An adaptable, reusable, and light implant for chronic Neuropixels probes.

Electrophysiology has proven invaluable to record neural activity, and the development of Neuropixels probes dramatically increased the number of recorded neurons. These probes are often implanted acutely, but acute recordings cannot be performed in freely moving animals and the recorded neurons cannot be tracked across days. To study key behaviors such as navigation, learning, and memory formation, the probes must be implanted chronically. An ideal chronic implant should (1) allow stable recordings of neurons for weeks; (2) be light enough for use in mice; (3) allow reuse of the probes after explantation. Here, we present the "Apollo Implant", an open-source and editable device that meets these criteria and accommodates up to two Neuropixels 1.0 or 2.0 probes. The implant comprises a "payload" module that is attached to the probe and is recoverable, and a "docking" module that is cemented to the skull. The design is adjustable, making it easy to change the distance between probes, the angle of insertion, and the depth of insertion. We tested the implant across seven labs in head-fixed mice, freely moving mice, and freely moving rats. The number of neurons recorded across days was stable, even after repeated implantations of the same probe. The Apollo implant provides an inexpensive, lightweight, and flexible solution for reusable chronic Neuropixels recordings.

The patient's view on rare disease trial design - a qualitative study.

BACKGROUND: Clinical trials in rare diseases are more challenging than trials in frequent diseases. Small numbers of eligible trial participants, often complicated by heterogeneity among rare disease patients, hamper the design and conduct of a 'classical' Randomized Controlled Trial. Therefore, novel designs are developed by statisticians. However, it is important to be aware of possible design aspects that may jeopardize the feasibility of trial conduct. If the burden of participation is considered out of proportion by patients or parents, recruitment may fail or participants may drop out before trial completion. In order to maximize the chance of success of trials in small populations, it is important to know which aspects of trial design are considered important by patients. RESULTS: We have interviewed all ten members of the Patient Think Tank (PTT) of the ASTERIX project, a European research consortium on methodology for clinical trials in small populations. The PTT members are rare disease patient representatives who have completed extensive training in clinical trial methodology. We have analyzed the interviews qualitatively according to Grounded Theory using a thematic analysis, and we structured the topics in four chronologically ordered themes: 1. Involvement in trial design; 2. Opinions on trial design; 3. Trial participation; 4. Phase after the trial. Our main findings are that the PTT-members recommend that patients are involved in trial design from an early stage on, and have influence on the outcomes and measurement instruments that are chosen in the trial, the length of the study, the choice of participants, and the information that is sent to potential participants. Also, according to the PTT-members, patient groups should consider setting up disease registries, placebo groups should be minimized, and more education on clinical trials is advised. CONCLUSIONS: Rare disease patient representatives who have been educated about clinical trial methodology think it is important to involve patient representatives in research at an early stage. They can be of advice in trial design in such a way that the ratio of potential benefit and burden of trial participation as well as the chosen outcome measures and in- and exclusion criteria are optimized.

Psychosis and sexual abuse: An interpretative phenomenological analysis.

OBJECTIVES: This study aimed to investigate the first-person perspective of psychosis sufferers who survived childhood sexual abuse. METHODS: Interpretative phenomenological analysis was employed to explore the experiences of 7 women with a history of sexual abuse and psychosis. RESULTS: Analysis generated six themes: (a) degradation of self, interlinking shame, guilt, and sometimes disgust; (b) body-self entrapment, experiencing bodily constraint and distortion; (c) a sense of being different to others, involving interpersonal problems; (d) unending struggle and depression, a pervasive sense of defeat; (e) psychotic condemnations and abuse, describing psychotic phenomena related to harm and sexual abuse; and (f) perception of links to the past, the links made from past abuse to current functioning. CONCLUSION: Participants suffered extreme psychological, physical, and interpersonal difficulties past and present. Psychotic experiences reported exhibited themes of condemnation by external entities and reflected the topic of sexual abuse. Participants did not generally link psychosis to their past abusive experiences.

Observations of the Interaction and Transport of Fine Mode Aerosols with Cloud and/or Fog in Northeast Asia from Aerosol Robotic Network (AERONET) and Satellite Remote Sensing.

