7 days. Onion slices inoculated with the new isolate exhibited soft rot symptoms similar to those caused by the known isolates while no symptoms were observed for the water control. The yeast reisolated from symptomatic tissue was confirmed to be K. marxianus var. marxianus (2). The identification of K. marxianus var. marxianus infecting dry bulb storage onions grown in the Columbia Basin is of interest because the disease can be confused with bacterial soft rot and could become a serious problem in this important storage onion-growing region. References: (1) D. A. Johnson et al. Plant Dis. 72:359, 1988. (2) N. J. W. Kreger-van Rig, ed. The Yeasts: A Taxonomic Study. Elsevier, Amsterdam, 1984.

Survival of Sporangia of New Clonal Lineages of Phytophthora infestans in Soil Under Semiarid Conditions

Currently, there is no information on the viability of sporangia in soil of the new metalaxyl-resistant genotypes of Phytophthora infestans in the semiarid Columbia Basin of Washington and potato-growing regions throughout the world. Sporangia of metalaxyl-resistant US-8 and US-11 clonal lineages of P. infestans survived a maximum of 23 to 30 days in a Shano silt loam and a Quincy loamy fine sand. There were no significant differences between soil types in area under the spore survival curve (AUSSC) in two trials, however, sporangia of P. infestans in the Quincy sand had a significantly greater mean maximum days of sporangia survival (MDSS) than did the Shano silt loam in one of two trials. AUSSC and MDSS were significantly greater (P < 0.05) for sporangia in wet soil than in dry soil under shaded conditions. Mean AUSSC and MDSS significantly decreased (P < 0.01) under nonshaded conditions versus shaded conditions. Three metalaxyl-resistant isolates (two US-8 and one US-11) of P. infestans did not significantly differ (P < 0.05) in AUSSC and MDSS.

Vegetative Compatibility Groups and Aggressiveness of North American Isolates of Colletotrichum coccodes, the Causal Agent of Potato Black Dot

The vegetative compatibility of 123 isolates of Colletotrichum coccodes from North America (United States and Canada) originating from potato, tomato, pepper, and mint was tested using nitrate-nonutilizing (nit) mutants. The North American isolates did not anastomose with previously selected European/Israeli vegetative compatibility group (VCG) testers; therefore, eight isolates were selected as VCG testers for the North American population. The 123 isolates distributed to seven VCGs at 1.6, 1.6, 4.0, 8.1, 13.8, 19.5, and 36.6%, with 14.6% of the isolates not assigned to any of the seven VCGs. Among the North American (NA)-VCGs, the average frequency of the nit1/nit3 nit mutants was lower (P < 0.05) for isolates belonging to NA-VCG1 than for isolates belonging to the NA-VCGs 2, 3, and 5. In contrast, the frequency of NitM nit mutants did not vary (P > 0.05) among the NA-VCGs and was collectively 5.14%. The results also indicated significant (P < 0.05) differences among NA-VCGs and European/Israeli (EU/I)-VCGs regarding the frequency of nit mutants. The aggressiveness trials of the North American isolates to potato indicated that plants infected with isolates belonging to NA-VCG2 and NA-VCG5 had more (P < 0.05) sclerotia on the roots and crowns than plants infected with isolates belonging to NA-VCGs 1 and 3. The plants infected with isolates belonging to NA-VCG2 had sclerotia formed higher (P < 0.05) up the stem than the plants infected with isolates belonging to NA-VCGs 1, 3, or 5. The plants infected with isolates assigned to NA-VCG2 had more (P < 0.05) infected progeny tubers than the plants infected with isolates belonging to NA-VCGs 1, 3, or 5; and the plants infected with isolates belonging to NA-VCGs 1, 2, and 5 yielded fewer (P < 0.05) potato tubers than the noninoculated control plants. A naming system for the population of C. coccodes based on the continent source of the population, the VCG number, and the isolate's code was suggested.

