Modulation of the wheat transcriptome by TaZFP13D under well-watered and drought conditions

Maintaining global food security in the context of climate changes will be an important challenge in the next century. Improving abiotic stress tolerance of major crops such as wheat can contribute to this goal. This can be achieved by the identification of the genes involved and their use to develop tools for breeding programs aiming to generate better adapted cultivars. Recently, we identified the wheat TaZFP13D gene encoding Zinc Finger Protein 13D as a new gene improving water-stress tolerance. The current work analyzes the TaZFP13D-dependent transcriptome modifications that occur in well-watered and dehydration conditions to better understand its function during normal growth and during drought. Plants that overexpress TaZFP13D have a higher biomass under well-watered conditions, indicating a positive effect of the protein on growth. Survival rate and stress recovery after a severe drought stress are improved compared to wild-type plants. The latter is likely due the higher activity of key antioxidant enzymes and concomitant reduction of drought-induced oxidative damage. Conversely, down-regulation of TaZFP13D decreases drought tolerance and protection against drought-induced oxidative damage. RNA-Seq transcriptome analysis identified many genes regulated by TaZFP13D that are known to improve drought tolerance. The analysis also revealed several genes involved in the photosynthetic electron transfer chain known to improve photosynthetic efficiency and chloroplast protection against drought-induced ROS damage. This study highlights the important role of TaZFP13D in wheat drought tolerance, contributes to unravel the complex regulation governed by TaZFPs, and suggests that it could be a promising marker to select wheat cultivars with higher drought tolerance.

Inhibition of ice recrystallization and cryoprotective activity of wheat proteins in liver and pancreatic cells

Efficient cryopreservation of cells at ultralow temperatures requires the use of substances that help maintain viability and metabolic functions post-thaw. We are developing new technology where plant proteins are used to substitute the commonly-used, but relatively toxic chemical dimethyl sulfoxide. Recombinant forms of four structurally diverse wheat proteins, TaIRI-2 (ice recrystallization inhibition), TaBAS1 (2-Cys peroxiredoxin), WCS120 (dehydrin), and TaENO (enolase) can efficiently cryopreserve hepatocytes and insulin-secreting INS832/13 cells. This study shows that TaIRI-2 and TaENO are internalized during the freeze-thaw process, while TaBAS1 and WCS120 remain at the extracellular level. Possible antifreeze activity of the four proteins was assessed. The "splat cooling" method for quantifying ice recrystallization inhibition activity (a property that characterizes antifreeze proteins) revealed that TaIRI-2 and TaENO are more potent than TaBAS1 and WCS120. Because of their ability to inhibit ice recrystallization, the wheat recombinant proteins TaIRI-2 and TaENO are promising candidates and could prove useful to improve cryopreservation protocols for hepatocytes and insulin-secreting cells, and possibly other cell types. TaENO does not have typical ice-binding domains, and the TargetFreeze tool did not predict an antifreeze capacity, suggesting the existence of nontypical antifreeze domains. The fact that TaBAS1 is an efficient cryoprotectant but does not show antifreeze activity indicates a different mechanism of action. The cryoprotective properties conferred by WCS120 depend on biochemical properties that remain to be determined. Overall, our results show that the proteins' efficiencies vary between cell types, and confirm that a combination of different protection mechanisms is needed to successfully cryopreserve mammalian cells.

Production of human rotavirus and Salmonella antigens in plants and elicitation of fljB-specific humoral responses in mice

A Nicotiana benthamiana transient expression system was used to express single antigen and dimeric combinations of the human rotavirus (HRV) VP7 and a truncated VP4 (VP4Δ) proteins fused with Salmonella typhimurium's flagellin fljB subunit. Immunoblot analyses using rabbit antibodies generated against these proteins demonstrated that the constructs were successfully expressed with yields ranging from 0.85 to 31.97 μg of recombinant protein per gram of fresh leaf tissue. Expressing the single and dimeric antigens has no effect on plant growth and development except for VP7 and VP4Δ::VP7, which show mild necrotic lesions. Immunization of mice with proteins from leaves transformed with constructs bearing the fljB moiety elicited an fljB-specific humoral response. The Nicotiana benthamiana transient system is efficient to express multiple combinations of pathogen proteins and demonstrates the potential of generating a Salmonella typhimurium subunit vaccine in plants.

