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1

Inducible Resistance to Maize Streak Virus  

PubMed Central

Maize streak virus (MSV), which causes maize streak disease (MSD), is the major viral pathogenic constraint on maize production in Africa. Type member of the Mastrevirus genus in the family Geminiviridae, MSV has a 2.7 kb, single-stranded circular DNA genome encoding a coat protein, movement protein, and the two replication-associated proteins Rep and RepA. While we have previously developed MSV-resistant transgenic maize lines constitutively expressing “dominant negative mutant” versions of the MSV Rep, the only transgenes we could use were those that caused no developmental defects during the regeneration of plants in tissue culture. A better transgene expression system would be an inducible one, where resistance-conferring transgenes are expressed only in MSV-infected cells. However, most known inducible transgene expression systems are hampered by background or “leaky” expression in the absence of the inducer. Here we describe an adaptation of the recently developed INPACT system to express MSV-derived resistance genes in cell culture. Split gene cassette constructs (SGCs) were developed containing three different transgenes in combination with three different promoter sequences. In each SGC, the transgene was split such that it would be translatable only in the presence of an infecting MSV’s replication associated protein. We used a quantitative real-time PCR assay to show that one of these SGCs (pSPLITrepIII-Rb-Ubi) inducibly inhibits MSV replication as efficiently as does a constitutively expressed transgene that has previously proven effective in protecting transgenic maize from MSV. In addition, in our cell-culture based assay pSPLITrepIII-Rb-Ubi inhibited replication of diverse MSV strains, and even, albeit to a lesser extent, of a different mastrevirus species. The application of this new technology to MSV resistance in maize could allow a better, more acceptable product. PMID:25166274

Shepherd, Dionne N.; Dugdale, Benjamin; Martin, Darren P.; Varsani, Arvind; Lakay, Francisco M.; Bezuidenhout, Marion E.; Monjane, Aderito L.; Thomson, Jennifer A.; Dale, James; Rybicki, Edward P.

2014-01-01

2

Inhibition of maize streak virus (MSV) replication by transient and transgenic expression of MSV replication-associated protein mutants  

Microsoft Academic Search

Maize streak disease is a severe agricultural problem in Africa and the development of maize genotypes resistant to the causal agent, Maize streak virus (MSV), is a priority. A transgenic approach to engineering MSV-resistant maize was developed and tested in this study. A pathogen- derived resistance strategy was adopted by using targeted deletions and nucleotide-substitution mutants of the multifunctional MSV

Dionne N. Shepherd; Tichaona Mangwende; Darren P. Martin; Marion Bezuidenhout; Jennifer A. Thomson; Edward P. Rybicki

2007-01-01

3

A high degree of African streak virus diversity within Nigerian maize fields includes a new mastrevirus from Axonopus compressus.  

PubMed

The A-strain of maize streak virus (MSV-A; genus Mastrevirus, family Geminiviridae), the causal agent of maize streak disease, places a major constraint on maize production throughout sub-Saharan Africa. In West-African countries such as Nigeria, where maize is not cultivated year-round, this MSV strain is forced to overwinter in non-maize hosts. In order to both identify uncultivated grasses that might harbour MSV-A during the winter season and further characterise the diversity of related maize-associated streak viruses, we collected maize and grass samples displaying streak symptoms in a number of Nigerian maize fields. From these we isolated and cloned 18 full mastrevirus genomes (seven from maize and 11 from various wild grass species). Although only MSV-A isolates were obtained from maize, both MSV-A and MSV-F isolates were obtained from Digitaria ciliaris. Four non-MSV African streak viruses were also sampled, including sugarcane streak Reunion virus and Urochloa streak virus (USV) from Eleusine coacana, USV from Urochloa sp., maize streak Reunion virus (MSRV) from both Setaria barbata and Rottboellia sp., and a novel highly divergent mastrevirus from Axonopus compressus, which we have tentatively named Axonopus compressus streak virus (ACSV). Besides the discovery of this new mastrevirus species and expanding the known geographical and host ranges of MSRV, we have added D. ciliaris to the list of uncultivated species within which Nigerian MSV-A isolates are possibly able to overwinter. PMID:24796552

Oluwafemi, Sunday; Kraberger, Simona; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind

2014-10-01

4

Biological and Genomic Sequence Characterization of Maize streak virus Isolates from Wheat.  

PubMed

ABSTRACT Maize streak virus (MSV) is best known as the causal agent of maize streak disease. However, only a genetically uniform subset of the viruses within this diverse species is actually capable of producing severe symptoms in maize. Whereas these "maize-type" viruses all share greater than 95% sequence identity, MSV strains isolated from grasses may share as little as 79% sequence identity with the maize-type viruses. Here, we present the complete genome sequences and biological characterization of two MSV isolates from wheat that share approximately 89% sequence identity with the maize-type viruses. Clonal populations of these two isolates, named MSV-Tas and MSV-VW, were leafhopper-transmitted to Digitaria sanguinalis and a range of maize, wheat, and barley genotypes. Whereas the two viruses showed some differences in their pathogenicity in maize, they were both equally pathogenic in D. sanguinalis and the various wheat and barley genotypes tested. Phylogenetic analyses involving the genome sequences of MSV-Tas and MSV-VW, a new maize-type virus also fully sequenced in this study (MSV-VM), and all other available African streak virus sequences, indicated that MSV-Tas and MSV-VW are close relatives that together represent a distinct MSV strain. Sequence analyses revealed that MSV-VM has a recombinant genome containing MSV-Tas/VW-like sequences within its movement protein gene. PMID:18944143

Willment, J A; Martin, D P; Van der Walt, E; Rybicki, E P

2002-01-01

5

Vectors based on maize streak virus can replicate to high copy numbers in maize plants.  

PubMed

The genome of maize streak virus (MSV) consists of one molecule of circular, single-stranded DNA of 2.7 kb. A reporter gene (bar) coding for phosphinothricin acetyl-transferase was inserted into the small non-coding region of the MSV genome. The recombinant bar-containing MSV vectors were introduced into maize seedlings via agroinfection. The chimeric viral DNA was found to replicate to high copy numbers in maize leaves resistant to the application of the herbicide Basta. This establishes the usefulness of MSV as an efficient replicating vector in cells of maize plants. PMID:9049343

Shen, W H; Hohn, B

1995-04-01

6

Replicative intermediates of maize streak virus found during leaf development.  

PubMed

Geminiviruses of the genera Begomovirus and Curtovirus utilize three replication modes: complementary-strand replication (CSR), rolling-circle replication (RCR) and recombination-dependent replication (RDR). Using two-dimensional gel electrophoresis, we now show for the first time that maize streak virus (MSV), the type member of the most divergent geminivirus genus, Mastrevirus, does the same. Although mastreviruses have fewer regulatory genes than other geminiviruses and uniquely express their replication-associated protein (Rep) from a spliced transcript, the replicative intermediates of CSR, RCR and RDR could be detected unequivocally within infected maize tissues. All replicative intermediates accumulated early and, to varying degrees, were already present in the shoot apex and leaves at different maturation stages. Relative to other replicative intermediates, those associated with RCR increased in prevalence during leaf maturation. Interestingly, in addition to RCR-associated DNA forms seen in other geminiviruses, MSV also apparently uses dimeric open circular DNA as a template for RCR. PMID:20032206

Erdmann, Julia B; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind; Rybicki, Edward P; Jeske, Holger

2010-04-01

7

Serotyping and strain identification of maize streak virus isolates.  

PubMed

Four strains of maize streak virus, namely the Panicum maximum, Digitaria setigera and sugarcane strains, have been identified from 19 isolates by ELISA using polyclonal antisera cross-absorbed with particles of the maize strain. The results suggest there is an epitope of the maize strain which is not dependent on the capsid being intact and which is common to all the members of the group; other strain-specific epitopes are probably conformation-dependent. A specific epitope (probably internal) occurs on the coat protein of a maize strain isolate, D(R)D, grown in D. velutina, that is also present on the coat protein of the D. setigera (previously reported as D. sanguinalis) strain. Specific internal epitopes also occur in the coat proteins of sugarcane and P. maximum strains. The use of indirect ELISA was necessary for accurate serotyping. The serological reactivities of particles of all the members of each type were identical irrespective of the host from which they were extracted. Sap extracts proved to be more reliable sources of antigen than virus preparations, which could vary in their serological reactivity. Nevertheless, serological differentiation index values determined in tests using either type of antigen proved reliable and consistent. PMID:1697327

Pinner, M S; Markham, P G

1990-08-01

8

A gene for resistance to the maize streak virus in the African CIMMYT maize inbred line CML202  

Microsoft Academic Search

Resistance to maize streak virus (MSV) is an essential trait of improved maize varieties in sub-Saharan Africa. We mapped quantitative trait loci (QTL) for resistance to MSV in a population of 196 F2:3 lines derived from a cross between the maize inbred lines CML202 (resistant) from CIMMYT-Zimbabwe and Lo951 (susceptible) from Italy. Field tests were planted at two locations in

H. G. Welz; A. Schechert; A. Pernet; K. V. Pixley; H. H. Geiger

1998-01-01

9

Inhibition of maize streak virus (MSV) replication by transient and transgenic expression of MSV replication-associated protein mutants.  

PubMed

Maize streak disease is a severe agricultural problem in Africa and the development of maize genotypes resistant to the causal agent, Maize streak virus (MSV), is a priority. A transgenic approach to engineering MSV-resistant maize was developed and tested in this study. A pathogen-derived resistance strategy was adopted by using targeted deletions and nucleotide-substitution mutants of the multifunctional MSV replication-associated protein gene (rep). Various rep gene constructs were tested for their efficacy in limiting replication of wild-type MSV by co-bombardment of maize suspension cells together with an infectious genomic clone of MSV and assaying replicative forms of DNA by quantitative PCR. Digitaria sanguinalis, an MSV-sensitive grass species used as a model monocot, was then transformed with constructs that had inhibited virus replication in the transient-expression system. Challenge experiments using leafhopper-transmitted MSV indicated significant MSV resistance--from highly resistant to immune--in regenerated transgenic D. sanguinalis lines. Whereas regenerated lines containing a mutated full-length rep gene displayed developmental and growth defects, those containing a truncated rep gene both were fertile and displayed no growth defects, making the truncated gene a suitable candidate for the development of transgenic MSV-resistant maize. PMID:17170465

Shepherd, Dionne N; Mangwende, Tichaona; Martin, Darren P; Bezuidenhout, Marion; Thomson, Jennifer A; Rybicki, Edward P

2007-01-01

10

Recombination, decreased host specificity and increased mobility may have driven the emergence of maize streak virus as an agricultural pathogen  

PubMed Central

Maize streak virus (MSV; family Geminiviridae, genus Mastrevirus), the causal agent of maize streak disease, ranks amongst the most serious biological threats to food security in subSaharan Africa. Although five distinct MSV strains have been currently described, only one of these – MSV-A – causes severe disease in maize. Due primarily to their not being an obvious threat to agriculture, very little is known about the ‘grass-adapted’ MSV strains, MSV-B, -C, -D and -E. Since comparing the genetic diversities, geographical distributions and natural host ranges of MSV-A with the other MSV strains could provide valuable information on the epidemiology, evolution and emergence of MSV-A, we carried out a phylogeographical analysis of MSVs found in uncultivated indigenous African grasses. Amongst the 83 new MSV genomes presented here, we report the discovery of six new MSV strains (MSV-F to -K). The non-random recombination breakpoint distributions detectable with these and other available mastrevirus sequences partially mirror those seen in begomoviruses, implying that the forces shaping these breakpoint patterns have been largely conserved since the earliest geminivirus ancestors. We present evidence that the ancestor of all MSV-A variants was the recombinant progeny of ancestral MSV-B and MSV-G/-F variants. While it remains unknown whether recombination influenced the emergence of MSV-A in maize, our discovery that MSV-A variants may both move between and become established in different regions of Africa with greater ease, and infect more grass species than other MSV strains, goes some way towards explaining why MSV-A is such a successful maize pathogen. PMID:18753214

Varsani, Arvind; Shepherd, Dionne N.; Monjane, Aderito L.; Owor, Betty E.; Erdmann, Julia B.; Rybicki, Edward P.; Peterschmitt, Michel; Briddon, Rob W.; Markham, Peter G.; Oluwafemi, Sunday; Windram, Oliver P.; Lefeuvre, Pierre; Lett, Jean-Michel; Martin, Darren P.

2008-01-01

11

Reconstructing the History of Maize Streak Virus Strain A Dispersal To Reveal Diversification Hot Spots and Its Origin in Southern Africa ? †  

PubMed Central

Maize streak virus strain A (MSV-A), the causal agent of maize streak disease, is today one of the most serious biotic threats to African food security. Determining where MSV-A originated and how it spread transcontinentally could yield valuable insights into its historical emergence as a crop pathogen. Similarly, determining where the major extant MSV-A lineages arose could identify geographical hot spots of MSV evolution. Here, we use model-based phylogeographic analyses of 353 fully sequenced MSV-A isolates to reconstruct a plausible history of MSV-A movements over the past 150 years. We show that since the probable emergence of MSV-A in southern Africa around 1863, the virus spread transcontinentally at an average rate of 32.5 km/year (95% highest probability density interval, 15.6 to 51.6 km/year). Using distinctive patterns of nucleotide variation caused by 20 unique intra-MSV-A recombination events, we tentatively classified the MSV-A isolates into 24 easily discernible lineages. Despite many of these lineages displaying distinct geographical distributions, it is apparent that almost all have emerged within the past 4 decades from either southern or east-central Africa. Collectively, our results suggest that regular analysis of MSV-A genomes within these diversification hot spots could be used to monitor the emergence of future MSV-A lineages that could affect maize cultivation in Africa. PMID:21715477

Monjane, Adérito L.; Harkins, Gordon W.; Martin, Darren P.; Lemey, Philippe; Lefeuvre, Pierre; Shepherd, Dionne N.; Oluwafemi, Sunday; Simuyandi, Michelo; Zinga, Innocent; Komba, Ephrem K.; Lakoutene, Didier P.; Mandakombo, Noella; Mboukoulida, Joseph; Semballa, Silla; Tagne, Appolinaire; Tiendrébéogo, Fidèle; Erdmann, Julia B.; van Antwerpen, Tania; Owor, Betty E.; Flett, Bradley; Ramusi, Moses; Windram, Oliver P.; Syed, Rizwan; Lett, Jean-Michel; Briddon, Rob W.; Markham, Peter G.; Rybicki, Edward P.; Varsani, Arvind

2011-01-01

12

Computer analysis identifies sequence homologies between potential gene products of Maize Streak Virus and those of Cassava Latent Virus and Tomato Golden Mosaic Virus  

Microsoft Academic Search

The amino acid sequences of the putative polypeptides of maize streak virus (MSV) have been systematically compared with those of cassava latent virus (CLV) and tomato golden mosaic virus (TGMV) using the programme DIAGON (8).

P. M. Mullineaux; J. Donson; M. I. Boulton; B. A. M. Morris-Krsinich; P. G. Markham; J. W. Davies

1985-01-01

13

Genetic Insights into Graminella nigrifrons Competence for Maize fine streak virus Infection and Transmission  

PubMed Central

Background Most plant-infecting rhabdoviruses are transmitted by one or a few closely related insect species. Additionally, intraspecific differences in transmission efficacy often exist among races/biotypes within vector species and among strains within a virus species. The black-faced leafhopper, Graminella nigrifrons, is the only known vector of the persistent propagative rhabdovirus Maize fine streak virus (MFSV). Only a small percentage of leafhoppers are capable of transmitting the virus, although the mechanisms underlying vector competence are not well understood. Methodology RNA-Seq was carried out to explore transcript expression changes and sequence variation in G. nigrifrons and MFSV that may be associated with the ability of the vector to acquire and transmit the virus. RT-qPCR assays were used to validate differential transcript accumulation. Results/Significance Feeding on MFSV-infected maize elicited a considerable transcriptional response in G. nigrifrons, with increased expression of cytoskeleton organization and immunity transcripts in infected leafhoppers. Differences between leafhoppers capable of transmitting MFSV, relative to non-transmitting but infected leafhoppers were more limited, which may reflect difficulties discerning between the two groups and/or the likelihood that the transmitter phenotype results from one or a few genetic differences. The ability of infected leafhoppers to transmit MFSV did not appear associated with virus transcript accumulation in the infected leafhoppers or sequence polymorphisms in the viral genome. However, the non-structural MFSV 3 gene was expressed at unexpectedly high levels in infected leafhoppers, suggesting it plays an active role in the infection of the insect host. The results of this study begin to define the functional roles of specific G. nigrifrons and MFSV genes in the viral transmission process. PMID:25420026

Michel, Andrew P.; Stewart, Lucy R.; Redinbaugh, Margaret G.

2014-01-01

14

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. PMID:23268599

2012-01-01

15

Loop-mediated isothermal amplification for rapid detection of the causal agents of cassava brown streak disease.  

PubMed

The causal agents of cassava brown streak disease have recently been identified as Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). Primers have been developed for rapid detection of these viruses by reverse transcription loop-mediated isothermal amplification (RT-LAMP). Performance of the RT-LAMP assays compared favourably with published RT-PCR and real-time RT-PCR methods. Furthermore, amplification by RT-LAMP is completed in 40 min and does not require thermal cycling equipment. Modification of the RT-LAMP reactions to use labelled primers allowed rapid detection of amplification products using lateral flow devices containing antibodies specific to the incorporated labels, avoiding the need for fluorescence detection or gel electrophoresis. PMID:22820076

Tomlinson, J A; Ostoja-Starzewska, S; Adams, I P; Miano, D W; Abidrabo, P; Kinyua, Z; Alicai, T; Dickinson, M J; Peters, D; Boonham, N; Smith, J

2013-08-01

16

Research of Maize Leaf Disease Identifying Models Based Image Recognition  

Microsoft Academic Search

\\u000a The methods of recognition and diagnosis of main maize leaf diseases using machine vision were studied in the paper. Threshold\\u000a method was adopted to do image segmentation, and area-marking method was used calculating the num of disease as well as wiping\\u000a off redundancy dots. And then Freeman link code was used to calculate form feature. Finally diseases were deduced according

Yu-Xia Zhao; Ke-Ru Wang; Zhong-Ying Bai; Shao-Kun Li; Rui-Zhi Xie; Shi-Ju Gao

17

Transcriptional response of virus-infected cassava and identification of putative sources of resistance for cassava brown streak disease.  

PubMed

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. PMID:24846209

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

2014-01-01

18

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. PMID:24846209

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

2014-01-01

19

Wind Streaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

Released 17 September 2003

Bright wind streaks are present in the lee of craters and other obstacles in this image, located in Sinus Sabaeus, near the Martian equator. These streaks indicate that the local winds blow from the northeast (upper right in the image). The brightness of the streaks indicates that either bright material has been deposited in the lee of the craters, or that the surface has eroded preferentially in the lee of craters, exposing an underlying bright material. Because the streaks are bright regardless of the surrounding surface brightness, the first hypothesis most likely. The streaks probably all represent deposits of the same bright material that settled out of the atmosphere in the wind shelter provided by topographic peaks.

Image information: VIS instrument. Latitude -6.3, Longitude 14.1 East (345.9 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.

2003-01-01

20

[Inheritance analysis and molecular marker selection of genes for wheat spindle streak mosaic disease resistance].  

PubMed

Three wheat spindle streak mosaic viruses (WSSMV) resistant cultivars ('Yining Xiaomai', 'Xu87-633', and 'Xifeng') and one susceptible cultivar ('Zhen9523') were used as parents of 3 crosses in this experiment. WSSMV resistance of the parents, F1, and F2 was evaluated under field condition. Based on the segregation ratios of resistant and susceptible plants in F, and F2 populations, it was deduced that the resistance to WSSMV was dominant and the inheritable factors controlling WSSMV resistance were encoded by the nuclear genome. WSSMV resistances in 'Yining Xiaomai' and 'Xifeng' were controlled by two pairs of alleles, which showed complementary effects. However the resistance in 'Xu-87633' was controlled by a single dominant gene. 266 pairs of SSR primers located on 21 wheat chromosomes were used for polymorphic analysis of the two resistant and the susceptible parents 'Yining Xiaomai' and 'Zhen9523', and 108 of them amplified polymorphic DNA products. By Bulk Segregant Analysis of resistant and susceptible pools, one pair of primer located on chromosome arm 2DS, Xgwm261, were found being linked to WSSMV resistance. The 224 F2 individuals were then amplified with marker Xgwm261. The statistic genetic distance between Xgwm261 and the resistance locus was calculated to be 22.9 cM using the software Mapmaker 3.0. PMID:16078742

Zhang, Qing-Ping; Wang, Xiu-E; Wang, Yao-Nan; Zhao, Yan; Wang, Hai-Yan; Wang, Su-Ling; Chen, Pei-Du

2005-07-01

21

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

Microsoft Academic Search

Transgenic plants have been employed successfully as a low-cost system for the production of therapeutically valuable proteins,\\u000a including antibodies, antigens and hormones. Here, we report the expression of the fusion (F) gene of the Newcastle disease\\u000a virus (NDV) in transgenic maize plants. The expression of the transgene, driven by the maize ubiquitin promoter, caused accumulation\\u000a of the F protein in

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

2006-01-01

22

Maize Prolamins Could Induce a Gluten-Like Cellular Immune Response in Some Celiac Disease Patients  

PubMed Central

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-Sanchez, Juan P.; Cabrera-Chavez, Francisco; Calderon de la Barca, Ana M.

2013-01-01

23

Primitive Streak (dorsal view)  

NSDL National Science Digital Library

This FlashTM animation is the first of a seven part series that presents the primitive streak from different angles. This installment displays the dorsal view, which provides an overview of elongation and regression. Epiblast is seen migrating medially, towards and into the streak. The appearance of the neural tube and somites demonstrates that morphogenesis commences before the streak recedes away.

PhD Jack D Thatcher (West Virginia School of Osteopathic Medicine Structural Biology)

2011-06-23

24

Maize Chlorotic Mottle Machlomovirus and Wheat Streak Mosaic Rymovirus Concentrations Increase in the Synergistic Disease Corn Lethal Necrosis  

E-print Network

in viral concentration also involve a potyvirus. PVX interacts synergistically with tobacco vein mottling potyvirus, tobacco etch poty- virus, and pepper mottle potyvirus (Vance et al., 1995). Cucumber mosaic and involve aphid-trans- mitted potyviruses. CLN provides a useful model for expanding our understanding

Scheets, Kay

25

Effect of Inoculation Pressure on Maize Dwarf Mosaic Virus Strain-A Disease Incidence, Severity and Titer in Sorghum.  

E-print Network

Z TA24S.7 8873 :--------------,1 NO.1706 8-1706 May 1992 TEXAS A&M UNIVERSITY LIBRARY Effect of Inoculation Pressure . on Maize Dwarf Mosaic Virus Strain-A Disease Incidence, Severity and Titer in Sorghum The Texas Agricultural Experiment... Station ? J. Charles Lee, Interim Director The Texas A&M University System ? College Station, Texas ~ ? . k ( :_ ., ., (Blank Page in OrigiBatBuUetiol I .I ,. : ::; , :" Effect of Inoculation Pressure on Maize Dwarf Mosaic Virus Strain-A Disease...

Mahuku, George S.; Toler, R.W.

1992-01-01

26

Identification of promoter motifs regulating ZmeIF4E expression level involved in maize rough dwarf disease resistance in maize (Zea Mays L.).  

PubMed

Maize rough dwarf disease (MRDD, a viral disease) results in significant grain yield losses, while genetic basis of which is largely unknown. Based on comparative genomics, eukaryotic translation initiation factor 4E (eIF4E) was considered as a candidate gene for MRDD resistance, validation of which will help to understand the possible genetic mechanism of this disease. ZmeIF4E (orthologs of eIF4E gene in maize) encodes a protein of 218 amino acids, harboring five exons and no variation in the cDNA sequence is identified between the resistant inbred line, X178 and susceptible one, Ye478. ZmeIF4E expression was different in the two lines plants treated with three plant hormones, ethylene, salicylic acid, and jasmonates at V3 developmental stage, suggesting that ZmeIF4E is more likely to be involved in the regulation of defense gene expression and induction of local and systemic resistance. Moreover, four cis-acting elements related to plant defense responses, including DOFCOREZM, EECCRCAH1, GT1GAMSCAM4, and GT1CONSENSUS were detected in ZmeIF4E promoter for harboring sequence variation in the two lines. Association analysis with 163 inbred lines revealed that one SNP in EECCRCAH1 is significantly associated with CSI of MRDD in two environments, which explained 3.33 and 9.04 % of phenotypic variation, respectively. Meanwhile, one SNP in GT-1 motif was found to affect MRDD resistance only in one of the two environments, which explained 5.17 % of phenotypic variation. Collectively, regulatory motifs respectively harboring the two significant SNPs in ZmeIF4E promoter could be involved in the defense process of maize after viral infection. These results contribute to understand maize defense mechanisms against maize rough dwarf virus. PMID:23474695

Shi, Liyu; Weng, Jianfeng; Liu, Changlin; Song, Xinyuan; Miao, Hongqin; Hao, Zhuanfang; Xie, Chuanxiao; Li, Mingshun; Zhang, Degui; Bai, Li; Pan, Guangtang; Li, Xinhai; Zhang, Shihuang

2013-04-01

27

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

28

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

29

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

30

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

31

Complex Wind Streaks  

NASA Technical Reports Server (NTRS)

16 February 2004 Northeastern Tharsis is known for its complicated patterns of wind streaks. Wind streaks are formed by sediment transport and deposition by wind. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a pattern of crisscrossing streaks indicating winds that generally blow from the southwest (lower left) toward northeast (upper right), but vary over time. The image is located near 27.6oN, 98.9oW. Sunlight illuminates the scene from the lower left; the image covers an area 3 km (1.9 mi) wide.

2004-01-01

32

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

33

Wheat Streak Mosaic Virus  

E-print Network

Virus First discovered in Nebraska in 1922, wheat streak mosaic virus (WSMV) remains a threat today across most of the U.S. Central Plains. WSMV affects spring wheat, barley, corn, triticale, rye and numerous other annual and perennial grasses... Virus First discovered in Nebraska in 1922, wheat streak mosaic virus (WSMV) remains a threat today across most of the U.S. Central Plains. WSMV affects spring wheat, barley, corn, triticale, rye and numerous other annual and perennial grasses...

Morgan, Gaylon

2005-01-26

34

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. PMID:23535334

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

2013-01-01

35

Devil-Streaked Plain  

NASA Technical Reports Server (NTRS)

19 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark streaks on a plain south of the giant impact basin, Hellas Planitia. The streaks map the routes traveled by dozens of individual southern spring and early summer dust devils.

Location near: 68.4oS, 296.1oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2006-01-01

36

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

37

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.  

PubMed

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases. PMID:11716210

Pal, K K; Tilak, K V; Saxena, A K; Dey, R; Singh, C S

2001-01-01

38

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

39

Universal Streak Camera  

NASA Astrophysics Data System (ADS)

A universal streak camera which works in synchroscan and single-shot modes with 3 plug-ins (synchroscan, fast and slow) has been developed utilizing a microchannel plate-incorporated streak tube. The synchroscan plug-in features low jitter of less than 4 ps, and high-speed sine-wave deflection from 80 to 160 MHz, achieving a limiting temporal resolution of 5 ps. The fast plug-in offers temporal resolution of better than 2 ps with triggering jitter of less than t20 ps. The slow plug-in provides longer time windows from 10 ns to 1 ms/15 mm in 16 ranges. Shutter operation down to 100 ns in duration is available with a maximum repetition rate of 1 - 10 KHz for the 3 plug-ins. An on-off ratio of more than 1:106 has been achieved by using double gate operation at photocathode and built-in microchannel plate.

Tsuchiya, Y.; Takeshima, A.; Inuzuka, E.; Suzuki, K.; Koishi, M.; Kinoshita, K.

1985-02-01

40

Dust Devil Streaks  

NASA Technical Reports Server (NTRS)

27 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of dark streaks created by spring and summer dust devil activity in Argyre Planitia.

Location near: 64.9oS, 8.3oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2005-01-01

41

Dust Devil Streaks  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

At first glance, the dust devil streaks observed in this THEMIS image of the martian northern plains may look similar to many other images. However, what makes this THEMIS image so interesting are the many streaks that trend over hills, mounds, and valleys. Many of the dust devil streaks previously observed occur in very flat and dusty regions. This unique image gives hints to the dynamic nature of the dust devil streak formational process.

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.

Image information: VIS instrument. Latitude 53.8, Longitude 200.9 East (159.1 West). 19 meter/pixel resolution.

2003-01-01

42

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

43

Bright Devil Streaks  

NASA Technical Reports Server (NTRS)

4 March 2005 In honor of Giovanni V. Schiaparelli's 170th birthday, we present this Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image showing light-toned dust devil streaks on the southern floor of Schiaparelli Crater.

Location near: 5.3oS, 343.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Autumn

2005-01-01

44

Genetically Modified, Insect Resistant Maize: Implications for Management of Ear and Stalk Diseases  

NSDL National Science Digital Library

This article summarizes six years of research that indicate that Bt transformation of maize hybrids enhances the safety of grain for livestock and human food products by reducing the plants' vulnerability to mycotoxin-producing Fusarium fungi.

G. P. Munkvold (Iowa State University;); R. L. Hellmich (USDA, ARS Corn Insects and Crop Genetics Research Unit, Iowa State University;)

2000-09-12

45

Unraveling genomic complexity at a quantitative disease resistance locus in maize.  

PubMed

Multiple disease resistance has important implications for plant fitness, given the selection pressure that many pathogens exert directly on natural plant populations and indirectly via crop improvement programs. Evidence of a locus conditioning resistance to multiple pathogens was found in bin 1.06 of the maize genome with the allele from inbred line "Tx303" conditioning quantitative resistance to northern leaf blight (NLB) and qualitative resistance to Stewart's wilt. To dissect the genetic basis of resistance in this region and to refine candidate gene hypotheses, we mapped resistance to the two diseases. Both resistance phenotypes were localized to overlapping regions, with the Stewart's wilt interval refined to a 95.9-kb segment containing three genes and the NLB interval to a 3.60-Mb segment containing 117 genes. Regions of the introgression showed little to no recombination, suggesting structural differences between the inbred lines Tx303 and "B73," the parents of the fine-mapping population. We examined copy number variation across the region using next-generation sequencing data, and found large variation in read depth in Tx303 across the region relative to the reference genome of B73. In the fine-mapping region, association mapping for NLB implicated candidate genes, including a putative zinc finger and pan1. We tested mutant alleles and found that pan1 is a susceptibility gene for NLB and Stewart's wilt. Our data strongly suggest that structural variation plays an important role in resistance conditioned by this region, and pan1, a gene conditioning susceptibility for NLB, may underlie the QTL. PMID:25009146

Jamann, Tiffany M; Poland, Jesse A; Kolkman, Judith M; Smith, Laurie G; Nelson, Rebecca J

2014-09-01

46

Cerberus Wind Streaks  

NASA Technical Reports Server (NTRS)

(Released 6 May 2002) The Science Cerberus is a dark region on Mars that has shrunk down from a continuous length of about 1000 km to roughly three discontinuous spots a few 100 kms in length in less than 20 years. There are two competing processes at work in the Cerberus region that produce the bright and dark features seen in this THEMIS image. Bright dust settles out of the atmosphere, especially after global dust storms, depositing a layer just thick enough to brighten the dark surfaces. Deposition occurs preferentially in the low wind 'shadow zones' within craters and downwind of crater rims, producing the bright streaks. The direction of the streaks clearly indicates that the dominant winds come from the northeast. Dust deposition would completely blot out the dark areas if it were not for the action of wind-blown sand grains scouring the surface and lifting the dust back into the atmosphere. Again, the shadow zones are protected from the blowing sand, preserving the bright layer of dust. Also visible in this image are lava flow features extending from the flanks of the huge Elysium volcanoes to the northwest. Two shallow channels and a raised flow lobe are just barely discernable. The lava channel in the middle of the image crosses the boundary of the bright and dark surfaces without any obvious change in its morphology. This demonstrates that the bright dust layer is very thin in this location, perhaps as little as a few millimeters. The Story Mars is an ever-changing land of spectacular contrasts. This THEMIS image shows the Cerberus region of Mars, a dark area located near the Elysium volcanoes and fittingly named after the three-headed, dragon-tailed dog who guards the door of the underworld. Two opposing processes are at work here: a thin layer of dust falling from the atmosphere and/or dust storms creating brighter surface areas (e.g. the top left portion of this image) and dust being scoured away by the action of the Martian wind disturbing the sand grains and freeing the lighter dust to fly away once more (the darker portions of this image). There are, however, some darker areas that are somewhat shielded and protected from the wind that have yielded bright, dusty crater floors and wind streaks that trail out behind the craters. These wind streaks tell a story all their own as to the prevailing wind direction coming from the northeast. This, added to the fact that this dark region was once 1000 km in length and has dwindled to just a few isolated dark splotches of 100 kilometers in the past 20 years, help us to see that the Martian environment is still quite dynamic and capable of changing. Finally, this being a volcanic region, a lobe of a lava flow from the immense Elysium volcanoes to the northwest is visible stretching across the bottom one-quarter of the image.

2002-01-01

47

Eragrostis minor streak virus: an Asian streak virus in Africa  

Microsoft Academic Search

The genus Mastrevirus of the single-stranded DNA virus family Geminiviridae consists of four distinct virus lineages that have been sampled in different parts of the Old World. These include the Panicoideae-infecting African streak viruses (ten described species including the geographical outlier, Digitaria streak virus [DSV] from Vanuatu) and Australian striate mosaic viruses (three described species), the dicotyledonous-plant-infecting mastreviruses (seven described

Darren P. Martin; Daphne Linderme; Pierre Lefeuvre; Dionne N. Shepherd; Arvind Varsani

2011-01-01

48

Streak camera time calibration procedures  

NASA Technical Reports Server (NTRS)

Time calibration procedures for streak cameras utilizing a modulated laser beam are described. The time calibration determines a writing rate accuracy of 0.15% with a rotating mirror camera and 0.3% with an image converter camera.

Long, J.; Jackson, I.

1978-01-01

49

On sublayer streaks  

NASA Astrophysics Data System (ADS)

Turbulent sublayer streaks are studied with the aid of a simplified theoretical model. In this the nonlinear activity is assumed to be intermittent and to act locally in space during a very short initial time so as to set up the initial conditions for the subsequent linear and inviscid evolution of the resulting three-dimensional flow disturbance. The mean shear flow is taken as a parallel one and a correction for the long-tern effects of viscosity is applied. A model for the initial nonlinear phase is chosen to represent the local Reynolds stresses that would be produced by a patch of local inflectional instability. The streamwise dimension of the resulting eddy is found to grow linearly with time in accordance with the algebraic instability mechanism (Landahl 1980). The associated Reynolds shear stress is expressible in a simple manner in terms of the liftup of the fluid elements and is suggestive of an algebraic-type Reynolds stress model similar to, but not identical to, that of Prandtl's (1925) mixing-length theory.

Landahl, M. T.

