Sply regulation of sphingolipid signaling molecules is essential for Drosophila development

Sphingosine-1-phosphate is a sphingolipid metabolite that regulates cell proliferation, migration and apoptosis through specific signaling pathways. Sphingosine-1-phosphate lyase catalyzes the conversion of sphingosine-1-phosphate to ethanolamine phosphate and a fatty aldehyde. We report the cloning of the Drosophila sphingosine-1-phosphate lyase gene (Sply) and demonstrate its importance for adult muscle development and integrity, reproduction and larval viability. Sply expression is temporally regulated, with onset of expression during mid-embryogenesis. Sply null mutants accumulate both phosphorylated and unphosphorylated sphingoid bases and exhibit semi-lethality, increased apoptosis in developing embryos, diminished egg-laying, and gross pattern abnormalities in dorsal longitudinal flight muscles. These defects are corrected by restoring Sply expression or by introduction of a suppressor mutation that diminishes sphingolipid synthesis and accumulation of sphingolipid intermediates. This is the first demonstration of novel and complex developmental pathologies directly linked to a disruption of sphingolipid catabolism in metazoans.     

Purification and properties of arabis mosaic and tomato bushy stunt viruses isolated from lilac (Syringa vulgaris L.)

The paper gives more detailed characteristics of Arabis mosaic virus (AMV) and tomato bushy stunt virus (TBSV) isolated from lilac, the latter being identified in lilac (from plants suffering from yellow ring disease) for the first time. The isolate of TBSV from lilac, from which an antiserum with a titre of 1024 was prepared, is closely related to the artichoke strain. Information is given about two types of ringspot disease and about chlorotic ringspot of lilac. Whereas in the leaves of lilac suffering from ringspot disease (of ring mosaic type) the presence of AMV was demonstrated, the sap transmission from the leaves diseased with ringspot of linepattern (and wave-like mosaic) type failed; from the leaves affected by chlorotic ringspot a mixture of AMV and cherry leaf roll virus was identified. In addition, the polyetiological nature of “spring” mosaic and necrotic mosaic of lilac, in which bacteriumPseudomonas syringae van Hall, was found is dealt with. The TBSV was also identified in the isolate of necrotic mosaic.Additional index words: Lilac ringspot, chlorotic ringspot, yellow ring, “spring” mosaic, necrotic mosaic, cherry leaf roll virus,Pseudomonas syringae van Hall.     

Eimeria tenella ROP kinase EtROP1 induces G0/G1 cell cycle arrest and inhibits host cell apoptosis

Coccidia are obligate intracellular protozoan parasites responsible for human and veterinary diseases. Eimeria tenella, the aetiologic agent of caecal coccidiosis, is a major pathogen of chickens. In Toxoplasma gondii, some kinases from the rhoptry compartment (ROP) are key virulence factors. ROP kinases hijack and modulate many cellular functions and pathways, allowing T. gondii survival and development. E. tenella's kinome comprises 28 putative members of the ROP kinase family; most of them are predicted, as pseudokinases and their functions have never been characterised. One of the predicted kinase, EtROP1, was identified in the rhoptry proteome of E. tenella sporozoites. Here, we demonstrated that EtROP1 is active, and the N‐terminal extension is necessary for its catalytic kinase activity. Ectopic expression of EtROP1 followed by co‐immunoprecipitation identified cellular p53 as EtROP1 partner. Further characterisation confirmed the interaction and the phosphorylation of p53 by EtROP1. E. tenella infection or overexpression of EtROP1 resulted both in inhibition of host cell apoptosis and G0/G1 cell cycle arrest. This work functionally described the first ROP kinase from E. tenella and its noncanonical structure. Our study provides the first mechanistic insight into host cell apoptosis inhibition by E. tenella. EtROP1 appears as a new candidate for coccidiosis control.     

Polarity of meiotic gene conversion is 5′ to 3′ within the niaD gene of Aspergillus nidulans

We have examined polarity of meiotic gene conversion in the niiA-niaD gene cluster of Aspergillus nidulans in two-point crosses. The type and position of the mutations represented by the niaD alleles and the correlation between the relative frequency of gene conversion and the physical position of these mutations were determined. We show that polarity of meiotic gene conversion is 5 to 3 (transcribed strand) within the niaD gene. Additional crosses involving a niiA allele and a niaD allele show little polarity of gene conversion, which suggests that the recombination events leading to restoration of the niaD gene are initiated upstream of the coding region of the niaD gene but within the niiA-niaD gene cluster, possibly within the intergenic promoter region.     

Compositional biases and polyalanine runs in humans

Human proteins containing polyalanine tracts tend to have runs of other amino acids and their open reading frames (ORFs) display a biased codon usage. Their alanine, glycine, proline, and histidine content strongly correlates with the GC content of the third codon base, suggesting that the compositional specificity of these proteins is dictated to a great extent by the evolution of their ORFs.     

