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1

Sequence Analysis of the Complete Genome of Rice Black-Streaked Dwarf Virus Isolated from Maize with Rough Dwarf Disease  

Microsoft Academic Search

The complete nucleotide sequences of 10 genomic segments (S1–S10) from an isolate of rice black-streaked dwarf virus causing rough dwarf disease on maize (RBSDV-Hbm) in China were determined, a total of 29,142 base pairs (bp). Each segment possessed the genus-specific termini with conserved nucleotide sequences of (+) 5'-AAGUUUUU?......?CAGCUNNNGUC-3' and a perfect or imperfect inverted repeat of seven to eleven nucleotides

Zhao-Hui Wang; Shou-Guo Fang; Jia-Ling Xu; Li-Ying Sun; Da-Wei Li; Jia-Lin Yu

2003-01-01

2

Forced recombination between distinct strains of Maize streak virus  

Microsoft Academic Search

Recombination between divergent virus genomes is believed to be a major mechanism for generation of novel virus genotypes. We have examined the recombination process in gemini- viruses by forcing recombination between two distinct isolates of Maize streak virus (MSV), MSV- Kom and MSV-Set. Heterodimeric agroinfectious constructs containing tandemly cloned mixtures of complete or partial MSV-Set and MSV-Kom genomes were used

W. H. Schnippenkoetter; D. P. Martin; J. A. Willment; E. P. Rybicki

3

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

PubMed Central

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

2011-01-01

4

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...

5

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

PubMed

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

2008-09-01

6

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  

Microsoft Academic Search

Three maize streak virus (MSV) isolates were de- rived 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

Muriel Isnard; Martine Granier; Roger Frutos; Bernard Reynaud; Michel Peterschmitt

1998-01-01

7

Genetic mapping of maize streak virus resistance from the Mascarene source. II. Resistance in line CIRAD390 and stability across germplasm  

Microsoft Academic Search

The streak disease has a major effect on maize in sub-Saharan Africa. Various genetic factors for resistance to the virus\\u000a have been identified and mapped in several populations; these factors derive from different sources of resistance. We have\\u000a focused on the Runion island source and have recently identified several factors in the D211 line. A second very resistant\\u000a line, CIRAD390,

A. Pernet; D. Hoisington; J. Dintinger; D. Jewell; C. Jiang; M. Khairallah; P. Letourmy; J.-L. Marchand; J.-C. Glaszmann; D. González de León

1999-01-01

8

Cassava brown streak disease re-emerges in Uganda  

Microsoft Academic Search

Cassava brown streak disease (CBSD) is an important virus disease that damages the starch-bearing tuberous roots of cassava. The disease is endemic in the coastal lowlands of Eastern Africa and the coastal strip of Lake Malawi. CBSD has rarely been seen at altitudes above 1000 m above sea level, although the reason for this is unknown. CBSD is maintained through

C. Omongo; R. J. Hillocks; R. Kawuki; G. W. Otim-Nape

9

Infectivity and complete nucleotide sequence of the genome of a genetically distinct strain of maize streak virus from Reunion Island  

Microsoft Academic Search

Summary A complete infectious genome of an isolate of maize streak subgroup 1 geminivirus from Reunion Island (MSV-R) was cloned and sequenced. Using anAgrobacterium tumefaciens Ti plasmid delivery system, the cloned 2.7 kb circular DNA was shown to be infectious in maize. The agroinfected virus could be transmitted byCicadulina mbila, the most common vector species of MSV in Reunion. Analysis

M. Peterschmitt; M. Granier; R. Frutos; B. Reynaud

1996-01-01

10

Transcriptome of the plant virus vector Graminella nigrifrons, and the molecular interactions of Maize fine streak rhabdovirus transmission  

Technology Transfer Automated Retrieval System (TEKTRAN)

Background: Leafhoppers (Hemiptera:Cicadellidae) are plant-phloem feeders that are known for their ability to vector plant pathogens. The black-faced leafhopper (Graminella nigrifrons) has been identified as the only known vector for the Maize fine streak virus (MFSV), an emerging plant pathogen in...

11

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

PubMed Central

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

Monjane, Aderito 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; Tiendrebeogo, Fidele; Erdmann, Julia B.; van Antwerpen, Tania; Owor, Betty E.; Flett, Bradley; Ramusi, Moses; Windram, Oliver P.; Syed, Rizwan; Lett, Jean-Michel; Briddon, Rob W.; Markham, Peter G.; Rybicki, Edward P.; Varsani, Arvind

2011-01-01

12

Etiology and transmission of mottle streak disease of finger millet (Eleusine coracana Gaertn.)  

Microsoft Academic Search

Four stages in the development of symptoms commencing from small specks to total yellowing were observed in finger millet infected by mottle streak disease. Presence of bacilliform Rhabdovirus particles was ascertained under electron microscope in all the leaf samples that exhibited varying degrees of mottle streak infection, viz. mottling, streaking, striping and yellowing. Different buffers at various pH were attempted

Kandhasamy Saveetha; Ambalavanan Sankaralingam; Rajendra Pant; Ayyasami Ramanathan

2007-01-01

13

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.

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

2008-01-01

14

Evolution of cassava brown streak disease-associated viruses.  

PubMed

Cassava brown streak disease (CBSD) has occurred in the Indian Ocean coastal lowlands and some areas of Malawi in East Africa for decades, and makes the storage roots of cassava unsuitable for consumption. CBSD is associated with Cassava brown streak virus (CBSV) and the recently described Ugandan cassava brown streak virus (UCBSV) [picorna-like (+)ssRNA viruses; genus Ipomovirus; family Potyviridae]. This study reports the first comprehensive analysis on how evolution is shaping the populations of CBSV and UCBSV. The complete genomes of CBSV and UCBSV (four and eight isolates, respectively) were 69.0-70.3 and 73.6-74.4% identical at the nucleotide and polyprotein amino acid sequence levels, respectively. They contained predictable sites of homologous recombination, mostly in the 3'-proximal part (NIb-HAM1h-CP-3'-UTR) of the genome, but no evidence of recombination between the two viruses was found. The CP-encoding sequences of 22 and 45 isolates of CBSV and UCBSV analysed, respectively, were mainly under purifying selection; however, several sites in the central part of CBSV CP were subjected to positive selection. HAM1h (putative nucleoside triphosphate pyrophosphatase) was the least similar protein between CBSV and UCBSV (aa identity approx. 55%). Both termini of HAM1h contained sites under positive selection in UCBSV. The data imply an on-going but somewhat different evolution of CBSV and UCBSV, which is congruent with the recent widespread outbreak of UCBSV in cassava crops in the highland areas (>1000 m above sea level) of East Africa where CBSD has not caused significant problems in the past. PMID:21169213

Mbanzibwa, D R; Tian, Y P; Tugume, A K; Patil, B L; Yadav, J S; Bagewadi, B; Abarshi, M M; Alicai, T; Changadeya, W; Mkumbira, J; Muli, M B; Mukasa, S B; Tairo, F; Baguma, Y; Kyamanywa, S; Kullaya, A; Maruthi, M N; Fauquet, C M; Valkonen, J P T

2010-12-15

15

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

16

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

PubMed Central

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

2012-01-01

17

Transmission and distribution of cassava brown streak virus disease in cassava growing areas of Kenya  

Microsoft Academic Search

Objectives: To determine the incidence and distribution of cassava brown streak disease (CBSD) in relation to Bemisia tabaci populations in Central, Eastern, Nyanza and Western provinces of Kenya and investigate the ability of 4 cassava pests to transmit cassava brown streak virus (CBSV). Methodology and results: A multistage sampling survey was conducted from November 2006 to April 2007 to determine

B. O. MWARE; E. M. ATEKA; J. M. SONGA; R. D. NARLA; F. OLUBAYO; R. AMATA

18

Identification of genetic markers linked to banana streak disease expression in inter-specific Musa hybrids  

Microsoft Academic Search

Recently-introduced inter-specific Musa hybrids, bred for improved yield and resistance to diseases, have been found to be widely infected with banana streak virus (BSV), the causal agent of banana streak disease (BSD). One hypothesis suggests: (1) that BSD occurrence in these inter-specific hybrids results from activation of BSV-Ol endogenous pararetrovirus sequences (EPRV) integrated into the Musa genome rather than from

F. Lheureux; F. Carreel; C. Jenny; B. E. L. Lockhart; M. L. Iskra-Caruana

2003-01-01

19

Cassava brown streak disease: A review of present knowledge and research needs  

Microsoft Academic Search

Cassava (Manihot esculenta) is an important subsistence food crop in Africa where it is affected by two main virus diseases, cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). CMD occurs in all the cassava-growing countries on the continent and it has been much researched. CBSD occurs mainly on the East African coast, and although the disease was first

RJ Hillocks; DL Jennings

2003-01-01

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

Viable chimaeric viruses confirm the biological importance of sequence specific maize streak virus movement protein and coat protein interactions  

PubMed Central

Background A variety of interactions between up to three different movement proteins (MPs), the coat protein (CP) and genomic DNA mediate the inter- and intra-cellular movement of geminiviruses in the genus Begomovirus. Although movement of viruses in the genus Mastrevirus is less well characterized, direct interactions between a single MP and the CP of these viruses is also clearly involved in both intra- and intercellular trafficking of virus genomic DNA. However, it is currently unknown how specific these MP-CP interactions are, nor how disruption of these interactions might impact on virus viability. Results Using chimaeric genomes of two strains of Maize streak virus (MSV) we adopted a genetic approach to investigate the gross biological effects of interfering with interactions between virus MP and CP homologues derived from genetically distinct MSV isolates. MP and CP genes were reciprocally exchanged, individually and in pairs, between maize (MSV-Kom)- and Setaria sp. (MSV-Set)-adapted isolates sharing 78% genome-wide sequence identity. All chimaeras were infectious in Zea mays c.v. Jubilee and were characterized in terms of symptomatology and infection efficiency. Compared with their parental viruses, all the chimaeras were attenuated in symptom severity, infection efficiency, and the rate at which symptoms appeared. The exchange of individual MP and CP genes resulted in lower infection efficiency and reduced symptom severity in comparison with exchanges of matched MP-CP pairs. Conclusion Specific interactions between the mastrevirus MP and CP genes themselves and/or their expression products are important determinants of infection efficiency, rate of symptom development and symptom severity.

van der Walt, Eric; Palmer, Kenneth E; Martin, Darren P; Rybicki, Edward P

2008-01-01

22

Genetic gain and cost efficiency of marker-assisted selection of maize for improved resistance to multiple foliar pathogens  

Microsoft Academic Search

Northern corn leaf blight (NCLB) caused by Exserohilum turcicum, gray leaf spot (GLS) caused by Cercospora zeae-maydis and maize streak caused by maize streak Mastrevirus (MSV) are the most destructive foliar diseases limiting maize production in sub-Saharan Africa. Most foliar diseases of maize\\u000a are managed using quantitative (partial) resistance, and previous studies have reported quantitative trait loci associated\\u000a with host

Godfrey AseaBindiganavile; Bindiganavile S. Vivek; Patrick E. Lipps; Richard C. Pratt

23

Analysis of cassava brown streak viruses reveals the presence of distinct virus species causing cassava brown streak disease in East Africa.  

PubMed

Cassava brown streak virus (CBSV) isolates were analysed from symptomatic cassava collected between 1997 and 2008 in the major cultivation regions of East Africa. An analysis of complete RNA genomes of seven isolates from Kenya, Tanzania, Mozambique, Uganda and Malawi revealed a common genome structure, but the isolates clearly clustered in two distinct clades. The first comprised isolates from Kenya, Uganda, Malawi, north-western Tanzania and the CBSV described previously, and shared between 87 and 95% nucleotide sequence identity, whilst the second included isolates from coastal regions of Mozambique and Tanzania, which shared only 70% nucleotide sequence identities with isolates of the first clade. When the amino acid sequences of viral proteins were compared, identities as low as 47% (Ham1) and 59% (P1) between the two clades were found. An antiserum obtained against the capsid protein of a clade 1 isolate identified a 43 kDa protein in clade 1 isolates and a 45 kDa protein in clade 2 isolates. Several cassava cultivars were susceptible to isolates of clade 2 but resistant to those of clade 1. The differences observed both in biological behaviour and in genomic and protein sequences indicate that cassava brown streak disease in East Africa is caused by at least two distinct virus species. It is suggested that those of clade 1 retain the species name Cassava brown streak virus, whilst those of clade 2 be classified as Cassava brown streak Mozambique virus. PMID:20071490

Winter, Stephan; Koerbler, Marianne; Stein, Beate; Pietruszka, Agnes; Paape, Martina; Butgereitt, Anja

2010-01-13

24

Diallel analysis of cassava brown streak disease, yield and yield related characteristics in Mozambique  

Microsoft Academic Search

Cassava brown streak disease (CBSD) reported from 1999 in Mozambique, now constitutes the main production constraint in the\\u000a country. CBSD may be found in all plant parts, affecting food security and availability and quality of planting material.\\u000a The aim of this study was to evaluate the relative importance of general (GCA) and specific combining ability (SCA), and inheritance\\u000a of relevant

A. M. Zacarias; M. T. Labuschagne

2010-01-01

25

An intact RBR-binding motif is not required for infectivity of Maize streak virus in cereals, but is required for invasion of mesophyll cells.  

PubMed

The replication-associated protein (RepA) of Maize streak virus interacts in yeast with retinoblastoma-related protein (RBR), the negative regulator of cell-cycle progression. This may allow geminiviruses to subvert cell-cycle control to provide an environment that is suitable for viral DNA replication. To determine the importance of this interaction for MSV infection, the RBR-binding motif, LxCxE, was mutated to IxCxE or LxCxK. Whilst RBR binding in yeast could not be detected for the LxCxK mutant, the IxCxE protein retained limited binding activity. Both mutants were able to replicate in maize cultures and to infect maize plants. However, whereas the wild-type virus invaded mesophyll cells of mature leaves, the LxCxK mutant was restricted to the vasculature, which is invaded prior to leaf maturity. Mature leaves contain high levels of RBR and it is suggested that the MSV RepA-RBR interaction is essential only in tissues with high levels of active RBR. PMID:15722542

McGivern, David R; Findlay, Kim C; Montague, Nicholas P; Boulton, Margaret I

2005-03-01

26

Successful application of FTA Classic Card technology and use of bacteriophage phi29 DNA polymerase for large-scale field sampling and cloning of complete maize streak virus genomes.  

PubMed

Leaf samples from 155 maize streak virus (MSV)-infected maize plants were collected from 155 farmers' fields in 23 districts in Uganda in May/June 2005 by leaf-pressing infected samples onto FTA Classic Cards. Viral DNA was successfully extracted from cards stored at room temperature for 9 months. The diversity of 127 MSV isolates was analysed by PCR-generated RFLPs. Six representative isolates having different RFLP patterns and causing either severe, moderate or mild disease symptoms, were chosen for amplification from FTA cards by bacteriophage phi29 DNA polymerase using the TempliPhi system. Full-length genomes were inserted into a cloning vector using a unique restriction enzyme site, and sequenced. The 1.3-kb PCR product amplified directly from FTA-eluted DNA and used for RFLP analysis was also cloned and sequenced. Comparison of cloned whole genome sequences with those of the original PCR products indicated that the correct virus genome had been cloned and that no errors were introduced by the phi29 polymerase. This is the first successful large-scale application of FTA card technology to the field, and illustrates the ease with which large numbers of infected samples can be collected and stored for downstream molecular applications such as diversity analysis and cloning of potentially new virus genomes. PMID:17174409

Owor, Betty E; Shepherd, Dionne N; Taylor, Nigel J; Edema, Richard; Monjane, Adérito L; Thomson, Jennifer A; Martin, Darren P; Varsani, Arvind

2006-12-15

27

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

2012-07-31

28

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

PubMed

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

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

2012-07-20

29

Characterization of the sugarcane streak agent as a distinct geminivirus.  

PubMed

The relationship between maize streak virus and the geminivirus causing streak in sugarcane was investigated. The DNA of sugarcane streak virus does not cross-hybridize detectably with that of maize streak virus and vice versa. Restriction mapping of native replicative form viral DNA (genome size 2.7 kb) and of cloned viral DNA, combined with limited sequencing and estimated DNA sequence divergence, showed that sugarcane streak virus is as unrelated to maize streak virus and digitaria streak virus as these are different from each other. The virus is only distantly related to wheat dwarf virus and chloris striate mosaic virus. Based on these results, we propose that the agent causing sugarcane streak is a distinct geminivirus. PMID:2016148

Hughes, F L; Rybicki, E P; Kirby, R; von Wechmar, M B

1991-01-01

30

Role of Dehydrodiferulates in Maize Resistance to Pests and Diseases  

PubMed Central

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

Santiago, Rogelio; Malvar, Rosa A.

2010-01-01

31

Seed treatments enhance photosynthesis in maize seedlings by reducing infection with Fusarium spp. and consequent disease development in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effects of a seed treatment on early season growth, seedling disease development, incidence Fusarium spp. infection, and photosynthetic performance of maize were evaluated at two locations in Iowa in 2007. Maize seed was either treated with Cruiser 2Extreme 250 ® (fludioxonil + azoxystrobin + me...

32

Plant-pathogen microevolution: Molecular basis for the origin of a fungal disease in maize  

Microsoft Academic Search

A new and severe disease of maize caused by a previously unknown fungal pathogen, Cochliobolus carbonum race 1, was first described in 1938. The molecular events that led to the sudden appearance of this disease are described in this paper. Resistance to C. carbonum race 1 was found to be widespread in maize and is conferred by a pair of

D. S. Multani; R. B. MEELEY; A. H. P ATERSON; J. G RAY; S. P. BRIGGS; G. S. JOHAL

1998-01-01

33

Primitive Streak (dorsal view)  

NSDL National Science Digital Library

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

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

2011-06-23

34

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

35

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

36

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

37

Cytogenetic mapping of disease resistance genes and analysis of their distribution features on chromosomes in maize  

Microsoft Academic Search

Cytogenetie maps of four clusters of disease resistance genes were generated by ISH of the two RFLP markers tightly linked\\u000a to and flanking each of maize resistance genes and the cloned resistance genes from other plant species onto maize chromosomes,\\u000a combining with data published before. These genes includeHelminthosporium turcium Pass resistance genes Ht1, Htn1 and Ht2,Helminthosporium maydis Nisik resistance genes

Li-jia Li; Yun-chun Song

2003-01-01

38

Systematic analysis and comparison of nucleotide-binding site disease resistance genes in maize.  

PubMed

Nucleotide-binding site (NBS) disease resistance genes play an integral role in defending plants from a range of pathogens and insect pests. Consequently, a number of recent studies have focused on NBS-encoding genes in molecular disease resistance breeding programmes for several important plant species. Little information, however, has been reported with an emphasis on systematic analysis and a comparison of NBS-encoding genes in maize. In the present study, 109 NBS-encoding genes were identified based on the complete genome sequence of maize (Zea mays cv. B73), classified as four different subgroups, and then characterized according to chromosomal locations, gene duplications, structural diversity and conserved protein motifs. Subsequent phylogenetic comparisons indicated that several maize NBS-encoding genes possessed high similarity to function-known NBS-encoding genes, and revealed the evolutionary relationships of NBS-encoding genes in maize comparede to those in other model plants. Analyses of the physical locations and duplications of NBS-encoding genes showed that gene duplication events of disease resistance genes were lower in maize than in other model plants, which may have led to an increase in the functional diversity of the maize NBS-encoding genes. Various expression patterns of maize NBS-encoding genes in different tissues were observed using an expressed-sequence tags database and, alternatively, after southern leaf blight infection or the application of exogenous salicylic acid. The results reported in the present study contribute to an improved understanding of the NBS-encoding gene family in maize. PMID:22564701

Cheng, Ying; Li, Xiaoyu; Jiang, Haiyang; Ma, Wei; Miao, Weiyun; Yamada, Toshihiko; Zhang, Ming

2012-05-24

39

Comparison of Streak Tube Performance.  

National Technical Information Service (NTIS)

The performance of four streak tubes in six streak camera configurations is reported. Evaluations were made as part of a search for a streak tube to replace the obsolete RCA C73435 used in the ICF Program's optical streak cameras. Characteristics measured...

R. A. Lerche D. S. Andrews P. M. Bell R. L. Griffiths A. W. Huey J. W. McDonald G. Vergel de Dios

2004-01-01

40

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

PubMed

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

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

2013-10-21

41

On-farm selection for quality and resistance to pest\\/diseases of cocoa in Sulawesi: (ii) quality and performance of selections against Phytophthora pod rot and vascular-streak dieback  

Microsoft Academic Search

The cocoa industry in Sulawesi, the main region of cocoa production in Indonesia, is threatened by destructive diseases, including vascular-streak dieback (VSD) caused by the basidiomycete Oncobasidium theobromae and stem canker and Phytophthora pod rot (PPR) or black pod, caused by Phytophthora palmivora. Using the considerable genetic diversity of cocoa on farms, host resistance was identified and tested with the

Peter McMahon; Agus Purwantara; Agung W. Susilo; Sri Sukamto; Abdul Wahab; Hussin bin Purung; Muhammad Hidayat; Darna Ismail; Tap Taproni; Smilja Lambert; David Guest; Philip Keane

2010-01-01

42

Seed Treatment With EM and Micronutrients for Controlling Rice and Maize Diseases  

Microsoft Academic Search

A study was conducted to determine whether seed treatment of rice and maize with Effective Microorganisms (EM) and micro nutrients could reduce the incidence of disease and parasite injury, and prevent nutrient imbalances after germination. Potassium and certain micro nutrient metals (e.g., copper, zinc and manganese) are essential activators of enzyme systems for the biosynthesis of organic compounds in plants.

A. M. Primavesi; Fazenda Ecológica; Itaí SP Brazil

43

Endophytic Fusarium verticillioides reduces disease severity caused by Ustilago maydis on maize.  

PubMed

Endophytic fungi represent diverse taxa that inhabit plant hosts without causing disease symptoms. We used endophytic isolates of Fusarium verticillioides (Sacc.) Nirenberg to understand how endophytic fungi interact with pathogens, in this case, the corn smut pathogen, Ustilago maydis DC (Corda). Endophytic F. verticillioides strains were inoculated onto maize seedlings before, simultaneously, or after inoculation with U. maydis, and the effects on smut disease severity and on plant growth were assessed. When F. verticillioides is simultaneously coinoculated with U. maydis, smut disease severity is significantly decreased and plant growth is increased, compared with other treatments. Controls show that F. verticillioides by itself does not have measurable effects on plant growth. Together, our results suggest that a commonly occurring fungal endophyte on maize, F. verticillioides, ameliorates the effects of a host-specific pathogen, U. maydis, by interfering with the early infection process and limiting disease development, resulting in increased plant growth. PMID:19694816

Lee, Keunsub; Pan, Jean J; May, Georgiana

2009-07-10

44

Validation of consensus quantitative trait loci associated with resistance to multiple foliar pathogens of maize.  

PubMed

Maize production in sub-Saharan Africa incurs serious losses to epiphytotics of foliar diseases. Quantitative trait loci conditioning partial resistance (rQTL) to infection by causal agents of gray leaf spot (GLS), northern corn leaf blight (NCLB), and maize streak have been reported. Our objectives were to identify simple-sequence repeat (SSR) molecular markers linked to consensus rQTL and one recently identified rQTL associated with GLS, and to determine their suitability as tools for selection of improved host resistance. We conducted evaluations of disease severity phenotypes in separate field nurseries, each containing 410 F2:3 families derived from a cross between maize inbred CML202 (NCLB and maize streak resistant) and VP31 (a GLS-resistant breeding line) that possess complimentary rQTL. F2:3 families were selected for resistance based on genotypic (SSR marker), phenotypic, or combined data and the selected F3:4 families were reevaluated. Phenotypic values associated with SSR markers for consensus rQTL in bins 4.08 for GLS, 5.04 for NCLB, and 1.04 for maize streak significantly reduced disease severity in both generations based on single-factor analysis of variance and marker-interval analysis. These results were consistent with the presence of homozygous resistant parent alleles, except in bin 8.06, where markers were contributed by the NCLB-susceptible parent. Only one marker associated with resistance could be confirmed in bins 2.09 (GLS) and 3.06 (NCLB), illustrating the need for more robust rQTL discovery, fine-mapping, and validation prior to undertaking marker-based selection. PMID:19351250

Asea, Godfrey; Vivek, Bindiganavile S; Bigirwa, George; Lipps, Patrick E; Pratt, Richard C

2009-05-01

45

Primitive Streak, Oblique Overview  

NSDL National Science Digital Library

This FlashTM animation is the seventh and last of a series that presents the primitive streak from different angles. This installment displays the streak from an oblique angle, which provides an overview of simultaneous processes. Cells that ingress through the steak early insert into the underlying hypoblast and differentiate into endodermal cells. The notochordal process emerges from HensenÃÂs node. Mesenchyme dissociates from the streak and spreads throughout the germ disc. The distal end of the notochordal process fuses with the endoderm and flattens into the notochordal plate. The plate dissociates form the endoderm to form the solid notochord. Eventually the streak completely regresses, leaving the three germ layers; ectoderm, mesoderm, endoderm, with the notochord buried in the paraxial mesoderm. 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

46

Attosecond angular streaking  

Microsoft Academic Search

Ultrashort measurement-time resolution is traditionally obtained in pump–probe experiments, for which two ultrashort light pulses are required; the time resolution is then determined by the pulse duration. But although pulses of subfemtosecond duration are available, so far the energy of these pulses is too low to fully implement the traditional pump–probe technique. Here, we demonstrate ‘attosecond angular streaking’, an alternative

Mathias Smolarski; Philip Schlup; Jens Biegert; André Staudte; Markus Schöffler; Harm G. Muller; Reinhard Dörner; Ursula Keller; Petrissa Eckle

2008-01-01

47

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

PubMed

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

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

2013-03-10

48

The Development and Application of a Dot-ELISA Assay for Diagnosis of Southern Rice Black-Streaked Dwarf Disease in the Field  

PubMed Central

Outbreaks of the southern rice black-streaked dwarf virus (SRBSDV) have caused significant crop losses in southern China in recent years, especially in 2010. There are no effective, quick and practicable methods for the diagnosis of rice dwarf disease that can be used in the field. Traditional reverse transcription-polymerase chain reaction (RT-PCR) methodology is accurate but requires expensive reagents and instruments, as well as complex procedures that limit its applicability for field tests. To develop a sensitive and reliable assay for routine laboratory diagnosis, a rapid dot enzyme-linked immunosorbent assay (dot-ELISA) method was developed for testing rice plants infected by SRBSDV. Based on anti-SRBSDV rabbit antiserum, this new dot-ELISA was highly reliable, sensitive and specific toward SRBSDV. The accuracy of two blotting media, polyvinylidene fluoride membrane (PVDF membrane) and nitrocellulose filter membrane (NC membrane), was compared. In order to facilitate the on-site diagnosis, three county laboratories were established in Shidian (Yunnan province), Jianghua (Hunan Province) and Libo (Guizhou province). Suspected rice cases from Shidian, Yuanjiang and Malipo in Yunnan province were tested and some determined to be positive for SRBSDV by the dot-ELISA and confirmed by the One Step RT-PCR method. To date, hundreds of suspected rice samples collected from 61 districts in southwestern China have been tested, among which 55 districts were found to have rice crops infected by SRBSDV. Furthermore, the test results in the county laboratories showed that Libo, Dehong (suspected samples were sent to Shidian) and Jianghua were experiencing a current SRBSDV outbreak.

Wang, Zhenchao; Yu, Dandan; Li, Xiangyang; Zeng, Mengjiao; Chen, Zhuo; Bi, Liang; Liu, Jiaju; Jin, Linhong; Hu, Deyu; Yang, Song; Song, Baoan

2012-01-01

49

Angioid streaks, clinical course, complications, and current therapeutic management  

PubMed Central

Angioid streaks are visible irregular crack-like dehiscences in Bruch’s membrane that are associated with atrophic degeneration of the overlying retinal pigmented epithelium. Angioid streaks may be associated with pseudoxanthoma elasticum, Paget’s disease, sickle-cell anemia, acromegaly, Ehlers–Danlos syndrome, and diabetes mellitus, but also appear in patients without any systemic disease. Patients with angioid streaks are generally asymptomatic, unless the lesions extend towards the foveola or develop complications such as traumatic Bruch’s membrane rupture or macular choroidal neovascularization (CNV). The visual prognosis in patients with CNV secondary to angioid streaks if untreated, is poor and most treatment modalities, until recently, have failed to limit the devastating impact of CNV in central vision. However, it is likely that treatment with antivascular endothelial growth factor, especially in treatment-naive eyes to yield favorable results in the future and this has to be investigated in future studies.

Georgalas, Ilias; Papaconstantinou, Dimitris; Koutsandrea, Chrysanthi; Kalantzis, George; Karagiannis, Dimitris; Georgopoulos, Gerasimos; Ladas, Ioannis

2009-01-01

50

Mechanical Transmission of Cassava Brown Streak Virus  

Microsoft Academic Search

BROWN streak virus disease of cassava (Manihot utilissima Pohl.) is important in all the cassava-growing areas on the coasts of Kenya and Tanganyika, because necrosis of the starch storage tissues of the roots and stems of infected plants results in serious losses in yield1,2. Transmission of the virus by a white fly (Bemisia sp.) is suspected but has not been

R. M. Lister

1959-01-01

51

Disease resistance in maize and the role of molecular breeding in defending against global threat.  