1990-03-01

50

Circular Scan Streak Tube Development  

NASA Technical Reports Server (NTRS)

A streak tube having circular scan was designed, built and tested. Continuous circular scan, easily derived from out of phase sine waves applied to the conventional deflection plates, permits the timing of pulses traveling long baselines. At the tube's output a circular array of 720 elements is scanned to provide 30 to 40 picosecond resolution. Initial difficulties with electron bombarded silicon arrays were circumvented by using microchannel plates within the streak tube to provide the needed electronic amplification and digital sensitivity and coupling the 720 element arrays to the electron beam by means of a phosphor on a fiber optics. Two ceramic body tubes with S-20 photocathodes were tested and delivered.

Nevin, S.

1980-01-01

51

Statistics of optimal particle streak photography  

Microsoft Academic Search

A number of statistical problems pertinent to the optimal use of particle streak photography are examined with the goal of deriving error bars and practical rules of thumb. The seeding density of particles is analyzed with the goal of maximizing the number of isolated streaks from randomly distributed particles. The number of overlapped streaks, the main source of ‘‘noise’’ in

Donald B. Altman

1991-01-01

52

Streak tube characterization for transient recording  

Microsoft Academic Search

This paper describes the methods used by EG and G Energy Measurements to characterize a streak tube. Both radiometric (QE, uniformity, gain, linearity, extinction ratio, opacity) and resolution (static, spatial, and temporal) tests are covered. The significance of these measurements with respect to streak camera applications is discussed. The results of the measurements on a streak tube designed and built

T. B. Jennings; R. W. Olsen

1987-01-01

53

Gated SIT vidicon streak tube  

SciTech Connect

A recently developed prototype streak tube designed to produce high gain and resolution by incorporating the streak and readout functions in one envelope thereby minimizing photon-to-change transformations and eliminating external coupling losses is presented. The tube is based upon a grid-gated Silicon-Intensified-Target Vidicon (SITV) with integral Focus Projection Scan (FPS) TV readout. Demagnifying electron optics (m=0.63) in the image section map the 40-mm-diameter photocathode image unto a 25-mm-diameter silicon target where gains greater than or equal to10/sup 3/ are achieved with only 10 KV accelerating voltage. This is compared with much lower gains (approx.50) at much higher voltages (approx.30 KV) reported for streak tubes using phosphor screens. Because SIT technology is well established means for electron imaging in vacuum, such fundamental problems as ''backside thinning'' required for electron imaging unto CCDs do not exist. The high spatial resolution (approx.30 lp/mm), variable scan formats, and high speed electrostatic deflection (250 mm/sup 2/ areas are routinely rastered with 256 scan lines in 1.6 ms) available from FPS readout add versatility not available in CCD devices. Theoretical gain and spatial resolution for this design (developed jointly by Los Alamos National Laboratory and General Electric Co.) are compared with similar calculations and measured data obtained for RCA 73435 streaks fiber optically coupled to (1) 25-mm-diameter SIT FPS vidicons and (2) 40-mm-diameter MCPTs (proximity-focused microchannel plate image intensifier tubes) fiber optically coupled to 18-mm-diameter Sb/sub 2/S/sub 3/ FPS vidicons. Sweep sensitivity, shutter ratio, and record lengths for nanosecond duration (20 to 200 ns) streak applications are discussed.

Dunbar, D.L.; Yates, G.J.; Black, J.P.

1985-01-01

54

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

55

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. PMID:24058362

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

2013-01-01

56

Notes on the IMACON 500 streak camera system  

SciTech Connect

The notes provided are intended to supplement the instruction manual for the IMACON 500 streak camera system. The notes cover the streak analyzer, instructions for timing the streak camera, and calibration. (LEW)

Clendenin, J.E.

1985-01-31

57

Serum bone GLA protein in streak gonad syndrome  

Microsoft Academic Search

Summary  Osteoporosis is one of the most common complications of streak gonad syndrome (SGS), however its pathogenesis is still unclear.\\u000a Bone Gla protein (BGP) has been found to be a serum marker of bone turnover in various metabolic disease states. In the present\\u000a study serum BGP and alkaline phosphatase (AP) were measured in 13 osteoporotic patients with SGS and in 56

János Zséli; Péter Bösze; Péter Lakatos; Péter Vargha; Gábor Tarján; Éva Kollin; Csaba Horváth; János László; István Holló

1991-01-01

58

Statistics of optimal particle streak photography  

Microsoft Academic Search

To derive error bars and practical rules of thumb, statistical problems of optimal particle streak photography (PSP) have been examined. Four practical problems are discussed, including the seeding density of particles necessary for maximizing the number of isolated streaks from randomly distributed particles, estimation of the mean of an arbitrary velocity field with randomly placed noise-free measurements, determination of the

Donald B. Altman

1991-01-01

59

Laminar streaks with spanwise wall forcing  

NASA Astrophysics Data System (ADS)

The influence of steady sinusoidal oscillations of spanwise wall velocity on the Klebanoff modes, i.e. unsteady streaky fluctuations induced by free-stream turbulence in the pre-transitional Blasius boundary layer, is investigated numerically. The wall motion induces a spanwise boundary layer which grows downstream as x1/6 and has an asymptotic analytical solution at large downstream distances. While the forcing has no effect on the initial growth of the streaks, their intensity eventually increases or decreases substantially depending on the relative magnitude between the forcing wavelength and the characteristic length scales of the streaks. The wall actuation enhances the streak intensity if the streak spanwise length scale is much larger than the Blasius boundary layer thickness. The streak energy is instead attenuated when the spanwise viscous diffusion effects play a key role. Wall pressure fluctuations may also be significantly damped in this case. The Klebanoff modes generated by full-spectrum free-stream turbulence are predicted to be attenuated by the wall motion. The asymptotic scaling analysis reveals that there exists an optimal forcing wavelength for full-spectrum streak attenuation as long as the spanwise length scales of the dominant streaks are as large as or smaller than the Blasius boundary layer thickness, a common scenario encountered in experiments. The optimal forcing wavelength is found to be comparable with the streak streamwise length scale. As the amplitude of the wall forcing increases, the reduction of streak intensity grows monotonically. The streaks are completely suppressed in the limit of large amplitude.

Ricco, Pierre

2011-06-01

60

Electro-optic phase grating streak spectrometer  

NASA Astrophysics Data System (ADS)

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. Since 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, Fletcher

2012-10-01

61

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

62

Agrobacterium-mediated delivery of infectious maize streak virus into maize plants  

Microsoft Academic Search

Cells of certain strains of Agrobacterium colonize plants by transferring a portion of their DNA (the T-DNA) into a host plant cell, so causing it to proliferate and produce substances (opines) which the bacteria can use as food1. Most dicotyledonous plants can act as hosts, but most monocotyledonous species (including the economically important gramineae) are thought not to be susceptible2.

Nigel Grimsley; Thomas Hohn; Jeffrey W. Davies; Barbara Hohn

1987-01-01

63

Large Reynolds number streak description using RNS  

NASA Astrophysics Data System (ADS)

It has been recently shown [Choi, Nature, April 06 - Cossu et al., PRL, February 06] that the inclusion of 3D streaky structures in the boundary layer can make it remain laminar longer than the purely 2D Blasius flow. We compute the development of 3D streaks in the boundary layer over a flat plate using the so-called Reduced Navier Stokes equations (RNS). The RNS are a boundary layer like formulation, which is derived from the Navier-Stokes equations making use of the fact that in the large Re limit two very different spatial scales are present: one long (streamwise direction) and two short (spanwise and wall-normal direction). The resulting RNS are a nonlinear, parabolic, Re independent system that describes the streak structure in the large Re limit. The RNS streak computations are also much more less CPU costly than DNS for high Re, and they don't have the numerical problems that the PSE formulation exhibits (divergence of the results for small ?x, or blow-up of the solution when the amplitude of the deviation from Blasius is not small). In this work we comment the details of the numerical integration of the RNS, and we present some comparisons of the RNS results with the linear computations of streak development together with some fully nonlinear computations of streak evolution.

Martin, Juan; Martel, Carlos

2009-11-01

64

The Domestication of Maize The Maize Genome  

E-print Network

resources being developed. Two maize genomes sequenced recently were B73, an elite inbred line grown). A genetic map from 1937 displays the 10 maize chromosomes. Mutants are used to map and study genes

Napp, Nils

65

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. PMID:24847713

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

2014-01-01

66

Frost streaks in the south polar cap of Mars  

NASA Technical Reports Server (NTRS)

Viking Orbiter images of the annual south polar cap on Mars exhibit elongated bright features that are associated with craters and resemble wind streaks observed elsewhere on Mars. The study focuses on the well-documented frost streaks. The discussion covers the morphology of frost streaks, occurrence, seasonal behavior, thickness of frost in streak deposits, wind patterns inferred from frost streaks and other eolian features in the south polar region, formation of frost streaks, and other locales of preferential frost accumulation. The form and seasonal behavior of the bright elongated albedo markings which extend from the rims of many craters in the south polar cap suggest that they are accumulations of CO2 frost in the lee of craters. The frost streaks appear in the fall, increasing in length but not changing in direction during fall and winter. The frost streaks indicate a prograde circulation pattern of near-surface winds around the pole. Other details are also presented.

Thomas, P.; Veverka, J.; Campos-Marquetti, R.

1979-01-01

67

Host range and some characterization of Tobacco streak virus isolated from lettuce in Iran  

Microsoft Academic Search

Lettuce (Lactuca sativa) is one of the most common vegetable planted in the world, so the identification of its viral disease is important because this kind of pathogen causes the loss of quantitative and qualitative characteristic of lettuce. Tobacco streak virus (TSV) is an ilarvirus with quasi-isometric particles, 27 - 35 nm in diameter. It has a wide host range

F. S. Abtahi; M. Koohi Habibi

2008-01-01

68

The first satellite laser echoes recorded on the streak camera  

NASA Technical Reports Server (NTRS)

The application of the streak camera with the circular sweep for the satellite laser ranging is described. The Modular Streak Camera system employing the circular sweep option was integrated into the conventional Satellite Laser System. The experimental satellite tracking and ranging has been performed. The first satellite laser echo streak camera records are presented.

Hamal, Karel; Prochazka, Ivan; Kirchner, Georg; Koidl, F.

1993-01-01

69

Perception of Randomness: On the Time of Streaks  

ERIC Educational Resources Information Center

People tend to think that streaks in random sequential events are rare and remarkable. When they actually encounter streaks, they tend to consider the underlying process as non-random. The present paper examines the time of pattern occurrences in sequences of Bernoulli trials, and shows that among all patterns of the same length, a streak is the…

Sun, Yanlong; Wang, Hongbin

2010-01-01

70

Streaks Of Colored Water Indicate Surface Airflows  

NASA Technical Reports Server (NTRS)

Response faster and contamination less than in oil-flow technique. Flowing colored water provides accurate and clean way to reveal flows of air on surfaces of models in wind tunnels. Colored water flows from small orifices in model, forming streak lines under influence of air streaming over surface of model.

Wilcox, Floyd J., Jr.

1994-01-01

71

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

72

Forecast of maize dwarf mosaic using growth model forecasting method  

Microsoft Academic Search

Maize dwarf mosaic (MDM) is an important maize viral disease in the world. Disease forecast plays a vital role in controlling it. In this study, three growth models including Logistic growth model, Gompertz model and Weibull model, were used to fit seven groups of MDM data obtained in Chengde, Hebei Province in China. Residual sum of square test showed that

Haiguang Wang; Zhanhong Ma

2010-01-01

73

How accurate is the attosecond streak camera?  

PubMed

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)]. PMID:22181882

Ivanov, Misha; Smirnova, Olga

2011-11-18

74

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

75

Streak breakdown instability in pipe Poiseuille flow  

Microsoft Academic Search

This work is devoted to the study of the stability of Hagen–Poiseuille flow or pipe flow. The analysis is focused on the streak breakdown process by which two-dimensional streamwise-independent finite amplitude perturbations transiently modulate the basic flow leading to a profile that contains saddle points and is linearly unstable with respect to very small streamwise-dependent perturbations. This mechanism is one

A´lvaro Meseguer

2003-01-01

76

Streak breakdown instability in pipe Poiseuille flow  

Microsoft Academic Search

This work is devoted to the study of the stability of Hagen-Poiseuille flow or pipe flow. The analysis is focused on the streak breakdown process by which two-dimensional streamwise-independent finite amplitude perturbations transiently modulate the basic flow leading to a profile that contains saddle points and is linearly unstable with respect to very small streamwise-dependent perturbations. This mechanism is one

Álvaro Meseguer

2003-01-01

77

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. PMID:24524215

2014-01-01

78

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

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

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

81

RESEARCH ARTICLE Bichromatic particle streak velocimetry bPSV  

E-print Network

RESEARCH ARTICLE Bichromatic particle streak velocimetry bPSV Interfacial, volumetric three-component velocimetry using a single camera Bjo¨rn Voss · Julian Stapf · Andre´ Berthe · Christoph S. Garbe Received: 20 three-component (3D3C) interfacial flow measurement. It is based on the particle streak velocimetry

Garbe, Christoph S.

82

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

83

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. PMID:12399395

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

2002-01-01

84

Streak breakdown instability in pipe Poiseuille flow  

NASA Astrophysics Data System (ADS)

This work is devoted to the study of the stability of Hagen-Poiseuille flow or pipe flow. The analysis is focused on the streak breakdown process by which two-dimensional streamwise-independent finite amplitude perturbations transiently modulate the basic flow leading to a profile that contains saddle points and is linearly unstable with respect to very small streamwise-dependent perturbations. This mechanism is one possible route of transition to turbulence in subcritical shear flows. The exploration is carried out for initial disturbances of different finite amplitudes and axial and azimuthal periodicity. This study covers a wide range of Reynolds numbers and the double threshold curve obtained for transition is consistent with experimental observations.

Meseguer, Álvaro

2003-05-01

85

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

86

High performance imaging streak camera for the National Ignition Facility  

NASA Astrophysics Data System (ADS)

An x-ray streak camera platform has been characterized and implemented for use at the National Ignition Facility. The camera has been modified to meet the experiment requirements of the National Ignition Campaign and to perform reliably in conditions that produce high electromagnetic interference. A train of temporal ultra-violet timing markers has been added to the diagnostic in order to calibrate the temporal axis of the instrument and the detector efficiency of the streak camera was improved by using a CsI photocathode. The performance of the streak camera has been characterized and is summarized in this paper. The detector efficiency and cathode measurements are also presented.

Opachich, Y. P.; Kalantar, D. H.; MacPhee, A. G.; Holder, J. P.; Kimbrough, J. R.; Bell, P. M.; Bradley, D. K.; Hatch, B.; Brienza-Larsen, G.; Brown, C.; Brown, C. G.; Browning, D.; Charest, M.; Dewald, E. L.; Griffin, M.; Guidry, B.; Haugh, M. J.; Hicks, D. G.; Homoelle, D.; Lee, J. J.; Mackinnon, A. J.; Mead, A.; Palmer, N.; Perfect, B. H.; Ross, J. S.; Silbernagel, C.; Landen, O.

2012-12-01

87

High performance imaging streak camera for the National Ignition Facility.  

PubMed

An x-ray streak camera platform has been characterized and implemented for use at the National Ignition Facility. The camera has been modified to meet the experiment requirements of the National Ignition Campaign and to perform reliably in conditions that produce high electromagnetic interference. A train of temporal ultra-violet timing markers has been added to the diagnostic in order to calibrate the temporal axis of the instrument and the detector efficiency of the streak camera was improved by using a CsI photocathode. The performance of the streak camera has been characterized and is summarized in this paper. The detector efficiency and cathode measurements are also presented. PMID:23278024

Opachich, Y P; Kalantar, D H; MacPhee, A G; Holder, J P; Kimbrough, J R; Bell, P M; Bradley, D K; Hatch, B; Brienza-Larsen, G; Brown, C; Brown, C G; Browning, D; Charest, M; Dewald, E L; Griffin, M; Guidry, B; Haugh, M J; Hicks, D G; Homoelle, D; Lee, J J; Mackinnon, A J; Mead, A; Palmer, N; Perfect, B H; Ross, J S; Silbernagel, C; Landen, O

2012-12-01

88

Streak tube photocathode development program. Phase 2, Final technical report  

SciTech Connect

This report details the progress made toward developing a streak tube with greater than 1% quantum efficiency at a wavelength of 1300 nm. The achieved performance is the result of approximately three years of effort. The goal of Phase 2 of this contract was to seal a working 1.3 {mu}m streak tube. This effort was focused in two areas. First there was a continuing effort to further develop and demonstrate the cathodes ability to meet the stated requirements. The second effort was aimed at solving the mechanical and process related problems related to sealing this cathode onto a EG&G streak tube.

Not Available

1993-11-20

89

Workshop on standards for photonic streak camera characterization  

SciTech Connect

A summary paper proposing standardization of definitions and parameter measurements related to photonic streak cameras was generated at the 16th International Congress of High Speed Photography and Photonics at Strasborg, France (August 1984). An international committee appointed by the general Workshop on Picosecond Streak Cameras met and discussed the areas appropriate for standardization and proposed specific definitions, measurements and complementary parameter sets to be used in characterizing photonic streak cameras. These proposals were compiled into a summary paper by the committee co-chairmen, Noel Fleurot (CEA-Limeil) and Gary L. Stradling (Los Alamos National Laboratory), with the intent that it be distributed to interested streak camera users and manufacturers and that appropriate improvements and additions be solicited.

Stradling, G.L.

1985-01-01

90

Note: X-ray streak camera sweep speed calibration.  

PubMed

X-ray streak cameras are extensively used to study transient x-ray processes in experiments carried out on various laser facilities at the Research Center of Laser Fusion. Precise calibration and clear description of the sweep speed of the x-ray streak camera are vital for obtaining precise temporal information to understand the fast physics phenomena. An x-ray streak camera named wide-slit x-ray streak camera has been calibrated using a small-scale laser facility with pulse duration of 8 ps. Sweep speeds on most part of the output screen (charge coupled device) are obtained. These calibration results can be used to correct the nonlinearity of sweep speed in measurement of temporal processes. PMID:20515185

Zhu, Tuo; Yang, Jia-Min; Deng, Bo; Yang, Dong; He, Xiao-an; Wang, Zhe-bin

2010-05-01

91

Attosecond streaking of photoelectron emission from disordered solids  

E-print Network

Attosecond streaking of photoelectrons emitted by extreme ultraviolet light has begun to reveal how electrons behave during their transport within simple crystalline solids. Many sample types within nanoplasmonics, thin-film physics, and semiconductor physics, however, do not have a simple single crystal structure. The electron dynamics which underpin the optical response of plasmonic nanostructures and wide-bandgap semiconductors happen on an attosecond timescale. Measuring these dynamics using attosecond streaking will enable such systems to be specially tailored for applications in areas such as ultrafast opto-electronics. We show that streaking can be extended to this very general type of sample by presenting streaking measurements on an amorphous film of the wide-bandgap semiconductor tungsten trioxide, and on polycrystalline gold, a material that forms the basis of many nanoplasmonic devices. Our measurements reveal the near-field temporal structure at the sample surface, and photoelectron wavepacket te...

Okell, W A; Fabris, D; Arrell, C A; Hengster, J; Ibrahimkutty, S; Seiler, A; Barthelmess, M; Stankov, S; Lei, D Y; Sonnefraud, Y; Rahmani, M; Uphues, Th; Maier, S A; Marangos, J P; Tisch, J W G

2014-01-01

92

Tests for Wet Mechanism of Slope Streaks Formation on Mars.  

NASA Astrophysics Data System (ADS)

Slope streaks are forming in some equatorial regions on Mars. They have been mostly interpreted as a result of dry mass wasting of dust. Recently a striking morphological similarity with wet slope streaks in the Antarctic Dry Valleys has been demonstrated. Physical conditions on Mars do not allow the same mechanism. We propose a "wet" mechanism on Mars, which inherits the main feature of the Antarctic slope streaks responsible for their distinctive planforms, namely, shallow subsurface percolation of liquid above the ice table. This mechanism assumes some ice in the shallow subsurface, which had been emplaced under previous wetter climate conditions and currently is undergoing slow desiccation. This icy soil is overlaid by a layer highly enriched in chlorides. On top of this layer, there is a thin layer of dry fine dust. During the warm season, droplets of highly concentrated brines are formed in the salty layer. Sometimes at some places, the droplets coalesce; the liquid percolates downhill, wicks up through the dust layer and dries up. This alters the uppermost dust layer structure, which affects the surface albedo and observable as a dark streak. Further gradual changes of this new surface structure lead to slow brightening of the streak and final fading away. Such a mechanism is at the margin of physical possibility and consistency with observational constraints. Prospective observational tests for "wet" mechanism: (1) Spectral signature of hydrated chlorides in fresh streaks, would make "wet" hypothesis much more probable. (2) Gentle slope of slope streaks, especially of their uppermost parts would strongly favor "wet" mechanism. (3) Observation of slope streak formation during cold seasons, when the day-average surface temperature is below 190 K would reject "wet" mechanism. (4) Observation of a slope streak in the process of formation (a streak that lengthens from earlier to later image) would almost prove "wet" mechanism, at least, almost reject dry avalanche scenario. (5) Absence of a shallow high-thermal-inertia layer would be inconsistent with a "wet" scenario. (6) Geomorphologic observations supporting subsurface ice in the slope streak regions would favor the "wet" mechanism.

Kreslavsky, M.; Head, J.

2007-12-01

93

Shuttle radar images of wind streaks in the Altiplano, Bolivia  

Microsoft Academic Search

Shuttle imaging radar (SIR-A) coverage across Bolivia shows the major physiographic provinces, including the Andean Altiplano. The Altiplano contains a variety of eolian features, many of which are visible as radar-dark, radar-mottled, and radar-bright streaks aligned parallel to the prevailing winds. The streaks form downwind from hills and are as much as 15 km long and 800 m wide. Dark

Ronald Greeley; Philip Christensen; Raul Carrasco

1989-01-01

94

Streak image denoising and segmentation using adaptive Gaussian guided filter.  

PubMed

In streak tube imaging lidar (STIL), streak images are obtained using a CCD camera. However, noise in the captured streak images can greatly affect the quality of reconstructed 3D contrast and range images. The greatest challenge for streak image denoising is reducing the noise while preserving details. In this paper, we propose an adaptive Gaussian guided filter (AGGF) for noise removal and detail enhancement of streak images. The proposed algorithm is based on a guided filter (GF) and part of an adaptive bilateral filter (ABF). In the AGGF, the details are enhanced by optimizing the offset parameter. AGGF-denoised streak images are significantly sharper than those denoised by the GF. Moreover, the AGGF is a fast linear time algorithm achieved by recursively implementing a Gaussian filter kernel. Experimentally, AGGF demonstrates its capacity to preserve edges and thin structures and outperforms the existing bilateral filter and domain transform filter in terms of both visual quality and peak signal-to-noise ratio performance. PMID:25321679

Jiang, Zhuocheng; Guo, Baoping

2014-09-10

95

MaizeGDB.  

PubMed

MaizeGDB is the community database for biological information about the crop plant Zea mays. Genetic, genomic, sequence, gene product, functional characterization, literature reference, and person/organization contact information are among the data types stored at MaizeGDB. At the project's website (http://www.maizegdb.org) are standardized custom interfaces enabling researchers to browse data and to seek out specific information matching explicit search criteria. In addition, pre-compiled reports are made available for particular types of data, and bulletin boards are provided to facilitate communication and coordination among members of the community of maize geneticists. PMID:18287701

Lawrence, Carolyn J

2007-01-01

96

Bioinformatics The Maize Genetics and Genomics Database.  

E-print Network

Bioinformatics The Maize Genetics and Genomics Database. The Community Resource for Access 50011­3260 (T.E.S.) The Maize Genetics and Genomics Database (MaizeGDB) serves the maize (Zea mays data types available through MaizeGDB. MISSION AND SCOPE The Maize Genetics and Genomics Database

Brendel, Volker

97

A Geminivirus, Serologically Related to Maize Streak Virus, from Digitaria sanguinalis from Vanuatu  

Microsoft Academic Search

SUMMARY Electron microscopy of purified particles of a virus found in Dig#aria sanguinalis from Vanuatu (formerly New Hebrides) indicated that it is a geminivirus. Preparations of virus particles contained one coat protein of tool. wt. about 27 500 and circular and linear single-stranded DNA about 2350 nucleotides in length. In thin sections of infected cells, geminate particles were found in

MICHEL DOLLET; GIAN PAOLO ACCOTTO; VITTORIA LISA; JOSIANE MENISSIER; GUIDO BOCCARDO

1986-01-01

98

Transformation of Digitaria sanguinalis: A model system for testing maize streak virus resistance in Poaceae  

Microsoft Academic Search

Digitaria sanguinalis, an African grass, was micropropagated from immature inflorescences and callus was transformed by particle\\u000a gun bombardment. Integration and expression of the bar and uidA genes was shown in the T0 generation. Transformants were shown to be fertile by the production of viable seeds. The time taken from bombardment to\\u000a the setting of seed was approximately four months. D.

Wusi Chen; Sandra J. Lennox; Kenneth E. Palmer; Jennifer A. Thomson

1998-01-01

99

Global Maize Trade and Food Security: Implications from a Social Network Model  

PubMed Central

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 were decreased due to factors such as diversion to non-food uses, climatic factors, or plant diseases. Using data on imports and exports from the United Nations 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, while Japan and the Republic of Korea are the largest maize importers. In particular, the star-shaped cluster of the network that represents US 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 US 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

2013-01-01

100

Molecular population genetics of maize regulatory genes during maize evolution  

E-print Network

Molecular population genetics of maize regulatory genes during maize evolution By Qiong Zhao population genetics of MADS-box genes during the domestication and improvement of maize. Chapter 2 Page 92 population genetic approaches to search for targets of selection in several groups of candidate genes

Doebley, John

101

Unsteady analysis of hot streak migration in a turbine stage  

NASA Technical Reports Server (NTRS)

Two- and three-dimensional Navier-Stokes analyses are used to predict unsteady viscous rotor-stator interacting flow in the presence of a combustor hot streak. Predicted results are presented for a two-dimensional three-stator/four-rotor, a two-dimensional one-stator/one-rotor, and a three-dimensional one-stator/one-rotor simulation of hot streak migration through a turbine stage. Comparison of these results with experimental data demonstrates the capability of the three-dimensional procedure to capture most of the flow physics associated with hot streak migration including the effects of combustor hot streaks on turbine rotor surface temperatures. It is noted that blade count ratio has little effect on predicted time-averaged surface pressure and temperature distributions, but a substantial effect on the unsteady flow characteristics. It is shown that high-temperature hot streak fluid accumulates on the pressure surface of the rotor blades, resulting in a high time-averaged surface temperature 'hot spots'.

Dorney, Daniel J.; Davis, Roger L.; Edwards, David E.; Madavan, Nateri K.

1990-01-01

102

Hitting Is Contagious in Baseball: Evidence from Long Hitting Streaks  

PubMed Central

Data analysis is used to test the hypothesis that “hitting is contagious”. A statistical model is described to study the effect of a hot hitter upon his teammates’ batting during a consecutive game hitting streak. Box score data for entire seasons comprising streaks of length games, including a total observations were compiled. Treatment and control sample groups () were constructed from core lineups of players on the streaking batter’s team. The percentile method bootstrap was used to calculate confidence intervals for statistics representing differences in the mean distributions of two batting statistics between groups. Batters in the treatment group (hot streak active) showed statistically significant improvements in hitting performance, as compared against the control. Mean for the treatment group was found to be to percentage points higher during hot streaks (mean difference increased points), while the batting heat index introduced here was observed to increase by points. For each performance statistic, the null hypothesis was rejected at the significance level. We conclude that the evidence suggests the potential existence of a “statistical contagion effect”. Psychological mechanisms essential to the empirical results are suggested, as several studies from the scientific literature lend credence to contagious phenomena in sports. Causal inference from these results is difficult, but we suggest and discuss several latent variables that may contribute to the observed results, and offer possible directions for future research. PMID:23251507

Bock, Joel R.; Maewal, Akhilesh; Gough, David A.

2012-01-01

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

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

105

Presumed ocular histoplasmosis syndrome and linear streak lesions.  

PubMed Central

Five cases of subretinal neovascular membranes in the macula associated with punched out chorioretinal scars and linear streaks were seen in five Dutch patients. Clinically the fundus lesions are consistent with those of presumed ocular histoplasmosis syndrome (POHS) seen in the United States of America. Cutaneous serological testing for histoplasmin reactivity was negative in the three patients tested. Of special interest is the presence of linear streaks in association with POHS. They have not been previously described in patients from Europe with this syndrome. Images PMID:2757993

Bottoni, F G; Deutman, A F; Aandekerk, A L

1989-01-01

106

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

107

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

108

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

NASA Technical Reports Server (NTRS)

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.

1992-01-01

109

Application of silica nanoparticles in maize to enhance fungal resistance.  

PubMed

In this study, maize treated with nanosilica (20-40 nm) is screened for resistance against phytopathogens such as Fusarium oxysporum and Aspergillus niger and compared with that of bulk silica. The resistivity is measured for disease index and expression of plant responsive compounds such as total phenols, phenylalanine ammonia lyase, peroxidase and polyphenol oxidase. The results indicate that nanosilica-treated plant shows a higher expression of phenolic compounds (2056 and 743 mg/ml) and a lower expression of stress-responsive enzymes against both the fungi. Maize expresses more resistance to Aspergillus spp., than Fusarium spp. These results show significantly higher resistance in maize treated with nanosilica than with bulk, especially at 10 and 15 kg/ha. In addition, hydrophobic potential and silica accumulation percentage of nanosilica treated maize (86.18° and 19.14%) are higher than bulk silica treatment. Hence, silica nanoparticles can be used as an alternative potent antifungal agent against phytopathogens. PMID:25082220

Suriyaprabha, Rangaraj; Karunakaran, Gopalu; Kavitha, Kandiah; Yuvakkumar, Rathinam; Rajendran, Venkatachalam; Kannan, Narayanasamy

2014-09-01

110

Mass movement within a slope streak on Mars Cynthia B. Phillips,1  

E-print Network

Mass movement within a slope streak on Mars Cynthia B. Phillips,1 Devon M. Burr,1 and Ross A. Beyer 2007. [1] Slope streaks on Mars represent a currently active geological process. Various theories streak on Mars, Geophys. Res. Lett., 34, L21202, doi:10.1029/2007GL031577. 1. Introduction [2] Slope

Perfect, Ed

111

Particle streak velocimetry and CH laser-induced fluorescence diagnostics in strained, premixed,  

E-print Network

Particle streak velocimetry and CH laser-induced fluorescence diagnostics in strained, premixed, 91125 Abstract We present the use of simultaneous Particle Streak Velocimetry (PSV) and CH Planar Laser Streak Velocimetry (PSV) [1­3], a tech- nique similar to particle tracking velocimetry [4], is used

Barr, Al

112

Microrobotic Streak Seeding For Protein Crystal Growth CUCS04104  

E-print Network

Microrobotic Streak Seeding For Protein Crystal Growth CUCS­041­04 Atanas Georgiev 1 Peter Allen 1 that consists of picking individual protein crystal from growth solution the purpose X­ray data collection) transferred protein solution that optimized their growth. building high­throughput protein crystal production

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

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

115

A-maize-ing Diversity  

NSDL National Science Digital Library

Maize (Zea mays)âÂÂcornâÂÂis a staple food source in much of the world, as well as a source of cooking oil, grain alcohol, livestock feed, and biofuel. There is enormous quantitative variation among maize strains for traits of agronomic importance. Buckler and colleagues describe the genetic properties of a new resource for mapping maize quantitative traits, and discuss the genetic architecture of a key traitâÂÂflowering timeâÂÂderived from it.

Trudy Mackay (North Carolina State University;Department of Genetics)

2009-08-07

116

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

117

Megahertz streak-mode Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

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.

2011-06-01

118

rf streak camera based ultrafast relativistic electron diffraction.  

PubMed

We theoretically and experimentally investigate the possibility of using a rf streak camera to time resolve in a single shot structural changes at the sub-100 fs time scale via relativistic electron diffraction. We experimentally tested this novel concept at the UCLA Pegasus rf photoinjector. Time-resolved diffraction patterns from thin Al foil are recorded. Averaging over 50 shots is required in order to get statistics sufficient to uncover a variation in time of the diffraction patterns. In the absence of an external pump laser, this is explained as due to the energy chirp on the beam out of the electron gun. With further improvements to the electron source, rf streak camera based ultrafast electron diffraction has the potential to yield truly single shot measurements of ultrafast processes. PMID:19191429

Musumeci, P; Moody, J T; Scoby, C M; Gutierrez, M S; Tran, T

2009-01-01

119

Development of streak camera with anisotropic focusing electron optical system  

NASA Astrophysics Data System (ADS)

In this paper, the anisotropic focusing technique is used to make a novel streak tube. The salient features are the introduction of both temporally focusing electrodes and spatially focusing electric quadrupole lens. The simulation showed that physical temporal dispersion of 0.38 ps and edge spatial resolution of 56 lp/mm can be achieved. The Nd:YLF 8ps pulse laser was used to calibrate the performance index of streak camera. The static and dynamic spatial resolutions are 35 lp/mm and 25 lp/mm respectively. The dynamic range more than 950:1 and time resolution 8ps can be reached. Furthermore, the magnifications in slit and scanning direction can be adjusted respectively, so it is very convenient to select amplification needed when it is coupled with KB microscope.

Tian, J.; Ding, Y.; Cao, X.; Liu, S.; Xu, X.; Hu, X.; Wen, W.; Wang, J.; Wang, C.; Liu, H.; Dong, G.; Zhang, T.; Lu, Y.; Wang, Xi.; Liu, J.

2013-05-01

120

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

121

Attosecond streaking experiments on atoms: quantum theory versus simple model  

E-print Network

A new theoretical approach to the description of the attosecond streaking measurements of atomic photoionization is presented. It is a fully quantum mechanical description based on numerical solving of the time-dependent Schroedinger equation which includes the atomic field as well as the fields of the XUV and IR pulses. Also a simple semiempirical description based on sudden approximation is suggested which agrees very well with the exact solution.

