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1

Comparative analysis of Panicum streak virus and Maize streak virus diversity, recombination patterns and phylogeography  

PubMed Central

Background Panicum streak virus (PanSV; Family Geminiviridae; Genus Mastrevirus) is a close relative of Maize streak virus (MSV), the most serious viral threat to maize production in Africa. PanSV and MSV have the same leafhopper vector species, largely overlapping natural host ranges and similar geographical distributions across Africa and its associated Indian Ocean Islands. Unlike MSV, however, PanSV has no known economic relevance. Results Here we report on 16 new PanSV full genome sequences sampled throughout Africa and use these together with others in public databases to reveal that PanSV and MSV populations in general share very similar patterns of genetic exchange and geographically structured diversity. A potentially important difference between the species, however, is that the movement of MSV strains throughout Africa is apparently less constrained than that of PanSV strains. Interestingly the MSV-A strain which causes maize streak disease is apparently the most mobile of all the PanSV and MSV strains investigated. Conclusion We therefore hypothesize that the generally increased mobility of MSV relative to other closely related species such as PanSV, may have been an important evolutionary step in the eventual emergence of MSV-A as a serious agricultural pathogen. The GenBank accession numbers for the sequences reported in this paper are GQ415386-GQ415401

2009-01-01

2

Recombination hotspots and host susceptibility modulate the adaptive value of recombination during maize streak virus evolution  

PubMed Central

Background Maize streak virus -strain A (MSV-A; Genus Mastrevirus, Family Geminiviridae), the maize-adapted strain of MSV that causes maize streak disease throughout sub-Saharan Africa, probably arose between 100 and 200 years ago via homologous recombination between two MSV strains adapted to wild grasses. MSV recombination experiments and analyses of natural MSV recombination patterns have revealed that this recombination event entailed the exchange of the movement protein - coat protein gene cassette, bounded by the two genomic regions most prone to recombination in mastrevirus genomes; the first surrounding the virion-strand origin of replication, and the second around the interface between the coat protein gene and the short intergenic region. Therefore, aside from the likely adaptive advantages presented by a modular exchange of this cassette, these specific breakpoints may have been largely predetermined by the underlying mechanisms of mastrevirus recombination. To investigate this hypothesis, we constructed artificial, low-fitness, reciprocal chimaeric MSV genomes using alternating genomic segments from two MSV strains; a grass-adapted MSV-B, and a maize-adapted MSV-A. Between them, each pair of reciprocal chimaeric genomes represented all of the genetic material required to reconstruct - via recombination - the highly maize-adapted MSV-A genotype, MSV-MatA. We then co-infected a selection of differentially MSV-resistant maize genotypes with pairs of reciprocal chimaeras to determine the efficiency with which recombination would give rise to high-fitness progeny genomes resembling MSV-MatA. Results Recombinants resembling MSV-MatA invariably arose in all of our experiments. However, the accuracy and efficiency with which the MSV-MatA genotype was recovered across all replicates of each experiment depended on the MSV susceptibility of the maize genotypes used and the precise positions - in relation to known recombination hotspots - of the breakpoints required to re-create MSV-MatA. Although the MSV-sensitive maize genotype gave rise to the greatest variety of recombinants, the measured fitness of each of these recombinants correlated with their similarity to MSV-MatA. Conclusions The mechanistic predispositions of different MSV genomic regions to recombination can strongly influence the accessibility of high-fitness MSV recombinants. The frequency with which the fittest recombinant MSV genomes arise also correlates directly with the escalating selection pressures imposed by increasingly MSV-resistant maize hosts.

2011-01-01

3

Black leaf streak and viral leaf streak: New banana diseases in East Africa  

Microsoft Academic Search

Black leaf streak, caused by Mycosphaerella fijiensis a virulent pathogen of bananas and plantains, is recorded from Zanzibar. This is the first record of this important pathogen from East Africa. Viral leaf streak of bananas is also identified from Zanzibar. The presence of panama disease and high infestations of root nematode are also noted.

A. J. Dabek; J. M. Waller

1990-01-01

4

TRANSMISSION, ELISA AND SDS-PAGE RESULTS OF SOME MAIZE STREAK VIRUS ISOLATES FROM DIFFERENT PARTS OF NIGERIA  

Microsoft Academic Search

Field surveys were undertaken in 1997-1999 across five ecological zones in Nigeria to collect isolates of Maize streak virus (MSV), genus Mastrevirus. Apart from maize (Zea mays L.), 15 other grass species were found with MSV symptoms in Nigeria. These hosts showed two types of symptoms viz: mild (with or without mottle) or severe (typical symptoms in maize). When Cicadulina

Sunday Oluwafemi; G. Thottappilly; Matthew D. Alegbejo

5

A rep-based hairpin inhibits replication of diverse maize streak virus isolates in a transient assay.  

PubMed

Maize streak disease, caused by the A strain of the African endemic geminivirus, maize streak mastrevirus (MSV-A), threatens the food security and livelihoods of subsistence farmers throughout sub-Saharan Africa. Using a well-established transient expression assay, this study investigated the potential of a spliceable-intron hairpin RNA (hpRNA) approach to interfere with MSV replication. Two strategies were explored: (i) an inverted repeat of a 662 bp region of the MSV replication-associated protein gene (rep), which is essential for virus replication and is therefore a good target for post-transcriptional gene silencing; and (ii) an inverted repeat of the viral long intergenic region (LIR), considered for its potential to trigger transcriptional silencing of the viral promoter region. After co-bombardment of cultured maize cells with each construct and an infectious partial dimer of the cognate virus genome (MSV-Kom), followed by viral replicative-form-specific PCR, it was clear that, whilst the hairpin rep construct (pHPrep?I(662)) completely inhibited MSV replication, the LIR hairpin construct was ineffective in this regard. In addition, pHPrep?I(662) inhibited or reduced replication of six MSV-A genotypes representing the entire breadth of known MSV-A diversity. Further investigation by real-time PCR revealed that the pHPrep?I(662) inverted repeat was 22-fold more effective at reducing virus replication than a construct containing the sense copy, whilst the antisense copy had no effect on replication when compared with the wild type. This is the first indication that an hpRNA strategy targeting MSV rep has the potential to protect transgenic maize against diverse MSV-A genotypes found throughout sub-Saharan Africa. PMID:21653753

Owor, Betty E; Martin, Darren P; Rybicki, Edward P; Thomson, Jennifer A; Bezuidenhout, Marion E; Lakay, Francisco M; Shepherd, Dionne N

2011-10-01

6

Adaptive evolution by recombination is not associated with increased mutation rates in Maize streak virus  

PubMed Central

Background Single-stranded (ss) DNA viruses in the family Geminiviridae are proving to be very useful in real-time evolution studies. The high mutation rate of geminiviruses and other ssDNA viruses is somewhat mysterious in that their DNA genomes are replicated in host nuclei by high fidelity host polymerases. Although strand specific mutation biases observed in virus species from the geminivirus genus Mastrevirus indicate that the high mutation rates in viruses in this genus may be due to mutational processes that operate specifically on ssDNA, it is currently unknown whether viruses from other genera display similar strand specific mutation biases. Also, geminivirus genomes frequently recombine with one another and an alternative cause of their high mutation rates could be that the recombination process is either directly mutagenic or produces a selective environment in which the survival of mutants is favoured. To investigate whether there is an association between recombination and increased basal mutation rates or increased degrees of selection favoring the survival of mutations, we compared the mutation dynamics of the MSV-MatA and MSV-VW field isolates of Maize streak virus (MSV; Mastrevirus), with both a laboratory constructed MSV recombinant, and MSV recombinants closely resembling MSV-MatA. To determine whether strand specific mutation biases are a general characteristic of geminivirus evolution we compared mutation spectra arising during these MSV experiments with those arising during similar experiments involving the geminivirus Tomato yellow leaf curl virus (Begomovirus genus). Results Although both the genomic distribution of mutations and the occurrence of various convergent mutations at specific genomic sites indicated that either mutation hotspots or selection for adaptive mutations might elevate observed mutation rates in MSV, we found no association between recombination and mutation rates. Importantly, when comparing the mutation spectra of MSV and TYLCV we observed similar strand specific mutation biases arising predominantly from imbalances in the complementary mutations G???T: C???A. Conclusions While our results suggest that recombination does not strongly influence mutation rates in MSV, they indicate that high geminivirus mutation rates are at least partially attributable to increased susceptibility of all geminivirus genomes to oxidative damage while in a single stranded state.

2012-01-01

7

Replication modes of Maize streak virus mutants lacking RepA or the RepA-pRBR interaction motif.  

PubMed

The plant-infecting mastreviruses (family Geminiviridae) express two distinct replication-initiator proteins, Rep and RepA. Although RepA is essential for systemic infectivity, little is known about its precise function. We therefore investigated its role in replication using 2D-gel electrophoresis to discriminate the replicative forms of Maize streak virus (MSV) mutants that either fail to express RepA (RepA(-)), or express RepA that is unable to bind the plant retinoblastoma related protein, pRBR. Whereas amounts of viral DNA were reduced in two pRBR-binding deficient RepA mutants, their repertoires of replicative forms changed only slightly. While a complete lack of RepA expression was also associated with reduced viral DNA titres, the only traces of replicative intermediates of RepA(-) viruses were those indicative of recombination-dependent replication. We conclude that in MSV, RepA, but not RepA-pRBR binding, is necessary for single-stranded DNA production and efficient rolling circle replication. PMID:23679984

Ruschhaupt, Moritz; Martin, Darren P; Lakay, Francisco; Bezuidenhout, Marion; Rybicki, Edward P; Jeske, Holger; Shepherd, Dionne N

2013-08-01

8

Transcriptome of the Plant Virus Vector Graminella nigrifrons, and the Molecular Interactions of Maize fine streak rhabdovirus Transmission  

PubMed Central

Background Leafhoppers (Hemiptera: Cicadellidae) are plant-phloem feeders that are known for their ability to vector plant pathogens. The black-faced leafhopper (Graminella nigrifrons) has been identified as the only known vector for the Maize fine streak virus (MFSV), an emerging plant pathogen in the Rhabdoviridae. Within G. nigrifrons populations, individuals can be experimentally separated into three classes based on their capacity for viral transmission: transmitters, acquirers and non-acquirers. Understanding the molecular interactions between vector and virus can reveal important insights in virus immune defense and vector transmission. Results RNA sequencing (RNA-Seq) was performed to characterize the transcriptome of G. nigrifrons. A total of 38,240 ESTs of a minimum 100 bp were generated from two separate cDNA libraries consisting of virus transmitters and acquirers. More than 60% of known D. melanogaster, A. gambiae, T. castaneum immune response genes mapped to our G. nigrifrons EST database. Real time quantitative PCR (RT-qPCR) showed significant down-regulation of three genes for peptidoglycan recognition proteins (PGRP – SB1, SD, and LC) in G. nigrifrons transmitters versus control leafhoppers. Conclusions Our study is the first to characterize the transcriptome of a leafhopper vector species. Significant sequence similarity in immune defense genes existed between G. nigrifrons and other well characterized insects. The down-regulation of PGRPs in MFSV transmitters suggested a possible role in rhabdovirus transmission. The results provide a framework for future studies aimed at elucidating the molecular mechanisms of plant virus vector competence.

Chen, Yuting; Cassone, Bryan J.; Bai, Xiaodong; Redinbaugh, Margaret G.; Michel, Andrew P.

2012-01-01

9

The C-terminus of Wheat streak mosaic virus coat protein is involved in differential infection of wheat and maize through host-specific long-distance transport.  

PubMed

Viral determinants and mechanisms involved in extension of host range of monocot-infecting viruses are poorly understood. Viral coat proteins (CP) serve many functions in almost every aspect of the virus life cycle. The role of the C-terminal region of Wheat streak mosaic virus (WSMV) CP in virus biology was examined by mutating six negatively charged aspartic acid residues at positions 216, 289, 290, 326, 333, and 334. All of these amino acid residues are dispensable for virion assembly, and aspartic acid residues at positions 216, 333, and 334 are expendable for normal infection of wheat and maize. However, mutants D289N, D289A, D290A, DD289/290NA, and D326A exhibited slow cell-to-cell movement in wheat, which resulted in delayed onset of systemic infection, followed by a rapid recovery of genomic RNA accumulation and symptom development. Mutants D289N, D289A, and D326A inefficiently infected maize, eliciting milder symptoms, while D290A and DD289/290NA failed to infect systemically, suggesting that the C-terminus of CP is involved in differential infection of wheat and maize. Mutation of aspartic acid residues at amino acid positions 289, 290, and 326 severely debilitated virus ingress into the vascular system of maize but not wheat, suggesting that these amino acids facilitate expansion of WSMV host range through host-specific long-distance transport. PMID:24111920

Tatineni, Satyanarayana; French, Roy

2014-02-01

10

RNAi-derived field resistance to Cassava brown streak disease persists across the vegetative cropping cycle.  

PubMed

A confined field trial was established to determine durability of RNAi-mediated resistance to Cassava brown streak disease (CBSD). Stem cuttings were obtained from field-grown cassava plants of cv 60444 transgenic for construct p718, consisting of an 894 bp inverted repeat sequence from the Ugandan Cassava brown streak virus (UCBSV) coat protein. Plants were established from three transgenic lines previously shown to provide complete resistance to UCBSV and differing levels of protection to the non-homologous virus species Cassava brown streak virus (CBSV), and grown for 11 months. CBSD symptoms were observed on shoots and storage roots of all non-transgenic cv 60444 control plants and transgenic lines p718-002 and p718-005, but not on p718-001. RT-PCR diagnostic showed tissues of plant lines p718-002 and p718-005 to be infected with CBSV, but free of UCBSV. All leaves and roots of p718-001 plants were to carry no detectable levels of either pathogen. Plants of cv 60444 in this field trial showed severe cassava mosaic disease symptoms, indicating that presence of replicating geminiviruses did not cause significant suppression of RNAi-mediated resistance to CBSD. Resistance to CBSD across a vegetative cropping cycle confirms earlier field data, and provides an important step in proof of concept for application of RNAi technology to control of CBSD under conditions encountered in farmers' fields. PMID:24296511

Odipio, John; Ogwok, Emmanuel; Taylor, Nigel J; Halsey, Mark; Bua, Anton; Fauquet, Claude M; Alicai, Titus

2014-01-01

11

Transgenic RNA interference (RNAi)-derived field resistance to cassava brown streak disease.  

PubMed

Cassava brown streak disease (CBSD), caused by the Ipomoviruses Cassava brown streak virus (CBSV) and Ugandan Cassava brown streak virus (UCBSV), is considered to be an imminent threat to food security in tropical Africa. Cassava plants were transgenically modified to generate small interfering RNAs (siRNAs) from truncated full-length (894-bp) and N-terminal (402-bp) portions of the UCBSV coat protein (?CP) sequence. Seven siRNA-producing lines from each gene construct were tested under confined field trials at Namulonge, Uganda. All nontransgenic control plants (n = 60) developed CBSD symptoms on aerial tissues by 6 months after planting, whereas plants transgenic for the full-length ?CP sequence showed a 3-month delay in disease development, with 98% of clonal replicates within line 718-001 remaining symptom free over the 11-month trial. Reverse transcriptase-polymerase chain reaction (RT-PCR) diagnostics indicated the presence of UCBSV within the leaves of 57% of the nontransgenic controls, but in only two of 413 plants tested (0.5%) across the 14 transgenic lines. All transgenic plants showing CBSD were PCR positive for the presence of CBSV, except for line 781-001, in which 93% of plants were confirmed to be free of both pathogens. At harvest, 90% of storage roots from nontransgenic plants were severely affected by CBSD-induced necrosis. However, transgenic lines 718-005 and 718-001 showed significant suppression of disease, with 95% of roots from the latter line remaining free from necrosis and RT-PCR negative for the presence of both viral pathogens. Cross-protection against CBSV by siRNAs generated from the full-length UCBSV ?CP confirms a previous report in tobacco. The information presented provides proof of principle for the control of CBSD by RNA interference-mediated technology, and progress towards the potential control of this damaging disease. PMID:22845735

Ogwok, Emmanuel; Odipio, John; Halsey, Mark; Gaitán-Solís, Eliana; Bua, Anton; Taylor, Nigel J; Fauquet, Claude M; Alicai, Titus

2012-12-01

12

Role of Dehydrodiferulates in Maize Resistance to Pests and Diseases  

PubMed Central

Phenolic esters have attracted considerable interest due to the potential they offer for peroxidase catalysed cross-linking of cell wall polysaccharides. Particularly, feruloyl residues undergo radical coupling reactions that result in cross-linking (intra-/intermolecular) between polysaccharides, between polysaccharides and lignin and, between polysaccharides and proteins. This review addresses for the first time different studies in which it is established that cross-linking by dehydrodiferulates contributes to maize’s defences to pests and diseases. Dehydrodiferulate cross-links are involved in maize defence mechanisms against insects such as the European, Mediterranean, and tropical corn borers and, storage pest as the maize weevil. In addition, cross-links are also discussed to be involved in genetic resistance of maize to fungus diseases as Gibberella ear and stalk rot. Resistance against insects and fungus attending dehydrodiferulates could go hand in hand. Quantitative trait loci mapping for these cell wall components could be a useful tool for enhancing resistance to pest and diseases in future breeding programs.

Santiago, Rogelio; Malvar, Rosa A.

2010-01-01

13

Transcriptional Response of Virus-Infected Cassava and Identification of Putative Sources of Resistance for Cassava Brown Streak Disease  

PubMed Central

Cassava (Manihot esculenta) is a major food staple in sub-Saharan Africa, which is severely affected by cassava brown streak disease (CBSD). The aim of this study was to identify resistance for CBSD as well as to understand the mechanism of putative resistance for providing effective control for the disease. Three cassava varieties; Kaleso, Kiroba and Albert were inoculated with cassava brown streak viruses by grafting and also using the natural insect vector the whitefly, Bemisia tabaci. Kaleso expressed mild or no disease symptoms and supported low concentrations of viruses, which is a characteristic of resistant plants. In comparison, Kiroba expressed severe leaf but milder root symptoms, while Albert was susceptible with severe symptoms both on leaves and roots. Real-time PCR was used to estimate virus concentrations in cassava varieties. Virus quantities were higher in Kiroba and Albert compared to Kaleso. The Illumina RNA-sequencing was used to further understand the genetic basis of resistance. More than 700 genes were uniquely overexpressed in Kaleso in response to virus infection compared to Albert. Surprisingly, none of them were similar to known resistant gene orthologs. Some of the overexpressed genes, however, belonged to the hormone signalling pathways and secondary metabolites, both of which are linked to plant resistance. These genes should be further characterised before confirming their role in resistance to CBSD.

Maruthi, M. N.; Bouvaine, Sophie; Tufan, Hale A.; Mohammed, Ibrahim U.; Hillocks, Rory J.

2014-01-01

14

Identification and fine-mapping of a QTL, qMrdd1, that confers recessive resistance to maize rough dwarf disease  

PubMed Central

Background Maize rough dwarf disease (MRDD) is a devastating viral disease that results in considerable yield losses worldwide. Three major strains of virus cause MRDD, including maize rough dwarf virus in Europe, Mal de Río Cuarto virus in South America, and rice black-streaked dwarf virus in East Asia. These viral pathogens belong to the genus fijivirus in the family Reoviridae. Resistance against MRDD is a complex trait that involves a number of quantitative trait loci (QTL). The primary approach used to minimize yield losses from these viruses is to breed and deploy resistant maize hybrids. Results Of the 50 heterogeneous inbred families (HIFs), 24 showed consistent responses to MRDD across different years and locations, in which 9 were resistant and 15 were susceptible. We performed trait-marker association analysis on the 24 HIFs and found six chromosomal regions which were putatively associated with MRDD resistance. We then conducted QTL analysis and detected a major resistance QTL, qMrdd1, on chromosome 8. By applying recombinant-derived progeny testing to self-pollinated backcrossed families, we fine-mapped the qMrdd1 locus into a 1.2-Mb region flanked by markers M103-4 and M105-3. The qMrdd1 locus acted in a recessive manner to reduce the disease-severity index (DSI) by 24.2–39.3%. The genetic effect of qMrdd1 was validated using another F6 recombinant inbred line (RIL) population in which MRDD resistance was segregating and two genotypes at the qMrdd1 locus differed significantly in DSI values. Conclusions The qMrdd1 locus is a major resistance QTL, acting in a recessive manner to increase maize resistance to MRDD. We mapped qMrdd1 to a 1.2-Mb region, which will enable the introgression of qMrdd1-based resistance into elite maize hybrids and reduce MRDD-related crop losses.

2013-01-01

15

Genome-wide gene responses in a transgenic rice line carrying the maize resistance gene Rxo1 to the rice bacterial streak pathogen, Xanthomonas oryzae pv. oryzicola  

Microsoft Academic Search

BACKGROUND: Non-host resistance in rice to its bacterial pathogen, Xanthomonas oryzae pv. oryzicola (Xoc), mediated by a maize NBS-LRR type R gene, Rxo1 shows a typical hypersensitive reaction (HR) phenotype, but the molecular mechanism(s) underlying this type of non-host resistance remain largely unknown. RESULTS: A microarray experiment was performed to reveal the molecular mechanisms underlying HR of rice to Xoc

Yong-Li Zhou; Mei-Rong Xu; Ming-Fu Zhao; Xue-Wen Xie; Ling-Hua Zhu; Bin-Ying Fu; Zhi-Kang Li

2010-01-01

16

Variable number of tandem repeat markers in the genome sequence of Mycosphaerella fijiensis, the causal agent of black leaf streak disease of banana (Musa spp).  

PubMed

We searched the genome of Mycosphaerella fijiensis for molecular markers that would allow population genetics analysis of this plant pathogen. M. fijiensis, the causal agent of banana leaf streak disease, also known as black Sigatoka, is the most devastating pathogen attacking bananas (Musa spp). Recently, the entire genome sequence of M. fijiensis became available. We screened this database for VNTR markers. Forty-two primer pairs were selected for validation, based on repeat type and length and the number of repeat units. Five VNTR markers showing multiple alleles were validated with a reference set of isolates from different parts of the world and a population from a banana plantation in Costa Rica. Polymorphism information content values varied from 0.6414 to 0.7544 for the reference set and from 0.0400 and 0.7373 for the population set. Eighty percent of the polymorphism information content values were above 0.60, indicating that the markers are highly informative. These markers allowed robust scoring of agarose gels and proved to be useful for variability and population genetics studies. In conclusion, the strategy we developed to identify and validate VNTR markers is an efficient means to incorporate markers that can be used for fungicide resistance management and to develop breeding strategies to control banana black leaf streak disease. This is the first report of VNTR-minisatellites from the M. fijiensis genome sequence. PMID:21064028

Garcia, S A L; Van der Lee, T A J; Ferreira, C F; Te Lintel Hekkert, B; Zapater, M-F; Goodwin, S B; Guzmán, M; Kema, G H J; Souza, M T

2010-01-01

17

Maize prolamins could induce a gluten-like cellular immune response in some celiac disease patients.  

PubMed

Celiac disease (CD) is an autoimmune-mediated enteropathy triggered by dietary gluten in genetically prone individuals. The current treatment for CD is a strict lifelong gluten-free diet. However, in some CD patients following a strict gluten-free diet, the symptoms do not remit. These cases may be refractory CD or due to gluten contamination; however, the lack of response could be related to other dietary ingredients, such as maize, which is one of the most common alternatives to wheat used in the gluten-free diet. In some CD patients, as a rare event, peptides from maize prolamins could induce a celiac-like immune response by similar or alternative pathogenic mechanisms to those used by wheat gluten peptides. This is supported by several shared features between wheat and maize prolamins and by some experimental results. Given that gluten peptides induce an immune response of the intestinal mucosa both in vivo and in vitro, peptides from maize prolamins could also be tested to determine whether they also induce a cellular immune response. Hypothetically, maize prolamins could be harmful for a very limited subgroup of CD patients, especially those that are non-responsive, and if it is confirmed, they should follow, in addition to a gluten-free, a maize-free diet. PMID:24152750

Ortiz-Sánchez, Juan P; Cabrera-Chávez, Francisco; de la Barca, Ana M Calderón

2013-10-01

18

Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a GST gene  

PubMed Central

Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) are expected to be under positive selection pressure. To address the hypothesis that naturally occurring allelic variation conditions MDR, we extended the framework of structured association mapping to allow for the analysis of correlated complex traits and the identification of pleiotropic genes. The multivariate analytical approach used here is directly applicable to any species and set of traits exhibiting correlation. From our analysis of a diverse panel of maize inbred lines, we discovered high positive genetic correlations between resistances to three globally threatening fungal diseases. The maize panel studied exhibits rapidly decaying linkage disequilibrium that generally occurs within 1 or 2 kb, which is less than the average length of a maize gene. The positive correlations therefore suggested that functional allelic variation at specific genes for MDR exists in maize. Using a multivariate test statistic, a glutathione S-transferase (GST) gene was found to be associated with modest levels of resistance to all three diseases. Resequencing analysis pinpointed the association to a histidine (basic amino acid) for aspartic acid (acidic amino acid) substitution in the encoded protein domain that defines GST substrate specificity and biochemical activity. The known functions of GSTs suggested that variability in detoxification pathways underlie natural variation in maize MDR.

Wisser, Randall J.; Kolkman, Judith M.; Patzoldt, Megan E.; Holland, James B.; Yu, Jianming; Krakowsky, Matthew; Nelson, Rebecca J.; Balint-Kurti, Peter J.

2011-01-01

19

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (uv to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 keV x-rays.

Wang, C.L.

1984-09-28

20

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1000 KeV x-rays.

Wang, Ching L. (Livermore, CA)

1989-01-01

21

Microchannel plate streak camera  

DOEpatents

An improved streak camera in which a microchannel plate electron multiplier is used in place of or in combination with the photocathode used in prior streak cameras is disclosed. The improved streak camera is far more sensitive to photons (UV to gamma-rays) than the conventional x-ray streak camera which uses a photocathode. The improved streak camera offers gamma-ray detection with high temporal resolution. It also offers low-energy x-ray detection without attenuation inside the cathode. Using the microchannel plate in the improved camera has resulted in a time resolution of about 150 ps, and has provided a sensitivity sufficient for 1,000 KeV x-rays. 3 figs.

Wang, C.L.

1989-03-21

22

Distribution and genetic diversity of Southern rice black-streaked dwarf virus in China  

PubMed Central

Background Rice and maize dwarf diseases caused by the newly introduced Southern rice black-streaked dwarf virus (SRBSDV) have led to severe economic losses in South China in recent years. The distribution and diversity of SRBSDV have not been investigated in the main rice and maize growing areas in China. In this study, the distribution of SRBSDV in China was determined by using reverse transcription-polymerase chain reaction (RT-PCR). Results Between 2009 and 2010, 2404 plant samples (2294 rice, 110 maize samples, and more than 300 cultivars) with dwarf symptoms were collected from fields in 194 counties of 17 provinces in China and SRBSDV was detected. The results indicated that 1545 (64.27%) of samples (both rice and maize) were infected with SRBSDV. SRBSDV was detected widely in Hainan, Guangdong, Guangxi, Yunnan, Guizhou, Chongqing, Fujian, Jiangxi, Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, which suggests SRBSDV is an important pathogen causing rice dwarfing diseases in South China. Phylogenetic analysis of 15 representative virus isolates revealed that SRBSDV isolates in China had high levels of nucleotide and amino acid sequence identities (>97.8%). Conclusions SRBSDV spreads naturally in Yangtze River basin and south region, the location of the major rice production areas. In comparison, the virus rarely spreads north of Yangtze River in North China. Distribution of SRBSDV is consistent with the migrating and existing ranges of its vector WBPH, suggesting that SRBSDV might be introduced into South China along with the migration of viruliferous WBPH.

2013-01-01

23

Expression of the Newcastle disease virus fusion protein in transgenic maize and immunological studies.  

PubMed

Transgenic plants have been employed successfully as a low-cost system for the production of therapeutically valuable proteins, including antibodies, antigens and hormones. Here, we report the expression of the fusion (F) gene of the Newcastle disease virus (NDV) in transgenic maize plants. The expression of the transgene, driven by the maize ubiquitin promoter, caused accumulation of the F protein in maize kernels. The presence of the transgene was verified by Southern and western blots. Feeding chickens with kernels containing the F protein induced the production of antibodies, which conferred protection against a viral challenge. This protection was comparable to that conferred by a commercial vaccine. Possible uses of this plant-based F protein as a potential mucosal vaccine are discussed. PMID:16906446

Guerrero-Andrade, Octavio; Loza-Rubio, Elizabeth; Olivera-Flores, Teresa; Fehérvári-Bone, Tamás; Gómez-Lim, Miguel Angel

2006-08-01

24

Wind Streak Changes  

NASA Technical Reports Server (NTRS)

2 September 2004 This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows changes in dark wind streak patterns that occurred between 5 April 1999 (image M00-00534) and 17 August 2004 (image R20-00901). Unlike the spaghetti-like streak patterns made by dust devils, these streaks all begin on their upwind ends as tapered forms that fan outward in the downwind direction, and they all indicate winds that blew from the same direction. In both cases, winds blew from the southeast (lower right) toward the northwest (upper left). These streaks and the small pedestal craters found among them occur in the Memnonia region of Mars near 5.9oS, 162.2oW. The 400 meter scale bar is about 437 yards long. Sunlight illuminates each scene from the upper left.

2004-01-01

25

Visible Embryo: Primitive Streak  

NSDL National Science Digital Library

the page on early placentation and primitive streak formation from a comprehensive resource of information on human development from conception to birth, designed for both medical student and interested lay people.

Carmen Arbona (Mouseworks)

2006-09-08

26

Mycotoxicological investigations on maize and groundnuts from the endemic area of Mseleni joint disease in Kwazulu.  

PubMed

Samples of home-grown maize and groundnuts from the endemic area of Mseleni joint disease (MJD) during four seasons (1980-1983) were examined mycologically. The mycoflora of these dietary staples included Fusarium poae and F. oxysporum, which have been implicated in the aetiology of Kashin-Beck or Urov disease, another osteo-arthrosis endemic in Siberia and China. Two other species of Fusarium, i.e. F. moniliforme and F. equiseti, implicated in syndromes of abnormal bone development in animals, were also present. The predominant fungus associated with maize kernels was F. moniliforme; two other fungi relatively frequently isolated from Mseleni maize, i.e. F. compactum and Lasiodiplodia theobromae, have not previously been reported in maize in southern Africa. The predominant fungi associated with groundnut kernels were Penicillium spp., L. theobromae, Macrophomina phaseolina and F. oxysporum. The incidence of certain fungi, particularly F. compactum, F. oxysporum and L. theobromae, appeared to be higher in dietary staples from households affected by MJD than from non-affected ones. The numbers of samples examined were, however, small and these findings need to be confirmed. Cultures of 120/322 isolates of fungi from Mseleni dietary staples proved toxic to ducklings, the most toxic species being F. compactum, F. moniliforme, F. oxysporum and Phomopsis sp. The characteristic pathological changes of MJD have, however, not been induced in experimental animals with cultures of any of these fungi. A diet containing maize and groundnuts from households affected by MJD also failed to induce the characteristic osteo-arthritic changes of MJD in rats. The dietary staples used in this experiment were, however, collected during seasons of abnormally low rainfall at Mseleni.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3961620

Marasas, W F; Van Rensburg, S J

1986-03-15

27

Frosty Wind Streaks  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-532, 2 November 2003

As seasonal polar frosts sublime away each spring, winds may re-distribute some of the frost or move sediment exposed from beneath the frost. This action creates ephemeral wind streaks that can be used by scientists seeking to study the local circulation of the martian [missing text] surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of wind streaks created in subliming carbon dioxide frost. These dark streaks appear to conform to the shape of the slopes on which they occur, suggesting that slope winds play a dominant role in creating and orienting these streaks. This picture is located near 73.8oS, 305.7oW. The image is illuminated by sunlight from the upper left and covers an area 3 km (1.9 mi) wide. Winds responsible for the streaks generally blew from the bottom/right (south/southeast) toward the top/upper left (north/northwest).

2003-01-01

28

Craters and Wind Streaks  

NASA Technical Reports Server (NTRS)

25 March 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of small wind tails or streaks in the lees of impact craters in northeastern Tharsis near 25.8oN, 89.0oW. The streak tails point toward the east/northeast (right), indicating that the dominant winds blow from the west/southwest (left). This February 2004 picture covers an area about 3 km (1.9 mi) across. Sunlight illuminates the scene from the lower left.

2004-01-01

29

Layers and Streaks  

NASA Technical Reports Server (NTRS)

6 December 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an outcrop of light-toned layered rock and a plethora of dark streaks on the floor of a crater in southern Noachis Terra. The streaks were created by dozens of dust devils which disrupted and perhaps removed some of the thin layer of dust that coats the surface. This view is located near 55.5oS, 333.4oW. The scene is illuminated by sunlight from the lower right. The 500 meter scale bar is approximately 547 yards long.

2004-01-01

30

Streak camera receiver definition study  

NASA Technical Reports Server (NTRS)

Detailed streak camera definition studies were made as a first step toward full flight qualification of a dual channel picosecond resolution streak camera receiver for the Geoscience Laser Altimeter and Ranging System (GLRS). The streak camera receiver requirements are discussed as they pertain specifically to the GLRS system, and estimates of the characteristics of the streak camera are given, based upon existing and near-term technological capabilities. Important problem areas are highlighted, and possible corresponding solutions are discussed.

Johnson, C. B.; Hunkler, L. T., Sr.; Letzring, S. A.; Jaanimagi, P.

1990-01-01

31

Jet Streak Circulations  

NSDL National Science Digital Library

This Webcast is based on a presentation given by Dr. James T. Moore of Saint Louis University at the 5th Annual MSC/COMET Winter Weather Workshop on 30 November 2004 in Boulder, Colorado. Dr. Moore reviews many aspects of jet streak dynamics including convergence/divergence, ageostrophic winds, propagation, and coupled jets.

Spangler, Tim

2005-04-25

32

Interaction of Fusarium graminearum and F. moniliforme in Maize Ears: Disease Progress, Fungal Biomass, and Mycotoxin Accumulation  

Microsoft Academic Search

Reid, L. M., Nicol, R. W., Ouellet, T., Savard, M., Miller, J. D., Y oung, J. C., Stewart, D. W., and Schaafsma, A. W. 1999. Interaction of Fusarium graminearum and F. moniliforme in maize ears: Disease progress, fungal biomass, and mycotoxin accumulation. Phytopathology 89:1028-1037. To investigate the interaction between two major ear-rotting pathogens, maize ears were inoculated with either Fusarium

L. M. Reid; R. W. Nicol; T. Ouellet; M. Savard; J. D. Miller; J. C. Young; D. W. Stewart; A. W. Schaafsma

1999-01-01

33

An Ion Streak Camera  

Microsoft Academic Search

The possibility of detecting fast ions (protons and a particles) using an X-ray-sensitive streak camera with a CsI photocathode is demonstrated. The spatial resolution of the instrument is 70 µm, and its physical time resolution is 7 ps. The yield of secondary electrons from the photocathode irradiated with a particles is 8 electrons\\/particle. The instrument is able to detect single

A. G. Kravchenko; D. N. Litvin; V. P. Lazarchuk; V. M. Murugov; S. I. Petrov; A. V. Senik; I. G. Pryanishnikov

2004-01-01

34

AERIAL AND GROUND APPLICATIONS OF FUNGICIDE FOR THE CONTROL OF LEAF DISEASES IN MAIZE CROP ( Zea mayz L.)  

Microsoft Academic Search

Maize crop occupies the second place in volume of grain production in Brazil and can be infected by several leaf diseases, standing out the polysora rust ( Puccinia polyssora) and the common helminthosporiose ( Exserohilum turcicum ). The objective of the present experiment was to verify the viability of the chemical control of these diseases by means of ground and

DEISE ISABEL DA COSTA; WALTER BOLLER

35

Streaking tremor in Cascadia  

NASA Astrophysics Data System (ADS)

Details of tremor deep in subduction zones is damnably difficult to glimpse because of the lack of crisp initial arrivals, low waveform coherence, uncertain focal mechanisms, and the probability of simultaneous activity across extended regions. Yet such details hold out the best hope to illuminate the unknown mechanisms underlying episodic tremor and slip. Attacking this problem with brute force, we pointed a small, very dense seismic array down at the migration path of a good-sized episodic tremor and slip (ETS) event. In detail, it was an 84-element, 1300-m-aperture temporary seismic array in northern Washington, and the migration path of the May 2008 ETS event was 30-40 km directly underneath. Our beamforming technique tracked the time, incident angle, and azimuth of tremor radiation in unprecedented detail. We located the tremor by assuming it occurs on the subduction interface, estimated relative tremor moment released by each detected tremor window, and mapped it on the interface [Ghosh et al., GRL, 2009]. Fortunately for our ability to image it, the tremor generally appears to emanate from small regions, and we were surprised by how steadily the regions migrated with time. For the first time in Cascadia, we found convergence-parallel transient streaks of tremor migrating at velocities of several tens of km/hr, with movement in both up- and down-dip directions. Similar patterns have been seen in Japan [Shelly, G3, 2007]. This is in contrast to the long-term along-strike marching of tremor at 10 km/day. These streaks tend to propagate steadily and often repeat the same track on the interface multiple times. They light up persistent moment patches on the interface by a combination of increased amplitude and longer residence time within the patches. The up- and down-dip migration dominates the 2 days of tremor most clearly imaged by our array. The tendency of the streaks to fill in bands is the subject of the presentation of Ghosh et al. here. The physical mechanism causing the streaks, however, is not entirely clear. We suggest surges of fluid released at the megathrust may transmit stress pulses that cause failure by reducing effective normal stress along linear corrugated weak features on the fault. Houston et al., here, will explore the implications of tremor streaks for a source model.

Vidale, J. E.; Ghosh, A.; Sweet, J. R.; Creager, K. C.; Wech, A.; Houston, H.

2009-12-01

36

Mapping QTL conferring resistance in maize to gray leaf spot disease caused by Cercospora zeina  

PubMed Central

Background Gray leaf spot (GLS) is a globally important foliar disease of maize. Cercospora zeina, one of the two fungal species that cause the disease, is prevalent in southern Africa, China, Brazil and the eastern corn belt of the USA. Identification of QTL for GLS resistance in subtropical germplasm is important to support breeding programmes in developing countries where C.?zeina limits production of this staple food crop. Results A maize RIL population (F7:S6) from a cross between CML444 and SC Malawi was field-tested under GLS disease pressure at five field sites over three seasons in KwaZulu-Natal, South Africa. Thirty QTL identified from eleven field trials (environments) were consolidated to seven QTL for GLS resistance based on their expression in at least two environments and location in the same core maize bins. Four GLS resistance alleles were derived from the more resistant parent CML444 (bin 1.10, 4.08, 9.04/9.05, 10.06/10.07), whereas the remainder were from SC Malawi (bin 6.06/6.07, 7.02/7.03, 9.06). QTLs in bin 4.08 and bin 6.06/6.07 were also detected as joint QTLs, each explained more than 11% of the phenotypic variation, and were identified in four and seven environments, respectively. Common markers were used to allocate GLS QTL from eleven previous studies to bins on the IBM2005 map, and GLS QTL “hotspots” were noted. Bin 4.08 and 7.02/7.03 GLS QTL from this study overlapped with hotspots, whereas the bin 6.06/6.07 and bin 9.06 QTLs appeared to be unique. QTL for flowering time (bin 1.07, 4.09) in this population did not correspond to QTL for GLS resistance. Conclusions QTL mapping of a RIL population from the subtropical maize parents CML444 and SC Malawi identified seven QTL for resistance to gray leaf spot disease caused by C.?zeina. These QTL together with QTL from eleven studies were allocated to bins on the IBM2005 map to provide a basis for comparison. Hotspots of GLS QTL were identified on chromosomes one, two, four, five and seven, with QTL in the current study overlapping with two of these. Two QTL from this study did not overlap with previously reported QTL.

2014-01-01

37

Bright Streak on Amalthea  

NASA Technical Reports Server (NTRS)

These two images of Jupiter's small, irregularly shaped moon Amalthea, obtained by the camera onboard NASA's Galileo spacecraft in August 1999(left) and November 1999 (right), form a 'stereo pair' that helps scientists determine this moon's shape and the topography of its surface features. Features as small as 3.8 kilometers (2.4 miles) across can be resolved in these images, making them among the highest-resolution images ever taken of Amalthea.

The large impact crater visible in both images, near the right-hand edge of Amalthea's disk, is about 40 kilometers (about 29 miles) across; two ridges, tall enough to cast shadows, extend from the top of the crater in a V-shape reminiscent of a 'rabbit ears' television antenna. To the left of these ridges, in the top center portion of Amalthea's disk, is a second large impact crater similar in size to the first crater. To the left of this second crater is a linear 'streak' of relatively bright material about 50 kilometers (31 miles) long. In previous spacecraft images of Amalthea taken from other viewing directions, this bright feature was thought to be a small, round, bright 'spot' and was given the name Ida. These new images reveal for the first time that Ida is actually a long, linear 'streak.' This bright streak may represent material ejected during the formation of the adjacent impact crater, or it may just mark the crest of a local ridge. Other patches of relatively bright material can be seen elsewhere on Amalthea's disk, although none of these other bright spots has Ida's linear shape.

In both images, sunlight is coming from the left and north is approximately up. Note that the north pole of Amalthea is missing in the right-hand image (it was cut off by the edge of the camera frame). The bright streak, Ida, is on the side of the moon that faces permanently away from Jupiter, and the crater near the right-hand edge of the disk is in the center of Amalthea's leading side (the side of the moon that 'leads' as Amalthea moves in its orbit around Jupiter).

The images are, from left to right: Amalthea taken on August 12, 1999 at a range of 446,000 kilometers (about 277,000 miles) and on November 26, 1999 at a range of 374,000 kilometers (about 232,000 miles).

2000-01-01

38

Wind Streak Changes  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-358, 12 May 2003

Mars is a dynamic planet. This pair of Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) pictures, taken 2 Mars years apart, show changes in dark streak patterns caused by wind movement of dust. The top picture was taken in July 1999, the bottom one in March 2003. The pair of images are in Tharsis near 9.5oS, 128.5oW. Sunlight illuminates both from the upper left.

2003-01-01

39

Impact of Cell Wall Composition on Maize Resistance to Pests and Diseases  

PubMed Central

In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among the same plant species, different tissues or even the same tissue at different developmental stages. Thus, it is important to highlight that the role of the cell wall components needs to be tested in diverse genotypes and specific tissues where the feeding or attacking by the pathogen takes place. Understanding the role of cell wall constituents as defense mechanisms may allow modifications of crops to withstand pests and diseases.

Santiago, Rogelio; Barros-Rios, Jaime; Malvar, Rosa A.

2013-01-01

40

Influence of Maize Root Colonization by the Rhizosphere Actinomycetes and Yeast Fungi on Plant Growth and on the Biological Control of Late Wilt Disease  

Microsoft Academic Search

Isolates of 85 actinomycetes and 40 yeast fungi were obtained from the rhizosphere of maize plant (Zea mays L.) and were screened for in vitro antagonism to Cephalosporium maydis, a causal agent of late wilt disease of maize. Of these, six actinomycetes and five yeast fungi isolates were found to be strongly antagonistic to the pathogen in vitro. The isolates

ADEL A. EL-MEHALAWY; NAZIHA M. HASSANEIN; HEND M. KHATER; EL-ZAHRAA A. KARAM EL-DIN; YOUSSEF A. YOUSSEF

41

Studies on certain aspects of chemical control of bacterial stalk rot disease of maize.  

PubMed

Sandoz seed dressing 6335 showing high efficacy in checking the growth of the maize stalk rot pathogen Erwinia carotovora f. sp. zeae Sabet in culture. Brestan, Antracol, Difolatan, Aratan, Duter, Ceresan wet, Flit-406, Cuman, Blitox-50, Streptocycline, Agrimycin, Terramycin, Actidione, Aureomycin, Chloromycetin, Penicillin G, and Streptomycin were moderately effective. The rest of the 35 chemicals was negligible in its influence. 15 different chemicals, namely Agrimycin, Streptocycline, Chloromycetin, Sodium penicillin G, Actidione, Terramycin, Aureomycin, Sandoz seed dressing 6335, Antracol, Aratan, Blitox-50, Diflotan-80, Ceresan wet, Cuman and Brestan 60 could also control the disease, but only when the plants were treated in vivo immediately after inoculation. They could not show any effectiveness, however, after 24, 48, and 72 hours of inoculation, showing their failure to control, once the infection has taken place by the pathogen. PMID:857509

Sinha, S K; Prasad, M

1977-01-01

42

Efficacy of Burkholderia cepacia MCI 7 in disease suppression and growth promotion of maize  

Microsoft Academic Search

Repeated greenhouse experiments were performed to evaluate the ability of a maize-rhizosphere isolate of Burkholderia cepacia, applied as a seed coating, to promote maize growth in both uninfested soil and soil infested with a maize pathogenic strain\\u000a of Fusarium moniliforme, and to displace or negatively affect the population of F. moniliforme throughout plant growth. Results demonstrated that the B. cepacia

A. Bevivino; C. Dalmastri; S. Tabacchioni; L. Chiarini

2000-01-01

43

Circles and Streaks  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-544, 14 November 2003

This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, acquired less than a week ago on 8 November 2003, shows a typical southern middle-to-high latitude scene at this time of year. It is summer in the southern hemisphere, and regions such as Promethei Terra, where this image was acquired, are being streaked by dust devils that remove or disrupt the coating of dust that was deposited over the region in the previous autumn or winter. While no active dust devils were captured in this scene, their tell-tale tracks are scratched all across the image. The circular features are the sites of buried meteor impact craters; their rims form dark rings; the material that fills the craters has become cracked. This picture is located near 68.1oS, 247.9oW. The area shown is approximately 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.

2003-01-01

44

Mapping Resistance Quantitative Trait Loci for Three Foliar Diseases in a Maize Recombinant Inbred Line Population—Evidence for Multiple Disease Resistance?  

Microsoft Academic Search

Zwonitzer, J. C., Coles, N. D., Krakowsky, M. D., Arellano, C., Holland, J. B., McMullen, M. D., Pratt, R. C., and Balint-Kurti, P. J. 2010. Mapping resistance quantitative trait loci for three foliar diseases in a maize recombinant inbred line population—evidence for multiple disease resistance? Phytopathology 100:72-79. Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB)

John C. Zwonitzer; Nathan D. Coles; Matthew D. Krakowsky; Consuelo Arellano; James B. Holland; Michael D. McMullen; Richard C. Pratt; Peter J. Balint-Kurti

2010-01-01

45

A Porphyrin Pathway Impairment Is Responsible for the Phenotype of a Dominant Disease Lesion Mimic Mutant of Maize  

Microsoft Academic Search

The maize lesion mimic gene Les22 is defined by dominant mutations and characterized by the production of minute necrotic spots on leaves in a developmentally specified and light-dependent manner. Phenotypically, Les22 lesions re- semble those that are triggered during a hypersensitive disease resistance response of plants to pathogens. We have cloned Les22 by using a Mutator -tagging technique. It encodes

Gongshe Hu; Nasser Yalpani; Steven P. Briggs; Gurmukh S. Johal

1998-01-01

46

Root Interactions in a Maize/Soybean Intercropping System Control Soybean Soil-Borne Disease, Red Crown Rot  

PubMed Central

Background Within-field multiple crop species intercropping is well documented and used for disease control, but the underlying mechanisms are still unclear. As roots are the primary organ for perceiving signals in the soil from neighboring plants, root behavior may play an important role in soil-borne disease control. Principal Findings In two years of field experiments, maize/soybean intercropping suppressed the occurrence of soybean red crown rot, a severe soil-borne disease caused by Cylindrocladium parasiticum (C. parasiticum). The suppressive effects decreased with increasing distance between intercropped plants under both low P and high P supply, suggesting that root interactions play a significant role independent of nutrient status. Further detailed quantitative studies revealed that the diversity and intensity of root interactions altered the expression of important soybean PR genes, as well as, the activity of corresponding enzymes in both P treatments. Furthermore, 5 phenolic acids were detected in root exudates of maize/soybean intercropped plants. Among these phenolic acids, cinnamic acid was released in significantly greater concentrations when intercropped maize with soybean compared to either crop grown in monoculture, and this spike in cinnamic acid was found dramatically constrain C. parasiticum growth in vitro. Conclusions To the best of our knowledge, this study is the first report to demonstrate that intercropping with maize can promote resistance in soybean to red crown rot in a root-dependent manner. This supports the point that intercropping may be an efficient ecological strategy to control soil-borne plant disease and should be incorporated in sustainable agricultural management practices.

Gao, Xiang; Wu, Man; Xu, Ruineng; Wang, Xiurong; Pan, Ruqian; Kim, Hye-Ji; Liao, Hong

2014-01-01

47

Dust streaks on Mars: Colors and photometry  

NASA Astrophysics Data System (ADS)

Photometric studies of crater related bright and dark streaks have strongly supported the hypothesis that the bright streaks are excess dust deposits and dark streaks are erosional windows in a partial dust cover. Red-blue (and red-violet) plots show that bright streaks are consistent with mosaics of bright red dust and background material. Here the plains are also consistent with a partial dust cover; the dark streak is the least covered area. Bright and dark streaks both reverse contrast relative to surrounding plains at phase angles over 100 deg in violet filter images. The similar phase behavior of both bright and dark streaks supports the idea that they are both changes in the amount of dust cover. Red-violet plots of bright streaks are most easily explained by mosaics of optically thick dust and plains material. Lengths of bright streaks are independent of their contrasts. This suggests the streak deposition, if in the mosaic patterns indicated above, is a function of available sites of deposition, rather than atmospheric dust loading. Contrasts of dark streaks with plains indicate the plains have fractional dust covers nearly as great as the maximum additional cover in bright streaks. The bright streaks thus store little of the global supply of dust.

Thomas, P.

1984-04-01

48

Field Evaluation of Transgenic and Classical Sources of Wheat streak mosaic virus Resistance  

Microsoft Academic Search

of the disease include light green and yellow streaking of the leaves as well as curling of the leaves due to mite The development of wheat (Triticum aestivum L.) cultivars that activity. Infected plants typically exhibit stunted growth, are resistant to Wheat streak mosaic virus (WSMV), yet competitive in yield under nondiseased conditions, is an objective for breeding reduced tillering,

G. L. Sharp; J. M. Martin; S. P. Lanning; N. K. Blake; C. W. Brey; E. Sivamani; R. Qu; L. E. Talbert

49

Streaking into middle school science: The Dell Streak pilot project  

NASA Astrophysics Data System (ADS)

A case study is conducted implementing the Dell Streak seven-inch android device into eighth grade science classes of one teacher in a rural middle school in the Piedmont region of North Carolina. The purpose of the study is to determine if the use of the Dell Streaks would increase student achievement on standardized subject testing, if the Streak could be used as an effective instructional tool, and if it could be considered an effective instructional resource for reviewing and preparing for the science assessments. A mixed method research design was used for the study to analyze both quantitative and qualitative results to determine if the Dell Streaks' utilization could achieve the following: 1. instructional strategies would change, 2. it would be an effective instructional tool, and 3. a comparison of the students' test scores and benchmark assessments' scores would provide statistically significant difference. Through the use of an ANOVA it was determined a statistically significant difference had occurred. A Post Hoc analysis was conducted to identify where the difference occurred. Finally a T-test determined was there was no statistically significance difference between the mean End-of-Grade tests and four quarterly benchmark scores of the control and the experimental groups. Qualitative research methods were used to gather results to determine if the Streaks were an effective instructional tool. Classroom observations identified that the teacher's teaching styles and new instructional strategies were implemented throughout the pilot project. Students had an opportunity to complete a questionnaire three times during the pilot project. Results revealed what the students liked about using the devices and the challenges they were facing. The teacher completed a reflective questionnaire throughout the pilot project and offered valuable reflections about the use of the devices in an educational setting. The reflection data supporting the case study was drawn from the teacher's statements regarding the change in instructional delivery as a respect of using the students' device. The results section of the study will elaborate upon these findings. The study recommendations on the use of the Dell Streak device will address whether further actions as the use of the Streak technology in the classroom and summary section.