Colonization of Potato Plants after Aerial Infection by Colletotrichum coccodes, Causal Agent of Potato Black Dot

Colonization of potato plants by Colletotrichum coccodes after artificial inoculation of stems was modeled in relation to the severity of chlorosis and necrosis on foliage using logistic regression. C. coccodes internally colonized the stems up to 24 cm above the inoculation court (mean of 11.3 ± 7.7 cm and 14.1 ± 9.3 cm in 2003 and 2004, respectively), and completely colonized the stem below the inoculation court including the roots (mean of 13.2 ± 3.1 cm and 12 ± 2.3 cm in 2003 and 2004, respectively). C. coccodes grew significantly faster from the inoculation court toward the roots, stolons, and tubers than toward the plant apex. Internal stem colonization was restricted before senescence but rapidly increased as the plants started to senescence, suggesting that physiological events associated with plant senescence activated fungal growth and plant colonization. The results showed no relationship between C. coccodes growth and plant colonization and the development of chlorosis and necrosis severity of leaves. The severity of chlorosis and necrosis on foliage in this study was the outcome of natural plant senescence, and was not caused by the fungal colonization. Therefore, chlorosis and necrosis severity is an inaccurate tool to diagnose infection in potato by C. coccodes and does not indicate the presence or amount of C. coccodes in potato plants. Disease assessment for C. coccodes in potato plants should not rely on severity of chlorosis and necrosis. Black dot assessment should be carried out by isolation and quantification of the fungus from stem and root tissues or by polymerase chain reaction techniques before plant senescence.

Characterization of a novel glycine-rich protein from the cell wall of maize silk tissues

The isolation, characterization and regulation of expression of a maize silk-specific gene is described. zmgrp5 (Zea mays glycine-rich protein 5) encodes a 187 amino acid glycine-rich protein that displays developmentally regulated silk-specific expression. Northern, Western, in situ mRNA hybridization and transient gene expression analyses indicate that zmgrp5 is expressed in silk hair and in cells of the vascular bundle and pollen tube transmitting tissue elements. The protein is secreted into the extracellular matrix and is localized in the cell wall fraction mainly through interactions mediated by covalent disulphide bridges. Taken together, these results suggest that the protein may play a role in maintaining silk structure during development. This is the first documented isolation of a stigma-specific gene from maize, an important agronomic member of the Poaceae family.

Quantification of the retrotransposon BARE-1 reveals the dynamic nature of the barley genome

We used quantitative real-time PCR analysis to measure the copy number of the BARE-1 retrotransposon in 5 cultivars of barley (Hordeum vulgare), as well as in samples from its wild relative, Hordeum spontaneum. Two sets of PCR primers were used to amplify regions within the long terminal repeat (LTR) and the reverse transcriptase (RT) gene of BARE-1 (GenBank accession Z17327). The LTR primers detected an average of 2.148 x 105 +/- 0.012 x 105 copies per haploid genome among barley samples, whereas the RT primers detected an average of 1.588 x 104 +/- 0.085 x 104 copies. The average ratio of LTR:RT was estimated to be 13.5:1. This finding indicates that more than 7% of the barley genome is occupied by BARE-1 elements in the form of solo LTRs and another 2.6% of the genome is occupied by the full-length element. Taken together, BARE-1 sequences represent approximately 9.6% of the barley genome among the barley plants used in this study. For the above estimation, a genome size of 5.44 x 103 Mb for H. vulgare and 5.39 x 103 Mb for H. spontaneum were assumed. Our study on quantification results of the BARE-1 for a small group of barley cultivars showed that there are significant differences among cultivars in terms of BARE-1 copy number, providing further evidence that BARE-1 is active and has a major role in shaping the barley genome as a result of breeding and selection. Quantification results also showed that most of the elements (> 90%) are present as truncated copies (solo LTRs). These results show that there is a high level of recombination leading to the formation of truncated elements and a subsequent DNA loss from the genome. Taken together, our study provides a glimpse into a dynamic micro-evolutionary process that is the by-product of genome reshuffling and directional selection in barley breeding programs.

