2,721 research outputs found
Search for partial resistance to leaf rust in a collection of ancient Spanish wheats
No full textA collection of 917 accessions of Spanish durum and bread wheat was screened for resistance to leaf rust (Puccinia triticina) under field conditions at three locations. Resistance levels ranged from very low to very high, high susceptibility being most frequent. Relative disease severity (referred to the most susceptible accession = 100 %) was lower than 20 % in about 6 % of the accessions in each location. In the collection most of the lines (84 %)displayed a susceptible infection type. A final selection of seven accessions (one of them durum) displaying low severity level in the field and high infection type in a growth chamber was chosen for further studies. High levels of partial resistant with longer latency period and high percentage of early aborted colonies without necrosis were found. They might be used in breeding programmes
Characterization of Lr46, a gene conferring partial resistance to wheat leaf rust
No full textComponents of resistance conferred by the Lr46 gene, reported as causing "slow rusting" resistance to leaf rust in wheat, were studied and compared with the effects of Lr34 and genes for quantitative resistance in cv. Akabozu. Lr34 is a gene that confers non-hypersensitive type of resistance. The effect of Lr46 resembles that of Lr34 and other wheats reported with partial resistance. At macroscopic level, Lr46 produced a longer latency period than observed on the susceptible recurrent parent Lalbahadur, and a reduction of the infection frequency not associated with hypersensitivity. Microscopically, Lr46 increased the percentage of early aborted infection units not associated with host cell necrosis and decreased the colony size. The effect of Lr46 is comparable to that of Lr34 in adult plant stage, but in seedling stage its effect is weaker than that of Lr34
Partial resistance to leaf rust in a collection of ancient Spanish barleys
No full textA collection of 569 Spanish barley accessions was screened for resistance to leaf rust (Puccinia hordei Otth) in the field at Cordoba during the 2000-2001 season. The level of resistance ranged from very low to very high. In 14% of the accessions the relative AUDPC (L94 = 100%) was lower than 10%. Selected accessions that were most resistant in the field, were tested in the seedling stage under controlled conditions. Macroscopic components of resistance indicated that six lines had a high level of partial resistance close to check cv. Vada and one line a similar level of partial resistance. Histological studies indicated that the resistance was based on a high percentage of early aborted colonies and reduction in colony size without plant cell necrosis. Three of the selected lines showed high percentage of plant cell necrosis associated with established colonies, which indicates a combination of prehaustorial resistance with late acting incomplete posthaustorial resistance. Although the new barley varieties already incorporate some partial resistance, new sources of partial resistance like these are needed to improve durability of the resistance
Rethinking live electronic music: a DJ perspective
No full textThe author critiques the conventional understanding of live electronic music through empirical research on his own DJ practice and investigates others working in the field. In reviewing the opinions of theorists and practitioners in both the live electronic music genre and DJ-ing he argues against the body/machine dialectic that has determined much of the thinking in the former. The author forms a notion of the DJ as a real-time composer working beyond traditional binary distinctions who brings the human body and machine into a mutual relationship. Through practice-led research he charts an investigation beginning in physical human gesture and culminating in digital machine repetition. He concludes that mechanical and digital repetition do not obscure human agency in the production of live works and that this concern is imaginary
Lifecycle, biology and diversity of Puccinia boroniae in Western Australia
No full textThe rust fungi (Uredinales, Basidiomycota) are an expansive and diverse group of fungal species, consisting of approximately 7000 different species in over 160 different genera. Fungi of the genus Puccinia represent a large proportion of these rust fungi, many species of which are well known for their role in causing massive yield and subsequent economic losses in agricultural crops worldwide. Puccinia boroniae is one such rust fungus and is a significant pathogen of several species of Boronia (Rutaceae), a native Australian wildflower grown commercially in Western Australia as a cutflower. Complete control of the rust pathogen is rarely achieved using chemical fungicides. Improving the level of disease control is vital for the long-term sustainability and future growth of the Boronia industry, and requires an understanding of the pathogen. The objectives of this thesis were to investigate aspects of the epidemiology, the biology and the diversity of P. boroniae in Western Australia, providing a broad understanding of the pathogen, which in turn could be employed to improve disease control.
