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1

MAIZE FINE STREAK VIRUS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The report outlines the salient features of maize fine streak virus (MFSV) including a general description of the causal virus species, virion properties, genome description, the relationship of the virus to other taxa, biological properties of the disease and agronomic aspects of the disease. Maize...

2

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, Adérito L.; Thomson, Jennifer A.; Dale, James; Rybicki, Edward P.

2014-01-01

3

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

4

Structure of the Maize Streak Virus Geminate Particle  

Microsoft Academic Search

The Geminiviridae is an extensive family of plant viruses responsible for economically devastating diseases in crops worldwide. Geminiviruses package circular, single-stranded DNA (ssDNA) genomes. The characteristic twinned or “geminate” particles, which consist of two joined, incomplete T = 1 icosahedra, are unique among viruses. We have determined the first structure of a geminivirus particle, the Nigerian strain of Maize streak

Wei Zhang; Norman H. Olson; Timothy S. Baker; Lee Faulkner; Mavis Agbandje-McKenna; Margaret I. Boulton; Jeffrey W. Davies; Robert McKenna

2001-01-01

5

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

PubMed Central

Background Panicum streak virus (PanSV; Family Geminiviridae; Genus Mastrevirus) is a close relative of Maize streak virus (MSV), the most serious viral threat to maize production in Africa. PanSV and MSV have the same leafhopper vector species, largely overlapping natural host ranges and similar geographical distributions across Africa and its associated Indian Ocean Islands. Unlike MSV, however, PanSV has no known economic relevance. Results Here we report on 16 new PanSV full genome sequences sampled throughout Africa and use these together with others in public databases to reveal that PanSV and MSV populations in general share very similar patterns of genetic exchange and geographically structured diversity. A potentially important difference between the species, however, is that the movement of MSV strains throughout Africa is apparently less constrained than that of PanSV strains. Interestingly the MSV-A strain which causes maize streak disease is apparently the most mobile of all the PanSV and MSV strains investigated. Conclusion We therefore hypothesize that the generally increased mobility of MSV relative to other closely related species such as PanSV, may have been an important evolutionary step in the eventual emergence of MSV-A as a serious agricultural pathogen. The GenBank accession numbers for the sequences reported in this paper are GQ415386-GQ415401 PMID:19903330

2009-01-01

6

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

7

Mapping the distribution of maize streak virus genotypes across the forest and transition zones of Ghana.  

PubMed

Throughout sub-Saharan Africa, maize streak virus strain A (MSV-A), the causal agent of maize streak disease (MSD), is an important biological constraint on maize production. In November/December 2010, an MSD survey was carried out in the forest and transition zones of Ghana in order to obtain MSV-A virulence sources for the development of MSD-resistant maize genotypes with agronomic properties suitable for these regions. In 79 well-distributed maize fields, the mean MSD incidence was 18.544 % and the symptom severity score was 2.956 (1 = no symptoms and 5 = extremely severe). We detected no correlation between these two variables. Phylogenetic analysis of cloned MSV-A isolates that were fully sequenced from samples collected in 51 of these fields, together with those sampled from various other parts of Africa, indicated that all of the Ghanaian isolates occurred within a broader cluster of West African isolates, all belonging to the highly virulent MSV-A1 subtype. Besides being the first report of a systematic MSV survey in Ghana, this study is the first to characterize the full-genome sequences of Ghanaian MSV isolates. The 51 genome sequences determined here will additionally be a valuable resource for the rational selection of representative MSV-A variant panels for MSD resistance screening. PMID:25344899

Oppong, Allen; Offei, Samuel K; Ofori, Kwadwo; Adu-Dapaah, Hans; Lamptey, Joseph N L; Kurenbach, Brigitta; Walters, Matthew; Shepherd, Dionne N; Martin, Darren P; Varsani, Arvind

2015-02-01

8

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

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

INFECTIOUS CDNA TRANSCRIPTS OF MAIZE NECROTIC STREAK VIRUS: INFECTIVITY AND TRANSLATIONAL CHARACTERISTICS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The completion of the sequence of Maize necrotic streak virus (MNeSV) indicated a genome of 4094 nt. Northern blotting and primer extension mapping identified two sgRNAs, 1607 nt and 781 nt long. Comparison of the MNeSV and Tomato bushy stunt virus genome sequences indicated that tombusvirus regulat...

11

Nuclear import of Maize fine streak virus proteins in Drosophila S2 cells  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize fine streak virus (MFSV) is a member of the genus Nucleorhabdovirus, family Rhabdoviridae and is transmitted by the leafhopper Graminella nigrifons. The virus replicates in both its plant host and in its insect vector. Nucleorhabdoviruses replicate in the nucleus and assemble at the inner nu...

12

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, Adérito 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

13

Maize Disease Resistance  

Technology Transfer Automated Retrieval System (TEKTRAN)

Worldwide losses in maize due to disease (not including animals or viruses) were estimated to be about 9% in 2001-3 . This varied significantly by region with estimates of 4% in northern Europe and 14% in West Africa and South Asia (http://www.cabicompendium.org/cpc/economic.asp). Losses have tende...

14

Reconstructing the history of maize streak virus strain a dispersal to reveal diversification hot spots and its origin in southern Africa.  

PubMed

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

2011-09-01

15

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

16

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

17

Experimental observations of rapid Maize streak virus evolution reveal a strand-specific nucleotide substitution bias  

PubMed Central

Background Recent reports have indicated that single-stranded DNA (ssDNA) viruses in the taxonomic families Geminiviridae, Parvoviridae and Anellovirus may be evolving at rates of ~10-4 substitutions per site per year (subs/site/year). These evolution rates are similar to those of RNA viruses and are surprisingly high given that ssDNA virus replication involves host DNA polymerases with fidelities approximately 10 000 times greater than those of error-prone viral RNA polymerases. Although high ssDNA virus evolution rates were first suggested in evolution experiments involving the geminivirus maize streak virus (MSV), the evolution rate of this virus has never been accurately measured. Also, questions regarding both the mechanistic basis and adaptive value of high geminivirus mutation rates remain unanswered. Results We determined the short-term evolution rate of MSV using full genome analysis of virus populations initiated from cloned genomes. Three wild type viruses and three defective artificial chimaeric viruses were maintained in planta for up to five years and displayed evolution rates of between 7.4 × 10-4 and 7.9 × 10-4 subs/site/year. Conclusion These MSV evolution rates are within the ranges observed for other ssDNA viruses and RNA viruses. Although no obvious evidence of positive selection was detected, the uneven distribution of mutations within the defective virus genomes suggests that some of the changes may have been adaptive. We also observed inter-strand nucleotide substitution imbalances that are consistent with a recent proposal that high mutation rates in geminiviruses (and possibly ssDNA viruses in general) may be due to mutagenic processes acting specifically on ssDNA molecules. PMID:18816368

van der Walt, Eric; Martin, Darren P; Varsani, Arvind; Polston, Jane E; Rybicki, Edward P

2008-01-01

18

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

19

Wheat curl mite (Acari: Eriophyidae) dispersal and its relationship with kernel red streaking in maize.  

PubMed

Wheat curl mites, Aceria tosichella Keifer, dispersing from wheat (Triticum spp.) to nearby corn (Zea mays L.) fields play a role in the development of kernel red streaking in corn. These studies were undertaken to verify the relationship of wheat curl mite to kernel red streaking, to determine whether wheat is the main source of curl mites dispersing into corn and to determine whether planting corn in temporal or spatial isolation of wheat is a valid management strategy. These studies were conducted on farm fields using sticky traps to monitor mites, followed by sampling mature grain for kernel streaking in southwestern Ontario from 1999 to 2002. The dominant source mites were winter wheat. Mite dispersal occurred during the first 3 wk of winter wheat maturation after the wheat had reached Zadoks stage 87. Mite dispersal corresponded to prevailing winds in the area with the lowest number of mites and the lowest severity of kernel red streaking occurring 60 m from wheat fields planted to the north, south, and east of cornfields and 90 m from wheat fields planted to the west of cornfields. The severity of kernel red streaking was positively correlated with the density of wheat curl mites in corn; however, the correlation was weak and kernel red streaking was still high in many cornfields when few or no mites were present. These findings suggest that wheat curl mite migration into corn is not entirely predictive of the incidence and severity of kernel red streaking. PMID:16334327

Liu, J; Lee, E A; Sears, M K; Schaafsma, A W

2005-10-01

20

Quasispecies nature of three maize streak virus isolates obtained through different modes of selection from a population used to assess response to infection of maize cultivars.  

PubMed

Three maize streak virus (MSV) isolates were derived from an MSV population used to assess the response to infection of maize cultivars. Isolate SP1 was obtained from this population through short acquisition and inoculation periods (1 and 5 min, respectively), using a single Cicadulina mbila vector. Isolate SP2 was derived from SP1 after transmission to a wild perennial host (Coix lacryma-jobi), on which it was maintained for about 4 years without insect transmission. Isolate N2A, the most pathogenic isolate, was obtained from the initial population after serial passages on almost completely resistant inbred maize lines. The complexity of each isolate was analysed by RFLP analysis and sequencing based on 120 SP1 clones, 36 SP2 clones and 40 N2A clones. All three isolates were composed of different but related clones, consistent with a quasispecies structure. The mutations were distributed throughout the genome. Mutation frequencies, based on all available sequences, were 3.8 x 10(-4) for SP1, 10.5 x 10(-4) for SP2 and 6.9 x 10(-4) for N2A. As expected from the bottleneck selection step, the intra-isolate variability of SP1 was relatively low. Comparison between SP1 and SP2 showed that SP1 heterogeneity increased during maintenance on the wild host. Furthermore, the consensus sequences of SP1 and SP2 differed by two non-synonymous substitutions in the complementary sense gene repA. N2A had a relatively low degree of heterogeneity, but was composed of several sub-populations. The results reflect the influence of the mode of selection of MSV isolates on their quasispecies organization, i.e. distribution of variants, and master sequence. PMID:9880027

Isnard, M; Granier, M; Frutos, R; Reynaud, B; Peterschmitt, M

1998-12-01

21

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

PubMed

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

Tatineni, Satyanarayana; French, Roy

2014-02-01

22

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

PubMed

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

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

2014-01-01

23

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

PubMed

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

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

2012-12-01

24

Efficient transmission of Cassava brown streak disease viral pathogens by chip bud grafting  

PubMed Central

Background Techniques to study plant viral diseases under controlled growth conditions are required to fully understand their biology and investigate host resistance. Cassava brown streak disease (CBSD) presents a major threat to cassava production in East Africa. No infectious clones of the causal viruses, Cassava brown streak virus (CBSV) or Ugandan cassava brown streak virus (UCBSV) are available, and mechanical transmission to cassava is not effective. An improved method for transmission of the viruses, both singly and as co-infections has been developed using bud grafts. Findings Axillary buds from CBSD symptomatic plants infected with virulent isolates of CBSV and UCBSV were excised and grafted onto 6–8 week old greenhouse-grown, disease-free cassava plants of cultivars Ebwanateraka, TME204 and 60444. Plants were assessed visually for development of CBSD symptoms and by RT-PCR for presence of the viruses in leaf and storage root tissues. Across replicated experiments, 70-100% of plants inoculated with CBSV developed CBSD leaf and stem symptoms 2–6 weeks after bud grafting. Infected plants showed typical, severe necrotic lesions in storage roots at harvest 12–14 weeks after graft inoculation. Sequential grafting of buds from plants infected with UCBSV followed 10–14 days later by buds carrying CBSV, onto the same test plant, resulted in 100% of the rootstocks becoming co-infected with both pathogens. This dual transmission rate was greater than that achieved by simultaneous grafting with UCBSV and CBSV (67%), or when grafting first with CBSV followed by UCBSV (17%). Conclusions The bud grafting method described presents an improved tool for screening cassava germplasm for resistance to CBSD causal viruses, and for studying pathogenicity of this important disease. Bud grafting provides new opportunities compared to previously reported top and side grafting systems. Test plants can be inoculated as young, uniform plants of a size easily handled in a small greenhouse or large growth chamber and can be inoculated in a controlled manner with CBSV and UCBSV, either singly or together. Disease symptoms develop rapidly, allowing better studies of interactions between these viral pathogens, their movement within shoot and root systems, and how they induce their destructive disease symptoms. PMID:24314370

2013-01-01

25

Mapping Disease Resistance QTL for Three Foliar Diseases of Maize in a RIL Population  

Technology Transfer Automated Retrieval System (TEKTRAN)

Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB) are three important foliar diseases impacting maize production. The objectives of this study were to identify quantitative trait loci for disease resistance (dQTL) for resistance to these diseases in a maize recombinan...

26

IDENTIFICATION AND ANALYSIS OF DISEASE RESISTANCE LOCI IN MAIZE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The majority of disease resistance used in maize is quantitative in nature, i.e. it is not complete but is sufficient to protect yield. Quantitative resistance is generally extremely durable. Very little is known about the molecular or physiological basis of quantitative disease resistance in mai...

27

Role of Dehydrodiferulates in Maize Resistance to Pests and Diseases  

PubMed Central

Phenolic esters have attracted considerable interest due to the potential they offer for peroxidase catalysed cross-linking of cell wall polysaccharides. Particularly, feruloyl residues undergo radical coupling reactions that result in cross-linking (intra-/intermolecular) between polysaccharides, between polysaccharides and lignin and, between polysaccharides and proteins. This review addresses for the first time different studies in which it is established that cross-linking by dehydrodiferulates contributes to maize’s defences to pests and diseases. Dehydrodiferulate cross-links are involved in maize defence mechanisms against insects such as the European, Mediterranean, and tropical corn borers and, storage pest as the maize weevil. In addition, cross-links are also discussed to be involved in genetic resistance of maize to fungus diseases as Gibberella ear and stalk rot. Resistance against insects and fungus attending dehydrodiferulates could go hand in hand. Quantitative trait loci mapping for these cell wall components could be a useful tool for enhancing resistance to pest and diseases in future breeding programs. PMID:20386661

Santiago, Rogelio; Malvar, Rosa A.

2010-01-01

28

EVALUATION OF RESISTANCE TO WHEAT SPINDLE STREAK MOSAIC VIRUS BY ANALYSIS OF DISEASE INCIDENCE DATA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Once Wheat spindle streak mosaic virus (WSSMV) becomes established in a field, the only available control tactic is the planting of resistant genotypes. In this study we assessed 113 genotypes of autumn-sown wheat, rye, triticale, and barley for resistance to WSSMV in a three-year trial in a field t...

29

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

30

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

31

Streaked Plain  

NASA Technical Reports Server (NTRS)

4 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark streaks created by dust devils on a plain southwest of Hellas Planitia. Based on the width and the length of individual streaks in this scene, it is clear that not all dust devils are created equally.

Location near: 55.8oS, 317.5oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

2006-01-01

32

The nucleotide sequence and genome structure of the geminivirus miscanthus streak virus  

Microsoft Academic Search

A tandem dimer of miscanthus streak virus (MiSV) DNA was inserted into the T-DNA of the binary plasmid vector pBIN19 and agroinoculated into several monocotyledonous plants (monocots) using Agrobacterium tumefaciens or A. rhizogenes. Disease symptoms and geminate particles were produced in maize and Panicum milaceum plants, and MiSV- specific double-stranded and single-stranded DNAs were found in these plants. The nucleotide

Masaaki Chatani; Yoshinori Matsumoto; Haruyoshi Mizuta; Masato Ikegami; Margaret I. Boulton; Jeffrey W. Davies

1991-01-01

33

Development of a genetic linkage map of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in bananas (Musa spp.) using SSR and DArT markers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mycosphaerella fijiensis is the causal agent of black leaf streak (BLS) disease in bananas. This pathogen threatens global banana production as the main export cultivars are highly susceptible. As a consequence, commercial banana plantations must be protected chemically with fungicides; up to 40 app...

34

Development of VNTR Markers to Assess Genetic Diversity of Mycosphaerella Fijiensis, the Causal Agent of Black Leaf Streak Disease in Bananas (Musa spp.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mycosphaerella fijiensis is the causal agent of black leaf streak (BLS) disease in bananas. This pathogen threatens global banana production as the main export cultivars are highly susceptible. As a consequence, commercial banana plantations must be protected chemically with fungicides; up to 40 app...

35

Variable Number of Tandem Repeat Markers in the Genome Sequence of Mycosphaerella Fijiensis, the Causal Agent of Black Leaf Streak Disease of Banana (Musa spp.)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Mycosphaerella fijiensis, the causal agent of banana leaf streak disease (commonly known as black Sigatoka), is the most devastating pathogen attacking bananas (Musa spp). Recently the whole genome sequence of M. fijiensis became available. This sequence was screened for the presence of Variable Num...

36

Fumonisin biomarkers in maize eaters and implications for human disease  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize is the predominant food source contaminated by fumonisins and this has particular health risks for communities consuming maize as a staple diet. The main biochemical effect of fumonisins is the inhibition of ceramide biosynthesis causing an increase in sphingoid bases and sphingoid base 1-pho...

37

Co-infection and disease severity of Maize dwarf mosaic virus and Maize chlorotic dwarf virus strains  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two major maize viruses have been reported in the United States: Maize dwarf mosaic virus (MDMV) and Maize chlorotic dwarf virus (MCDV). These viruses co-occur in regions where maize is grown such that co-infections are likely. Co-infection of different strains of MCDV is also observed frequently...

38

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

PubMed Central

Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) are expected to be under positive selection pressure. To address the hypothesis that naturally occurring allelic variation conditions MDR, we extended the framework of structured association mapping to allow for the analysis of correlated complex traits and the identification of pleiotropic genes. The multivariate analytical approach used here is directly applicable to any species and set of traits exhibiting correlation. From our analysis of a diverse panel of maize inbred lines, we discovered high positive genetic correlations between resistances to three globally threatening fungal diseases. The maize panel studied exhibits rapidly decaying linkage disequilibrium that generally occurs within 1 or 2 kb, which is less than the average length of a maize gene. The positive correlations therefore suggested that functional allelic variation at specific genes for MDR exists in maize. Using a multivariate test statistic, a glutathione S-transferase (GST) gene was found to be associated with modest levels of resistance to all three diseases. Resequencing analysis pinpointed the association to a histidine (basic amino acid) for aspartic acid (acidic amino acid) substitution in the encoded protein domain that defines GST substrate specificity and biochemical activity. The known functions of GSTs suggested that variability in detoxification pathways underlie natural variation in maize MDR. PMID:21490302

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

2011-01-01

39

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

2013-01-01

40

Targeted discovery of quantitative trait loci for resistance to northern leaf blight and other diseases of maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

To capture diverse alleles at a set of loci associated with disease resistance in maize, heterogeneous inbred family (HIF) analysis was applied for targeted QTL mapping and near-isogenic line (NIL) development. Tropical maize lines CML52 and DK888 were chosen as donors of alleles based on their know...

41

Plant-Plant-Microbe Mechanisms Involved in Soil-Borne Disease Suppression on a Maize and Pepper Intercropping System  

PubMed Central

Background Intercropping systems could increase crop diversity and avoid vulnerability to biotic stresses. Most studies have shown that intercropping can provide relief to crops against wind-dispersed pathogens. However, there was limited data on how the practice of intercropping help crops against soil-borne Phytophthora disease. Principal Findings Compared to pepper monoculture, a large scale intercropping study of maize grown between pepper rows reduced disease levels of the soil-borne pepper Phytophthora blight. These reduced disease levels of Phytophthora in the intercropping system were correlated with the ability of maize plants to form a “root wall” that restricted the movement of Phytophthora capsici across rows. Experimentally, it was found that maize roots attracted the zoospores of P. capsici and then inhibited their growth. When maize plants were grown in close proximity to each other, the roots produced and secreted larger quantities of 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA) and 6-methoxy-2-benzoxazolinone (MBOA). Furthermore, MBOA, benzothiazole (BZO), and 2-(methylthio)-benzothiazole (MBZO) were identified in root exudates of maize and showed antimicrobial activity against P. capsici. Conclusions Maize could form a “root wall” to restrict the spread of P. capsici across rows in maize and pepper intercropping systems. Antimicrobe compounds secreted by maize root were one of the factors that resulted in the inhibition of P. capsici. These results provide new insights into plant-plant-microbe mechanisms involved in intercropping systems. PMID:25551554

Mei, Xinyue; Liao, Jingjing; Ding, Xupo; Deng, Weiping; Fan, Limin; He, Xiahong; Vivanco, Jorge M.; Li, Chengyun; Zhu, Youyong; Zhu, Shusheng

2014-01-01

42

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

PubMed Central

Background Rice and maize dwarf diseases caused by the newly introduced Southern rice black-streaked dwarf virus (SRBSDV) have led to severe economic losses in South China in recent years. The distribution and diversity of SRBSDV have not been investigated in the main rice and maize growing areas in China. In this study, the distribution of SRBSDV in China was determined by using reverse transcription-polymerase chain reaction (RT-PCR). Results Between 2009 and 2010, 2404 plant samples (2294 rice, 110 maize samples, and more than 300 cultivars) with dwarf symptoms were collected from fields in 194 counties of 17 provinces in China and SRBSDV was detected. The results indicated that 1545 (64.27%) of samples (both rice and maize) were infected with SRBSDV. SRBSDV was detected widely in Hainan, Guangdong, Guangxi, Yunnan, Guizhou, Chongqing, Fujian, Jiangxi, Hunan, Hubei, Anhui, Jiangsu, and Zhejiang provinces, which suggests SRBSDV is an important pathogen causing rice dwarfing diseases in South China. Phylogenetic analysis of 15 representative virus isolates revealed that SRBSDV isolates in China had high levels of nucleotide and amino acid sequence identities (>97.8%). Conclusions SRBSDV spreads naturally in Yangtze River basin and south region, the location of the major rice production areas. In comparison, the virus rarely spreads north of Yangtze River in North China. Distribution of SRBSDV is consistent with the migrating and existing ranges of its vector WBPH, suggesting that SRBSDV might be introduced into South China along with the migration of viruliferous WBPH. PMID:24131521

2013-01-01

43

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

44

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

45

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

46

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

47

Wheat Streak Mosaic Virus  

E-print Network

E-337 1/05 Gaylon Morgan, State Extension Small Grains Specialist, College Station, TX Carl Patrick, Extension Entomologist, Amarillo, TX Karl Steddom and Charlie Rush, Plant Pathologists, Amarillo, TX W Overview of WSMV and HPV Wheat Streak Mosaic...

Morgan, Gaylon

2005-01-26

48

Wind Streak Changes  

NASA Technical Reports Server (NTRS)

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

2004-01-01

49

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

50

Huygens Wind Streak  

NASA Technical Reports Server (NTRS)

19 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the results of wind action on the floor of the giant martian impact basin, Huygens. The large crater in this image has a wind streak on its lee side, pointing toward the lower right (southeast). Usually, a light-toned wind streak behind a crater on Mars will be composed of a thin veneer of dust that the wind was not able to erode because it was protected by the presence of the crater's raised rims. In this case, the streak is caused by something different -- by the fact that dark, windblown sand has not been able to accumulate behind the crater.

Location near: 13.0oS, 303.7oW Image width: width: 3 km (1.9 mi) Illumination from: lower left Season: Southern Spring

2005-01-01

51

Polar Dust Devil Streaks  

NASA Technical Reports Server (NTRS)

30 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of dunes in the martian north polar region is important because it shows one of the highest northern latitude views of streaks thought to be made by passing dust devils. The dark, thin, filamentary streaks on the dunes and on the adjacent plains were probably formed by dust devils. The dunes occur near 76.6oN, 62.7oW. Dust devil streaks are observed on Mars at very high latitudes, such as this, all the way down to the equator. They are also seen at all elevations, from the deepest parts of the Hellas Basin to the summit of Olympus Mons. This picture covers an area about 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

2004-01-01

52

Oxidative stress response of Mycosphaerella fijiensis, the causal agent of black leaf streak disease in banana plants, to hydrogen peroxide and paraquat.  

PubMed

Mycosphaerella fijiensis causes black leaf streak disease in banana and plantain. This fungus is usually attacked by reactive oxygen species secreted by the plant or during exposure to fungicide, however, little is known about the antioxidant response of the fungus. In this study, mycelia were observed to totally decompose 30 mmol/L of hydrogen peroxide (H2O2) within 120 min, liberating oxygen bubbles, and also to survive in concentrations as high as 100 mmol/L H2O2. The oxidative stress responses to H2O2, paraquat, and hydroquinone were characterized in terms of the activities of catalase and superoxide dismutase (SOD). Two active catalase bands were seen in native PAGE induced by H2O2. Band I had monofunctional activity and band II had bifunctional catalase-peroxidase activity. Two isozymes of SOD, distinguishable by their cyanide sensitivity, were found; CuZnSOD was the main one. The combination of H2O2 and 3-aminotriazole reduced the accumulation of biomass up to 40% compared with exposure to H2O2 alone, suggesting that catalase is important for the rapid decomposition of H2O2 and has a direct bearing on cell viability. The results also suggest that the superoxide anion formed through the redox of paraquat and hydroquinone has a greater effect than H2O2 on the cellular viability of M. fijiensis. PMID:19767862

Beltrán-García, Miguel J; Manzo-Sanchez, Gilberto; Guzmán-González, Salvador; Arias-Castro, Carlos; Rodríguez-Mendiola, Martha; Avila-Miranda, Martin; Ogura, Tetsuya

2009-07-01

53

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

54

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

55

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

PubMed Central

Background Gray leaf spot (GLS) is a globally important foliar disease of maize. Cercospora zeina, one of the two fungal species that cause the disease, is prevalent in southern Africa, China, Brazil and the eastern corn belt of the USA. Identification of QTL for GLS resistance in subtropical germplasm is important to support breeding programmes in developing countries where C.?zeina limits production of this staple food crop. Results A maize RIL population (F7:S6) from a cross between CML444 and SC Malawi was field-tested under GLS disease pressure at five field sites over three seasons in KwaZulu-Natal, South Africa. Thirty QTL identified from eleven field trials (environments) were consolidated to seven QTL for GLS resistance based on their expression in at least two environments and location in the same core maize bins. Four GLS resistance alleles were derived from the more resistant parent CML444 (bin 1.10, 4.08, 9.04/9.05, 10.06/10.07), whereas the remainder were from SC Malawi (bin 6.06/6.07, 7.02/7.03, 9.06). QTLs in bin 4.08 and bin 6.06/6.07 were also detected as joint QTLs, each explained more than 11% of the phenotypic variation, and were identified in four and seven environments, respectively. Common markers were used to allocate GLS QTL from eleven previous studies to bins on the IBM2005 map, and GLS QTL “hotspots” were noted. Bin 4.08 and 7.02/7.03 GLS QTL from this study overlapped with hotspots, whereas the bin 6.06/6.07 and bin 9.06 QTLs appeared to be unique. QTL for flowering time (bin 1.07, 4.09) in this population did not correspond to QTL for GLS resistance. Conclusions QTL mapping of a RIL population from the subtropical maize parents CML444 and SC Malawi identified seven QTL for resistance to gray leaf spot disease caused by C.?zeina. These QTL together with QTL from eleven studies were allocated to bins on the IBM2005 map to provide a basis for comparison. Hotspots of GLS QTL were identified on chromosomes one, two, four, five and seven, with QTL in the current study overlapping with two of these. Two QTL from this study did not overlap with previously reported QTL. PMID:24885661

2014-01-01

56

Stolbur Phytoplasma Transmission to Maize by Reptalus panzeri and the Disease Cycle of Maize Redness in Serbia  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize redness (MR), induced by stolbur phytoplasma (Candidatus Phytoplasma solani, subgroup 16SrXII-A), is characterized by midrib, leaf and stalk reddening and abnormal ear development. MR has been reported from Serbia, Romania and Bulgaria for 50 years, and recent epiphytotics reduced yields by 4...

57

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

58

Dunes and Wind Streaks  

NASA Technical Reports Server (NTRS)

12 June 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows small, dark, north polar sand dunes and attendant wind streaks located near 76.7oN, 317.6oW. The dominant winds responsible for these features blow from the southwest (lower left). The image covers an area about 3 km (1.9 mi) across. The scene is illuminated by sunlight from the lower left.

2004-01-01

59

Disruption of ceramide biosynthesis and accumulation of sphingoid bases and sphingoid base 1-phosphates: A mechanism for Fusarium verticillioides effects in maize-seedling disease.  

Technology Transfer Automated Retrieval System (TEKTRAN)

In sweet corn at the seedling and seed maturation stages, Fusarium can be a serious field problem. The fungus Fusarium verticillioides infects maize and produces fumonisins, inhibitors of ceramide synthase. To determine the role of fumonisins in maize seedling disease, seeds were inoculated with fu...

60

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

Microsoft Academic Search

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

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

61

Wheat Cultivar-Specific Disease Synergism and Alteration of Virus Accumulation During Co-Infection with Wheat Streak Mosaic Virus and Triticum Mosaic Virus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Triticum mosaic virus (TriMV), the type member of the newly proposed Poacevirus genus and Wheat streak mosaic virus (WSMV), the type member of Tritimovirus genus of the family Potyviridae, infect wheat naturally in the Great Plains and are transmitted by wheat curl mites. In this study, we examined ...

62

Triton's streaks as windblown dust  

NASA Technical Reports Server (NTRS)

Explanations for the surface streaks observed by Voyager 2 on Triton's southern hemisphere are discussed. It is shown that, despite Triton's tenuous atmosphere, low-cohesion dust trains with diameters of about 5 micron or less may be carried into suspension by aeolian surface shear stress, given expected geostrophic wind speeds of about 10 m/s. For geyser-like erupting dust plumes, it is shown that dust-settling time scales and expected wind velocities can produce streaks with length scales in good agreement with those of the streaks. Thus, both geyserlike eruptions or direct lifting by surface winds appear to be viable mechanisms for the origin of the streaks.

Sagan, Carl; Chyba, Christopher

1990-01-01

63

FINE MAPPING AND NEAR ISOGENIC LINES FOR THREE WHEAT STREAK MOSAIC VIRUS (WSMV) RESISTANCE GENES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three independent genes controlling resistance to Wheat streak mosaic virus (WSMV; family Potyviridae; genus Tritimovirus) were previously identified on chromosomes six (Wsm1), three (Wsm2) and ten (Wsm3) in the resistant maize (Zea mays L.) inbred line Pa405. Near isogenic lines (NIL) carrying the...

64

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

PubMed Central

Background Within-field multiple crop species intercropping is well documented and used for disease control, but the underlying mechanisms are still unclear. As roots are the primary organ for perceiving signals in the soil from neighboring plants, root behavior may play an important role in soil-borne disease control. Principal Findings In two years of field experiments, maize/soybean intercropping suppressed the occurrence of soybean red crown rot, a severe soil-borne disease caused by Cylindrocladium parasiticum (C. parasiticum). The suppressive effects decreased with increasing distance between intercropped plants under both low P and high P supply, suggesting that root interactions play a significant role independent of nutrient status. Further detailed quantitative studies revealed that the diversity and intensity of root interactions altered the expression of important soybean PR genes, as well as, the activity of corresponding enzymes in both P treatments. Furthermore, 5 phenolic acids were detected in root exudates of maize/soybean intercropped plants. Among these phenolic acids, cinnamic acid was released in significantly greater concentrations when intercropped maize with soybean compared to either crop grown in monoculture, and this spike in cinnamic acid was found dramatically constrain C. parasiticum growth in vitro. Conclusions To the best of our knowledge, this study is the first report to demonstrate that intercropping with maize can promote resistance in soybean to red crown rot in a root-dependent manner. This supports the point that intercropping may be an efficient ecological strategy to control soil-borne plant disease and should be incorporated in sustainable agricultural management practices. PMID:24810161

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

2014-01-01

65

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; )

2000-09-12

66

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

67

The Streak Camera Development at LLE  

SciTech Connect

The Diagnostic Development Group at the Laboratory for Laser Energetics has endeavored to build a stand-alone, remotely operated streak camera with comprehensive autofocus and self-calibration capability. Designated as the Rochester Optical Streak System (ROSS), it is a generic streak camera platform, capable of accepting a variety of streak tubes. The system performance is limited by the installed tube's electron optics, not by any camera subsystem. Moreover, the ROSS camera can be photometrically calibrated.

Jaanimagi, P.A.; Boni. R.; Butler, D.; Ghosh, S.; Donaldson, W.R.; Keck, R.L.