Analysis of sun photometer measured and satellite retrieved aerosol optical depth (AOD) data has shown that major aerosol pollution events with very high fine mode AOD (>1.0 in mid-visible) in the China/Korea/Japan region are often observed to be associated with significant cloud cover. This makes remote sensing of these events difficult even for high temporal resolution sun photometer measurements. Possible physical mechanisms for these events that have high AOD include a combination of aerosol humidification, cloud processing, and meteorological co-variation with atmospheric stability and convergence. The new development of Aerosol Robotic network (AERONET) Version 3 Level 2 AOD with improved cloud screening algorithms now allow for unprecedented ability to monitor these extreme fine mode pollution events. Further, the Spectral Deconvolution Algorithm (SDA) applied to Level 1 data (L1; no cloud screening) provides an even more comprehensive assessment of fine mode AOD than L2 in current and previous data versions. Studying the 2012 winter-summer period, comparisons of AERONET L1 SDA daily average fine mode AOD data showed that Moderate Resolution Imaging Spectroradiometer (MODIS) satellite remote sensing of AOD often did not retrieve and/or identify some of the highest fine mode AOD events in this region. Also, compared to models that include data assimilation of satellite retrieved AOD, the L1 SDA fine mode AOD was significantly higher in magnitude, particularly for the highest AOD events that were often associated with significant cloudiness.

Molecular characterization and distinguishing features of a novel human rhinovirus (HRV) C, HRVC-QCE, detected in children with fever, cough and wheeze during 2003.

BACKGROUND: Human rhinoviruses (HRVs) are associated with more acute respiratory tract infections than any other viral group yet we know little about viral diversity, epidemiology or clinical outcome resulting from infection by strains, in particular the recently identified HRVs. OBJECTIVES: To determine whether HRVC-QCE was a distinct HRV-C strain, by determining its genome and prevalence, by cataloguing genomic features for strain discrimination and by observing clinical features in positive patients. STUDY DESIGN: Novel real-time RT-PCRs and retrospective chart reviews were used to investigate a well-defined population of 1247 specimen extracts to observe the prevalence and the clinical features of each HRV-QCE positive case from an in- and out-patient pediatric, hospital-based population during 2003. An objective illness severity score was determined for each HRVC-QCE positive patient. RESULTS: Differences in overall polyprotein and VP1 binding pocket residues and the predicted presence of a cis-acting replication element in 1B defined HRVC-QCE as a novel HRV-C strain. Twelve additional HRVC-QCE detections (1.0% prevalence) occurred among infants and toddlers (1-24 months) suffering mild to moderate illness, including fever and cough, who were often hospitalized. HRVC-QCE was frequently detected in the absence of another virus and was the only virus detected in three (23% of HRVC-QCE positives) children with asthma exacerbation and in two (15%) toddlers with febrile convulsion. CONCLUSIONS: HRVC-QCE is a newly identified, genetically distinct HRV strain detected in hospitalized children with a range of clinical features. HRV strains should be independently considered to ensure we do not overestimate the HRVs in asymptomatic illness.

The effect of positive mood induction on emotional processing in euthymic individuals with bipolar disorder and controls.

BACKGROUND: Many studies have used negative mood induction techniques to investigate the effect of emotional state on cognitive performance but positive mood induction paradigms have been used less frequently. The objective of this study was to investigate the effect of positive mood induction on emotional processing in euthymic individuals with bipolar disorder (BD) and controls. METHOD: Previously, we reported that positive mood induction using a novel technique based on feedback produced a longer-lasting effect in euthymic individuals with BD than controls (Farmer et al. 2006). Here we report the effect of mood induction on two tests of emotional processing, the Affective Go/No-go test (AGNG) and the Cambridge Gamble task (CGT), on which BD patients in the manic phase differ in their performance from controls. RESULTS: Following positive mood induction, bipolar cases exhibited a positive emotional bias on the AGNG and performed more slowly than controls on the CGT, particularly when making more difficult decisions. CONCLUSIONS: These data confirm that positive mood induction is more effective in individuals with BD than controls. They also suggest that alterations in decision making and attentional biases occur even with transient and subtle changes in mood in bipolar disorder.