PubMed

Diseases are a potential threat to global food security but plants have evolved an extensive array of methodologies to cope with the invading pathogens. Non-host resistance and quantitative resistance are broad spectrum forms of resistance, and all kinds of resistances are controlled by extremely diverse genes called "R-genes". R-genes follow different mechanisms to defend plants and PAMP-induced defenses in susceptible host plants are referred to as basal resistance. Genetic and phenotypic diversity are vital in maize (Zea mays L.); as such, genome wide association study (GWAS) along with certain other methodologies can explore the maximum means of genetic diversity. Exploring the complete genetic architecture to manipulate maize genetically reduces the losses from hazardous diseases. Genomic studies can reveal the interaction between different genes and their pathways. By confirming the specific role of these genes and protein-protein interaction (proteomics) via advanced molecular and bioinformatics tools, we can shed a light on the most complicated and abstruse phenomena of resistance. PMID:22333113

Ali, Farhan; Yan, Jianbing

2012-03-01

52

Complete genome sequence of a novel badnavirus, banana streak IM virus  

Microsoft Academic Search

In 1999, banana streak disease outbreaks occurred at two locations in Australia in new banana hybrids that were being screened\\u000a for fusarium wilt resistance. Two different badnaviruses, banana streak GF virus and a newly discovered virus called banana\\u000a streak IM virus (BSIMV), were detected in these plants. The complete nucleotide sequence of the BSIMV genome was determined\\u000a and comprised 7768

Andrew D. W. GeeringJudith; Judith N. Parry; John E. Thomas

2011-01-01

53

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

PubMed Central

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

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

2013-01-01

54

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

55

Selection mapping of loci for quantitative disease resistance in a diverse maize population.  

PubMed

The selection response of a complex maize population improved primarily for quantitative disease resistance to northern leaf blight (NLB) and secondarily for common rust resistance and agronomic phenotypes was investigated at the molecular genetic level. A tiered marker analysis with 151 simple sequence repeat (SSR) markers in 90 individuals of the population indicated that on average six alleles per locus were available for selection. An improved test statistic for selection mapping was developed, in which quantitative trait loci (QTL) are identified through the analysis of allele-frequency shifts at mapped multiallelic loci over generations of selection. After correcting for the multiple tests performed, 25 SSR loci showed evidence of selection. Many of the putatively selected loci were unlinked and dispersed across the genome, which was consistent with the diffuse distribution of previously published QTL for NLB resistance. Compelling evidence for selection was found on maize chromosome 8, where several putatively selected loci colocalized with published NLB QTL and a race-specific resistance gene. Analysis of F2 populations derived from the selection mapping population suggested that multiple linked loci in this chromosomal segment were, in part, responsible for the selection response for quantitative resistance to NLB. PMID:18723892

Wisser, Randall J; Murray, Seth C; Kolkman, Judith M; Ceballos, Hernán; Nelson, Rebecca J

2008-08-24

56

Transmission studies with Cassava brown streak Uganda virus ( Potyviridae: Ipomovirus) and its interaction with abiotic and biotic factors in Nicotiana benthamiana  

Microsoft Academic Search

Cassava brown streak disease (CBSD), caused by two distinct species, Cassava brown streak Uganda virus (CBSUV) and Cassava brown streak virus (CBSV), is a major constraint to cassava (Manihot esculenta Crantz) production in Africa. Absence of infectious clones of CBSUV or CBSV and the lack of efficient means of mechanical transmission of CBSD has hampered laboratory studies of this disease.

Emmanuel Ogwok; Basavaprabhu L. Patil; Titus Alicai; Claude M. Fauquet

2010-01-01

57

Mapping resistance quantitative trait Loci for three foliar diseases in a maize recombinant inbred line population-evidence for multiple disease resistance?  

PubMed

Southern leaf blight (SLB), gray leaf spot (GLS), and northern leaf blight (NLB) are all important foliar diseases impacting maize production. The objectives of this study were to identify quantitative trait loci (QTL) for resistance to these diseases in a maize recombinant inbred line (RIL) population derived from a cross between maize lines Ki14 and B73, and to evaluate the evidence for the presence genes or loci conferring multiple disease resistance (MDR). Each disease was scored in multiple separate trials. Highly significant correlations between the resistances and the three diseases were found. The highest correlation was identified between SLB and GLS resistance (r = 0.62). Correlations between resistance to each of the diseases and time to flowering were also highly significant. Nine, eight, and six QTL were identified for SLB, GLS, and NLB resistance, respectively. QTL for all three diseases colocalized in bin 1.06, while QTL colocalizing for two of the three diseases were identified in bins 1.08 to 1.09, 2.02/2.03, 3.04/3.05, 8.05, and 10.05. QTL for time to flowering were also identified at four of these six loci (bins 1.06, 3.04/3.05, 8.05, and 10.05). No disease resistance QTL was identified at the largest-effect QTL for flowering time in bin 10.03. PMID:19968551

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

2010-01-01

58

Streak tube characterization for transient recording  

Microsoft Academic Search

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

T. B. Jennings; R. W. Olsen

1987-01-01

59

Gated SIT vidicon streak tube  

SciTech Connect

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

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

1985-01-01

60

Promoters for pregenomic RNA of banana streak badnavirus are active for transgene expression in monocot and dicot plants  

Microsoft Academic Search

Two putative promoters from Australian banana streak badnavirus (BSV) isolates were analysed for activity in different plant species. In transient expression systems the My (2105 bp) and Cv (1322 bp) fragments were both shown to have promoter activity in a wide range of plant species including monocots (maize, barley, banana, millet, wheat, sorghum), dicots (tobacco, canola, sunflower, Nicotiana benthamiana, tipu

Peer M. Schenk; Tony Remans; László Sági; Adrian R. Elliott; Ralf G. Dietzgen; Rony Swennen; Paul R. Ebert; Christopher P. L. Grof; John M. Manners

2001-01-01

61

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

Microsoft Academic Search

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

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

2001-01-01

62

Dark streaks on talus slopes, Mars  

NASA Astrophysics Data System (ADS)

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

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

1984-04-01

63

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

PubMed

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 known resistance to multiple diseases. Chromosomal regions ("bins"; n = 39) associated with multiple disease resistance (MDR) were targeted based on a consensus map of disease QTLs in maize. We generated HIFs segregating for the targeted loci but isogenic at ~97% of the genome. To test the hypothesis that CML52 and DK888 alleles at MDR hotspots condition broad-spectrum resistance, HIFs and derived NILs were tested for resistance to northern leaf blight (NLB), southern leaf blight (SLB), gray leaf spot (GLS), anthracnose leaf blight (ALB), anthracnose stalk rot (ASR), common rust, common smut, and Stewart's wilt. Four NLB QTLs, two ASR QTLs, and one Stewart's wilt QTL were identified. In parallel, a population of 196 recombinant inbred lines (RILs) derived from B73 × CML52 was evaluated for resistance to NLB, GLS, SLB, and ASR. The QTLs mapped (four for NLB, five for SLB, two for GLS, and two for ASR) mostly corresponded to those found using the NILs. Combining HIF- and RIL-based analyses, we discovered two disease QTLs at which CML52 alleles were favorable for more than one disease. A QTL in bin 1.06-1.07 conferred resistance to NLB and Stewart's wilt, and a QTL in 6.05 conferred resistance to NLB and ASR. PMID:21526397

Chung, Chia-Lin; Poland, Jesse; Kump, Kristen; Benson, Jacqueline; Longfellow, Joy; Walsh, Ellie; Balint-Kurti, Peter; Nelson, Rebecca

2011-04-28

64

Numerical simulation of attosecond nanoplasmonic streaking  

NASA Astrophysics Data System (ADS)

The characterization of the temporal profile of plasmonic fields is important both from the fundamental point of view and for potential applications in ultrafast nanoplasmonics. It has been proposed by Stockman et al (2007 Nat. Photonics 1 539) that the plasmonic electric field can be directly measured by the attosecond streaking technique; however, streaking from nanoplasmonic fields differs from streaking in the gas phase because of the field localization on the nanoscale. To understand streaking in this new regime, we have performed numerical simulations of attosecond streaking from fields localized in nanoantennas. In this paper, we present simulated streaked spectra for realistic experimental conditions and discuss the plasmonic field reconstruction from these spectra. We show that under certain circumstances when spatial averaging is included, a robust electric field reconstruction is possible.

Skopalová, E.; Lei, D. Y.; Witting, T.; Arrell, C.; Frank, F.; Sonnefraud, Y.; Maier, S. A.; Tisch, J. W. G.; Marangos, J. P.

2011-08-01

65

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

66

Streak tube characterization for transient recording  

SciTech Connect

This paper describes the methods used by EG and G Energy Measurements to characterize a streak tube. Both radiometric (QE, uniformity, gain, linearity, extinction ratio, opacity) and resolution (static, spatial, and temporal) tests are covered. The significance of these measurements with respect to streak camera applications is discussed. The results of the measurements on a streak tube designed and built by EG and G Amador Valley Operations are included as an illustration. 6 refs.

Jennings, T.B.; Olsen, R.W.

1987-01-01

67

Streak Breakdown Leading to Wall Turbulence  

NASA Astrophysics Data System (ADS)

Growth and eventual breakdown of near-wall low-speed streaks are responsible for generating and then sustaining wall turbulence structures in wall-bounded shear flows. This paper reviews our two experiments which are well designed to follow up the development of streak breakdown up to first appearance of wall turbulence structures. We first focus on evolution of subharmonic streak instability into wall turbulence in a spanwise periodic laminar streak flow. When the subharmonic mode grows beyond the nonlinear saturation stage of subharmonic instability, quasi-streamwise vortices developing along the neighboring low-speed streaks strongly interact with each other in each cycle, causing horseshoe vortex structures to develop in a staggered array. Next we focus on streak breakdown caused by high-intensity background turbulence. Low-speed streaks are generated in a quasi-laminar boundary layer containing high-intensity turbulent vortices. In this case, the streak breakdown is not caused by linear streak instability but by transient disturbance growth.

Asai, M.

2011-09-01

68

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

PubMed Central

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

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

2013-01-01

69

Notes on the IMACON 500 streak camera system  

SciTech Connect

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

Clendenin, J.E.

1985-01-31

70

Laminar streaks with spanwise wall forcing  

NASA Astrophysics Data System (ADS)

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

Ricco, Pierre

2011-06-01

71

Simultaneous virus-specific detection of the two cassava brown streak-associated viruses by RT-PCR reveals wide distribution in East Africa, mixed infections, and infections in Manihot glaziovii  

Microsoft Academic Search

The expanding cassava brown streak disease (CBSD) epidemic in East Africa is caused by two ipomoviruses (genus Ipomovirus; Potyviridae), namely, Cassava brown streak virus (CBSV), and Ugandan cassava brown streak virus (UCBSV) that was described recently. A reverse transcription polymerase chain reaction (RT-PCR) based diagnostic method was developed in this study for simultaneous virus-specific detection of the two viruses. Results

D. R. Mbanzibwa; Y. P. Tian; A. K. Tugume; S. B. Mukasa; F. Tairo; S. Kyamanywa; A. Kullaya; J. P. T. Valkonen

2011-01-01

72

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

73

Etiology of root and stalk rots of maize in north Queensland. Disease development and associated fungi  

Microsoft Academic Search

The etiology and development of mesocotyl, root and stalk rots of maize on the Atherton Tableland in north Queensland were\\u000a investigated in two seasons. The identities and relative isolation frequencies of fungi from the mesocotyls, roots and stalks\\u000a were determined at different stages of growth at two sites. Mesocotyl rot was first observed ca. 40 days after planting, and by

M. D. Ramsey

1990-01-01

74

Transglutaminase treatment of wheat and maize prolamins of bread increases the serum IgA reactivity of celiac disease patients.  

PubMed

Celiac disease (CD) is mediated by IgA antibodies to wheat gliadins and tissue transglutaminase (tTG). As tTG is homologous to microbial transglutaminase (mTG) used to improve foodstuff quality, it could elicit the immune response of celiac patients. This study evaluated the reactivity of IgA of celiac patients to prolamins of wheat and gluten-free (maize and rice flours) breads mTG-treated or not. Prolamins extracted from wheat and gluten-free breads were analyzed by ELISA and immunodetected on membranes with individual or pooled sera from nine celiac patients recently diagnosed. Sera pool IgA titers were higher against prolamins of mTG-treated wheat or gluten-free breads than against mTG-untreated, mainly due to two individual patients' sera. The electrophoretic pattern of gluten-free bread prolamins was changed by the mTG treatment, and a new 31000 band originated in maize was recognized by three CD patients' IgA. PMID:18193828

Cabrera-Chávez, Francisco; Rouzaud-Sández, Ofelia; Sotelo-Cruz, Norberto; Calderón de la Barca, Ana M

2008-01-15

75

Neutron Streak Camera Electron Gun Design.  

National Technical Information Service (NTIS)

Representative values for electrode voltages, time compensation, and transmission efficiency are obtained by computer simulation for a preliminary design of an electron gun to be used in a neutron streak camera application. The calculations indicate a tim...

E. R. Close J. S. Colonias

1984-01-01

76

The streak camera system in HLS  

NASA Astrophysics Data System (ADS)

HLS (Hefei Light Source) is an 800MeV electron storage ring in National Synchrotron Radiation Laboratory. To measure electron bunch for Synchrotron Radiation and to understand the machine behavior during the operation, the streak camera system has been built in HLS storage ring on April 2006. The streak camera system mainly consists of the synchrotron light extracting optics setup and OPTOSCOPE the streak camera. The light extracting optics setup consists of the light extracting path and the optics imaging system. The OPTOSCOPE the streak camera consists of a camera main unit with input optics, a remote control unit, a CCD camera readout unit, a power supply unit, a Personal Computer with a frame grabber interface card and ARP-Optoscope software package. The streak camera system operates with synchroscan sweep mode or dual time base sweep mode. Controlling the streak camera and image acquisition is made by the ARP-Optoscope software. At present, the system is used to measure the bunch length and the bunch interval in HLS storage ring. Some typical results of the measurement are given.

Wang, J. G.; Sun, B. G.; Cao, Y.; Wang, B. Y.

2007-01-01

77

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

PubMed

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 susceptible, its sister lines NC292 and NC330 are both SLB resistant. Previously, we identified the 12 introgressions from NC250P that differentiate NC292 and NC330 from B73. The goals of this study were to determine the effects of each introgression on resistance to SLB and to two other foliar fungal diseases of maize, northern leaf blight and gray leaf spot. This was achieved by generating and testing a set of near isogenic lines carry single or combinations of just two or three introgressions in a B73 background. Introgressions 3B, 6A, and 9B (bins 3.03-3.04, 6.01, and 9.02-9.03) all conferred significant levels of SLB resistance in the field. Introgression 6A was the only introgression that had a significant effect on juvenile plant resistance to SLB. Introgressions 6A and 9B conferred resistance to multiple diseases. PMID:21997760

Belcher, Araby R; Zwonitzer, John C; Santa Cruz, Jose; Krakowsky, Mathew D; Chung, Chia-Lin; Nelson, Rebecca; Arellano, Consuelo; Balint-Kurti, Peter J

2011-10-14

78

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

79

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.

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

80

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

Microsoft Academic Search

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

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

2011-01-01

81

First Satellite Laser Echoes Recorded on the Streak Camera.  

National Technical Information Service (NTIS)

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 s...

K. Hamal I. Prochazka G. Kirchner F. Koidl

1993-01-01

82

Bichromatic particle streak velocimetry bPSV  

NASA Astrophysics Data System (ADS)

We propose a novel technique for three-dimensional three-component (3D3C) interfacial flow measurement. It is based on the particle streak velocimetry principle. A relatively long integration time of the camera is used for capturing the movement of tracer particles as streaks on the sensor. The velocity along these streaks is extracted by periodically changing the illumination using a known pattern. A dye with different absorption characteristics in two distinct wavelengths is used to color the fluid. The depth of particles relative to the fluid interface can then be computed from their intensities when illuminated with light sources at those two different wavelengths. Hence, from our approach, a bichromatic, periodical illumination together with an image processing routine for precisely extracting particle streak features is used for measuring 3D3C fluid flow with a single camera. The technique is applied to measuring turbulent Rayleigh-Bénard convection at the free air--water interface. Using Lagrangian statistics, we are able to demonstrate a clear transition from the Batchelor regime to the Richardson regime, both of which were postulated for isotropic turbulence. The relative error of the velocity extraction of our new technique was found to be below 0.5 %.

Voss, Björn; Stapf, Julian; Berthe, André; Garbe, Christoph S.

2012-11-01

83

A SIGHT RECORD OF A STREAKED SHEARWATER  

Microsoft Academic Search

On 13 September 1996, while conducting surveys for marine mammals and seabirds aboard the NOAA ship McArthur about 57 kilometers off the southern Oregon coast, we found a Streaked Shearwater (Calonectris leucomelas), a species familiar to both Force and Rowlett. The bird was seen at 08:40 in a large mixed feeding flock over Heceta Bank. Lane County, Oregon (43 ø

1999-01-01

84

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

85

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

86

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

87

High-spatial-resolution streak image tube  

Microsoft Academic Search

A new streak tube was designed to provide improved spatial resolution across a large-diameter photocathode to obtain more spatial information. The first version of the tube did not employ an accelerator electrode. Tube design goals were achieved when operating at 30 kV. Spatial resolutions of 19 line pairs per millimeter (lp\\/mm) or better were measured across a 1-in.-diameter photocathode at

C. K. Hinrichs; R. W. Olsen

1985-01-01

88

First report of bacterial streak of fennel (Foeniculum vulgare) in California caused by Pseudomonas syringae pv. apii  

Technology Transfer Automated Retrieval System (TEKTRAN)

A new bacterial streak disease appeared on fennel leaves, stems and bulbs grown in Salinas California production fields. Initial symptoms consisted of small black lesions on stems that spread down the stem to the bulbs and up the stem to leaves as the disease progressed. The disease rendered the pl...

89

Rapid, continuous streaking of tremor in Cascadia  

NASA Astrophysics Data System (ADS)

Nonvolcanic tremor is a recently discovered weak seismic signal associated with slow slip on a fault plane and has potential to answer many questions about how faults move. Its spatiotemporal distribution, however, is complex and varies over different time scales, and the causal physical mechanisms remain unclear. Here we use a beam backprojection method to show rapid, continuous, slip-parallel streaking of tremor over time scales of several minutes to an hour during the May 2008 episodic tremor and slip event in the Cascadia subduction zone. The streaks propagate across distances up to 65 km, primarily parallel to the slip direction of the subduction zone, both updip and downdip at velocities ranging from 30 to 200 km/h. We explore mainly two models that may explain such continuous tremor streaking. The first involves interaction of slowly migrating creep front with slip-parallel linear structures on the fault. The second is pressure-driven fluid flow through structurally controlled conduits on the fault. Both can be consistent with the observed propagation velocities and geometries, although the second one requires unlikely condition. In addition, we put this new observation in the context of the overall variability of tremor behavior observed over different time scales.

Ghosh, Abhijit; Vidale, John E.; Sweet, Justin R.; Creager, Kenneth C.; Wech, Aaron G.; Houston, Heidi; Brodsky, Emily E.

2010-12-01

90

Understanding baseball team standings and streaks  

NASA Astrophysics Data System (ADS)

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

Sire, C.; Redner, S.

2009-02-01

91

Opticla and X-Ray Streak Camera Gain Measurements  

SciTech Connect

Measurements of streak camera gain as the number of CCD (charge-coupled-device) electrons recorded per single-electron events hitting the streak tube phosphor are presented. The CCD is fiber optically coupled to the streak tube output; there is no image intensifier in the system. The gain is measured from the signal-to-noise (SNR) ratio of the recorded photoelectrons. This technique allows us to verify that the photoelectron SNR follows Poisson statistics and to establish the linear dynamic range.

Ghosh, S.; Boni, R.; Jaanimagi, P.A.

2004-10-19

92

Compressible laminar streaks with wall suction  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

93

Association mapping of quantitative trait loci responsible for resistance to Bacterial Leaf Streak and Spot Blotch in spring wheat landraces  

Technology Transfer Automated Retrieval System (TEKTRAN)

Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, and spot blotch (SB), caused by Cochliobolus sativus are two major diseases of wheat (Triticum aestivum L.). Planting resistant cultivars is the best approach to manage these diseases and identifying new sources of resistan...

94

Transmission of Rice Black-Streaked Dwarf Virus from Frozen Infected Leaves to Healthy Rice Plants by Small Brown Planthopper ( Laodelphax striatellus)  

Microsoft Academic Search

In order to preserve virus for identifying the resistance of rice varieties against rice black-streaked dwarf disease, a simple and reliable method was developed, through which virus-free small brown planthopper (SBPH) acquired rice black-streaked dwarf virus (RBSDV) from frozen infected leaves and the virus was transmitted to healthy rice plants. The experimental results showed that SBPH could obtain RBSDV from

Tong ZHOU; Li-juan WU; Ying WANG; Zhao-bang CHENG; Ying-hua JI; Yong-jian FAN; Yi-jun ZHOU

2011-01-01

95

Genetic analysis of resistance to bacterial leaf streak caused by Xanthomonas campestris pv. undulosa in bread wheat  

Microsoft Academic Search

The inheritance of resistance to bacterial leaf streak or black chaff of wheat was studied under field conditions, with an artificial epidemic of Xanthomonas campestris pv. undulosa. A complete series of crosses between five parents, differing in reaction to X. c. pv. undulosa, was generated. Disease was recorded at two different stages of growth. No evidence of cytoplasmic effect was

Etienne Duveiller; Maarten van Ginkel; Marja Thijssen

1992-01-01

96

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

SciTech Connect

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

Not Available

1993-11-20

97

The formation of streak defects on anodized aluminum extrusions  

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

98

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

99

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

100

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

PubMed

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. PMID:19291988

Imai, Kuniahru; Ikeda, Mitsuru; Enchi, Yukihiro; Niimi, Takanaga

2009-02-01

101

Note: X-ray streak camera sweep speed calibration.  

PubMed

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

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

2010-05-01

102

Note: X-ray streak camera sweep speed calibration  

SciTech Connect

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

Zhu Tuo; Yang Jiamin; Deng Bo; Wang Zhebin [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China); National Key Laboratory of High Temperature and Density Plasmas, Mianyang 621900 (China); Yang Dong; He Xiaoan [Research Center of Laser Fusion, China Academy of Engineering Physics, P.O. Box 919-986, Mianyang 621900 (China)

2010-05-15

103

Ultrafast x-ray imaging with sliced sampling streak cameras  

SciTech Connect

The ultrafast imaging methods in sliced sampling streak cameras are investigated. It is shown that the sampling-image x-ray streak camera has potential advantages in highly time-resolved and space-resolved imaging for imploded core plasmas. An optimized sampling method is presented to acquire two-dimensional spatial resolutions {<=}10 {mu}m and temporal resolution {approx}10 ps, within a field of view {approx}100 {mu}m and a time range {approx}100 ps.

Huang, T.X.; Nakai, M.; Shiraga, H.; Azechi, H.; Huang, T.X.; Ding, Y.K.; Zheng, Z.J. [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-0871 (Japan); Research Center of Laser Fusion, Mianyang 621900 (China)

2006-02-15

104

Shielding a streak camera from hard x rays  

SciTech Connect

The targets used in the hot halfraum campaign at OMEGA create many hot electrons, which result in a large flux of hard x rays. The hard x rays produce a high background in the streak camera. The background was significantly reduced by wrapping the streak camera with a high-Z material; in this case, 1/8 in. of Pb. The large hard x-ray flux also adds noise to images from framing cameras which use charge-coupled devices.

Schneider, M.B.; Sorce, C.; Loughman, K.; Emig, J.; Bruns, C.; Back, C.; Bell, P.M.; Compton, S.; Hargrove, D.; Holder, J.P.; Landen, O.L.; Perry, T.S.; Shepherd, R.; Young, B.K. [Lawrence Livermore National Laboratory, P.O. Box 808, L-472 Livermore, California 94550 (United States)

2004-10-01

105

Semiclassical model for attosecond angular streaking.  

PubMed

Attosecond angular streaking is a new technique to achieve unsurpassed time accuracy of only a few attoseconds. Recently this has been successfully used to set an upper limit on the electron tunneling delay time in strong laser field ionization. The measurement technique can be modeled with either the time-dependent Schrödinger equation (TDSE) or a more simple semiclassical approach that describes the process in two steps in analogy to the three-step model in high harmonic generation (HHG): step one is the tunnel ionization and step two is the classical motion in the strong laser field. Here we describe in detail a semiclassical model which is based on the ADK theory for the tunneling step, with subsequent classical propagation of the electron in the laser field. We take into account different ellipticities of the laser field and a possible wavelength-dependent ellipticity that is typically observed for pulses in the two-optical-cycle regime. This semiclassical model shows excellent agreement with the experimental result. PMID:20721150

Smolarski, M; Eckle, P; Keller, U; Dörner, R

2010-08-16

106

Tobacco streak virus isolated from lettuce.  

PubMed

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

Abtahi, F S; Khodai Motlagh, M

2009-05-01

107

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

PubMed Central

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

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

2011-01-01

108

RNAi-mediated resistance to Cassava brown streak Uganda virus in transgenic cassava.  

PubMed

Cassava brown streak disease (CBSD), caused by Cassava brown streak Uganda virus (CBSUV) and Cassava brown streak virus (CBSV), is of new epidemic importance to cassava (Manihot esculenta Crantz) production in East Africa, and an emerging threat to the crop in Central and West Africa. This study demonstrates that at least one of these two ipomoviruses, CBSUV, can be efficiently controlled using RNA interference (RNAi) technology in cassava. An RNAi construct targeting the near full-length coat protein (FL-CP) of CBSUV was expressed constitutively as a hairpin construct in cassava. Transgenic cassava lines expressing small interfering RNAs (siRNAs) against this sequence showed 100% resistance to CBSUV across replicated graft inoculation experiments. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis showed the presence of CBSUV in leaves and some tuberous roots from challenged controls, but not in the same tissues from transgenic plants. This is the first demonstration of RNAi-mediated resistance to the ipomovirus CBSUV in cassava. PMID:21726367

Yadav, Jitender S; Ogwok, Emmanuel; Wagaba, Henry; Patil, Basavaprabhu L; Bagewadi, Basavaraj; Alicai, Titus; Gaitan-Solis, Eliana; Taylor, Nigel J; Fauquet, Claude M

2011-02-17

109

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

PubMed Central

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

Lee, Ji Woong; Shin, Jae Pil

2011-01-01

110

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...

111

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.

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

2012-01-01

112

Widespread occurrence and diversity of Cassava brown streak virus (Potyviridae: Ipomovirus) in Tanzania.  

PubMed

Cassava brown streak disease (CBSD) has been a problem in Tanzania since 1936. Existing literature indicated limited distribution of the disease to low altitudes, usually <100 m above sea level, but the current geographical distribution of the disease was not known. Whether a single or many strains for the virus exist in Tanzania had not been reported to date. In this study, CBSD was recorded from sea level to ?1,800 m above sea level. In total, 2,730 cassava plants were assessed for CBSD leaf symptoms in 91 fields and root symptoms were assessed at 81 sites. A sample was taken from each site for laboratory screening for Cassava brown streak virus (CBSV). CBSD mean foliar and root incidences were 38 and 36%, respectively. Reverse-transcription polymerase chain reaction of a partial 3'-terminal coat protein (CP) region of CBSV indicated the presence of CBSV in 67 of the 91 (73%) samples. Forty-three amplicons were sequenced, and phylogenetic comparisons with nucleotide sequences from GenBank (National Center for Biotechnology Information database) suggested that one major clade of CBSV primarily exists in Tanzania. However, there was nucleotide sequence divergence of up to 19% among the 42 isolates. In all, 42 of the 43 sequences had 80 to 100% nucleotide identity with 6 previously reported CP-CBSV sequences (from Mozambique and Tanzania). In total, 13 of 42 isolates had <80% nucleotide identities with three previously reported Ugandan CBSV sequences. One isolate, FJ687177, shared <78% sequence identity with the other Tanzanian sequences but was closely related (93%) to Ugandan isolates. It is likely that isolate FJ687177 may belong to a less widely distributed recently described species (clade 2) of CBSV, named Ugandan cassava brown streak virus (UCBSV). PMID:21916624

Rwegasira, G M; Momanyi, G; Rey, M E C; Kahwa, G; Legg, J P

2011-10-01

113

Attosecond streaking in a nano-plasmonic field  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

114

Streak Camera Performance with Large-Format CCD Readout  

SciTech Connect

The ICF program at Livermore has a large inventory of optical streak cameras that were built in the 1970s and 1980s. The cameras include micro-channel plate image-intensifier tubes (IIT) that provide signal amplification and early lens-coupled CCD readouts. Today, these cameras are still very functional, but some replacement parts such as the original streak tube, CCD, and IIT are scarce and obsolete. This article describes recent efforts to improve the performance of these cameras using today's advanced CCD readout technologies. Very sensitive, large-format CCD arrays with efficient fiber-optic input faceplates are now available for direct coupling with the streak tube. Measurements of camera performance characteristics including linearity, spatial and temporal resolution, line-spread function, contrast transfer ratio (CTR), and dynamic range have been made for several different camera configurations: CCD coupled directly to the streak tube, CCD directly coupled to the IIT, and the original configuration with a smaller CCD lens coupled to the IIT output. Spatial resolution (limiting visual) with and without the IIT is 8 and 20 lp/mm, respectively, for photocathode current density up to 25% of the Child-Langmuir (C-L) space-charge limit. Temporal resolution (fwhm) deteriorates by about 20% when the cathode current density reaches 10% of the C-L space charge limit. Streak tube operation with large average tube current was observed by illuminating the entire slit region through a Ronchi ruling and measuring the CTR. Sensitivity (CCD electrons per streak tube photoelectron) for the various configurations ranged from 7.5 to 2,700 with read noise of 7.5 to 10.5 electrons. Optimum spatial resolution is achieved when the IIT is removed. Maximum dynamic range requires a configuration where a single photoelectron from the photocathode produces a signal that is 3 to 5 times the read noise.

Lerche, R A; Andrews, D S; Bell, P M; Griffith, R L; McDonald, J W; Torres, P III; Vergel de Dios, G

2003-07-08

115

Wheat streak mosaic virus-Structural parameters for a Potyvirus  

SciTech Connect

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

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

2005-09-15

116

Formation and reduction of streak artefacts in electron tomography.  

