How to measure the agroecological performance of farming in order to assist with the transition process.

The use of plant protection products enables farmers to maximize economic performance and yields, but in return, the environment and human health can be greatly affected because of their toxicity. There are currently strong calls for farmers to reduce the use of these toxic products for the preservation of the environment and the human health, and it has become urgent to invest in more sustainable models that help reduce these risks. One possible solution is the transition toward agroecological production systems.

SimPhy: a simulation game to lessen the impact of phytosanitaries on health and the environment--the case of Merja Zerga in Morocco.

Diffuse phytosanitary pollution is a complex phenomenon to manage. Reducing this type of pollution is one of today's key socio-economic and environmental challenges. At the regional level, few approaches enable the actors concerned to implement agricultural management strategies to reduce the use and impact of phytosanitary products.

Xenopus Rbm9 is a novel interactor of XGld2 in the cytoplasmic polyadenylation complex.

During early development, control of the poly(A) tail length by cytoplasmic polyadenylation is critical for the regulation of specific mRNA expression. Gld2, an atypical poly(A) polymerase, is involved in cytoplasmic polyadenylation in Xenopus oocytes. In this study, a new XGld2-interacting protein was identified: Xenopus RNA-binding motif protein 9 (XRbm9).

Cytoplasmic CstF-77 protein belongs to a masking complex with cytoplasmic polyadenylation element-binding protein in Xenopus oocytes.

Regulated mRNA translation is a hallmark of oocytes and early embryos, of which cytoplasmic polyadenylation is a major mechanism. This process involves multiple protein components, including the CPSF (cleavage and polyadenylation specificity factor), which is also required for nuclear polyadenylation. The CstF (cleavage stimulatory factor), with CPSF, is required for the pre-mRNA cleavage before nuclear polyadenylation.

XCdh1 is involved in progesterone-induced oocyte maturation.

The molecular events triggered during progesterone-induced oocyte maturation in Xenopus are not well understood. One of the first events is the activation of the MAPK cascade and the maturation-promoting factor (MPF). The latter triggers meiosis I resumption and meiosis II progression until the metaphase II arrest.

Involvement of Aurora A kinase during meiosis I-II transition in Xenopus oocytes.

The Aurora kinase family has been involved both in vivo and in vitro in the stability of the metaphase plate and chromosome segregation. However, to date only one member of this family, the protein kinase Aurora B, has been implicated in the regulation of meiotic division in Caenorhabditis elegans. In this species, disruption of Aurora B results in the failure of polar body extrusion.

A new role for Mos in Xenopus oocyte maturation: targeting Myt1 independently of MAPK.

The resumption of meiosis in Xenopus arrested oocytes is triggered by progesterone, which leads to polyadenylation and translation of Mos mRNA, then activation of MAPK pathway. While Mos protein kinase has been reported to be essential for re-entry into meiosis in Xenopus, arrested oocytes can undergo germinal vesicle breakdown (GVBD) independently of MAPK activation, leading us to question what the Mos target might be if Mos is still required. We now demonstrate that Mos is indeed necessary, although is independent of the MAPK cascade, for conversion of inactive pre-MPF into active MPF.

c-Mos and cyclin B/cdc2 connections during Xenopus oocyte maturation.

Fully-grown G2 arrested Xenopus oocytes can be induced to enter and progress into meiotic cell cycle by progesterone stimulation. This process is termed oocyte maturation. An early response to progesterone is the synthesis of the onco-protein c-Mos, defined as the candidate initiator of Xenopus oocyte maturation, which triggers the MAPK cascade, MPF activation and promotes CSF activity.

Hsp90 is required for c-Mos activation and biphasic MAP kinase activation in Xenopus oocytes.

During Xenopus oocyte maturation, the Mos protein kinase is synthesized and activates the MAP kinase cascade. In this report, we demonstrate that the synthesis and activation of Mos are two separable processes. We find that Hsp90 function is required for activation and phosphorylation of Mos and full activation of the MAP kinase cascade.

Effects of mutations in the Saccharomyces cerevisiae RNA14 gene on the abundance and polyadenylation of its transcripts.

In the yeast Saccharomyces cerevisiae, the RNA14 and RNA15 gene products have been implicated in RNA cleavage and polyadenylation in vitro and in the choice of polyadenylation site of ACT1 mRNA in vivo. The RNA14 gene produces three transcripts that differ in their 3' end, suggesting the use of different polyadenylation sites. The appearance of the three RNA14 transcripts was examined in different rna14 and/or rna15 mutant strains.

SLS1, a new Saccharomyces cerevisiae gene involved in mitochondrial metabolism, isolated as a syntheticlethal in association with an SSM4 deletion.

SSM4 was isolated as a suppressor of rna14-1, a mutant involved in nuclear mRNA maturation. In order to isolate genes interacting with SSM4, we have searched for mutants that are syntheticlethal in association with an SSM4 deletion. Among the mutants obtained, one, named sls1-1, shows a pet- phenotype.

Effects of mutations in the Saccharomyces cerevisiae RNA14, RNA15, and PAP1 genes on polyadenylation in vivo.

The RNA14 and RNA15 gene products have been implicated in a variety of cellular processes. Mutations in these genes lead to faster decay of some mRNAs and yield extracts that are deficient in cleavage and polyadenylation in vitro. These results suggest that the RNA14 and RNA15 gene products may be involved in both adenylation and deadenylation in vivo.