Effects of government policies on the work of home care personnel and their occupational health and safety

The health sector in Québec (Canada) is dealing with profound macro-economic and macro-organizational changes. This article is interested in the impact of these changes on the work of home health aides (HHAs) and home care nurses and their occupational health and safety (OHS). The study was carried out in the home care services (HCS) of four local community service centres (CLSC) with different organizational characteristics. It is based on an analysis by triangulation of 66 individual and group interviews, 22 observed workdays and 35 observed multidisciplinary or professional meetings, as well as on administrative documents. HHAs are experiencing an erosion of their job because the relational and affective aspects of their work are disappearing. This may be due to an increase in their physical workload, leading to an increase in musculoskeletal problems and, to a lesser extent, in psychological health problems. Nurses are seeing an increase in the volume of invisible work that they have to do, which also has the effect of decreasing the relational aspects of their activity. The increasingly numerous psychological health problems are the consequence of this change in their profession. This study also shows that managers' decisions at the local level can reduce or increase the work constraints of HHAs and nurses. Examples of good practices for HHAs are the stabilization of clienteles and the possibility of organizing their itinerary, while for nurses, it is in how clientele follow-up tools are implemented. This article discusses the effects of government policies and decisions on the work and OHS of home care personnel. To address this subject, we use a specific analysis of the workload of home health aides (HHAs) and nurses. We will show the relationships between managers' organizational choices to respond to governmental constraints and the resulting work changes. We will also look at their consequences on occupational health and safety (OHS) and on the work of different personnel.

Overexpression of TaVRN1 in Arabidopsis promotes early flowering and alters development

TaVRN1, a member of the APETALA1 (AP1) subfamily of MADS-box transcription factors, is a key gene that controls transition from vegetative to reproductive phase in wheat. The accumulation of TaVRN1 transcripts in winter wheat probably requires the down-regulation of TaVRT2, a MADS-box factor that binds and represses the TaVRN1 promoter, and of the flowering repressor TaVRN2. However, the molecular mechanisms by which TaVRN1 functions as an activator of phase transition is unknown. To address this, a combination of gene expression and functional studies was used. RNA in situ hybridization studies showed that TaVRN1 transcripts accumulate in all meristems and primordia associated with flower development. An interaction screen in yeast revealed that TaVRN1 interacts with several proteins involved in different processes of plant development such as transcription factors, kinases and a cyclophilin. Arabidopsis plants overexpressing TaVRN1 flower early and show various levels of modified plant architecture. The ectopic expression causes an overexpression of the AP1 and MAX4 genes, which are associated with flowering and auxin regulation, respectively. The induction of gene expression probably results from the binding of TaVRN1 to CArG motifs present on the AP1 and MAX4 promoters. In contrast, Arabidopsis plants that overexpress TaVRT2, which encodes a putative flowering repressor, show an opposite late flowering phenotype. Together, the data provide molecular evidence that TaVRN1 may have pleiotropic effects in various processes such as control of axillary bud growth, transition to flowering and development of floral organs.

TaVRT2 represses transcription of the wheat vernalization gene TaVRN1

In wheat, VRN1/TaVRN1 and VRN2/TaVRN2 determine the growth habit and flowering time. In addition, the MADS box transcription factor VEGETATIVE TO REPRODUCTIVE TRANSITION 2 (TaVRT2) is also associated with the vernalization response in a manner similar to TaVRN2. However, the molecular relationship between these three genes and their products is unknown. Using transient expression assays in Nicotiana benthamiana, we show that TaVRT2 acts as a repressor of TaVRN1 transcription. TaVRT2 binds the CArG motif in the TaVRN1 promoter and represses its activity in vivo. In contrast, TaVRN2 does not bind the TaVRN1 promoter and has no direct effect on its activity, but it can enhance the repression effect of TaVRT2. This suggests that a repressor complex regulates the expression of TaVRN1. In winter wheat, TaVRT2, TaVRN2 and TaVRN1 transcripts accumulate in the shoot apical meristem and young leaves, and temporal expression is consistent with TaVRT2 and TaVRN2 being repressors of floral transition, whereas TaVRN1 is an activator. Non-vernalized spring wheat grown under a short-day photoperiod accumulates TaVRT2 and shows a delay in flowering, suggesting that TaVRT2 is regulated independently by photoperiod and low temperature. The data presented suggest that TaVRT2, in association with TaVRN2, represses the transcription of TaVRN1.