Austin, Susan Eudy

50

Properties of martian slope streak populations  

NASA Astrophysics Data System (ADS)

Slope streaks are down-slope mass movements on the surface of Mars that are among the few known examples of contemporary geologic activity on Mars. Here we study slope streak activity over three decades, based on overlapping images in the Lycus Sulci region taken by the Context Camera (CTX) 2007-2010 and the Viking Orbiter Camera in 1977. The number of disappeared slope streaks is nearly equal the number of newly formed slope streaks, suggesting the streak population is balanced. The turnover time of the population is estimated to be four decades. Slope streaks fade gradually over time, with islands of persistence. We also determine the number of observable slope streaks as a function of image resolution based on images by the High Resolution Imaging Science Experiment (HiRISE) camera, and find that the number of discernible slope streaks can increase rapidly with spatial resolution.

Bergonio, Justin R.; Rottas, Kimberly M.; Schorghofer, Norbert

2013-07-01

51

Slope Streaks in Terra Sabaea  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1 Click on image for larger version

This HiRISE image shows the rim of a crater in the region of Terra Sabaea in the northern hemisphere of Mars.

The subimage (figure 1) is a close-up view of the crater rim revealing dark and light-toned slope streaks. Slope streak formation is among the few known processes currently active on Mars. While their mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material.

Other ideas include the triggering of slope streak formation by possible concentrations of near-surface ice or scouring of the surface by running water from aquifers intercepting slope faces, spring discharge (perhaps brines), and/or hydrothermal activity.

Several of the slope streaks in the subimage, particularly the three longest darker streaks, show evidence that downslope movement is being diverted around obstacles such as large boulders. Several streaks also appear to originate at boulders or clumps of rocky material.

In general, the slope streaks do not have large deposits of displaced material at their downslope ends and do not run out onto the crater floor suggesting that they have little reserve kinetic energy. The darkest slope streaks are youngest and can be seen to cross cut and superpose older and lighter-toned streaks. The lighter-toned streaks are believed to be dark streaks that have lightened with time as new dust is deposited on their surface.

Observation Geometry Image PSP_001808_1875 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 15-Dec-2006. The complete image is centered at 7.4 degrees latitude, 47.0 degrees East longitude. The range to the target site was 272.1 km (170.1 miles). At this distance the image scale is 54.4 cm/pixel (with 2 x 2 binning) so objects 163 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel and north is up. The image was taken at a local Mars time of 03:36 PM and the scene is illuminated from the west with a solar incidence angle of 53 degrees, thus the sun was about 37 degrees above the horizon. At a solar longitude of 150.7 degrees, the season on Mars is Northern Summer.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

2007-01-01

52

Analysis of the diversity of African streak mastreviruses using PCR-generated RFLPs and partial sequence data  

Microsoft Academic Search

Maize streak virus (MSV) is the most economically significant member of a diverse group of African grass-infecting Mastrevirus species in the family Geminiviridae. We designed a single set of degenerate primers which enables the PCR amplification of an approximately 1300 bp DNA fragment spanning both conserved (the RepA gene) and variable (the long intergenic region and MP gene) portions of

J. A Willment; D. P Martin; E. P Rybicki

2001-01-01

53

Dark streaks on talus slopes, Mars  

NASA Technical Reports Server (NTRS)

High-resolution pictures of talus slopes on Mars show small, dark streaks that characteristically widen downward. These streaks are different from the thin and even streaks of various albedos that stream from cliffs on talus slopes, but gradations between the two streak types occur and not all streaks can be classified with confidence. In order to study the nature and origin of the small, widening, dark streaks, all Viking pictures with a resolution of less than 100 m/pixel were surveyed. To date several hundred streaks were located, but only few are of high enough resolution to be confidently identified as widening downwards. The approximate dimensions of the streaks were measured and their shapes, numbers, position, and spacing on slopes were noted. They were plotted on a topographic map, and their relation to topography, geologic units, and regions of distinct thermal inertia and albedo were studied. Also noted was the season at which images containing streaks were acquired and the direction of illumination. Albedo measurements are in progress. Several streaks can be seen stereoscopically, but none are observed on color images. The observation of small dark streaks on talus slopes on Mars is compatible with an interpretation of their origin as eruptions of small masses of wet debris in places where steep walls intersect aquifers or where seasonal equatorial warming permits the local melting of ground ice.

Ferguson, H. M.; Lucchitta, B. K.

1984-01-01

54

Wind vs. Dust Devil Streaks  

NASA Technical Reports Server (NTRS)

22 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image presents a fine illustration of the difference between streaks made by dust devils and streaks made by wind gusts. Dust devils are usually solitary, spinning vortices. They resemble a tornado, or the swirling motion of a familiar, Tasmanian cartoon character. Wind gusts, on the other hand, can cover a larger area and affect more terrain at the same time. The dark, straight, and parallel features resembling scrape marks near the right/center of this image are thought to have been formed by a singular gust of wind, whereas the more haphazard dark streaks that crisscross the scene were formed by dozens of individual dust devils, acting at different times. This southern summer image is located in Noachis Terra near 67.0oS, 316.2oW. Sunlight illuminates the scene from the upper left; the picture covers an area 3 km (1.9 mi) wide.

2004-01-01

55

Southern rice black-streaked dwarf virus: a white-backed planthopper-transmitted fijivirus threatening rice production in Asia.  

PubMed

Southern rice black-streaked dwarf virus (SRBSDV), a non-enveloped icosahedral virus with a genome of 10 double-stranded RNA segments, is a novel species in the genus Fijivirus (family Reoviridae) first recognized in 2008. Rice plants infected with this virus exhibit symptoms similar to those caused by Rice black-streaked dwarf virus. Since 2009, the virus has rapidly spread and caused serious rice losses in East and Southeast Asia. Significant progress has been made in recent years in understanding this disease, especially about the functions of the viral genes, rice-virus-insect interactions, and epidemiology and control measures. The virus can be efficiently transmitted by the white-backed planthopper (WBPH, Sogatella furcifera) in a persistent circulative propagative manner but cannot be transmitted by the brown planthopper (Nilaparvata lugens) and small brown planthopper (Laodelphax striatellus). Rice, maize, Chinese sorghum (Coix lacryma-jobi) and other grass weeds can be infected via WBPH. However, only rice plays a major role in the virus infection cycle because of the vector's preference. In Southeast Asia, WBPH is a long-distance migratory rice pest. The disease cycle can be described as follows: SRBSDV and its WBPH vector overwinter in warm tropical or sub-tropical areas; viruliferous WBPH adults carry the virus from south to north via long-distance migration in early spring, transmit the virus to rice seedlings in the newly colonized areas, and lay eggs on the infected seedlings; the next generation of WBPHs propagate on infected seedlings, become viruliferous, disperse, and cause new disease outbreaks. Several molecular and serological methods have been developed to detect SRBSDV in plant tissues and individual insects. Control measures based on protection from WBPH, including seedbed coverage, chemical seed treatments, and chemical spraying of seedlings, have proven effective in China. PMID:24058362

Zhou, Guohui; Xu, Donglin; Xu, Dagao; Zhang, Maoxin

2013-01-01

56

Southern rice black-streaked dwarf virus: a white-backed planthopper-transmitted fijivirus threatening rice production in Asia  

PubMed Central

Southern rice black-streaked dwarf virus (SRBSDV), a non-enveloped icosahedral virus with a genome of 10 double-stranded RNA segments, is a novel species in the genus Fijivirus (family Reoviridae) first recognized in 2008. Rice plants infected with this virus exhibit symptoms similar to those caused by Rice black-streaked dwarf virus. Since 2009, the virus has rapidly spread and caused serious rice losses in East and Southeast Asia. Significant progress has been made in recent years in understanding this disease, especially about the functions of the viral genes, rice–virus–insect interactions, and epidemiology and control measures. The virus can be efficiently transmitted by the white-backed planthopper (WBPH, Sogatella furcifera) in a persistent circulative propagative manner but cannot be transmitted by the brown planthopper (Nilaparvata lugens) and small brown planthopper (Laodelphax striatellus). Rice, maize, Chinese sorghum (Coix lacryma-jobi) and other grass weeds can be infected via WBPH. However, only rice plays a major role in the virus infection cycle because of the vector’s preference. In Southeast Asia, WBPH is a long-distance migratory rice pest. The disease cycle can be described as follows: SRBSDV and its WBPH vector overwinter in warm tropical or sub-tropical areas; viruliferous WBPH adults carry the virus from south to north via long-distance migration in early spring, transmit the virus to rice seedlings in the newly colonized areas, and lay eggs on the infected seedlings; the next generation of WBPHs propagate on infected seedlings, become viruliferous, disperse, and cause new disease outbreaks. Several molecular and serological methods have been developed to detect SRBSDV in plant tissues and individual insects. Control measures based on protection from WBPH, including seedbed coverage, chemical seed treatments, and chemical spraying of seedlings, have proven effective in China.

Zhou, Guohui; Xu, Donglin; Xu, Dagao; Zhang, Maoxin

2013-01-01

57

Overexpression of Rice Black-Streaked Dwarf Virus P7-1 in Arabidopsis Results in Male Sterility Due to Non-Dehiscent Anthers  

PubMed Central

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, is propagatively transmitted by the small brown planthopper (Laodelphax striatellus Fallén). RBSDV causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China. Although several RBSDV proteins have been studied in detail, the functions of the nonstructural protein P7-1 are still largely unknown. To investigate the role of the P7-1 protein in virus pathogenicity, transgenic Arabidopsis thaliana plants were generated in which the P7-1 gene was expressed under the control of the 35S promoter. The RBSDV P7-1-transgenic Arabidopsis plants (named P7-1-OE) were male sterility. Flowers and pollen from P7-1-transgenic plants were of normal size and shape, and anthers developed to the normal size but failed to dehisce. The non-dehiscent anthers observed in P7-1-OE were attributed to decreased lignin content in the anthers. Furthermore, the reactive oxygen species levels were quite low in the transgenic plants compared with the wild type. These results indicate that ectopic expression of the RBSDV P7-1 protein in A. thaliana causes male sterility, possibly through the disruption of the lignin biosynthesis and H2O2-dependent polymerization pathways.

Sun, Feng; Yuan, Xia; Xu, Qiufang; Zhou, Tong; Fan, Yongjian; Zhou, Yijun

2013-01-01

58

Bright Streaks and Dark Fans  

NASA Technical Reports Server (NTRS)

The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the 'cryptic terrain,' the ice is translucent and sunlight can penetrate through the ice to warm the surface below.

The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is 'visible' by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans.

Bright streaks in this image are fresh frost. The CRISM team has identified the composition of these streaks to be carbon dioxide.

Observation Geometry Image PSP_003113_0940 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 26-Mar-2007. The complete image is centered at -85.8 degrees latitude, 106.0 degrees East longitude. The range to the target site was 244.9 km (153.0 miles). At this distance the image scale is 49.0 cm/pixel (with 2 x 2 binning) so objects 147 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 06:20 PM and the scene is illuminated from the west with a solar incidence angle of 79 degrees, thus the sun was about 11 degrees above the horizon. At a solar longitude of 207.6 degrees, the season on Mars is Northern Autumn.

2007-01-01

59

Electro-optic Phase Grating Streak Spectrometer  

SciTech Connect

The electro-optic phase grating streak spectrometer (EOPGSS) generates a time-resolved spectra equivalent to that obtained with a conventional spectrometer/streak camera combination, but without using a streak camera (by far the more expensive and problematic component of the conventional system). The EOPGSS is based on a phase, rather than an amplitude grating. Further, this grating is fabricated of electro-optic material such as, for example, KD*P, by either etching grooves into an E-O slab, or by depositing lines of the E-O material onto an optical flat. An electric field normal to the grating alters the material’s index of refraction and thus affects a shift (in angle) of the output spectrum. Ramping the voltage streaks the spectrum correspondingly. The streak and dispersion directions are the same, so a second (static, conventional) grating disperses the spectrum in the orthogonal direction to prevent different wavelengths from “overwriting” each other. Because the streaking is done by the grating, the streaked output spectrum is recorded with a time-integrating device, such as a CCD. System model, typical design, and performance expectations will be presented.

Goldin, F. J.

2012-08-02

60

Ozone, jet streaks and severe weather  

NASA Technical Reports Server (NTRS)

Data from three independent observing platforms are synthesized to study the role of jet streaks in severe weather. The three data types are: conventional radiosondes; 6.7 micron water vapor imagery from the GOES satellite; and total ozone imagery from Nimbus 7. Diagnoses are then made of potential vorticity, mid-tropospheric moisture, and total ozone at and below the level of jet streaks. Potential vorticity and total ozone distributions are both tracers of stratospheric air. Theoretically, both should respond to the transverse, vertical circulations expected in the vicinity of jet streaks. Both should increase due to the sinking above the left front quadrant of the streaks. Moisture, on the other hand, increases in the ascent under the left front quadrant. This study shows striking agreement between the three parameters independently observed from three different observing platforms. Moreover, the three severe weather case studies suggest a unique distribution of ozone, potential vorticity, and mid-tropospheric moisture relative to a jet streak. This, in turn, led to the creation of a new ozone/jet streak model which shows that the total ozone distribution provides a signature in the vicinity of jet streaks and permits identification of areas most likely to experience severe weather at a later time. The value of such observations to operational forecasting is discussed.

Sechrist, Frank S.; Petersen, Ralph A.; Brill, Keith F.; Krueger, Arlin J.; Uccellini, Louis W.

1987-01-01

61

The diversity of Banana streak virus isolates in Uganda.  

PubMed

In a study of the variation among isolates of Banana streak virus (BSV) in Uganda, 140 sequences were obtained from 49 samples by PCR across the conserved reverse transcriptase/RNaseH region of the genome. Pairwise comparison of these sequences suggested that they represented 15 different species and phylogenetic analyses showed that all species fell into three major clades based on 28% sequence difference. In addition to the Ugandan sequences, clade I also contained BSV species that are known as both integrated sequences and episomal viruses; clade II also contained integrated BSV sequences but which have not previously been identified as episomal viruses. Clade III comprised of Sugarcane bacilliform virus isolates and Ugandan BSV sequences and for which there is no evidence of integration. The possible reasons for the extraordinary levels of virus sequence variation and the potential origins and epidemiology of these viruses causing banana streak disease are discussed. PMID:16096705

Harper, G; Hart, D; Moult, S; Hull, R; Geering, A; Thomas, J

2005-12-01

62

Positive selection and intragenic recombination contribute to high allelic diversity in effector genes of Mycosphaerella fijiensis, causal agent of the black leaf streak disease of banana.  

PubMed

Previously, we have determined the nonhost-mediated recognition of the MfAvr4 and MfEcp2 effector proteins from the banana pathogen Mycosphaerella fijiensis in tomato, by the cognate Cf-4 and Cf-Ecp2 resistance proteins, respectively. These two resistance proteins could thus mediate resistance against M.?fijiensis if genetically transformed into banana (Musa spp.). However, disease resistance controlled by single dominant genes can be overcome by mutated effector alleles, whose products are not recognized by the cognate resistance proteins. Here, we surveyed the allelic variation within the MfAvr4, MfEcp2, MfEcp2-2 and MfEcp2-3 effector genes of M.?fijiensis in a global population of the pathogen, and assayed its impact on recognition by the tomato Cf-4 and Cf-Ecp2 resistance proteins, respectively. We identified a large number of polymorphisms that could reflect a co-evolutionary arms race between host and pathogen. The analysis of nucleotide substitution patterns suggests that both positive selection and intragenic recombination have shaped the evolution of M.?fijiensis effectors. Clear differences in allelic diversity were observed between strains originating from South-East Asia relative to strains from other banana-producing continents, consistent with the hypothesis that M.?fijiensis originated in the Asian-Pacific region. Furthermore, transient co-expression of the MfAvr4 effector alleles and the tomato Cf-4 resistance gene, as well as of MfEcp2, MfEcp2-2 and MfEcp2-3 and the putative Cf-Ecp2 resistance gene, indicated that effector alleles able to overcome these resistance genes are already present in natural populations of the pathogen, thus questioning the durability of resistance that can be provided by these genes in the field. PMID:24245940

Stergiopoulos, Ioannis; Cordovez, Viviane; Okmen, Bilal; Beenen, Henriek G; Kema, Gert H J; de Wit, Pierre J G M

2014-06-01

63

Atomic and molecular phases through attosecond streaking  

SciTech Connect

In attosecond streaking, an electron is released by a short xuv pulse into a strong near infrared laser field. If the laser couples two states in the target, the streaking technique, which allows for a complete determination of the driving field, also gives an accurate measurement of the relative phase of the atomic or molecular ionization matrix elements from the two states through the interference from the two channels. The interference may change the phase of the photoelectron streaking signal within the envelope of the infrared field, an effect to be accounted for when reconstructing short pulses from the photoelectron signal and in attosecond time-resolved measurements.

Baggesen, Jan Conrad; Madsen, Lars Bojer [Lundbeck Foundation Theoretical Center for Quantum System Research, Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

2011-02-15

64

Enhanced virus resistance in transgenic maize expressing a dsRNA-specific endoribonuclease gene from E. coli.  

PubMed

Maize rough dwarf disease (MRDD), caused by several Fijiviruses in the family Reoviridae, is a global disease that is responsible for substantial yield losses in maize. Although some maize germplasm have low levels of polygenic resistance to MRDD, highly resistant cultivated varieties are not available for agronomic field production in China. In this work, we have generated transgenic maize lines that constitutively express rnc70, a mutant E. coli dsRNA-specific endoribonuclease gene. Transgenic lines were propagated and screened under field conditions for 12 generations. During three years of evaluations, two transgenic lines and their progeny were challenged with Rice black-streaked dwarf virus (RBSDV), the causal agent of MRDD in China, and these plants exhibited reduced levels of disease severity. In two normal years of MRDD abundance, both lines were more resistant than non-transgenic plants. Even in the most serious MRDD year, six out of seven progeny from one line were resistant, whereas non-transgenic plants were highly susceptible. Molecular approaches in the T12 generation revealed that the rnc70 transgene was integrated and expressed stably in transgenic lines. Under artificial conditions permitting heavy virus inoculation, the T12 progeny of two highly resistant lines had a reduced incidence of MRDD and accumulation of RBSDV in infected plants. In addition, we confirmed that the RNC70 protein could bind directly to RBSDV dsRNA in vitro. Overall, our data show that RNC70-mediated resistance in transgenic maize can provide efficient protection against dsRNA virus infection. PMID:23593318

Cao, Xiuling; Lu, Yingui; Di, Dianping; Zhang, Zhiyan; Liu, He; Tian, Lanzhi; Zhang, Aihong; Zhang, Yanjing; Shi, Lindan; Guo, Bihong; Xu, Jin; Duan, Xifei; Wang, Xianbing; Han, Chenggui; Miao, Hongqin; Yu, Jialin; Li, Dawei

2013-01-01

65

Compact Optical Technique for Streak Camera Calibration  

SciTech Connect

The National Ignition Facility is under construction at the Lawrence Livermore National Laboratory for the U.S. Department of Energy Stockpile Stewardship Program. Optical streak cameras are an integral part of the experimental diagnostics instrumentation. To accurately reduce data from the streak cameras a temporal calibration is required. This article describes a technique for generating trains of precisely timed short-duration optical pulses that are suitable for temporal calibrations.

Curt Allen; Terence Davies; Frans Janson; Ronald Justin; Bruce Marshall; Oliver Sweningsen; Perry Bell; Roger Griffith; Karla Hagans; Richard Lerche

2004-04-01

66

Performance comparison of streak camera recording systems  

SciTech Connect

Streak camera based diagnostics are vital to the inertial confinement fusion program at Sandia National Laboratories. Performance characteristics of various readout systems coupled to an EGG-AVO streak camera were analyzed and compared to scaling estimates. The purpose of the work was to determine the limits of the streak camera performance and the optimal fielding conditions for the Amador Valley Operations (AVO) streak camera systems. The authors measured streak camera limitations in spatial resolution and sensitivity. Streak camera limits on spatial resolution are greater than 18 lp/mm at 4% contrast. However, it will be difficult to make use of any resolution greater than this because of high spatial frequency variation in the photocathode sensitivity. They have measured a signal to noise of 3,000 with 0.3 mW/cm{sup 2} of 830 nm light at a 10 ns/mm sweep speed. They have compared lens coupling systems with and without micro-channel plate intensifiers and systems using film or charge coupled device (CCD) readout. There were no conditions where film was found to be an improvement over the CCD readout. Systems utilizing a CCD readout without an intensifier have comparable resolution, for these source sizes and at a nominal cost in signal to noise of 3, over those with an intensifier. Estimates of the signal-to-noise for different light coupling methods show how performance can be improved.

Derzon, M. [Sandia National Labs., Albuquerque, NM (United States). Diagnostics and Target Experiment Dept.; Barber, T. [K-tech Corp., Albuquerque, NM (United States)

1995-07-01

67

Comparison of optical streak tube performance  

NASA Astrophysics Data System (ADS)

The ICF program at Livermore has a large inventory of optical streak cameras that were built in the 1970s and 1980s. The cameras include microchannel plate image-intensifier tubes (IIT) that provide signal amplification and early lens-coupled CCD readouts. Today, these cameras are still very functional, but some replacement parts such as the original streak tube, CCD, and IIT are scarce and obsolete. This article describes recent efforts to compare the performance of different commercially available streak tubes in an updated camera employing current advanced CCD readout technologies. Measurements of camera performance characteristics including linearity, spatial and temporal resolution, line-spread function, contrast transfer ratio (CTR), and dynamic range have been made for the same camera configuration: CCD coupled directly to the various streak tubes. Streak tube operation with large average tube current was observed by illuminating the entire slit region through a Ronchi ruling and measuring the CTR. This work was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48.

McDonald, Joseph; Learch, Richard; Andrews, David; Vergel de Dios, Eugene; Griffith, Roger; Bell, Perry

2003-10-01

68

Femtosecond streak tubes designing, manufacturing, and testing  

NASA Astrophysics Data System (ADS)

New generation of streak tubes intended for single-shot and synchroscan operations with femtosecond time resolution was computer modelled, designed, manufactured, tested and adopted for further application in laser research. The developed PV-FS type tubes provide close to 100 fs-time resolution in single-shot streak mode. It is important to note that the PV-FS tubes may be equipped with Peltier cooled S1-photocathodes and their spectral sensitivity may cover the range of 115 - 1550 nm. The developed photocathodes have very low surface resistance (tens of Ohm per square unit). New tubes offer a high (more than 50 line pairs/mm) spatial resolution when recording ultrafast optical images with femtosecond time resolution. Due to keeping the PV-FS external geometry similar to the well-known PV-type tubes it becomes possible to install new devices into available streak cameras (AGAT, Imacon 500, etc.).

Degtyareva, Valentina P.; Belolipetskii, Vladimir S.; Bryukhnevich, Gennadii I.; Ivanova, Svetlana R.; Levina, Galina P.; Makushina, Valentina A.; Polikarkina, Nadejda D.; Semichastnova, Zoya M.; Schelev, Mikhail Y.

2003-07-01

69

Ozone, jet streaks, and severe weather  

NASA Technical Reports Server (NTRS)

Data obtained with the total ozone mapping spectrometer (TOMS) onboard the Nimbus-7 satellite are presented. An attempt is made to relate and synthesize TOMS data with conventional radiosonde analyses and with midtropospheric moisture data available from the VISSR onboard the GOES. Case studies are described which relate the potential vorticity structure of the upper troposphere to the total ozone distribution as measured by TOMS. Cyclogenesis, frontogenesis, and the formation of severe weather outbreaks are then related to jet streaks and their characteristic ozone signature. It is shown that the primary maxima of ozone and potential vorticity are associated with cold advection and subsidence in the main upper-air trough as suggested earlier. The secondary maxima of the three quantities diagnosed in the present work appear in the left front quadrant of a jet streak, revealing the importance of transverse, secondary motions induced by a jet streak above the level of maximum winds in further modifying the potential vorticity and ozone structures.

Sechrist, F. S.; Petersen, R. A.; Krueger, A. J.; Uccellini, L. W.; Brill, K. F.

1986-01-01

70

Martian crater dark streak lengths - Explanation from wind tunnel experiments  

NASA Astrophysics Data System (ADS)

The mechanism determining the length of dark erosional (type-Id) streaks near craters and hills on the surface of Mars is investigated using Mariner-9 images and the results of wind-tunnel studies (Greeley et al., 1974; Iversen et al., 1975 and 1976). An empirical model of time-dependent growth of crater-wake streaks in the downwind direction involving deflation by sand-grain saltation is developed and shown to give relatively good agreement with streak growth rates observed over a 38-day period of Mariner observations and with the streak-length/crater-diameter and streak-length/crater-height ratios analyzed statistically by Lee (1984). This time-dependent mechanism is thus considered a reasonable alternative (for dark streaks) to the blocking model proposed by Lee for both bright and dark streaks. Preliminary analysis of further wind-tunnel experiments (Iversen et al., 1982) supports the blocking model of bright-streak formation.

Iversen, J. D.; Greeley, R.

1984-06-01

71

Martian Slope Streaks and Gullies: Origins as Dry Granular Flows  

NASA Technical Reports Server (NTRS)

Streaks and gullies are common on Martian slopes, and are geologically young; slope streaks have formed during the last few years of Mars Global Surveyor imaging. Both slope streaks and gullies involve flow of granular material, but it is not clear whether liquid water (or another suspending agent) was involved. The possibility that liquid water was involved makes gullies and slope streaks important for understanding Mars recent climate and for the hope of extant life near its surface. Here, we show that significant features of slope streaks and gullies are consistent with dry flows of granular material. Liquid water may not be required.

Treiman, A. H.; Louge, M. Y.

2004-01-01

72

Wind Streaks on Venus: Clues to Atmospheric Circulation  

NASA Technical Reports Server (NTRS)

Magellan images reveal surface features on Venus attributed to wind processes. Sand dunes, wind-sculpted hills, and more than 5830 wind streaks have been identified. The streaks serve as local "wind vanes," representing wind direction at the time of streak formation and allowing the first global mapping of near-surface wind patterns on Venus. Wind streaks are oriented both toward the equator and toward the west. When streaks associated with local transient events, such as impact cratering, are deleted, the westward component is mostly lost but the equatorward component remains. This pattern is consistent with a Hadley circulation of the lower atmosphere.

Greeley, Ronald; Schubert, Gerald; Limonadi, Daniel; Bender, Kelly C.; Newman, William I.; Thomas, Peggy E.; Weitz, Catherine M.; Wall, Stephen D.

1994-01-01

73

How Accurate Is the Attosecond Streak Camera?  

NASA Astrophysics Data System (ADS)

An attosecond streak camera holds the promise of time resolving the dynamics of photoionization with a few-attosecond accuracy. But can the attosecond measurement be disentangled from the process it measures? We address this question by deriving simple closed-form analytical expressions for the measurement-related apparent time delays in photoionization, associated with the application of the attosecond streak camera and/or resolution of attosecond beating by interference of two-photon transitions techniques. Our analytical results are accurate on about the 1 asec level and show that both intrinsic and measurement-induced delays depend on the same scattering phase and are, therefore, not independent. We also suggest a procedure for extracting intrinsic time delays from the measurement and a possible resolution of the controversy caused by the experiments of Schultze et al. [Science 328, 1658 (2010)SCIEAS0036-807510.1126/science.1189401].

Ivanov, Misha; Smirnova, Olga

2011-11-01

74

Understanding baseball team standings and streaks  

NASA Astrophysics Data System (ADS)

Can one understand the statistics of wins and losses of baseball teams? Are their consecutive-game winning and losing streaks self-reinforcing or can they be described statistically? We apply the Bradley-Terry model, which incorporates the heterogeneity of team strengths in a minimalist way, to answer these questions. Excellent agreement is found between the predictions of the Bradley-Terry model and the rank dependence of the average number team wins and losses in major-league baseball over the past century when the distribution of team strengths is taken to be uniformly distributed over a finite range. Using this uniform strength distribution, we also find very good agreement between model predictions and the observed distribution of consecutive-game team winning and losing streaks over the last half-century; however, the agreement is less good for the previous half-century. The behavior of the last half-century supports the hypothesis that long streaks are primarily statistical in origin with little self-reinforcing component. The data further show that the past half-century of baseball has been more competitive than the preceding half-century.

Sire, C.; Redner, S.

2009-02-01

75

Pantoea stewartii subsp. stewartii exhibits surface motility, which is a critical aspect of Stewart's wilt disease development on maize.  

PubMed

Pantoea stewartii subsp. stewartii is a plant-pathogenic bacterium that causes Stewart's vascular wilt in maize. The organism is taxonomically described as aflagellated and nonmotile. We recently showed that P. stewartii colonizes the xylem of maize as sessile, cell-wall-adherent biofilms. Biofilm formation is a developmental process that generally involves some form of surface motility. For that reason, we reexamined the motility properties of P. stewartii DC283 based on the assumption that the organism requires some form of surface motility for biofilm development. Here, we show that the organism is highly motile on agar surfaces. This motility is flagella dependent, shown by the fact that a fliC mutant, impaired in flagellin subunit synthesis, is nonmotile. Motility also requires the production of stewartan exopolysaccharide. Moreover, surface motility plays a significant role in the colonization of the plant host. PMID:18785831

Herrera, Carmen M; Koutsoudis, Maria D; Wang, Xiaolei; von Bodman, Susanne B

2008-10-01

76

Black Streak of Edible Burdock Caused by Itersonilia perplexans in Japan  

Microsoft Academic Search

  Black streak disease of edible burdock (Arctium lappa L.) has been observed periodically in Hokkaido Prefecture, Japan since 1988. Symptoms appeared initially as small, dark brown\\u000a to black spots on the leaf veins and petioles. The necrotic spots developed longitudinally along the leaf veins or petioles.\\u000a Diseased leaf veins or petioles occasionally snapped off at the necrotic lesions. An Itersonilia

Harukuni HORITA; Shinji YASUOKA

2002-01-01

77

Compressible laminar streaks with wall suction  

NASA Astrophysics Data System (ADS)

The response of a compressible laminar boundary layer subject to free-stream vortical disturbances and steady mean-flow wall suction is studied. The theoretical frameworks of Leib et al. [J. Fluid Mech. 380, 169-203 (1999)] and Ricco and Wu [J. Fluid Mech. 587, 97-138 (2007)], based on the linearized unsteady boundary-region equations, are adopted to study the influence of suction on the kinematic and thermal streaks arising through the interaction between the free-stream vortical perturbations and the boundary layer. In the asymptotic limit of small spanwise wavelength compared with the boundary layer thickness, i.e., when the disturbance flow is conveniently described by the steady compressible boundary region equations, the effect of suction is mild on the velocity fluctuations and negligible on the temperature fluctuations. When the spanwise wavelength is comparable with the boundary layer thickness, small suction values intensify the supersonic streaks, while higher transpiration levels always stabilize the disturbances at all Mach numbers. At larger spanwise wavelengths, very small amplitudes of wall transpiration have a dramatic stabilizing effect on all boundary layer fluctuations, which can take the form of transiently growing thermal streaks, large amplitude streamwise oscillations, or oblique exponentially growing Tollmien-Schlichting waves, depending on the Mach number and the wavelengths. The range of wavenumbers for which the exponential growth occurs becomes narrower and the location of instability is significantly shifted downstream by mild suction, indicating that wall transpiration can be a suitable vehicle for delaying transition when the laminar breakdown is promoted by these unstable disturbances. The typical streamwise wavelength of these disturbances is instead not influenced by suction, and asymptotic triple deck theory predicts the strong changes in growth rate and the very mild modifications in streamwise wavenumber in the limit of larger downstream distance and small spanwise wavenumber.

Ricco, Pierre; Shah, Daniel; Hicks, Peter D.

2013-05-01

78

Compact optical technique for streak camera calibration  

NASA Astrophysics Data System (ADS)

To produce accurate data from optical streak cameras requires accurate temporal calibration sources. We have reproduced an older technology for generating optical timing marks that had been lost due to component availability. Many improvements have been made which allow the modern units to service a much larger need. Optical calibrators are now available that produce optical pulse trains of 780 nm wavelength light at frequencies ranging from 0.1 to 10 GHz, with individual pulse widths of approximately 25 ps full width half maximum. Future plans include the development of single units that produce multiple frequencies to cover a wide temporal range, and that are fully controllable via an RS232 interface.

Bell, Perry; Griffith, Roger; Hagans, Karla; Lerche, Richard; Allen, Curt; Davies, Terence; Janson, Frans; Justin, Ronald; Marshall, Bruce; Sweningsen, Oliver

2004-10-01

79

X-ray streak crystal spectography  

SciTech Connect

We have built an x-ray streaked crystal spectrograph for making time-resolved x-ray spectral measurements. This instrument can access Bragg angles from 11/sup 0/ to 38/sup 0/ and x-ray spectra from 200 eV to greater than 10 keV. We have demonstrated resolving powers, E/..delta..E > 200 at 1 keV and time resolution less than 20 psec. A description of the instrument and an example of the data is given.

Kauffman, R.L.; Brown, T.; Medecki, H.

1983-07-01

80

Structure-Based Computational Study of Two Disease Resistance Gene Homologues (Hm1 and Hm2) in Maize (Zea mays L.) with Implications in Plant-Pathogen Interactions  

PubMed Central

The NADPH-dependent HC-toxin reductases (HCTR1 and 2) encoded by enzymatic class of disease resistance homologous genes (Hm1 and Hm2) protect maize by detoxifying a cyclic tetrapeptide, HC-toxin, secreted by the fungus Cochliobolus carbonum race 1(CCR1). Unlike the other classes' resistance (R) genes, HCTR-mediated disease resistance is an inimitable mechanism where the avirulence (Avr) component from CCR1 is not involved in toxin degradation. In this study, we attempted to decipher cofactor (NADPH) recognition and mode of HC-toxin binding to HCTRs through molecular docking, molecular dynamics (MD) simulations and binding free energy calculation methods. The rationality and the stability of docked complexes were validated by 30-ns MD simulation. The binding free energy decomposition of enzyme-cofactor complex was calculated to find the driving force behind cofactor recognition. The overall binding free energies of HCTR1-NADPH and HCTR2-NADPH were found to be ?616.989 and ?16.9749 kJ mol?1 respectively. The binding free energy decomposition revealed that the binding of NADPH to the HCTR1 is mainly governed by van der Waals and nonpolar interactions, whereas electrostatic terms play dominant role in stabilizing the binding mode between HCTR2 and NADPH. Further, docking analysis of HC-toxin with HCTR-NADPH complexes showed a distinct mode of binding and the complexes were stabilized by a strong network of hydrogen bond and hydrophobic interactions. This study is the first in silico attempt to unravel the biophysical and biochemical basis of cofactor recognition in enzymatic class of R genes in cereal crop maize.

Maharana, Jitendra; Sahu, Jagajjit; Sen, Priyabrata; Modi, Mahendra Kumar; Choudhury, Manabendra Dutta; Barooah, Madhumita

2014-01-01

81

Wind streaks: geological and botanical effects on surface albedo contrast  

NASA Astrophysics Data System (ADS)

Two wind streaks in the eastern Mojave Desert of California were examined to gain insight into the origin of the surface brightness contrast that makes them visible, both on the ground and in remote sensing data. The two localities are: a 4-km-long dark streak oriented S43E from the Amboy cinder cone (34°32'N, 115°46'W), located on a Quaternary basalt flow covered with aeolian sand, and a 2-km-long dark streak oriented S22E from a low hill near the southwestern base of Sleeping Beauty Mountain (34°48'N, 116°20'W), located on a sand-covered alluvial surface. In both cases, the dark streaks have enhanced rock abundances on the streak surface, relative to the surroundings. At the Amboy streak, slope wash likely contributed to the rock concentration on the streak surface, shielded from burial under aeolian sand by the cinder cone. At the Sleeping Beauty streak, the relative albedo contrast is strongly emphasized by the presence of Big Galleta grass only outside of the streak. The albedo contrast of the Sleeping Beauty streak can be effectively eliminated by the seasonal presence of annual grass preferentially within the streak. Some plants may have reflectances that are strongly dependent upon viewing and illumination geometry, raising the possibility that certain terrestrial aeolian features may appear variable on a diurnal basis. Alluvial processes appear to have been important at both localities for redistributing surface materials, even given the infrequent rain conditions present in the Mojave Desert.

Zimbelman, James R.; Williams, Steven H.

1996-09-01

82

A possible scenario for the evolution of Banana streak virus in banana.  

PubMed

Outbreaks of Banana streak virus (BSV) have been recorded worldwide where Musa spp. is grown during the last 20 years with no convincing evidence of epidemics. Epidemics were previously reported in Uganda where BSV is currently endemic. BSV is a plant pararetrovirus of the family Caulimoviridae, genus Badnavirus it causes chlorosis leaf streak disease. The information currently available on banana streak disease makes it possible to identify a complex of distinct BSV species each causing the same disease. BSV exists in two states: one as an episomal form, infecting plant cells; the other as viral DNA integrated within the B genome of banana (endogenous BSV-eBSV) forming a viral genome for de novo viral particles. Both forms can be infectious in banana plants. The BSV phylogeny is polyphyletic with BSV distributed in two clades. Clade 1 clusters BSV species that occur worldwide and may have an eBSV counterpart, whereas Clade 3 only comprises BSV species from Uganda. Clearly, two distinct origins explain such BSV diversity. However, the epidemiology/outbreaks of BSV remains unclear and the role of eBSV needs to be clarified. In this review, the biodiversity of BSV is explained and discussed in the light of field and molecular epidemiology data. A scheme is proposed for the co-evolution of BSV and banana based on old or recent infection hypotheses related to African domestication sites and banana dissemination to explain the disease context. PMID:24457073

Iskra-Caruana, Marie-Line; Chabannes, Matthieu; Duroy, Pierre-Olivier; Muller, Emmanuelle

2014-06-24

83

Radar-visible wind streaks in the Altiplano of Bolivia  

NASA Technical Reports Server (NTRS)

Isolated knobs that are erosional remnants of central volcanoes or of folded rocks occur in several areas of the Altiplano are visible on both optical and images. The optically visible streaks occur in the immediate lee of the knobs, whereas the radar visible streaks occur in the zone downwind between the knobs. Aerial reconnaissance and field studies showed that the optically visible streaks consist of a series of small ( 100 m wide) barchan and barchanoid dunes, intradune sand sheets, and sand hummocks (large shrub coppice dunes) up to 15 m across and 5 m high. On LANDSAT images these features are poorly resolved but combine to form a bright streak. On the radar image, this area also appears brighter than the zone of the radar dark streak; evidently, the dunes and hummocks serve as radar reflectors. The radar dark streak consists of a relatively flat, smooth sand sheet which lacks organized aerolian bedforms, other than occasional ripples. Wind velocity profiles show a greater U value in the optically bright streak zone than in the radar dark streak.

Greeley, R.; Christensen, P.

1984-01-01

84

Integrated streak camera in standard (Bi)CMOS technology  

Microsoft Academic Search

The conventional streak camera (CSC) is an optoelectronic instrument which captures the spatial distribution versus time of a ultra high-speed luminous phenomena with a picosecond temporal resolution and a typical spatial resolution of 60 mum. This paper presents two Integrated Streak Camera (ISC) architectures called MISC (M for Matrix) and VISC (V for Vector) which replicate the functionality of a

Wilfried Uhring; Jean-Pierre Le Normand; Virginie Zint; Martin Zlatanski

2010-01-01

85

Very high long-term stability synchroscan streak camera  

Microsoft Academic Search

In this article, we present the drifts phenomena that affect the temporal resolution of a standard synchroscan streak camera and some techniques to correct them in order to enhance the long-term resolution of these cameras. First, we give a comprehensive list of the components of the synchroscan streak camera which are sensitive to temporal and thermal drift: from the trigger

Wilfried Uhring; Chantal Virginie Zint; Patrick Summ; Bernard Cunin

2003-01-01

86

Fluid dynamical implications of anastomosing slope streaks on Mars  

Microsoft Academic Search

The Mars Global Surveyor mission has imaged slope streaks, some of which have formed in periods as short as 109 days. These features are one of the most currently active surface processes on Mars. Some slope streaks have flow-like morphologic characteristics, which include anastomosing patterns influenced by small topographic barriers. In order to understand what processes gave rise to these

Hideaki Miyamoto; James M. Dohm; Ross A. Beyer; Victor R. Baker

2004-01-01

87

Mesoscale ageostrophic circulations associated with baroclinic jet streaks  

NASA Technical Reports Server (NTRS)

Studies of ageostrophic motion attending jet streaks and convection are examined. Various types of dynamical experiments are carried out with the hybrid isentropic-sigma coordinate model. The effects of vorticity and static stability distributions on the intensity of secondary circulations forced by inertial accelerations as well as the superposition of an amplifying baroclinic wave on the jet streak structure are investigated.

Johnson, D. R.

1984-01-01

88

ZmPep1, an Ortholog of Arabidopsis Elicitor Peptide 1, Regulates Maize Innate Immunity and Enhances Disease Resistance1[W][OA  

PubMed Central

ZmPep1 is a bioactive peptide encoded by a previously uncharacterized maize (Zea mays) gene, ZmPROPEP1. ZmPROPEP1 was identified by sequence similarity as an ortholog of the Arabidopsis (Arabidopsis thaliana) AtPROPEP1 gene, which encodes the precursor protein of elicitor peptide 1 (AtPep1). Together with its receptors, AtPEPR1 and AtPEPR2, AtPep1 functions to activate and amplify innate immune responses in Arabidopsis and enhances resistance to both Pythium irregulare and Pseudomonas syringae. Candidate orthologs to the AtPROPEP1 gene have been identified from a variety of crop species; however, prior to this study, activities of the respective peptides encoded by these orthologs were unknown. Expression of the ZmPROPEP1 gene is induced by fungal infection and treatment with jasmonic acid or ZmPep1. ZmPep1 activates de novo synthesis of the hormones jasmonic acid and ethylene and induces the expression of genes encoding the defense proteins endochitinase A, PR-4, PRms, and SerPIN. ZmPep1 also stimulates the expression of Benzoxazineless1, a gene required for the biosynthesis of benzoxazinoid defenses, and the accumulation of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside in leaves. To ascertain whether ZmPep1-induced defenses affect resistance, maize plants were pretreated with the peptide prior to infection with fungal pathogens. Based on cell death and lesion severity, ZmPep1 pretreatment was found to enhance resistance to both southern leaf blight and anthracnose stalk rot caused by Cochliobolis heterostrophus and Colletotrichum graminicola, respectively. We present evidence that peptides belonging to the Pep family have a conserved function across plant species as endogenous regulators of innate immunity and may have potential for enhancing disease resistance in crops.

Huffaker, Alisa; Dafoe, Nicole J.; Schmelz, Eric A.

2011-01-01

89

The study of streak camera dynamic distortion  

NASA Astrophysics Data System (ADS)

Dynamic distortion, which is caused by space-charge effect, widely exists in streak camera. When input light intensity becomes too large, the electric field caused by electric beam turns out analogous to that caused by image converter tube, which leads to the dynamic distortion. In this article, we analyze the theory of the dynamic distortion by experiments and simulations upon CST Particle Studio software. Results show that: the intensity of current and the space position along the photocathode shall affect the dynamic distortion, leading to defocusing effect and reduce both the spatial resolution and the temporal resolution. All above assist us to better understand the electric-optic system of image converter tube, and provide ideas for further experimental diagnose design.

Deng, Bo; Li, Jing; Chen, Tao; Hu, Xin; Liu, Shenye

2012-10-01

90

Virus-independent and common transcriptome responses of leafhopper vectors feeding on maize infected with semi-persistently and persistent propagatively transmitted viruses  

PubMed Central

Background Insects are the most important epidemiological factors for plant virus disease spread, with >75% of viruses being dependent on insects for transmission to new hosts. The black-faced leafhopper (Graminella nigrifrons Forbes) transmits two viruses that use different strategies for transmission: Maize chlorotic dwarf virus (MCDV) which is semi-persistently transmitted and Maize fine streak virus (MFSV) which is persistently and propagatively transmitted. To date, little is known regarding the molecular and cellular mechanisms in insects that regulate the process and efficiency of transmission, or how these mechanisms differ based on virus transmission strategy. Results RNA-Seq was used to examine transcript changes in leafhoppers after feeding on MCDV-infected, MFSV-infected and healthy maize for 4 h and 7 d. After sequencing cDNA libraries constructed from whole individuals using Illumina next generation sequencing, the Rnnotator pipeline in Galaxy was used to reassemble the G. nigrifrons transcriptome. Using differential expression analyses, we identified significant changes in transcript abundance in G. nigrifrons. In particular, transcripts implicated in the innate immune response and energy production were more highly expressed in insects fed on virus-infected maize. Leafhoppers fed on MFSV-infected maize also showed an induction of transcripts involved in hemocoel and cell-membrane linked immune responses within four hours of feeding. Patterns of transcript expression were validated for a subset of transcripts by quantitative real-time reverse transcription polymerase chain reaction using RNA samples collected from insects fed on healthy or virus-infected maize for between a 4 h and seven week period. Conclusions We expected, and found, changes in transcript expression in G. nigrifrons feeding of maize infected with a virus (MFSV) that also infects the leafhopper, including induction of immune responses in the hemocoel and at the cell membrane. The significant induction of the innate immune system in G. nigrifrons fed on a foregut-borne virus (MCDV) that does not infect leafhoppers was less expected. The changes in transcript accumulation that occur independent of the mode of pathogen transmission could be key for identifying insect factors that disrupt vector-mediated plant virus transmission.

2014-01-01

91

Attosecond streaking of correlated two-electron transitions in helium.  

PubMed

We present fully ab initio simulations of attosecond streaking for ionization of helium accompanied by shakeup of the second electron. This process represents a prototypical case for strongly correlated electron dynamics on the attosecond time scale. We show that streaking spectroscopy can provide detailed information on the Eisenbud-Wigner-Smith time delay as well as on the infrared-field dressing of both bound and continuum states. We find a novel contribution to the streaking delay that stems from the interplay of electron-electron and infrared-field interactions in the exit channel. We quantify all the contributions with attosecond precision and provide a benchmark for future experiments. PMID:22680715

Pazourek, Renate; Feist, Johannes; Nagele, Stefan; Burgdörfer, Joachim

2012-04-20

92

The formation of streak defects on anodized aluminum extrusions  

NASA Astrophysics Data System (ADS)

Streaking is a common surface defect on anodized extrusions of 6xxx series soft alloys. Very often, the defects only become apparent after anodizing, which makes it difficult to identify their root cause. In industry practice, a trial-and-error method has been taken to reduce the intensities of the streak defects, greatly increasing the fabrication cost. This paper describes the formation mechanism of various streak defects on the basis of a literature review and experimental results. This provides a basis for developing effective measures for preventing the formation of these defects for the extrusion industry.

Zhu, Hanliang; Zhang, Xinquan; Couper, Malcolm J.; Dahle, Arne K.

2010-05-01

93

The Future of Maize  

Microsoft Academic Search

In the near future, maize will continue to expand and diversify as a research model, as an industrial resource and as a crop\\u000a for feed and fuel. The generation of the first maize genome sequence, followed by great improvements in genome sequencing\\u000a technology, will allow the exceptional genetic diversity of maize to be described in multiple sequenced genomes. Maize will

Jeffrey L. Bennetzen

94

Streak camera in standard (Bi)CMOS (bipolar complementary metal-oxide-semiconductor) technology  

Microsoft Academic Search

The conventional streak camera (CSC) is an optoelectronic instrument that captures the spatial distribution as a function of time of an ultra high-speed luminous phenomenon with picosecond temporal resolution and a typical spatial resolution of several tens of micrometers. This paper presents two tubeless streak camera architectures called MISC (matrix integrated streak camera) and VISC (vector integrated streak camera), which

M. Zlatanski; W. Uhring; J. P. Le Normand; C. V. Zint; D. Mathiot

2010-01-01

95

Active Processes: Bright Streaks and Dark Fans  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] [figure removed for brevity, see original site] Figure 1Figure 2

In a region of the south pole known informally as 'Ithaca' numerous fans of dark frost form every spring. HiRISE collected a time lapse series of these images, starting at Ls = 185 and culminating at Ls = 294. 'Ls' is the way we measure time on Mars: at Ls = 180 the sun passes the equator on its way south; at Ls = 270 it reaches its maximum subsolar latitude and summer begins.

In the earliest image (figure 1) fans are dark, but small narrow bright streaks can be detected. In the next image (figure 2), acquired at Ls = 187, just 106 hours later, dramatic differences are apparent. The dark fans are larger and the bright fans are more pronounced and easily detectable. The third image in the sequence shows no bright fans at all.

We believe that the bright streaks are fine frost condensed from the gas exiting the vent. The conditions must be just right for the bright frost to condense.

Observation Geometry Image PSP_002622_0945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 16-Feb-2007. The complete image is centered at -85.2 degrees latitude, 181.5 degrees East longitude. The range to the target site was 246.9 km (154.3 miles). At this distance the image scale is 49.4 cm/pixel (with 2 x 2 binning) so objects 148 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel . The image was taken at a local Mars time of 05:46 PM and the scene is illuminated from the west with a solar incidence angle of 88 degrees, thus the sun was about 2 degrees above the horizon. At a solar longitude of 185.1 degrees, the season on Mars is Northern Autumn.

2007-01-01

96

Temporal Contrast Changes in Dark Slope Streaks on Mars  

NASA Astrophysics Data System (ADS)

Dark slope streaks on Mars are among the most active and dynamic processes observed on the planet's surface. While various formation models have been suggested [1][2][3], dust avalanches seem to best explain streak origin and characteristics[4][5]. New streaks have the highest contrast suggesting they fade over time. One theory for this is atmospheric dust fallout slowly raising the albedo of the surface exposed by the dust avalanche, progressively increasing streak albedo until the streak becomes indistinguishable from the surrounding surface. In this study, we attempt an initial evaluation of changes in streak brightness relative to surroundings with a first order correction for incidence angle[6]. CRISM images were identified for spatial overlap and temporal range, then further selected for image sets with well-matched viewing geometries. The 1 micron wavelength band was used to reduce atmospheric interference and brightness values then collected at multiple locations within and alongside individual streaks, with on-streak/off-streak pairs at points of similar elevation. Values were then divided by the cosine of the corresponding MOLA incidence angle for brightness variation correction due to topography. Measurements for overlapping images established local and overall averages for the rate of change in contrast ratio. Results showed a range of trends including streaks that darkened, brightened, brightened then darkened or vice versa. We continue to explore the possibility of non-linear brightening as well as streak reactivation and localized events, surface characteristics, and topography. Further study will focus on these and other morphological changes observed from vast data sets of other instruments including the Mars Reconnaissance Orbter HiRISE and CTX, Mars Express HRSC, Mars Odyssey THEMIS (visible), and the Mars Global Surveyor MOC. [1] Morris (1982) JGR, 87, 1164-1178. [2] Ferguson and Lucchita (1984) NASA Tech. Memo., TM-86246, 188-190. [3] Miyamoto, H. et al. (2004) JGR, 109, E06008. [4] Sullivan, R. et al. (2001) JGR, 106, 23607-23633. [5] Baratoux, N. M. et al. (2006) Icarus, 183, 30-45. [6] Brown, A. et al. (2010) JGR, 115, E00D13.

Chilton, Heather; Phillips, C. B.; Brown, A.; Fenton, L.

2013-01-01

97

Optical fiducial timing system for x-ray streak cameras  

Microsoft Academic Search

An optical fiducial timing system is provided for use with interdependent groups of x-ray streak cameras. The aluminium coated ends of optical fibers are positioned with the photocathodes of the x-ray streak cameras. The other ends of the optical fibers are placed together in a bundled array. A fiducial optical signal, that is comprised of 2..omega.. or 1..omega.. laser light,

D. G. Nilson; E. M. Campbell; B. J. MacGowan; H. Medecki

1986-01-01

98

Microprocessor-controlled wide-range streak camera  

Microsoft Academic Search

Bechtel Nevada\\/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable

Amy E. Lewis; Craig Hollabaugh

2006-01-01

99

Tobacco streak virus isolated from lettuce.  