Kazansky, A K

2006-01-01

122

Incidence of Fusarium Species and Mycotoxins in Silage Maize  

PubMed Central

Maize is frequently infected by the Fusarium species producing mycotoxins. Numerous investigations have focused on grain maize, but little is known about the Fusarium species in the entire plant used for silage. Furthermore, mycotoxins persist during the ensiling process and thus endanger feed safety. In the current study, we analyzed 20 Swiss silage maize samples from growers’ fields for the incidence of Fusarium species and mycotoxins. The species spectrum was analyzed morphologically and mycotoxins were measured by LC-MS/MS. A pre-harvest visual disease rating showed few disease symptoms. In contrast, the infection rate of two-thirds of the harvest samples ranged from 25 to 75% and twelve different Fusarium species were isolated. The prevailing species were F. sporotrichioides, F. verticillioides and F. graminearum. No infection specificity for certain plant parts was observed. The trichothecene deoxynivalenol (DON) was found in each sample (ranging from 780 to 2990 µg kg?1). Other toxins detected in descending order were zearalenone, further trichothecenes (nivalenol, HT-2 and T-2 toxin, acetylated DON) and fumonisins. A generalized linear regression model containing the three cropping factors harvest date, pre-precrop and seed treatment was established, to explain DON contamination of silage maize. Based on these findings, we suggest a European-wide survey on silage maize. PMID:22069750

Eckard, Sonja; Wettstein, Felix E.; Forrer, Hans-Rudolf; Vogelgsang, Susanne

2011-01-01

123

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

124

Streaking at high energies with electrons and positrons  

SciTech Connect

State-of-the-art attosecond metrology deals with the detection and characterization of photon pulses with typical energies up to the hundreds of eV and time resolution of several tens of attoseconds. Such short pulses are used for example to control the motion of electrons on the atomic scale or to measure inner-shell atomic dynamics. The next challenge of time-resolving the inner-nuclear dynamics, transient meson states and resonances requires photon pulses below attosecond duration and with energies exceeding the MeV scale. Here we discuss a detection scheme for time-resolving high-energy gamma ray pulses down to the zeptosecond timescale. The scheme is based on the concept of attosecond streak imaging, but instead of conversion of photons into electrons in a nonlinear medium, the high-energy process of electron-positron pair creation is utilized. These pairs are produced in vacuum through the collision of a test pulse to be characterized with an intense laser pulse, and they acquire additional energy and momentum depending on their phase in the streaking pulse at the moment of production. A coincidence measurement of the electron and positron momenta after the interaction provides information on the pair production phase within the streaking pulse. We examine the limitations imposed by quantum radiation reaction in multiphoton Compton scattering on this detection scheme, and discuss other necessary conditions to render the scheme feasible in the upcoming Extreme Light Infrastructure (ELI) laser facility.

Ipp, Andreas; Evers, Joerg; Keitel, Christoph H.; Hatsagortsyan, Karen Z. [Institut fuer Theoretische Physik, Technische Universitaet Wien, 1040 Vienna (Austria); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany)

2012-07-09

125

Slope streaks on Mars: A new “wet” mechanism  

NASA Astrophysics Data System (ADS)

Slope steaks are one of the most intriguing modern phenomena observed on Mars. They have been mostly interpreted as some specific type of granular flow. We propose another mechanism for slope streak formation on Mars. It involves natural seasonal formation of a modest amount of highly concentrated chloride brines within a seasonal thermal skin, and runaway propagation of percolation fronts. Given the current state of knowledge of temperature regimes and the composition and structure of the surface layer in the slope streak regions, this mechanism is consistent with the observational constraints; it requires an assumption that a significant part of the observed chlorine to be in form of calcium and ferric chloride, and a small part of the observed hydrogen to be in form of water ice. This "wet" mechanism has a number of appealing advantages in comparison to the widely accepted "dry" granular flow mechanism. Potential tests for the "wet" mechanism include better modeling of the temperature regime and observations of the seasonality of streak formation.

Kreslavsky, Mikhail A.; Head, James W.

2009-06-01

126

Perception of randomness: On the time of streaks.  

PubMed

People tend to think that streaks in random sequential events are rare and remarkable. When they actually encounter streaks, they tend to consider the underlying process as non-random. The present paper examines the time of pattern occurrences in sequences of Bernoulli trials, and shows that among all patterns of the same length, a streak is the most delayed pattern for its first occurrence. It is argued that when time is of essence, how often a pattern is to occur (mean time, or, frequency) and when a pattern is to first occur (waiting time) are different questions and bear different psychological relevance. The waiting time statistics may provide a quantitative measure to the psychological distance when people are expecting a probabilistic event, and such measure is consistent with both of the representativeness and availability heuristics in people's perception of randomness. We discuss some of the recent empirical findings and suggest that people's judgment and generation of random sequences may be guided by their actual experiences of the waiting time statistics. PMID:20728080

Sun, Yanlong; Wang, Hongbin

2010-12-01

127

Design of microcontroller based system for automation of streak camera  

SciTech Connect

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.

Joshi, M. J.; Upadhyay, J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P. [Laser Electronics Support Division, RRCAT, Indore 452013 (India)

2010-08-15

128

MaizeGDB, the community database for maize genetics and genomics  

E-print Network

MaizeGDB, the community database for maize genetics and genomics Carolyn J. Lawrence1 , Qunfeng Dong1 , Mary L. Polacco3 , Trent E. Seigfried1 and Volker Brendel1,2,* 1 Department of Genetics ABSTRACT The Maize Genetics and Genomics Database (MaizeGDB) is a central repository for maize sequence

Brendel, Volker

129

Evaluation of Argentine maize hybrids and exotic x temperate testcrosses across environments  

E-print Network

diversity among U.S. maize hybrids has narrowed. Problems, such as insect pressure, diseases, and mycotoxins, present obstacles for breeders. One approach is to use exotic germplasm in breeding programs to provide useful, novel alleles for productivity...

Ochs, Brett Allen

2005-11-01

130

Catalase Hybrid Enzymes in Maize  

Microsoft Academic Search

In maize endosperm there are two electrophoretic variants of catalase. The variations are under genetic control, and the heterozygote shows three hybrid enzymes with mobilities intermediate between the parental enzymes. Thus, maize catalase may exist as a tetramer, and the hybrid enzymes may be formed by random association of two different catalase monomers.

Lars Beckman; John G. Scandalios; James L. Brewbaker

1964-01-01

131

Streak camera based SLR receiver for two color atmospheric measurements  

NASA Technical Reports Server (NTRS)

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

1993-01-01

132

Genetic erosion in maize's center of origin.  

PubMed

Crop genetic diversity is an indispensable resource for farmers and professional breeders responding to changing climate, pests, and diseases. Anecdotal appraisals in centers of crop origin have suggested serious threats to this diversity for over half a century. However, a nationwide inventory recently found all maize races previously described for Mexico, including some formerly considered nearly extinct. A flurry of social studies seems to confirm that farmers maintain considerable diversity. Here, we compare estimates of maize diversity from case studies over the past 15 y with nationally and regionally representative matched longitudinal data from farmers across rural Mexico. Our findings reveal an increasing bias in inferences based on case study results and widespread loss of diversity. Cross-sectional, case study data suggest that farm-level richness has increased by 0.04 y(-1) nationwide; however, direct estimates using matched longitudinal data reveal that richness dropped -0.04 y(-1) between 2002 and 2007, from 1.43 to 1.22 varieties per farm. Varietal losses occurred across regions and altitudinal zones, and regardless of farm turnover within the sector. Extinction of local maize populations may not have resulted in an immediate loss of alleles, but low varietal richness and changes in maize's metapopulation dynamics may prevent farmers from accessing germplasm suitable to a rapidly changing climate. Declining yields could then lead farmers to leave the sector and result in a further loss of diversity. Similarities in research approaches across crops suggest that methodological biases could conceal a loss of diversity at other centers of crop origin. PMID:25197088

Dyer, George A; López-Feldman, Alejandro; Yúnez-Naude, Antonio; Taylor, J Edward

2014-09-30

133

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

NASA Technical Reports Server (NTRS)

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.

1992-01-01

134

Root Infection and Systemic Colonization of Maize by Colletotrichum graminicola?  

PubMed Central

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.; Garcia, Veronica M.; Shaw, Brian D.; Thon, Michael R.

2008-01-01

135

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

PubMed

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. PMID:25019767

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

2014-06-01

136

Effects of elevated [CO2 ] on maize defence against mycotoxigenic Fusarium verticillioides.  

PubMed

Maize is by quantity the most important C4 cereal crop; however, future climate changes are expected to increase maize susceptibility to mycotoxigenic fungal pathogens and reduce productivity. While rising atmospheric [CO2 ] is a driving force behind the warmer temperatures and drought, which aggravate fungal disease and mycotoxin accumulation, our understanding of how elevated [CO2 ] will effect maize defences against such pathogens is limited. Here we report that elevated [CO2 ] increases maize susceptibility to Fusarium verticillioides proliferation, while mycotoxin levels are unaltered. Fumonisin production is not proportional to the increase in F.?verticillioides biomass, and the amount of fumonisin produced per unit pathogen is reduced at elevated [CO2 ]. Following F.?verticillioides stalk inoculation, the accumulation of sugars, free fatty acids, lipoxygenase (LOX) transcripts, phytohormones and downstream phytoalexins is dampened in maize grown at elevated [CO2 ]. The attenuation of maize 13-LOXs and jasmonic acid production correlates with reduced terpenoid phytoalexins and increased susceptibility. Furthermore, the attenuated induction of 9-LOXs, which have been suggested to stimulate mycotoxin biosynthesis, is consistent with reduced fumonisin per unit fungal biomass at elevated [CO2 ]. Our findings suggest that elevated [CO2 ] will compromise maize LOX-dependent signalling, which will influence the interactions between maize and mycotoxigenic fungi. PMID:24689748

Vaughan, Martha M; Huffaker, Alisa; Schmelz, Eric A; Dafoe, Nicole J; Christensen, Shawn; Sims, James; Martins, Vitor F; Swerbilow, Jay; Romero, Maritza; Alborn, Hans T; Allen, Leon Hartwell; Teal, Peter E A

2014-12-01

137

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

138

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

139

Ultrashort pulse characterization with a terahertz streak camera.  

PubMed

A phase-locked terahertz transient is exploited as an ultrafast phase gate for femtosecond optical pulses. We directly map out the group delay dispersion of a low-power near-infrared pulse by measuring the electro-optically induced polarization rotation as a function of wavelength. Our experiment covers the spectral window from 1.0 to 1.4 ?m and reaches a temporal precision better than 1 fs. A quantitative analysis of the detector response confirms that this streaking technique requires no reconstruction algorithm and is also well suited for the characterization of pulses spanning more than one optical octave. PMID:22089596

Schubert, O; Riek, C; Junginger, F; Sell, A; Leitenstorfer, A; Huber, R

2011-11-15

140

Agrobacterium-mediated infectivity of cloned digitaria streak virus DNA.  

PubMed

A monomeric clone of double-stranded DNA synthesized in vitro DNA of the geminivirus Digitaria streak (DSV) was subcloned as a tandem dimeric unit into a binary vector of Agrobacterium tumefaciens, creating a plasmid pDS2. Inoculation of digitaria sanguinalis with A. tumefaciens carrying pDS2 resulted in viral infection. The symptoms, virus particles, and DNA forms obtained were indistinguishable from those of a natural DSV infection of D. sanguinalis. Inoculations have also induced infections in Zea mays and Avena sativa. The sequence of the Agrobacterium-mediated infectious clone of DSV has been determined. PMID:3341112

Donson, J; Gunn, H V; Woolston, C J; Pinner, M S; Boulton, M I; Mullineaux, P M; Davies, J W

1988-01-01

141

Microprocessor-controlled, wide-range streak camera  

SciTech Connect

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.

Amy E. Lewis, Craig Hollabaugh

2006-09-01

142

Parametric frequency upconversion, optical fiber transmission, and streak camera recording  

SciTech Connect

The use of optical fiber for the transmission of information over relatively long distances is being recognized as the only viable solution to many data transmission problems, particularly those requiring high information density and faithful temporal content. This necessary reliance upon the optical carrier has meant that the image-tube based optical streak camera is often the instrument of choice for recording single-shot multi-parameter events with high temporal resolution. However, current photocathode technology is incompatible with the trend of the optical fiber industry toward the use of the 1300 to 1600 nm wavelength regime. To retain the advantages of optical streak-camera recording and optical fiber transmission, a way must be found to ''upconvert'' the optical carrier to higher energy. This report describes the use of an intense lazer pump beam coincident with the IR signal into a non-linear crystal (LiIO/sub 3/) to increase the signal's frequency. A beam splitter is used to separate the signal from the pump beam at the detector. The physical theory underlying this process is described. (JDH)

Lowry, M.E.; Rotter, M.D.

1987-01-30

143

A possible role for chemotaxis in primitive streak formation  

NASA Astrophysics Data System (ADS)

One of the fundamental problems in modern biology is to understand the transformation of a fertilized egg to an adult organism. A key stage of this developmental process is gastrulation, in which cell germ layers are defined, and the basic three-dimensional body plan of the organism is established. Presented here is a model used to investigate the collective cell movement which is observed at the onset of gastrulation in the Chick embryo. In the avian embryo, gastrulation is initiated by a cadre of cells moving coherently, bisecting the embryo, thereby forming a structure known as the primitive streak. The mechanisms underlying primitive streak formation are the subject of recent experimental controversy. One hypothesis is that coherent cell motion is driven by chemotactic response to long-range signaling gradients. We will present results from large-scale computer simulations testing this hypothesis. In particular, we perform simulations using the Subcellular Element Model (SEM). Within the model framework, a single cell is represented by a collection of visco-elastically interacting elements. Dynamic interactions of elements are motivated, as coarse-grained representations, of the actively remodeling cell cytoskeleton. We have found that, in addition to chemotaxis, active cell migration is crucial for ``fluidizing" the tissue thereby allowing large-scale coherent cell movement.

Sandersius, Sebastian A.; Weijer, Cornelis J.; Newman, Timothy J.

2010-03-01

144

Interactions between performance pressure, performance streaks, and attentional focus.  

PubMed

How is performance under pressure influenced by the history of events that precede it, and how does the pressure outcome influence the series of events that follow? A baseball batting simulation was used with college players to investigate these questions. In Experiment 1, the difficulty of the simulation was first adaptively adjusted to equate performance level. Batters next completed 20 at-bats used to classify them into one of three performance groups (normal, cold streak, or hot streak) followed by a one at-bat pressure condition. Finally, performance was evaluated over a period of 20 postpressure at-bats. In Experiment 2, a series of secondary tasks were added to assess attentional focus. In both experiments, whether batters succeeded or failed under pressure was significantly related to their performance history immediately before the pressure event, with the normal group having the poorest pressure performance. Performance postpressure was significantly related to both the pressure outcome and prepressure performance. These performance effects were related to changes in the batter's attentional focus as shown by changes in secondary task accuracy. PMID:23966447

Gray, Rob; Allsop, Jonathan

2013-08-01

145

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

2006-08-01

146

A Monte Carlo Approach to Joe DiMaggio and Streaks in Baseball  

Microsoft Academic Search

We examine Joe DiMaggio's 56-game hitting streak and look at its likelihood, using a number of simple models. And it turns out that, contrary to many people's expectations, an extreme streak, while unlikely in any given year, is not unlikely to have occurred about once within the history of baseball. Surprisingly, however, such a record should have occurred far earlier

Samuel Arbesman; S. H. Strogatz

2008-01-01

147

Characterization of X-ray streak cameras for use on Nova  

SciTech Connect

There are many different types of measurements that require a continuous time history of x-ray emission that can be provided with an x-ray streak camera. In order to properly analyze the images that are recorded with the x-ray streak cameras operated on Nova, it is important to account for the streak characterization of each camera. We have performed a number of calibrations of the streak cameras both on the bench as well as with Nova disk target shots where we use a time modulated laser intensity profile (self-beating of the laser) on the target to generate an x-ray comb. We have measured the streak camera sweep direction and spatial offset, curvature of the electron optics, sweep rate, and magnification and resolution of the electron optics.

Kalantar, D.H.; Bell, P.M.; Costa, R.L.; Hammel, B.A.; Landen, O.L.; Orzechowski, T.J. [Lawrence Livermore National Lab., CA (United States); Hares, J.D.; Dymoke-Bradshaw, A.K.L. [Kentech Instruments Ltd., Didcot (United Kingdom)

1996-09-01

148

Space charge effects in the axis-photonique PX-1 x-ray streak camera  

NASA Astrophysics Data System (ADS)

The Axis-Photonique PX1 fast X-ray streak camera records the temporal structure of events with picosecond accuracy. Using a potassium iodide photocathode the streak camera has been characterised for the effects of space charge. In a recent grazing incidence pumping X-ray laser experiment the streak camera was coupled to the output of a flat field spectrometer to observe first order diffraction. The second order was observed using a CCD camera. In this paper data is presented from this experiment comparing the brightness of the X-ray laser emission with the dispersion of the streaked image both temporally and spectrally (non temporal direction). Consequently measurements of the dynamic range of the streak camera are made. The results are compared with data from previous experiments.

Edwards, M. H.; Booth, N.; Zhai, Z.; Tallents, G. J.; Dzelzainis, T.; Lewis, C. L. S.; Foster, P.; Streeter, M.; Neely, D.

2007-09-01

149

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. PMID:22454455

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

2012-01-01

150

Kernel Composition Affects Seed Vigor of Maize  

Microsoft Academic Search

In recent years, new seed technologies have been developed that alter the nutrient composition (oil, protein, starch, amino acids, fatty acids, phosphorus) of maize to improve grain quality for livestock feed and other end uses. New specialty maize hybrids used in value added grain production include, but are not limited to, TopCross high oil maize (HOM), nutritionally enhanced Nutridense and

P. R. Thomison

151

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

152

High-speed TV cameras for streak tube readout  

SciTech Connect

Two fast framing TV cameras have been characterized and compared as readout media for imaging of 40 mm diameter streak tube (P-11) phosphor screens. One camera is based upon a Focus-Projection-Scan (FPS) high-speed electrostatic deflected vidicon with 30-mm-diameter PbO target. The other uses an interline transfer charge-coupled device (CCD) with 8.8 {times} 11.4 mm rectangular Si target. The field-of-view (FOV), resolution, responsivity, and dynamic range provided by both cameras when exposed to short duration ({approx} 10 {mu} full width at half maximum (FWHM)) transient illumination followed by a single field readout period of {lt}3 ms are presented. 11 refs., 8 figs., 3 tabs.

Yates, G.J.; Gallegos, R.A.; Holmes, V.H. (Los Alamos National Lab., NM (United States)); Turko, B.T. (Lawrence Berkeley Lab., CA (United States))

1991-01-01

153

Laser streaking of free electrons at 25 keV  

NASA Astrophysics Data System (ADS)

Recording electronic motion in atomic systems requires attosecond and picometre resolutions. Current attosecond technology provides photon pulses up to an energy range of 100 eV, with wavelengths far too long to access structures on the atomic scale. In contrast, ultrashort free-electron pulses with sub-Ångstrom de Broglie wavelengths offer the potential to resolve sub-atomic structures. Here, we demonstrate an optical-field-driven streak camera for their temporal characterization. Our concept is to have an electron beam and a laser beam intersect at an ultrathin metal mirror, and potentially offers attosecond resolution. The technique will be instrumental in advancing ultrafast electron diffraction towards ever higher temporal resolution in the pursuit of the long-term goal of sub-atomic four-dimensional imaging. As a first application, we study the influence of electron-electron interactions on the characteristics of few-electron pulses.

Kirchner, F. O.; Gliserin, A.; Krausz, F.; Baum, P.

2014-01-01

154

Streaking and Wigner time delays in photoemission from atoms and surfaces  

SciTech Connect

Streaked photoemission metrology allows the observation of an apparent relative time delay between the detection of photoelectrons from different initial electronic states. This relative delay is obtained by recording the photoelectron yield as a function of the delay between an ionizing ultrashort extended ultraviolet pulse and a streaking infrared (IR) pulse. Theoretically, photoemission delays can be defined based on (i) the phase shift the photoelectron wave function accumulates during the release and propagation of the photoelectron (''Wigner delay'') and, alternatively, (ii) the streaking trace in the calculated photoemission spectrum (''streaking delay''). We investigate the relation between Wigner and streaking delays in the photoemission from atomic and solid-surface targets. For solid targets and assuming a vanishing IR skin depth, both Wigner and streaking delays can be interpreted as an average propagation time needed by photoelectrons to reach the surface, while the two delays differ for nonvanishing skin depths. For atomic targets, the difference between Wigner and streaking delays depends on the range of the ionic potential.

Zhang, C.-H.; Thumm, U. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2011-09-15

155

Detection Algorithm of Small and Fast orbital objects using Faint Streaks; application to geosynchronous orbit objects  

NASA Astrophysics Data System (ADS)

This paper proposes an algorithm to detect small or apparently fast orbital objects from optical images making use of their faint streaks. In the conventional algorithm, a high signal-to-background-noise-ratio (e.g., 3 or more) is required to detect objects. In our algorithm, we sum signals along the streak direction to improve sensitivity. By applying this algorithm to multi-images, we can detect lower signal-to-noise ratio objects. The algorithm consists of following steps; 1) take local sums of signal intensity on each pixel along preliminarily predicted streak direction, 2) find middle point candidates of streaks on each image, 3) search candidates of a sequence of points aligning in a straight line, and 4) select the candidate with the best linearity and reliability. In this paper, we focus on objects around geosynchronous orbit where most of streaks are oriented to South-North direction. We note that it is not reasonable to apply this algorithm to low Earth orbit objects having no specific streak direction because of limited computational resources. It requires orbit information from other facilities (e.g., space-based sensors). We confirmed that we can detect a streak appeared on images with approximately 1 signal-to-background-noise-ratio with applying the algorithm.

Tagawa, Makoto; Hanada, Toshiya; Oda, Hiroshi; Kurosaki, Hirohisa; Yanagisawa, Toshifumi

156

Emissivity spectrum of a large "dark streak" from themis infrared imagery  

SciTech Connect

'Dark streaks', also known as 'slope streaks', are unusual surface features found on Mars that are known to appear and fade away on timescales of years. Various explanations have been proposed for their origin and composition, including dry avalanches and wet debris or precipitates from brines. Previous investigations have been based on analysis of panchromatic imagery and altimetry from Viking and Mars Global Surveyor missions. We have obtained an infrared emissivity spectrum of a large dark streak on the north western edge of Olympus Mons, using imagery from the THEMIS instrument on the Mars Odyssey 2001 spacecraft.

Brumby, Steven P.; Vaniman, D. T. (David T.); Bish, D. L. (David L.)

2003-01-01

157

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

PubMed

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. PMID:23126928

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

2012-10-01

158

Streak camera crosstalk reduction using a multiple delay optical fiber bundle.  

PubMed

The streak camera is one of the fastest photodetection systems, while its capability of multiplexing is particularly attractive to many applications requiring parallel data acquisition. The degree of multiplexing in a streak camera is limited by the crosstalk between input channels. We developed a technique that introducing a fixed time delay between adjacent fiber channels in a customized two-dimensional to one-dimensional fiber array to significantly reduce crosstalk both at the sample plane and at the input of a streak camera. A prototype system has been developed that supports 100 input channels, and its performance in fluorescence microscopy is demonstrated. PMID:22854483

Tsikouras, Anthony; Ning, Jin; Ng, Sandy; Berman, Richard; Andrews, David W; Fang, Qiyin

2012-01-15

159

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

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

160

Blue Nevus with a Dermoscopic Appearance of Peripheral Streaks with Branches  

PubMed Central

Blue nevi are dermal dendritic melanocytic proliferations presenting as papules, nodules or plaques of blue, blue-gray or blue-brown color. Dermoscopic appearance commonly shows global patterns as homogeneous mono/dichromatic pigmentation and multichromatic pigmentation. Here, we report the case of a blue nevus with the dermoscopic feature of peripheral streaks with branches. With histopathologic deep sections, we confirmed that dermal dendritic melanocytes were distributed in the direction of the streaks. We emphasize that streaks are a rare but important sign of blue nevi. PMID:24707253

Sakamoto, Sachiko; Oiso, Naoki; Narita, Tomohiko; Kawada, Akira

2014-01-01

161

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

162

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

163

Oat-maize chromosome addition lines: a new system for mapping the maize genome.  

PubMed

Novel plants with individual maize chromosomes added to a complete oat genome have been recovered via embryo rescue from oat (Avena sativa L., 2n = 6x = 42) x maize (Zea mays L., 2n = 20) crosses. An oat-maize disomic addition line possessing 21 pairs of oat chromosomes and one maize chromosome 9 pair was used to construct a cosmid library. A multiprobe (mixture of labeled fragments used as a probe) of highly repetitive maize-specific sequences was used to selectively isolate cosmid clones containing maize genomic DNA. Hybridization of individual maize cosmid clones or their subcloned fragments to maize and oat genomic DNA revealed that most high, middle, or low copy number DNA sequences are maize-specific. Such DNA markers allow the identification of maize genomic DNA in an oat genomic background. Chimeric cosmid clones were not found; apparently, significant exchanges of genetic material had not occurred between the maize-addition chromosome and the oat genome in these novel plants or in the cloning process. About 95% of clones selected at random from a maize genomic cosmid library could be detected by the multiprobe. The ability to selectively detect maize sequences in an oat background enables us to consider oat as a host for the cloning of specific maize chromosomes or maize chromosome segments. Introgressing maize chromosome segments into the oat genome via irradiation should allow the construction of a library of overlapping fragments for each maize chromosome to be used for developing a physical map of the maize genome. PMID:9108009

Ananiev, E V; Riera-Lizarazu, O; Rines, H W; Phillips, R L

1997-04-15

164

RESEARCH ARTICLES Maize Centromeres: Organization and Functional Adaptation  

E-print Network

Background of Oat Weiwei Jin,a Juliana R. Melo,b Kiyotaka Nagaki,a Paul B. Talbert,c Steven Henikoff,c R maize (Zea mays) centromeres using oat (Avena sativa)-maize chromosome addition lines. The maize, one from oat and one from maize, the oat CENH3 was consistently incorporated by the maize centromeres

165

ADVANCES IN DEVELOPING INSECT RESISTANT MAIZE VARIETIES FOR KENYA WITHIN THE INSECT RESISTANT MAIZE FOR AFRICA (IRMA) PROJECT  

Microsoft Academic Search

Lepidopteran stem borers are economically important pests of maize, a major staple in Kenya. The Insect Resistant Maize for Africa (IRMA) Project aims at increasing maize production and food security through the development and deployment of insect resistant maize. Bt maize utilizes genes that encode delta-endotoxins; proteins derived from the soil bacterium Bacillus thuringiensis (Bt). Suitable genes have been acquired

S. Mugo; H. DeGroote; J. Songa; M. Mulaa; B. Odhiambo; C. Taracha; D. Bergvinson; D. Hoisington; M. Gethi

166

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. PMID:25010060

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

2014-01-01

167

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

168

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

169

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. PMID:16668098

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

1991-01-01

170

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

171

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

172

Pedestal Craters and Wind Streaks, South Medusae Fossae  

NASA Technical Reports Server (NTRS)

Mars is a desert planet in which wind has a considerable effect on the landscape. Bright and dark wind streaks in this image indicate past movement of fine sediment across the landscape from upper left toward lower right. Two impact craters that look like flowers or starfish are seen in the lower portion of the image. The ejecta deposits of these craters are raised above the surrounding terrain, and indicate that wind has deflated a layer of material (that is, blown it away, thus lowering the surface) that was present at the time that the craters formed. The craters were formed by impacts of meteorites into the earlier, higher surface, and the rocks and gravel thrown out when they formed protected some of this former layer from the wind's effects. This picture--showing part of the Medusae Fossae region near the martian equator--was taken in early April 1999 and covers an area only 1 kilometer (0.62 miles)wide. Illumination is from the lower 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

173

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. PMID:24865494

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

2014-01-01

174

Development of pachytene FISH maps for six maize chromosomes and their integration with other maize maps  

E-print Network

Development of pachytene FISH maps for six maize chromosomes and their integration with other maize in situ hybridization (FISH) maps were devel- oped for chromosomes 1, 3, 4, 5, 6, and 8 of maize using restriction fragment length polymorphism marker-selected Sorghum propinquum bacterial artifi- cial chromosomes

Ronquist, Fredrik

175

Fertility Relationships in Maize-Teosinte Hybrids.  

E-print Network

of teosinte. The teosintes used were the Mexican varieties Durango, Chalco, Nobogame and New, and the Guatemalan varieties Huixta and Florida. Hybrids of the Mexican teosinte varieties with maize exhibit approximaiely normal fertility, although... Guate- malan teosintes and maize are similar in chromosome structure. In addition, the existing evidence indicates that differences on the fourth chromosome are of primary importance in clistinguish- ing the southern Guatemalan teosintes from maize...

Rogers, John S. (John Sinclair)

1950-01-01

176

That's the Second-Biggest Hitting Streak I've Ever Seen! Verifying Simulated Historical Extremes in Baseball  

Microsoft Academic Search

There is considerable interest in two consecutive game streak records in baseball, namely, the celebrated 56-game hitting streak of Joe DiMaggio and the less famous 84-games-reaching-base streak of Ted Williams, and how likely these records would be predicted to occur if the history of Major League Baseball were repeated. I strive to answer this question through simulated replication using a

Andrew C. Thomas

2010-01-01

177

Genome-wide association study of quantitative resistance to southern leaf blight in the maize nested association mapping population.  

PubMed

Nested association mapping (NAM) offers power to resolve complex, quantitative traits to their causal loci. The maize NAM population, consisting of 5,000 recombinant inbred lines (RILs) from 25 families representing the global diversity of maize, was evaluated for resistance to southern leaf blight (SLB) disease. Joint-linkage analysis identified 32 quantitative trait loci (QTLs) with predominantly small, additive effects on SLB resistance. Genome-wide association tests of maize HapMap SNPs were conducted by imputing founder SNP genotypes onto the NAM RILs. SNPs both within and outside of QTL intervals were associated with variation for SLB resistance. Many of these SNPs were within or near sequences homologous to genes previously shown to be involved in plant disease resistance. Limited linkage disequilibrium was observed around some SNPs associated with SLB resistance, indicating that the maize NAM population enables high-resolution mapping of some genome regions. PMID:21217757

Kump, Kristen L; Bradbury, Peter J; Wisser, Randall J; Buckler, Edward S; Belcher, Araby R; Oropeza-Rosas, Marco A; Zwonitzer, John C; Kresovich, Stephen; McMullen, Michael D; Ware, Doreen; Balint-Kurti, Peter J; Holland, James B

2011-02-01

178

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

179

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. PMID:24176102

2013-01-01

180

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

181

Duplicated fie Genes in Maize  

PubMed Central

Two maize genes with predicted translational similarity to the Arabidopsis FIE (Fertilization-Independent Endosperm) protein, a repressor of endosperm development in the absence of fertilization, were cloned and analyzed. Genomic sequences of fie1 and fie2 show significant homology within coding regions but none within introns or 5? upstream. The fie1 gene is expressed exclusively in the endosperm of developing kernels starting at ?6 days after pollination. fie1 is an imprinted gene showing no detectable expression of the paternally derived fie1 allele during kernel development. Conversely, fie2 is expressed in the embryo sac before pollination. After pollination, its expression persists, predominantly in the embryo and at lower levels in the endosperm. The paternal fie2 allele is not expressed early in kernel development, but its transcription is activated at 5 days after pollination. fie2 is likely to be a functional ortholog of the Arabidopsis FIE gene, whereas fie1 has evolved a distinct function. The maize FIE2 and sorghum FIE proteins form a monophyletic group, sharing a closer relationship to each other than to the FIE1 protein, suggesting that maize fie genes originated from two different ancestral genomes. PMID:12566582

Danilevskaya, Olga N.; Hermon, Pedro; Hantke, Sabine; Muszynski, Michael G.; Kollipara, Krishna; Ananiev, Evgueni V.

2003-01-01

182

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

183

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

PubMed Central

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

2014-01-01

184

High-value products from transgenic maize  

Microsoft Academic Search

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

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

2011-01-01

185

A proteinaceous elicitor Sm1 from the beneficial fungus Trichoderma virens is required for induced systemic resistance in maize.  

PubMed

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. PMID:17885089

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

2007-11-01

186

Operational experience with optical streak cameras at the National Ignition Facility  

NASA Astrophysics Data System (ADS)

The National Ignition Facility (NIF) utilizes over 6 optical streak camera systems that collect data from 350 to 1053 nm band during a full system laser shot. The camera systems are configured to collect single or multiple intensity profile signals, spectrally resolved data, spatially resolved interferometry data, and spatially resolved intensity data. The output data format represents the temporal resolution of the recorded event as a two dimensional image. For all these configurations, the time record ranges from 3ns to 100 ns. The precision of the recorded data requires several calibration techniques that provide an overall 2D space-time warp correction that is applied to the raw streak data. The article shall review the typical applications of the optical streak cameras on NIF, the performance of the calibration applied to shot data while in operation and the overall performance and reliability of the camera systems over the several years of operation.

Datte, Philip; Celliers, Peter; Kalantar, Daniel; Moody, John; Bond, Essex; Hibbard, Robin; Krauter, Kerry; Nelson, Jarom; Warrick, Abbie

2013-09-01

187

An aerobiological framework for assessing cross-pollination in maize  

Microsoft Academic Search

Maize (Zea mays L.) is one of the world’s most important crops. Until recent times, improvement in maize resulted from the manipulation and exchange of genetic information within the genus Zea. With the advent of genetic engineering, genetic information from other species is routinely incorporated into the maize genome. Since maize is a wind-pollinated outcrossing species, questions arise concerning the

Donald E. Aylor; Neil P. Schultes; Elson J. Shields

2003-01-01

188

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

SciTech Connect

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. [Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2011-12-15

189

Dielectric response effects in attosecond time-resolved streaked photoelectron spectra of metal surfaces  

E-print Network

The release of conduction-band electrons from a metal surface by a sub-femtosecond extreme ultraviolet (XUV) pulse, and their propagation through the solid, 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, suggesting the observation of the ultrafast solid-state dielectric response in contemporary streaked photoemission experiments.

Zhang, Chang-hua

2011-01-01

190

A Monte Carlo Approach to Joe DiMaggio and Streaks in Baseball  

E-print Network

We examine Joe DiMaggio's 56-game hitting streak and look at its likelihood, using a number of simple models. And it turns out that, contrary to many people's expectations, an extreme streak, while unlikely in any given year, is not unlikely to have occurred about once within the history of baseball. Surprisingly, however, such a record should have occurred far earlier in baseball history: back in the late 1800's or early 1900's. But not in 1941, when it actually happened.

Arbesman, S

2008-01-01

191

Optimizing data recording for the NIF core diagnostic x-ray streak camera  

NASA Astrophysics Data System (ADS)

Quantitative measurements of the sensitivity, dynamic range, and image resolution of a Nova secondary ion mass-based x-ray streak camera have been made. Comparisons were made using film versus a 4k×4k optical charge-coupled device for data readout. These tests were performed with and without an optical image intensifier tube, and with a direct electron-sensitive microchannel plate. We present results from these tests and recommendations for the National Ignition Facility core x-ray streak camera.

Kalantar, D. H.; Bell, P. M.; Perry, T. S.; Sewall, N.; Kimbrough, J.; Weber, F.; Diamond, C.; Piston, K.

2001-01-01

192

A grazing incidence x-ray streak camera for ultrafast, single-shot measurements  

SciTech Connect

An ultrafast x-ray streak camera has been realized using a grazing incidence reflection photocathode. X-rays are incident on a gold photocathode at a grazing angle of 20 degree and photoemitted electrons are focused by a large aperture magnetic solenoid lens. The streak camera has high quantum efficiency, 600fs temporal resolution, and 6mm imaging length in the spectral direction. Its single shot capability eliminates temporal smearing due to sweep jitter, and allows recording of the ultrafast dynamics of samples that undergo non-reversible changes.

Feng, Jun; Engelhorn, K.; Cho, B.I.; Lee, H.J.; Greaves, M.; Weber, C.P.; Falcone, R.W.; Padmore, H. A.; Heimann, P.A.

