Lack of class I H-2 antigens in cells transformed by radiation leukemia virus is associated with methylation and rearrangement of H-2 DNA

Transformation of murine thymocytes by radiation leukemia virus is associated with reduced expression of the class I antigens encoded in the major histocompatibility complex (MHC) and increased methylation and altered restriction enzyme patterns of MHC DNA. These changes may play a role in host susceptibility to virus-induced leukemogenesis and accord with the notion that viral genomes play a regulatory function when they integrate adjacent to histocompatibiity genes

The genetic diversity and evolution of field pea (Pisum) studied by high throughput retrotransposon based insertion polymorphism (RBIP) marker analysis

BACKGROUND: The genetic diversity of crop species is the result of natural selection on the wild progenitor and human intervention by ancient and modern farmers and breeders. The genomes of modern cultivars, old cultivated landraces, ecotypes and wild relatives reflect the effects of these forces and provide insights into germplasm structural diversity, the geographical dimension to species diversity and the process of domestication of wild organisms. This issue is also of great practical importance for crop improvement because wild germplasm represents a rich potential source of useful under-exploited alleles or allele combinations. The aim of the present study was to analyse a major Pisum germplasm collection to gain a broad understanding of the diversity and evolution of Pisum and provide a new rational framework for designing germplasm core collections of the genus. RESULTS: 3020 Pisum germplasm samples from the John Innes Pisum germplasm collection were genotyped for 45 retrotransposon based insertion polymorphism (RBIP) markers by the Tagged Array Marker (TAM) method. The data set was stored in a purpose-built Germinate relational database and analysed by both principal coordinate analysis and a nested application of the Structure program which yielded substantially similar but complementary views of the diversity of the genus Pisum. Structure revealed three Groups (1-3) corresponding approximately to landrace, cultivar and wild Pisum respectively, which were resolved by nested Structure analysis into 14 Sub-Groups, many of which correlate with taxonomic sub-divisions of Pisum, domestication related phenotypic traits and/or restricted geographical locations. Genetic distances calculated between these Sub-Groups are broadly supported by principal coordinate analysis and these, together with the trait and geographical data, were used to infer a detailed model for the domestication of Pisum. CONCLUSIONS: These data provide a clear picture of the major distinct gene pools into which the genus Pisum is partitioned and their geographical distribution. The data strongly support the model of independent domestications for P. sativum ssp abyssinicum and P. sativum. The relationships between these two cultivated germplasms and the various sub-divisions of wild Pisum have been clarified and the most likely ancestral wild gene pools for domesticated P. sativum identified. Lastly, this study provides a framework for defining global Pisum germplasm which will be useful for designing core collections

Genome-wide association analysis of grain yield-associated traits in a pan-European barley cultivar collection

A collection of 379 Hordeum vulgare cultivars, comprising all combinations of spring and winter growth habits with two and six row ear type, was screened by genome wide association analysis to discover alleles controlling traits related to grain yield. Genotypes were obtained at 6,810 segregating gene-based single nucleotide polymorphism (SNP) loci and corresponding field trial data were obtained for eight traits related to grain yield at four European sites in three countries over two growth years. The combined data were analyzed and statistically significant associations between the traits and regions of the barley genomes were obtained. Combining this information with the high resolution gene map for barley allowed the identification of candidate genes underlying all scored traits and superposition of this information with the known genomics of grain trait genes in rice resulted in the assignation of 13 putative barley genes controlling grain traits in European cultivated barley. Several of these genes are associated with grain traits in both winter and spring barley

GENETIC DIVERSITY OF FABA BEAN (VICIA FABA L.) POPULATIONS ESTIMATED BY ISOZYMIC AND MOLECULAR MARKERS: RELATIONSHIP BETWEEN THE TWO METHODS

In our previous studies, the genetic diversity among nine Tunisian faba bean (Vicia faba) populations was analysed using isozymes and sequence-specific amplification polymorphism (SSAP) markers. The objectives of this study were to compare the application and utility of isozymes and sequence-specific amplification polymorphism (SSAP) techniques for analysis of genetic diversity among nine Tunisian faba bean (Vicia faba) populations. A high genetic diversity within populations was detected by both isozymes (SOD, 6-PGD, ME, EST, SKDH, FDH and GDH) and (SSAP) markers (PDR1, Tps19 and Tvf4). For all populations, the genetic diversity revealed by SSAP was more pronounced than that detected with isozyme, based on polymorphic profiles. The analyses of correspondance between the tow methodes based in Mantel test revealed a low correlation ( r=0.177). The low correspondance indicated the absence of correlation and therfore the complimentarit

Barley yield formation under abiotic stress depends on the interplay between flowering time genes and environmental cues

Abstract Since the dawn of agriculture, crop yield has always been impaired through abiotic stresses. In a field trial across five locations worldwide, we tested three abiotic stresses, nitrogen deficiency, drought and salinity, using HEB-YIELD, a selected subset of the wild barley nested association mapping population HEB-25. We show that barley flowering time genes Ppd-H1, Sdw1, Vrn-H1 and Vrn-H3 exert pleiotropic effects on plant development and grain yield. Under field conditions, these effects are strongly influenced by environmental cues like day length and temperature. For example, in Al-Karak, Jordan, the day length-sensitive wild barley allele of Ppd-H1 was associated with an increase of grain yield by up to 30% compared to the insensitive elite barley allele. The observed yield increase is accompanied by pleiotropic effects of Ppd-H1 resulting in shorter life cycle, extended grain filling period and increased grain size. Our study indicates that the adequate timing of plant development is crucial to maximize yield formation under harsh environmental conditions. We provide evidence that wild barley alleles, introgressed into elite barley cultivars, can be utilized to support grain yield formation. The presented knowledge may be transferred to related crop species like wheat and rice securing the rising global food demand for cereals

Evidence of inverted-gravity driven variation in predictive sensorimotor function.

We move our eyes to place the fovea into the part of a viewed scene currently of interest. Recent evidence suggests that each human has signature patterns of eye movements like handwriting which depend on their sensitivity, allocation of attention and experience. Use of implicit knowledge of how earth's gravity influences object motion has been shown to aid dynamic perception. We used a projected ball tracking task with a plain background offering no context cues to probe the effect of acquired experience about physical laws of gravitation on performance differences of 44 participants under a simulated gravity and an atypical (upward) antigravity condition. Performance measured by the unsigned difference between instantaneous eye and stimulus positions (RMSE) was consistently worse in the antigravity condition. In the vertical RMSE, participants took about 200ms longer to improve to the best performance for antigravity compared to gravity trials. The antigravity condition produced a divergence of individual performance which was correlated with levels of questionnaire based quantified traits of schizotypy but not control traits. Grouping participants by high or low traits revealed a negative relationship between schizotypy traits level and both initiation and maintenance of tracking, a result consistent with trait related impoverished sensory prediction. The findings confirm for the first time that where cues enabling exact estimation of acceleration are unavailable, knowledge of gravity contributes to dynamic prediction improving motion processing. With acceleration expectations violated, we demonstrate that antigravity tracking could act as a multivariate diagnostic window into predictive brain function