Lima Bean Downy Mildew Epiphytotics Caused by New Physiological Races of Phytophthora phaseoli.

Before 1995, race D of Phytophthora phaseoli, the causal agent of downy mildew on lima bean (Phaseolus lunatus), was the prevalent physiological race in the mid-Atlantic region of the United States. Since 1995, however, new physiological races of P. phaseoli have been responsible for downy mildew outbreaks in previously resistant cultivars in this region. Cultivar differential testing of 180 isolates of P. phaseoli collected between 1994 and 2005 from Delaware and the eastern shore of Maryland has confirmed the presence of two new physiological races. The detection of race E in 1995 and race F only 5 years later in 2000, plus the lack of resistant cultivars to manage the epiphytotics in lima bean, have led to millions of dollars of crop losses. Intra- and interspecific genetic variation of Phytophthora spp. and isolates were assessed using amplified fragment length polymorphism DNA fingerprinting. Primer groups EcoRI+AG and MseI+C distinguished P. phaseoli and P. capsici from P. infestans but did not distinguish among different races of P. phaseoli.

Comparison of Colletotrichum orbiculare and Several Allied Colletotrichum spp. for mtDNA RFLPs, Intron RFLP and Sequence Variation, Vegetative Compatibility, and Host Specificity.

ABSTRACT Based on spore morphology, appressorium development, sequence similarities of the rDNA, and similarities in amplified restriction fragment length polymorphism (AFLP), it has been proposed that Colletotrichum orbiculare, C. trifolii, C. lindemuthianum, and C. malvarum represent a single phylogenetic species, C. orbiculare. In the current study, the phylogenetic relationship among isolates in the C. orbiculare species complex was reassessed. In all, 72 isolates of C. orbiculare from cultivated cucurbit or weed hosts, C. trifolii from alfalfa, C. lindemuthianum from green bean, and C. malvarum from prickly sida (Sida spinosa) were examined for mitochondrial DNA (mtDNA) restriction fragment length polymorphisms (RFLPs), RFLPs and sequence variation of a 900-bp intron of the glutamine synthetase gene and a 200-bp intron of the glyceraldehyde-3-phosphate dehydrogenase gene, and vegetative compatibility. In addition, host specificity was examined in foliar inoculations on cucurbit, bean, and alfalfa hosts. Inoculations also were conducted on cucumber fruit. Genetically distinct isolates, based on vegetative compatibility, within the species complex (C. orbiculare, C. trifolii, and C. malvarum) had an identical mtDNA haplotype (haplotype A) when examined with each of three different restriction enzymes. Isolates of C. lindemuthianum had a very similar mtDNA haplotype to haplotype A, with a single polymorphism detected with the enzyme HaeIII. The four species represent a phylogenetically closely related group based on a statistical analysis of the 900- and 200-bp intron sequences. However, distinct RFLPs in the 900-bp intron were consistently associated with each species and could be used to qualitatively and quantitatively distinguish each species. Furthermore, each of the species showed distinct host specificity, with isolates of C. orbiculare (from cucurbits), C. lindemuthianum, and C. trifolii being pathogenic only on cucurbits, green bean, and alfalfa, respectively. Consequently, distinct and fixed nucleotide, or genotypic (intron sequences and RFLPs) and phenotypic (host specificity) characteristics can be used to distinguish C. orbiculare, C. lindemuthianum, and C. trifolii from one another; therefore, they should be recognized as distinct species. This species delineation is consistent with the most current species concepts in fungi. More isolates and further characterization is needed to determine whether C. orbiculare from cocklebur and C. malvarum represent distinct species. RFLPs of the 900-bp intron may represent a relatively inexpensive, reliable, and useful diagnostic tool for general species differentiation in the genus Colletotrichum.

A New Biotype of Phaeosphaeria sp. of Uncertain Affinity Causing Stagonospora Leaf Blotch Disease in Cereals in Poland.

