Isolation and characterization of a dehydrin gene from white spruce induced upon wounding, drought and cold stresses.

A cDNA clone encoding a dehydrin gene was isolated from a cDNA library prepared from white spruce (Picea glauca) needle mRNAs. The cDNA, designated PgDhn1, is 1159 nucleotides long and has an open reading frame of 735 bp with a deduced amino acid sequence of 245 residues. The PgDhn1 amino acid sequence is highly hydrophilic and possesses four conserved repeats of the characterized lysine-rich K-segment (EKKGIMD-KIKEKLPG), and an 8-serine residue stretch prior to the first lysine-rich repeat that is common to many dehydrins. The DEYGNP conserved motif is, however, absent in the PgDhn1 sequence. In unstressed plants, the highest level of transcripts was detected in stem tissue and not fully expanded vegetative buds. PgDhn1 expression was also clearly detected in reproductive buds, at various stages of development. The mRNAs corresponding to PgDhn1 cDNA were induced upon wounding and by jasmonic acid (JA) and methyl jasmonate (MeJa) treatments. Upon drought stress, increased transcript accumulation was observed in needle tissue reaching a maximum level 48 h after treatment. Treatments of seedlings with abscisic acid or ethephon also resulted in high levels of transcript accumulation in needle tissue. Finally, cold induction of PgDhn1 transcripts was also detected as early as 8 h after treatment.

The analysis of the transcriptional activator PrnA reveals a tripartite nuclear localisation sequence.

Nuclear localisation signals (NLSs) have been classified as either mono- or bipartite. Genetic analysis and GFP fusions show that the NLS of a Zn-binuclear cluster transcriptional activator of Aspergillus nidulans (PrnA) is tripartite. This NLS comprises two amino-terminal basic sequences and the first basic sequence of the Zn-cluster. Neither the two amino-terminal basic sequences nor the paradigmatic nucleoplasmin bipartite NLS drive our construction to the nucleus. Cryosensitive mutations in the second basic sequence are suppressed by mutations that restore the basicity of the domain. The integrity of the Zn-cluster is not necessary for nuclear localisation. A tandem repetition of the two basic amino-terminal sequences results in a strong NLS. Complete nuclear localisation is observed when the whole DNA-binding domain, including the putative dimerisation element, is included in the construction. At variance with what is seen with tandem NLSs, all fluorescence here is intra-nuclear. This suggests that retention and nuclear entry are functionally different. With the whole PrnA protein, we observe localisation, retention and also a striking sub-localisation within the nucleus. Nuclear localisation and sub-localisation are constitutive (not dependent on proline induction). In contrast with what has been observed by others in A. nidulans, none of our constructions are delocalised during mitosis. This is the first analysis of the NLS of a Zn-binuclear cluster protein and the first characterisation of a tripartite NLS.

[Management of lymphoblastic lymphomas during pregnancy]. / Prise en charge des lymphomes lymphoblastiques au cours de la grossesse.

Lymphoblastic lymphoma (non-Hodgkin lymphoma) is a highly uncommon but serious condition during pregnancy. With multidisciplinary management (obstetrics, pediatrics, hematology and anesthesia), outcome is generally good for both mother and child. Chemotherapy must be initiated rapidly, during pregnancy. Consequences depend on the stage of the disease, its progressive nature and the of pregnancy. During the first trimester, medical termination should be proposed in order to initiate chemotherapy cannot be started until the second trimester using alkaloids. Chemotherapy has little effect on the fetus during the second trimester. During the trimester, extraction should be discussed as soon as the fetal maturity is sufficient.

Isolation and characterization of a cDNA clone encoding a putative white spruce glycine-rich RNA binding protein.

A presumably full-length cDNA encoding a putative glycine-rich RNA binding protein was isolated from a lambdaZAP cDNA library prepared from mRNAs extracted from needles of 2year old white spruce seedlings, which had been either wounded or jasmonate-treated. The cDNA, designated PgRNP (Picea glauca RNP protein), presents a 468bp open reading frame encoding a 155 amino acid protein. This polypeptide possesses an RNA binding domain (RNP-CS) and a glycine-rich domain. Comparative alignment reveals extensive homologies to glycine-rich RNA binding proteins containing an RNP-CS found in other angiosperm species. Genomic hybridization experiments suggest that the PgRNP gene is part of a small multigene family with at least four members. RNA blot analysis revealed that the PgRNP transcript is expressed in all tissues from non-stressed plants. Constitutive mRNA level was found in needle tissue from control as well as methyl-jasmonate treated plants. Wounding had no clear induction effect. Jasmonic acid treatment and systemic wound response had a positive effect on transcript accumulation. Transcript accumulation was slightly induced by cold in needles, and repressed by drought stress in both needle and root tissues of 2year old plants. Finally, the level of PgRNP accumulation was induced by wounding and repressed in 2week old dark-grown seedlings upon jasmonate treatments.

Mechanism of retinoblastoma gene inactivation in the spectrum of neuroendocrine lung tumors.

The retinoblastoma (RB) gene plays a key role in cell cycle control by regulation of G1 growth arrest. This gene is inactivated in some human cancers and in most small-cell lung carcinoma (SCLC) cell lines. The aim of this study was to analyze the mechanisms of RB silencing in freshly excised neuroendocrine (NE) tumors embracing the entire spectrum of NE lung neoplasms (typical and atypical carcinoids, large-cell neuroendocrine carcinomas [LCNECs], and SCLCs). To study the role and mechanism of RB inactivation in tumor differentiation and malignant potential, the status of the Rb protein was analyzed in 37 NE lung tumors, using immunohistochemistry with five Rb antibodies. Loss or altered expression of Rb protein was more frequently observed in high-grade NE lung carcinoma (23 of 28, 82%) than in typical and atypical carcinoids (1 of 9, 11%) (P < 0.001). Of 24 tumors with abnormal Rb staining, Southern blotting showed 1 to have undergone rearrangement, SSCP (single-strand conformation polymorphism) and sequencing showed that 6 (25%) exhibited mutations in exons 13-18 or 20-24 of the RB gene, and RT-PCR (reverse transcriptase-polymerase chain reaction) revealed that 14 (58%) showed a low level of or entirely absent RB mRNA (messenger RNA) expression, whereas hypermethylation of the CpG-rich island at the 5' end of the RB gene was not observed. Abnormal Rb protein expression was always associated with one of these three alternative mechanisms in the SCLCs analyzed, but in only 50% of LCNECs. These results indicate that inactivation of the RB gene is highly frequent in freshly excised high-grade NE lung tumors through distinct mechanisms including point mutations and frequent abnormal mRNA expression. Different modes of RB inactivation seem to be implicated along the spectrum of NE lung carcinomas, depending on differentiation state, phenotype, and malignancy grade.

Oncogene arrangement in a shooty strain of Agrobacterium tumefaciens.

The Agrobacterium tumefaciens nopaline strain 82.139 induces non-teratogenic shooty tumours on several plant species. We have determined the position of the T-region oncogenes in a 11.4 kb Xba I fragment which shows a general organization similar to its pTiC58 counterpart. Sequence analysis of the 4.7 kb right part of this fragment allowed us to identify the pTi82.139 ipt, 6b and nos coding sequences. pTi82.139 lacks the 6a gene, which lies between the ipt and 6b genes in pTiC58. The intervening region between the 6b and the nos genes contains an additional ORF with homology to ORF 21 (transcript 3') from the TR-DNA of octopine strain pTi15955.