PubMed

We have analysed the formation of streak artefacts in the reconstruction based on the filtered back projection algorithm in electron tomography (ET) and accordingly applied an adaptive interpolation technique to artefact reduction. In the adaptive interpolation to recover the missing information, the edge positions in a projection curve were tracked to reduce the interpolation error. A simulation was used to demonstrate the effectiveness of the artefact reduction. Furthermore, image reconstruction of integrated circuit specimens in the ET experiments with the ultra-high voltage electron microscope show that the strong streak artefacts can be reduced effectively by our artefact reduction technique. PMID:20579270

Cao, M; Zhang, H-B; Lu, Y; Nishi, R; Takaoka, A

2010-07-01

117

Attosecond Streaking Enables the Measurement of Quantum Phase  

SciTech Connect

Attosecond streaking, as a measurement technique, was originally conceived as a means to characterize attosecond light pulses, which is a good approximation if the relevant transition matrix elements are approximately constant within the bandwidth of the light pulse. Our analysis of attosecond streaking measurements on systems with a complex response to the photoionizing pulse reveals the relation between the momentum-space wave function of the outgoing electron and the result of conventional retrieval algorithms. This finding enables the measurement of the quantum phase associated with bound-continuum transitions.

Yakovlev, V. S.; Gagnon, J.; Krausz, F. [Department fuer Physik, Ludwig-Maximilians-Universitaet, Am Coulombwall 1, Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Karpowicz, N. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany)

2010-08-13

118

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

119

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

120

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

121

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

Microsoft Academic Search

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

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

2008-01-01

122

Reference genes for reliable potyvirus quantitation in cassava and analysis of Cassava brown streak virus load in host varieties  

Microsoft Academic Search

A reliable method for detection and quantitation of viruses associated with cassava brown streak disease (CBSD) is essential to determine their presence in material used for field propagation as well as for precise evaluation of CBSD resistance in the cassava germplasm. Quantitative RT-PCR (RT-qPCR) is a well-established method for precise quantitation of viral RNA amount in infected tissues. The method

Isabel Moreno; Wilhelm Gruissem; Hervé Vanderschuren

2011-01-01

123

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

124

Attosecond streaking experiments on atoms: quantum theory versus simple model  

Microsoft Academic Search

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

A. K. Kazansky; N. M. Kabachnik

2006-01-01

125

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

126

Presumed ocular histoplasmosis syndrome and linear streak lesions  

Microsoft Academic Search

Five cases of subretinal neovascular membranes in the macula associated with punched out chorioretinal scars and linear streaks were seen in five Dutch patients. Clinically the fundus lesions are consistent with those of presumed ocular histoplasmosis syndrome (POHS) seen in the United States of America. Cutaneous serological testing for histoplasmin reactivity was negative in the three patients tested. Of special

F G Bottoni; A F Deutman; A L Aandekerk

1989-01-01

127

Improved approach to characterizing and presenting streak camera performance  

SciTech Connect

The performance of a streak camera recording system is strongly linked to the technique used to amplify, detect and quantify the streaked image. At the Lawrence Livermore National Laboratory (LLNL) streak camera images have been recorded both on film and by fiber-optically coupling to charge-coupled devices (CCD's). During the development of a new process for recording these images (lens coupling the image onto a cooled CCD) the definitions of important performance characteristics such as resolution and dynamic range were re-examined. As a result of this development, these performance characteristics are now presented to the streak camera user in a more useful format than in the past. This paper describes how these techniques are used within the Laser Fusion Program at LLNL. The system resolution is presented as a modulation transfer function, including the seldom reported effects that flare and light scattering have at low spatial frequencies. Data are presented such that a user can adjust image intensifier gain and pixel averaging to optimize the useful dynamic range in any particular application.

Wiedwald, J.D.; Jones, B.A.

1985-07-15

128

Streak Camera Performance with Large-Format CCD Readout.  

National Technical Information Service (NTIS)

The ICF program at Livermore has a large inventory of optical streak cameras that were built in the 1970s and 1980s. The cameras include micro-channel plate image-intensifier tubes (IIT) that provide signal amplification and early lens-coupled CCD readout...

R. A. Lerche D. S. Andrews P. M. Bell R. L. Griffith J. W. McDonald

2003-01-01

129

Movement and commitment of primitive streak precardiac cells during cardiogenesis.  

PubMed

Fate maps are required to address questions about the commitment and differentiation of precardiac cells. Here, we report a detailed study of the precardiac cells located at the level of the primitive streak, employing different experiments with a variety of techniques combining double transplantations, microinjections and immunocytochemistry. Most cells of the more rostral segments of the primitive streak were found to contribute cells to the endodermal layer, adjacent to precardiac mesodermal cells of the heart forming region whose provenance was in the immediately more caudal segments of the primitive streak. We established a close spatio-temporal relationship between the two cell layers and the expression of their specific cardiac markers (cNkx-2.5, Bmp2, Cripto, Usmaar, dHand, GATA4, Pitx2, Hex, Fgf8, AMHC1 and VMHC1). We also analyzed the ability of precardiac cells to differentiate when they are transplanted to ectopic locations or are subjected to the influence of the organizer. We propose that the precardiac cells of the primitive streak form at least two groups with different significance. One, regulated by mediation of the organizer, is located preferentially in the more rostral region of the primitive streak. It consists of the prospective cells of the endoderm layer, with a hierarchic pattern of expression of different genes characterized by its capacity for induction and regulation of a second group of cells. This second group is located preferentially in the more caudal segments, and is fated to form the precardiac mesoderm, whose differentiation would be characterized by the expression of various specific genes. PMID:19247942

Lopez-Sanchez, Carmen; Garcia-Masa, Natividad; Gañan, Carlos M; Garcia-Martinez, Virginio

2009-01-01

130

The symptom and genetic diversity of cassava brown streak viruses infecting cassava in East Africa.  

PubMed

The genetic and symptom diversity of six virus isolates causing cassava brown streak disease (CBSD) in the endemic (Kenya, Mozambique, and Tanzania) and the recently affected epidemic areas (Uganda) of eastern Africa was studied. Five cassava varieties; Albert, Colombian, Ebwanateraka, TMS60444 (all susceptible) and Kiroba (tolerant) were graft inoculated with each isolate. Based on a number of parameters including the severity of leaf and root symptoms, and the extent of virus transmission by grafting, the viruses were classified as either severe or relatively mild. These results were further confirmed by the mechanical inoculation of 13 herbaceous hosts in which the virulent isolates caused plant death in Nicotiana clevelandii and N. benthamiana whereas the milder isolates did not. Phylogenetic analysis of complete coat protein gene sequences of these isolates together with sequences obtained from 14 other field-collected samples from Kenya and Zanzibar, and reference sequences grouped them into two distinct clusters, representing the two species of cassava brown streak viruses. Put together, these results did not suggest the association of a hypervirulent form of the virus with the current CBSD epidemic in Uganda. Identification of the severe and milder isolates, however, has further implications for disease management and quarantine requirements. PMID:22454639

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

2012-02-21

131

Investigation of other operating points for the RCA streak tube in the Lawrence Livermore National Laboratory streak camera  

SciTech Connect

The soft x-ray streak camera uses the RCA C73435 streak tube body fitted with a removable x-ray cathode. The front of the streak tube is exposed to the vacuum of an experimental chamber, which is not entirely under the control of a streak camera operator. Occasionally, the vacuum becomes poor enough to cause corona and arcing from the cathode to the chamber wall. The corona problem is more difficult because the dimensions of the x-ray camera body are smaller than for the optical camera body. Therefore, we investigated the effects on camera performance of decreasing the accelerating voltage at the cathode from the customary 17 kV. Several operating points were evaluated and 12 kV cathode-to-anode with 5 kV cathode-to-grid were selected for more detailed investigation. Transverse spatial resolution and dynamic range were found to be essentially the same as at our normal operating point of 17 kV for the cathode and 2500 V on the grid. Magnification, sweep linearity and absolute sensitivity changed as expected. In the course of the investigation, we measured the dynamic range with our CCD readout system. The effect of Coulomb repulsion at the crossover point was also measured and found not to affect dynamic range.

Thomas, S.W.; Peterson, R.L.; Griffith, R.L.

1982-07-01

132

Multivariate analysis of maize disease resistances suggests a pleiotropic genetic basis and implicates a glutathione S-transferase gene  

Technology Transfer Automated Retrieval System (TEKTRAN)

Plants are attacked by pathogens representing diverse taxonomic groups, such that genes providing multiple disease resistance (MDR) would likely be under positive selection pressure. We examined the novel proposition that naturally occurring allelic variants may confer MDR. To do so, we applied a ...

133

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

PubMed Central

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

2013-01-01

134

Maize Genetic Resources  

Technology Transfer Automated Retrieval System (TEKTRAN)

This chapter describes the resources held at the Maize Genetics Cooperation • Stock Center in detail and also provides some information about the North Central Regional Plant Introduction Station (NCRPIS) in Ames, IA, Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT) in Mexico, and the N...

135

Iron Absorption from Maize  

Microsoft Academic Search

The present study was performed to measure the effect of increasing amounts of ascorbic acid on the absorption of 5 mg iron in a maize meal. 30 normal subjects were served two maize meals, one of them with ascorbic acid at different dose levels. At the dose level of 200 mg ascorbic acid there was a sixfold increase in iron

Erik Björn-Rasmussen; Leif Hallberg

1974-01-01

136

First report of Maize chlorotic mottle virus and maize (corn) lethal necrosis in Kenya  

Technology Transfer Automated Retrieval System (TEKTRAN)

In September 2011, high incidence of a new maize (Zea mays L.) disease was reported at lower elevations (1900 masl) in the Longisa division of Bomet County, Southern Rift Valley of Kenya. Later the disease was noted in Bomet Central division, spreading into the neighboring Chepalungu and Narok South...

137

Streaked x-ray microscopy of laser-fusion targets  

SciTech Connect

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

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

1982-08-01

138

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

139

Attosecond streaking experiments on atoms: quantum theory versus simple model  

Microsoft Academic Search

A new theoretical approach to the description of the attosecond streaking\\u000ameasurements of atomic photoionization is presented. It is a fully quantum\\u000amechanical description based on numerical solving of the time-dependent\\u000aSchroedinger equation which includes the atomic field as well as the fields of\\u000athe XUV and IR pulses. Also a simple semiempirical description based on sudden\\u000aapproximation is suggested

A. K. Kazansky; N. M. Kabachnik

2006-01-01

140

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

141

Visualization of Streak Lines in Liquid Metal by Neutron Radiography  

Microsoft Academic Search

Experimental results were presented to visualize streak lines in a liquid metal by neutron radiography. Lead-bismuth eutectic was used as a working fluid for both natural and forced convention flows. Tracer and dye injection methods were employed for the visualization and the tracer made of gold-cadmium intermetallic compound and the dye made of lead-bismuth-cadmium alloy were developed. It was shown

N. Takenaka; T. Fujii; A. Ono; K. Sonoda; S. Tazawa; T. Nakanii

1994-01-01

142

Choroidal neovascularization after blunt ocular trauma in angioid streaks  

PubMed Central

Background Patients with angioid streaks are prone to develop a subretinal hemorrhage after ocular injury, due to fragility of Bruch’s membrane. Objective The purpose of this study was to report a patient with angioid streaks in whom subfoveal choroidal neovascularization (CNV) developed after blunt ocular trauma. Case report A 60-year-old man was accidentally struck in the left eye with a crowbar handle while engaged in the demolition of wooden building materials in May 2011 and was initially evaluated at our hospital. Corrected visual acuity was 0.3 in the right and 1.2 in the left eye, and relative afferent pupillary defect was negative. Funduscopy revealed choroidal atrophy around the optic papillae and angioid streaks radiating from around the optic discs in both eyes. In the right eye, there was macular atrophy. In the left eye, there was a subretinal hemorrhage around the macular region. Fluorescein angiography of the left eye showed a blockage due to subretinal hemorrhage and increasing hyperfluorescent spots superior to the fovea, suggestive of extrafoveal CNV. Spectral-domain optical coherence tomography showed macular thinning in the right eye and no obvious abnormalities near the subfoveal region in the left eye. Two months later, the patient noticed decreased visual acuity in the left eye and was reevaluated. Visual acuity had decreased to 0.7, and well-defined CNV, one disc diameter in size, was presenting slightly superior to the macula, including the subfoveal region. Two weeks later, anti–vascular endothelial growth factor (anti-VEGF) antibody (bevacizumab) was injected intravitreally; the CNV then regressed, and visual acuity improved to 1.2. Conclusion Marked improvement in visual acuity with early treatment has not been reported in angioid streaks with subfoveal CNV after ocular injury. Intravitreal injection of an anti-VEGF antibody should be considered early after the diagnosis of CNV.

Kubota, Masaomi; Hayashi, Takaaki; Arai, Kota; Tsuneoka, Hiroshi

2013-01-01

143

Effect of inoculation time and point of entry on disease severity in Fusarium graminearum, Fusarium verticillioides, or Fusarium subglutinans inoculated maize ears  

Microsoft Academic Search

To determine if differences exist in the ability of three Fusarium species (F. graminearum, F. verticillioides, and F. subglutinans) to infect maize ears as the silks and kernels mature, one moderately resistant and two susceptible hybrids were inoculated at two points of entry (silk channel and kernels) in 1994 and 1995. Inoculations were conducted nine times for each part of

L. M. Reid; T. Woldemariam; X. Zhu; D. W. Stewart; A. W. Schaafsma

2002-01-01

144

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

Microsoft Academic Search

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

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

2007-01-01

145

Resolution limitations and optimization of the LLNL streak camera focus  

NASA Astrophysics Data System (ADS)

The RCA C73435 image tube is biased at voltages far from its original design in the Lawrence Livermore National Laboratory (LLNL) ultrafast (10 ps) streak camera. Its output resolution at streak camera operating potentials has been measured as a function of input slit width, incident-light wavelength, and focus-grid voltage. The temporal resolution is insensitive to focus-grid voltage for a narrow (100 micron) input slit, but is very sensitive to focus-grid voltage for a wide (2 mm) input slit. At the optimum wide-slit focus voltage, temporal resolution is insensitive to slit width. Spatial resolution is nearly independent of focus-grid voltage for values that give good temporal resolution. Both temporal and spatial resolution depend on the incident-light wavelength. Data for 1.06 micron light show significantly better focusing than for 0.53 micron light. Streak camera operation is simulated with a computer program that calculates photoelectron trajectories. Electron ray tracing describes all of the observed effects of slit width, incident-light wavelength, and focus-grid voltage on output resolution.

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

1987-09-01

146

Streaking at high energies with electrons and positrons  

SciTech Connect

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

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

2012-07-09

147

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

148

Dose-related effects of doxazosin on plasma lipids and aortic fatty streak formation in the hypercholesterolemic hamster model.  

PubMed Central

Doxazosin, an alpha 1-adrenergic inhibitor, has been shown to decrease hypertension and plasma lipids, especially total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), thus reducing certain risk factors associated with increased incidence of cardiovascular disease. One preliminary report indicated that the decrease in LDL-C in hypercholesterolemic hamsters treated with doxazosin was associated with a reduction in fatty streak formation. However, since the effects of doxazosin on plasma lipids, aortic fatty streak development, or the relationship between the two have not been studied in a dose-dependent manner, these effects were further investigated over varying doses of doxazosin (0, 1, 5, 10, and 20 mg/kg body wt/day) during a 10-week period. Doxazosin administration was associated with a dose-dependent decrease in LDL-C of 2%, 29%, 52%, and 60%, whereas the degree of fatty streak formation was reduced 11%, 45%, 76%, and 92% compared with controls, with the first statistically significant decrease for both parameters at the 10 mg/kg dose. Significant correlations between LDL-C concentrations and fatty streak area suggest that doxazosin altered aortic lipid infiltration primarily by its effect on plasma lipids. However, the 20 mg/kg dose of doxazosin significantly decreased lesion area compared with the 10 mg/kg dose without a further effect on plasma lipid concentrations. Three animals at these higher doses demonstrated no stainable lipid inclusions while maintaining plasma lipid values similar to their cohorts. These exceptions to the lipid-lesion relationship raise the possibility of additional effects of doxazosin, which may occur independent of or in concert with lipoprotein cholesterol lowering, on lesion formation. Images Figure 1 Figure 3

Foxall, T. L.; Shwaery, G. T.; Stucchi, A. F.; Nicolosi, R. J.; Wong, S. S.

1992-01-01

149

Promising genetic resources for resistance to wheat streak mosaic virus and the wheat curl mite in wheat- Thinopyrum partial amphiploids and their derivatives  

Microsoft Academic Search

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM),Aceria tosichella Keifer, is one of the most destructive viral diseases of wheat found in many wheat producing areas of the world. Host resistance is the most effective method for controlling this disease and its vector. Symptomatological analysis and enzyme-linked immunosorbent assay (ELISA) were used to characterize WSMV-resistance in

Hongjie Li; Robert L. Conner; Qin Chen; Robert J. Graf; André Laroche; F. Ahmad; A. D. Kuzyk

2005-01-01

150

Boron deficiency in maize  

Microsoft Academic Search

Boron (B) deficiency depresses wheat, barley and triticale yield through male sterility. On the basis of field responses to\\u000a B fertilization, maize (Zea mays L.) is affected by B deficiency in five continents. In a series of sand culture trials with maize subject to B0 (nil added\\u000a B) and B20 (20 ?M added B) treatments, we described how B deficiency depressed

Sittichai Lordkaew; Bernard Dell; Sansanee Jamjod; Benjavan Rerkasem

2011-01-01

151

Chemical control of maize grey leaf spot  

Microsoft Academic Search

Grey leaf spot, Cercospora zeae-maydis, has, in a relatively short period, caused significant annual grain yield losses in the maize industry of KwaZulu-Natal, South Africa. No commercial hybrids are resistant to the disease, and because alternative measures of control, such as crop rotations and tillage practices, have limited effects, fungicides are the main option available for control of the disease.

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

1997-01-01

152

First in situ investigation of a dark wind streak on Mars  

NASA Astrophysics Data System (ADS)

Prominent low-albedo wind streaks issue from embayments at the north end of Victoria crater in Meridiani Planum, the site of surface investigations by the Mars Exploration Rover Opportunity. Opportunity was sent to examine the darkest of these wind streaks and compare it to the adjacent soil in the brighter corridor between the streaks. Two nearby sites inside and outside of the streak were selected for visible and infrared remote sensing and for elemental abundance measurements and images of the microscopic soil morphology. The rover was next sent to study the interaction of the wind streak with an obstacle, a small rock near the source of the streak. Opportunity's observations suggest that the Victoria wind streaks are deposits of basaltic sand blown out of the crater from the dark dunes nestled below the crater rim, particularly at the base of the alcove leading up to the darkest streak. No local sources of sand have been identified within the Victoria crater wall rock, suggesting that the sand is supplied from outside the crater and is presently escaping its temporary topographic trap. This process presents a possible explanation for the serrated margin of Victoria crater through abrasion of the soft rock as trapped sands are blown out of the crater and carve alcoves under various seasonal winds. Some indication of the rate of activity of these wind streaks will be provided by continued monitoring of the erasure of the rover's tracks.

Geissler, P. E.; Johnson, J. R.; Sullivan, R.; Herkenhoff, K.; Mittlefehldt, D.; Fergason, R.; Ming, D.; Morris, R.; Squyres, S.; Soderblom, L.; Golombek, M.

2008-10-01

153

Evidence of recombination and genetic diversity in southern rice black-streaked dwarf virus.  

PubMed

Southern rice black-streaked dwarf virus (SRBSDV) causes one of the most serious viral diseases of rice in China and Vietnam. Sequence identities of S10, encoding the major capsid protein, were 98.0 %-100 % and 98.3 %-100 % at the nucleotide and amino acid level, respectively. Our results suggest that the codon at position 550 of S10 is under positive selection, while most of the other codons are under neutral evolution. Putative recombination events were identified in genomic RNA segments S1, 2, 4, 5, 6 and 10, which are rare in plant-infecting dsRNA viruses. This study reveals the current state of SRBSDV evolution. PMID:23605668

Li, Yongqiang; Xia, Zihao; Peng, Jun; Zhou, Tao; Fan, Zaifeng

2013-04-21

154

Inbred maize line Ph0R8  

US Patent & Trademark Office Database

An inbred maize line, designated PH0R8, the plants and seeds of inbred maize line PH0R8, methods for producing a maize plant, either inbred or hybrid, produced by crossing the inbred maize line PH0R8 with itself or with another maize plant, and hybrid maize seeds and plants produced by crossing the inbred line PH0R8 with another maize line or plant and to methods for producing a maize plant containing in its genetic material one or more transgenes and to the transgenic maize plants produced by that method. This invention also relates to inbred maize lines derived from inbred maize line PH0R8, to methods for producing other inbred maize lines derived from inbred maize line PH0R8 and to the inbred maize lines derived by the use of those methods.

2004-04-06

155

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...

156

Summary and conclusions on electrooptical streak camera project  

SciTech Connect

Two modifications to the evaluation set-up which would provide increased insight into the performance of the crystal streaking camera were proposed. The first of these has been tested with the results included in this report. The simple RC ramp circuit was modified by placing a diode across the output capacitance which shorts out the over-shoot which could depolarize the crystal. A pulser was added between the Stanford Research logic pulse generator and the Bragg cell modulator. This pulser is gated on and off to produce several laser pulses during the ramp. The concept was to be able to observe directly the resolvability of individual laser pulses beginning with 1 pulse on then two pulses on during the ramp, then increasing the number of pulses until the individual pulses are no longer resolvable. This can be converted into CTF (contrast transfer function) plotted against LPM (line pairs per millimeter) used in the evaluation of streaking cameras. The second modification proposed is to place the crystal in a liquid environment which will enable the application of voltages between 10 and 20 kV across the 1.3 mm crystal. A suitable liquid has been identified and ordered, Fluorinert, manufactured by 3M, with a break-down strength of about 21 kV per 1.3 mm. This should enable a deflection of about 250 pixels (at 16.25 kilo-volts) with the present optics or 500 pixels with a mirror causing two passes through the crystal.

Welch, B.

1988-01-01

157

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

158

Slope Streaks in the Antarctic Dry Valleys: Characteristics, Candidate Formation Mechanisms, and Implications for Slope Streak Formation in the Martian Environment  

Microsoft Academic Search

Enigmatic slope streaks on Mars are apparently active today. Remarkably similar analogs in the Antarctic Dry Valleys hyperarid polar desert involve near-surface flow of saline meltwater and wicking to the surface; we examine implications for Mars.

J. W. Head; D. R. Marchant; J. L. Dickson; J. S. Levy; G. A. Morgan

2007-01-01

159

Bunch length measurements at the TESLA Test Facility using a streak camera  

Microsoft Academic Search

A streak camera provides a direct and convenient way to measure bunch lengths in the millimeter and submillimeter range. At the TESLA Test Facility (TTF) a streak camera with a subpicosecond resolution is in operation. A bunch compressor is used to produce bunch lengths down to 250 ?m for the operation of the TTF free electron laser. Bunch length measurements

K. Honkavaara; P. Piot; S. Schreiber; D. Sertore

2001-01-01

160

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

Microsoft Academic Search

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

Eugene M. Caruso; Adam Waytz; Nicholas Epley

2010-01-01

161

Genetic variation of wheat streak mosaic virus in the United States Pacific Northwest.  

PubMed

Wheat streak mosaic virus (WSMV), the cause of wheat streak mosaic, is a widespread and damaging pathogen of wheat. WSMV is not a chronic problem of annual wheat in the United States Pacific Northwest but could negatively affect the establishment of perennial wheat, which is being developed as an alternative to annual wheat to prevent soil erosion. Fifty local isolates of WSMV were collected from 2008 to 2010 near Lewiston, ID, Pullman, WA, and the United States Department of Agriculture Central Ferry Research Station, near Pomeroy, WA to determine the amount of genetic variation present in the region. The coat protein gene from each isolate was sequenced and the data subjected to four different methods of phylogenetic analyses. Two well-supported clades of WSMV were identified. Isolates in clade I share sequence similarity with isolates from Central Europe; this is the first report of isolates from Central Europe being reported in the United States. Isolates in clade II are similar to isolates originating from Australia, Argentina, and the American Pacific Northwest. Nine isolates showed evidence of recombination and the same two well-supported clades were observed when recombinant isolates were omitted from the analysis. More polymorphic sites, parsimony informative sites, and increased diversity were observed in clade II than clade I, suggesting more recent establishment of the virus in the latter. The observed diversity within both clades could make breeding for durable disease resistance in perennial wheat difficult if there is a differential response of WSMV resistance genes to isolates from different clades. PMID:22970701

Robinson, Megan D; Murray, Timothy D

2013-01-01

162

Characterization of X-ray streak cameras for use on Nova  

SciTech Connect

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

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

1996-09-01

163

Finite-range time delays in numerical attosecond-streaking experiments  

NASA Astrophysics Data System (ADS)

We present results of numerical simulations and theoretical classical analysis of time delays with respect to the instant of ionization in a numerical streaking experiment. We show that the time delay is related to a finite range in space, which the emitted electron probes after its transition into the continuum until the streaking pulse ceases. This finite-range time delay results from the coupling of the atomic potential and the streaking field and strongly depends on the parameters, in particular the duration, of the streaking field. It can be represented as an integral or sum over piecewise field-free time delays weighted by the ratio of the instantaneous streaking field strength relative to the field strength at the instant of ionization.

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

2013-08-01

164

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

PubMed Central

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

2013-01-01

165

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...

166

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

PubMed Central

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

Nuss, Emily T.; Tanumihardjo, Sherry A.

2011-01-01

167

Lipid droplets in atherosclerotic fatty streaks of human aorta  

PubMed Central

Preparations of lipid droplets and droplet-free tissue residue (cytoplasm + membranes + nuclei) were obtained by homogenization and centrifugal separation from intimal fatty streak lesions of aortic atherosclerosis of 21 adults who had died suddenly. Neutral lipids and phospholipids were analyzed by quantitative thin-layer chromatography and cholesteryl ester fatty acids by gas-liquid chromatography. Optical properties of droplets were evaluated by differential counting and sizing procedures with the polarizing microscope. The droplets occurred in mixtures of two forms distinguished by their optical properties, anisotropic (i.e. liquid crystals) and isotropic (true liquids). Both forms had average diameters of about 1.8 ?, with a range of 0.5-5?. The proportions of the two forms varied with temperature as individual droplets changed their form; anisotropic forms averaged 83.7% at °C and 37.8% at 37°C, with isotropic forms being 16.3 and 62.2% respectively. The proportions of anisotropic forms at 22°C decreased with age. These forms were not separated for chemical analysis. The droplets contained about half the lipid in the lesions. The composition of the lipids of the droplet mixture was remarkably uniform and strikingly different from that of the droplet-free residue, respectively: cholesteryl esters 94.9% vs. 38.7%, free cholesterol 1.7% vs. 18.6%, total phospholipids 1.0% vs. 38.6%, and triglycerides 2.4% vs. 4.0%. The proportions of individual phospholipids, with the exception of lysolecithin, were also different between the preparations. In the droplets only the proportions of lecithin correlated positively with the proportion of anisotropic forms (at 22°C). Droplet cholesteryl esters were particularly rich in oleic acid and when compared to residue esters had more palmitoleic (+0.7%), oleic (+12.3%), and eicosatrienoic (+2.4%) and less palmitic (-2.2%), linoleic (-12.4%), and arachidonic (-1.6%) acids. The proportions of most individual fatty acids of droplets and residue correlated positively. The lipids of the residue closely resemble those reported for the normal intima. The observations that these droplets are prominent in the morphology of the fatty streak lesions, and that their high content of oleate-rich cholesteryl esters is similar to that reported for analysis of the whole lesions, suggest that the droplets may be involved in the pathogenesis of the fatty streak lesions of artherosclerosis in man.

Lang, P. Dieter; Insull, William

1970-01-01

168

Identification of QTLs conferring resistance to downy mildews of maize in Asia  

Microsoft Academic Search

Downy mildew is one of the most destructive diseases of maize in subtropical and tropical regions in Asia. As a prerequisite for improving downy mildew resistance in maize, we analyzed quantitative trait loci (QTLs) involved in resistance to the important downy mildew pathogens – Peronosclerospora sorghi (sorghum downy mildew) and P. heteropogoni (Rajasthan downy mildew) in India, P. maydis (Java

M. L. C. George; B. M. Prasanna; R. S. Rathore; T. A. S. Setty; F. Kasim; M. Azrai; S. Vasal; O. Balla; D. Hautea; A. Canama; E. Regalado; M. Vargas; M. Khairallah; D. Jeffers; D. Hoisington

2003-01-01

169

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

Technology Transfer Automated Retrieval System (TEKTRAN)

Due to autoinfection and alloinfection, maize is susceptible to infection by Fusarium verticillioides 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...

170

Doppler streak mode Fourier domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

Doppler Fourier domain optical coherence tomography is able to be used for in vivo blood flow measurement. In conventional methods, the highest velocity that can be measured is limited to the range the phase shift between two successively recorded depth profiles at the same probe-beam location, which cannot exceed (-?, ?), otherwise phase wrapping will occur. This phase-wrapping limit is determined by the time interval between two consecutive A-scans. We present a novel approach to shorten the time interval between two consecutive A-scans and thus increase the phase-wrapping limit by using an area scan camera to record the interference spectrum in a streak mode. To demonstrate the effectiveness of this method, the blood flows in HH18 and HH19 chick hearts were imaged and phase wrapping free Doppler images were obtained.

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

2012-02-01

171

Paramutation in maize  

Microsoft Academic Search

Paramutation is a heritable change in gene expression induced by allele interactions. This review summarizes key experiments on three maize loci, which undergo paramutation. Similarities and differences between the phenomenology at the three loci are described. In spite of many differences with respect to the stability of the reduced expression states at each locus or whether paramutation correlates with DNA

Vicki L. Chandler; William B. Eggleston; Jane E. Dorweiler

2000-01-01

172

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

173

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

174

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

2011-04-28

175

Chapter 11 Insect transmitted virus and mollicute disease  

Technology Transfer Automated Retrieval System (TEKTRAN)

Insect-transmitted diseases of maize are found throughout the maize growing regions of the world. These diseases are caused by viruses, phytoplasmas and spiroplasmas. The pathogens, vectors and plant hosts for the major insect-transmitted diseases of maize world-wide are reviewed. Factors leading to...