PubMed

Tobacco streak virus (TSV) is an ilarvirus with a worldwide distribution. This virus infects many plants and causes significant yield losses. In this study, 300 samples of lettuce were collected from lettuce fields in Tehran Province. Infected plants show symptoms such as: mosaic, vein clearing, vein necrosis, yellowing and leaf distortion. DAS-ELISA (Double Antibody Sandwich-ELISA) was used with a polyclonal antiserum against TSV. Five isolates (T1, T2, T3, T4 and T5), which are collected, respectively from Mohammad Abad (Karaj), Malek Abad (Karaj), Hashtgerd (Karaj), Tarand Balla (Varamin) and Deh mah sin (Pishva) were inoculated on 29 species of Cucurbitaceae, Amaranthaceae, Solanacea, Compositae, Leguminosae and Chenopodiacea. Chenopodium quinoa 6 days after inoculation showed necrotic local lesions. Gomphrena globosa 10 days after inoculation developed chlorotic local lesions. Systemic symptoms were produced in Datura stramonium. Phaseolus vulgaris cv. Red Kidney 5 days after inoculation developed necrotic local lesions. Nicotiana tabacum 7 days after inoculation showed necrotic and chlorotic local lesions. Nicotiana clevelandii 15 days after inoculation developed leaf distortion and vein necrosis. Lactuca sativa 10-15 days after inoculation developed leaf istortion and mosaic. Reverse Transcription Polymerase Chain Reaction (RT-PCR) was performed using one primer pairs designed by DSMZ. An approximately 710 bp fragment was amplified with a specific primer. PMID:19634475

Abtahi, F S; Khodai Motlagh, M

2009-05-01

100

A Case of Intravitreal Bevacizumab Injection for the Treatment of Choroidal Neovascularization in Angioid Streaks  

PubMed Central

A 56-year-old Korean woman presented with decreased visual acuity of the right eye. She had a history of two photodynamic therapy treatments for choroidal neovascularization (CNV) due to angioid streaks in her left eye with central scarring and low visual acuity. She was diagnosed with subfoveal CNV due to angioid streaks in her right eye and treated with six intravitreal bevacizumab (1.25 mg / 0.05 mL) injections over one year. Best corrected visual acuity improved from 20 / 125 at baseline to 20 / 50 at the final visit. The area of CNV had changed into a fibrotic scar by the final visit, and fluorescein angiography and indocyanine green angiography revealed no evidence of leakage. Optical coherence tomography showed that central macular thickness decreased from 311 µm at baseline to 203 µm with complete resolution of subretinal and intraretinal fluid at the final visit. Intravitreal bevacizumab for CNV associated with angioid streaks prevented the progression of disease and resulted in the improvement of visual acuity after one year of follow-up in our patient.

Lee, Ji Woong; Shin, Jae Pil

2011-01-01

101

Time delays for attosecond streaking in photoionization of neon  

NASA Astrophysics Data System (ADS)

We revisit the time-resolved photoemission in neon atoms as probed by attosecond streaking. We calculate streaking time shifts for the emission of 2p and 2s electrons and compare the relative delay as measured in a recent experiment by Schultze et al. [Science 328, 1658 (2010), 10.1126/science.1189401]. The B-spline R-matrix method is employed to calculate accurate Eisenbud-Wigner-Smith time delays from multielectron dipole transition matrix elements for photoionization. The additional laser field-induced time shifts in the exit channel are obtained from separate, time-dependent simulations of a full streaking process by solving the time-dependent Schrödinger equation on the single-active-electron level. The resulting accurate total relative streaking time shifts between 2s and 2p emission lie well below the experimental data. We identify the presence of unresolved shake-up satellites in the experiment as a potential source of error in the determination of streaking time shifts.

Feist, Johannes; Zatsarinny, Oleg; Nagele, Stefan; Pazourek, Renate; Burgdörfer, Joachim; Guan, Xiaoxu; Bartschat, Klaus; Schneider, Barry I.

2014-03-01

102

Population genetics of duplicated disease-defense genes, hm1 and hm2, in maize (Zea mays ssp. mays L.) and its wild ancestor (Zea mays ssp. parviglumis).  

PubMed Central

Plant defense genes are subject to nonneutral evolutionary dynamics. Here we investigate the evolutionary dynamics of the duplicated defense genes hm1 and hm2 in maize and its wild ancestor Zea mays ssp. parviglumis. Both genes have been shown to confer resistance to the fungal pathogen Cochliobolus carbonum race 1, but the effectiveness of resistance differs between loci. The genes also display different population histories. The hm1 locus has the highest nucleotide diversity of any gene yet sampled in the wild ancestor of maize, and it contains a large number of indel polymorphisms. There is no evidence, however, that high diversity in hm1 is a product of nonneutral evolution. In contrast, hm2 has very low nucleotide diversity in the wild ancestor of maize. The distribution of hm2 polymorphic sites is consistent with nonneutral evolution, as indicated by Tajima's D and other neutrality tests. In addition, one hm2 haplotype is more frequent than expected under the equilibrium neutral model, suggesting hitchhiking selection. Both defense genes retain >80% of the level of genetic variation in maize relative to the wild ancestor, and this level is similar to other maize genes that were not subject to artificial selection during domestication.

Zhang, Liqing; Peek, Andrew S; Dunams, Detiger; Gaut, Brandon S

2002-01-01

103

Characteristics of an ultrafast x-ray streak camera  

SciTech Connect

The detection and temporal dispersion of the x-rays using x-ray streak cameras has been limited to a resolution of 2 ps, primarily due to the transit time dispersion of the electrons between the photocathode and the acceleration grid. The transit time spread of the electrons traveling from the photocathode to the acceleration grid is inversely proportional to the accelerating field. By increasing the field by a factor of 7, we have minimized the effects of transit time dispersion in the photocathode/accelerating grid region and produce an x-ray streak camera with sub-picosecond temporal resolution ({approximately}900 fs). The streak camera has been calibrated using a Michelson interferometer and 100 fs, 400 nm laser light. Time resolved x-ray data is shown from an aluminum target heated at 10{sup 18} W/cm{sup 2} with a 100 fs, 400 nm laser .

Shepherd, R.; Booth, R.; Price, D. [and others

1994-06-01

104

Attosecond nanoplasmonic streaking of localized fields near metal nanospheres  

NASA Astrophysics Data System (ADS)

Collective electron dynamics in plasmonic nanosystems can unfold on timescales in the attosecond regime and the direct measurement of plasmonic near-field oscillations is highly desirable. We report on numerical studies on the application of attosecond nanoplasmonic streaking spectroscopy to the measurement of collective electron dynamics in isolated Au nanospheres. The plasmonic field oscillations are induced by a few-cycle near-infrared (NIR) driving field and are mapped by the energy of photoemitted electrons using a synchronized, time-delayed attosecond extreme ultraviolet (XUV) pulse kinetic. By a detailed analysis of the amplitudes and phase shifts, we identify the different regimes of nanoplasmonic streaking and study the dependence on particle size, XUV in streaking spectrograms photoelectron energy, and emission position. The simulations indicate that the near fields around the nanoparticles can be spatiotemporally reconstructed and may give detailed insight into the build-up and decay of collective electron motion.

Süßmann, Frederik; Kling, Matthias F.

2011-09-01

105

Attosecond streaking in a nano-plasmonic field  

NASA Astrophysics Data System (ADS)

A theoretical study of the application of attosecond streaking spectroscopy to time-resolved studies of the plasmonic fields surrounding isolated, resonantly excited spherical nanoparticles is presented. A classification of the different regimes in attosecond streaking is proposed and identified in our results that are derived from Mie calculations of plasmon fields, coupled to classical electron trajectory simulations. It is shown that in an attosecond streaking experiment, the electrons are almost exclusively sensitive to the component of the field parallel to the direction in which they are detected. This allows one to probe the different components of the field individually by resolving the angle of emission of the electrons. Finally, simulations based on fields calculated by finite-difference time-domain (FDTD) are compared with the results obtained using Mie fields. The two are found to be in good agreement with each other, supporting the notion that FDTD methods can be used to reliably investigate non-spherical structures.

Kelkensberg, F.; Koenderink, A. F.; Vrakking, M. J. J.

2012-09-01

106

A time-resolved image sensor for tubeless streak cameras  

NASA Astrophysics Data System (ADS)

This paper presents a time-resolved CMOS image sensor with draining-only modulation (DOM) pixels for tube-less streak cameras. Although the conventional streak camera has high time resolution, the device requires high voltage and bulky system due to the structure with a vacuum tube. The proposed time-resolved imager with a simple optics realize a streak camera without any vacuum tubes. The proposed image sensor has DOM pixels, a delay-based pulse generator, and a readout circuitry. The delay-based pulse generator in combination with an in-pixel logic allows us to create and to provide a short gating clock to the pixel array. A prototype time-resolved CMOS image sensor with the proposed pixel is designed and implemented using 0.11um CMOS image sensor technology. The image array has 30(Vertical) x 128(Memory length) pixels with the pixel pitch of 22.4um. .

Yasutomi, Keita; Han, SangMan; Seo, Min-Woong; Takasawa, Taishi; Kagawa, Keiichiro; Kawahito, Shoji

2014-03-01

107

Fluorescence lifetime imaging microscopy using a streak camera  

NASA Astrophysics Data System (ADS)

We present the development of a fluorescence lifetime imaging microscopy system using a streak camera (SC-FLIM), which uses ultrafast infrared laser for multiphoton excitation and a streak camera for lifetime measurement. A pair of galvo mirrors are employed to accomplish quick time-resolved scanning on a line and 2D fluorescence lifetime imaging. The SC-FLIM system was calibrated using an F-P etalon and several standard fluorescent dyes, and was also used to perform fluorescence lifetime imaging of fluorescent microspheres and a prepared plant stem slide.

Liu, Lixin; Li, Yahui; Sun, Luogeng; Li, Heng; Peng, Xiao; Qu, Junle

2014-02-01

108

Wheat streak mosaic virus-Structural parameters for a Potyvirus  

SciTech Connect

Wheat streak mosaic virus is a Tritimovirus, a member of the Potyviridae family, which includes the very large Potyvirus genus. We have examined wheat streak mosaic virus by electron microscopy and fiber diffraction from partially oriented sols, and analyzed the results to estimate the symmetry and structural parameters of the viral helix. The virions have an apparent radius of 63 {+-} 5 A. The viral helix has a pitch of 33.4 A {+-} 0.6 A. There appear to be 6.9 subunits per turn of the helix, although we cannot completely eliminate values of 5.9 or 7.9 for this parameter.

Parker, Lauren [Center for Structural Biology, Vanderbilt University, Nashville, TN 37232 (United States); Kendall, Amy [Center for Structural Biology, Vanderbilt University, Nashville, TN 37232 (United States); Berger, P.H. [Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339 (United States); Shiel, P.J. [Department of Plant, Soil and Entomological Sciences, University of Idaho, Moscow, ID 83844-2339 (United States); Stubbs, Gerald [Center for Structural Biology, Vanderbilt University, Nashville, TN 37232 (United States)]. E-mail: gerald.stubbs@vanderbilt.edu

2005-09-15

109

Relationships among soilborne bean seedling diseases, Lablab purpureus L. and maize stover residue management, bean insect pests, and soil characteristics in Trans Nzoia district, Kenya  

Microsoft Academic Search

Smallholder farmers who practice continuous maize (Zea mays L.) and bean (Phaseolus vulgaris L.) cultivation in the highlands of eastern African have been introduced to new leguminous crops for soil fertility enhancement. However, little is known about the impact these crops may have on farmers’ pre-existing crop pest problems. We investigated the cumulative effects of 7 years of differential management

Beth A. Medvecky; Quirine M. Ketterings; Eric B. Nelson

2007-01-01

110

Hot streaks and phantom cooling in a turbine rotor passage. I - Separate effects  

NASA Astrophysics Data System (ADS)

Experimental documentation and analytical correlations demonstrating the effects of hot streak accumulation and phantom cooling on turbine rotor airfoil surface temperature. Test results are shown for a range of controlling variables to identify where streak accumulation and phantom cooling are most likely to be strongest. These variables include streak injection location, streak-to-free stream density ratio and coolant-to-free stream density and velocity ratios.

Roback, Richard J.; Dring, Robert P.

1992-06-01

111

Synchroscan streak camera temporal resolution improvement by phase locked loop technique  

Microsoft Academic Search

Different temporal instabilities, which degrade the temporal resolution of s a synchroscan streak camera, have been studied. Each of the 3 main components: the laser, the trigger and the streak camera, have their intrinsic instability, thus a degradation of the final temporal resolution is occurred. An internal PLL in the streak camera has been developed in order to improve the

Wilfried Uhring; Chantal Virginie Zint; Patrick Summ; Bernard Cunin

2003-01-01

112

Radial Streaks in Electron Diffraction Patterns Observation and Theory.  

National Technical Information Service (NTIS)

Electron diffraction patterns from cold-rolled aluminum and chromium specimens showed sharply defined radial streaks, rather than spots, on each Debye-Scherer ring. These patterns were obtained using only the two condenser lenses of a Siemens Elmiskop 1 a...

J. F. Nankivell M. R. Kindermann P. A. Doyle

1971-01-01

113

Reliable and repeatable characterization of optical streak cameras.  

PubMed

Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility. To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information. PMID:19044688

Charest, Michael R; Torres, Peter; Silbernagel, Christopher T; Kalantar, Daniel H

2008-10-01

114

Reliable and Repeatable Characterization of Optical Streak Cameras  

SciTech Connect

Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

Michael Charest Jr., Peter Torres III, Christopher Silbernagel, and Daniel Kalantar

2008-10-31

115

Reliable and repeatable characterization of optical streak cameras  

SciTech Connect

Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility. To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

Charest, Michael R. Jr.; Torres, Peter III; Silbernagel, Christopher T. [National Security Technologies, LLC, 161-A S. Vasco Rd., Livermore, California 94551 (United States); Kalantar, Daniel H. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94551 (United States)

2008-10-15

116

Strong Electrical Currents Leave the Primitive Streak of Chick Embryos  

Microsoft Academic Search

The electrical fields above chick embryos were explored with a vibrating probe. These fields indicate that steady currents with exit densities of the order of 100 microamperes per square centimeter leave the whole streak and return elsewhere through the epiblast. The epicenter of these strong exit currents lies near Hensen's node. They are probably pumped into the intraembryonic space by

Lionel F. Jaffe; Claudio D. Stern

1979-01-01

117

The Cause of Streaks upon Lath and Plaster Walls  

Microsoft Academic Search

IN reply to Mr. Thomas D. Cope's letter in NATURE of January 21, it may be stated that he is correct in supposing that the best explanation of the streaks on the plaster he refers to is that they are due to the hot-air molecules driving the dust particles into contact with the plaster, and the colder the plaster the

John Aitken

1915-01-01

118

Wind Tunnel Simulations of Light and Dark Streaks on Mars  

Microsoft Academic Search

Wind tunnel experiments have revealed a characteristic flow field pattern over raised-rim craters which causes distinctive zones of aeolian erosion and deposition. Comparisons of the results with Mariner 9 images of Mars show that some crater-associated dark zones result from wind erosion and that some crater-associated light streaks are depositional.

Ronald Greeley; James D. Iversen; James B. Pollack; Nancy Udovich; Bruce White

1974-01-01

119

Reliable and Repeatable Characterication of Optical Streak Cameras  

SciTech Connect

Optical streak cameras are used as primary diagnostics for a wide range of physics and laser experiments at facilities such as the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electrical components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases, the characterization data are applied to the raw data images to correct for the nonlinearities. In order to characterize an optical streak camera, a specific set of data is collected, where the response to defined inputs are recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, and temporal resolution from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

Kalantar, D; Charest, M; Torres III, P; Charest, M

2008-05-06

120

The Symptom and Genetic Diversity of Cassava Brown Streak Viruses Infecting Cassava in East Africa  

PubMed Central

The genetic and symptom diversity of six virus isolates causing cassava brown streak disease (CBSD) in the endemic (Kenya, Mozambique, and Tanzania) and the recently affected epidemic areas (Uganda) of eastern Africa was studied. Five cassava varieties; Albert, Colombian, Ebwanateraka, TMS60444 (all susceptible) and Kiroba (tolerant) were graft inoculated with each isolate. Based on a number of parameters including the severity of leaf and root symptoms, and the extent of virus transmission by grafting, the viruses were classified as either severe or relatively mild. These results were further confirmed by the mechanical inoculation of 13 herbaceous hosts in which the virulent isolates caused plant death in Nicotiana clevelandii and N. benthamiana whereas the milder isolates did not. Phylogenetic analysis of complete coat protein gene sequences of these isolates together with sequences obtained from 14 other field-collected samples from Kenya and Zanzibar, and reference sequences grouped them into two distinct clusters, representing the two species of cassava brown streak viruses. Put together, these results did not suggest the association of a hypervirulent form of the virus with the current CBSD epidemic in Uganda. Identification of the severe and milder isolates, however, has further implications for disease management and quarantine requirements.

Mohammed, I. U.; Abarshi, M. M.; Muli, B.; Hillocks, R. J.; Maruthi, M. N.

2012-01-01

121

The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits  

PubMed Central

Background: Atherosclerosis is a complex disease that is associated with a variety of etiologic factors such as hyperlipidemia and inflammation. Aloe vera (Liliaceae family) has been used traditionally as an anti-inflammatory drug. The aims of this survey were to define the beneficial effects of Aloe vera leaf gel on some of the atherosclerosis risk factors, and also fatty streak formation in hypercholesterolemic rabbits. Materials ans Methods: 32 white male rabbits were randomly divided into four experimental groups (n = 8, each). During the study, the animals had a standard diet (control group), high cholesterol diet (HC group), high cholesterol diet with Aloe vera leaf gel (3.2%v/v) (HC+ Aloe group) and Aloe vera leaf gel (Aloe group) for 30 days. Fasting blood samples were collected from all animals at the beginning and end of the study. Then total cholesterol (TC), fasting blood sugar (FBS), triglyceride (TG) and CRP were measured before and after experimental periods. By the end of the study, the aortas were removed and investigated for atherosclerosis plaque formation. Results: Significant differences were observed in TC and CRP levels of the high-cholesterol diet with Aloe vera and the high-cholesterol diet alone (p < 0.05). The formation of fatty streaks in the aorta was also significantly lower in the same animals under the influence of dietary Aloe vera(p < 0.05). The control and Aloe group did not show any evidence of atherosclerosis. No significant difference was found between the groups in TG and FBS. Conclusions: The data suggests that Aloe vera has beneficial effects on the prevention of fatty streak development; it may reduce the development of atherosclerosis through modification of risk factors. However, further studies are needed to understand the mechanisms whereby this plant exerts its anti-atherosclerotic effects.

Dana, Nasim; Javanmard, Shaghayegh Haghjooy; Asgary, Sedigheh; Asnaashari, Hossein; Abdian, Narges

2012-01-01

122

Evaluation of the DipStreak, a New Device with an Original Streaking Mechanism for Detection, Counting, and Presumptive Identification of Urinary Tract Pathogens  

Microsoft Academic Search

DipStreak is a new urine culture device with two types of agar attached back-to-back on a plastic paddle. It combines dip-slide technology and an original streaking inoculation mechanism, allowing for bacterial count- ing and colony isolation. The performance of the DipStreak device with two different medium formulations, CHROMagar and MacConkey media in study A and UriSelect 3 and MacConkey media

Claudio Scarparo; Paola Piccoli; Paolo Ricordi; Mariuccia Scagnelli

2002-01-01

123

Simultaneous detection and differentiation of Rice black streaked dwarf virus (RBSDV) and Southern rice black streaked dwarf virus (SRBSDV) by duplex real time RT-PCR  

PubMed Central

Background The diseases caused by Rice black streaked dwarf virus (RBSDV) and Southern rice black streaked dwarf virus (SRBSDV) have been occurring epidemically in China and southeastern Asia in recent years. A sensitive, reliable and quantitative method is required to detect and distinguish for RBSDV and SRBSDV in rice and vector insects. Results We developed a sensitive and lineage-specific duplex real time RT-qPCR for detection of RBSDV and SRBSDV in a single or/and double infection in rice samples. The duplex RT-qPCR was optimized using standard samples transcribed by T7 Large Scale RNA Production System in vitro. We developed a reliable system for duplex RT-qPCR, in which its co-efficiency of RBSDV and SRBSDV, were 91.6% and 90.7%, respectively. The coefficient of determination was more than 0.990; the slope of linear equation was ?3.542, and ?3.567, respectively. Out of 30 samples collected in North and Central China, which were suspected to be infected with these two viruses, 10 samples were detected RBSDV positive by RT-PCR and 12 samples by RT-qPCR. No mixed infections were found. Simultaneously, out of total 60 samples collected from Southern China, which were also suspected to be infected with these two viruses, 41 samples were determined SRBSDV positive by RT-PCR and 47 samples by RT-qPCR. Also in this case no mixed infections were found. The rice genes eEF-1a and UBQ5 were selected as internal controls for quantification assay also performed as good expression stability. Conclusion The duplex RT-qPCR assay provided as a sufficiently sensitive, specific, accurate, reproducible and rapid tool for the detection and differentiation of RBSDV and SRBSDV. The RT-qPCR assay can be used in routine diagnostic of these two viruses in order to study the disease epidemiology in rice crops.

2013-01-01

124

Global maize trade and food security: implications from a social network model.  

PubMed

In this study, we developed a social network model of the global trade of maize: one of the most important food, feed, and industrial crops worldwide, and critical to food security. We used this model to analyze patterns of maize trade among nations, and to determine where vulnerabilities in food security might arise if maize availability was decreased due to factors such as diversion to nonfood uses, climatic factors, or plant diseases. Using data on imports and exports from the U.N. Commodity Trade Statistics Database for each year from 2000 to 2009 inclusive, we summarized statistics on volumes of maize trade between pairs of nations for 217 nations. There is evidence of market segregation among clusters of nations; with three prominent clusters representing Europe, Brazil and Argentina, and the United States. The United States is by far the largest exporter of maize worldwide, whereas Japan and the Republic of Korea are the largest maize importers. In particular, the star-shaped cluster of the network that represents U.S. maize trade to other nations indicates the potential for food security risks because of the lack of trade these other nations conduct with other maize exporters. If a scenario arose in which U.S. maize could not be exported in as large quantities, maize supplies in many nations could be jeopardized. We discuss this in the context of recent maize ethanol production and its attendant impacts on food prices elsewhere worldwide. PMID:23656551

Wu, Felicia; Guclu, Hasan

2013-12-01

125

Streak cameras for soft x-ray and optical radiation  

SciTech Connect

The principal component of a streak camera is the image converter tube. A slit-shaped photocathode transforms the radiation into a proportional emission of electrons. An electron - optics arrangement accelerates the electrons and projects them into a phosphor screen creating the image of the slit. A pair of deflection plates deflects the electronic beam along a direction perpendicular to the main dimension of the slit. Different portions of the phosphor screen show the instantaneous image of the slit with brightness proportional to the number of emitted electrons and, consequently, to the intensity of the radiation. For our x-ray streak cameras, we use the RCA C73435A image conventer tube intended for the measurement of the radiation of light and modified to have an x-ray sensitive photocathode. Practical considerations lead to the use of transparent rather than reflecting photocathodes. Several of these camera tubes are briefly described.

Medecki, H.

1983-09-01

126

Streaked x-ray microscopy of laser-fusion targets  

SciTech Connect

An ultrafast soft x-ray streak camera has been coupled to a Wolter axisymmetric x-ray microscope. This system was used to observe the dynamics of laser fusion targets both in self emission and backlit by laser produced x-ray sources. Spatial resolution was 7 ..mu..m and temporal resolution was 20 ps. Data is presented showing the ablative acceleration of foils to velocities near 10/sup 7/ cm/sec and the collision of an accelerated foil with a second foil, observed using 3 keV streaked x-ray backlighting. Good agreement was found between hydrocode simulations, simple models of the ablative acceleration and the observed velocities of the carbon foils.

Price, R.H.; Campbell, E.M.; Rosen, M.D.; Auerbach, J.M.; Phillion, D.W.; Whitlock, R.R.; Obenshain, S.P.; McLean, E.A.; Ripin, B.H.

1982-08-01

127

Megahertz streak-mode Fourier domain optical coherence tomography  

PubMed Central

Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz resonant scanner as the streak scanner, 1,016,000 A-scans have been obtained in 1 s. This method's effectiveness has been demonstrated by recording in vivo OCT-image sequences of embryonic chick hearts at 1000 frames/s. In addition, 2-megahertz OCT data have been obtained with another high speed camera.

Wang, Rui; Yun, Julie X.; Yuan, Xiaocong; Goodwin, Richard; Markwald, Roger R.; Gao, Bruce Z.

2011-01-01

128

Streak Camera: A Multidetector for Diffuse Optical Tomography  

Microsoft Academic Search

We describe an experimental setup for time-resolved diffuse optical tomography that uses a seven-channel light guide to transmit scattered light to a streak camera. This setup permits the simultaneous measurement of the time profiles of photons reemitted at different boundary sites of the objects studied. The instrument, its main specifications, and detector-specific data analysis before image reconstruction are described. The

C. Virginie Zint; Wilfried Uhring; Murielle Torregrossa; Bernard Cunin; Patrick Poulet

2003-01-01

129

Detection of episomal banana streak badnavirus by IC-PCR  

Microsoft Academic Search

A polymerase chain reaction (PCR) based strategy to detect episomal banana streak badnavirus (BSV) in banana and plantain plants that carry integrated BSV sequences was developed. Antisera used in immuno-capture polymerase chain reaction (IC-PCR) are capable of binding a large number of BSV serotypes. The primers used for PCR are capable of annealing to and amplifying across the aspartic protease-reverse

Glyn Harper; Ganesh Dahal; George Thottappilly; R. Hull

1999-01-01

130

Attosecond nanoplasmonic streaking of localized fields near metal nanospheres  

Microsoft Academic Search

Collective electron dynamics in plasmonic nanosystems can unfold on timescales in the attosecond regime and the direct measurement of plasmonic near-field oscillations is highly desirable. We report on numerical studies on the application of attosecond nanoplasmonic streaking spectroscopy to the measurement of collective electron dynamics in isolated Au nanospheres. The plasmonic field oscillations are induced by a few-cycle near-infrared (NIR)

Frederik Süßmann; Matthias F. Kling

2011-01-01

131

Streaked horned lark Eremophila  alpestris  strigata has distinct mitochondrial DNA  

Microsoft Academic Search

The Streaked Horned Lark (STHL; Eremophila  alpestris  strigata) is a federal candidate for listing under the Endangered Species Act. We evaluated the conservation status and level of genetic\\u000a diversity of the STHL using the complete mitochondrial ND2 gene. We sampled 32 STHLs from the southern Puget Sound region,\\u000a the Pacific coast, and Whites Island in the Columbia River of Washington,

Sergei V. Drovetski; Scott F. Pearson

2005-01-01

132

Reliable and Repeatable Characterization of Optical Streak Cameras  

SciTech Connect

Optical streak cameras are used as primary diagnostics for a wide range of physics and laser performance verification experiments at the National Ignition Facility (NIF). To meet the strict accuracy requirements needed for these experiments, the systematic nonlinearities of the streak cameras (attributed to nonlinearities in the optical and electronic components that make up the streak camera system) must be characterized. In some cases the characterization information is used as a guide to help determine how experiment data should be taken. In other cases the characterization data is used to “correct” data images, to remove some of the nonlinearities. In order to obtain these camera characterizations, a specific data set is collected where the response to specific known inputs is recorded. A set of analysis software routines has been developed to extract information such as spatial resolution, dynamic range, temporal resolution, etc., from this data set. The routines are highly automated, requiring very little user input and thus provide very reliable and repeatable results that are not subject to interpretation. An emphasis on quality control has been placed on these routines due to the high importance of the camera characterization information.

Michael R. Charest, Peter Torres III, Christopher Silbernagel

2008-03-01

133

Missed Diagnostic Opportunities of Streak Camera Imaging in Tokamaks  

NASA Astrophysics Data System (ADS)

The streak camera imaging of tokamak plasmas is shown to provide diagnostic opportunities based on the existence of a long-lived (i.e., identifiable during time period comparable with slow MHD times, e.g., with the period of plasma toroidal rotation) fine structure of filaments (of luminosity) in plasmas. The skeletal structure of such filaments have been found [1] in visible light images taken with a streak camera in former experiments in tokamaks TM-2, T-4, T-6, with effective time resolution one microsecond. The above phenomenon enables us to suggest a new method of streak camera imaging which allows the determination of time evolution of direction and magnitude of rotation velocity of these structures. This exploits the «blurring» of bright spots (within these filaments) in toroidal and poloidal directions, for a wide enough slit. The above determination in a single discharge requires a special optical scheme and preliminary optimization, trying only few discharges, of the time-dependent velocity of pulling the exposed film (or its electronic analog). The examples are presented of evaluating the velocities from the data from tokamak T-6 experiments in the ordinary scheme which requires trying many discharges to optimize the imaging. [1] Proc. 27th EPS PPCF, Budapest, 2000 (http://sgi30.rmki.kfki.hu/EPS2000/P2_029.pdf).

Rantsev-Kartinov, Valentin A.

2002-11-01

134

Design of microcontroller based system for automation of streak camera.  

PubMed

A microcontroller based system has been developed for automation of the S-20 optical streak camera, which is used as a diagnostic tool to measure ultrafast light phenomenon. An 8 bit MCS family microcontroller is employed to generate all control signals for the streak camera. All biasing voltages required for various electrodes of the tubes are generated using dc-to-dc converters. A high voltage ramp signal is generated through a step generator unit followed by an integrator circuit and is applied to the camera's deflecting plates. The slope of the ramp can be changed by varying values of the capacitor and inductor. A programmable digital delay generator has been developed for synchronization of ramp signal with the optical signal. An independent hardwired interlock circuit has been developed for machine safety. A LABVIEW based graphical user interface has been developed which enables the user to program the settings of the camera and capture the image. The image is displayed with intensity profiles along horizontal and vertical axes. The streak camera was calibrated using nanosecond and femtosecond lasers. PMID:20815627

Joshi, M J; Upadhyay, J; Deshpande, P P; Sharma, M L; Navathe, C P

2010-08-01

135

Streak artifact reduction in cardiac cone beam CT  

NASA Astrophysics Data System (ADS)

Cone beam reconstructed cardiac CT images suffer from characteristic streak artifacts that affect the quality of coronary artery imaging. These artifacts arise from inhomogeneous distribution of noise. While in non-tagged reconstruction inhomogeneity of noise distribution is mainly due to anisotropy of the attenuation of the scanned object (e.g. shoulders), in cardiac imaging it is largely influenced by the non-uniform distribution of the acquired data used for reconstructing the heart at a given phase. We use a cardiac adaptive filter to reduce these streaks. In difference to previous methods of adaptive filtering that locally smooth data points on the basis of their attenuation values, our filter is applied as a function of the noise distribution of the data as it is used in the phase selective reconstruction. We have reconstructed trans-axial images without adaptive filtering, with a regular adaptive filter and with the cardiac adaptive filter. With the cardiac adaptive filter significant reduction of streaks is achieved, and thus image quality is improved. The coronary vessel is much more pronounced in the cardiac adaptive filtered images, in slab MIP the main coronary artery branches are more visible, and non-calcified plaque is better differentiated from vessel wall. This improvement is accomplished without altering significantly the border definition of calcified plaques.

Shechter, Gilad; Naveh, Galit; Lessick, Jonathan; Altman, Ami

2005-04-01

136

Streak camera based SLR receiver for two color atmospheric measurements  

NASA Astrophysics Data System (ADS)

To realize accurate two-color differential measurements, an image digitizing system with variable spatial resolution was designed, built, and integrated to a photon-counting picosecond streak camera, yielding a temporal scan resolution better than 300 femtosecond/pixel. The streak camera is configured to operate with 3 spatial channels; two of these support green (532 nm) and uv (355 nm) while the third accommodates reference pulses (764 nm) for real-time calibration. Critical parameters affecting differential timing accuracy such as pulse width and shape, number of received photons, streak camera/imaging system nonlinearities, dynamic range, and noise characteristics were investigated to optimize the system for accurate differential delay measurements. The streak camera output image consists of three image fields, each field is 1024 pixels along the time axis and 16 pixels across the spatial axis. Each of the image fields may be independently positioned across the spatial axis. Two of the image fields are used for the two wavelengths used in the experiment; the third window measures the temporal separation of a pair of diode laser pulses which verify the streak camera sweep speed for each data frame. The sum of the 16 pixel intensities across each of the 1024 temporal positions for the three data windows is used to extract the three waveforms. The waveform data is processed using an iterative three-point running average filter (10 to 30 iterations are used) to remove high-frequency structure. The pulse pair separations are determined using the half-max and centroid type analysis. Rigorous experimental verification has demonstrated that this simplified process provides the best measurement accuracy. To calibrate the receiver system sweep, two laser pulses with precisely known temporal separation are scanned along the full length of the sweep axis. The experimental measurements are then modeled using polynomial regression to obtain a best fit to the data. Data aggregation using normal point approach has provided accurate data fitting techniques and is found to be much more convenient than using the full rate single shot data. The systematic errors from this model have been found to be less than 3 ps for normal points.

Varghese, Thomas K.; Clarke, Christopher; Oldham, Thomas; Selden, Michael

1993-06-01

137

Warm streaks in the U.S. temperature record: What are the chances?  

NASA Astrophysics Data System (ADS)

A recent observation in NOAA's National Climatic Data Center's monthly assessment of the state of the climate was that contiguous U.S. average monthly temperatures were in the top third of monthly ranked historical temperatures for 13 straight months from June 2011 to June 2012. The chance of such a streak occurring randomly was quoted as (1/3)13, or about one in 1.6 million. The streak continued for three more months before the October 2012 value dropped below the upper tercile. The climate system displays a degree of persistence that increases this probability relative to the assumption of independence. This paper puts forth different statistical techniques that more accurately quantify the probability of this and other such streaks. We consider how much more likely streaks are when an underlying warming trend is accounted for in the record, the chance of streaks occurring anywhere in the record, and the distribution of the record's longest streak.

Craigmile, Peter F.; Guttorp, Peter; Lund, Robert; Smith, Richard L.; Thorne, Peter W.; Arndt, Derek

2014-05-01

138

On the nature and visibility of crater-associated streaks on Mars  

NASA Technical Reports Server (NTRS)

The paper considers Mariner 9 and Viking data that contradict Kuzmin's (1975) hypothesis that all crater-associated wind streaks on Mars are depositional and consist of unresolved barchan-like dunes. According to Kuzmin's hypothesis, any streak can appear either bright or dark relative to its surroundings depending on the sun's position. The spacecraft images, however, show examples of dark and light streaks visible at the same azimuth angle of the sun. Evidence that bright and dark streaks differ both in morphology and in character is considered. It is suggested that the common ragged dark streaks are probably erosion scars while most bright streaks probably represent accumulations of bright dust-storm fallout.

Veverka, J.; Thomas, P.; Sagan, C.

1978-01-01

139

Hot streaks and phantom cooling in a turbine rotor passage. II - Combined effects and analytical modelling  

NASA Astrophysics Data System (ADS)

Experimental documentation and analytical correlations demonstrating the effects of hot streak accumulation and phantom cooling on turbine rotor airfoil surface temperature are presented. Results are shown which quantify the impact of a nonuniform temperature profile at the entrance of a turbine due to combustor-generated hot and cold streaks, and cooling air discharged from the trailing edge of the upstream stator. Experimental results are shown for a range of controlling variables to identify where streak accumulation and phantom cooling were most likely to be strongest. These variables include streak-to-free stream density ratio, streak injection location, and coolant-to-free stream density and velocity ratios. Experimental results are shown for the combined effects of hot streak and stator coolant on the adiabatic recovery temperature of the rotor.

Roback, Richard J.; Dring, Robert P.

1992-06-01

140

Density-driven spontaneous streak segregation patterns in a thin rotating drum  

NASA Astrophysics Data System (ADS)

Granular mixtures may segregate because of external driving forces, which play an important role in industry and geophysics. We investigate experimentally the mechanism of density-driven spontaneous streak segregation patterns in a thin rotating drum. We find that a spontaneous streak segregation pattern can occur in such a system, which we call a D-system. A phase diagram identifies three segregation pattern regimes in this study: the mixing regime, the core segregation regime, and the streak segregation regime.

Liao, C. C.; Hsiau, S. S.; Nien, H. C.

2014-06-01

141

Development of picosecond time resolution optical and X-ray streak cameras  

Microsoft Academic Search

We describe the development of an optical and an X-ray streak camera with picosecond time resolution. The entire peripheral\\u000a electronics and testing systems have been developed indigenously. Both the streak cameras provide ? 15 mm\\/1 ns streak rate\\u000a with a sweep voltage of ? 1 kV amplitude and rise time of 1 ns. The time and spatial resolution of the

V N Rai; M Shukla; H C Pant; D D Bhawalkar

1995-01-01

142

Surface properties of the Pettit wind streak on Mars Implications for sediment transport  

NASA Astrophysics Data System (ADS)

Satellite imagery of the Pettit streak on Amazonis Planitia are discussed in terms of the details of wind streaks and their associated sediments. Increasingly more detailed blow-ups of the available imagery demonstrate that the Pettit streak holds both a Type I bright streak (at the crater rim) and a Type II dark streak beginning at the dark patch within the crater. The lowest albedos measured, 0.20-0.22, are associated with the highest thermal inertia, indicative of grain diameters similar to medium sand, i.e., ranging from 250-350 microns. The brightest portions of the streak have albedos over 0.26 and a low thermal inertia, in the range 3-4, which implies the presence of fine-grained sand, diameters from 50-100 microns. The particle grains are less than 50 microns diameter in the surrounding plains, which have an approximately uniform albedo (0.27) and a thermal inertia of 2.5, characteristics typical of silt or clay. Current streak models describe the dark streak well, but do not account for the bright streak, which may be optically thick patches of very fine dust.

Zimbelman, J. R.

1986-04-01

143

Surface properties of the Pettit wind streak on Mars Implications for sediment transport  

NASA Technical Reports Server (NTRS)

Satellite imagery of the Pettit streak on Amazonis Planitia are discussed in terms of the details of wind streaks and their associated sediments. Increasingly more detailed blow-ups of the available imagery demonstrate that the Pettit streak holds both a Type I bright streak (at the crater rim) and a Type II dark streak beginning at the dark patch within the crater. The lowest albedos measured, 0.20-0.22, are associated with the highest thermal inertia, indicative of grain diameters similar to medium sand, i.e., ranging from 250-350 microns. The brightest portions of the streak have albedos over 0.26 and a low thermal inertia, in the range 3-4, which implies the presence of fine-grained sand, diameters from 50-100 microns. The particle grains are less than 50 microns diameter in the surrounding plains, which have an approximately uniform albedo (0.27) and a thermal inertia of 2.5, characteristics typical of silt or clay. Current streak models describe the dark streak well, but do not account for the bright streak, which may be optically thick patches of very fine dust.

Zimbelman, J. R.

1986-01-01

144

Attosecond-streaking time delays: Finite-range property and comparison of classical and quantum approaches  

NASA Astrophysics Data System (ADS)

We theoretically study time delays obtained using the attosecond-streaking technique. To this end, we compute time delays by numerically solving the corresponding time-dependent Schrödinger equation and analyze the delays using two classical methods, namely, a perturbative approach and a full numerical solution of Newton's equation describing the motion of the photoelectron in the continuum. A good agreement between the quantum streaking results and those from the full classical solution is found. This indicates that the streaking time delay arises from the continuum dynamics of the electron in the coupled potential of the Coulomb and streaking fields, while the transition of the photoelectron from the bound state to the continuum occurs instantaneously upon absorption of the photon. We further analyze the variation of the time delay with respect to the delay between the ionizing XUV pulse and a long streaking pulse, its dependence on the polarization direction of the streaking pulse, and the influence of the shape of the streaking pulse and/or additional static electric fields on the numerically obtained time delays. The results are interpreted based on the previously revealed property that the attosecond-streaking time delay depends on the finite region in space over which the electron propagates between its instant of transition into the continuum and the end of the streaking pulse.

Su, Jing; Ni, Hongcheng; Becker, Andreas; Jaro?-Becker, Agnieszka

2014-01-01

145

Defrosting Polar Dunes--Dark Spots and Wind Streaks  

NASA Technical Reports Server (NTRS)

The first time that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC)team saw dark spots on defrosting dune surfaces was in August and September of 1998. At that time, it was the north polar seasonal frost cap that was subliming away (more recent images from 1999 have shown the south polar frosts). This picture (above) shows a small portion of the giant dune field that surrounds the north polar region, as it appeared on August 23, 1998. At the time, it was early northern spring and the dunes were still covered with winter frost.

Dark spots had appeared on the north polar dunes, and many of them exhibited a radial or semi-radial pattern of dark streaks and streamers. At first, there was speculation that the streaks indicated that the defrosting process might somehow involve explosions! The dark spots seemed to resemble small craters with dark, radial ejecta. It seemed possible that frozen carbon dioxide trapped beneath water ice might somehow heat up, turn to gas, expand, and then 'explode' in either a small blast or at least a 'puff' of air similar to that which comes from the blowhole of a surfacing whale or seal.

The image shown here changed the earlier impression. The dark spots and streaks do not result from explosions. The spots--though not well understood--represent the earliest stages of defrosting on the sand dunes. The streaks, instead of being caused by small explosions, are instead the result of wind. In this picture, the fine, dark streaks show essentially identical orientations from spot to spot (e.g., compare the spots seen in boxes (a) and (b)). Each ray of dark material must result from wind blowing from a particular direction--for example, all of the spots in this picture exhibit a ray that points toward the upper left corner of the image, and each of these rays indicates the same wind regime. Each spot also has a ray pointing toward the lower right and top/upper-right. These, too, must indicate periods when the wind was strong enough to move materials, consistently, in only one direction.

The sand that makes up the north polar dunes is dark. Each spot and streak is composed of the dune sand. The bright surfaces are all covered with frost. This picture is located near 76.9oN, 271.2oW, in the north polar sand sea. Illumination is from the lower left. The 200 meter scale also indicates a distance of 656 feet.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

146

Evaluation of the DipStreak, a New Device with an Original Streaking Mechanism for Detection, Counting, and Presumptive Identification of Urinary Tract Pathogens  

PubMed Central

DipStreak is a new urine culture device with two types of agar attached back-to-back on a plastic paddle. It combines dip-slide technology and an original streaking inoculation mechanism, allowing for bacterial counting and colony isolation. The performance of the DipStreak device with two different medium formulations, CHROMagar and MacConkey media in study A and UriSelect 3 and MacConkey media in study B, was evaluated and compared to that of the reference streak method by using plates of cystine-lactose-electrolyte-deficient (CLED) agar, tryptic soy agar with 5% sheep blood, and UriSelect 3 medium. In study A, 2,000 urine specimens were processed and 511 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave the same detection rate, 99.7%. For the direct identification of Escherichia coli, Proteus mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 97 and 93.4%, respectively. In study B, 3,000 urine specimens were processed and 714 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave detection rates of 99.4, 99.9, and 99.2%, respectively. For the direct identification of E. coli, P. mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 88 and 94.4%, respectively. In conclusion, the DipStreak device with both medium formulations represents an attractive and excellent screening method for the reliable detection, counting, and presumptive identification of urinary tract pathogens. It enables bedside urine inoculation and provides a valid means of transporting the sample back to the laboratory, decreasing drastically the rate of false-positive results due to bacterial overgrowth and reducing associated costs.

Scarparo, Claudio; Piccoli, Paola; Ricordi, Paolo; Scagnelli, Mariuccia

2002-01-01

147

Quality Protein Maize for Africa: Closing the Protein Inadequacy Gap in Vulnerable Populations12  

PubMed Central

Africa shares a unique relationship with maize (Zea mays). After its introduction from New World explorers, maize was quickly adopted as the cornerstone of local cuisine, especially in sub-Saharan countries. Although maize provides macro- and micronutrients required for humans, it lacks adequate amounts of the essential amino acids lysine and tryptophan. For those consuming >50% of their daily energy from maize, pandemic protein malnutrition may exist. Severe protein and energy malnutrition increases susceptibility to life-threatening diseases such as tuberculosis and gastroenteritis. A nutritionally superior maize cultivar named quality protein maize (QPM) represents nearly one-half century of research dedicated to malnutrition eradication. Compared with traditional maize types, QPM has twice the amount of lysine and tryptophan, as well as protein bioavailability that rivals milk casein. Animal and human studies suggest that substituting QPM for common maize results in improved health. However, QPM’s practical contribution to maize-subsisting populations remains unresolved. Herein, total protein and essential amino acid requirements recommended by the WHO and the Institute of Medicine were applied to estimate QPM target intake levels for young children and adults, and these were compared with mean daily maize intakes by African country. The comparisons revealed that ?100 g QPM is required for children to maintain adequacy of lysine, the most limiting amino acid, and nearly 500 g is required for adults. This represents a 40% reduction in maize intake relative to common maize to meet protein requirements. The importance of maize in Africa underlines the potential for QPM to assist in closing the protein inadequacy gap.

Nuss, Emily T.; Tanumihardjo, Sherry A.

2011-01-01

148

Streaked radiography measurements of convergent ablator performance (invited)  

SciTech Connect

The velocity and remaining ablator mass of an imploding capsule are critical metrics for assessing the progress toward ignition of an inertially confined fusion experiment. These and other ablator rocket parameters have been measured using a single streaked x-ray radiograph. A regularization technique has been used to determine the ablator density profile {rho}(r) at each time step; moments of {rho}(r) then provide the areal density, average radius, and mass of the unablated, or remaining, ablator material, with the velocity determined from the time derivative of the average radius. The technique has been implemented on experiments at the OMEGA laser facility.

Hicks, D. G. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Spears, B. K.; Braun, D. G.; Olson, R. E.; Sorce, C. M.; Celliers, P. M.; Collins, G. W.; Landen, O. L. [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States)

2010-10-15

149

Picotron 100 streak tubes as a 150-channel photometer  

SciTech Connect

The characterization of a streak camera based upon Picotron 100 tube types is given. Both a large (30 cm 1 x 10 cm dia.) and a small (18 cm 1 x 5 cm dia.) version of this design has been tested. Over 150 channels of information are simultaneously time resolved with system S.N.R. of 3 at 100 picosecond time resolution without post intensification. Absolute photometric evaluation is given in the dynamic mode, i.e. while operating in the picosecond time domain. Such quantitative data has been lacking in the past, particularly for multiple channel applications.

Majumdar, S.; Weiss, P.B.; Black, J.P.

1982-01-01

150

Streaks of Aftershocks Following the 2004 Sumatra-Andaman Earthquake  

NASA Astrophysics Data System (ADS)

Five years after the devastating 26 December, 2004 M 9.3 Sumatra-Andaman earthquake, regional and global seismic networks have recorded tens of thousands of aftershocks. We use bulletin data from the International Seismological Centre (ISC) and the National Earthquake Information Center (NEIC), and waveforms from IRIS, to relocate more than 20,000 hypocenters between 1964 and 2008 using teleseimic cross-correlation and double-difference methods. Relative location uncertainties of a few km or less allow for detailed analysis of the seismogenic faults activated as a result of the massive stress changes associated with the mega-thrust event. We focus our interest on an area of intense aftershock activity off-shore Banda Aceh in northern Sumatra, where the relocated epicenters reveal a pattern of northeast oriented streaks. The two most prominent streaks are ~70 km long with widths of only a few km. Some sections of the streaks are formed by what appear to be small, NNE striking sub-streaks. Hypocenter depths indicate that the events locate both on the plate interface and in the overriding Sunda plate, within a ~20 km wide band overlying the plate interface. Events on the plate interface indicate that the slab dip changes from ~20° to ~30° at around 50 km depth. Locations of the larger events in the overriding plate indicate an extension of the steeper dipping mega thrust fault to the surface, imaging what appears to be a major splay fault that reaches the surface somewhere near the western edge of the Aceh basin. Additional secondary splay faults, which branch off the plate interface at shallower depths, may explain the diffuse distribution of smaller events in the overriding plate, although their relative locations are less well constrained. Focal mechanisms support the relocation results. They show a narrowing range of fault dips with increasing distance from the trench. Specifically, they show reverse faulting on ~30° dipping faults above the shallow (20°) dipping plate interface. The observation of active splay faults associated with the mega thrust event is consistent with co- and post-seismic motion data, and may have significant implications on the generation and size of the tsunami that caused 300,000 deaths.

Waldhauser, F.; Schaff, D. P.; Engdahl, E. R.; Diehl, T.

2009-12-01

151

Microprocessor-controlled wide-range streak camera  

NASA Astrophysics Data System (ADS)

Bechtel Nevada/NSTec recently announced deployment of their fifth generation streak camera. This camera incorporates many advanced features beyond those currently available for streak cameras. The arc-resistant driver includes a trigger lockout mechanism, actively monitors input trigger levels, and incorporates a high-voltage fault interrupter for user safety and tube protection. The camera is completely modular and may deflect over a variable full-sweep time of 15 nanoseconds to 500 microseconds. The camera design is compatible with both large- and small-format commercial tubes from several vendors. The embedded microprocessor offers Ethernet connectivity, and XML [extensible markup language]-based configuration management with non-volatile parameter storage using flash-based storage media. The camera's user interface is platform-independent (Microsoft Windows, Unix, Linux, Macintosh OSX) and is accessible using an AJAX [asynchronous Javascript and XML]-equipped modem browser, such as Internet Explorer 6, Firefox, or Safari. User interface operation requires no installation of client software or browser plug-in technology. Automation software can also access the camera configuration and control using HTTP [hypertext transfer protocol]. The software architecture supports multiple-simultaneous clients, multiple cameras, and multiple module access with a standard browser. The entire user interface can be customized.

Lewis, Amy E.; Hollabaugh, Craig

2006-09-01

152

Development and use of three monoclonal antibodies for the detection of rice black-streaked dwarf virus in field plants and planthopper vectors  

PubMed Central

Background Rice black-streaked dwarf virus (RBSDV) causes great losses in rice, maize and wheat production in Asian countries. The use of serological methods for RBSDV detection depends on the availability of antibodies. In this study, three highly sensitive and specific murine monoclonal antibodies (MAbs) against RBSDV antigens were produced using crude extracts from tumors of RBSDV-infected maize as the immunogen, and two serological assays, antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and dot enzyme-linked immunosorbent assay (dot-ELISA) were developed for RBSDV detection. Results All three MAbs reacted strongly and specifically with the crude extracts from RBSDV-infected plant and planthopper tissues. The detection endpoints of three MAbs (12E10, 18F10 and 5G5) in ACP-ELISA were respectively 1:40,960, 1:40,960, 1:81,920 (w/v, g?mL-1) with the crude extract of infected maize, 1:10,240, 1:20,480, 1:20,480 (w/v, g?mL-1) with the crude extract of infected rice, 1:5,120, 1:10,240, 1:10,240 (w/v, g?mL-1) with the crude extract of infected wheat, 1:9,600, 1:9,600, 19,200 (individual planthopper/?L) with the crude extract of infected planthopper. The newly developed ACP-ELISA could detect the virus in the infected maize, wheat, rice tissue crude extracts diluted at 1:81,920, 1:20,480, 1:10,240 (w/v, g?mL-1), respectively, and in individual viruliferous planthopper extract diluted at 1:19200 (individual planthopper/?L). The dot-ELISA was proved to detect the virus in the infected maize, wheat and rice tissue crude extracts diluted at 1:320 (w/v, g?mL-1), and in individual viruliferous planthopper extract diluted at 1:1,600 (individual planthopper/?L), respectively. Field plants (915) and planthopper samples (594) from five provinces of China were screened for the presence of RBSDV using the two developed serological assays. The results indicated that 338 of the 915 plant samples and 19 of the 594 planthopper samples were infected by RBSDV. Conclusions The newly developed ACP-ELISA and dot-ELISA were highly sensitive and specific to detect RBSDV in field plant and planthopper samples. The field survey demonstrated that RBSDV is widespread in rice, maize and wheat crops in Jiangsu, Zhejiang, Shandong provinces of China.

2013-01-01

153

Performances of a solid streak camera in standard CMOS technology with nanosecond time resolution  

Microsoft Academic Search

The classical streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. The FAst MOS Imager (FAMOSI) project consists in reproducing completely this streak camera functionality with a single CMOS chip. The advantages of on-chip functionalities lead to a power reduction, a lower cost and miniaturization. In this paper, we show the capabilities of a prototype fabricated in

Frédéric Morel; Chantal-Virginie Zint; Wilfried Uhring; Jean-Pierre Le Normand

2008-01-01

154

Effects of Variations in the Photocathode Voltages of Electronic Streak Cameras.  

National Technical Information Service (NTIS)

Electronic streak cameras are used to record subnanosecond data at the Nevada Test Site. It has been found that externally induced variations in the photocathode voltage of the streak tube can produce both temporal and spatial errors on the output image. ...