2005-03-31

68

Fumonisin production is necessary for development of the full spectrum of symptoms indicative of Fusarium verticillioides maize-seedling disease and evidence for disruption of sphingolipid metabolism as the proximate cause.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fungus Fusarium verticillioides infects maize and produces fumonisins, inhibitors of ceramide synthase. To determine the role of fumonisins in maize seedling disease, seeds were inoculated with fumonisin producing or non-producing strains of F. verticillioides. Seedlings grown from seeds inocul...

69

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

70

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

PubMed

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

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

2013-01-01

71

Different Responses of Two Genes Associated with Disease Resistance Loci in Maize (Zea mays L.) to 3-allyloxy-1,2-benzothiazole 1,1-dioxide  

Microsoft Academic Search

Probenazole (3-allyloxy-1,2-benzothiazole 1,1-dioxide, PBZ) is a bactericide and fungicide that acts by inducing plant defense systems. It has been shown to induce the expression of NBS-LRR genes like RPR1 (rice probenazole-response gene) in rice (Oryza sativa L.) and systemic acquired resistance (SAR)-like disease resistance. Two maize (Zea mays L.) genes Zmnbslrr1 (a NBS-LRR gene, cloned from a disease resistance analog

Jiazheng Yuan; Jennifer Tedman; Liakat Ali; Jie Liu; Jeff Taylor; David Lightfoot

72

A porphyrin pathway impairment is responsible for the phenotype of a dominant disease lesion mimic mutant of maize.  

PubMed

The maize lesion mimic gene Les22 is defined by dominant mutations and characterized by the production of minute necrotic spots on leaves in a developmentally specified and light-dependent manner. Phenotypically, Les22 lesions resemble those that are triggered during a hypersensitive disease resistance response of plants to pathogens. We have cloned Les22 by using a Mutator-tagging technique. It encodes uroporphyrinogen decarboxylase (UROD), a key enzyme in the biosynthetic pathway of chlorophyll and heme in plants. Urod mutations in humans are also dominant and cause the metabolic disorder porphyria, which manifests itself as light-induced skin morbidity resulting from an excessive accumulation of photoexcitable uroporphyrin. The phenotypic and genetic similarities between porphyria and Les22 along with our observation that Les22 is also associated with an accumulation of uroporphyrin revealed what appears to be a case of natural porphyria in plants. PMID:9668130

Hu, G; Yalpani, N; Briggs, S P; Johal, G S

1998-07-01

73

Fiber-optic spectral-streak equalizer  

SciTech Connect

A spectral-streak equalizer was developed for use with an electronic streak camera to correct for material dispersion in optical fibers. Material dispersion occurs because different wavelengths of light travel at different speeds through glass fibers; the resulting difference in transit times broadens light pulses, which can lead to errors in certain scientific applications. This new instrument combines optical equalization and streak equalization techniques; it uses an array of optical fibers, as in the optical equalization technique, to partially compensate for the dispersion and uses the streak camera dynamics, as in the streak equalization technique, to complete the compensation. This paper examines the principles of equalization and compares several techniques, enumerates general and specific design considerations, outlines the calibration procedure, details efficiency estimates, describes testing techniques, gives calibration data and test results for spectral-streak equalizers currently in use, and draws conclusions from recent experience with these devices.

Reedy, R.P.; Roeske F. Jr.; Smith, D.E.

1985-07-01

74

Overexpression of rice black-streaked dwarf virus p7-1 in Arabidopsis results in male sterility due to non-dehiscent anthers.  

PubMed

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, is propagatively transmitted by the small brown planthopper (Laodelphax striatellus Fallén). RBSDV causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China. Although several RBSDV proteins have been studied in detail, the functions of the nonstructural protein P7-1 are still largely unknown. To investigate the role of the P7-1 protein in virus pathogenicity, transgenic Arabidopsis thaliana plants were generated in which the P7-1 gene was expressed under the control of the 35S promoter. The RBSDV P7-1-transgenic Arabidopsis plants (named P7-1-OE) were male sterility. Flowers and pollen from P7-1-transgenic plants were of normal size and shape, and anthers developed to the normal size but failed to dehisce. The non-dehiscent anthers observed in P7-1-OE were attributed to decreased lignin content in the anthers. Furthermore, the reactive oxygen species levels were quite low in the transgenic plants compared with the wild type. These results indicate that ectopic expression of the RBSDV P7-1 protein in A. thaliana causes male sterility, possibly through the disruption of the lignin biosynthesis and H2O2-dependent polymerization pathways. PMID:24260239

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

2013-01-01

75

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

PubMed Central

Rice black-streaked dwarf virus (RBSDV), a member of the genus Fijivirus in the family Reoviridae, is propagatively transmitted by the small brown planthopper (Laodelphax striatellus Fallén). RBSDV causes rice black-streaked dwarf and maize rough dwarf diseases, which lead to severe yield losses in crops in China. Although several RBSDV proteins have been studied in detail, the functions of the nonstructural protein P7-1 are still largely unknown. To investigate the role of the P7-1 protein in virus pathogenicity, transgenic Arabidopsis thaliana plants were generated in which the P7-1 gene was expressed under the control of the 35S promoter. The RBSDV P7-1-transgenic Arabidopsis plants (named P7-1-OE) were male sterility. Flowers and pollen from P7-1-transgenic plants were of normal size and shape, and anthers developed to the normal size but failed to dehisce. The non-dehiscent anthers observed in P7-1-OE were attributed to decreased lignin content in the anthers. Furthermore, the reactive oxygen species levels were quite low in the transgenic plants compared with the wild type. These results indicate that ectopic expression of the RBSDV P7-1 protein in A. thaliana causes male sterility, possibly through the disruption of the lignin biosynthesis and H2O2-dependent polymerization pathways. PMID:24260239

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

2013-01-01

76

ZmPep1, an ortholog of Arabidopsis elicitor peptide 1, regulates maize innate immunity and enhances disease resistance.  

PubMed

ZmPep1 is a bioactive peptide encoded by a previously uncharacterized maize (Zea mays) gene, ZmPROPEP1. ZmPROPEP1 was identified by sequence similarity as an ortholog of the Arabidopsis (Arabidopsis thaliana) AtPROPEP1 gene, which encodes the precursor protein of elicitor peptide 1 (AtPep1). Together with its receptors, AtPEPR1 and AtPEPR2, AtPep1 functions to activate and amplify innate immune responses in Arabidopsis and enhances resistance to both Pythium irregulare and Pseudomonas syringae. Candidate orthologs to the AtPROPEP1 gene have been identified from a variety of crop species; however, prior to this study, activities of the respective peptides encoded by these orthologs were unknown. Expression of the ZmPROPEP1 gene is induced by fungal infection and treatment with jasmonic acid or ZmPep1. ZmPep1 activates de novo synthesis of the hormones jasmonic acid and ethylene and induces the expression of genes encoding the defense proteins endochitinase A, PR-4, PRms, and SerPIN. ZmPep1 also stimulates the expression of Benzoxazineless1, a gene required for the biosynthesis of benzoxazinoid defenses, and the accumulation of 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside in leaves. To ascertain whether ZmPep1-induced defenses affect resistance, maize plants were pretreated with the peptide prior to infection with fungal pathogens. Based on cell death and lesion severity, ZmPep1 pretreatment was found to enhance resistance to both southern leaf blight and anthracnose stalk rot caused by Cochliobolis heterostrophus and Colletotrichum graminicola, respectively. We present evidence that peptides belonging to the Pep family have a conserved function across plant species as endogenous regulators of innate immunity and may have potential for enhancing disease resistance in crops. PMID:21205619

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

2011-03-01

77

Laminar streak enhancement using streamwise grooves  

NASA Astrophysics Data System (ADS)

Laminar streak promotion in a flat plate boundary layer results in an increase of the stability of the Tollmien-Schlichting waves with respect to that of the 2D Blasius profile. This stabilization delays the laminar-turbulent transition, increasing the laminar phase of the flow. The stabilization effect is stronger for higher streak amplitudes, and therefore simple ways of generating high amplitude stable streaks are sought to be used as boundary layer flow control methods. In a recent experiment [Tallamelli & Franson,AIAA 2010-4291] high amplitude stable steady streaks have been produced using Miniature Vortex Generators (MGVs), where one array of MGVs is used to excite the streak and a second array is used downstream to enhance their amplitude. In this presentation we numerically explore the possibility of enhancing the streaks using a different passive mechanism: streamwise grooves carved in the plate. We will present some numerical simulations for different values of the spanwise period of the streaks and of the grooves, and we will show the combinations that provide maximum streak amplitude.

Martel, Carlos; Ángel Martín, Juan

2011-11-01

78

Purification and some properties of reovirus-like particles from leafhoppers and their possible involvement in wallaby ear disease of maize.  

PubMed

Reovirus-like particles, occurring in association with viroplasms, crystalline arrays and tubules, in the cytoplasm of Cicadulina bimaculata capable of inducing wallaby ear disease in maize, were purified from the insects by differential centrifugation, treatment with the nonionic detergent, Nonidet P-40, and sucrose density gradient centrifugation. The purified particles have a double-shelled icosahedral structure about 70 nm in diameter with external projections (A spikes) about 10 nm long located at the 12 vertices. These intact particles (IPs) are morphologically similar to those of Fiji disease virus (FDV), but are more stable. Cores were produced by enzymatic digestion of IPs with alpha-chymotrypsin. The cores are icosahedra about 57 nm in diameter with projections (B spikes) located at the 12 vertices, resembling those of FDV and cytoplasmic polyhedrosis virus. Immunization of a rabbit with purified IPs resulted in the production of antibodies specific to IPs, cores, and dsRNA. Immunoelectron microscopic investigations revealed that there is no relationship between this virus and FDV, maize rough dwarf, oat sterile dwarf, pangola stunt, and rice ragged stunt viruses, all members of the genus Fijivirus in the family Reoviridae. The nucleic acid extracted from partially purified virus was resolved into 10 segments by polyacrylamide gel electrophoresis. Reovirus-like particles or viroplasms could not be detected in thin sections of maize seedlings colonized by C. bimaculata showing wallaby ear symptoms. In the light of these data the possible etiology of wallaby ear disease is discussed. PMID:18631635

Boccardo, G; Hatta, T; Francki, R I; Grivell, C J

1980-01-30

79

The Domestication of Maize The Maize Genome  

E-print Network

The Domestication of Maize The Maize Genome Maize Genetics in the 20th Century The Future From Gene Discovery to Application The Dynamic Maize Genome Corn, also known as maize (from the Spanish maíz these bigger spikes, and thus the remarkable events of domestication began. By studying the maize genome

Napp, Nils

80

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

PubMed

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

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

2013-01-01

81

Enhanced Virus Resistance in Transgenic Maize Expressing a dsRNA-Specific Endoribonuclease Gene from E. coli  

PubMed Central

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

Liu, He; Tian, Lanzhi; Zhang, Aihong; Zhang, Yanjing; Shi, Lindan; Guo, Bihong; Xu, Jin; Duan, Xifei; Wang, Xianbing; Han, Chenggui; Miao, Hongqin; Yu, Jialin; Li, Dawei

2013-01-01

82

Banana streak virus is very diverse in Uganda.  

PubMed

Banana streak virus (BSV) is a badnavirus that causes a viral leaf streak disease of banana and plantain (Musa spp.). Identified in essentially all Musa growing areas of the world, it has a deleterious effect on the productivity of infected plants as well as being a major constraint to Musa breeding programmes and germplasm dissemination. Banana is a staple food in Uganda which is, per capita, one of the worlds largest banana producers and consumers. BSV was isolated from infected plants sampled across the Ugandan Musa growing area and the isolates were analysed using molecular and serological techniques. These analyses showed that BSV is very highly variable in Uganda. They suggest that the variability is, in part, due to a series of introductions of banana into Uganda, each with a different complement of infecting viruses. PMID:15036835

Harper, Glyn; Hart, Darren; Moult, Sarah; Hull, Roger

2004-03-01

83

Electro-optic Phase Grating Streak Spectrometer  

SciTech Connect

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

Goldin, F. J.

2012-08-02

84

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

85

Streak breakup in turbulent boundary layers  

NASA Astrophysics Data System (ADS)

Direct numerical simulations are used to compute the evolution of a single streak in a laminar boundary layer (Re* = 450) and a turbulent boundary on a flat plate at zero pressure gradient (Re* = 900). The single streak is formed through fluid injection at the wall as in Acarlar and Smith (1987). It is found that the single streak undergoes an instability resulting in the formation of hairpin vortices. The resulting flow field is in very good agreement with the experimental results of Acarlar and Smith (1987). The instability can be explained through an Orr-Sommerfeld analysis of the velocity profile on the plane of symmetry of the streak. The predicted wavelength and eigenfunctions are in very good agreement with those obtained from the simulations. Application of the same analysis to streaks in a fully turbulent boundary layer reveal as good an agreement. It is argued that this instability is the basic mechanism responsible for streak breakup. Acarlar, M.S. and Smith, C.R., 1987. A study of hairpin vortices in a laminar boundary layer. Part 2. Hairpin vortices generated by fluid injection. J. Fluid Mech., 175, pp. 43-83.

Haritonidis, Joseph H.; Skote, Martin

1999-11-01

86

High plains disease of corn and wheat: ultrastructural and serological aspects.  

PubMed

Virus-like particles with unique size and morphology were consistently associated with a new eriophyid mite-borne disease of maize and wheat, the high plains disease. In cells of symptomatic leaves, double membrane-bound particles (DMPs), quasi-spherical structures 120-200 nm in diameter, were present throughout the cytoplasm in association with electron-dense amorphous inclusions. No DMPs and inclusions were observed in symptomless plants. The DMPs were morphologically indistinguishable from those associated with eriophyid mite-borne diseases of uncertain etiology: fig mosaic, rose rosette, yellow ringspot of redbud, thistle mosaic, wheat spot chlorosis and wheat spot mosaic diseases. The DMPs and associated viroplasm-like inclusions in maize and wheat were specifically immunogold labeled in situ with an antiserum to the 32 kDa protein associated specifically with the high plains disease. Thread-like structures, present in the purified preparations from diseased maize were also immunogold labeled with the antiserum. It is suggested that the thread-like structures are derived from the DMPs. In many cells of symptomatic maize and wheat samples, DMPs occurred together with flexuous rod-shaped particles and cylindrical inclusions of wheat streak mosaic potyvirus (WSMV), indicating that these cells are infected doubly with WSMV and the agent represented by the DMPs. PMID:9851064

Ahn, K K; Kim, K S; Gergerich, R C; Jensen, S G

1998-10-01

87

The Primitive Streak, Cross Section  

NSDL National Science Digital Library

This FlashTM animation is the third of a seven part series that presents the primitive streak from different angles. This installment displays the cross section, which is conducive to observing invagination. Epiblast cells ingress through the middle of the germ disc, to differentiate into either endoderm or mesenchymal mesoderm. The endoderm proliferates to drive the hypoblast into the extraembryonic endoderm of the yolk sac. The mesenchyme spreads between the epiblast and endoderm. Although not drawn to scale, the progressive thickening from lateral to paraxial mesoderm is depicted. To open the animation using Internet Explorer follow these steps. (1.) Click the link for the animation. (2.) A dialog box may pop up that begins with the statement "Windows cannot open this file:" If this box does not appear proceed to step four. If it does choose "Select the program from a list," then click OK. (3.) Another dialog box will pop up that lists different programs. Make sure "Internet Explorer" is selected, then click OK. (4.) Internet Explorer will pop up. Beneath the toolbars at the top of the window a yellow bar will appear that reads "To help protect your security, Internet Explorer has restricted this webpage from running scripts or Active X controls that could access your computer. Click here for options..." Pass the cursor over this yellow bar and click the right mouse button. (5.) A dialog box will pop up. Left click the option "Allow Blocked Content." (6.) Another dialog box will appear labeled "Security Warning" asking you to confirm that you want to run the content. Click "Yes." (7.) The Flash animation will appear in the Internet Explorer Window. (8.) Instructions for navigating the lesson are provided by the first frame of the animation.

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

2011-06-23

88

Southern leaf blight disease severity is correlated with decreased maize leaf epiphytic bacterial species richness and the phyllosphere bacterial diversity decline is enhanced by nitrogen fertilization.  

PubMed

Plant leaves are inhabited by a diverse group of microorganisms that are important contributors to optimal growth. Biotic and abiotic effects on plant growth are usually studied in controlled settings examining response to variation in single factors and in field settings with large numbers of variables. Multi-factor experiments with combinations of stresses bridge this gap, increasing our understanding of the genotype-environment-phenotype functional map for the host plant and the affiliated epiphytic community. The maize inbred B73 was exposed to single and combination abiotic and the biotic stress treatments: low nitrogen fertilizer and high levels of infection with southern leaf blight (causal agent Cochliobolus heterostrophus). Microbial epiphyte samples were collected at the vegetative early-season phase and species composition was determined using 16S ribosomal intergenic spacer analysis. Plant traits and level of southern leaf blight disease were measured late-season. Bacterial diversity was different among stress treatment groups (P < 0.001). Lower species richness-alpha diversity-was correlated with increased severity of southern leaf blight disease when disease pressure was high. Nitrogen fertilization intensified the decline in bacterial alpha diversity. While no single bacterial ribotype was consistently associated with disease severity, small sets of ribotypes were good predictors of disease levels. Difference in leaf bacterial-epiphyte diversity early in the season were correlated with plant disease severity, supporting further tests of microbial epiphyte-disease correlations for use in predicting disease progression. PMID:25177328

Manching, Heather C; Balint-Kurti, Peter J; Stapleton, Ann E

2014-01-01

89

Fumonisin disruption of ceramide biosynthesis in maize roots and the effects on plant development and Fusarium verticillioides-induced seedling disease.  

PubMed

The fungus Fusarium verticillioides infects maize and produces fumonisins, inhibitors of ceramide synthase. Seeds of the cultivar Silver Queen were inoculated with fumonisin-producing or non-fumonisin-producing strains of F. verticillioides. Leaf lesion incidence and severity of effects on root and stalk growth were significantly correlated with fumonisin in roots and disruption of sphingolipid metabolism in roots. Uninoculated seeds grown in soil watered with solutions of fumonisin B1 exhibited above-ground symptoms indicative of F. verticillioides-induced seedling disease and dose-dependent reduction in root mass that was inversely correlated with fumonisin B1, sphingoid bases, and sphingoid base 1-phosphates in roots. There was also evidence of an adaptive response to disrupted sphingolipid metabolism in both the virulence and watering assays, suggesting induction of pathways responsible for metabolism of sphingoid base 1-phosphates after prolonged exposure. The results suggest that fumonisin, and its effects on sphingolipids, could contribute to all aspects of F. verticillioides maize seedling disease. PMID:17381121

Williams, Lonnie D; Glenn, Anthony E; Zimeri, Anne Marie; Bacon, Charles W; Smith, Mary Alice; Riley, Ronald T

2007-04-18

90

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

91

Evaluation of banana hybrids for tolerance to black leaf streak (Mycosphaerella fijiensis Morelet) in Puerto Rico  

Technology Transfer Automated Retrieval System (TEKTRAN)

In Puerto Rico, bananas (including plantains) are important agricultural commodities; their combined production totaled 133,500 tons in 2008. Black leaf streak (BLS) and Sigatoka leaf spot diseases, caused by Mycosphaerella fijiensis and M. musicola, respectively, are responsible for significant los...

92

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

93

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

94

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 crystallographers streak seeding it is used entice certain protein crystals grow. Our system features a of custom this paper known crystallographers streak seeding a technique where small nuclei (or micro­crystals

95

Improving count rate of attosecond streak camera  

NASA Astrophysics Data System (ADS)

We report the measurement of 140-attosecond single isolated extreme ultraviolet pulses generated with 9-fs carrier-envelope phase stabilized lasers. The temporal shape and phase of the isolated attosecond pulses were characterized using the attosecond streaking technique, whereby electrons ionized by the attosecond pulse are momentum-shifted by a near-infrared laser field. Due to the limited flux of attosecond pulses, low electron count rate is a major problem in the streaking measurement. In our setup, the streaked photoelectrons were detected by a COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) type time-of-flight detector. A uniform magnetic field was applied along the flight axis between the detection gas jet and the MCP to increase the full acceptance angle to more than 28 degrees. Instead of measuring the photoelectron energy, the electron momentum was measured, which allows us to examine the effect of the acceptance angle on the accuracy of the pulse characterization. Differential pumping was successfully applied, which allows high gas target pressure for increasing the XUV photoionization efficiency. When the isolated attosecond pulses were generated with argon gas and detected with neon gas, the improved count rate allowed the streaking measurement to be done in the time period that the laser could maintain carrier-envelope phase locking.

Feng, Ximao; Gilbertson, Steve; Mashiko, Hiroki; Wang, He; Khan, Sabih; Chini, Michael; Chang, Zenghu

2009-05-01

96

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

97

Analysis of quantitative disease resistance to southern leaf blight and of multiple disease resistance in maize, using near-isogenic lines  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize inbred lines NC292 and NC330 were derived by repeated backcrossing of an elite source of southern leaf blight (SLB) resistance (NC250P) to the SLB-susceptible line B73, with selection for SLB resistance among and within backcross families at each generation. Consequently, while B73 is very SLB...

98

Clinical comparison of the Welch Allyn SureSight™ handheld autorefractor versus streak retinoscopy in dogs  

PubMed Central

Objective To compare the Welch Allyn SureSight™ wavefront autorefractor with retinoscopy in normal dogs. Animals studied 50 privately-owned dogs (100 eyes) of 20 breeds, free of ocular disease. Mean ±SD age 5.7 ± 3.25 years (range: 6 months – 13 years). Procedures The refractive error was determined in each eye by two experienced retinoscopists using streak retinoscopy as well as by an autorefractor operated by two different examiners. Measurements were performed before and approximately 30–45 minutes after cycloplegia was induced by cyclopentolate 0.5% and tropicamide 0.5% ophthalmic solutions. Results Mean ±SD non-cyclopleged retinoscopy net sphere was ?0.55 ± 1.14 (range: ?3.75 to 3.5) diopters (D). Mean cyclopleged retinoscopy net sphere was ?0.52 ±1.18 (range: ?4.25 to 2) D. Mean ± SD non-cyclopleged autorefractor spherical equivalent (SE) was ?0.42 ± 1.13D (range: ?3.36 to 2.73) D. Mean cyclopleged autorefractor spherical equivalent was 0.10 ±1.47 (range: ?5.62 to 3.19) D. Non-cyclopleged autorefraction results were not significantly different from streak retinoscopy (whether non-cyclopleged or cyclopleged, p=0.80, 0.26, respectively). Cyclopleged autorefraction results were significantly different from non-cyclopleged or cyclopleged streak retinoscopy (p<0.0001 in both states). There was no significant difference between non-cyclopleged and cyclopleged streak retinoscopy (p= 0.97). Conclusions Non-cyclopleged autorefraction shows good agreement with streak retinoscopy in dogs and may be a useful clinical technique. Cycloplegia does not significantly affect streak retinoscopy results in dogs. PMID:23173899

Groth, Allyson D.; Hollingsworth, Steven R.; Ofri, Ron; Kass, Philip H.; Reed, Zoe; Murphy, Christopher J.

2013-01-01

99

Photonic streaking of attosecond pulse trains  

NASA Astrophysics Data System (ADS)

High harmonic radiation, produced when intense laser pulses interact with matter, is composed of a train of attosecond pulses. Individual pulses in this train carry information on ultrafast dynamics that vary from one half-optical-cycle to the next. Here, we demonstrate an all-optical photonic streaking measurement that provides direct experimental access to each attosecond pulse by mapping emission time onto propagation angle. This is achieved by inducing an ultrafast rotation of the instantaneous laser wavefront at the focus. We thus time-resolve attosecond pulse train generation, and hence the dynamics in the nonlinear medium itself. We apply photonic streaking to harmonic generation in gases and directly observe, for the first time, the influence of non-adiabatic electron dynamics and plasma formation on the generated attosecond pulse train. These experimental and numerical results also provide the first evidence of the generation of attosecond lighthouses in gases, which constitute ideal sources for attosecond pump-probe spectroscopy.

Kim, Kyung Taec; Zhang, Chunmei; Ruchon, Thierry; Hergott, Jean-François; Auguste, Thierry; Villeneuve, D. M.; Corkum, P. B.; Quéré, F.

2013-08-01

100

Multichannel fiber-optic spectral streak equalizer  

SciTech Connect

Spectral-streak equalization is a technique that has been developed to compensate for the material dispersion in optical fibers when used in conjunction with an electronic streak camera. Material dispersion occurs because different wavelengths of light travel at different speeds through glass fibers; the resulting difference in transit time broadens light pulses, and can lead to errors in high bandwidth photonic measurements. An instrument designed to compensate for this effect has been in use for the past several years in systems used to evaluate underground nuclear tests. A new instrument has been developed that has the following advantages: it can equalize several channels with one set of optics; it uses considerably less space; it has better resolution and greater efficiency, and it is more cost effective. This paper reviews the basic principles, describes the equalizers currently in use, discusses the design considerations of the new equalizer, describes a prototype four channel instrument, details efficiency estimates, outlines calibration procedures, and gives test results.

Reedy, R.P.

1986-08-20

101

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

102

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

103

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

104

Transcriptomic landscape of the primitive streak.  

PubMed

In birds and mammals, all mesoderm cells are generated from the primitive streak. Nascent mesoderm cells contain unique dorsoventral (D/V) identities according to their relative ingression position along the streak. Molecular mechanisms controlling this initial phase of mesoderm diversification are not well understood. Using the chick model, we generated high-quality transcriptomic datasets of different streak regions and analyzed their molecular heterogeneity. Fifteen percent of expressed genes exhibit differential expression levels, as represented by two major groups (dorsal to ventral and ventral to dorsal). A complete set of transcription factors and many novel genes with strong and region-specific expression were uncovered. Core components of BMP, Wnt and FGF pathways showed little regional difference, whereas their positive and negative regulators exhibited both dorsal-to-ventral and ventral-to-dorsal gradients, suggesting that robust D/V positional information is generated by fine-tuned regulation of key signaling pathways at multiple levels. Overall, our study provides a comprehensive molecular resource for understanding mesoderm diversification in vivo and targeted mesoderm lineage differentiation in vitro. PMID:20667916

Alev, Cantas; Wu, Yuping; Kasukawa, Takeya; Jakt, Lars M; Ueda, Hiroki R; Sheng, Guojun

2010-09-01

105

Maize Transformation  

Microsoft Academic Search

Plant genetic transformation technologies have brought fundamental changes to both plant biology laboratory research as well\\u000a as to modern agricultural field practices. Once a recalcitrant plant for tissue culture and gene delivery, maize is becoming\\u000a one of the most targeted cereal crops using genetic transformation for both basic and applied purposes. This chapter provides\\u000a a brief review of the history

Kan Wang; Bronwyn Frame; Yuji Ishida; Toshihiko Komari

106

Streaked, x-ray-transmission-grating spectrometer  

SciTech Connect

A free standing x-ray transmission grating has been coupled with a soft x-ray streak camera to produce a time resolved x-ray spectrometer. The instrument has a temporal resolution of approx. 20 psec, is capable of covering a broad spectral range, 2 to 120 A, has high sensitivity, and is simple to use requiring no complex alignment procedure. In recent laser fusion experiments the spectrometer successfully recorded time resolved spectra over the range 10 to 120 A with a spectral resolving power, lambda/..delta..lambda of 4 to 50, limited primarily by source size and collimation effects.

Ceglio, N.M.; Roth, M.; Hawryluk, A.M.

1981-08-01

107

Compact optical technique for streak camera calibration  

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

108

Wind streaks: geological and botanical effects on surface albedo contrast  

NASA Astrophysics Data System (ADS)

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

Zimbelman, James R.; Williams, Steven H.

1996-09-01

109

SDOSS: A Spatially Discriminating, Optical Streaked Spectrograph  

NASA Astrophysics Data System (ADS)

SDOSS is employed to study broadband laser scattering encompassing SBS, SRS, and the 3/2-omega signature of two plasmon decay for ns-scale laser-plasma experiments with 351 or 527-nm drive. It uses a Cassegrain telescope to image scattered light from a laser plasma onto a field stop. The telescope magnification and the stop aperture provide spatial discrimination of target plane scatter. A UV lens relays the image to a 0.25-m spectrograph which is lens coupled to a streak camera with an S-1 photocathode. The streak output is imaged onto a CCD camera. In its 512 x 480 pixel array, the CCD covers a spectral range from 200 to 800 nm with 4-nm resolution and can be adjusted to look from 350 to 1,060 nm. The sweep speed is variable with full window values of 30, 12, 6 ns, and faster. An optical fiducial provides a spectral and temporal marker. On the Livermore Nova laser, SDOSS has been used to determine spatial density in gas-filled hohlraums from SRS signals. At Trident in Los Alamos, it has been employed for similar measurements with long scale length plasmas in SBS and SRS seeding experiments. It has proven to be a versatile tool for studying the physics of laser-generated plasmas.

Cobble, J.; Evans, S.; Fernandez, J.; Oertel, J.; Watt, R.; Wilde, B.

110

Streak breakdown instability in pipe Poiseuille flow A lvaro Meseguera)  

E-print Network

Streak breakdown instability in pipe Poiseuille flow A´ lvaro Meseguera) Oxford University of Hagen­Poiseuille flow or pipe flow. The analysis is focused on the streak breakdown process by which two.1063/1.1564093 I. INTRODUCTION Hydrodynamic instability of pipe flow remains one of the oldest and yet unsolved

Meseguer, Alvaro

111

COMPARISON OF THREE CEREALS : WHEAT, MAIZE, BARLEY AND MAIZE-BARLEY, MAIZE-WHEAT MIXTURES  

E-print Network

SUMMARY COMPARISON OF THREE CEREALS : WHEAT, MAIZE, BARLEY AND MAIZE-BARLEY, MAIZE-WHEAT MIXTURES IN GROWING-FINISHING PIG DIETS The purpose of our experiment was to compare the feeding value of maize, wheat and barley and of maize-wheat, maize-barley mixtures (at two levels : 2/3-1/3- r/3-2/3) in the rations

Paris-Sud XI, Université de

112

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

113

Biolistic Protocol Organism: Maize  

E-print Network

Biolistic Protocol Organism: Maize In vivo/in vitro/in situ: in vitro Target tissue: Callus Instrument: PDS-1000/He System Tissue preparation: Maize, callus 28°C (N6 salts). Callus is initiated on high

Raizada, Manish N.

114

Streak interactions and breakdown in boundary layer flows  

NASA Astrophysics Data System (ADS)

The objective of this paper is to show that the interaction of streamwise velocity streaks of finite length can lead to turbulent breakdown in the flat-plate boundary layer flow. The work is motivated by previous numerical and experimental studies of transitional flows where the high-frequency oscillations leading to turbulence are seen to form in the region of strongest shear induced by streaks in relative motion. Therefore, a model for the interaction of steady and unsteady (i.e., slowly moving in the spanwise direction) spanwise periodic streaks is proposed. The interaction of two subsequent streaks is investigated for varying collision parameters. In particular, the relative spanwise position and angle are considered. The results show that the interaction is able to produce both a symmetric and asymmetric breakdown without the need for additional random noise from the main stream. Velocity structures characteristic of both scenarios are analyzed. Hairpin and ? vortices are found in the case of symmetric collision between a low-speed region and an incoming high-speed streak, when a region of strong wall-normal shear is induced. Alternatively, when the incoming high-momentum fluid is misaligned with the low-speed streak in front, single quasi-streamwise vortices are identified. Despite the different symmetry at the breakdown, the detrimental interaction involves for both cases the tail of a low-speed region and the head of a high-speed streak. Further, the breakdown appears in both scenarios as an instability of three-dimensional shear layers formed between the two streaks. The streak interaction scenario is suggested to be of relevance for turbulence production in wall-bounded flows.

Brandt, Luca; de Lange, H. C.