176

Improvements in off-center focusing in an x-ray streak camera  

NASA Astrophysics Data System (ADS)

Due to the planar construction of present x-ray streak tubes significant off-center defocusing is observed in both static and dynamic images taken with one-dimensional resolution slits. Based on the streak tube geometry curved photocathodes with radii of curvature ranging from 3.5 to 18 inches have been fabricated. We report initial off-center focusing performance data on the evaluation of these "improved" photocathodes in an X-ray streak camera and an update on the theoretical simulations to predict the optimum cathode curvature.

McDonald, Joseph W.; Weber, Franz; Griffith, Roger L.; Holder, Joe P.; Bell, Perry M.

2004-01-01

177

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

178

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

SciTech Connect

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

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

2003-01-01

179

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

180

On the Origin of Near-Surface Streaks in the Neutrally-Stratified Planetary Boundary Layer  

NASA Astrophysics Data System (ADS)

The dynamics of near-surface streak formation in the neutrallystratified, rotating planetary boundary layer areinvestigated. The purpose of this note is to compare large-eddysimulation results to theoretical predictions suggesting thatstreaks are associated with non-normal mode optimal perturbations.Streaks are regions near the surface of alternating high and lowspeed fluid organized into nearly linear bands, with horizontalspacing of several hundred metres, oriented up to 30° relativeto the geostrophic wind, that evolve through a continuous cycle ofgeneration, growth, decay and reformation. We find that the earlystages of streak formation and growth are consistent with thelinear theory.

Drobinski, Philippe; Foster, Ralph C.

181

Transmission studies with Cassava brown streak Uganda virus (Potyviridae: Ipomovirus) and its interaction with abiotic and biotic factors in Nicotiana benthamiana.  

PubMed

Cassava brown streak disease (CBSD), caused by two distinct species, Cassava brown streak Uganda virus (CBSUV) and Cassava brown streak virus (CBSV), is a major constraint to cassava (Manihot esculenta Crantz) production in Africa. Absence of infectious clones of CBSUV or CBSV and the lack of efficient means of mechanical transmission of CBSD has hampered laboratory studies of this disease. Mechanical transmission, achieved mainly by plant sap inoculation, is a widely used technique for characterizing plant viruses. Efficient sap transmission of CBSUV/CBSV to the common laboratory host Nicotiana benthamiana is essential for both basic and applied studies of the virus. We report here the development of an efficient protocol for sap transmission of CBSUV to N. benthamiana and N. debneyi. Several factors affecting transmission efficiency were identified such as the effects of buffer composition, antioxidants, inoculum concentration, plant age and temperature. Higher temperatures (30 °C) favored rapid symptom initiation compared to lower temperatures (21 °C) when sap prepared in phosphate buffer of pH 7.0 was applied on the leaves of N. benthamiana dusted with the abrasive (carborundum). We demonstrated the usefulness of the transmission method in transient evaluation of CBSUV[UG:Nam:04]-derived RNA interference constructs for CBSD resistance and also in studying the interaction of CBSUV[UG:Nam:04] with cassava mosaic geminiviruses, another important group of viruses infecting cassava. PMID:20691215

Ogwok, Emmanuel; Patil, Basavaprabhu L; Alicai, Titus; Fauquet, Claude M

2010-08-04

182

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

SciTech Connect

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

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

2010-10-15

183

Research on a flash imaging lidar based on a multiple-streak tube  

NASA Astrophysics Data System (ADS)

A flash imaging lidar based on a multiple-streak tube is presented in this paper; a fiber remapping optics maps light from an area in the focal plane of an imaging lens to multiple rows of fibers on the streak tube’s photocathode. The lidar system contains a multiple-streak tube, laser, transmitting and receiving telescope, remapping optical fibers, and CCD to capture stripe images from the streak tube’s phosphor screen. Data processing yields 48 × 48-pixel intensity and range images for each laser pulse. An experiment to test the property of this lidar is carried out in the laboratory; the intensity images and range images are gained by image remapping, and the range sampling is 0.21 m. Field test imagery demonstrated the capability of the flash lidar system to image a building 705 m away.

Liu, J.; Wang, Q.; Li, S.; Cheng, Y.; Wei, J.

2009-01-01

184

THEMIS Observations of Low-Albedo Intracrater Materials and Wind Streaks in Western Arabia Terra  

NASA Astrophysics Data System (ADS)

THEMIS day/night TIR images are used for thermophysical and spectral analyses of low-albedo intracrater materials and wind streaks and are compared with TES surface compositions and MOC observations to constrain origin hypotheses for these materials.

Wyatt, M. B.; McSween, H. Y., Jr.; Moersch, J. E.; Gorelick, N. S.; Christensen, P. R.

2003-03-01

185

Reference genes for reliable potyvirus quantitation in cassava and analysis of Cassava brown streak virus load in host varieties.  

PubMed

A reliable method for detection and quantitation of viruses associated with cassava brown streak disease (CBSD) is essential to determine their presence in material used for field propagation as well as for precise evaluation of CBSD resistance in the cassava germplasm. Quantitative RT-PCR (RT-qPCR) is a well-established method for precise quantitation of viral RNA amount in infected tissues. The method requires host reference genes with stable expression patterns under experimental conditions as internal controls for correct data normalization. Using the Genevestigator Refgene tool with Arabidopsis microarray data from Potyvirus-infected Arabidopsis as input data, candidate reference genes with stable expression pattern were selected as potential internal controls for the cassava -Cassava brown streak virus (CBSV; genus Ipomovirus; family Potyviridae) pathosystem. Primer pairs were designed for the cassava orthologs and their expression was analyzed in different tissues of three different CBSV-infected cassava varieties. The expression patterns of PP2A, UBQ10 and GTPb appeared to be the most stable in different CBSV-infected tissues and cassava varieties. The reference genes can therefore be used as internal controls for normalization of gene expression data in all types of cassava samples as well as in different cassava varieties infected by CBSV. The selected reference genes were used as internal controls to quantify CBSV in various symptomatic and asymptomatic plant organs to establish a correlation between virus load and symptom severity. PMID:21756941

Moreno, Isabel; Gruissem, Wilhelm; Vanderschuren, Hervé

2011-07-02

186

Ethanol Production from Maize  

Microsoft Academic Search

The production of fuel ethanol from corn grain is widely carried out in the US, with total current production at 7 billion\\u000a gallons. This may soon reach 10 billion gallons or more. This chapter addresses the potential of fuel ethanol as an additional\\u000a source of product based on utilization of the cellulosic (non-food) portions of maize, and in particular the

Stefan Schwietzke; Youngmi Kim; Eduardo Ximenes; Nathan Mosier; Michael Ladisch

187

The Maize Floral Transition  

Microsoft Academic Search

\\u000a The floral transition is a critical developmental change in a plant's life cycle that is marked by the switch from vegetative\\u000a to reproductive growth. The transition is induced by leaf-derived signals that translocate through the phloem to the shoot\\u000a apex where the shoot apical meristem is reprogrammed to adopt a floral fate. In maize, this occurs when the vegetative shoot

Joseph Colasanti; Michael Muszynski

188

Isolation of Lipoprotein-Acid Mucopolysaccharide Complexes from Fatty Streaks of Human Aorta  

Microsoft Academic Search

A method is presented for isolation of 1ipoprotein-acid mucopolysaccharide complexes from fatty streaks of human aorta. The complexes were extracted from fatty streaks with 0.15M NaCl and fractionated by gel filtration followed by ultracentrifugation at densities 1.006 and 1.065- The solvent density 1.065 was achieved by using D2O instead of NaCl which decreased dissociation of the complexes. These studies demonstrated

S. R. Srinivasan; P. Dolan; B. Radhakrishnamurthy; G. S. Berenson

1972-01-01

189

Applications of synchroscan and dual-sweep streak camera techniques to free-electron laser experiments  

Microsoft Academic Search

The results of several types of time-resolved experiments on rf-linac driven free-electron lasers (FELs) using streak-camera techniques are presented. In the past these techniques generally traded off time resolution, time span, and timing jitter to address either submicropulse or submacropulse effects. More recently, we have taken advantage of synchroscan streak cameras that were phase-locked to the reference 108.3 MHz rf

Alex H. Lumpkin

1991-01-01

190

Bone-induced streak artifact suppression in sparse-view CT image reconstruction  

PubMed Central

Background In sparse-view CT imaging, strong streak artifacts may appear around bony structures and they often compromise the image readability. Compressed sensing (CS) or total variation (TV) minimization-based image reconstruction method has reduced the streak artifacts to a great extent, but, sparse-view CT imaging still suffers from residual streak artifacts. We introduce a new bone-induced streak artifact reduction method in the CS-based image reconstruction. Methods We firstly identify the high-intensity bony regions from the image reconstructed by the filtered backprojection (FBP) method, and we calculate the sinogram stemming from the bony regions only. Then, we subtract the calculated sinogram, which stands for the bony regions, from the measured sinogram before performing the CS-based image reconstruction. The image reconstructed from the subtracted sinogram will stand for the soft tissues with little streak artifacts on it. To restore the original image intensity in the bony regions, we add the bony region image, which has been identified from the FBP image, to the soft tissue image to form a combined image. Then, we perform the CS-based image reconstruction again on the measured sinogram using the combined image as the initial condition of the iteration. For experimental validation of the proposed method, we take images of a contrast phantom and a rat using a micro-CT and we evaluate the reconstructed images based on two figures of merit, relative mean square error and total variation caused by the streak artifacts. Results The images reconstructed by the proposed method have been found to have smaller streak artifacts than the ones reconstructed by the original CS-based method when visually inspected. The quantitative image evaluation studies have also shown that the proposed method outperforms the conventional CS-based method. Conclusions The proposed method can effectively suppress streak artifacts stemming from bony structures in sparse-view CT imaging.

2012-01-01

191

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

SciTech Connect

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

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

1983-06-27

192

Genetic mechanisms of Maize dwarf mosaic virus resistance in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize resistance to viruses has been well-characterized at the genetic level, and loci responsible for resistance to potyviruses including Maize dwarf mosaic virus (MDMV), Sugarcane mosaic virus (SCMV), Sorghum mosaic virus (SrMV), and Johnsongrass mosaic virus (JGMV), have been mapped in several ge...

193

Spatiotemporal mechanical variation reveals critical role for rho kinase during primitive streak morphogenesis.  

PubMed

Large-scale morphogenetic movements during early embryo development are driven by complex changes in biochemical and biophysical factors. Current models for amniote primitive streak morphogenesis and gastrulation take into account numerous genetic pathways but largely ignore the role of mechanical forces. Here, we used atomic force microscopy (AFM) to obtain for the first time precise biomechanical properties of the early avian embryo. Our data reveal that the primitive streak is significantly stiffer than neighboring regions of the epiblast, and that it is stiffer than the pre-primitive streak epiblast. To test our hypothesis that these changes in mechanical properties are due to a localized increase of actomyosin contractility, we inhibited actomyosin contractility via the Rho kinase (ROCK) pathway using the small-molecule inhibitor Y-27632. Our results using several different assays show the following: (1) primitive streak formation was blocked; (2) the time-dependent increase in primitive streak stiffness was abolished; and (3) convergence of epiblast cells to the midline was inhibited. Taken together, our data suggest that actomyosin contractility is necessary for primitive streak morphogenesis, and specifically, ROCK plays a critical role. To better understand the underlying mechanisms of this fundamental process, future models should account for the findings presented in this study. PMID:22956163

Henkels, Julia; Oh, Jaeho; Xu, Wenwei; Owen, Drew; Sulchek, Todd; Zamir, Evan

2012-09-07

194

Intial synchroscan streak camera imaging at the A0 photoinjector  

SciTech Connect

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

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

2008-04-01

195

Maize is life”: Malawi's delayed Green Revolution  

Microsoft Academic Search

The pattern of maize seed development in Malawi demonstrates the importance of farmers' capacity to articulate their interests through collective action and institutions. Despite the vital significance of maize as a wage good in Malawi, limited effective demand for maize seed research prolonged the period of technical stagnation. Analysis of the institutional factors shaping the demand for maize seed research

Melinda Smale

1995-01-01

196

BIOGAS PRODUCTION FROM FRESH MAIZE BIOMASS  

Microsoft Academic Search

There is a need to find acceptable energy crops for biogas production for the climatic and soil conditions in Latvia. The average annual dry matter yields from maize vary from 12 to 16 t·ha -1 under the climatic conditions in Latvia. Biogas yield from fresh maize biomass was investigated in dependence on the harvesting time of maize. The maize varieties

Vilis Dubrovskis; Imants Plume; Janis Bartusevics; Vladimirs Kotelenecs

2010-01-01

197

Catalase Hybrid Enzymes in Maize  

Microsoft Academic Search

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

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

1964-01-01

198

The Effect of Heat–Moisture Treatment on the Structure and Physicochemical Properties of Normal Maize, Waxy Maize, Dull Waxy Maize and Amylomaize V Starches  

Microsoft Academic Search

Normal maize, waxy maize, dull waxy maize and amylomaize V starches were heat treated at 100 °C for 16 h at a moisture content of 30%. The results showed that the X-ray intensities of the major d-spacings of all starches increased on heat–moisture treatment (waxy maize > normal maize > dull waxy maize > amylomaize V). This treatment decreased the

R. Hoover; H. Manuel

1996-01-01

199

A SNP Streak Model for the Identification of Genetic Regions Identical-by-descent  

PubMed Central

The availability of very dense genetic maps is changing in a fundamental way the methods used to identify the genetic basis of both rare and common inherited traits. The ability to directly compare the genomes of two related individuals and quickly identify those regions that are inherited identical-by-descent (IBD) from a recent common ancestor would be of utility in a wide range of genetic mapping methods. Here, we describe a simple method for using dense SNP maps to identify regions of the genome likely to be inherited IBD by family members. This method is based on identifying obligate recombination events and examining the pattern of distribution of such events along the genetic map. Specifically, we use the length of a consecutive set of biallelic markers that have a high probability of having avoided such obligate recombination events. This “SNP streak” is derived from subsets of samples within a pedigree and allows us to make statistical inferences about the ancestry of the region(s) containing stretches of markers with these properties. We show that the use of subsets of more than two samples has the advantage of identifying shorter shared subsegments as significant. This mitigates the effects of errors in SNP calls. We provide specific examples of microarray-based SNP data, using a family with a complex pedigree and with a rare form of inherited kidney disease, to illustrate this approach.

Leibon, Gregory; Rockmore, Daniel N; Pollak, Martin R

2008-01-01

200

Quantitative measurements using soft x-ray streak cameras  

NASA Astrophysics Data System (ADS)

A Soft X-ray Streak Camera (SXRSC) is a fast timing instrument sensitive to x rays from 100 eV to 30 keV. The instrument has excellent time resolution (~15 ps) and large dynamic range (~103) which are well suited for measuring x-ray pulses produced by laser-fusion targets. The SXRSC uses a thin transmission photocathode to convert x-rays to a secondary electron signal which is acelerated, focused, and deflected onto a phosphor producing an image of the x-ray pulse time history. In the past, such instruments have been used only to make relative measurements of the time history. At LINL we have calibrated the SXRSC in order to make absolute intensity measurements of the soft x-ray flux from laser fusion targets. Such measurements will assist in understanding the laser plasma processes and conditions needed to attain laser-produced fusion. Because of the nature of the instrument, we have calibrated it in the dynamic mode using a small laser-produced pulsed x-ray source. Details of the calibrations will be given. We have measured the SXRSC response to be linear over more than two orders of magnitude with the range limited by the x-ray source strength. The dynamic range of similar instruments sensitive to optical light has been demonstrated to be greater than 103. Based on first generation calibrations, flux measurements are accurate to +/-30% with the largest uncertainty in the calibrations being in determining the source spectrum and intensity. The uncertainties can possibly be reduced by a factor of two by better source characterization. In that case errors in SXRSC measurements would approach those of other x-ray pulse detectors, such as x-ray diodes.

Kauffman, Robert L.; Stradling, Gary L.; Pierce, Edward L.; Medecki, Hector

1981-10-01

201

Exploiting the combination of natural and genetically engineered resistance to cassava mosaic and cassava brown streak viruses impacting cassava production in Africa.  

PubMed

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

2012-09-25

202

The Distribution and Spread of Sorghum Downy Mildew in Sorghum and Maize Fields in Nigeria and Zimbabwe  

Microsoft Academic Search

Sorghum downy mildew (Peronosclerospora sorghi, SDM) is a damaging disease of sorghum and maize crops in Africa. Runs analysis was used to study the distribution of systemically infected sorghum and maize plants in Nigeria and Zimbabwe. The temporal and spatial development of local lesions of SDM on sorghum in Zimbabwe was investigated by assessing the local lesion symptoms caused by

C. H. Bock; M. J. Jeger

2002-01-01

203

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...

204

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...

205

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

PubMed Central

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

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

2005-01-01

206

Effect of sources of maize and maize particle sizes on the utilization of phytate phosphorus in broiler chicks  

Microsoft Academic Search

Two experiments were conducted to test the effects of sources of maize and maize particle sizes on the utilization of phytate P in broiler chicks fed on maize–soyabean meal diets deficient in P. In Experiment 1, maize from four consignments was ground separately using the same milling facility. Four maize–soyabean diets representing each maize source, and two control diets made

A. B Kasim; H. M Edwards

2000-01-01

207

Anterior ischemic optic neuropathy in patient with hereditary spherocytosis and coexisting angioid streaks.  

PubMed

Purpose. To describe a rare case of hereditary spherocytosis (HE) with angioid streaks that developed anterior ischemic optic neuropathy (AION).?Method. Case report.?Results. A 53-year-old woman with HE had a 3-day history of blurred vision in the lower hemifield in the left eye. At presentation, her visual acuity was 20/20 OD and 20/200 OS. Perimetric testing showed a relative scotoma in the superior parafoveal region in the right eye and an inferior altitudinal field defect in the left eye. Fundus examination demonstrated angioid streaks in both eyes with swelling of the optic disc in the left eye. Both parvovirus B19 immunoglobulin M and immunoglobulin G were identified in her serum. ?Conclusions. This is the first report of AION in HE and coexisting angioid streaks. The infection by parvovirus itself might be involved in the development of AION. PMID:23112036

Sawada, Akira; Oie, Shinya; Mochizuki, Kiyofumi; Yamamoto, Tetsuya

2012-10-26

208

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

2010-05-15

209

Same-Shot X-Ray Thomson Scattering and Streaked Imaging of Xenon Radiative Shock Experiments  

NASA Astrophysics Data System (ADS)

We review the experimental design and results from recent CRASH radiative shock experiments at the Omega Laser facility. These experiments seek to measure the system with high accuracy, employing streaked x-ray radiography and x-ray Thomson scattering diagnostics on each shot. We detail how this diagnostic combination allows for precise interrogation of the different regions of the shock, including the radiation-heated upstream precursor, the radiatively collapsed cooling layer, and the downstream material. Spatially and temporally correlated data from the x-ray streak camera and gated spectrometer is shown, and plans for future iterations of radiative shock experiments are also discussed.

Huntington, Channing; Gamboa, Eliseo; Krauland, Christine; Kuranz, Carolyn; Drake, R. Paul; Glenzer, Siegfried

2011-11-01

210

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

SciTech Connect

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

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

2011-12-15

211

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

PubMed

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

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

2011-11-01

212

Probing subtle fluorescence dynamics in cellular proteins by streak camera based fluorescence lifetime imaging microscopy  

NASA Astrophysics Data System (ADS)

We report the cell biological applications of a recently developed multiphoton fluorescence lifetime imaging microscopy system using a streak camera (StreakFLIM). The system was calibrated with standard fluorophore specimens and was shown to have high accuracy and reproducibility. We demonstrate the applicability of this instrument in living cells for measuring the effects of protein targeting and point mutations in the protein sequence, which are not obtainable by conventional intensity-based fluorescence microscopy methods. We discuss the relevance of such time-resolved information in quantitative energy transfer microscopy and in measurement of the parameters that characterize the intracellular physiology.

Krishnan, R. V.; Biener, Eva; Zhang, Jian-Hua; Heckel, Robert; Herman, Brian

2003-12-01

213

Influence of wheat streak mosaic virus infection on phenylpropanoid metabolism and the accumulation of phenolics and lignin in wheat  

Microsoft Academic Search

Wheat plants infected with wheat streak mosaic virus were studied for their physiological response to infection. Previous histological data suggest that wheat streak mosaic virus-induced deposits of phenolic nature are present along the bundle sheath and mesophyll cell walls. In this study, we examined this phenomenon further by analysis of phenolic compounds and enzymes involved in their synthesis. In infected

S. A. Kofalvi; A. Nassuth

1995-01-01

214

Genomic variation in maize. Final project report.  

National Technical Information Service (NTIS)

These studies have sought to learn how different DNA sequences and sequence arrangements contribute to genome plasticity in maize. We describe quantitative variation among maize inbred lines for tandemly arrayed and dispersed repeated DNA sequences and ge...

C. J. Rivin

1991-01-01

215

Hybrid-maize—a maize simulation model that combines two crop modeling approaches  

Microsoft Academic Search

A new maize (Zea mays L.) simulation model, Hybrid-Maize, was developed by combining the strengths of two modeling approaches: the growth and development functions in maize-specific models represented by CERES-Maize, and the mechanistic formulation of photosynthesis and respiration in generic crop models such as INTERCOM and WOFOST. It features temperature-driven maize phenological development, vertical canopy integration of photosynthesis, organ-specific growth

H. S. Yang; A. Dobermann; J. L. Lindquist; D. T. Walters; T. J. Arkebauer; K. G. Cassman

2004-01-01

216

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

PubMed Central

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

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

2012-01-01

217

Streak observation of DC pre-breakdown light in silicone oil \\/ low-density polyethylene (LDPE) film composites using a long image guide scope  

Microsoft Academic Search

DC breakdown light of silicone oil and LDPE film composites between needle-sphere electrodes with the film placed on sphere electrode was observed using a streak camera. A long image guide scope (IGS) was attached to the streak camera as light delay path. This new system enables us to obtain a streak image of an initial process of the DC breakdown

Amir Izzani Mohamed; Yuuji Miyamoto; Masayoshi Mori; Kazunori Kadowaki

2011-01-01

218

Molecular characterization of the genome composition of partial amphiploids derived from Triticum aestivum×Thinopyrum ponticum and T. aestivum×Th. intermedium as sources of resistance to wheat streak mosaic virus and its vector, Aceria tosichella  

Microsoft Academic Search

Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (WCM), is one of the most important viral diseases of wheat\\u000a (Triticum aestivum) in the world. Genetic resistance to WSMV and the WCM does not exist in wheat. Resistance to WSMV and the WCM was evaluated\\u000a in five different partial amphiploids namely Agrotana, OK7211542, ORRPX, Zhong 5 and TAF

Q. Chen; R. L. Conner; F. Ahmad; A. Laroche; G. Fedak; J. B. Thomas

1998-01-01

219

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...

220

EVOLUTION OF WHEAT STREAK MOSAIC VIRUS: Dynamics of Population Growth Within Plants May Explain Limited Variation  

Microsoft Academic Search

Like many other plant RNA viruses, Wheat streak mosaic virus (WSMV) sequence diversity within and among infected plants is low given the large number of virions produced. This may be explained by considering aspects of plant virus life history. Intracellular replication of RNA viruses is predominately linear, not exponential, which means that the rate at which mutations accumulate also is

Roy C. French; Drake C. Stenger

2003-01-01

221

Sub-100 fs streak tube: computer-aided design, manufacturing, and testing  

NASA Astrophysics Data System (ADS)

In the present communication we describe the design of the sub-100 fs streak-tube that may be used for commercial streak cameras manufacturing. Careful attention is paid to preparing of a very smooth input photocathode substrate on which a low surface resistance (1-5 Ohm/) photocathode of S-1 type is deposited. Our estimations have shown that the photocathode surface roughness of about tens of nanometers may restrict the ultimate time resolution at the level of 100 fs. This is the reason why the photocathode substrate surface has to be smooth within the units of nanometers. The curvature of the photocathode surface is also very important to compensate the difference in the time-of-flight of electrons emitted from the central and peripheral photocathode areas. Further modernization was conducted with a photocathode-accelerating mesh assembly. The assembly may operate with 2 - 3 ns (FWHM) electrical pulses of 12 - 15 kV amplitude. In order to improve the S/N ratio in the streaked images, a shuttering system was incorporated inside the tube. As the result, a completely new femtosecond streak tube of PV-FS-M type was designed, manufactured, and tested.

Ageeva, N. V.; Andreev, S. V.; Degtyareva, V. P.; Greenfield, D. E.; Ivanova, S. R.; Kaverin, A. M.; Kulechenkova, T. P.; Levina, G. P.; Makushina, V. A.; Monastyrskiy, M. A.; Polikarkina, N. D.; Schelev, M. Ya; Semichastnova, Z. M.; Skaballanovich, T. A.; Sokolov, V. E.

2008-11-01

222

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

SciTech Connect

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

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

2008-09-18

223

STRAWBERRY NECROTIC SHOCK VIRUS: A NEW VIRUS PREVIOUSLY THOUGHT TO BE TOBACCO STREAK VIRUS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Tobacco streak virus (TSV) has a wide host range that exceeds 80 species (Fulton, 1948). Most of the efforts carried out previously comparing TSV isolates was based on immunological relations between them. The isolates of the virus from Fragaria and Rubus have been considered very closely related, ...

224

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

225

Temporal Characterization of Electron Beam Bunches with a Fast Streak Camera at JLAB FEL Facility.  

National Technical Information Service (NTIS)

The design and construction of an optical transport that brings synchrotron radiation from electron bunches to a fast streak camera in a remote area has become a useful tool for online observation of bunch length and stability. This paper will report the ...

S. Zhang S. Benson D. Doluglas D. Hardy K. Jordan

2005-01-01

226

Molecular characterization of banana streak acuminata Vietnam virus isolated from Musa acuminata siamea (banana cultivar)  

Microsoft Academic Search

Summary  An isolate of banana streak virus (BSV) that does not also occur as an integrant in the Musa balbisiana genome was sought in order to investigate the biological role of BSV in the evolution of either the Musa genome or of the virus itself. We isolated BSV virions from a Musa acuminata siamea accession from Vietnam and sequenced the entire

F. Lheureux; N. Laboureau; E. Muller; B. E. L. Lockhart; M.-L. Iskra-Caruana

2007-01-01

227

Multiplex Real Time PCR For Detection of Wheat Streak Mosaic Virus and Triticum Mosaic Virus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TRIMV) are widespread throughout the southwestern Great Plains states. Using conventional diagnostics such as Enzyme-Linked Immunosorbent Assays (ELISA), these two viruses are commonly found together in infected wheat samples. Methods for m...

228

Small Craters from Oblique Impacts and the Origin of an Unusual Streak in Elysium Planitia, Mars  

Microsoft Academic Search

We present a HiRISE image revealing details of small craters (<100 m) that are probably secondaries formed by oblique impacts. We also discuss working hypotheses for the formation mechanisms of the light-toned streak associated with one of them.

G. Komatsu; M. A. de Pablo; J. Ormö; L. L. Tornabene

2009-01-01

229

Full-Waveform Earthquake Location and the Mechanics of Streaks on the Calaveras Fault  

NASA Astrophysics Data System (ADS)

Recent advances in earthquake location techniques and their application to large waveform datasets have uncovered a number of previously obscured seismic phenomena. These phenomena have the potential to provide new insight into the physics of faulting and earthquakes. Seismic streaks are one of these phenomena, and we have developed a new method of earthquake location to study them. Our technique is based upon standard array analysis methods, but applied in the reciprocal geometry to earthquake sources instead of the more typical receiver array analysis. Using array techniques allows us to use information contained throughout the entire waveform, unlike traditional location techniques that rely solely on measurements of the direct P and S arrivals. This allows us to determine centroid locations for earthquakes previously unlocated or poorly located by standard methods due to clipping or lack of data. It also has the potential to produce high-resolution earthquake locations for similar events even with relatively few stations. Here, we apply this method to medium magnitude earthquakes (M3.5-M5) near streaks on the Calaveras fault. We find that that these earthquakes initiate within the seismic streaks, and rupture into regions generally devoid of microseismicity. From this, we infer that seismic streaks represent a rheological boundary between creeping and locked sections of a fault.

Rubinstein, J. L.; Beroza, G. C.

2005-12-01

230

Isochromosome 18q in a girl with holoprosencephaly, DiGeorge anomaly, and streak ovaries.  

PubMed

We report on the clinical and pathologic findings in a girl with isochromosome 18q (46, XX,i(18q)) who had combined manifestations of monosomy 18p and trisomy 18q. Major congenital anomalies included premaxillary agenesis, alobar holoprosenphaly, double outlet right ventricle, DiGeorge anomaly and streak ovaries. The clinical spectrum in i(18q) is very broad. PMID:8368259

van Essen, A J; Schoots, C J; van Lingen, R A; Mourits, M J; Tuerlings, J H; Leegte, B

1993-08-01

231

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

Microsoft Academic Search

Wheat streak mosaic virus, 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 reduce both forage and grain yield, and water-use efficiency of the plant. In light

Margarita Velandia; Roderick M. Rejesus; David C. Jones; Jacob A. Price; Fekede Workneh; Charles M. Rush

2010-01-01

232

Implications for global climate change on Mars: intriguing dark streaks and valleys-ocean boundary  

NASA Astrophysics Data System (ADS)

While some evidences imply that Mars was for most of its history cold and dry as it is today, other evidences imply that Martian history was much warmer and richer with water. The usual arguments for the first hypothesis is the lack of carbonates in the soil and large amounts of olivine that could survive only in dry conditions. One possible explanation for carbonates is that chemical processes near Martian surface dissolved them. One possible explanation for olivine is that it was exposed to the surface after the Mars was transformed to the present cold and dry state. The other explanation for olivine is that after ejection from volcanoes, in very short time it was covered by large amount of material before it had a chance to react with water, and re-exposed recently again in cold and dry conditions (e.g. Valles Marineris case). On the other hand, not only that some evidences support warm and wet hypothesis, but also that Mars once had rivers, lakes and ocean. Common to all related with the first hypothesis is that climate conditions were the same as today during most of the Martian history. Common to the second hypothesis is that climate significantly changed at some point in time. Accordingly, it has a sense to search for evidences that global climate changed. Recently, it was presented that intriguing dark streaks imply that we are near the end of large climate change on Mars [6thMars #3204]. The first interesting thing regarding them is that there are at least three cases where newly formed dark streak is observed. This proves that process of creation of dark streaks is still going on, meaning that any hypothesis regarding dark streaks has a good chance to be confirmed in some future mission to Mars. One is that formation of dark streaks is related with melting of ground water. This in combination with local distribution of dark streaks, where new one creates where some old one was not before, implies irreversible process where such water accumulated in different climate conditions. Recent analysis additionally shows correlation between valleys-termini and Contact 1 and Contact 2 [35thLPS #1992]. This additionally implies that global climate change happened when proposed ocean was between those two elevations, from warm and wet to cold and dry conditions. Accordingly, conclusion is that while dark-streaks and valleys-termini certainly require some further analysis and additional study by high-resolution color images and perhaps even some rover at the ground, they even now strongly support warm and wet hypothesis. This supports the above mentioned processes on Martian surface, currently not explainable by cold and dry hypothesis.