The lifecycle of P. boroniae was conclusively shown to be microcyclic by artificial inoculation of Boronia heterophylla with basidiospores released from germinating teliospores suspended over the host plant. Telia developed on the leaves within 21 days, with no intermediate rust spore stages (pycnial, uredial or aecial) observed. Rarely, low numbers of pycnia of P. boroniae were observed on field specimens collected from leaves of B. megastigma cultivated at one commercial floriculture plantation. This was the first record of pycnia of P. boroniae; however, as pycnia were not observed on other host species or plantations, or formed during controlled inoculation trials, their functional role in the lifecycle is currently unresolved.
Telia were subepidermal, erumpent and pulvinate, amphigenous on leaves, stems and parts of developing flower buds, and generally persistent year round. Intracellular hyphae resembling monokaryotic haustoria (M-haustoria) were observed in leaf mesophyll cells beneath and adjacent of telia. Occasionally Sphaerellopsis filum (teleomorph Eudarluca caricis), a known mycoparasite of rust fungi, was observed on the telia. Under favourable conditions, teliospores germinated immediately without a period of dormancy, with fully mature basidiospores formed within 3-4 h after telia were exposed to moisture. Basidial development in P. boroniae was unusual, in that only one basidiospore was formed from each germinating teliospore cell. Immature teliospores were initially binucleate undergoing karyogamy to form a single large (presumably diploid) nucleus that migrated into the developing metabasidium. Both binucleate and tetranucleate metabasidia were observed, with mature uninucleate, binucleate and tetranucleate basidiospores present. At this stage, more research is required to understand the complete nuclear behaviour during teliospore germination. The morphology of the pycnial stage was similar to other Puccinia species, being ampulliform, subepidermal, amphigenous and arranged in small clusters on leaves of B. megastigma. However, the spine-like periphyses protruded through stomata as apposed to penetrating the leaf epidermis.
Environmental conditions favouring the formation and dispersal of basidiospores were assessed in vitro and under field conditions with a spore catcher. Under field conditions, basidiospores were captured from February-August 2004, with peak numbers and daily incidence occurring during autumn (April/May) when the average temperature range was 9.1-22.6 degrees C. Daily basidiospore numbers were positively correlated with minimum daily temperature and total daily rainfall. A distinct diurnal periodicity of release was observed, with numbers peaking on average between 02:00 and 05:00 hrs. The hourly release of basidiospores was positively correlated with relative humidity and negatively correlated with temperature and evaporation. This data was in agreement with the in vitro experimentation, which showed that basidiospore formation occurred between 10-25 plus-minus 1 degrees C (apparent optimal temperature of 15-20 plus-minus 1 degrees C) with telia incubated in continuous darkness promoting a greater number of basidiospores.
The level of genetic variation of P. boroniae in Western Australia was assessed by PCR-RFLP of the nuclear ribosomal intergenic spacer 2 (IGS2) region. Two RFLP profiles were observed, separating three specimens (Group 1) from the remaining population (Group 2). Sequence analysis indicated that point mutations at endonuclease recognition sites were responsible for the changes in RFLP profile. Group 2 specimens had been collected from the same host species (B. megastigma) and plantation, and it is suggested that the variant specimens may constitute a subspecies of P. boroniae, isolated by geographic location and possibly host (cultivar) specificity. Further analysis, primarily pathogenicity trials, is needed to confirm this.