2010-02-18

193

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

194

© IDOSI Publications, 2009 Adoption of Improved Maize Seeds and Production Efficiency in Rivers State, Nigeria  

E-print Network

Abstract: Maize is an important staple food in Nigeria. Declining yields of maize as a result of several environmental and biological factors have necessitated technological innovations focusing on maturity time, disease resistance and palatability of the crop. This study therefore assesses the adoption of improved seeds and efficiency levels of farmers in River state, Nigeria. The data were obtained from 150 farmers that were randomly selected using two-stage sampling procedures. The Probit model and production function analysis were the analytical methods. Results show that education, farming experience, mono-cropping, minimum tillage and use of fertilizer significantly influence adoption (p<0.1). Also, use of hybrid seeds significantly reduces inefficiency (p<0.1) along with other factors like age, experience, crop rotation, minimum tillage, fertilization. It was recommended that efforts to increase adoption of improved maize seeds for enhanced farm efficiency should focus on farmers ’ education, farming experience and access to fertilizers.

A. S. Oyekale; E. Idjesa

195

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

196

Associations of planting date, drought stress, and insects with Fusarium ear rot and fumonisin B1 contamination in California maize  

Microsoft Academic Search

Fusarium ear rot, caused by Fusarium verticillioides, is one of the most common diseases of maize, causing yield and quality reductions and contamination of grain by fumonisins and other mycotoxins. Drought stress and various insects have been implicated as factors affecting disease severity. Field studies were conducted to evaluate the interactions and relative influences of drought stress, insect infestation, and

M. W. Parsons; G. P. Munkvold

2010-01-01

197

Microrobotic Streak Seeding For Protein Crystal Growth CUCS-041-04  

E-print Network

Microrobotic Streak Seeding For Protein Crystal Growth CUCS-041-04 Atanas Georgiev1 , Peter K the task known as crystal mounting that consists of picking an individual protein crystal from its growth Abstract We present a microrobotic system for protein crystal micromanipulation tasks. The focus

198

Asymmetric Vshaped streaks recorded on board DEMETER satellite above powerful thunderstorms  

E-print Network

Asymmetric Vshaped streaks recorded on board DEMETER satellite above powerful thunderstorms F. El are associated with intense and numerous 0+ whistlers generated in the VLF range by active thunderstorms network. A relationship between the local inclination of the magnetic field above active thunderstorms

199

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

200

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

201

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

202

Improvements in avalanche-transistor sweep circuitry for electrooptic streak cameras  

Microsoft Academic Search

The performance of the avalanche transistor deflector driver (sweep) circuitry used in the high speed, electrooptic streak camera was improved. In the previous design for the sweep circuit, trigger to output delay time drifted on some cameras. This delay drift is a function of a somewhat randomly unstable breakdown voltage of some avalanche transistors. Both temperature and differences in manufacturing

S. W. Thomas; R. L. Griffith; W. R. McDonald

1984-01-01

203

Picosecond streak camera display of an intermodal coupling matrix at a multimode fiber splice  

NASA Technical Reports Server (NTRS)

A technique is developed that permits direct visualization of the coupling matrix for all guided modes of a moderately multimode fiber optic at a splice or mode coupler. The matrix is formed by an array of spots at the output of a picosecond streak camera. The technique also permits unambiguous determination of the phase velocity and group velocity of the modes.

Louradour, F.; Shaklan, Stuart

1991-01-01

204

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

PubMed

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. PMID:21034058

Kimbrough, J R; Bell, P M; Bradley, D K; Holder, J P; Kalantar, D K; MacPhee, A G; Telford, S

2010-10-01

205

Deblurring Low-light Images with Light Streaks Sunghyun Cho2  

E-print Network

Deblurring Low-light Images with Light Streaks Zhe Hu1 Sunghyun Cho2 Jue Wang2 Ming-Hsuan Yang1 1 University of California, Merced 2 Adobe Research Abstract Images taken in low-light conditions with handheld been made recently on image deblurring, state-of-the-art approaches often fail on low-light images

Yang, Ming-Hsuan

206

Holographic particle-streak velocimetry Lisa Dixon, Fook Chiong Cheong and David G. Grier  

E-print Network

Holographic particle-streak velocimetry Lisa Dixon, Fook Chiong Cheong and David G. Grier. Willert, S. T. Wereley, and J. Kompenhans, Particle Image Velocimetry: A Practical Guide (Springer, Berlin and motions," Appl. Opt. 45(16), 3893�3901 (2006). 1. Introduction Particle image velocimetry (PIV) is widely

Grier, David

207

Projected and slice emittance measurements using multi-quadrupole scan and streak readout at PITZ  

E-print Network

Projected and slice emittance measurements using multi-quadrupole scan and streak readout at PITZ R electron beam. One of the main characteristics of the beam is its normalized emittance. Development of injectors is targeted towards producing beams with low normalized emittance, thus high resolution emittance

208

MaizeGDB: The Maize Model Organism Database for Basic, Translational, and Applied Research  

PubMed Central

In 2001 maize became the number one production crop in the world with the Food and Agriculture Organization of the United Nations reporting over 614 million tonnes produced. Its success is due to the high productivity per acre in tandem with a wide variety of commercial uses. Not only is maize an excellent source of food, feed, and fuel, but also its by-products are used in the production of various commercial products. Maize's unparalleled success in agriculture stems from basic research, the outcomes of which drive breeding and product development. In order for basic, translational, and applied researchers to benefit from others' investigations, newly generated data must be made freely and easily accessible. MaizeGDB is the maize research community's central repository for genetics and genomics information. The overall goals of MaizeGDB are to facilitate access to the outcomes of maize research by integrating new maize data into the database and to support the maize research community by coordinating group activities. PMID:18769488

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

2008-01-01

209

The maize Dof protein PBF activates transcription of ?-zein during maize seed development  

Microsoft Academic Search

Maize PBF (prolamin-box binding factor) belongs to the Dof class of plant specific transcription factors containing one highly\\u000a conserved zinc finger DNA-binding domain, called Dof (DNA binding with one finger) domain. Maize PBF trans-activates the ?-zein\\u000a gene (?Z) promoter in developing maize seeds as shown by transient expression in maize endosperms. Co-transfection of a ?Z:GUS\\u000a construct with 35S:PBF resulted in

Pau Marzábal; Elisabet Gas; Pilar Fontanet; Jesús Vicente-Carbajosa; Margarita Torrent; M. Dolores Ludevid

2008-01-01

210

Formation and evolution of a hairpin vortex induced by subharmonic sinuous low-speed streaks  

NASA Astrophysics Data System (ADS)

In this paper, a process of the formation and evolution of hairpin vortices, which originated from the interaction between the spanwise-aligned low-speed streaks with a subharmonic sinuous (SS) oscillation mode, is studied using a direct numerical simulation method in a small periodic local region of an incompressible plane channel flow. The initial artificial perturbations are used to excite the SS-mode oscillation of two spanwise-aligned low-speed streaks in such a flow. A new mechanism of formation and decay of the hairpin vortices is proposed in which the shear layer induced by the spanwise collision and merging between the low-speed streaks is emphasized. Our results show that the streamwise vortices can be induced by the SS-mode streaks and then developed into an X-like pattern at the initial stage due to the mutual induction effect. The X-like vortices further enhance the spanwise oscillation and lift-up of the two streaks that thus lead to the spanwise collision and merging of the low-speed streaks and produce a low-speed region in high-speed fluid. The strong shear layer between the high- and low-speed fluids gives rise to the spanwise vorticity that connects the X-like streamwise vortices and forms the ?-like vortex. Once the low-speed region entirely enters the high-speed fluid, the shear layer shows the ring shape and results in the transition from a ?-like vortex to ?-like one. After that, the viscous diffusion of the low-speed region in the high-speed fluid leads to the decay of the ?-like vortex; the collision and merging of the low-speed streaks simultaneously reoccur upstream and give birth to a secondary ?-like vortex, which exhibits behavior that is nearly similar with that of the primary one. Although the hairpin vortex packet is not observed in the present plane channel flow, the regeneration of the hairpin vortex suggests that this type of vortical structure plays an important role in the wall-bounded flow.

Li, Jian; Dong, Gang; Lu, Ziheng

2014-10-01

211

Correct patterning of the primitive streak requires the anterior visceral endoderm.  

PubMed

Anterior-posterior axis specification in the mouse requires signalling from a specialised extra-embryonic tissue called the anterior visceral endoderm (AVE). AVE precursors are induced at the distal tip of the embryo and move to the prospective anterior. Embryological and genetic analysis has demonstrated that the AVE is required for anterior patterning and for correctly positioning the site of primitive streak formation by inhibiting Nodal activity. We have carried out a genetic ablation of the Hex-expressing cells of the AVE (Hex-AVE) by knocking the Diphtheria toxin subunit A into the Hex locus in an inducible manner. Using this model we have identified that, in addition to its requirement in the anterior of the embryo, the Hex-AVE sub-population has a novel role between 5.5 and 6.5dpc in patterning the primitive streak. Embryos lacking the Hex-AVE display delayed initiation of primitive streak formation and miss-patterning of the anterior primitive streak. We demonstrate that in the absence of the Hex-AVE the restriction of Bmp2 expression to the proximal visceral endoderm is also defective and expression of Wnt3 and Nodal is not correctly restricted to the posterior epiblast. These results, coupled with the observation that reducing Nodal signalling in Hex-AVE ablated embryos increases the frequency of phenotypes observed, suggests that these primitive streak patterning defects are due to defective Nodal signalling. Together, our experiments demonstrate that the AVE is not only required for anterior patterning, but also that specific sub-populations of this tissue are required to pattern the posterior of the embryo. PMID:21445260

Stuckey, Daniel W; Di Gregorio, Aida; Clements, Melanie; Rodriguez, Tristan A

2011-01-01

212

Twelve signals multiplexed with the Lawrence Livermore National Laboratory (LLNL) optical streak camera  

SciTech Connect

At our Nova laser facility, the temporal history of incident and reflected laser energy is recorded on LLNL optical streak cameras. Currently, six cameras are used to record the incident 1.06-{mu}m, incident 0.35{mu}m power of each of the ten Nova beams. Each camera records seven multiplexed signals: typically one signal from each of five beam lines, a fiducial pulse, and time mark generator signal. The optical signals are transported to the camera through optical fibers. The output end of each fiber is placed in the slit plane of the camera. The light exiting the fiber is focused to the streak camera photocathode by the streak camera relay lens. One camera can record a signal from each of the ten Nova beams plus a fiducial and time mark generator signal if the number of multiplexed channels can be increased from seven to twelve. This would allow one camera to record the same data that currently requires two cameras. At a savings of $150 per camera/CCD system, this represents a savings of $450K. Additionally, camera/CCD maintenance and operation complexity would be cut in half and three streak cameras would be freed for use in other experiments. Recent laboratory measurements suggest that the number of multiplexed signals per camera can indeed be increased from seven to twelve without noticeably increasing the crosstalk between signal channels. In this memorandum, we describe recent work in which seven and twelve signals were multiplexed to one streak camera. We describe the effect focusing has on the crosstalk channels and the effect wavelength has on focusing. We conclude the memorandum with suggestions concerning the implementation of a twelve channel system.

Lerche, R.A.; Griffith, R.L.

1990-08-28

213

Influence of rice black streaked dwarf virus on the ecological fitness of non-vector planthopper Nilaparvata lugens (Hemiptera: Delphacidae).  

PubMed

Rice black streak dwarf virus (RBSDV) is transmitted by the small brown planthopper (SBPH), Laodelphax striatellus (Fallen). Non-vector rice brown planthopper (BPH), Nilaparvata lugens (Stål), shares the same host rice plants with SBPH in paddy fields. The changes in nutritional composition of rice plants infected by RBSDV and the ecological fitness of BPH feeding on the infected plants were studied under both artificial climate chamber and field conditions. Contents of 16 detected amino acids and soluble sugar in RBSDV infected rice plants were higher than those in the healthy ones. On the diseased plants BPH had significantly higher nymphal survival rates, nymphal duration of the males, weight of the female adults, as well as egg hatchability compared to BPH being fed on healthy plants. However, there was no obvious difference in female nymph duration, longevity and fecundity. Defense enzymes (superoxidase dismutase, SOD and catalase, CAT) and detoxifying enzymes (carboxylesterase, CAE and glutathione S-transferase, GST) in BPH adults fed on diseased plants had markedly higher activities. The results indicate rice plants infected by RBSDV improved the ecological fitness of the brown planthopper, a serious pest but not a transmitter of the RBSDV virus. PMID:23956237

Xu, Hong-Xing; He, Xiao-Chan; Zheng, Xu-Song; Yang, Ya-Jun; Lu, Zhong-Xian

2014-08-01

214

Effects of Bt maize on Agrotis segetum (Lepidoptera: Noctuidae): a pest of maize seedlings.  

PubMed

The lepidopteran stemborers Busseola fusca (Fuller) (Lepidoptera: Noctuidae), Sesamia calamistis (Hampson) (Lepidoptera: Noctuidae), and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae) are effectively controlled by Bt maize that expresses the Cry1Ab insecticidal protein. Another noctuid species, the cutworm Agrotis segetum (Denis and Schiffermüller) (Lepidoptera: Noctuidae), which is the most common and injurious pest of maize seedlings in South Africa, is exposed to Bt toxin for a part of its life cycle. The effect of this exposure to Bt maize has not been studied yet. The aims of this study were to determine the effects of Bt maize (events MON810 and Bt11) on larval mass, development time, survival, and fecundity of A. segetum. Laboratory studies were conducted with first- and fourth-instar larvae and moths. Results showed that the effect of Cry1Ab toxin on the biology of A. segetum larvae and moths were largely insignificant. The effects of the two Bt maize events on the different parameters measured in this study was not similar between the Bt events and their respective iso-hybrids. Compared with larvae that fed on conventional (non-Bt) maize, Bt maize did not affect survival of first-instar larvae. However, mean mass of larvae that fed on Bt maize (Bt11) was significantly lower. Feeding on Bt maize did not have a significant effect on development and survival of fourth-instar larvae or moth longevity. It did, however, delay the development period to pupa formation. Fewer eggs were laid by moths fed as larvae on maize event Bt11 compared with MON810. This study indicates that Bt maize will most likely not have any significant effect on the control of A. segetum under field conditions. PMID:20388305

Erasmus, A; Van Rensburg, J B J; Van den Berg, J

2010-04-01

215

Effect of volunteers on maize gene flow  

Microsoft Academic Search

Regulatory approvals for deliberate release of GM maize events into the environment have lead to real situations of coexistence\\u000a between GM and non-GM, with some fields being cultivated with GM and conventional varieties in successive seasons. Given the\\u000a common presence of volunteer plants in maize fields in temperate areas, we investigated the real impact of GM volunteers on\\u000a the yield

Montserrat Palaudelmàs; Gisela Peñas; Enric Melé; Joan Serra; Jordi Salvia; Maria Pla; Anna Nadal; Joaquima Messeguer

2009-01-01

216

Supplementation of maize silage or mixed forage (maize and grass silage) based rations with rumen  

E-print Network

Supplementation of maize silage or mixed forage (maize and grass silage) based rations with rumen (% PDIE) supplemented with 12 g of rumen protected methionine (SmartamineT"" M). The aim of this study content were significantly influenced by the supplementation with SmartamineT"^ M. Milk protein content

Paris-Sud XI, Université de

217

Update on the Maize Genome Sequencing Project The Maize Genome Sequencing Project  

E-print Network

at a lower cost than in the past. Second, new high-resolution, high-throughput DNA fingerprinting methods is likely to be too diverged to serve as a resource for efficient map-based cloning of maize traits. However and human genomes (Gregory et al., 2002). Our current picture of the maize genome is largely derived from

Brendel, Volker

218

Mixing of maize and wheat genomic DNA by somatic hybridization in regenerated sterile maize plants  

Microsoft Academic Search

Intergeneric somatic hybridization was performed between albino maize (Zea mays L.) protoplasts and mesophyll protoplasts of wheat (Triticum aestivum L.) by polyethylene glycol (PEG) treatments. None of the parental protoplasts were able to produce green plants without fusion. The maize cells regenerated only rudimentary albino plantlets of limited viability, and the wheat mesophyll protoplasts were unable to divide. PEG-mediated fusion

B. Szarka; I. Göntér; M. Molnár-Láng; S. Mórocz; D. Dudits

2002-01-01

219

Cytological and molecular characterization of oat x maize partial hybrids.  

PubMed

In cereals, interspecific and intergeneric hybridizations (wide crosses) which yield karyotypically stable hybrid plants have been used as starting points to widen the genetic base of a crop and to construct stocks for genetic analysis. Also, uniparental genome elimination in karyotypically unstable hybrids has been utilized for cereal haploid production. We have crossed hexaploid oat (2n=6x=42, Avena sativa L.) and maize (2n=2x=20, Zea mays L.) and recovered 90 progenies through embryo rescue. Fifty-two plants (58%) produced from oatxmaize hybridization were oat haploids (2n=3x=21) following maize chromosome elimination. Twenty-eight plants (31%) were found to be stable partial hybrids with 1-4 maize chromosomes in addition to a haploid set of 21 oat chromosomes (2n=21+1 to 2n=21+4). Ten of the ninety plants produced were found to be apparent chromosomal chimeras, where some tissues in a given plant contained maize chromosomes while other tissues did not, or else different tissues contained a different number of maize chromosomes. DNA restriction fragment length polymorphisms (RFLPs) were used to identify the maize chromosome(s) present in the various oat-maize progenies. Maize chromosomes 2, 3, 4, 5, 6, 7, 8, and 9 were detected in partial hybrids and chromosomal chimeras. Maize chromosomes 1 and 10 were not detected in the plants analyzed to-date. Furthermore, partial self-fertility, which is common in oat haploids, was also observed in some oat-maize hybrids. Upon selfing, partial hybrids with one or two maize chromosomes showed nearly complete transmission of the maize chromosome to give self-fertile maize-chromosome-addition oat plants. Fertile lines were recovered that contained an added maize chromosome or chromosome pair representing six of the ten maize chromosomes. Four independently derived disomic maize chromosome addition lines contained chromosome 4, one line carried chromosome 7, two lines had chromosome 9, one had chromosome 2, and one had chromosome 3. One maize chromosome-8 monosomic addition line was also identified. We also identified a double disomic addition line containing both maize chromosomes 4 and 7. This constitutes the first report of the production of karyotypically stable partial hybrids involving highly unrelated species from two subfamilies of the Gramineae (Pooideae - oat, and Panicoideae - maize) and the subsequent recovery of fertile oat-maize chromosome addition lines. These represent novel material for gene/ marker mapping, maize chromosome manipulation, the study of maize gene expression in oat, and the transfer of maize DNA, genes, or active transposons to oat. PMID:24162209

Riera-Lizarazu, O; Rines, H W; Phillips, R L

1996-07-01

220

MaizeGDB's new data types, resources and activities.  

PubMed

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 http://www.maizegdb.org. PMID:17202174

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

2007-01-01

221

Initial tests of the dual-sweep streak camera system planned for APS particle-beam diagnostics  

SciTech Connect

Initial tests of a dual-sweep streak system planned for use on the Advanced Photon Source (APS) have been performed using assets of the Argonne Wakefield Accelerator (AWA) facility. The short light pulses from the photoelectric injector drive laser in both the visible ({lambda}=496 nm, {Delta}t{approximately}1.5 ps (FWHM)), and the ultraviolet ({lambda}=248 nm, {Delta}t{approximately}5 ps (FWHM)) were used. Both a UV-visible S20 photocathode streak tube and a UV-to-x-ray Au photocathode streak tube were tested. Calibration data with an etalon were also obtained. A sample of dual-sweep streak data using optical synchrotron radiation on the APS injector synchrotron is also presented.

Lumpkin, A.; Yang, B.; Gai, W. [Argonne National Lab., IL (United States); Cieslik, W. [Hamamatsu Photonic Systems, Bridgewater, NJ (United States)

1995-07-01

222

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

223

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

224

Streaked radiography of an irradiated foam sample on the National Ignition Facility  

SciTech Connect

Streaked x-ray radiography images of annular patterns in an evolving tantalum oxide foam under the influence of a driven, subsonic radiation wave were obtained on the National Ignition Facility. This is the first successful radiography measurement of the evolution of well-defined foam features under a driven, subsonic wave in the diffusive regime. A continuous record of the evolution was recorded on an x-ray streak camera, using a slot-apertured point-projection backlighter with an 8 ns nickel source (7.9 keV). Radiography images were obtained for four different annular patterns, which were corrected using a source-dependent flat-field image. The evolution of the foam features was well-modeled using the 3D KULL radiation hydrodynamics code. This experimental and modeling platform can be modified for scaled high-energy-density laboratory astrophysics experiments.

Cooper, A. B. R.; Schneider, M. B.; MacLaren, S. A.; Young, P. E.; Hsing, W. W.; Seugling, R.; Foord, M. E.; Sain, J. D.; May, M. J.; Marrs, R. E.; Maddox, B. R.; Lu, K.; Dodson, K.; Smalyuk, V. [Lawrence Livermore National Laboratory, 7000 East Ave Livermore, California 94550 (United States); Moore, A. S.; Graham, P.; Foster, J. M. [Atomic Weapons Establishment, Aldermaston, Reading RG7 4PR (United Kingdom); Back, C. A.; Hund, J. F. [General Atomics, San Diego, California 92121 (United States)

2013-03-15

225

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

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

226

Attochirp-corrected photo ionization time delays using coincidence attosecond streaking  

E-print Network

Recent measurements have demonstrated the possibility of probing single-photon ionization time delays of electrons originating from different initial states [1,2]. Here, we show for the first time the importance of the temporal structure of the ionizing single attosecond pulse (i.e. attochirp) in the extraction of time delays in attosecond streaking experiments. We have demonstrated this by measuring the time delay between valence electrons from different atomic species by combining attosecond streaking with a coincidence detection scheme. This novel technique allows for the simultaneous measurement of both species under identical conditions. We find that the attochirp introduces an artificial time delay that may exceed the atomic time delay and present a general procedure, which corrects for this contribution. Our analysis, exemplarily applied to argon (Ar) and neon (Ne), reveals an energy-dependent atomic time delay of a few tens of attoseconds in agreement with theoretical predictions.

Sabbar, M; Boge, R; Lucchini, M; Gallmann, L; Cirelli, C; Keller, U

2014-01-01

227

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

228

An approach for megahertz OCT: streak mode Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

We report a technique, which uses an area-scan camera to record the interference spectrum. Traditional point-scanning is remained in this streak-mode FDOCT so that the small aperture of the single-mode fiber functions as a confocal gate and screens multiply scattered photons very well. While the sample beam is scanning the specimen laterally, the interference spectrum is physically scanned on the area scan camera using a streak scanner. Therefore, pixels of the camera are illuminated by the spectrum of OCT signal row by row, corresponding to each A-scan at different lateral position. A unidirectional B-scan of 700 lines is obtained in 1 ms; thus, an A-scan time of 1.4 ?s is achieved. A Day 4 chick embryo sampled is imaged using this method. This technique is highly potential for multi-Megahertz OCT imaging.

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

2011-03-01

229

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

230

Single-Shot Visualization of Evolving Laser Wakefields Using an All-Optical Streak Camera  

NASA Astrophysics Data System (ADS)

We visualize ps-time-scale evolution of an electron density bubble—a wake structure created in atmospheric density plasma by an intense ultrashort laser pulse—from the phase "streak" that the bubble imprints onto a probe pulse that crosses its path obliquely. Phase streaks, recovered in one shot using frequency-domain interferometric techniques, reveal the formation, propagation, and coalescence of the bubble within a 3 mm long ionized helium gas target. 3D particle-in-cell simulations validate the observed density-dependent bubble evolution, and correlate it with the generation of a quasimonoenergetic ˜100 MeV electron beam. The results provide a basis for understanding optimized electron acceleration at a plasma density ne?2×1019 cm-3, inefficient acceleration at lower density, and dephasing limits at higher density.

Li, Zhengyan; Tsai, Hai-En; Zhang, Xi; Pai, Chih-Hao; Chang, Yen-Yu; Zgadzaj, Rafal; Wang, Xiaoming; Khudik, V.; Shvets, G.; Downer, M. C.

2014-08-01

231

Streaked radiography of an irradiated foam sample on the National Ignition Facility  

NASA Astrophysics Data System (ADS)

Streaked x-ray radiography images of annular patterns in an evolving tantalum oxide foam under the influence of a driven, subsonic radiation wave were obtained on the National Ignition Facility. This is the first successful radiography measurement of the evolution of well-defined foam features under a driven, subsonic wave in the diffusive regime. A continuous record of the evolution was recorded on an x-ray streak camera, using a slot-apertured point-projection backlighter with an 8 ns nickel source (7.9 keV). Radiography images were obtained for four different annular patterns, which were corrected using a source-dependent flat-field image. The evolution of the foam features was well-modeled using the 3D KULL radiation hydrodynamics code. This experimental and modeling platform can be modified for scaled high-energy-density laboratory astrophysics experiments.

Cooper, A. B. R.; Schneider, M. B.; MacLaren, S. A.; Moore, A. S.; Young, P. E.; Hsing, W. W.; Seugling, R.; Foord, M. E.; Sain, J. D.; May, M. J.; Marrs, R. E.; Maddox, B. R.; Lu, K.; Dodson, K.; Smalyuk, V.; Graham, P.; Foster, J. M.; Back, C. A.; Hund, J. F.

2013-03-01

232

A novel compact high speed x-ray streak camera (invited).  

PubMed

Conventional in-line high speed streak cameras have fundamental issues when their performance is extended below a picosecond. The transit time spread caused by both the spread in the photoelectron (PE) "birth" energy and space charge effects causes significant electron pulse broadening along the axis of the streak camera and limits the time resolution. Also it is difficult to generate a sufficiently large sweep speed. This paper describes a new instrument in which the extraction electrostatic field at the photocathode increases with time, converting time to PE energy. A uniform magnetic field is used to measure the PE energy, and thus time, and also focuses in one dimension. Design calculations are presented for the factors limiting the time resolution. With our design, subpicosecond resolution with high dynamic range is expected. PMID:19044647

Hares, J D; Dymoke-Bradshaw, A K L

2008-10-01

233

Time-resolved X-ray excited optical luminescence using an optical streak camera  

NASA Astrophysics Data System (ADS)

We report the development of a time-resolved XEOL (TR-XEOL) system that employs an optical streak camera. We have conducted TR-XEOL experiments at the Canadian Light Source (CLS) operating in single bunch mode with a 570 ns dark gap and 35 ps electron bunch pulse, and at the Advanced Photon Source (APS) operating in top-up mode with a 153 ns dark gap and 33.5 ps electron bunch pulse. To illustrate the power of this technique we measured the TR-XEOL of solid-solution nanopowders of gallium nitride - zinc oxide, and for the first time have been able to resolve near-band-gap (NBG) optical luminescence emission from these materials. Herein we will discuss the development of the streak camera TR-XEOL technique and its application to the study of these novel materials.

Ward, M. J.; Regier, T. Z.; Vogt, J. M.; Gordon, R. A.; Han, W.-Q.; Sham, T. K.

2013-03-01

234

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

235

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

236

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

237

Simulating Record Accomplishments in Baseball Or, That's the Second-Biggest Hitting Streak I've Ever Seen  

Microsoft Academic Search

Simulations of baseball history have been presented as a means of demonstrat- ing the degree of exceptionality of certain feats in the game, notably the 56-game hitting streak of Joe DiMaggio and the less-celebrated 84-game on base streak by Ted Williams. These simulations typically ignore regression to the mean in their estimates of true ability, and do not verify other

Andrew C. Thomas

238

The Allantoic Core Domain: New Insights Into Development of the Murine Allantois and Its Relation to the Primitive Streak  

PubMed Central

The whereabouts and properties of the posterior end of the primitive streak have not been identified in any species. In the mouse, the streak’s posterior terminus is assumed to be confined to the embryonic compartment, and to give rise to the allantois, which links the embryo to its mother during pregnancy. In this study, we have refined our understanding of the biology of the murine posterior primitive streak and its relation to the allantois. Through a combination of immunostaining and morphology, we demonstrate that the primitive streak spans the posterior extraembryonic and embryonic regions at the onset of the neural plate stage (~7.0 days postcoitum, dpc). Several hours later, the allantoic bud emerges from the extraembryonic component of the primitive streak (XPS). Then, possibly in collaboration with overlying allantois-associated extraembryonic visceral endoderm, the XPS establishes a germinal center within the allantois, named here the Allantoic Core Domain (ACD). Microsurgical removal of the ACD beyond headfold (HF) stages resulted in the formation of allantoic regenerates that lacked the ACD and failed to elongate; nevertheless, vasculogenesis and vascular patterning proceeded. In situ and transplantation fate mapping demonstrated that, from HF stages onward, the ACD’s progenitor pool contributed to the allantois exclusive of the proximal flanks. By contrast, the posterior intraembryonic primitive streak (IPS) provided the flanks. Grafting the ACD into TC/TC hosts, whose allantoises are significantly foreshortened, restored allantoic elongation. These results revealed that the ACD is essential for allantoic elongation, but the cues required for vascularization lie outside of it. On the basis of these and previous findings, we conclude that the posterior primitive streak of the mouse conceptus is far more complex than was previously believed. Our results provide new directives for addressing the origin and development of the umbilical cord, and establish a novel paradigm for investigating the fetal/placental relationship. PMID:19191225

Downs, Karen M.; Inman, Kimberly E.; Jin, Dexter X.; Enders, Allen C.

2010-01-01

239

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

240

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

241

Improvements in avalanche-transistor sweep circuitry for electro-optic streak cameras  

Microsoft Academic Search

The authors have improved the performance of the avalanche-transistor deflector-driver (sweep) circuitry used in the high-speed, electro-optic streak camera at Lawrence Livermore National Laboratory. In the previous design for the sweep circuit, trigger-to-output delay time drifted on some cameras. This delay drift is a function of a somewhat randomly unstable breakdown voltage of some avalanche transistors. Both temperature and differences

S. W. Thomas; R. L. Griffith; W. R. McDonald

1986-01-01

242

Comparison of lightning flash rates from the PBE sensor and streak counting from the DMSP satellite  

Microsoft Academic Search

A comparison of lightning trigger rates from the PBE sensor and streaks recorded by the accompanying optical scanner provides a calibration between these two lightning detection techniques. From this calibration is inferred the areal sensitivity of the optical scanner for lightning detection (2.6 x 10⁴ km²). Lightning flash density can be calculated from equations 9 and 10, and global flash

Turman

1984-01-01

243

Signs of the principle body axes prior to primitive streak formation in the rabbit embryo  

Microsoft Academic Search

An early common element during anterior-posterior axis formation amongst amniotes is the primitive streak, running longitudinally in the two-layered embryonic disc. In mammals the primordium of this transient structure is the first definite morphological sign of the anterior-posterior axis, while in avian embryos the axis is visible and apparently defined earlier. Here we scrutinize suggestions that in mammals also there

Christoph Viebahn; Barbara Mayer; Martin Hrabé Angelis

1995-01-01

244

Complete Genome Sequence of an Emerging Genotype of Tobacco Streak Virus in the United States  

PubMed Central

We report here the complete genome sequence of an emerging genotype of tobacco streak virus (TSV) infecting zucchini squash in Florida (TSV_FL13-07), obtained using deep sequencing of short RNAs (sRNAs) and validation by Sanger sequencing. TSV_FL13-07 shares only <90% sequence identity in all three genomic RNAs to several known U.S. isolates. PMID:25377714

Padmanabhan, Chellappan; Gao, Shan; Li, Rugang; Zhang, Shouan; Fei, Zhangjun

2014-01-01

245

Real-time quantitative polymerase chain reaction methods for four genetically modified maize varieties and maize DNA content in food.  

PubMed

Quantitative detection methods are needed for enforcement of the recently introduced labeling threshold for genetically modified organisms (GMOs) in food ingredients. This labeling threshold, which is set to 1% in the European Union and Switzerland, must be applied to all approved GMOs. Four different varieties of maize are approved in the European Union: the insect-resistant Bt176 maize (Maximizer), Btl 1 maize, Mon810 (YieldGard) maize, and the herbicide-tolerant T25 (Liberty Link) maize. Because the labeling must be considered individually for each ingredient, a quantitation system for the endogenous maize content is needed in addition to the GMO-specific detection systems. Quantitative real-time polymerase chain reaction detection methods were developed for the 4 approved genetically modified maize varieties and for an endogenous maize (invertase) gene system. PMID:12083257

Brodmann, Peter D; Ilg, Evelyn C; Berthoud, Hélène; Herrmann, Andre

2002-01-01

246

Effect of maize processing on diet selection in cows  

Microsoft Academic Search

The effect of maize, processed by three different methods, on the diet selection process was studied in 12 fistulated dry cows in a randomized block design. The experimental period lasted 20 days and was repeated twice (eight animals\\/treatment). Treatments allowed selection of different processed maize grains by the animals: sugar cane and coarsely ground maize (CG), sugar cane and finely ground

Fernanda Altieri Ferreira; Roberta Passini; Laura Maria Oliveira Borgatti; Rondon T. Y. B. de Souza; Paula Marques Meyer; Paulo Henrique Mazza Rodrigues

2007-01-01

247

When Genomes Collide: Aberrant Seed Development Following Maize Interploidy Crosses  

Microsoft Academic Search

†Background and Aims The results of wide- or interploidy crosses in angiosperms are unpredictable and often lead to seed abortion. The consequences of reciprocal interploidy crosses have been explored in maize in detail, focusing on alterations to tissue domains in the maize endosperm, and changes in endosperm-specific gene expression. †Methods Following reciprocal interploidy crosses between diploid and tetraploid maize lines,

ANDY J. G REENLAND; G. DICKINSON

2008-01-01

248

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

249

Phytotoxic effects of fumonisin B 1 on maize seedling growth  

Microsoft Academic Search

Fumonisin B1 toxin is produced by the fungusFusarium moniliforme Sheldon, which is systemic to maize (Zea mays L.) and maize seeds. The effects of zero to 100 parts per million fumonisin B1 on the germination process of maize seeds was determined. The presence of fumonisin had no effect on percent seed germination, but fumonisin inhibited radicle elongation by up to

Douglas C. Doehlert; Clarence A. Knutson; Ronald F. Vesonder

1994-01-01

250

Original article Maize-coconut intercropping: effects of shade  

E-print Network

Original article Maize-coconut intercropping: effects of shade and root competition on maize growth from coconut palms. Under artifi- cial shade, the more solar radiation was intercepted, the less. Applying this relation to a maize-coconut intercropping system gave an estimated yield slightly higher than

Paris-Sud XI, Université de

251

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

252

Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.  

