Technical report: Optimization of the harvest stage for reducing cooking banana postharvest losses: a multi-criteria approach targeting matooke end-product.

This report presents results of RTB-ENDURE sub-output 1.3; ‘Determining appropriate harvest time for the cooking bananas with intrinsic long shelf-life using physical, chemical and sensory attributes’ of the cooking banana business case’s Output 1, entitled “Increased access of farmers to cooking banana varieties with preferred quality attributes and intrinsic long shelf life traits”. The worked aimed at reducing postharvest losses for cooking banana while modulating harvest stage for green life extension. The originality of this investigation was to evaluate the putative impact of fruit stage of harvest onto its potential storage life and eating quality. The optimal harvest stage was evaluated by coupling three antagonist parameters, namely fruit diameter, green life, and eating quality, to optimize harvest stage of the variety Kibuzi in specific edapho-climatic conditions of Rakai and Isingiro districts in southwestern Uganda. A temperature record was considered in both sites between flowering and harvest. The interval between flowering and harvest (IFH) of Kibuzi banana variety was used as a quantitative explanatory variable, and the site location (Rakai at 1270 masl vs Isingiro at 1440 masl) was used as a qualitative one. Since the sites were at different altitudes, two Tynitag temperature data loggers were installed to record temperatures. Fruits size, dry matter, fruit firmness, total soluble solids, titratable acidity and sensory attributes were recorded at four harvest stages: 112, 126, 138, 152 days and 111, 125, 137, 151 days after flowering. The evolution of three parameters; diameter of fruit, green life and overall acceptability of the end-product - Matooke - were simulated for 110 to 155 days range, leading to the identification of a range of optimal harvest ages for variety Kibuzi in Rakai at between 133 to 142 days and 133 to 150 days for Isingiro. The prediction of the optimal harvest stage will remain only valid for the two locations without taking into account thermal sum for establishing a strong relationship between fruit age in degree.days and green life. Given the respective altitudes at Rakai and Isingiro, it implies that the two edapho-climatic conditions were not so different in terms of on field temperature. With some more diverse thermal conditions in the experimental sites (lowland vs highland with at least 3°C needed between sites), the thermal sum concept will be even more precise for the prediction of the optimal harvest stage for bananas, regardless the location site (lowland, highland, with hot or cool local conditions). Such original multi-criteria approach (agro-morphological, physiological traits, and end-product sensory attributes) was relevant for the prediction of the optimal harvest stage, in order to reduce banana postharvest losses during transport and until Matooke preparation by end-users. Such innovative methodology can be applied to some other banana culinary recipes and end-uses

Suppression traductionnelle des codons stop chez les mammifères

Nonsense mutations, also known as premature termination codons (PTCs) are responsible for 10% to 30% of all human genetic diseases. Nonsense translation suppression can be induced by readthrough inducers. The presence of such PTC leads to premature translation termination. These stop therapeutic strategies have emerged which attempt to use molecules that facilitate tRNA incorporation at the PTC (readthrough). The, translation continue in the same reading frame until the next stop codon. I first developed an innovative screening system I used to test more than 17,000 molecules and have identified one hit, TLN468 molecule. I have shown that this molecule is able to induce re-expression of an active p53 protein.I also characterized new compounds derived from aminoglycosides. I have shown that the NB124 induces apoptosis of tumor cells by re-expressing p53 protein while having a much lower toxicity than gentamicin.I developed a single molecule approach for studying the ribosome programmed errors (recoding). I was able to analyze the kinetics of elongation eukaryotic ribosomes and showed that the initiation of translation at an internal entry site (IRES) slows the ribosome during the first elongation cycle.Entre 10% et 30% des maladies humaines sont liées à l'apparition d'une mutation non-sens (PTC). La synthèse protéique est alors arrêté prématurément. Cet arrêt peut être inhibé par des molécules inductrices de translecture qui permettent l’incorporation d’un ARNt suppresseur naturel au niveau du PTC (translecture). Le ribosome peut alors franchir le PTC et restaurer l’expression de la protéine.Au cours de ma thèse, je me suis intéressé à la suppression des codons stop en caractérisant de nouvelles molécules inductrices de translecture et en analysant les mécanismes de la fidélité de la traduction.J’ai tout d’abord mis au point un système de criblage innovant avec lequel j’ai testé plus de 17 000 molécules et identifié la molécule TLN468. J’ai pu mettre en évidence que cette molécule est capable d’induire la réexpression d’une protéine p53 active.J'ai aussi caractérisé de nouveaux composés dérivés d’aminoglycosides. J’ai pu montré que le NB124 est capable d’induire l’apoptose de cellules tumorales via la réexpression de la protéine p53 tout ayant une toxicité bien plus faible que la gentamicine.En parallèle, j’ai développé une approche en molécule unique permettant d’étudier les erreurs programmées du ribosome (recodage). J’ai ainsi pu analyser la cinétique d’élongation des ribosomes eucaryotes et montré que l’initiation de la traduction sur un site d’entrée interne (IRES) ralentit le ribosome lors des premiers cycles d’élongation