A new Phaeosphaeria sp. biotype was isolated from winter ryes in Poland during 1995. Two isolates, Sn23-1 and Sn48-1, were obtained from diseased leaves of cvs. Motto and Dankowskie, respectively. The rye Phaeosphaeria sp. represented by isolate Sn48-1 has similar pycnidiospore morphology and induces disease symptoms in cereals similar to Phaeosphaeria nodorum, the causal agent of Stagonospora nodorum blotch disease (4). The pathogen (Sn48-1) produces hyaline, cylindrical pycnidiospores that are mostly three-septate and measure 12.8 to 23.7 × 2.1 to 3.2 µm (average size = 16 × 2.6 µm) on water agar. A molecular comparison of several genes in isolates Sn23-1 and Sn48-1 revealed that the rye Phaeosphaeria sp. was different from P. nodorum. In the conserved alpha-box sequence (1,93 bp) of the MAT1-1 gene, a four nucleotide difference occurred between the wheat-biotype P. nodorum and isolates Sn23-1 and Sn48-1 (GenBank Accession Nos. AY072933 and AF322008). In addition, the length of the internal transcribed spacer (ITS) region of the nuclear rDNA was the same for the wheat-biotype P. nodorum and the two rye Phaeosphaeria sp. isolates. However, a six nucleotide discrepancy was found in the ITS region (GenBank Accession Nos. U77362 and AF321323). The beta-glucosidase (bgl1) and beta-tubulin (tubA) genes differ in length between the wheat-biotype P. nodorum and two rye Phaeosphaeria sp. isolates (2,3). The main difference was due to the intron sizes of these two genes. One extra nucleotide was found in the intron2 of the bgl1 gene (GenBank Accession Nos. AY683619 and AY683620) and the intron1 of the tubA gene (GenBank Accession Nos. AY786337 and AY786331), respectively, in these two rye Phaeosphaeria sp. isolates. Disease severity on the fifth leaf (GS15) of Polish wheat (Alba, Begra, and Liwilla), triticale (Bogo and Pinokio), and rye (Zduno) cultivars was assessed with one (resistant) to nine (susceptible) scales 14 days after inoculation. Aggressiveness of wheat-biotype P. nodorum isolate Sn26-1 and rye Phaeosphaeria sp. isolate Sn48-1 was significant (P < 0.01) in five cultivars except in the moderately resistant wheat cv. Liwilla. The rye Phaeosphaeria sp. isolate Sn48-1 severely affected Polish rye Zduno (8.3) and two triticale cultivars (6.5), while the infection by isolate Sn26-1 was moderate (3-4). On the contrary, the wheat-biotype P. nodorum isolate Sn26-1 was more aggressive on wheat (4.1 on moderately resistant Alba and 6.2 on highly susceptible Begra) than the rye Phaeosphaeria sp. isolate Sn48-1, which had a scale of 2.2 and 4.3, respectively. Under laboratory conditions, the rye isolate Sn48-1 was able to cross with the wheat-biotype P. nodorum isolate Sn26-1 that has an opposite mating-type (MAT1-2) gene, but few viable ascospores were produced (1). References: (1) P. C. Czembor and E. Arseniuk. Mycol. Res. 104:919, 2000. (2) A. Malkus et al. FEMS (Fed. Eur. Microbiol. Soc.) Lett. 249:49, 2005. (3) E. Reszka et al. Can. J. Bot. 83:1001, 2005. (4) M. J. Richardson and M. Noble. Plant Pathol. 19:159, 1970.

Genetic Diversity of Sclerotinia homoeocarpa Isolates from Turfgrasses from Various Regions in North America.