PubMed

Streak tube imaging lidar (STIL) is an active imaging system using a pulsed laser transmitter and a streak tube receiver to produce 3D range and intensity imagery. The STIL has recently attracted a great deal of interest and attention due to its advantages of wide azimuth field-of-view, high range and angle resolution, and high frame rate. This work investigates the signal-to-noise performance of STIL systems. A theoretical model for characterizing the signal-to-noise performance of the STIL system with an internal or external intensified streak tube receiver is presented, based on the linear cascaded systems theory of signal and noise propagation. The STIL system is decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Expressions for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. The work presented here is useful for the design and evaluation of STIL systems. PMID:23262622

Yang, Hongru; Wu, Lei; Wang, Xiaopeng; Chen, Chao; Yu, Bing; Yang, Bin; Yuan, Liang; Wu, Lipeng; Xue, Zhanli; Li, Gaoping; Wu, Baoning

2012-12-20

253

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. PMID:24244203

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

254

A compact UV timing fiducial system for use with x-ray streak cameras at NIF  

NASA Astrophysics Data System (ADS)

We present the design of a compact UV (263-nm) timing fiducial system for use with x-ray streak cameras at the National Ignition Facility (NIF). The design consists of remote fiber amplification of an infrared 1053-nm (1?) seed, a free-space optical path that has two stages of frequency conversion from 1? to the fourth harmonic (4?), and fiber delivery of the 4? signal via output fiber for use with an x-ray streak camera. This is all contained within an airbox that can reside in a vacuum. The 1? seed and the pump light for the fiber amplifier is delivered to the airbox via optical fiber ( 100 meters) from a location in the NIF that is shielded from neutron radiation generated from imploding targets during system shots. When complete, the system will be able to provide timing fiducials to multiple x-ray streak cameras on the same system shot. We will present data that demonstrates end-to-end system performance.*

Homoelle, Doug; Bowers, Mark; Browning, Don; Burns, Scott; Erbert, Gaylen; Golick, Brad; Haley, Jim; McCarville, Tom; Opachich, Yekaterina; Padilla, Ernesto; Palmer, Nathan; Perfect, Brad; Pelz, Larry; Spinka, Tom; Throop, Alan; Wong, J. Nan

2012-10-01

255

Femtosecond streaking of electron diffraction patterns to study structural dynamics in crystalline matter  

NASA Astrophysics Data System (ADS)

A table-top femtosecond, non-relativistic, electron diffraction setup is combined with a low-jitter, photo-triggered streak camera to follow the optically induced structural dynamics in complex solids. A temporal resolution of 550 fs is experimentally demonstrated, while the route to streaking with sub-250 fs temporal resolution is outlined. The streaking technique allows for parallel capturing of temporal information as opposed to the serial data acquisition in a conventional scanning femtosecond electron diffraction. Moreover, its temporal resolution is not corrupted by increasing the number of electrons per pulse. Thus, compared to the conventional scanning approach, a substantial increase in signal-to-noise ratio (SNR) can be achieved. These benefits are demonstrated by studying a photo-induced charge density wave phase transition in 4Hb-TaSe2 using both methods. Within the same data acquisition time a three-fold increase in SNR is achieved when compared to the scanning method, with ways for a further improvement outlined.

Eichberger, M.; Erasmus, N.; Haupt, K.; Kassier, G.; von Flotow, A.; Demsar, J.; Schwoerer, H.

2013-03-01

256

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. PMID:17885089

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

2007-01-01

257

Flavone-rich maize: an opportunity to improve the nutritional value of an important commodity crop.  

PubMed

Agricultural outputs have resulted in food production continuously expanding. To satisfy the needs of a fast growing human population, higher yields, more efficient food processing, and food esthetic value, new crop varieties with higher caloric intake have and continue to be developed, but which lack many phytochemicals important for plant protection and adequate human nutrition. The increasing incidence of chronic diseases such as obesity, diabetes and cardiovascular diseases, combined with social disparity worldwide prompted the interest in developing enhanced crops that can simultaneously address the two sides of the current malnutrition sword, increasing yield while providing added nutritional value. Flavones, phytochemicals associated with the beneficial effects of the Mediterranean diet, have potent anti-inflammatory and anti-carcinogenic activities. However, many Mediterranean diet-associated vegetables are inaccessible, or lowly consumed, in many parts of the world. Maize is the most widely grown cereal crop, yet most lines used for hybrid maize production lack flavones. As a first step toward a sustainable strategy to increasing the nutritional value of maize-based diets, we investigated the accumulation and chemical properties of flavones in maize seeds of defined genotypes. We show that the pericarps of the P1-rr genotype accumulate flavones at levels comparable to those present in some flavone-rich vegetables, and are mostly present in their C- and O-glycosylated forms. Some of these glycosides can be readily converted into the corresponding more active health beneficial aglycones during food processing. Our results provide evidence that nutritionally beneficial flavones could be re-introduced into elite lines to increase the dietary benefits of maize. PMID:25250036

Casas, María I; Duarte, Silvia; Doseff, Andrea I; Grotewold, Erich

2014-01-01

258

Safety assessment of BT 176 Maize in broiler nutrition: Degradation of Maize-DNA and its metabolic fate  

Microsoft Academic Search

Insect resistant Bt 176 maize has been developed by genetic modification to resist European borer infection. In the present investigation, the experiment was conducted to determine the effect of feeding a new hybrid of Bt 176 maize (NX 6262 - Bt 176) on general health condition and performance of broiler chickens. Maize grains and diets were subjected to proximate analysis.

M. A. Tony; A. Butschke; H. Broll; L. Grohmann; J. Zagon; I. Halle; S. Dänicke; M. Schauzu; H. M. Hafez; G. Flachowsky

2003-01-01

259

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

260

The genetic architecture of maize flowering time.  

PubMed

Flowering time is a complex trait that controls adaptation of plants to their local environment in the outcrossing species Zea mays (maize). We dissected variation for flowering time with a set of 5000 recombinant inbred lines (maize Nested Association Mapping population, NAM). Nearly a million plants were assayed in eight environments but showed no evidence for any single large-effect quantitative trait loci (QTLs). Instead, we identified evidence for numerous small-effect QTLs shared among families; however, allelic effects differ across founder lines. We identified no individual QTLs at which allelic effects are determined by geographic origin or large effects for epistasis or environmental interactions. Thus, a simple additive model accurately predicts flowering time for maize, in contrast to the genetic architecture observed in the selfing plant species rice and Arabidopsis. PMID:19661422

Buckler, Edward S; Holland, James B; Bradbury, Peter J; Acharya, Charlotte B; Brown, Patrick J; Browne, Chris; Ersoz, Elhan; Flint-Garcia, Sherry; Garcia, Arturo; Glaubitz, Jeffrey C; Goodman, Major M; Harjes, Carlos; Guill, Kate; Kroon, Dallas E; Larsson, Sara; Lepak, Nicholas K; Li, Huihui; Mitchell, Sharon E; Pressoir, Gael; Peiffer, Jason A; Rosas, Marco Oropeza; Rocheford, Torbert R; Romay, M Cinta; Romero, Susan; Salvo, Stella; Sanchez Villeda, Hector; da Silva, H Sofia; Sun, Qi; Tian, Feng; Upadyayula, Narasimham; Ware, Doreen; Yates, Heather; Yu, Jianming; Zhang, Zhiwu; Kresovich, Stephen; McMullen, Michael D

2009-08-01

261

Genome-wide nested association mapping of quantitative resistance to northern leaf blight in maize  

PubMed Central

Quantitative resistance to plant pathogens, controlled by multiple loci of small effect, is important for food production, food security, and food safety but is poorly understood. To gain insights into the genetic architecture of quantitative resistance in maize, we evaluated a 5,000-inbred-line nested association mapping population for resistance to northern leaf blight, a maize disease of global economic importance. Twenty-nine quantitative trait loci were identified, and most had multiple alleles. The large variation in resistance phenotypes could be attributed to the accumulation of numerous loci of small additive effects. Genome-wide nested association mapping, using 1.6 million SNPs, identified multiple candidate genes related to plant defense, including receptor-like kinase genes similar to those involved in basal defense. These results are consistent with the hypothesis that quantitative disease resistance in plants is conditioned by a range of mechanisms and could have considerable mechanistic overlap with basal resistance. PMID:21482771

Poland, Jesse A.; Bradbury, Peter J.; Buckler, Edward S.; Nelson, Rebecca J.

2011-01-01

262

A genome-wide association study reveals genes associated with fusarium ear rot resistance in a maize core diversity panel.  

PubMed

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. PMID:24048647

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

2013-11-01

263

Maize Dwarf Mosaic Can Reduce Weed Suppressive Ability of Sweet Corn Martin M. Williams II and Jerald K. Pataky*  

E-print Network

Maize Dwarf Mosaic Can Reduce Weed Suppressive Ability of Sweet Corn Martin M. Williams II prevalent viral disease of sweet corn grown in many regions of North America and Europe. Although some weeds escape control in most sweet corn fields, the extent to which MDM influences the weed suppressive ability

Sims, Gerald K.

264

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

265

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

266

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

267

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

268

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

269

Reevaluating the Health and Nutritional Status of Maize-Dependent Populations: Evidence for the Impact of Pellagra on Human Skeletons from South Africa  

Microsoft Academic Search

Pellagra, a niacin\\/tryptophan deficiency disease, is prevalent in populations that have high maize\\/low protein diets. Historically it has been essentially a disease of undernutrition and social inequality. We offer a unique analysis of both macro- and microstructural skeletal indicators from 31 individuals known to have died from pellagra (n = 14) and non-specific general malnutrition (n = 17). These cases

Barrett P. Brenton; Robert R. Paine

2007-01-01

270

Gene expression in physically impeded maize roots  

E-print Network

PIIGI contains 678 hp with an open reading frame which specifies a polypeptide of 129 amino acid residues which showed 97% similarity at the nucleic acid level to maize root cortical cell delineating protein. Northern analysis with cDNA PIIGI as a probe...

Huang, Ying-Fei

2012-06-07

271

Molecular Evidenceandthe Evolutionof Maize JOHN DOEBLEY1  

E-print Network

not disprove such theories. Analyses of isozyme and chloroplast DNA diversity in Zea provide evidence of isozyme and chloroplast DNA studies to questions surrounding the evolution of maize are summarized proposed by Iltis and Doebley (1980). Molecular evidence isfully congruent with the theory that teosinte

Doebley, John

272

Conservation and diversification of SCARECROW in maize  

PubMed Central

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 Arabidopsis scr mutant phenotype suggests conservation of function, yet its expression pattern during embryogenesis and in the shoot system indicates divergence. ZmSCR expression was detected early during embryogenesis and localized to the endodermal lineage in the root, showing a gradual regionalization of expression. Expression of ZmSCR appeared to be analogous to that of SCR during leaf formation. However, its absence from the maize shoot meristem and its early expression pattern during embryogenesis suggest a diversification of ZmSCR in the patterning processes in maize. To further investigate the evolutionary relationship of SCR and ZmSCR, we performed a phylogenetic analysis using Arabidopsis, rice and maize SCARECROW-LIKE genes (SCLs). We found SCL23 to be the most closely related to SCR in both eudicots and monocots, suggesting that a gene duplication resulting in SCR and SCL23 predates the divergence of dicots and monocots. PMID:16244911

Lim, Jun; Jung, Jee W.; Lim, Chae Eun; Lee, Mi-Hyun; Kim, Bong Jun; Kim, Miran; Bruce, Wesley B.; Benfey, Philip N.

2006-01-01

273

Ribonucleoprotein particles of quiescent maize embryonic axes  

Microsoft Academic Search

Certain RNA molecules are known to be sequestered and stored as ribonucleoprotein particles (RNPs) in many different tissues, particularly at some stages of metabolic quiescence. In this research RNPs from embryonic axes of mature maize seeds were isolated by sucrose and CsCl gradient centrifugation and characterized based on their RNA and protein contents. Two types of RNP particles of non-ribosomal

Alma Rincón-Guzmán; Elda Beltrán-Peña; Adriana Ortíz-López; Estela Sánchez de Jiménez

1998-01-01

274

Neocentromere-mediated Chromosome Movement in Maize  

Microsoft Academic Search

Neocentromere activity is a classic example of nonkinetochore chromosome movement. In maize, neocentromeres are induced by a gene or genes on Abnormal chromosome 10 (Ab10) which causes het- erochromatic knobs to move poleward at meiotic anaphase. Here we describe experiments that test how neocentromere activity affects the function of linked centromere\\/kinetochores (kinetochores) and whether neocentromeres and kinetochores are mobilized on

Hong-Guo Yu; Evelyn N. Hiatt; Annette Chan; Mary Sweeney; R. Kelly Dawe

1997-01-01

275

Streak-photographic investigation of shock wave emission after laser-induced plasma formation in water  

NASA Astrophysics Data System (ADS)

The shock wave emission after dielectric breakdown in water was investigated to assess potential shock wave effects in plasma mediated tissue ablation and intraocular photodisruption. Of particular interest was the dependence of shock wave pressure as a function of distance from the plasma for different laser pulse energies. We have generated plasmas in water with a Nd:YAG laser system delivering pulses of 6 ns duration. The pulses, with energies between 0.4 and 36 mJ (approximately equals 180 times threshold), were focused into a cuvette containing distilled water. The shock wave was visualized with streak photography combined with a schlieren technique. An important advantage of this technique is that the shock position as a function of time can directly be obtained from a single streak and hence a single event. Other methods (e.g. flash photography or passage time measurements between fixed locations) in contrast rely on reproducible events. Using the shock wave speed obtained from the streak images, shock wave peak pressures were calculated providing detailed information on the propagation of the shock. The shock peak pressure as a function of distance r from the optical axis was found to decrease faster than 1/r2 in regions up to distances of 100-150 micrometers . For larger distances it was found to be roughly proportional to 1/r. The scaling law for maximum shock pressure p, at a given distance was found to be proportional to the square root of the laser pulse energy E for distances of 50-200 micrometers from the optical axis.

Noack, Joachim; Vogel, Alfred

1995-05-01

276

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

PubMed

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/cm(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. PMID:22938275

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

2012-08-01

277

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

278

A new tubeless nanosecond streak camera based on optical deflection and direct CCD imaging  

SciTech Connect

A new optically deflected streaking camera with performance of nanosecond-range resolution, superior imaging quality, high signal detectability, and large format recording has been conceived and developed. Its construction is composed of an optomechanical deflector that deflects the line-shape image of spatial-distributed time-varying signals across the sensing surface of a cooled scientific two-dimensional CCD array with slow readout driving electronics, a lens assembly, and a desk-top computer for prompt digital data acquisition and processing. Its development utilizes the synergism of modern technologies in sensor, optical deflector, optics and microcomputer. With laser light as signal carrier, the deflecting optics produces near diffraction-limited streak images resolving to a single pixel size of 25{mu}. A 1kx1k-pixel array can thus provide a vast record of 1,000 digital data points along each spatial or temporal axis. Since only one photon-to-electron conversion exists in the entire signal recording path, the camera responses linearly to the incident light over a wide dynamic range in excess of 10{sup 4}:1. Various image deflection techniques are assessed for imaging fidelity, deflection speed, and capacity for external triggering. Innovative multiple-pass deflection methods for utilizing optomechanical deflector have been conceived and developed to attain multi-fold amplification for the optical scanning. speed across the CCD surface at a given angular deflector speed. Without significantly compromising imaging. quality or flux throughput efficiency, these optical methods enable a sub-10 ns/pixel streak speed with the deflector moving benignly at 500 radians/second, or equivalently 80 revolutions /second. Test results of the prototype performance are summarized including a spatial resolution of 10 lp/mm at 65% CTF and a temporal resolution of 11.4 ns at 3.8 ns/pixel.

Lai, C.C.

1992-12-01

279

A new tubeless nanosecond streak camera based on optical deflection and direct CCD imaging  

SciTech Connect

A new optically deflected streaking camera with performance of nanosecond-range resolution, superior imaging quality, high signal detectability, and large format recording has been conceived and developed. Its construction is composed of an optomechanical deflector that deflects the line-shape image of spatial-distributed time-varying signals across the sensing surface of a cooled scientific two-dimensional CCD array with slow readout driving electronics, a lens assembly, and a desk-top computer for prompt digital data acquisition and processing. Its development utilizes the synergism of modern technologies in sensor, optical deflector, optics and microcomputer. With laser light as signal carrier, the deflecting optics produces near diffraction-limited streak images resolving to a single pixel size of 25[mu]. A 1kx1k-pixel array can thus provide a vast record of 1,000 digital data points along each spatial or temporal axis. Since only one photon-to-electron conversion exists in the entire signal recording path, the camera responses linearly to the incident light over a wide dynamic range in excess of 10[sup 4]:1. Various image deflection techniques are assessed for imaging fidelity, deflection speed, and capacity for external triggering. Innovative multiple-pass deflection methods for utilizing optomechanical deflector have been conceived and developed to attain multi-fold amplification for the optical scanning. speed across the CCD surface at a given angular deflector speed. Without significantly compromising imaging. quality or flux throughput efficiency, these optical methods enable a sub-10 ns/pixel streak speed with the deflector moving benignly at 500 radians/second, or equivalently 80 revolutions /second. Test results of the prototype performance are summarized including a spatial resolution of 10 lp/mm at 65% CTF and a temporal resolution of 11.4 ns at 3.8 ns/pixel.

Lai, C.C.

1992-12-01

280

Physics and roller coasters-The Blue Streak at Cedar Point  

NASA Astrophysics Data System (ADS)

The use of a roller coaster for external classroom studies of kinematics, forces, dynamics, and energy conservation is discussed. Experimental accelerometer measurements of the vertical forces acting on riders of the Blue Streak at Cedar Point in Sandusky, Ohio are presented. Theoretically, the track profile is used to calculate/predict the vertical forces acting on a rider at the hilltops, valley bottoms, and several other points of interest along the track. Finally the experimental results and theoretical predictions are compared in the context of a rider's experiences.

Speers, Robert R.

1991-06-01

281

Frequency-domain streak camera for ultrafast imaging of evolving light-velocity objects.  

PubMed

We demonstrate a frequency-domain streak camera (FDSC) that captures the picosecond time evolution of luminal-velocity refractive index structures in a single shot. In our prototype FDSC, a probe-reference pulse pair propagates obliquely to a subpicosecond pump pulse that creates an evolving nonlinear index structure in glass, supplementing a conventional frequency-domain holographic probe-reference pair that copropagates with the pump. A single spectrometer acquires data from both pairs via spatial or temporal multiplexing, demonstrating the feasibility of a compact frequency-domain tomographic system in which a single spectrometer processes data from multiple probing angles. PMID:21165098

Li, Z; Zgadzaj, R; Wang, X; Reed, S; Dong, P; Downer, M C

2010-12-15

282

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

283

Subpicosecond hard x-ray streak camera using single-photon counting.  

PubMed

We have developed and characterized a hard x-ray accumulating streak camera that achieves subpicosecond time resolution by using single-photon counting. A high repetition rate of 2 kHz was achieved by use of a readout camera with built-in image processing capabilities. The effects of sweep jitter were removed by using a UV timing reference. The use of single-photon counting allows the camera to reach a high quantum efficiency by not limiting the divergence of the photoelectrons. PMID:20890339

Enquist, Henrik; Navirian, Hengameh; Nüske, Ralf; von Korff Schmising, Clemens; Jurgilaitis, Andrius; Herzog, Marc; Bargheer, Matias; Sondhauss, Peter; Larsson, Jörgen

2010-10-01

284

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

285

Temporal Characterization of Electron Beam Bunches with a Fast Streak Camera at the JLab FEL Facility  

SciTech Connect

The design and construction of an optical transport that brings synchrotron radiation from electron bunches to a fast streak camera in a remote area has become a useful tool for online observation of bunch length and stability. This paper will report on the temporal measurements we have done, comparison with simulations, and the on-going work for another imaging optical transport system that will make possible the direct measurement of the longitudinal phase space by measuring the bunch length as a function of energy

S. Zhang; S.V. Benson; D. Douglas; D. Hardy; C. Hernandez-Garcia; K. Jordan; G. Neil; Michelle D. Shinn

2005-08-21

286

Modes on a short SPEAR bunch as observed with a streak camera  

SciTech Connect

The longitudinal structure of electron bunches in the storage ring SPEAR on a single pass was studied with time resolution approx. 10 ps. The measuring instrument used is an image-converter streak camera, a specialized device heretofore used mostly by laser workers. Unexpectedly, under some conditions the charge in a single RF bucket breaks up into two short sub-bunches which seem to rotate about a common center in energy-phase space. No evidence is seen for other, higher-frequency structure on the bunches.

Sabersky, A.P.; Donald, M.H.R.

1981-02-01

287

Achieving 280 fs resolution with a streak camera by reducing the deflection dispersion  

SciTech Connect

The factors that limit the temporal resolution in a streak camera operating in an accumulative mode were studied. By controlling the timing jitter, the transit-time dispersion and the technical resolution of the camera on the order of 100 fs, the role of the deflection dispersion was investigated experimentally. It was done by changing the electron beam size in the deflection plates with a variable slit in front of the plates. The temporal resolution of the camera reached 280 fs when the slit width was a 5 {mu}m slit.

Shakya, Mahendra Man; Chang Zenghu [J.R. MacDonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States)

2005-07-25

288

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. PMID:22911570

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

289

Genetic Diversity and Molecular Evolution of Chinese Waxy Maize Germplasm  

PubMed Central

Waxy maize (Zea mays L. var. certaina Kulesh), with many excellent characters in terms of starch composition and economic value, has grown in China for a long history and its production has increased dramatically in recent decades. However, the evolution and origin of waxy maize still remains unclear. We studied the genetic diversity of Chinese waxy maize including typical landraces and inbred lines by SSR analysis and the results showed a wide genetic diversity in the Chinese waxy maize germplasm. We analyzed the origin and evolution of waxy maize by sequencing 108 samples, and downloading 52 sequences from GenBank for the waxy locus in a number of accessions from genus Zea. A sharp reduction of nucleotide diversity and significant neutrality tests (Tajima’s D and Fu and Li’s F*) were observed at the waxy locus in Chinese waxy maize but not in nonglutinous maize. Phylogenetic analysis indicated that Chinese waxy maize originated from the cultivated flint maize and most of the modern waxy maize inbred lines showed a distinct independent origin and evolution process compared with the germplasm from Southwest China. The results indicated that an agronomic trait can be quickly improved to meet production demand by selection. PMID:23818949

Zheng, Hongjian; Wang, Hui; Yang, Hua; Wu, Jinhong; Shi, Biao; Cai, Run; Xu, Yunbi; Wu, Aizhong; Luo, Lijun

2013-01-01

290

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

291

Genetic characterization of a core set of a tropical maize race Tuxpeño for further use in maize improvement.  

PubMed

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. PMID:22412898

Wen, Weiwei; Franco, Jorge; Chavez-Tovar, Victor H; Yan, Jianbing; Taba, Suketoshi

2012-01-01

292

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. PMID:22412898

Chavez-Tovar, Victor H.; Yan, Jianbing; Taba, Suketoshi

2012-01-01

293

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

294

Slit-mounted LED fiducial system for rotating mirror streak cameras  

SciTech Connect

We have developed a fiducial system for rotating mirror streak cameras that utilizes light emitting diodes mounted at the slit position of the camera. The diodes are driven to the required high brightness by a unique pulse power circuit designed to provide high voltage, high current pulses 18 nanoseconds in length at a frequency of up to 2.5 megahertz. The availability of super bright light emitting diodes with a wavelength of 630 to 640 nanometers allows us to record fiducial pulses, at streaking speeds in excess of 20mm per microsecond, on all the black and white films commonly used in high speed photography. The time marks on the film record are referenced to the real time of the experiment from a clock-driver that controls the start and frequency of the fiducial pulse train and by three adjustable and discreet blanked fiducials. This paper discusses the development of this system and describes the full setup as used at LLNL. 6 refs., 4 figs.

Shaw, L.L.; Muelder, S.A.; Rivera, A.T.

1991-01-01

295

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

296

PS-1/S1 picosecond streak camera application for multichannel laser system diagnostics  

NASA Astrophysics Data System (ADS)

A PS-1/S1 picosecond image-tube streak camera (ITSC) with slit scan (streak camera), developed and manufactured at the General Physics Institute RAS, has been used to measure the spatiotemporal characteristics of ultrashort laser pulses generated by a petawatt-power laser installation 'FEMTO' at the Institute of Laser Physics Research in Sarov. It is found that such a camera is suitable for measuring the spatial and temporal parameters of single laser pulses with an accuracy of about one picosecond. It is shown that the intensity time profile of a train of picosecond pulses may be precisely defined for the pulses separated in time by a few picoseconds. The camera allows the contrast of radiation to be determined with a high (no less than 103) accuracy; spatial distribution of the laser pulses can be measured with an accuracy of tens of microns, and the temporal separation of single laser pulses can be identified with an accuracy of 1 – 1.5 ps.

Garanin, S. G.; Bel'kov, S. A.; Rogozhnikov, G. S.; Rukavishnikov, N. N.; Romanov, V. V.; Voronich, I. N.; Vorob'ev, N. S.; Gornostaev, P. B.; Lozovoi, V. I.; Shchelev, M. Ya

2014-08-01

297

Gas-phase lifetimes of nucleobase analogues by picosecond pumpionization and streak techniques.  

PubMed

The picosecond (ps) timescale is relevant for the investigation of many molecular dynamical processes such as fluorescence, nonradiative relaxation, intramolecular vibrational relaxation, molecular rotation and intermolecular energy transfer, to name a few. While investigations of ultrafast (femtosecond) processes of biological molecules, e.g. nucleobases and their analogues in the gas phase are available, there are few investigations on the ps time scale. We have constructed a ps pump-ionization setup and a ps streak camera fluorescence apparatus for the determination of lifetimes of supersonic jet-cooled and isolated molecules and clusters. The ps pump-ionization setup was used to determine the lifetimes of the nucleobase analogue 2-aminopurine (2AP) and of two 2AP?(H2O)n water cluster isomers with n=1 and 2. Their lifetimes lie between 150 ps and 3 ns and are strongly cluster-size dependent. The ps streak camera setup was used to determine accurate fluorescence lifetimes of the uracil analogue 2-pyridone (2PY), its self-dimer (2PY)2, two isomers of its trimer (2PY)3 and its tetramer (2PY)4, which lie in the 7-12 ns range. PMID:24983611

Blaser, Susan; Frey, Hans-Martin; Heid, Cornelia G; Leutwyler, Samuel

2014-01-01

298

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

299

An Optical Streak Diagnostic for Observing Anode-Cathode Plasmas for Radiographic Source Development  

SciTech Connect

National Security Technologies, LLC, and Sandia National Laboratories are collaborating in the development of pulsed power–driven flash x-ray radiographic sources that utilize high-intensity electron beam diodes. The RITS 6 (Radiographic Integrated Test Stand) accelerator at Sandia is used to drive a self magnetic pinch diode to produce a Bremsstrahlung x-ray source. The high electric fields and current densities associated with these short A-K gap pinch beam diodes present many challenges in diode development. Plasmas generated at both the anode and cathode affect the diode performance, which is manifested in varying spot (source) sizes, total dose output, and impedance profiles. Understanding the nature of these plasmas including closure rates and densities is important in modeling their behavior and providing insight into their mitigation. In this paper we describe a streak camera–based optical diagnostic that is capable of observing and measuring plasma evolution within the A-K gap. By imaging a region of interest onto the input slit of a streak camera, we are able to produce a time-resolved one-dimensional image of the evolving plasma. Typical data are presented.

Droemer, Darryl W. [National Security Technologies, LLC; Crain, Marlon D.; Lare, Gregory A. [National Security Technologies, LLC; Bennett, Nichelle L. [National Security Technologies, LLC; Johnston, Mark D. [Sandia National Laboratories

2013-06-13

300

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. PMID:23379350

2013-01-01

301

Bt maize and integrated pest management--a European perspective.  

PubMed

The European corn borer (Ostrinia nubilalis), the Mediterranean corn borer (Sesamia nonagrioides) and the western corn rootworm (Diabrotica virgifera virgifera) are the main arthropod pests in European maize production. Practised pest control includes chemical control, biological control and cultural control such as ploughing and crop rotation. A pest control option that is available since 1996 is maize varieties that are genetically engineered (GE) to produce insecticidal compounds. GE maize varieties available today express one or several genes from Bacillus thuringiensis (Bt) that target corn borers or corn rootworms. Incentives to growing Bt maize are simplified farm operations, high pest control efficiency, improved grain quality and ecological benefits. Limitations include the risk of resistance evolution in target pest populations, risk of secondary pest outbreaks and increased administration to comply with licence agreements. Growers willing to plant Bt maize in the European Union (EU) often face the problem that authorisation is denied. Only one Bt maize transformation event (MON810) is currently authorised for commercial cultivation, and some national authorities have banned cultivation. Spain is the only EU member state where Bt maize adoption levels are currently delivering farm income gains near full potential levels. In an integrated pest management (IPM) context, Bt maize can be regarded as a preventive (host plant resistance) or a responsive pest control measure. In any case, Bt maize is a highly specific tool that efficiently controls the main pests and allows combination with other preventive or responsive measures to solve other agricultural problems including those with secondary pests. PMID:21710684

Meissle, Michael; Romeis, Jörg; Bigler, Franz

2011-09-01

302

Ultraweak photon emission from herbivory-injured maize plants  

NASA Astrophysics Data System (ADS)

Following perception of herbivory or infection, plants exhibit a wide range of inducible responses. In this study, we found ultraweak photon emissions from maize leaves damaged by Helicoverpa armigera (Noctuidae). Interestingly, mechanically damaged maize leaves treated with caterpillar regurgitants emitted the same intensity and pattern of photon emissions as those from maize leaves damaged by caterpillars. Furthermore, two-dimensional imaging of the leaf section treated with the oral secretions clearly shows that photon emissions were observed specifically at the lip of the wound exposed to the secretions. These results suggest that the direct interaction between maize leaf cells and chemicals contained in caterpillar regurgitants triggers these photon emissions.

Yoshinaga, Naoko; Kato, Kimihiko; Kageyama, Chizuko; Fujisaki, Kenji; Nishida, Ritsuo; Mori, Naoki

2006-01-01

303

Evaluation of fall armyworm resistance in maize germplasm lines using visual leaf injury rating and predator survey.  

PubMed

After examining ear-colonizing pest resistance, 20 maize lines from the USDA-ARS Germplasm Enhancement of Maize (GEM) Program were evaluated for whorl-feeding fall armyworm (FAW) (Spodoptera frugiperda) resistance using 4 maize inbred lines as the resistant and susceptible controls. Both FAW injury ratings at 7- and 14-d after infestation, and predator abundance and diversity at whorl stage (V6-V8) were recorded in 2009 and 2010. The survey of the diversity and abundance of predators in each experimental plot were conducted 7 d after the FAW infestation. Of the 20 germplasm lines examined, 3 of them (i.e., entries 9, 15, and 19 that were derived from tropical maize germplasm lines were originated from Uruguay, Cuba, and Thailand, respectively) were identified as the best FAW-resistant germplasm lines using the leaf injury ratings and predator survey data. In addition, the abundance and diversity of the predators were greater in 2010 than in 2009, which might have caused the low level of the FAW injury ratings on all lines examined in 2010. The 2-year data showed that the FAW injury ratings were negatively correlated to the predator abundance and diversity, which is also influence by genotype × environment interactions. The findings suggested that tropical germplasm is an important source of native resistance to the FAW and the corn earworm. At the same time, the maize genotype × environment interaction (e.g., predator attractiveness, and varying weather conditions) should be included in the multiple-year evaluations of insect and disease resistance of maize germplasm lines under field conditions. PMID:24318539

Ni, Xinzhi; Xu, Wenwei; Blanco, Michael H; Williams, W Paul

2014-10-01

304

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

305

Thermotropism by primary roots of maize  

SciTech Connect

Sensing in the roots of higher plants has long been recognized to be restricted mainly to gravitropism and thigmotropism. However, root responses to temperature gradients have not been extensively studied. We have designed experiments under controlled conditions to test if and how root direction of maize can be altered by thermal gradients perpendicular to the gravity vector. Primary roots of maize grown on agar plates exhibit positive thermotropism (curvature toward the warmer temperature) when exposed to gradients of 0.5 to 4.2{degree}C cm{sup {minus}1}. The extent of thermotropism depends on the temperature gradient and the temperature at which the root is placed within the gradient. The curvature cannot be accounted for by differential growth as a direct effect of temperature on each side of the root.

Fortin, M.-C.; Poff, K.L. (MSU-DOE Plant Research Laboratory, East Lansing, MI (USA))

1990-05-01

306

Programmed Cell Death during Embryogenesis in Maize  

PubMed Central

Programmed cell death (PCD) in plants is considered an integral part of development. Evidence of DNA fragmentation, occurring at specific sites and times during embryo formation in maize (Zea mays L.), was obtained using terminal deoxyribonucleotidyl transferase?mediated dUTP?fluorescein nick end labelling (TUNEL) and by genomic DNA ladder detection. During the crucial period of elaboration of the primary shoot and root axis (14–20 d after pollination), TUNEL?positive nuclei are present in the scutellum, coleoptile, root cap and principally in the suspensor. Additional evidence of a form of programmed cell death occurring in these tissues comes from the detection of a DNA ladder. Upon completion of the differentiation process, all embryonic cells are TUNEL?negative, indicating that possible programmed cell death events during maize embryogenesis are confined to structures or organs that do not contribute to the adult plant body. PMID:12197527

GIULIANI, CONCETTA; CONSONNI, GABRIELLA; GAVAZZI, GIUSEPPE; COLOMBO, MONICA; DOLFINI, SILVANA

2002-01-01

307

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. PMID:10889260

Glawischnig, Erich; Tomas, Adriana; Eisenreich, Wolfgang; Spiteller, Peter; Bacher, Adelbert; Gierl, Alfons

2000-01-01

308

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

309

Importance of heat shock proteins in maize  

Microsoft Academic Search

Abiotic and biotic stress conditions cause extensive losses to maize production, mainly due to protein dysfunction in these\\u000a conditions. In higher plants, the occurrence of heat-shock proteins (HSPs) in response to different environmental stresses\\u000a is a universal phenomenon and has been well documented. Many studies have demonstrated that most HSPs are involved in many\\u000a regulatory pathways, act as molecular chaperones

Camila Pegoraro; Liliane Marcia Mertz; Luciano Carlos da Maia; Cesar Valmor Rombaldi; Antonio Costa de Oliveira

2011-01-01

310

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. PMID:24050704

2013-01-01

311

Hydroquinone peroxidase activity of maize root mitochondria  

Microsoft Academic Search

Summary.  The oxidation of hydroquinone with H2O2 in the presence of mitochondria isolated from maize (Zea mays L.) roots was studied. The results indicate that a reduced form of quinone may be a substrate of mitochondrial peroxidases.\\u000a Specific activities in different mitochondrial isolates, the apparent K\\u000a m for hydrogen peroxide and hydroquinone, and the influence of some known peroxidase inhibitors or

Vesna Hadži-Taškovi? Šukalovi?; B. Kukavica; M. Vuleti?

2007-01-01

312

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

313

Gibberellins and Heterosis in Maize 1  

PubMed Central

Two maize inbreds, CM7 and CM49, and CM7 × CM49, their F1 hybrid (which displayed significant heterosis), were examined with regard to response to exogenous gibberellin A3 (GA3), and in their ability to metabolize GA20, a native GA of maize. The leaf sheath elongation response to GA3 was far greater for the imbreds than for their hybrid. The inbreds also displayed significant elongation of the leaf blades in response to GA3, whereas the hybrid was unaffected. Promotion of cell division in the leaf sheath of CM7 and the hybrid was effected by GA3, but no promotion of cell elongation was observed in CM49, even though significant leaf sheath elongation occurred. Shoot dry weight of both inbreds was significantly increased by GA3, but response by the hybrid in this parameter was slight and variable. Root dry weight of CM7 was significantly increased by GA3, but was unchanged in CM49 and the hybrid. Thus, inbred shoot dry weight increases effected by GA3 were not at the expense of the root system. Rapid metabolism of [2,3-3H]GA20 occurred in all genotypes, although genotypic differences were observed. The hybrid had the highest rates of metabolism to GA glucosyl conjugate-like substances. Oxidative metabolism was also fastest in the hybrid, followed by CM7, and slowest in CM49, the slowest-growing inbred. Thus, rate of GA20 metabolism is under genetic control in normal (i.e. not dwarfed) maize genotypes. These results, taken together with previous reports that the hybrid has significantly enhanced levels of endogenous GA-like substances, suggest that GA play a role in the expression of heterosis in maize. Images Fig. 2 PMID:16662881

Rood, Stewart B.; Blake, Terence J.; Pharis, Richard P.

