Alternative splicing of hepatitis B virus: A novel virus/host interaction altering liver immunity

This work was supported by grants from Institut National de la Sante et de la Recherche Medicale (Inserm) – France, Universite Pierre et Marie Curie (UPMC) – France, Agence National de la Recherche sur le Sida et les Hepatites (ANRS) – France (n° N14015DR) and PHC-Tassili (11MDU826). MD was supported by ANRS (grant ASA14013DRA). YM was supported by French Ministry for Higher Education and Research and by the Ligue contre le Cancer (grant n° GB/MA/VSP-10504)

Farmers' attitudes and landscape change: evidence from the abandonment of terraced cultivations on Lesvos, Greece

Agricultural landscapes are the product of the interaction of the natural environment of an area and the practices of its farmers. In this paper, farmers' practices are examined in order to describe and understand processes of landscape change in terraced fields on the island of Lesvos, Greece. We examine the changes of the terraced fields of each farmer and the reasons for these changes, practices concerning the maintenance of terraces and how farmers view this landscape change. The concept of farming systems is used to link farmers' practices at the farm level with changes at the landscape level. Data come from research via questionnaires to farmers in order to record their practices, to explore changes in land use and the landscape elements and the reasons behind these changes, and finally to record their opinions on the landscape change that result. Findings indicate that although farm households in the case study areas depend on farming incomes by very different degrees, they employ similar cultivation and landscape management practices. At the same time, "hobby" farm households may be more prone to abandonment of fields and negligence of landscape elements (here terraces)

Unicircular structure of the Brassica hirta mitochondrial genome

Restriction mapping studies reveal that the mitochondrial genome of white mustard ( Brassica hirta ) exists in the form of a single circular 208 kb chromosome. The B. hirta genome has only one copy of the two sequences which, in several related Brassica species, are duplicated and undergo intramolecular recombination. This first report of a plant mitochondrial DNA that does not exist in a multipartite structure indicates that high frequency intramolecular recombination is not an obligatory feature of plant mitochondrial genomes. Heterologous filter hybridizatios reveal that the mitochondrial genomes of B. hirta and B. campestris have diverged radically in sequence arrangement, as the result of approximately 10 large inversions. At the same time, however, the two genomes are similar in size, sequence content, and primary sequence.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46962/1/294_2004_Article_BF00384620.pd

Alternative splicing of hepatitis B virus: A novel virus/host interaction altering liver immunity

Background & Aims: Hepatitis B virus (HBV) RNA can undergo alternative splicing, but the relevance of this post-transcriptional regulation remains elusive. The mechanism of HBV alternative splicing regulation and its impact on liver pathogenesis were investigated. Methods: HBV RNA-interacting proteins were identified by RNA pull-down, combined with mass spectrometry analysis. HBV splicing regulation was investigated in chemically and surgically induced liver damage, in whole HBV genome transgenic mice and in hepatoma cells. Viral and endogenous gene expression were quantified by quantitative reverse transcription polymerase chain reaction, Western blot and enzyme-linked immunosorbent assay. Resident liver immune cells were studied by fluorescence-activated cell sorting. Results: HBV pregenomic RNA-interacting proteins were identified and 15% were directly related to the splicing machinery. Expression of these splicing factors was modulated in HBV transgenic mice with liver injuries and contributed to an increase of the HBV spliced RNA encoding for HBV splicing-generated protein (HBSP). HBSP transgenic mice with chemically induced liver fibrosis exhibited attenuated hepatic damage. The protective effect of HBSP resulted from a decrease of inflammatory monocyte/macrophage recruitment through downregulation of C-C motif chemokine ligand 2 (CCL2) expression in hepatocytes. In human hepatoma cells, the ability of HBSP to control CCL2 expression was confirmed and maintained in a whole HBV context. Finally, viral spliced RNA detection related to a decrease of CCL2 expression in the livers of HBV chronic carriers underscored this mechanism. Conclusion: The microenvironment, modified by liver injury, increased HBSP RNA expression through splicing factor regulation, which in turn controlled hepatocyte chemokine synthesis. This feedback mechanism provides a novel insight into liver immunopathogenesis during HBV infection. Lay summary: Hepatitis B virus persists for decades in the liver of chronically infected patients. Immune escape is one of the main mechanisms developed by this virus to survive. Our study highlights how the crosstalk between virus and liver infected cells may contribute to this immune escape