Sixty-seven isolates of Sclerotinia homoeocarpa, causing dollar spot disease in creeping bentgrass, annual bluegrass, Bermudagrass, and perennial ryegrass turf, collected from 23 golf courses in various geographical regions of the United States and Canada between 1972 and 2001, were characterized by vegetative compatibility, genetic diversity, and pathogenicity. Eleven vegetative compatibility groups (VCGs A to K) were identified among the isolates tested in this study, and five of them (VCGs G to K) were new. VCG B was the most predominant group, typifying 33 isolates (51%) tested. S. homoeocarpa isolates collected from golf courses in Pennsylvania belonged to seven VCGs (A, B, E, F, G, I, and K), whereas three groups were observed in those collected from New York (B, E, and G) and New Jersey (E, H, and I). Two isolates, one each from Pennsylvania and Canada, were incompatible when paired with the tester isolates in all possible combinations, and did not fall into any known VCG. An isolate collected from Canada was compatible with tester isolates from two VCGs (C and D). Genetic analyses using amplified fragment length polymorphism (AFLP) showed the presence of two genetically distinct groups, designated as major group and the minor group. The major group included 36 isolates collected from various golf courses in the United States and Canada. Two isolates collected from bermudagrass in Florida formed a separate cluster, the minor group. Isolates that belonged to the major group were further divided into two subgroups (1 and 2). Subgroup 1 consisted of all the isolates that belonged to VCGs A, E, G, H, and I. Three of the four isolates that belonged to VCG K also were clustered with isolates of subgroup 1. Subgroup 2 consisted of all the isolates from VCG B, and one each from VCGs F and K. Pathogenicity assays on Penncross creeping bentgrass showed significant differences (P = 0.05) in virulence among the isolates. Overall, a relationship between virulence and VCGs was observed, in which certain virulence groups corresponded to specific VCGs; however, such a relationship was not observed between virulence and AFLPs. Close similarity among isolates of S. homoeocarpa collected from different locations in the United States and Canada suggests that isolates of the same genotype could be involved in outbreaks of dollar spot epidemics at multiple locations.

Stroke outcomes in Northern Scotland: does rurality really matter?

INTRODUCTION: Stroke is the third leading cause of death in Scotland after coronary heart disease and cancer and is a major cause of long-term disability. There is evidence in other clinical conditions such as asthma, diabetic retinopathy, and cancer that rural residents may have poorer outcomes, due to relative inaccessibility of health-service provision or because the disease is at a more advanced stage at diagnosis. However, the evidence-base for stroke care and outcomes in remote and rural areas is small and the subject matter is under-researched. This study was designed to examine, over a one-year period, the incidence and outcome of stroke occurring in the Highlands and Islands of Scotland, a large geographical area with many rural and remote settlements. The study explored whether stroke care and outcome was affected by remoteness and rurality. METHODS: The study was a prospective, community-based, observational survey. Patients in Highland and the Islands (Orkney, Shetland and the Western Isles) suffering first-ever stroke during a 12-month period (from 1 May 2001 to 30 April 2002) were included. All practitioners from health and social care sectors, residential homes, voluntary and charitable organisations were encouraged to notify the researchers of any individual they suspected or knew had a first-ever stroke within the designated time period. Data on 'limitation in activities' (formerly 'level of disability') and service provision were collected using questionnaires and proformas at 1, 3 and 6 months post-stroke from several sources. These included individual patients and carers, health and social care professionals, residential homes, voluntary organisations, and charitable organisations. The analysis focused on location at time of follow up, limitation in activities and service provision. Outcomes were compared across different settlement categories. Settlements were classified as urban/accessible, remote rural and very remote, based on the Scottish Household Survey. RESULTS: In all, 303 patients with a suspected first-ever stroke were notified to the study. The resulting crude incidence of reported stroke was 1.1 per 1000. From the notifications, 239 patients were sent a consent form, of whom 118 agreed to participate in the study. The final dataset, after exclusions for incorrect diagnosis, deaths and other reasons, was derived from 85 patients. Among these, patients from remote rural and very remote settlements were over-represented, when compared to all patients notified. The majority of patients returned home from acute hospitals during the study period and the likelihood of returning home was not related to settlement category. However, a greater proportion of patients in remote rural settlements were admitted to community hospitals and remained there at 6 months. Approximately two-thirds had some degree of disability (or limitation in activities) after their stroke. One-third of patients classed themselves as independent across all time points. Overall, the Barthel Index score increased over time (ie, patients experienced a reduction in disability) with the average score at 1 month post-stroke being 82.5 (range 0-100), at 3 months 85 (range 5-100), and at 6 months 90 (range 5-100). Uptake of services was similar across all settlement categories, with low levels of use at 6-months post-stroke. In particular, few patients used social-support and stroke-specific services, for example Chest, Heart and Stroke Scotland, and Stroke Nurse services. The proportion of patients using any service at 1, 3 and 6 months did not differ between settlement categories. Rural patients did not therefore appear disadvantaged in service provision. CONCLUSIONS: The low incidence of reported stroke may have been due to a number of reasons including: death prior to notification; diagnostic uncertainty; stroke severity--failure to notify very mild or very severe stroke cases; and inadequate reporting of patients managed at home. The greater proportion of patients in remote rural settlements being admitted to community hospitals and remaining there at 6 months may reflect greater availability of community hospital places in this settlement category, but may also be influenced by stroke severity. The low uptake of rehabilitation and support services generally, combined with the relatively poor functional outcome of our patients, suggests that there may be an unmet need for rehabilitation. However, rural patients did not appear specifically disadvantaged. Our study indicates that patients developing a first-time stroke in remote and rural areas of the Highlands and Islands of Scotland are not disadvantaged compared to those in urban/accessible areas, with respect to outcome or to the utilization of health and social care services. However, functional outcomes could be improved for patients in all settlement categories.