2008-02-01

115

High Performance Imaging Streak Camera for the National Ignition Facility  

SciTech Connect

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 EMI. A train of temporal UV 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. [LLNL; Kalantar, D. [LLNL; MacPhee, A. [LLNL; Holder, J. [LLNL; Kimbrough, J. [LLNL; Bell, P. M. [LLNL; Bradley, D. [LLNL; Hatch, B. [LLNL; Brown, C. [LLNL; Landen, O. [LLNL; Perfect, B. H. [LLNL, HMC; Guidry, B. [LLNL; Mead, A. [NSTec; Charest, M. [NSTec; Palmer, N. [LLNL; Homoelle, D. [LLNL; Browning, D. [LLNL; Silbernagel, C. [NSTec; Brienza-Larsen, G. [NSTec; Griffin, M. [NSTec; Lee, J. J. [NSTec; Haugh, M. J. [NSTec

2012-12-01

116

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

117

Progress on Modeling of Ultrafast X-Ray Streak Cameras  

SciTech Connect

Streak cameras continue to be useful tools for studying phenomena on the picoseconds time scale. We have employed accelerator modeling tools to understand and possibly improve the time resolution of present and future streak cameras. This effort has resulted in an end-to-end model of the camera. This model has contributed to the recent measurement of 230 fsec (FWHM) resolution measured at 266 nm in the Advanced Light Source Streak Camera Laboratory. We describe results from this model that show agreement with the experiments. We also extrapolate the performance of this camera including several possible improvements.

Huang, G.; Byrd, J.M.; Feng, J.; Qiang, J.; Wang, W.

2007-06-22

118

Temporal Contrast Changes in Dark Slope Streaks on Mars  

NASA Astrophysics Data System (ADS)

Dark slope streaks on Mars, first observed in Viking images, provide insight into one of the most active and dynamic processes observed on the planet's surface. While various formation models have been suggested [1][2][3], dust avalanches seem to best explain streak origin and characteristics[4][5]. New dark streaks are observed to have the greatest contrast to their surroundings while older streaks have lower contrast, suggesting that streaks fade over time. One theory for this is atmospheric dust fallout slowly raising the albedo of the surface exposed by the dust avalanche, resulting in increased streak albedo over time until the streak becomes indistinguishable from the surrounding surface. In this study, we attempt an initial evaluation of changes in streak brightness relative to surroundings, with a first order correction for incidence angle[6] based on MOLA data. CRISM images were first identified for spatial and temporal overlap, then further selected for those image sets with well-matched viewing geometries. Locations included Nicholson Crater (CRISM images: frt0000c287_07_de165l, hrl0000d0f1_7_de165l, frt00018c69_07_de165l) and South of Nestus Valles (CRISM images: hrl00004a5e_07_de181l, hrl0000812a_07_de182l) as well as Naktong Vallis (CRISM images: hrl0000898d_07_de182l, hrl00005337_07_de182l) and an area in Lycus Sulci (CRISM images: hrl0000a52a_07_de166l, hrl0000ce5f_07_if175l). We focused on 1 micron wavelength CRISM images in order to reduce atmosphric interference. From here, brightness (observed radiance divided by solar irradiance at Mars divided by pi) values were collected along individual streaks, with measurements at multiple locations along the streak length and alongside at points of similar elevation to streak measurements to establish an average contrast ratio. Both on-streak and off-streak values were divided by the cosine of their respective local MOLA incidence angles to correct for brightness variation due to solar flux and topographic angles. These measurements were then repeated for overlapping temporal images, establishing local and overall averages for the rate of change in this contrast ratio. While our initial hypothesis was for linear streak fading, results showed a range of trends, including streaks and imaged areas with streaks that darkened, brightened, and brightened then darkened or vice versa. We continue to explore the possibility of non-linear brightening as well as streak reactivation and localized events, surface characteristics, and topography. Further study will focus on these and other morphological changes observed from vast data sets of other instruments including the Mars Reconnaissance Orbter HiRISE and CTX, Mars Express HRSC, Mars Odyssey THEMIS (visible), and the Mars Global Surveyor MOC. [1] Morris (1982) JGR, 87, 1164-1178. [2] Ferguson and Lucchita (1984) NASA Tech. Memo., TM-86246, 188-190. [3] Miyamoto, H. et al. (2004) JGR, 109, E06008. [4] Sullivan, R. et al. (2001) JGR, 106, 23607-23633. [5] Baratoux, N. M. et al. (2006) Icarus, 183, 30-45. [6] Brown, A. et al. (2010) JGR, 115, E00D13.

Chilton, H.; Phillips, C. B.; Fenton, L. K.; Brown, A. J.

2012-12-01

119

Responses of Maize (Zea mays L.) near isogenic lines carrying Wsm1, Wsm2 and Wsm3 to three viruses in the Potyviridae  

Technology Transfer Automated Retrieval System (TEKTRAN)

Three independent genes controlling resistance to Wheat streak mosaic virus (WSMV; family Potyviridae; genus Tritimovirus) were previously identified on chromosomes six (Wsm1), three (Wsm2) and ten (Wsm3) in the resistant maize (Zea mays L.) inbred line Pa405. Near isogenic lines (NIL) carrying eac...

120

Statistical characteristics of streak artifacts on CT images: Relationship between streak artifacts and mA s values  

SciTech Connect

The purpose of this study is to investigate how streak artifacts on computed tomography (CT) images vary with reduction in radiation doses by assessing the quantitative relationship between the streak artifacts and milliampere-time product (mA s) values. A commercially available chest phantom was used to measure the streak artifacts on the CT images obtained using a 4- and 16-multidetector-row helical CT scanners with various mA s values at a constant tube voltage of 120 kVp. The cardiac slice image was employed as a target image for evaluating the streak artifacts on the CT image. Eighty parallel line segments with a length of 20 pixels were placed perpendicular to numerous streak artifacts on the cardiac slice image, and the largest difference between adjacent CT values in each of the 80 CT-value profiles of these line segments was employed as a feature variable of streak artifacts; these feature variables have been analyzed by the extreme value theory. The largest difference between adjacent CT values in each CT-value profile can be statistically modeled by a Gumbel distribution. Further, the maximum level of streak artifacts on CT images that will be tolerated for clinical use and low-dose CT screening examination was expected to be estimated using the location parameter in the Gumbel distribution.

Imai, Kuniahru; Ikeda, Mitsuru; Enchi, Yukihiro; Niimi, Takanaga [Department of Radiological Technology, Nagoya University School of Health Sciences, 1-20 Daikominami 1-chome, Higashi-ku, Nagoya, 461-8673 (Japan); Department of Radiology, Osaka University Hospital, 2-15 Yamadaoka, Suita, Osaka, 565-0871 (Japan); Department of Radiological Technology, Nagoya University School of Health Sciences, 1-20 Daikominami 1-chome, Higashi-ku, Nagoya 461-8673 (Japan)

2009-02-15

121

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

122

Breaking the 100-fs Barrier with a Streak Camera  

SciTech Connect

We present a novel x-rat streak tube design that uses a modest extraction field at the photocathode, axial time-of-flight dispersion compensation, and transverse energy selection to achieve better-than-100-fs time resolution.

Jaaniamgi,P.A.

2004-12-13

123

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

E-print Network

of two sorghum cultivars. This experiment evaluated the effect of mechanical inoculation pressure on virus titer as measured by double antibody sandwich method of enzyme-linked immunosorbent assay (DAS-ELISA), disease incidence and severity... in both susceptible and resistant cultivars is required. Enzyme-linked im munosorbent assay (ELISA) has been used to quan tify virus (2, 3, 10, 11, 12, 13, 14) and is a promising alternate to infectivity assay to study MDMV titer. The obje...

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

1992-01-01

124

Design of neutron streak camera for fusion diagnostics  

SciTech Connect

The D-T burn time for advanced laser-fusion targets is calculated to be very short, < 50 ps. We describe the design of a neutron streak camera of 16 ps resolving time that can be used to study the temporal history of fusion burn. The cathode of the neutron streak camera is sensitive to neutrons and is curved such that the difference in the neutron path lengths from a point source to various parts of the cathode is compensated by electron transit times within the streak tube. Thus the cathode can be made large for high sensitivity, without sacrificing time resolution. The cathode is coated with 1 ..mu..m UO/sub 2/. Each fission fragment leaving the cathode generates 400 secondary electrons that are all < 20 eV. These electrons are focussed to a point with an extractor and an anode, and are then purified with an electrostatic deflector. The electron beam is streaked and detected with the standard streak camera techniques. Careful shielding is needed for x-rays from the fusion target and general background. It appears that the neutron streak camera can be a viable and unique tool for studying temporal history of fusion burns in D-T plasmas of a few keV ion temperature.

Wang, C.L.; Kalibjian, R.; Singh, M.S.

1982-06-01

125

Dynamics of low-speed streak evolution and interaction in laminar boundary layer  

NASA Astrophysics Data System (ADS)

The present paper presents an experimental effort on the regeneration process of two low-speed laminar streaks in a zero-pressure-gradient laminar boundary layer. Two vertical thin wires separated by a spanwise distance of 30mm are used to introduce disturbances of two rolls of transitional Kármán vortex street to the downstream boundary layer. Both hydrogen bubble visualization and particle image velocimetry (PIV) measurement show that two low-speed streaks are induced through leading-edge receptivity process. As these streaks develop in the downstream, two additional low-speed streaks begin to appear outboard of the flank of the original two, together with complex dynamics of streak splitting and merging. A flow pattern of four streaks aligned along the spanwise direction occurs finally in the far downstream. It is found that besides the mechanisms of streak breakdown, the streak interaction is also an important factor characterizing the instability of low speed streaks and their regeneration process.

Deng, Si-Chao; Pan, Chong; Wang, Jin-Jun

2014-10-01

126

Identification of multiple ear-colonizing insect and disease resistance in CIMMYT maize inbred lines with varying levels of silk maysin  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ninety four corn inbred lines selected from International Center for the Improvement of Maize and Wheat (CIMMYT) in Mexico were evaluated for levels of silk maysin in 2001 and 2002. Damage by major ear-feeding insects [i.e., the corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), the m...

127

Design and Field Test of a Galvanometer Deflected Streak Camera  

SciTech Connect

We have developed a compact fieldable optically-deflected streak camera first reported in the 20th HSPP Congress. Using a triggerable galvanometer that scans the optical signal, the imaging and streaking function is an all-optical process without incurring any photon-electron-photon conversion or photoelectronic deflection. As such, the achievable imaging quality is limited mainly only by optical design, rather than by multiple conversions of signal carrier and high voltage electron-optics effect. All core elements of the camera are packaged into a 12 inch x 24 inch footprint box, a size similar to that of a conventional electronic streak camera. At LLNL's Site-300 Test Site, we have conducted a Fabry-Perot interferometer measurement of fast object velocity using this all-optical camera side-by-side with an intensified electronic streak camera. These two cameras are configured as two independent instruments for recording synchronously each branch of the 50/50 splits from one incoming signal. Given the same signal characteristics, the test result has undisputedly demonstrated superior imaging performance for the all-optical streak camera. It produces higher signal sensitivity, wider linear dynamic range, better spatial contrast, finer temporal resolution, and larger data capacity as compared with that of the electronic counterpart. The camera had also demonstrated its structural robustness and functional consistence to be well compatible with field environment. This paper presents the camera design and the test results in both pictorial records and post-process graphic summaries.

Lai, C C; Goosman, D R; Wade, J T; Avara, R

2002-11-08

128

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

129

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

130

Time delays for attosecond streaking in photoionization of neon  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

131

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 Molecular evolution of tb1, tga1 and ba1 during maize domestication. Chapter 3 Page 133 Molecular evolution

Doebley, John

132

Quantifying wheat yield across the field as a function of wheat streak mosaic intensity: a state space approach.  

PubMed

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite Aceria tosichella, is one of the major limiting factors in wheat production in the Texas Panhandle. The mites are blown by wind into wheat fields from nearby volunteer wheat fields or fields supporting vegetation which harbor virulent mites. Consequently, gradients of wheat streak severity are often observed stretching from the edges of wheat fields into the center or beyond. To describe the magnitude of the spatial relationships between grain yield and wheat streak intensity across the field, studies were conducted in 2006 and 2007 in three infected fields. Wheat streak severity was quantified with reflectance measurements (remote sensing) at 555-nm wave length using a hand-held radiometer. Measurements were taken in several equally spaced 1 m(2) locations along a total of eight transects and grain yield was assessed from a 0.8 m(2) area of each location. State space analysis was used to describe the relationships in which yield data and reflectance values were used as dependent and explanatory variables, respectively. A structural time series model was formulated as a state space model where the unobserved components were modeled explicitly. In the analysis the state of yield at current location (d) was related to the state of wheat streak intensity either at current locations (d) or lagged locations with autoregressive values of the first order (d-1) or greater. There were significant cross-correlations between yield and wheat streak intensity up to distances of 150 m (P < or = 0.05). Grain yield at the current position was significantly correlated with reflectance values at the same location and/or at lagged locations. The spatial aspects of the yield-reflectance relationships were best described by state space models with stochastic trends without slopes or deterministic trends with or without slopes. The models correctly predicted almost all of the observed yield values as a function of wheat streak intensity across the field within the 95% confidence interval. Results obtained in this study suggest that state space methodology can be a powerful tool in the study of plant disease spread as a function of other variables. PMID:19271985

Workneh, F; Jones, D C; Rush, C M

2009-04-01

133

Molecular cytogenetic characterization of Thinopyrum intermedium-derived wheat germplasm specifying resistance to wheat streak mosaic virus  

Microsoft Academic Search

Thinopyrum intermedium is a promising source of resistance to wheat streak mosaic virus (WSMV), a devastating disease of wheat. Three wheat germplasm\\u000a lines possessing resistance to WSMV, derived from Triticum aestivum?Th. intermedium crosses, are analyzed by C-banding and genomic in situ hybridization (GISH) to determine the amount and location of alien\\u000a chromatin in the transfer lines. Line CI15092 was confirmed

Q. Chen; B. Friebe; R. L. Conner; A. Laroche; J. B. Thomas; B. S. Gill

1998-01-01

134

Viruses in maize and johnsongrass in southern ohio.  

PubMed

ABSTRACT The two major U.S. maize viruses, Maize dwarf mosaic virus (MDMV) and Maize chlorotic dwarf virus (MCDV), emerged in southern Ohio and surrounding regions in the 1960s and caused significant losses. Planting resistant varieties and changing cultural practices has dramatically reduced virus impact in subsequent decades. Current information on the distribution, diversity, and impact of known and potential U.S. maize disease-causing viruses is lacking. To assess the current reservoir of viruses present at the sites of past disease emergence, we used a combination of serological testing and next-generation RNA sequencing approaches. Here, we report enzyme-linked immunosorbent assay and RNA-Seq data from samples collected over 2 years to assess the presence of viruses in cultivated maize and an important weedy reservoir, Johnsongrass (Sorghum halepense). Results revealed a persistent reservoir of MDMV and two strains of MCDV in Ohio Johnsongrass. We identified sequences of several other grass-infecting viruses and confirmed the presence of Wheat mosaic virus in Ohio maize. Together, these results provide important data for managing virus disease in field corn and sweet corn maize crops, and identifying potential future virus threats. PMID:24918609

Stewart, L R; Teplier, R; Todd, J C; Jones, M W; Cassone, B J; Wijeratne, S; Wijeratne, A; Redinbaugh, M G

2014-12-01

135

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

136

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

137

A wide dynamic range x-ray streak camera system  

SciTech Connect

An x-ray streak camera with wide dynamic range and a large slit photocathode of 30 mm length has been developed and calibrated. In order to achieve wide dynamic range, a conventional streak tube has been improved and the camera system has been designed without microchannel plate electron amplifier. As a result, a dynamic range of 922 is achieved in a single shot mode with laser pulse of 30 ps (full width at half maximum) at time resolution of better than 31 ps.

Niu Lihong; Yang Qinlao; Niu Hanben; Liao Hua; Zhou Junlan; Ding Yunkun [Institute of Optoelectronics, Shenzhen University, Guangdong 518060 (China); Laser Fusion Research Center, China Academy of Engineering Physics, Mianyang 621900 (China)

2008-02-15

138

Effects of driving laser jitter on the attosecond streaking measurement.  

PubMed

Driving laser jitter is one of the main factors affecting the attosecond streaking measurement. The effect of carrier-envelope phase (CEP) jitter and the pulse energy jitter on the attosecond pulse characterization is studied in this paper. We have theoretically calculated and experimentally confirmed that CEP jitter could result in a symmetry trace in the streaking spectrogram, while the intensity jitter could result in a slight shift and broadening of the trace. Both of them can lead to an underestimate of the retrieved attosecond pulse duration. PMID:23938620

Zhong, Shiyang; He, Xinkui; Ye, Peng; Zhan, Minjie; Teng, Hao; Wei, Zhiyi

2013-07-29

139

X-ray streak camera with 30-fs timing jitter  

NASA Astrophysics Data System (ADS)

We demonstrated that the shot-to-shot timing jitter of a streak camera is reduced to 30 fs when it is triggered by a standard kilohertz laser with 1.2% RMS fluctuation. Such small jitter was obtained by improving the response time of deflection plates and the rise-time of a ramp pulse generated by a photoconductive switch, and by operating the photoconductive switch at the optimum working condition. The temporal resolution of the x-ray streak camera operating in accumulation mode is better than 600 femtosecond that is not limited by the timing jitter.

Liu, Jinyuan; Wang, Jin; Shan, Bing; Wang, Chun; Chang, Zenghu

2004-01-01

140

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

141

Integrated Management Practices for the Control of Maize Grey Leaf Spot  

Microsoft Academic Search

Grey leaf spot of maize, (Zea maydis L.) (Cercospora zeae-maydis) Tehon and Daniels, is one of the most destructive leaf diseases of maize. The distribution and severity of grey leaf spot has increased over the past 10 to 15 years. The United States and South Africa are main areas where research on the disease has been concentrated. The research results

J. M. J. Ward; D. C. Nowell

1998-01-01

142

Dark slope streaks on Mars: Are aqueous processes involved?  

NASA Astrophysics Data System (ADS)

Concentrations of dark slope streaks occur in the equatorial latitudes of Mars, mostly where magmatic-driven activity dominates the geologic record. Although originally ascribed to wet debris flows, all the most recent published hypotheses concerning these features focus on processes which disturb a brighter dusty mantle to expose a darker substrate. These mechanisms invoke dry mass wasting or eolian processes, excluding a role for water. In light of the geographic, geologic, and morphologic considerations, and the new information provided from the Mars Orbital Camera and the Mars Orbital Data Altimeter, we reexamine fluvial processes as a viable explanation for some of the dark slope streaks. In our opinion, two contrasting processes for the formation of dark slope streaks, dust avalanching and spring discharge, represent endpoints on a continuum of progenitors. It may be that some of these features result from dry mass wasting or eolian processes, some from fluvial processes, and some from a mechanism(s) not yet conceived. A spring discharge origin for the formation of the dark slope streaks has profound implications, including Mars having limited, but currently active, fluvial processes acting upon its surface, as well as near-surface aquifers.

Ferris, J. C.; Dohm, J. M.; Baker, V. R.; Maddock, T.

2002-05-01

143

Analysis of hot streak effects on turbine rotor heat load  

SciTech Connect

The influence of inlet hot streak temperature distortion on turbine blade heat load was explored on a transonic axial flow turbine stage test article using a three-dimensional, multiblade row unsteady Euler code. The turbine geometry was the same as that used for a recently reported testing of hot streak influence. Emphasis was placed on elucidating the physical and mechanisms by which hot streaks affect turbine durability. It was found that temperature distortion significantly increases both blade surface heat load nonuniformity and total blade heat load by as much as 10--30% (mainly in the pressure surface), and that the severity of this influence is a strong function of turbine geometry and flow conditions. Three physical mechanisms were identified that drive the heat load nonuniformity: buoyancy, wake convection (the Kerrebrock-Mikolajczak effect), and rotor-stator interactions. The latter can generate significant nonuniformity of the time-averaged relative frame rotor inlet temperature distribution. Dependence of these effects on turbine design variables was investigated to shed light on the design space, which minimizes the adverse effects of hot streaks.

Shang, T. [Pratt and Whitney, East Hartford, CT (United States); Epstein, A.H. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Gas Turbine Lab.

1997-07-01

144

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

145

Reliable and Repeatable Characterization of Optical Streak Cameras  

SciTech Connect

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

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

2008-10-31

146

Performance characterization of an image converter based streak camera  

Microsoft Academic Search

The performance response of an electronic subnanosecond streak camera to a spatially distributed optical signal varies significantly with the image location on output screen. The variations are due mainly to the combined effects of (1) electron-optics aberrations, (2) camera sweep ramps and gating waveform imperfections, (3) photocathode and phosphor quantum efficiency nonuniformities, and (4) excessive incident intensity or power. Consequently,

C. C. Lai; L. B. Olk

1985-01-01

147

Wind Tunnel Simulations of Light and Dark Streaks on Mars  

Microsoft Academic Search

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

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

1974-01-01

148

Low-speed streaks in drag-reduced turbulent flow  

NASA Astrophysics Data System (ADS)

The effect of a surfactant drag-reducing additive (530 ppm Habon G solution) on the structure of wall turbulence, both in a flume and in pipe flow, was investigated experimentally. Real-time infrared thermography was used for flow visualization and measurements of the spanwise spacing between the thermal streaks. The experiments were carried out over a broad range of friction velocities, i.e., up*=0.51-3.27 cm/s. With wall shear velocities 1.54?up*?3.27 cm/s drag reduction of 82%-85% was achieved in a tube flow, well below the predictions of the Virk maximum drag reduction asymptote proposed for high polymers. The results of spanwise streak spacing indicate that wall shear velocity may be an appropriate parameter for describing nondimensional streak spacing behavior in drag reducing flows. A hypothesis, based on the average spanwise streak spacing ?+, can be applied to describe the mean velocity profiles of Habon G solutions. The ratio (?p+-100)/100 was applied to describe mean velocity profiles with 530 ppm Habon G solution.

Hetsroni, G.; Zakin, J. L.; Mosyak, A.

1997-08-01

149

Reliable and Repeatable Characterication of Optical Streak Cameras  

SciTech Connect

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

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

2008-05-06

150

Streaked Visible Spectroscopy Data Reduction Manual Ross E. Falcon1  

E-print Network

Streaked Visible Spectroscopy Data Reduction Manual Ross E. Falcon1 Department of Astronomy and Mc forms of this diagnostic (e.g., Bailey et al. 2000; Dunham et al. 2004; Bailey et al. 2008; Falcon et al Physical Science Consortium Graduate Fellow #12;R. E. Falcon SVS Data Manual 2 The pulsed power accelerator

Jefferys, William

151

Hitting is contagious in baseball: evidence from long hitting streaks.  

PubMed

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 [Formula: see text] streaks of length [Formula: see text] games, including a total [Formula: see text] observations were compiled. Treatment and control sample groups ([Formula: see text]) were constructed from core lineups of players on the streaking batter's team. The percentile method bootstrap was used to calculate [Formula: see text] 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 [Formula: see text] for the treatment group was found to be [Formula: see text] to [Formula: see text] percentage points higher during hot streaks (mean difference increased [Formula: see text] points), while the batting heat index [Formula: see text] introduced here was observed to increase by [Formula: see text] points. For each performance statistic, the null hypothesis was rejected at the [Formula: see text] 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

152

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

153

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

PubMed

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

Wu, Felicia; Guclu, Hasan

2013-12-01

154

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

155

Maize (Zea mays L.).  

PubMed

Agrobacterium tumefaciens-mediated transformation is an effective method for introducing genes into maize. In this chapter, we describe a detailed protocol for genetic transformation of the maize genotype Hi II. Our starting plant material is immature embryos cocultivated with an Agrobacterium strain carrying a standard binary vector. In addition to step-by-step laboratory transformation procedures, we include extensive details in growing donor plants and caring for transgenic plants in the greenhouse. PMID:25300834

Frame, Bronwyn; Warnberg, Katey; Main, Marcy; Wang, Kan

2015-01-01

156

Transmission of viral RNA and DNA to maize kernels by vascular puncture inoculation.  

PubMed

Vascular puncture inoculation (VPI) is an effective technique for transmission of maize viruses without using arthropods or other biological vectors. It involves using a jeweler's engraving tool to push minuten pins through a droplet of virus inoculum toward the major vascular bundle in the scutellum of germinating kernels. Here, VPI is shown to be useful for introducing RNA and DNA viral genomes into maize. Maize dwarf mosaic potyvirus (MDMV) virions, MDMV genomic RNA, foxtail mosaic potexvirus (FoMV) genomic RNA and maize streak geminivirus (MSV) DNA were introduced into kernels by VPI, and infection rates determined. At high concentrations, both MDMV virion and genomic RNA preparations produced 100% infection of susceptible maize. However, MDMV genomic RNA was transmitted with about 100-fold lower efficiency than virions. FoMV genomic RNA and MSV DNA were transmitted at lower efficiency than the MDMV RNA, and the highest transmission rates were about 50%. Ribonuclease A pretreatment prevented genomic MDMV and FoMV RNA transmission, but not MDMV virion transmission indicating the viral RNA was the infectious entity. Proteinase K (ProK) pretreatment reduced transmission of MDMV RNA suggesting that integrity of the viral genomic protein bound covalently to the viral RNA may be important for efficient transmission. PMID:11576640

Redinbaugh, M G; Louie, R; Ngwira, P; Edema, R; Gordon, D T; Bisaro, D M

2001-11-01

157

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

158

Randomness and inductions from streaks: "gambler's fallacy" versus "hot hand".  

PubMed

Sometimes people believe that a run of similar independent events will be broken (belief in the gambler's fallacy) but, other times, that such a run will continue (belief in the hot hand). Both of these opposite inductions have been explained as being due to belief in a law of small numbers. We argue that one factor that distinguishes these phenomena is people's beliefs about the randomness of the underlying process generating the events. We gave participants information about a streak of events but varied the scenarios in such a way that the mechanism generating the events should vary in how random the participants would judge it to be. A manipulation check confirmed our assumptions about the scenarios. We found that with less random scenarios, the participants were more likely to continue a streak. PMID:15117006

Burns, Bruce D; Corpus, Bryan

2004-02-01

159

Megahertz streak-mode Fourier domain optical coherence tomography  

PubMed Central

Here we present an ultrahigh-speed Fourier-domain optical coherence tomography (OCT) that records the OCT spectrum in streak mode with a high-speed area scan camera, which allows higher OCT imaging speed than can be achieved with a line-scan camera. Unlike parallel OCT techniques that also use area scan cameras, the conventional single-mode fiber-based point-scanning mechanism is retained to provide a confocal gate that rejects multiply scattered photons from the sample. When using a 1000 Hz resonant scanner as the streak scanner, 1,016,000 A-scans have been obtained in 1 s. This method's effectiveness has been demonstrated by recording in vivo OCT-image sequences of embryonic chick hearts at 1000 frames/s. In addition, 2-megahertz OCT data have been obtained with another high speed camera. PMID:21721817

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

2011-01-01

160

Streaked horned lark Eremophila  alpestris  strigata has distinct mitochondrial DNA  

Microsoft Academic Search

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

Sergei V. Drovetski; Scott F. Pearson

2005-01-01

161

9. VIEW OF 'BLUE STREAK' HAMMER MILL (Prater Pulverizer Co., ...  

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. VIEW OF 'BLUE STREAK' HAMMER MILL (Prater Pulverizer Co., Chicago, Illinois), LOCATED IN THE SOUTHEAST CORNER OF THE BASEMENT, WAS ADDED IN THE EARLY 1930s. THIS WAS THE MILL'S FIRST ELECTRIC-POWERED MACHINERY. THE HAMMER MILL WAS USED TO PULVERIZE OATS, ALFALFA MEAL, AND CORN. Photographer: Louise Taft Cawood, July 1986 - Alexander's Grist Mill, Lock 37 on Ohio & Erie Canal, South of Cleveland, Valley View, Cuyahoga County, OH

162

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

163

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

164

Streaking At High Energies With Electrons And Positrons  

E-print Network

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.

Andreas Ipp; Jörg Evers; Christoph H. Keitel; Karen Z. Hatsagortsyan

2012-02-01

165

Stabilization of boundary layer streaks by plasma actuators  

NASA Astrophysics Data System (ADS)

A flow's transition from laminar to turbulent leads to increased levels of skin friction. In recent years, dielectric barrier discharge actuators have been shown to be able to delay the onset of turbulence in boundary layers. While the laminar to turbulent transition process can be initiated by several different instability mechanisms, so far, only stabilization of the Tollmien-Schlichting path to transition has received significant attention, leaving the stabilization of other transition paths using these actuators less explored. To fill that void, a bi-global stability analysis is used here to examine the stabilization of boundary layer streaks in a laminar boundary layer. These streaks, which are important to both transient and by-pass instability mechanisms, are damped by the addition of a flow-wise oriented plasma body force to the boundary layer. Depending on the magnitude of the plasma actuation, this damping can be up to 25% of the perturbation's kinetic energy. The damping mechanism appears to be due to highly localized effects in the immediate vicinity of the body force, and when examined using a linearized Reynolds-averaged Navier-Stokes energy balance, indicate negative production of the perturbation's kinetic energy. Parametric studies of the stabilization have also been performed, varying the magnitude of the plasma actuator's body force and the spanwise wavenumber of the actuation. Based on these parametric studies, the damping of the boundary layer streaks appears to be linear with respect to the total amount of body force applied to the flow.

Riherd, Mark; Roy, Subrata

2014-03-01

166

Reliable and Repeatable Characterization of Optical Streak Cameras  

SciTech Connect

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

Michael R. Charest, Peter Torres III, Christopher Silbernagel

2008-03-01

167

Maize Photoperiod Control: Part II  

Technology Transfer Automated Retrieval System (TEKTRAN)

During the 2007 and 2008 seasons, the staff of the Germplasm Enhancement of Maize Project and the Maize Curatorial Project staff of the North Central Regional Plant Introduction Station experimented with various types of structures to ensure that field plantings of tropical maize germplasm were expo...

168

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

169

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

170

Cell streak imaging cytometry for rare cell detection.  

PubMed

Detection of rare cells, such as circulating tumor cells, have many clinical applications. To measure rare cells with increased sensitivity and improved data managements, we developed an imaging flow cytometer with a streak imaging mode capability. The new streak mode imaging mode utilizes low speed video to capture moving fluorescently labeled cells in a flow cell. Each moving cell is imaged on multiple pixels on each frame, where the cell path is marked as a streak line proportional to the length of the exposure. Finding rare cells (e.g., <1 cell/mL) requires measuring larger sample volumes to achieve higher sensitivity, therefore we combined streak mode imaging with a "wide" high throughput flow cell (e.g. flow rates set to 10 mL/min) in contrast to the conventional "narrow" hydrodynamic focusing cells typically used in cytometry that are inherently limited to low flow rates. The new flow cell is capable of analyzing 20 mL/min of fluorescently labeled cells. To further increase sensitivity, the signal to noise ratio of the images was also enhanced by combining three imaging methods: (1) background subtraction, (2) pixel binning, and (3) CMOS color channel selection. The streaking mode cytometer has been used for the analysis of SYTO-9 labeled THP-1 human monocytes in buffer and in blood. Samples of cells at 1 cell/mL and 0.1 cell/mL were analyzed in 30 mL with flow rates set to 10 mL/min and frame rates of 4 fps (frame per second). For the target of 1 cell/mL, an average concentration of 0.91 cell/mL was measured by cytometry, with a standard error of 0.03 (C(95) = 0.85-0.97). For the target of 0.1 cell/mL, an average concentration of 0.083 cell/mL was measured, with a standard error of 0.01 (C(95) = 0.065-0.102). Whole blood was also spiked with SYTO-9 labeled cells to a concentration of 10 cell/mL, and the average flow cytometry measurement was 8.7 cells/mL (i.e. 0.87 cells/mL in diluted blood) with a 95% CL of 8.1-9.2 cells/mL. This demonstrated the ability to detect rare cells in blood with high accuracy. Such detection approaches for rare cells have many potential clinical applications. Furthermore, the simplicity and low cost of this device may enable expansion of cell-based clinical diagnostics, especially in resource-poor settings. PMID:25212069

Balsam, Joshua; Bruck, Hugh Alan; Rasooly, Avraham

2015-02-15

171

Diallel analysis of resistance to fusarium ear rot and fumonisin contamination in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fungus Fusarium verticillioides infects maize ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with the mycotoxin fumonisin. Typical hybrid maize breeding programs involve selection for both favorable inbred and hybrid performance, and the...