This study has improved our knowledge regarding the rust fungus P. boroniae and has laid strong foundations for future research into several aspects of the biology, epidemiology and population variation. The implications of the key findings of this research, with an emphasis on the management of P. boroniae in commercial situations, are discussed
An eQTL analysis of partial resistance to Puccinia hordei in barley
No full textBackground - Genetic resistance to barley leaf rust caused by Puccinia hordei involves both R genes and quantitative trait loci. The R genes provide higher but less durable resistance than the quantitative trait loci. Consequently, exploring quantitative or partial resistance has become a favorable alternative for controlling disease. Four quantitative trait loci for partial resistance to leaf rust have been identified in the doubled haploid Steptoe (St)/Morex (Mx) mapping population. Further investigations are required to study the molecular mechanisms underpinning partial resistance and ultimately identify the causal genes.Methodology/Principal Findings - We explored partial resistance to barley leaf rust using a genetical genomics approach. We recorded RNA transcript abundance corresponding to each probe on a 15K Agilent custom barley microarray in seedlings from St and Mx and 144 doubled haploid lines of the St/Mx population. A total of 1154 and 1037 genes were, respectively, identified as being P. hordei-responsive among the St and Mx and differentially expressed between P. hordei-infected St and Mx. Normalized ratios from 72 distant-pair hybridisations were used to map the genetic determinants of variation in transcript abundance by expression quantitative trait locus (eQTL) mapping generating 15685 eQTL from 9557 genes. Correlation analysis identified 128 genes that were correlated with resistance, of which 89 had eQTL co-locating with the phenotypic quantitative trait loci (pQTL). Transcript abundance in the parents and conservation of synteny with rice allowed us to prioritise six genes as candidates for Rphq11, the pQTL of largest effect, and highlight one, a phospholipid hydroperoxide glutathione peroxidase (HvPHGPx) for detailed analysis.Conclusions/Significance - The eQTL approach yielded information that led to the identification of strong candidate genes underlying pQTL for resistance to leaf rust in barley and on the general pathogen response pathway. The dataset will facilitate a systems appraisal of this host-pathogen interaction and, potentially, for other traits measured in this populatio
hpDJ: An automated DJ with floorshow feedback
No full textMany radio stations and nightclubs employ Disk-Jockeys (DJs) to provide a continuous uninterrupted stream or “mix” of dance music, built from a sequence of individual song-tracks. In the last decade, commercial pre-recorded compilation CDs of DJ mixes have become a growth market. DJs exercise skill in deciding an appropriate sequence of tracks and in mixing 'seamlessly' from one track to the next. Online access to large-scale archives of digitized music via automated music information retrieval systems offers users the possibility of discovering many songs they like, but the majority of consumers are unlikely to want to learn the DJ skills of sequencing and mixing. This paper describes hpDJ, an automatic method by which compilations of dance-music can be sequenced and seamlessly mixed by computer, with minimal user involvement. The user may specify a selection of tracks, and may give a qualitative indication of the type of mix required. The resultant mix can be presented as a continuous single digital audio file, whether for burning to CD, or for play-out from a personal playback device such as an iPod, or for play-out to rooms full of dancers in a nightclub. Results from an early version of this system have been tested on an audience of patrons in a London nightclub, with very favourable results. Subsequent to that experiment, we designed technologies which allow the hpDJ system to monitor the responses of crowds of dancers/listeners, so that hpDJ can dynamically react to those responses from the crowd. The initial intention was that hpDJ would monitor the crowd’s reaction to the song-track currently being played, and use that response to guide its selection of subsequent song-tracks tracks in the mix. In that version, it’s assumed that all the song-tracks existed in some archive or library of pre-recorded files. However, once reliable crowd-monitoring technology is available, it becomes possible to use the crowd-response data to dynamically “remix” existing song-tracks (i.e, alter the track in some way, tailoring it to the response of the crowd) and even to dynamically “compose” new song-tracks suited to that crowd. Thus, the music played by hpDJ to any particular crowd of listeners on any particular night becomes a direct function of that particular crowd’s particular responses on that particular night. On a different night, the same crowd of people might react in a different way, leading hpDJ to create different music. Thus, the music composed and played by hpDJ could be viewed as an “emergent” property of the dynamic interaction between the computer system and the crowd, and the crowd could then be viewed as having collectively collaborated on composing the music that was played on that night. This en masse collective composition raises some interesting legal issues regarding the ownership of the composition (i.e.: who, exactly, is the author of the work?), but revenue-generating businesses can nevertheless plausibly be built from such technologies
Characterisation of DJ1 (PARK7) in human brain: possible involvement in idiopathic Parkinson's disease and other neurodegenerative disorders
No full textMutations in the DJ‐1 gene can induce the development of early‐onset Parkinson's disease
(PD) through a loss of protein function. Currently any possible role for DJ‐1 in sporadic PD
remains undetermined. To address this, we have studied the characteristics and activities of
DJ‐1 in post‐mortem human brain tissue in order to gain insights into its contribution to the
development of PD and other neurodegenerative disorders.
