Microarray analysis of spring barley cultivars displaying differing sensitivity to physiological leaf spot (PLS)

peer-reviewedPhysiological leaf spot (PLS) is a disorder of spring barley (Hordeum vulgare L.), which has become more pronounced in recent years. The initial symptoms are small chlorotic/brown spots on the upper four leaves, which may develop into necrotic lesions with an irregular shape. As PLS occurs on leaves that are directly exposed to sunlight, it is thought that high light stress could be a trigger for the condition. This study concentrates on two cultivars, Cooper and Crusader, which display differential sensitivity to PLS. Biochemical measurements and enzyme assays revealed substantial difference in levels of ascorbate, type III peroxidases, and superoxide dismutase between the chosen cultivars during the 2003 growing season. A global gene expression study, using these field samples, was performed by microarray analysis. This supported the biochemical findings and highlighted additional sets of genes differentially expressed between the cultivars. Transcripts of particular interest, which appeared, included calcium signalling genes, cold-responsive genes and those involved in the assembly of Photosystem I. We conclude that susceptibility to PLS is related to levels of expression of genes with a role in countering the effects of oxidative stress.Teagasc Walsh Fellowship Programm

Sperm competition in mated first generation hermaphrodite females of the HP 88 strain of Heterorhabditis (Nematoda : Heterorhabditidae) and progeny sex ratios in mated and unmated females

Nous avons utilisé un mutant "obèse" pour étudier le processus de la fécondation chez #Heterorhabditis. Nous avons observé que, chez les femelles hermaphrodites de première génération inséminées, les spermatozoïdes provenant du mâle possèdent un avantage dans leur compétition avec les spermatozoïdes provenant de la femelle hermaphrodite elle-même. Les observations en microscopie optique ont montré qu'il n'y a pas de spermathèque chez les femelles hermaphrodites de première génération et que les spermatozoïdes introduits sont stockés dans la partie proximale de l'ovotestis où ils se mélangent avec les spermatozoïdes d'origine hermaphrodite. Les spermatozoïdes introduits ont des pseudopodes bien développés et paraissent plus actifs que les spermatozoïdes d'origine hermaphrodite. Les femelles amphimictiques de deuxième génération possèdent une spermathèque où sont stockés les spermatozoïdes introduits, et non dans la partie proximale de l'ovaire ou de l'utérus. La proportion des sexes dans la descendance croisée de femelles tant hermaphrodites qu'amphimictiques varie de 2,2 à 6,6 mâles pour mille descendants, chiffres très différents du rapport 1/1 qui aurait pu être attendu dans la descendance croisée de mâles hétérogamiques. Des mâles, en proportion 20 à 30 fois supérieure, ont été observés dans la descendance d'hermaphrodites autofécondés. Ainsi, l'origine des spermatozoïdes, suivant qu'ils proviennent de mâles ou d'individus hermaphrodites, influencent nettement la proportion des sexes de la descendance chez la souche HP 88 d'#Heterorhabditis. (Résumé d'auteur

Studies of in vitro Propagation Systems for Sugar Beet

Commercial cultivars of Beta vulgaris (sugar beet) and an annual diploid line, as well as some breeder's materials developed in Ireland, were used in studies on several in vitro culture procedures. An efficient micropropagation system, based on cytokinin-mediated release of apical dominance in axenic shoot cultures, was established for all genotypes. Callus was initiated by several combinations of naphthalene acetic acid and benzyl aminopurine, and was maintained indefinitely on a defined medium. Shoot regeneration from callus developed from petiole explants was achieved using two different protocols but somatic embryogenesis was not observed. The best frequency of shoot regeneration achieved was 16% of calli responding with 1 to 30 adventitious buds developing on responsive calli. A number of apparently normal, rooted plants were obtained from regenerants. Out of 200 ovaries dissected from flowering spikes of cv. Hilma, two ovules developed into plantlets after a two-step culture procedure

Characterisation of the entomopathogenic nematode Heterorhabditis (Nematoda : Heterorhabditidae) from Ireland and Britain by molecular and cross-breeding techniques, and the occurrence of the genus in these islands