Salamuniccar, G.

233

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

SciTech Connect

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

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

1990-08-28

234

MaizeGDB, the community database for maize genetics and genomics  

PubMed Central

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

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

2004-01-01

235

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

Microsoft Academic Search

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

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

236

RESPUESTA DE HÍBRIDOS DE MAÍZ A LA APLICACIÓN DE POTASIO EN DIFERENTES DENSIDADES DE POBLACIÓN RESPONSE OF MAIZE HYBRIDS TO POTASSIUM APPLICATION AT DIFFERENT POPULATION DENSITIES  

Microsoft Academic Search

Maize producers in México confront a permanent challenge of getting a greater production at a lower cost. To increase the bene- fit\\/cost ratio, requires an optimal combination of factors involved in maize production. Some of these factors are variety, population den- sity, disease resistance and mineral nutrition. The importance of po- tassium in crop production is well known; however, studies

José Blas; Maya Lozano; José Luis Ramírez Díaz

2002-01-01

237

Aggressiveness of Cephalosporium maydis causing late wilt of maize in Spain.  

PubMed

Late wilt of maize, caused by the vascular and soilborne pathogen Cephalosporium maydis, was identified in the Iberian Peninsula in 2008. During the last years the incidence and economical impact of the disease has importantly increased both in Portugal and Spain. Varieties of maize displaying tolerance to the pathogen are available, but the effectiveness can be dependent on the virulence of the fungus (i.e. ability to cause disease on a specific genotype). On the other hand, strains of crop pathogens from different geographic origins can differ with regard to the degree of disease caused on a specific genotype (i.e. aggressiveness). Our working hypothesis was that isolates of C. maydis from different maize growing areas may differ in aggressiveness towards maize plants. Seven fungal strains were isolated in 2009 from diseased plants collected in the most important maize growing regions of Spain and used to inoculate two susceptible maize varieties grown in shadehouse from March to July 2010. The experimental unit consisted of two 4-day-old seedlings planted in an 8-liter pot filled with sand/silt previously infested with 200 g of wheat grains colonized by the fungi. Non colonized wheat grains were used for the control treatments. Six replications (pots) were established for each variety/isolate combination according to a complete randomized 2 x 8 factorial design. The percentage of necrotic and dry aboveground tissues was recorded 14 weeks after inoculation and thereafter weekly until physiological senescence of the control plants. At the end of the experiment, weights of roots and aboveground parts of the plants were recorded. Initial occurrence of symptoms in the plants was significantly dependent on the isolate of C. maydis and on the maize variety. However, final severity of aboveground symptoms (leaf necroses and drying up) was only dependent on the fungal isolate. All the isolates significantly reduced the root weight of both varieties of maize. The highest root weight reductions were also associated to a significant low weight of above-ground parts. Considering all the symptoms analysed and their progression in the maize plants, our results reveal that a diversity of aggressiveness exists among isolates of C. maydis. The need for a characterization of maize genotypes by their reaction against highly aggressive isolates of the fungus in the Iberian Peninsula is suggested. This study is a first step towards a recommendation of crop varieties that are tolerant to C. maydis in different areas of the Iberian Peninsula. Future research aims at studying the relationship between aggressiveness levels, molecular characteristics and geographical origin whithin C. maydis. PMID:23878971

García-Carneros, A B; Girón, I; Molinero-Ruiz, L

2012-01-01

238

Whiskers-mediated maize transformation.  

PubMed

There has been rapid progress in recent years in extending gene transfer capabilities to include plant species that fall outside the normal host range of Agrobacterium. Methods that allow direct DNA delivery into plant cells have contributed significantly to this expanded capability. Whiskers treatment is one means of delivering macromolecules, including DNA, to plant cells. Using relatively simple equipment and inexpensive materials, whiskers-mediated transformation of maize is possible. A critical prerequisite, however, is the establishment and maintenance of embryogenic tissue cultures as a source of totipotent, transformation-competent cells. Within hours of agitation in the presence of silicon carbide whiskers and DNA, embryogenic maize tissue cultures display transient gene expression, providing evidence for DNA uptake. Using appropriate selectable marker genes, following in vitro selection on inhibitory levels of a corresponding selection agent, stably transgenic tissue cultures can be generated from which fertile plants can be recovered. The timeline from whiskers treatment of embryogenic maize tissue cultures to fertile seed recovery is approximately 9 months, which is competitive with other methods of maize transformation. PMID:19378002

Petolino, Joseph F; Arnold, Nicole L

2009-01-01

239

The iojap gene in maize  

Microsoft Academic Search

The classical maize mutant iojap (Iodent japonica) has variegated green and white leaves. Green sectors have cells with normal chloroplasts whereas white sectors have cells where plastids fail to differentiate. These mutant plastids, when transmitted through the female gametophyte, do not recover in the presence of wild type Iojap. We cloned the Ij locus, and we have investigated the mechanism

Martienssen

2001-01-01

240

Flowering and determinacy in maize  

Microsoft Academic Search

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 control of meristem fate because of the contribution from determinate and indeterminate

Esteban Bortiri; Sarah Hake

2007-01-01

241

Betaine Deficiency in Maize 1  

PubMed Central

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

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

1991-01-01

242

Comparison of Diagnostic and Kinematic Vertical Motion Fields Associated with Curved and Straight Jet Streak Adjustment Processes.  

National Technical Information Service (NTIS)

Investigative research was performed on real and simulated jet streaks to determine the relationship of the diagnostic Rossby number with kinematic, balanced and non-balanced omega fields as a function of magnitude, wind shear and curvature. Hydrodynamic ...

G. E. Van Knowe

1990-01-01

243

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

SciTech Connect

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

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

1995-07-01

244

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

Federal Register 2010, 2011, 2012, 2013

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

2013-04-24

245

The mouse primitive streak forms in situ by initiation of epithelial to mesenchymal transition without migration of a cell population  

PubMed Central

During gastrulation, an embryo acquires the three primordial germ layers that will give rise to all of the tissues in the body. In amniote embryos, this process occurs via an epithelial to mesenchymal transition (EMT) of epiblast cells at the primitive streak. Although the primitive streak is vital to development, many aspects of how it forms and functions remain poorly understood. Using live imaging and immunohistochemistry, we have shown that the murine primitive streak arises in situ by progressive initiation of EMT beginning in the posterior epiblast, without large-scale movement or convergence and extension of epiblast cells. Loss of basal lamina (BL) is the first step of this EMT, and is strictly correlated with ingression of nascent mesoderm. This is the first description of dynamic cell behavior during primitive streak formation in the mouse embryo, and reveals mechanisms that are quite distinct from those observed in other amniote model systems.

Williams, Margot; Burdsal, Carol; Periasamy, Ammasi; Lewandoski, Mark; Sutherland, Ann

2011-01-01

246

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

247

Motion Streaks Do Not Influence the Perceived Position of Stationary Flashed Objects  

PubMed Central

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

Pavan, Andrea; Bellacosa Marotti, Rosilari

2012-01-01

248

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

SciTech Connect

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

Hares, J. D.; Dymoke-Bradshaw, A. K. L. [Kentech Instruments Ltd., Howbery Park, Wallingford, Oxfordshire OX10 8BA (United Kingdom)

2008-10-15

249

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

251

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

Microsoft Academic Search

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

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

2004-01-01

252

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

Microsoft Academic Search

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

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

2004-01-01

253

Compact streak camera for the shock study of solids by using the high-pressure gas gun  

Microsoft Academic Search

For the precise observation of high-speed impact phenomena, a compact high-speed streak camera recording system has been developed. The system consists of a high-pressure gas gun, a streak camera, and a long-pulse dye laser. The gas gun installed in our laboratory has a muzzle of 40 mm in diameter, and a launch tube of 2 m long. Projectile velocity is

Kunihito Nagayama; Yasuhito Mori

1993-01-01

254

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

Microsoft Academic Search

Summary. We have sequenced the complete genome of an isolate of Banana streak virus from banana cv. ‘Mysore’ and show that it is sufficiently different from a previously characterised isolate from cv. ‘Obino l’Ewai’ to warrant recognition as a distinct species, for which the name Banana streak Mysore virus (BSMysV) is proposed. The structure of the BSMysV genome was typical

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

2005-01-01

255

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

Microsoft Academic Search

A new optically deflected streaking camera with performance of nanosecond-range resolution, superior imaging quality, high signal detectability, and large format recording has been conceived and developed. Its construction is composed of an optomechanical deflector that deflects the line-shape image of spatial-distributed time-varying signals across the sensing surface of a cooled scientific two-dimensional CCD array with slow readout driving electronics, a

Ching C. Lai

1993-01-01

256

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

Microsoft Academic Search

A new optically deflected streaking camera with performance of nanosecond-range resolution, superior imaging quality, high signal detectability, and large format recording has been conceived and developed. Its construction is composed of an optomechanical deflector that deflects the line-shape image of spatial-distributed time-varying signals across the sensing surface of a cooled scientific two-dimensional CCD array with slow readout driving electronics, a

C. C. Lai

1992-01-01

257

Global-Scale Winds at the Venus Cloud-Top Inferred from Cloud Streak Orientations  

NASA Astrophysics Data System (ADS)

The orientations of the small cloud streaks that are always found at mid-latitudes in ultraviolet images of the Venus cloud-top provide a means for characterizing the global-scale circulation, including the wind field on the night side of Venus. Assuming that small clouds act as passive tracers of the cloud-top wind field, the orientation of cloud streaks is determined by the wind shear that the cloud has recently experienced. The typical deformation time for small clouds is about 50 hr, or one-half of a cloud-top rotation, so clouds viewed on the sunlit half of Venus show the influence of daytime and nighttime winds. By recording the orientations of cloud streaks and their variation with local solar time, we for the first time use cloud orientation information to place a constraint on the amplitudes of the Hadley circulation and solar thermal tides at the cloud-top level. A large solar thermal tide with a cloud-top meridional wind amplitude at 45 deg latitude of between 5.5-10.5 m sec^-1 is found to be necessary to account for the observed variation with local solar time of cloud streak orientations. Maximum poleward tidal winds occur in the early afternoon. The cloud-top Hadley circulation is estimated to have an amplitude at 45 deg latitude of between 3.5 and 8.5 m s^-1. This means the Hadley circulation may not be the dominant contributor to cloud-top meridional velocities, and that equatorward meridional velocities may exist over a portion of the night side at the Venus cloud-top.

Smith, Michael D.; Gierasch, Peter J.

1996-10-01

258

Mars eolian geology at airphoto scales: The large wind streaks of western Arabia Terra  

Microsoft Academic Search

More than 27,000 pictures at aerial photograph scales (1.5-12 m\\/pixel) have been acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) since September 1997. The pictures are valuable for testing hypotheses about geologic history and processes of Mars. Of particular interest are eolian features connected to surface albedo patterns. This work is focused on low-albedo wind streaks, some

2000-01-01

259

Spatiotemporal Pattern Formation in Early Development: A Review of Primitive Streak Formation and Somitogenesis  

Microsoft Academic Search

\\u000a The basic body plan of a number of vertebrates results from two processes that occur early in the development of the blastoderm:\\u000a large scale rearrangements of tissue via a process called gastrulation, and axial subdivision of tissue in a process called\\u000a somitogenesis. The first step of gastrulation in avians is formation of the primitive streak, which marks the first clear

S. Schnell; K. J. Painter; P. K. Maini; H. G. Othmer

260

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

PubMed

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. PMID:21230185

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

2010-09-28

261

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

NASA Astrophysics Data System (ADS)

Soft X-ray stream cameras are used in conjunction with several instruments for the diagnostic of laser irradiated targets. The development of cameras which satisfy the requirements of the laser facility, to improve the reliability and performance of the camera and to reduce the level of effort required to set and operate each diagnostic is reported. The implemented soft X-ray streak cameras can be operated either manually or automatically.

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

1983-06-01

262

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

2013-08-08

263

Maize DNA enrichment by representational difference analysis in a maize chromosome addition line of oat  

Microsoft Academic Search

The recent recovery of maize (Zea mays L.) single-chromosome addition lines of oat (Avena sativa L.) from oat x maize crosses has provided novel source materials for the potential isolation of maize chromosome-specific\\u000a sequences for use in genetic mapping and gene cloning. We report here the application of a technique, known as representational\\u000a difference analysis (RDA), to selectively isolate maize

Z. J. Chen; Ronald L. Phillips; Howard W. Rines

1998-01-01

264

Comparative Sequence Analysis of the Sorghum Rph Region and the Maize Rp1 Resistance Gene Complex  

PubMed Central

A 268-kb chromosomal segment containing sorghum (Sorghum bicolor) genes that are orthologous to the maize (Zea mays) Rp1 disease resistance (R) gene complex was sequenced. A region of approximately 27 kb in sorghum was found to contain five Rp1 homologs, but most have structures indicating that they are not functional. In contrast, maize inbred B73 has 15 Rp1 homologs in two nearby clusters of 250 and 300 kb. As at maize Rp1, the cluster of R gene homologs is interrupted by the presence of several genes that appear to have no resistance role, but these genes were different from the ones found within the maize Rp1 complex. More than 200 kb of DNA downstream from the sorghum Rp1-orthologous R gene cluster was sequenced and found to contain many duplicated and/or truncated genes. None of the duplications currently exist as simple tandem events, suggesting that numerous rearrangements were required to generate the current genomic structure. Four truncated genes were observed, including one gene that appears to have both 5? and 3? deletions. The maize Rp1 region is also unusually enriched in truncated genes. Hence, the orthologous maize and sorghum regions share numerous structural features, but all involve events that occurred independently in each species. The data suggest that complex R gene clusters are unusually prone to frequent internal and adjacent chromosomal rearrangements of several types.

Ramakrishna, Wusirika; Emberton, John; SanMiguel, Phillip; Ogden, Matthew; Llaca, Victor; Messing, Joachim; Bennetzen, Jeffrey L.

2002-01-01

265

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

266

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

267

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

268

Direct evidence for encoding of motion streaks in human visual cortex  

PubMed Central

Temporal integration in the visual system causes fast-moving objects to generate static, oriented traces (‘motion streaks’), which could be used to help judge direction of motion. While human psychophysics and single-unit studies in non-human primates are consistent with this hypothesis, direct neural evidence from the human cortex is still lacking. First, we provide psychophysical evidence that faster and slower motions are processed by distinct neural mechanisms: faster motion raised human perceptual thresholds for static orientations parallel to the direction of motion, whereas slower motion raised thresholds for orthogonal orientations. We then used functional magnetic resonance imaging to measure brain activity while human observers viewed either fast (‘streaky’) or slow random dot stimuli moving in different directions, or corresponding static-oriented stimuli. We found that local spatial patterns of brain activity in early retinotopic visual cortex reliably distinguished between static orientations. Critically, a multivariate pattern classifier trained on brain activity evoked by these static stimuli could then successfully distinguish the direction of fast (‘streaky’) but not slow motion. Thus, signals encoding static-oriented streak information are present in human early visual cortex when viewing fast motion. These experiments show that motion streaks are present in the human visual system for faster motion.

Apthorp, Deborah; Schwarzkopf, D. Samuel; Kaul, Christian; Bahrami, Bahador; Alais, David; Rees, Geraint

2013-01-01

269

NO-?-catenin crosstalk modulates primitive streak formation prior to embryonic stem cell osteogenic differentiation.  

PubMed

Nitric oxide (NO) has been shown to play a crucial role in bone formation in vivo. We sought to determine the temporal effect of NO on murine embryonic stem cells (ESCs) under culture conditions that promote osteogenesis. Expression profiles of NO pathway members and osteoblast-specific markers were analyzed using appropriate assays. We found that NO was supportive of osteogenesis specifically during an early phase of in vitro development (days 3-5). Furthermore, ESCs stably overexpressing the inducible NO synthase showed accelerated and enhanced osteogenesis in vitro and in bone explant cultures. To determine the role of NO in early lineage commitment, a stage in ESC differentiation equivalent to primitive streak formation in vivo, ESCs were transfected with a T-brachyury-GFP reporter. Expression levels of T-brachyury and one of its upstream regulators, ?-catenin, the major effector in the canonical Wnt pathway, were responsive to NO levels in differentiating primitive streak-like cells. Our results indicate that NO may be involved in early differentiation through regulation of ?-catenin and T-brachyury, controlling the specification of primitive-streak-like cells, which may continue through differentiation to later become osteoblasts. PMID:22946055

Ding, Huawen; Keller, Kevin C; Martinez, Ivann K C; Geransar, Rose M; zur Nieden, Kai O; Nishikawa, Sandra G; Rancourt, Derrick E; zur Nieden, Nicole I

2012-09-03

270

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...

271

CHROMOSOME-BY-CHROMOSOME MAIZE GENOME ANALYSIS USING OAT-MAIZE ADDITION LINES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Oat-maize Addition lines (OMA 1 through 10) are available where one maize chromosome has been individually added to the oat genome by a wide cross. By gamma irradiation, several hundred Radiation Hybrid (RH) lines now exist with only a fragment of the maize chromosome resulting from deletions of the...

272

MaizeGDB: Global support for maize research through open access information [abstract  

Technology Transfer Automated Retrieval System (TEKTRAN)

MaizeGDB is the open-access global repository for maize genetic and genomic information – from single genes that determine nutritional quality to whole genome-scale data for complex traits including yield and drought tolerance. The data and tools at MaizeGDB enable researchers from Ethiopia to Ghan...

273

Divergent Selection for Resistance to Maize Weevil in Six Maize Populations  

Microsoft Academic Search

weevils for untreated grain of maize hybrids stored in traditional structures, and up to an 80% loss may occur Maize weevil (Sitophilus zeamais Motschulsky) is an important in on-farm stores in tropical countries (Mutiro et al., pest of maize (Zea mays L.) in the tropics, causing serious losses for 1992; Pingali and Pandey, 2001). many resource-poor farmers who store grain

Thanda Dhliwayo; Kevin V. Pixley

2003-01-01

274

Keepers of maize in Chiapas, Mexico  

Microsoft Academic Search

This study concerns the knowledge and selection of biological diversity of maize (Zea mays) within its center of domestication in Mesoamerica. Maize farmers in central Chiapas of Southern México keep local varieties\\u000a (landraces) belonging to six races and four race mixtures. Fifteen local varieties are recognized. In spite of widespread\\u000a adoption of a modern, high yielding variety, maize farmers continue

Mauricio R. Bellon; Stephen B. Brush

1994-01-01

275

Cassava virus diseases in Africa  

Microsoft Academic Search

Cassava plays a key role in the food security of sub-Saharan Africa, but as a vegetatively propagated crop, it is particularly vulnerable to the effects of virus diseases and these therefore represent a major threat to the livelihoods of millions of Africans. Nine viruses have been isolated from African cassava, but only cassava mosaic geminiviruses (CMGs) and Cassava brown streak

J. M. Threshb

276

Cassava virus diseases in Africa  

Microsoft Academic Search

Abstract Cassava plays a key role in the food security of sub-Saharan Africa, but as a vegetatively propagated crop, it is particularly vulnerable to the effects of virus diseases and these therefore represent a major,threat to the livelihoods of millions of Africans. Nine viruses have been isolated from African cassava, but only cassava mosaic geminiviruses (CMGs) and Cassava brown streak

J. p. Legg; J. m. Thresh

277

[New technology in maize breeding].  

PubMed

Results obtained by several approaches in the application of Biotechnology in maize breeding are reviewed. RFLP technology in the determination of genetic variation; gene transfer by the use of different methods of gene delivery and the determination of gene integration. Three technologies for foreign gene introduction have been applied; injection of plasmid pRT100 neo into archesporial tissue before micro and macro sporogenesis, slightly modified pollen-tube pathway technology and dry seed incubation in plasmid DNA solution. NPTII gene integration was followed by dot-blot and Southern blot analysis of plant DNA of both T1 and T2 plants. Gene expression was analysed by neomycin phosphotransferase activity. Transformed plants contained the selective NPTII gene sequence in an active form. Bacterial gene integration induced several heritable changes of plant phenotype. As an important change, alteration of the flowering time has been used as a criterion for selection and plant propagation to keep transformed progeny. Besides plant genome transformation, endogenous bacteria living in different maize tissue were found. As a perspective approach for biotechnology application in maize breeding biological vaccine construction has been selected. Therefore, antagonistic effect of gram positive bacterial strains to several pathogenic fungi was investigated. Results obtained after in vivo experiments are discussed. PMID:1340483

Konstantinov, K; Mladenovi?, S; Stojkov, S; Deli?, N; Gosi?, S; Petrovi?, R; Levi?, J; Deni?, M

1992-01-01

278

Duplicated fie Genes in Maize  

PubMed Central

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

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

2003-01-01

279

The iojap gene in maize  

SciTech Connect

The classical maize mutant iojap (Iodent japonica) has variegated green and white leaves. Green sectors have cells with normal chloroplasts whereas white sectors have cells where plastids fail to differentiate. These mutant plastids, when transmitted through the female gametophyte, do not recover in the presence of wild type Iojap. We cloned the Ij locus, and we have investigated the mechanism of epigenetic inheritance and phenotypic expression. More recently, a modifier of this type of variegation, ''Inhibitor of striate'', has also been cloned. Both the iojap and inhibitor of striate proteins have homologs in bacteria and are members of ancient conserved families found in multiple species. These tools can be used to address fundamental questions of inheritance and variegation associated with this classical conundrum of maize genetics. Since the work of Rhoades there has been considerable speculation concerning the nature of the Iojap gene product, the origin of leaf variegation and the mechanism behind the material inheritance of defective plastids. This has made Iojap a textbook paradigm for cytoplasmic inheritance and nuclear-organellar interaction for almost 50 years. Cloning of the Iojap gene in maize, and homologs in other plants and bacteria, provides a new means to address the origin of heteroplastidity, variegation and cytoplasmic inheritance in higher plants.

Martienssen, Robert

2001-12-01

280

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...

281

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 ...

282

Chemical and Physicochemical Properties of Maize Starch After Industrial Nixtamalization  

Microsoft Academic Search

Cereal Chem. 78(5):543-550 Processing conditions similar to traditional nixtamalization are now used by the industry in the production of dry maize flours (DMF). The objective of this investigation was to evaluate the effect of industrial nixtamalization on maize starch. Thus, dent maize grains were sampled from storage silos and the starch isolated (S). From the same batch of maize, DMF

Jorge F. Toro-Vazquez; Carlos A. Gómez-Aldapa

2001-01-01

283

Comparative genomics of Arabidopsis and maize: prospects and limitations  

PubMed Central

The completed Arabidopsis genome seems to be of limited value as a model for maize genomics. In addition to the expansion of repetitive sequences in maize and the lack of genomic micro-colinearity, maize-specific or highly-diverged proteins contribute to a predicted maize proteome of about 50,000 proteins, twice the size of that of Arabidopsis.

Brendel, Volker; Kurtz, Stefan; Walbot, Virginia

2002-01-01

284

Transgenic Maize Plants by Tissue Electroporation  

Microsoft Academic Search

In this paper, we describe the transformation of regenerable maize tissues by electroporation. In many maize lines, imma- ture zygotic embryos can give rise to embryogenic callus cultures from which plants can be regenerated. lmmature zygotic embryos or embryogenic type I calli were wounded either enzymatically or mechanically and subsequently electropo- rated with a chimeric gene encoding neomycin phosphotransferase (neo).

Kathleen DHalluin; Martine Bossut; Marc De Beuckeleer; Jan Leemans

1992-01-01

285

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...

286

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...

287

Two-dimensional sampling-image x-ray streak camera for ultrafast imaging of ICF plasmas  

NASA Astrophysics Data System (ADS)

Ultrafast two-dimensional (2D) x-ray imaging with a temporal resolution better than 10 ps is of great importance in diagnosing the final stages of the imploded core plasmas of ICF targets. Multi-imaging x-ray streak camera (MIXS)[1,2] has been one of such imaging technique. Recently, we have proposed another scheme, a 2D sampling-image x-ray streak camera method (2D-SIXS)[2]. In this scheme, a 2D image is sampled two-dimensionally with a set of sampling points distributed regularly over the whole image on a cathode plate of an x-ray streak camera. The sampled image is streaked, and then, reconstructed to form the time-resolved 2D images like movie pictures. In this paper, we report results of our proof-of-principle experiments of 2D-SIXS scheme performed at Gekko-XII glass laser system. A gold-coated spherical target was irradiated by three beams of Gekko-XII laser (527 nm). Streaked data of 2D-SIXS was obtained and a series of time-resolved 2D x-ray images were successfully reconstructed. [1] H. Shiraga, et al, Rev. Sci. Instrum. 66, 722 (1995), and references therein. [2] H. Shiraga, et al, Rev. Sci. Instrum. 68, 745 (1997).

Shiraga, H.; Nakasuji, M.; Heya, M.; Miyanaga, N.

1997-11-01

288

Two-dimensional sampling-image x-ray streak camera for ultrafast imaging of inertial confinement fusion plasmas  

NASA Astrophysics Data System (ADS)

Ultrafast two-dimensional (2D) x-ray imaging with a temporal resolution better than 10 ps is of great importance in diagnosing the final stages of the imploded core plasmas of inertial confinement fusion (ICF) targets. The multi-imaging x-ray streak camera (MIXS) has been one of such imaging techniques. Recently, we have proposed another scheme, a 2D sampling-image x-ray streak camera method (2D-SIXS). In this scheme, a 2D image is sampled two dimensionally with a set of sampling points distributed regularly over the whole image on a cathode plate of an x-ray streak camera. The sampled image is streaked, and then, reconstructed to form the time-resolved 2D images like movie pictures. In this article, we report results of our proof-of-principle experiments of 2D-SIXS scheme performed at Gekko-XII glass laser system. A gold-coated spherical target was irradiated by three beams (0.53 ?m) of Gekko-XII laser. Streaked data of 2D-SIXS were obtained and a series of time-resolved 2D x-ray images were successfully reconstructed. 2D-SIXS is suitable for very fast, short-lived, and small x-ray sources such as a hot spark in the ICF plasma as well as short-pulse-laser-produced plasmas.

Shiraga, H.; Nakasuji, M.; Heya, M.; Miyanaga, N.

1999-01-01

289

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

PubMed

This paper describes a convenient and accurate method to calibrate fast (<1 ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such systems are inherently difficult to calibrate due to the lack of sufficiently intense, calibrated light sources. Such a system is used to collect spectral data on plasmas generated in electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA) at Sandia National Laboratories. On RITS, plasma light is collected through a small diameter (200 ?m) optical fiber and recorded on a fast streak camera at the output of a 1 meter Czerny-Turner monochromator. For this paper, a 300 W xenon short arc lamp (Oriel Model 6258) was used as the calibration source. Since the radiance of the xenon arc varies from cathode to anode, just the area around the tip of the cathode ("hotspot") was imaged onto the fiber, to produce the highest intensity output. To compensate for chromatic aberrations, the signal was optimized at each wavelength measured. Output power was measured using 10 nm bandpass interference filters and a calibrated photodetector. These measurements give power at discrete wavelengths across the spectrum, and when linearly interpolated, provide a calibration curve for the lamp. The shape of the spectrum is determined by the collective response of the optics, monochromator, and streak tube across the spectral region of interest. The ratio of the spectral curve to the measured bandpass filter curve at each wavelength produces a correction factor (Q) curve. This curve is then applied to the experimental data and the resultant spectra are given in absolute intensity units (photons/sec/cm(2)/steradian/nm). Error analysis shows this method to be accurate to within +?- 20%, which represents a high level of accuracy for this type of measurement. PMID:22938275

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

2012-08-01

290

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

291

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

SciTech Connect

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

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

1981-02-01

292

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

SciTech Connect

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

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

2005-08-21

293

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

SciTech Connect

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

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

2005-07-25

294

Transient electric fields in laser plasmas observed by proton streak deflectometry  

SciTech Connect

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

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

2008-03-03

295

QUANTITATIVE TRAIT LOCICONDITIONING RESISTANCE TO PHAEOSPHAERIA LEAF SPOT OF MAIZE CAUSED BY PHAEOSPHAERIA MAYDIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Phaeosphaeria leaf spot is a potentially important maize disease that has recently appeared in the continental United States in winter breeding nurseries in southern Florida. Inbred lines related to B73 are particularly susceptible to Phaeosphaeria leaf spot, whereas inbreds related to Mo17 are high...

296

Fusarium verticillioides gene clusters associated with biotransformation of maize allelopathic compounds  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize produces the benzoxazinones DIMBOA and DIBOA, which naturally transform into the more stable benzoxazolinones MBOA and BOA, respectively. These weed-suppressive allelopathic compounds are also implicated in resistance to microbial diseases and insect feeding. Fusarium verticillioides is able t...

297

Using Maize chlorotic dwarf virus to explore future frontiers in plant virology  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize chlorotic dwarf virus (MCDV) causes a chlorosis and stunting disease of corn throughout the Midwest United States. It is a waikavirus transmitted by the leafhopper Graminella nigrifrons. Although waikaviruses are economically important viruses in corn and rice, little is known about the viru...

298

Maize and oat antixenosis and antibiosis against Delphacodes kuscheli (Homoptera: Delphacidae), vector of "Mal de Rio Cuarto" of maize in Argentina.  