Restructuring of the Québec health network and its effects on the profession of home health aides and their occupational health and safety

The Québec health sector is facing profound macroeconomic and macro-organizational changes. This article addresses the impact of these changes on the work of home health aides (HHAs) and their occupational health and safety (OHS). The study was carried out in the home care services of four local community service centers (CLSCs) with different organizational characteristics. It is based on an analysis by triangulation of 66 individual and group interviews, 11 work days, and 35 multidisciplinary or professional meetings observed, as well as administrative documents. HHAs are experiencing an erosion of their job because the relational and emotional components of their work are disappearing. This results in an increase in musculoskeletal and psychological health problems. This study also shows that managers' decisions can reduce or increase the HHAs' work constraints. Stability in the clientele served and the possibility of organizing their routes are good examples of positive impacts.

Wheat EST resources for functional genomics of abiotic stress

Background

Wheat is an excellent species to study freezing tolerance and other abiotic stresses. However, the sequence of the wheat genome has not been completely characterized due to its complexity and large size. To circumvent this obstacle and identify genes involved in cold acclimation and associated stresses, a large scale EST sequencing approach was undertaken by the Functional Genomics of Abiotic Stress (FGAS) project.

Results

We generated 73,521 quality-filtered ESTs from eleven cDNA libraries constructed from wheat plants exposed to various abiotic stresses and at different developmental stages. In addition, 196,041 ESTs for which tracefiles were available from the National Science Foundation wheat EST sequencing program and DuPont were also quality-filtered and used in the analysis. Clustering of the combined ESTs with d2_cluster and TGICL yielded a few large clusters containing several thousand ESTs that were refractory to routine clustering techniques. To resolve this problem, the sequence proximity and "bridges" were identified by an e-value distance graph to manually break clusters into smaller groups. Assembly of the resolved ESTs generated a 75,488 unique sequence set (31,580 contigs and 43,908 singletons/singlets). Digital expression analyses indicated that the FGAS dataset is enriched in stress-regulated genes compared to the other public datasets. Over 43% of the unique sequence set was annotated and classified into functional categories according to Gene Ontology.

Conclusion

We have annotated 29,556 different sequences, an almost 5-fold increase in annotated sequences compared to the available wheat public databases. Digital expression analysis combined with gene annotation helped in the identification of several pathways associated with abiotic stress. The genomic resources and knowledge developed by this project will contribute to a better understanding of the different mechanisms that govern stress tolerance in wheat and other cereals.

Identification, expression, and evolutionary analyses of plant lipocalins

Lipocalins are a group of proteins that have been characterized in bacteria, invertebrate, and vertebrate animals. However, very little is known about plant lipocalins. We have previously reported the cloning of the first true plant lipocalins. Here we report the identification and characterization of plant lipocalins and lipocalin-like proteins using an integrated approach of data mining, expression studies, cellular localization, and phylogenetic analyses. Plant lipocalins can be classified into two groups, temperature-induced lipocalins (TILs) and chloroplastic lipocalins (CHLs). In addition, violaxanthin de-epoxidases (VDEs) and zeaxanthin epoxidases (ZEPs) can be classified as lipocalin-like proteins. CHLs, VDEs, and ZEPs possess transit peptides that target them to the chloroplast. On the other hand, TILs do not show any targeting peptide, but localization studies revealed that the proteins are found at the plasma membrane. Expression analyses by quantitative real-time PCR showed that expression of the wheat (Triticum aestivum) lipocalins and lipocalin-like proteins is associated with abiotic stress response and is correlated with the plant's capacity to develop freezing tolerance. In support of this correlation, data mining revealed that lipocalins are present in the desiccation-tolerant red algae Porphyra yezoensis and the cryotolerant marine yeast Debaryomyces hansenii, suggesting a possible association with stress-tolerant organisms. Considering the plant lipocalin properties, tissue specificity, response to temperature stress, and their association with chloroplasts and plasma membranes of green leaves, we hypothesize a protective function of the photosynthetic system against temperature stress. Phylogenetic analyses suggest that TIL lipocalin members in higher plants were probably inherited from a bacterial gene present in a primitive unicellular eukaryote. On the other hand, CHLs, VDEs, and ZEPs may have evolved from a cyanobacterial ancestral gene after the formation of the cyanobacterial endosymbiont from which the chloroplast originated.

