Biomedical subjects

Michela Zottini

Publications and source records attributed to Michela Zottini.

4 recordsLinked to original sources

PubMed2006

Growth and senescence of Medicago truncatula cultured cells are associated with characteristic mitochondrial morphology.

Here mitochondrial morphology and dynamics were investigated in Medicago truncatula cell-suspension cultures during growth and senescence. Cell biology techniques were used to measure cell growth and death in culture. Mitochondrial morphology was investigated in vivo using a membrane potential sensor probe coupled with confocal microscopy. Expression of a senescence-associated gene (MtSAG) was evaluated in different cell-growth phases. Mitochondria appeared as numerous, punctuate organelles in cells at the beginning of the subculture cycle, while interconnected networks were observed in actively growing cells. In senescent cells, giant mitochondria were associated with dying cells. The release of cytochrome c from mitochondria was detected in different growth phases of cultured cells. Studies on plant cell cultures allowed us to identify physiological and molecular markers of senescence and cell death, and to associate distinct mitochondrial morphology with cells under different physiological conditions.

Amino Acid Sequence↗

PubMed2002

Cytokinins: new apoptotic inducers in plants.

High concentrations of cytokinins block cell proliferation and induce programmed cell death (PCD) in both carrot ( Daucus carota L.) and Arabidopsis thaliana (L.) Heynh. cell cultures [13 and 27 micro M N(6)-benzylaminopurine (BAP), respectively]. In the present work, cell death was scored by Evan's blue staining and was also demonstrated to be programmed by various parameters, including chromatin condensation, oligonucleosomal DNA degradation (laddering), and release of cytochrome c from mitochondria. In carrot cells, this induction takes approximately 24 h, with proliferating cells being more sensitive than quiescent ones. Two hormones, namely abscisic acid and 2,4-dichlorophenoxyacetic acid (2,4-D), protect cells against the cytokinin-induced death. PCD is not merely a consequence of the inability of the culture to proliferate, since high levels of 2,4-D block carrot cell proliferation without promoting PCD. Increased ethylene production was also observed in BAP-treated cultures, although this increase was not responsible for PCD because inhibitors of ethylene synthesis and action did not block PCD in BAP-treated cultures. Programmed cell death in the form of DNA laddering was also seen in plants treated with cytokinins. This process was accompanied by accelerated senescence in the form of leaf yellowing.

2,4-Dichlorophenoxyacetic Acid↗

PubMed2002

Genetically modified parthenocarpic eggplants: improved fruit productivity under both greenhouse and open field cultivation.

BACKGROUND: Parthenocarpy, or fruit development in the absence of fertilization, has been genetically engineered in eggplant and in other horticultural species by using the DefH9-iaaM gene. The iaaM gene codes for tryptophan monoxygenase and confers auxin synthesis, while the DefH9 controlling regions drive expression of the gene specifically in the ovules and placenta. A previous greenhouse trial for winter production of genetically engineered (GM) parthenocarpic eggplants demonstrated a significant increase (an average of 33% increase) in fruit production concomitant with a reduction in cultivation costs. RESULTS: GM parthenocarpic eggplants have been evaluated in three field trials. Two greenhouse spring trials have shown that these plants outyielded the corresponding untransformed genotypes, while a summer trial has shown that improved fruit productivity in GM eggplants can also be achieved in open field cultivation. Since the fruits were always seedless, the quality of GM eggplant fruits was improved as well. RT-PCR analysis demonstrated that the DefH9-iaaM gene is expressed during late stages of fruit development. CONCLUSIONS: The DefH9-iaaM parthenocarpic gene is a biotechnological tool that enhances the agronomic value of all eggplant genotypes tested. The main advantages of DefH9-iaaM eggplants are: i) improved fruit productivity (at least 30-35%) under both greenhouse and open field cultivation; ii) production of good quality (marketable) fruits during different types of cultivation; iii) seedless fruit with improved quality. Such advantages have been achieved without the use of either male or female sterility genes.

Food Industry↗

PubMed2002

Nitric oxide affects plant mitochondrial functionality in vivo.

In this report, we show that nitric oxide affects mitochondrial functionality in plant cells and reduces total cell respiration due to strong inhibition of the cytochrome pathway. The residual respiration depends on the alternative pathway and novel synthesis of alternative oxidase occurs. These modifications are associated with depolarisation of the mitochondrial membrane potential and release of cytochrome c from mitochondria, suggesting a conserved signalling pathway in plants and animals. This signal cascade is triggered at the mitochondrial level and induces about 20% of cell death. In order to achieve a higher level of cell death, the addition of H(2)O(2) is necessary.

Cell Death↗