PubMed

"Mal de Rio Cuarto" (MRC) is the most important virus disease of maize, Zea mays L., in Argentina. Several maize lines show different levels of resistance to MRC in the field; however, no studies have been conducted to investigate resistance mechanisms against its insect vector, Delphacodes kuscheli Fennah (Homoptera: Delphacidae). Oat, Avena spp., is the main overwintering host of D. kuscheli and main source of populations that infest maize. Although oat varieties resistant to the greenbug, Schizaphis graminum (Rondani) (Homoptera: Aphididae) are commercially available, their effect on D. kuscheli is unknown. We conducted laboratory experiments to test for the presence of antixenosis and antibiosis resistance mechanisms on six maize lines with different levels of field resistance to MRC, and seven commercial oat cultivars that include two S. graminum-resistant varieties. We did not find antibiotic effects of maize lines on D. kuscheli longevity and survivorship patterns, but we obtained antixenotic effects from the LP2 line (field moderate) due to reduced settling preference and feeding. Oat 'Bonaerense Payé and 'Suregrain INTA' showed both antixenosis and antibiosis, with significantly less settling preference, oviposition in the no-choice test, and reduced total fecundity in comparison with the other varieties studied. The S. graminum-resistant 'Boyera F. A.' and 'Tambera F. A.' did not showed a consistent pattern of resistance versus D. kuscheli across all experiments. Our results indicate the presence of potential sources of insect resistance in the maize lines and oat cultivars tested that may be used in MRC integrated pest management programs. PMID:16156593

Costamagna, A C; de Remes Lenicov, A M M; Zanelli, M

2005-08-01

299

Evidence for tidal triggering of high-amplitude rapid tremor reversals and tremor streaks in northern Cascadia  

NASA Astrophysics Data System (ADS)

We provide a new link between tectonic tremor propagation, tremor amplitude, and tidal stresses by analyzing high-resolution tremor locations and amplitudes determined by multibeam backprojection of data from an array of subarrays. For two Cascadia episodic tremor and slip events, we observe repeating, high-amplitude rapid tremor reversals (RTRs) and tremor streaks. They tend to occur when tremor amplitudes are highest and occur almost exclusively during periods of thrust-encouraging, tidally induced shear stress on the fault. We speculate that thrust-encouraging shear stress from tidal loading forces trigger RTRs and streaks that energetically rerupture the weakened fault behind the slow slip front. The high rate and amplitude of tremor during RTRs and streaks stands in contrast to the hypothesis that activity at the leading edge of the slow slip zone is the most energetic and loudest. This implies that the spatiotemportal pattern of slow earthquake slip migration is even more intricate than previously reported.

Thomas, Trevor W.; Vidale, John E.; Houston, Heidi; Creager, Kenneth C.; Sweet, Justin R.; Ghosh, Abhijit

2013-08-01

300

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

NASA Astrophysics Data System (ADS)

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.

2010-11-01

301

Preliminary Performance Measurements for a Streak Camera with a Large-Format Direct-Coupled CCD Readout  

SciTech Connect

Livermore's ICF Program has a large inventory of optical streak cameras built in the 1970s and 1980s. The cameras are still very functional, but difficult to maintain because many of their parts are obsolete including the original streak tube and image-intensifier tube. The University of Rochester's Laboratory for Laser Energetics is leading an effort to develop a fully automated, large-format streak camera that incorporates modern technology. Preliminary characterization of a prototype camera shows spatial resolution better than 20 lp/mm, temporal resolution of 12 ps, line-spread function of 40 {micro}m (fwhm), contrast transfer ratio (CTR) of 60% at 10 lp/mm, and system sensitivity of 16 CCD electrons per photoelectron. A dynamic range of 60 for a 2 ns window is determined from system noise, linearity and sensitivity measurements.

Lerche, R A; McDonald, J W; Griffith, R L; de Dios, G V; Andrews, D S; Huey, A W; Bell, P M; Landen, O L; Jaanimagi, P A; Boni, R

2004-04-13

302

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.

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

2012-01-01

303

Benzoxazinoids in root exudates of maize attract Pseudomonas putida to the rhizosphere.  

PubMed

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

2012-04-24

304

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  

Microsoft Academic Search

A series of Wheat streak mosaic virus (WSMV)-based expression vectors were developed by engineering a 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 peptides cleaved GFP from HC-Pro but expressed GFP inefficiently. WSMV-GFP vectors with homologous NIa-Pro heptapeptide

Satyanarayana Tatineni; Anthony J. McMechan; Gary L. Hein; Roy French

2011-01-01

305

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

PubMed Central

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

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

2012-01-01

306

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

307

A Method for Analysing High Resolution, Time Domain, Streak Camera Calibration Data  

SciTech Connect

Many experiments that require a highly accurate continuous time history of photon emission incorporate streak cameras into their setup. Nonlinear recordings both in time and spatial displacement are inherent to streak camera measurements. These nonlinearities can be attributed to sweep rate electronics, curvature of the electron optics, the magnification, and resolution of the electron optics. These nonlinearities are systematic; it has been shown that a short pulse laser source, an air-spaced etalon of known separation, and a defined spatial resolution mask can provide the proper image information to correct for the resulting distortion. A set of Interactive Data Language (IDL){sup 1} software routines were developed to take a series of calibration images showing temporally and spatially displaced points, and map these points from a nonlinear to a linear space-time resultant function. This correction function, in combination with standardized image correction techniques, can be applied to experiment data to minimize systematic errors and improve temporal and spatial resolution measurements.

Silbernagel, C

2004-07-02

308

Slit-mounted LED fiducial system for rotating mirror streak cameras  

SciTech Connect

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

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

1991-01-01

309

Spontaneous hybridization between maize and teosinte.  

PubMed

The closest wild relatives of maize, Zea mays ssp. mays are various Zea taxa known as "teosinte." Hybrids between maize and the teosinte taxon, Zea mays ssp. mexicana, often occur when the 2 are sympatric in Mexico. Measuring the spontaneous hybridization rate of the 2 taxa would shed light on the mechanisms contributing to the evolution and persistence of these hybrid swarms. We conducted a series of field experiments in Riverside, CA, to measure the natural hybridization rates between maize and 2 teosinte taxa, Z. m. ssp. mexicana and Zea mays ssp. parviglumis. We planted teosinte within and near maize plantations. Hybrids were identified by progeny testing for a maize-specific herbicide resistance allele and a teosinte-specific allozyme allele. Hybridity was confirmed by growing putative hybrid progeny to maturity to evaluate whether they had the characteristic morphology of maize x teosinte hybrids. We found that maize and Z. m. ssp. mexicana naturally hybridize at a low rate (<1%), whereas Z. m. ssp. parviglumis hybridizes with the crop at a high rate (>50%). PMID:17400586

Ellstrand, Norman C; Garner, Lauren C; Hegde, Subray; Guadagnuolo, Roberto; Blancas, Lesley

2007-03-30

310

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

PubMed

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

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

2005-01-27

311

Hybridization of maize and teosinte, in mexico and guatemala and the improvement of maize  

Microsoft Academic Search

The recognition and subsequent detection of the importance of teosinte introgression in the racial diversity and heterotic\\u000a gene architecture of maize has been one of the outstanding achievements of Paul C. Mangelsdorf’s investigations into the origin\\u000a of maize. This paper documents three areas in Mexico and Guatemala where maize and teosinte hybridize and where there is a\\u000a system by which

H. G. Wllkes

1977-01-01

312

The Maize Genome Contains a Helitron Insertion  

PubMed Central

The maize mutation sh2-7527 was isolated in a conventional maize breeding program in the 1970s. Although the mutant contains foreign sequences within the gene, the mutation is not attributable to an interchromosomal exchange or to a chromosomal inversion. Hence, the mutation was caused by an insertion. Sequences at the two Sh2 borders have not been scrambled or mutated, suggesting that the insertion is not caused by a catastrophic reshuffling of the maize genome. The insertion is large, at least 12 kb, and is highly repetitive in maize. As judged by hybridization, sorghum contains only one or a few copies of the element, whereas no hybridization was seen to the Arabidopsis genome. The insertion acts from a distance to alter the splicing of the sh2 pre-mRNA. Three distinct intron-bearing maize genes were found in the insertion. Of most significance, the insertion bears striking similarity to the recently described DNA helicase–bearing transposable elements termed Helitrons. Like Helitrons, the inserted sequence of sh2-7527 is large, lacks terminal repeats, does not duplicate host sequences, and was inserted between a host dinucleotide AT. Like Helitrons, the maize element contains 5? TC and 3? CTRR termini as well as two short palindromic sequences near the 3? terminus that potentially can form a 20-bp hairpin. Although the maize element lacks sequence information for a DNA helicase, it does contain four exons with similarity to a plant DEAD box RNA helicase. A second Helitron insertion was found in the maize genomic database. These data strongly suggest an active Helitron in the present-day maize genome.

Lal, Shailesh K.; Giroux, Michael J.; Brendel, Volker; Vallejos, C. Eduardo; Hannah, L. Curtis

2003-01-01

313

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

PubMed

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

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

2010-11-30

314

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

PubMed Central

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

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

2008-01-01

315

Hardness methods for testing maize kernels.  

PubMed

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry. PMID:19496585

Fox, Glen; Manley, Marena

2009-07-01

316

Photophobic behavior of maize roots.  

PubMed

Primary roots of young maize seedlings showed peculiar growth behavior when challenged by placing them on a slope, or if whole seedlings were turned upside down. Importantly, this behavior was dependent on the light conditions. If roots were placed on slopes in the dark, they performed "crawling" behavior and advanced rapidly up the slope. However, as soon as these roots were illuminated, their crawling movements along their horizontal paths slowed down, and instead tried to grow downwards along the gravity vector. A similar light-induced switch in the root behavior was observed when roots were inverted, by placing them in thin glass capillaries. As long as they were kept in the darkness, they showed rapid growth against the gravity vector. If illuminated, these inverted roots rapidly accomplished U-turns and grew down along the gravity vector, eventually escaping from the capillaries upon reaching their open ends. De-capped roots, although growing vigorously, did not display these light-induced photophobic growth responses. We can conclude that intact root cap is essential for the photophobic root behavior in maize. PMID:22751294

Burbach, Christian; Markus, Katharina; Zhang, Yin; Schlicht, Markus; Baluška, František

2012-07-01

317

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

PubMed Central

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

2011-01-01

318

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

PubMed

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

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

2011-11-27

319

Impact of enhanced ultraviolet-B irradiance on maize yield and its seed qualities: a field evaluation  

NASA Astrophysics Data System (ADS)

Stratospheric ozone depletion has caused an increase in the amount of UV-B radiation reaching the earth"s surface. Numerous investigations have demonstrated that the effect of UV-B enhancements on plants includes reduction in grain yield, alteration in species competition, susceptibility to disease, and changes in plant structure and pigmentation. Many experiments examining UV-B radiation effects on plants were conducted in growth chambers or greenhouses. It has been questioned if the effect of UV-B radiation on plants can be extrapolated to field responses from indoor studies because of the unnaturally high ratios of UV-B/UV-A and UV-B/PAR in many indoor studies. Field studies on UV-B radiation effect on plants has been recommended in order to use the UV and PAR irradiance provided by natural light. This study reported the growth and yield responses of a maize crop exposed to enhanced UV-B radiation and the UV-B effects on maize seed qualities under field conditions. Enhanced UV-B radiation caused a significant reduction of the dry matter accumulation, and the maize yield in turn was affected. With increased UV-B radiation the flavonoid accumulation in maize leaves increased, and the contents of chlorophyll a, b, and (a+b) of maize leaves were reduced. The levels of protein, sugar, and starch of maize seed decreased with enhanced UV-B radiation, while the level of lysine increased with enhanced UV-B radiation.

Gao, Wei; Zheng, Youfei; Slusser, James R.; Heisler, Gordon M.; He, Douliang; Xu, Jianqiang

2003-06-01

320

Foliar diseases of corn  

Technology Transfer Automated Retrieval System (TEKTRAN)

Leaf blights and spots caused by fungi are some of the most destructive diseases of corn in the US and around the world. Correct identification of the disease is very important in determining the best means of control. For example, gray leaf spot of maize can be caused by one of at least two species...

321

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...

322

Maize, Matrilocality, Migration, and Northern Iroquoian Evolution  

Microsoft Academic Search

The co-occurrence of matrilocality and maize-based agriculture among historical northern Iroquoian groups of New York and southern Ontario has long been of interest to anthropologists and archaeologists. The traditional explanation of this association is that gradual evolution of maize-based agriculture through female labor enhanced female status in families, which resulted in matrilocality. Dean Snow (1995a) recently challenged this in situ

John P. Hart

2001-01-01

323

Can Transgenic Maize Affect Soil Microbial Communities?  

PubMed Central

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

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

2006-01-01

324

Molecular Evidence and the Evolution of Maize  

Microsoft Academic Search

In this review, the contributions of isozyme and chloroplast DNA studies to questions surrounding the evolution of maize are\\u000a summarized. These methods of analysis provide generally strong support for the hierarchical system of classification of Zea\\u000a proposed by Iltis and Doebley (1980). Molecular evidence is fully congruent with the theory that teosinte is ancestral to\\u000a maize and suggests thatZ. mays

John Doebley

1990-01-01

325

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

2011-07-23

326

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

SciTech Connect

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

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

1987-11-01

327

Molecular Analysis of the Essential and Nonessential Genetic Elements in the Genome of Peanut Chlorotic Streak Caulimovirus  

Microsoft Academic Search

The DNA genome of caulimoviruses contains a set of essential genes: I (movement gene), IV (major capsid protein gene), V (reverse transcriptase gene), and VI (gene coding for a post-transcriptional activator of the expression of other virus genes). In peanut chlorotic streak caulimovirus (PCISV), three ORFs, A, B, and C, are located between genes I and IV. They are dissimilar

A. R. Mushegian; J. A. Wolff; R. D. Richins; R. J. Shepherd

1995-01-01

328

Wheat streak mosaic virus genotypes introduced to Argentina are closely related to isolates from the American Pacific Northwest and Australia  

Technology Transfer Automated Retrieval System (TEKTRAN)

Wheat streak mosaic virus (WSMV) was first detected in Argentina in 2002. Comparison of 78 WSMV coat protein sequences revealed that three Argentine isolates were closely related to isolates from the American Pacific Northwest (APNW) and Australia. Complete sequences were determined for one Argen...

329

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

National Technical Information Service (NTIS)

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

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

1984-01-01

330

A detection method for streak artifacts and radiological noise in a non-uniform region in a CT image.  

PubMed

By using the CT images obtained by subtracting two CT images acquired under the same conditions and slice locations, we have devised a method for detecting streak artifacts in non-uniform regions and only radiological noise components in CT images. A chest phantom was scanned using 16- and 64-multidetector row helical CT scanners with various mAs values at 120kVp. The upper lung slice image was employed as a target image for evaluating the streak artifacts and radiological noise. One hundred parallel line segments with a length of 80 pixels were placed on the subtracted CT image, and the largest CT value in each CT value profile was employed as a feature variable of the streak artifacts; these feature variables were analyzed with the extreme value theory (Gumbel distribution). To detect only the radiological noise, all CT values contained in the 100 line profile were plotted on normal probability paper and the standard deviation was estimated from the inclination of its fitted line for the CT value plots. The two detection methods devised in this study were able to evaluate the streak artifacts and radiological noise in the CT images with high accuracy. PMID:20036595

Imai, Kuniharu; Ikeda, Mitsuru; Enchi, Yukihiro; Niimi, Takanaga

2009-12-29

331

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

National Technical Information Service (NTIS)

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 flo...

K. S. Edgett

2001-01-01

332

Identification of functional sequences in the pregenomic RNA promoter of the Banana streak virus Cavendish strain (BSV-Cav)  

Microsoft Academic Search

The promoter regions of plant pararetroviruses direct transcription of the full-length viral genome into a pregenomic RNA that is an intermediate in the replication of the virus. It serves as template for reverse transcription and as polycistronic mRNA for translation to viral proteins. We have identified functional promoter elements in the intergenic region of the Cavendish isolate of Banana streak

Tony Remans; Christopher P. L. Grof; Paul R. Ebert; Peer M. Schenk

2005-01-01

333

CERES-Maize: A Simulation Model of Maize Growth and Development.  

National Technical Information Service (NTIS)

CERES-Maize, like the similar model CERES-Wheat, is a user-oriented, daily-incrementing simulation model of maize growth, development, and yield. It is available in two versions. The standard version simulates the effects of genotype, weather, and soil pr...

C. A. Jones J. R. Kiniry D. B. Farmer P. T. Dyke D. C. Godwin

1985-01-01

334

Replacement Value of Normal Maize with Quality Protein Maize (Obatampa) in Broiler Diets  

Microsoft Academic Search

Three hundred and sixty days old Ross Broiler Chicks were used in a completely randomized design feeding trial to evaluate the benefits of replacing Normal Maize (NM) with Quality Protein Maize (QPM) (Obatampa variety) in Broiler diets. There were 6 treatments of 3 replicates each and each replicate had 20 chicks. Six diets were formulated in which the NM in

P. A. Onimisi; J. J. Omage; I. I. Dafwang; G. S. Bawa

2009-01-01

335

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

Microsoft Academic Search

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

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

2002-01-01

336

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

2013-03-12

337

Antimicrobial Screening of Actinobacteria using a Modified Cross-Streak Method.  

PubMed

Out of the 30 actinobacterial cultures screened for antimicrobial activity, 28 cultures were found to produce active products against various pathogenic microorganisms such as Gram-negative, Gram-positive bacteria and yeast, using a modified cross streak method. The modified method helped in easy quantification of results and also in ruling out probable mutual antibiosis. The actinobacterial strains that showed the ability to produce antimicrobial compounds belonged to Streptomyces (53%), Micromonospora (13%) and Actinomadura (10%) genera. Streptomyces sp. strain MMA-5 showed the highest multispecific antibiosis efficiency score value. Broad antibiotic spectrum activity was exhibited by Streptomyces sp. strain MMA-2 and Micromonospora sp. strain MMA-8. The multidrug resistant human pathogenic yeast strain Candida albicans was inhibited by 18 actinobacterial strains. PMID:22303068

Velho-Pereira, Sonashia; Kamat, N M

2011-03-01

338

Integration of banana streak badnavirus into the Musa genome: molecular and cytogenetic evidence.  

PubMed

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 and Musa sequences and a complex BSV integrant. In situ hybridization revealed two different BSV sequence locations in Obino l'Ewai chromosomes and a complex arrangement of BSV and Musa sequences was shown by probing stretched DNA fibers. This is the first report of integrated sequences that possibly lead to a plant pararetrovirus episomal infection by a mechanism differing markedly from animal retroviral systems. PMID:10069945

Harper, G; Osuji, J O; Heslop-Harrison, J S; Hull, R

1999-03-15

339

The genome organization of lucerne transient streak and turnip rosette sobemoviruses revisited.  

PubMed

Unlike other sobemoviruses, lucerne transient streak virus (LTSV) and turnip rosette virus (TRoV) have been reported to contain two successive ORF1s (denoted as ORF1a and ORF1b) instead of a single ORF1. Also, their next ORF (ORF2a/2a2b) has been mapped to a region ca. 200 nucleotides downstream from that of other sobemoviruses, leading to the lack of transmembrane segments at the N-termini of P2a/2a2b. In the current study, we resequenced this region for TRoV and LTSV. The hypothetical beginning of ORF1b was mapped as the beginning of ORF2a/2a2b for both TRoV and LTSV. Computional analysis revealed transmembrane segments at the N-termini of the TRoV and LTSV polyproteins. PMID:23111554

Sõmera, Merike; Truve, Erkki

2012-10-31

340

High dynamic range streak camera for subpicosecond time-resolved x-ray spectroscopy  

SciTech Connect

The full characterization of a time resolved x-ray spectrometer is presented. It is based on the coupling of a conical crystal with a subpicosecond x-ray streak camera. The detector is designed to operate in accumulation mode at high repetition rate (up to 1 kHz) allowing signal to noise ratio as high as 10{sup 4}:1. Optical switches have been used to limit the jitter induced in the subpicosecond range, demonstrating the very long term stability (a few hours) of the entire device. The data analysis have been developed to get the spectral and temporal resolution of an ultrashort laser-plasma-based x-ray source.

Bonte, C.; Harmand, M.; Dorchies, F.; Magnan, S.; Pitre, V.; Kieffer, J.-C.; Audebert, P.; Geindre, J.-P. [Universite Bordeaux I, CNRS, CEA, CELIA UMR 5107, 351 cours de la Liberation, Talence, F-33405 (France); I.N.R.S.-Energie, Materiaux et Telecommunications, 1650 boul. Lionel-Boulet, Varennes, Qc, J3X 1S2 (Canada); Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, 91128 Palaiseau (France)

2007-04-15

341

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

SciTech Connect

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

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

1982-01-01

342

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

NASA Astrophysics Data System (ADS)

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

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

1981-02-01

343

The ECM Moves during Primitive Streak Formation--Computation of ECM Versus Cellular Motion  

PubMed Central

Galileo described the concept of motion relativity—motion with respect to a reference frame—in 1632. He noted that a person below deck would be unable to discern whether the boat was moving. Embryologists, while recognizing that embryonic tissues undergo large-scale deformations, have failed to account for relative motion when analyzing cell motility data. A century of scientific articles has advanced the concept that embryonic cells move (“migrate”) in an autonomous fashion such that, as time progresses, the cells and their progeny assemble an embryo. In sharp contrast, the motion of the surrounding extracellular matrix scaffold has been largely ignored/overlooked. We developed computational/optical methods that measure the extent embryonic cells move relative to the extracellular matrix. Our time-lapse data show that epiblastic cells largely move in concert with a sub-epiblastic extracellular matrix during stages 2 and 3 in primitive streak quail embryos. In other words, there is little cellular motion relative to the extracellular matrix scaffold—both components move together as a tissue. The extracellular matrix displacements exhibit bilateral vortical motion, convergence to the midline, and extension along the presumptive vertebral axis—all patterns previously attributed solely to cellular “migration.” Our time-resolved data pose new challenges for understanding how extracellular chemical (morphogen) gradients, widely hypothesized to guide cellular trajectories at early gastrulation stages, are maintained in this dynamic extracellular environment. We conclude that models describing primitive streak cellular guidance mechanisms must be able to account for sub-epiblastic extracellular matrix displacements.

Zamir, Evan A; Rongish, Brenda J; Little, Charles D

2008-01-01

344

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

PubMed Central

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

Mikedis, Maria M.; Downs, Karen M.

2012-01-01

345

High density lipoprotein plasma fractions inhibit aortic fatty streaks in cholesterol-fed rabbits.  

PubMed

The effects of in vivo administration of high density lipoprotein-very high density lipoprotein (HDL-VHDL) on the development of aortic fatty streaks were studied in cholesterol-fed rabbits. The rabbits received a 0.5% cholesterol-rich diet for 8 weeks. During this period, the HDL-VHDL group was intravenously administered with 50 mg/week of homologous HDL-VHDL protein; the control group received normal saline (0.9% NaCl). HDL-VHDL fraction was obtained at density range 1.063 to 1.25 gm/ml by ultracentrifugation of normal rabbit plasma. Along the study, plasma lipid levels followed a similar profile in both groups. At the completion of the study, atherosclerotic-like lipid-rich lesions covered 37.9 +/- 6% (X +/- SEM) of the intimal aortic surface in the control group, and 14.9 +/- 2.1% in the treated group (p less than 0.001). The values of total and free cholesterol, esterified cholesterol, and phospholipids deposited within vessel wall were significantly lower in the aortas of the HDL-VHDL treated group than those in the control group. Cholesterol accumulation in the livers was also significantly lower (p less than 0.01) in the treated group than in the control. We concluded that administration of homologous HDL-VHDL lipoprotein fraction to cholesterol-fed rabbits, dramatically inhibited the extent of aortic fatty streaks and lowered lipid deposition in the arterial wall and liver without modification of the plasma lipid levels. PMID:2927083

Badimon, J J; Badimon, L; Galvez, A; Dische, R; Fuster, V

1989-03-01

346

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

NASA Astrophysics Data System (ADS)

The classical streak cameras use a vacuum tube making thus fragile, cumbersome and expensive. The FAst MOS Imager (FAMOSI) project consists in reproducing completely this streak camera functionality with a single CMOS chip. The advantages of on-chip functionalities lead to a power reduction, a lower cost and miniaturization. In this paper, we show the capabilities of a prototype fabricated in the AMS 0.35 ?m CMOS process. The chip is composed of 64 columns per 64 rows of pixels. The pixels have a size of 20 ?m per 20 ?m and a fill factor of 47 %. The Chip FAMOSI implements an electronic shutter and an analog accumulation capability inside the pixel. With this pixel architecture, the sensor can work in single shot mode when the light pulse power is sufficient and in repetitive mode, i.e. it can measure a recurrent light pulse and accumulates the successive photo charges into an internal node, for low light pulse detection. This repetitive mode utilizes an analog accumulation in order to improve the sensitivity and the signal to noise ratio of the system. Characterizations under static and uniform illumination in single shot mode have been done in order to evaluate the performances of the detector. The main noises levels have been evaluated and the experiments show that a conversion gain of 4.8 ?V/e- is obtained with a dynamic range of 1.2V. Moreover, the charge transfer characterization in single shot mode has been realized. It permits to know which potential must be apply to the charge spill transistor to obtain the whole dynamic of the output with a maximal transfer gain, what is primordial to optimize the analog accumulation. Finally, the dynamic operation of the sensors is exposed. Measurements show a sample time of 715 ps and a time resolution better than 2 ns. A 6 ns light pulse has been measured in single shot and in accumulation mode.

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

2008-05-01

347

Technique for in situ calibration of an x-ray streak camera in the nanosecond regime using a high density Z-pinch  

SciTech Connect

A technique for calibrating an x-ray streak camera in situ has been developed. It has been applied to an x-ray streak camera installed on a collapsing gas shell Z-pinch. The calibration was done by simultaneously measuring the emitted x-rays using a pinhole camera, an InP:Fe photoconductive detector, and the streak camera. The spatial dimension of the streak image was calibrated by integrating the film density over time and fitting the resulting data to the corresponding information taken from an x-ray pinhole image. The temporal calibration was obtained by similarly fitting the film density from the x-ray streak image as a function of time integrated over the appropriate part of the spatial dimension with the signal from an InP:Fe photoconductive detector. By using this technique we have found a spatial magnification of the streak camera system consistent with the results derived from the geometrical optics to within 10%. A temporal dispersion of 2.5 +- 0.5 ns/mm was obtained, which is in agreement with the nominal speed of 2.5 ns/mm. This technique also yielded an absolute intensity calibration of the streak camera.

Jones, L.A.; Kallne, E.; Kania, D.R.; Maestas, M.; McGurn, J.S.; Shepherd, R.

1985-09-01

348

Improved Cell and Tissue Culture Systems for Maize.  

National Technical Information Service (NTIS)

Observations indicated a promotive effect of 5-azacytidine (SAC), a known DNA methylation inhibitor, on the initiation of embryonic callus and maize. Also, maize culture maintenance improved when callus was grown on media containing sorbitol. The objectiv...

R. D. Locy

1987-01-01

349

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

2011-03-10

350

Quantitative assessment of image noise and streak artifact on CT image: comparison of z-axis automatic tube current modulation technique with fixed tube current technique.  

PubMed

The purpose of our study is to quantitatively assess the effects of z-axis automatic tube current modulation technique on image noise and streak artifact, by comparing with fixed tube current technique. Standard deviation of CT-values was employed as a physical index for evaluating image noise, and streak artifact was quantitatively evaluated using our devised Gumbel evaluation method. z-Axis automatic tube current modulation technique will improve image noise and streak artifact, compared with fixed tube current technique, and will make it possible to significantly reduce radiation doses at lung levels while maintaining the same image quality as fixed tube current technique. PMID:19342196

Imai, Kuniharu; Ikeda, Mitsuru; Enchi, Yukihiro; Niimi, Takanaga

2009-04-01

351

Design and simulation analysis for maize stubble harvester  

Microsoft Academic Search

In order to reduce the towing resistance of the digging maize stubble device and ensure the indicators of reducing missing ratio and raising the harvest productivity when reaping maize, the new harvest technique was put forward, namely, stubble cutting shovel first stretch stubble ridge, and then maize rhizomes were collected by rhizome pick-up device and auxiliary pick-up device together. A

Yang ChuanHua; Ge YiYuan; Wang JunFa; Wei TianLu

2011-01-01

352

Investigation of the Bottleneck Leading to the Domestication of Maize  

Microsoft Academic Search

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

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

1998-01-01

353

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...

354

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

355

Species of Cercospora associated with grey leaf spot of maize  

PubMed Central

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

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

2006-01-01

356

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

PubMed Central

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

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

2007-01-01

357

Long-term assessment of nitrogen and variety technologies on attainable maize yields in Nigeria using CERES-maize  

Microsoft Academic Search

Maize simulation models are proposed as tools for assessment of response to nitrogen (N) fertilizer and varieties in order to explore potential target zones for improved maize varieties. The CERES-maize model in the Decision Support System for Agrotechnology Transfer version 2.1 was tested using international testing nurseries at Ibadan, Mokwa, and Kaduna situated, respectively, in the derived savanna, southern guinea

S. S. Jagtap; F. J. Abamu; J. G. Kling

1999-01-01

358

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

Microsoft Academic Search

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

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

359

An Integrated Control Scheme for Cocoa Pests and Diseases in Papua New Guinea  

Microsoft Academic Search

Pest control recommendations in Papua New Guinea cocoa plantings are based on an integrated approach to insect pest and disease management. The most damaging problems are Pantorhytes weevils, black pod and bark canker disease (both caused by Phytophthora palmivora) but vascular streak dieback (VSD) disease is important in some areas of the country. Most other insect pests can be kept

E. S. C. Smith

1981-01-01

360

Cassava virus diseases and their control with special reference to southern Tanzania  

Microsoft Academic Search

Cassava is a major smallholder crop in much of Africa where it is attacked by two main virus diseases. African cassava mosaic disease (ACMD) occurs almost everywhere that the crop is grown causing severe losses in some countries. Cassava brown streak disease (CBSD) is of more restricted distribution being prevalent mainly on the east African coast and shores of Lake

R. J. HILLOCKS

1997-01-01

361

Gene Mapping with Recombinant Inbreds in Maize  

PubMed Central

Recombinant inbred lines of maize have been developed for the rapid mapping of molecular probes to chromosomal location. Two recombinant inbred families have been constructed from F(2) populations of T232 X CM37 and CO159 X Tx303. A genetic map based largely on isozymes and restriction fragment length polymorphisms has been produced that covers virtually the entire maize genome. In order to map a new gene, an investigator has only to determine its allelic distribution among the recombinant inbred lines and then compare it by computer with the distributions of all previously mapped loci. The availability of the recombinant inbreds and the associated data base constitute an efficient means of mapping new molecular markers in maize.