172

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

173

MaizeGDB - Past, present, and future  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Maize Genetics and Genomics Database (MaizeGDB) turns 20 this year. This editorial outlines MaizeGDB's history and connection to the Maize Genetics Cooperation, describes key components of how the MaizeGDB interface will be completely redesigned over the course of the next two years to meet cur...

174

Use of an advanced intercross line population for mapping of quantitative trait loci for northern leaf blight resistance in maize and for the investigation of multiple disease resistance  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this paper we identify regions of the genome conferring resistance to the corn disease, northern corn leaf blight. We also report evidence for the existence of genes conferring resistance to multiple diseases....

175

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

176

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

177

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

PubMed Central

Background Rice black-streaked dwarf virus (RBSDV) causes great losses in rice, maize and wheat production in Asian countries. The use of serological methods for RBSDV detection depends on the availability of antibodies. In this study, three highly sensitive and specific murine monoclonal antibodies (MAbs) against RBSDV antigens were produced using crude extracts from tumors of RBSDV-infected maize as the immunogen, and two serological assays, antigen-coated-plate enzyme-linked immunosorbent assay (ACP-ELISA) and dot enzyme-linked immunosorbent assay (dot-ELISA) were developed for RBSDV detection. Results All three MAbs reacted strongly and specifically with the crude extracts from RBSDV-infected plant and planthopper tissues. The detection endpoints of three MAbs (12E10, 18F10 and 5G5) in ACP-ELISA were respectively 1:40,960, 1:40,960, 1:81,920 (w/v, g?mL-1) with the crude extract of infected maize, 1:10,240, 1:20,480, 1:20,480 (w/v, g?mL-1) with the crude extract of infected rice, 1:5,120, 1:10,240, 1:10,240 (w/v, g?mL-1) with the crude extract of infected wheat, 1:9,600, 1:9,600, 19,200 (individual planthopper/?L) with the crude extract of infected planthopper. The newly developed ACP-ELISA could detect the virus in the infected maize, wheat, rice tissue crude extracts diluted at 1:81,920, 1:20,480, 1:10,240 (w/v, g?mL-1), respectively, and in individual viruliferous planthopper extract diluted at 1:19200 (individual planthopper/?L). The dot-ELISA was proved to detect the virus in the infected maize, wheat and rice tissue crude extracts diluted at 1:320 (w/v, g?mL-1), and in individual viruliferous planthopper extract diluted at 1:1,600 (individual planthopper/?L), respectively. Field plants (915) and planthopper samples (594) from five provinces of China were screened for the presence of RBSDV using the two developed serological assays. The results indicated that 338 of the 915 plant samples and 19 of the 594 planthopper samples were infected by RBSDV. Conclusions The newly developed ACP-ELISA and dot-ELISA were highly sensitive and specific to detect RBSDV in field plant and planthopper samples. The field survey demonstrated that RBSDV is widespread in rice, maize and wheat crops in Jiangsu, Zhejiang, Shandong provinces of China. PMID:23575411

2013-01-01

178

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

179

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

180

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

181

A guanylyl cyclase-like gene is associated with Gibberella ear rot resistance in maize ( Zea mays L.)  

Microsoft Academic Search

Gibberella ear rot, caused by the fungal pathogen Fusarium graminearum Schwabe, is a serious disease of maize (Zea mays L.) grown in northern climates. The infected maize grain contains toxins that are very harmful to livestock and humans. A\\u000a maize gene that encodes a putative 267-amino acid guanylyl cyclase-like protein (ZmGC1) was characterized and shown to be\\u000a associated with resistance

J. Yuan; M. Liakat Ali; J. Taylor; J. Liu; G. Sun; W. Liu; P. Masilimany; A. Gulati-Sakhuja; K. P. Pauls

2008-01-01

182

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 Abstract We present a microrobotic system for protein crystal micromanipulation tasks. The focus in this paper is on the task known by crystallographers as streak seeding ­ it is used to entice certain protein

183

On the Introduction of Unsteady Streaks into a Blasius Boundary Layer Using Dynamically Actuated Roughness  

NASA Astrophysics Data System (ADS)

Observations of the spatio-temporal growth of streamwise elongated streaks emanating from a cylindrical roughness element undergoing dynamic actuation into/out of a Blasius boundary layer are presented. Hot-wire measurements provide 2D maps of the disturbance velocity of these streaks. Modal decomposition methods are performed on these maps to evaluate the nature of the temporal growth of the streaks. For this analysis, various roughness element actuation heights, velocities, and accelerations are examined in order to identify the ``dynamic-roughness'' actuation parameters range for which transiently growing streaks can be produced while avoiding the introduction of T-S wave packets and/or non-linearly-growing disturbances. The establishment of such streaks with 5-10% disturbance magnitude will provide the basis for an experimental platform, and help develop efficient models for feedback bypass transition control in an ongoing study in collaboration with Princeton University.

Bade, Kyle; Naguib, Ahmed; Lavoie, Philippe

2011-11-01

184

Clonal characteristics of fibrous plaques and fatty streaks from human aortas.  

PubMed Central

Using isoenzymes of glucose-6-phosphate dehydrogenase (G-6-PD) as cellular markers, a study was made of atherosclerotic fibrous plaques and fatty streaks in aortas of black women heterozygous for G-6-PD. Of 29 fibrous plaques, 26 (89.7%) contained only one isoenzyme (17, A; 9, B), the other three containing both A and B. Of 28 fatty streaks, five (17.8%) contained only one isoenzyme (2, A; 3, B), the remaining 23 containing both A and B. Normal uninvolved aorta contained both A and B isoenzymes in 99 of 101 samples. These results confirm the monoclonal character of atherosclerotic fibrous plaques; this strands in contrast to the fatty streaks which most commonly contain the two isoenzymes. The studies on the fatty streaks are inconclusive at this stage in determining whether the streak is the forerunner of the fibrous plaque. Images Figure 1 PMID:1190295

Pearson, T. A.; Wang, B. A.; Solez, K.; Heptinstall, R. H.

1975-01-01

185

Efficient and stable expression of GFP through Wheat streak mosaic virus-based vectors in cereal hosts using a range of cleavage sites: Formation of dense fluorescent aggregates for sensitive virus tracking  

Technology Transfer Automated Retrieval System (TEKTRAN)

A series of Wheat streak mosaic virus (WSMV)-based expression vectors were developed by engineering cycle 3 GFP (GFP) cistron between P1 and HC-Pro cistrons with several catalytic/cleavage peptides at the C-terminus of GFP. WSMV-GFP vectors with the Foot-and-mouth disease virus 1D/2A or 2A catalytic...

186

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

187

THE MAIZE GENETICS AND GENOMICS DATABASE: A COMMUNITY RESOURCE FOR ACCESS TO DIVERSE MAIZE DATA  

Technology Transfer Automated Retrieval System (TEKTRAN)

MaizeGDB (the Maize Genetics and Genomics Database) is the research database for the maize community. The site features a wealth of resources and data facilitating the scientific study of maize. Among the data sets included in MaizeGDB are sequences, including PlantGDB's EST and GSS contig assemblie...

188

Comparing the regional epidemiology of the cassava mosaic and cassava brown streak virus pandemics in Africa.  

PubMed

The rapid geographical expansion of the cassava mosaic disease (CMD) pandemic, caused by cassava mosaic geminiviruses, has devastated cassava crops in 12 countries of East and Central Africa since the late 1980s. Region-level surveys have revealed a continuing pattern of annual spread westward and southward along a contiguous 'front'. More recently, outbreaks of cassava brown streak disease (CBSD) were reported from Uganda and other parts of East Africa that had been hitherto unaffected by the disease. Recent survey data reveal several significant contrasts between the regional epidemiology of these two pandemics: (i) severe CMD radiates out from an initial centre of origin, whilst CBSD seems to be spreading from independent 'hot-spots'; (ii) the severe CMD pandemic has arisen from recombination and synergy between virus species, whilst the CBSD pandemic seems to be a 'new encounter' situation between host and pathogen; (iii) CMD pandemic spread has been tightly linked with the appearance of super-abundant Bemisia tabaci whitefly vector populations, in contrast to CBSD, where outbreaks have occurred 3-12 years after whitefly population increases; (iv) the CMGs causing CMD are transmitted in a persistent manner, whilst the two cassava brown streak viruses appear to be semi-persistently transmitted; and (v) different patterns of symptom expression mean that phytosanitary measures could be implemented easily for CMD but have limited effectiveness, whereas similar measures are difficult to apply for CBSD but are potentially very effective. An important similarity between the pandemics is that the viruses occurring in pandemic-affected areas are also found elsewhere, indicating that contrary to earlier published conclusions, the viruses per se are unlikely to be the key factors driving the two pandemics. A diagrammatic representation illustrates the temporal relationship between B. tabaci abundance and changing incidences of both CMD and CBSD in the Great Lakes region. This emphasizes the pivotal role played by the vector in both pandemics and the urgent need to identify effective and sustainable strategies for controlling whiteflies on cassava. PMID:21549776

Legg, J P; Jeremiah, S C; Obiero, H M; Maruthi, M N; Ndyetabula, I; Okao-Okuja, G; Bouwmeester, H; Bigirimana, S; Tata-Hangy, W; Gashaka, G; Mkamilo, G; Alicai, T; Lava Kumar, P

2011-08-01

189

Detection of episomal banana streak badnavirus by IC-PCR.  

PubMed

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 transcriptase domain boundaries of both episomal and integrated BSV sequences and result in similar or identical sequence size fragments from either template. However, we show that under the conditions selected for IC-PCR, nuclear, mitochondrial or chloroplast genomic sequences are not amplified and thus only captured episomal BSV is amplified. IC-PCR is suitable for the large-scale screening of Musa for episomal BSV which is necessary for germplasm movement. PMID:10328530

Harper, G; Dahal, G; Thottappilly, G; Hull, R

1999-04-01

190

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

191

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

192

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

193

Maize variety and method of production  

DOEpatents

The disclosure relates to a maize plant, seed, variety, and hybrid. More specifically, the disclosure relates to a maize plant containing a Cal-1 allele, whose expression results in increased cell wall-derived glucan content in the maize plant. The disclosure also relates to crossing inbreds, varieties, and hybrids containing the Cal-1 allele to produce novel types and varieties of maize plants.

Pauly, Markus; Hake, Sarah; Kraemer, Florian J

2014-05-27

194

The MaizeGDB Genome Browser  

Technology Transfer Automated Retrieval System (TEKTRAN)

MaizeGDB (http://www.maizegdb.org) is the community database for maize genetics and genomics. As part of an effort to develop MaizeGDB as a more sequence-centric resource, we implemented a genome browser based on information we gathered by surveying the community of maize geneticists. Based on commu...

195

AN INTEGRATED MAP FOR MAIZE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Maize Mapping Project (MMP) is focused on developing genetic, physical, and database resources for the maize genome. A key resource being developed by the MMP is a well-integrated genetic and physical map that will expedite the identification of DNA sequences underlying key traits that have been...

196

Optimal streaks in a Falkner-Skan boundary layer  

NASA Astrophysics Data System (ADS)

This paper deals with the optimal streaky perturbations (which maximize the perturbed energy growth) in a wedge flow boundary layer, which involves a favorable streamwise pressure gradient. These three-dimensional perturbations are governed by a system of linearized boundary layer equations around the Falkner-Skan base flow. Based on an asymptotic analysis of this system near the free-stream and the leading edge singularity, we show that for acute wedge semi-angle, all solutions converge after a streamwise transient to a single streamwise-growing solution of the linearized equations, whose initial condition near the leading edge is given by an eigenvalue problem first formulated in this context by Tumin [Phys. Fluids 13, 1521 (2001)]. Such a solution may be regarded as a streamwise evolving most unstable streaky mode, in analogy with the usual eigenmodes in strictly parallel flows, and shows an approximate self-similarity, which was partially known and is completed in this paper. An important consequence of this result is that the optimization procedure based on the adjoint equations heretofore used to define optimal streaks is not necessary. Instead, a simple low-dimensional optimization process is proposed and used to obtain optimal streaks. Comparison with previous results by Tumin and Ashpis [AIAA J. 41, 2297 (2003)] shows an excellent agreement. The unstable streaky mode exhibits transient growth if the wedge semi-angle is smaller than a critical value that is slightly larger than ? /6, and decays otherwise. Thus, the cases of right and obtuse wedge semi-angles exhibit less practical interest, but they show a qualitatively different behavior, which is briefly described in the supplementary material.

Sánchez-Álvarez, José J.; Higuera, María; Vega, José M.

2011-02-01

197

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

PubMed

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

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

2013-05-01

198

Streaking in Cascadia ETS Events and Implications for the Subduction Plate Interface  

NASA Astrophysics Data System (ADS)

The manner in which episodic tremor and slow slip (ETS) propagates across the subduction plate interface provides constraints on its properties and the physical processes involved. We have been examining catalogs of tremor locations to study propagation patterns during ETS. Tremor in the large Cascadia ETS events propagates mainly via three modes: 1) the slow along-strike advance of ETS, 2) rapid tremor reversals (RTRs) that propagate back from the tremor front in an opposite direction to the along-strike advance, but at speeds 10-40 times faster (Houston et al., Nature Geoscience, 2011), and 3) streaks, even faster migrations of tremor parallel to the plate-convergence direction at speeds ~ 70 km/hr (Ghosh et al., G3, 2011). The UW Seismology group has recently deployed an EarthScope-funded seismic experiment, the Array of Arrays, to image tremor more precisely with eight subarrays. A 15-month catalog of high-resolution tremor locations has been generated based on the triangulation of back-projected beams from the subarrays. We detect tremor streaks in this catalog automatically and systematically determine streak propagation properties. Key issues for constraining streak-generation processes include systematic differences between up- and down-dip traveling streaks, how streak properties may depend on depth, and whether streaks accelerate or decelerate during propagation. Stacking automatically-detected streaks can address some of these issues. Two approaches to automatically detecting streaks have been developed and applied to the M6.8 2010 ETS. One method declares a streak when averaged epicenters continue to move in a roughly constant direction for more than 10 km. The second declares a streak if epicenters during a specified time interval, say 20 min, are sufficiently well-correlated with time. The two methods agree well and detect several streaks per day of 15-30 min duration with speeds consistent with those inferred for the 2008 ETS. Although the detection methods have no azimuthal bias, most of the detected streaks align with one direction; furthermore, that direction lies much closer to the plate convergence direction than directly down-dip (the down-dip and plate convergence directions differ significantly along most of Cascadia). Many more streaks are detected in the actual catalog than in randomized versions, in which the times within each hour are permuted. These results lend substantial credence to convergence-parallel streaks as real features of ETS. Streak propagation patterns suggest the plate interface is anisotropic along the slip direction. The ubiquity of streaking parallel to plate convergence implies control by corrugated or smeared structures on the plate interface. This could occur via such structures controlling the orientation of an advancing slip pulse, which could carry streaks along its peak (Rubin, G3, 2011), or more directly via heterogeneous physical properties (such as rheology or permeability) elongated in the convergence direction. In this connection, we note that daily tremor bands in Cascadia ETS are also often oriented parallel to the convergence direction whether the ETS is advancing north or south, even though the direction of ETS advance would be expected to affect the orientation of a slip pulse on a homogeneous interface.

Houston, H.; Ghosh, A.

2011-12-01

199

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

200

Roles of Stolbur Phytoplasma and Reptalus Panzeri (Cixiinae, Auchenorrhyncha) in the Epidemiology of Maize Redness in Serbia  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40-90% in southern Banat, Serbia. MR was recently associated with the presence of th...

201

Roles of Stolbur phytoplasma and Reptalus panzeri (Cixiinae, Auchenorrhyncha) in the epidemiology of Maize redness in Serbia  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize redness (MR), a disease causing midrib, leaf and stalk reddening and abnormal ear development in maize, has been reported from Serbia, Romania and Bulgaria for 50 years. Recent epiphytotics reduced yields by 40-90% in southern Banat, Serbia. MR was recently associated with the presence of th...

202

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

203

Ultra fast x-ray streak camera for ten inch manipulator 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 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. [Physics and Life Science, Lawrence Livermore National Laboratory, M.S. L-490, Livermore, California 94550 (United States); University of California Davis, One Shields Avenue, Davis, California 95616 (United States); Shepherd, R.; Fulkerson, S.; James, L.; Emig, J.; Norman, D. [Physics and Life Science, Lawrence Livermore National Laboratory, M.S. L-490, Livermore, California 94550 (United States)

2012-10-15

204

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

205

The instability and breakdown of a near-wall low-speed streak  

NASA Astrophysics Data System (ADS)

The instability of the three-dimensional high-shear layer associated with a near-wall low-speed streak is investigated experimentally. A single low-speed streak, not unlike the near-wall low-speed streaks in transitional and turbulent flows, is produced in a laminar boundary layer by using a small piece of screen set normal to the wall. In order to excite symmetric and anti-symmetric modes separately, well-controlled external disturbances are introduced into the laminar low-speed streak through small holes drilled behind the screen. The growth of the excited symmetric varicose mode is essentially governed by the Kelvin Helmholtz instability of the in ectional velocity profiles across the streak in the normal-to-wall direction and it can occur when the streak width is larger than the shear-layer thickness. The spatial growth rate of the symmetric mode is very sensitive to the streak width and is rapidly reduced as the velocity defect decreases flowing to the momentum transfer by viscous stresses. By contrast, the anti-symmetric sinuous mode that causes the streak meandering is dominated by the wake-type instability of spanwise velocity distributions across the streak. As far as the linear instability is concerned, the growth rate of the anti-symmetric mode is not so strongly affected by the decrease in the streak width, and its exponential growth may continue further downstream than that of the symmetric mode. As for the mode competition, it is important to note that when the streak width is narrow and comparable with the shear-layer thickness, the low-speed streak becomes more unstable to the anti-symmetric modes than to the symmetric modes. It is clearly demonstrated that the growth of the symmetric mode leads to the formation of hairpin vortices with a pair of counter-rotating streamwise vortices, while the anti-symmetric mode evolves into a train of quasi-streamwise vortices with vorticity of alternate sign.

Asai, Masahito; Minagawa, Masayuki; Nishioka, Michio

2002-03-01

206

RESEARCH ARTICLES Maize Centromeres: Organization and Functional Adaptation  

E-print Network

RESEARCH ARTICLES Maize Centromeres: Organization and Functional Adaptation in the Genetic maize (Zea mays) centromeres using oat (Avena sativa)-maize chromosome addition lines. The maize and organization of centromeric DNA of individual maize chromosomes. We demonstrate that the cores of maize

207

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

PubMed Central

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. Elevated [CO2] increases maize susceptibility to Fusarium verticillioides proliferation but mycotoxin levels are unaltered. The attenuation of maize 13-LOXs and JA 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]. 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 EA

2014-01-01

208

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

209

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

210

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

211

Polar Dunes In Summer Exhibit Frost Patches, Wind Streaks  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

212

Exploiting the Combination of Natural and Genetically Engineered Resistance to Cassava Mosaic and Cassava Brown Streak Viruses Impacting Cassava Production in Africa  

PubMed Central

Cassava brown streak disease (CBSD) and cassava mosaic disease (CMD) are currently two major viral diseases that severely reduce cassava production in large areas of Sub-Saharan Africa. Natural resistance has so far only been reported for CMD in cassava. CBSD is caused by two virus species, Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV). A sequence of the CBSV coat protein (CP) highly conserved between the two virus species was used to demonstrate that a CBSV-CP hairpin construct sufficed to generate immunity against both viral species in the cassava model cultivar (cv. 60444). Most of the transgenic lines showed high levels of resistance under increasing viral loads using a stringent top-grafting method of inoculation. No viral replication was observed in the resistant transgenic lines and they remained free of typical CBSD root symptoms 7 month post-infection. To generate transgenic cassava lines combining resistance to both CBSD and CMD the hairpin construct was transferred to a CMD-resistant farmer-preferred Nigerian landrace TME 7 (Oko-Iyawo). An adapted protocol allowed the efficient Agrobacterium-based transformation of TME 7 and the regeneration of transgenic lines with high levels of CBSV-CP hairpin-derived small RNAs. All transgenic TME 7 lines were immune to both CBSV and UCBSV infections. Further evaluation of the transgenic TME 7 lines revealed that CBSD resistance was maintained when plants were co-inoculated with East African cassava mosaic virus (EACMV), a geminivirus causing CMD. The innovative combination of natural and engineered virus resistance in farmer-preferred landraces will be particularly important to reducing the increasing impact of cassava viral diseases in Africa. PMID:23049780

Vanderschuren, Hervé; Moreno, Isabel; Anjanappa, Ravi B.; Zainuddin, Ima M.; Gruissem, Wilhelm

2012-01-01

213

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 mapping on maize chromosome addition lines of oats, we found that the relative locus position along

Ronquist, Fredrik

214

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

E-print Network

Update on the Maize Genome Sequencing Project The Maize Genome Sequencing Project Vicki L. Chandler­3260 (V.B.) On September 20, 2002, the National Science Foundation (NSF) announced the launch of the Maize Genome Sequencing Project. The momentum for this endeavor has been building within the maize (Zea mays

Brendel, Volker

215

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 cows fed a maize silage based ration formulated to be optimal in digestible lysine (LysDl) content was to investigate if the energy value of the maize silage fed or the substitution of part of the total forage

Paris-Sud XI, Université de

216

The sedimentology and dynamics of crater-affiliated wind streaks in western Arabia Terra, Mars and Patagonia, Argentina  

USGS Publications Warehouse

Wind streaks comprise recent aeolian deposits that have been extensively documented on Venus, Earth and Mars. Martian wind streaks are among the most abundant surface features on the planet and commonly extend from the downwind margins of impact craters. Previous studies of wind streaks emerging from crater interior deposits suggested that the mode of emplacement was primarily related to the deposition of silt-sized particles as these settled from plumes. We have performed geologic investigations of two wind streaks clusters; one situated in western Arabia Terra, a region in the northern hemisphere of Mars, and another in an analogous terrestrial site located in southern Patagonia, Argentina, where occurrences of wind streaks emanate from playas within maar craters. In both these regions we have identified bedforms in sedimentary deposits on crater floors, along wind-facing interior crater margins, and along wind streaks. These observations indicate that these deposits contain sand-sized particles and that sediment migration has occurred via saltation from crater interior deposits to wind streaks. In Arabia Terra and in Patagonia wind streaks initiate from crater floors that contain lithic and evaporitic sedimentary deposits, suggesting that the composition of wind streak source materials has played an important role in development. Spatial and topographic analyses suggest that regional clustering of wind streaks in the studied regions directly correlates to the areal density of craters with interior deposits, the degree of proximity of these deposits, and the craters' rim-to-floor depths. In addition, some (but not all) wind streaks within the studied clusters have propagated at comparable yearly (Earth years) rates. Extensive saltation is inferred to have been involved in its propagation based on the studied terrestrial wind streak that shows ripples and dunes on its surface and the Martian counterpart changes orientation toward the downslope direction where it extends into an impact crater. ?? 2009 Elsevier B.V.

Rodriguez, J.A.P.; Tanaka, K.L.; Yamamoto, A.; Berman, D.C.; Zimbelman, J.R.; Kargel, J.S.; Sasaki, S.; Jinguo, Y.; Miyamoto, H.

2010-01-01

217

CHROMOSOMAL DISTRIBUTION OF MAIZE REPETITIVE SEQUENCES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Microarray technology used in conjunction with labeled DNA from oat-maize addition (OMA) lines enable chromosomal analysis of the organization and distribution of maize repetitive elements. Each OMA line contains an individual maize chromosome allowing for an analysis of its composition. The probes ...

218

The Genetic Architecture of Maize Flowering Time  

Technology Transfer Automated Retrieval System (TEKTRAN)

Flowering time is the key trait controlling adaptation of plants to their local environment, and, in an outcrossing species like maize, it is a complex trait. Variation for this complex trait was dissected in maize using a novel set of 5000 recombinant inbred lines (maize Nested Association Mapping...

219

Thc6 protein, isolated from Trichoderma harzianum, can induce maize defense response against Curvularia lunata.  

PubMed

Mutant T66 was isolated from 450 mutants (constructed with Agrobacterium tumefaciens-mediated transformation method) of Trichoderma harzianum. Maize seeds coated with T66 were more susceptible to Curvularia lunata when compared with those coated with wild-type (WT) strain. The disease index of maize treated with T66 and WT were 62.5 and 42.1%, respectively. Further research showed T-DNA has inserted into the ORF of one gene, which resulted in the functional difference between WT and T66. The gene was cloned and named Thc6, which encodes a novel 327 amino acid protein. To investigate its function, we obtained knockout, complementation, and overexpression mutants of Thc6. Challenge inoculation studies suggested that the Thc6 overexpression mutant can reduce the disease index of maize inbred line Huangzao 4 against the leaf spot pathogen (C. lunata). Meanwhile, The Thc6 mutants were found to affect the resistance of maize inbred line Huangzao 4 against C. lunata by enhancing the activation of jasmonate-responsive genes expression. Liquid chromatography-mass spectrometry (LC-MS) data further confirmed that the concentration of jasmonate in the induced maize exhibits a parallel change tendency with the expression level of defense-related genes. Hence, the Thc6 gene could be participated in the induced resistance of maize inbred line Huangzao 4 against C. lunata infection through a jasmonic acid-dependent pathway. PMID:24771614

Fan, Lili; Fu, Kehe; Yu, Chuanjin; Li, Yingying; Li, Yaqian; Chen, Jie

2014-04-28

220

Active Hydrogeomorphic Processes and the Formation of Dark Slope Streaks on Mars  

NASA Astrophysics Data System (ADS)

Mars Orbital Camera images reveal concentrations of dark slope streaks non-uniformly distributed within the equatorial region of Mars, where Late Hesperian and younger magmatic, tectonic, and fluvial activity often dominate the geologic record. Although originally ascribed to wet debris flows, all of the hypotheses published in the last ~18 years have focused on these features being solely the result of eolian or dry mass-wasting processes, excluding a role for water. In light of (1) the information provided from the Mars Global Surveyor (i.e., high-resolution imagery and topography), (2) the correlation of dark slope streak concentrations to specific geologic environments and histories portrayed in published research, and (3) geomorphic and hydrologic considerations, we hypothesize that eolian or dry mass-wasting and aqueous processes represent endpoints on a continuum of progenitors for the formation of dark slope streaks. In our hypothesis, the hydrogeomorphic features result from artesian spring discharge, hypersaline aquifers, or any combination thereof. Due to observations of dark slope streak features appearing on annual and decadal time scales, and their inferred fading over time, a spring discharge origin for the formation of the dark slope streaks has profound implications. Specifically, that Mars has limited, but currently active, hydrogeomorphic processes acting on its surface. Although the Mars Odyssey's Gamma Ray Spectrometer lacks the resolution to detect these features, its discovery of large amounts of near-surface ice provides further support for our hypothesis.

Ferris, J. C.; Dohm, J. M.; Baker, V. R.; Maddock, T.

2002-12-01

221

Temporal Integration of Movement: The Time-Course of Motion Streaks Revealed by Masking  

PubMed Central

Temporal integration in the visual system causes fast-moving objects to leave oriented ‘motion streaks’ in their wake, which could be used to facilitate motion direction perception. Temporal integration is thought to occur over 100 ms in early cortex, although this has never been tested for motion streaks. Here we compare the ability of fast-moving (‘streaky’) and slow-moving fields of dots to mask briefly flashed gratings either parallel or orthogonal to the motion trajectory. Gratings were presented at various asynchronies relative to motion onset (from to ms) to sample the time-course of the accumulating streaks. Predictions were that masking would be strongest for the fast parallel condition, and would be weak at early asynchronies and strengthen over time as integration rendered the translating dots more streaky and grating-like. The asynchrony where the masking function reached a plateau would correspond to the temporal integration period. As expected, fast-moving dots caused greater masking of parallel gratings than orthogonal gratings, and slow motion produced only modest masking of either grating orientation. Masking strength in the fast, parallel condition increased with time and reached a plateau after 77 ms, providing an estimate of the temporal integration period for mechanisms encoding motion streaks. Interestingly, the greater masking by fast motion of parallel compared with orthogonal gratings first reached significance at 48 ms before motion onset, indicating an effect of backward masking by motion streaks. PMID:22205961

Alais, David; Apthorp, Deborah; Karmann, Anna; Cass, John

2011-01-01

222

Maize, tropical (Zea mays L.).  

PubMed

Maize (Zea mays L.) is the third most important food crop globally after wheat and rice. In sub-Saharan Africa, tropical maize has traditionally been the main staple of the diet; 95 % of the maize grown is consumed directly as human food and as an important source of income for the resource-poor rural population. The biotechnological approach to engineer biotic and abiotic traits implies the availability of an efficient plant transformation method. The production of genetically transformed plants depends both on the ability to integrate foreign genes into target cells and the efficiency with which plants are regenerated. Maize transformation and regeneration through immature embryo culture is the most efficient system to regenerate normal transgenic plants. However, this system is highly genotype dependent. Genotypes adapted to tropic areas are difficult to regenerate. Therefore, transformation methods used with model genotypes adapted to temperate areas are not necessarily efficient with tropical lines. Agrobacterium-mediated transformation is the method of choice since it has been first achieved in 1996. In this report, we describe a transformation method used successfully with several tropical maize lines. All the steps of transformation and regeneration are described in details. This protocol can be used with a wide variety of tropical lines. However, some modifications may be needed with recalcitrant lines. PMID:25300835

Assem, Shireen K

2015-01-01

223

Temporal progress of southern rust in maize under different environmental conditions  

Microsoft Academic Search

The progress of the severity of southern rust in maize (Zea mays) caused by Puccinia polysora was quantified in staggered plantings in different geographical areas in Brazil, from October to May, over two years (1995-1996 and 1996-1997). The logistic model, fitted to the data, better described the disease progress curves than the Gompertz model. Four components of the disease progress

Cláudia V. Godoy; Lílian Amorim; Armando Bergamin Filho; Herbert P. Silva; Willian J. Silva; Richard D. Berger

2003-01-01

224

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

Technology Transfer Automated Retrieval System (TEKTRAN)

The fungus Fusarium verticillioides is a pathogen of many plants and produces fumonisins. In addition to their well-studied animal toxicoses these toxins contribute to the development of maize seedling disease in susceptible maize varieties. Fumonisin disruption of sphingolipid biosynthesis occurs ...

225

Use of Mutant-Assisted Gene Identification and Characterization (MAGIC) to identify novel genetic loci that modify the maize hypersensitive response  

Technology Transfer Automated Retrieval System (TEKTRAN)

The partially-dominant, autoactive maize disease resistance gene Rp1-D21 causes hypersensitive response (HR) lesions to form spontaneously on the leaves and stem in the absence of pathogen recognition. The maize nested association mapping (NAM) population consists of 25 200-line subpopulations each...

226

MaizeGDB, the community database for maize genetics and genomics  

PubMed Central

The Maize Genetics and Genomics Database (MaizeGDB) is a central repository for maize sequence, stock, phenotype, genotypic and karyotypic variation, and chromosomal mapping data. In addition, MaizeGDB provides contact information for over 2400 maize cooperative researchers, facilitating interactions between members of the rapidly expanding maize community. MaizeGDB represents the synthesis of all data available previously from ZmDB and from MaizeDB—databases that have been superseded by MaizeGDB. MaizeGDB provides web-based tools for ordering maize stocks from several organizations including the Maize Genetics Cooperation Stock Center and the North Central Regional Plant Introduction Station (NCRPIS). Sequence searches yield records displayed with embedded links to facilitate ordering cloned sequences from various groups including the Maize Gene Discovery Project and the Clemson University Genomics Institute. An intuitive web interface is implemented to facilitate navigation between related data, and analytical tools are embedded within data displays. Web-based curation tools for both designated experts and general researchers are currently under development. MaizeGDB can be accessed at http://www.maizegdb.org/. PMID:14681441

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

2004-01-01

227

The intentional mind and the hot hand: Perceiving intentions makes streaks seem likely to continue.  