TaVRT-2, a member of the StMADS-11 clade of flowering repressors, is regulated by vernalization and photoperiod in wheat

The initiation of the reproductive phase in winter cereals is delayed during winter until favorable growth conditions resume in the spring. This delay is modulated by low temperature through the process of vernalization. The molecular and genetic bases of the interaction between environmental factors and the floral transition in these species are still unknown. However, the recent identification of the wheat (Triticum aestivum L.) TaVRT-1 gene provides an opportunity to decipher the molecular basis of the flowering-time regulation in cereals. Here, we describe the characterization of another gene, named TaVRT-2, possibly involved in the flowering pathway in wheat. Molecular and phylogenetic analyses indicate that the gene encodes a member of the MADS-box transcription factor family that belongs to a clade responsible for flowering repression in several species. Expression profiling of TaVRT-2 in near-isogenic lines and different genotypes with natural variation in their response to vernalization and photoperiod showed a strong relationship with floral transition. Its expression is up-regulated in the winter genotypes during the vegetative phase and in photoperiod-sensitive genotypes during short days, and is repressed by vernalization to a level that allows the transition to the reproductive phase. Protein-protein interaction studies revealed that TaVRT-2 interacts with proteins encoded by two important vernalization genes (TaVRT-1/VRN-1 and VRN-2) in wheat. These results support the hypothesis that TaVRT-2 is a putative repressor of the floral transition in wheat.

Molecular characterization and origin of novel bipartite cold-regulated ice recrystallization inhibition proteins from cereals

To understand the molecular basis of freezing tolerance in plants, several low temperature-responsive genes have been identified from wheat. Among these are two genes named TaIRI-1 and TaIRI-2 (Triticum aestivum ice recrystallization inhibition) that are up-regulated during cold acclimation in freezing-tolerant species. Phytohormones involved in pathogen defense pathways (jasmonic acid and ethylene) induce the expression of one of the two genes. The encoded proteins are novel in that they have a bipartite structure that has never been reported for antifreeze proteins. Their N-terminal part shows similarity with the leucine-rich repeat-containing regions present in the receptor domain of receptor-like protein kinases, and their C-terminus is homologous to the ice-binding domain of some antifreeze proteins. The recombinant TaIRI-1 protein inhibits the growth of ice crystals, confirming its function as an ice recrystallization inhibition protein. The TaIRI genes were found only in the species belonging to the Pooideae subfamily of cereals. Comparative genomic analysis suggested that molecular evolutionary events took place in the genome of freezing-tolerant cereals to give rise to these genes with putative novel functions. These apparent adaptive DNA rearrangement events could be part of the molecular mechanisms that ensure the survival of hardy cereals in the harsh freezing environments.

Characterization of a calcium-soluble protein fraction from yellow mustard (Sinapis alba) seed meal with potential application as an additive to calcium-rich drinks

A calcium-soluble protein isolate (CSPI) was prepared from the supernatant obtained after addition of 0.75 M calcium chloride to a pH 5.0 aqueous extract of yellow mustard (Sinapis alba) seed meal. Total amino acid analysis showed that the CSPI has significantly higher (p < 0.05) contents of glutamic acid + glutamine, cysteine, and proline when compared to the precipitated, calcium-insoluble proteins. Peptide mass fingerprinting of tryptic peptides of the major polypeptides by mass spectrometry indicated that the CSPI is composed mainly of cruciferin proteins with a contribution from napins (the major allergenic proteins of S. alba). The S. alba CSPI had significantly higher (p < 0.05) protein solubility and emulsion formation ability in the presence of 0.75 M calcium chloride when compared to similar isolates prepared from Brassica juncea (brown mustard) and soybean seed meals. We suggest that the S. alba CSPI could be used to prepare calcium-fortified high protein liquid products. However, the presence of allergenic proteins in this extract may limit its widespread food use.