Reactivation of Bentgrass Dead Spot and Growth, Pseudothecia Production, and Ascospore Germination of Ophiosphaerella agrostis.

Ophiosphaerella agrostis incites bentgrass dead spot (BDS) of creeping bentgrass. Little is known about the biology of O. agrostis; hence the primary goal of this study was to determine some basic biological properties of the pathogen and epidemiological components of the disease. Winter-dormant creeping bentgrass field samples showing symptoms of BDS were incubated at temperatures ranging from 15 to 30°C. Between 12 and 28 days of incubation, reactivation of BDS symptoms occurred at temperatures ≥20°C, but the greatest expansion in BDS patch diameter occurred at 25 and 30°C. The optimum temperatures for growth of hyphae among 10 O. agrostis isolates ranged from 25 to 30°C, and growth was suppressed at 35°C. Pseudothecia of O. agrostis were produced in vitro on a mixture of tall fescue seed and wheat bran. Pseudothecia developed under constant fluorescent light at 13 to 28°C, but no pseudothecia developed in darkness at any temperature. Pseudothecia developed in as few as 4 days, but the highest numbers appeared about 30 days after incubation began. Ascospores incubated at 25°C germinated in as little as 2 h, with germ tubes generally emerging from the terminal rather than interior cells of ascospores. Germination during the first 4 h of incubation was enhanced by both light and the presence of bentgrass leaves or roots. After 18 h of incubation, however, there were few differences in the percentage of ascospores germinated regardless of light treatment or presence of plant tissue.

Suicide in the Highlands of Scotland.

OBJECTIVE: The Highlands have one of the highest suicide rates in Scotland. This paper describes suicide and deliberate self-harm in the Highlands in the last 20 years and explores possible reasons for the differences from the Scottish average. DESIGN: Retrospective analysis of routine data from the SMRI/SMR01 scheme and information on deaths from the Registrar General. Suicide and undetermined deaths were combined in the analysis. SETTING: Highland and Scotland 1978-98. RESULTS: The high rates in Highland are caused by an excess of male deaths. Highland has had consistently high male suicide rates over the 20 year period compared to Scotland. These differences do not disappear when deaths of non-Highland residents are excluded. By comparison, deliberate self-harm admissions follow a similar pattern to Scotland as a whole. Causes of death differed from Scotland as a whole, with an over-representation of drowning, gases and firearm deaths. CONCLUSION: Highland suicide rates are elevated compared to Scotland. This is mainly due to an excess of deaths in men up to the age of 74 years, and is not accounted for by deaths of non-residents. Female deaths are not elevated in comparison to the rest of Scotland. Male attempted suicide rates do not differ from Scotland. Lethality of method--drowning, car exhausts and firearms--may contribute to the elevated male death rates.

Identification of the temporal components of seizure onset in the scalp EEG.