M. W. Bowers G. L. Biggs J. J. Ronchetto A. T. Teruya

1988-01-01

155

Streamwise streaks and secondary instability in a two-dimensional bent channel  

NASA Astrophysics Data System (ADS)

Streamwise streaks generated from a pair of oblique waves and secondary instability of the streaks are studied in a two-dimensional bent channel. Nonlinear parabolized stability equations (NPSE) are employed to investigate streamwise streaks and vortices. A pair of oblique waves from linear stability analysis is imposed as initial disturbances. Generation of streamwise streaks and vortices and subsequent development are described in detail. The case of plane channel is also studied to provide comparable data. Through comparison, the effect of bent region is clearly highlighted. Results of parametric studies to examine the effect of Reynolds number, radius of curvature, and bent angle are also given and discussed in detail. Secondary instability analysis for the modified mean flow due to the streamwise streaks is carried out by solving a two-dimensional eigenvalue problem. Several unstable modes which can be classified into fundamental and subharmonic mode of secondary instability are identified. Among several unstable modes, two modes are turned out to be dominant modes. Details on these two modes including generation mechanism, typical pattern, and dependency on wave number and streak amplitude are discussed. It is found that the presence of bent channel can lead to early oblique-mode breakdown via strong growth of the streamwise streaks due to the curved section. Such large amplitude of streaks and its secondary instability eventually could trigger transition even for small amplitude oblique waves at subcritical channel Reynolds numbers.

Park, Donghun; Park, Seung O.

2014-06-01

156

Temporal characteristics of picosecond continuum as revealed by a two-dimensional analysis of streak images  

NASA Astrophysics Data System (ADS)

A two-dimensional analysis has been made for streak images of picosecond continua generated in D 2O, CCl 4, saturated aqueous solution of KDP, H 3PO 4 and quartz block. Their pulse width and distribution of arrival time at the streak camera were determined as a function of the wavelength.

Masuhara, Hiroshi; Miyasaka, Hiroshi; Karen, Akiya; Uemiya, Taka; Mataga, Noboru; Koishi, Musubu; Takeshima, Akira; Tsuchiya, Yutaka

1983-02-01

157

Development of recombinant coat protein antibody based IC-RT-PCR for detection and discrimination of sugarcane streak mosaic virus isolates from Southern India  

Microsoft Academic Search

Summary.  ?Sugarcane streak mosaic virus (SCSMV), causes mosaic disease of sugarcane and is thought to belong to a new undescribed genus\\u000a in the family Potyviridae. The coat protein (CP) gene from the Andhra Pradesh (AP) isolate of SCSMV (SCSMV-AP) was cloned and expressed in Escherichia coli. The recombinant coat protein was used to raise high quality antiserum. The CP antiserum was

M. Hema; N. Kirthi; P. Sreenivasulu; H. S. Savithri

2003-01-01

158

Genetic variants of Banana streak virus in Mauritius.  

PubMed

Genetic variations among isolates of Banana streak virus (BSV) were assessed using two sets of primers. The virus, found in banana accessions in Mauritius, was compared to a Nigerian isolate from cultivar Obino l'Ewai (BSOEV). On the basis of the observed size of amplicons, some Mauritius strains were different from l'Ewai BSOEV. Both Southern blot hybridization and the nucleotide sequences of the PCR products confirmed that they were of episomal BSV origin. An isolate of sugarcane bacilliform virus (SCBV) was found to be also very similar to the BSV isolated from banana samples. Nucleotide sequence analysis showed that even the same size PCR products had differing sequences. The dendrogram placed the isolates from Mauritius in a cluster separate from BSV and SCBV from other geographical locations. PMID:16143419

Jaufeerally-Fakim, Y; Khorugdharry, Ashwin; Harper, Glyn

2006-01-01

159

Attosecond Streaking in the Low-Energy Region  

NASA Astrophysics Data System (ADS)

The low-energy photonelectron (PEs) ionized by a single attosecond pulse can be controlled by a moderately intense infrared field (IR). The electric field of the IR pulse can drive part of the PEs back to the parent ion and induce multiple rescattering of the electrons. Interesting interference patterns are observed in the photoelectron momentum distributions, which are formed by the rescattered electrons and the directly ionized PEs. By analyzing the interference patterns with a simple semiclassical model, which considers the particular PE trajectories incorporating the rescattering with the core, we demonstrate that the low-energy attosecond streaking offers a promising method of holographic imaging of atomic and molecular potential. In addition, we show that neither strong field approximation (SFA) or Coulomb-Volkov approximation (CVA) is able to reproduce these interesting structures at the low energy region.

Geng, Ji-Wei; Peng, Liang-You; Xu, Ming-Hui; Gong, Qihuang

2014-04-01

160

Photorespiratory Phenomena in Maize  

PubMed Central

Concurrent O2 evolution, O2 uptake, and CO2 uptake by illuminated maize (Zea mays) leaves were measured using 13CO2 and 18O2. Considerable O2 uptake occurred during active photosynthesis. At CO2 compensation, O2 uptake increased. Associated with this increase was a decrease in O2 release such that a stoichiometric exchange of O2 occurred. The rate of O2 exchange at CO2 compensation was directly related to O2 concentration in the atmosphere at least up to 8% (v/v). When illuminated maize leaves were exposed to saturating CO2 concentrations containing approximately equal amounts of 12CO2 and 13CO2, the latter was taken up more rapidly, thus depressing the atom% 13C in the atmosphere. Moreover, upon exposure to CO2 containing 96 atom% 13C, there occurred a directly measurable efflux of 12CO2 from the leaves for at least 15 minutes. During this period an equimolar evolution of 16O2 and uptake of 13CO2 was observed. Thereafter, although the rate of 16O2 evolution remained unchanged, the rate of 13CO2 uptake declined markedly, suggesting continual 13C enrichment of the photorespiratory substrate. It is concluded that a finite photorespiratory process occurs in maize and that the CO2 generated thereby is efficiently recycled. Recycling maintains the internal CO2 concentration at a level difficult to detect by most photorespiratory assays.

Volk, R. J.; Jackson, W. A.

1972-01-01

161

Breeding widely adapted, popular maize hybrids  

Microsoft Academic Search

World trend is to more maize hectarage grown to fewer, more widely-adapted hbrids. My purpose is to document research events leading to the most popular corn hybrids, Pioneer Brand 3780 and 3732. I provide background on maize adaptedness, on the seed maize business, on commercial maize hybrid development process, and on cultural practice change. I provide historical information on the

A. Forrest Troyer

1996-01-01

162

Evaluation of the DipStreak, a new device with an original streaking mechanism for detection, counting, and presumptive identification of urinary tract pathogens.  

PubMed

DipStreak is a new urine culture device with two types of agar attached back-to-back on a plastic paddle. It combines dip-slide technology and an original streaking inoculation mechanism, allowing for bacterial counting and colony isolation. The performance of the DipStreak device with two different medium formulations, CHROMagar and MacConkey media in study A and UriSelect 3 and MacConkey media in study B, was evaluated and compared to that of the reference streak method by using plates of cystine-lactose-electrolyte-deficient (CLED) agar, tryptic soy agar with 5% sheep blood, and UriSelect 3 medium. In study A, 2,000 urine specimens were processed and 511 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave the same detection rate, 99.7%. For the direct identification of Escherichia coli, Proteus mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 97 and 93.4%, respectively. In study B, 3,000 urine specimens were processed and 714 cultures were found positive. The DipStreak device and the UriSelect 3 and CLED medium plates gave detection rates of 99.4, 99.9, and 99.2%, respectively. For the direct identification of E. coli, P. mirabilis, and Enterococcus sp. isolates, the DipStreak device and the UriSelect 3 medium plate showed overall sensitivities of 88 and 94.4%, respectively. In conclusion, the DipStreak device with both medium formulations represents an attractive and excellent screening method for the reliable detection, counting, and presumptive identification of urinary tract pathogens. It enables bedside urine inoculation and provides a valid means of transporting the sample back to the laboratory, decreasing drastically the rate of false-positive results due to bacterial overgrowth and reducing associated costs. PMID:12037082

Scarparo, Claudio; Piccoli, Paola; Ricordi, Paolo; Scagnelli, Mariuccia

2002-06-01

163

Dynamics of Southern rice black-streaked dwarf virus in rice and implication for virus acquisition.  

PubMed

A novel viral disease of rice caused by Southern rice black-streaked dwarf virus (SRBSDV) has spread throughout East and Southeast Asia since the mid-2000s. Outbreaks of this viral disease occur yearly in southern parts of Japan concurrently with overseas migration of the planthopper vector Sogatella furcifera from southern China during the rainy season (from late June to early July). We examined the dynamics (changes in titer and localization) of SRBSDV on rice using reverse-transcription real-time polymerase chain reaction and determined the relationship between virus titer in plants and virus acquisition by S. furcifera. Under a constant temperature of 27°C, a substantial increase of SRBSDV titer in the leaf sheath together with typical symptoms (stunted growth and twisting of leaf tips) was observed at 20 days after the end of a 7-day exposure of viruliferous S. furcifera. Approximately 40% of S. furcifera acquired SRBSDV through feeding for 5 days on rice plants that were infected following exposure to viruliferous vectors for 10 to 15 days. These results suggest that rice infected by S. furcifera can be a source of SRBSDV before the next generation of S. furcifera emerges. PMID:23301813

Matsukura, Keiichiro; Towata, Tomomi; Sakai, Junichi; Onuki, Masatoshi; Okuda, Mitsuru; Matsumura, Masaya

2013-05-01

164

Ultra fast x-ray streak camera for ten inch manipulator based platforms  

NASA Astrophysics Data System (ADS)

Ultra fast x-ray streak cameras are a staple for time resolved x-ray measurements. There is a need for a ten inch manipulator (TIM) based streak camera that can be fielded in a newer large scale laser facility. The Lawrence Livermore National Laboratory ultra fast streak camera's drive electronics have been upgraded and redesigned to fit inside a TIM tube. The camera also has a new user interface that allows for remote control and data acquisition. The system has been outfitted with a new sensor package that gives the user more operational awareness and control.

Marley, E. V.; Shepherd, R.; Fulkerson, S.; James, L.; Emig, J.; Norman, D.

2012-10-01

165

Ultra Fast X-ray Streak Camera for TIM Based Platforms  

SciTech Connect

Ultra fast x-ray streak cameras are a staple for time resolved x-ray measurements. There is a need for a ten inch manipulator (TIM) based streak camera that can be fielded in a newer large scale laser facility. The LLNL ultra fast streak camera's drive electronics have been upgraded and redesigned to fit inside a TIM tube. The camera also has a new user interface that allows for remote control and data acquisition. The system has been outfitted with a new sensor package that gives the user more operational awareness and control.

Marley, E; Shepherd, R; Fulkerson, E S; James, L; Emig, J; Norman, D

2012-05-02

166

Root infection and systemic colonization of maize by Colletotrichum graminicola.  

PubMed

Colletotrichum graminicola is a filamentous ascomycete that causes anthracnose disease of maize. While the fungus can cause devastating foliar leaf blight and stalk rot diseases, little is known about its ability to infect roots. Previously published reports suggest that C. graminicola may infect maize roots and that root infections may contribute to the colonization of aboveground plant tissues, leading to disease. To determine whether C. graminicola can infect maize roots and whether root infections can result in the colonization of aboveground plant tissues, we developed a green fluorescent protein-tagged strain and used it to study the plant root colonization and infection process in vivo. We observed structures produced by other root pathogenic fungi, including runner hyphae, hyphopodia, and microsclerotia. A mosaic pattern of infection resulted from specific epidermal and cortical cells becoming infected by intercellular hyphae while surrounding cells were uninfected, a pattern that is distinctly different from that described for leaves. Interestingly, falcate conidia, normally restricted to acervuli, were also found filling epidermal cells and root hairs. Twenty-eight percent of plants challenged with soilborne inoculum became infected in aboveground plant parts (stem and/or leaves), indicating that root infection can lead to asymptomatic systemic colonization of the plants. Many of the traits observed for C. graminicola have been previously reported for other root-pathogenic fungi, suggesting that these traits are evolutionally conserved in multiple fungal lineages. These observations suggest that root infection may be an important component of the maize anthracnose disease cycle. PMID:18065625

Sukno, Serenella A; García, Verónica M; Shaw, Brian D; Thon, Michael R

2008-02-01

167

Wind streaks in Tharsis and Elysium - Implications for sediment transport by slope winds  

NASA Technical Reports Server (NTRS)

Detailed maps of wind streaks in Tharsis and Elysium have been compiled from Viking Orbiter observations spanning one complete Martian year. The streak pattern is controlled by slope winds on the central volcanoes and on the flanks of the Tharsis bulge, while the global circulation dominates in Elysium. Dust erosion by downslope winds occurs over much of Tharsis and in the vicinity of Elysium Mons; this process is effective even at the low atmospheric pressures found near the summits of the large volcanoes. Erosional streaks are largely absent in Elysium Planitia; net deposition of dust might have occurred during the period of the observations. Surface properties such as slope, thermal inertia, and roughness may influence the efficiency of slope wind production sufficiently to account for the pronounced differences in streak types and patterns present in these two regions.

Lee, S. W.; Thomas, P. C.; Veverka, J.

1982-01-01

168

Errors in Streak Photography Measurements Caused by Subject and Camera Misalighment.  

National Technical Information Service (NTIS)

Streak-camera photography can be used to determine velocity and acceleration of projectiles during impact. The values obtained from these photographs are subject to errors such as caused by the trajectory canted relative to the camera slit (aximuthal misa...

D. J. Mary

1972-01-01

169

Standard design for National Ignition Facility x-ray streak and framing cameras  

SciTech Connect

The x-ray streak camera and x-ray framing camera for the National Ignition Facility were redesigned to improve electromagnetic pulse hardening, protect high voltage circuits from pressure transients, and maximize the use of common parts and operational software. Both instruments use the same PC104 based controller, interface, power supply, charge coupled device camera, protective hermetically sealed housing, and mechanical interfaces. Communication is over fiber optics with identical facility hardware for both instruments. Each has three triggers that can be either fiber optic or coax. High voltage protection consists of a vacuum sensor to enable the high voltage and pulsed microchannel plate phosphor voltage. In the streak camera, the high voltage is removed after the sweep. Both rely on the hardened aluminum box and a custom power supply to reduce electromagnetic pulse/electromagnetic interference (EMP/EMI) getting into the electronics. In addition, the streak camera has an EMP/EMI shield enclosing the front of the streak tube.

Kimbrough, J. R.; Bell, P. M.; Bradley, D. K.; Holder, J. P.; Kalantar, D. K.; MacPhee, A. G.; Telford, S. [Lawrence Livermore National Laboratory, Livermore, California 94551-0808 (United States)

2010-10-15

170

Effects of Canavalia ensiformis and Mucuna pruriens intercrops on Pratylenchus zeae damage and yield of maize in subsistence agriculture  

Microsoft Academic Search

Host status of four leguminous cover crops [Canavalia ensiformis (L.) DC. (Jack bean), Crotalaria ochroleuca G. Don (Sunnhemp), Lablab purpureus L. (Hyacinth bean) and Mucuna pruriens (L.) DC. (velvet bean)] to Pratylenchus zeae Filipjev and effects of intercropping C. ensiformis and M. pruriens with Pan5195, H627 and Emap11 maize cultivars on P. zeae population and disease severity on maize were

O. J. Arim; J. W. Waceke; S. W. Waudo; J. W. Kimenju

2006-01-01

171

Development of soft x-ray streak cameras at Lawrence Livermore National Laboratory  

SciTech Connect

Soft x-ray streak cameras are used in conjunction with several instruments for the diagnostic of laser irradiated targets. A program was undertaken to develop cameras satisfying the requirements of the laser facility, to improve the reliability and performance of the camera and to reduce the level of effort required to set and operate each diagnostic. The implemented soft x-ray streak cameras can be operated either manually or automatically.

Medecki, H.; Phillips, G.E.; Bushman, J.F.

1983-06-27

172

Split ring resonator based THz-driven electron streak camera featuring femtosecond resolution  

PubMed Central

Through combined three-dimensional electromagnetic and particle tracking simulations we demonstrate a THz driven electron streak camera featuring a temporal resolution on the order of a femtosecond. The ultrafast streaking field is generated in a resonant THz sub-wavelength antenna which is illuminated by an intense single-cycle THz pulse. Since electron bunches and THz pulses are generated with parts of the same laser system, synchronization between the two is inherently guaranteed.

Fabianska, Justyna; Kassier, Gunther; Feurer, Thomas

2014-01-01

173

Split ring resonator based THz-driven electron streak camera featuring femtosecond resolution.  

PubMed

Through combined three-dimensional electromagnetic and particle tracking simulations we demonstrate a THz driven electron streak camera featuring a temporal resolution on the order of a femtosecond. The ultrafast streaking field is generated in a resonant THz sub-wavelength antenna which is illuminated by an intense single-cycle THz pulse. Since electron bunches and THz pulses are generated with parts of the same laser system, synchronization between the two is inherently guaranteed. PMID:25010060

Fabia?ska, Justyna; Kassier, Günther; Feurer, Thomas

2014-01-01

174

Automatic spatial characterization of low-speed streaks from thermal images  

Microsoft Academic Search

Flow visualization is an important tool for investigating turbulent flow, and, specifically, for characterizing low-speed\\u000a streaks in the boundary layer. The span-wise spatial characteristics of these streaks are commonly extracted by human visual\\u000a inspection, which is time consuming and subject to human errors and biases. Attempts to develop automatic methods have relied\\u000a exclusively on spectral techniques, using mostly the autocorrelation

M. Zacksenhouse; G. Abramovich; G. Hetsroni

2001-01-01

175

Effect of Aging on Fatty Streak Formation in a Diet-Induced Mouse Model of Atherosclerosis  

Microsoft Academic Search

Age is considered to be a major risk factor for atherosclerosis, but it is unclear whether age has a direct effect on susceptibility to atherosclerosis. Wild-type mice develop fatty streak lesions in the aortic root only when fed a cholate-containing high fat\\/cholesterol diet. To investigate the influence of age on fatty streak formation, young (10 weeks) and old (53 weeks)

Yuhua Li; Timothy R. Gilbert; Alan H. Matsumoto; Weibin Shi

2008-01-01

176

Polar Dunes In Summer Exhibit Frost Patches, Wind Streaks  

NASA Technical Reports Server (NTRS)

Mars Global Surveyor passes over the north polar region of the red planet twelve times each day, offering many opportunities to observe how the polar cap frosts and dunes are changing as the days goby. Right now it is summer in the north. This picture, taken the second week of April 1999, shows darks and dunes and remnant patches of bright frost left over from the winter that ended in July 1998. Dark streaks indicate recent movement of sand. The picture covers an area only 1.4 kilometers (0.9 miles)across and is illuminated from the upper right.

Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

1999-01-01

177

Intial synchroscan streak camera imaging at the A0 photoinjector  

SciTech Connect

At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10 to 20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5-ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of {approx}1 ps over 10s of minutes. This allowed us to measure both the UV laser pulse train at 244 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 1 nC per micropulse. We also did electron beam bunch length vs. micropulse charge measurements to identify a significant e-beam micropulse elongation from 10 to 30 ps (FWHM) for charges from 1 to 4.6 nC. This effect is attributed to space-charge effects in the PC gun as reproduced by ASTRA calculations. Chromatic temporal dispersion effects in the optics were also characterized and will be reported.

Lumpkin, A.H.; Ruan, J.; /Fermilab

2008-04-01

178

Quantitative measurements using soft-x-ray streak cameras  

SciTech Connect

A Soft X-Ray Streak Camera (SXRSC) is a fast timing instrument sensitive to x rays from 100 eV to 300 keV. The instrument has excellent time resolution (approx. 15 ps) and large dynamic range (approx. 10/sup 3/) which are well suited for measuring x-ray pulses produced by laser-fusion targets. The SXRSC uses a thin transmission photocathode to convert x-rays to a secondary electron signal which is accelerated, focused, and deflected onto a phosphor producing an image of the x-ray pulse time history. In the past, such instruments have been used only to make relative measurements of the time history. At LLNL we have calibrated the SXRSC in order to make absolute intensity measurements of the soft x-ray flux from laser fusion targets. Such measurements will assist in understanding the laser plasma processes and conditions needed to attain laser-produced fusion. Because of the nature of the instrument, we have calibrated it in the dynamic mode using a small laser-produced pulsed x-ray source.

Kauffman, R.L.; Stradling, G.L.; Pierce, E.L.; Medecki, H.

1981-08-01

179

New observations of Bolivian wind streaks by JPL Airborne SAR: Preliminary results  

NASA Technical Reports Server (NTRS)

In 1993 NASA's Jet Propulsion Laboratory Airborne Synthetic Aperture Radar system (AIRSAR) was deployed to South America to collect multi-parameter radar data over pre-selected targets. Among the sites targeted was a series of wind streaks located in the Altiplano of Bolivia. The objective of this investigation is to study the effect of wavelength, polarization, and incidence angle on the visibility of wind streaks in radar data. Because this is a preliminary evaluation of the recently acquired data we will focus on one scene and, thus, only on the effects of wavelength and polarization. Wind streaks provide information on the near-surface prevailing winds and on the abundance of winderodible material, such as sand. The potential for a free-flyer radar system that could provide global radar images in multiple wavelengths, polarizations, and incidence angles requires definition of system parameters for mission planning. Furthermore, thousands of wind streaks were mapped from Magellan radar images of Venus; their interpretation requires an understanding of the interaction of radar with wind streaks and the surrounding terrain. Our experiment was conducted on wind streaks in the Altiplano of Bolivia to address these issues.

Blumberg, Dan G.; Greeley, Ronald

1995-01-01

180

Effects of Hot Streak Shape on Rotor Heating in a High-Subsonic Single-Stage Turbine  

NASA Technical Reports Server (NTRS)

Experimental data have shown that combustor temperature non-uniformities can lead to the excessive heating of first-stage rotor blades in turbines. This heating of the rotor blades can lead to thermal fatigue and degrade turbine performance. The results of recent studies have shown that variations in the circumferential location (clocking) of the hot streak relative to the first-stage vane airfoils can be used to minimize the adverse effects of the hot streak. The effects of the hot streak/airfoil count ratio on the heating patterns of turbine airfoils have also been evaluated. In the present investigation, three-dimensional unsteady Navier-Stokes simulations have been performed for a single-stage high-pressure turbine operating in high subsonic flow. In addition to a simulation of the baseline turbine, simulations have been performed for circular and elliptical hot streaks of varying sizes in an effort to represent different combustor designs. The predicted results for the baseline simulation show good agreement with the available experimental data. The results of the hot streak simulations indicate: that a) elliptical hot streaks mix more rapidly than circular hot streaks, b) for small hot streak surface area the average rotor temperature is not a strong function of hot streak temperature ratio or shape, and c) hot streaks with larger surface area interact with the secondary flows at the rotor hub endwall, generating an additional high temperature region.

Dorney, Daniel J.; Gundy-Burlet, Karen L.; Norvig, Peter (Technical Monitor)

1999-01-01

181

The Maize Genetics and Genomics Database. The Community Resource for Access to Diverse Maize Data1  

PubMed Central

The Maize Genetics and Genomics Database (MaizeGDB) serves the maize (Zea mays) research community by making a wealth of genetics and genomics data available through an intuitive Web-based interface. The goals of the MaizeGDB project are 3-fold: to provide a central repository for public maize information; to present the data through the MaizeGDB Web site in a way that recapitulates biological relationships; and to provide an array of computational tools that address biological questions in an easy-to-use manner at the site. In addition to these primary tasks, MaizeGDB team members also serve the community of maize geneticists by lending technical support for community activities, including the annual Maize Genetics Conference and various workshops, teaching researchers to use both the MaizeGDB Web site and Community Curation Tools, and engaging in collaboration with individual research groups to make their unique data types available through MaizeGDB.

Lawrence, Carolyn J.; Seigfried, Trent E.; Brendel, Volker

2005-01-01

182

Prediction of functional regions of the maize streak virus replication-associated proteins by protein-protein interaction analysis  

Microsoft Academic Search

The replication of the geminiviruses depends on the viral encoded early (complementary-sense) proteins and on host genome encoded factors. Additionally, some of the early proteins (the AL2 protein of subgroup III, and the RepA (formerly known as C1) or Rep (C1:C2) proteins of subgroup I geminiviruses) can function as transcriptional activators of virion- (V-)sense gene expression. The yeast two-hybrid system

Gábor V. Horváth; Aladár Pettkó-Szandtner; Krisztina Nikovics; Metin Bilgin; Margaret Boulton; Jeffrey W. Davies; Crisanto Gutiérrez; Dénes Dudits

1998-01-01

183

An Optical Streaking Method for Measuring Femtosecond Electron Bunches  

SciTech Connect

The measurement of the ultra-short electron bunch length on the femtosecond time scale constitutes a very challenging problem. In the x-ray free electron laser facilities such as the Linac Coherent Light Source, generation of a sub-ten femtoseconds electron beam with 20pC charge is possible, but direct measurements are very difficult due to the resolution limit of the present diagnostics. We propose a new method here based on the measurement of the electron beam energy modulation induced from laser-electron interaction in a short wiggler. A typical optical streaking method requires a laser wavelength much longer than the electron bunch length. In this paper a laser with its wavelength shorter than the electron bunch length has been adopted, while the slope on the laser intensity envelope is used to distinguish the different periods. With this technique it is possible to reconstruct the bunch longitudinal profile from a single shot measurement. Generation of ultrashort x-ray pulses at femtoseconds (fs) scale is of great interest within synchrotron radiation and free electron laser (FEL) user community. One of the simple methods is to operate the FEL facility at low charge. At the Linac Coherent Light Source (LCLS), we have demonstrated the capability of generating ultrashort electron-beam (e-beam) with a duration of less than 10 fs fwhm using 20 pC charge. The x-ray pulses have been delivered to the x-ray users with a similar or even shorter pulse duration. However, The measurement of such short electron or x-ray pulse length at the fs time-scale constitutes a challenging problem. A standard method using an S-band radio-frequency (rf) transverse deflector has been established at LCLS, which works like a streak camera for electrons and is capable of resolving bunch lengths as short as 25 fs fwhm. With this device, the electrons are transversely deflected by the high-frequency time-variation of the deflecting fields. Increasing the deflecting voltage and rf frequency are the right direction to achieve a better resolution. For example, by choosing an X-band transverse deflecting cavity, the expected resolution for LCLS beam with 4.3 GeV is about 1 fs rms. Typically the rf breakdown threshold and the power source availability prevent going to even higher voltage and frequency. With the highly-developed laser techniques, we can choose to streak the beam at optical frequencies. By jumping from rf to optical frequency, the wavelength is shortening by 4 to 5 orders. With an electron bunch length shorter than half period of the laser, we can apply the similar rf deflecting or zero-phasing method for e-beam bunch length measurements using a high-power laser. A short wiggler is required to provide interaction between the electron and the laser. For example, to measure the e-beam at the order of 1 m rms length, a laser with its wavelength of 10 {mu}m may be considered. For a typical few GeV e-beam, the wiggler period has to be large to satisfy the resonance condition. Also, if the e-beam is longer than one laser period, the different modulation periods will overlap and we cannot distinguish them. So this method is so far limited by the achievable long-wavelength laser power. To get an effective modulation on an e-beam of 4.3 GeV, the required laser power is about a few tens GW. In this paper we propose to adopt a high-power Ti:Sapphire laser (wavelength of 800 nm), and use the slope in the intensity envelope to distinguish the different modulation periods. First an ultrashort electron beam interacts with the Ti:Sapphire laser in a wiggler, where the electron energy is modulated at the same periods of the laser. If the laser pulse is long and the short electron bunch is overlapped (in time) with the middle part of the laser, such as the setup at LCLS laser heater, the different energy modulation periods on the electron beam will be overlapped on the energy profile. In this conditionwe typically have a double-horn distribution of the energy profile, and the electron-bunch length information cannot be retrieved. But if the laser pulse (

Ding, Yuantao; Bane, Karl L.F.; Huang, Zhirong; /SLAC

2011-12-14

184

Bioactive metabolites from Stenocarpella maydis, a stalk and ear rot pathogen of maize  

Microsoft Academic Search

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. In an effort to investigate the potential roles of S. maydis metabolites in the fungal disease cycle, ethyl acetate extracts of solid-substrate fermentations of several S. maydis isolates

Donald T. Wicklow; Kristina D. Rogers; Patrick F. Dowd; James B. Gloer

2011-01-01

185

Influence of maize/lablab intercropping on lepidopterous stem borer infestation in maize.  

PubMed

Lepidopterous stem borers seriously affect production of maize, Zea mays L., in sub-Saharan Africa. Intercropping maize with legumes such as lablab, Lablab purpurens (L.), is one of the effective systems to control stem borers. Sole culture maize and maize/lablab intercrop system of different lablab densities were planted at two locations to investigate the effects of intercrop system on incidence and severity of stem borers with particular reference to Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). Stem borer infestation was found to be more severe in sole culture maize than maize in maize/lablab intercrop. There was a significantly negative relationship between lablab densities and maize grain yields, suggesting a possible competition for resources between the two crops. It was concluded that density of lablab and date of planting of lablab in maize/lablab intercropping have significant affects on stem borer populations and maize grain yields. PMID:15889728

Maluleke, Mary H; Addo-Bediako, Abraham; Ayisi, Kingsley K

2005-04-01

186

A maize cystatin suppresses host immunity by inhibiting apoplastic cysteine proteases.  

PubMed

Ustilago maydis is a biotrophic pathogen causing maize (Zea mays) smut disease. Transcriptome profiling of infected maize plants indicated that a gene encoding a putative cystatin (CC9) is induced upon penetration by U. maydis wild type. By contrast, cc9 is not induced after infection with the U. maydis effector mutant ?pep1, which elicits massive plant defenses. Silencing of cc9 resulted in a strongly induced maize defense gene expression and a hypersensitive response to U. maydis wild-type infection. Consequently, fungal colonization was strongly reduced in cc9-silenced plants, while recombinant CC9 prevented salicylic acid (SA)-induced defenses. Protease activity profiling revealed a strong induction of maize Cys proteases in SA-treated leaves, which could be inhibited by addition of CC9. Transgenic maize plants overexpressing cc9-mCherry showed an apoplastic localization of CC9. The transgenic plants showed a block in Cys protease activity and SA-dependent gene expression. Moreover, activated apoplastic Cys proteases induced SA-associated defense gene expression in naïve plants, which could be suppressed by CC9. We show that apoplastic Cys proteases play a pivotal role in maize defense signaling. Moreover, we identified cystatin CC9 as a novel compatibility factor that suppresses Cys protease activity to allow biotrophic interaction of maize with the fungal pathogen U. maydis. PMID:22454455

van der Linde, Karina; Hemetsberger, Christoph; Kastner, Christine; Kaschani, Farnusch; van der Hoorn, Renier A L; Kumlehn, Jochen; Doehlemann, Gunther

2012-03-01

187

A Maize Cystatin Suppresses Host Immunity by Inhibiting Apoplastic Cysteine Proteases[C][W  

PubMed Central

Ustilago maydis is a biotrophic pathogen causing maize (Zea mays) smut disease. Transcriptome profiling of infected maize plants indicated that a gene encoding a putative cystatin (CC9) is induced upon penetration by U. maydis wild type. By contrast, cc9 is not induced after infection with the U. maydis effector mutant ?pep1, which elicits massive plant defenses. Silencing of cc9 resulted in a strongly induced maize defense gene expression and a hypersensitive response to U. maydis wild-type infection. Consequently, fungal colonization was strongly reduced in cc9-silenced plants, while recombinant CC9 prevented salicylic acid (SA)–induced defenses. Protease activity profiling revealed a strong induction of maize Cys proteases in SA-treated leaves, which could be inhibited by addition of CC9. Transgenic maize plants overexpressing cc9-mCherry showed an apoplastic localization of CC9. The transgenic plants showed a block in Cys protease activity and SA-dependent gene expression. Moreover, activated apoplastic Cys proteases induced SA-associated defense gene expression in naïve plants, which could be suppressed by CC9. We show that apoplastic Cys proteases play a pivotal role in maize defense signaling. Moreover, we identified cystatin CC9 as a novel compatibility factor that suppresses Cys protease activity to allow biotrophic interaction of maize with the fungal pathogen U. maydis.

van der Linde, Karina; Hemetsberger, Christoph; Kastner, Christine; Kaschani, Farnusch; van der Hoorn, Renier A.L.; Kumlehn, Jochen; Doehlemann, Gunther

2012-01-01

188

Automatic spatial characterization of low-speed streaks from thermal images  

NASA Astrophysics Data System (ADS)

Flow visualization is an important tool for investigating turbulent flow, and, specifically, for characterizing low-speed streaks in the boundary layer. The span-wise spatial characteristics of these streaks are commonly extracted by human visual inspection, which is time consuming and subject to human errors and biases. Attempts to develop automatic methods have relied exclusively on spectral techniques, using mostly the autocorrelation or its Fourier transform, the spatial spectrum. However, the autocorrelation tends to get flattened with the amount of data analyzed and has been reported to provide biased estimates. Furthermore, it estimates only the mean spacing and does not provide a direct measure of its distribution. In this paper, an alternative automatic method is developed based on edge detection, and is applied to thermal images obtained by infrared thermography of a heated wall exposed to a turbulent flow. The method presented yields not only the spacing between the low-speed streaks but also their width and separation. The analysis indicates that the spacing (120+/-52wall units) is divided almost evenly between the width (65+/-33wall units) and the separation (55+/-40wall units) between the streaks, and that the width and separation are statistically independent. We also present a statistical model for the data, and demonstrate that when the spatial parameters of the streaks are so widely distributed, the spectral methods are not reliable.

Zacksenhouse, M.; Abramovich, G.; Hetsroni, G.

189

Distinct Wnt-driven primitive streak-like populations reflect in vivo lineage precursors.  

PubMed

During gastrulation, epiblast cells are pluripotent and their fate is thought to be constrained principally by their position. Cell fate is progressively restricted by localised signalling cues from areas including the primitive streak. However, it is unknown whether this restriction accompanies, at the individual cell level, a reduction in potency. Investigation of these early transition events in vitro is possible via the use of epiblast stem cells (EpiSCs), self-renewing pluripotent cell lines equivalent to the postimplantation epiblast. Strikingly, mouse EpiSCs express gastrulation stage regional markers in self-renewing conditions. Here, we examined the differentiation potential of cells expressing such lineage markers. We show that undifferentiated EpiSC cultures contain a major subfraction of cells with reversible early primitive streak characteristics, which is mutually exclusive to a neural-like fraction. Using in vitro differentiation assays and embryo grafting we demonstrate that primitive streak-like EpiSCs are biased towards mesoderm and endoderm fates while retaining pluripotency. The acquisition of primitive streak characteristics by self-renewing EpiSCs is mediated by endogenous Wnt signalling. Elevation of Wnt activity promotes restriction towards primitive streak-associated lineages with mesendodermal and neuromesodermal characteristics. Collectively, our data suggest that EpiSC pluripotency encompasses a range of reversible lineage-biased states reflecting the birth of pioneer lineage precursors from a pool of uncommitted EpiSCs similar to the earliest cell fate restriction events taking place in the gastrula stage epiblast. PMID:24595287

Tsakiridis, Anestis; Huang, Yali; Blin, Guillaume; Skylaki, Stavroula; Wymeersch, Filip; Osorno, Rodrigo; Economou, Costas; Karagianni, Eleni; Zhao, Suling; Lowell, Sally; Wilson, Valerie

2014-03-01

190

Nonstructural protein P7-2 encoded by Rice black-streaked dwarf virus interacts with SKP1, a core subunit of SCF ubiquitin ligase  

PubMed Central

Background Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus within the family Reoviridae, causes severe damage to cereal crops in South East Asia. The protein P7-2, encoded by the second open reading frame of segment S7, is conserved among most plant-infecting fijiviruses, but its function is still obscure. Results In this study, P7-2 was used as bait in two-hybrid screens of a cDNA library expressing Zea mays proteins. It was found that there is a strong interaction between P7-2 and Z. mays SKP1 (SKP1Maize), a core subunit of the multicomponent SCF (SKP1/Cullin1/F-box/Rbx1) E3 ubiquitin ligase. The interaction was then confirmed in leaf epidermal cells of Nicotiana benthamiana by bimolecular fluorescence complementation assay. Further investigations indicated that P7-2 also interacts with SKP1 proteins from other plants, including Arabidopsis thaliana, N. benthamiana,Oryza sativa and Saccharum sinense. The C-terminal fragment of SKP1Maize (residues 97–176) and the middle fragment of P7-2 (residues 79–214) are necessary to sustain the interaction, while the C-terminal putative ?-helix domain spanning residues 214–295 of P7-2 greatly facilitates the interaction. Agrobacterium-mediated transient suppression assay showed that P7-2 has no obvious activity to suppress local RNA silencing. Conclusions Taken together, our results indicated that RBSDV P7-2 can interact with SKP1 proteins from different plants. This is the first report linking a Fijivirus protein to a component of the ubiquitin proteasome system. P7-2 might be a potential F-box protein encoded by RBSDV and involved in the plant-virus interaction through ubiquitination pathway.

2013-01-01

191

Image streak techniques: ISKRA-5 facility X-ray space-time and spectral characteristics recording  

SciTech Connect

Presented below are the X-ray image streak techniques used to study the spectral- and spectral-spatial time behavior of the ISKRA-5 facility laser-irradiated target X-ray radiation. For this purpose, we developed several 0.1-10 keV range X-ray slit streak cameras with 3x10{sup {minus}11}-s time resolution. Our X-ray imaging layout made it possible to simultaneously project several target images (in different spectral intervals) to the photocathode and streak them synchroniously. These techniques made it possible to: Study the microsphere target and plasma corona implosion dynamics; investigate the well-adjacent plasma electron temperature behavior; determine the compressed core lifetime; and monitor the state of the external (non-irradiated) target surface. 7 refs., 4 figs.

Lazarchuk, V.P.; Murugov, V.M.; Petrov, S.I.; Senik, A.V. [VNIIEF Russian Federal Nuclear Center, Novgorod (Russian Federation)

1994-12-31

192

Time-resolved photoemission by attosecond streaking: extraction of time information  

NASA Astrophysics Data System (ADS)

Attosecond streaking is one of the most fundamental processes in attosecond science allowing for a mapping of temporal information to the energy domain. We study attosecond streaking setups for measuring the release time of electrons in atomic photoemission [cf. M. Schultze et al, Science 328, 1658 (2010)]. We show that on the single-particle level, the extracted time delays (phase shifts) contain timing (or spectral phase) information associated with the Eisenbud-Wigner-Smith time delay matrix of quantum scattering. However, this is only accessible if distortion effects by the streaking infrared field on the emission process are properly accounted for. We show that the ``time shifts'' due to the interaction between the outgoing electron and the combined Coulomb and IR laser field can be described classically. By contrast, we also find a strong initial state dependence of the apparent time delay, which is of quantum mechanical origin.

Nagele, Stefan; Pazourek, Renate; Doblhoff-Dier, Katharina; Lemell, Christoph; Burgdörfer, Joachim; T?kési, Karoly; Feist, Johannes

2011-06-01

193

Effects of diabatic heating on the ageostrophic circulation of an upper tropospheric jet streak  

NASA Technical Reports Server (NTRS)

Higher temporal resolution data from NASA's fourth Atmospheric Variability Experiment (April 24-25, 1975) are used to study the role of diabatic heating within the convective region in altering the ageostrophic mass circulation in the entrance region of the jet streak. The modifying effect this diabatic heating in the mesoscale storm exerts on the synoptic-scale environmental flow through dynamical mechanisms which link the mass circulation of these two scales is examined. The effect of diabatic heating on the ageostrophic motion within the thermally direct circulation of the jet streak and the mesoscale convective complexes is investigated. Diabatic modes of ageostrophic motion that intensify the upper tropospheric jet streak downstream are identified.

Keyser, D. A.; Johnson, D. R.

1984-01-01

194

Development of streak cameras for time-resolved experiments at the advanced laser light source laboratory  

NASA Astrophysics Data System (ADS)

The Advanced Laser light Source (ALLS) infrastructure is a new state-of-the-art multi-beams femtosecond laser facility currently in operation at INRS near Montreal, Canada. Multi-beams experiments and pump-probe geometry lead to the need of synchronization instrumentation tools. The use of a wide range of energy radiation from hard x-ray up to infrared light on the ultrafast time scale requires the development of ultrafast detector diagnostics tools to study the emission spectrum of these sources. To fulfill these requirements, new streak cameras have been developed for ALLS facility. The SV streak camera is a simple and compact multi-purpose instrument that will be used for beams synchronization with picosecond time resolution and good spatial resolution. The FXR streak camera is dedicated to x-ray spectroscopy with sub-picosecond time resolution combined with a very high spatial resolution.

Martel, C.; Fourmaux, S.; Côté, C. Y.; Magnan, S.; Lecherbourg, L.; Kieffer, J. C.

2007-01-01

195

Variable features on Mars V - Evidence for crater streaks produced by wind erosion  

NASA Technical Reports Server (NTRS)

High-resolution television pictures obtained by Mariner 9 are presented as evidence to show that the ragged dark streaks which appeared behind many dark craters several months after the end of the 1971 global dust storm resulted from wind erosion of a thin surface veneer consisting of dust-storm fallout. The pictures were taken over an area near the border between Mare Serpentis and Pandorae Fretum (approximately 30 deg S, 335 deg W). The high-resolution pictures are compared with low-resolution views of the same area, and it is shown that one very long dark streak is interrupted by a rille. It is concluded that this interruption proves that the dark streaks were produced by the present erosional mechanism.

Veverka, J.

1975-01-01

196

Mapping Maize Sequences to Chromosomes Using Oat-Maize Chromosome Addition Materials1[w  

PubMed Central

Oat- (Avena sativa) maize (Zea mays) chromosome additions are produced by crossing maize and oat. During early embryo development maize chromosomes are preferentially eliminated, and oat plants are often recovered that retain a single maize chromosome. Each of the 10 maize chromosomes recently has been isolated as a separate oat-maize addition. We describe here the mapping of 400 maize sequences to chromosomes using polymerase chain reaction and DNA from the oat-maize addition material. Fifty of the sequences were from cloned markers that had been previously mapped by linkage analysis, and our results were consistent with those obtained using Southern-blot analysis. Previously unmapped expressed sequence tags and sequence tagged sites (350) were mapped to chromosomes. Maize gene sequences and expression data are rapidly being accumulated. Coupling this information with positional information from high throughput mapping programs provides plant biologists powerful tools for identifying candidate genes of interest.

Okagaki, Ron J.; Kynast, Ralf G.; Livingston, Suzanne M.; Russell, Charles D.; Rines, Howard W.; Phillips, Ronald L.

2001-01-01

197

Probing dielectric-response effects with attosecond time-resolved streaked photoelectron spectroscopy of metal surfaces  

NASA Astrophysics Data System (ADS)

The release of conduction-band electrons from a metal surface by a subfemtosecond extreme ultraviolet (XUV) pulse and their propagation through the solid provoke a dielectric response in the solid that acts back on the photoelectron wave packet. We calculated the (wake) potential associated with this photoelectron self-interaction in terms of bulk and surface plasmon excitations and show that it induces a considerable, XUV-frequency-dependent temporal shift in laser-streaked XUV photoemission spectra, suggesting the observation of the ultrafast solid-state dielectric response in contemporary streaked photoemission experiments.

Zhang, C.-H.; Thumm, U.

2011-12-01

198

Accurate and efficient characterization of streak camera using etalon and fitting method with constraints.  

PubMed

Streak camera is widely used in continuous time diagnostics in fast physical process. To produce accurate result, it requires delicate calibration and a reliable analysis method. High quality sweep-rate data with uncertainty smaller than 0.5% are obtained over the full record area by a constrained fitting method of peak position measurement, with a short pulse laser and an etalon as the fiducial source. The temporal response is linearized by this full-screen sweep-rate data, which eliminates errors in measurement due to nonlinearity and space-distortion inherent in streak camera. PMID:22128970

Yang, Dong; Wang, Zhebin; Jiang, Xiaohua; Liu, Yonggang; Peng, Xiaoshi; Zhu, Tuo; Zhang, Huan; Li, Zhichao; Li, Sanwei; Ding, Yongkun

2011-11-01

199

MaizeGDB, the community database for maize genetics and genomics  

PubMed Central

The Maize Genetics and Genomics Database (MaizeGDB) is a central repository for maize sequence, stock, phenotype, genotypic and karyotypic variation, and chromosomal mapping data. In addition, MaizeGDB provides contact information for over 2400 maize cooperative researchers, facilitating interactions between members of the rapidly expanding maize community. MaizeGDB represents the synthesis of all data available previously from ZmDB and from MaizeDB—databases that have been superseded by MaizeGDB. MaizeGDB provides web-based tools for ordering maize stocks from several organizations including the Maize Genetics Cooperation Stock Center and the North Central Regional Plant Introduction Station (NCRPIS). Sequence searches yield records displayed with embedded links to facilitate ordering cloned sequences from various groups including the Maize Gene Discovery Project and the Clemson University Genomics Institute. An intuitive web interface is implemented to facilitate navigation between related data, and analytical tools are embedded within data displays. Web-based curation tools for both designated experts and general researchers are currently under development. MaizeGDB can be accessed at http://www.maizegdb.org/.

Lawrence, Carolyn J.; Dong, Qunfeng; Polacco, Mary L.; Seigfried, Trent E.; Brendel, Volker

2004-01-01

200

Investigations on Fusarium spp. and their mycotoxins causing Fusarium ear rot of maize in Kosovo.  

PubMed

After wheat, maize (Zea mays L.) is the second most important cereal crop in Kosovo and a major component of animal feed. The purpose of this study was to analyse the incidence and identity of the Fusarium species isolated from naturally infected maize kernels in Kosovo in 2009 and 2010, as well as the mycotoxin contamination. The disease incidence of Fusarium ear rot (from 0.7% to 40% diseased ears) on maize in Kosovo is high. The most frequently Fusarium spp. identified on maize kernels were Fusarium subglutinans, F. verticillioides/F. proliferatum and F. graminearum. Maize kernel samples were analysed by LC-MS/MS and found to be contaminated with deoxynivalenol (DON), DON-3-glucoside, 3-acetyl-DON, 15-acetyl-DON, zearalenone, zearalenone-14-sulphate, moniliformin, fumonisin B1 and fumonisin B2. This is the first report on the incidence and identification of Fusarium species isolated from naturally infected maize as well as the mycotoxin contamination in Kosovo. PMID:24779930

Shala-Mayrhofer, Vitore; Varga, Elisabeth; Marjakaj, Robert; Berthiller, Franz; Musolli, Agim; Berisha, Defrime; Kelmendi, Bakir; Lemmens, Marc

2013-12-01

201

Global maize production, utilization, and consumption.  

PubMed

Maize (Zea mays), also called corn, is believed to have originated in central Mexico 7000 years ago from a wild grass, and Native Americans transformed maize into a better source of food. Maize contains approximately 72% starch, 10% protein, and 4% fat, supplying an energy density of 365 Kcal/100 g and is grown throughout the world, with the United States, China, and Brazil being the top three maize-producing countries in the world, producing approximately 563 of the 717 million metric tons/year. Maize can be processed into a variety of food and industrial products, including starch, sweeteners, oil, beverages, glue, industrial alcohol, and fuel ethanol. In the last 10 years, the use of maize for fuel production significantly increased, accounting for approximately 40% of the maize production in the United States. As the ethanol industry absorbs a larger share of the maize crop, higher prices for maize will intensify demand competition and could affect maize prices for animal and human consumption. Low production costs, along with the high consumption of maize flour and cornmeal, especially where micronutrient deficiencies are common public health problems, make this food staple an ideal food vehicle for fortification. PMID:24650320

Ranum, Peter; Peña-Rosas, Juan Pablo; Garcia-Casal, Maria Nieves

2014-04-01

202

One and two-dimensional fast x-ray imaging of laser-driven implosion dynamics with x-ray streak cameras  

Microsoft Academic Search

One- (1D) and two-dimensional (2D) x-ray imaging techniques with x-ray streak cameras have been developed and utilized for investigating implosion dynamics of laser fusion targets. Conventional streaked 1D images of the shell motion of the imploding target was recorded together with the time-resolved 2D multi-imaging x-ray streak images of the core shapes on the same x-ray streak camera. Precise comparison

H. Shiraga; M. Heya; M. Nakasuji; N. Miyanaga; H. Azechi; H. Takabe; T. Yamanaka; K. Mima

1997-01-01

203

Streak camera measurements of laser pulse temporal dispersion in short graded-index optical fibers  

SciTech Connect

Streak camera measurements were used to determine temporal dispersion in short (5 to 30 meter) graded-index optical fibers. Results show that 50-ps, 1.06-..mu..m and 0.53-..mu..m laser pulses can be propagated without significant dispersion when care is taken to prevent propagation of energy in fiber cladding modes.

Lerche, R.A.; Phillips, G.E.

1981-08-28

204

Architectures and signal reconstruction methods for nanosecond resolution Integrated Streak Camera in standard CMOS technology  

Microsoft Academic Search

This paper presents the state of the art of the Integrated Streak Camera (ISC) architectures in standard CMOS technology. It focuses on some of the methods required for reconstructing the luminous events profile from the chip raw data. Two main ISC architectures are presented. The first adopts the traditional for the most silicon imagers pixel array configuration, where the photocharges-induced

Martin Zlatanski; Wilfried Uhring; Virginie Zint; Jean-Pierre Le Normand; Daniel Mathiot

2010-01-01

205

Photoemissive materials for 0. 35. mu. m laser fiducials in x-ray streak cameras  

SciTech Connect

Using a soft x-ray streak camera, materials are tested for suitability as transmission photocathodes when irradiated by 0.35..mu..m laser pulses. Preliminary measurements of sensitivity, dynamic range and temporal resolution are reported. A practical fiber optic fiducial under development for laser fusion x-ray diagnostics on the LLNL Nova laser system is described.

Hale, C.P.; Medecki, H.; Lee, P.H.Y.

1984-01-01

206

Optical Comb Generation for Streak Camera Calibration for Inertial Confinement Fusion Experiments  

SciTech Connect

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is coming on-line to support physics experimentation for the U.S. Department of Energy (DOE) programs in Inertial Confinement Fusion (ICF) and Stockpile Stewardship (SS). Optical streak cameras are an integral part of the experimental diagnostics instrumentation at NIF. To accurately reduce streak camera data a highly accurate temporal calibration is required. This article describes a technique for simultaneously generating a precise +/- 2 ps optical marker pulse (fiducial reference) and trains of precisely timed, short-duration optical pulses (so-called “comb” pulse trains) that are suitable for the timing calibrations. These optical pulse generators are used with the LLNL optical streak cameras. They are small, portable light sources that, in the comb mode, produce a series of temporally short, uniformly spaced optical pulses, using a laser diode source. Comb generators have been produced with pulse-train repetition rates up to 10 GHz at 780 nm, and somewhat lower frequencies at 664 nm. Individual pulses can be as short as 25-ps FWHM. Signal output is via a fiber-optic connector on the front panel of the generator box. The optical signal is transported from comb generator to streak camera through multi-mode, graded-index optical fiber.

Ronald Justin, Terence Davies, Frans Janson, Bruce Marshall, Perry Bell, Daniel Kalantar, Joseph Kimbrough, Stephen Vernon, Oliver Sweningsen

2008-09-18

207

Carotenoid-based status signaling by females in the tropical streak-backed oriole  

Microsoft Academic Search

In many tropical bird species, both males and females maintain elaborate plumage traits. Although there is considerable evidence that many male plumage traits function as status signals that convey information about fighting ability, less is known about status signaling in females. We tested whether the carotenoid-based orange breast coloration of the female streak-backed oriole (Icterus pustulatus pustulatus) signals status during

Troy G. Murphy; Diego Hernández-Muciño; Marcela Osorio-Beristain; Robert Montgomerie; Kevin E. Omland

2009-01-01

208

Full waveform earthquake location: Application to seismic streaks on the Calaveras Fault, California  

Microsoft Academic Search

We use a novel technique based upon source array analysis to locate three moderate earthquakes that occur at the edge of previously identified streaks of seismicity on the Calaveras Fault, California. Our method determines centroid locations for earthquakes, in addition to the hypocenters previously determined using first-break picks. Application of the method to smaller earthquakes indicates that the errors associated

Justin L. Rubinstein; Gregory C. Beroza

2007-01-01

209

Analysis of the thermal equilibrium state of bunched beams with a streak camera  

NASA Astrophysics Data System (ADS)

The thermal equilibrium distribution of cooled bunched ion beams in the ESR storage ring is investigated in simultaneous longitudinal-transverse measurements by using a scintillator and streak camera in the extraction beam line. We have found a cylindrical bunch model with local Gaussian density profiles confirming the model of a Maxwell-Boltzmann distribution in six-dimensional phase space.