Mechanisms of uptake and resistance to troxacitabine, a novel deoxycytidine nucleoside analogue, in human leukemic and solid tumor cell lines

Troxacitabine (Troxatyl; BCH-4556; (-)-2'-deoxy-3'-oxacytidine), a deoxycytidine analogue with an unusual dioxolane structure and nonnatural L-configuration, has potent antitumor activity in animal models and is in clinical trials against human malignancies. The current work was undertaken to identify potential biochemical mechanisms of resistance to troxacitabine and to determine whether there are differences in resistance mechanisms between troxacitabine, gemcitabine, and cytarabine in human leukemic and solid tumor cell lines. The CCRF-CEM leukemia cell line was highly sensitive to the antiproliferative effects of troxacitabine, gemcitabine, and cytarabine with inhibition of proliferation by 50% observed at 160, 20, and 10 nM, respectively, whereas a deoxycytidine kinase (dCK)-deficient variant (CEM/dCK(-)) was resistant to all three drugs. In contrast, a nucleoside transport-deficient variant (CEM/ARAC8C) exhibited high levels of resistance to cytarabine (1150-fold) and gemcitabine (432-fold) but only minimal resistance to troxacitabine (7-fold). Analysis of troxacitabine transportability by the five molecularly characterized human nucleoside transporters [human equilibrative nucleoside transporters 1 and 2, human concentrative nucleoside transporter (hCNT) 1, hCNT2, and hCNT3] revealed that short- and long-term uptake of 10-30 microM [(3)H]troxacitabine was low and unaffected by the presence of either nucleoside transport inhibitors or high concentrations of nonradioactive troxacitabine. These results, which suggested that the major route of cellular uptake of troxacitabine was passive diffusion, demonstrated that deficiencies in nucleoside transport were unlikely to impart resistance to troxacitabine. A troxacitabine-resistant prostate cancer subline (DU145(R); 6300-fold) that exhibited reduced uptake of troxacitabine was cross-resistant to both gemcitabine (350-fold) and cytarabine (300-fold). dCK activity toward deoxycytidine in DU145(R) cell lysates was <20% of that in DU145 cell lysates, and no activity was detected toward troxacitabine. Sequence analysis of cDNAs encoding dCK revealed a mutation of a highly conserved amino acid (Trp(92)-->Leu) in DU145(R) dCK, providing a possible explanation for the reduced phosphorylation of troxacitabine in DU145(R) lysates. Reduced deamination of deoxycytidine was also observed in DU145(R) relative to DU145 cells, and this may have contributed to the overall resistance phenotype. These results, which demonstrated a different resistance profile for troxacitabine, gemcitabine, and cytarabine, suggest that troxacitabine may have an advantage over gemcitabine and cytarabine in human malignancies that lack or have low nucleoside transport activities.

IAA17/AXR3: biochemical insight into an auxin mutant phenotype

The Aux/IAA genes are rapidly and specifically induced by the plant hormone auxin. The proteins encoded by this gene family are short-lived nuclear proteins that are capable of homodimerizing and heterodimerizing. Molecular, biochemical, and genetic data suggest that these proteins are involved in auxin signaling. The pleiotropic morphological phenotype and altered auxin responses of the semidominant axr3-1 mutant of Arabidopsis result from a single amino acid change in the conserved domain II of the Aux/IAA protein IAA17. Here, we show that the biochemical effect of this gain-of-function mutation is to increase the half-life of the iaa17/axr3-1 protein by sevenfold. Intragenic mutations that suppress the iaa17/axr3-1 phenotype have been described. The iaa17/axr3-1R3 revertant contains a second site mutation in domain I and the iaa17/axr3-1R2 revertant contains a second site mutation in domain III. Transient expression assays show that the mutant forms of IAA17/AXR3 retain the ability to accumulate in the nucleus. Using the yeast two hybrid system, we show that the iaa17/axr3-1 mutation does not affect homodimerization. However, the iaa17/axr3-1 revertants counteract the increased levels of iaa17/axr3-1 protein by decreasing the capacity of the mutant protein to homodimerize. Interestingly, heterodimerization of the revertant forms of IAA17/AXR3 with IAA3/SHY2, another Aux/IAA protein, and ARF1 or ARF5/MP proteins is affected only by changes in domain III. Collectively, the results provide biochemical evidence that the revertant mutations in the IAA17/AXR3 gene affect the capacity of the encoded protein to dimerize with itself, other members of the Aux/IAA protein family, and members of the ARF protein family. By extension, these findings may provide insight into the effects of analogous mutations in other members of the Aux/IAA gene family.