BACKGROUND: The identification of the earliest indication of rhythmical oscillations and paroxysmal events associated with an epileptic seizure is paramount in identifying the location of the seizure onset in the scalp EEG. In this work, data-dependent filters are designed that can help reveal obscure activity at the onset of seizures in problematic EEGs. METHODS: Data-dependent filters were designed using temporal patterns common to selected segments from pre-ictal and ictal portions of the scalp EEG. Temporal patterns that accounted for more variance in the ictal segment than in the pre-ictal segment of the scalp EEG were used to form the filters. RESULTS: Application of the filters to the scalp EEG revealed temporal components in the seizure onset in the scalp recording that were not obvious in the unfiltered EEG. Examination of the filtered EEG enabled the onset of the seizure to be recognized earlier in the recording. The utility of the filters was confirmed qualitatively by comparing the scalp recording to the intracranial recording and quantitatively by calculating correlation coefficients between the scalp and intracranial recordings before and after filtering. CONCLUSION: The data-dependent approach to EEG filter design allows automatic detection of the basic frequencies present in the seizure onset. This approach is more effective than narrow band-pass filtering for eliminating artifactual and other interference that can obscure the onset of a seizure. Therefore, temporal-pattern filtering facilitates the identification of seizure onsets in challenging scalp EEGs.

Modified angström exponent for the characterization of submicrometer aerosols.

The classical Angström exponent is an operationally robust optical parameter that contains size information on all optically active aerosols in the field of view of a sunphotometer. Assuming that the optical effects of a typical (radius) size distribution can be approximated by separate submicrometer and supermicrometer components, we show that one can exploit the spectral curvature information in the measured optical depth to permit a direct estimation of a fine-mode (submicrometer) Angström exponent (alpha(f)) as well as the optical fraction of fine-mode particles (eta). Simple expressions that enable the estimation of these parameters are presented and tested by use of simulations and measurements.

Assessment of Diversity in Claviceps africana and Other Claviceps Species by RAM and AFLP Analyses.

ABSTRACT Genetic diversity among isolates of Claviceps africana, the sorghum ergot pathogen, and isolates of other Claviceps spp. causing ergot on sorghum or other hosts, was analyzed by random amplified microsatellite (RAM) and amplified fragment length polymorphism (AFLP) analyses. Of the RAM primer sets tested, one revealed polymorphism in C. africana isolates, with Australian and Indian isolates possessing a unique fragment. AFLP analysis, in addition to clearly distinguishing Claviceps spp., revealed polymorphisms in C. africana. A group of isolates from the United States, Puerto Rico, and South Africa exhibited 95 to 100% similarity with one another. Several isolates from Isabela, Puerto Rico were 100% similar to an isolate from Texas, and another isolate from Puerto Rico was identical with one from Nebraska. Australian and Indian isolates showed greater than 90% similarity with isolates from the United States., Puerto Rico, and South Africa. A number of polymorphisms existed in the United States group, indicating that the recently introduced population contains multiple genotypes. Isolates of C. sorghicola, a newly described sorghum pathogen from Japan, were very distinct from other species via RAM and AFLP analyses, as were isolates from outgroups C. purpurea and C. fusiformis. Both RAM and AFLP analysis will be useful in determining future patterns of intercontinental migration of the sorghum ergot pathogen, with the AFLP method showing greater ability to characterize levels of intraspecific variation.

Dendryphion penicillatum and Pleospora papaveracea, Destructive Seedborne Pathogens and Potential Mycoherbicides for Papaver somniferum.