Hofmann, I.; Johnson, K. F.; Spiller, P.; Eickhoff, H.; Kalisch, G.; Laux, W.; Steck, M.

1995-11-01

210

Simultaneous velocity interferometry and electronic streak photography of laser-launched plates  

SciTech Connect

Laser-launched, miniature, pseudo-one-dimensional flyer plates are evaluated by three distinct optical techniques that may be incorporated into an optical diagnostic system to give a complete understanding of the plate performance. These techniques are: velocity interferometry, streak photography, and pulsed laser stereo photography. 2 refs., 5 figs.

Paisley, D.L.; Stahl, D.B.; Garcia, I.A.

1991-01-01

211

Betaine Deficiency in Maize 1  

PubMed Central

Maize (Zea mays L.) is a betaine-accumulating species, but certain maize genotypes lack betaine almost completely; a single recessive gene has been implicated as the cause of this deficiency (D Rhodes, PJ Rich [1988] Plant Physiol 88: 102-108). This study was undertaken to determine whether betaine deficiency in diverse maize germplasm is conditioned by the same genetic locus, and to define the biochemical lesion(s) involved. Complementation tests indicated that all 13 deficient genotypes tested shared a common locus. One maize population (P77) was found to be segregating for betaine deficiency, and true breeding individuals were used to produce related lines with and without betaine. Leaf tissue of both betaine-positive and betaine-deficient lines readily converted supplied betaine aldehyde to betaine, but only the betaine-containing line was able to oxidize supplied choline to betaine. This locates the lesion in betaine-deficient plants at the choline ? betaine aldehyde step of betaine synthesis. Consistent with this location, betaine-deficient plants were shown to have no detectable endogenous pool of betaine aldehyde.

Lerma, Claudia; Rich, Patrick J.; Ju, Grace C.; Yang, Wen-Ju; Hanson, Andrew D.; Rhodes, David

1991-01-01

212

On the condition of streak formation in a bounded turbulent flow  

SciTech Connect

Flow between two surfaces at which no-slip and free-slip conditions can be imposed has been investigated numerically with a Fourier--Chebyshev pseudospectral method. Different mean shear rates have been applied to each boundary to study the effect of shear and boundary condition on the streaky structures that have been observed near walls in many previous investigations. In addition to the streaks found near the no-slip wall, the computations also reveal streaky structures when the free-slip surface is under a sufficiently high shear. The low-speed streaks observed near the free-slip surface, although appearing somewhat more pronounced, have much the same characteristics as the wall-layer streaks---e.g., the average spanwise spacing between the streaks both near the wall and the free surface is about 100 when normalized by the kinematic viscosity and the appropriate shear velocity (at the wall or at the free-slip surface). The results show that shear is much more important than the nature of the boundary in determining the dominant flow structure, rather unexpected since vortex lines can attach at a free-slip boundary whereas they cannot at a no-slip one. The formation of streaks appears to be governed by a local nondimensional shear parameter defined as {ital {tilde S}}{equivalent to}{ital S}{vert bar}{l angle}{ital u}{prime}{ital w}{prime}{r angle}{vert bar}/{epsilon}, where {ital S} is the mean shear rate, and {l angle}{ital u}{prime}{ital w}{prime}{r angle} and {epsilon} are the kinematic turbulent shear stress and rate of dissipation of turbulent kinetic energy, respectively. It is found that {ital {tilde S}}{congruent}1.0 is the condition at which the elongated low-speed streaky regions first appear.

Lam, K. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)); Banerjee, S. (Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, California 93106 (United States))

1992-02-01

213

Maize ZmRACK1 Is Involved in the Plant Response to Fungal Phytopathogens.  

PubMed

The receptor for activated C kinase 1 (RACK1) belongs to a protein subfamily containing a tryptophan-aspartic acid-domain (WD) repeat structure. Compelling evidence indicates that RACK1 can interact with many signal molecules and affect different signal transduction pathways. In this study, we cloned a maize RACK1 gene (ZmRACK1) by RT-PCR. The amino acid sequence of ZmRACK1 had seven WD repeats in which there were typical GH (glycine-histidine) and WD dipeptides. Comparison with OsRACK1 from rice revealed 89% identity at the amino acid level. Expression pattern analysis by RT-PCR showed that ZmRACK1 was expressed in all analyzed tissues of maize and that its transcription in leaves was induced by abscisic acid and jasmonate at a high concentration. Overexpression of ZmRACK1 in maize led to a reduction in symptoms caused by Exserohilum turcicum (Pass.) on maize leaves. The expression levels of the pathogenesis-related protein genes, PR-1 and PR-5, increased 2.5-3 times in transgenic maize, and reactive oxygen species production was more active than in the wild-type. Yeast two-hybrid assays showed that ZmRACK1 could interact with RAC1, RAR1 and SGT1. This study and previous work leads us to believe that ZmRACK1 may form a complex with regulators of plant disease resistance to coordinate maize reactions to pathogens. PMID:24865494

Wang, Baosheng; Yu, Jingjuan; Zhu, Dengyun; Chang, Yujie; Zhao, Qian

2014-01-01

214

Floral transition in maize infected with Sporisorium reilianum disrupts compatibility with this biotrophic fungal pathogen.  

PubMed

Sporisorium reilianum f. sp. zeae is an important biotrophic pathogen that causes head smut disease in maize. Head smut is not obvious until the tassels and ears emerge. S. reilianum has a very long life cycle that spans almost the entire developmental program of maize after the pathogen successfully invades the root. The aim of this study was to understand at a molecular level how this pathogen interacts with the host during its long life cycle, and how this interaction differs between susceptible and resistant varieties of maize after hyphal invasion. We investigated transcriptional changes in the resistant maize line Mo17 at four developmental stages using a maize 70mer-oligonucleotide microarray. We found that there was a lengthy compatible relationship between the pathogen and host until the early eighth-leaf stage. The resistance in Mo17 relied on the assignment of auxin and regulation of flavonoids in the early floral primordium during the early floral transition stage. We propose a model describing the putative mechanism of head smut resistance in Mo17 during floral transition. In the model, the synergistic regulations among auxin, flavonoids, and hyphal growth play a key role in maintaining compatibility with S. reilianum in the resistant maize line. PMID:23354455

Zhang, Shaopeng; Gardiner, Jack; Xiao, Yannong; Zhao, Jiuran; Wang, Fengge; Zheng, Yonglian

2013-05-01

215

Maize ZmRACK1 Is Involved in the Plant Response to Fungal Phytopathogens  

PubMed Central

The receptor for activated C kinase 1 (RACK1) belongs to a protein subfamily containing a tryptophan-aspartic acid-domain (WD) repeat structure. Compelling evidence indicates that RACK1 can interact with many signal molecules and affect different signal transduction pathways. In this study, we cloned a maize RACK1 gene (ZmRACK1) by RT-PCR. The amino acid sequence of ZmRACK1 had seven WD repeats in which there were typical GH (glycine-histidine) and WD dipeptides. Comparison with OsRACK1 from rice revealed 89% identity at the amino acid level. Expression pattern analysis by RT-PCR showed that ZmRACK1 was expressed in all analyzed tissues of maize and that its transcription in leaves was induced by abscisic acid and jasmonate at a high concentration. Overexpression of ZmRACK1 in maize led to a reduction in symptoms caused by Exserohilum turcicum (Pass.) on maize leaves. The expression levels of the pathogenesis-related protein genes, PR-1 and PR-5, increased 2.5–3 times in transgenic maize, and reactive oxygen species production was more active than in the wild-type. Yeast two-hybrid assays showed that ZmRACK1 could interact with RAC1, RAR1 and SGT1. This study and previous work leads us to believe that ZmRACK1 may form a complex with regulators of plant disease resistance to coordinate maize reactions to pathogens.

Wang, Baosheng; Yu, Jingjuan; Zhu, Dengyun; Chang, Yujie; Zhao, Qian

2014-01-01

216

Andreas Acrivos Dissertation Award Talk: Generation of near-wall streamwise vortices by transient growth of streak perturbations  

NASA Astrophysics Data System (ADS)

A new mechanism for generation of near-wall streamwise vortices is presented, based on linear perturbation analysis and direct numerical simulations of turbulent channel flow. Analysis of streaks extracted from fully developed near-wall turbulence indicates that roughly 20 percent of buffer layer streaks exceed the strength threshold for classical normal-mode instability. However, these unstable streaks exhibit only moderate (twofold) normal mode amplification, the growth arrested by viscous cross-diffusion of streak-flank vorticity. An alternative, streak transient growth (STG) mechanism is revealed, capable of producing much larger (tenfold) linear amplification of x-dependent disturbances. Streamwise vortices are generated from the more numerous normal-mode-stable streaks, via a new STG-based scenario: (i) formation of a sheet of streamwise vorticity, (ii) growth of sinuous streak waviness and hence partialu/partialx as STG reaches nonlinear amplitude, and (iii) collapse of the vorticity sheet via stretching by partialu/partialx into streamwise vortices. Notably, the three-dimensional features of the (instantaneous) streamwise vortices of x-alternating sign generated by STG agree well with the (ensemble-averaged) coherent structures educed from fully turbulent flow. The STG-induced formation of internal shear layers, quadrant Reynolds stresses, and other measures of 'bursting' also agree well with fully-developed turbulence, and suggest new possibilities for control of drag and heat transfer.

Schoppa, Wade; Hussain, Fazle

2002-11-01

217

MaizeGDB becomes 'sequence-centric'  

PubMed Central

MaizeGDB is the maize research community’s central repository for genetic and genomic information about the crop plant and research model Zea mays ssp. mays. The MaizeGDB team endeavors to meet research needs as they evolve based on researcher feedback and guidance. Recent work has focused on better integrating existing data with sequence information as it becomes available for the B73, Mo17 and Palomero Toluqueño genomes. Major endeavors along these lines include the implementation of a genome browser to graphically represent genome sequences; implementation of POPcorn, a portal ancillary to MaizeGDB that offers access to independent maize projects and will allow BLAST similarity searches of participating projects’ data sets from a single point; and a joint MaizeGDB/PlantGDB project to involve the maize community in genome annotation. In addition to summarizing recent achievements and future plans, this article also discusses specific examples of community involvement in setting priorities and design aspects of MaizeGDB, which should be of interest to other database and resource providers seeking to better engage their users. MaizeGDB is accessible online at http://www.maizegdb.org. Database URL: http://www.maizegdb.org

Sen, Taner Z.; Andorf, Carson M.; Schaeffer, Mary L.; Harper, Lisa C.; Sparks, Michael E.; Duvick, Jon; Brendel, Volker P.; Cannon, Ethalinda; Campbell, Darwin A.; Lawrence, Carolyn J.

2009-01-01

218

The role of maize root size in phosphorus uptake and productivity of maize/faba bean and maize/wheat intercropping systems.  

PubMed

Interspecific root/rhizosphere interactions affect phosphorus (P) uptake and the productivity of maize/faba bean and maize/wheat intercropping systems. The aim of these experiments was to determine whether manipulation of maize root growth could improve the productivity of the two intercropping systems. Two near isogenic maize hybrids (the larger-rooted T149 and smaller-rooted T222) were intercropped with faba bean and wheat, under conditions of high- and low-P availability. The larger-rooted T149 showed greater competitive ability than the smaller-rooted T222 in both maize/faba bean and maize/wheat intercropping systems. The higher competitive ability of T149 improved the productivity of the maize/faba bean intercropping system in P-sufficient conditions. In maize/wheat intercropping systems, root growth, shoot biomass, and P uptake of maize were inhibited by wheat, regardless of the P-supply. Compared with T222, the larger-rooted T149 suffered less in the intercropping systems. The total biomass of the maize/wheat intercropping system was higher for wheat/T149 than for wheat/T222 under low-P conditions. These data suggested that genetic improvement of maize root size could enhance maize growth and its ability to compete for P resources in maize/faba bean and maize/wheat intercropping systems. In addition, depending on the P availability, larger maize roots could increase the productivity of intercropping systems. PMID:23124795

Zhang, Yikai; Chen, Fanjun; Li, Long; Chen, Yanhua; Liu, Bingran; Zhou, Yuling; Yuan, Lixing; Zhang, Fusuo; Mi, Guohua

2012-11-01

219

PLANT SCIENCES: Promiscuous Maize Chromosomes  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. The intricate chromosome dance that characterizes meiotic cell division involves careful coordination of chromosome pairing, recombination, and synapsis. In their Perspective, Martinez-Perez and Moore discuss new work that identifies the PHS1 protein in maize as being a key player in the coordination of these three events (Pawlowski et al.).

Enrique Martinez-Perez (Stanford University;Department of Developmental Biology); Graham Moore (John Innes Centre;)

2004-01-02

220

On Maize and the Sunflower  

NSDL National Science Digital Library

Agriculture is believed to have arisen independently in six to eight independent centers, including both hemispheres of the Americas. In her Perspective, Piperno discusses recent work, which indicates that maize was domesticated at least 7100 years ago in tropical Mexico, 1000 years earlier than previous data indicated. The sunflower also seems to have been domesticated in Mexico, as well as in eastern North America. Molecular evidence is required to establish the origin of the sunflower with greater certainty.

Dolores R. Piperno (Smithsonian Tropical Research Institute ;)

2001-06-22

221

78 FR 24199 - Streak Products, Inc. v. UTi, United States, Inc.; Notice of Filing of Complaint and Assignment  

Federal Register 2010, 2011, 2012, 2013

...Docket No. 13--04] Streak Products, Inc. v. UTi, United States, Inc.; Notice of Filing of Complaint...hereinafter ``Complainant,'' against UTi, United States, Inc. (``UTi''), hereinafter ``Respondent.''...

2013-04-24

222

Analysis of Streak-Camera Measurement Errors Caused by Misorientation of the Camera Slit with Recording Direction.  

National Technical Information Service (NTIS)

Erroneous data are produced when we analyze streak or smear camera records in which the lack of perpendicularity between the camera slit and the recording direction is not considered. Generated velocity errors are either constant or variable, depending up...

E. A. Igel

1982-01-01

223

New ultra fast x-ray streak camera for the advanced laser light source facility  

NASA Astrophysics Data System (ADS)

The Advanced Laser Light Source (ALLS) infrastructure is a new state-of-the-art multi-beams femtosecond laser facility currently in operation at INRS near Montreal, Canada. The use of a wide range of energy radiation from hard x-ray up to infrared light on the ultrafast time scale requires the development of ultrafast detector diagnostics tools to study the emission spectrum of these sources. To fulfill these requirements, new streak cameras have been developed for ALLS facility. We present the new FXR streak camera which has been specifically developed for ALLS and which is dedicated to x-ray spectroscopy with sub-picosecond time resolution combined with a very high spatial resolution.

Martel, C.; Fourmaux, S.; Lecherbourg, L.; Bandulet, H.; Kieffer, J. C.

2007-09-01

224

Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination  

SciTech Connect

A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

Goldin, F. J. [Livermore Operations, National Security Technologies, LLC, Livermore, California 94550 (United States); Meehan, B. T.; Hagen, E. C. [North Las Vegas Facility, National Security Technologies, LLC, North Las Vegas, Nevada 89030 (United States); Wilkins, P. R. [Lawrence Livermore National Laboratories, Livermore, California 94550 (United States)

2010-10-15

225

Dynamical image-charge effects in attosecond time-resolved streaked photoelectron spectra of metal surfaces  

NASA Astrophysics Data System (ADS)

The release of conduction-band electrons from a metal surface by a sub-femtosecond extreme ultraviolet (XUV) pulse, and their propagation through and near the solid [1], provokes a dielectric response in the solid that acts back on the photoelectron wave packet. We calculated the (wake) potential associated with this photoelectron self-interaction in terms of bulk and surface plasmon excitations and show that it induces a considerable, XUV-frequency-dependent temporal shift in laser-streaked XUV-photoemission spectra [2], suggesting the observation of the ultrafast solid-state dielectric response in contemporary streaked photoemission experiments. [4pt] [1] C.-H. Zhang and U. Thumm, Phys. Rev. Lett. 102, 123601(2009); Phys. Rev. A 80, 032902 (2009).[0pt] [2] C.-H. Zhang and U. Thumm, Phys. Rev. A 82, 043405(2010).

Zhang, Chang-Hua; Thumm, Uwe

2011-06-01

226

Effects of diabatic heating on the ageostrophic circulation of an upper tropospheric jet streak  

NASA Technical Reports Server (NTRS)

Interaction between the mass circulation within a mesoscale convective complex (MCC) and a direct mass circulation in the entrance region of an upper tropospheric polar jet streak was examined within the isentropic structure to investigate mechanisms responsible for linking these two scales of motion. The results establish that latent heating in the MCC modifies the direct mass circulation in the jet streak entrance region through the diabatically induced components of ageostrophic motion analyzed within isentropic coordinates. Within the strong mesoscale mass circulation of each MCC, strong horizontal mass flux convergence into the MCC at low levels is balanced by strong horizontal mass flux divergence away from the convergence at upper levels. Locations of large diabatic heating rates correspond well to the MCC position for each case; diabatic heating forces the upward vertical branch for the mesoscale mass circulation.

Keyser, D. A.; Johnson, D. R.

1982-01-01

227

A distinct tospovirus causing necrotic streak on Alstroemeria sp. in Colombia.  

PubMed

A tospovirus causing necrotic streaks on leaves was isolated from Alstroemeria sp. in Colombia. Infected samples reacted positively with tomato spotted wilt virus (TSWV) antiserum during preliminary serological tests. Further analysis revealed a close serological relationship to tomato chlorotic spot virus (TCSV) and groundnut ringspot virus (GRSV). A major part of the S-RNA segment, encompassing the nucleocapsid (N) protein gene, the 5' untranslated region and a part of the intergenic region 3' of the N gene, was cloned and sequenced. The deduced N protein sequence showed highest amino acid identity (82%) to that of TCSV, indicating that the virus represents a new tospovirus species, for which the name Alstroemeria necrotic streak virus (ANSV) is coined. Phylogenetic analysis based on the N protein sequence revealed that this Alstroemeria-infecting tospovirus clustered with tospoviruses from the American continent. Frankliniella occidentalis was identified as potential vector species for ANSV. PMID:20151164

Hassani-Mehraban, Afshin; Botermans, Marleen; Verhoeven, J Th J; Meekes, Ellis; Saaijer, Janneke; Peters, Dick; Goldbach, Rob; Kormelink, Richard

2010-03-01

228

4D imaging of embryonic chick hearts by streak-mode Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

Recently, we developed the streak-mode Fourier domain optical coherence tomography (OCT) technique in which an area-scan camera is used in a streak-mode to record the OCT spectrum. Here we report the application of this technique to in ovo imaging HH18 embryonic chick hearts with an ultrahigh speed of 1,016,000 axial scans per second. The high-scan rate enables the acquisition of high temporal resolution 2D datasets (1,000 frames per second or 1 ms between frames) and 3D datasets (10 volumes per second), without use of prospective or retrospective gating technique. This marks the first time that the embryonic animal heart has been 4D imaged using a megahertz OCT.

Wang, Rui; Yun, Julie X.; Goodwin, Richard; Markwald, Roger; Borg, Thomas K.; Runyan, Raymond B.; Gao, Bruce

2012-02-01

229

Drag reduction of a 3D bluff body using coherent streamwise streaks  

NASA Astrophysics Data System (ADS)

Separation on the rear-end of an Ahmed body is suppressed by means of large-scale coherent streaks forced on the roof of the model. These streaks originate from an array of suitably shaped cylindrical roughness elements and are amplified by the mean shear through the lift-up effect. Interacting with the mean velocity field at leading order, they induce a strong controlled spanwise modulation. The resulting streaky base flow is observed to sustain the adverse pressure gradient since PIV measurements as well as static wall pressure distributions show that the re-circulation bubble completely vanishes. These modifications of the topology of the flow are associated with a substantial drag reduction, which can be of about 10% when the roughness array is optimally placed on the roof of the bluff body.

Pujals, G.; Depardon, S.; Cossu, C.

2010-11-01

230

Motion streaks do not influence the perceived position of stationary flashed objects.  

PubMed

In the present study, we investigated whether motion streaks, produced by fast moving dots Geisler 1999, distort the positional map of stationary flashed objects producing the well-known motion-induced position shift illusion (MIPS). The illusion relies on motion-processing mechanisms that induce local distortions in the positional map of the stimulus which is derived by shape-processing mechanisms. To measure the MIPS, two horizontally offset Gaussian blobs, placed above and below a central fixation point, were flashed over two fields of dots moving in opposite directions. Subjects judged the position of the top Gaussian blob relative to the bottom one. The results showed that neither fast (motion streaks) nor slow moving dots influenced the perceived spatial position of the stationary flashed objects, suggesting that background motion does not interact with the shape-processing mechanisms involved in MIPS. PMID:22645464

Pavan, Andrea; Bellacosa Marotti, Rosilari

2012-01-01

231

X-ray streak camera temporal resolution improvement using a longitudinal time-dependent field  

SciTech Connect

X-ray streak cameras (XSC) have been known to be one of the fastest detectors forultrafast X-ray science. A number of applications in material science, biochemistry, accelerator physics, require sub-picosecond resolution to study new phenomena. Inthis paper, we report on a new method which can potentially improve the temporal resolution of a streak camera down to 100 femtoseconds. This method uses a time-dependent acceleration field to lengthen the photoelectron bunch, significantlyimproving the time resolution as well as reducing the time dispersion caused byinitial energy spread and the effects fromthe space charge forces. A computer simulation of an XSC using this method shows significant improvement in the resolution.

Qiang, Ji; Qiang, J.; Byrd, J.M.; Feng, J.; Huang, G.

2008-05-09

232

Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination  

NASA Astrophysics Data System (ADS)

A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments.

Goldin, F. J.; Meehan, B. T.; Hagen, E. C.; Wilkins, P. R.

2010-10-01

233

Time-resolved spectra of dense plasma focus using spectrometer, streak camera, and CCD combination.  

PubMed

A time-resolving spectrographic instrument has been assembled with the primary components of a spectrometer, image-converting streak camera, and CCD recording camera, for the primary purpose of diagnosing highly dynamic plasmas. A collection lens defines the sampled region and couples light from the plasma into a step index, multimode fiber which leads to the spectrometer. The output spectrum is focused onto the photocathode of the streak camera, the output of which is proximity-coupled to the CCD. The spectrometer configuration is essentially Czerny-Turner, but off-the-shelf Nikon refraction lenses, rather than mirrors, are used for practicality and flexibility. Only recently assembled, the instrument requires significant refinement, but has now taken data on both bridge wire and dense plasma focus experiments. PMID:21034059

Goldin, F J; Meehan, B T; Hagen, E C; Wilkins, P R

2010-10-01

234

Integration of Banana Streak Badnavirus into the MusaGenome: Molecular and Cytogenetic Evidence  

Microsoft Academic Search

Breeding and tissue culture of certain cultivars of bananas (Musa) have led to high levels of banana streak badnavirus (BSV) infection in progeny from symptomless parents. BSV DNA hybridized to genomic DNA of one such parent, Obino l'Ewai, suggesting integration of viral sequences. Sequencing of clones of Obino l'Ewai genomic DNA revealed an interface between BSV andMusasequences and a complex

Glyn Harper; Julian O. Osuji; Roger Hull

1999-01-01

235

Comparison of cesium iodide and gold photocathodes for x-ray streak cameras  

Microsoft Academic Search

X-ray streak cameras at Lawrence Livermore Laboratory use gold transmission photocathodes for x-ray detection. Other photocathode materials which might provide improved sensitivity without loss of temporal resolution are of interest. Of particular interest are dielectrics such as cesium iodide. Simultaneous measurements of the sensitivity to 500 eV x-rays of both gold and cesium iodide photocathodes in the LLL Soft X-ray

G. L. Stradling; H. Medecki; D. T. Attwood; R. L. Kauffman; B. L. Henke

1979-01-01

236

Isolation of polymorphic tetranucleotide microsatellite markers for the streak-necked flycatcher Mionectes striaticollis  

Microsoft Academic Search

We have isolated 11 polymorphic microsatellite markers for the streak-necked flycatcher Mionectes striaticollis from genomic libraries enriched for either (AACC) n , (AAGG) n or (AAAG) n repetitive elements. The number of alleles ranged from four to 14 per locus with the observed heterozygosity ranging from 0.38 to 1.00. These markers will be useful for analysis of questions concerning population

CAROLYNE BARDELEBEN; MELISSA M. GRAY

2005-01-01

237

Structure and Temporal Dynamics of Populations within Wheat Streak Mosaic Virus Isolates  

Microsoft Academic Search

Variation within the Type and Sidney 81 strains of wheat streak mosaic virus was assessed by single-strand conformation polymorphism (SSCP) analysis and confirmed by nucleotide sequencing. Limiting-dilution subisolates (LDSIs) of each strain were evaluated for polymorphism in the P1, P3, NIa, and CP cistrons. Different SSCP patterns among LDSIs of a strain were associated with single-nucleotide substitutions. Sidney 81 LDSI-S10

JEFFREY S. HALL; ROY FRENCH; T. JACK MORRIS; DRAKE C. STENGER

2001-01-01

238

Streak camera technique to measure plastic plate velocities as a continuum  

Microsoft Academic Search

A technique was developed to measure velocities of thin plastic plates as a continuum with a streak camera at 20 mm\\/..mu.. s and 8.4X magnification. The plastic plates are bonded to an exploding foil with a transparent cylindrical barrel located over the exploding foil\\/plastic plate laminate on the side of the plastic plate. When the foil is exploded, a plastic

Paisley

1976-01-01

239

Ultrafast x-ray streak camera for use in ultrashort laser-produced plasma research  

Microsoft Academic Search

In recent years there has been growing interest in energetic (?100 eV), temporally short (<10 ps) x rays produced by ultrashort laser-produced plasmas. The detection and temporal dispersion of the x rays using x-ray streak cameras has been limited to a resolution of 2 ps, primarily due to the transit time dispersion of the electrons between the photocathode and the

Ronnie Shepherd; Rex Booth; Dwight Price; Mark Bowers; Don Swan; Jim Bonlie; Bruce Young; Jim Dunn; Bill White; Richard Stewart

1995-01-01

240

Note: A technique to capture and compose streak images of explosive events with unpredictable timing  

Microsoft Academic Search

The authors describe a method to capture optical data and construct digitized streak images for analysis of high-speed phenomena with unpredictable timing by using a high-speed video camera and software routines. Advances in high-speed video camera technology have led to development of cameras with frame rates (1×106 frames per second) and spatial resolution (1280×800 pixels) suitable to capture fast phenomena,

Gary R. Parker; Blaine W. Asay; Peter M. Dickson

2010-01-01

241

Optical laser-based THz streaking for full FEL pulse characterization  

NASA Astrophysics Data System (ADS)

Full temporal characterization of ultrashort, high brilliance x-ray pulses at Free Electron Laser (FEL) facilities, while elusive, will underpin their future use in experiments ranging from single-molecule imaging to extreme timescale x-ray science. This issue is especially acute when confronted with the characteristics of current generation FELs operating on the principle of self-amplified spontaneous emission, as most parameters fluctuate from pulse to pulse. We have achieved this crucial characterization by extending the techniques of photoelectron streaking originally developed for attosecond spectroscopy. In our experiments, high-intensity, optical laser generated single-cycle THz pulses were used to broaden and shift -- or streak -- the photoelectron spectrum of a noble gas target ionized by the incident FEL pulse. Due to the relatively long rise time of the THz streaking field (˜600 fs), these measurements allow for the arrival-time and temporal profile of femtosecond to hundred-femtosecond FEL pulses to be determined simultaneously and on a single-shot basis. Optical laser-based THz streaking is suited for use over the full range of photon energies and pulse durations produced at FELs, from XUV to the hard x-ray regime. Experiments have now been performed at the hard x-ray Linac-Coherent Light Source at the SLAC National Accelerator Laboratory as well as at the XUV Free Electron Laser in Hamburg. Distinct temporal features as short as 50 fs FWHM have been observed in the raw pulse profile prior to any correction for instrument resolution. While these first measurements have been resolution-limited, the potential for improvement to access the sub 10-fs range has also been demonstrated, which would allow for characterization and effective application of the shortest predicted, few-femtosecond x-ray pulses in the near future.

Cavalieri, Adrian

2012-06-01

242

Molecular organization of the cholesteryl ester droplets in the fatty streaks of human aorta.  

PubMed Central

X-ray diffraction patterns from human arterial specimens containing atherosclerotic fatty streak lesions exhibited a single sharp reflection, corresponding to a structural spacing of about 35 A. Specimens without lesions did not. When specimens with fatty streaks were heated, an order-to-disorder phase transition was revealed by the disappearance of the sharp reflection. The transition was thermally reversible and its temperature varied from aorta to aorta over a range from 28 degrees to 42 degrees C. Since cholesteryl ester droplets are a major component of fatty streaks, comparison studies were made of the diffraction behavior from pure cholesteryl esters. We found that the diffraction patterns of the fatty streak material could be accounted for by the organization of the cholesteryl esters into a liquid-crystalline smectic phase that melts from the smectic to a less ordered phase upon heating. When combined with the conclusions of others from polarized light microscopy, our study shows that a droplet in the smectic phase has well-defined concentric layers of lipid molecules. In each layer, the long axes of the molecules have a net radial orientation with respect to the droplet, but the side-to-side organization is disordered. We suggest that the accessibility of portions of the lipids for specific binding to enzymes or transport proteins may be restricted when they are in the smectic state, and that exchange of lipids with surrounding membranes or other potential binding sites may likewise be inhibited. The restriction in the smectic phase should be greater than in the less ordered phases that exist at higher temperatures. Images

Engelman, D M; Hillman, G M

1976-01-01

243

Ultrafast photonic-crystal fiber light flash for streak-camera fluorescence measurements.  

PubMed

Photonic-crystal fibers (PCFs) provide a high efficiency of frequency upconversion of femtosecond Cr: forsterite laser pulses through the emission of dispersive waves by solitons and third-harmonic generation. Dispersion management allows the central wavelength of the frequency-upconverted signal in PCF output to be tuned within the range of wavelengths from 400 to 900 nm. PCF frequency shifters are employed as excitation sources for time-resolved fluorescence streak-camera measurements on fluorescein solution. PMID:19498569

Konorov, Stanislav; Ivanov, Anatoly; Ivanov, Denis; Alfimov, Mikhail; Zheltikov, Aleksei

2005-07-25

244

Instability of streaks in pipe flow of shear-thinning fluids  

NASA Astrophysics Data System (ADS)

This study is motivated by recent experimental results dealing with the transition to turbulence in a pipe flow of shear-thinning fluids, where a streaky flow with an azimuthal wave number n=1 is observed in the transitional regime. Here, a linear stability analysis of pipe flow of shear-thinning fluids modulated azimuthally by finite amplitude streaks is performed. The shear-thinning behavior of the fluid is described by the Carreau model. The streaky base flows considered are obtained from two-dimensional direct numerical simulation using finite amplitude longitudinal rolls as the initial condition and by extracting the velocity field at time tmax, where the amplitude of the streaks reaches its maximum, denoted by Amax. It is found that the amplitude Amax increases with increasing Reynolds number as well as with increasing amplitude E0 of the initial longitudinal rolls. For sufficiently large streaks amplitude, streamwise velocity profiles develop inflection points, leading to instabilities. Depending on the threshold amplitude Ac, two different modes may trigger the instability of the streaks. If Ac exceeds approximately 41.5% of the centerline velocity, the instability mode is located near the axis of the pipe, i.e., it is a “center mode.” For weaker amplitude Ac, the instability mode is located near the pipe wall, in the region of highest wall normal shear, i.e., it is a “wall mode.” The threshold amplitude Ac decreases with increasing shear-thinning effects. The energy equation analysis indicates that (i) wall modes are driven mainly by the work of the Reynolds stress against the wall normal shear and (ii) for center modes, the contribution of the normal wall shear remains dominant; however, it is noted that the contribution of the Reynolds stress against the azimuthal shear increases with increasing shear-thinning effects.

López Carranza, S. N.; Jenny, M.; Nouar, C.

2013-08-01

245

High-Speed Observer: Automated Streak Detection for the Aerospike Engine  

NASA Technical Reports Server (NTRS)

A high-frame-rate digital video camera, installed on test stands at Stennis Space Center (SSC), has been used to capture images of the aerospike engine plume during test. These plume images are processed in real time to detect and differentiate anomalous plume events. Results indicate that the High-Speed Observer (HSO) system can detect anomalous plume streaking events that are indicative of aerospike engine malfunction.

Rieckhoff, T. J.; Covan, M. A.; OFarrell, J. M.

2001-01-01

246

Cheap streak camera based on the LD-S-10 intensifier tube  

Microsoft Academic Search

Basic properties of a new streak camera and its test results are reported. To intensify images on its screen, we employed modular G1 tubes, the LD-A-1.0 and LD-A-0.33, enabling magnification of 1.0 and 0.33, respectively. If necessary, the LD-A-0.33 tube may be substituted by any other image intensifier of the LDA series, the choice to be determined by the size

Boris E. Dashevsky; Mikhail I. Krutik; Alexander L. Surovegin

1992-01-01

247

High temporal resolution and streak-free four-dimensional cone-beam computed tomography  

PubMed Central

Cone-beam computed tomography (CBCT) has been clinically used to verify patient position and to localize the target of treatment in image-guided radiation therapy (IGRT). However, when the chest and the upper abdomen are scanned, respiratory-induced motion blurring limits the utility of CBCT. In order to mitigate this blurring, respiratory-gated CBCT, i.e. 4D CBCT, was introduced. In 4D CBCT, the cone-beam projection data sets acquired during a gantry rotation are sorted into several respiratory phases. In these gated reconstructions, the number of projections for each respiratory phase is significantly reduced. Consequently, undersampling streaking artifacts are present in the reconstructed images, and the image contrast resolution is also significantly compromised. In this paper, we present a new method to simultaneously achieve both high temporal resolution (~100 ms) and streaking artifact-free image volumes in 4D CBCT. The enabling technique is a newly proposed image reconstruction method, i.e. prior image constrained compressed sensing (PICCS), which enables accurate image reconstruction using vastly undersampled cone-beam projections and a fully sampled prior image. Using PICCS, a streak-free image can be reconstructed from 10–20 cone-beam projections while the signal-to-noise ratio is determined by a denoising feature of the selected objective function and by the prior image, which is reconstructed using all of the acquired cone-beam projections. This feature of PICCS breaks the connection between the temporal resolution and streaking artifacts’ level in 4D CBCT. Numerical simulations and experimental phantom studies have been conducted to validate the method.

Leng, Shuai; Tang, Jie; Zambelli, Joseph; Nett, Brian; Tolakanahalli, Ranjini; Chen, Guang-Hong

2009-01-01

248

2-ps Hard X-Ray Streak Camera Measurements at Sector 7 Beamline of the Advanced Photon Source  

SciTech Connect

A hard X-ray streak camera capable of 2-ps time resolution is in operation at the Sector 7 beamline of the Advanced Photon Source. It is used for laser-pump, X-ray probe experiments using the Ti:Sapphire femtosecond laser system installed on the beamline. This streak camera, combined with standardized and prealigned experimental setups, can perform time-resolved liquid-phase absorption spectroscopy, reflectivity, and diffraction experiments.

Chollet, M.; Ahr, B.; Walko, D.A.; Rose-Petruck, C.; Adams, B.

2011-08-02

249

Ultrafast two-dimensional x-ray imaging with x-ray streak cameras for laser fusion research (invited)  

Microsoft Academic Search

Ultrafast two-dimensional x-ray imaging is required for diagnosing laser-driven inertial confinement fusion plasmas. Image sampling technique with x-ray streak cameras can meet this requirement. Multi-imaging x-ray streak camera method (MIXS) with temporal and spatial resolutions of 10 ps and 15 ?m, respectively, has been developed and successfully utilized for diagnosing the uniformity and heating process of the imploded core plasmas.

H. Shiraga; N. Miyanaga; M. Heya; M. Nakasuji; Y. Aoki; H. Azechi; T. Yamanaka; K. Mima

1997-01-01

250

Grazing-incidence mirror streak camera diagnostic for emission measurements of imploding z pinches on the Sandia Z-machine  

Microsoft Academic Search

A soft x-ray (0.1-1 keV) streak camera using a grazing-incidence mirror has been developed for the Sandia Z facility, a 20 MA, 100 ns rise-time accelerator that can generate >200 TW,2 MJ, x-ray pulses. The streak camera is used to measure with one dimension of spatial resolution the continuous time history of sub-kilo-electron-volts emission from z-pinch and radiation flow experiments.

D. F. Wenger; D. B. Sinars; K. L. Keller; R. A. Aragon; L. E. Ruggles; W. W. Simpson; P. H. Primm; J. L. Porter

2004-01-01

251

Priming of Production in Maize of Volatile Organic Defence Compounds by the Natural Plant Activator cis-Jasmone  

PubMed Central

cis-Jasmone (CJ) is a natural plant product that activates defence against herbivores in model and crop plants. In this study, we investigated whether CJ could prime defence in maize, Zea mays, against the leafhopper, Cicadulina storeyi, responsible for the transmission of maize streak virus (MSV). Priming occurs when a pre-treatment, in this case CJ, increases the potency and speed of a defence response upon subsequent attack on the plant. Here, we tested insect responses to plant volatile organic compounds (VOCs) using a Y-tube olfactometer bioassay. Our initial experiments showed that, in this system, there was no significant response of the herbivore to CJ itself and no difference in response to VOCs collected from unexposed plants compared to CJ exposed plants, both without insects. VOCs were then collected from C. storeyi-infested maize seedlings with and without CJ pre-treatment. The bioassay revealed a significant preference by this pest for VOCs from infested seedlings without the CJ pre-treatment. A timed series of VOC collections and bioassays showed that the effect was strongest in the first 22 h of insect infestation, i.e. before the insects had themselves induced a change in VOC emission. Chemical analysis showed that treatment of maize seedlings with CJ, followed by exposure to C. storeyi, led to a significant increase in emission of the defensive sesquiterpenes (E)-(1R,9S)-caryophyllene, (E)-?-bergamotene, (E)-?-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene, known to act as herbivore repellents. The chemical analysis explains the behavioural effects observed in the olfactometer, as the CJ treatment caused plants to emit a blend of VOCs comprising more of the repellent components in the first 22 h of insect infestation than control plants. The speed and potency of VOC emission was increased by the CJ pre-treatment. This is the first indication that CJ can prime plants for enhanced production of defensive VOCs antagonist towards herbivores.

Oluwafemi, Sunday; Dewhirst, Sarah Y.; Veyrat, Nathalie; Powers, Stephen; Bruce, Toby J. A.; Caulfield, John C.; Pickett, John A.; Birkett, Michael A.

2013-01-01

252

Optical fiducial timing system for X-ray streak cameras with aluminum coated optical fiber ends  

DOEpatents

An optical fiducial timing system is provided for use with interdependent groups of X-ray streak cameras (18). The aluminum coated (80) ends of optical fibers (78) are positioned with the photocathodes (20, 60, 70) of the X-ray streak cameras (18). The other ends of the optical fibers (78) are placed together in a bundled array (90). A fiducial optical signal (96), that is comprised of 2.omega. or 1.omega. laser light, after introduction to the bundled array (90), travels to the aluminum coated (82) optical fiber ends and ejects quantities of electrons (84) that are recorded on the data recording media (52) of the X-ray streak cameras (18). Since both 2.omega. and 1.omega. laser light can travel long distances in optical fiber with only a slight attenuation, the initial arial power density of the fiducial optical signal (96) is well below the damage threshold of the fused silica or other material that comprises the optical fibers (78, 90). Thus the fiducial timing system can be repeatably used over long durations of time.

Nilson, David G. (Oakland, CA); Campbell, E. Michael (Pleasanton, CA); MacGowan, Brian J. (Livermore, CA); Medecki, Hector (Livermore, CA)

1988-01-01

253

Retention of stem cell plasticity in avian primitive streak cells and the effects of local microenvironment.  

PubMed

Primitive streak (PS) is the first structure occurring in embryonic gastrulation, in which the epiblast cells undergo the epithelial-mesenchymal transition to become the loose mesoderm cells subsequently. Because the mesoderm cells departing from different portions of PS are blessed with disparate migration trajectory and differentiation fate, one question is when the cell fate is determinated. To understand whether the cell fate and cell migration pattern will be alternated along with the microenvironment transformation, the traditional transplantation technology was used to replace the anterior PS cells in HH4 host embryo using posterior PS tissue labeled by green fluorescent protein (GFP) in the same stage donor embryo, and then, we tracked the migration trajectory of the GFP-positive cells with fluorescence stereomicroscope after incubation, and eventually verified the cell contribution from the transplants with in situ hybridization and immunocytochemistry. The same experimental strategy applied for posterior PS site replacement in host embryo. We found that the transplanted posterior PS cells to anterior part of streak followed the anterior PS cell migration pattern rather than kept its posterior streak cell migration trajectory, and so did vice versa. In addition, the transplants were involved in the contribution to the subsequent organogenesis as the local PS tissues affirmed by specific expression of myocardial or hematopoietic markers. Therefore, our data strongly suggest that the PS cells still keep stem cell plasticity during gastrulation and the eventual cell fate will depend on the spatial gene expression within local microenvironment along with development. PMID:23382139

Wang, Xiao-Yu; Li, Yan; Ma, Zheng-Lai; Wang, Li-Jing; Chuai, Manli; Münsterberg, Andrea; Geng, Jian-Guo; Yang, Xuesong

2013-03-01

254

Oct4 Is Required ~E7.5 for Proliferation in the Primitive Streak  

PubMed Central

Oct4 is a widely recognized pluripotency factor as it maintains Embryonic Stem (ES) cells in a pluripotent state, and, in vivo, prevents the inner cell mass (ICM) in murine embryos from differentiating into trophectoderm. However, its function in somatic tissue after this developmental stage is not well characterized. Using a tamoxifen-inducible Cre recombinase and floxed alleles of Oct4, we investigated the effect of depleting Oct4 in mouse embryos between the pre-streak and headfold stages, ?E6.0–E8.0, when Oct4 is found in dynamic patterns throughout the embryonic compartment of the mouse egg cylinder. We found that depletion of Oct4 ?E7.5 resulted in a severe phenotype, comprised of craniorachischisis, random heart tube orientation, failed turning, defective somitogenesis and posterior truncation. Unlike in ES cells, depletion of the pluripotency factors Sox2 and Oct4 after E7.0 does not phenocopy, suggesting that ?E7.5 Oct4 is required within a network that is altered relative to the pluripotency network. Oct4 is not required in extraembryonic tissue for these processes, but is required to maintain cell viability in the embryo and normal proliferation within the primitive streak. Impaired expansion of the primitive streak occurs coincident with Oct4 depletion ?E7.5 and precedes deficient convergent extension which contributes to several aspects of the phenotype.

DeVeale, Brian; Brokhman, Irina; Mohseni, Paria; Babak, Tomas; Yoon, Charles; Lin, Anthony; Onishi, Kento; Tomilin, Alexey; Pevny, Larysa; Zandstra, Peter W.; Nagy, Andras; van der Kooy, Derek

2013-01-01

255

Maize Research and Development in Pakistan.  

National Technical Information Service (NTIS)

Maize is frequently cited as a crop that was bypassed by Pakistan's green revolutions in wheat and rice, and more recently, cotton. While the returns to investments in maize research and extension have been positive, they have not been nearly as great as ...

1989-01-01

256

A meteorologically driven maize stress indicator model  

NASA Technical Reports Server (NTRS)

A maize soil moisture and temperature stress model is described which was developed to serve as a meteorological data filter to alert commodity analysts to potential stress conditions in the major maize-producing areas of the world. The model also identifies optimum climatic conditions and planting/harvest problems associated with poor tractability.

Taylor, T. W.; Ravet, F. W. (principal investigators)

1981-01-01

257

Comparative Genome Mapping of Sorghum and Maize  

Microsoft Academic Search

Linkage relationships were determined among 85 maize low copy number nuclear DNA probes and seven isozyme loci in an FP population derived from a cross of Sorghum bicolor ssp. bicolor X S. bicolor ssp. arundinaceum. Thirteen linkage groups were defined, three more than the 10 chromosomes of sorghum. Use of maize DNA probes to produce the sorghum linkage map allowed

Richard Whitkus; John Doebleyt; Michael Lee

1992-01-01

258

Modeling maize canopy 3D architecture  

Microsoft Academic Search

The aim of this study is to develop a 3D model of maize (Zea mays) canopy structure for accurate reflectance simulations. We focus on fully developed maize plants without paying attention to the reproductive organs. Several experiments are used to describe the dimension, shape, position and orientation of the leaves and stems. They correspond to a wide range of cultural

Mar??a Luisa España; Frédéric Baret; Franck Aries; M. Chelle; B. Andrieu; Laurent Prévot

1999-01-01

259

Comparison of productivity between tropical and temperate maize  

Microsoft Academic Search

To Identify the difference in maize productivity between tropical and temperate regions, maize (Zea mays L.) plants were grown in two regions: in the fields of two CIMMYT Experimental Stations in Mexico and in a field of Hokkaido University in northern Japan. Results obtained were as follows.1. The grain yield of tropical maize was lower than that of temperate maize.

Mitsuru Osaki

1995-01-01

260

Adoption of improved maize varieties in the hills of Nepal  

Microsoft Academic Search

Maize (Zea mays L.) is the most important cereal crop in the hills of Nepal, where the grain is used for human consumption and the stover for animal fodder. Maize farms are small, and population pressure necessitates the intensification of existing farming systems. Maize research directed at developing technologies for maize production began in Nepal in 1965. In 2000, a

J. K. Ransom; K. Paudyal; K. Adhikari

2003-01-01

261

Application of the continuous wavelet transform for analysis of formation and streaks in fibrous web structures  

NASA Astrophysics Data System (ADS)

The purpose of this research was to develop a method to characterize the distribution of material in paper and other fibrous webs using a method based on the continuous wavelet transform. While investigating this subject, two major advantages of the method were discovered. The first is the ability of the method to accommodate stochastic, non-stationary data sets by spatial localization of the spectral analysis. The second is its ability to distinguish flocs and lightweight region in the spectral analysis. The impetus for using continuous wavelet transform to analyze the structure of webs, and especially machine made papers, was the need to relate the final structure of the product to the forming processes. Given that objective, an existing method that separates the static and the stochastic components of the wavelet based energy spectrum of the cross machine profile was enhanced to account for additional characteristics of machine direction streaks. These included streak intermittency, off axis orientation and oscillation of the streak position in the cross machine direction. The method was validated using simulated and measured images of the paper formation (distribution of mass). This permitted the existing problem of separating different types of streaks from the wavelet energy spectra. The potential for application of the wavelet algorithm for online processing of webs was also examined. The zone-variance effect on the quality of separation of various streaks was studied. Descriptive parameters that can simplify and effectively represent the energy spectra were described and demonstrated. Machine direction variability that was not identified in the simultaneous space-scale analysis can now be incorporated in the analysis by using the spottiness parameter. The continuous wavelet transform was also used to delineate between heavy weight (floc) and lightweight zones to provide separate spectra for each. The manner in which these spectra change with floc geometry and density was tested by using simulated and actual formation images. Significant difference in the spectra reflected the manner in which the flocs were formed. This will find significant use for characterizing differences in processes that influence the uniformity of the structure and will allow the identification of process improvements.

Hasan, Asif

262

Pests, pesticide use and alternative options in European maize production: current status and future prospects  

Microsoft Academic Search

Political efforts are made in the European Union (EU) to reduce pesticide use and to increase the implementation of integrated pest management (IPM). Within the EU project ENDURE, research priorities on pesticide reduction are defined. Using maize, one of the most important crops in Europe, as a case study, we identified the most serious weeds, arthropod pests, and fungal diseases

M. Meissle; P. Mouron; T. Musa; Weide van der R. Y; J. A. M. Groten

2010-01-01

263

Experimentally-Induced Metabolic Acidosis Does not Alter Aortic Fatty Streak Formation in High-Cholesterol Fed Rabbits  

PubMed Central

Objective(s) Cardiovascular disease causes a major clinical problem in patients with end stage renal disease. Since metabolic acidosis is very common in patients with end stage renal disease, we aimed to investigate the effect of experimentally-induced metabolic acidosis on serum lipid profile and aortic fatty streak (FS) formation in normal and high-cholesterol fed rabbits. Materials and Methods Twenty-four male rabbits were divided into four groups (n=6 each): (1) normal diet (ND): (2) hypercholesterolemic diet (HCD) (1%): (3) ND plus acidemic diet: (4) HCD plus acidemic diet. Metabolic acidosis was induced by adding 0.75% NH4Cl in drinking water. After 4 weeks, blood samples were taken and thoracic aortae were dissected for histological examinations. Results Results showed that in the animals who received NH4Cl, metabolic acidosis was successfully induced. Serum total cholesterol and low density lipoprotein (LDL) concentrations in HCD groups were significantly higher than ND groups (P<0.05) and acidosis did not significantly change serum lipid levels neither in ND nor in HCD animals (P>0.05). Histological examination of aortae showed higher mean average grades of pathological evaluation in HCD than ND groups (2.1±0.16 vs. 0±0; P<0.05). Acidosis did not further increase FS formation in HCD groups (P >0.05). Conclusion In this model of experimentally-induced metabolic acidosis, acidosis could not increase FS formation in HCD animals and it seems that it does not interfere in progression of atherosclerosis process.

Khazaei, Majid; Nematbakhsh, Mehdi

2012-01-01

264

Antimicrobial activity of pyrrocidines from Acremonium zeae against endophytes and pathogens of maize.  

PubMed

Acremonium zeae produces pyrrocidines A and B, which are polyketide-amino acid-derived antibiotics, and is recognized as a seedborne protective endophyte of maize which augments host defenses against microbial pathogens causing seedling blights and stalk rots. Pyrrocidine A displayed significant in vitro activity against Aspergillus flavus and Fusarium verticillioides in assays performed using conidia as inoculum, with pyrrocidine A being more active than B. In equivalent assays performed with conidia or hyphal cells as inoculum, pyrrocidine A revealed potent activity against major stalk and ear rot pathogens of maize, including F. graminearum, Nigrospora oryzae, Stenocarpella (Diplodia) maydis, and Rhizoctonia zeae. Pyrrocidine A displayed significant activity against seed-rotting saprophytes A. flavus and Eupenicillium ochrosalmoneum, as well as seed-infecting colonists of the phylloplane Alternaria alternata, Cladosporium cladosporioides, and Curvularia lunata, which produces a damaging leaf spot disease. Protective endophytes, including mycoparasites which grow asymptomatically within healthy maize tissues, show little sensitivity to pyrrocidines. Pyrrocidine A also exhibited potent activity against Clavibacter michiganense subsp. nebraskense, causal agent of Goss's bacterial wilt of maize, and Bacillus mojaviense and Pseudomonas fluorescens, maize endophytes applied as biocontrol agents, but were ineffective against the wilt-producing bacterium Pantoea stewartii. PMID:19055442

Wicklow, Donald T; Poling, Stephen M

2009-01-01

265

Production of highly concentrated, heat stable hepatitis B surface antigen in maize  

PubMed Central

Summary Plant-based oral vaccines are a promising emergent technology that could help alleviate disease burden worldwide by providing a low-cost, heat stable, oral alternative to parenterally administered commercial vaccines. Here we describe high-level accumulation of the hepatitis B surface antigen (HBsAg) at a mean concentration of 0.51%TSP in maize T1 seeds using an improved version of the globulin1 promoter. This concentration is more than four-fold higher than any previously reported lines. HBsAg expressed in maize seeds was extremely heat stable, tolerating temperatures up to 55°C for one month without degradation. Optimal heat stability was achieved after oil extraction of ground maize material, either by supercritical fluid extraction or hexane treatment. The contributions of this material towards the development of a practical oral vaccine delivery system are discussed.