Biotechnological applications of plant freezing associated proteins

Plants use a wide array of proteins to protect themselves against low temperature and freezing conditions. The identification of these freezing tolerance associated proteins and the elucidation of their cryoprotective functions will have important applications in several fields. Genes encoding structural proteins, osmolyte producing enzymes, oxidative stress scavenging enzymes, lipid desaturases and gene regulators have been used to produce transgenic plants. These studies have revealed the potential capacity of different genes to protect against temperature related stresses. In some cases, transgenic plants with significant cold tolerance have been produced. Furthermore, the biochemical characterization of the cold induced antifreeze proteins and dehydrins reveals many applications in the food and the medical industries. These proteins are being considered as food additives to improve the quality and shelf-life of frozen foods, as cryoprotective agents for organ and cell cryopreservation, and as chemical adjuvant in cancer cryosurgery.

Comparative study of a novel nucleoside analogue (Troxatyl, troxacitabine, BCH-4556) and AraC against leukemic human tumor xenografts expressing high or low cytidine deaminase activity

PURPOSE

Troxacitabine (beta-L-dioxolane cytidine, BCH-4556; Troxatyl, BioChem Pharma Inc.) is a novel nucleoside analogue, which in experiments demonstrated potent antitumor activity against both leukemias and solid tumors. Since troxacitabine is a cytidine nucleoside analogue like AraC (1-beta-D-arabinofuranosylcytosine), which is currently used in the treatment of acute myelogenous leukemia, we compared the in vivo antileukemic activity of troxacitabine with that of AraC in human leukemia xenograft models.

METHODS

The antiproliferative activity of troxacitabine and AraC was analyzed on hemapoietic cell lines by use of a thymidine incorporation assay. For in vivo studies, we compared troxacitabine with AraC by using equitotoxic schedules of the two nucleosides optimized for therapeutic activity. The antileukemic activity of both drugs was evaluated by measurement of their effect on the percent increased lifespan.

RESULTS

AraC had good in vitro antiproliferative activity (IC50 = 14 nM) but was ineffective in vivo against the HL60 promyelocyte leukemia cell line (treated vs control, T/C = 105%). Troxacitabine, which in contrast to AraC is not a substrate for cytidine deaminase, showed potent in vitro and in vivo activity in the same model (IC50 = 53 nM and T/C = 272% to 422%). The poor in vivo activity of AraC against HL60 leukemia cells could be due to the high cytidine deaminase (CDA; EC 3.5.4.5) activity in this cell line. This hypothesis was tested with CCRF-CEM T-lymphoblastoid leukemia cells which have undetectable levels of CDA activity. Short-term exposure of these leukemia cell lines to both drugs indicated that AraC was indeed significantly more effective in the CCRF-CEM cell line than in HL60. In contrast, the antiproliferative activity of troxacitabine was similar for both cell lines. These observations were extended to in vivo studies. Mice bearing CCRF-CEM tumor xenografts were treated with AraC and troxacitabine. In this model, T/C values were comparable for both drugs and ranged from 138% to 157%.

CONCLUSIONS

Our findings indicate that troxacitabine is likely to be effective not only against solid tumors with high CDA activity but also in leukemias which have developed resistance to AraC due to increased CDA levels; this suggests that troxacitabine is a promising agent for the treatment of cancer. Indeed, significant antileukemic activity has been observed with troxacitabine in a phase I clinical trial in patients with primary refractory or relapsed acute myeloid leukemias (AML).

Regulation of a wheat actin-depolymerizing factor during cold acclimation

We have previously shown that the wheat (Triticum aestivum) TaADF gene expression level is correlated with the plants capacity to tolerate freezing. Sequence analysis revealed that this gene encodes a protein homologous to members of the actin-depolymerizing factor (ADF)/cofilin family. We report here on the characterization of the recombinant TaADF protein. Assays for ADF activity showed that TaADF is capable of sequestering actin, preventing nucleotide exchange, and inducing actin depolymerization. In vitro phosphorylation studies showed that TaADF is a substrate for a wheat 52-kD kinase. The activity of this kinase is modulated by low temperature during the acclimation period. Western-blot analyses revealed that TaADF is expressed only in cold-acclimated Gramineae species and that the accumulation level is much higher in the freezing-tolerant wheat cultivars compared with the less tolerant ones. This accumulation was found to be regulated by a factor(s) encoded by a gene(s) located on chromosome 5A, the chromosome most often found to be associated with cold hardiness. The induction of an active ADF during cold acclimation and the correlation with an increased freezing tolerance suggest that the protein may be required for the cytoskeletal rearrangements that may occur upon low temperature exposure. These remodelings might be important for the enhancement of freezing tolerance.