Burr, B.; Burr, F. A.; Thompson, K. H.; Albertson, M. C.; Stuber, C. W.

1988-01-01

362

Topology of a maize field  

PubMed Central

Correlations were established between plant height and Cartesian position in a field of diverse maize (Zea mays) germplasm. The influence of the shade avoidance syndrome (SAS), a series of responses to lower photosynthetically active radiation (PAR) and red to far-red light ratio (R:FR) at high planting density, was detected by a steep increase of plant height from the edge to interior rows of the field. In addition, a gradual increase in height was observed across the field from east to west. We attribute this result to a R:FR gradient caused by sunlight laterally penetrating the stand at dusk. Furthermore, we hypothesize that the increased height of west-positioned plants may be analogous to responses induced by end-of-day FR (EOD-FR) treatments used by photobiologists to induce SAS in controlled environments. While preliminary, these results nevertheless suggest that a plant's position in a field will influence the impact of daily fluctuations in PAR and R:FR in modulating plant height and, potentially, other agronomically relevant traits.

Brutnell, Thomas P

2011-01-01

363

Electrotropism of Maize Roots 1  

PubMed Central

We examined the kinetics of electrotropic curvature in solutions of low electrolyte concentration using primary roots of maize (Zea mays L., variety Merit). When submerged in oxygenated solution across which an electric field was applied, the roots curved rapidly and strongly toward the positive electrode (anode). The strength of the electrotropic response increased and the latent period decreased with increasing field strength. At a field strength of 7.5 volts per centimeter the latent period was 6.6 minutes and curvature reached 60 degrees in about 1 hour. For electric fields greater than 10 volts per centimeter the latent period was less than 1 minute. There was no response to electric fields less than 2.8 volts per centimeter. Both electrotropism and growth were inhibited when indoleacetic acid (10 micromolar) was included in the medium. The auxin transport inhibitor pyrenoylbenzoic acid strongly inhibited electrotropism without inhibiting growth. Electrotropism was enhanced by treatments that interfere with gravitropism, e.g. decapping the roots or pretreating them with ethyleneglycol-bis-[?-ethylether]-N,N,N?,N?-tetraacetic acid. Similarly, roots of agravitropic pea (Pisum sativum, variety Ageotropum) seedlings were more responsive to electrotropic stimulation than roots of normal (variety Alaska) seedlings. The data indicate that the early steps of gravitropism and electrotropism occur by independent mechanisms. However, the motor mechanisms of the two responses may have features in common since auxin and auxin transport inhibitors reduced both gravitropism and electrotropism.

Ishikawa, Hideo; Evans, Michael L.

1990-01-01

364

Response of UK winter wheat cultivars to Soil-borne cereal mosaic and Wheat spindle streak mosaic viruses across Europe  

Microsoft Academic Search

Twenty-one UK winter wheat cultivars were grown over three seasons at sites with natural inoculum sources of Soil-borne cereal mosaic virus (SBCMV) and Wheat spindle streak mosaic virus (WSSMV) located in France, Italy and the UK. Plants were assessed visually for virus symptoms and leaf extracts were tested\\u000a for the presence of each virus using enzyme-linked immunosorbent assays (ELISA). Cultivars

G. E. Budge; C. Ratti; C. Rubies-Autonell; D. Lockley; M. Bonnefoy; V. Vallega; S. Pietravalle; C. M. Henry

2008-01-01

365

Phylogeny of Banana Streak Virus Reveals Recent and Repetitive Endogenization in the Genome of Its Banana Host ( Musa sp.)  

Microsoft Academic Search

Banana streak virus (BSV) is a plant dsDNA pararetrovirus (family Caulimoviridae, genus badnavirus). Although integration is not an essential step in the BSV replication cycle, the nuclear genome of banana (Musa sp.) contains BSV endogenous pararetrovirus sequences (BSV EPRVs). Some BSV EPRVs are infectious by reconstituting a functional\\u000a viral genome. Recent studies revealed a large molecular diversity of episomal BSV

Philippe Gayral; Marie-Line Iskra-Caruana

2009-01-01

366

Molecular cytogenetic analysis of Agropyron elongatum chromatin in wheat germplasm specifying resistance to wheat streak mosaic virus  

Microsoft Academic Search

Three lines derived from wheat (6x) x Agropyron elongatum (10x) that are resistant to wheat streak mosaic virus (WSMV) were analyzed by chromosome pairing, banding, and in situ hybridization. Line CI15321 was identified as a disomic substitution line where wheat chromosome 1D is replaced by Ag. elongatum chromosome 1Ae-1. Line 87-94-1 is a wheat-Ag. elongatum ditelosomic addition 1Ae-1L. Line CI15322

J. Jiang; B. Friebe; H. S. Dhaliwal; T. J. Martin; B. S. Gill

1993-01-01

367

Effects of maize inoculation with Fusarium verticillioides and with two bacterial biocontrol agents on seedlings growth and antioxidative enzymatic activities  

Microsoft Academic Search

Maize (Zea mays L.) is a staple food for the majority of the world's population and different diseases may affect its emergence, growth and development. Fusarium verticillioides (Sacc.) Nirenberg (Teleomorph: Gibberella moniliformis Wineland) is the most commonly reported fungal species infecting this crop. The present work analyzes the bioprotective role of two bacterial agents, Bacillus amyloliquefaciens and Microbacterium oleovorans, against

Paola Pereira; Sabrina G. Ibáñez; Elizabeth Agostini; Miriam Etcheverry

2011-01-01

368

IDENTIFYING A NATURAL SUPPRESSOR OF CELL DEATH IN MAIZE: IMPLICATIONS FOR GENE DISCOVERY, DIVERSITY EVALUATION AND BEYOND  

Technology Transfer Automated Retrieval System (TEKTRAN)

Penetrance and expressivity of Mendelian mutants is often influenced by the genome in which they reside. In maize, this is most evident with disease lesion mimic mutants (les) which spontaneously form symptoms resembling infectious encounters. For instance, the same les mutation may have a lethal ph...

369

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

PubMed

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

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

2011-04-11

370

Long-term follow-up of choroidal neovascularization secondary to angioid streaks: case series and literature review  

PubMed Central

Background The purpose of this paper is to report the clinical course of choroidal neovascularization (CNV) secondary to angioid streaks and the outcomes in response to different treatment modalities. Methods This was a case series of two consecutive patients (four eyes) with CNV secondary to angioid streaks. Visual acuity, ophthalmological examination, color photographs, fluorescein angiography, and optical coherence tomography were used to assess the outcomes of treatment. Results Two eyes were treated with photodynamic therapy for subfoveal choroidal neovascular membrane, one eye underwent thermal laser photocoagulation for extrafoveal CNV followed by intravitreal bevacizumab for subfoveal CNV, and one eye underwent intravitreal bevacizumab for subfoveal CNV. The follow-up period was 4–6 years. The final visual acuities of all eyes were 20/300 or worse with large submacular fibrosis. Conclusion CNV secondary to angioid streaks in these two patients had a poor prognosis despite undergoing different types of treatment. Poor outcome was likely related to frequent recurrence and newly developed CNV, which remained a clinical concern in these cases.

Al-Rashaed, Saba; Arevalo, J Fernando

2012-01-01

371

Maize pollen is an important allergen in occupationally exposed workers  

PubMed Central

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

2011-01-01

372

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

373

[Detection of genetic modification in maize and maize products by ELISA-test].  

PubMed

Enzyme immunoassay methods--TRAIT Test--was applied for detection of genetic modification in maize seeds and foodstuffs, which have been produced from this crop. TRAIT Test is based on the identification GMO protein Cry 1Ab produced by a gene derived from Bacillus thuringiensis (Bt) incorporated into insect resistant corn grain. The experiment was carried out on maize standards and foodstuffs from Warsaw market. The positive result was obtained for one maize product, which was not labelled as GMO. The presence of GMO material was approximately equal to 1%. In conclusion, this test is proper for fast routine qualitative (yes/no) determination GMO material in maize seeds and unprocessed food products. PMID:15052732

Urbanek-Kar?owska, Bogumi?a; Sawilska-Rautenstrauch, Dorota; Jedra, Ma?gorzata; Badowski, Pawe?

2003-01-01

374

Production and characterization of maize chromosome 9 radiation hybrids derived from an oat-maize addition line.  

PubMed Central

In maize (Zea mays L., 2n = 2x = 20), map-based cloning and genome organization studies are often complicated because of the complexity of the genome. Maize chromosome addition lines of hexaploid cultivated oat (Avena sativa L., 2n = 6x = 42), where maize chromosomes can be individually manipulated, represent unique materials for maize genome analysis. Maize chromosome addition lines are particularly suitable for the dissection of a single maize chromosome using radiation because cultivated oat is an allohexaploid in which multiple copies of the oat basic genome provide buffering to chromosomal aberrations and other mutations. Irradiation (gamma rays at 30, 40, and 50 krad) of a monosomic maize chromosome 9 addition line produced maize chromosome 9 radiation hybrids (M9RHs)-oat lines possessing different fragments of maize chromosome 9 including intergenomic translocations and modified maize addition chromosomes with internal and terminal deletions. M9RHs with 1 to 10 radiation-induced breaks per chromosome were identified. We estimated that a panel of 100 informative M9RHs (with an average of 3 breaks per chromosome) would allow mapping at the 0. 5- to 1.0-Mb level of resolution. Because mapping with maize chromosome addition lines and radiation hybrid derivatives involves assays for the presence or absence of a given marker, monomorphic markers can be quickly and efficiently mapped to a chromosome region. Radiation hybrid derivatives also represent sources of region-specific DNA for cloning of genes or DNA markers.

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

2000-01-01

375

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

376

Intravitreal ranibizumab for the treatment of choroidal neovascularisation secondary to angioid streaks  

PubMed Central

Aims To assess the medium to long-term efficacy and safety of intravitreal ranibizumab for the treatment of choroidal neovascularisation (CNV) secondary to angioid streaks (AS). Methods A total of 12 eyes of nine patients treated with intravitreal ranibizumab (0.5?mg in 0.05?ml) for CNV secondary to AS were retrospectively identified. Efficacy of treatment was determined by changes in best-corrected LogMAR visual acuity (BCVA) and optical coherence tomography. Changes with respect to baseline BCVA were defined as improved or reduced with a gain or loss of more than 10 letters, respectively, or stable if remaining within 10 letters. Results Over a mean follow-up of 21.75 months (range: 1–54), patients received mean 5.75 (range: 2–15) intravitreal ranibizumab injections per affected eye. BCVA improved in three eyes (25%), stabilised in eight eyes (66.67%), and deteriorated in one eye (8.33%). There was no significant change in central retinal thickness (CRT) over the follow-up period (P=0.1072). No drug-related systemic side effects were recorded. Conclusion The long-term treatment of CNV secondary to AS with intravitreal ranibizumab showed a stabilisation in CRT and an improvement or stabilisation of BCVA. The absence of systemic side effects was reassuring. Further long-term prospective studies are required to validate these findings.

Shah, M; Amoaku, W M K

2012-01-01

377

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

SciTech Connect

Metavinculin is an alternatively spliced isoform of vinculin that has a 68-residue insert in its tail domain (1134 total residues) and is exclusively expressed in cardiac and smooth muscle tissue, where it plays important roles in myocyte adhesion complexes. Mutations in the metavinculin-specific insert are associated with dilated cardiomyopathy (DCM) in man. Crystals of a DCM-associated mutant of full-length selenomethionine-labeled metavinculin grown by hanging-drop vapor diffusion diffracted poorly and were highly sensitive to radiation, preventing the collection of a complete X-ray diffraction data set at the highest possible resolution. Streak-seeding markedly improved the stability, crystal-growth rate and diffraction quality of DCM-associated mutant metavinculin crystals, allowing complete data collection to 3.9 {angstrom} resolution. These crystals belonged to space group P4{sub 3}2{sub 1}2, with two molecules in the asymmetric unit and unit-cell parameters a = b = 170, c = 211 {angstrom}, {alpha} = {beta} = {gamma} = 90{sup o}.

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

2012-06-28

378

Lucerne transient streak virus RNA and its translation in rabbit reticulocyte lysate and wheat germ extract.  

PubMed

Two abundant, encapsidated RNAs of lucerne transient streak virus (LTSV) are the 1.5 x 10(6) molecular weight (Mr) linear RNA-1 and both circular (RNA-2) and linear (RNA-3) forms of a 0.15 x 10(6) Mr viroid-like RNA. Two additional discrete minor RNAs, Mr 0.35 x 10(6) and 0.07 x 10(6), and a heterogeneous mixture of RNAs in the Mr range 0.05 to 1.0 x 10(6) are reported. Principal polypeptides translated from unfractionated LTSV RNA in rabbit reticulocyte lysate were of Mr 105,000 (p105), 78,000 (p78), and 33,000 (p33), the last not easily detected after translation in wheat germ extracts. All apparently are encoded in RNA-1. However, p33, which was precipitated by antibody of LTSV particles and presumably is the major capsid protein, was more readily translated from a smaller, most likely the Mr 0.35 x 10(6), RNA. Partial proteolysis and other tests indicate that p105 has a carboxyl terminal extension of p78 amino acid sequences and that neither shares sequences with p33. No translation products were attributed to RNA-2, RNA-3 or the Mr 0.07 x 10(6) RNA. PMID:18639026

Morris-Krsinich, B A; Forster, R L

1983-07-15

379

Longitudinal beam profile measurements at CTF3 using a streak camera  

NASA Astrophysics Data System (ADS)

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

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

2006-09-01

380

Line and streak detection on polished and textured surfaces using line integrals  

NASA Astrophysics Data System (ADS)

In this paper, a framework for detecting lines in a polished or textured substrate is proposed. Modules for image capture, rectification, enhancement, and line detection are included. If the surface being examined is specular (mirror-like), the image capture will be restricted, that is, the camera has to be fixed off-axis in the zenith direction. A module for image rectification and projection is included to overcome this limitation in order to yield an orthographic image. In addition, a module for image enhancement that includes high-boost is employed to improve the edge sharpness and decrease the spatial noise in the image. Finally, a line-integral technique is applied to find the confidence vectors that represent the spatial positions of the lines of interest. The Full-Width at Half-Max (FWHM) approximation is applied to determine the corresponding lines in a target image. Experimental results show that our technique has an effective performance on synthetic and real images. Print quality assessment is the main application of the proposed algorithm; however, it can be used to detect lines/ streak in prints, on substrate or any type of media where lines are visible.

Erkilinc, M. Sezer; Jaber, Mustafa; Saber, Eli; Pearson, Robert

2011-02-01

381

Streak spectroscopy and velocimetry of electrically exploded Ni/Al laminates  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

382

Areawide suppression of European corn borer with Bt maize reaps savings to non-Bt maize growers.  

PubMed

Transgenic maize engineered to express insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) has become widely adopted in U.S. agriculture. In 2009, Bt maize was planted on more than 22.2 million hectares, constituting 63% of the U.S. crop. Using statistical analysis of per capita growth rate estimates, we found that areawide suppression of the primary pest Ostrinia nubilalis (European corn borer) is associated with Bt maize use. Cumulative benefits over 14 years are an estimated $3.2 billion for maize growers in Illinois, Minnesota, and Wisconsin, with more than $2.4 billion of this total accruing to non-Bt maize growers. Comparable estimates for Iowa and Nebraska are $3.6 billion in total, with $1.9 billion for non-Bt maize growers. These results affirm theoretical predictions of pest population suppression and highlight economic incentives for growers to maintain non-Bt maize refugia for sustainable insect resistance management. PMID:20929774

Hutchison, W D; Burkness, E C; Mitchell, P D; Moon, R D; Leslie, T W; Fleischer, S J; Abrahamson, M; Hamilton, K L; Steffey, K L; Gray, M E; Hellmich, R L; Kaster, L V; Hunt, T E; Wright, R J; Pecinovsky, K; Rabaey, T L; Flood, B R; Raun, E S

2010-10-01

383

RNA Interference-Based Transgenic Maize Resistant to Maize Dwarf Mosaic Virus  

Microsoft Academic Search

Maize dwarf mosaic virus (MDMV) is a widespread pathogenic virus that causes serious loss of yield in maize (Zea mays). RNA interference (RNAi) triggered by hairpin RNA (hpRNA) transcribed from a transgenic inverted-repeat sequence is an effective\\u000a way to defend against viruses in plants. In this study, an hpRNA expression vector containing a sense arm and an antisense\\u000a arm of

Zhi-Yong Zhang; Feng-Ling Fu; Lin Gou; Han-Guang Wang; Wan-Chen Li

2010-01-01

384

Comparative Analysis of the Performance of Aspergillus flavus on Resistant and Susceptible Maize Genotypes during Infection  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus, a mycotoxicogenic fungal genus, produces carcinogenic aflatoxins in crops like peanuts and maize. Development of fungal resistant maize cultivars is one strategy used to decrease contamination. Successful development and identification of resistant maize genotypes requires evaluation o...

385

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

Code of Federal Regulations, 2010 CFR

...false Certified seed potatoes, and seed corn or maize. 10.57 Section 10.57...ETC. General Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification...

2009-04-01

386

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

Code of Federal Regulations, 2013 CFR

...false Certified seed potatoes, and seed corn or maize. 10.57 Section 10.57...ETC. General Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification...

2013-04-01

387

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...

388

Domestication process of maize continues in guatemala  

Microsoft Academic Search

The early Amerind, prescientific farmer, without the knowledge of sexual reproduction in plants, improved maize from a wild ancestor, and modern plant breeders are continuing to improve it in a similar continuum. I consider domestication to be a process, not an act. The domestication process is defined here as the continuing, human-controlled, evolutionary process of the modification of the genotype

Carl L. Johannessen

1982-01-01

389

Nuclear mutations affecting plastoquinone accumulation in maize  

Microsoft Academic Search

We have isolated and characterized two nuclear mutations which affect plastoquinone accumulation in maize. The mutations, hcf103 and hcf114, modify the same genetic locus. Plants homozygous for either mutant allele exhibit reduced PS II electron transport activity, reduced variable chlorophyll fluorescence and reduced delayed fluorescence yield. In these ways, hcf103 and hcf114 resemble previously described PS II mutants which lack

William B. Cook; Donald Miles

1992-01-01

390

Morphotypes of friable embryogenic maize callus  

Microsoft Academic Search

Friable, embryogenic callus cultures of maize are normally maintained as a heterogeneous mixture of various morphotypes in different stages of development (Fransz and Schel 1991). With stringent selection during subculture, three Type II callus morphotypes have been enriched and maintained. Cultured tissue segments from the three morphotypes referred to as pre-embryogenic, early embryogenic, and late embryogenic were analyzed using light

M. E. Welter; D. S. Clayton; M. A. Miller; J. E Petolino

1995-01-01

391

Maize canopies under two soil water regimes  

Microsoft Academic Search

The degree of coupling between the plant canopy and the atmosphere is indicative of the ability of the two systems to exchange momentum, energy, and mass. In terms of water vapor and CO2 exchange, it characterizes the extent to which stomatal and canopy conductance may control transpiration and CO2 assimilation. In the present work, the degree of coupling of maize

Pasquale Steduto; Theodore C Hsiao

1998-01-01

392

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...

393

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...

394

REGISTRATION OF MAIZE GERMPLASM LINE MP717  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize (Zea mays L.) germplasm line Mp717 was released by USDA-ARS and the Mississippi Agricultural and Forestry Experiment Station in July 2005 as a source of resistance to Aspergillus flavus infection and aflatoxin contamination. Mp717 was developed from a cross of MP420 and Tx601 by selfing for ei...

395

Diallel analysis of aflatoxin accumulation in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxin, a toxin produced by the fungus Aspergillus flavus Link: Fries, occurs naturally in maize, Zea mays L. It is a potent carcinogen, and its presence markedly reduces the value of grain. Host plant resistance to A. flavus infection and subsequent aflatoxin accumulation is generally conside...

396

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.

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

2013-01-01

397

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

2013-06-20

398

Tripsacum-Maize Interaction: A Novel Cytogenetic System  

PubMed Central

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

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

1974-01-01

399

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

Microsoft Academic Search

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

Barrett P. Brenton; Robert R. Paine

2007-01-01

400

Foliar Diseases of Apiaceae Crops in Coastal California  

Technology Transfer Automated Retrieval System (TEKTRAN)

The number of outbreaks of leaf spot, blight and streak diseases on celery, cilantro, fennel and parsley has been increasing throughout central coastal California and particularly in Monterey County since 2002. Two different bacterial pathogens (Pseudomonas syringae pv. apii, and P. syringae pv. cor...

401

Genetic Characterization of a Core Set of a Tropical Maize Race Tuxpe?o for Further Use in Maize Improvement  

PubMed Central

The tropical maize race Tuxpeño is a well-known race of Mexican dent germplasm which has greatly contributed to the development of tropical and subtropical maize gene pools. In order to investigate how it could be exploited in future maize improvement, a panel of maize germplasm accessions was assembled and characterized using genome-wide Single Nucleotide Polymorphism (SNP) markers. This panel included 321 core accessions of Tuxpeño race from the International Maize and Wheat Improvement Center (CIMMYT) germplasm bank collection, 94 CIMMYT maize lines (CMLs) and 54 U.S. Germplasm Enhancement of Maize (GEM) lines. The panel also included other diverse sources of reference germplasm: 14 U.S. maize landrace accessions, 4 temperate inbred lines from the U.S. and China, and 11 CIMMYT populations (a total of 498 entries with 795 plants). Clustering analyses (CA) based on Modified Rogers Distance (MRD) clearly partitioned all 498 entries into their corresponding groups. No sub clusters were observed within the Tuxpeño core set. Various breeding strategies for using the Tuxpeño core set, based on grouping of the studied germplasm and genetic distance among them, were discussed. In order to facilitate sampling diversity within the Tuxpeño core, a minicore subset of 64 Tuxpeño accessions (20% of its usual size) representing the diversity of the core set was developed, using an approach combining phenotypic and molecular data. Untapped diversity represents further use of the Tuxpeño landrace for maize improvement through the core and/or minicore subset available to the maize community.

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

2012-01-01

402

2D Optical Streaking for Ultra-Short Electron Beam Diagnostics  

SciTech Connect

We propose a novel approach to measure short electron bunch profiles at micrometer level. Low energy electrons generated during beam-gas ionization are simultaneously modulated by the transverse electric field of a circularly-polarized laser, and then they are collected at a downstream screen where the angular modulation is converted to a circular shape. The longitudinal bunch profile is simply represented by the angular distribution of the electrons on the screen. We only need to know the laser wavelength for calibration and there is no phase synchronization problem. Meanwhile the required laser power is also relatively low in this setup. Some simulations examples and experimental consideration of this method are discussed. At Linac Coherent Light Source (LCLS), an S-band RF transverse deflector (TCAV) is used to measure the bunch length with a resolution 10 femtosecond (fs) rms. An X-band deflector (wavelength 2.6cm) is proposed recently to improve the resolution. However, at the low charge operation mode (20pC), the pulse length can be as short as fs. It is very challenging to measure femtosecond and sub-femtosecond level bunch length. One of the methods is switching from RF to {mu}m level wavelength laser to deflect the bunch. A powerful laser ({approx}10s GW) is required to deflect such a high energy beam (GeV) in a wiggler. Synchronization is another difficulty: the jitter between the bunch and the laser can be larger than the laser wavelength, which makes single-shot measurement impossible. To reduce the laser power, we propose to use ionized electrons from high energy electron beam and gas interaction for high energy electron bunch diagnostics. Similarly, the femtosecond X-ray streak camera uses X-ray ionization electrons to measure the X-ray pulse. The electrons generated by beam-gas ionization have low energy (eVs). Therefore, a lower laser power is possible to deflect such low energy electrons. Note that there is no field ionization in our case. To avoid field ionization, which occurs in plasma case, gases species with high field ionization threshold should be considered. For a linear polarized laser, the kick to the ionized electrons depends on the phase of the laser when the electrons are born and the unknown timing jitter between the electron beam and laser beam makes the data analysis very difficult. Here we propose to use a circular polarized laser to do a 2-dimensional (2D) streaking (both x and y) and measure the bunch length from the angular distribution on the screen, where the phase jitter causes only a rotation of the image on the screen without changing of the relative angular distribution. Also we only need to know the laser wavelength for calibration. A similar circular RF deflecting mode was used to measure long bunches. We developed a numerical particle-in-Cell (PIC) code to study the dynamics of ionization electrons with the high energy beam and the laser beam.

Ding, Y.T.; Huang, Z.; Wang, L.; /SLAC

2011-12-14

403

Utilizing virus-induced gene silencing for the functional characterization of maize genes during infection with the fungal pathogen Ustilago maydis.  

PubMed

While in dicotyledonous plants virus-induced gene silencing (VIGS) is well established to study plant-pathogen interaction, in monocots only few examples of efficient VIGS have been reported so far. One of the available systems is based on the brome mosaic virus (BMV) which allows gene silencing in different cereals including barley (Hordeum vulgare), wheat (Triticum aestivum), and maize (Zea mays).Infection of maize plants by the corn smut fungus Ustilago maydis leads to the formation of large tumors on stem, leaves, and inflorescences. During this biotrophic interaction, plant defense responses are actively suppressed by the pathogen, and previous transcriptome analyses of infected maize plants showed comprehensive and stage-specific changes in host gene expression during disease progression.To identify maize genes that are functionally involved in the interaction with U. maydis, we adapted a VIGS system based on the Brome mosaic virus (BMV) to maize at conditions that allow successful U. maydis infection of BMV pre-infected maize plants. This setup enables quantification of VIGS and its impact on U. maydis infection using a quantitative real-time PCR (q(RT)-PCR)-based readout. PMID:23386294

van der Linde, Karina; Doehlemann, Gunther

2013-01-01

404

Observations of Wire Array Dynamics on the Z Accelerator using Optical Frames and Streak Images  

NASA Astrophysics Data System (ADS)

We present the first laser shadowgraph measurements of wire array dynamics on Z using a sub-nanosecond visible framing camera to record 6 sequential frames. Simultaneously, a streak camera records the radial intensity versus time at a fixed height on the wire array. This set of complimentary diagnostics provides new possibilities for the direct observation of wire array ablation and stagnation dynamics with a 20-MA current driver. We observe a strong disagreement between experimental results and a 0-D compression trajectory. The compression starts later in time and has a steeper trajectory than the 0-D prediction due to prolonged plasma generation. Stainless steel wires are measured to expand with an initial velocity during the prepulse of 1.3 km/s. During the main pulse, the wires expansion velocity reaches values of 27 km/s. The velocity of the wire-array at stagnation is 200-400 km/s. Density perturbations are observed along the Z-axis as plasma, ablated from the wires, streams to the axis. The spatial period of this instability is 250 mm. Early in time, we observe small-scale perturbations in the wire array boundary, which transform to larger structures later in the implosion. Similar instabilities are observed in the creation of plasma on the return current conductor, which contains the wire array. Possible origins and growth rates for the instabilities, such as Rayleigh Taylor, the thermo-electric effect and other mechanisms will be discussed. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL8500.

Bliss, David E.; Sarkisov, Gennady S.; Rogowski, Sonrisa T.; Jones, Brent M.; Deeney, Chris; Nash, Thomas J.; Struve, Kenneth W.; McDaniel, Dillon H.

2003-10-01

405

Rapid decomposition of maize detritus in agricultural headwater streams  

Microsoft Academic Search

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

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

2009-01-01

406

Molecular marker diversity among current and historical maize inbreds  

Microsoft Academic Search

Advanced-cycle pedigree breeding has caused maize (Zea mays L.) inbreds to become more-elite but more-narrow genetically. Our objectives were to evaluate the genetic distance among\\u000a current and historical maize inbreds, and to estimate how much genetic diversity has been lost among current inbreds. We selected\\u000a eight maize inbreds (B14, B37, B73, B84, Mo17, C103, Oh43 and H99) that largely represented

H. Lu; R. Bernardo

2001-01-01

407

Transcriptome analysis of embryo maturation in maize  

PubMed Central

Background Maize is one of the most important crops in the world. With the exponentially increasing population and the need for ever increased food and feed production, an increased yield of maize grain (as well as rice, wheat and other grains) will be critical. Maize grain development is understood from the perspective of morphology, hormone responses, and storage reserve accumulation. This includes various studies on gene expression during embryo development and maturation but a global study of gene expression of the embryo has not been possible until recently. Transcriptome analysis is a powerful new tool that can be used to understand the genetic basis of embryo maturation. Results We undertook a transcriptomic analysis of normal maturing embryos at 15, 21 and 27 days after pollination (DAP), of one elite maize germplasm line that was utilized in crosses to transgenic plants. More than 19,000 genes were analyzed by this method and the challenge was to select subsets of genes that are vitally important to embryo development and maturation for the initial analysis. We describe the changes in expression for genes relating to primary metabolic pathways, DNA synthesis, late embryogenesis proteins and embryo storage proteins, shown through transcriptome analysis and confirmed levels of transcription for some genes in the transcriptome using qRT-PCR. Conclusions Numerous genes involved in embryo maturation have been identified, many of which show changes in expression level during the progression from 15 to 27 DAP. An expected array of genes involved in primary metabolism was identified. Moreover, more than 30% of transcripts represented un-annotated genes, leaving many functions to be discovered. Of particular interest are the storage protein genes, globulin-1, globulin-2 and an unidentified cupin family gene. When expressing foreign proteins in maize, the globulin-1 promoter is most often used, but this cupin family gene has much higher expression and may be a better candidate for foreign gene expression in maize embryos. Results such as these allow identification of candidate genes and promoters that may not otherwise be available for use. mRNA seq data archived in NCBI SRA; Accession number: ACC=SRA060791 subid=108584.