Hayden, Celine A.; Egelkrout, Erin M.; Moscoso, Alessa M.; Enrique, Cristina; Keener, Todd K.; Jimenez-Flores, Rafael; Wong, Jeffrey C.; Howard, John A.

2012-01-01

266

Natural Genetic Variation in Lycopene Epsilon Cyclase Tapped for Maize Biofortification  

PubMed Central

Dietary vitamin A deficiency causes eye disease in 40 million children each year and places 140 to 250 million at risk for health disorders. Many children in sub-Saharan Africa subsist on maize-based diets. Maize displays considerable natural variation for carotenoid composition, including vitamin A precursors ?-carotene, ?-carotene, and ?-cryptoxanthin. Through association analysis, linkage mapping, expression analysis, and mutagenesis, we show that variation at the lycopene epsilon cyclase (lcyE) locus alters flux down ?-carotene versus ?-carotene branches of the carotenoid pathway. Four natural lcyE polymorphisms explained 58% of the variation in these two branches and a threefold difference in provitamin A compounds. Selection of favorable lcyE alleles with inexpensive molecular markers will now enable developing-country breeders to more effectively produce maize grain with higher provitamin A levels.

Harjes, Carlos E.; Rocheford, Torbert R.; Bai, Ling; Brutnell, Thomas P.; Kandianis, Catherine Bermudez; Sowinski, Stephen G.; Stapleton, Ann E.; Vallabhaneni, Ratnakar; Williams, Mark; Wurtzel, Eleanore T.; Yan, Jianbing; Buckler, Edward S.

2010-01-01

267

Measuring 8-250 ps short pulses using a high-speed streak camera on kilojoule, petawatt-class laser systems  

NASA Astrophysics Data System (ADS)

Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a more-uniform streak image and enables one to characterize space-charge-induced pulse-broadening effects.

Qiao, J.; Jaanimagi, P. A.; Boni, R.; Bromage, J.; Hill, E.

2013-07-01

268

Measuring 8–250 ps short pulses using a high-speed streak camera on kilojoule, petawatt-class laser systems  

SciTech Connect

Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a more-uniform streak image and enables one to characterize space-charge-induced pulse-broadening effects.

Qiao, J.; Jaanimagi, P. A.; Boni, R.; Bromage, J.; Hill, E. [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)] [Laboratory for Laser Energetics, University of Rochester, 250 East River Road, Rochester, New York 14623-1299 (United States)

2013-07-15

269

Measuring 8-250 ps short pulses using a high-speed streak camera on kilojoule, petawatt-class laser systems.  

PubMed

Short-pulse measurements using a streak camera are sensitive to space-charge broadening, which depends on the pulse duration and shape, and on the uniformity of photocathode illumination. An anamorphic-diffuser-based beam-homogenizing system and a space-charge-broadening calibration method were developed to accurately measure short pulses using an optical streak camera. This approach provides a more-uniform streak image and enables one to characterize space-charge-induced pulse-broadening effects. PMID:23902041

Qiao, J; Jaanimagi, P A; Boni, R; Bromage, J; Hill, E

2013-07-01

270

Tissue-specific expression in transgenic maize of four endosperm promoters from maize and rice  

Microsoft Academic Search

The tissue-specific, developmental, and genetic control of four endosperm-active genes was studied via expression of GUS reporter genes in transgenic maize plants. The transgenes included promoters from the maize granule-bound starch synthase (Waxy) gene (zmGBS), a maize 27 kDa zein gene (zmZ27), a rice small subunit ADP-glucose pyrophosphorylase gene (osAGP) and the rice glutelin 1 gene (osGT1). Most plants had

Douglas A. Russell; Michael E. Fromm

1997-01-01

271

Investigations on Genetically Modified Maize (Bt-Maize) in Pig Nutrition: Fattening Performance and Slaughtering Results  

Microsoft Academic Search

A grower finisher performance trial with forty-eight pigs was designed to compare the growth performance of pigs fed diets containing either genetically modified (GM) Bt-maize (NX6262) or its parental maize (Prelude) line. During the experiment, the pigs were fed with a grower and a finisher diet both containing 70% maize investigated in a previously study which showed that they contained

T. Reuter; Karen Aulrich; A. Berk

2002-01-01

272

Bioactive metabolites from Stenocarpella maydis, a stalk and ear rot pathogen of maize.  

PubMed

Stenocarpella maydis is a fungal pathogen of major importance that causes a dry-rot of maize ears and is associated with a neuromycotoxicosis in cattle grazing harvested maize fields in southern Africa and Argentina. In an effort to investigate the potential roles of S. maydis metabolites in the fungal disease cycle, ethyl acetate extracts of solid-substrate fermentations of several S. maydis isolates from maize grown in the United States were found to exhibit significant phytotoxic, antifungal, and antiinsectan activity. Chemical investigations of extracts of S. maydis isolates from Illinois and Nebraska led to the isolation or detection of the known metabolites diplodiatoxin, chaetoglobosins K and L, and (all-E)-trideca-4,6,10,12-tetraene-2,8-diol as major components. A culture of Stenocarpella macrospora from maize grown in Zambia produced diplosporin and chaetoglobosins K and L as major components that were isolated. Diplodiatoxin produced significant lesions in a maize leaf puncture wound assay. Diplosporin and chaetoglobosin K displayed moderate antiinsectan activity in dietary assays against the fall armyworm Spodoptera frugiperda, while chaetoglobosin K exhibited significant antifungal activity against Aspergillus flavus and Fusarium verticillioides. Using LC-ESIMS and (1)H NMR data, diplodiatoxin was detected as a major component in S. maydis-rotted grain, stalks, and stalk residues. This constitutes the first report of chaetoglobosins K and L from S. maydis, of (all-E)-trideca-4,6,10,12-tetraene-2,8-diol from Stenocarpella, and the first reported detection of diplodiatoxin, or any other Stenocarpella metabolite, in diseased maize seeds and stalk tissues. PMID:21315311

Wicklow, Donald T; Rogers, Kristina D; Dowd, Patrick F; Gloer, James B

2011-02-01

273

Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems  

SciTech Connect

This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 {mu}m) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ('hotspot') was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm{sup 2}/steradian/nm). Error analysis shows this method to be accurate to within +/- 20%, which represents a high level of accuracy for this type of measurement.

Johnston, Mark D.; Oliver, Bryan V. [Advanced Radiographic Technologies, Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1195 (United States); Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D. [National Security Technologies, LLC, P.O. Box 98521, Las Vegas, Nevada 89193 (United States); Maron, Yitzhak [Weizmann Institute of Science, Rehovot, Israel 76100 (Israel)

2012-08-15

274

Absolute calibration method for nanosecond-resolved, time-streaked, fiber optic light collection, spectroscopy systems  

NASA Astrophysics Data System (ADS)

This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 ?m) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode (``hotspot'') was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm2/steradian/nm). Error analysis shows this method to be accurate to within +/- 20%, which represents a high level of accuracy for this type of measurement.

Johnston, Mark D.; Oliver, Bryan V.; Droemer, Darryl W.; Frogget, Brent; Crain, Marlon D.; Maron, Yitzhak

2012-08-01

275

Design of a streaked radiography instrument for ICF ablator tuning measurements  

SciTech Connect

A streaked radiography diagnostic has been proposed as a technique to determine the ablator mass remaining in an inertial confinement fusion ignition capsule at peak velocity. This instrument, the 'HXRI-5', has been designed to fit within a National Ignition Facility Diagnostic Instrument Manipulator. The HXRI-5 will be built at Sandia National Laboratories (SNL), and initial testing will be done at the SNL Z-Beamlet Facility. In this paper, we will describe the National Ignition Campaign requirements for this diagnostic, the instrument design, and the planned test experiments.

Olson, R. E.; Geissel, M.; Kellogg, J. W.; Bennett, G. R.; Edens, A. D.; Atherton, B. W.; Leeper, R. J. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Hicks, D. G.; Spears, B. K.; Celliers, P. M.; Holder, J. P.; Landen, O. L. [Lawrence Livermore National Laboratories, Livermore, California 94550 (United States)

2008-10-15

276

Streaked Optical Pyrometer System for Laser-Driven Shock-Wave Experiments on OMEGA  

SciTech Connect

The temperature of laser-driven shock waves is of interest to inertial confinement fusion and high-energy-density physics. We report on a streaked optical pyrometer that measures the self-emission of laser-driven shocks simultaneously with a velocity interferometer system for any reflector (VISAR). Together these diagnostics are used to obtain the temporally and spatially resolved temperatures of ~Mbar shocks driven by the OMEGA laser. We provide a brief description of the diagnostic and how it is used with VISAR. Key spectral calibration results are discussed and important characteristics of the recording system are presented.

Miller, J.E.; Boehly, T.R.; Melchior, Meyerhofer, D.D.; Celliers, P.M.; Eggert, J.H.; Hicks, D.G.; Sorce, C.M.; Oertel, J.A.; Emmel, P.M.

2007-03-23

277

Picosecond fluorescence spectroscopy of purple membrane in Halobacterium halobium with a photon-counting streak camera  

NASA Astrophysics Data System (ADS)

Fluorescence lifetimes and spectra of native and deionized purple membranes of Halobacterium halobium at 22°C were measured to be <3 and 12±4 ps, respectively, with a photon-counting streak camera system. The results confirmed that the blue-shifted transient previously found by absorption spectroscopy is attributed to bacteriorhodopsin in the lowest excited-singlet state. Ultraweak fluorescence of the light-adapted purple membrane with 2.5 × 10 -4 quantum yield could be detected even though the excitation pulse energy at 570 nm was reduced to 0.88 pJ (72 ?W average power).

Ohtani, Hiroyuki; Ishikawa, Mitsuru; Itoh, Hiroyasu; Takiguchi, Yoshihiro; Urakami, Tsuneyuki; Tsuchiya, Yutaka

1990-05-01

278

Streaked optical pyrometer system for laser-driven shock-wave experiments on OMEGA.  

PubMed

The temperature of laser-driven shock waves is of interest to inertial confinement fusion and high-energy-density physics. We report on a streaked optical pyrometer that measures the self-emission of laser-driven shocks simultaneously with a velocity interferometer system for any reflector (VISAR). Together these diagnostics are used to obtain the temporally and spatially resolved temperatures of approximately megabar shocks driven by the OMEGA laser. We provide a brief description of the diagnostic and how it is used with VISAR. Key spectral calibration results are discussed and important characteristics of the recording system are presented. PMID:17411209

Miller, J E; Boehly, T R; Melchior, A; Meyerhofer, D D; Celliers, P M; Eggert, J H; Hicks, D G; Sorce, C M; Oertel, J A; Emmel, P M

2007-03-01

279

Transient electric fields in laser plasmas observed by proton streak deflectometry  

SciTech Connect

A novel proton imaging technique was applied which allows a continuous temporal record of electric fields within a time window of several nanoseconds. This 'proton streak deflectometry' was used to investigate transient electric fields of intense ({approx}10{sup 17} W/cm{sup 2}) laser irradiated foils. We found out that these fields with an absolute peak of up to 10{sup 8} V/m extend over millimeter lateral extension and decay at nanosecond duration. Hence, they last much longer than the (approximately picosecond) laser excitation and extend much beyond the laser irradiation focus.

Sokollik, T.; Schnuerer, M.; Ter-Avetisyan, S.; Nickles, P. V.; Risse, E.; Kalashnikov, M.; Sandner, W. [Max Born Institut, Max Born Str. 2a, D-12489 Berlin (Germany); Priebe, G. [STFC Daresbury Laboratory, Warrington, Cheshire, WA4 4AD (United Kingdom); Amin, M.; Toncian, T.; Willi, O. [Heinrich Heine Universitaet Duesseldorf, D-40225 Duesseldorf (Germany); Andreev, A. A. [Vavilov State Optical Institute, St. Petersburg (Russian Federation)

2008-03-03

280

Resolving the shape of a sonoluminescence pulse in sulfuric acid by the use of streak camera.  

PubMed

A streak camera is used to measure the shape of sonoluminescence pulses from a cavitation bubble levitated stably in a sulfuric acid solution. The shape and response to an acoustic pressure field of the sonoluminescence pulse in 85% by weight sulfuric acid are qualitatively similar to those in water. However, the pulse width in sulfuric acid is wider than that in water by over one order of magnitude. The width of the sonoluminescence pulse is strongly dependent on the concentration of the sulfuric acid solution, while the skewed distribution of the shape remains unchanged. PMID:19507941

Huang, Wei; Chen, Weizhong; Cui, Weicheng

2009-06-01

281

High resolution vidicon-based readout system for photon-counting streak camera applications  

NASA Technical Reports Server (NTRS)

The design, implementation, and evaluation of a high-resolution vidicon-based reconfigurable imaging system for integration into a photon-counting streak camera that can be readily coupled to a standard interface and computer have been achieved. Experimental results are reported which demonstrate that the design goals are met, providing the capability to measure differential time to better than 3 picosecond accuracy. Augmented by real-time calibration, the accuracy, linearity, noise levels, and stability of the system are adequate to support dual wavelength laser ranging.

Varghese, Thomas K.; Steggerda, Charles; Selden, Mike; Oldham, Thomas; Degnan, John J.

1992-01-01

282

Fumonisin B1, a toxin produced by Fusarium verticillioides, modulates maize ?-1,3-glucanase activities involved in defense response.  

PubMed

Fusarium verticillioides is an important pathogen in maize that causes various diseases affecting all stages of plant development worldwide. The fungal pathogen could be seed borne or survive in soil and penetrate the germinating seed. Most F. verticillioides strains produce fumonisins, which are of concern because of their toxicity to animals and possibly humans, and because they enhance virulence against seedlings of some maize genotypes. In this work, we studied the action of fumonisin B1 (FB1) on the activity of maize ?-1,3-glucanases involved in plant defense response. In maize embryos, FB1 induced an acidic isoform while suppressing the activity of two basic isoforms. This acidic isoform was induced also with 2,6-dichloroisonicotinic acid, an analog of salicylic acid. Repression of the basic isoforms suggested a direct interaction of the enzymes with the mycotoxin as in vitro experiments showed that pure FB1 inhibited the basic ?-1,3-glucanases with an IC(50) of 53 ?M. When germinating maize embryos were inoculated with F. verticillioides the same dual effect on ?-1,3-glucanase activities that we observed with the pure toxin was reproduced. Similar levels of FB1 were recovered at 24 h germination in maize tissue when they were treated with pure FB1 or inoculated with an FB1-producing strain. These results suggest that ?-1,3-glucanases are a relevant physiological target and their modulation by FB1 might contribute to F. verticillioides colonization. PMID:22120123

Sánchez-Rangel, Diana; Sánchez-Nieto, Sobeida; Plasencia, Javier

2012-05-01

283

High-value products from transgenic maize.  

PubMed

Maize (also known as corn) is a domesticated cereal grain that has been grown as food and animal feed for tens of thousands of years. It is currently the most widely grown crop in the world, and is used not only for food/feed but also to produce ethanol, industrial starches and oils. Maize is now at the beginning of a new agricultural revolution, where the grains are used as factories to synthesize high-value molecules. In this article we look at the diversity of high-value products from maize, recent technological advances in the field and the emerging regulatory framework that governs how transgenic maize plants and their products are grown, used and traded. PMID:20816943

Naqvi, Shaista; Ramessar, Koreen; Farré, Gemma; Sabalza, Maite; Miralpeix, Bruna; Twyman, Richard M; Capell, Teresa; Zhu, Changfu; Christou, Paul

2011-01-01

284

Wind Streaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 12 July 2004 The atmosphere of Mars is a dynamic system. Water-ice clouds, fog, and hazes can make imaging the surface from space difficult. Dust storms can grow from local disturbances to global sizes, through which imaging is impossible. Seasonal temperature changes are the usual drivers in cloud and dust storm development and growth.

Eons of atmospheric dust storm activity has left its mark on the surface of Mars. Dust carried aloft by the wind has settled out on every available surface; sand dunes have been created and moved by centuries of wind; and the effect of continual sand-blasting has modified many regions of Mars, creating yardangs and other unusual surface forms.

Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

Image information: VIS instrument. Latitude 6.9, Longitude 69.4 East (290.6 West). 19 meter/pixel resolution.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

2004-01-01

285

Quantification of Imidacloprid Uptake in Maize Crops  

Microsoft Academic Search

The systemic imidacloprid is one of the most used insecticides in the world for field and horticultural crops. This neurotoxicant is often used as seed-dressing, especially for maize, sunflower, and rape. Using a LC\\/MS\\/MS technique (LOQ ) 1 Ìg\\/kg and LOD ) 0.1 Ìg\\/kg), the presence of imidacloprid has been measured in maize from field samples at the time of

J. M. Bonmatin; P. A. Marchand; R. Charvet; I. Moineau; E. R. Bengsch; M. E. Colin

2005-01-01

286

Can Transgenic Maize Affect Soil Microbial Communities?  

PubMed Central

The aim of the experiment was to determine if temporal variations of belowground activity reflect the influence of the Cry1Ab protein from transgenic maize on soil bacteria and, hence, on a regulatory change of the microbial community (ability to metabolize sources belonging to different chemical guilds) and/or a change in numerical abundance of their cells. Litter placement is known for its strong influence on the soil decomposer communities. The effects of the addition of crop residues on respiration and catabolic activities of the bacterial community were examined in microcosm experiments. Four cultivars of Zea mays L. of two different isolines (each one including the conventional crop and its Bacillus thuringiensis cultivar) and one control of bulk soil were included in the experimental design. The growth models suggest a dichotomy between soils amended with either conventional or transgenic maize residues. The Cry1Ab protein appeared to influence the composition of the microbial community. The highly enhanced soil respiration observed during the first 72 h after the addition of Bt-maize residues can be interpreted as being related to the presence of the transgenic crop residues. This result was confirmed by agar plate counting, as the averages of the colony-forming units of soils in conventional treatments were about one-third of those treated with transgenic straw. Furthermore, the addition of Bt-maize appeared to induce increased microbial consumption of carbohydrates in BIOLOG EcoPlates. Three weeks after the addition of maize residues to the soils, no differences between the consumption rate of specific chemical guilds by bacteria in soils amended with transgenic maize and bacteria in soils amended with conventional maize were detectable. Reaped crop residues, comparable to post-harvest maize straw (a common practice in current agriculture), rapidly influence the soil bacterial cells at a functional level. Overall, these data support the existence of short Bt-induced ecological shifts in the microbial communities of croplands' soils.

Mulder, Christian; Wouterse, Marja; Raubuch, Markus; Roelofs, Willem; Rutgers, Michiel

2006-01-01

287

Induction of pluripotency in human somatic cells via a transient state resembling primitive streak-like mesendoderm.  

PubMed

During mammalian embryonic development, the primitive streak initiates the differentiation of pluripotent epiblast cells into germ layers. Pluripotency can be reacquired in committed somatic cells using a combination of a handful of transcription factors, such as OCT3/4, SOX2, KLF4 and c-MYC (hereafter referred to as OSKM), albeit with low efficiency. Here we show that during OSKM-induced reprogramming towards pluripotency in human cells, intermediate cells transiently show gene expression profiles resembling mesendoderm, which is a major component of the primitive streak. Based on these findings, we discover that forkhead box H1 (FOXH1), a transcription factor required for anterior primitive streak specification during early development, significantly enhances the reprogramming efficiency of human fibroblasts by promoting their maturation, including mesenchymal to epithelial transition and the activation of late pluripotency markers. These results demonstrate that during the reprogramming process, human somatic cells go through a transient state that resembles mesendoderm. PMID:24759836

Takahashi, Kazutoshi; Tanabe, Koji; Ohnuki, Mari; Narita, Megumi; Sasaki, Aki; Yamamoto, Masamichi; Nakamura, Michiko; Sutou, Kenta; Osafune, Kenji; Yamanaka, Shinya

2014-01-01

288

Frequency-Domain Streak Camera and Tomography for Ultrafast Imaging of Evolving and Channeled Plasma Accelerator Structures  

SciTech Connect

We demonstrate a prototype Frequency Domain Streak Camera (FDSC) that can capture the picosecond time evolution of the plasma accelerator structure in a single shot. In our prototype Frequency-Domain Streak Camera, a probe pulse propagates obliquely to a sub-picosecond pump pulse that creates an evolving nonlinear index 'bubble' in fused silica glass, supplementing a conventional Frequency Domain Holographic (FDH) probe-reference pair that co-propagates with the 'bubble'. Frequency Domain Tomography (FDT) generalizes Frequency-Domain Streak Camera by probing the 'bubble' from multiple angles and reconstructing its morphology and evolution using algorithms similar to those used in medical CAT scans. Multiplexing methods (Temporal Multiplexing and Angular Multiplexing) improve data storage and processing capability, demonstrating a compact Frequency Domain Tomography system with a single spectrometer.

Li Zhengyan; Zgadzaj, Rafal; Wang Xiaoming; Reed, Stephen; Dong Peng; Downer, Michael C. [Department of Physics, University of Texas at Austin, Austin, TX, 78712 (United States)

2010-11-04

289

Novel Maize Split-Seed Explant and Methods for In Vitro Regeneration of Maize.  

National Technical Information Service (NTIS)

The present invention provides an efficient and novel maize transformation and regeneration system based on a novel split-seed explant. Mature maize seeds are split longitudinally to form a split-seed explant. The split-seed explant can then be used in tr...

D. Al-Abed S. L. Goldman S. V. Rudrabhatla

2005-01-01

290

The Maize Pathogenesis-Related PRms Protein Localizes to Plasmodesmata in Maize Radicles  

Microsoft Academic Search

Pathogenesis-related (PR) proteins are plant proteins induced in response to infection by pathogens. In this study, an antibody raised against the maize PRms protein was used to localize the protein in fungal-infected maize radicles. The PRms protein was found to be localized at the contact areas between parenchyma cells of the differentiating protoxy- lem elements. By using immunoelectron microscopy, we

Isabel Murillo; Laura Cavallarin; Blanca San

1997-01-01

291

First streaked radiography experiments of indirect drive ICF capsule implosions on the National Ignition Facility  

NASA Astrophysics Data System (ADS)

1-dimensional (slit imaging) time resolved radiography of capsule implosions in ignition hohlraums on the National Ignition Facility (NIF) is used to measure the time history of implosion velocities, ablator shell thickness and remaining ablator mass in the last 5 ns before peak implosion time [1]. While first experiments on the NIF performed with gated imagers recorded these quantities at four adjustable times, streaked radiography [2] adds the tremendous benefit of recording the full implosion evolution through capsule stagnation and explosion phase. First streaked radiography experiments of Si doped indirect drive ignition capsule surrogates with an initial radius of 1.1 mm successfully measured implosion performance with required accuracies at radii in the 0.9 to 0.2 mm range. These experiments were performed in Au and Au/DU gas filled ignition hohlraums driven by laser pulses with a peak power in the 330-420 TW range and total laser energy up to 1.8 MJ. Data quality and inferred statistical uncertainties in implosion velocity, remaining mass and capsule thickness will be discussed. [1] O.L. Landen et al, Phys. Plasmas 18, 051002 (2011). [2] D.G. Hicks et al, Phys. Plasmas 17, 102703 (2010).

Dewald, E.; MacKinnon, A.; Tommasini, R.; Meezan, N.; Hicks, D.; Olson, R.; Prisbey, S.; Opachich, Y. P.; Kalantar, D.; Macphee, A.; Khan, S.; Hatch, B.; Bailey, C.; Ehrlich, B.; Bradley, D.; Bell, P.; Glenzer, S.; Landen, O.; MacGowan, B.; Kilkenny, J.; Edwards, J.; van Wonterghem, B.; Moses, E.

2012-10-01

292

Nonlinear response of the photocathode of an x-ray streak camera to UV light  

SciTech Connect

We have found that a potassium-iodide photocathode of an x-ray streak camera responds to UV light at {lambda}=308 nm. The photocathode surface work function, 6.5 eV, is larger than the 4 eV energy of the UV photon, hence the source of the response is interesting. We will present results on the response of a transmission type potassium-iodide photocathode to the UV light from a {lambda}308 nm, subpicosecond XeCl laser and from a {lambda}=326 nm HeCd laser. We will test for the nonlinearity of the yield to measure of the number of photons that are needed to be absorbed before a signal is recorded. We will present data on the effect of the UV irradiance on the yield, as well as on the temporal width of the recorded signal. We will give an explanation of the observation and its effect on the dynamic-range response of the streak-camera. We will show that the response is linear with the incident irradiance, up to an incident irradiance of 10{sup 8} W/cm{sup 2} and we will explain the observation.

Kyrala, G.A.; Oro, D.M.; Studebaker, J.K.; Wood, W.M.; Schappert, G.T.; Watts, S.; Fulton, R.D.

1994-09-01

293

On the origin of the streak spacing in turbulent shear flows  

NASA Technical Reports Server (NTRS)

It is shown that the ideas of selective amplification and direct resonance, based on linear theory, can not provide an explanation for the well-defined streak spacing of about 100 wall units (referred to as 100(+) hereafter) in wall-bounded turbulent shear flows. In addition, for the direct resonance theory, the streaks are created by the non-linear self-interaction of the vertical velocity rather than of the directly forced vertical vorticity. In view of the failure of these approaches, it is then proposed that the selection mechanism must be inherently non-linear and correspond to a self-sustaining mechanism. The 100(+) value should thus be considered as a critical Reynolds number for that mechanism. Indeed, in the case of Poiseuille flow, this 100(+) criterion for transition to turbulence corresponds to the usually quoted value of 1000 based on the half-width and the centerline velocity. In Couette flow, it corresponds to a critical Reynolds number of about 400 based on the half width and half velocity difference.

Waleffe, Fabian A.

1991-01-01

294

Synchroscan streak camera imaging at a 15-MeV photoinjector with emittance exchange  

NASA Astrophysics Data System (ADS)

At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a fast single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10-20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5 ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of ˜1 ps over 10 s of minutes. These steps allowed us to measure both the UV laser pulse train at 263 nm and the e-beam via optical transition radiation (OTR). Due to the low electron beam energies and OTR signals, we typically summed over 50 micropulses with 0.25-1 nC per micropulse. The phase-locked delay box allowed us to assess chromatic temporal effects and instigated another upgrade to an all-mirror input optics barrel. In addition, we added a slow sweep horizontal deflection plug-in unit to provide dual-sweep capability for the streak camera. We report on a series of measurements made during the commissioning of these upgrades including bunch-length and phase effects using the emittance exchange beamline and simultaneous imaging of a UV drive laser component, OTR, and the 800 nm diagnostics laser.

Lumpkin, A. H.; Ruan, J.; Thurman-Keup, R.

2012-09-01

295

Multiple maize minichromosomes in meiosis.  

PubMed

In this study, four distinct minichromosomes derived from the maize B chromosome, were increased in copy number using the B chromosome's accumulation mechanism, namely nondisjunction at the second pollen mitosis and preferential fertilization of the egg. These minichromosomes provide the unique opportunity to examine the behavior of many copies of a single chromosome in an otherwise diploid background. While multiple copies were associated in multivalent configurations, they often dissociated into univalents or bivalents prior to metaphase I. The largest mini's behavior closely resembled the progenitor B chromosome, but all smaller chromosomes showed failure of sister chromatid cohesion. In addition to the meiotic behavior, we observed many anomalies of univalent behavior and possible heterochromatic fusions of B repeat associated heterochromatin. PMID:22552914

Masonbrink, Rick E; Gaeta, Robert T; Birchler, James A

2012-05-01

296

Chlorophyllous totipotent maize cell cultures  

US Patent & Trademark Office Database

The subject invention provides totipotent, chlorophyllous, cell cultures of maize. In addition, the methods of producing such cultures are applicable to other related species, including cereals such as rice, oats, barley, and heat. The subject cultures are valuable for herbicide studies, studies for enhancing photosynthesis, and genetic manipulation, such as plastid transformation. The methods of the subject invention are capable of providing high percentages of totipotent cells. These cells are capable of sustained cell division and are competent for regeneration over long periods; they provide high-quality target tissue for nuclear and organelle transformation. The invention also describes methods for the introduction of heterologous DNA into the chloroplast genome. The present invention also provides methods, vectors, and gene constructs for enhancing expression of a recombinant nucleic acid sequence in transgenic plants and plant tissues.

2011-10-18

297

A single extraction method for the analysis by liquid chromatography\\/tandem mass spectrometry of fumonisins and biomarkers of disrupted sphingolipid metabolism in tissues of maize seedlings  

Microsoft Academic Search

The fungus Fusarium verticillioides is a pathogen of many plants and produces fumonisins. In addition to their well-studied animal toxicoses, these toxins contribute\\u000a to the development of maize seedling disease in susceptible maize varieties. Fumonisin disruption of sphingolipid biosynthesis\\u000a occurs during pathogenesis. An extraction method was developed for the simultaneous analysis of fumonisins B1 (FB1), B2 (FB2) and B3 (FB3),

Nicholas C. Zitomer; Anthony E. Glenn; Charles W. Bacon; Ronald T. Riley

2008-01-01

298

Characterisation of Banana streak Mysore virus and evidence that its DNA is integrated in the B genome of cultivated Musa.  

PubMed

We have sequenced the complete genome of an isolate of Banana streak virus from banana cv. 'Mysore' and show that it is sufficiently different from a previously characterised isolate from cv. 'Obino l'Ewai' to warrant recognition as a distinct species, for which the name Banana streak Mysore virus (BSMysV) is proposed. The structure of the BSMysV genome was typical of badnaviruses in general, although ORF I had a non-conventional start codon. Evidence that at least part of the BSMysV genome is integrated in the B genome of cultivated Musa is presented and transmissibility by the mealybug Planococcus citri also demonstrated. PMID:15785970

Geering, A D W; Pooggin, M M; Olszewski, N E; Lockhart, B E L; Thomas, J E

2005-04-01

299

Streak formation as side effect of optical breakdown during processing the bulk of transparent Kerr media with ultra-short laser pulses  

Microsoft Academic Search

Femtosecond lasers have been successfully used to perform refractive surgery, by cutting within the bulk of the corneal tissue. As a side effect to the laser cutting there, a streak-like discoloration is observed in histological sections above and below the cutting plane, incident with the direction of laser propagation. These streak-shaped alterations of tissue are believed to originate from low

C. L. Arnold; A. Heisterkamp; W. Ertmer; H. Lubatschowski

2005-01-01

300

Organization of the R Chromosome Region in Maize. Triennial Report.  

National Technical Information Service (NTIS)

Anthocyanin pigmentation in maize is strain and tissue specific. The primary source of variation is represented in maize races indigenous to widely separated geographic regions of North and South America. Secondary sources include variants which have appe...

J. L. Kermicle

1979-01-01

301

Report of On-Farm Maize Travelling Workshop, 1986,  

National Technical Information Service (NTIS)

The fourth annual maize travelling workshop was conducted in two parts, because of different crop growth stages in the northern and southern parts of the country. An interdisciplinary group of maize scientists and representatives from the industry and pri...

M. Aslam E. J. Stevens M. Q. Chatta

1987-01-01

302

A single domestication for maize shown by multilocus microsatellite genotyping  

PubMed Central

There exists extraordinary morphological and genetic diversity among the maize landraces that have been developed by pre-Columbian cultivators. To explain this high level of diversity in maize, several authors have proposed that maize landraces were the products of multiple independent domestications from their wild relative (teosinte). We present phylogenetic analyses based on 264 individual plants, each genotyped at 99 microsatellites, that challenge the multiple-origins hypothesis. Instead, our results indicate that all maize arose from a single domestication in southern Mexico about 9,000 years ago. Our analyses also indicate that the oldest surviving maize types are those of the Mexican highlands with maize spreading from this region over the Americas along two major paths. Our phylogenetic work is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. We also found only modest evidence for postdomestication gene flow from teosinte into maize.

Matsuoka, Yoshihiro; Vigouroux, Yves; Goodman, Major M.; Sanchez G., Jesus; Buckler, Edward; Doebley, John

2002-01-01

303

MaizeGDB's new data types, resources and activities  

PubMed Central

MaizeGDB is the Maize Genetics and Genomics Database. Available at MaizeGDB are diverse data that support maize research including maps, gene product information, loci and their various alleles, phenotypes (both naturally occurring and as a result of directed mutagenesis), stocks, sequences, molecular markers, references and contact information for maize researchers worldwide. Also available through MaizeGDB are various community support service bulletin boards including the Editorial Board's list of high-impact papers, information about the Annual Maize Genetics Conference and the Jobs board where employment opportunities are posted. Reported here are data updates, improvements to interfaces and changes to standard operating procedures that have been made during the past 2 years. MaizeGDB is freely available and can be accessed online at .

Lawrence, Carolyn J.; Schaeffer, Mary L.; Seigfried, Trent E.; Campbell, Darwin A.; Harper, Lisa C.

2007-01-01

304

Diaporthaceae associated with root and crown rot of maize.  

PubMed

Several isolates of coelomycetous fungi with pigmented conidia were consistently isolated from diseased roots of Zea mays in irrigated plots monitored in the KwaZulu-Natal Province of South Africa. Based on their morphology, these isolates could be identified as representative of Stenocarpella macrospora, S. maydis, and Phaeocytostroma ambiguum. Although species of Stenocarpella are well-known as causal agents of cob and stalk rot and leaf blight of maize in South Africa, the occurrence and importance of P. ambiguum is less well documented and understood. To determine the role of P. ambiguum as a root pathogen of maize, pathogenicity tests were conducted under glasshouse conditions at 18 °C night and 28 °C day temperatures using a pasteurised soil, river sand and perlite medium and a 0.5 % sand-bran inoculum. Based on these results, P. ambiguum was shown to be a primary pathogen of maize, but to be less virulent than the positive control, S. maydis. Furthermore, to clarify the higher-level phylogeny of these fungal genera, isolates were subjected to DNA sequencing of the nuclear ribosomal DNA (ITS & LSU). Partial gene sequences of the translation elongation factor 1-alpha gene were added to confirm the species monophyly. To resolve the generic placement of Phaeocytostroma, additional species such as P. sacchari, P. plurivorum and P. megalosporum were also added to the analysis. Based on these results, Stenocarpella and Phaeocytostroma were shown to be two well defined genera, belonging to Diaporthales, Diaporthaceae, being closely allied to Phomopsis (Diaporthe). All three genera were also observed to form alpha as well as beta conidia, and although this phenomenon is well documented for Phomopsis and Phaeocytostroma, it is a new observation for Stenocarpella. In spite of the differences in conidial pigmentation, no support could be obtained for polyphyly in Diaporthaceae, suggesting that as observed in Botryosphaeriaceae (Botryosphaeriales), conidial pigmentation is not informative at the family level in Diaporthales. PMID:22679583

Lamprecht, Sandra C; Crous, Pedro W; Groenewald, Johannes Z; Tewoldemedhin, Yared T; Marasas, Walter F O

2011-06-01

305

Rice black-streaked dwarf virus P6 self-interacts to form punctate, viroplasm-like structures in the cytoplasm and recruits viroplasm-associated protein P9-1  

PubMed Central

Background Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus within the family Reoviridae, can infect several graminaceous plant species including rice, maize and wheat, and is transmitted by planthoppers. Although several RBSDV proteins have been studied in detail, functions of the nonstructural protein P6 are still largely unknown. Results In the current study, we employed yeast two-hybrid assays, bimolecular fluorescence complementation and subcellular localization experiments to show that P6 can self-interact to form punctate, cytoplasmic viroplasm-like structures (VLS) when expressed alone in plant cells. The region from residues 395 to 659 is necessary for P6 self-interaction, whereas two polypeptides (residues 580-620 and 615-655) are involved in the subcellular localization of P6. Furthermore, P6 strongly interacts with the viroplasm-associated protein P9-1 and recruits P9-1 to localize in VLS. The P6 395-659 region is also important for the P6-P9-1 interaction, and deleting any region of P9-1 abolishes this heterologous interaction. Conclusions RBSDV P6 protein has an intrinsic ability to self-interact and forms VLS without other RBSDV proteins or RNAs. P6 recruits P9-1 to VLS by direct protein-protein interaction. This is the first report on the functionality of RBSDV P6 protein. P6 may be involved in the process of viroplasm nucleation and virus morphogenesis.

2011-01-01

306

Participatory plant breeding with maize in Mexico and Honduras  

Microsoft Academic Search

Maize is a staple food crop in many developing countries. However, if seven major maize producing countries are excluded from\\u000a this group, data indicate that only 34% of the maize area is planted with improved seed despite considerable effort invested\\u000a in maize breeding. This has led researchers to investigate other options, such as farmer-participatory plant breeding, for\\u000a delivering the benefits

Margaret E. Smith; Fernando G. Castillo; Francisco Gómez

2001-01-01

307

The genetic architecture of maize height.  

PubMed

Height is one of the most heritable and easily measured traits in maize (Zea mays L.). Given a pedigree or estimates of the genomic identity-by-state among related plants, height is also accurately predictable. But, mapping alleles explaining natural variation in maize height remains a formidable challenge. To address this challenge, we measured the plant height, ear height, flowering time, and node counts of plants grown in >64,500 plots across 13 environments. These plots contained >7300 inbreds representing most publically available maize inbreds in the United States and families of the maize Nested Association Mapping (NAM) panel. Joint-linkage mapping of quantitative trait loci (QTL), fine mapping in near isogenic lines (NILs), genome-wide association studies (GWAS), and genomic best linear unbiased prediction (GBLUP) were performed. The heritability of maize height was estimated to be >90%. Mapping NAM family-nested QTL revealed the largest explained 2.1 ± 0.9% of height variation. The effects of two tropical alleles at this QTL were independently validated by fine mapping in NIL families. Several significant associations found by GWAS colocalized with established height loci, including brassinosteroid-deficient dwarf1, dwarf plant1, and semi-dwarf2. GBLUP explained >80% of height variation in the panels and outperformed bootstrap aggregation of family-nested QTL models in evaluations of prediction accuracy. These results revealed maize height was under strong genetic control and had a highly polygenic genetic architecture. They also showed that multiple models of genetic architecture differing in polygenicity and effect sizes can plausibly explain a population's variation in maize height, but they may vary in predictive efficacy. PMID:24514905

Peiffer, Jason A; Romay, Maria C; Gore, Michael A; Flint-Garcia, Sherry A; Zhang, Zhiwu; Millard, Mark J; Gardner, Candice A C; McMullen, Michael D; Holland, James B; Bradbury, Peter J; Buckler, Edward S

2014-04-01

308

The Genetic Architecture Of Maize Height  

PubMed Central

Height is one of the most heritable and easily measured traits in maize (Zea mays L.). Given a pedigree or estimates of the genomic identity-by-state among related plants, height is also accurately predictable. But, mapping alleles explaining natural variation in maize height remains a formidable challenge. To address this challenge, we measured the plant height, ear height, flowering time, and node counts of plants grown in >64,500 plots across 13 environments. These plots contained >7300 inbreds representing most publically available maize inbreds in the United States and families of the maize Nested Association Mapping (NAM) panel. Joint-linkage mapping of quantitative trait loci (QTL), fine mapping in near isogenic lines (NILs), genome-wide association studies (GWAS), and genomic best linear unbiased prediction (GBLUP) were performed. The heritability of maize height was estimated to be >90%. Mapping NAM family-nested QTL revealed the largest explained 2.1 ± 0.9% of height variation. The effects of two tropical alleles at this QTL were independently validated by fine mapping in NIL families. Several significant associations found by GWAS colocalized with established height loci, including brassinosteroid-deficient dwarf1, dwarf plant1, and semi-dwarf2. GBLUP explained >80% of height variation in the panels and outperformed bootstrap aggregation of family-nested QTL models in evaluations of prediction accuracy. These results revealed maize height was under strong genetic control and had a highly polygenic genetic architecture. They also showed that multiple models of genetic architecture differing in polygenicity and effect sizes can plausibly explain a population’s variation in maize height, but they may vary in predictive efficacy.

Peiffer, Jason A.; Romay, Maria C.; Gore, Michael A.; Flint-Garcia, Sherry A.; Zhang, Zhiwu; Millard, Mark J.; Gardner, Candice A. C.; McMullen, Michael D.; Holland, James B.; Bradbury, Peter J.; Buckler, Edward S.

2014-01-01

309

Species of Cercospora associated with grey leaf spot of maize.  

PubMed

Grey leaf spot is a serious yield-reducing disease of maize (Zea mays) in many parts of the world where this crop is cultivated. The causal organism associated with the disease is Cercospora zeae-maydis. Two potential sibling species have been recognized as Groups I and II. The DNA sequences for the internal transcribed spacers (ITS1 & ITS2), the 5.8S rRNA gene, elongation factor 1-alpha, histone H3, actin and calmodulin gene regions suggest that Groups I and II are two distinct species. Furthermore, Cercospora zeae-maydis (Group I) can be distinguished from C. zeina sp. nov. (Group II) by its faster growth rate on artificial media, the ability to produce cercosporin, longer conidiophores, and broadly fusiform conidia. A PCR-based test that distinguishes the two species was developed using species-specific primers designed from the histone H3 gene. PMID:18490979

Crous, Pedro W; Groenewald, Johannes Z; Groenewald, Marizeth; Caldwell, Pat; Braun, Uwe; Harrington, Thomas C

2006-01-01

310

Species of Cercospora associated with grey leaf spot of maize  

PubMed Central

Grey leaf spot is a serious yield-reducing disease of maize (Zea mays) in many parts of the world where this crop is cultivated. The causal organism associated with the disease is Cercospora zeae-maydis. Two potential sibling species have been recognized as Groups I and II. The DNA sequences for the internal transcribed spacers (ITS1 & ITS2), the 5.8S rRNA gene, elongation factor 1-?, histone H3, actin and calmodulin gene regions suggest that Groups I and II are two distinct species. Furthermore, Cercospora zeae-maydis (Group I) can be distinguished from C. zeina sp. nov. (Group II) by its faster growth rate on artificial media, the ability to produce cercosporin, longer conidiophores, and broadly fusiform conidia. A PCR-based test that distinguishes the two species was developed using species-specific primers designed from the histone H3 gene.

Crous, Pedro W.; Groenewald, Johannes Z.; Groenewald, Marizeth; Caldwell, Pat; Braun, Uwe; Harrington, Thomas C.

2006-01-01

311

Investigation of the Bottleneck Leading to the Domestication of Maize  

Microsoft Academic Search

Maize (Zea mays ssp. mays) is genetically diverse, yet it is also morphologically distinct from its wild relatives. These two observations are somewhat contradictory: the first observation is consistent with a large historical population size for maize, but the latter observation is consistent with strong, diversity-limiting selection during maize domestication. In this study, we sampled sequence diversity, coupled with simulations

Adam Eyre-Walker; Rebecca L. Gaut; Holly Hilton; Dawn L. Feldman; Brandon S. Gaut

1998-01-01

312

Rajasthan Downy Mildew of Maize: The Problem and Management Perspectives  

Microsoft Academic Search

Rajasthan downy mildew of maize incited by Peronosclerospora heteropogoni is a unique example of ontogenic predisposition of a crop to a pathogen from wild grass host. Since its first record on maize in 1968, several outbreaks have been reported during 1973-80 and losses of up to 60 per cent have been recorded. The pathogen can infect maize, teosinte, Heteropogon melanocarpus,

R. S. Rathore; Amit Trivedi; Kusum Mathur

313

Maize Authentication: Quality Control Methods and Multivariate Analysis (Chemometrics)  

Microsoft Academic Search

Maize is one of the most important cereals because of its numerous applications in processed foods where it is the major or minor component. Apart from maize authenticity issues related to cultivar and geographical origin (national and\\/or international level), there is another important issue related to genetically modified maize. Various objective parameters such as fatty acids, phenolic compounds, pigments, heavy

Ioannis S. Arvanitoyannis; Antonios Vlachos

2009-01-01

314

Ultrafast Electron-Optical X-Ray Streak and Framing Cameras.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. In this thesis the development of ultrafast electron -optical streak and framing cameras having radiation sensitivities ranging from the visible to soft X-ray are discussed. A framing camera incorporating a vacuum demountable image tube with ultraviolet/soft X-ray sensitivity has been demonstrated to be capable of providing multiple, temporally separated, two-dimensional images with picosecond image exposure times under various operating conditions. Experimental evidence has been presented to show that this camera system can provide up to four high quality temporally separated images with an exposure time of 230 ps (FWHM) and inter-frame times of ~1 ns under UV illumination. In the two-frame operation with soft X-ray illumination (generated using a laser produced plasma) image exposure times of as short as 100 ps (FWHM) and inter-frame times of 400 ps have been achieved. The dynamic spatial resolution of the camera has been shown to be ~8 lp/mm and ~5 lp/mm for the UV and soft X-ray sensitive devices respectively. A visible-sensitivity electron-optical single -shot streak camera possessing a novel travelling-wave deflection structure has been experimentally evaluated using a mode -locked cw ring dye laser. The limiting temporal resolution for this has been measured to be 300 fs and the merits of the travelling-wave deflection structure have been discussed. The implementation of this type of deflector geometry has also been demonstrated in conjunction with the vacuum demountable framing camera system. Computer aided design techniques have been utilised to further optimise the electron-optical framing tube configuration, and modifications have been proposed to enable shorter frame periods to be obtained while maintaining the dynamic spatial resolution. Results from preliminary evaluations of this design using a vacuum demountable UV-sensitive system are included. A novel streak camera design has also been proposed in which very high electrostatic photocathode extraction fields (up to 12 kV/mm) may be employed without danger of structural damage arising from electrostatic breakdown. This has been achieved by the removal of the usual mesh electrode placed in close proximity to the photocathode. Preliminary evaluations of a vacuum demountable UV-sensitive version of this camera geometry have been achieved which demonstrate a static spatial resolution of 80 lp/mm (when referred to the photocathode).

Walker, David R.

315

A Proteinaceous Elicitor Sm1 from the Beneficial Fungus Trichoderma virens Is Required for Induced Systemic Resistance in Maize1[W  

PubMed Central

We have previously shown that the beneficial filamentous fungus Trichoderma virens secretes the highly effective hydrophobin-like elicitor Sm1 that induces systemic disease resistance in the dicot cotton (Gossypium hirsutum). In this study we tested whether colonization of roots by T. virens can induce systemic protection against a foliar pathogen in the monocot maize (Zea mays), and we further demonstrated the importance of Sm1 during maize-fungal interactions using a functional genomics approach. Maize seedlings were inoculated with T. virens Gv29-8 wild type and transformants in which SM1 was disrupted or constitutively overexpressed in a hydroponic system or in soil-grown maize seedlings challenged with the pathogen Colletotrichum graminicola. We show that similar to dicot plants, colonization of maize roots by T. virens induces systemic protection of the leaves inoculated with C. graminicola. This protection was associated with notable induction of jasmonic acid- and green leaf volatile-biosynthetic genes. Neither deletion nor overexpression of SM1 affected normal growth or development of T. virens, conidial germination, production of gliotoxin, hyphal coiling, hydrophobicity, or the ability to colonize maize roots. Plant bioassays showed that maize grown with SM1-deletion strains exhibited the same levels of systemic protection as non-Trichoderma-treated plants. Moreover, deletion and overexpression of SM1 resulted in significantly reduced and enhanced levels of disease protection, respectively, compared to the wild type. These data together indicate that T. virens is able to effectively activate systemic disease protection in maize and that the functional Sm1 elicitor is required for this activity.

Djonovic, Slavica; Vargas, Walter A.; Kolomiets, Michael V.; Horndeski, Michelle; Wiest, Aric; Kenerley, Charles M.

2007-01-01

316

Diagnosing coupled jet-streak circulations for a northern plains snow band from the operational nested-grid model  

NASA Technical Reports Server (NTRS)

On 17 March 1989, moderate to heavy snow developed in a 100- to 200-km-wide band extending from South Dakota to northern Michigan. The 4- to 8-inch snowfall within this band was not associated with major cyclogenesis, and developed 500 to 600 km north of a stationary surface front. A diagnostic analysis based on an application of the General Meteorological Package (GEMPAK 5.0) to a numerical simulation from the operational nested-grid model (NGM) is utilized to show that the development of this snow band is related to the interaction of two upper-tropospheric jet streaks and their associated transverse circulation patterns. The eastward propagation of a jet streak from the West Coast toward the middle United States and to the south of a slower-moving jet along the U.S.-Canadian border led to a merger of the ascent maxima associated with the direct and indirect circulations of the northern and southern jets, respectively. The snow band developed as the ascending branches of the jet-streak circulation patterns merged, with the eastward propagation of the heaviest snow linked to the motion of the coupled circulation pattern. The study also demonstrates the usefulness of the operational NGM for providing the higher-resolution datasets required to relate the evolution of jet-streak circulation patterns to the development of mesoscale precipitation bands.

Hakim, Gregory J.; Uccellini, Louis W.

1992-01-01

317

Viral Coat Protein Peptides with Limited Sequence Homology Bind Similar Domains of Alfalfa Mosaic Virus and Tobacco Streak Virus RNAs  

Microsoft Academic Search

An unusual and distinguishing feature of alfalfa mosaic virus (AMV) and ilarviruses such as tobacco streak virus (TSV) is that the viral coat protein is required to activate the early stages of viral RNA replication, a phenomenon known as genome activation. AMV-TSV coat protein homology is limited; however, they are functionally interchangeable in activating virus replication. For example, TSV coat

MAUD M. SWANSON; PATRICIA ANSEL-MCKINNEY; FELICIA HOUSER-SCOTT; VIDADI YUSIBOV; L. SUE LOESCH-FRIES; LEE GEHRKE

1998-01-01

318

C.C.D. Readout of a Picosecond Streak Camera with an Intensified C.C.D.  

National Technical Information Service (NTIS)

This paper deals with a digital streak camera readout device. The device consists in a low light level television camera made of a solid state C.C.D. array coupled to an image intensifier associated to a video-digitizer coupled to a micro-computer system....

M. Lemonier J. C. Richard C. Cavailler A. Mens G. Raze

1984-01-01

319

Multiplex real-time RT-PCR for detection of Wheat streak mosaic virus and Tritcum mosaic virus  

Microsoft Academic Search

Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV) are widespread throughout the southwestern Great Plains states. When using conventional diagnostics such as enzyme-linked immunosorbent assays (ELISA), these two viruses are commonly found together in infected wheat samples. Methods for molecular detection have been developed for wheat viral pathogens, but until recently no multiplex method for detection of both

J. A. Price; J. Smith; A. Simmons; J. Fellers; C. M. Rush

2010-01-01

320

Fungal growth and fusarium mycotoxin content in isogenic traditional maize and genetically modified maize grown in France and Spain.  

PubMed

Fungi of the genus Fusarium are common fungal contaminants of maize and are also known to produce mycotoxins. Maize that has been genetically modified to express a Bt endotoxin has been used to study the effect of insect resistance on fungal infection of maize grains by Fusarium species and their related mycotoxins. Maize grain from Bt hybrids and near-isogenic traditional hybrids was collected in France and Spain from the 1999 crop, which was grown under natural conditions. According to the ergosterol level, the fungal biomass formed on Bt maize grain was 4-18 times lower than that on isogenic maize. Fumonisin B(1) grain concentrations ranged from 0.05 to 0.3 ppm for Bt maize and from 0.4 to 9 ppm for isogenic maize. Moderate to low concentrations of trichothecenes and zearalenone were measured on transgenic as well as on non-transgenic maize. Nevertheless, significant differences were obtained in certain regions. The protection of maize plants against insect damage (European corn borer and pink stem borer) through the use of Bt technology seems to be a way to reduce the contamination of maize by Fusarium species and the resultant fumonisins in maize grain grown in France and Spain. PMID:11829636

Bakan, B; Melcion, D; Richard-Molard, D; Cahagnier, B

2002-02-13

321

Inferences on the Genome Structure of Progenitor Maize Through Comparative Analysis of Rice, Maize and the Domesticated Panicoids  

Microsoft Academic Search

Corn and rice genetic linkage map alignments were extended and refined by the addition of 262 new, reciprocally mapped maize cDNA loci. Twenty chromosomal rearrangements were identified in maize relative to rice and these included telomeric fusions between rice linkage groups, nested insertion of rice linkage groups, intrachromosomal inversions, and a nonreciprocal translocation. Maize genome evolution was inferred relative to

William A. Wilson; Sandra E. Harrington; Wendy L. Woodman; Michael Lee; Mark E. Sorrells; Susan R. McCouch

322

Genetic and Morphological Analysis of a Maize-Teosinte F_2 Population: Implications for the Origin of Maize  

Microsoft Academic Search

Genes controlling the dramatic morphological differences between maize and its presumed progenitor (teosinte) were investigated in a maize-teosinte F_2 population through the use of molecular markers. Results indicate that the key traits differentiating maize and teosinte are each under multigenic control, although for some traits, such as the number of ranks of cupules, the data are consistent with a mode

John Doebley; Adrian Stec; Jonathan Wendel; Marlin Edwards

1990-01-01

323

Two members of the Ustilago maydis velvet family influence teliospore development and virulence on maize seedlings.  