PubMed

People can appear inconsistent in their intuitions about sequences of repeated events. Sometimes people believe such sequences will continue (the "hot hand"), and sometimes people believe they will reverse (the "gambler's fallacy"). These contradictory intuitions can be partly explained by considering the perceived intentionality of the agent generating the streak. The intuition that streaks will continue (reverse) should emerge in contexts involving agents that are perceived to be intentional (unintentional), and should be most common among those who are most inclined to attribute intentions to other agents. Four studies support these predictions, identifying both situational and dispositional determinants of the perceived continuity of streaks. Discussion focuses on the foundational nature of intentionality for perceptions of interdependence between events, the relationship between these findings and existing theoretical accounts, and the inverse possibility that people use perceptions of streakiness as a cue for an agent's intentionality. PMID:20472229

Caruso, Eugene M; Waytz, Adam; Epley, Nicholas

2010-07-01

228

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

229

MAIZEGDB: THE MAIZE COMMUNITY GENETICS AND GENOMICS DATABASE  

Technology Transfer Automated Retrieval System (TEKTRAN)

MaizeGDB (Maize Genetics and Genomics Database) is the research database for the maize community. The site features a wealth of resources and data facilitating the scientific study of maize. Among the data sets included in MaizeGDB are sequences, including integration with various contig assemblies;...

230

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

231

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

232

Ustilago maydis populations tracked maize through domestication and cultivation in the Americas  

PubMed Central

The domestication of crops and the development of agricultural societies not only brought about major changes in human interactions with the environment but also in plants' interactions with the diseases that challenge them. We evaluated the impact of the domestication of maize from teosinte and the widespread cultivation of maize on the historical demography of Ustilago maydis, a fungal pathogen of maize. To determine the evolutionary response of the pathogen's populations, we obtained multilocus genotypes for 1088 U. maydis diploid individuals from two teosinte subspecies in Mexico and from maize in Mexico and throughout the Americas. Results identified five major U. maydis populations: two in Mexico; two in South America; and one in the United States. The two populations in Mexico diverged from the other populations at times comparable to those for the domestication of maize at 6000–10?000 years before present. Maize domestication and agriculture enforced sweeping changes in U. maydis populations such that the standing variation in extant pathogen populations reflects evolution only since the time of the crop's domestication. PMID:18252671

Munkacsi, Andrew B; Stoxen, Sam; May, Georgiana

2008-01-01

233

A maize wall-associated kinase confers quantitative resistance to head smut.  

PubMed

Head smut is a systemic disease in maize caused by the soil-borne fungus Sporisorium reilianum that poses a grave threat to maize production worldwide. A major head smut quantitative resistance locus, qHSR1, has been detected on maize chromosome bin2.09. Here we report the map-based cloning of qHSR1 and the molecular mechanism of qHSR1-mediated resistance. Sequential fine mapping and transgenic complementation demonstrated that ZmWAK is the gene within qHSR1 conferring quantitative resistance to maize head smut. ZmWAK spans the plasma membrane, potentially serving as a receptor-like kinase to perceive and transduce extracellular signals. ZmWAK was highly expressed in the mesocotyl of seedlings where it arrested biotrophic growth of the endophytic S. reilianum. Impaired expression in the mesocotyl compromised ZmWAK-mediated resistance. Deletion of the ZmWAK locus appears to have occurred after domestication and spread among maize germplasm, and the ZmWAK kinase domain underwent functional constraints during maize evolution. PMID:25531751

Zuo, Weiliang; Chao, Qing; Zhang, Nan; Ye, Jianrong; Tan, Guoqing; Li, Bailin; Xing, Yuexian; Zhang, Boqi; Liu, Haijun; Fengler, Kevin A; Zhao, Jing; Zhao, Xianrong; Chen, Yongsheng; Lai, Jinsheng; Yan, Jianbing; Xu, Mingliang

2015-02-01

234

Flowering and Determinacy in Maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

All plant organs are produced by meristems, groups of stem cells located in the tips of roots and shoots. Indeterminate meristems make an indefinite number of organs, whereas determinate meristems are consumed after making a specific number of organs. Maize is an ideal system to study the genetic co...

235

AFFYMETRIX MAIZE PILOT EXPRESSION ARRAY  

Technology Transfer Automated Retrieval System (TEKTRAN)

A pilot study was conducted to evaluate design criteria and analytical methods (particularly signal estimators) for gene expression monitoring in a selection of maize inbreds (B73, W23, Mo17, Wf9-BG) and exotic land races using the Affymetrix probe array technology. The key issue was whether eleven ...

236

Maize Genetics and Genomics Database  

Technology Transfer Automated Retrieval System (TEKTRAN)

The 2007 report for MaizeGDB lists the new hires who will focus on curation/outreach and the genome sequence, respectively. Currently all sequence in the database comes from a PlantGDB pipeline and is presented with deep links to external resources such as PlantGDB, Dana Farber, GenBank, the Arizona...

237

Development of maize starch granules  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize kernels of self-pollinated inbred line B73 harvested on various days after pollination (DAP) were subjected for starch granule development studies. Starch in endosperms was first observed on 6 DAP. A small amount of starch granules (<2% of dry weight) was found in the endosperm on 12 DAP. S...

238

Microrobotic Streak Seeding For Protein Crystal Atanas Georgiev1, Peter K. Allen1, Ting Song2, Andrew Laine2, William Edstrom3, John Hunt3  

E-print Network

Microrobotic Streak Seeding For Protein Crystal Growth Atanas Georgiev1, Peter K. Allen1, Ting Song to crystallographers as streak seeding ­ it is used to entice certain protein crystals to grow. Our system features the throughput in crystal production. The focus here is on the task known by crystallographers as streak seeding

Georgiev, Atanas

239

Measuring detonation front configuration via flash radiography and ultra high speed streak photography  

NASA Astrophysics Data System (ADS)

Although modern numerical computational techniques are able to predict the geometry of a complex detonation front in condensed explosives, in most instances, experimental measurements are still required to verify computational results. Non-planar detonation fronts are measured by means of flash radiography as well as multislit ultrahigh-speed streak photography.

Fuchs, Brian Edward; Baker, Ernest L.; Dalrymple, Everett; Lu, Pai-Lien

1988-02-01

240

Comportement de deux virus filamenteux (Carnation Vein Mottle Virus, Carnation Streak  

E-print Network

Comportement de deux virus filamenteux (Carnation Vein Mottle Virus, Carnation Streak Virus) dans Botanique et de Pathologie végétale, Villa Thuret, B.P. 78, 06602 Antibes Cedex. R�SUM� Virus filamenteux, Dosage, Spectrophotométrie, OEillet. L'évolution de la teneur en virus de la Marbrure des Nervures de l

Paris-Sud XI, Université de

241

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

242

Economic impact of wheat streak mosaic virus in the Texas High Plains  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite Aceria tosichella Keifer, is a major limiting factor in wheat production in the Texas Panhandle. It is the most frequently encountered virus in the region, affecting both shoot and root biomass, and consequently it can drastically red...

243

THE WINDOW OF RISK FOR EMIGRATION OF WHEAT STREAK MOSAIC VIRUS VARIES WITH HOST ERADICATION METHOD  

Technology Transfer Automated Retrieval System (TEKTRAN)

The wheat curl mite (WCM), Aceria tosichella, the vector of Wheat streak mosaic virus (WSMV), often survives the summer on volunteer wheat (Triticum aestivum) and may disperse from this 'green bridge' in fall to newly-planted winter wheat. Because some methods for managing volunteer wheat do not dir...

244

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

NASA Astrophysics Data System (ADS)

The conventional streak camera (CSC) is an optoelectronic instrument that captures the spatial distribution as a function of time of an ultra high-speed luminous phenomenon with picosecond temporal resolution and a typical spatial resolution of several tens of micrometers. This paper presents two tubeless streak camera architectures called MISC (matrix integrated streak camera) and VISC (vector integrated streak camera), which replicate the functionality of a CSC on a single CMOS chip. The MISC structure consists of a lens, which spreads the photon flux on the surface of a specific pixel array-based (Bi)CMOS sensor. The VISC architecture is based on a sensor featuring a single column of photodetectors, where each element is coupled to a front-end and a multi-sampling and storage unit. In this case the optical objective used in front of the sensor focuses the luminous event on the several tens of micrometers wide photosensitive column. For both architectures, the spatial resolution is linked to the size of the photodetector and the temporal resolution is determined by the bandwidths of the photodetectors and the signal conditioning electronics. The capture of a 6 ns full width at half maximum 532 nm laser pulse is reported for two generations of MISC and a first generation of VISC.

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

2010-11-01

245

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

246

Multiple roles of Wheat streak mosaic virus coat protein in virus biology  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat streak mosaic virus (WSMV) is an economically important member of the Potyviridae family impacting wheat production in the Great Plains region. The role of WSMV coat protein (CP) in virus biology was examined by introducing a series of point or deletion mutations into the CP cistron, and it wa...

247

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

248

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

Microsoft Academic Search

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

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

2009-01-01

249

Interactive Separating Streak Surfaces Florian Ferstl, Kai Burger, Holger Theisel, and Rudiger Westermann  

E-print Network

ridges on a planar seeding probe. Green particles show points on time surfaces, which are additionally released from the seeding plane into the flow and serve as context information. Abstract--Streak surfaces. The computation of such separation surfaces requires to place seeding structures at the separation locations

250

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

251

Investigations on Genetically Modified Maize (Bt-Maize) in Pig Nutrition: Chemical Composition and Nutritional Evaluation  

Microsoft Academic Search

The objective of the present study was to determine the composition and the nutritional value of parental and transgenic maize seeds fed to pigs. The parental maize line was genetically modified to incorporate a gene from Bacillus thuringiensis (Bt) expressing a toxin against the European corn borer (Ostrinia nubilalis). Both (parental and transgenic) maize lines were analyzed for crude nutrients,

T. Reuter; Karen Aulrich; A. Berk; G. Flachowsky

2002-01-01

252

Kernel Composition, Starch Structure, and Enzyme Digestibility of Opaque-2 Maize and Quality Protein Maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Objectives of this study were to understand how opaque-2 (o2) mutation and quality protein maize (QPM) affect maize kernel composition and starch structure, property, and enzyme digestibility. Kernels of o2 maize contained less protein (9.6−12.5%) than those of the wild-type (WT) counterparts (12...

253

In planta reduction of maize seedling stalk lesions by the bacterial endophyte Bacillus mojavensis.  

PubMed

Maize (Zea mays L.) is susceptible to infection by Fusarium verticillioides through autoinfection and alloinfection, resulting in diseases and contamination of maize kernels with the fumonisin mycotoxins. Attempts at controlling this fungus are currently being done with biocontrol agents such as bacteria, and this includes bacterial endophytes, such as Bacillus mojavensis . In addition to producing fumonisins, which are phytotoxic and mycotoxic, F. verticillioides also produces fusaric acid, which acts both as a phytotoxin and as an antibiotic. The question now is Can B. mojavensis reduce lesion development in maize during the alloinfection process, simulated by internode injection of the fungus? Mutant strains of B. mojavensis that tolerate fusaric acid were used in a growth room study to determine the development of stalk lesions, indicative of maize seedling blight, by co-inoculations with a wild-type strain of F. verticillioides and with non-fusaric acid producing mutants of F. verticillioides. Lesions were measured on 14-day-old maize stalks consisting of treatment groups inoculated with and without mutants and wild-type strains of bacteria and fungi. The results indicate that the fusaric-acid-tolerant B. mojavensis mutant reduced stalk lesions, suggesting an in planta role for this substance as an antibiotic. Further, lesion development occurred in maize infected with F. verticillioides mutants that do not produce fusaric acid, indicating a role for other phytotoxins, such as the fumonisins. Thus, additional pathological components should be examined before strains of B. mojavensis can be identified as being effective as a biocontrol agent, particularly for the control of seedling disease of maize. PMID:21635192

Bacon, Charles W; Hinton, Dorothy M

2011-06-01

254

Identification and validation of sugarcane streak mosaic virus-encoded microRNAs and their targets in sugarcane.  

PubMed

Plants have developed several defense mechanisms to cope with various pathogens (bacteria, fungi, virus, and phytoplasma). Among these, RNA interference (RNAi)-mediated defense against viral infection was found to be a major innate immune response. As a counter attack strategy against the host defense, viruses produce suppressors of host RNAi pathway. MicroRNAs (miRNAs) are an abundant class of short (~18-22 nucleotide) non-coding single-stranded RNAs involved in RNAi pathway leading to post-transcriptional regulation of gene expression. Sugarcane streak mosaic virus (SCSMV) is a distinct strain of Potyviridae family which has a single-stranded positive-sense RNA genome causing mosaic disease in sugarcane. In this study, we computationally predicted and experimentally validated the miRNA encoded by the SCSMV genome with detection efficiency of 99.9 % in stem-loop RT-qPCR and predicted their potential gene targets in sugarcane. These sugarcane target genes considerably broaden future investigation of the SCSMV-encoded miRNA function during viral pathogenesis and might be applied as a new strategy for controlling mosaic disease in sugarcane. PMID:24145912

Viswanathan, Chandran; Anburaj, Jeyaraj; Prabu, Gajjeraman

2014-02-01

255

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

256

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

257

Heterosis of maize photosynthetic performance  

Microsoft Academic Search

Four maize inbred lines with different photosynthetic rates and their two hybrids were used as test materials, and the diurnal\\u000a variations of their photosynthesis parameters in the silking stage were measured to study the heterosis of photosynthetic\\u000a performance. Results showed that net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) all presented an obvious single-peaked curve in a

Xia Li; Lianlu Li; Meiyun Wang; Zaisong Ding; Ming Zhao

2007-01-01

258

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

259

On Maize and the Sunflower  

NSDL National Science Digital Library

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

Dolores R. Piperno (Smithsonian Tropical Research Institute ;)

2001-06-22

260

Nutritional evaluation and utilisation of quality protein maize, Nityashree hybrid maize, and normal maize in broiler chickens.  

PubMed

Three experiments were conducted to determine the apparent metabolisable energy, apparent digestible amino acid values, and utilisation of three maize varities in chickens: quality protein maize (QPM), hybrid maize Nityashree (HMN) and normal maize (NM). There was no significant difference in the apparent metabolisable energy (AME) content amongst the three varieties of maize. Lysine and threonine digestibilities were significantly higher in QPM compared to either HMN or NM. No difference in the digestibilities of other amino acids occurred among the three different maize varieties. There was no difference between diets containing NM or HMN for body weight gain (21 and 40?d of age) and overall feed conversion ratio (0-40?d), but values were significantly higher for QPM (and Lys-supplemented NM) diets. The relative weights of dressed meat yield and giblets were unaffected by dietary replacement of NM with QPM, HMN, or Lys supplementation of the NM diet. However, abdominal fat content decreased and breast meat yield increased with both dietary replacement of NM with QPM and Lys supplementation of the NM diet. The concentration of protein in serum was significantly increased by dietary replacement of NM with QPM. Adding Lys to the NM based diet significantly increased the Ca concentration in serum compared with NM or HMN diets. However, the highest concentration of Ca in serum was found in the QPM diet. The concentration of total cholesterol in serum significantly decreased by either replacing NM with QPM or adding Lys to the NM based diet, compared with the NM diet. These results suggested that the feeding value of quality protein maize was superior to normal maize, while the feeding value of hybrid maize Nityashree was similar to that of normal maize. PMID:22029791

Panda, A K; Raju, M V L N; Rao, S V Rama; Lavanya, G; Reddy, E Pradeep Kumar; Sunder, G Shyam

2011-10-01

261

Functional Allelic Variation at Key Photoperiod Response QTL in Maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tropical maize represents a valuable genetic resource containing unique alleles not present in elite temperate maize. The strong delay in flowering in response to long daylength photoperiods exhibited by most tropical maize hinders its incorporation into temperate maize breeding programs. We tested ...

262

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; accepted18 June 1998) Abstract - Maize was grown simultaneously under artificial and under natural shade the maize developed and yielded. Under our experimental conditions, where photosynthetically active

Paris-Sud XI, Université de

263

Cell wall composition and in vitro fermentation characteristics of maize  

E-print Network

Cell wall composition and in vitro fermentation characteristics of maize HJP Marvin, CF Krechting (OMD) has been the most important forage quality characteristic. Consequently, maize breeders have put-cell walls of maize, we have generated a series of homozygous recombinant inbred lines of maize (RILs

Boyer, Edmond

264

Relationships between digestibility and cell wall structure of forage maize  

E-print Network

Relationships between digestibility and cell wall structure of forage maize JM Besle V Serre MP studied in maize whole crop. Whole plants of normal maize were collected at six stages after flowering (1 by the heterogeneity and complexity of whole maize, but the phenylpropanoid components can be utilized to predict

Paris-Sud XI, Université de

265

Research Paper High-throughput phenotyping technology for maize roots  

E-print Network

Research Paper High-throughput phenotyping technology for maize roots T.E. Grift a, *, J. Novais b-throughput measurement techniques allowing acquisition of phenotypical data describing maize roots. One of a maize root maize inbreds B73 and CML333. B73 and CML333 are known to have different root characteristics

266

REGULAR ARTICLE Field decomposition of transgenic Bt maize residue  

E-print Network

REGULAR ARTICLE Field decomposition of transgenic Bt maize residue and the impact on non modified Bacillus thuringiensis Berliner (Bt) maize (Zea mays L.) expressing Cry toxins against various of Bt maize expressing the Cry1Ab protein on both the soil community and maize residue decomposition. We

Richner, Heinz

267

MaizeGDB's new data types, resources, and activities  

Technology Transfer Automated Retrieval System (TEKTRAN)

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, molecul...

268

The genetic architecture of maize height  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 (IBS) among related plants, height is also accurately predictable. But, mapping alleles explaining natural variation in maize height remains a formida...

269

Gene expression in physically impeded maize roots  

E-print Network

clones, TCH1 induced by wind stress in Arabidopsis, and LP2 induced by drought stress in pine, had high homology with the RNA in maize root tips, but they did not reveal an inducible pattern of expression in the impeded maize roots tips. Second, a cDNA...

Huang, Ying-Fei

2012-06-07

270

A meteorologically driven maize stress indicator model  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

271

Resistance in maize to Paratrichodorus minor  

Technology Transfer Automated Retrieval System (TEKTRAN)

The stubby-root nematode Paratrichodorus minor is widespread in the southeastern United States. Maize is both a good host for reproduction and sensitive to feeding damage from this nematode. The primary objective of this study was to evaluate commercial maize hybrids and public inbred lines for re...

272

Maize metabolic network construction and transcriptome analysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

A framework for understanding the synthesis and catalysis of metabolites and other biochemicals by proteins is crucial for unraveling the physiology of cells. To create such a framework for Zea mays ssp. mays (maize), we developed MaizeCyc a metabolic network of enzyme catalysts, proteins, carbohydr...

273

Use of tropical maize for bioethanol production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lo...

274

FUNCTIONAL GENOMICS OF ENDOSPERM DEVELOPMENT IN MAIZE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Maize Endosperm Functional Genomics Project is developing tools for the molecular cloning of seed mutants in maize. Specifically, we are developing normalized and subtracted ESTs from endopserm cDNA libraries, identifying transposon-tagged endosperm mutants from the mutagenic inbred, UniformMu, ...

275

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

276

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

SciTech Connect

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

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

2010-10-15

277

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

SciTech Connect

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

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

2008-05-09

278

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

SciTech Connect

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

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

2011-08-02

279

New Experimental Hosts of Tobacco streak virus and Absence of True Seed Transmission in Leguminous Hosts  

Microsoft Academic Search

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,\\u000a stunting, total necrosis and wilt) symptoms are observed by majority of plant species. Eleven new experimental hosts were\\u000a identified viz., Amaranthus blitum var. oleracea (Chaulai sag), Celosia cristata (Cocks comb),

K. Vemana; R. K. Jain

2010-01-01

280

Optimally amplified large-scale streaks and drag reduction in turbulent pipe flow  

NASA Astrophysics Data System (ADS)

The optimal amplifications of small coherent perturbations within turbulent pipe flow are computed for Reynolds numbers up to one million. Three standard frameworks are considered: the optimal growth of an initial condition, the response to harmonic forcing and the Karhunen-Loève (proper orthogonal decomposition) analysis of the response to stochastic forcing. Similar to analyses of the turbulent plane channel flow and boundary layer, it is found that streaks elongated in the streamwise direction can be greatly amplified from quasistreamwise vortices, despite linear stability of the mean flow profile. The most responsive perturbations are streamwise uniform and, for sufficiently large Reynolds number, the most responsive azimuthal mode is of wave number m=1 . The response of this mode increases with the Reynolds number. A secondary peak, where m corresponds to azimuthal wavelengths ??+?70-90 in wall units, also exists in the amplification of initial conditions and in premultiplied response curves for the forced problems. Direct numerical simulations at Re=5300 confirm that the forcing of m=1,2 and m=4 optimal structures results in the large response of coherent large-scale streaks. For moderate amplitudes of the forcing, low-speed streaks become narrower and more energetic, whereas high-speed streaks become more spread. It is further shown that drag reduction can be achieved by forcing steady large-scale structures, as anticipated from earlier investigations. Here the energy balance is calculated. At Re=5300 it is shown that, due to the small power required by the forcing of optimal structures, a net power saving of the order of 10% can be achieved following this approach, which could be relevant for practical applications.

Willis, Ashley P.; Hwang, Yongyun; Cossu, Carlo

2010-09-01

281

Instability of streaks in pipe flow of shear-thinning fluids.  

PubMed

This study is motivated by recent experimental results dealing with the transition to turbulence in a pipe flow of shear-thinning fluids, where a streaky flow with an azimuthal wave number n=1 is observed in the transitional regime. Here, a linear stability analysis of pipe flow of shear-thinning fluids modulated azimuthally by finite amplitude streaks is performed. The shear-thinning behavior of the fluid is described by the Carreau model. The streaky base flows considered are obtained from two-dimensional direct numerical simulation using finite amplitude longitudinal rolls as the initial condition and by extracting the velocity field at time t(max), where the amplitude of the streaks reaches its maximum, denoted by A(max). It is found that the amplitude A(max) increases with increasing Reynolds number as well as with increasing amplitude E(0) of the initial longitudinal rolls. For sufficiently large streaks amplitude, streamwise velocity profiles develop inflection points, leading to instabilities. Depending on the threshold amplitude A(c), two different modes may trigger the instability of the streaks. If A(c) exceeds approximately 41.5% of the centerline velocity, the instability mode is located near the axis of the pipe, i.e., it is a "center mode." For weaker amplitude A(c), the instability mode is located near the pipe wall, in the region of highest wall normal shear, i.e., it is a "wall mode." The threshold amplitude A(c) decreases with increasing shear-thinning effects. The energy equation analysis indicates that (i) wall modes are driven mainly by the work of the Reynolds stress against the wall normal shear and (ii) for center modes, the contribution of the normal wall shear remains dominant; however, it is noted that the contribution of the Reynolds stress against the azimuthal shear increases with increasing shear-thinning effects. PMID:24032922

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

2013-08-01

282

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

283

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

284

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

PubMed Central

Objective(s) Cardiovascular disease causes a major clinical problem in patients with end stage renal disease. Since metabolic acidosis is very common in patients with end stage renal disease, we aimed to investigate the effect of experimentally-induced metabolic acidosis on serum lipid profile and aortic fatty streak (FS) formation in normal and high-cholesterol fed rabbits. Materials and Methods Twenty-four male rabbits were divided into four groups (n=6 each): (1) normal diet (ND): (2) hypercholesterolemic diet (HCD) (1%): (3) ND plus acidemic diet: (4) HCD plus acidemic diet. Metabolic acidosis was induced by adding 0.75% NH4Cl in drinking water. After 4 weeks, blood samples were taken and thoracic aortae were dissected for histological examinations. Results Results showed that in the animals who received NH4Cl, metabolic acidosis was successfully induced. Serum total cholesterol and low density lipoprotein (LDL) concentrations in HCD groups were significantly higher than ND groups (P<0.05) and acidosis did not significantly change serum lipid levels neither in ND nor in HCD animals (P>0.05). Histological examination of aortae showed higher mean average grades of pathological evaluation in HCD than ND groups (2.1±0.16 vs. 0±0; P<0.05). Acidosis did not further increase FS formation in HCD groups (P >0.05). Conclusion In this model of experimentally-induced metabolic acidosis, acidosis could not increase FS formation in HCD animals and it seems that it does not interfere in progression of atherosclerosis process. PMID:23653846

Khazaei, Majid; Nematbakhsh, Mehdi

2012-01-01

285

The effect of boundary conditions and shear rate on streak formation and breakdown in turbulent channel flows  

SciTech Connect

Experiments in a horizontal channel indicate that low-speed/high-speed streaks form in the region very close to the interface if shear is imposed on the liquid surface by the motion of a gas. They also form at the wall. Even though the boundary conditions at the wall and at the interface are different (no slip versus nearly free slip with regard to fluctuations), the main characteristics of the streaks appear similar. The spanwise spacing of the streaks when nondimensionalized using the local shear stress and kinematic viscosity is about 100 units whether the streaks are at the wall or at the liquid surface. The ejection and breakdown of the streaks also show qualitatively similar features. For example, the burst frequency appears to scale on local inner variables and the numerical values in nondimensionalized frequency units are about the same whether the bursts originate near the interface or the wall. A number of experiments have been done varying the shear rate at the interface to determine its role in streak formation and breakdown. From the present experiments it is concluded that the shear rate has the main influence on the phenomena and the effect of the boundary conditions is much less important.

Rashidi, M.; Banerjee, S. (Department of Chemical and Nuclear Engineering, University of California, Santa Barbara, CA (USA))

1990-10-01

286

Low Albedo Surfaces and Eolian Sediment: Mars Orbiter Camera Views of Western Arabia Terra Craters and Wind Streaks  

NASA Technical Reports Server (NTRS)

High spatial resolution (1.5 to 12 m/pixel) Mars Global Surveyor Mars Orbiter Camera images obtained September 1997 through June 2001 indicate that the large, dark wind streaks of western Arabia Terra each originate at a barchan dune field on a crater floor. The streaks consist of a relatively thin coating of sediment deflated from the dune fields and their vicinity. This sediment drapes a previous mantle that more thickly covers nearly all of western Arabia Terra. No dunes or eolian bedforms are found within the dark wind streaks, nor do any of the intracrater dunes climb up crater walls to provide sand to the wind streaks. The relations between dunes, wind streak, and subjacent terrain imply that dark-toned grains finer than those which comprise the dunes are lifted into suspension and carried out of the craters to be deposited on the adjacent terrain. Such grains are most likely in the silt size range (3.9-62.5 micrometers). The streaks change in terms of extent, relative albedo, and surface pattern over periods measured in years, but very little evidence for recent eolian activity (dust plumes, storms, dune movement) has been observed.

Edgett, Kenneth S.

2001-01-01

287

Rho kinase activity controls directional cell movements during primitive streak formation in the rabbit embryo  

PubMed Central

During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different vertebrate classes. Here, we test the impact of interfering with Rho kinase-mediated cell movements on gastrulation topography in blastocysts of the rabbit, which has a flat embryonic disc typical for most mammals. Time-lapse video microscopy, electron microscopy, gene expression and morphometric analyses of the effect of inhibiting ROCK activity showed – besides normal specification of the organizer region – a dose-dependent disruption of primitive streak formation; this disruption resulted in circular, arc-shaped or intermediate forms, reminiscent of those found in amphibians, fishes and reptiles. Our results reveal a crucial role of ROCK-controlled directional cell movements during rabbit primitive streak formation and highlight the possibility that temporal and spatial modulation of cell movements were instrumental for the evolution of gastrulation forms. PMID:25516971

Stankova, Viktoria; Tsikolia, Nikoloz; Viebahn, Christoph

2015-01-01

288

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

289

Altitude Starting Characteristics of an Afterburner with Autoignition and Hot-streak Ignition  

NASA Technical Reports Server (NTRS)

An investigation was conducted in an altitude test chamber at the NACA Lewis Laboratory to determine the altitude starting characteristics of an afterburner with autoignition and with hot-streak ignition. Transient afterburner ignition data were obtained over a range of altitudes from 30,000 to 50,000 feet at a flight Mach number of 0.60. Afterburner ignition with a torch igniter located axially at approximately the midpoint of the combustion chamber was possible over the entire range, but ignition ignition with a torch igniter located in the transition section 1 5/8 inches upstream of the turbine stators proved unsatisfactory at an altitude of 50,000 feet due to the inability to obtain flame through the turbine. Increasing the afterburner-inlet total pressure at a constant afterburner fuel-air ratio decreased the afterburner ignition time. Hot-streak ignition was possible within 2 seconds after the time required to obtain the preset, normal afterburner fuel pressure, whereas autoignition required 4 to 7 seconds for the range of altitudes investigated. Following the ignition there was a period of oscillatory operation existing in the engine-afterburner before steady-state operation was attained. The time required for steady-state stable operation decreased as afterburner inlet total pressure increased. The duration of oscillations also decreased with hot-streak ignition because the fuel-air mixture was ignited before a large volume of combustible mixture was accumulated in the afterburner.

Renas, P E; Jansen, E T; Harvey, R W , Sr

1953-01-01

290

Unsteady numerical simulation of hot streak/blades interaction and film cooling  

NASA Astrophysics Data System (ADS)

Deeply research on management and application of hot streak is an important way to breakthrough technique obstacle of aero engine hot components. Numerical method is a useful instrument to investigate the correlative problems. Firstly the paper developed independently three dimensional unsteady parallel computational code-MpiTurbo based on Fortran 90 and MPI at Linux operating system. Then unsteady numerical simulation was carried out to investigate impacts of the factors, which included circumferential locations of hot streak and clocking positions of blade rows, on the thermal environment of a 1+1 counter-rotating turbine. The results clearly indicated that clocking positions of hot streak/blade row and blade row/blade row had great influence on the time-averaged temperature distribution of the third blade row. Therefore, it can be effective for improving thermal environment of turbine to optimize blade parameters and clocking positions. Lastly film cooling layout was designed by the repetitious steady simulation based on source term method. And the flow structure detail was given by the unsteady simulation.

Yi, Weilin; Ji, Lucheng; Xiao, Yunhan

2010-10-01

291

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

292

Rho kinase activity controls directional cell movements during primitive streak formation in the rabbit embryo.  

