Biomedical subjects

M Jeanneau

Publications and source records attributed to M Jeanneau.

6 recordsLinked to original sources

PubMed2002

Improvement of drought tolerance in maize: towards the functional validation of the Zm-Asr1 gene and increase of water use efficiency by over-expressing C4-PEPC.

Water availability is one of the major limiting factors for plant growth. Maize is particularly sensitive to water stress at reproductive stages with a strong impairment of photosynthesis and grain filling. Here, we describe the use of genetic transformation first to assess the role of a candidate gene Asr1-a putative transcription factor-as an explanation for genetically linked drought tolerance Quantitative Trait Loci (QTLs), and second to modify CO(2) fixation rates in leaves through changes of C(4) phosphoenolpyruvate carboxylase (C(4)-PEPC) activity. Transgenic Asr1 over-expressing lines show an increase in foliar senescence under drought conditions. The highest C(4)-PEPC overexpressing line exhibited an increase (+30%) in intrinsic water use efficiency (WUE) accompanied by a dry weight increase (+20%) under moderate drought conditions. Opposite effects were observed for transgenic plants under-expressing the corresponding proteins. The data presented here indicate the feasibility to increase the level of endogenous biochemical activities related to water economy and/or drought tolerance, and opens a way to develop maize varieties more tolerant to dry growing conditions.

Acclimatization↗

PubMed2002

Manipulating PEPC levels in plants.

This review examines the current understanding of the structural, functional and regulatory properties of C4 and C3 forms of higher plant phosphoenolpyruvate carboxylase. The emphasis is on the interactive metabolic and post-translational controls acting on the enzyme in the physiological context of C4 photosynthesis and the anaplerotic pathway. A brief overview is given concerning the recent developments of PEPC-based genetic engineering of C3 plants with the aim of improving photosynthetic performance in normal and limiting environmental conditions. So far, in spite of achieving a considerable increase in PEPC levels, more work needs to be done with respect to the correct dosage and location before that goal is reached. Some unpublished results on the transformation of maize with a sorghum C4 PEPC cDNA are also presented. They show that it is possible to increase photosynthetic PEPC levels in this C4 plant and that the modification in enzyme content has a pleiotropic physiological impact and, notably, an improved water use efficiency when water is limited.

Biomass↗

PubMed2001

Disruption of the Arabidopsis RAD50 gene leads to plant sterility and MMS sensitivity.

The Rad50 protein is involved in the cellular response to DNA-double strand breaks (DSBs), including the detection of damage, activation of cell-cycle checkpoints, and DSB repair via recombination. It is essential for meiosis in yeast, is involved in telomere maintenance, and is essential for cellular viability in mice. Here we present the isolation, sequence and characterization of the Arabidopsis thaliana RAD50 homologue (AtRAD50) and an Arabidopsis mutant of this gene. A single copy of this gene is present in the Arabidopsis genome, located on chromosome II. Northern analysis shows a single 4.3 Kb mRNA species in all plant tissues tested, which is strongly enriched in flowers and other tissues with many dividing cells. The predicted protein presents strong conservation with the other known Rad50 homologues of the amino- and carboxy-terminal regions. Mutant plants present a sterility phenotype which co-segregates with the T-DNA insertion. Molecular analysis of the mutant plants shows that the sterility phenotype is present only in the plants homozygous for the T-DNA insertion. An in vitro mutant cell line, derived from the mutant plant, shows a clear hypersensitivity to the DNA-damaging agent methylmethane sulphonate, suggesting a role of RAD50 in double-strand break repair in plant cells. This is the first report of a plant mutated in a protein of the Rad50-Mre11-Xrs2 complex, as well as the first data suggesting the involvement of the Rad50 homologue protein in meiosis and DNA repair in plants.

Amino Acid Sequence↗

PubMed2000

Self-image and burnout in psychiatric staff.

Burnout was tested for in 754 mental health workers and related to self-image as assessed with Structural Analysis of Social Behavior (SASB, Benjamin 1974). A positive relation was found between burnout and negative self-image, and between the experience of personal accomplishment and positive self-image. Compared to self-image, gender, age and work setting did not explain any variance in burnout. Highly burned-out persons had a significantly more negative self-image than staff who had rated themselves as low burnout. Finally, the relation between self-image and burnout was studied in 210 subjects who had completed their self-image ratings one year before burnout was measured, with the same results: a negative self-image was related to higher burnout one year later. One general conclusion is that a tendency in staff to treat themselves in negative ways may function as a negative filter for coping with difficulties at work and thus be a risk factor for burnout.

Adaptation, Psychological↗

PubMed1996

Multivariate modelling and personality organization: a comparative study of the Defense Mechanism Test and linguistic expressions.

The main aim of the study is to establish an empirical connection between perceptual defences as measured by the Defense Mechanism Test (DMT)--a projective percept-genetic method--and manifest linguistic expressions based on word pattern analyses. The subjects were 25 psychiatric patients with the diagnoses neurotic personality organization (NPO), borderline personality organization (BPO) and psychotic personality organization (PPO) in accordance with Kernberg's theory. A set of 130 DMT variables and 40 linguistic variables were analyzed by means of partial least squares (PLS) discriminant analysis separately and then pooled together. The overall hypothesis was that it would be possible to define the personality organization of the patients in terms of an amalgam of perceptual defences and word patterns, and that these two kinds of data would confirm each other. The result of the combined PLS analysis revealed a very good separation between the diagnostic groups as measured by the pooled variable sets. Among other things, it was shown that NPO patients are principally characterized by linguistic variables, whereas BPO and PPO patients are better defined by perceptual defences as measured by the DMT method.

Borderline Personality Disorder↗

PubMed1993

Linguistic characteristics of neurotic, borderline and psychotic personality organization.

Thirty patients were subjected to a Structural Interview by means of which 10 of them received the diagnosis NPO (Neurotic Personality Organization), 10 BPO (Borderline Personality Organization) and 10 PPO (Psychotic Personality Organization). About 2500 words and groups of words were extracted from the patients' utterances for analysis. The word-frequencies thus found were analyzed by a PLS discriminant analysis which yielded two significant principal components (main dimensions) explaining 57% of the variance. This analysis showed that the three groups of patients are well separated from one another and that there is a definite correlation between personality organization and linguistic variables. The main features of the BPO-patients in this study seem to be that they refer to positions outside themselves and their language is impersonal; we see this as an example of a vacillating identity. The NPO-group is characterized by an intense and rich language, signs of a more advanced symbolizing ability, deixis and high level defenses. The language of the PPO-patients is poor and its predominant feature is a lack of words; in our interpretation this indicates foreclosure and a lack of identity.

Adult↗