Effects of Soil-Applied Late Blight Foliar Fungicides on Infection of Potato Tubers by Phytophthora infestans

Potato tuber infection was assessed under greenhouse and outdoor conditions when late blight foliar fungicides were applied to soil 24 h prior to soil infestation with a suspension of zoospores and sporangia of Phytophthora infestans. Spore viability of P. infestans in soil treated with various fungicides was determined using buried healthy whole tubers and by assaying infested soil applied to freshly cut tuber disks. Protection of tubers and tuber disks from infection was more effective when soil was treated with mancozeb, metiram, and cyazofamid than with other fungicides. Whole tuber infections were significantly less in soils treated with mancozeb, metiram, fluazinam, and fenamidone than when treated with distilled water. Infection of buried tubers and tuber disks was prevented for 3 to 5 days following a single soil application of mancozeb or metiram under outdoor conditions. The tuber disk method was more sensitive in determining the efficacy of a fungicide in inhibiting infection and spore viability than using whole buried tubers. However, both methods of determining viability may determine different modes of action of some fungicides that inhibit infection since whole tubers were not infected when protected by some fungicides but tuber disks were infected.

Effect of Seed-Tuber Generation, Soilborne Inoculum, and Azoxystrobin Application on Development of Potato Black Dot Caused by Colletotrichum coccodes

The effect of azoxystrobin on potato black dot and the role of seed- and soilborne inocula of Colletotrichum coccodes in the development of black dot were evaluated in the field using two potato seed generations (generation 1 and 3) of the susceptible cvs. Norkotah Russet and Russet Burbank over 3 years (2002 to 2004). Plants of Norkotah Russet and Russet Burbank treated with azoxystrobin had 13 and 23% higher yields, respectively, than nontreated plants in 2003. Disease severity on both cultivars was reduced 19 to 81%, and 22 to 81% on above- and belowground stem sections, respectively, when plants were treated with azoxystrobin. Plants of both cultivars that were treated with azoxystrobin had 9 to 26% less infected progeny tubers than the nontreated plants. These results indicated the efficacy of azoxystrobin to reduce black dot severity on both stems and progeny tubers. The roles of seed- and soilborne inocula in disease development were evaluated in 2003 and 2004 using generation 1 and 3 seed tubers. The incidence of C. coccodes in generation 1 mother tubers of Norkotah Russet and Russet Burbank were 2 and 16% in 2003, respectively, and 0 and 30% in 2004, respectively. The incidence of C. coccodes in generation 3 mother tubers of Norkotah Russet and Russet Burbank were 14 and 49% in 2003, respectively, and 12 and 38% in 2004, respectively. Generation 1 plants of Norkotah Russet had 36 and 13% greater yield than generation 3 plants in 2003 and 2004, respectively. In 2004, generation 1 plants of Norkotah Russet and Russet Burbank had 26 and 15% greater disease severity, respectively, on belowground stem than generation 3 plants. Generation 1 plants of Norkotah Russet had 7.5 and 11% more infected progeny tubers in 2003 and 2004, respectively, than generation 3. Significant differences for yield reduction and incidence of infected progeny tubers between the two seed generations were not recorded for Russet Burbank, suggesting that the effect of inoculum source of C. coccodes on black dot severity may be cultivar specific.

A comparison of esomeprazole and lansoprazole for control of intragastric pH in patients with symptoms of gastro-oesophageal reflux disease

BACKGROUND

Intragastric acid suppression is the most direct measure of the pharmacodynamic efficacy of proton pump inhibitors, which are the most effective drugs for acid-related diseases.

AIM

To compare the effectiveness of once and twice daily dosing of lansoprazole and esomeprazole in controlling intragastric acidity (target gastric pH > 4.0) over a 24-hour period.