1983-01-01

314

Tracing transgenic maize as affected by breadmaking process and raw material for the production of a traditional maize bread, broa.  

PubMed

Broa is a maize bread highly consumed and appreciated, especially in the north and central zones of Portugal. In the manufacturing of broa, maize flour and maize semolina might be used, besides other cereals such as wheat and rye. Considering the needs for genetically modified organism (GMO) traceability in highly processed foods, the aim of this work was to assess DNA degradation, DNA amplification and GMO quantification along breadmaking process of broa. DNA degradation was noticed by its decrease of integrity after dough baking and in all parts of bread sampling. The PCR amplification results of extracted DNA from the three distinct maize breads (broa 1, 2 and 3) showed that sequences for maize invertase gene and for events MON810 and TC1507 were easily detected with strong products. Real-time PCR revealed that quantification of GMO was feasible in the three different breads and that sampling location of baked bread might have a limited influence since the average quantitative results of both events after baking were very close to the actual values in the case of broa 1 (prepared with maize semolina). In the other two maize breads subjected to the same baking treatment, the contents of MON810 maize were considerably underestimated, leading to the conclusion that heat-processing was not the responsible parameter for that distortion, but the size of particle and mechanical processing of raw maize play also a major role in GMO quantification. PMID:23265541

Fernandes, Telmo J R; Oliveira, M Beatriz P P; Mafra, Isabel

2013-05-01

315

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

316

Natural maize phenolic acids for control of aflatoxigenic fungi on maize.  

PubMed

Natural phytochemicals may be an alternative to synthetic chemicals for controlling fungal growth and mycotoxin production in stored maize. A key to progress in this field is to select the best natural maize phytochemicals to be applied in a storage maize ecosystem. This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) and ferulic acid (FA) alone at concentrations of 20 to 30 mM and in 5 combinations on Aspergillus flavus Link and A. parasiticus Speare populations and aflatoxin B(1) production. Studies on Aspergillus population and aflatoxin B(1) production were carried out in maize grain in relation to a water activity a(w) of 0.99, 0.97, 0.95, and 0.93. CA and FA at concentrations of 25 to 30 mM, respectively, and CA-FA mixture T9 (25 + 30 mM) were the treatments most effective at inhibiting A. flavus and A. parasiticus population at all a(w) assayed after 11 d of incubation. At all a(w) values, the mixture CA-FA T9 (25 + 30 mM) completely inhibited (100%) aflatoxin B(1) production by both strains at a(w)= 0.99, 0.97, 0.95, and 0.93. Decreased aflatoxin B(1) levels in comparison with the control were observed with mixtures CA-FA T6 (10 + 25 mM), T7 (20 + 20 mM), and T8 (20 + 30 mM) of both strains in the majority of a(w) assayed. The data show that CA and FA could be considered as effective fungitoxicants for A. flavus and A. parasiticus in maize in the a(w) range 0.99 to 0.93. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize. PMID:17995741

Nesci, A; Gsponer, N; Etcheverry, M

2007-06-01

317

Regional mutagenesis using Dissociation in maize.  

PubMed

We describe genetic screens, molecular methods and web resources newly available to utilize Dissociation (Ds) as an insertional mutagen in maize. Over 1700 Ds elements have been distributed throughout the maize genome to serve as donor elements for local or regional mutagenesis. Two genetic screens are described to identify Ds insertions in genes-of-interest (goi). In scheme I, Ds is used to generate insertion alleles when a recessive reference allele is available. A Ds insertion will enable the cloning of the target gene and can be used to create an allelic series. In scheme II, Ds insertions in a goi are identified using a PCR-based screen to identify the rare insertion alleles among a population of testcross progeny. We detail an inverse PCR protocol to rapidly amplify sequences flanking Ds insertion alleles and describe a high-throughput 96-well plate-based DNA extraction method for the recovery of high-quality genomic DNA from seedling tissues. We also describe several web-based tools for browsing, searching and accessing the genetic materials described. The development of these Ds insertion lines promises to greatly accelerate functional genomics studies in maize. PMID:19394430

Ahern, Kevin R; Deewatthanawong, Prasit; Schares, Justin; Muszynski, Michael; Weeks, Rebecca; Vollbrecht, Erik; Duvick, Jon; Brendel, Volker P; Brutnell, Thomas P

2009-11-01

318

Lipids in Aspergillus flavus-maize interaction  

PubMed Central

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

319

Applications of a streak-camera-based imager with simultaneous high space and time resolution  

NASA Astrophysics Data System (ADS)

A high-speed imaging device has been built that is capable of recording several hundred images over a time span of 25 to 400 ns. The imager is based on a streak camera, which provides both spatial and temporal resolution. The system's current angular resolution is 16 X 16 pixels, with a time resolution of 250 ps. It was initially employed to provide 3-D images of objects, in conjunction with a short-pulse (approximately 100 ps) laser. For the 3-D (angle-angle-range) laser radar, the 250 ps time resolution corresponds to a range resolution of 4 cm. In the 3-D system, light from a short-pulse laser (a frequency-doubled, Q-switched, mode-locked Nd:YAG laser operating at a wavelength of 532 nm) flood-illuminates a target of linear dimension approximately 1 m. The returning light from the target is imaged, and the image is dissected by a 16 X 16 array of optical fibers. At the other end of the fiber optic image converter, the 256 fibers form a vertical line array, which is input to the slit of a streak camera. The streak camera sweeps the input line across the output phosphor screen so that horizontal position is directly proportional to time. The resulting 2-D image (fiber location vs. time) at the phosphor is read by an intensified (SIT) vidicon TV tube, and the image is digitized and stored. A computer subsequently decodes the image, unscrambling the linear pixels into an angle-angle image at each time or range bin. We are left with a series of snapshots, each one depicting the portion of target surface in a given range bin. The pictures can be combined to form a 3-D realization of the target. Continuous recording of many images over a short time span is of use in imaging other transient phenomena. These applications share a need for multiple images from a nonrepeatable transient event of time duration on the order of nanoseconds. Applications discussed for the imager include (1) pulsed laser beam diagnostics -- measuring laser beam spatial and temporal structure, (2) reflectivity monitoring during pulsed laser annealing of microelectronics, and (3) detonics or shock wave research, especially microscopic studies of shocks produced by laser pulses.

Klick, David I.; Knight, Frederick K.

1993-01-01

320

Resolution limitations and optimization of the ITT F4157 streak tube focus for fast (10 ps) operation  

SciTech Connect

The ITT F4157 image tube is biased at voltages far from the original design for operation in an ultrafast (10 ps) streak camera. Its output resolution at streak camera operating potentials has been measured as a function of input slit width, incident-light wavelength, and focus-grid voltage. The results are similar to those reported for the RCA C73435 streak tube. Indeed, the two tubes can be substituted for each other with minor mechanical modifications. The temporal resolution is insensitive to focus-grid voltage for a narrow (50 ..mu..m) input slit, but is very sensitive to focus-grid voltage for a wide (500 ..mu..m) input slit. Spatial resolution is nearly independent of focus-grid voltage for values that give good temporal resolution. Both temporal and spatial resolution depend on the incident-light wavelength. Streak camera operation is simulated with a computer program that calculates photoelectron trajectories. Electron ray tracing describes the observed effects of slit width, incident-light wavelength, and focus-grid voltage on the output resolution. 6 refs., 10 figs., 1 tab.

Lerche, R.A.; Grasz, E.L.; Griffith, R.L.; Simpson, R.A.; Posey, R.

1987-11-01

321

Chirp Measurement of Multimode Q Switched Laser Diode Pulses by Use of a Streak Camera and a Grating Monochromator  

Microsoft Academic Search

We discuss spectrotemporal measurements of laser diode pulses performed with a streak camera and a grating monochromator to yield a precise evaluation of chirping effects in Q -switched multimode emissions. We experimentally illustrate several causes of errors, depending on the grating size and period as well as on the adjustment of the collimating lens at the monochromator output. An analytical

Alexandre Bresson; Nikolaï Stelmakh; Jean-Michel Lourtioz; Alexandre Shen; Claude Froehly

1998-01-01

322

A 'chemotactic dipole' mechanism for large-scale vortex motion during primitive streak formation in the chick embryo  

NASA Astrophysics Data System (ADS)

Primitive streak formation in the chick embryo involves significant coordinated cell movement lateral to the streak, in addition to the posterior-anterior movement of cells in the streak proper. Cells lateral to the streak are observed to undergo 'polonaise movements', i.e. two large counter-rotating vortices, reminiscent of eddies in a fluid. In this paper, we propose a mechanism for these movement patterns which relies on chemotactic signals emitted by a dipolar configuration of cells in the posterior region of the epiblast. The 'chemotactic dipole' consists of adjacent regions of cells emitting chemo-attractants and chemo-repellents. We motivate this idea using a mathematical analogy between chemotaxis and electrostatics, and test this idea using large-scale computer simulations. We implement active cell response to both neighboring mechanical interactions and chemotactic gradients using the Subcellular Element Model. Simulations show the emergence of large-scale vortices of cell movement. The length and time scales of vortex formation are in reasonable agreement with experimental data. We also provide quantitative estimates for the robustness of the chemotaxis dipole mechanism, which indicate that the mechanism has an error tolerance of about 10% to variation in chemotactic parameters, assuming that only 1% of the cell population is involved in emitting signals. This tolerance increases for larger populations of cells emitting signals.

Sandersius, S. A.; Chuai, M.; Weijer, C. J.; Newman, T. J.

2011-08-01

323

1 Introduction Gazing at a flower garden through a window streaked with rain, one is aware of the  

E-print Network

1 Introduction Gazing at a flower garden through a window streaked with rain, one is aware of the properties of two surfaces in one direction, albeit at different depths. In this situation, monocular before being combined for awareness by a process that integrates over about 120 ms. A final experiment

Holcombe, Alex O.

324

Determination of shaped-jet characteristics by double orthogonal synchro streak technique and double x-ray technique  

Microsoft Academic Search

This paper presents a method that allows very accurate measurements for a full characterization of shaped charge jets. A double visualization of the jets is achieved by means of both a modified high speed camera CORDIN in Double Orthogonal Synchro Streak Technique (DOSST) configuration and a classical Double XRays Technique (DXRT). The interests of this method are twofold: Firstly, the

Robert Tosello; Mohamed Mehaddi; Henry Marrot

1995-01-01

325

Two dimensions are not better than one: STREAK and the univariate signal detection model of remember\\/know performance  

Microsoft Academic Search

We evaluated STREAK and the univariate signal detection model of Remember\\/Know (RK) judgments in terms of their ability to fit empirical data and produce psychologically meaningful parameter estimates. Participants studied pairs of words and completed item recognition tests with RK judgments as well as associative recognition tests. Fits to the RK data showed that the univariate model provided a better

Jeffrey J. Starns; Roger Ratcliff

2008-01-01

326

Effects of dietary supplementation with ghee, hydrogenated oil, or olive oil on lipid profile and fatty streak formation in rabbits  

PubMed Central

BACKGROUND Coronary heart disease is the leading cause of mortality worldwide. A high-fat diet, rich in saturated fatty acids and low in polyunsaturated fatty acids, is said to be an important cause of atherosclerosis and cardiovascular diseases. METHODS In this experimental study, 40 male rabbits were randomly assigned to eight groups of five to receive normal diet, hypercholesterolemic diet, normal diet plus ghee, normal diet plus olive oil, normal diet plus hydrogenated oil, hypercholesterolemic diet plus ghee, hypercholesterolemic diet plus olive oil, and hypercholesterolemic diet plus hydrogenated oil. They received rabbit chow for a period of 12 weeks. At the start and end of the study, fasting blood samples were taken from all animals to measure biochemical factors including total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride (TG), fasting blood sugar (FBS), and C-reactive protein (CRP). Moreover, aorta, left and right coronary arteries were dissected at the end of the study to investigate fatty streak formation (FSF). Data was analyzed in SPSS at a significance level of 0.05. RESULTS In rabbits under normal diet, ghee significantly increased TC, LDL, and HDL compared to the beginning (P < 0.01) and also to the other two types of fat (P < 0.05). Moreover, normal diet plus olive oil significantly enhanced FSF in left coronary arteries and aorta compared to normal diet plus ghee. In groups receiving hypercholesterolemic diets, ghee significantly increased HDL and CRP (P < 0.05) and significantly decreased FBS (P < 0.01). The hypecholesterolemic diet plus olive oil significantly increased HDL (P < 0.01). Supplementation of hypecholesterolemic diet with ghee significantly increased HDL and FBS in comparison with hydrogenated oil. Significant increase of FBS was also detected with the use of ghee compared to olive oil. Ghee also significantly reduced FSF in left and right coronary arteries compared to olive oil. FSF in left coronary arteries was significantly lower in the hypecholesterolemic diet plus ghee group compared to the hypecholesterolemic diet plus hydrogenated oil group. CONCLUSION According to the achieved results, future clinical trial studies and investigation of other risk factors such as inflammatory factors are required. PMID:23358722

Hosseini, Mohsen; Asgary, Sedigheh

2012-01-01

327

P552 X-Ray Streak Tube With Removable Photocathode, Improved Spatial Resolution And Temporal Fiducial  

NASA Astrophysics Data System (ADS)

We present here the P552 soft X-ray streak tube which is derived from the P500-P550 X-ray tube from RTC 1. To meet the requirements of X-ray diagnostics in high power laser interaction experiments performed at Centre d' Etudes de Limeil-Valenton some modifications were carried out to allow an easier control of the photocathode and the insertion of an optical fiducial of the laser pulse. We describe the main features of the whole device. This tube associated with a Thomson 2 TSN 505 camera has been used in laser plasma experiments and we present here some results obtained on the PHFBUS laser facility at CEL-V.

de Mascureau, J.; Bourgade, J.-L.; Mens, A.; Sauneif, R.; Rebuffie, J.-C.; Roux, J.-P.

1989-02-01

328

Characterization Of A Large-Format, High-Fidelity, Picosecond, Optical Streak Camera  

NASA Astrophysics Data System (ADS)

We have completed preliminary characterizations of a new 3-grid, large-format, ITT1 streak camera tube operating with about a 2.3-kV extraction voltage. We have found that the best attainable impulse response is 10 ps at low input intensity. However, the impulse response increases to only 30 ps with an increase of nearly three orders of magnitude in input intensity. Further, the spatial resolution remains greater than 5 line pairs/mm at 50% contrast over these three orders of magnitude of input intensity. We have also done preliminary computational modeling of the tube's temporal response as a function of focus voltage, illumina-tion spot size, and wavelength.

Lowry, Mark; Lancaster, Greg; Jander, Don; Grasz, Erna; Simpson, Bob; Lerche, Richard; Rickard, Bryan; Imhoff, C.

1988-02-01

329

Investigation of thin laser-driven flyer plates using streak imaging and stop motion microphotography  

SciTech Connect

The dynamic behavior of laser-accelerator flyers has been studied using high-speed streak imaging in combination with stop motion microphotography. With very thin targets, melting and plasma penetration of the flyer material occur in rapid sequence. The time delay from the onset of motion to flyer breakup increases with flyer thickness and decreasing incident energy. Flyer materials examined include pure aluminum (0.25-2.6 {mu}m thick) and composite targets (0.5-2.0 {mu}m thick) containing an insulating layer of aluminum oxide. While flyer breakup is observed in both types of material, the Al{sub 2}O{sub 3} barrier significantly delays the deleterious effects of deep thermal diffusion.

Frank, A.M. [Lawrence Livermore National Lab., CA (United States); Trott, W.M. [Sandia National Labs., Albuquerque, NM (United States)

1995-09-01

330

Operation and maintenance manual for LEA76-1334 compact streak camera  

SciTech Connect

This manual describes the ultra-fast streak camera which measures photon intensity vs time. The input photon wavelength range is from the near infrared of about 1.2 ..mu..m (longest usable wavelength for the S1 photo cathode) to below 100 eV x-rays (12 nm). The camera is capable of resolving events separated in time by 7 to 10 ps. The window or aperture time is adjustable from a minimum of about 1.6 ns to 50 ns or longer, with a total of 200 resolvable spots during the aperture time. The linear dynamic range of input intensity exceeds 1000 and is nominally about 2500. Included in the approximately 100 pages of the manual are specifications, precautions, operating instructions, theory of operation, checkout procedure, maintenance instructions, and other information.

Thomas, S.W.

1982-09-10

331

Microstructure investigations of streak formation in 6063 aluminum extrusions by optical metallographic techniques.  

PubMed

The present study investigates the effect of the solidification strategy for AA 6063 alloy on the surface appearance of anodized extrusions. The microstructure of the samples was analyzed using both light optical microscopy and scanning electron microscopy. Results show that if heavy segregation occurs from rapid solidification, coarse Mg2Si particles form, thus reducing the potential for precipitation strengthening by the finer ?-Mg2Si developed in the solid state. Differentially-strained regions formed during hot extrusion induce differences in particle size for magnesium silicide (Mg2Si) precipitates. Anodizing generates surface roughness due to Mg2Si particle dissolution and AlFeSi decohesion, which is related to both particle size and deformation. During anodizing, an oxide layer forms on the surface of the extruded products, which can lead to streak formation, usually a subject of rejection due to unacceptable heterogeneous reflectivity. PMID:23481588

Vander Voort, George; Suárez-Peña, Beatriz; Asensio-Lozano, Juan

2013-04-01

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

Solid-state ultrafast all-optical streak camera enabling high-dynamic-range picosecond recording.  

PubMed

We demonstrate an ultrafast optical recording system based on a novel optical beam deflection technique. An optical pump temporarily creates an array of prisms that deflect an optical signal beam within a GaAs/AlGaAs planar waveguide. The fabricated device yielded, to our knowledge, the fastest sustained optical deflection reported to date and was used to create spatial representations of ultrafast temporal waveforms. A conventional camera was then used to record single-shot waveforms with a 2.5 ps resolution over a 50 ps record with a dynamic range in excess of 3000:1. Through further development, this all-optical streak camera could provide insight into previously unmeasurable phenomena in many fields. PMID:20436579

Sarantos, Chris H; Heebner, John E

2010-05-01

334

Time-resolved spectra of single-bubble sonoluminescence in sulfuric acid with a streak camera.  

PubMed

The time-resolved spectra of single-bubble sonoluminescence (SBSL) in sulfuric acid have been observed with a streak camera after a spectrograph. The spectral center evolves from infrared to ultraviolet gradually within a SBSL duration, which corresponds to an increase of temperature. The peak temperature within one sonoluminescence (SL) duration is 5-9 times higher than the average temperature based on the average spectrum in our experiment. Furthermore, the ratio of the peak temperature to average temperature increases with the increase of driving pressure. The SBSL flash dies out after a dramatic heating-up, and there is no cooling procedure observed at the time resolution of 110 SL duration, which is incompatible with the radius-related adiabatic heating model as the mechanism of SBSL. PMID:18851095

Chen, Weizhong; Huang, Wei; Liang, Yue; Gao, Xianxian; Cui, Weicheng

2008-09-01

335

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. PMID:19701191

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

2009-01-01

336

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 PMID:2472960

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

1989-01-01

337

Electron streaking and dissociation in laser-assisted photoionization of molecular hydrogen  

NASA Astrophysics Data System (ADS)

We report ab initio calculations on laser-assisted photoionization of the hydrogen molecule in the energy region where autoionization from doubly excited states is expected to occur. We use a UV-pump/IR-probe scheme in which an isolated attosecond UV pulse and a 750 nm IR pulse are combined. The IR pulse has a relatively low intensity (1012 W cm-2), which allows us to perform a perturbative analysis of the calculated ionization probabilities differential in either electron or nuclear energy or both. We show that, for dissociative ionization, the electron energy distributions as a function of time delay exhibit unusual streaking patterns that are due to the presence of autoionizing states. These patterns significantly differ from the standard ones observed in direct single ionization of atoms and molecules. We also show that, by using such a pump-probe scheme, one can suppress autoionization from doubly excited states for time delays between 0 and 4 fs.

Palacios, Alicia; González-Castrillo, Alberto; Martín, Fernando

2014-06-01

338

Streaked x-ray spectrometer having a discrete selection of Bragg geometries for Omegaa)  

NASA Astrophysics Data System (ADS)

The streaked x-ray spectrometer (SXS) is used with streak cameras [D. H. Kalantar, P. M. Bell, R. L. Costa, B. A. Hammel, O. L. Landen, T. J. Orzechowski, J. D. Hares, and A. K. L. Dymoke-Bradshaw, in 22nd International Congress on High-Speed Photography and Photonics, edited by D. L. Paisley and A. M. Frank (SPIE, Bellingham, WA, 1997), Vol. 2869, p. 680] positioned with a ten-inch manipulator on OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], 10.1016/S0030-4018(96)00325-2 and OMEGA EP [L. J. Waxer et al., Presented at CLEO/QELS 2008, San Jose, CA, 4-9 May 2008 (Paper JThB1)] for time-resolved, x-ray spectroscopy of laser-produced plasmas in the 1.4- to 20-keV photon-energy range. These experiments require measuring a portion of this photon-energy range to monitor a particular emission or absorption feature of interest. The SXS relies on a pinned mechanical reference system to create a discrete set of Bragg reflection geometries for a variety of crystals. A wide selection of spectral windows is achieved accurately and efficiently using this technique. It replaces the previous spectrometer designs that had a continuous Bragg angle adjustment and required a tedious alignment calibration procedure. The number of spectral windows needed for the SXS was determined by studying the spectral ranges selected by OMEGA users over the last decade. These selections are easily configured in the SXS using one of the 25 discrete Bragg reflection geometries and one of the six types of Bragg crystals, including two curved crystals.

Millecchia, M.; Regan, S. P.; Bahr, R. E.; Romanofsky, M.; Sorce, C.

2012-10-01

339

A characteristic symptom of calcium deficiency in maize and sorghum  

Microsoft Academic Search

The appearance of the so?called “bull?whip”; in leaves of maize plants has been recognized as a calcium deficiency symptom. Another characteristic symptom, in which the leaf edges of maize plants become serrated and curl, is often observed when there is a low calcium supply, especially in solution cultures. The effects of several factors on this symptom were investigated using solution

T. Kawaski; M. Moritsugu

1979-01-01

340

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

341

Maize for production of recombinant proteins: fundamental and practical considerations  

Microsoft Academic Search

The present work addresses fundamental and practical considerations of using maize for production of recombinant proteins. Maize expressing the B subunit of the heat labile enterotoxin (LT-B) of Escherichia coli was used as a model crop. To address the fundamental aspects of the system, the role of LT-B and its native signal peptide (BSP) in plant cells was investigated using

Lorena Beatriz Moeller

2009-01-01

342

Natural Gas Flaring Affects Microclimate and Reduces Maize  

Microsoft Academic Search

It is a common saying by farmers in the oil producing area of Niger Delta that gas flaring is a major reason for low maize yield. This paper reports the impact of natural gas flaring on microclimate and maize yield in the Niger Delta, using Ovade flare site as a case study. Experimental sites were located at 500 m, 1

P. A. O. ODJUGO; E. J. OSEMWENKHAE

343

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

344

Original article Foliar senescence in maize plants grown  

E-print Network

Original article Foliar senescence in maize plants grown under different water regimes Arturo) Abstract - The leaf ontogeny of potted maize plants subjected to severe water stress was carried out and water-stressed plants received 100 and 50 % of the water evapotranspired, respectively. After 30 days

Paris-Sud XI, Université de

345

RESPONSE OF MAIZE AND WHEAT TO SULFUR DIOXIDE  

EPA Science Inventory

Four hybrids of maize and seven cultivars of wheat were exposed to relatively low concentrations of sulfur dioxide (0.1 to 0.6 ppm) for up to 100 hours. Maize was found to be tolerant to sulfur dioxide and only minor differences were observed in dry mass, foliar injury, and total...

346

Scientific Correspondence Cleavage of Bipartite Substrates by Rice and Maize  

E-print Network

Scientific Correspondence Cleavage of Bipartite Substrates by Rice and Maize Ribonuclease P III, George Thomas, and Venkat Gopalan* Departments of Biochemistry (M.L.S.R., D.K.P., J.F.R., V with rice (Oryza sativa) and maize (Zea mays) nuclear RNase P. By successively employing ion

Gopalan, Venkat

347

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

348

Assessment of wind-induced environmental lodging stress for maize based on GIS  

Microsoft Academic Search

Lodging in maize is one of the major problems in maize production worldwide. This study is to assess environmental lodging stress for maize based on probability analysis of extreme wind event in maize vegetative stage. A total of 687 growing counties in Huang-Huai-Hai Plain, China were chosen as study area. There were 148 meteorology stations with daily extreme wind speed

Chunqiao Mi; Xiaodong Zhang; Shaoming Li; Jianyu Yang; Dehai Zhu; Yang Yang; Zhe Liu

2011-01-01

349

BIOCHEMICAL CHANGES IN MAIZE SEEDLINGS EXPOSED TO DROUGHT STRESS CONDITIONS AT DIFFERENT NITROGEN LEVELS  

Microsoft Academic Search

Normally, under field conditions, maize seedlings are often exposed to early water stress. The objective of the present study was to evaluate the biochemical changes in maize seedlings exposed to drought stress at different nitrogen levels. Maize (Zea mays L.) hybrid SC 704 plants were grown in 18 kg pots containing the same soil from the field that maize is

Ali Ahmadi; Yahya Emam; Mohammad Pessarakli

2010-01-01

350

Intestinal and Peripheral Immune Response to MON810 Maize Ingestion in Weaning and Old Mice  

Microsoft Academic Search

This study evaluated the gut and peripheral immune response to genetically modified (GM) maize in mice in vulnerable conditions. Weaning and old mice were fed a diet containing MON810 or its parental control maize or a pellet diet containing a GM-free maize for 30 and 90 days. The immunophenotype of intestinal intraepithelial, spleen, and blood lymphocytes of control maize fed

Alberto Finamore; Marianna Roselli; Serena Britti; Giovanni Monastra; Roberto Ambra; Aida Turrini; Elena Mengheri

2008-01-01

351

Diversity in global maize germplasm: characterization and utilization.  

PubMed

Maize (Zea mays L.) is not only of worldwide importance as a food, feed and as a source of diverse industrially important products, but is also a model genetic organism with immense genetic diversity. Although it was first domesticated in Mexico, maize landraces are widely found across the continents. Several studies in Mexico and other countries highlighted the genetic variability in the maize germplasm. Applications of molecular markers, particularly in the last two decades, have led to new insights into the patterns of genetic diversity in maize globally, including landraces as well as wild relatives (especially teosintes) in Latin America, helping in tracking the migration routes of maize from the centers of origin, and understanding the fate of genetic diversity during maize domestication. The genome sequencing of B73 (a highly popular US Corn Belt inbred) and Palomero (a popcorn landrace in Mexico) in the recent years are important landmarks in maize research, with significant implications to our understanding of the maize genome organization and evolution. Next-generation sequencing and high-throughput genotyping platforms promise to further revolutionize our understanding of genetic diversity and for designing strategies to utilize the genomic information for maize improvement. However, the major limiting factor to exploit the genetic diversity in crops like maize is no longer genotyping, but high-throughput and precision phenotyping. There is an urgent need to establish a global phenotyping network for comprehensive and efficient characterization of maize germplasm for an array of target traits, particularly for biotic and abiotic stress tolerance and nutritional quality. 'Seeds of Discovery' (SeeD), a novel initiative by CIMMYT with financial support from the Mexican Government for generating international public goods, has initiated intensive exploration of phenotypic and molecular diversity of maize germplasm conserved in the CIMMYT Gene Bank; this is expected to aid in effective identification and use of novel alleles and haplotypes for maize improvement. Multi-institutional efforts are required at the global level to systematically explore the maize germplasm to diversify the genetic base of elite breeding materials, create novel varieties and counter the effects of global climate changes. PMID:23107920

Prasanna, B M

2012-11-01

352

Ancient maize from Chacoan great houses: Where was it grown?  

USGS Publications Warehouse

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 Mountains. The youngest maize came from the San Juan or Animas river flood-plains 90 km to the north. This article demonstrates that maize, a dietary staple of southwestern Native Americans, was transported over considerable distances in pre-Columbian times, a finding fundamental to understanding the organization of pre-Columbian southwestern societies. In addition, this article provides support for the hypothesis that major construction events in Chaco Canyon were made possible because maize was brought in to support extra-local labor forces.

Benson, L.; Cordell, L.; Vincent, K.; Taylor, H.; Stein, J.; Farmer, G.L.; Futa, K.

2003-01-01

353

Tissue localization of maize acetylcholinesterase associated with heat tolerance in plants.  

PubMed

Our recent study reported that maize acetylcholinesterase (AChE) activity in the coleoptile node is enhanced through a post-translational modification response to heat stress and transgenic plants overexpressing maize AChE gene had an elevated heat tolerance, which strongly suggests that maize AChE plays a positive, important role in maize heat tolerance. Here we present (1) maize AChE activity in the mesocotyl also enhances during heat stress and (2) maize AChE mainly localizes in vascular bundles including endodermis and epidermis in coleoptile nodes and mesocotyls of maize seedlings. PMID:22476469

Yamamoto, Kosuke; Momonoki, Yoshie S

2012-03-01

354

Lipid-lowering effect of maize-based traditional Mexican food on a metabolic syndrome model in rats  

PubMed Central

Background Maize-based food is typical in Mexico and other Mesoamerican countries. Used for millennia, they have recently been replaced by modern food that is associated with an increase in the prevalence of non-communicable chronic diseases. This study was carried out in order to evaluate the effects of traditional food on lipid profiles. Methods Metabolic syndrome was induced in animals given a 30% sucrose solution. The animals were given maize tortillas (n=5) and maize pozol (n=5), traditional Mexican food items. A control group was given a 30% sucrose solution in the laboratory diet (n=5) and a witness group was given plain water and pellets. Triglycerides, cholesterol and glucose in tail blood were recorded each month between weeks 12 to 24. Blood was obtained from the cardiac cavity on week 28 and triglycerides, total cholesterol, LDL, HDL, C-reactive protein, alanine amino transferase, glucose and glycated hemoglobin were recorded. Results The animals provided with supplementary traditional food presented a lower increase in triglycerides up to week 24 (p<0.001). Data recorded on week 28 showed lower values of LDL (p<0.05), a lower percentage of glycated hemoglobin when maize tortillas were provided (p<0.01) and lower values of alanine amino transferase when both food items were provided (p<0.01). Conclusions Providing traditional Mexican food generated a protective effect against the intake of a 30% sucrose solution over a long period. PMID:23497051

2013-01-01

355

Tripsacum-Maize Interaction: A Novel Cytogenetic System  

PubMed Central

The genera Zea and Tripsacum cross readily when they are not isolated by gametophytic barriers, and it has been postulated that intergeneric introgression played a role in the evolution of maize. The basic x = 9 Tripsacum and x = 10 Zea genomes have little cytological affinity for each other in hybrids that combine 10 Zea with 18 Tripsacum chromosomes. However, one to four Tripsacum chromosomes sometimes associate with Zea chromosomes in hybrids between Z. mays (2n = 20) and T. dactyloides (2n = 72). These hybrids with 10 Zea and 36 Tripsacum chromosomes frequently produce functional female gametes with 36 Tripsacum chromosomes only. When they are pollinated with maize, their offspring again have 36 Tripsacum and 10 maize chromosomes, but the Tripsacum genome is contaminated with maize genetic material. In these individuals, intergenome pairing is the rule, and when they are pollinated with maize, their offspring have 36 Tripsacum and 10, 12, 14, 16, 18, or 20 Zea chromosomes. Plants with 36 Tripsacum and 20 Zea chromosomes behave cytologically as alloploids, although the Tripsacum genome is contimated with maize, and one basic maize genome is contaminated with with Tripsacum genetic material. When they are pollinated with maize, offspring with 18 Tripsacum and 20 Zea chromosome are obtained. Further successive backcrosses with maize selectively eliminate Tripsacum chromosomes, and eventually plants with 2n = 20 Zea chromosomes are recovered. Many of these maize plants are highly "tripsacoid." Strong gametophytic selection for essentially pure Zea gametes, however, eliminates all obvious traces of Tripsacum morphology within a relatively few generations. PMID:17248666

de Wet, J. M. J.; Harlan, J. R.

1974-01-01

356

Genetic Analyses with Oat-Maize Addition and Radiation Hybrid Lines  

Microsoft Academic Search

Oat-maize addition lines, with individual maize (Zea mays L.) chromosomes added to the oat (Avena sativa L.) genome via wide hybridization and embryo rescue, simplify the maize genome by 10-fold. Radiation hybrids, derived through\\u000a gamma irradiation of monosomic addition lines, have less than a complete maize chromosome in an oat genomic background. Maize\\u000a genes and gene families can be readily

Ronald L. Phillips; Howard W. Rines

357

HETEROSIS AND COMBINING ABILITY AMONG CIMMYT'S MID-ALTITUDE EARLY TO INTERMEDIATE MATURING MAIZE (ZEA MAYS L.) POPULATIONS  

Microsoft Academic Search

Maize is an important food crop in sub-Sa- haran Africa. There is an increasing demand for early ma- turing maize cultivars even though long-season maize cul- tivars yield more than early maturing cultivars under favourable conditions. This is because vast areas of maize are routinely affected by drought and low N fertility and early maturing maize cultivars offer more flexibility

B. S. Vivek; J. Crossa; G. Alvarado

2009-01-01

358

Recent, extensive, and preferential insertion of members of the miniature inverted-repeat transposable element family Heartbreaker into genic regions of maize  

PubMed Central

A 314-bp DNA element called Heartbreaker-hm1 (Hbr-hm1) was previously identified in the 3? untranslated region of a mutant allele of the maize disease resistance gene HM1. This element has structural features of miniature inverted-repeat transposable elements (MITEs) and is a member of a large family of approximately 4,000 copies in the maize genome. Unlike previously described MITEs, most members of the Hbr family display over 90% sequence identity. This, coupled with the insertion of an Hbr element into an allele of the HM1 gene, suggested that this family might have spread recently throughout the genome. Consistent with this view is the finding that Hbr insertion sites are remarkably polymorphic. Ten of ten loci containing Hbr elements were found to be polymorphic for the presence or absence of Hbr among a collection of maize inbred lines and teosinte strains. Despite the fact that over 80% of the maize genome contain moderate to highly repetitive DNA, we find that randomly chosen Hbr elements are predominantly in single or low copy regions. Furthermore, when used to query both the public and private databases of plant genes, over 50% of the sequences flanking these Hbr elements resulted in significant “hits.” Taken together, these data indicate that the presence or absence of Hbr elements is a significant contributory factor to the high level of polymorphism associated with maize genic regions. PMID:10655501

Zhang, Qiang; Arbuckle, John; Wessler, Susan R.