Inactivation of SSM4, a new Saccharomyces cerevisiae gene, suppresses mRNA instability due to rna14 mutations.

Decay rates of mRNAs depend on many elements and among these, the role of the poly(A) tail is now well established. In the yeast Saccharomyces cerevisiae, thermosensitive mutations in two genes, RNA14 and RNA15, result in mRNAs having shorter poly(A) tails and reduced half-life. To identify other components interacting in the same process, we have used a genetic approach to isolate mutations that suppress the thermosensitivity of an rna14 mutant strain.

Woodchuck hepatitis virus surface antigen produced in vitro fails to bind polymerized woodchuck serum albumin.

Using a plasmid (pSWS) similar to one that has been successfully used for large-scale production of hepatitis B virus (HBV) envelope protein particles (pSVS) but containing the corresponding woodchuck hepatitis virus (WHV) envelope gene sequences, we have stably transformed the rodent dihydrofolate reductase-deficient cell line CHO dhfr-. Although production of WHV envelope particles in CHO/pSWS cell lines was low, it was sufficient to test whether these particles could bind to polymerized serum albumin. Whereas binding of HBV particles produced in CHO/pSVS cells to polymerized human serum albumin could readily be detected, we found no evidence that the WHV envelope protein particles produced in vitro bind to either human or woodchuck polymerized serum albumin.

Recognition of the N-terminal, C-terminal, and interior portions of HBx by sera from patients with hepatitis B.

We have cloned and expressed in Escherichia coli three different parts of the HBx open reading frame, the N- and C-termini and the interior or central portion, using two vector systems. The sera of 43 hepatitis B virus patients representing three clinical categories--asymptomatic carriers, chronic active hepatitis, and hepatitis B patients with cirrhosis--known to be anti-HBx positive, were tested for reactivity against these constructs by Western blotting. The great majority of sera, regardless of the clinical categories, clearly recognise all three parts of HBx, strongly suggesting that the normal mechanism of biosynthesis of the HBx gene product is a straight-forward translation of the open reading frame starting from the first ATG.

Production of polyclonal antibodies against the S and preS2 regions of woodchuck hepatitis virus: lack of detectable low glycosylated preS2 protein (GP33) in sera from infected animals.

Polyclonal antibodies directed against the preS2 and S domains of the woodchuck hepatitis virus (WHV) envelope proteins were prepared using synthetic peptides and fusion polypeptides as immunogens. They were tested by immunoblotting and immunoprecipitation of infected woodchuck sera and lysates of a eukaryotic cell line expressing WHV envelope proteins. Only one anti-peptide serum directed against the preS2 domain was reactive with WHV envelope proteins, recognizing the preS2 and preS1 proteins by their preS2 epitopes.

Early and frequent detection of HBxAg and/or anti-HBx in hepatitis B virus infection.

To clarify the significance of the X gene of hepatitis B virus, we have tested for anti-HBx in the serum and HBxAg in the liver at different stages of the natural history of hepatitis B virus infection. Sera were screened by enzyme-linked immunosorbent assay and positive results confirmed by immunoblot. Purified recombinant MS2 Pol-HBx fusion protein was used as target for both assays.

The HBV HBX gene expressed in E. coli is recognised by sera from hepatitis patients.

We have cloned the X gene (HBx) and the HBc antigen (HBc Ag) gene of human hepatitis B virus (HBV) in Escherichia coli as fusion products with beta-galactosidase. Both HBV genes are expressed in E. coli strain CSR 603.

Nucleotide sequence of a cloned duck hepatitis B virus genome: comparison with woodchuck and human hepatitis B virus sequences.

The nucleotide sequence of an EcoRI duck hepatitis B virus (DHBV) clone was elucidated by using the Maxam and Gilbert method. This sequence, which is 3,021 nucleotides long, was compared with the two previously analyzed hepatitis B-like viruses (human and woodchuck). From this comparison, it was shown that DHBV is derived from an ancestor common to the two others but has a slightly different genomic organization.

Nucleotide sequence of a cloned woodchuck hepatitis virus genome: comparison with the hepatitis B virus sequence.

The complete nucleotide sequence of a woodchuck hepatitis virus genome cloned in Escherichia coli was determined by the method of Maxam and Gilbert. This sequence was found to be 3,308 nucleotides long. Potential ATG initiator triplets and nonsense codons were identified and used to locate regions with a substantial coding capacity.

Localization and nucleotide sequence of the gene coding for the woodchuck hepatitis virus surface antigen: comparison with the gene coding for the human hepatitis B virus surface antigen.

Nucleotide sequence analysis was performed with the Maxam--Gilbert method on a cloned woodchuck hepatitis virus DNA (Eco WHV DNA). The structural gene coding for the envelope protein of the virus was localized on the viral genome in the partially single-stranded region between map positions 91.2 and 71.

Nucleotide sequence of the hepatitis B virus genome (subtype ayw) cloned in E. coli.

The complete nucleotide sequence of hepatitis B virus genome (subtype ayw) cloned in Escherichia coli has been determined using the Maxam and Gilbert method and the dideoxynucleotide method. This sequence is 3,182 nucleotides long. Location of the nonsense codons shows that the coding capacity of the L chain is larger than the coding capacity of the S chain.