From a unidimensional to a bidimensional concept and measurement of workers' safety behavior

OBJECTIVES

This study examines the concept and measurement of worker's safety behavior. It shows that the traditional concept of safety behavior centered on workers' carefulness or compliance with safety rules is limited and proposes that an additional dimension, namely, workers' safety initiatives, be taken into account.

METHODS

Confirmatory factor analyses were carried out for a random sample of 828 workers drawn from 9 manufacturing facilities located in the province of Quebec (Canada).

RESULTS

A 2-correlated congeneric factor model gave parameters in the expected direction, but the overall model was unable to reach a good fit. Separate construct analyses showed that compliance with safety rules is not a consistent dimension. The safety-initiatives dimension achieved a good fit with a high composite reliability (p=0.85).

CONCLUSIONS

Workers' compliance with safety rules was not structured as a unitary dimension; therefore a selective process of safety-rules compliance by workers is suggested. Each category of safety rules should be considered as 1 single dimension and measured by several specific indicators. Indicators for safety initiatives provide high reliability, and, since this dimension is an important predictor of effectiveness in accident prevention, the items tested provide a better measurement than those previously published.

The wheat wcs120 promoter is cold-inducible in both monocotyledonous and dicotyledonous species

The wcs120 gene is specifically induced by low temperature (LT) and encodes a protein that is thought to play an important role in the cold acclimation process in wheat. To identify the regulatory elements involved in its LT responsiveness, the transient expression activity of different promoter regions was determined using the luciferase reporter gene. The data indicate the involvement of putative enhancer elements, negative and positive regulatory regions in the transcriptional regulation of this gene. The promoter was found to be cold-inducible in different freezing-tolerant and -sensitive monocot and dicot species, suggesting that universal transcription factors responsive to LT may be present in all plants. This promoter could be used to drive the genes needed for LT tolerance in sensitive species.

Low temperature-stimulated phosphorylation regulates the binding of nuclear factors to the promoter of Wcs120, a cold-specific gene in wheat

The Wcs120 gene encodes a highly abundant protein which appears to play an important role during cold acclimation of wheat. To understand the regulatory mechanism controlling its expression at low temperature, the promoter region has been characterized. Electrophoretic mobility shift assays using short promoter fragments revealed the presence in nuclear extracts from non-acclimated (NA) plants of multiple DNA-binding proteins which interact with several elements. In contrast, no DNA-binding activity was observed in the nuclear extracts from cold-acclimated (CA) plants. In vitro dephosphorylation of these CA nuclear extracts with alkaline phosphatase restored the binding activity. Moreover, okadaic acid (a potent phosphatase inhibitor) markedly stimulated the in vivo accumulation of the WCS120 family of proteins. This suggests that protein phosphatases PP1 and/or PP2A negatively regulate the expression of the Wcs120 gene. In addition, both Ca(2+)-dependent and Ca(2+)-independent kinase activities were found to be significantly higher in the CA nuclear extracts. Western analysis using antibodies directed against protein kinase C (PKC) isoforms showed that a PKCgamma homolog (84 kDa) is selectively translocated into the nucleus in response to low temperature. Taken together, our results suggest that, in vivo, the expression of the Wcs120 gene may be regulated by nuclear factors whose binding activity is modulated by a phosphorylation/dephosphorylation mechanism.

Gene expression during cold acclimation in strawberry

To elucidate the molecular basis of cold acclimation in strawberry (Fragaria x anannassa), we have begun studies to identify genes associated with low temperature (LT) acclimation. Differential screening of a cDNA library prepared from cold-acclimated strawberry plants allowed us to isolate several cDNAs showing differential expression at LT. Northern analysis showed that the transcript level of Fcor1 (Fragaria Cold-Regulated) peaked after 2 days of LT exposure while that of Fcor2 peaked after 2 weeks. On the other hand, the level of Fcor3 transcript decreased within 24 hours of LT exposure and remained low during the 8 weeks acclimation period. Fcor1 and Fcor2 are expressed in all tissues while Fcor3 is specific to leaves. The Fcor1-encoded protein has a compositional bias for leucine, isoleucine, glycine, proline and serine. This protein shares homology with the proteins encoded by blt101, a LT-responsive gene from barley, and ESI3, a gene induced by salt stress in Lophopyrum. The FCOR2 protein is rich in lysine, leucine, valine, alanine and arginine, and shows no homology with any known gene products. The partial Fcor3 cDNA clone encodes a polypeptide that shows a very high identity with the spinach PSI subunit V and with the PSI PsaG polypeptide from barley. The level of Fcor1 transcript accumulation is correlated with the freezing tolerance of the strawberry cultivars used in our study. This suggests that Fcor1 may be useful as a molecular marker to select for this trait in resulted species of the Rosaceae family.