The sequence of rice chromosomes 11 and 12, rich in disease resistance genes and recent gene duplications

Background: Rice is an important staple food and, with the smallest cereal genome, serves as a reference species for studies on the evolution of cereals and other grasses. Therefore, decoding its entire genome will be a prerequisite for applied and basic research on this species and all other cereals. Results: We have determined and analyzed the complete sequences of two of its chromosomes, 11 and 12, which total 55.9 Mb (14.3% of the entire genome length), based on a set of overlapping clones. A total of 5,993 non-transposable element related genes are present on these chromosomes. Among them are 289 disease resistance-like and 28 defense-response genes, a higher proportion of these categories than on any other rice chromosome. A three-Mb segment on both chromosomes resulted from a duplication 7.7 million years ago (mya), the most recent large-scale duplication in the rice genome. Paralogous gene copies within this segmental duplication can be aligned with genomic assemblies from sorghum and maize. Although these gene copies are preserved on both chromosomes, their expression patterns have diverged. When the gene order of rice chromosomes 11 and 12 was compared to wheat gene loci, significant synteny between these orthologous regions was detected, illustrating the presence of conserved genes alternating with recently evolved genes. Conclusion: Because the resistance and defense response genes, enriched on these chromosomes relative to the whole genome, also occur in clusters, they provide a preferred target for breeding durable disease resistance in rice and the isolation of their allelic variants. The recent duplication of a large chromosomal segment coupled with the high density of disease resistance gene clusters makes this the most recently evolved part of the rice genome. Based on syntenic alignments of these chromosomes, rice chromosome 11 and 12 do not appear to have resulted from a single whole-genome duplication event as previously suggested

'Horsiculture': how important a land use change in Scotland?

[Extract] Rural areas are now widely recognised as supplying a range of goods and services to people living in urban communities, with one of the fastest developing forms of land use being recreation (Ravenscroft & Long, 1994). In the context of falling agricultural commodity prices, farm-based recreation is a potentially important form of diversification (Ilbery, 1989; Bailey et al., 2000). Recreation also changes the nature of land management, which may have important implications for the rural landscape and environmental features of the rural ecosystems (Gordon. et al., 1989). The growing importance of equestrianism as a UK leisure activity has, in turn, promoted the development of 'horsiculture', with many horses being grazed outdoors for part of the year on land formerly used for livestock grazing (Mellor et al., 1999,2001).\ud \ud The aim of this work is to draw attention to the importance of equestrianism as a determined land-use change within rural areas and how this form of land use is likely to be underestimated in the agriculturally-based information gathering exercises currently conducted by the Scottish Executive

Plant traits in a state and transition framework as markers of ecosystem response to land-use change

International audienceUnderstanding and forecasting changes in plant communities, ecosystem properties, and their associated services requires a mechanistic link between community shifts and modi. cations in ecosystem properties. In this study, we test the hypothesis that plant traits can provide such a link. Using subalpine grasslands in the central French Alps as a case study, we investigate the response of plant traits to changes in soil resource availability and disturbance regimes associated with changing grassland management as well as the effects of changes in plant traits on measured ecosystem properties. We found that fertilization leads to greater specific leaf area and leaf nitrogen content which leads to greater productivity and faster litter decomposition, and that grazing leads to higher leaf toughness and leaf dry matter content which leads to lower productivity and slower decomposition compared to mowing. A state and transition model was used as a flexible conceptual tool for integrating data on community composition, plant traits, and ecosystem properties in the context of management-mediated successional dynamics in subalpine grasslands. Focusing on the biology driving the transition between grassland states, we incorporated plant traits into the formulation of a state and transition model and demonstrated how they could be used to provide a mechanistic link between community shifts and ecosystem properties under complex management regimes with strong land-use legacies