PubMed

Members of the fungal-specific velvet protein family regulate sexual and asexual spore production in the Ascomycota. We predicted, therefore, that velvet homologs in the basidiomycetous plant pathogen Ustilago maydis would regulate sexual spore development, which is also associated with plant disease progression in this fungus. To test this hypothesis, we studied the function of three U. maydis velvet genes, umv1, umv2 and umv3. Using a gene replacement strategy, deletion mutants were made in all three genes in compatible haploid strains, and additionally for umv1 and umv2 in the solopathogenic strain, SG200. None of the mutants showed novel morphological phenotypes during yeast-like, in vitro growth. However, the ?umv1 mutants failed to induce galls or teliospores in maize. Chlorazol black E staining of leaves infected with ?umv1 dikaryons revealed that the ?umv1 hyphae did not proliferate normally and were blocked developmentally before teliospore formation. The ?umv2 mutants were able to induce galls and teliospores in maize, but were slow to do so and thus reduced in virulence. The ?umv3 mutants were not affected in teliospore formation or disease progression. Complementation of the ?umv1 and ?umv2 mutations in the SG200 background produced disease indices similar to those of SG200. These results indicate that two U. maydis velvet family members, umv1 and umv2, are important for normal teliospore development and disease progression in maize seedlings. PMID:24064149

Karakkat, Brijesh B; Gold, Scott E; Covert, Sarah F

2013-12-01

324

Laser-produced plasma x-ray diagnostics with an x-ray streak camera at the Iskra-4 plant  

NASA Astrophysics Data System (ADS)

An X.raj streak camera with an Xray streak tube used for laser-produced plasma soft Xrays measurement is described, and experimental results are given. In investigating short-Jived high temperature plasma, and inertial control of thermonuclear fusion in particular, measurement techniques based on registration of X-.rays emitted by the investigated object are of great value. They make it possible to get much information on the dynamics of plasma evolution, its form, dimensions, temperature, and density. The instrumentation used for these purposes must meet the following main requirements: it must provide measuring X-.rays time, intensity and spatial coordinate; its spectral range must be wide, from relatively hard to extremely soft X-rays (tens of keV to tens of eV quantum energy); its tiive resolution must be high (of the order of 10 s). At present the only type of an instrument satisfying the above requirements is a streak camera with an X-ray' streak tube (X'RST). The XRST operation principle has been known long ago: the photocathode converts the incident X-rays into an electron beam, which is accelerated and focused by the electric fields onto the output phosphor screen, where a visible image of the incident radiation cross-.section appears. The image travels very rapidly over the screen, resulting in a time sweep. The design and development of such kind of instrumentation was begun in our country more than 10 years ago. In 1986 the All-Union Research Institute of experimental Physics, in collaboration with the Research Institute of Pulse Technique, designed and built first instruments with satisfactory parameters. These instruments found use in laser thermonuclear fusion research. Mainly two types of X-.ray streak tubes are used for X-.ray spatial-temporal structure registration: special type X-ray streak tubes with X-ray sensitive photocathodes and transparent for X-ray input windows, and X-ray streak tubes with X-ray sensitive photocathodes and without an input win dow; these tubes are joined to a continuously pumped-out vacuum plant with an X-ray source inside it. The quantum energy lower limit of the registered X-rays depends on the input window thickness and. material, which determine its transparency for the radiation being investigated.

Berkovski, Arkadi G.; Gubanov, Yuri I.; Pryanishnikov, Ivan G.; Murugov, Vasili M.; Petrov, Sergej I.; Senik, Alexei V.

1991-04-01

325

Pulsed versus direct current calibration of a proximity focused x-ray streak camera  

SciTech Connect

The absolute sensitivity of a proximity focused x-ray streak tube was measured with dc Henke tube x-ray line sources. Calibration covered the photon energy range from 0.930 to 8.05 keV at five points. These data were compared to a model of sensitivity based on photocathode response and matched the model well on a relative scale. A pulsed comparison was performed using a laser-plasma x-ray source. The calculated camera sensitivity was folded with the measured spectrum and compared to measured film exposures. The predicted exposures were 6.5 times less than the measured exposures, verifying concerns that the proximity focused tube response is nonlinear with flux at low, dc flux levels. Results of dc recalibrations that varied flux levels determined the extent of this phenomenon.

Rockett, P.D.; McGurn, J.S.

1981-02-01

326

Understanding the role of phase in chemical bond breaking with coincidence angular streaking.  

PubMed

Electron motion in chemical bonds occurs on an attosecond timescale. This ultrafast motion can be driven by strong laser fields. Ultrashort asymmetric laser pulses are known to direct electrons to a certain direction. But do symmetric laser pulses destroy symmetry in breaking chemical bonds? Here we answer this question in the affirmative by employing a two-particle coincidence technique to investigate the ionization and fragmentation of H? by a long circularly polarized multicycle femtosecond laser pulse. Angular streaking and the coincidence detection of electrons and ions are employed to recover the phase of the electric field, at the instant of ionization and in the molecular frame, revealing a phase-dependent anisotropy in the angular distribution of H? fragments. Our results show that electron localization and asymmetrical breaking of molecular bonds are ubiquitous, even in symmetric laser pulses. The technique we describe is robust and provides a powerful tool for ultrafast science. PMID:23867800

Wu, J; Magrakvelidze, M; Schmidt, L P H; Kunitski, M; Pfeifer, T; Schöffler, M; Pitzer, M; Richter, M; Voss, S; Sann, H; Kim, H; Lower, J; Jahnke, T; Czasch, A; Thumm, U; Dörner, R

2013-01-01

327

Improving the diffraction of full-length human selenomethionyl metavinculin crystals by streak-seeding  

PubMed Central

Metavinculin is an alternatively spliced isoform of vinculin that has a 68-residue insert in its tail domain (1134 total residues) and is exclusively expressed in cardiac and smooth muscle tissue, where it plays important roles in myocyte adhesion complexes. Mutations in the metavinculin-specific insert are associated with dilated cardiomyopathy (DCM) in man. Crystals of a DCM-associated mutant of full-length selenomethionine-labeled metavinculin grown by hanging-drop vapor diffusion diffracted poorly and were highly sensitive to radiation, preventing the collection of a complete X-ray diffraction data set at the highest possible resolution. Streak-seeding markedly improved the stability, crystal-growth rate and diffraction quality of DCM-associated mutant metavinculin crystals, allowing complete data collection to 3.9?Å resolution. These crystals belonged to space group P43212, with two molecules in the asymmetric unit and unit-cell parameters a = b = 170, c = 211?Å, ? = ? = ? = 90°.

Rangarajan, Erumbi S.; Izard, Tina

2010-01-01

328

Mapping of Digitaria streak virus transcripts reveals different RNA species from the same transcription unit.  

PubMed Central

All, except 19 [corrected] bp, of the Digitaria streak virus (DSV) genome is transcribed. Two RNA transcripts (1+ and 2+) are encoded by the virion DNA strand and up to five (1- to 5-) by the complementary DNA strand [corrected]. Detailed mapping of these RNAs has revealed evidence for splicing in one species (RNA 4-), which together with its more abundant unspliced counterpart (RNA 2-) could synthesize both a 30.5 and 41 kd polypeptide from the same transcription unit. This extensive overlapping of spliced and unspliced RNAs could indicate that the initiation and splicing of transcripts is temporally regulated. At least one transcript (RNA 1-) may have a non-translational role. Transcription of the DSV genome shows similarities to some animal DNA viruses, particularly the papovaviruses. Images

Accotto, G P; Donson, J; Mullineaux, P M

1989-01-01

329

Spectroscopic analysis of diesel combustion flame by means of streak camera  

SciTech Connect

Band spectra in ultraviolet and visible ranges contain information on the state of combustion flame. Measurement of those spectra in diesel combustion flame, however, has been regarded as impossible because of the obstruction of bright flame and soot. The phenomena of diesel combustion, therefore, have not been analyzed clearly from the viewpoint of chemical reaction. The authors inserted an optical fiber into the diesel combustion chamber to detect the flame. The combustion flame was recorded by a special spectroscopic apparatus, named Streak camera, and the recorded image was subjected to spectroscopic analysis. The result of the experiments confirmed the existence of band spectra emitted from CH and OH radicals in the ultraviolet and visible ranges. The recorded data made clear the progress of chemical reactions and the formation of intermediate products during the diesel combustion process.

Nagase, K.; Funatsu, K.

1988-01-01

330

Absolutely calibrated soft-x-ray streak camera for laser-fusion applications  

SciTech Connect

The intensity output of a soft-x-ray streak camera was calibrated (SXRSC) in order to make absolute flux measurements of x rays emitted from laser-produced plasmas. The SXRSC developed at LLNL is used to time-resolve x-ray pulses to better than 20 ps. The SXRSC uses a Au photocathode on a thin carbon substrate which is sensitive to x rays from 100 eV to greater than 10 keV. Calibrations are done in the dynamic mode using a small laser-produced x-ray source. The SXRSC is calibrated by comparing its integrated signal to the output of calibrated x-ray diodes monitoring the source strength. The measured SXRSC response is linear over greater than two orders of magnitude. Using these calibrations, absolute intensities can be measured to an accuracy of +-30%.

Kauffman, R.L.; Medecki, H.; Stradling, G.

1982-01-01

331

New developments and results on high-spatiotemporal-resolution x-ray streak cameras  

NASA Astrophysics Data System (ADS)

High resolution x-ray streak camera built around bilamellar tubes have been developed for a long time in CEL-V2. The C850X camera is the last step of those studies. We describe here the different versions of the camera; we also present the experimental results (temporal resolution approximately equals 2 ps in conjunction with a dynamic spatial resolution > 15 1p/mm) obtained in ENSTA on a 60 fs UV laser, which match our theoretical predictions. The improvement of the C850X electronics have also been implemented on C750X (the P750X tube of the camera has the same structure as that of C850X, but its deflection plates are replaced by a 50(Omega) meander stripline, which allows higher sweep speeds). We present the status of that development, the improvements accomplished on the sweep circuit, and the first results obtained with that device.

Mens, Alain; Gontier, D.; Huilizen, J.-C.; Sauneuf, Richard; Schirmann, Daniel; Verrecchia, R.; Chambaret, Jean-Paul; Hamoniaux, G.; Roth, J. M.; Tomasini, F.

1992-01-01

332

Streaked laser shadowgraphy of tungsten wire array implosions on the Saturn generator  

SciTech Connect

A combination of a 400 ns, 300 mJ, 640 nm dye laser, and an optical streak camera have been used to demonstrate that time-resolved shadowgrams can be made of the implosion phase of tungsten wire arrays. Initial experiments have shown that mirror lifetime and spatial resolution are issues for this diagnostic technique. Nonetheless, these experiments have provided new information on wire array dynamics; specifically, they show that even with a 0.46 mm wire spacing, the high density regions formed by the wires, are separate until 30 ns into the main drive current. Peak currents of 6.6 MA were obtained 40 ns after the start of the current, while peak radiated powers of 85 TW were measured at 50 ns. {copyright} {ital 1997 American Institute of Physics.}

Deeney, C.; McGurn, J.; Noack, D.; Porter, J.L.; Spielman, R.B.; Seamen, J.F.; Jobe, D.O.; Vargas, M.F.; Gilliland, T.; Douglas, M.R.; Matzen, M.K. [Sandia National Laboratory, Albuquerque, New Mexico 87185-1194 (United States)] [Sandia National Laboratory, Albuquerque, New Mexico 87185-1194 (United States)

1997-01-01

333

Posterior Malformations in Dact1 mutant mice arise through misregulated Vangl2 at the Primitive Streak  

PubMed Central

Mice homozygous for mutations in Dact1 (Dpr/Frodo) phenocopy human malformations involving the spine, genitourinary system, and distal digestive tract. We trace this phenotype to disrupted germ layer morphogenesis at the primitive streak (PS). Remarkably, heterozygous mutation of Vangl2, a transmembrane component of the Planar Cell Polarity (PCP) pathway, rescues recessive Dact1 phenotypes, whereas loss of Dact1 reciprocally rescues semidominant Vangl2 phenotypes. We show that Dact1, an intracellular protein, forms a complex with Vangl2. In Dact1 mutants, Vangl2 is increased at the PS where cells ordinarily undergo an epithelial-mesenchymal transition. This is associated with abnormal E-cadherin distribution and changes in biochemical measures of the PCP pathway. We conclude that Dact1 contributes to morphogenesis at the PS by regulating Vangl2 upstream of cell adhesion and the PCP pathway.

Suriben, Rowena; Kivimae, Saul; Fisher, Daniel A.; Moon, Randall T.; Cheyette, Benjamin N.R.

2009-01-01

334

Antimicrobial Screening of Actinobacteria using a Modified Cross-Streak Method  

PubMed Central

Out of the 30 actinobacterial cultures screened for antimicrobial activity, 28 cultures were found to produce active products against various pathogenic microorganisms such as Gram-negative, Gram-positive bacteria and yeast, using a modified cross streak method. The modified method helped in easy quantification of results and also in ruling out probable mutual antibiosis. The actinobacterial strains that showed the ability to produce antimicrobial compounds belonged to Streptomyces (53%), Micromonospora (13%) and Actinomadura (10%) genera. Streptomyces sp. strain MMA-5 showed the highest multispecific antibiosis efficiency score value. Broad antibiotic spectrum activity was exhibited by Streptomyces sp. strain MMA-2 and Micromonospora sp. strain MMA-8. The multidrug resistant human pathogenic yeast strain Candida albicans was inhibited by 18 actinobacterial strains.

Velho-Pereira, Sonashia; Kamat, N M

2011-01-01

335

Efficient kinematical simulation of reflection high-energy electron diffraction streak patterns for crystal surfaces  

NASA Astrophysics Data System (ADS)

An efficient program with a user-friendly graphical interface has been developed for simulating reflection high-energy electron diffraction patterns obtained on crystal surfaces. The calculations are based on a kinematical approach which considers single electron scattering events at the surface. This time-efficient approach is in most cases sensitive enough for distinguishing different structural models, even if they differ very subtly. The results are presented in realistic two-dimensional density plots which can be directly compared to experimental observations. This program provides a useful tool in studying different structural models for crystal surfaces. Program summaryProgram title: RHEEDsim Catalogue identifier: AEJC_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEJC_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 2752 No. of bytes in distributed program, including test data, etc.: 367 205 Distribution format: tar.gz Programming language: Matlab (version > 7.6.0) Computer: Personal Computers Operating system: Windows with Matlab environment RAM: Greater than 1 MB Classification: 7.4 Nature of problem: Reflection high-energy electron diffraction (RHEED) has been widely used in studying crystal surface structures all over the world, especially in combination with ultra-high vacuum molecular beam epitaxy systems. In addition to determining the surface smoothness, RHEED is also a very useful tool in studying surface reconstructions, which are often encountered at the growth surfaces of semiconductors and alloys. While the positions of the fractional streaks can be used to determine the basic information of the surface supercells, the intensity modulations on the fractional streaks provide further insights on the details within these unit cells. Kinematic approach is an efficient method for simulating the RHEED patterns based on various surface structural models, which can help unraveling the surface atomic structure. Solution method: The kinematic approach utilized here assumes single scattering events. Furthermore, the Ewald sphere is approximated into a planar surface for computing the streak intensities (which are most relevant to real experiments). Structure factors are calculated based on a given input of atomic species and their coordinates, with user modifiable form factors. In addition to the intensity modulation within the surface plane, additional modulations extending into the z direction is also taken into consideration, resulting in realistic density maps of the RHEED streaks, which can be directly compared to experimental observations. Unusual features: The main program RHEEDsim.m calls several local subprograms for certain computational tasks. As a result, all programs should be extracted into a single folder, and that folder should be set as the main directory in Matlab. Running time: The computing time is computer and user parameter dependent, but typically ranges from few seconds to few minutes.

Wang, Kangkang; Smith, Arthur R.

2011-10-01

336

Ustilago maydis reprograms cell proliferation in maize anthers.  

PubMed

The basidiomycete Ustilago maydis is a ubiquitous pathogen of maize (Zea mays), one of the world's most important cereal crops. Infection by this smut fungus triggers tumor formation in aerial plant parts within which the fungus sporulates. Using confocal microscopy to track U. maydis infection on corn anthers for 7 days post-injection, we found that U. maydis is located on the epidermis during the first 2 days, and has reached all anther lobe cell types by 3 days post-injection. Fungal infection alters cell-fate specification events, cell division patterns, host cell expansion and host cell senescence, depending on the developmental stage and cell type. Fungal effects on tassel and plant growth were also quantified. Transcriptome profiling using a dual organism microarray identified thousands of anther genes affected by fungal infection at 3 days post-injection during the cell-fate specification and rapid cell proliferation phases of anther development. In total, 4147 (17%) of anther-expressed genes were altered by infection, 2018 fungal genes were expressed in anthers, and 206 fungal secretome genes may be anther-specific. The results confirm that U. maydis deploys distinct genes to cause disease in specific maize organs, and suggest mechanisms by which the host plant is manipulated to generate a tumor. PMID:23795972

Gao, Li; Kelliher, Timothy; Nguyen, Linda; Walbot, Virginia

2013-09-01

337

Antifungal metabolites (monorden, monocillins I, II, III) from Colletotrichum graminicola, a systemic vascular pathogen of maize.  

PubMed

Colletotrichum graminicola is a systemic vascular pathogen that causes anthracnose stalk rot and leaf blight of maize. In the course of an effort to explore the potential presence and roles of C. graminicola metabolites in maize, ethyl acetate extracts of solid substrate fermentations of several C. graminicola isolates from Michigan and Illinois were found to be active against Aspergillus flavus and Fusarium verticillioides, both mycotoxin-producing seed-infecting fungal pathogens. Chemical investigations of the extract of one such isolate (NRRL 47511) led to the isolation of known metabolites monorden (also known as radicicol) and monocillins I-III as major components. Monorden and monocillin I displayed in vitro activity against the stalk- and ear-rot pathogen Stenocarpella maydis while only the most abundant metabolite (monorden) showed activity against foliar pathogens Alternaria alternata, Bipolaris zeicola, and Curvularia lunata. Using LC-HRESITOFMS, monorden was detected in steam-sterilized maize stalks and stalk residues inoculated with C. graminicola but not in the necrotic stalk tissues of wound-inoculated plants grown in an environmental chamber. Monorden and monocillin I can bind and inhibit plant Hsp90, a chaperone of R-proteins. It is hypothesized that monorden and monocillins could support the C. graminicola disease cycle by disrupting maize plant defenses and by excluding other fungi from necrotic tissues and crop residues. This is the first report of natural products from C. graminicola, as well as the production of monorden and monocillins by a pathogen of cereals. PMID:19825415

Wicklow, Donald T; Jordan, Annalisa M; Gloer, James B

2009-12-01

338

STELLA-positive subregions of the primitive streak contribute to posterior tissues of the mouse gastrula  

PubMed Central

The developmental relationship between the posterior embryonic and extraembryonic regions of the mammalian gastrula is poorly understood. Although many different cell types are deployed within this region, only the primordial germ cells (PGCs) have been closely studied. Recent evidence has suggested that the allantois, within which the PGCs temporarily take up residence, contains a pool of cells, called the Allantoic Core Domain (ACD), critical for allantoic elongation to the chorion. Here, we have asked whether the STELLA-positive cells found within this region, thought to be specified PGCs, are actually part of the ACD and to what extent they, and other ACD cells, contribute to the allantois and fetal tissues. To address these hypotheses, STELLA was immunolocalized to the mouse gastrula between Early Streak (ES) and 12-somite pair (-s) stages (~6.75 – 9.0 days post coitum, dpc) in histological sections. STELLA was found in both the nucleus and cytoplasm in a variety of cell types, both within and outside of the putative PGC trajectory. Fate-mapping the headfold-stage (~7.75 – 8.0 dpc) posterior region, by which time PGCs are thought to be segregated into a distinct lineage, revealed that the STELLA-positive proximal ACD and intraembryonic posterior primitive streak (IPS) contributed to a wide range of somatic tissues that encompassed derivatives of the three primary germ layers. This contribution included STELLA-positive cells localizing to tissues both within and outside of the putative PGC trajectory. Thus, while STELLA may identify a subpopulation of cells destined for the PGC lineage, our findings reveal that it may be part of a broader niche that encompasses the ACD and through which the STELLA population may contribute cells to a wide variety of posterior tissues of the mouse gastrula.

Mikedis, Maria M.; Downs, Karen M.

2012-01-01

339

Carrageenan as an elicitor of induced secondary metabolites and its effects on various growth characters of chickpea and maize plants  

Microsoft Academic Search

The effects of polysaccharide elicitor k-carrageenan obtained from Hypnea musciformis, red algae on the production of Induced Secondary Metabolites, ISMs (the disease resistance compounds) and on various growth characters of chickpea and maize plants were studied. Experiments were conducted in the field of PCSIR Laboratories Complex Karachi during December 2008–April 2009 in randomized complete block design with three replications. Three

Fatima Bi; Seema Iqbal; Muhammad Arman; Amanat Ali; Mahmood-ul Hassan

2011-01-01

340

A Genome-Wide Association Study Reveals Genes Associated with Fusarium Ear Rot Resistance in a Maize Core Diversity Panel  

PubMed Central

Fusarium ear rot is a common disease of maize that affects food and feed quality globally. Resistance to the disease is highly quantitative, and maize breeders have difficulty incorporating polygenic resistance alleles from unadapted donor sources into elite breeding populations without having a negative impact on agronomic performance. Identification of specific allele variants contributing to improved resistance may be useful to breeders by allowing selection of resistance alleles in coupling phase linkage with favorable agronomic characteristics. We report the results of a genome-wide association study to detect allele variants associated with increased resistance to Fusarium ear rot in a maize core diversity panel of 267 inbred lines evaluated in two sets of environments. We performed association tests with 47,445 single-nucleotide polymorphisms (SNPs) while controlling for background genomic relationships with a mixed model and identified three marker loci significantly associated with disease resistance in at least one subset of environments. Each associated SNP locus had relatively small additive effects on disease resistance (±1.1% on a 0–100% scale), but nevertheless were associated with 3 to 12% of the genotypic variation within or across environment subsets. Two of three identified SNPs colocalized with genes that have been implicated with programmed cell death. An analysis of associated allele frequencies within the major maize subpopulations revealed enrichment for resistance alleles in the tropical/subtropical and popcorn subpopulations compared with other temperate breeding pools.

Zila, Charles T.; Samayoa, L. Fernando; Santiago, Rogelio; Butron, Ana; Holland, James B.

2013-01-01

341

Genetically transformed maize plants from protoplasts.  

PubMed

Genetically transformed maize plants were obtained from protoplasts treated with recombinant DNA. Protoplasts that were digested from embryogenic cell suspension cultures of maize inbred A188 were combined with plasmid DNA containing a gene coding for neomycin phosphotransferase (NPT II) next to the 35S promoter region of cauliflower mosaic virus. A high voltage electrical pulse was applied to the protoplasts, which were then grown on filters placed over feeder layers of maize suspension cells (Black Mexican Sweet) and selected for growth in the presence of kanamycin. Selected cell lines showed NPT II activity. Plants were regenerated from transformed cell lines and grown to maturity. Southern analysis of DNA extracted from callus and plants indicated the presence of the NPT II gene. PMID:2832947

Rhodes, C A; Pierce, D A; Mettler, I J; Mascarenhas, D; Detmer, J J

1988-04-01

342

Gene Mapping with Recombinant Inbreds in Maize  

PubMed Central

Recombinant inbred lines of maize have been developed for the rapid mapping of molecular probes to chromosomal location. Two recombinant inbred families have been constructed from F(2) populations of T232 X CM37 and CO159 X Tx303. A genetic map based largely on isozymes and restriction fragment length polymorphisms has been produced that covers virtually the entire maize genome. In order to map a new gene, an investigator has only to determine its allelic distribution among the recombinant inbred lines and then compare it by computer with the distributions of all previously mapped loci. The availability of the recombinant inbreds and the associated data base constitute an efficient means of mapping new molecular markers in maize.

Burr, B.; Burr, F. A.; Thompson, K. H.; Albertson, M. C.; Stuber, C. W.

1988-01-01

343

Maize pollen is an important allergen in occupationally exposed workers  

PubMed Central

Background The work- or environmental-related type I sensitization to maize pollen is hardly investigated. We sought to determine the prevalence of sensitization to maize pollen among exposed workers and to identify the eliciting allergens. Methods In July 2010, 8 out of 11 subjects were examined who were repeatedly exposed to maize pollen by pollinating maize during their work in a biological research department. All 8 filled in a questionnaire and underwent skin prick testing (SPT) and immune-specific analyses. Results 5 out of the 8 exposed subjects had repeatedly suffered for at least several weeks from rhinitis, 4 from conjunctivitis, 4 from urticaria, and 2 from shortness of breath upon occupational exposure to maize pollen. All symptomatic workers had specific IgE antibodies against maize pollen (CAP class ? 1). Interestingly, 4 of the 5 maize pollen-allergic subjects, but none of the 3 asymptomatic exposed workers had IgE antibodies specific for grass pollen. All but one of the maize pollen-allergic subjects had suffered from allergic grass pollen-related symptoms for 6 to 11 years before job-related exposure to maize pollen. Lung function testing was normal in all cases. In immunoblot analyses, the allergenic components could be identified as Zea m 1 and Zea m 13. The reactivity is mostly caused by cross-reactivity to the homologous allergens in temperate grass pollen. Two sera responded to Zea m 3, but interestingly not to the corresponding timothy allergen indicating maize-specific IgE reactivity. Conclusion The present data suggest that subjects pollinating maize are at high risk of developing an allergy to maize pollen as a so far underestimated source of occupational allergens. For the screening of patients with suspected maize pollen sensitization, the determination of IgE antibodies specific for maize pollen is suitable.

2011-01-01

344

Areawide suppression of European corn borer with Bt maize reaps savings to non-Bt maize growers.  

PubMed

Transgenic maize engineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has become widely adopted in U.S. agriculture. In 2009, Bt maize was planted on more than 22.2 million hectares, constituting 63% of the U.S. crop. Using statistical analysis of per capita growth rate estimates, we found that areawide suppression of the primary pest Ostrinia nubilalis (European corn borer) is associated with Bt maize use. Cumulative benefits over 14 years are an estimated $3.2 billion for maize growers in Illinois, Minnesota, and Wisconsin, with more than $2.4 billion of this total accruing to non-Bt maize growers. Comparable estimates for Iowa and Nebraska are $3.6 billion in total, with $1.9 billion for non-Bt maize growers. These results affirm theoretical predictions of pest population suppression and highlight economic incentives for growers to maintain non-Bt maize refugia for sustainable insect resistance management. PMID:20929774

Hutchison, W D; Burkness, E C; Mitchell, P D; Moon, R D; Leslie, T W; Fleischer, S J; Abrahamson, M; Hamilton, K L; Steffey, K L; Gray, M E; Hellmich, R L; Kaster, L V; Hunt, T E; Wright, R J; Pecinovsky, K; Rabaey, T L; Flood, B R; Raun, E S

2010-10-01

345

Identification and characterization of maize pathogenesis-related proteins. Four maize PR proteins are chitinases  

Microsoft Academic Search

Eight pathogenesis-related proteins extractable at pH 2.8 were found to accumulate in maize leaves after mercuric chloride treatment or brome mosaic virus infection. These proteins were called PRm (pathogenesis-related maize) proteins. Seven PRm proteins were purified to homogeneity by preparative polyacrylamide gel electrophoresis and their amino acid compositions determined. Estimated molecular weights in SDS-containing gels were: PRm 1 14.2 kDa;

William Nasser; Marc de Tapia; Serge Kauffmann; Shideh Montasser-Kouhsari; Gérard Burkard

1988-01-01

346

Individual detection of genetically modified maize varieties in non-identity-preserved maize samples.  

PubMed

In many countries, the labeling of grains and feed- and foodstuffs is mandatory if the genetically modified organism (GMO) content exceeds a certain level of approved GM varieties. The GMO content in a maize sample containing the combined-trait (stacked) GM maize as determined by the currently available methodology is likely to be overestimated. However, there has been little information in the literature on the mixing level and varieties of stacked GM maize in real sample grains. For the first time, the GMO content of non-identity-preserved (non-IP) maize samples imported from the United States has been successfully determined by using a previously developed individual kernel detection system coupled to a multiplex qualitative PCR method followed by multichannel capillary gel electrophoresis system analysis. To clarify the GMO content in the maize samples imported from the United States, determine how many stacked GM traits are contained therein, and which GM trait varieties frequently appeared in 2005, the GMO content (percent) on a kernel basis and the varieties of the GM kernels in the non-IP maize samples imported from the United States were investigated using the individual kernel analysis system. The average (+/-standard deviation) of the GMO contents on a kernel basis in five non-IP sample lots was determined to be 51.0+/-21.6%, the percentage of a single GM trait grains was 39%, and the percentage of the stacked GM trait grains was 12%. The MON810 grains and NK603 grains were the most frequent varieties in the single GM traits. The most frequent stacked GM traits were the MON810xNK603 grains. In addition, the present study would provide the answer and impact for the quantification of GM maize content in the GM maize kernels on labeling regulation. PMID:18298063

Akiyama, Hiroshi; Sakata, Kozue; Kondo, Kazunari; Tanaka, Asako; Liu, Ming S; Oguchi, Taichi; Furui, Satoshi; Kitta, Kazumi; Hino, Akihiro; Teshima, Reiko

2008-03-26

347

Mycotoxins in ingredients of animal feeding stuffs: II. determination of mycotoxins in maize and maize products  

Microsoft Academic Search

Analytical methods have been developed for the reliable detection and estimation of 22 mycotoxins in maize gluten and other maize products used in the animal feed industry. The mycotoxins are aflatoxins B1 B2, G1and G2, ochratoxins A and B, citrinin, cyclopiazonic acid, zearalenone, sterigmatocystin, deoxynivalenol, nivalenol together with seven related trichothecene mycotoxins, fumonisins B1 and B2 and moniliformin. For most

K. A. Scudamore; S. Nawaz; M. T. Hetmanski

1998-01-01

348

Fumonisins: probable role as effectors in the complex interaction of susceptible and resistant maize hybrids and Fusarium verticillioides.  

PubMed

Fusarium verticillioides is best known for its worldwide occurrence on maize resulting in highly variable disease symptoms, ranging from asymptomatic to severe rotting and wilting and fumonisin production. The aim of this study was to investigate the influence of hybrid genotypes in the early stages of F. verticillioides infection, and the role of fumonisins as effectors in the outcome of this complex interaction. Disease symptoms, growth parameters, root morphology, and fungal colonization were evaluated at 7, 14, and 21 days after planting in seedlings from maize seeds of resistant (RH) and susceptible (SH) hybrids inoculated with F. verticillioides or watered with solutions of fumonisins. F. verticillioides induced growth enhancement or retardation depending on the plant genetic background and the fungal colonization rate, while fumonisins caused severe reduction in biomass and fitness. Seedlings watered with high fumonisin concentrations displayed lesions similar to those seen in F. verticillioides maize seedling disease, and also elicited inhibitory effects on root growth and morphology and on functional properties. In summary, these data strongly suggest a dual role for fumonisins in the F. verticillioides-maize interaction, acting as pathogenic factors at high concentrations, or triggering the plant detoxification mechanisms at low levels. PMID:22578291

Arias, Silvina L; Theumer, Martin G; Mary, Veronica S; Rubinstein, Hector R

2012-06-01

349

Use of tropical maize for bioethanol production.  

PubMed

Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25-2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1 % (v/v) to 15.6 % (v/v), equivalent to 90.3-92.2 % of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry. PMID:23508398

Chen, Ming-Hsu; Kaur, Prabhjot; Dien, Bruce; Below, Frederick; Vincent, Michael L; Singh, Vijay

2013-08-01

350

Maize Profilin Isoforms Are Functionally Distinct  

PubMed Central

Profilin is an actin monomer binding protein that, depending on the conditions, causes either polymerization or depolymerization of actin filaments. In plants, profilins are encoded by multigene families. In this study, an analysis of native and recombinant proteins from maize demonstrates the existence of two classes of functionally distinct profilin isoforms. Class II profilins, including native endosperm profilin and a new recombinant protein, ZmPRO5, have biochemical properties that differ from those of class I profilins. Class II profilins had higher affinity for poly-l-proline and sequestered more monomeric actin than did class I profilins. Conversely, a class I profilin inhibited hydrolysis of membrane phosphatidylinositol-4,5-bisphosphate by phospholipase C more strongly than did a class II profilin. These biochemical properties correlated with the ability of class II profilins to disrupt actin cytoplasmic architecture in live cells more rapidly than did class I profilins. The actin-sequestering activity of both maize profilin classes was found to be dependent on the concentration of free calcium. We propose a model in which profilin alters cellular concentrations of actin polymers in response to fluctuations in cytosolic calcium concentration. These results provide strong evidence that the maize profilin gene family consists of at least two classes, with distinct biochemical and live-cell properties, implying that the maize profilin isoforms perform distinct functions in the plant.

Kovar, David R.; Dr?bak, Bj?rn K.; Staiger, Christopher J.

2000-01-01

351

Excision of Helitron Transposons in Maize  

PubMed Central

Helitrons are novel transposons discovered by bioinformatic analysis of eukaryotic genome sequences. They are believed to move by rolling circle (RC) replication because their predicted transposases are homologous to those of bacterial RC transposons. We report here evidence of somatic Helitron excision in maize, an unexpected finding suggesting that Helitrons can exhibit an excisive mode of transposition.

Li, Yubin; Dooner, Hugo K.

2009-01-01

352

Maize canopies under two soil water regimes  

Microsoft Academic Search

The degree of coupling between the plant canopy and the atmosphere is indicative of the ability of the two systems to exchange momentum, energy, and mass. In terms of water vapor and CO2 exchange, it characterizes the extent to which stomatal and canopy conductance may control transpiration and CO2 assimilation. In the present work, the degree of coupling of maize

Pasquale Steduto; Theodore C Hsiao

1998-01-01

353

Maize canopies under two soil water regimes  

Microsoft Academic Search

Seasonal course of evapotranspiration and of canopy CO2 assimilation are determined by interactions among the plant, aerial, and soil factors over time and culminate in the total water requirement and primary productivity of a crop. In this study, maize was grown for two seasons in large fields under two contrasting soil water regimes (WET and DRY), and monitored for canopy

Pasquale Steduto; Theodore C Hsiao

1998-01-01

354

The evolution of apical dominance in maize  

Microsoft Academic Search

The domestication of crop plants has often involved an increase in apical dominance (the concentration of resources in the main stem of the plant and a corresponding suppression of axillary branches)1. A striking example of this phenomenon is seen in maize (Zea mays spp. mays), which exhibits a profound increase in apical dominance compared with its probable wild ancestor, teosinte

John Doebley; Adrian Stec; Lauren Hubbard

1997-01-01

355

Biological Control of Fusarium moniliforme in Maize  

Microsoft Academic Search

Fusarium moniliforme Sheldon, a biological species of the mating populations within the Gibberella fujikuroi species complex, i.e., population A (= G. moniliformis (Sheld.) Wineland), is an example of a facultative fungal endophyte. During the biotrophic endophytic association with maize, as well as during saprophytic growth, F. moniliforme produces the fumonisins. The fungus is transmitted vertically and horizontally to the next

Charles W. Bacon; Ida E. Yates; Dorothy M. Hinton; Filmore Meredith

2001-01-01

356

Conservation and Diversification of SCARECROW in Maize  

Microsoft Academic Search

The SCARECROW (SCR) gene in Arabidopsis is required for asymmetric cell divisions responsible for ground tissue formation in the root and shoot. Previously, we reported that Zea mays SCARECROW (ZmSCR) is the likely maize ortholog of SCR. Here we describe conserved and divergent aspects of ZmSCR. Its ability to complement the Arabidopsisscr mutant phenotype suggests conservation of function, yet its

Jun Lim; Jee W. Jung; Chae Eun Lim; Mi-Hyun Lee; Bong Jun Kim; Miran Kim; Wesley B. Bruce; Philip N. Benfey

2005-01-01

357

Hydrophobic films from maize bran hemicelluloses  

Microsoft Academic Search

The covalent binding of laurylamine chains to maize bran heteroxylan (HX) was studied in order to produce hydrophobic plastic films. The process was carried out using periodic oxidation followed by reductive amination, both steps conducted in water. A kinetic study of the first step was performed, measuring periodate consumption, formic acid release and aldehyde formation. The over-oxidation effect was evaluated.

E. Fredon; R. Granet; R. Zerrouki; P. Krausz; L. Saulnier; J. F. Thibault; J. Rosier; C. Petit

2002-01-01

358

Ontogeny of the Maize Shoot Apical Meristem[W][OA  

PubMed Central

The maize (Zea mays) shoot apical meristem (SAM) arises early in embryogenesis and functions during stem cell maintenance and organogenesis to generate all the aboveground organs of the plant. Despite its integral role in maize shoot development, little is known about the molecular mechanisms of SAM initiation. Laser microdissection of apical domains from developing maize embryos and seedlings was combined with RNA sequencing for transcriptomic analyses of SAM ontogeny. Molecular markers of key events during maize embryogenesis are described, and comprehensive transcriptional data from six stages in maize shoot development are generated. Transcriptomic profiling before and after SAM initiation indicates that organogenesis precedes stem cell maintenance in maize; analyses of the first three lateral organs elaborated from maize embryos provides insight into their homology and to the identity of the single maize cotyledon. Compared with the newly initiated SAM, the mature SAM is enriched for transcripts that function in transcriptional regulation, hormonal signaling, and transport. Comparisons of shoot meristems initiating juvenile leaves, adult leaves, and husk leaves illustrate differences in phase-specific (juvenile versus adult) and meristem-specific (SAM versus lateral meristem) transcript accumulation during maize shoot development. This study provides insight into the molecular genetics of SAM initiation and function in maize.

Takacs, Elizabeth M.; Li, Jie; Du, Chuanlong; Ponnala, Lalit; Janick-Buckner, Diane; Yu, Jianming; Muehlbauer, Gary J.; Schnable, Patrick S.; Timmermans, Marja C.P.; Sun, Qi; Nettleton, Dan; Scanlon, Michael J.

2012-01-01

359

Development and Spread of Improved Maize Varieties and Hybrids in Developing Countries.  

National Technical Information Service (NTIS)

The International Maize and Wheat Improvement Center (CIMMYT) and the International Institute of Tropical Agriculture (IITA) serve as research hubs of large maize improvement networks embracing over 100 developing countries. The report documents the maize...

D. H. Timothy P. H. Harvey C. R. Dowswell

1988-01-01

360

Dust Devils Seen Streaking Across Mars: PART II--They're the Work of the Devil!  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

[figure removed for brevity, see original site]

In December 1999, the MOC team finally had an answer! A dust devil, shown in the above left figure, was caught in the act of creating a swirly, dark streak! An eerie sensation washed over the first team members who saw this picture--here was an event on Mars 'caught in the act' just hours before the picture was played back to Earth. A 'smoking gun.'

The first dust devil seen making a streak--located in Promethei Terra (above, left)--was traveling from right (east) to left (west). A columnar shadow was cast by sunlight coming from the upper left. This shadow indicates the true shape of the dust devil. The bright dust devil itself does not look like a column because the picture was taken from a camera looking straight down on it. The dust devil is less than 100 meters (less than 100 yards) wide and the picture covers an area approximately 1.5 by 1.7 kilometers (about 1 by 1 mile).

Dust devils are spinning, columnar vortices of wind that move across the landscape, pick up dust, and look somewhat like miniature tornadoes. Dust devils are a common occurrence in dry and desert landscapes on Earth as well as Mars. They form when the ground heats up during the day, warming the air immediately above the surface. As the warmed air nearest the surface begins to rise, it spins. The spinning column begins to move across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it the 'dust devil' or tornado-like appearance. On Earth, dust devils typically last for only a few minutes.

The fourth picture (above, right) shows a surface in southwestern Terra Sirenum near 63oS, 168oW, that has seen the activity of so many dust devils that it looks like a plate of dark gray spaghetti. This image, taken in early summer during February 2000, covers an area 3 km wide and 30 km long (1.9 by 19 miles). In fact, a dust devil can be seen in the upper right of this image. Like the other pictures shown here, the Terra Sirenum image is illuminated by sunlight from the upper left.

2000-01-01

361

Historical Weather Conditions and Maize Yields  

NASA Astrophysics Data System (ADS)

Projections of maize crops response to climate based on empirical models generally show a negative response to warmer temperatures. These models typically use monthly averages of temperature or assume that the response to a high frequency warming event is independent of when it occurs in the growing season. Biophysical modeling and experimental studies indicate that crop yields are dependent on high frequency warming events and that the timing of the event can also play a significant role in crop development. This research looks to the historical record of maize yields in the United States paired with daily station data to categorize high, low, and normal yield years with the particular high frequency patterns in maximum and minimum temperature as well as precipitation that led to such yields. A multiple linear regression model is used with these patterns to predict yields. These results expand on prior empirical modeling by incorporating high frequency temporal sensitivity into the regression model. The United States is the training region for the model because of high quality weather station and crop data. The weather data are taken from the United States Historical Climatology Network (USHCN) and provide daily records of maximum temperature, minimum temperature and precipitation at 1218 sites across the lower 48 states, with some records extending into the mid-19th century. The United States Department of Agriculture/National Agricultural Statistics Service (USDA/NASS) provides data on maize yields at the county level back to 1910, and provides state level planting and harvest time data back to 1981, at it's peak maize was produced in 2821 counties offering a wide range of different climates. The study is limited by restricting itself to the United States and maize, but could provide the basis for similar studies on a wider range of crops, geographic regions and future projections of climate change.

Butler, E.; Huybers, P.

2010-12-01

362

Transmission grating streaked spectrometer for the diagnosis of soft x-ray emission from ultrahigh intensity laser heated targets  

SciTech Connect

A free-standing gold transmission grating with a period of 5000 A has been coupled to a soft x-ray sensitive streak camera with a limiting temporal resolution of 10 ps. The streak camera is equipped with a caesium iodide transmission photocathode and observations have been made in the 10-100 A regime. For a small source (200 {mu}m diameter) the spectral resolution is predicted to be around 2.5 A. This has been confirmed by examination of the Lyman-{alpha} line in hydrogen-like laser heated boron. A recorded linewidth of 2.44 A is demonstrated. The instrument has been used to diagnose the soft x-ray emission from a plastic (CH) foil target heated by an ultra-intense (2x10{sup 20} W cm{sup -2}) laser pulse.

Eagleton, R.T.; James, S.F. [AWE Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

2004-10-01

363

The President's Day cyclone 17-19 February 1979: An analysis of jet streak interactions prior to cyclogenesis  

NASA Technical Reports Server (NTRS)

The President's Day cyclone, produced record breaking snowfall along the East Coast of the United States in February 1979. Conventional radiosonde data, SMS GOES infrared imagery and LFM 2 model diagnostics were used to analyze the interaction of upper and lower tropospheric jet streaks prior to cyclogenesis. The analysis reveals that a series of complex scale interactive processes is responsible for the development of the intense cyclone. The evolution of the subsynoptic scale mass and momentum fields prior to and during the period of rapid development of the President's Day cyclone utilizing conventional data and SMS GOES imagery is documented. The interaction between upper and lower tropospheric jet streaks which occurred prior to the onset of cyclogenesis is discussed as well as the possible effects of terrain modified airflow within the precyclogenesis environment. Possible deficiencies in the LFM-2 initial wind fields that could have been responsible, in part, for the poor numerical forecast are examined.

Uccellini, L. W.; Kocin, P. J.; Walsh, C. H.

1981-01-01

364

Genetic Characterization of a Core Set of a Tropical Maize Race Tuxpe?o for Further Use in Maize Improvement  

PubMed Central

The tropical maize race Tuxpeño is a well-known race of Mexican dent germplasm which has greatly contributed to the development of tropical and subtropical maize gene pools. In order to investigate how it could be exploited in future maize improvement, a panel of maize germplasm accessions was assembled and characterized using genome-wide Single Nucleotide Polymorphism (SNP) markers. This panel included 321 core accessions of Tuxpeño race from the International Maize and Wheat Improvement Center (CIMMYT) germplasm bank collection, 94 CIMMYT maize lines (CMLs) and 54 U.S. Germplasm Enhancement of Maize (GEM) lines. The panel also included other diverse sources of reference germplasm: 14 U.S. maize landrace accessions, 4 temperate inbred lines from the U.S. and China, and 11 CIMMYT populations (a total of 498 entries with 795 plants). Clustering analyses (CA) based on Modified Rogers Distance (MRD) clearly partitioned all 498 entries into their corresponding groups. No sub clusters were observed within the Tuxpeño core set. Various breeding strategies for using the Tuxpeño core set, based on grouping of the studied germplasm and genetic distance among them, were discussed. In order to facilitate sampling diversity within the Tuxpeño core, a minicore subset of 64 Tuxpeño accessions (20% of its usual size) representing the diversity of the core set was developed, using an approach combining phenotypic and molecular data. Untapped diversity represents further use of the Tuxpeño landrace for maize improvement through the core and/or minicore subset available to the maize community.

Chavez-Tovar, Victor H.; Yan, Jianbing; Taba, Suketoshi

2012-01-01

365

FGF signalling through RAS/MAPK and PI3K pathways regulates cell movement and gene expression in the chicken primitive streak without affecting E-cadherin expression  

PubMed Central

Background FGF signalling regulates numerous aspects of early embryo development. During gastrulation in amniotes, epiblast cells undergo an epithelial to mesenchymal transition (EMT) in the primitive streak to form the mesoderm and endoderm. In mice lacking FGFR1, epiblast cells in the primitive streak fail to downregulate E-cadherin and undergo EMT, and cell migration is inhibited. This study investigated how FGF signalling regulates cell movement and gene expression in the primitive streak of chicken embryos. Results We find that pharmacological inhibition of FGFR activity blocks migration of cells through the primitive streak of chicken embryos without apparent alterations in the level or intracellular localization of E-cadherin. E-cadherin protein is localized to the periphery of epiblast, primitive streak and some mesodermal cells. FGFR inhibition leads to downregulation of a large number of regulatory genes in the preingression epiblast adjacent to the primitive streak, the primitive streak and the newly formed mesoderm. This includes members of the FGF, NOTCH, EPH, PDGF, and canonical and non-canonical WNT pathways, negative modulators of these pathways, and a large number of transcriptional regulatory genes. SNAI2 expression in the primitive streak and mesoderm is not altered by FGFR inhibition, but is downregulated only in the preingression epiblast region with no significant effect on E-cadherin. Furthermore, over expression of SNAIL has no discernable effect on E-cadherin protein levels or localization in epiblast, primitive streak or mesodermal cells. FGFR activity modulates distinct downstream pathways including RAS/MAPK and PI3K/AKT. Pharmacological inhibition of MEK or AKT indicate that these downstream effectors control discrete and overlapping groups of genes during gastrulation. FGFR activity regulates components of several pathways known to be required for cell migration through the streak or in the mesoderm, including RHOA, the non-canonical WNT pathway, PDGF signalling and the cell adhesion protein N-cadherin. Conclusions In chicken embryos, FGF signalling regulates cell movement through the primitive streak by mechanisms that appear to be independent of changes in E-cadherin expression or protein localization. The positive and negative effects on large groups of genes by pharmacological inhibition of FGF signalling, including major signalling pathways and transcription factor families, indicates that the FGF pathway is a focal point of regulation during gastrulation in chicken.

2011-01-01

366

Transcriptome and Comparative Gene Expression Analysis of Sogatella furcifera (Horváth) in Response to Southern Rice Black-Streaked Dwarf Virus  

Microsoft Academic Search

BackgroundThe white backed planthopper (WBPH), Sogatella furcifera (Horváth), causes great damage to many crops by direct feeding or transmitting plant viruses. Southern rice black-streaked dwarf virus (SRBSDV), transmitted by WBPH, has become a great threat to rice production in East Asia.Methodology\\/Principal FindingsBy de novo transcriptome assembling and massive parallel pyrosequencing, we constructed two transcriptomes of WBPH and profiled the alternation

Yi Xu; Wenwu Zhou; Yijun Zhou; Jianxiang Wu; Xueping Zhou

2012-01-01

367

A Multiscale Numerical Study of Hurricane Andrew (1992). Part VI: Small-Scale Inner-Core Structures and Wind Streaks  

Microsoft Academic Search

The objectives of Part VI of this series of papers are to (a) simulate the finescale features of Hurricane Andrew (1992) using a cloud-resolving grid length of 2 km, (b) diagnose the formation of small-scale wind streaks, and (c) perform sensitivity experiments of varying surface fluxes on changes in storm inner-core structures and intensity. As compared to observations and a

M. K. Yau; Yubao Liu; Da-Lin Zhang; Yongsheng Chen

2004-01-01

368

Determination of intrinsic fluorescence lifetime parameters of crude oils using a laser fluorosensor with a streak camera detection system  

SciTech Connect

A laser fluorosensor system has been developed for remotely detecting and identifying crude oils and oil based products from an airborne platform. A streak camera system is the essential detection element in the laser fluorosensor. The capability of this device for rapidly measuring intrinsic temporal characteristics of oil fluorescence has been investigated. These characteristics have been used with spectral parameters for oil spill identification. 3 refs., 7 figs.

Quinn, M.F.; Al-Otaibi, A.S.; Abdullah, A. [Kuwait Institute for Scientific Research, Safat (Kuwait)] [and others

1995-12-31

369

Detection and Discrimination of Wheat Spindle Streak Mosaic Virus and Wheat Yellow Mosaic Virus Using Multiplex RT-PCR  

Microsoft Academic Search

Wheat spindle streak mosaic virus (WSSMV) and wheat yellow mosaic virus (WYMV) are two closely related bymoviruses which cause significant yield losses in wheat. There is no molecular diagnostic protocol available for either virus nor are serological methods able to discriminate them. A multiplex reverse transcription-polymerase chain reaction (RT-PCR) protocol was developed for their detection and discrimination. Twenty-three isolates of

Gerard Clover; Christine Henry

1999-01-01

370

Intestinal microbiota and secretory immunoglobulin A in feces of exclusively breast-fed infants with blood-streaked stools.  

PubMed

Episodes of blood-streaked stools are not uncommon in exclusively breast-fed infants under 6 months of age. Such bleeding is thought to be associated with food protein-induced proctocolitis, however the pathomechanism remains unclear. The aim of this study was to investigate intestinal microbiota and secretory immunoglobulin A in the feces of exclusively breast-fed infants with blood-streaked stools. Fecal specimens from 15 full-term infants with blood-streaked stools and 15 breast-fed healthy infants were studied and the results compared. All infants had been delivered vaginally and exclusively breast-fed. The fecal microbiota were investigated by phylogenetic analysis combined with culture methods for some bacterial species, and feces were assessed for the presence of fecal secretory immunoglobulin A by enzyme-linked immunosorbent assay. Phylogenetic cluster analysis revealed four major clusters of fecal bacteria, cluster A being found only in healthy infants. The Bacteroides fragilis group was observed more frequently in controls than in patients (P < 0.05). In the controls, the predominant species belonging to the Enterobacteriaceae group was Escherichia coli, whereas in the patients it was Klebsiella (P < 0.05). Concentrations of secretory immunoglobulin A were high in one third of the healthy controls. In conclusion, the pathomechanism of rectal bleeding in exclusively breast-fed infants may be related to differences in the composition of their intestinal flora. PMID:22725615

Kumagai, Hideki; Maisawa, Shun-ichi; Tanaka, Mamoru; Takahashi, Motomichi; Takasago, Yuhei; Nishijima, Asaka; Watanabe, Shuhka

2012-10-01

371

Shiny white streaks: a sign of malignancy at dermoscopy of pigmented skin lesions.  

PubMed

The aim of this study was to evaluate the practical importance of the presence of shiny white streaks (SWS) (chrysalis or crystalline structures in polarized dermoscopy) for suspicion of malignancy, diagnosis of melanoma, and pre-operative estimation of Breslow thickness and its correlation with total dermoscopy score (TDS). SWS were present in 13.6% of 800 consecutive excised lesions. The presence of SWS was associated with malignancy (odds ratio (OR) 10.534, 95% confidence interval (95% CI) 6.357-17.455, p?