METHODS

In an open-label, two-way crossover study, 45 Helicobacter pylori-negative patients with gastro-oesophageal reflux disease were randomized to receive one of two regimens: 30 mg lansoprazole or esomeprazole 40 mg once daily. Intragastric pH was assessed by 24-hour pH monitoring on day 5 of each regimen. Dosing was increased to twice daily and pH was reassessed on day 10. Following a 14-day washout, patients were crossed over to the other medication and the dosage regimens and pH assessments were repeated.

RESULTS

Data were analysed from 35 patients who completed all scheduled assessments and had 24-hour monitoring for each end-point. Mean time pH > 4.0 and mean 24-hour pH were highest for esomeprazole 40 mg twice daily, followed by lansoprazole 30 mg twice daily, esomeprazole 40 mg once daily and lansoprazole 30 mg once daily. Esomeprazole 40 mg twice daily provided superior control of intragastric pH compared with either once or twice daily dosing of lansoprazole and once daily dosing of esomeprazole (P < 0.01). Esomeprazole 40 mg once daily was comparable with lansoprazole 30 mg twice daily and both were superior to lansoprazole 30 mg once daily (P < 0.01).

CONCLUSIONS

Response to acid suppression treatment depends on the treatment selected. Esomeprazole 40 mg twice daily provided better control of intragastric pH than all other regimens evaluated. Esomeprazole 40 mg daily, however, was comparable with lansoprazole 30 mg twice daily and superior to lansoprazole 30 mg once daily.

Quality in the technical performance of screening flexible sigmoidoscopy: recommendations of an international multi-society task group

BACKGROUND

Flexible sigmoidoscopy (FS) is a complex technical procedure performed in a variety of settings, by examiners with diverse professional backgrounds, training, and experience. Potential variation in technical quality may have a profound impact on the effectiveness of FS on the early detection and prevention of colorectal cancer.

AIM

We propose a set of consensus and evidence based recommendations to assist the development of continuous quality improvement programmes around the delivery of FS for colorectal cancer screening.

RECOMMENDATIONS

These recommendations address the intervals between FS examinations, documentation of results, training of endoscopists, decision making around referral for colonoscopy, policies for antibiotic prophylaxis and management of anticoagulation, insertion of the FS endoscope, bowel preparation, complications, the use of non-physicians as FS endoscopists, and FS endoscope reprocessing. For each of these areas, continuous quality improvement targets are recommended, and research questions are proposed.

Genetic diversity among barley cultivars assessed by sequence-specific amplification polymorphism

We analyzed the genetic structure and relationships among barley cultivars (Hordeum vulgare L.) with sequence-specific amplification polymorphisms (S-SAPs). Polymorphisms were identified in 824 individual barley plants representing 103 cultivars (eight plants per cultivar) widely grown in Canada and the United States, using PCR primers designed from the long terminal repeat of the barley retrotransposon BARE-1 and a subset of four selective MseI primers. From the 404 bands scored, 150 were polymorphic either within or between cultivars. Genetic structure assessed with analysis of molecular variance attributed the largest component of variation to the within groups of cultivars (69-86%). Within-cultivar genetic variation was estimated as average gene diversity over loci and ranged from 0 (completely homogenous) to 0.076 (most heterogeneous cultivar). Only 17 out of 103 cultivars (16%) were judged to be homogenous by this criterion. Relationships among cultivars were analyzed by cluster analysis using unweighted pair-groups using arithmetic averages and found groups similar to those determined by agriculturally significant phenotypic traits such as spike morphology (two-rowed or six-rowed), cultivar type (malting or feed), seed characteristic (hull-less or hulled), and growth habit (winter or spring), with minor overlaps. Discriminant analysis of groups determined by these phenotypic traits fully supported the different groups with minor overlaps between the malting/feed. S-SAP markers generated from retrotransposons such as BARE-1 are invaluable tools for the study of genetic diversity in organisms with a narrow genetic base such as barley. In this study, S-SAP analysis revealed significant amounts of cryptic variation in closely related cultivars including somaclonal variation, which could not be inferred by the pedigree analysis.