PubMed

During animal gastrulation, the specification of the embryonic axes is accompanied by epithelio-mesenchymal transition (EMT), the first major change in cell shape after fertilization. EMT takes place in disparate topographical arrangements, such as the circular blastopore of amphibians, the straight primitive streak of birds and mammals or in intermediate gastrulation forms of other amniotes such as reptiles. Planar cell movements are prime candidates to arrange specific modes of gastrulation but there is no consensus view on their role in different vertebrate classes. Here, we test the impact of interfering with Rho kinase-mediated cell movements on gastrulation topography in blastocysts of the rabbit, which has a flat embryonic disc typical for most mammals. Time-lapse video microscopy, electron microscopy, gene expression and morphometric analyses of the effect of inhibiting ROCK activity showed - besides normal specification of the organizer region - a dose-dependent disruption of primitive streak formation; this disruption resulted in circular, arc-shaped or intermediate forms, reminiscent of those found in amphibians, fishes and reptiles. Our results reveal a crucial role of ROCK-controlled directional cell movements during rabbit primitive streak formation and highlight the possibility that temporal and spatial modulation of cell movements were instrumental for the evolution of gastrulation forms. PMID:25516971

Stankova, Viktoria; Tsikolia, Nikoloz; Viebahn, Christoph

2015-01-01

293

Benzoxazinoids in Root Exudates of Maize Attract Pseudomonas putida to the Rhizosphere  

PubMed Central

Benzoxazinoids, such as 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), are secondary metabolites in grasses. In addition to their function in plant defence against pests and diseases above-ground, benzoxazinoids (BXs) have also been implicated in defence below-ground, where they can exert allelochemical or antimicrobial activities. We have studied the impact of BXs on the interaction between maize and Pseudomonas putida KT2440, a competitive coloniser of the maize rhizosphere with plant-beneficial traits. Chromatographic analyses revealed that DIMBOA is the main BX compound in root exudates of maize. In vitro analysis of DIMBOA stability indicated that KT2440 tolerance of DIMBOA is based on metabolism-dependent breakdown of this BX compound. Transcriptome analysis of DIMBOA-exposed P. putida identified increased transcription of genes controlling benzoate catabolism and chemotaxis. Chemotaxis assays confirmed motility of P. putida towards DIMBOA. Moreover, colonisation essays in soil with Green Fluorescent Protein (GFP)-expressing P. putida showed that DIMBOA-producing roots of wild-type maize attract significantly higher numbers of P. putida cells than roots of the DIMBOA-deficient bx1 mutant. Our results demonstrate a central role for DIMBOA as a below-ground semiochemical for recruitment of plant-beneficial rhizobacteria during the relatively young and vulnerable growth stages of maize. PMID:22545111

Neal, Andrew L.; Ahmad, Shakoor; Gordon-Weeks, Ruth; Ton, Jurriaan

2012-01-01

294

Choroidal neovascularization in angioid streaks following microincision vitrectomy surgery: a case report  

PubMed Central

Background Patients with angioid streaks are prone to developing subretinal hemorrhage after ocular or head injury due to the brittleness of Bruch’s membrane. However, there have been no reports of any angioid streak patients in whom choroidal neovascularization occurred after vitrectomy surgery. We report herein a patient with angioid streaks who developed choroidal neovascularization after vitrectomy surgery for epiretinal membrane. Case presentation A 76-year-old man presented with distorted vision in his left eye, with a best corrected visual acuity of 1.2 and 0.6 in his right and left eyes, respectively. Fundus examination showed angioid streaks in both eyes and epiretinal membrane only in the left eye. The patient underwent 23-gauge three-port pars plana vitrectomy with removal of the epiretinal membrane combined with cataract surgery. Internal limiting membrane in addition to the epiretinal membrane were successfully peeled and removed, with indocyanine green dye used to visualize the internal limiting membrane. His left best corrected visual acuity improved to 0.8. An elevated lesion with retinal hemorrhage due to probable choroidal neovascularization was found between the fovea and the optic disc in the left eye at 7 weeks after surgery. Since best corrected visual acuity decreased to 0.15 and the hemorrhage expanded, posterior sub-Tenon injection of triamcinolone acetonide was performed. However, no improvement was observed. Even though intravitreal bevacizumab injection was performed a total of five times, his best corrected visual acuity remained at 0.1. Subsequently, we performed a combination treatment of a standard-fluence photodynamic therapy and intravitreal ranibizumab injection, with additional intravitreal ranibizumab injections performed 3 times after this combination treatment. Best corrected visual acuity improved to 0.5 and the size of the choroidal neovascularization markedly regressed at 4 months after the combined treatment. Conclusion Development of choroidal neovascularization could possibly occur in elderly patients with angioid streaks after vitrectomy surgery. In such cases, a combination of photodynamic therapy and intravitreal ranibizumab injection may be considered for initial treatment of the choroidal neovascularization. PMID:23829451

2013-01-01

295

Nutrient absorbtion of weeds in maize.  

PubMed

Our study was carried out in Hungary at Keszthely, in 2007. The effect of different cultivation methods: no-till drill, disk tillage, conventional tillage (ploughing) and five increasing N doses were studied on the weediness. The bi-factorial trial was arranged in split plot design with four replications. Crop rotation: winter wheat-winter wheat-maize-maize. The seeding of maize was 23rd of April in 2007. The weed survey was made with Balázs-Ujvárosi coenological method on the 17th of May. In the experiment were found 21 weed species. We collected all plants of every weed species by plots. The sample area was 1 m2. Furthermore five maize plants per plot were sampled on the 22nd of May. Maize was at 3-4 leaves stage. For reason of competition studies no herbicides were applied on sampling sites. The aerial parts of weeds and maize plants were collected, and the fresh and dry matter weight was measured. We analyzed in detail, the occurrence of weed species, and the biomass production of weeds in comparison with maize. The effect of different cultivation methods markedly demonstrated the weed cover, the number of perennial and annual weeds and the number of occurring weed species. PMID:19226848

Lehoczky, E; Kismányoky, A; Nagy, P; Németh, T

2008-01-01

296

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

Microsoft Academic Search

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

T. Reuter; Karen Aulrich; A. Berk

2002-01-01

297

Initial-state, mean-free-path, and skin-depth dependence of attosecond time-resolved IR-streaked XUV photoemission from single-crystalline magnesium  

NASA Astrophysics Data System (ADS)

We analyze the dependence of attosecond streaked photoelectron spectra and photoemission time delays from valence band (VB) and 2p core-level (CL) states of a single-crystalline Mg(0001) thin film on the (i) modeling of the substrate electronic structure, (ii) electron mean free path (MFP), (iii) screening of the near-infrared (NIR) streaking laser field, and (iv) chirp of the attosecond extreme ultraviolet (XUV) pulse. Our quantum-mechanical numerical simulations predict streaked photoemission spectra that depend sensitively on the XUV chirp and weakly on the screening of the streaking laser field by the substrate. They furthermore show that streaking time delays for VB emission are relatively insensitive to the modeling of the initial quantum states, electron MFP, and NIR skin depth of the Mg substrate, in contrast to the stronger dependence of streaking time delays for 2p CL emission on these factors.

Liao, Q.; Thumm, U.

2014-03-01

298

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

299

Choosing a Genome Browser for a Model Organism Database (MOD): Surveying the Maize Community  

Technology Transfer Automated Retrieval System (TEKTRAN)

As the maize genome sequencing is nearing its completion, the Maize Genetics and Genomics Database (MaizeGDB), the Model Organism Database for maize, integrated a genome browser to its already existing Web interface and database. The addition of the MaizeGDB Genome Browser to MaizeGDB will allow it ...

300

No Adjuvant Effect of Bacillus thuringiensis-Maize on Allergic Responses in Mice  

PubMed Central

Genetically modified (GM) foods are evaluated carefully for their ability to induce allergic disease. However, few studies have tested the capacity of a GM food to act as an adjuvant, i.e. influencing allergic responses to other unrelated allergens at acute onset and in individuals with pre-existing allergy. We sought to evaluate the effect of short-term feeding of GM Bacillus thuringiensis (Bt)-maize (MON810) on the initiation and relapse of allergic asthma in mice. BALB/c mice were provided a diet containing 33% GM or non-GM maize for up to 34 days either before ovalbumin (OVA)-induced experimental allergic asthma or disease relapse in mice with pre-existing allergy. We observed that GM-maize feeding did not affect OVA-induced eosinophilic airway and lung inflammation, mucus hypersecretion or OVA-specific antibody production at initiation or relapse of allergic asthma. There was no adjuvant effect upon GM-maize consumption on the onset or severity of allergic responses in a mouse model of allergic asthma. PMID:25084284

Dekan, Gerhard; Epstein, Michelle M.

2014-01-01

301

Mapping and validation of quantitative trait loci for resistance to Cercospora zeae-maydis infection in tropical maize ( Zea mays L.)  

Microsoft Academic Search

Breeding for resistance to gray leaf spot, caused by Cercospora zeae-maydis (Cz) is paramount for many maize environments, in particular under warm and humid growing conditions. In this study, we mapped\\u000a and characterized quantitative trait loci (QTL) involved in the resistance of maize against Cz. We confirmed the impact of\\u000a the QTL on disease severity using near-isogenic lines (NILs), and

Gilberto Pozar; David Butruille; Heyder Diniz Silva; Zoe Patterson McCuddin; Julio Cesar Viglioni Penna

2009-01-01

302

Molecular Genetics of Mitochondrial Biogenesis in Maize.  

Technology Transfer Automated Retrieval System (TEKTRAN)

The mitochondrial genome encodes proteins essential for mitochondrial respiration and ATP synthesis. Nuclear gene products, however, are required for the expression of mitochondrial genes and the elaboration of functional mitochondrial protein complexes. We are exploiting a unique collection of maiz...

303

High-value products from transgenic maize.  

PubMed

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

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

2011-01-01

304

Field performance of maize grown from Fusarium verticillioides-inoculated seed.  

PubMed

Fusarium verticillioides is an important fungus occupying dual roles in the maize plant. The fungus functions as an endophyte, a fungal/host interaction beneficial to the growth of some plants. At other times, the fungus may function as a mycotoxin producing pathogen. The advantages and/or disadvantages of the endophytic relationship must be established in order to target appropriate sites for controlling diseases and mycotoxins in maize. One possibility could be to ensure seed maize is fungal free prior to planting. Reciprocal inoculations were made with two fungal isolates on seed of two maize genotypes. Yield was measured at harvest by ear and seed characters and vegetative growth at one-month intervals for plant survival, height, weight and stem diameter. Yield and vegetative growth differed among mature plants only once based on seed inoculation status. In 1998, plant weight was reduced and seed weight per ear was increased for the dent maize, GT-MAS: gk, grown from F. verticillioides RRC 374-inoculated seed compared to other seed treatments. Most vegetative characters were reduced at the first collection for Silver Queen plants grown from F. verticillioides-inoculated seed in 1997 and 1999, but not in 1998. However, no significant differences occurred among mature Silver Queen plants during any of the three growing seasons. In conclusion, yield and vegetative growth of mature maize plants grown from F. verticillioides-inoculated seed were equal to or greater than plants grown from non-inoculated seed under south Georgia field conditions during 1997, 1998, and 1999. PMID:15750733

Yates, I E; Widstrom, N W; Bacon, C W; Glenn, A; Hinton, D M; Sparks, D; Jaworski, A J

2005-01-01

305

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

306

A Dust Devil Making a Streak and Climbing a Crater Wall  

NASA Technical Reports Server (NTRS)

MGS MOC Release No. MOC2-318, 8 August 2002 [figure removed for brevity, see original site] One of the key elements of the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) Extended Mission is to look for and monitor changes taking place on the planet over the course of a second--and, eventually, a third--martian year. MGS is now well into its second Mars year, which will draw to a close in December 2002. Among the changes the MOC has observed are streaks believed to be caused by the passage of dust devils. Thousands of MOC images show these streaks, dozens show that they change over time, but far fewer images have actually captured a dust devil in the act of creating a streak. At the center right of this image (above left) is a dust devil that, on May 21, 2002, was seen climbing the wall of a crater at 4.1oS, 9.5oW. This crater (above right) is in western Terra Meridiani. The dust devil was moving toward the northeast (upper right), leaving behind a dark trail where a thin coating of surficial dust was removed or disrupted as the dust devil advanced. Dust devils most commonly form after noon on days when the martian air is still (that is, when there isn't even a faint breeze). On such days, the ground is better able to heat up the air immediately above the surface. As the warmed near-surface air begins to rise, it also begins to spin, creating a vortex. The spinning column then moves across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it a tornado-like appearance. The dust devil in this image has a very short, dark shadow cast to the right of the bright column; this shadow is short because the sun was nearly overhead.

2002-01-01

307

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

SciTech Connect

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

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

2012-08-15

308

Conserved terminal nucleotide sequences in the genome of rice black streaked dwarf virus.  

PubMed

The terminal regions of the dsRNA genome segments of rice black streaked dwarf virus (RBSDV) were sequenced. The individual dsRNAs, which were 32P-labelled at their 3' termini by incubation with [32P]pCp and T4RNA ligase, were separated by 5% PAGE, and the 10 dsRNA segments were sequenced by two-dimensional electrophoresis. The common 3'-terminal sequences ---GUC 3' and ---AAAAACUU 3' were found in the plus and minus strands, respectively. The strictly conserved terminal sequences (5' AAGUUUUU ... GUC 3') of the genome segments of RBSDV differ from those of the phytoreoviruses and rice ragged stunt virus. PMID:1607875

Azuhata, F; Uyeda, I; Shikata, E

1992-06-01

309

Study of the Performance of a Streaked Optical Pyrometer System for Temperature Measurement of Shocked Materials  

NASA Astrophysics Data System (ADS)

A streaked optical pyrometer (SOP) is developed and calibrated for the measurement of the temperature of shocked materials. In order to achieve a higher relative sensitivity, a one-channel scheme is adopted for the system. The system is calibrated with a shocked step-shaped aluminum sample in the SG-III prototype laser facility. The relation between the count number in the detection system and the sample temperature is thus obtained, which can be adopted to infer the temperature of any shocked materials in future experiments.

Zhang, Chen; Liu, Hao; Wang, Zhebin; Jiang, Xiaohua; Zhang, Huige; Liu, Yonggang; Li, Zhichao; Li, Sanwei; Yang, Dong; Ding, Yongkun; Zhao, Bin; Hu, Guangyue; Zheng, Jian

2014-06-01

310

An accumulative x-ray streak camera with 280-fs resolution  

NASA Astrophysics Data System (ADS)

We demonstrated a significant improvement in the resolution of the x-ray streak camera by reducing the electron beam size in the deflection plates. This was accomplished by adding a slit in front of the focusing lens and the deflection plates. The temporal resolution reached 280 fs when the slit width was 5 mm. The camera was operated in an accumulative mode and tested by using a 25 fs laser with 2 kHz repetition rate and 1-2% RMS pulse energy stability. We conclude that deflection aberrations, which limit the resolution of the camera, can be appreciably reduced by eliminating the wide-angle electrons.

Shakya, Mahendra M.; Chang, Zenghu

2004-11-01

311

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

SciTech Connect

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

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

2007-03-23

312

Expression of an anthranilate synthase from maize mutant bf-1 in maize line HiII  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize mutant bf-1 was one of a series of maize mutants generated by radiation from the Bikini Atoll atomic bomb test in 1946. It is characterized by blue fluorescence in seedlings and anthers under ultraviolet illumination and by mutant plants giving off a characteristic grape-like odor due to the ...

313

The Other NPGS Maize Collection – A Rich Source of Maize Genetic Diversity  

Technology Transfer Automated Retrieval System (TEKTRAN)

The maize collection at the North Central Regional Plant Introduction Station, Ames, IA is comprised of over 18,300 accessions from all over the world. Of these, 16,000 are maize accessions with population level genetic diversity and over 2,000 are inbred lines with little segregation. The collectio...

314

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

Microsoft Academic Search

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

Isabel Murillo; Laura Cavallarin; Blanca San

1997-01-01

315

Species of Cercospora associated with grey leaf spot of maize.  

PubMed

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

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

2006-01-01

316

Species of Cercospora associated with grey leaf spot of maize  

PubMed Central

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

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

2006-01-01

317

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

318

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

319

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

320

A single domestication for maize shown by multilocus microsatellite genotyping  

PubMed Central

There exists extraordinary morphological and genetic diversity among the maize landraces that have been developed by pre-Columbian cultivators. To explain this high level of diversity in maize, several authors have proposed that maize landraces were the products of multiple independent domestications from their wild relative (teosinte). We present phylogenetic analyses based on 264 individual plants, each genotyped at 99 microsatellites, that challenge the multiple-origins hypothesis. Instead, our results indicate that all maize arose from a single domestication in southern Mexico about 9,000 years ago. Our analyses also indicate that the oldest surviving maize types are those of the Mexican highlands with maize spreading from this region over the Americas along two major paths. Our phylogenetic work is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands. We also found only modest evidence for postdomestication gene flow from teosinte into maize. PMID:11983901

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

2002-01-01

321

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

322

FLORETS AND ROSETTES: MERISTEM GENES IN MAIZE AND ARABIDOPSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize and Arabidopsis genes that regulate inflorescence development are contrasted. Genes that regulate meristem size are often conserved, whereas genes that regulate meristem identity in maize do not have readily identifiable orthologs in Arabidopsis....

323

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

324

Immunodiagnosis of episomal Banana streak MY virus using polyclonal antibodies to an expressed putative coat protein.  

PubMed

A cryptic Badnavirus species complex, known as banana streak viruses (BSV) poses a serious threat to banana production and genetic improvement worldwide. Due to the presence of integrated BSV sequences in the banana genome, routine detection is largely based on serological and nucleo-serological diagnostic methods which require high titre specific polyclonal antiserum. Viral structural proteins like coat protein (CP) are the best target for in vitro expression, to be used as antigen for antiserum production. However, in badnaviruses precise CP sequences are not known. In this study, two putative CP coding regions (p48 and p37) of Banana streak MY virus (BSMYV) were identified in silico by comparison with caulimoviruses, retroviruses and Rice tungro bacilliform virus. The putative CP coding region (p37) was in vitro expressed in pMAL system and affinity purified. The purified fusion protein was used as antigen for raising polyclonal antiserum in rabbit. The specificity of antiserum was confirmed in Western blots, immunosorbent electron microscopy (ISEM) and antigen coated plate-enzyme linked immunosorbent assay (ACP-ELISA). The antiserum (1:2000) was successfully used in ACP-ELISA for specific detection of BSMYV infection in field and tissue culture raised banana plants. The antiserum was also utilized in immuno-capture PCR (IC-PCR) based indexing of episomal BSMYV infection. This is the first report of in silico identification of putative CP region of BSMYV, production of polyclonal antiserum against recombinant p37 and its successful use in immunodetection. PMID:24977315

Sharma, Susheel Kumar; Kumar, P Vignesh; Baranwal, Virendra Kumar

2014-10-01

325

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

SciTech Connect

At the Fermilab A0 photoinjector facility, bunch-length measurements of the laser micropulse and the e-beam micropulse have been done in the past with a fast single-sweep module of the Hamamatsu C5680 streak camera with an intrinsic shot-to-shot trigger jitter of 10 to 20 ps. We have upgraded the camera system with the synchroscan module tuned to 81.25 MHz to provide synchronous summing capability with less than 1.5-ps FWHM trigger jitter and a phase-locked delay box to provide phase stability of {approx}1 ps over 10s of minutes. 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.; /Fermilab

2012-03-01

326

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

327

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

328

Tumors of Bilateral Streak Gonads in Patients with Disorders of Sex Development Containing Y Chromosome Material  

PubMed Central

Abstract The presence of Y chromosome material in patients with disorders of sex development (DSD) has been associated with a high risk of gonadoblastoma. Therefore, gonadectomy is recommended in females with bilateral streak gonads and Y chromosome material. The aim of this study was to present our experience with prophylactic gonadectomy in those patients and evaluate their risk of gonadal tumors. We reviewed the charts of 11 female patients who had bilateral gonadectomy (by laparoscopically in 9 patients, by laparotomy in 2 patients) between 1991 and 2012 at our hospital. Seven patients with Turner syndrome (TS) who carry a Y mosaic karyotype in peripheral blood, 3 patients with Swyer syndrome and one patient with Frasier syndrome were included. All patients had an unambiguous female phenotype. Age at surgery and follow-up ranged from 2 to 23 (mean 11) and 0.5 to 20 (mean 8) yr, respectively. Pathologic examination revealed gonadal tumors in 6 of 11 patients (56%), including 4 with TS, the youngest of which was 2 yr old, one with Swyer syndrome and one with Frasier syndrome. A gonadoblastoma was detected in 8 gonads, and an association of dysgerminoma with gonadoblastoma was detected in 2 gonads. Imaging studies showed no metastasis, and the postoperative course was uneventful in all patients. In our series of DSD patients with bilateral streak gonads and Y chromosome material, the risk of gonadal tumor was high. Considering the early occurrence of gonadoblastoma and its high potential for malignant transformation, early prophylactic gonadectomy is strongly recommended. PMID:25110393

Matsumoto, Fumi; Shimada, Kenji; Ida, Shinobu

2014-01-01

329

Modal description of optimal internal streaks in a Falkner-Skan Boundary Layer  

NASA Astrophysics Data System (ADS)

Understanding the growing disturbances in boundary layers is of crucial interest for numerous engineering applications. Here we examine the optimal streaky perturbations (which maximize energy growth) in a wedge flow boundary layer. These 3D perturbations are governed by a system of equations obtained by linearizing the 3D Navier-Stokes equations around the base flow given by the Falkner-Skan similarity solution. Based on an asymptotic analysis of this system near the free stream and the leading edge singularity, we show that optimal streaks can be described in terms of a single streamwise-growing solution of the linearized equations, which is associated with an eigenvalue problem first formulated in this context by Tumin (Phys. Fluids 13, 5, (2001)). Such a solution may be regarded as an internal spatially-unstable mode, in analogy with the usual eigenmodes of standard linear stability theory. An important consequence of this result is that the optimization procedure heretofore used to define optimal streaks is not necessary. Comparison with previous results in A.Tumin and D.E. Ashpis AIAA (2003) show excellent agreement.

Sanchez-Alvarez, Jose; Higuera, Maria; Vega, Jose Manuel

2009-11-01

330

Study Progress on Tissue Culture of Maize Mature Embryo  

NASA Astrophysics Data System (ADS)

It has been paid more and more attention on maize tissue culture as it is a basic work in maize genetic transformation, especially huge breakthrough has been made in maize tissue culture utilizing mature embryos as explants in the recent years. This paper reviewed the study progress on maize tissue culture and plant regeneration utilizing mature embryos as explants from callus induction, subculture, plant regeneration and browning reduction and so on.

Wang, Hongzhen; Cheng, Jun; Cheng, Yanping; Zhou, Xioafu

331

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

332

Protocol to Sterilize & Charcoal-Germinate Maize Seeds 1 PROTOCOL TO STERILIZE AND CHARCHOAL-GERMINATE MAIZE SEEDS  

E-print Network

Protocol to Sterilize & Charcoal-Germinate Maize Seeds 1 PROTOCOL TO STERILIZE AND CHARCHOAL-GERMINATE MAIZE SEEDS (Last revised August 2010) This protocol is used for germinating moldy seeds that would

Wurtele, Eve Syrkin

333

Vascular Streak Dieback of cacao in Southeast Asia and Melanesia: in planta detection of the pathogen and a new taxonomy.  

PubMed

Vascular Streak Dieback (VSD) disease of cacao (Theobroma cacao) in Southeast Asia and Melanesia is caused by a basidiomycete (Ceratobasidiales) fungus Oncobasidium theobromae (syn. =Thanatephorus theobromae). The most characteristic symptoms of the disease are green-spotted leaf chlorosis or, commonly since about 2004, necrotic blotches, followed by senescence of leaves beginning on the second or third flush behind the shoot apex, and blackening of infected xylem in the vascular traces at the leaf scars resulting from the abscission of infected leaves. Eventually the shoot apex is killed and infected branches die. In susceptible cacao the fungus may grow through the xylem down into the main stem and kill a mature cacao tree. Infections in the stem of young plants prior to the formation of the first 3-4 lateral branches usually kill the plant. Basidiospores released from corticioid basidiomata developed on leaf scars or along cracks in the main vein of infected leaves infect young leaves. The pathogen commonly infects cacao but there are rare reports from avocado. As both crops are introduced to the region, the pathogen is suspected to occur asymptomatically in native vegetation. The pathogen is readily isolated but cultures cannot be maintained. In this study, DNA was extracted from pure cultures of O. theobromae obtained from infected cacao plants sampled from Indonesia. The internal transcribed spacer region (ITS), consisting of ITS1, 5.8S ribosomal RNA and ITS2, and a portion of nuclear large subunit (LSU) were sequenced. Phylogenetic analysis of ITS sequences placed O. theobromae sister to Ceratobasidium anastomosis groups AG-A, AG-Bo, and AG-K with high posterior probability. Therefore the new combination Ceratobasidium theobromae is proposed. A PCR-based protocol was developed to detect and identify C. theobromae in plant tissue of cacao enabling early detection of the pathogen in plants. A second species of Ceratobasidium, Ceratobasidium ramicola, identified through ITS sequence analysis, was isolated from VSD-affected cacao plants in Java, and is widespread in diseased cacao collected from Indonesia. PMID:22208598

Samuels, Gary J; Ismaiel, Adnan; Rosmana, Ade; Junaid, Muhammad; Guest, David; McMahon, Peter; Keane, Philip; Purwantara, Agus; Lambert, Smilja; Rodriguez-Carres, Marianela; Cubeta, Marc A

2012-01-01

334

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

335

Comprehensive genotyping of the USA national maize inbred seed bank  

Technology Transfer Automated Retrieval System (TEKTRAN)

The germplasm bank at the USDA-ARS North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa, preserves maize inbred lines from breeding programs from all over the world, including some of the key lines from the breeding history of maize. We genotyped 2,815 maize inbred accessions, mo...

336

MAIZE TROPICAL VINE LEGUME INTERCROPPING FOR SILAGE IN TEMPERATE CLIMATES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize silage (Zea mays) comprises an increasing proportion of US Midwestern dairy cow rations. A weakness of maize silage is its lower protein levels; however, maize silage protein and biomass yield might be enhanced by intercropping with legumes. This study measured forage quality and dry matter pe...

337

INTRODUCTION The maize leaf is a photosynthetic organ comprising three  

E-print Network

INTRODUCTION The maize leaf is a photosynthetic organ comprising three basic parts; the proximal. The leaf is one component of a phytomer, the basic, repeating structural unit of the maize plant (Galinat, 1959). A maize phytomer comprises the basal internode and lateral bud (the tiller, or the ear with its

Pawlowski, Wojtek

338

NEWS AND COMMENTARY Massive changes of the maize  

E-print Network

............................................................... Massive changes of the maize genome are caused by Helitrons SK Lal and LC Hannah-winning work of Barbara McClintock some 50 years ago was that genetic elements of the maize genome move from- tinguishing two well-known maize lines is due to a newly-described class of transposable elements termed

339

ORIGINAL ARTICLE Maize host requirements for Ustilago maydis tumor induction  

E-print Network

ORIGINAL ARTICLE Maize host requirements for Ustilago maydis tumor induction Virginia Walbot Ã? vegetative and floral develop- ment in maize (Zea mays L.). After fungal injection into immature tassels-sterile maize mutants with defects in anther cell division patterns and cell fate acquisition prior to meiosis

Kay, Mark A.

340

Maize Centromeres and Knobs (neocentromeres) R. Kelly Dawe  

E-print Network

Maize Centromeres and Knobs (neocentromeres) R. Kelly Dawe Abstract In most species, the only chromosomal domains that interact with the cytoskeleton are the centromeres. However in maize there are two, University of Georgia, Athens, GA 30602 J.L. Bennetzen and S.C. Hake (eds.), Handbook of Maize, 239

341

RESEARCH PAPER Maize ribosome-inactivating proteins (RIPs) with  

E-print Network

RESEARCH PAPER Maize ribosome-inactivating proteins (RIPs) with distinct expression patterns have species. The maize RIP is unusual among the plant RIPs because it is synthesized as an inactive precursor (also known as maize proRIP1 or b-32). The proenzyme undergoes proteolytic activation that results

Bass, Hank W.

342

INVESTIGATION Evidence for a Natural Allelic Series at the Maize  

E-print Network

INVESTIGATION Evidence for a Natural Allelic Series at the Maize Domestication Locus teosinte architecture and ear morphology between domesticated maize and teosinte; however, the effect of tb1 on trait teosinte alleles of tb1 that were introgressed into an isogenic maize inbred background. Our results

Doebley, John

343

Bioclimatology Source-sink relationships in maize grown  

E-print Network

Bioclimatology Source-sink relationships in maize grown in a cool-temperate area SA Uhart, FH maize yield in Balcarce (Argentina 37°45'LS; 58°18'LO) is limited by the source of assimilates. Nevertheless, a tendency toward a source limitation was evident in the long season hybrid. Zea mays = maize

Paris-Sud XI, Université de

344

Original article Composition and nutritive value of whole maize  

E-print Network

Original article Composition and nutritive value of whole maize plants fed fresh to sheep. II coefficient of whole plant maize used for silage. The new equations account for 60 to 70% of the variability level and set up a wider data base. feeding value I maize I digestibility I in vivo I Near Infrared

Paris-Sud XI, Université de

345

Original article Analysis of local limitations to maize yield  

E-print Network

Original article Analysis of local limitations to maize yield under tropical conditions Joseph Weya in maize was tested. The test was based on a survey carried out in west Burkina-Faso, with a total of 437 farmers, over a period of 3 years. Data on weather, soil, farm, maize (cul- tural practices, and, on two

Paris-Sud XI, Université de

346

Original article Genetic analysis of root traits in maize  

E-print Network

Original article Genetic analysis of root traits in maize Emmanuelle Guingoa Yannick Héberta Alain December 1997; accepted 27 April 1998) Abstract - In many areas around the world, maize (Zea Mays L.) crops@lusignan.inra.fr #12;1. INTRODUCTION Selection for increased root lodging resistance is an important objective of maize

Paris-Sud XI, Université de

347

Plant breeding Brown-midrib genes of maize: a review  

E-print Network

Plant breeding Brown-midrib genes of maize: a review Y Barrière* O Argillier INRA, Station d incrustration. Four brown-midrib genes (bm1, bm2, bm3 and bm4) have been described in maize. Brown-midrib plants when using well-adapted breeding methods, with normal lines of a very high agronomical value. maize

Paris-Sud XI, Université de

348

Original article Ground cover and leaf area index of maize  

E-print Network

Original article Ground cover and leaf area index of maize and sugar beet crops B Andrieu JM. For both maize (Zea mays L, var Dea) and sugar beet (Beta vul- garis, var Matador), we found the extinction crop geometry. maize / sugar beet / leaf area index / ground cover / photography Résumé — Taux de

Paris-Sud XI, Université de

349

Original article Composition and nutritive value of whole maize  

E-print Network

Original article Composition and nutritive value of whole maize plants fed fresh to sheep. I) Summary — The composition and digestibility by sheep of 15 commercial maize varieties and 1 brown conditions, the digestibility of a given maize hybrid increases significantly with growth stage, whereas

Boyer, Edmond

350

Plant improvement Genetic variation for heterotrophic growth in maize  

E-print Network

Plant improvement Genetic variation for heterotrophic growth in maize in relation to temperature C was conducted in the frame of early maize (Zea mays L) adaptation to northern Eu- rope climatic conditions, and for optimum temperature between 27 and 30 °C). maize / temperature / heterotrophic growth / radicle / non

Boyer, Edmond

351

Original article Do changes in the azimuthal distribution of maize  

E-print Network

Original article Do changes in the azimuthal distribution of maize leaves over time affect canopy, 86600 Lusignan, France (Received 16 September 1998; accepted 22 February 1999) Abstract - In maize are distributed uniformly. Once we had demonstrated azimuthal re-orientation of maize leaves during the vegetative

Paris-Sud XI, Université de

352

Influence of maize genotype on rate of ruminal starch degradation  

E-print Network

Influence of maize genotype on rate of ruminal starch degradation B Michalet-Doreau1 M Champion2 influence ruminal starch degradation. The trial was performed on two maize cultivars characterised:25 for "waxy", "normal" and "extender"starchs, respectively. The 6 maize were ground to 2 mm mesh size

Paris-Sud XI, Université de

353

Plant physiology Relative efficiency of two zinc sources for maize  

E-print Network

Plant physiology Relative efficiency of two zinc sources for maize (Zea mays L.) in two calcareous; Effects of 2 Zn sources (ZnEDTA and ZnS04) and 4 Zn levels on the growth and Zn utilization by maize with regard to the growth and Zn accumulation. Maize seedlings grown in the Bajgah soil produced more dry

Paris-Sud XI, Université de

354

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 with rice (Oryza sativa) and maize (Zea mays) nuclear RNase P. By successively employing ion from rice (Pusa Basmati-1) and maize (Black Mexican Sweet) calli. Details of the purification

Gopalan, Venkat

355

The B73 Maize Genome: Complexity, Diversity, and Dynamics  

E-print Network

The B73 Maize Genome: Complexity, Diversity, and Dynamics Patrick S. Schnable,1,2,3,4 * Doreen Ware. Wilson7,33 We report an improved draft nucleotide sequence of the 2.3-gigabase genome of maize of the domestication and agricultural improvements of maize. M aize (Zea mays ssp. mays L.) was do- mesticated over

356

BREEDING MAIZE FOR RESISTANCE TO MYCOTOXINS AT IITA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ear rot causing fungi including Aspergillus and Fusarium are common in maize in West and Central Africa. These fungi contaminate maize with mycotoxins that pose serious potential health hazards to humans in the sub-region. In an effort to develop maize germplasm with resistance to aflatoxin contam...

357

Biochar mitigation of allelopathy induced yield loss in continuous maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Continuous maize yields are limited by the release of phytotoxic compounds as the previous year’s maize residue decomposes. We tested the hypothesis that soil biochar applications could help mitigate maize autotoxicity and the associated yield depression. Eighteen small field plots (23.7 m2) were es...

358

Complete Genome Sequence of "Candidatus Sulcia muelleri" ML, an Obligate Nutritional Symbiont of Maize Leafhopper (Dalbulus maidis).  