Shitara, Danielle; Ishioka, Priscila; Alonso-Pinedo, Yarel; Palacios-Bejarano, Leyla; Carrera, Cristina; Malvehy, Josep; Puig, Susana

2014-03-01

372

New Experimental Hosts of Tobacco streak virus and Absence of True Seed Transmission in Leguminous Hosts.  

PubMed

Of 70 plant species tested, 50 species were susceptible to Tobacco streak virus (TSV) on sap inoculation. Both localized (necrotic and chlorotic spots) and systemic (necrotic spots, axillary shoot proliferation, stunting, total necrosis and wilt) symptoms are observed by majority of plant species. Eleven new experimental hosts were identified viz., Amaranthus blitum var. oleracea (Chaulai sag), Celosia cristata (Cocks comb), Beta vulgaris var. bengalensis (Palak/Indian spinach), Calendula officinalis (Pot marigold), Chrysanthemum indicum, Cosmos sulphurens (Yellow cosmos), Citrullus lunatus (Watermelon), Lagenaria siceraria (Bottle gourd), Coriandrum sativum (Coriander), Hibiscus subderiffa var. subderiffa (Roselle) and Portulaca oleraceae (Little hogweed). Detected groundnut seed infection with TSV for the first time by Direct antigen coated immunosorbent assay (DAC-ELISA) using whole seed. The seed infection ranged from 18.9 to 28.9% among the seeds collected from naturally infected and sap inoculated groundnut varieties (JL 24, TMV 2, Prasuna, Kadiri 6, Kadiri 9, Anantha and Kadiri 7 Bold) belonging to spanish and virginia types. Further, TSV was detected both in pod shell and seed testa and none of the samples showed the presence of TSV either in cotyledon or embryo. Grow-out and bio-assay tests proved the absence of seed transmission in groundnut and other legume crops. Hence, TSV isolate was not a true seed transmission case under Indian conditions in legumes. PMID:23637490

Vemana, K; Jain, R K

2010-10-01

373

Time-resolved Measurements of ICF Capsule Ablator Properties by Streaked X-Ray Radiography  

NASA Astrophysics Data System (ADS)

Determining the capsule ablator thickness and peak laser or x-ray drive pressure required to optimize fuel compression is a critical part of ensuring ICF ignition on the NIF. If too little ablator is burned off, the implosion velocity will be too low for adequate final compression; if too much ablator is burned off, the fuel will be preheated or the shell will be broken up by growth of hydrodynamic instabilities, again compromising compression. Avoiding such failure modes requires having an accurate, in-flight measure of the implosion velocity, areal density, and remaining mass of the ablator near peak velocity. We present a new technique which achieves simultaneous time-resolved measurements of all these parameters in a single, area-backlit, x-ray streaked radiograph. This is accomplished by tomographic inversion of the radiograph to determine the radial density profile at each time step; scalar quantities such as the average position, areal density, and mass of the ablator can then be calculated by taking moments of this density profile. Details of the successful demonstration of this technique using backlit Cu-doped Be capsule implosions at the Omega facility will be presented. This work was performed under the auspices of the U.S.Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and in collaboration with Brian Spears, David Braun, Peter Celliers, Gilbert Collins, and Otto Landen at LLNL and Rick Olson at SNL.

Hicks, Damien

2008-11-01

374

Note: A technique to capture and compose streak images of explosive events with unpredictable timing.  

PubMed

The authors describe a method to capture optical data and construct digitized streak images for analysis of high-speed phenomena with unpredictable timing by using a high-speed video camera and software routines. Advances in high-speed video camera technology have led to development of cameras with frame rates (1 x 10(6) frames per second) and spatial resolution (1280 x 800 pixels) suitable to capture fast phenomena, such as detonation in high explosives (< or = 10 km s(-1)), on small enough scales to be convenient for laboratory experiments. Further, relatively long-duration recordings (> or = 1 s) are maintained in a rolling buffer in volatile memory allowing the entire frame sequence to be recorded pretrigger, thus obviating the need for precisely located diagnostic triggers. The method described was used to capture the progression of luminous reaction during the deflagration-to-detonation transition of the HMX-based (octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine) plastic bonded explosive (PBX) formulation during cookoff. PMID:20113140

Parker, Gary R; Asay, Blaine W; Dickson, Peter M

2010-01-01

375

Improving the diffraction of full-length human selenomethionyl metavinculin crystals by streak-seeding.  

PubMed

Metavinculin is an alternatively spliced isoform of vinculin that has a 68-residue insert in its tail domain (1134 total residues) and is exclusively expressed in cardiac and smooth muscle tissue, where it plays important roles in myocyte adhesion complexes. Mutations in the metavinculin-specific insert are associated with dilated cardiomyopathy (DCM) in man. Crystals of a DCM-associated mutant of full-length selenomethionine-labeled metavinculin grown by hanging-drop vapor diffusion diffracted poorly and were highly sensitive to radiation, preventing the collection of a complete X-ray diffraction data set at the highest possible resolution. Streak-seeding markedly improved the stability, crystal-growth rate and diffraction quality of DCM-associated mutant metavinculin crystals, allowing complete data collection to 3.9?Å resolution. These crystals belonged to space group P4(3)2(1)2, with two molecules in the asymmetric unit and unit-cell parameters a=b=170, c=211?Å, ?=?=?=90°. PMID:21139209

Rangarajan, Erumbi S; Izard, Tina

2010-12-01

376

Processing of complementary sense RNAs of Digitaria streak virus in its host and in transgenic tobacco.  

PubMed Central

We have used a polymerase chain reaction (PCR) procedure to analyse low abundance complementary sense RNAs of Digitaria streak virus (DSV) from infected leaves of Digitaria setigera. This study has confirmed that both spliced and unspliced RNAs are synthesised by the same transcription unit. The position of the intron has been proven from sequencing cDNAs corresponding to the spliced RNA. Although the majority of cDNAs have 3' ends at coordinate 1063, downstream from a consensus polyadenylation sequence, a minor population of RNAs with heterogeneous 3' ends has also been identified. Two major RNA species with alternative splice sites or 3' ends, previously identified by nuclease S1 protection assays, could not be detected, but a cDNA species was observed with an apparent 90bp insertion at the 5' end of the intron. In transgenic tobacco containing integrated dimers of DSV DNA, the major unspliced RNA could readily be detected, but no spliced RNA was present. This may be a reason why DSV DNA did not replicate in tobacco. In addition, neither the minor population of heterogeneous RNAs nor the cDNA species with the insertion could be detected. The failure of the intron to be spliced in tobacco and its low activity in Digitaria is discussed in relation to recent studies on RNA splicing in plants and has led us to the conclusion that the geminivirus introns may be intrinsically inefficient. Images

Mullineaux, P M; Guerineau, F; Accotto, G P

1990-01-01

377

Note: A technique to capture and compose streak images of explosive events with unpredictable timing  

NASA Astrophysics Data System (ADS)

The authors describe a method to capture optical data and construct digitized streak images for analysis of high-speed phenomena with unpredictable timing by using a high-speed video camera and software routines. Advances in high-speed video camera technology have led to development of cameras with frame rates (1×106 frames per second) and spatial resolution (1280×800 pixels) suitable to capture fast phenomena, such as detonation in high explosives (<=10 km s-1), on small enough scales to be convenient for laboratory experiments. Further, relatively long-duration recordings (>=1 s) are maintained in a rolling buffer in volatile memory allowing the entire frame sequence to be recorded pretrigger, thus obviating the need for precisely located diagnostic triggers. The method described was used to capture the progression of luminous reaction during the deflagration-to-detonation transition of the HMX-based (octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine) plastic bonded explosive (PBX) formulation during cookoff.

Parker, Gary R.; Asay, Blaine W.; Dickson, Peter M.

2010-01-01

378

Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector  

SciTech Connect

Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab's A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infrared laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 50-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.

Ruan, J.; Lumpkin, A.H.; Santucci, J.K.; /Fermilab

2009-04-30

379

The transcriptional and functional properties of mouse epiblast stem cells resemble the anterior primitive streak.  

PubMed

Mouse epiblast stem cells (EpiSCs) can be derived from a wide range of developmental stages. To characterize and compare EpiSCs with different origins, we derived a series of EpiSC lines from pregastrula stage to late-bud-stage mouse embryos. We found that the transcriptomes of these cells are hierarchically distinct from those of the embryonic stem cells, induced pluripotent stem cells (iPSCs), and epiblast/ectoderm. The EpiSCs display globally similar gene expression profiles irrespective of the original developmental stage of the source tissue. They are developmentally similar to the ectoderm of the late-gastrula-stage embryo and behave like anterior primitive streak cells when differentiated in vitro and in vivo. The EpiSC lines that we derived can also be categorized based on a correlation between gene expression signature and predisposition to differentiate into particular germ-layer derivatives. Our findings therefore highlight distinct identifying characteristics of EpiSCs and provide a foundation for further examination of EpiSC properties and potential. PMID:24139757

Kojima, Yoji; Kaufman-Francis, Keren; Studdert, Joshua B; Steiner, Kirsten A; Power, Melinda D; Loebel, David A F; Jones, Vanessa; Hor, Angelyn; de Alencastro, Gustavo; Logan, Grant J; Teber, Erdahl T; Tam, Oliver H; Stutz, Michael D; Alexander, Ian E; Pickett, Hilda A; Tam, Patrick P L

2014-01-01

380

Early detection of toxigenic fungi on maize by hyperspectral imaging analysis.  

PubMed

Fungi can grow on many food commodities. Some fungal species, such as Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger and Fusarium spp., can produce, under suitable conditions, mycotoxins, secondary metabolites which are toxic for humans and animals. Toxigenic fungi are a real issue, especially for the cereal industry. The aim of this work is to carry out a non destructive, hyperspectral imaging-based method to detect toxigenic fungi on maize kernels, and to discriminate between healthy and diseased kernels. A desktop spectral scanner equipped with an imaging based spectrometer ImSpector- Specim V10, working in the visible-near infrared spectral range (400-1000 nm) was used. The results show that the hyperspectral imaging is able to rapidly discriminate commercial maize kernels infected with toxigenic fungi from uninfected controls when traditional methods are not yet effective: i.e. from 48 h after inoculation with A. niger or A. flavus. PMID:20869132

Del Fiore, A; Reverberi, M; Ricelli, A; Pinzari, F; Serranti, S; Fabbri, A A; Bonifazi, G; Fanelli, C

2010-11-15

381

Early maize pollen from Chaco Canyon, New Mexico, USA  

Microsoft Academic Search

Pollen concentrations containing abundant Zea mays pollen grains are AMS radiocarbon dated 3940 ± 40 to 2450 ± 40 C years BP. The maize pollen is from two prehistoric woodrat (Neotoma) middens that occur in fractures in the south-facing sandstone cliff at Chaco Culture National Historical Park. The diameters of the Archaic-age maize pollen grains are significantly larger than Puebloan and modern maize pollen.

Stephen A. Hall

2010-01-01

382

Biotechnology Approaches to Improving Maize Nitrogen Use Efficiency  

Microsoft Academic Search

Nitrogen (N) is an essential and often limiting nutrient to plant growth. Maize grain yields are highly responsive to supplemental\\u000a N, leading to annual application of an estimated 10 million metric tons of N fertilizer to the maize crop worldwide (FAO 2004).\\u000a Nearly all cultivated maize in developed countries receives some form of N fertilizer and N use is increasing

Stephen Moose

383

Constitutive expression of fluorescent protein by Aspergillus var. niger and Aspergillus carbonarius to monitor fungal colonization in maize plants.  

PubMed

Aspergillus niger and Aspergillus carbonarius are two species in the Aspergillus section Nigri (black-spored aspergilli) frequently associated with peanut (Arachis hypogea), maize (Zea mays), and other plants as pathogens. These infections are symptomless and as such are major concerns since some black aspergilli produce important mycotoxins, ochratoxins A, and the fumonisins. To facilitate the study of the black aspergilli-maize interactions with maize during the early stages of infections, we developed a method that used the enhanced yellow fluorescent protein (eYFP) and the monomeric red fluorescent protein (mRFP1) to transform A. niger and A. carbonarius, respectively. The results were constitutive expressions of the fluorescent genes that were stable in the cytoplasms of hyphae and conidia under natural environmental conditions. The hyphal in planta distribution in 21-day-old seedlings of maize were similar wild type and transformants of A. niger and A. carbonarius. The in planta studies indicated that both wild type and transformants internally colonized leaf, stem and root tissues of maize seedlings, without any visible disease symptoms. Yellow and red fluorescent strains were capable of invading epidermal cells of maize roots intercellularly within the first 3 days after inoculation, but intracellular hyphal growth was more evident after 7 days of inoculation. We also tested the capacity of fluorescent transformants to produce ochratoxin A and the results with A. carbonarius showed that this transgenic strain produced similar concentrations of this secondary metabolite. This is the first report on the in planta expression of fluorescent proteins that should be useful to study the internal plant colonization patterns of two ochratoxigenic species in the Aspergillus section Nigri. PMID:23899775

Palencia, Edwin Rene; Glenn, Anthony Elbie; Hinton, Dorothy Mae; Bacon, Charles Wilson

2013-09-01

384

Transcriptome analysis of embryo maturation in maize  

PubMed Central

Background Maize is one of the most important crops in the world. With the exponentially increasing population and the need for ever increased food and feed production, an increased yield of maize grain (as well as rice, wheat and other grains) will be critical. Maize grain development is understood from the perspective of morphology, hormone responses, and storage reserve accumulation. This includes various studies on gene expression during embryo development and maturation but a global study of gene expression of the embryo has not been possible until recently. Transcriptome analysis is a powerful new tool that can be used to understand the genetic basis of embryo maturation. Results We undertook a transcriptomic analysis of normal maturing embryos at 15, 21 and 27 days after pollination (DAP), of one elite maize germplasm line that was utilized in crosses to transgenic plants. More than 19,000 genes were analyzed by this method and the challenge was to select subsets of genes that are vitally important to embryo development and maturation for the initial analysis. We describe the changes in expression for genes relating to primary metabolic pathways, DNA synthesis, late embryogenesis proteins and embryo storage proteins, shown through transcriptome analysis and confirmed levels of transcription for some genes in the transcriptome using qRT-PCR. Conclusions Numerous genes involved in embryo maturation have been identified, many of which show changes in expression level during the progression from 15 to 27 DAP. An expected array of genes involved in primary metabolism was identified. Moreover, more than 30% of transcripts represented un-annotated genes, leaving many functions to be discovered. Of particular interest are the storage protein genes, globulin-1, globulin-2 and an unidentified cupin family gene. When expressing foreign proteins in maize, the globulin-1 promoter is most often used, but this cupin family gene has much higher expression and may be a better candidate for foreign gene expression in maize embryos. Results such as these allow identification of candidate genes and promoters that may not otherwise be available for use. mRNA seq data archived in NCBI SRA; Accession number: ACC=SRA060791 subid=108584.

2013-01-01

385

Comparative study on concentrations of deoxynivalenol and zearalenone in kernels of transgenic Bt maize hybrids and nontransgenic maize hybrids.  

PubMed

Ears from seven pairs of Bt maize hybrids / isogenic maize hybrids from field experiments in the year 1999 were collected arbitrarily and divided into corn borer (ECB) infested and not infested ears, respectively. The kernels were analysed for the mycotoxins deoxynivalenol (DON) and zearalenone (ZON).The percentage of infested ears was significantly lower in case of Bt maize (5%) as compared with non transgenic maize (31%). The study demonstrated further that the DON concentration in kernels of ECB infested ears of the non Bt maize hybrids was significantly higher than the DON concentration of the other groups. In the case of zearalenone, the same trend was observed. When the mean concentrations of the Bt and non-Bt hybrids, respectively, are considered, the lower contamination of Bt maize hybrids with DON and ZON, compared with their isogenic counterparts, is even more evident. PMID:23605751

Valenta, H; Dänicke, S; Flachowsky, G; Böhme, T

2001-03-01

386

Meso-beta scale numerical simulation studies of terrain-induced jet streak mass/momentum perturbations  

NASA Technical Reports Server (NTRS)

Mesoscale model simulations provide insight into the complex jet streak adjustments on 11-12 July 1981 that preceded the first of two significant gravity wave events to have been generated over the Rocky Mountains in Montana. Simulations employing a variety of terrain treatments indicate that prior to wave formation, geostrophic adjustment processes modified the structure of the mid-upper tropospheric jet streak by creating secondary jetlets to the southeast of the polar jet streak in proximity to the gravity wave generation region. This simulated restructuring of the mid-upper tropospheric jet streak is the result of a four stage process. During stage 1, the wind adjusts to the mass field as the jet streak exit region propagates into the inflection point between the upstream trough and downstream ridge in the height field. Stage 2 is initiated as the mass field is forced to adjust to the new ageostrophic wind field created during stage 1. Stage 3 is defined by a second geostrophic adjustment process occurring in a similar manner but to the south and east of the adjustment which occurs during stage 1. A low-level mesoscale jetlet is formed during stage 4 in response to the low-level pressure falls that are established during stage 3. The perturbation of this jetlet, caused by orographically-induced adiabatic and diabatic physical processes, is the likely mechanism responsible for the generation of the first and second episode of observed gravity waves. The dynamics responsible for this wave episode are discussed as differential surface sensible heating inducing an orographically-forced mountain-plains solenoid, resulting in the formation of additional mesoscale jetlets and internal gravity waves. Also discussed is how convective latent heating modifies the numerically simulated terrain-induced internal gravity waves, especially their amplitude and phase velocities, which provide better agreement with those wave characteristics observed in nature. Finally, the three-dimensional linear response of a zonally uniform barotropic flow in a vertically unbounded, continuously stratified, Boussinesq atmosphere which is perturbed from geostrophic equilibrium is investigated.

Lin, Yuh-Lang; Kaplan, Michael L.

1995-01-01

387

Comparative diversity of arthropods on Bt maize and non-Bt maize in two different cropping systems in South Africa.  

PubMed

The biodiversity of an agroecosystem is not only important for its intrinsic value but also because it influences ecological functions that are vital for crop production in sustainable agricultural systems and the surrounding environment. A concern about genetically modified (GM) crops is the potential negative impact that such crops could have on diversity and abundance of nontarget organisms, and subsequently on ecosystem functions. Therefore, it is essential to assess the potential environmental risk of the release of a GM crop and to study its effect on species assemblages within that ecosystem. Assessment of the impact of Bt maize on the environment is hampered by the lack of basic checklists of species present in maize agroecosystems. The aims of the study were to compile a checklist of arthropods that occur on maize in South Africa and to compare the diversity and abundance of arthropods and functional groups on Bt maize and non-Bt maize. Collections of arthropods were carried out during two growing seasons on Bt maize and non-Bt maize plants at two localities. Three maize fields were sampled per locality during each season. Twenty plants, each of Bt maize and non-Bt maize, were randomly selected from the fields at each site. The arthropods collected during this study were classified to morphospecies level and grouped into the following functional groups: detritivores, herbivores, predators, and parasitoids. Based on feeding strategy, herbivores and predators were further divided into sucking herbivores or predators (piercing-sucking mouthparts) and chewing herbivores or predators (chewing mouthparts). A total of 8,771 arthropod individuals, comprising 288 morphospecies and presenting 20 orders, were collected. Results from this short-term study indicated that abundance and diversity of arthropods in maize and the different functional guilds were not significantly affected by Bt maize, either in terms of diversity or abundance. PMID:24472209

Truter, J; Van Hamburg, H; Van Den Berg, J

2014-02-01

388

The ACAT inhibitor, CI-1011 is effective in the prevention and regression of aortic fatty streak area in hamsters.  

PubMed

The hypocholesterolemic and anti-atherogenic properties of sulfamic acid ((2,4,6-tris (1-methylethyl) phenyl) acetyl) 2,6-bis(1-methylethyl) phenyl ester, the ACAT inhibitor, CI-1011, was tested in 120 male F1B hamsters fed a hypercholesterolemic chow-based diet containing 10%, coconut oil and 0.05% cholesterol plus: (i) no drug treatment (HCD); (ii) 3 mg/kg per day (HCD+3): (iii)10 mg/kg per day (HCD+10); (iv) 30 mg/kg per day (HCD+30) of CI-1011; or (v) 500 mg/kg per day of cholestyramine (CSTY). Plasma samples were collected at 8 and 10 weeks for measurement of total cholesterol (TC), very low-density lipoprotein cholesterol (VLDL-C), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG). For the progression studies, animals were euthanized after 10 weeks for aortic fatty streak area and hepatic cholesterol analysis. For the regression study, a cohort of the HCD was treated with 30 mg/kg per day of CI-1011 (regression) for an additional 8 weeks. The HCD+3, HCD+10, HCD+30 and CSTY lowered plasma TC (25, 32, 34 and 32%, respectively), VLDL-C (62, 74, 71 and 75%, respectively), LDL-C (25, 38, 47 and 46%, respectively) and TG (48, 47, 42 and 45%, respectively). All treatments resulted in a significant lowering of aortic fatty streak area (68, 86, 93 and 94%, respectively) and reduction in hepatic cholesteryl esters (57, 65, 67 and 70%, respectively). Regression of aortic fatty streak area was 90% after 8 weeks of HCD+30 treatment. Also during the regression phase, plasma TC, LDL-C and TG were lowered 23, 33 and 47%, respectively, as well as, hepatic cholesteryl esters (76%). Significant correlations between plasma LDL-C concentration and aortic fatty streak area (r=0.62, P < 0.004) in the HCD+10 group, suggest that CI-1101 altered aortic lipid infiltration primarily by its effect on plasma lipids. However the 30 mg/kg per day dose of CI-1011 which additionally reduced aortic fatty streak area by 51% relative to the 10 mg/kg per day dose was only associated with a 14% further decrease in plasma LDL-C. Finally the 10-fold regression of aortic fatty streak area was associated with only a 35% reduction in plasma LDL-C. These exceptions to the lipid-lesion relationship raise the possibility of additional effects of CI-1011, which may occur independent of or in concert with lipoprotein cholesterol lowering. It is concluded that in hypercholesterolemic hamsters, CI-1011 is approximately 50 times more potent than cholestyramine in cholesterol-lowering, reduction and regression of aortic fatty streak area. PMID:9568739

Nicolosi, R J; Wilson, T A; Krause, B R

1998-03-01

389

Iron bioavailability of maize hemoglobin in a Caco-2 cell culture model.  

PubMed

Maize ( Zea mays ) is an important staple crop in many parts of the world but has low iron bioavailability, in part due to its high phytate content. Hemoglobin is a form of iron that is highly bioavailable, and its bioavailability is not inhibited by phytate. It was hypothesized that maize hemoglobin is a highly bioavailable iron source and that biofortification of maize with iron can be accomplished by overexpression of maize globin in the endosperm. Maize was transformed with a gene construct encoding a translational fusion of maize globin and green fluorescent protein under transcriptional control of the maize 27 kDa ?-zein promoter. Iron bioavailability of maize hemoglobin produced in Escherichia coli and of stably transformed seeds expressing the maize globin-GFP fusion was determined using an in vitro Caco-2 cell culture model. Maize flour fortified with maize hemoglobin was found to have iron bioavailability that is not significantly different from that of flour fortified with ferrous sulfate or bovine hemoglobin but is significantly higher than unfortified flour. Transformed maize grain expressing maize globin was found to have iron bioavailability similar to that of untransformed seeds. These results suggest that maize globin produced in E. coli may be an effective iron fortificant, but overexpressing maize globin in maize endosperm may require a different strategy to increase bioavailable iron content in maize. PMID:23834908

Bodnar, Anastasia L; Proulx, Amy K; Scott, M Paul; Beavers, Alyssa; Reddy, Manju B

2013-07-31

390

Root gravitropism in maize and Arabidopsis  

NASA Technical Reports Server (NTRS)

Research during the period 1 March 1992 to 30 November 1993 focused on improvements in a video digitizer system designed to automate the recording of surface extension in plants responding to gravistimulation. The improvements included modification of software to allow detailed analysis of localized extension patterns in roots of Arabidopsis. We used the system to analyze the role of the postmitotic isodiametric growth zone (a region between the meristem and the elongation zone) in the response of maize roots to auxin, calcium, touch and gravity. We also used the system to analyze short-term auxin and gravitropic responses in mutants of Arabidopsis with reduced auxin sensitivity. In a related project, we studied the relationship between growth rate and surface electrical currents in roots by examining the effects of gravity and thigmostimulation on surface potentials in maize roots.

Evans, Michael L.

1993-01-01

391

Auxin Biosynthesis in Maize Kernels1  

PubMed Central

Auxin biosynthesis was analyzed in a maize (Zea mays) kernel culture system in which the seeds develop under physiological conditions similar to the in vivo situation. This system was modified for precursor feeding experiments. Tryptophan (Trp) is efficiently incorporated into indole-3-acetic acid (IAA) with retention of the 3,3? bond. Conversion of Trp to IAA is not competed by indole. Labeling with the general precursors [U-13C6]glucose and [1,2-13C2]acetate followed by retrobiosynthetic analysis strongly suggest that Trp-dependent IAA synthesis is the predominant route for auxin biosynthesis in the maize kernel. The synthesis of IAA from indole glycerol phosphate and IAA formation via condensation of indole with an acetyl-coenzyme A or phosphoenolpyruvate derived metabolite can be excluded.

Glawischnig, Erich; Tomas, Adriana; Eisenreich, Wolfgang; Spiteller, Peter; Bacher, Adelbert; Gierl, Alfons

2000-01-01

392

Temperature sensing by primary roots of maize  

NASA Technical Reports Server (NTRS)

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

Poff, K. L.

1990-01-01

393

Maize canopies under two soil water regimes  

Microsoft Academic Search

The feasibility of determining at 5-min intervals the fluxes of water vapor and CO2 using a Bowen ratio\\/energy balance\\/CO2 gradient (BREB+) apparatus was studied. Details of the BREB+ apparatus are given. The results obtained over maize canopies at the short 5-min signal averaging time are examined in several aspects. One aspect is the fact that on days when net radiation

Pasquale Steduto; Theodore C. Hsiao

1998-01-01

394

Intraspecific variation of recombination rate in maize  

PubMed Central

Background In sexually reproducing organisms, meiotic crossovers ensure the proper segregation of chromosomes and contribute to genetic diversity by shuffling allelic combinations. Such genetic reassortment is exploited in breeding to combine favorable alleles, and in genetic research to identify genetic factors underlying traits of interest via linkage or association-based approaches. Crossover numbers and distributions along chromosomes vary between species, but little is known about their intraspecies variation. Results Here, we report on the variation of recombination rates between 22 European maize inbred lines that belong to the Dent and Flint gene pools. We genotype 23 doubled-haploid populations derived from crosses between these lines with a 50 k-SNP array and construct high-density genetic maps, showing good correspondence with the maize B73 genome sequence assembly. By aligning each genetic map to the B73 sequence, we obtain the recombination rates along chromosomes specific to each population. We identify significant differences in recombination rates at the genome-wide, chromosome, and intrachromosomal levels between populations, as well as significant variation for genome-wide recombination rates among maize lines. Crossover interference analysis using a two-pathway modeling framework reveals a negative association between recombination rate and interference strength. Conclusions To our knowledge, the present work provides the most comprehensive study on intraspecific variation of recombination rates and crossover interference strength in eukaryotes. Differences found in recombination rates will allow for selection of high or low recombining lines in crossing programs. Our methodology should pave the way for precise identification of genes controlling recombination rates in maize and other organisms.

2013-01-01

395

2D Optical Streaking for Ultra-Short Electron Beam Diagnostics  

SciTech Connect

We propose a novel approach to measure short electron bunch profiles at micrometer level. Low energy electrons generated during beam-gas ionization are simultaneously modulated by the transverse electric field of a circularly-polarized laser, and then they are collected at a downstream screen where the angular modulation is converted to a circular shape. The longitudinal bunch profile is simply represented by the angular distribution of the electrons on the screen. We only need to know the laser wavelength for calibration and there is no phase synchronization problem. Meanwhile the required laser power is also relatively low in this setup. Some simulations examples and experimental consideration of this method are discussed. At Linac Coherent Light Source (LCLS), an S-band RF transverse deflector (TCAV) is used to measure the bunch length with a resolution 10 femtosecond (fs) rms. An X-band deflector (wavelength 2.6cm) is proposed recently to improve the resolution. However, at the low charge operation mode (20pC), the pulse length can be as short as fs. It is very challenging to measure femtosecond and sub-femtosecond level bunch length. One of the methods is switching from RF to {mu}m level wavelength laser to deflect the bunch. A powerful laser ({approx}10s GW) is required to deflect such a high energy beam (GeV) in a wiggler. Synchronization is another difficulty: the jitter between the bunch and the laser can be larger than the laser wavelength, which makes single-shot measurement impossible. To reduce the laser power, we propose to use ionized electrons from high energy electron beam and gas interaction for high energy electron bunch diagnostics. Similarly, the femtosecond X-ray streak camera uses X-ray ionization electrons to measure the X-ray pulse. The electrons generated by beam-gas ionization have low energy (eVs). Therefore, a lower laser power is possible to deflect such low energy electrons. Note that there is no field ionization in our case. To avoid field ionization, which occurs in plasma case, gases species with high field ionization threshold should be considered. For a linear polarized laser, the kick to the ionized electrons depends on the phase of the laser when the electrons are born and the unknown timing jitter between the electron beam and laser beam makes the data analysis very difficult. Here we propose to use a circular polarized laser to do a 2-dimensional (2D) streaking (both x and y) and measure the bunch length from the angular distribution on the screen, where the phase jitter causes only a rotation of the image on the screen without changing of the relative angular distribution. Also we only need to know the laser wavelength for calibration. A similar circular RF deflecting mode was used to measure long bunches. We developed a numerical particle-in-Cell (PIC) code to study the dynamics of ionization electrons with the high energy beam and the laser beam.

Ding, Y.T.; Huang, Z.; Wang, L.; /SLAC

2011-12-14

396

Brassinosteroid control of sex determination in maize  

PubMed Central

Brassinosteroids (BRs) are plant hormones that regulate growth and development. They share structural similarities with animal steroids, which are decisive factors of sex determination. BRs are known to regulate morphogenesis and environmental stress responses, but their involvement in sex determination in plants has been only speculative. We show that BRs control sex determination in maize revealed through characterization of the classical dwarf mutant nana plant1 (na1), which also feminizes male flowers. na1 plants carry a loss-of-function mutation in a DET2 homolog—a gene in the BR biosynthetic pathway. The mutant accumulates the DET2-specific substrate (24R)-24-methylcholest-4-en-3-one with a concomitant decrease of downstream BR metabolites. Treatment of wild-type maize plants with BR biosynthesis inhibitors completely mimicked both dwarf and tasselseed phenotypes of na1 mutants. Tissue-specific na1 expression in anthers throughout their development supports the hypothesis that BRs promote masculinity of the male inflorescence. These findings suggest that, in the monoecious plant maize, BRs have been coopted to perform a sex determination function not found in plants with bisexual flowers.

Hartwig, Thomas; Chuck, George S.; Fujioka, Shozo; Klempien, Antje; Weizbauer, Renate; Potluri, Devi Prasad V.; Choe, Sunghwa; Johal, Gurmukh S.; Schulz, Burkhard

2011-01-01

397

Gibberellins and Heterosis in Maize 1  

PubMed Central

Under controlled environment and/or field conditions, vegetative growth (height, internode length, leaf area, shoot dry weight, grain yield) was greater in an F1 maize hybrid than in either parental inbred. Endogenous gibberellin (GA)-like substances in apical meristem cylinders were also higher in the hybrid than in either inbred, both on a per plant and per gram dry weight basis. There were no apparent qualitative differences in GA-like substances, however. Levels of GA-like substances in all genotypes were highest prior to tassel initiation. Chromatographic comparisons of the GA-like substances and authentic standards of GA native to maize on gradient-eluted SiO2 partition and reverse-phase C18 high-pressure liquid chromatography columns are described. No consistent differences in abscisic acid levels of the three genotypes were observed. This correlation of heterosis for endogenous GA-like substances with heterosis for growth suggests that amounts of endogenous GA may be related to hybrid vigor in maize. Images Fig. 1

Rood, Stewart B.; Pharis, Richard P.; Koshioka, Masaji; Major, David J.

1983-01-01

398

Lipids in Aspergillus flavus-maize interaction.  

PubMed

In some filamentous fungi, the pathways related to the oxidative stress and oxylipins production are involved both in the process of host-recognition and in the pathogenic phase. In fact, recent studies have shown that the production of oxylipins in filamentous fungi, yeasts and chromists is also related to the development of the organism itself and to mechanisms of communication with the host at the cellular level. The oxylipins, also produced by the host during defense reactions, are able to induce sporulation and to regulate the biosynthesis of mycotoxins in several pathogenic fungi. In A. flavus, the oxylipins play a crucial role as signals for regulating the biosynthesis of aflatoxins, the conidiogenesis and the formation of sclerotia. To investigate the involvement of an oxylipins based cross-talk into Z. mays and A. flavus interaction, we analyzed the oxylipins profile of the wild type strain and of three mutants of A. flavus that are deleted at the Aflox1 gene level also during maize kernel invasion. A lipidomic approach has been addressed through the use of LC-ToF-MS, followed by a statistical analysis of the principal components (PCA). The results showed the existence of a difference between the oxylipins profile generated by the WT and the mutants onto challenged maize. In relation to this, aflatoxin synthesis which is largely hampered in vitro, is intriguingly restored. These results highlight the important role of maize oxylipin in driving secondary metabolism in A. flavus. PMID:24578700

Scarpari, Marzia; Punelli, Marta; Scala, Valeria; Zaccaria, Marco; Nobili, Chiara; Ludovici, Matteo; Camera, Emanuela; Fabbri, Anna A; Reverberi, Massimo; Fanelli, Corrado

2014-01-01

399

Historical genomics of North American maize  

PubMed Central

Since the advent of modern plant breeding in the 1930s, North American maize has undergone a dramatic adaptation to high-input agriculture. Despite the importance of genetic contributions to historical yield increases, little is known about the underlying genomic changes. Here we use high-density SNP genotyping to characterize a set of North American maize lines spanning the history of modern breeding. We provide a unique analysis of genome-wide developments in genetic diversity, ancestry, and selection. The genomic history of maize is marked by a steady increase in genetic differentiation and linkage disequilibrium, whereas allele frequencies in the total population have remained relatively constant. These changes are associated with increasing genetic separation of breeding pools and decreased diversity in the ancestry of individual lines. We confirm that modern heterotic groups are the product of ongoing divergence from a relatively homogeneous landrace population, but show that differential landrace ancestry remains evident. Using a recent association approach, we characterize signals of directional selection throughout the genome, identifying a number of candidate genes of potential agronomic relevance. However, overall we find that selection has had limited impact on genome-wide patterns of diversity and ancestry, with little evidence for individual lines contributing disproportionately to the accumulation of favorable alleles in today's elite germplasm. Our data suggest breeding progress has mainly involved selection and recombination of relatively common alleles, contributed by a representative but limited set of ancestral lines.

van Heerwaarden, Joost; Hufford, Matthew B.; Ross-Ibarra, Jeffrey

2012-01-01

400

Hydroxamic Acid Glucosyltransferases from Maize Seedlings 1  

PubMed Central

Hydroxamic acids occur in several forms in maize (Zea mays L.) with 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) being the predominant form and others including 2,4-dihydroxy-1,4-benzoxazin-3-one (DIBOA) being found at lower concentrations. Two enzymes capable of glucosylating hydroxamic acids were identified in maize protein extracts and partially purified and characterized. The total enzyme activity per seedling increased during the first 4 days of germination and was concurrent with the accumulation of DIMBOA. Purification of the enzymes by ammonium sulfate precipitation followed by Sephadex G-200 and Q-Sepharose gel chromatography resulted in a 13-fold increase in specific activity. The enzymes are initially separated into two peaks (peak 1 and peak 2) of activity by Q-Sepharose gel chromatography. The peak 1 glucosyltransferase had 3.6% of the DIMBOA glucosylating activity when DIBOA was used as substrate, whereas this percentage increased to 57% for the peak 2 enzyme. The enzyme in peak 2 has a Km of 174 micromolar for DIMBOA and a Km of 638 micromolar for DIBOA; the enzyme in peak 1 has a Km of 217 micromolar for DIMBOA and its activity on DIBOA was too low to determine a Km. The identification of two glucosyltransferases capable of glucosylating hydroxamic acids in vitro serves as an initial step in the characterization of the enzymes involved in production of hydroxamic acids in maize.

Bailey, Bryan A.; Larson, Russell L.

1989-01-01

401

Aflatoxin Regulations in a Network of Global Maize Trade  

PubMed Central

Worldwide, food supplies often contain unavoidable contaminants, many of which adversely affect health and hence are subject to regulations of maximum tolerable levels in food. These regulations differ from nation to nation, and may affect patterns of food trade. We soughtto determine whether there is an association between nations' food safety regulations and global food trade patterns, with implications for public health and policymaking. We developed a network model of maize trade around the world. From maize import/export data for 217 nations from 2000–2009, we calculated basic statistics on volumes of trade; then examined how regulations of aflatoxin, a common contaminant of maize, are similar or different between pairs of nations engaging in significant amounts of maize trade. Globally, market segregation appears to occur among clusters of nations. The United States is at the center of one cluster; European countries make up another cluster with hardly any maize trade with the US; and Argentina, Brazil, and China export maize all over the world. Pairs of nations trading large amounts of maize have very similar aflatoxin regulations: nations with strict standards tend to trade maize with each other, while nations with more relaxed standards tend to trade maize with each other. Rarely among the top pairs of maize-trading nations do total aflatoxin standards (standards based on the sum of the levels of aflatoxins B1, B2, G1, and G2) differ by more than 5 µg/kg. These results suggest that, globally, separate maize trading communities emerge; and nations tend to trade with other nations that have very similar food safety standards.

Wu, Felicia; Guclu, Hasan

2012-01-01

402

Dietary fish oil enhances monocyte adhesion and fatty streak formation in the hypercholesterolemic rat.  

PubMed Central

Using the rat model of atherosclerosis, the influence of dietary fish oil on early stages of atherosclerotic lesion formation was studied. Normocholesterolemic rats (serum cholesterol less than 100 mg/dl), moderately hypercholesterolemic rats fed cholesterol and cholic acid (serum cholesterol less than 400 mg/dl), and severely hypercholesterolemic rats fed cholesterol, cholic acid, and 2-thiouracil (serum cholesterol greater than 900 mg/dl) had their diets supplemented with 5% (w/w) "MaxEPA" fish oil for a period of 2 weeks. In each diet group safflower oil was used as a control for fish oil. Monocyte adhesion to the thoracic aorta and intimal foam cell formation were used to measure the extent of atherosclerotic lesion formation in each rat. Cholesterol and triglyceride levels were measured in both plasma and lipoprotein fractions. In normocholesterolemic rats, fish oil did not influence the morphology of the vessel wall. In moderately hypercholesterolemic rats, monocyte adhesion was the same irrespective of dietary oil, however, intimal foam cell formation was 2-fold higher in the fish oil-fed animals despite a reduction in serum cholesterol levels when compared to the safflower oil-fed animals. In severely hypercholesterolemic rats, monocyte adhesion to the vessel wall and intimal foam cell formation were both 4-fold higher in the fish oil compared with the safflower oil fed animals. These observations could not be attributed to differences in the plasma or lipoprotein profiles of safflower oil vs. fish oil fed rats. The results of this study suggest that dietary fish oil, when fed to hypercholesterolemic rats for a period of 2 weeks, enhances the rate of monocyte adhesion and fatty streak formation in the thoracic aorta.

Rogers, K. A.; Karnovsky, M. J.

1988-01-01

403

Neutron Radiation Shielding For The NIF Streaked X-Ray Detector (SXD) Diagnostic  

SciTech Connect

The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) is preparing for the National Ignition Campaign (NIC) scheduled in 2010. The NIC is comprised of several ''tuning'' physics subcampaigns leading up to a demonstration of Inertial Confinement Fusion (ICF) ignition. In some of these experiments, time-resolved x-ray imaging of the imploding capsule may be required to measure capsule trajectory (shock timing) or x-ray ''bang-time''. A capsule fueled with pure tritium (T) instead of a deutriun-tritium (DT) mixture is thought to offer useful physics surrogacy, with reduced yields of up to 5e14 neutrons. These measurements will require the use of the NIF streak x-ray detector (SXD). The resulting prompt neutron fluence at the planned SXD location ({approx}1.7 m from the target) would be {approx}1.4e9/cm{sup 2}. Previous measurements suggest the onset of significant background at a neutron fluence of {approx} 1e8/cm{sup 2}. The radiation damage and operational upsets which starts at {approx}1e8 rad-Si/sec must be factored into an integrated experimental campaign plan. Monte Carlo analyses were performed to predict the neutron and gamma/x-ray fluences and radiation doses for the proposed diagnostic configuration. A possible shielding configuration is proposed to mitigate radiation effects. The primary component of this shielding is an 80 cm thickness of Polyethylene (PE) between target chamber center (TCC) and the SXD diagnostic. Additionally, 6-8 cm of PE around the detector provide from the large number of neutrons that scatter off the inside of the target chamber. This proposed shielding configuration reduces the high-energy neutron fluence at the SXD by approximately a factor {approx}50.

Song, P; Holder, J; Young, B; Kalantar, D; Eder, D; Kimbrough, J

2006-11-02

404

Phenolics in maize genotypes differing in susceptibility to Gibberella stalk rot (Fusarium graminearum Schwabe).  

PubMed

The relationship between phenolic compounds and maize pith resistance to Fusarium graminearum, the causal agent of Gibberella stalk rot, was investigated. The phenolic acid profiles in the stalks of six maize inbred lines of varying susceptibility were evaluated from silking to grain maturity. Four different fractions of phenolic compounds were extracted from inoculated and non-inoculated (control) pith tissues: insoluble cell-wall-bound, free, soluble ester-bound, and soluble glycoside-bound phenolics. Analysis by HPLC revealed that p-coumaric acid and ferulic acid were the most abundant compounds in the soluble and cell-wall-bound fractions. The quantity of free, glycoside-bound, and ester-bound phenolics in the pith was lower than the level required for the inhibition of Fusarium growth or mycotoxins production; however, significant negative correlations between diferulic acid contents in the cell walls and disease severity ratings 4 days after inoculation were found. The results indicated that future studies should focus on the levels of diferulic acids during the early infection process. Diferulates may play a role in genotypic resistance of maize to Gibberella stalk rot as preformed barriers to infection. PMID:17547419

Santiago, Rogelio; Reid, Lana M; Arnason, John T; Zhu, Xiaoyang; Martinez, Noelia; Malvar, Rosa A

2007-06-27

405

Proteomic profiling of two maize inbreds during early gibberella ear rot infection.  

PubMed

Fusarium graminearum is the causal agent of gibberella ear rot in maize ears, resulting in yield losses due to mouldy and mycotoxin-contaminated grain. This study represents a global proteomic approach to document the early infection by F. graminearum of two maize inbreds, B73 and CO441, which differ in disease susceptibility. Mock- and F. graminearum-treated developing kernels were sampled 48?h post-inoculation over three field seasons. Infected B73 kernels consistently contained higher concentrations of the mycotoxin deoxynivalenol than the kernels of the more tolerant inbred CO441. A total of 2067 maize proteins were identified in the iTRAQ analysis of extracted kernel proteins at a 99% confidence level. A subset of 878 proteins was identified in at least two biological replicates and exhibited statistically significantly altered expression between treatments and/or the two inbred lines of which 96 proteins exhibited changes in abundance >1.5-fold in at least one of the treatments. Many proteins associated with the defense response were more abundant after infection, including PR-10 (PR, pathogenesis-related), chitinases, xylanase inhibitors, proteinase inhibitors, and a class III peroxidase. Kernels of the tolerant inbred CO441 contained higher levels of these defense-related proteins than B73 kernels even after mock treatment, suggesting that these proteins may provide a basal defense against Fusarium infection in CO441. PMID:21751381

Mohammadi, Mohsen; Anoop, Valar; Gleddie, Steve; Harris, Linda J

2011-09-01

406

Identification and molecular tagging of two complementary dominant resistance genes to maize dwarf mosaic virus.  

PubMed

Maize dwarf mosaic is one of the devastating and widespread viral diseases in the world. So far, only a few genes were identified and mapped in the resistant materials. A new resistant elite inbred line Siyi was identified with resistance to maize dwarf mosaic virus strain B at early and adult stage. Two complementary dominant genes conditioned the resistance, with a new genetic model, of the maize inbred line were found at adult stage by the genetic analysis based on parents, F1, F2 and backcrosses in two years. The microsatellite analysis of a F2 population from the cross between Siyi and Mo17 was used to identify the two resistance genes on chromosome 3 and 6 respectively by 87 pairs of microsatellite markers. The linkage distance between phi029 and the one resistance gene on chromosome 3 is 14.5 cM, and phi126 to the other on chromosome 6 is 7.2 cM. PMID:12693101

Wu, Jian-Yu; Ding, Jun-Qiang; Du, Yan-Xiu; Chen, Wei-Cheng

2002-12-01

407

Ancient maize from Chacoan great houses: Where was it grown?  

Microsoft Academic Search

In this article, we compare chemical (87Sr\\/86Sr and elemental) analyses of archaeological maize from dated contexts within Pueblo Bonito, Chaco Canyon, New Mexico, to potential agricultural sites on the periphery of the San Juan Basin. The oldest maize analyzed from Pueblo Bonito probably was grown in an area located 80 km to the west at the base of the Chuska

Larry Benson; Linda Cordell; Kirk Vincent; Howard Taylor; John Stein; G. Lang Farmer; Kiyoto Futa

2003-01-01

408

Development and mapping of SSR markers for maize  

Microsoft Academic Search

Microsatellite or simple sequence repeat (SSR) markers have wide applicability for genetic analysis in crop plant improvement strategies. The objectives of this project were to isolate, characterize, and map a comprehensive set of SSR markers for maize (Zea mays L.). We developed 1051 novel SSR markers for maize from microsatellite-enriched libraries and by identification of microsatellite-containing sequences in public and

Natalya Sharopova; Michael D. McMullen; Linda Schultz; Steve Schroeder; Hector Sanchez-Villeda; Jack Gardiner; Dean Bergstrom; Katherine Houchins; Susan Melia-Hancock; Theresa Musket; Ngozi Duru; Mary Polacco; Keith Edwards; Thomas Ruff; James C. Register; Cory Brouwer; Richard Thompson; Riccardo Velasco; Emily Chin; Michael Lee; Wendy Woodman-Clikeman; Mary Jane Long; Emmanuel Liscum; Karen Cone; Georgia Davis; Edward H. Coe

2002-01-01

409

Mutant maize variety containing the glt1-1 allele  

DOEpatents

A maize plant has in its genome a non-mutable form of a mutant allele designated vitX-8132. The allele is located at a locus designated as glt which conditions kernels having an altered starch characteristic. Maize plants including such a mutant allele produce a starch that does not increase in viscosity on cooling, after heating.

Nelson, Oliver E. (Cross Plains, WI); Pan, David (Madison, WI)

1994-01-01

410

Metabolomic Analysis of Low Phytic Acid Maize Kernels  

Microsoft Academic Search

Phytic acid, or hexaphosphorylated myo-inositol, is the major storage form of phosphorous (P) in maize kernels. Phytic acid in foods or animal feeds can complex with proteins and mineral cations resulting in reduced bioavailablility of important nutrients. Classic mutation breeding has been used to develop maize plants that produce kernels with significantly less phytic acid. An extensive survey of the

Jan Hazebroek; Teresa Harp; Jinrui Shi; Hongyu Wang

411

Analytical Economic Study of Maize Production in Egypt.  

National Technical Information Service (NTIS)

Total maize consumption in Egypt has more than doubled in the past 20 years and may double again by the year 2000, far exceeding feasible production and import levels. Constraints to increased maize yield include insufficient local production of high-yiel...

A. M. M. Basheer

1981-01-01

412

Purification and Characterization of Soluble Starch Synthases from Maize Endosperm  

Microsoft Academic Search

This study identified and characterized the soluble starch synthase of maize endosperm that was initially revealed as the SSII activity peak in anion exchange chromatography (J. L. Ozbun et al. (1971) Plant Physiol. 48, 765–769). At least six different genes coding for starch synthases are expressed in maize, although previously it was not known which of these is responsible for

Heping Cao; Martha G James; Alan M Myers

2000-01-01

413

Mutant maize variety containing the glt1-1 allele  

DOEpatents

A maize plant has in its genome a non-mutable form of a mutant allele designated vitX-8132. The allele is located at a locus designated as glt which conditions kernels having an altered starch characteristic. Maize plants including such a mutant allele produce a starch that does not increase in viscosity on cooling, after heating. 2 figs.

Nelson, O.E.; Pan, D.

1994-07-19

414

In vivo pollination with maize pollen stored in aqueous medium.  

National Technical Information Service (NTIS)

A hypertonic aqueous medium can be used to obtain non-bursting, non-germinating maize (zea mays L.) pollen suspensions, which can be stored at 0(sub 0)C preserving pollen viability. This medium could be used in different techniques for maize pollen geneti...

M. Broglia

1994-01-01

415

The art and design of genetic screens: maize  

Microsoft Academic Search

Maize (Zea mays) is an excellent model for basic research. Genetic screens have informed our understanding of developmental processes, meiosis, epigenetics and biochemical pathways — not only in maize but also in other cereal crops. We discuss the forward and reverse genetic screens that are possible in this organism, and emphasize the available tools. Screens exploit the well-studied behaviour of

Héctor Candela; Sarah Hake

2008-01-01

416

Sporophytic control of pollen tube growth and guidance in maize.  

PubMed

Pollen tube germination, growth, and guidance (progamic phase) culminating in sperm discharge is a multi-stage process including complex interactions between the male gametophyte as well as sporophytic tissues and the female gametophyte (embryo sac), respectively. Inter- and intra-specific crossing barriers in maize and Tripsacum have been studied and a precise description of progamic pollen tube development in maize is reported here. It was found that pollen germination and initial tube growth are rather unspecific, but an early, first crossing barrier was detected before arrival at the transmitting tract. Pollination of maize silks with Tripsacum pollen and incompatible pollination of Ga1s/Ga1s-maize silks with ga1-maize pollen revealed another two incompatibility barriers, namely transmitting tract mistargeting and insufficient growth support. Attraction and growth support by the transmitting tract seem to play key roles for progamic pollen tube growth. After leaving transmitting tracts, pollen tubes have to navigate across the ovule in the ovular cavity. Pollination of an embryo sac-less maize RNAi-line allowed the role of the female gametophyte for pollen tube guidance to be determined in maize. It was found that female gametophyte controlled guidance is restricted to a small region around the micropyle, approximately 50-100 microm in diameter. This area is comparable to the area of influence of previously described ZmEA1-based short-range female gametophyte signalling. In conclusion, the progamic phase is almost completely under sporophytic control in maize. PMID:19926683

Lausser, Andreas; Kliwer, Irina; Srilunchang, Kanok-orn; Dresselhaus, Thomas

2010-03-01

417

PCR detection of genetically modified soya and maize in foodstuffs  

Microsoft Academic Search

The detection of genetically modified foodstuffs is becoming both a food sales and legal necessity. This study reports a rapid DNA extraction\\/PCR-based method for the detection of genetically modified soya (GMS) and maize (GMM) in mixed samples of transgenic and unmodified soybeans and maize kernels, and a variety of processed samples including soya flour, soya protein isolates, extruded defatted soya,

Carolyn D. Hurst; Angus Knight; Ian J. Bruce

1999-01-01

418

Adoption of Maize Conservation Tillage in Azuero, Panama  

Microsoft Academic Search

An aggressive research and validation program launched in 1984 in Azuero, Panama, yielded a recommendation advocating zero tillage for maize production. Ten years later, maize farmers in Azuero used three land preparation methods: conventional tillage, zero tillage, and minimum tillage (an adaptation of the zero tillage technology). This study aimed to quantify the adoption of zero and minimum tillage for

Adys Pereira de Herrera; Gustavo Sain

1999-01-01

419

Explaining Productivity Variation among Smallholder Maize Farmers in Tanzania  

Microsoft Academic Search

Using a stochastic frontier production model proposed by Battese and Coelli (1995), the