2013-01-01

408

Close Split of Sorghum and Maize Genome Progenitors  

PubMed Central

It is generally believed that maize (Zea mays L. ssp. mays) arose as a tetraploid; however, the two progenitor genomes cannot be unequivocally traced within the genome of modern maize. We have taken a new approach to investigate the origin of the maize genome. We isolated and sequenced large genomic fragments from the regions surrounding five duplicated loci from the maize genome and their orthologous loci in sorghum, and then we compared these sequences with the orthologous regions in the rice genome. Within the studied segments, we identified 11 genes that were conserved in location, order, and orientation. We performed phylogenetic and distance analyses and examined the patterns of estimated times of divergence for sorghum and maize gene orthologs and also the time of divergence for maize orthologs. Our results support a tetraploid origin of maize. This analysis also indicates contemporaneous divergence of the ancestral sorghum genome and the two maize progenitor genomes about 11.9 million years ago (Mya). On the basis of a putative conversion event detected for one of the genes, tetraploidization must have occurred before 4.8 Mya, and therefore, preceded the major maize genome expansion by gene amplification and retrotransposition.

Swigonova, Zuzana; Lai, Jinsheng; Ma, Jianxin; Ramakrishna, Wusirika; Llaca, Victor; Bennetzen, Jeffrey L.; Messing, Joachim

2004-01-01

409

Brownish inclusions and dark streaks in Libyan Desert Glass: Evidence for high-temperature melting of the target rock  

NASA Astrophysics Data System (ADS)

Dark streaks and different types of inclusions in Libyan Desert Glass (LDG) collected from the LDG strewn field in Egypt were investigated. Rare transparent spherules enclosed in the glassy matrix are characterized by concentric cracks, irregular internal cracks, intense twinning, and considerable amounts of Ti and Al. Raman spectra show that the spherules are ?-cristobalite. Their occurrence together with lechatelierite indicates quick heating of the source rock to at least 1550°C, followed by rapid quenching leading to crystallization of ?-cristobalite, which upon cooling inverted into ?-cristobalite. Brownish inclusions are irregularly shaped, elongated objects with smooth contacts to the surrounding glass. They contain small roundish to elliptical droplets, and a few larger angular grains, which compositionally and according to their Raman spectra most closely resemble low-Ca, Al-rich orthopyroxene. Composition and texture of the orthopyroxene suggest that the brownish inclusions formed by incomplete melting of an Al-rich orthopyroxene bearing precursor, e.g., mafic phases present in desert surface sands or also of orthopyroxene-bearing granulite dykes in the LDG target. Experimental data on Ca-poor enstatite also support that the inclusions were heated to about 1550°C. Analyses of dark streaks in LDG reveal high abundances of Al, Ti, Mn, Cr, Fe, and Ni and a pronounced correlation between the abundances of Cr, Mn, Fe, and Ni. As the Fe/Ni, Mn/Ni, and Cr/Ni ratios are all clearly nonchondritic, the source of this material is most likely terrestrial and the dark streaks studied here represent a different type of schlieren compared to those which contain a meteoritic component. These findings suggest LDG formation during a short high-temperature event. Melting of Al-rich orthopyroxene bearing target material seems to suggest an asteroid impact rather than a near-surface airburst.

Greshake, Ansgar; Koeberl, Christian; Fritz, Jörg; Reimold, W. Uwe

2010-06-01

410

Motility and fertility of the subtropical freshwater fish streaked prochilod (Prochilodus lineatus) sperm cryopreserved in powdered coconut water.  

PubMed

Streaked prochilod (Prochilodus lineatus) is a freshwater fish inhabiting many South American rivers. The objective was to determine the effectiveness of coconut water (ACP), combined with methylglycol, as a freezing medium for streaked prochilod sperm. A secondary objective was to compare a computer-assisted sperm analyzer (CASA) system versus subjective microscropic examination as a means of assessing sperm motility. As a control, glucose and methylglycol was used, according to our previous study. Sperm diluted in each medium was loaded into 0.5 mL straws, frozen in liquid nitrogen vapor (in a dry shipper), and stored in liquid nitrogen (-196 degrees C). Half of the samples were evaluated for sperm motility, both subjectively and with CASA; the remainder were evaluated for fertility. There was no difference (P > 0.05) between subjective or CASA assessment of post-thaw sperm motility. Although sperm motility was higher in sperm cryopreserved in ACP (85%) than in glucose (75%), cryopreservation in either extender yielded similar fertilization rates (46-48%) and sperm velocities. There were positive correlations (r = 0.56-0.8) between all sperm velocities and fertilization rate. In conclusion, streaked prochilod sperm cryopreserved in glucose or ACP and methylglycol was fertile, and thus could be used for research or commercial settings. Furthermore, although the CASA system provided objective data regarding sperm motility, in the present study, subjective evaluation of sperm motility was practical and a good indication of sperm quality; it could readily be done by well-trained personnel under field or laboratory conditions. PMID:20494428

Viveiros, A T M; Nascimento, A F; Orfão, L H; Isaú, Z A

2010-05-23

411

Pseudorhabdosynochus quadratus n. sp. (Monogenea: Diplectanidae) from the white-streaked grouper Epinephelus ongus (Bloch) (Perciformes: Serranidae) off New Caledonia.  

PubMed

Pseudorhabdosynochus quadratus n. sp. is described from three specimens collected from the gills of a rarely examined fish, the white-streaked grouper Epinephelus ongus (Bloch), caught off Nouméa, New Caledonia. The description is based on Berlese slides and observations of live specimens; the soft parts are not described in detail. The species is characterised by a compact, sclerotised vagina with a robust trumpet, short primary canal, two closely associated chambers linked by a very short secondary canal and small accessory structure. PMID:21487950

Schoelinck, Charlotte; Justine, Jean-Lou

2011-04-13

412

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

SciTech Connect

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

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

1990-07-01

413

Investigation of pinch dynamics in plasma-focus discharges by means of fast-streak-and fast-frame-cameras  

Microsoft Academic Search

In order to investigate the Plasma-Focus (PF) pinch dynamics within the large PF-1000 facility the use was made of fast streak-and\\u000a frame-cameras operated as the routine optical diagnostic tools. They enabled images of a current-sheath (CS) layer and the\\u000a PF-pinch to be recorded within the visible range (VR) at chosen instants of the investigated PF-discharges. The measurements\\u000a were carried out

M. Borowiecki; B. Bienkowska; S. Jednoróg; L. Karpinski; M. Paduch; M. Scholz; M. J. Sadowski

2006-01-01

414

Preliminary performance measurements for a streak camera with a large-format direct-coupled charge-coupled device readout  

SciTech Connect

The University of Rochester's Laboratory for Laser Energetics (Rochester, New York) is leading an effort to develop a modern, fully automated streak camera. Characterization of a prototype camera shows spatial resolution better than 20 lp/mm, temporal resolution of 12 ps, line-spread function of 40 {mu}m (full width at half maximum) contrast transfer ratio of 60% at 10 lp/mm, system gain of 101 charge-coupled device electrons per photoelectron, and a dynamic range of 500 for a 2 ns window.

Lerche, R.A.; McDonald, J.W.; Griffith, R.L.; Dios, G. Vergel de; Andrews, D.S.; Huey, A.W.; Bell, P.M.; Landen, O.L.; Jaanimagi, P.A.; Boni, R. [Lawrence Livermore National Laboratory, Box 808, Livermore, California 94551 (United States); University of Rochester Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623 (United States)

2004-10-01

415

Isolation of a subterranean clover mottle virus-like satellite RNA from lucerne infected with lucerne transient streak virus.  

PubMed

A circular, viroid-like satellite RNA (sat RNA) was detected in lucerne transient streak virus (LTSV), from lucerne in South Australia. It was larger than the previously reported sat RNA of LTSV, being similar in size and sequence homology to the 388 nucleotide sat RNA previously shown to be encapsidated by subterranean clover mottle virus (SCMoV) isolated from subterranean clover in Western Australia. This indicates that under field conditions, very similar sat RNAs can be associated with two distantly related sobemoviruses, LTSV and SCMoV. The natural hosts of these viruses are lucerne and subterranean clover, respectively. PMID:1697331

Dall, D J; Graddon, D J; Randles, J W; Francki, R I

1990-08-01

416

Iron bioavailability of maize hemoglobin in a Caco-2 cell culture model.  

PubMed

Maize ( Zea mays ) is an important staple crop in many parts of the world but has low iron bioavailability, in part due to its high phytate content. Hemoglobin is a form of iron that is highly bioavailable, and its bioavailability is not inhibited by phytate. It was hypothesized that maize hemoglobin is a highly bioavailable iron source and that biofortification of maize with iron can be accomplished by overexpression of maize globin in the endosperm. Maize was transformed with a gene construct encoding a translational fusion of maize globin and green fluorescent protein under transcriptional control of the maize 27 kDa ?-zein promoter. Iron bioavailability of maize hemoglobin produced in Escherichia coli and of stably transformed seeds expressing the maize globin-GFP fusion was determined using an in vitro Caco-2 cell culture model. Maize flour fortified with maize hemoglobin was found to have iron bioavailability that is not significantly different from that of flour fortified with ferrous sulfate or bovine hemoglobin but is significantly higher than unfortified flour. Transformed maize grain expressing maize globin was found to have iron bioavailability similar to that of untransformed seeds. These results suggest that maize globin produced in E. coli may be an effective iron fortificant, but overexpressing maize globin in maize endosperm may require a different strategy to increase bioavailable iron content in maize. PMID:23834908

Bodnar, Anastasia L; Proulx, Amy K; Scott, M Paul; Beavers, Alyssa; Reddy, Manju B

2013-07-19

417

Rheological changes in nixtamalised maize starch  

Microsoft Academic Search

In Mexico, a great deal of maize lines are growth, most of them go through the process of nixtamalisation (lye treatment at\\u000a boiling temperature) to produce masa, which is used to mainly elaborate tortillas. During this process, the heat treatment\\u000a brings about biochemical reactions, cross-links and molecular interactions that modify the physicochemical, structural and\\u000a rheological properties of the masa as

Guadalupe Méndez-Montealvo; Javier Solorza-Feria; Francisco García-Suárez; Luis Arturo Bello-Pérez

2007-01-01

418

Gibberellins and Heterosis in Maize 1  

PubMed Central

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

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

1983-01-01

419

Peptide regulation of Maize defense reponses  

Technology Transfer Automated Retrieval System (TEKTRAN)

ZmPEP1 is a peptide signal encoded by a previously uncharacterized maize gene that we have named ZmPROPEP1. The ZmPROPEP1 gene was identified by homology to the Arabidopsis AtPROPEP1 gene that encodes the precursor protein to the peptide signal AtPEP1. Together with its receptors, AtPEPR1 and AtPEP...

420

Kinetic modelling of phototropism in maize coleoptiles  

Microsoft Academic Search

Blue-light-induced phototropism of maize (Zea mays L.) coleoptiles was studied with a view to kinetic models. Red-light-grown plants were used to eliminate complication arising from the activation by blue light of phytochrome-mediated phototropism. In the first part, mathematical models were developed to explain the phototropic fluence-response data, which were obtained for the responses induced by a single unilateral pulse (30

M. Iino

1987-01-01

421

Hydrothermal carbonization of anaerobically digested maize silage  

Microsoft Academic Search

Hydrochars were prepared by hydrothermal carbonization (HTC) of maize silage previously treated at 55°C in a two-stage solid-state reactor system. The HTC was carried out in a 1-L stirred pressure reactor with pH regulation by citric acid. The treated silage carbonized at relatively mild conditions (190°C, 2h), and the hydrochars showed mainly amorphous macro-size features with a carbon content of

Jan Mumme; Lion Eckervogt; Judith Pielert; Mamadou Diakité; Fabian Rupp; Jürgen Kern

2011-01-01

422

The mycotoxin distribution in maize milling fractions under experimental conditions.  

PubMed

Mycotoxin contamination of maize and maize-based food and feed products poses a health risk to humans and animals if not adequately controlled and managed. The current study investigates the effect of dry milling on the reduction of fumonisins (FB), deoxynivalenol (DON) and zearalenone (ZEA) in maize. Five composite samples, constructed to represent different mycotoxin contamination levels were degermed yielding degermed maize and the germ. The degermed maize was milled under laboratory conditions and four major milling fractions (SPECIAL, SUPER, semolina (SEM) and milling hominy feed) collected. The whole maize, degermed maize and total hominy feed (germ+milling hominy feed) were reconstructed to ensure homogenous samples for mycotoxin analyses. For comparison, commercial dry milling fractions (whole maize, SPECIAL, SUPER and total hominy feed), collected from three South African industrial mills, were analysed for the same mycotoxins and hence a more accurate assessment of the distribution between the different milling fractions. The distribution of the mycotoxins during the experimental dry milling of the degermed maize differs, with FB mainly concentrated in the SPECIAL, DON in the SEM whereas ZEA was equally distributed between the two milling fractions. Distribution of mycotoxins between the fractions obtained during commercial dry milling generally provided similar results with the total hominy feed containing the highest and the SUPER milling fractions the lowest mycotoxin levels although variations existed. Although milling is an effective way to reduce mycotoxins in maize, kernel characteristics and resultant fungal colonisation may impact on the distribution of specific mycotoxins among the different milling fractions. Differences in industrial dry milling practices and problems encountered in sampling bulk maize remain a large problem in assessing mycotoxin contamination in milling fractions intended for human consumption. PMID:23693022

Burger, H-M; Shephard, G S; Louw, W; Rheeder, J P; Gelderblom, W C A

2013-04-11

423

Aflatoxin Regulations in a Network of Global Maize Trade  

PubMed Central

Worldwide, food supplies often contain unavoidable contaminants, many of which adversely affect health and hence are subject to regulations of maximum tolerable levels in food. These regulations differ from nation to nation, and may affect patterns of food trade. We soughtto determine whether there is an association between nations' food safety regulations and global food trade patterns, with implications for public health and policymaking. We developed a network model of maize trade around the world. From maize import/export data for 217 nations from 2000–2009, we calculated basic statistics on volumes of trade; then examined how regulations of aflatoxin, a common contaminant of maize, are similar or different between pairs of nations engaging in significant amounts of maize trade. Globally, market segregation appears to occur among clusters of nations. The United States is at the center of one cluster; European countries make up another cluster with hardly any maize trade with the US; and Argentina, Brazil, and China export maize all over the world. Pairs of nations trading large amounts of maize have very similar aflatoxin regulations: nations with strict standards tend to trade maize with each other, while nations with more relaxed standards tend to trade maize with each other. Rarely among the top pairs of maize-trading nations do total aflatoxin standards (standards based on the sum of the levels of aflatoxins B1, B2, G1, and G2) differ by more than 5 µg/kg. These results suggest that, globally, separate maize trading communities emerge; and nations tend to trade with other nations that have very similar food safety standards.

Wu, Felicia; Guclu, Hasan

2012-01-01

424

Aflatoxin regulations in a network of global maize trade.  

PubMed

Worldwide, food supplies often contain unavoidable contaminants, many of which adversely affect health and hence are subject to regulations of maximum tolerable levels in food. These regulations differ from nation to nation, and may affect patterns of food trade. We soughtto determine whether there is an association between nations' food safety regulations and global food trade patterns, with implications for public health and policymaking. We developed a network model of maize trade around the world. From maize import/export data for 217 nations from 2000-2009, we calculated basic statistics on volumes of trade; then examined how regulations of aflatoxin, a common contaminant of maize, are similar or different between pairs of nations engaging in significant amounts of maize trade. Globally, market segregation appears to occur among clusters of nations. The United States is at the center of one cluster; European countries make up another cluster with hardly any maize trade with the US; and Argentina, Brazil, and China export maize all over the world. Pairs of nations trading large amounts of maize have very similar aflatoxin regulations: nations with strict standards tend to trade maize with each other, while nations with more relaxed standards tend to trade maize with each other. Rarely among the top pairs of maize-trading nations do total aflatoxin standards (standards based on the sum of the levels of aflatoxins B(1), B(2), G(1), and G(2)) differ by more than 5 µg/kg. These results suggest that, globally, separate maize trading communities emerge; and nations tend to trade with other nations that have very similar food safety standards. PMID:23049773

Wu, Felicia; Guclu, Hasan

2012-09-25

425

Historical genomics of North American maize  

PubMed Central

Since the advent of modern plant breeding in the 1930s, North American maize has undergone a dramatic adaptation to high-input agriculture. Despite the importance of genetic contributions to historical yield increases, little is known about the underlying genomic changes. Here we use high-density SNP genotyping to characterize a set of North American maize lines spanning the history of modern breeding. We provide a unique analysis of genome-wide developments in genetic diversity, ancestry, and selection. The genomic history of maize is marked by a steady increase in genetic differentiation and linkage disequilibrium, whereas allele frequencies in the total population have remained relatively constant. These changes are associated with increasing genetic separation of breeding pools and decreased diversity in the ancestry of individual lines. We confirm that modern heterotic groups are the product of ongoing divergence from a relatively homogeneous landrace population, but show that differential landrace ancestry remains evident. Using a recent association approach, we characterize signals of directional selection throughout the genome, identifying a number of candidate genes of potential agronomic relevance. However, overall we find that selection has had limited impact on genome-wide patterns of diversity and ancestry, with little evidence for individual lines contributing disproportionately to the accumulation of favorable alleles in today's elite germplasm. Our data suggest breeding progress has mainly involved selection and recombination of relatively common alleles, contributed by a representative but limited set of ancestral lines.

van Heerwaarden, Joost; Hufford, Matthew B.; Ross-Ibarra, Jeffrey

2012-01-01

426

Brassinosteroid control of sex determination in maize  

PubMed Central

Brassinosteroids (BRs) are plant hormones that regulate growth and development. They share structural similarities with animal steroids, which are decisive factors of sex determination. BRs are known to regulate morphogenesis and environmental stress responses, but their involvement in sex determination in plants has been only speculative. We show that BRs control sex determination in maize revealed through characterization of the classical dwarf mutant nana plant1 (na1), which also feminizes male flowers. na1 plants carry a loss-of-function mutation in a DET2 homolog—a gene in the BR biosynthetic pathway. The mutant accumulates the DET2-specific substrate (24R)-24-methylcholest-4-en-3-one with a concomitant decrease of downstream BR metabolites. Treatment of wild-type maize plants with BR biosynthesis inhibitors completely mimicked both dwarf and tasselseed phenotypes of na1 mutants. Tissue-specific na1 expression in anthers throughout their development supports the hypothesis that BRs promote masculinity of the male inflorescence. These findings suggest that, in the monoecious plant maize, BRs have been coopted to perform a sex determination function not found in plants with bisexual flowers.

Hartwig, Thomas; Chuck, George S.; Fujioka, Shozo; Klempien, Antje; Weizbauer, Renate; Potluri, Devi Prasad V.; Choe, Sunghwa; Johal, Gurmukh S.; Schulz, Burkhard

2011-01-01

427

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.

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

1997-01-01

428

Telomere-mediated chromosomal truncation in maize  

PubMed Central

Direct repeats of Arabidopsis telomeric sequence were constructed to test telomere-mediated chromosomal truncation in maize. Two constructs with 2.6 kb of telomeric sequence were used to transform maize immature embryos by Agrobacterium-mediated transformation. One hundred seventy-six transgenic lines were recovered in which 231 transgene loci were revealed by a FISH analysis. To analyze chromosomal truncations that result in transgenes located near chromosomal termini, Southern hybridization analyses were performed. A pattern of smear in truncated lines was seen as compared with discrete bands for internal integrations, because telomeres in different cells are elongated differently by telomerase. When multiple restriction enzymes were used to map the transgene positions, the size of the smears shifted in accordance with the locations of restriction sites on the construct. This result demonstrated that the transgene was present at the end of the chromosome immediately before the integrated telomere sequence. Direct evidence for chromosomal truncation came from the results of FISH karyotyping, which revealed broken chromosomes with transgene signals at the ends. These results demonstrate that telomere-mediated chromosomal truncation operates in plant species. This technology will be useful for chromosomal engineering in maize as well as other plant species.

Yu, Weichang; Lamb, Jonathan C.; Han, Fangpu; Birchler, James A.

2006-01-01

429

Measuring x-ray burn history with the Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER) at the National Ignition Facility (NIF)  

NASA Astrophysics Data System (ADS)

We present a new diagnostic for the National Ignition Facility (NIF) [1,2]. The Streaked Polar Instrumentation for Diagnosing Energetic Radiation (SPIDER) is an x-ray streak camera for use on almost-igniting targets, up to ~1017 neutrons per shot. It measures the x-ray burn history for ignition campaigns with the following requirements: X-Ray Energy 8-30keV, Temporal Resolution 10ps, Absolute Timing Resolution 30ps, Neutron Yield: 1014 to 1017. The features of the design are a heavily shielded instrument enclosure outside the target chamber, remote location of the neutron and EMP sensitive components, a precise laser pulse comb fiducial timing system and fast streaking electronics. SPIDER has been characterized for sweep linearity, dynamic range, temporal and spatial resolution. Preliminary DT implosion data shows the functionality of the instrument and provides an illustration of the method of burn history extraction.

Khan, S. F.; Bell, P. M.; Bradley, D. K.; Burns, S. R.; Celeste, J. R.; Dauffy, L. S.; Eckart, M. J.; Gerhard, M. A.; Hagmann, C.; Headley, D. I.; Holder, J. P.; Izumi, N.; Jones, M. C.; Kellogg, J. W.; Khater, H. Y.; Kimbrough, J. R.; Macphee, A. G.; Opachich, Y. P.; Palmer, N. E.; Petre, R. B.; Porter, J. L.; Shelton, R. T.; Thomas, T. L.; Worden, J. B.

2012-10-01

430

The use and calibration of read-out streaks to increase the dynamic range of the Swift Ultraviolet/Optical Telescope  

NASA Astrophysics Data System (ADS)

The dynamic range of photon counting micro-channel-plate (MCP) intensified charged-coupled device (CCD) instruments such as the Swift Ultraviolet/Optical Telescope (UVOT) and the XMM-Newton Optical Monitor (XMM-OM) is limited at the bright end by coincidence loss, the superposition of multiple photons in the individual frames recorded by the CCD. Photons which arrive during the brief period in which the image frame is transferred for read out of the CCD are displaced in the transfer direction in the recorded images. For sufficiently bright sources, these displaced counts form read-out streaks. Using UVOT observations of Tycho-2 stars, we investigate the use of these read-out streaks to obtain photometry for sources which are too bright (and hence have too much coincidence loss) for normal aperture photometry to be reliable. For read-out-streak photometry, the bright-source limiting factor is coincidence loss within the MCPs rather than the CCD. We find that photometric measurements can be obtained for stars up to 2.4 mag brighter than the usual full-frame coincidence-loss limit by using the read-out streaks. The resulting bright-limit Vega magnitudes in the UVOT passbands are UVW2 = 8.80, UVM2 = 8.27, UVW1 = 8.86, u = 9.76, b = 10.53, v = 9.31 and White = 11.71; these limits are independent of the windowing mode of the camera. We find that a photometric precision of 0.1 mag can be achieved through read-out streak measurements. A suitable method for the measurement of read-out streaks is described and all necessary calibration factors are given.

Page, M. J.; Kuin, N. P. M.; Breeveld, A. A.; Hancock, B.; Holland, S. T.; Marshall, F. E.; Oates, S.; Roming, P. W. A.; Siegel, M. H.; Smith, P. J.; Carter, M.; De Pasquale, M.; Symeonidis, M.; Yershov, V.; Beardmore, A. P.

2013-10-01

431

The influence of wall suction and blowing on boundary-layer laminar streaks generated by free-stream vortical disturbances  

NASA Astrophysics Data System (ADS)

The effect of mean flow wall transpiration on boundary-layer fluctuations generated by free-stream disturbances of the convected gust type is investigated numerically. The theoretical frameworks of Leib et al. [J. Fluid Mech. 380, 169 (1999)] and Ricco [J. Fluid Mech. 638, 267 (2009)], based on the linearized unsteady boundary-region equations, are adopted. It is found that wall suction has a more significant attenuating effect on the low-frequency laminar streaks, while high-frequency disturbances are brought closer to the wall, but unaffected in magnitude. A simple asymptotic result, confirmed by the numerical calculations, shows that the characteristic peak of the laminar streaks in the core of the boundary layer may be suppressed completely by suction if this is sufficiently intense. Thought experiments of the modification induced by suction on existing wind-tunnel root-mean-square data are carried out. The findings are compared with other laboratory data with wall suction, and the reasons for discrepancy are outlined.

Ricco, Pierre; Dilib, Fahad

2010-04-01

432

Integration of maize nuclear and mitochondrial DNA into the wheat genome through somatic hybridization  

Microsoft Academic Search

Protoplasts were isolated from cultured cells of wheat and maize and fused using PEG. Calli and green plants were regenerated following irradiation of the maize, and some tested positive for hybridity using morphological, isozymic and various DNA-based marker systems. Genomic in situ hybridization (GISH) of selected maize-carrying regenerants showed that some maize chromatin was dispersed throughout the wheat nuclear genome.

Chunhui Xu; Guangmin Xia; Daying Zhi; Fengning Xiang; Huimin Chen

2003-01-01

433

Maize centromere mapping: A comparison of physical and genetic strategies  

Technology Transfer Automated Retrieval System (TEKTRAN)

The location of chromosome centromeres in various maize genetic maps relative to physical maps has not been consistently and clearly identified due to the paucity of markers and low recombination in the highly heterochromatic centromeric and flanking regions. Centromere positions on seven maize chro...

434

Genetic Variation at Bx 1 Controls DIMBOA Content in Maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

The main hydroxamic acid in maize (Zea mays L.) is 2-4-hydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA). DIMBOA confers resistance to leaf-feeding by several corn borers. Most genes involved in the DIMBOA metabolic pathway are located on the short arm of chromosome 4, and QTLs involved in maize resis...

435

Role of phosphatidic acid in high temperature tolerance in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize (Zea mays, L.) germplasm exhibits large genetic variations in tolerance to high temperature (HT) stress under field conditions, but the mechanisms underling this variation are largely unknown. Based on many years of field observation, maize inbred line B76 consistently displays better toleranc...

436

Comparative population genomics of maize domestication and improvement  

Technology Transfer Automated Retrieval System (TEKTRAN)

Domestication and modern breeding represent exemplary case studies of evolution in action. Maize is an outcrossing species with a complex genome, and an understanding of maize evolution is thus relevant for both plant and animal systems. This study is the largest plant resequencing effort to date, ...

437

Maize Production and Agricultural Policies in Central America and Mexico  

Microsoft Academic Search

This paper reviews trends in maize production and consumption in Central America and Mexico in the context of the political and economic changes taking place in the region since the 1970s. The authors focus on the effects of the structural adjustment programs in the 1980s and 1990s. The analysis begins by reviewing the economic context in which maize production occurs

Gustavo Sain; Miguel A. Lopez-Pereira

1999-01-01

438

Molecular and Ultrastructural Properties of Maize White Line Virus  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper reports the complete nucleotide sequence of the genome of Maize white line mosaic virus (MWLMV) and describes the ultrastructural features of infected maize cells. The viral genome is an RNA molecule 4293 nt in size with the same structural organization of members of the Aureusvirus and ...

439

A new methionine-rich seed storage protein from maize  

Microsoft Academic Search

The endosperm of maize (Zea mays) seeds contains sev- era1 classes of alcohol-soluble storage proteins called zeins, which together make up nearly 50% of the total seed pro- tein content. The abundance of the zeins and their low content of the essential amino acid Lys is responsible for the relatively poor nutritional quality of maize protein. However, zeins rich in

Chok-Fun Chui; S. Carl Falco

1995-01-01

440

Gibberellins promote vegetative phase change and reproductive maturity in maize  

Microsoft Academic Search

Postembryonic shoot development in maize (Zea mays 1.) is divided into a juvenile vegetative phase, an adult vegetative phase, and a reproductive phase that differ in the expression of many morphological traits. A reduction in the endogenous levels of bio- active gibberellins (CAs) conditioned by any one of the dwarfl, dwarf3, dwarf5, or anfher earl mutations in maize delays the

Matthew M. S. Evans; R. Scott Poethig

1995-01-01

441

Structure and Properties of an Engineered Transketolase from Maize  

Microsoft Academic Search

The gene specifying plastid transketolase (TK) of maize (Zea mays) was cloned from a cDNA library by southern blotting using a heterologous probe from sorghum (Sorghum bicolor). A recombinant fusion protein comprising thioredoxin of Escherichia coli and mature TK of maize was expressed at a high level in E. coli and cleaved with thrombin, affording plastid TK. The protein in

Stefan Gerhardt; Stefanie Echt; Marco Busch; Gunter Auerbach; Gerd Bader; William F. Martin; Adelbert Bacher; Robert Huber; Markus Fischer

2003-01-01

442

Transposition of the Maize Controlling Element ``Activator'' in Tobacco  

Microsoft Academic Search

Transposition of the maize autonomous controlling element Activator (Ac) and a nonautonomous derivative, Dissociation (Ds), was investigated in tobacco cells. Tobacco protoplasts were transformed with Ti-plasmid vectors that contained Ac or Ds flanked by short maize wx gene sequences. The structures of the elements and surrounding wx and T-DNA sequences were investigated in nine Ac and five Ds tobacco transformants

Barbara Baker; Jeff Schell; Horst Lorz; Nina Fedoroff

1986-01-01

443

Maize Stem Tissues: Cell Wall Concentration and Composition during Development  

Microsoft Academic Search

Grass maturation results in reduced cell wall degradability by ruminant livestock. Using a specific internode of maize (Zea mays L.) stems as a model, the pattern of grass stem tissue and cell wall de- velopment was characterized. The fourth elongated internode above ground level from three maize hybrids was sampled at 10 stages of deve