2000-01-01

359

Structure and expression of maize phytochrome family homeologs.  

PubMed Central

To begin the study of phytochrome signaling in maize, we have cloned and characterized the phytochrome gene family from the inbred B73. Through DNA gel blot analysis of maize genomic DNA and BAC library screens, we show that the PhyA, PhyB, and PhyC genes are each duplicated once in the genome of maize. Each gene pair was positioned to homeologous regions of the genome using recombinant inbred mapping populations. These results strongly suggest that the duplication of the phytochrome gene family in maize arose as a consequence of an ancient tetraploidization in the maize ancestral lineage. Furthermore, sequencing of Phy genes directly from BAC clones indicates that there are six functional phytochrome genes in maize. Through Northern gel blot analysis and a semiquantitative reverse transcriptase polymerase chain reaction assay, we determined that all six phytochrome genes are transcribed in several seedling tissues. However, expression from PhyA1, PhyB1, and PhyC1 predominate in all seedling tissues examined. Dark-grown seedlings express higher levels of PhyA and PhyB than do light-grown plants but PhyC genes are expressed at similar levels under light and dark growth conditions. These results are discussed in relation to phytochrome gene regulation in model eudicots and monocots and in light of current genome sequencing efforts in maize. PMID:15280251

Sheehan, Moira J; Farmer, Phyllis R; Brutnell, Thomas P

2004-01-01

360

Biofuel, land and water: maize, switchgrass or Miscanthus?  

NASA Astrophysics Data System (ADS)

The productive cellulosic crops switchgrass and Miscanthus are considered as viable biofuel sources. To meet the 2022 national biofuel target mandate, actions must be taken, e.g., maize cultivation must be intensified and expanded, and other biofuel crops (switchgrass and Miscanthus) must be cultivated. This raises questions on the use efficiencies of land and water; to date, the demand on these resources to meet the national biofuel target has rarely been analyzed. Here, we present a data-model assimilation analysis, assuming that maize, switchgrass and Miscanthus will be grown on currently available croplands in the US. Model simulations suggest that maize can produce 3.0-5.4 kiloliters (kl) of ethanol for every hectare of land, depending on the feedstock to ethanol conversion efficiency; Miscanthus has more than twice the biofuel production capacity relative to maize, and switchgrass is the least productive of the three potential sources of ethanol. To meet the biofuel target, about 26.5 million hectares of land and over 90 km3 of water (of evapotranspiration) are needed if maize grain alone is used. If Miscanthus was substituted for maize, the process would save half of the land and one third of the water. With more advanced biofuel conversion technology for Miscanthus, only nine million hectares of land and 45 km3 of water would probably meet the national target. Miscanthus could be a good alternative biofuel crop to maize due to its significantly lower demand for land and water on a per unit of ethanol basis.

Zhuang, Qianlai; Qin, Zhangcai; Chen, Min

2013-03-01

361

Transcriptional responses of maize seedling root to phosphorus starvation.  

PubMed

Maize (Zea mays) is the most widely cultivated crop around the world, however, it is commonly affected by phosphate (Pi) deficiency and the underlying molecular basis of responses mechanism is still unknown. In this study, the transcriptional response of maize roots to Pi starvation at 3 days after the onset of Pi deprivation was assessed. The investigation revealed a total of 283 Pi-responsive genes, of which 199 and 84 genes were found to be either up- or down-regulated respectively, by 2-fold or more. Pi-responsive genes were found to be involved in sugar and nitrogen metabolic pathways, ion transport, signal transduction, transcriptional regulation, and other processes related to growth and development. In addition, the expression patterns of maize inorganic phosphorus transporters, acid phosphatase, phytase, 2-deoxymugineic acid synthase1, POD and MYB transcription factor were validated in 178 roots response to low phosphorus stress. of which, two genes encoding phytase and acid phosphatase were significantly induced by Pi deficiency and may play a pivotal role in the process of absorption and re-utilization of Pi in Maize. These results not only enhance our knowledge about molecular processes associated with Pi deficiency, but also facilitate the identification of key molecular determinants for improving Pi use in maize. Moreover, this work sets a framework to produce Pi-specific maize microarrays to study the changes in global gene expression between Pi-efficient and Pi-inefficient maize genotypes. PMID:23670044

Lin, Hai-Jian; Gao, Jian; Zhang, Zhi-Ming; Shen, Ya-Ou; Lan, Hai; Liu, Li; Xiang, Kui; Zhao, Maojun; Zhou, Shufeng; Zhang, Yong-Zhong; Gao, Shi-Bin; Pan, Guang-Tang

2013-09-01

362

Unconventional P-35S sequence identified in genetically modified maize.  

PubMed

The Cauliflower Mosaic Virus 35S promoter sequence, CaMV P-35S, is one of several commonly used genetic targets to detect genetically modified maize and is found in most GMOs. In this research we report the finding of an alternative P-35S sequence and its incidence in GM maize marketed in Jordan. The primer pair normally used to amplify a 123 bp DNA fragment of the CaMV P-35S promoter in GMOs also amplified a previously undetected alternative sequence of CaMV P-35S in GM maize samples which we term V3. The amplified V3 sequence comprises 386 base pairs and was not found in the standard wild-type maize, MON810 and MON 863 GM maize. The identified GM maize samples carrying the V3 sequence were found free of CaMV when compared with CaMV infected brown mustard sample. The data of sequence alignment analysis of the V3 genetic element showed 90% similarity with the matching P-35S sequence of the cauliflower mosaic virus isolate CabbB-JI and 99% similarity with matching P-35S sequences found in several binary plant vectors, of which the binary vector locus JQ693018 is one example. The current study showed an increase of 44% in the incidence of the identified 386 bp sequence in GM maize sold in Jordan's markets during the period 2009 and 2012. PMID:24495911

Al-Hmoud, Nisreen; Al-Husseini, Nawar; Ibrahim-Alobaide, Mohammed A; Kübler, Eric; Farfoura, Mahmoud; Alobydi, Hytham; Al-Rousan, Hiyam

2014-01-01

363

From Many, One: Genetic Control of Prolificacy during Maize Domestication  

PubMed Central

A reduction in number and an increase in size of inflorescences is a common aspect of plant domestication. When maize was domesticated from teosinte, the number and arrangement of ears changed dramatically. Teosinte has long lateral branches that bear multiple small ears at their nodes and tassels at their tips. Maize has much shorter lateral branches that are tipped by a single large ear with no additional ears at the branch nodes. To investigate the genetic basis of this difference in prolificacy (the number of ears on a plant), we performed a genome-wide QTL scan. A large effect QTL for prolificacy (prol1.1) was detected on the short arm of chromosome 1 in a location that has previously been shown to influence multiple domestication traits. We fine-mapped prol1.1 to a 2.7 kb “causative region” upstream of the grassy tillers1 (gt1) gene, which encodes a homeodomain leucine zipper transcription factor. Tissue in situ hybridizations reveal that the maize allele of prol1.1 is associated with up-regulation of gt1 expression in the nodal plexus. Given that maize does not initiate secondary ear buds, the expression of gt1 in the nodal plexus in maize may suppress their initiation. Population genetic analyses indicate positive selection on the maize allele of prol1.1, causing a partial sweep that fixed the maize allele throughout most of domesticated maize. This work shows how a subtle cis-regulatory change in tissue specific gene expression altered plant architecture in a way that improved the harvestability of maize. PMID:23825971

Wills, David M.; Whipple, Clinton J.; Takuno, Shohei; Kursel, Lisa E.; Shannon, Laura M.; Ross-Ibarra, Jeffrey; Doebley, John F.

2013-01-01

364

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

365

Effect of volunteers on maize gene flow.  

PubMed

Regulatory approvals for deliberate release of GM maize events into the environment have lead to real situations of coexistence between GM and non-GM, with some fields being cultivated with GM and conventional varieties in successive seasons. Given the common presence of volunteer plants in maize fields in temperate areas, we investigated the real impact of GM volunteers on the yield of 12 non-GM agricultural fields. Volunteer density varied from residual to around 10% of plants in the field and was largely reduced using certain cultural practices. Plant vigour was low, they rarely had cobs and produced pollen that cross-fertilized neighbour plants only at low--but variable--levels. In the worst-case scenario, the estimated content of GMO was 0.16%. The influence of GM volunteers was not enough to reach the 0.9% adventitious GM threshold but it could potentially contribute to adventitious GM levels, especially at high initial densities (i.e. above 1,000 volunteers/ha). PMID:19225900

Palaudelmàs, Montserrat; Peñas, Gisela; Melé, Enric; Serra, Joan; Salvia, Jordi; Pla, Maria; Nadal, Anna; Messeguer, Joaquima

2009-08-01

366

Maize SUT1 functions in phloem loading  

PubMed Central

The functions of dicot sucrose transporters (SUTs) in apoplastic phloem loading of sucrose are well established; however, whether SUTs similarly function in monocots was unresolved. To address this question, we recently provided genetic evidence that ZmSUT1 from maize (Zea mays) is required for efficient phloem loading. sut1-m1 mutant plants hyperaccumulate carbohydrates in leaves, are defective in loading sucrose into the phloem, and have altered biomass partitioning. Presumably due to the hyperaccumulation of soluble sugars in leaves, mutations in ZmSUT1 lead to downregulation of chlorophyll accumulation, photosynthesis and stomatal conductance. However, because we had identified only a single mutant allele, we were not able to exclude the possibility that the mutant phenotypes were instead caused by a closely linked mutation. Based on a novel aspect of the sut1 mutant phenotype, secretion of a concentrated sugar solution from leaf hydathodes, we identified an additional mutant allele, sut1-m4. This confirms that the mutation of SUT1 is responsible for the impairment in phloem loading. In addition, the sut1-m4 mutant does not accumulate transcripts, supporting the findings reported previously that the original mutant allele is also a null mutation. Collectively, these data demonstrate that ZmSUT1 functions to phloem load sucrose in maize leaves. PMID:20404497

Slewinski, Thomas L; Garg, Anshu; Johal, Gurmukh S

2010-01-01

367

Adaptation of US maize to temperature variations  

NASA Astrophysics Data System (ADS)

High temperatures are associated with reduced crop yields, and predictions for future warming have raised concerns regarding future productivity and food security. However, the extent to which adaptation can mitigate such heat-related losses remains unclear. Here we empirically demonstrate how maize is locally adapted to hot temperatures across US counties. Using this spatial adaptation as a surrogate for future adaptation, we find that losses to average US maize yields from a 2°C warming would be reduced from 14% to only 6% and that loss in net production is wholly averted. This result does not account for possible changes in temperature variability or water resources, nor does it account for all possible forms of adaptation, but it does show that adaptation is of first-order importance for predicting future changes in yield. Further research should be undertaken regarding the ability to adapt to a changing climate, including analysis of other crops and regions, the application of more sophisticated models of crop development, and field trials employing artificially increased temperature.

Butler, Ethan E.; Huybers, Peter

2013-01-01

368

The transcriptome landscape of early maize meiosis  

PubMed Central

Background A major step in the higher plant life cycle is the decision to leave the mitotic cell cycle and begin the progression through the meiotic cell cycle that leads to the formation of gametes. The molecular mechanisms that regulate this transition and early meiosis remain largely unknown. To gain insight into gene expression features during the initiation of meiotic recombination, we profiled early prophase I meiocytes from maize (Zea mays) using capillary collection to isolate meiocytes, followed by RNA-seq. Results We detected ~2,000 genes as preferentially expressed during early meiotic prophase, most of them uncharacterized. Functional analysis uncovered the importance of several cellular processes in early meiosis. Processes significantly enriched in isolated meiocytes included proteolysis, protein targeting, chromatin modification and the regulation of redox homeostasis. The most significantly up-regulated processes in meiocytes were processes involved in carbohydrate metabolism. Consistent with this, many mitochondrial genes were up-regulated in meiocytes, including nuclear- and mitochondrial-encoded genes. The data were validated with real-time PCR and in situ hybridization and also used to generate a candidate maize homologue list of known meiotic genes from Arabidopsis. Conclusions Taken together, we present a high-resolution analysis of the transcriptome landscape in early meiosis of an important crop plant, providing support for choosing genes for detailed characterization of recombination initiation and regulation of early meiosis. Our data also reveal an important connection between meiotic processes and altered/increased energy production. PMID:24885405

2014-01-01

369

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

370

Observation of asymmetrically imploded core plasmas with a two-dimensional sampling image x-ray streak camera.  

PubMed

A shell target with a cone for guiding the heating beam has been proposed for the fast ignition scheme. Implosion of such target is no longer symmetric because of the cone. A fast two-dimensional x-ray imaging technique, two-dimensional (2D) sampling image x-ray streak camera was applied for the first time to observation of the dynamics of implosion and core plasma. X-ray emission image of the plasma was sampled with two-dimensionally distributed image sampling points, streaked with the tube, and the recorded signals were reconstructed as sequential 2D frame images. Shape and movement of the core plasma were clearly observed. PMID:19044575

Shiraga, Hiroyuki; Lee, Myongdok; Mahigashi, Norimitsu; Fujioka, Shinsuke; Azechi, Hiroshi

2008-10-01

371

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

372

Eriophyid mite transmission and host range of a Brome streak mosaic virus isolate derived from a full-length cDNA clone  

Microsoft Academic Search

Summary  Biolistic inoculation of Hordeum vulgare and Phalaris paradoxa with a brome streak mosaic virus (BrSMV) full-length cDNA clone (pBrSMVfl) led to typical leaf streak symptoms in both plant species. Infected H. vulgare plants showed a more stunted growth 8 weeks after symptom appearance compared to BrSMV wild type (BrSMVwt)-infected plants. Moreover, a slightly higher virus titer was observed in BrSMVfl-inoculated

D. Stephan; I. Moeller; A. Skoracka; F. Ehrig; E. Maiss

2008-01-01

373

Functionality Enhancement of Composite Cassava Flour in the Production of Maize Tuwo (A Non-fermented Maize-Based Food Dumpling)  

Microsoft Academic Search

The study was focused on the evaluation of textural and sensory quality enhancing functionality of cassava flour in the production\\u000a of maize tuwo (a non-fermented maize-based food dumpling). The cassava flour was added to maize flour at the level of 5%, 10%, 15%, 20%,\\u000a 25% and 30% (w\\/w), respectively. The bulk density and water holding capacity of maize\\/cassava flour mixes

Mathew Kolawole Bolade; Isaac Adebayo Adeyemi

374

Sequence analysis of shorter than genome length episomal Banana streak OL virus like sequences isolated from banana in India.  

PubMed

Electron microscopy and sequencing of reverse transcriptase and ribonuclease H (RT/RNase H) region of Badnavirus genome from two banana cultivars: Poovan (triploid: AAB) and Safed velchi (diploid: AB), exhibiting leaf streak symptoms, confirmed the association of Banana streak OL virus (BSOLV). As per ICTV species demarcation threshold of 80 % identity in RT/RNase H region, both the isolates were identified as BSOLV. Rolling circle and end-to-end amplification showed the association of two short episomal BSOLV variants: BSOLV-IN1 and BSOLV-IN2 from Poovan and Safed velchi banana, respectively. The genome sizes of both isolates were 6,950 nucleotides long, but shorter than the typical BSOLV genome of 7,389 bp. Open reading frames (ORFs) 1 and 2 of shorter BSOLV isolates shared almost complete nucleotide identity (>99 %) to that of BSOLV. However, the ORF 3 (5,130 bp) and intergenic region (IGR), 886 bp, showed deletions compared with ORF 3 (5,499 bp) and IGR (956 bp) of BSOLV. In phylogenetic analysis for ORF 3 polyprotein, both the isolates clustered with BSOLV, Banana streak CA virus (BSCAV), and Sugarcane bacilliform GA virus (SCBGAV). Identical ORF 1, ORF 2, and the presence of all the conserved domains in short ORF 3 and promoter elements in IGR indicated that these isolates represent replicationally competent shorter variants of BSOLV. These two shorter-than-BSOLV genome sequences and two other identical banana streak virus sequences in GenBank (BSV-TRY; DQ859899 and BSV-GD; DQ451009) might have evolved due to error-prone reverse transcription and splicing or excision from the integrated sequences by homologous recombination in natural banana hybrids under field conditions. PMID:24101342

Baranwal, Virendra K; Sharma, Susheel K; Khurana, Deepti; Verma, Raj

2014-02-01

375

Lunar-synchronized reproductive activity in the pencil-streaked rabbitfish Siganus doliatus in the Chuuk Lagoon, Micronesia  

Microsoft Academic Search

The annual reproductive and the lunar-related spawning cycles of the pencil-streaked rabbitfish Siganus doliatus collected from Chuuk Lagoon, Federated States of Micronesia, were examined histologically. Monthly collection of this species\\u000a revealed that ovaries with developing oocytes containing yolk were observed from February to May and in August and September.\\u000a Weekly collection of the fish showed that ovarian development and spawning

Yong Ju Park; Akihiro Takemura; Young Don Lee

2006-01-01

376

4D display of the outflow track of embryonic-chick hearts (HH 14-19) using a high speed streak mode OCT  

NASA Astrophysics Data System (ADS)

Congenital Heart Disease (CHD) is the most common congenital malformation in newborns in the US. Although knowledge of CHD is limited, altered hemodynamic conditions are suspected as the factor that stimulates cardiovascular cell response, resulting in the heart morphology remodeling that ultimately causes CHDs. Therefore, one of recent efforts in CHD study is to develop high-speed imaging tools to correlate the rapidly changing hemodynamic condition and the morphological adaptations of an embryonic heart in vivo. We have developed a high-speed streak mode OCT that works at the center wavelength of 830 nm and is capable of providing images (292x220 ?m2) of the outflow tract of an embryonic chick heart at the rate of 1000 Hz. The modality can provide a voxel resolution in the range of 10 ?m3, and the spectral resolution allows a depth range of 1.63 mm. In the study reported here, each of the 4D images of an outflow tract was recorded for 2 seconds. The recording was conducted every 2 hours (HH17 to HH18), 3 hours (HH14 to HH17), and 4 hours (HH18 to HH19). Because of the fast scan speed, there is no need for postacquisition processing such as use of gating techniques to provide a fine 3D structure. In addition, more details of the outflow tract are preserved in the recorded images. The 4D images can be used in the future to determine the role of blood flow in CHD development.

Ma, Siyu; Wang, Rui; Goodwin, Richard L.; Markwald, Roger R.; Borg, Thomas K.; Runyan, Raymond B.; Gao, Zhi

2013-02-01

377

Review article: Quality protein maize (QPM): Genetic manipulation for the nutritional fortification of maize  

Microsoft Academic Search

Cereals are the only source of nutrition for one-third of the world's population especially in developing and underdeveloped nations of Sub-Saharan Africa and South-east Asia. The three major cereals, rice, wheat and maize constitute about 85% of total global cereals production amounting to about 200 million tonnes of protein harvest annually at an average of 10% protein content, out of

P. A. Sofi; Shafiq A. Wani; Shabir H. Wani

378

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

SciTech Connect

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 {angstrom} resolution. These crystals belonged to space group P4{sub 3}2{sub 1}2, with two molecules in the asymmetric unit and unit-cell parameters a = b = 170, c = 211 {angstrom}, {alpha} = {beta} = {gamma} = 90{sup o}.

Rangarajan, Erumbi S.; Izard, Tina (Scripps)

2012-06-28

379

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

380

Absence of P-selectin delays fatty streak formation in mice.  

PubMed Central

P-selectin is expressed on activated endothelium and platelets where it can bind monocytes, neutrophils, stimulated T cells, and platelets. Because recruitment of these cells is critical for atherosclerotic lesion development, we examined whether P-selectin might play a role in atherosclerosis. We intercrossed P-selectin-deficient mice with mice lacking the low density lipoprotein receptor (LDLR) because these mice readily develop atherosclerotic lesions on diets rich in saturated fat and cholesterol. The atherogenic diet stimulated leukocyte rolling in the mesenteric venules of LDLR-deficient mice, and the increase in adhesiveness of the vessels was P-selectin-dependent. Most likely due to the reduced leukocyte interaction with the vessel wall, P-selectin-deficient mice on diet for 8-20 wk formed significantly smaller fatty streaks in the cusp region of the aortae than did P-selectin-positive mice. This difference was more prominent in males. At 37 wk on diet, the lesions in the LDLR-deficient animals progressed to the fibrous plaque stage and were distributed throughout the entire aorta; their size or distribution was no longer dependent on P-selectin. Our results show that P-selectin-mediated adhesion is an important factor in the development of early atherosclerotic lesions, and that adhesion molecules such as P-selectin are involved in the complex process of atherosclerosis. PMID:9062362

Johnson, R C; Chapman, S M; Dong, Z M; Ordovas, J M; Mayadas, T N; Herz, J; Hynes, R O; Schaefer, E J; Wagner, D D

1997-01-01

381

Urodeles remove mesoderm from the superficial layer by subduction through a bilateral primitive streak.  

PubMed

Urodeles begin gastrulation with much of their presumptive mesoderm in the superficial cell layer, all of which must move into the deep layers during development. We studied the morphogenesis of superficial mesoderm in the urodeles Ambystoma maculatum, Ambystoma mexicanum, and Taricha granulosa. In all three species, somitic, lateral, and ventral mesoderm move into the deep layer during gastrulation, ingressing through a "bilateral primitive streak" just inside the blastopore. The mesodermal epithelium appears to slide under the endodermal epithelium by a mechanism we term "subduction." Subduction removes the large expanse of superficial presumptive somitic and lateral-ventral mesoderm that initially separates the sub-blastoporal endoderm from the notochord, leaving the endoderm bounding the still epithelial notochord along the gastrocoel roof. Subduction may be a common feature of urodele gastrulation, differing in this regard from anurans. Subducting cells constrict their apices and become bottle-shaped as they approach the junction of the mesodermal and endodermal epithelia. Subducting bottle cells endocytose apical membrane and withdraw the tight junctional component cingulin from the contracting circumferential tight junctions. Either in conjunction with or immediately after subducting, the mesodermal cells undergo an epithelial-to-mesenchymal transition. The mechanism by which epithelial cells release their apical junctions to become mesenchymal, without disrupting the integrity of the epithelium, remains mysterious, but this system should prove useful in understanding this process in a developmental context. PMID:12167400

Shook, David R; Majer, Christina; Keller, Ray

2002-08-15

382

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

383

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

384

Streak spectroscopy and velocimetry of electrically exploded Ni/Al laminates  

NASA Astrophysics Data System (ADS)

We present an experimental and theoretical study of electrically exploded nickel-aluminum (Ni/Al) laminates, lithographically patterned into bow-tie bridge regions, and encapsulated with parylene. The exothermic nature of Ni/Al reactions is well-known at typical self-heating rates of 103-106 K/s, but electrical heating allows the interrogation of phenomena at heating rates which are five to six orders of magnitude higher. The use of time-resolved streak camera emission spectroscopy revealed that Ni/Al laminates heated at these higher rates exhibited brighter emission during the first 150 ns of emission than samples composed of either Al or Ni alone, suggesting an exothermic effect which rapidly started and persisted for at least this length of time. We also measured the transduction of electrical energy into kinetic energy through velocity measurements of encapsulation layers ejected from the bridge region. An empirical model using experimental power curves and one empirical fitting parameter successfully predicted these velocities. This model agreed well with experiments from different Al and Ni samples using the same fitting parameter, but an apparent 1.2 J/mg of additional energy from the mixing of Ni and Al was necessary to accurately predict velocities from Ni/Al laminate samples. This energy quantity corresponded to a reference value for the enthalpy of mixing Ni and Al, and likely contributed to both brighter emission and higher than expected velocities observed.

Morris, Christopher J.; Wilkins, Paul R.; May, Chadd M.

2013-01-01

385

Longitudinal beam profile measurements at CTF3 using a streak camera  

NASA Astrophysics Data System (ADS)

The proposed Compact Linear Collider (CLIC) is a multi-TeV electron-positron collider for particle physics based on an innovative two-beam acceleration concept. A high-intensity drive beam powers the main beam of a high-frequency (30 GHz) linac with a gradient of 150 MV/m, by means of transfer structure sections. The aim of the CLIC Test Facility (CTF3) is to make exhaustive tests of the main CLIC parameters and to prove the technical feasibility. One of the points of particular interest is the demonstration of bunch train compression and combination in the Delay Loop and in the Combiner Ring. Thus, detailed knowledge about the longitudinal beam structure is of utmost importance and puts high demands on the diagnostic equipment. Among others, measurements with a streak camera have been performed on the linac part of the CTF3 as well as on the newly installed Delay Loop. This allowed e.g. monitoring of the longitudinal structure of individual bunches, the RF combination of the beam, the behavior during phase shifts and the influence of the installed wiggler. This article first gives an overview of the CTF3 facility, then describes in detail the layout of the long optical lines required for observation of either optical transition radiation or synchrotron radiation, and finally shows first results obtained during the last machine run this year.

Welsch, C. P.; Braun, H. H.; Bravin, E.; Corsini, R.; Döbert, S.; Lefèvre, T.; Tecker, F.; Urschütz, P.; Buonomo, B.; Coiro, O.; Ghigo, A.; Preger, B.

2006-09-01

386

Assessment of factors influencing the biomethane yield of maize silages.  

PubMed

A large set of maize silage samples was produced to assess the major traits influencing the biomethane production of this crop. The biomass yield, the volatile solids contents and the biochemical methane potential (BMP) were measured to calculate the biomethane yield per hectare (average=7266m(3)ha(-1)). The most influential factor controlling the biomethane yield was the cropping environment. The biomass yield had more impact than the anaerobic digestibility. Nevertheless, the anaerobic digestibility of maize silages was negatively affected by high VS content in mature maize. Late maturing maize varieties produced high biomass yield with high digestibility resulting in high biomethane yield per hectare. The BMP was predicted with good accuracy using solely the VS content. PMID:24368275

Mayer, Frédéric; Gerin, Patrick A; Noo, Anaïs; Foucart, Guy; Flammang, Jos; Lemaigre, Sébastien; Sinnaeve, Georges; Dardenne, Pierre; Delfosse, Philippe

2014-02-01

387

Exploring Hormone Crosstalk in Fusarium verticillioidies Infection of Maize  

E-print Network

a direct effect on in vitro fungal growth. Available auxin deficient mutants of maize were exploited in a kernel bioassay and colonization was assessed through ergosterol quantification by high-performance liquid chromatography. Collectively, our...

Drab, Dillon

2013-02-04

388

Determining density of maize canopy. 1: Digitized photography  

NASA Technical Reports Server (NTRS)

The relationship between different densities of maize (Zea mays L.) canopies and the energy reflected by these canopies was studied. Field plots were laid out, representing four growth stages of maize, on a dark soil and on a very light colored surface soil. Spectral and spatial data were obtained from color and color infrared photography taken from a vertical distance of 10 m above the maize canopies. Estimates of ground cover were related to field measurements of leaf area index. Ground cover was predicted from leaf area index measurements by a second order equation. Color infrared photography proved helpful in determining the density of maize canopy on dark soils. Color photography was useful for determining canopy density on light colored soils. The near infrared dye layer is the most valuable in canopy density determinations.

Stoner, E. R.; Baumgardner, M. F.; Swain, P. H.

1972-01-01

389

Characterization of maize testing locations in eastern and southern Africa  

E-print Network

The region of eastern and southern Africa is very diverse in environments and agronomic practices. The region has one of the highest per capita consumption of maize (Zea mays. L), which is predominantly produced by smallholder farmers. Some...

Maideni, Francis W.

2006-08-16

390

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

391

Modelling of maize production in Croatia: present and future climate.  

PubMed

Maize is one of the most important agricultural crops in Croatia, and was selected for research of the effect of climate warming on yields. The Decision Support System for the Agrotechnology Transfer model (DSSAT) is one of the most utilized crop-weather models in the world, and was used in this paper for the investigation of maize growth and production in the present and future climate. The impact of present climate on maize yield was studied using DSSAT 4.0 with meteorological data from the Zagreb-Maksimir station covering the period 1949-2004. Pedological, physiological and genetic data from a 1999 field maize experiment at the same location were added. The location is representative of the continental climate in central Croatia. The linear trends of model outputs and the non-parametric Mann-Kendall test indicate that the beginning of silking has advanced significantly by 1·4 days/decade since the mid-1990s, and maturity by 4·5 days/decade. It also shows a decrease in biomass by 122 kg/ha and in maize yield by 216 kg/ha in 10 years.Estimates of the sensitivity of maize growth and yield in future climates were made by changing the initial weather and CO(2) conditions of the DSSAT 4.0 model according to the different climatic scenarios for Croatia at the end of the 21st century. Changed climate suggests increases in global solar radiation, minimal temperature and maximal temperature (×1·07, 2 and 4°C, respectively), but a decrease in the amount of precipitation (×0·92), compared with weather data from the period 1949-2004. The reduction of maize yield was caused by the increase in minimal and maximal temperature and the decrease in precipitation amount, related to the present climate, is 6, 12 and 3%, respectively. A doubling of CO(2) concentration stimulates leaf assimilation, but maize yield is only 1% higher, while global solar radiation growth by 7% increases evapotranspiration by 3%. Simultaneous application of all these climate changes suggested that the maize growth period would shorten by c. 1 month and maize yield would decrease by 9%, with the main reason for maize yield reduction in Croatia being due to extremely warm conditions in the future climate. PMID:22505771

Vu?eti?, V

2011-04-01

392

Modelling of maize production in Croatia: present and future climate  

PubMed Central

SUMMARY Maize is one of the most important agricultural crops in Croatia, and was selected for research of the effect of climate warming on yields. The Decision Support System for the Agrotechnology Transfer model (DSSAT) is one of the most utilized crop–weather models in the world, and was used in this paper for the investigation of maize growth and production in the present and future climate. The impact of present climate on maize yield was studied using DSSAT 4.0 with meteorological data from the Zagreb–Maksimir station covering the period 1949–2004. Pedological, physiological and genetic data from a 1999 field maize experiment at the same location were added. The location is representative of the continental climate in central Croatia. The linear trends of model outputs and the non-parametric Mann–Kendall test indicate that the beginning of silking has advanced significantly by 1·4 days/decade since the mid-1990s, and maturity by 4·5 days/decade. It also shows a decrease in biomass by 122 kg/ha and in maize yield by 216 kg/ha in 10 years. Estimates of the sensitivity of maize growth and yield in future climates were made by changing the initial weather and CO2 conditions of the DSSAT 4.0 model according to the different climatic scenarios for Croatia at the end of the 21st century. Changed climate suggests increases in global solar radiation, minimal temperature and maximal temperature (×1·07, 2 and 4°C, respectively), but a decrease in the amount of precipitation (×0·92), compared with weather data from the period 1949–2004. The reduction of maize yield was caused by the increase in minimal and maximal temperature and the decrease in precipitation amount, related to the present climate, is 6, 12 and 3%, respectively. A doubling of CO2 concentration stimulates leaf assimilation, but maize yield is only 1% higher, while global solar radiation growth by 7% increases evapotranspiration by 3%. Simultaneous application of all these climate changes suggested that the maize growth period would shorten by c. 1 month and maize yield would decrease by 9%, with the main reason for maize yield reduction in Croatia being due to extremely warm conditions in the future climate. PMID:22505771

VUCETIC, V.

2011-01-01

393

The Role of cis Regulatory Evolution in Maize Domestication.  

PubMed

Gene expression differences between divergent lineages caused by modification of cis regulatory elements are thought to be important in evolution. We assayed genome-wide cis and trans regulatory differences between maize and its wild progenitor, teosinte, using deep RNA sequencing in F1 hybrid and parent inbred lines for three tissue types (ear, leaf and stem). Pervasive regulatory variation was observed with approximately 70% of ?17,000 genes showing evidence of regulatory divergence between maize and teosinte. However, many fewer genes (1,079 genes) show consistent cis differences with all sampled maize and teosinte lines. For ?70% of these 1,079 genes, the cis differences are specific to a single tissue. The number of genes with cis regulatory differences is greatest for ear tissue, which underwent a drastic transformation in form during domestication. As expected from the domestication bottleneck, maize possesses less cis regulatory variation than teosinte with this deficit greatest for genes showing maize-teosinte cis regulatory divergence, suggesting selection on cis regulatory differences during domestication. Consistent with selection on cis regulatory elements, genes with cis effects correlated strongly with genes under positive selection during maize domestication and improvement, while genes with trans regulatory effects did not. We observed a directional bias such that genes with cis differences showed higher expression of the maize allele more often than the teosinte allele, suggesting domestication favored up-regulation of gene expression. Finally, this work documents the cis and trans regulatory changes between maize and teosinte in over 17,000 genes for three tissues. PMID:25375861

Lemmon, Zachary H; Bukowski, Robert; Sun, Qi; Doebley, John F

2014-11-01

394

Simple inheritance of key traits distinguishing maize and teosinte  

Microsoft Academic Search

The segregation of key traits distinguishing maize and teosinte was analyzed in three F2 and three backcross populations derived from crosses of the modern maize inbred T232 withZea mays ssp.parviglumis. These traits were (i) paired vs. single female spikelets; (ii) two-ranked vs. many-ranked ears; (iii) non-indurated vs. indurated glumes; (iv) inclination of the kernels toward the rachis, and (v) distichous

Véronique M. Szabó; Benjamin Burr

1996-01-01

395

The Role of cis Regulatory Evolution in Maize Domestication  

PubMed Central

Gene expression differences between divergent lineages caused by modification of cis regulatory elements are thought to be important in evolution. We assayed genome-wide cis and trans regulatory differences between maize and its wild progenitor, teosinte, using deep RNA sequencing in F1 hybrid and parent inbred lines for three tissue types (ear, leaf and stem). Pervasive regulatory variation was observed with approximately 70% of ?17,000 genes showing evidence of regulatory divergence between maize and teosinte. However, many fewer genes (1,079 genes) show consistent cis differences with all sampled maize and teosinte lines. For ?70% of these 1,079 genes, the cis differences are specific to a single tissue. The number of genes with cis regulatory differences is greatest for ear tissue, which underwent a drastic transformation in form during domestication. As expected from the domestication bottleneck, maize possesses less cis regulatory variation than teosinte with this deficit greatest for genes showing maize-teosinte cis regulatory divergence, suggesting selection on cis regulatory differences during domestication. Consistent with selection on cis regulatory elements, genes with cis effects correlated strongly with genes under positive selection during maize domestication and improvement, while genes with trans regulatory effects did not. We observed a directional bias such that genes with cis differences showed higher expression of the maize allele more often than the teosinte allele, suggesting domestication favored up-regulation of gene expression. Finally, this work documents the cis and trans regulatory changes between maize and teosinte in over 17,000 genes for three tissues. PMID:25375861

Lemmon, Zachary H.; Bukowski, Robert; Sun, Qi; Doebley, John F.