ABSTRACT Dendryphion penicillatum and Pleospora papaveracea were isolated from blighted Papaver somniferum and Papaver bracteatum plants grown in growth chambers and the field in Beltsville, MD. The etiology of the diseases was determined, and the fungi are being investigated as potential mycoherbicides to control the narcotic opium poppy plant. P. papaveracea is known to be a highly destructive seedborne pathogen of Papaver somniferum, causing seedling blight, leaf blight, crown rot, and capsule rot. Single conidia and ascospores were isolated and cultures established from naturally infested seed and diseased foliage and pods of opium poppy from Iran, Colombia, Venezuela, Sweden, India, and the United States (Maryland and Washington). Mycelia and conidia of P. papaveracea and D. penicillatum produced on necrotic leaf tissues appear morphologically similar, and the fungi were previously considered to be anamorph and teleomorph. However, no anamorph/teleomorph connection could be established, and the fungi appear to be distinct taxa. P. papaveracea produced conidia, mature pseudothecia, and chlamydospores in vitro and on infected stems. D. penicillatum produced conidia, microsclerotia, and macronematous conidiophores. Although both fungi were pathogenic to three poppy cultivars, conidial inoculum from P. papaveracea cultures was more virulent than conidial inoculum from D. penicillatum. Eight-week-old plants became necrotic and died 8 days after inoculation with a conidial suspension of P. papaveracea at 2 x 10(5) spores per ml. Disease severity was significantly enhanced by inoculum formulations that contained corn oil, by higher conidial inoculum concentrations, and by increased wetness periods. Symptoms on plants inoculated with either pathogen included leaf and stem necrosis, stem girdling, stunting, necrotic leaf spots, and foliar and pod blight. Inoculated seedlings exhibited wire stem, damping-off, and root rot. Conidia, and less frequently pseudothecia, of P. papaveracea and conidia of D. penicillatum were produced abundantly on inoculated, necrotic foliage, pods, and seedlings. Cultures from conidia or ascospores reisolated from these tissues consistently produced fungi whose morphologies were typical of the fungus from which the inoculum was derived.

Evaluation of Infection Processes and Resulting Disease Caused by Dendryphion penicillatum and Pleospora papaveracea on Papaver somniferum.

ABSTRACT Two pathogenic fungi of opium poppy, Pleospora papaveracea and Dendryphion penicillatum, were isolated from field material in Beltsville, MD. The processes of infection by these two fungi were studied to determine the optimal environmental conditions for infection. Both fungi formed appressoria capable of penetrating directly through the plant epidermal layer. Of the two fungi, P. papaveracea was more aggressive, causing more rapid necrosis. Appressorial formation by P. papaveracea occurred as early as 4 h after application of a conidial suspension to poppy leaves. P. papaveracea formed more appressoria than did D. penicillatum, especially at cool temperatures (7 to 13 degrees C). In greenhouse studies, P. papaveracea caused more damage to opium poppy than did D. penicillatum when applied in 10% unrefined corn oil. In the field, P. papaveracea was more consistent in its effects on opium poppy from a local seed source designated Indian Grocery. P. papaveracea caused higher disease ratings, more stem lesions, and equal or greater yield losses than did D. penicillatum on Indian Grocery. The late-maturing opium poppy variety White Cloud was severely damaged by disease, regardless of formulation or fungal treatment. P. papaveracea was the predominant fungus isolated from poppy seed capsules and the only fungus reisolated from the field the following year. These studies provide a better understanding of the infection process and the differences between these two pathogenic fungi and will be beneficial for the development of the fungi as biological control agents.

Nep1 Protein from Fusarium oxysporum Enhances Biological Control of Opium Poppy by Pleospora papaveracea.

ABSTRACT The fungus Pleospora papaveracea and Nep1, a phytotoxic protein from Fusarium oxysporum, were evaluated for their biocontrol potential on opium poppy (Papaver somniferum). Four treatments consisting of a control, P. papaveracea conidia, Nep1 (5 mug/ml), and P. papaveracea conidia plus Nep1 (5 mug/ml) were used in detached-leaf and whole-plant studies. Conidia of P. papaveracea remained viable for 38 days when stored at 20 or 4 degrees C. Nep1 was stable in the presence of conidia for 38 days when stored at 4 degrees C or for 28 days at 20 degrees C. The presence of Nep1 did not affect conidia germination or appressoria formation. Nep1 was recovered from drops applied to opium poppy leaves in greenhouse and field studies 24 h after treatment. Opium poppy treated with the combination of Nep1 and P. papaveracea had higher necrosis ratings than the other treatments. There were changes in the intercellular protein profiles, determined by sodium dodecyl sulfate gel electrophoresis and silver staining, due to application of treatments; the most intense occurred in response to the combination of Nep1 and P. papaveracea. The combination of Nep1 and P. papaveracea enhanced the damage caused to opium poppy more than either component alone.