Western blotting revealed DJ‐1 protein expression to be reduced in several brain regions
associated with PD pathology including nigra, striatum and frontal cortex. Similarly levels of
DJ‐1 mRNA were also shown to also be lower in PD striatum and frontal cortex suggesting a
transcriptional regulation of protein expression in human brain. Further analysis of DJ‐1
gene expression showed PD related changes to be variable throughout the brain, with
regions like the amygdala and entorhinal cortex displaying an up‐regulation. DJ‐1 protein
was also shown to undergo increased oxidation in PD cases, highlighting the elevated
oxidative stress conditions in PD. By using immunoprecipitation to investigate a possible role for DJ‐1 as an in vivo regulator
of translation, we found DJ‐1 protein associates with RNA transcripts for selenoproteins,
PTEN/Akt pathway components and mitochondrial subunits of complex 1. Protein levels for
a number of these transcripts were altered in PD tissue without any parallel change in
mRNA levels. DJ‐1 is reportedly involved in a diverse range of cellular activities and its
proclivity to associate with multiple RNA species provides a simple biochemical mechanism
for this. Moreover it demonstrates that under conditions of elevated oxidative stress, DJ‐1
can instigate a rapid and compartmentalised up‐regulation of pro‐survival proteins in a
transcriptionally independent manner.
Analysis of DJ‐1 in tauopathies showed co‐localisation with 3R and 4R tau, implicating a
possible chaperone function for DJ‐1. Unlike in PD, no altered expression of DJ‐1 mRNA and
protein was observed
Characterization of a wheat HSP70 gene and its expression in response to stripe rust infection and abiotic stresses
No full textMembers of the family of 70-kD heat shock proteins (HSP70 s) play various stress-protective roles in plants. In this study, a wheat HSP70 gene was isolated from a suppression subtractive hybridization (SSH) cDNA library of wheat leaves infected by Puccinia striiformis f. sp. tritici. The gene, that was designated as TaHSC70, was predicted to encode a protein of 690 amino acids, with a molecular mass of 73.54 KDa and a pI of 5.01. Further analysis revealed the presence of a conserved signature that is characteristic for HSP70s and phylogenetic analysis demonstrated that TaHSC70 is a homolog of chloroplast HSP70s. TaHSC70 mRNA was present in leaves of both green and etiolated wheat seedlings and in stems and roots. The transcript level in roots was approximately threefold less than in leaves but light–dark treatment did not charge TaHSC70 expression. Following heat shock of wheat seedlings at 40°C, TaHSC70 expression increased in leaves of etiolated seedlings but remained stable at the same level in green seedlings. In addition, TaHSC70 was differentially expressed during an incompatible and compatible interaction with wheat-stripe rust, and there was a transient increase in expression upon treatment with methyl jasmonate (MeJA) treatment. Salicylic acid (SA), ethylene (ET) and abscisic acid (ABA) treatments had no influence on TaHSC70 expression. These results suggest that TaHSC70 plays a role in stress-related responses, and in defense responses elicited by infection with stripe rust fungus and does so via a JA-dependent signal transduction pathway
Interview of author Phenderson Dj\ue8l\ued Clark at the Zora Neale Hurston Festival in Eatonville, Florida
No full textAward winning author and founding member of FIYAH Literary Magazine, Phenderson Dj\ue8l\ued Clark, is interviewed by Grace Chun, project coordinator at University of Florida Samuel Proctor Oral History Program, as part of the 2020 Zora Neale Hurston Festival in Eatonville, Florida. Mr. Clark shares how his time in Trinidad, his exposure to afro-creole folktales, Hindu stories, Muslim festivals as well as his exposure to Twilight Zone and old horror movies from his parents nurtured a deep interest in the fantastic. Mr. Clark defines afrofuturism as something to do with the future, whether it is how Black people will exist in the future or futuristic ideas. He describes how his writing fits more with retro-afrofuturism, where you imbue the past with future elements and explore a past that never was. Mr. Clark says that afrofuturism offers a way to resist the kind of future in a world like now and how to form a resistance against it; it empowers people to imagine a different future, a possibility of a different future. He also talks about how afrofuturism extends beyond literary work into music and other creative forms
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