PubMed

"Candidatus Sulcia muelleri" is a symbiont of sap-feeding insects in the suborder Auchenorrhyncha. The strain "Ca. Sulcia muelleri" ML is associated with the maize leafhopper (Dalbulus maidis), collected in Brazil, which is a disease vector that affects corn production. Here, we report the complete genome sequence of this bacterium. PMID:25635014

Chang, Hsing-Hua; Cho, Shu-Ting; Canale, Maria C; Mugford, Sam T; Lopes, João R S; Hogenhout, Saskia A; Kuo, Chih-Horng

2015-01-01

359

Complete Genome Sequence of “Candidatus Sulcia muelleri” ML, an Obligate Nutritional Symbiont of Maize Leafhopper (Dalbulus maidis)  

PubMed Central

“Candidatus Sulcia muelleri” is a symbiont of sap-feeding insects in the suborder Auchenorrhyncha. The strain “Ca. Sulcia muelleri” ML is associated with the maize leafhopper (Dalbulus maidis), collected in Brazil, which is a disease vector that affects corn production. Here, we report the complete genome sequence of this bacterium. PMID:25635014

Chang, Hsing-Hua; Cho, Shu-Ting; Canale, Maria C.; Mugford, Sam T.; Lopes, João R. S.; Hogenhout, Saskia A.

2015-01-01

360

Regulation of pathogenesis by light in Cercospora zeae-maydis: Identification of a photoreceptor required for infection of maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cercospora zeae-maydis causes gray leaf spot, one of the most prevalent and damaging foliar diseases of maize throughout the world. Light plays a key role in the virulence of C. zeae-maydis by inducing the biosynthesis of cercosporin, a photosensitizing, non-host-specific phytotoxin. We determined t...

361

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

PubMed Central

Fusarium ear rot is a common disease of maize that affects food and feed quality globally. Resistance to the disease is highly quantitative, and maize breeders have difficulty incorporating polygenic resistance alleles from unadapted donor sources into elite breeding populations without having a negative impact on agronomic performance. Identification of specific allele variants contributing to improved resistance may be useful to breeders by allowing selection of resistance alleles in coupling phase linkage with favorable agronomic characteristics. We report the results of a genome-wide association study to detect allele variants associated with increased resistance to Fusarium ear rot in a maize core diversity panel of 267 inbred lines evaluated in two sets of environments. We performed association tests with 47,445 single-nucleotide polymorphisms (SNPs) while controlling for background genomic relationships with a mixed model and identified three marker loci significantly associated with disease resistance in at least one subset of environments. Each associated SNP locus had relatively small additive effects on disease resistance (±1.1% on a 0–100% scale), but nevertheless were associated with 3 to 12% of the genotypic variation within or across environment subsets. Two of three identified SNPs colocalized with genes that have been implicated with programmed cell death. An analysis of associated allele frequencies within the major maize subpopulations revealed enrichment for resistance alleles in the tropical/subtropical and popcorn subpopulations compared with other temperate breeding pools. PMID:24048647

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

2013-01-01

362

DISTRIBUTION OF AND ASSOCIATION BETWEEN THE LARGER GRAIN BORER PROSTEPHANUS TRUNCATUS (HORN) (COLEOPTERA: BOSTRICHIDAE) AND THE MAIZE WEEVIL SITOPHILUS ZEAMAIS MOTSCHULSKY (COLEOPTERA: CURCULIONIDAE) IN MAIZE STORES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Interspecific interactions between the larger grain borer Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and the maize weevil Sitophilus zeamais Motschulsky (Coleoptera Curculionidae) were studied during two storage seasons in maize stores, in Bénin. Maize ears, randomly sampled from far...

363

QTL mapping of resistance to gray leaf spot in maize.  

PubMed

Gray leaf spot (GLS), caused by the causal fungal pathogen Cercospora zeae-maydis, is one of the most serious foliar diseases of maize worldwide. In the current study, a highly resistant inbred line Y32 and a susceptible line Q11 were used to produce segregating populations for both genetic analysis and QTL mapping. The broad-sense heritability (H (2)) for GLS resistance was estimated to be as high as 0.85, indicating that genetic factors played key roles in phenotypic variation. In initial QTL analysis, four QTL, located on chromosomes 1, 2, 5, and 8, were detected to confer GLS resistance. Each QTL could explain 2.53-23.90 % of the total phenotypic variation, predominantly due to additive genetic effects. Two major QTL, qRgls1 and qRgls2 on chromosomes 8 and 5, were consistently detected across different locations and replicates. Compared to the previous results, qRgls2 is located in a 'hotspot' for GLS resistance; while, qRgls1 does not overlap with any other known resistance QTL. Furthermore, the major QTL-qRgls1 was fine-mapped into an interval of 1.4 Mb, flanked by the markers GZ204 and IDP5. The QTL-qRgls1 could enhance the resistance percentages by 19.70-61.28 %, suggesting its usefulness to improve maize resistance to GLS. PMID:22903692

Zhang, Yan; Xu, Ling; Fan, Xingming; Tan, Jing; Chen, Wei; Xu, Mingliang

2012-12-01

364

Maize stem borer colonization, establishment and crop damage levels in a maize-leucaena agroforestry system in Kenya  

Microsoft Academic Search

The effect of resource concentration on the population of stem-borers of maize in the maize-leucaena agroforestry system was evaluated. The studies covered six cropping seasons from October 1992 to August 1995, and were conducted at Mtwapa and Amoyo in coastal and western Kenya, respectively. Treatments included monocropped and intercropped (maize, leucaena) plots, weeded and unweeded plots, mulched and unmulched plots,

Callistus K. P. O. Ogol; John R. Spence; Andrew Keddie

1999-01-01

365

Household dietary exposure to aflatoxins from maize and maize products in Kenya.  

PubMed

Aflatoxicosis has repeatedly affected Kenyans, particularly in the eastern region, due to consumption of contaminated maize. However, save for the cases of acute toxicity, the levels of sub-lethal exposure have not been adequately assessed. It is believed that this type of exposure does exist even during the seasons when acute toxicity does not occur. This study, therefore, was designed to assess the exposure of households to aflatoxins through consumption of maize and maize products. Twenty samples each of maize kernels, muthokoi and maize meal were randomly sampled from households in Kibwezi District of Makueni County in Eastern Kenya and analysed for aflatoxin contamination. The samples were quantitatively analysed for aflatoxin contamination using HPLC. The uncertainty and variability in dietary exposure was quantitatively modelled in Ms Excel using Monte Carlo simulation in @Risk software. Aflatoxins were found in 45% of maize kernels at between 18 and 480 ?g kg(-1), 20% of muthokoi at between 12 and 123 ?g kg(-1), and 35% of maize meal at between 6 and 30 ?g kg(-1). The mean dietary exposure to aflatoxin in maize kernels was 292 ± 1567 ng kg(-1) body weight day(-1), while the mean dietary exposure to aflatoxin in maize meal and muthokoi were 59 ± 62 and 27 ± 154 ng kg(-1) body weight day(-1) respectively. The results showed that the amount and frequency of consumption of the three foods is the more important contributing factor than the mean aflatoxin concentration levels, to the risk of dietary exposure to aflatoxins. PMID:25325777

Kilonzo, Robert M; Imungi, Jasper K; Muiru, William M; Lamuka, Peter O; Njage, Patrick M Kamau

2014-12-01

366

Streaked Pumice From the Youngest Toba Tuff: New Constraints on Compositional and Temperature Gradients  

NASA Astrophysics Data System (ADS)

Earth's largest Quaternary volcanic eruption (75 ka) expelled more than 2800 km3 of compositionally zoned silicic magma from Toba caldera, Indonesia, and produced the extensive Youngest Toba Tuff (YTT). Past petrologic studies identified that the YTT magma was zoned with respect to composition, temperature, and mineralogy. To understand the dynamics of differentiation leading to eruption of the YTT magma, we analyzed the geochemistry and mineralogy of rare mixed dacitic and rhyolitic pumice that extend the range of YTT compositions to less-evolved and apparently hotter compositions. Mixed pumices are streaked with light and dark domains mostly containing ca. 20-50% crystals of plagioclase, hornblende, quartz, biotite, and pyroxenes. In general, crystal size in the dark domains is smaller than in higher SiO2 pumice. Dark domains range in composition from dacite to low-silica rhyolite (63-72 wt.% SiO2, anhydrous); light domains typically contain higher SiO2 (65-74 wt.% SiO2, anhydrous) than their darker counterparts. SiO2 concentrations of the pumice domains correlate with trace element concentrations, including positive covariation with typically incompatible elements (e.g., Nb, Ta, U, Th) and negative covariation with typically compatible elements (e.g., Sr, Eu, Sc). Domain glasses mimic these same trace element trends. Within both domain types, plagioclase composition varies from An30 to An50. Hornblende composition generally covaries with pumice SiO2. Pressures calculated using the Johnson and Rutherford (1989) barometer range from ca. 2 kb to 5 kb. However, pressures calculated using the Anderson and Smith (1995) barometer range from ca. 0 kb to 2 kb. Hornblende-plagioclase pairs yield temperatures ranging from ca. 800° to 900°C, while equilibrium Fe-Ti oxide pairs yield temperatures ranging from ca. 760° to 800°C. In general, dark pumice domains yield the highest temperatures. The Pb and Nd isotope compositions of domains within single streaked pumice samples are variable, including different isotope compositions for glasses from adjacent streaks. Isotopic heterogeneity suggests mixing of melts that experienced different degrees of open-system evolution. The mixed pumice samples provide a new limit on the mafic end-member of YTT magma composition, and record mixing of magma with contrasting origins. Mixed pumice containing cm-scale compositional heterogeneity suggests mixing of contrasting magmas just prior to, or during, evacuation of the voluminous YTT reservoir, perhaps in response to heating after intrusion of new magma. Differences in hornblende composition between dacitic and rhyolitic pumice may reflect contrasting depths of crystallization for dacitic and rhyolitic end- members, or temperature-induced control of amphibole composition within a shallow reservoir beneath Toba.

Ferreira, M.; Vazquez, J.

2007-12-01

367

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

NASA Astrophysics Data System (ADS)

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

Walker, David R.

368

GPU-accelerated Faint Streak Detection for Uncued Surveillance of LEO  

NASA Astrophysics Data System (ADS)

By astronomical standards, small objects (<10cm) in LEO illuminated by the Sun under terminator conditions are quite bright, depositing 100's to 1000's of photons per second into small telescope apertures (< 1m diameter). The challenge in discovering these objects with no a priori knowledge of their orbit (i.e. uncued surveillance) is that their relative motion with respect to a ground-based telescope makes them appear to have large angular rates of motion, up to and exceeding 1 degree per second. Thus in even a short exposure, the signal from the object is smeared out in a streak with low signal-to-noise per pixel. Go Green Termite (GGT), Inc. of Gilroy, CA, in collaboration with the University of New Mexico (UNM), is building two proof-of-concept wide-field imaging systems to test, develop and prove a novel streak detection technique. The imaging systems are built from off-the-shelf optics and detectors resulting in a 350mm aperture and a 6 square degree field of view. For streak detection, field of view is of critical importance because the maximum exposure time on the object is limited by its crossing time. In this way, wider fields of view impact surveys for LEO objects both by increasing the survey volume and increasing sensitivity. Using our newly GPU-accelerated detection scheme, the proof-of-concept systems are expected to be able to detect objects fainter than 12th magnitude moving at 1 degree per second and possibly as faint as 13th magnitude for slower moving objects. Meter-class optical systems using these techniques should be able to detect objects fainter than 14th magnitude, which is roughly equivalent to a golf ball at 1000km altitude. The goal of this work is to demonstrate a scalable system for near real time detection of fast moving objects that can be then handed off to other instruments capable of tracking and characterizing them. The two proof-of-concept systems, separated by ~30km, work together by taking simultaneous images of the same volume to constrain the orbits of detected objects using parallax measurements. These detections will then be followed-up by photometric observations taken at UNM to independently assess the objects and the quality of the derived orbits. We believe this will demonstrate the potential of small telescope arrays for detecting and cataloguing heretofore unknown LEO objects.

Zimmer, P.; Ackermann, M.; McGraw, J. T.

2013-09-01

369

Effects of wheat streak mosaic virus on root development and water-use efficiency of hard red winter wheat  

Technology Transfer Automated Retrieval System (TEKTRAN)

Greenhouse and field studies were conducted to determine the effects of Wheat streak mosaic virus (WSMV), a member of the family Potyviridae, on root development and water-use efficiency (WUE) of two hard red winter wheat (Triticum aestivum) cultivars, one susceptible and one resistant to WSMV. In t...

370

The effect of boundary conditions and shear rate on streak formation and breakdown in turbulent channel flows  

Microsoft Academic Search

Experiments in a horizontal channel indicate that low-speed\\/high-speed streaks form in the region very close to the interface if shear is imposed on the liquid surface by the motion of a gas. They also form at the wall. Even though the boundary conditions at the wall and at the interface are different (no slip versus nearly free slip with regard

M. Rashidi; S. Banerjee

1990-01-01

371

A jet streak circulation associated with a low-latitude jet in the Southern Hemisphere over Africa.  

E-print Network

A jet streak circulation associated with a low-latitude jet in the Southern Hemisphere over Africa 2007 #12;2 Abstract In the Southern Hemisphere over Africa a mid-tropospheric easterly jet stream exists during some months that is analogous to the African Easterly Jet over West Africa. In this note

Nicholson, Sharon E.

372

Winter wheat cultivars with temperature sensitive resistance to wheat streak mosaic virus do not recover from early season infections  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat streak mosaic virus (WSMV), Triticum mosaic virus, and Wheat mosaic virus, all vectored by the wheat curl mite Aceria tosichella Keifer, frequently cause devastating losses to winter wheat production throughout the central and western Great Plains. Resistant 'Mace' and 'RonL' are commercially ...

373

When people say they see a shooting star after noticing a momentary streak of light in the night sky, what  

E-print Network

When people say they see a shooting star after noticing a momentary streak of light in the night sky, what they really see are meteors burning up as they enter the Earth's atmosphere--nothing to do can't even see Mira very well in the image because it is tiny compared to the tail. Mira is 350 light

374

Modified ecometric technique (four-quadrant sequential streak) to evaluate Campylobacter enrichment broth proficiency in suppressing background microflora  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ecometric technique is a semi-quantitative scoring method used for quality control of culture media in microbiological laboratories. The technique involves inoculation with defined populations of specific culture onto solid media via a standardized chronological streaking technique, leading to ever-...

375

Compositions of Low Albedo Intracrater Materials and Wind Streaks on Mars: Examination of MGS TES Data in Western Arabia Terra  

NASA Technical Reports Server (NTRS)

Basalt and andesite surface compositions are identified within individual low albedo intracrater features and adjacent dark wind streaks. High resolution mapping of compositional heterogeneities may help constrain origin hypotheses for these features. Additional information is contained in the original extended abstract.

Bandfield, J. L.; Wyatt, M. B.; Christensen, P.; McSween, H. Y., Jr.

2001-01-01

376

Quantification of yield loss caused by Triticum mosaic virus and Wheat streak mosaic virus in winter wheat under field conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Triticum mosaic virus (TriMV) and Wheat streak mosaic virus (WSMV) infect winter wheat in the Great Plains region of the United States. The two viruses are transmitted by wheat curl mites, which also transmit High Plains virus. In a field study conducted in 2011 and 2012, winter wheat cultivars Mi...

377

Two Dimensions Are Not Better than One: STREAK and the Univariate Signal Detection Model of Remember/Know Performance  

ERIC Educational Resources Information Center

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…

Starns, Jeffrey J.; Ratcliff, Roger

2008-01-01

378

Excitation Energy Transfer in Dimeric Light Harvesting Complex I: A Combined Streak-Camera/Fluorescence Upconversion Study  

E-print Network

Excitation Energy Transfer in Dimeric Light Harvesting Complex I: A Combined Streak harvesting complex I, the peripheral light harvesting complex associated with photosystem I in green plants, was studied by time-resolved fluorescence spectroscopy. A unique combination of two techniques, fluorescence

van Stokkum, Ivo

379

Segregation of transgenes in maize.  

PubMed

Progeny recovered from backcrossed transgenic maize tissue culture regenerants (R0) were analyzed to determine the segregation, expression, and stability of the introduced genes. Transgenic A188 x B73 R0 plants (regenerated from embryogenic suspension culture cells transformed by microprojectile bombardment; see [9]) were pollinated with nontransformed B73 pollen. Inheritance of a selectable marker gene, bar, and a nonselectable marker gene, uidA, was analyzed in progeny (R1) representing four independent transformation events. Activity of the bar gene product, phosphinothricin acetyltransferase (PAT), was assessed in plants comprising the four R1 populations. The number of R1 plants containing PAT activity per total number of R1 plants recovered for each population was 2/7, 19/34, 3/14 and 73/73. Molecular analysis confirmed the segregation of bar in three R1 populations and the lack of segregation in one R1 population. Cosegregation analysis indicated genetic linkage of bar and uidA in all four R1 populations. Analysis of numerous R2 plants derived from crossing transformed R1 plants with nontransformed inbreds revealed 1:1 segregation of PAT activity in three of four lines, including the line that failed to segregate in the R1 generation. Integrated copies of bar in one line appeared to be unstable or poorly transmitted. PMID:1731983

Spencer, T M; O'Brien, J V; Start, W G; Adams, T R; Gordon-Kamm, W J; Lemaux, P G

1992-01-01

380

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

381

Evaluation of five ab initio gene prediction programs for the discovery of maize genes  

E-print Network

Evaluation of five ab initio gene prediction programs for the discovery of maize genes Hong Yao1 Key words: ab initio gene prediction, a1-sh2 interval, maize, maize assembled genomic islands, maizeR and Grail) were evaluated for their accuracy in predicting maize genes. Two of these programs, Gene

Schnable, Patrick S.

382

Silicon Improves Maize Photosynthesis in Saline-Alkaline Soils  

PubMed Central

The research aimed to determine the effects of Si application on photosynthetic characteristics of maize on saline-alkaline soil, including photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (E), and intercellular CO2 concentration (Ci) of maize in the field with five levels (0, 45, 90, 150, and 225?kg·ha?1) of Si supplying. Experimental results showed that the values of Pn, gs, and Ci of maize were significantly enhanced while the values of E of maize were dramatically decreased by certain doses of silicon fertilizers, which meant that Si application with proper doses significantly increased photosynthetic efficiency of maize in different growth stages under stressing environment of saline-alkaline soil. The optimal dose of Si application in this experiment was 150?kg·ha?1?Si. It indicated that increase in maize photosynthesis under saline-alkaline stress took place by Si application with proper doses, which is helpful to improve growth and yield of maize.

Xie, Zhiming; Song, Ri; Shao, Hongbo; Song, Fengbin; Xu, Hongwen; Lu, Yan

2015-01-01

383

Blue maize: morphology and starch synthase characterization of starch granule.  

PubMed

The use of pigmented maize varieties has increased due to their high anthocyanins content, but very few studies are reported about the starch properties of these grains. The aim of this work was to isolate the starch granules from pigmented blue maize and carry out the morphological, physicochemical, and biochemical characterization studies. The proximate composition of starch granules showed high protein contents, after purification, the blue maize starch presented lower protein amount than starch from white maize (control). Although the purity of starch granules was increased, the damaged starch (determined for the Maltase cross absence) was also increased. Scanning electron microscopy showed the presence of some pores and channels in the blue maize starch. The electrophoretic protein profiles showed differences in the bands that correspond to the enzymes involved in the starch biosynthesis; these differences could explain the variation in morphological characteristics of blue maize starches against starch from white maize. PMID:19153833

Utrilla-Coello, Rubi G; Agama-Acevedo, Edith; de la Rosa, Ana Paulina Barba; Martinez-Salgado, Jose L; Rodriguez-Ambriz, Sandra L; Bello-Perez, Luis A

2009-03-01

384

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; Kivimäe, Saul; Fisher, Daniel A.; Moon, Randall T.; Cheyette, Benjamin N.R.

2009-01-01

385

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

386

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

PubMed

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

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

2013-01-01

387

Development of Time Resolved Streak Camera for the Observation of Lightning Discharge  

NASA Astrophysics Data System (ADS)

A new type of high-speed streak camera was developed to observe the process of lightning discharge. The camera consists of a rotating quadrate pyramid mirror and a digital video camera. Using the camera we can observe the lightning discharge in all horizontal direction and continuous observation is available without using high-speed shutter synchronizing with lightning discharge. The visual range, the time resolution and the dead time of the camera were evaluated theoretically and experimentally. From the evaluation we found that the time resolution of less than ten ?s is expected at maximum rotating speed of the mirror of 200s-1. The percentage of dead time was evaluated to be less than 50%. By using the camera, we have successfully observed the lightning discharges and from the observation we have evaluated the shape, and the duration of each lightning discharge.

Bounsou, Xayphone; Kitamura, Iwao; Masugata, Katsumi; Kontani, Ken

388

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

389

A quill vibrating mechanism for a sounding apparatus in the streaked tenrec (Hemicentetes semispinosus).  

PubMed

The streaked tenrec (Hemicentetes semispinosus) is equipped with a quill vibrating mechanism on the dorsal side of the caudal trunk that has evolved as an extraordinary sounding apparatus for communication. An arrangement of 15 or 16 light-brown quills was observed. Thickened cutaneous muscles were confirmed beneath quills. We named this structure the "quill vibrator disc" (QVD). The QVD was 16.8 mm long and 8.55 mm wide in a typical adult. Longitudinal musculature symmetrical about the sagittal plane was developed in the QVD. Myocytes were found immunohistochemically to contain mainly fast myosin but not slow myosin. These findings indicate that the QVD is a specialized apparatus in the cutaneous muscle that contributes to the vibration of quills and to the production of sound for communication. PMID:20443690

Endo, Hideki; Koyabu, Daisuke; Kimura, Junpei; Rakotondraparany, Felix; Matsui, Atsushi; Yonezawa, Takahiro; Shinohara, Akio; Hasegawa, Masami

2010-05-01

390

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

391

Rapid decomposition of maize detritus in agricultural headwater streams.  

PubMed

Headwater streams draining agricultural landscapes receive maize leaves (Zea mays L.) via wind and surface runoff, yet the contribution of maize detritus to organic-matter processing in agricultural streams is largely unknown. We quantified decomposition and microbial respiration rates on conventional (non-Bt) and genetically engineered (Bt) maize in three low-order agricultural streams in northwestern Indiana, USA. We also examined how substrate quality and in-stream nutrient concentrations influenced microbial respiration on maize by comparing respiration on maize and red maple leaves (Acer rubrum) in three nutrient-rich agricultural streams and three low-nutrient forested streams. We found significantly higher rates of microbial respiration on maize vs. red maple leaves and higher rates in agricultural vs. forested streams. Thus both the elevated nutrient status of agricultural streams and the lability of maize detritus (e.g., low carbon-to-nitrogen ratio and low lignin content) result in a rapid incorporation of maize leaves into the aquatic microbial food web. We found that Bt maize had a faster decomposition rate than non-Bt maize, while microbial respiration rates did not differ between Bt and non-Bt maize. Decomposition rates were not negatively affected by genetic engineering, perhaps because the Bt toxin does not adversely affect the aquatic microbial assemblage involved in maize decomposition. Additionally, shredding caddisflies, which are known to have suppressed growth rates when fed Bt maize, were depauperate in these agricultural streams, and likely did not play a major role in maize decomposition. Overall, the conversion of native vegetation to row-crop agriculture appears to have altered the quantity, quality, and predictability of allochthonous carbon inputs to headwater streams, with unexplored effects on stream ecosystem structure and function. PMID:19323178

Griffiths, Natalie A; Tank, Jennifer L; Royer, Todd V; Rosi-Marshall, Emma J; Whiles, Matt R; Chambers, Catherine P; Frauendorf, Therese C; Evans-White, Michelle A

2009-01-01

392

Maize pollen is an important allergen in occupationally exposed workers  

PubMed Central

Background The work- or environmental-related type I sensitization to maize pollen is hardly investigated. We sought to determine the prevalence of sensitization to maize pollen among exposed workers and to identify the eliciting allergens. Methods In July 2010, 8 out of 11 subjects were examined who were repeatedly exposed to maize pollen by pollinating maize during their work in a biological research department. All 8 filled in a questionnaire and underwent skin prick testing (SPT) and immune-specific analyses. Results 5 out of the 8 exposed subjects had repeatedly suffered for at least several weeks from rhinitis, 4 from conjunctivitis, 4 from urticaria, and 2 from shortness of breath upon occupational exposure to maize pollen. All symptomatic workers had specific IgE antibodies against maize pollen (CAP class ? 1). Interestingly, 4 of the 5 maize pollen-allergic subjects, but none of the 3 asymptomatic exposed workers had IgE antibodies specific for grass pollen. All but one of the maize pollen-allergic subjects had suffered from allergic grass pollen-related symptoms for 6 to 11 years before job-related exposure to maize pollen. Lung function testing was normal in all cases. In immunoblot analyses, the allergenic components could be identified as Zea m 1 and Zea m 13. The reactivity is mostly caused by cross-reactivity to the homologous allergens in temperate grass pollen. Two sera responded to Zea m 3, but interestingly not to the corresponding timothy allergen indicating maize-specific IgE reactivity. Conclusion The present data suggest that subjects pollinating maize are at high risk of developing an allergy to maize pollen as a so far underestimated source of occupational allergens. For the screening of patients with suspected maize pollen sensitization, the determination of IgE antibodies specific for maize pollen is suitable. PMID:22165847

2011-01-01

393

Identification and characterization of maize pathogenesis-related proteins. Four maize PR proteins are chitinases  

Microsoft Academic Search

Eight pathogenesis-related proteins extractable at pH 2.8 were found to accumulate in maize leaves after mercuric chloride treatment or brome mosaic virus infection. These proteins were called PRm (pathogenesis-related maize) proteins. Seven PRm proteins were purified to homogeneity by preparative polyacrylamide gel electrophoresis and their amino acid compositions determined. Estimated molecular weights in SDS-containing gels were: PRm 1 14.2 kDa;

William Nasser; Marc de Tapia; Serge Kauffmann; Shideh Montasser-Kouhsari; Gérard Burkard

1988-01-01

394

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

PubMed

cis-Jasmone (CJ) is a natural plant product that activates defence against herbivores in model and crop plants. In this study, we investigated whether CJ could prime defence in maize, Zea mays, against the leafhopper, Cicadulina storeyi, responsible for the transmission of maize streak virus (MSV). Priming occurs when a pre-treatment, in this case CJ, increases the potency and speed of a defence response upon subsequent attack on the plant. Here, we tested insect responses to plant volatile organic compounds (VOCs) using a Y-tube olfactometer bioassay. Our initial experiments showed that, in this system, there was no significant response of the herbivore to CJ itself and no difference in response to VOCs collected from unexposed plants compared to CJ exposed plants, both without insects. VOCs were then collected from C. storeyi-infested maize seedlings with and without CJ pre-treatment. The bioassay revealed a significant preference by this pest for VOCs from infested seedlings without the CJ pre-treatment. A timed series of VOC collections and bioassays showed that the effect was strongest in the first 22 h of insect infestation, i.e. before the insects had themselves induced a change in VOC emission. Chemical analysis showed that treatment of maize seedlings with CJ, followed by exposure to C. storeyi, led to a significant increase in emission of the defensive sesquiterpenes (E)-(1R,9S)-caryophyllene, (E)-?-bergamotene, (E)-?-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene, known to act as herbivore repellents. The chemical analysis explains the behavioural effects observed in the olfactometer, as the CJ treatment caused plants to emit a blend of VOCs comprising more of the repellent components in the first 22 h of insect infestation than control plants. The speed and potency of VOC emission was increased by the CJ pre-treatment. This is the first indication that CJ can prime plants for enhanced production of defensive VOCs antagonist towards herbivores. PMID:23840295

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

2013-01-01

395

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

PubMed Central

cis-Jasmone (CJ) is a natural plant product that activates defence against herbivores in model and crop plants. In this study, we investigated whether CJ could prime defence in maize, Zea mays, against the leafhopper, Cicadulina storeyi, responsible for the transmission of maize streak virus (MSV). Priming occurs when a pre-treatment, in this case CJ, increases the potency and speed of a defence response upon subsequent attack on the plant. Here, we tested insect responses to plant volatile organic compounds (VOCs) using a Y-tube olfactometer bioassay. Our initial experiments showed that, in this system, there was no significant response of the herbivore to CJ itself and no difference in response to VOCs collected from unexposed plants compared to CJ exposed plants, both without insects. VOCs were then collected from C. storeyi-infested maize seedlings with and without CJ pre-treatment. The bioassay revealed a significant preference by this pest for VOCs from infested seedlings without the CJ pre-treatment. A timed series of VOC collections and bioassays showed that the effect was strongest in the first 22 h of insect infestation, i.e. before the insects had themselves induced a change in VOC emission. Chemical analysis showed that treatment of maize seedlings with CJ, followed by exposure to C. storeyi, led to a significant increase in emission of the defensive sesquiterpenes (E)-(1R,9S)-caryophyllene, (E)-?-bergamotene, (E)-?-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene, known to act as herbivore repellents. The chemical analysis explains the behavioural effects observed in the olfactometer, as the CJ treatment caused plants to emit a blend of VOCs comprising more of the repellent components in the first 22 h of insect infestation than control plants. The speed and potency of VOC emission was increased by the CJ pre-treatment. This is the first indication that CJ can prime plants for enhanced production of defensive VOCs antagonist towards herbivores. PMID:23840295

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

2013-01-01

396

Mutator transposon activity reprograms the transcriptomes and proteomes of developing maize anthers  

E-print Network

Mutator transposon activity reprograms the transcriptomes and proteomes of developing maize anthers conservation of anther gene expression patterns across maize lines, Mu transposition programmed: transposon, Mutator, anther, maize, stress, microarray. INTRODUCTION DNA transposable elements (TEs

Kay, Mark A.

397

19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Certified seed potatoes, and seed corn or maize. 10.57 ...REDUCED RATE, ETC. General Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim...

2010-04-01

398

The genetic architecture of maize stalk strength  

Technology Transfer Automated Retrieval System (TEKTRAN)

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 4,892 rec...

399

Use of tropical maize for bioethanol production.  

PubMed

Tropical maize is an alternative energy crop being considered as a feedstock for bioethanol production in the North Central and Midwest United States. Tropical maize is advantageous because it produces large amounts of soluble sugars in its stalks, creates a large amount of biomass, and requires lower inputs (e.g. nitrogen) than grain corn. Soluble sugars, including sucrose, glucose and fructose were extracted by pressing the stalks at dough stage (R4). The initial extracted syrup fermented faster than the control culture grown on a yeast extract/phosphate/sucrose medium. The syrup was subsequently concentrated 1.25-2.25 times, supplemented with urea, and fermented using Saccharomyces cerevisiae for up to 96 h. The final ethanol concentrations obtained were 8.1 % (v/v) to 15.6 % (v/v), equivalent to 90.3-92.2 % of the theoretical yields. However, fermentation productivity decreased with sugar concentration, suggesting that the yeast might be osmotically stressed at the increased sugar concentrations. These results provide in-depth information for utilizing tropical maize syrup for bioethanol production that will help in tropical maize breeding and development for use as another feedstock for the biofuel industry. PMID:23508398

Chen, Ming-Hsu; Kaur, Prabhjot; Dien, Bruce; Below, Frederick; Vincent, Michael L; Singh, Vijay

2013-08-01

400

Regulatory modules controlling maize inflorescence architecture  

Technology Transfer Automated Retrieval System (TEKTRAN)

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...

401

DEVELOPMENTS OF STARCH GRANULES IN MAIZE KERNELS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize kernels of self-pollinated inbred line B73, grown in Ames IA, were harvested on 0, 5, 6, 8, 10 12, 14, 20 and 30 days after pollination (DAP). The kernels were used for starch granule development studies. Starch in the endosperm was first observed on 6 DAP. Starch granules in the kernels th...

402

MOLECULAR POPULATION GENETICS OF MAIZE DOMESTICATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

The domestication of maize resulted in a dramatic change in its plant architecture and inflorescence development as compared to its wild ancestor, teosinte, with the most remarkable difference being in their female inflorescence (ear) structure. Only a few genes have been uncovered to be associated ...

403

Maize Genetics Outreach to American Indians  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize is an excellent vehicle for plant genomics outreach to those American Indian tribes who use and appreciate it nutritionally, culturally, and spiritually. During the summer 2006 season we mentored six Native American Indian students for eight weeks. All six worked at the USDA-ARS North Centra...