Des examens de sol ont été effectués en Irlande et en Grande-Bretagne pour rechercher les nématodes du genre #Heterorhabditis. Des échantillons des sols prélevés sur des sites sablonneux furent pourvus de larves de #Galleria mellonella comme appâts. Des #Heterorhabditis furent collectés sur 18 sites sur 169 en Irlande, 2 sur 51 dans le nord de l'Ecosse et 9 sur 20 dans le sud du Pays de Galle. Tous les sites positifs sont situés sur le littoral ; aucun #Heterorhabditis n'a été détecté dans les échantillons prélevés dans 40 sites situés à l'intérieur des terres. La totalité des 76 isolats recueillis au cours de ces analyses ont été identifiés comme appartenant au groupe irlandais d'#Heterorhabditis, à l'aide de méthodes de concentration isoélectrique, de restriction de l'ADN et d'hybridation. Aucun #Heterohabditis appartenant au groupe de l'Europe du nord-ouest n'a été recueilli. Cependant, un isolat recueilli par d'autres chercheurs et provenant du sud de l'Angleterre a été identifié comme appartenant à ce groupe. Les membres du groupe irlandais ne se croisent généralement pas avec les membres du groupe de l'Europe du nord-ouest, bien que des juvéniles infestants fertiles aient été produits dans un nombre limité (3/15) de croisements entre ces groupes. (Résumé d'auteur

SOCS and Herpesviruses, With Emphasis on Cytomegalovirus Retinitis

Suppressor of cytokine signaling (SOCS) proteins provide selective negative feedback to prevent pathogeneses caused by overstimulation of the immune system. Of the eight known SOCS proteins, SOCS1 and SOCS3 are the best studied, and systemic deletion of either gene causes early lethality in mice. Many viruses, including herpesviruses such as herpes simplex virus and cytomegalovirus, can manipulate expression of these host proteins, with overstimulation of SOCS1 and/or SOCS3 putatively facilitating viral evasion of immune surveillance, and SOCS suppression generally exacerbating immunopathogenesis. This is particularly poignant within the eye, which contains a diverse assortment of specialized cell types working together in a tightly controlled microenvironment of immune privilege. When the immune privilege of the ocular compartment fails, inflammation causing severe immunopathogenesis and permanent, sight-threatening damage may occur, as in the case of AIDS-related human cytomegalovirus (HCMV) retinitis. Herein we review how SOCS1 and SOCS3 impact the virologic, immunologic, and/or pathologic outcomes of herpesvirus infection with particular emphasis on retinitis caused by HCMV or its mouse model experimental counterpart, murine cytomegalovirus (MCMV). The accumulated data suggests that SOCS1 and/or SOCS3 can differentially affect the severity of viral diseases in a highly cell-type-specific manner, reflecting the diversity and complexity of herpesvirus infection and the ocular compartment

Fault and magmatic interaction within Iceland's western rift over the last 9kyr

We present high-resolution 'Chirp' sub-bottom profiler data from Thingvallavatn, a lake in Iceland's western rift zone. These data are combined with stratigraphic constraints from sediment cores to show that movement on normal faults since 9 ka are temporally correlated with magmatic events, indicating that movements were controlled by episodic dyke intrusion. Sediment depo-centres and the focus of subsidence migrated westwards over 3-4 kyr towards the locus of subsequent brittle failure. We interpret this subsidence as related to dyke intrusion a few km along strike, originating from the Hengill volcanic system, which occurred prior to major dyking, faulting and subsidence within the lake at 1.9 ka

Automatic extraction of angiogenesis bioprocess from text

Motivation: Understanding key biological processes (bioprocesses) and their relationships with constituent biological entities and pharmaceutical agents is crucial for drug design and discovery. One way to harvest such information is searching the literature. However, bioprocesses are difficult to capture because they may occur in text in a variety of textual expressions. Moreover, a bioprocess is often composed of a series of bioevents, where a bioevent denotes changes to one or a group of cells involved in the bioprocess. Such bioevents are often used to refer to bioprocesses in text, which current techniques, relying solely on specialized lexicons, struggle to find

The DLV System for Knowledge Representation and Reasoning

This paper presents the DLV system, which is widely considered the state-of-the-art implementation of disjunctive logic programming, and addresses several aspects. As for problem solving, we provide a formal definition of its kernel language, function-free disjunctive logic programs (also known as disjunctive datalog), extended by weak constraints, which are a powerful tool to express optimization problems. We then illustrate the usage of DLV as a tool for knowledge representation and reasoning, describing a new declarative programming methodology which allows one to encode complex problems (up to $\Delta^P_3$-complete problems) in a declarative fashion. On the foundational side, we provide a detailed analysis of the computational complexity of the language of DLV, and by deriving new complexity results we chart a complete picture of the complexity of this language and important fragments thereof. Furthermore, we illustrate the general architecture of the DLV system which has been influenced by these results. As for applications, we overview application front-ends which have been developed on top of DLV to solve specific knowledge representation tasks, and we briefly describe the main international projects investigating the potential of the system for industrial exploitation. Finally, we report about thorough experimentation and benchmarking, which has been carried out to assess the efficiency of the system. The experimental results confirm the solidity of DLV and highlight its potential for emerging application areas like knowledge management and information integration.Comment: 56 pages, 9 figures, 6 table