New generation pharmacogenomic tools: a SNP linkage disequilibrium Map,validated SNP assay resource,and high-throughput instrumentation system for large-scale genetic studies

Since public and private efforts announced the first draft of the human genome last year, researchers have reported great numbers of single nucleotide polymorphisms (SNPs). We believe that the availability of well-mapped, quality SNP markers constitutes the gateway to a revolution in genetics and personalized medicine that will lead to better diagnosis and treatment of common complex disorders. A new generation of tools and public SNP resources for pharmacogenomic and genetic studies--specifically for candidate-gene, candidate-region, and whole-genome association studies--will form part of the new scientific landscape. This will only be possible through the greater accessibility of SNP resources and superior high-throughput instrumentation-assay systems that enable affordable, highly productive large-scale genetic studies. We are contributing to this effort by developing a high-quality linkage disequilibrium SNP marker map and an accompanying set of ready-to-use, validated SNP assays across every gene in the human genome. This effort incorporates both the public sequence and SNP data sources, and Celera Genomics' human genome assembly and enormous resource ofphysically mapped SNPs (approximately 4,000,000 unique records). This article discusses our approach and methodology for designing the map, choosing quality SNPs, designing and validating these assays, and obtaining population frequency ofthe polymorphisms. We also discuss an advanced, high-performance SNP assay chemisty--a new generation of the TaqMan probe-based, 5' nuclease assay-and high-throughput instrumentation-software system for large-scale genotyping. We provide the new SNP map and validation information, validated SNP assays and reagents, and instrumentation systems as a novel resource for genetic discoveries.     

The development of enantiostyly

Enantiostyly, the deflection of the style either to the left (left-styled) or right (right-styled) side of the floral axis, has evolved in at least ten angiosperm families. Two types of enantiostyly occur: monomorphic enantiostyly, in which individuals exhibit both stylar orientations, and dimorphic enantiostyly, in which the two stylar orientations occur on separate plants. To evaluate architectural or developmental constraints on the evolution of both forms of enantiostyly, we examined inflorescence structure and floral development among unrelated enantiostylous species. We investigated relations between the position of left- and right-styled flowers and inflorescence architecture in four monomorphic enantiostylous species, and we examined the development of enantiostyly in nine monomorphic and dimorphic enantiostylous species from five unrelated lineages. The location of left- and right-styled flowers within inflorescences ranged from highly predictable (in Solanum rostratum) to random (in Heteranthera mexicana). There were striking differences among taxa in the timing of stylar bending. In Wachendorfia paniculata, Dilatris corymbosa, and Philydrum lanuginosum, the style deflected in the bud, whereas in Heteranthera spp., Monochoria australasica, Cyanella lutea, and Solanum rostratum, stylar bending occurred at the beginning of anthesis. Comparisons of organ initiation and development indicated that asymmetries along the left-right axis were expressed very late in development, despite the early initiation of a dorsiventral asymmetry. We suggest that the evolution of dimorphic enantiostyly from monomorphic enantiostyly may be constrained by a lack of left-right positional information in the bud.     

Wildlife utilization and biodiversity conservation in Namibia: conflicting or complementaryobjectives?

This paper surveys different economic aspects of biodiversity conservation in Namibia's wildlife sector. One of the main causes of biodiversity loss has been the conversion of wildlife habitat to other land uses, notably livestock and crops. However, wildlife utilization strategies potentially yield significantly higher economic rates of return compared to these traditional land uses. Historically, the move towards land use patterns more favourable to wildlife has been hampered by a number of policy and institutional constraints. Since Namibia's independence, many of these constraints have now been removed or are in the process of reform. These moves are already encouraging investment in wildlife utilization, most notably in wildlife tourism and related activities. Some forms of wildlife utilization, particularly ecotourism and photographic safaris, will certainly complement the national and international commitment to biodiversity conservation. Consumptive uses may be economically attractive in some areas and will discourage further habitat conversion. However, uses which involve specialized management for the production of a few species may alter the species composition and functioning of ecosystems, causing conflict between the aims of wildlife utilization and biodiversity conservation. Less tangible components of biodiversity may remain under threat even under a well-designed wildlife utilization policy.     

An extensive analysis of the African rice genetic diversity through a global genotyping

Key message

We present here the first curated collection of wild and cultivated African rice species. For that, we designed specific SNPs and were able to structure these very low diverse species.

Abstract

Oryza glaberrima, the cultivated African rice, is endemic from Africa. This species and its direct ancestor, O. barthii, are valuable tool for improvement of Asian rice O. sativa in terms of abiotic and biotic stress resistance. However, only a few limited studies about the genetic diversity of these species were performed. In the present paper, and for the first time at such extend, we genotyped 279 O. glaberrima, selected both for their impact in current breeding and for their geographical distribution, and 101 O. barthii, chosen based on their geographic origin, using a set of 235 SNPs specifically designed for African rice diversity. Using those data, we were able to structure the individuals from our sample in three populations for O. barthii, related to geography, and two populations in O. glaberrima; these two last populations cannot be linked however to any currently phenotyped trait. Moreover, we were also able to identify misclassification in O. glaberrima as well as in O. barthii and identified new form of O. sativa from the set of African varieties.