404

Digital gene expression signatures for maize development  

Technology Transfer Automated Retrieval System (TEKTRAN)

Genome-wide expression signatures detect specific perturbations in developmental programs and contribute to functional resolution of key regulatory networks. In maize (Zea mays) inflorescences, mutations in the RAMOSA (RA) genes affect determinacy of axillary meristems and thus alter branching patt...

405

GENETIC VARIABILITY IN MAIZE CHLOROTIC DWARF VIRUS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize chlorotic dwarf virus (MCDV) (genus Waikavirus; family Sequiviridae) is a picorna-like virus transmitted by the black-faced leafhopper, Graminella nigrifrons, in a semi-persistent manner using a virus-encoded helper protein. The MCDV genome contains one large open reading frame encoding a poly...

406

Use and impact of Bt maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

This is an invited article for a free science library and personal training tool sponsored by Nature Publishing Group, which will be included under the topics Agriculture and Biotechnology (http://www.nature.com/scitable). The focus of this article is on Bacillus thuringiensis (Bt) maize. Growers of...

407

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

408

Genetic diversity and molecular evolution of Chinese waxy maize germplasm.  

PubMed

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

409

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

410

The 50th Annual Maize Genetics Conference  

SciTech Connect

The 50th Annual Maize Genetics Conference was held February 27 - March 2, 2008 at the Marriott Wardman Park Hotel in Washington, D.C. As the golden anniversary of the Conference and coinciding with the release of a draft of the maize genome sequence, this was a special meeting. To publicize this unique occasion, meeting organizers hosted a press conference, which was attended by members of the press representing science and non-science publications, and an evening reception at the Smithsonian National Museum of Natural History, where the draft sequence was announced and awards were presented to Dr. Mary Clutter and Senator Kit Bond to thank them for their outstanding contributions to maize genetics and genomics research. As usual, the Conference provided an invigorating forum for exchange of recent research results in many areas of maize genetics, e.g., cytogenetics, development, molecular genetics, transposable element biology, biochemical genetics, and genomics. Results were shared via both oral and poster presentations. Invited talks were given by four distinguished geneticists: Vicki Chandler, University of Arizona; John Doebley, University of Wisconsin; Susan Wessler, University of Georgia; and Richard Wilson, Washington University. There were 46 short talks and 241 poster presentations. The Conference was attended by over 500 participants. This included a large number of first-time participants in the meeting and an increasingly visible presence by individuals from underrepresented groups. Although we do not have concrete counts, there seem to be more African American, African and Hispanic/Latino attendees coming to the meeting than in years past. In addition, this meeting attracted many participants from outside the U.S. Student participation continues to be hallmark of the spirit of free exchange and cooperation characteristic of the maize genetics community. With the generous support provided by DOE, USDA NSF, and corporate/private donors, organizers were able to defray lodging and meal costs for 133 graduate and undergraduate students and 66 postdocs

Cone, Karen

2014-03-26

411

Flaked maize digestion in the gvowing pig In growing pigs, flaking of maize significantly improves (P < 0,01) organic matter and espe-.  

E-print Network

II. - Flaked maize digestion in the gvowing pig In growing pigs, flaking of maize significantly maize (87 or 81 p. ioo) and fish meal (6 or 12 p. roo), but it has only an effect on nitrogen retention hours after a test meal the following was noticed after flaked maize feeding : - a higher water content

Paris-Sud XI, Université de

412

CIMMYT 1997\\/98 WORLD MAIZE FACTS AND TRENDS; MAIZE PRODUCTION IN DROUGHT-STRESSED ENVIRONMENTS: TECHNICAL OPTIONS AND RESEARCH RESOURCE ALLOCATION  

Microsoft Academic Search

This publication, through its focus on maize production in drought stressed areas of developing countries, explores economic, research, and policy issues related to maize agriculture in marginal areas of the developing world generally. Key questions in the debate over agriculture in marginal vs. favorable production areas are reviewed with a focus on maize. Questions include whether maize production is expanding

Paul W. Heisey; Gregory O. Edmeades

1999-01-01

413

Genetic Characterization of a Core Set of a Tropical Maize Race Tuxpeño 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

414

Comparative phenology of Lepidoptera on genetically modified BT- and non-BT maize / A. van Wyk.  

E-print Network

??The maize stem borers, Busseola fusca (Fuller) (Lepidoptera: Noctuidae) and Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) are economically important pests of maize in South Africa. Genetically… (more)

Van Wyk, Annemie

2006-01-01

415

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

416

Processing maize flour and corn meal food products  

PubMed Central

Corn is the cereal with the highest production worldwide and is used for human consumption, livestock feed, and fuel. Various food technologies are currently used for processing industrially produced maize flours and corn meals in different parts of the world to obtain precooked refined maize flour, dehydrated nixtamalized flour, fermented maize flours, and other maize products. These products have different intrinsic vitamin and mineral contents, and their processing follows different pathways from raw grain to the consumer final product, which entail changes in nutrient composition. Dry maize mechanical processing creates whole or fractionated products, separated by anatomical features such as bran, germ, and endosperm. Wet maize processing separates by chemical compound classification such as starch and protein. Various industrial processes, including whole grain, dry milling fractionation, and nixtamalization, are described. Vitamin and mineral losses during processing are identified and the nutritional impacts outlined. Also discussed are the vitamin and mineral contents of corn. PMID:24329576

Gwirtz, Jeffrey A; Garcia-Casal, Maria Nieves

2014-01-01

417

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

418

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

419

FGF signalling through RAS\\/MAPK and PI3K pathways regulates cell movement and gene expression in the chicken primitive streak without affecting E-cadherin expression  

Microsoft Academic Search

Background  FGF signalling regulates numerous aspects of early embryo development. During gastrulation in amniotes, epiblast cells undergo\\u000a an epithelial to mesenchymal transition (EMT) in the primitive streak to form the mesoderm and endoderm. In mice lacking FGFR1,\\u000a epiblast cells in the primitive streak fail to downregulate E-cadherin and undergo EMT, and cell migration is inhibited. This\\u000a study investigated how FGF signalling

Katharine M Hardy; Tatiana A Yatskievych; JH Konieczka; Alexander S Bobbs; Parker B Antin

2011-01-01

420

Streaked x-ray backlighting with twin-slit imager for study of density profile and trajectory of low-density foam target filled with deuterium liquid  

Microsoft Academic Search

Low-density plastic foam filled with liquid deuterium is one of the candidates for inertial fusion target. Density profile and trajectory of 527 nm laser-irradiated planer foam-deuterium target in the acceleration phase were observed with streaked side-on x-ray backlighting. An x-ray imager employing twin slits coupled to an x-ray streak camera was used to simultaneously observe three images of the target:

H. Shiraga; N. Mahigashi; T. Yamada; S. Fujioka; T. Sakaiya; K. Shigemori; M. Nakai; H. Azechi; A. Sunahara

2008-01-01

421

Application of laser Mueller-polarimetry to the investigation of healthy and infected by the wheat streak mosaic virus apogee variety wheat grown under simulated microgravity conditions  

NASA Astrophysics Data System (ADS)

Apogee variety wheat plants inoculated by wheat streak mosaic virus isolated by us displaced the reduction under simulated microgravity conditions. We employed the laser Mueller-polarimetry method for the first time to study simulated microgravity effects on healthy and infected by the wheat streak mosaic virus wheat plants. Our results are indicative of the possibility to apply the laser Mueller-polarimetry procedure to the investigation of structural and functional changes in wheat leaves caused by virus infection and clinorotation.

Mishchenko, L. T.; Savenkov, S. M.; Oberemok, Ye. A.

422

The complete genome sequence of the Tanzanian strain of Cassava brown streak virus and comparison with the Ugandan strain sequence  

Microsoft Academic Search

The complete genome sequence for an isolate of the Ugandan and Tanzanian strain \\u000a types of Cassava brown streak virus have been determined using the novel approach \\u000a of non-directed next generation sequencing. Comparison of the genome sequences revealed that CBSV is highly heterogeneous\\u000a at the isolate level as well as the strain level. The isolate of the Ugandan strain was found

Wendy A. MongerT; T. Alicai; J. Ndunguru; Z. M. Kinyua; M. Potts; R. H. Reeder; D. W. Miano; I. P. Adams; N. Boonham; R. H. Glover; J. Smith

2010-01-01

423

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

424

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

425

Natural occurrence of aflatoxins from maize in Iran.  

PubMed

Fifty-one maize samples, intended for animal feed and human consumption, were collected from the four main maize production provinces in Iran and analyzed by high-performance liquid chromatography (HPLC) for contamination by four naturally occurring aflatoxin analogues (AFB1, AFB2, AFG1, and AFG2). AFB1 was detected in 58.3, and 80% of the maize samples obtained from Kermanshah and Mazandaran provinces, respectively. The maximum AFB1 (276.3 ?g/kg) and highest level of total aflatoxins (AFT) (316.9 ?g/kg) were detected in a maize sample collected from Kermanshah province. The mean aflatoxin level from contaminated samples (52.60 ?g/kg) from Kermanshah was significantly higher (P < 0.0001) than those in maize from the other three provinces and exceeded all the maximum tolerated levels (MTLs) set for AFT in maize. The level of AFB1 in 15.68% of the total samples was above the MTL (5 ?g/kg) for AFB1 in maize in Iran. The mean contamination level of AFT (23.86 ?g/kg) in the positive samples was higher than MTL for maize in Iran (20 ?g/kg) intended for animal feed. The levels of AFB1, AFB2, AFG1, and AFG2 ranged between not detected (<0.1 ?g/kg) and 276.3, 30.4, 9.1, and 1.1 ?g/kg in maize grain, respectively. PMID:21373903

Ghiasian, S A; Shephard, G S; Yazdanpanah, H

2011-08-01

426

Comparative diversity of arthropods on Bt maize and non-Bt maize in two different cropping systems in South Africa.  

PubMed

The biodiversity of an agroecosystem is not only important for its intrinsic value but also because it influences ecological functions that are vital for crop production in sustainable agricultural systems and the surrounding environment. A concern about genetically modified (GM) crops is the potential negative impact that such crops could have on diversity and abundance of nontarget organisms, and subsequently on ecosystem functions. Therefore, it is essential to assess the potential environmental risk of the release of a GM crop and to study its effect on species assemblages within that ecosystem. Assessment of the impact of Bt maize on the environment is hampered by the lack of basic checklists of species present in maize agroecosystems. The aims of the study were to compile a checklist of arthropods that occur on maize in South Africa and to compare the diversity and abundance of arthropods and functional groups on Bt maize and non-Bt maize. Collections of arthropods were carried out during two growing seasons on Bt maize and non-Bt maize plants at two localities. Three maize fields were sampled per locality during each season. Twenty plants, each of Bt maize and non-Bt maize, were randomly selected from the fields at each site. The arthropods collected during this study were classified to morphospecies level and grouped into the following functional groups: detritivores, herbivores, predators, and parasitoids. Based on feeding strategy, herbivores and predators were further divided into sucking herbivores or predators (piercing-sucking mouthparts) and chewing herbivores or predators (chewing mouthparts). A total of 8,771 arthropod individuals, comprising 288 morphospecies and presenting 20 orders, were collected. Results from this short-term study indicated that abundance and diversity of arthropods in maize and the different functional guilds were not significantly affected by Bt maize, either in terms of diversity or abundance. PMID:24472209

Truter, J; Van Hamburg, H; Van Den Berg, J

2014-02-01

427

Relationship of wheat streak mosaic and barley stripe mosaic viruses to vector and nonvector eriophyid mites.  

PubMed

Large amounts of wheat streak mosaic virus (WSMV) accumulate in the midgut of its mite vector Eriophyes tulipae reared on virus infected plants. Masses of flexuous rod shaped virus particles persisted in the midgut, without degradation, for at least 5 of the 6--9 day adult life of mites. WSMV particles also were found distributed in the body cavity and in salivary glands of mites suggesting that the virus is "circulative" in E. tulipae. Abacarus hystrix, a nonvector of WSMV, when reared on virus infected plants, occasionally contained a small number of virus particles in its gut only. Extracts of such mites were not infective. Barley stripe mosaic (BSMV)--a rod-shaped virus, was not transmitted by E. tulipae, although a large concentration of virus particles was found in the midgut of mites reared on virus infected plants. Extracts of such mites were infective and the virus particles were retained for several days in the gut of such mites held on virus-free plants. BSMV particles were also found in the body cavity of mites. Possible reasons for E. tulipae being a nonvector of BSMV are discussed. PMID:7356391

Paliwal, Y C

1980-01-01

428

Fully biologically active in vitro transcripts of the eriophyid mite-transmitted wheat streak mosaic tritimovirus.  

PubMed

ABSTRACT Infectious RNA of wheat streak mosaic virus (WSMV) has been produced using a full-length cDNA clone as a template for in vitro transcription with SP6 RNA polymerase. Infectivity was dependent on the use of template plasmid DNA that had not undergone spontaneous rearrangement during amplification in Escherichia coli. The presence of WSMV in systemically infected wheat plants inoculated with in vitro transcripts was confirmed by reverse-transcription polymerase chain reaction of the WSMV P3 gene and by accumulation of WSMV coat protein as detected by immunoblotting. Maintenance of the full-length WSMV cDNA in the high copy number plasmid pUC18 was problematic because of spontaneous rearrangement of WSMV sequences during growth in liquid media for more than 8 h or if the clone was subcultured. Stability of the WSMV cDNA clone was improved by the use of the low copy number plasmid pACYC177, and it could be grown in large scale volumes (up to 1 liter) of liquid culture for 14 h without noticeable rearrangements. Both the original WSMV culture and the progeny virus derived from infectious in vitro transcripts were efficiently transmitted by the natural eriophyid mite vector Aceria tosichella. This is the first report of infectious in vitro transcripts for any eriophyid mite-transmitted plant virus and represents the only monopartite member of the family Potyviridae infecting monocotyledonous hosts for which infectious in vitro transcripts are available. PMID:18944643

Choi, I R; French, R; Hein, G L; Stenger, D C

1999-12-01

429

Improved detection of episomal Banana streak viruses by multiplex immunocapture PCR.  

PubMed

Banana streak viruses (BSV) are currently the main viral constraint to Musa germplasm movement, genetic improvement and mass propagation. Therefore, it is necessary to develop and implement BSV detection strategies that are both reliable and sensitive, such as PCR-based techniques. Unfortunately, BSV endogenous pararetrovirus sequences (BSV EPRVs) are present in the genome of Musa balbisiana. They interfere with PCR-based detection of episomal BSV in infected banana and plantain, such as immunocapture PCR. Therefore, a multiplex, immunocapture PCR (M-IC-PCR) was developed for the detection of BSV. Musa sequence tagged microsatellite site (STMS) primers were selected and used in combination with BSV species-specific primers in order to monitor possible contamination by Musa genomic DNA, using multiplex PCR. Furthermore, immunocapture conditions were optimized in order to prevent Musa DNA from interfering with episomal BSV DNA during the PCR step. This improved detection method successfully allowed the accurate, specific and sensitive detection of episomal DNA only from distinct BSV species. Its implementation should benefit PCR-based detection of viruses for which homologous sequences are present in the genome of their hosts, including transgenic plants expressing viral sequences. PMID:16857272

Le Provost, Grégoire; Iskra-Caruana, Marie-Line; Acina, Isabelle; Teycheney, Pierre-Yves

2006-10-01

430

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

431

Laser Timing Jitter Measurements using a Dual-Sweep Streak Camera at the A0 Photoinjector  

SciTech Connect

Excellent phase stability of the drive laser is a critical performance specification of photoinjectors such as Fermilab's A0 photoinjector (A0PI). Previous efforts based on the measurement of the power spectrum of the signal of a fast photodiode illuminated by the mode locked infrared laser pulse component indicated a phase jitter of less than 1.4 ps (technique limited). A recently procured dual sweep plugin unit and existing Hamamatsu C5680 streak camera were used to study the phase stability of the UV laser pulse component. Initial measurements with the synchroscan vertical sweep unit locked to 81.25 MHz showed that the phase slew through the micropulse train and the phase jitter micropulse to micropulse were two key aspects that could be evaluated. The phase slew was much less than 100 fs per micropulse, and the total phase jitter (camera, trigger, and laser) was approximately 300 fs RMS for measurements of 50-micropulse trains. Data on the macropulse phase stability were also obtained. A possible upgrade to achieve better phase stability will be also discussed.

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

2009-04-30

432

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

433

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

434

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

435

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

436

Phenotyping maize for adaptation to drought  

PubMed Central

The need of a better adaptation of crops to drought is an issue of increasing urgency. However, enhancing the tolerance of maize has, therefore, proved to be somewhat elusive in terms of plant breeding. In that context, proper phenotyping remains as one of the main factors limiting breeding advance. Topics covered by this review include the conceptual framework for identifying secondary traits associated with yield response to drought and how to measure these secondary traits in practice. PMID:22934056

Araus, Jose L.; Serret, María D.; Edmeades, Gregory O.

2012-01-01

437

Mitochondrial Biogenesis during Germination in Maize Embryos  

Microsoft Academic Search

Mitochondrial biogenesis and metabolism were investigated during maize (Zea mays) seed germination. Mitochondria from dry and imbibed seed exhibited NADH-dependent O2 uptake that was completely inhibited by KCN and antimycin A. Mitochondria in the dry seed had a lower rate of succinate-dependent O2 uptake relative to that measured in imbibed and germinated seed. The activities of the tricarboxylic acid (TCA)

David C. Logan; A. Harvey Millar; Lee J. Sweetlove; Steven A. Hill; Christopher J. Leaver

2001-01-01

438

Temperature sensing by primary roots of maize  

NASA Technical Reports Server (NTRS)

Zea mays L. seedlings, grown on agar plates at 26 degrees C, reoriented the original vertical direction of their primary root when exposed to a thermal gradient applied perpendicular to the gravity vector. The magnitude and direction of curvature can not be explained simply by either a temperature or a humidity effect on root elongation. It is concluded that primary roots of maize sense temperature gradients in addition to sensing the gravitational force.

Poff, K. L.

1990-01-01

439

Epistasis in maize ( Zea mays L.)  

Microsoft Academic Search

Three flint and three dent maize (Zea mays L.) inbred lines, their possible F1 crosses, F2 and backcross progenies, and all possible three-way crosses were evaluated in a three-year experiment for yield, ear moisture, and plant height. The purpose was to estimate genetic parameters in European breeding materials from (i) generation means analysis, (ii) diallel analysis of generation means, and

A. E. Melchinger; H. H. Geiger; F. W. Schnell

1986-01-01

440

A model-based approach to preplanting risk assessment for gray leaf spot of maize.  

PubMed

ABSTRACT Risk assessment models for gray leaf spot of maize, caused by Cercospora zeae-maydis, were developed using preplanting site and maize genotype data as predictors. Disease severity at the dough/dent plant growth stage was categorized into classes and used as the response variable. Logistic regression and classification and regression tree (CART) modeling approaches were used to predict severity classes as a function of planting date (PD), amount of maize soil surface residue (SR), cropping sequence, genotype maturity and gray leaf spot resistance (GLSR) ratings, and longitude (LON). Models were development using 332 cases collected between 1998 and 2001. Thirty cases collected in 2002 were used to validate the models. Preplanting data showed a strong relationship with late-season gray leaf spot severity classes. The most important predictors were SR, PD, GLSR, and LON. Logistic regression models correctly classified 60 to 70% of the validation cases, whereas the CART models correctly classified 57 to 77% of these cases. Cases misclassified by the CART models were mostly due to overestimation, whereas the logistic regression models tended to misclassify cases by underestimation. Both the CART and logistic regression models have potential as management decision-making tools. Early quantitative assessment of gray leaf spot risk would allow for more sound management decisions being made when warranted. PMID:18943706

Paul, P A; Munkvold, G P

2004-12-01

441

Preparation and certification of zearalenone mass concentration of two low-level maize reference materials.  

PubMed

The contamination of maize by fungi, especially by Fusarium species, is a worldwide problem. One of the most prevalent Fusarium mycotoxins frequently found on European maize is zearalenone (ZON), which has been implicated in a range of human and animal diseases. It shows remarkable estrogenic properties and can cause severe infertility problems in farm animals. Currently, 9 countries have set maximum tolerable levels for ZON in food, ranging from 0 to 1000 microg/kg. This paper describes the preparation of 2 maize reference materials (BCR-716 very low level ZON and BCR-717 low level ZON) and the certification of their individual ZON contents (mass concentration and mass fraction). Uncertainties were calculated in compliance with the Guide to the Expression of Uncertainty in Measurement and include uncertainties that are due to possible inhomogeneity and instability. Finally, BCR-716 was certified at a level of <5 microg/kg and BCR-717 at a level of 83 microg/kg with an expanded uncertainty (k = 2) of 9 microg/kg. PMID:15295884

Krska, Rudolf; Josephs, Ralf D; Pettersson, Hans; MacDonald, Susan

2004-01-01

442

A L G A E 11 disease follows, wiping out entire crops. The primary  

E-print Network

the disease cycle. Aphids that feed on infected maize can be infected within minutes; they then carry.M. Engeman. 2004. Feral swine impacts on agriculture and the environment. Sheep and Goat Research Journal 19

Smith, Jennifer E.

443

Aflatoxin Control in Maize by Trametes versicolor  

PubMed Central

Aspergillus flavus is a well-known ubiquitous fungus able to contaminate both in pre- and postharvest period different feed and food commodities. During their growth, these fungi can synthesise aflatoxins, secondary metabolites highly hazardous for animal and human health. The requirement of products with low impact on the environment and on human health, able to control aflatoxin production, has increased. In this work the effect of the basidiomycete Trametes versicolor on the aflatoxin production by A. flavus both in vitro and in maize, was investigated. The goal was to propose an environmental loyal tool for a significant control of aflatoxin production, in order to obtain feedstuffs and feed with a high standard of quality and safety to enhance the wellbeing of dairy cows. The presence of T. versicolor, grown on sugar beet pulp, inhibited the production of aflatoxin B1 in maize by A. flavus. Furthermore, treatment of contaminated maize with culture filtrates of T. versicolor containing ligninolytic enzymes, showed a significant reduction of the content of aflatoxin B1. PMID:25525683

Scarpari, Marzia; Bello, Cristiano; Pietricola, Chiara; Zaccaria, Marco; Bertocchi, Luigi; Angelucci, Alessandra; Ricciardi, Maria Rosaria; Scala, Valeria; Parroni, Alessia; Fabbri, Anna A.; Reverberi, Massimo; Zjalic, Slaven; Fanelli, Corrado

2014-01-01

444

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

445

Distribution of expansins in graviresponding maize roots  

NASA Technical Reports Server (NTRS)

To test if expansins, wall loosening proteins that disrupt binding between microfibrils and cell wall matrix, participate in the differential elongation of graviresponding roots, Zea mays L. cv. Merit roots were gravistimulated and used for immunolocalization with anti-expansin. Western blots showed cross-reaction with two proteins of maize, one of the same mass as cucumber expansin (29 kDa), the second slightly larger (32 kDa). Maize roots contained mainly the larger protein, but both were found in coleoptiles. The expansin distribution in cucumber roots and hypocotyls was similar to the distribution in maize. Roots showed stronger expansin signals on the expanding convex side than the concave flank as early as 30 min after gravistimulation. Treatment with brefeldin A, a vesicle transport inhibitor, or the auxin transport inhibitor, naphthylphthalamic acid, showed delayed graviresponse and the appearance of differential staining. Our results indicate that expansins may be transported and secreted to cell walls via vesicles and function in wall expansion.

Zhang, N.; Hasenstein, K. H.

2000-01-01

446

Aflatoxin Control in Maize by Trametes versicolor.  

PubMed

Aspergillus flavus is a well-known ubiquitous fungus able to contaminate both in pre- and postharvest period different feed and food commodities. During their growth, these fungi can synthesise aflatoxins, secondary metabolites highly hazardous for animal and human health. The requirement of products with low impact on the environment and on human health, able to control aflatoxin production, has increased. In this work the effect of the basidiomycete Trametes versicolor on the aflatoxin production by A. flavus both in vitro and in maize, was investigated. The goal was to propose an environmental loyal tool for a significant control of aflatoxin production, in order to obtain feedstuffs and feed with a high standard of quality and safety to enhance the wellbeing of dairy cows. The presence of T. versicolor, grown on sugar beet pulp, inhibited the production of aflatoxin B1 in maize by A. flavus. Furthermore, treatment of contaminated maize with culture filtrates of T. versicolor containing ligninolytic enzymes, showed a significant reduction of the content of aflatoxin B1. PMID:25525683

Scarpari, Marzia; Bello, Cristiano; Pietricola, Chiara; Zaccaria, Marco; Bertocchi, Luigi; Angelucci, Alessandra; Ricciardi, Maria Rosaria; Scala, Valeria; Parroni, Alessia; Fabbri, Anna A; Reverberi, Massimo; Zjalic, Slaven; Fanelli, Corrado

2014-01-01

447

Differential Localization of Antioxidants in Maize Leaves.  

PubMed Central

The aim of this work was to determine the compartmentation of antioxidants between the bundle-sheath and mesophyll cells of maize (Zea mays L.) leaves. Rapid fractionation of the mesophyll compartment was used to minimize modifications in the antioxidant status and composition due to extraction procedures. The purity of the mesophyll isolates was assessed via the distribution of enzyme and metabolite markers. Ribulose-1,5 bisphosphate and ribulose-1,5-bisphosphate carboxylase/oxygenase were used as bundle-sheath markers and phosphoenolpyruvate carboxylase was used as the mesophyll marker enzyme. Glutathione reductase and dehydroascorbate reductase were almost exclusively localized in the mesophyll tissue, whereas ascorbate, ascorbate peroxidase, and superoxide dismutase were largely absent from the mesophyll fraction. Catalase, reduced glutathione, and monodehydroascorbate reductase were found to be approximately equally distributed between the two cell types. It is interesting that, whereas H2O2 levels were relatively high in maize leaves, this oxidant was largely restricted to the mesophyll compartment. We conclude that the antioxidants in maize leaves are partitioned between the two cell types according to the availability of reducing power and NADPH and that oxidized glutathione and dehydroascorbate produced in the bundle-sheat tissues have to be transported to the mesophyll for re-reduction to their reduced forms. PMID:12223757

Doulis, A. G.; Debian, N.; Kingston-Smith, A. H.; Foyer, C. H.

1997-01-01

448

THE EFFECTS OF COMBINING REGIONS OF CHROMOSOMES 3, 6 AND 10 ON RESISTANCE TO MAIZE DWARF MOSAIC VIRUS (MDMV) AND SUGARCANE MOSAIC VIRUS-MDB (SCMV)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Genes controlling resistance to diseases caused by viruses in the family Potyviridae have mapped to maize chromosomes three, six and ten. To study the effects of the individual genes, near isogenic lines (NIL) were made that carry specific chromosomal regions from the highly resistant inbred line P...

449

Analysis of the Fusarium graminearum species complex from wheat, barley, and maize in South Africa provides evidence of species-specific differences in host preference  

Technology Transfer Automated Retrieval System (TEKTRAN)

Species identity and trichothecene toxin potential of 560 members of the Fusarium graminearum species complex (FGSC) collected from diseased wheat, barley and maize in South Africa was determined using a microsphere-based multilocus genotyping assay. Although three trichothecene types (3-ADON, 15-AD...

450

Identification of Quantitative Trait Loci for Resistance to Southern Leaf Blight and Days to Anthesis in Two Maize Recombinant Inbred Line Populations  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two recombinant inbred line populations derived from crosses between maize lines H99 and B73 (HB population) and between B73 and B52 (BB population) were evaluated for resistance to southern leaf blight (SLB) disease caused by Cochliobolus heterostrophus race O and for days to anthesis (DTA) in tw...

451

MRG1-1 , a dominant allele that confers methomyl resistance in yeast expressing the cytoplasmic male sterility T- urf13 gene from maize  

Microsoft Academic Search

We have previously described a eukaryotic heterologous expression system, with the urf13TW gene in yeast, which mimics the disease susceptibility associated with the Texas cytoplasmic male sterility in maize. This yeast model was used to isolate yeast nuclear mutants conferring methomyl resistance. The genetic strategy we have developed focused on screening for nuclear dominant yeast mutations which restore methomyl resistance.

Nathalie Glab; Marie-Ange Teste; Piotr P. Slonimski

1994-01-01

452

Improvement of resistance to maize dwarf mosaic virus mediated by transgenic RNA interference.  

PubMed

To overcome the low efficiency of agronomic protection from maize dwarf mosaic disease, susceptible maize inbred line was transformed by Agrobacterium tumefaciens harboring hpRNA expression vectors containing inverted-repeat sequences of different lengths targeting coat protein gene (CP) of maize dwarf mosaic virus (MDMV). After PCR screening and Southern blotting, the flanking sequences of the integration sites were amplified by thermal asymmetric interlaced PCR (TAIL-PCR) and used for analysis of T-DNA integration patterns. The T? plant lines were evaluated for their MDMV resistance in field inoculation trials under two environments. Of the nineteen T? plant lines positive in Southern blotting, six were evaluated as resistant to MDMV, and four of them had resistance non-significantly different from the highly resistant control "H9-21", while the resistance of the other eleven was proved to be significantly improved when compared to their non-transformed parent line. These improvements in MDMV resistance were verified by the relative amount of virus CP gene expression measured by quantitative real time PCR. Comparing the results of Southern blotting and TAIL-PCR analysis, different integration patterns of one or two copies of the inverted-repeat sequences were identified from non-repetitive and repetitive sequences of the maize genome. The MDMV resistance mediated by RNA interference is relative to the length of the inverted-repeat sequence, the copy number of T-DNA integration and the repeatability of integration sites. A longer hpRNA expression construct shows more efficiency than a shorter one. PMID:21504770

Zhang, Zhi-Yong; Yang, Lin; Zhou, Shu-Feng; Wang, Han-Guang; Li, Wan-Chen; Fu, Feng-Ling

2011-05-20

453

Colinearity and Its Exceptions in Orthologous adh Regions of Maize and Sorghum  

Microsoft Academic Search

Orthologous adh regions of the sorghum and maize genomes were sequenced and analyzed. Nine known or candidate genes, including adh1, were found in a 225-kilobase (kb) maize sequence. In a 78-kb space of sorghum, the nine homologues of the maize genes were identified in a colinear order, plus five additional genes. The major fraction of DNA in maize, occupying 166

Alexander P. Tikhonov; Phillip J. Sanmiguel; Yuko Nakajima; Nina M. Gorenstein; Jeffrey L. Bennetzen; Zoya Avramova

1999-01-01

454

Chromatin Immunoprecipitation for Studying Chromosomal Localization of Meiotic Proteins in Maize  

E-print Network

Proteins in Maize Yan He, Gaganpreet Sidhu, and Wojciech P. Pawlowski Abstract Chromatin proteins in maize. Keywords Chromosomes, Chromatin, Immunoprecipitation, Antibody, Maize, Recombination to discrete sites on maize chromosomes during zygotene. Chromosome sites where RAD51 is located can be determ

Pawlowski, Wojtek

455

REGULAR ARTICLE Maize yield and nutrition during 4 years after biochar  

E-print Network

REGULAR ARTICLE Maize yield and nutrition during 4 years after biochar application to a Colombian for 4 years (2003­2006), under a maize-soybean rotation. Soil sampling to 30 cm was carried out after maize harvest in all years but 2005, maize tissue samples were collected and crop biomass was measured

Lehmann, Johannes

456

EFFECT OF HYDROTHERMAL TREATMENT ON THE PHYSICAL AND RHEOLOGICAL PROPERTIES OF MAIZE STARCHES  

E-print Network

EFFECT OF HYDROTHERMAL TREATMENT ON THE PHYSICAL AND RHEOLOGICAL PROPERTIES OF MAIZE STARCHES C;Abstract. Standard maize (SMS) and waxy maize starch (WMS) were hydrothermally treated at their residual and processing time, on the structural and rheological properties of the native maize starches were described

Paris-Sud XI, Université de

457

MADS-box genes of maize: frequent targets of selection during domestication  

E-print Network

MADS-box genes of maize: frequent targets of selection during domestication QIONG ZHAO1 development. We examined DNA sequence variation in 32 maize MADS-box genes and 32 randomly chosen maize loci and investigated their involvement in maize domestication and improvement. Using neutrality tests and a test based

Doebley, John