Myelin basic protein and human coronavirus 229E cross-reactive T cells in multiple sclerosis

Multiple sclerosis (MS) is an inflammatory demyelinating neurological disease in which autoreactive T lymphocytes sensitized to myelin components of the central nervous system are postulated to contribute to pathogenesis. The possible relevance of molecular mimicry between a human coronavirus and the myelin basic protein component of myelin in the generation of this autoimmune reaction was evaluated. Myelin basic protein- and virus-reactive T-cell lines were established from 16 MS patients and 14 healthy donors and shown to be mostly CD4+. In contrast to healthy donors, several T-cell lines isolated from MS patients showed cross-reactivity between myelin and coronavirus antigens. Overall, 29% of T-cell lines from MS patients (10 donors) but only 1.3% of T-cell lines from normal control subjects (2 donors) showed an HLA-DR-restricted cross-reactive pattern of antigen activation after in vitro selection with either myelin basic protein or human coronavirus strain 229E antigens. Moreover, reciprocal reactivities were only observed in MS patients (4 donors). This establishes molecular mimicry between a common viral pathogen, such as this human coronavirus, and myelin as a possible immunopathological mechanism in MS and is consistent with the possible involvement of more than one infectious pathogen as an environmental trigger of disease.

Purification, characterization and cDNA cloning of the 200 kDa protein induced by cold acclimation in wheat

We have purified to homogeneity the 200 kDa protein induced specifically by low temperature in wheat (Triticum aestivum L.). The boiling solubility of the protein has been used as a main step in the purification procedure. Amino acid composition indicates that the 200 kDa has a compositional bias for glycine (11.4%), threonine (13.3%), and alanine (22.0%). Using oligonucleotide probes, we have isolated a clone (p Wcs200) from a cold-acclimated winter wheat cDNA library. Northern analysis demonstrated that the expression of the corresponding gene was specifically upregulated by low temperature. Southern analysis showed that the gene organization and the relative copy number were identical in two cultivars differing in their capacity to develop freezing tolerance. Protein sequence and immunological analyses indicate that this protein shares similar features with the 50 kDa protein induced during cold acclimation of wheat. The two proteins are boiling-soluble, and possess similar repeated elements. These elements may be important for the development of freezing tolerance. We have shown that the 200 kDa protein is the largest member of a family of immunologically-related cold-induced proteins in wheat. Expression of pWcs200 in E. coli yielded a product of around 200 kDa, indicating that the clone contains most of the coding region for this protein.

[Non-professional workers and prevention of ill-treatment in childhood : evaluation of De la Visite project.]

SUMMARY The De La Visite project makes a contribution to a major social challenge : putting in place preventive measures with the long-term goal of diminishing abuse and negligence of children in the home. This project consisted of : 1) having nonprofes-sional workers visit at home new parents living in three economically disadvantaged neighbourhoods on the Island of Montreal ; 2) evaluating this new service via an innovative research method utilizing both an experimental instrument and a qualitative approach, in order to determine whether to propose implementation in the Montreal region. The first part of this article presents the project's premises and goals. The second part gives an overview of the experiment and discusses, for those who offer or wish to offer a similar service, what was learned from a detailed analysis of how the service worked. The third part of the article discusses the effects of the experiment.

[The natural increase of the Catholic population of Quebec before 1850: historiographic and quantitative perspectives]

"The author presents a critical evaluation of the different estimates of birth, death, and marriage rates in French Canada before 1850. He examines critically the sensitivity of these estimates to changes in the nature of the prevailing conceptual framework. In particular, the impact of the 'natalist' tradition and of the 'demographic transition hypothesis' on these estimates is noted." (summary in ENG)