2014-01-01

396

RESPONSE OF MAIZE SEEDLINGS TO MICROWAVES AT 945 MHz  

Microsoft Academic Search

The objective of the present study was to investigate the changes of germination, growth rate and absorbance efficiency of photosynthetic pigments of maize grains after exposed to microwaves (MW). Experiment was carried out by exposing maize plants to continuous microwaves energy at (935.2-960.2 MHz with intensities 0.07-0.15 mW\\/cm2). The test plants and the control plants were subjected to the same

A. A. KHALAFALLAH; SAMIRA M. SALLAM

397

Biological characteristics of maize dwarf mosaic potyvirus from Spain  

Microsoft Academic Search

Two isolates of maize dwarf mosaic virus (MDMV-Sp and MDMV-Spl) obtained from maize in the northeast of Spain were studied. Both isolates induced similar reactions on 6 sorghum cultivars, johnsongrass and oat (cv. Clintland), with the exception of MDMV-Sp which produced a different reaction on one sorghum cultivar. Thirty-three grass species were tested as possible hosts (16 previously untested) and

M. Angeles Achon; Marion Pinner; Vicente Medina; George P. Lomonossoff

1996-01-01

398

Water Transfer in an Alfalfa/Maize Association 1  

PubMed Central

We investigated the possibility of interspecific water transfer in an alfalfa (Medicago sativa L.) and maize (Zea mays L.) association. An alfalfa plant was grown through two vertically stacked plastic tubes. A 5 centimeter air gap between tubes was bridged by alfalfa roots. Five-week old maize plants with roots confined to the top tube were not watered, while associated alfalfa roots had free access to water in the bottom tube (the ?/+ treatment). Additional treatments included: top and bottom tubes watered (+/+), top and bottom tubes droughted (?/?), and top tube droughted after removal of alfalfa root bridges and routine removal of alfalfa tillers (?*). Predawn leaf water potential of maize in the ?/+ treatment fell to ?1.5 megapascals 13 days after the start of drought; thereafter, predawn and midday potentials were maintained near ?1.9 megapascals. Leaf water potentials of maize in the ?/? and ?* treatments declined steadily; all plants in these treatments were completely desiccated before day 50. High levels of tritium activity were detected in water extracted from both alfalfa and maize leaves after 3H2O was injected into the bottom ?/+ tube at day 70 or later. Maize in the ?/+ treatment was able to survive an otherwise lethal period of drought by utilizing water lost by alfalfa roots. Images Fig. 2 PMID:16665484

Corak, Steven J.; Blevins, Dale G.; Pallardy, Stephen G.

1987-01-01

399

Developing resistance to aflatoxin in maize and cottonseed.  

PubMed

At this time, no "magic bullet" for solving the aflatoxin contamination problem in maize and cottonseed has been identified, so several strategies must be utilized simultaneously to ensure a healthy crop, free of aflatoxins. The most widely explored strategy for the control of aflatoxin contamination is the development of preharvest host resistance. This is because A. flavus infects and produces aflatoxins in susceptible crops prior to harvest. In maize production, the host resistance strategy has gained prominence because of advances in the identification of natural resistance traits. However, native resistance in maize to aflatoxin contamination is polygenic and complex and, therefore, markers need to be identified to facilitate the transfer of resistance traits into agronomically viable genetic backgrounds while limiting the transfer of undesirable traits. Unlike maize, there are no known cotton varieties that demonstrate enhanced resistance to A. flavus infection and aflatoxin contamination. For this reason, transgenic approaches are being undertaken in cotton that utilize genes encoding antifungal/anti-aflatoxin factors from maize and other sources to counter fungal infection and toxin production. This review will present information on preharvest control strategies that utilize both breeding and native resistance identification approaches in maize as well as transgenic approaches in cotton. PMID:22069734

Cary, Jeffrey W; Rajasekaran, Kanniah; Brown, Robert L; Luo, Meng; Chen, Zhi-Yuan; Bhatnagar, Deepak

2011-06-01

400

Regulatory modules controlling maize inflorescence architecture  

PubMed Central

Genetic control of branching is a primary determinant of yield, regulating seed number and harvesting ability, yet little is known about the molecular networks that shape grain-bearing inflorescences of cereal crops. Here, we used the maize (Zea mays) inflorescence to investigate gene networks that modulate determinacy, specifically the decision to allow branch growth. We characterized developmental transitions by associating spatiotemporal expression profiles with morphological changes resulting from genetic perturbations that disrupt steps in a pathway controlling branching. Developmental dynamics of genes targeted in vivo by the transcription factor RAMOSA1, a key regulator of determinacy, revealed potential mechanisms for repressing branches in distinct stem cell populations, including interactions with KNOTTED1, a master regulator of stem cell maintenance. Our results uncover discrete developmental modules that function in determining grass-specific morphology and provide a basis for targeted crop improvement and translation to other cereal crops with comparable inflorescence architectures. PMID:24307553

Eveland, Andrea L.; Goldshmidt, Alexander; Pautler, Michael; Morohashi, Kengo; Liseron-Monfils, Christophe; Lewis, Michael W.; Kumari, Sunita; Hiraga, Susumu; Yang, Fang; Unger-Wallace, Erica; Olson, Andrew; Hake, Sarah; Vollbrecht, Erik; Grotewold, Erich; Ware, Doreen; Jackson, David

2014-01-01

401

Ribonucleoprotein particles of quiescent maize embryonic axes.  

PubMed

Certain RNA molecules are known to be sequestered and stored as ribonucleoprotein particles (RNPs) in many different tissues, particularly at some stages of metabolic quiescence. In this research RNPs from embryonic axes of mature maize seeds were isolated by sucrose and CsCl gradient centrifugation and characterized based on their RNA and protein contents. Two types of RNP particles of non-ribosomal nature were identified by northern blot analysis with specific probes: the 7S RNP and the signal recognition particle (SRP) particles which contain 5S rRNA and 7S RNA respectively. The proteins associated to these RNA molecules were the transcription factor TFIIIA-homologous protein associated to 7S RNP, and the p72, p68 and p54-GTPase proteins associated to SRP. PMID:9747844

Rincón-Guzmán, A; Beltrán-Peña, E; Ortíz-López, A; Sánchez de Jiménez, E

1998-10-01

402

Development of a Brazilian maize core collection  

PubMed Central

The aim of this study was to evaluate methods for developing a Brazilian maize core collection. For an initial survey of the active collection, passport information, as well as characterization and evaluation of accessions, were taken into consideration, these then being divided according to geographic region and kernel-type. Multiple sampling methods were evaluated. The strategy of constant sampling generated extensive alterations in extract accession frequency. The multivariate strategy with dispersion graphs and principal components associated with the Tocher method was considered efficient for identifying the most divergent genotypes. The multivariate strategy generated greater alterations in the variance of traits. The average number of traits revealed few modifications with the various sampling strategies used. Therefore, the active collection could be considered as possessing a satisfactory amount of information for most of its accessions. Moreover, the multivariate strategy generated modifications in the variance of the traits, independent of sampling intensity. PMID:21637517

2009-01-01

403

Development of a Brazilian maize core collection.  

PubMed

The aim of this study was to evaluate methods for developing a Brazilian maize core collection. For an initial survey of the active collection, passport information, as well as characterization and evaluation of accessions, were taken into consideration, these then being divided according to geographic region and kernel-type. Multiple sampling methods were evaluated. The strategy of constant sampling generated extensive alterations in extract accession frequency. The multivariate strategy with dispersion graphs and principal components associated with the Tocher method was considered efficient for identifying the most divergent genotypes. The multivariate strategy generated greater alterations in the variance of traits. The average number of traits revealed few modifications with the various sampling strategies used. Therefore, the active collection could be considered as possessing a satisfactory amount of information for most of its accessions. Moreover, the multivariate strategy generated modifications in the variance of the traits, independent of sampling intensity. PMID:21637517

Coimbra, Ronaldo R; Miranda, Glauco V; Cruz, Cosme D; Silva, Derly J H; Vilela, Ramiro A

2009-07-01

404

The Genetic Architecture of Maize Stalk Strength  

PubMed Central

Stalk strength is an important trait in maize (Zea mays L.). Strong stalks reduce lodging and maximize harvestable yield. Studies show rind penetrometer resistance (RPR), or the force required to pierce a stalk rind with a spike, is a valid approximation of strength. We measured RPR across 4,692 recombinant inbreds (RILs) comprising the maize nested association mapping (NAM) panel derived from crosses of diverse inbreds to the inbred, B73. An intermated B73×Mo17 family (IBM) of 196 RILs and a panel of 2,453 diverse inbreds from the North Central Regional Plant Introduction Station (NCRPIS) were also evaluated. We measured RPR in three environments. Family-nested QTL were identified by joint-linkage mapping in the NAM panel. We also performed a genome-wide association study (GWAS) and genomic best linear unbiased prediction (GBLUP) in each panel. Broad sense heritability computed on a line means basis was low for RPR. Only 8 of 26 families had a heritability above 0.20. The NCRPIS diversity panel had a heritability of 0.54. Across NAM and IBM families, 18 family-nested QTL and 141 significant GWAS associations were identified for RPR. Numerous weak associations were also found in the NCRPIS diversity panel. However, few were linked to loci involved in phenylpropanoid and cellulose synthesis or vegetative phase transition. Using an identity-by-state (IBS) relationship matrix estimated from 1.6 million single nucleotide polymorphisms (SNPs) and RPR measures from 20% of the NAM panel, genomic prediction by GBLUP explained 64±2% of variation in the remaining RILs. In the NCRPIS diversity panel, an IBS matrix estimated from 681,257 SNPs and RPR measures from 20% of the panel explained 33±3% of variation in the remaining inbreds. These results indicate the high genetic complexity of stalk strength and the potential for genomic prediction to hasten its improvement. PMID:23840585

Peiffer, Jason A.; Flint-Garcia, Sherry A.; De Leon, Natalia; McMullen, Michael D.; Kaeppler, Shawn M.; Buckler, Edward S.

2013-01-01

405

Safety assessment of Bt 176 maize in broiler nutrition: degradation of maize-DNA and its metabolic fate.  

PubMed

Insect resistant Bt 176 maize has been developed by genetic modification to resist European borer infection. In the present investigation, the experiment was conducted to determine the effect of feeding a new hybrid of Bt 176 maize (NX 6262- Bt 176) on general health condition and performance of broiler chickens. Maize grains and diets were subjected to proximate analysis. Amino and fatty acids investigation were applied for both maize grains before used. To evaluate the degradation of NX 6262- Bt 176 maize DNA and its metabolic fate in broiler blood, muscles and organs. One-day-old male broilers were fed ad libitum on either an experimental diet containing NX 6262- Bt 176 or a control diet containing the non-modified maize grains for 35 days. Feed consumption and body weight were recorded weekly during the experimental period. All chickens were subjected to nutritional evaluation period at day 20 of age for 5 successive days, to calculate the percentage of apparent digestible nutrients in both diets. At day 35 samples were collected at several intervals after feed withdrawal. Prior to slaughter blood samples were collected from all birds by heart puncture to prevent DNA cross contamination. Samples from pectoral and thigh muscles, liver, spleen, kidney, heart muscle, bursa and thymus glands were collected. Digesta from different sections of the gastrointestinal tract (GIT) were collected as well. Packed cell volume (PCV) and some serum parameters were investigated. There were no significant differences between control and experimental group concerning chemical composition of feeds, apparent digestible nutrients, and all performance parameters measured (P > 0.05). Furthermore, there were no differences in the PCV and the analysed serum parameters between the control and experimental group. The results of maize DNA digestibility showed that the new variety takes the normal physiological passage along broiler GIT similar to the conventional line. In addition, Bt 176 maize DNA appears to be partially degraded in different parts of GIT comparable to the DNA of the control maize line. Results of the metabolic fate of maize DNA in broiler blood, muscles and organs indicated that only short DNA fragments (199 bp) derived from the plant chloroplast gene could be detected in the blood, skeletal muscles, liver, spleen and kidney, which disappeared after prolongation the fasting time. In heart muscle, bursa of Fabricius and thymus, no plant chloroplast DNA was found. Bt gene specific constructs from Bt 176 maize were not detected in any investigated blood or tissue samples. PMID:14533864

Tony, M A; Butschke, A; Broll, H; Grohmann, L; Zagon, J; Halle, I; Dänicke, S; Schauzu, M; Hafez, H M; Flachowsky, G

2003-08-01

406

Effects of tree shading on maize crop within a Poplar-maize compound system in Hexi Corridor oasis, northwestern China  

Microsoft Academic Search

Effects of tree shading on crop within agroforestry system in the oasis regions or under irrigation agriculture are poorly\\u000a understood. Objective was to determine maize yield variation and its reasons when tall Poplar trees (Populus gansuensis) were grown in western and eastern margins of the crop field in Hexi Corridor desert oasis in northwestern China. Maize growing\\u000a among the 50 m

Songshuang Ding; Peixi Su

2010-01-01

407

The profitability of maize–haricot bean intercropping techniques to control maize stem borers under low pest densities in Ethiopia  

Microsoft Academic Search

Lepidopteran stem borers are the main pests of cereals in Ethiopia. In recent years, habitat management techniques, which\\u000a aim at increasing plant biodiversity through mixed cropping, have gained increased attention in stem borer control. In the\\u000a present study, the profitability of mixed cropping of maize with haricot beans at different ratios and the effect on infestation\\u000a of maize by stem

D. Belay; F. Schulthess; C. Omwega

2009-01-01

408

Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis ( Bt) maize and non- Bt maize  

Microsoft Academic Search

Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non-Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to

Lars-Henrik Heckmann; Bryan S. Griffiths; Sandra Caul; Jacqueline Thompson; Marianne Pusztai-Carey; William J. Moar; Mathias N. Andersen; Paul Henning Krogh

2006-01-01

409

Vector transmission studies of Maize Dwarf Mosaic Virus (MDMV) with the yellow sugar-cane aphid, Sipha flava (Forbes)  

E-print Network

was considered synomous with the johnsongrass strain of Sugar- cane Mosaic Virus (SMV-Jg). In recent years the MDMV has been reported in most of the corn and sorghum producing states. Maize Dwarf Mosaic Virus observed in Burleson county, Texas, for the fi. rst... the Ohio River. The signi. ficance of the disease was realized in 1963. It spread to an estimated 15, 000 acres in 12 counties along the Ohio and Scioto Rivers. Yie1d losses with this virus-like disease were suspected, but similarities to corn stunt...

Su, Shu-Hua

2012-06-07

410

Fluorescence measurement by a streak camera in a single-photon-counting mode.  

PubMed

We describe here a recently developed fluorescence measurement system that uses a streak camera to detect fluorescence decay in a single photon-counting mode. This system allows for easy measurements of various samples and provides 2D images of fluorescence in the wavelength and time domains. The great advantage of the system is that the data can be handled with ease; furthermore, the data are amenable to detailed analysis. We describe the picosecond kinetics of fluorescence in spinach Photosystem (PS) II particles at 4-77 K as a typical experimental example. Through the global analysis of the data, we have identified a new fluorescence band (F689) in addition to the already established F680, F685, and F695 emission bands. The blue shift of the steady-state fluorescence spectrum upon cooling below 77 K can be interpreted as an increase of the shorter-wavelength fluorescence, especially F689, due to the slowdown of the excitation energy transfer process. The F685 and F695 bands seem to be thermally equilibrated at 77 K but not at 4 K. The simple and efficient photon accumulation feature of the system allows us to measure fluorescence from leaves, solutions, single colonies, and even single cells. The 2D fluorescence images obtained by this system are presented for isolated spinach PS II particles, intact leaves of Arabidopsis thaliana, the PS I super-complex of a marine centric diatom, Chaetoceros gracilis, isolated membranes of a purple photosynthetic bacterium, Acidiphilium rubrum, which contains Zn-BChl a, and a coral that contains a green fluorescent protein and an algal endosymbiont, Zooxanthella. PMID:19568951

Komura, Masayuki; Itoh, Shigeru

2009-01-01

411

Prospects for reducing fumonisin contamination of maize through genetic modification.  

PubMed Central

Fumonisins (FB) are mycotoxins found in (italic)Fusarium verticillioides-infected maize grain worldwide. Attention has focused on FBs because of their widespread occurrence, acute toxicity to certain livestock, and their potential carcinogenicity. FBs are present at low levels in most field-grown maize but may spike to high levels depending on both the environment and genetics of the host plant. Among the strategies for reducing risk of FB contamination in maize supplied to the market, development and deployment of Fusarium ear mold-resistant maize germplasm is a high priority. Breeding for increased ear mold tolerance and reduced mycotoxin levels is being practiced today in both commercial and public programs, but the amount of resistance achievable may be limited due to complicated genetics and/or linkage to undesirable agronomic traits. Molecular markers can be employed to speed up the incorporation of chromosomal regions that have a quantitative effect on resistance (quantitative trait loci). Transgenic approaches to ear mold/mycotoxin resistance are now feasible as well. These potentially include genetically enhanced resistance to insect feeding, increased fungal resistance, and detoxification/prevention of mycotoxins in the grain. An example of the first of these approaches is already on the market, namely transgenic maize expressing Bacillus thuringiensis (Bt) toxin, targeted to the European corn borer. Some Bt maize hybrids have the potential to reduce FB levels in field-harvested grain, presumably through reduced feeding of Bt-susceptible insects in ear tissues. However, improved ear mold resistance per se is still an important goal, as the plant will still be vulnerable to noninsect routes of entry to (italic)Fusarium. A second approach, transgene-mediated control of the ability of Fusarium to infect and colonize the ear, could potentially be achieved through overexpression of specific antifungal proteins and metabolites, or enhancement of the plant's own defense systems in kernel tissues. This has not yet been accomplished in maize, although promising results have been obtained recently in other monocots versus other fungal and bacterial pathogens. Achieving reproducible and stable enhanced ear mold resistance under field conditions will be immensely challenging for biotechnologists. A third approach, transgene strategies aimed at preventing mycotoxin biosynthesis, or detoxifying mycotoxins in planta, could provide further protection for the grower in environments where FBs present a risk to the crop even when the maize is relatively resistant to Fusarium mold. In one example of such a strategy, enzymes that degrade FBs have been identified in a filamentous saprophytic fungus isolated from maize, and corresponding genes have been cloned and are currently being tested in transgenic maize. PMID:11359705

Duvick, J

2001-01-01

412

Molecular characterization of Fusarium globosum strains from South African maize and Japanese wheat  

E-print Network

are undergoing asexual but not sexual reproduction. Together, the results suggest that the South African maize maize and Japanese wheat isolates of the fungus exhibit multiple differences. An amplified fragment

413

Improving Maize by QTL Mapping, Agronomic Performance and Breeding to Reduce Aflatoxin in Texas  

E-print Network

Aflatoxins are potent carcinogens produced by the fungus Aspergillus flavus Link:Fr and are a significant preharvest problem in maize production in Texas, the southern US, and subtropical climates. Several sources of maize germplasm are available...

Mayfield, Kerry Lucas

2012-07-16

414

RESEARCH ARTICLE Little fertilizer response but high N loss risk of maize  

E-print Network

of biogas. The production and use of maize for biogas is more cost efficient compared with other crops and the cultivation, harvest and storage of maize is well established with farmers. Consequently, the biogas boom has

Paris-Sud XI, Université de

415

Decomposition of transgenic Bacillus thuringiensis maize by microorganisms and woodlice Porcellio scaber (Crustacea: Isopoda)  

E-print Network

Decomposition of transgenic Bacillus thuringiensis maize by microorganisms and woodlice Porcellio-transgenic maize was up to 60% high- er than on faeces of the transgenic-fed woodlice, but bacterial growth

Richner, Heinz

416

Analysis of the insect community in a stored-maize facility  

Microsoft Academic Search

Maize samples were obtained at two depths [0–30?cm (top sample) and 30–60?cm (bottom sample) from the maize surface] at 19–28 locations from a naturally infested maize storage facility in Wisconsin, USA. Based on identification of insects in stored-maize samples from 13 weekly sampling events, four topics were addressed: (i) the seasonal fluctuation in the insect community; (ii) ordination analysis was

Christian NANSEN; Thomas W. PHILLIPS; Michael W. PALMER

2004-01-01

417

Exposure of infants to fumonisins in maize-based complementary foods in rural Tanzania  

Microsoft Academic Search

Feeding children with maize may expose them to fumonisins (FBs). This study assessed FB exposure for infants consuming maize in Tanzania by modeling maize consumption data (kg\\/kg body weight (bw)\\/day) with previously collected total FB contamination (lg\\/kg) patterns for sorted and unsorted maize harvested in 2005 and 2006. Consumption was estimated by twice conducting a 24 h dietary recall for

Martin E. Kimanya; Bruno De Meulenaer; Katleen Baert; Bendantunguka Tiisekwa; John Van Camp; Simbarashe Samapundo; Carl Lachat; Patrick Kolsteren

2009-01-01

418

agronomie: agriculture and environment Nitrogen uptake capacities of maize and sorghum crops  

E-print Network

of sorghum crops to take up nitrogen from the soil was always higher than that of maize. This feature of taking up much larger quantities of nitrogen from the soil than maize before its nitrogen nutrition became limiting. Drought reduced nitrogen availability in the soil for both crops. Maize was more

Boyer, Edmond

419

Genetic Diversity in CIMMYT Nontemperate Maize Germplasm: Landraces, Open Pollinated Varieties, and Inbred Lines  

Microsoft Academic Search

CIMMYT is the source of improved maize (Zea mays L.) breeding material for a signifi cant por- tion of the nontemperate maize growing world. Landraces which did not serve as sources for improved maize germplasm may contain untapped allelic variation useful for future breed- ing progress. Information regarding levels of diversity in different germplasm would help to identify sources for

M. L. Warburton; J. C. Reif; M. Frisch; M. Bohn; C. Bedoya; X. C. Xia; J. Crossa; J. Franco; D. Hoisington; K. Pixley; S. Taba; A. E. Melchinger

2008-01-01

420

Research on the use of dehydrated whole maize plant in the feed of growing rabbits  

E-print Network

Research on the use of dehydrated whole maize plant in the feed of growing rabbits Maria during the trial, but significantly until 60 days of age. Utilization of dehydrated whole maize plant Cunicole, 95450 Vigny (France). Four trials were made to study dehydrated whole maize plant as crude fibre

Paris-Sud XI, Université de

421

SHORT COMMUNICATION Does feeding on Bt-maize affect the slug Arion vulgaris  

E-print Network

2 September 2009) Via expression of Cry-proteins, toxic for specific insect groups, genetically modified Bacillus thuringiensis (Bt) maize offers an effective protection against insect pests-effect but indicated the general poor quality of maize as food resource for slugs. Keywords: Bt-maize; non

Richner, Heinz

422

Diversity and comparative phenology of Lepidoptera on Bt and non-Bt maize in South Africa  

Microsoft Academic Search

The use of Bt maize could directly or indirectly affect non-target organisms. Assessment of the impacts of Bt crops is hampered by the lack of even the most basic checklist of the species present in most systems. In South Africa the maize agroecosystem is of particular interest because of the large area planted with Bt maize (Event MON810) for the

Annemie van Wyk; Johnnie van den Berg; Huib van Hamburg

2008-01-01

423

Cover crops and interrow tillage for weed control in short season maize ( Zea mays)  

Microsoft Academic Search

Weed competition can cause substantial maize (Zea mays L.) yield reductions. Interseeding maize with cover crops or a combination of interrow cultivation and interseeded cover crops are possible alternative methods of weed control. This study was conducted to examine the potential of interrow cultivation plus cover crops to reduce weed density in maize without reducing the grain yield. Field experiments

O. A. Abdin; X. M. Zhou; D. Cloutier; D. C. Coulman; M. A. Faris; D. L. Smith

2000-01-01

424

Decomposition of transgenic Bacillus thuringiensis maize by microorganisms and woodlice Porcellio scaber (Crustacea: Isopoda)  

Microsoft Academic Search

Foliage of transgenic maize Zea mays L., expressing a Cry1Ab protein derived from Bacillus thuringiensis (Berliner) subsp. kurstaki, was compared with foliage of the corresponding non-trans- genic maize variety in laboratory feeding and decomposition experiments to study the effects of the B. thuringiensis protein on the chemical composition of the maize leaves, on the decomposer Por- cellio scaber (Crustacea: Isopoda),

Natalie Escher; Barbara Käch; Wolfgang Nentwig

2000-01-01

425

Evaluation of dynamic range for LLNL streak cameras using high contrast pulses and pulse podiatry'' on the Nova laser system  

SciTech Connect

A standard LLNL streak camera has been used to analyze high contrast pulses on the Nova laser facility. These pulses have a plateau at their leading edge (foot) with an amplitude which is approximately 1% of the maximum pulse height. Relying on other features of the pulses and on signal multiplexing, we were able to determine how accurately the foot amplitude was being represented by the camera. Results indicate that the useful single channel dynamic range of the instrument approaches 100:1. 1 ref., 4 figs., 1 tab.

Richards, J.B.; Weiland, T.L.; Prior, J.A.

1990-07-01

426

A compact streak camera for 150 fs time resolved measurement of bright pulses in ultrafast electron diffraction.  

PubMed

We have developed a compact streak camera suitable for measuring the duration of highly charged subrelativistic femtosecond electron bunches with an energy bandwidth in the order of 0.1%, as frequently used in ultrafast electron diffraction (UED) experiments for the investigation of ultrafast structural dynamics. The device operates in accumulation mode with 50 fs shot-to-shot timing jitter, and at a 30 keV electron energy, the full width at half maximum temporal resolution is 150 fs. Measured durations of pulses from our UED gun agree well with the predictions from the detailed charged particle trajectory simulations. PMID:21034115

Kassier, G H; Haupt, K; Erasmus, N; Rohwer, E G; von Bergmann, H M; Schwoerer, H; Coelho, S M M; Auret, F D

2010-10-01

427

Characterization of the x-ray sensitivity of a streak camera used at the National Ignition Facility (NIF)  

NASA Astrophysics Data System (ADS)

A neutron hardened x-ray streak camera has been used to report x-ray burn duration and time of peak emission from imploding ICF capsules at the National Ignition Facility with <30 ps. Recent characterization of the instrument using a NIST traceable High Energy X-ray reference source (HEX, National Security Technologies) will enable absolute capsule self-emission x-ray yield measurements (J/sr/keV). This manuscript describes the characterization procedure used and preliminary results of the x-ray sensitivity using three different thicknesses of the CsI photocathode.

Khan, S. F.; Lee, J. J.; Izumi, N.; Hatch, B.; Larsen, G. K.; MacPhee, A. G.; Kimbrough, J. R.; Holder, J. P.; Haugh, M. J.; Opachich, Y. P.; Bell, P. M.; Bradley, D. K.

2013-09-01

428

Acid Phosphatase Role in Chickpea/Maize Intercropping  

PubMed Central

• Background and aims Organic P comprises 30–80 % of the total P in most agricultural soils. It has been proven that chickpea facilitates P uptake from an organic P source by intercropped wheat. In this study, acid phosphatase excreted from chickpea roots is quantified and the contribution of acid phosphatase to the facilitation of P uptake by intercropped maize receiving phytate is examined. • Methods For the first experiment using hydroponics, maize (Zea mays ‘Zhongdan No. 2’) and chickpea (Cicer arietinum ‘Sona’) were grown in either the same or separate containers, and P was supplied as phytate, KH2PO4 at 0·25 mmol P L?1, or not at all. The second experiment involved soil culture with three types of root separation between the two species: (1) plastic sheet, (2) nylon mesh, and (3) no barrier. Maize plants were grown in one compartment and chickpea in the other. Phosphorus was supplied as phytate, Ca(H2PO4)2 at 50 mg P kg?1, or no P added. • Key results In the hydroponics study, the total P uptake by intercropped maize supplied with phytate was 2·1-fold greater than when it was grown as a monoculture. In the soil experiment, when supplied with phytate, total P uptake by maize with mesh barrier and without root barrier was 2·2 and 1·5 times, respectively, as much as that with solid barrier. In both experiments, roots of both maize and chickpea supplied with phytate and no P secreted more acid phosphatase than those with KH2PO4 or Ca(H2PO4)2. However, average acid phosphatase activity of chickpea roots supplied with phytate was 2–3-fold as much as maize. Soil acid phosphatase activity in the rhizosphere of chickpea was also significantly higher than maize regardless of P sources. • Conclusions Chickpea can mobilize organic P in both hydroponic and soil cultures, leading to an interspecific facilitation in utilization of organic P in maize/chickpea intercropping. PMID:15238349

LI, S. M.; LI, L.; ZHANG, F. S.; TANG, C.

2004-01-01

429

Protein profiles reveal diverse responsive signaling pathways in kernels of two maize inbred lines with contrasting drought sensitivity.  

PubMed

Drought stress is a major factor that contributes to disease susceptibility and yield loss in agricultural crops. To identify drought responsive proteins and explore metabolic pathways involved in maize tolerance to drought stress, two maize lines (B73 and Lo964) with contrasting drought sensitivity were examined. The treatments of drought and well water were applied at 14 days after pollination (DAP), and protein profiles were investigated in developing kernels (35 DAP) using iTRAQ (isobaric tags for relative and absolute quantitation). Proteomic analysis showed that 70 and 36 proteins were significantly altered in their expression under drought treatments in B73 and Lo964, respectively. The numbers and levels of differentially expressed proteins were generally higher in the sensitive genotype, B73, implying an increased sensitivity to drought given the function of the observed differentially expressed proteins, such as redox homeostasis, cell rescue/defense, hormone regulation and protein biosynthesis and degradation. Lo964 possessed a more stable status with fewer differentially expressed proteins. However, B73 seems to rapidly initiate signaling pathways in response to drought through adjusting diverse defense pathways. These changes in protein expression allow for the production of a drought stress-responsive network in maize kernels. PMID:25334062

Yang, Liming; Jiang, Tingbo; Fountain, Jake C; Scully, Brian T; Lee, Robert D; Kemerait, Robert C; Chen, Sixue; Guo, Baozhu

2014-01-01

430

Protein Profiles Reveal Diverse Responsive Signaling Pathways in Kernels of Two Maize Inbred Lines with Contrasting Drought Sensitivity  

PubMed Central

Drought stress is a major factor that contributes to disease susceptibility and yield loss in agricultural crops. To identify drought responsive proteins and explore metabolic pathways involved in maize tolerance to drought stress, two maize lines (B73 and Lo964) with contrasting drought sensitivity were examined. The treatments of drought and well water were applied at 14 days after pollination (DAP), and protein profiles were investigated in developing kernels (35 DAP) using iTRAQ (isobaric tags for relative and absolute quantitation). Proteomic analysis showed that 70 and 36 proteins were significantly altered in their expression under drought treatments in B73 and Lo964, respectively. The numbers and levels of differentially expressed proteins were generally higher in the sensitive genotype, B73, implying an increased sensitivity to drought given the function of the observed differentially expressed proteins, such as redox homeostasis, cell rescue/defense, hormone regulation and protein biosynthesis and degradation. Lo964 possessed a more stable status with fewer differentially expressed proteins. However, B73 seems to rapidly initiate signaling pathways in response to drought through adjusting diverse defense pathways. These changes in protein expression allow for the production of a drought stress-responsive network in maize kernels. PMID:25334062

Yang, Liming; Jiang, Tingbo; Fountain, Jake C.; Scully, Brian T.; Lee, Robert D.; Kemerait, Robert C.; Chen, Sixue; Guo, Baozhu

2014-01-01

431

Evolution and Expression of Tandem Duplicated Maize Flavonol Synthase Genes  

PubMed Central

Flavonoids are specialized compounds widely distributed and with diverse functions throughout the plant kingdom and with several benefits for human health. In particular, flavonols, synthesized by flavonol synthase (FLS), protect plants against UV-B radiation and are essential for male fertility in maize and other plants. We have recently characterized a UV-B inducible ZmFLS1, corresponding to the first to be described in monocot plants. Interestingly, the new assembly of the B73 maize genome revealed the presence of a second putative FLS gene (ZmFLS2), with very high identity with ZmFLS1. ZmFLSs expression was analyzed in different maize tissues, and by combining electrophoretic mobility shift assays and transient expression experiments, we show that both genes are direct targets of anthocyanin (C1/PL1?+?R/B) and 3-deoxy flavonoid (P1) transcriptional regulators. ZmFLS expression analyses show higher levels of both transcripts in high altitude landraces than inbred lines, and both genes are regulated by UV-B radiation in all lines analyzed. Moreover, the high sequence conservation of the ZmFLS promoters between maize lines suggests that the differences observed in ZmFLS expression are due to allelic variations in the transcription factors that regulate their activities. Finally, we generated pFLS1::FLS1-RFP transgenic plants and analyzed ZmFLS1 expression in different maize tissues; we found that this enzyme is localized in the ER and the perinuclear region. PMID:22654889

Falcone Ferreyra, Maria Lorena; Casas, Maria Isabel; Questa, Julia Irene; Herrera, Andrea Lorena; DeBlasio, Stacy; Wang, Jing; Jackson, David; Grotewold, Erich; Casati, Paula

2012-01-01

432

Maize transformation technology development for commercial event generation.  

PubMed

Maize is an important food and feed crop in many countries. It is also one of the most important target crops for the application of biotechnology. Currently, there are more biotech traits available on the market in maize than in any other crop. Generation of transgenic events is a crucial step in the development of biotech traits. For commercial applications, a high throughput transformation system producing a large number of high quality events in an elite genetic background is highly desirable. There has been tremendous progress in Agrobacterium-mediated maize transformation since the publication of the Ishida et al. (1996) paper and the technology has been widely adopted for transgenic event production by many labs around the world. We will review general efforts in establishing efficient maize transformation technologies useful for transgenic event production in trait research and development. The review will also discuss transformation systems used for generating commercial maize trait events currently on the market. As the number of traits is increasing steadily and two or more modes of action are used to control key pests, new tools are needed to efficiently transform vectors containing multiple trait genes. We will review general guidelines for assembling binary vectors for commercial transformation. Approaches to increase transformation efficiency and gene expression of large gene stack vectors will be discussed. Finally, recent studies of targeted genome modification and transgene insertion using different site-directed nuclease technologies will be reviewed. PMID:25140170

Que, Qiudeng; Elumalai, Sivamani; Li, Xianggan; Zhong, Heng; Nalapalli, Samson; Schweiner, Michael; Fei, Xiaoyin; Nuccio, Michael; Kelliher, Timothy; Gu, Weining; Chen, Zhongying; Chilton, Mary-Dell M

2014-01-01

433

Prospects for maize production in Spain under climate change  

SciTech Connect

Agricultural productivity and water resources may be affected by global climate change. Three global climate models (GCMs) and the CERES-maize crop model were used to explore the potential impacts of climate change on maize (Zea mays L.) production in Spain. This study was carried out in five regions that include the largest areas of Spain where maize is grown as a high input crop. Although the results depend on the severity of climate change and the physiological effects of CO{sub 2} on the crop, the simulations under the present management practices suggest that yields are likely to decrease in the all production areas. This is due to a shortening of the crop growth duration as temperatures increase. Finally, this study evaluated changes in crop management that may represent the adaptation of farmers to changing climate conditions. Adaptation strategies based on earlier sowing dates or choice of hybrids with a longer crop growth duration compensated for climate change impacts only in two regions, but not in the main maize-growing areas of central Spain. The high production costs of this crop and the limited water available for irrigation may force maize production to be abandoned in some areas, especially in Central Spain.

Iglesias, A. [Inst. Nacional de Investigacion Tecnologia, Madrid (Spain). Centre de Investigacion Forestal; Minguez, M.I. [Escuela Tecnica Superio