Translational suppression of stop codons in mammals

Entre 10% et 30% des maladies humaines sont liées à l'apparition d'une mutation non-sens (PTC). La synthèse protéique est alors arrêté prématurément. Cet arrêt peut être inhibé par des molécules inductrices de translecture qui permettent l’incorporation d’un ARNt suppresseur naturel au niveau du PTC (translecture). Le ribosome peut alors franchir le PTC et restaurer l’expression de la protéine.Au cours de ma thèse, je me suis intéressé à la suppression des codons stop en caractérisant de nouvelles molécules inductrices de translecture et en analysant les mécanismes de la fidélité de la traduction.J’ai tout d’abord mis au point un système de criblage innovant avec lequel j’ai testé plus de 17 000 molécules et identifié la molécule TLN468. J’ai pu mettre en évidence que cette molécule est capable d’induire la réexpression d’une protéine p53 active.J'ai aussi caractérisé de nouveaux composés dérivés d’aminoglycosides. J’ai pu montré que le NB124 est capable d’induire l’apoptose de cellules tumorales via la réexpression de la protéine p53 tout ayant une toxicité bien plus faible que la gentamicine.En parallèle, j’ai développé une approche en molécule unique permettant d’étudier les erreurs programmées du ribosome (recodage). J’ai ainsi pu analyser la cinétique d’élongation des ribosomes eucaryotes et montré que l’initiation de la traduction sur un site d’entrée interne (IRES) ralentit le ribosome lors des premiers cycles d’élongation.Nonsense mutations, also known as premature termination codons (PTCs) are responsible for 10% to 30% of all human genetic diseases. Nonsense translation suppression can be induced by readthrough inducers. The presence of such PTC leads to premature translation termination. These stop therapeutic strategies have emerged which attempt to use molecules that facilitate tRNA incorporation at the PTC (readthrough). The, translation continue in the same reading frame until the next stop codon. I first developed an innovative screening system I used to test more than 17,000 molecules and have identified one hit, TLN468 molecule. I have shown that this molecule is able to induce re-expression of an active p53 protein.I also characterized new compounds derived from aminoglycosides. I have shown that the NB124 induces apoptosis of tumor cells by re-expressing p53 protein while having a much lower toxicity than gentamicin.I developed a single molecule approach for studying the ribosome programmed errors (recoding). I was able to analyze the kinetics of elongation eukaryotic ribosomes and showed that the initiation of translation at an internal entry site (IRES) slows the ribosome during the first elongation cycle

Timing the ribosome with fluorescent markers

séminaire, 23 mai au laboratoire LPEM, ESPCI, présenté par Nathalie Westbroo

Cinétique de traduction eucaryote en molécule unique ou comment chronométrer un ribosome mammifère grâce à l'optique (Poster)

Poster présenté par Nathalie BarbierNational audienc

Toward the study of eukaryotic translation recoding events by single molecule fluorescence microscopy (Orale)

communication orale invitée (session étudiante) présentée par Nathalie BarbierInternational audienc

Characterization of new-generation aminoglycoside promoting premature termination codon readthrough in cancer cells

Nonsense mutations, generating premature termination codons (PTCs), account for 10% to 30% of the mutations in tumor suppressor genes. Nonsense translational suppression, induced by small molecules including gentamicin and G418, has been suggested as a potential therapy to counteract the deleterious effects of nonsense mutations in several genetic diseases and cancers. We describe here that NB124, a synthetic aminoglycoside derivative recently developed especially for PTC suppression, strongly induces apoptosis in human tumor cells by promoting high level of PTC readthrough. Using a reporter system, we showed that NB124 suppressed several of the PTCs encountered in tumor suppressor genes, such as the p53 and APC genes. We also showed that NB124 counteracted p53 mRNA degradation by nonsense-mediated decay (NMD). Both PTC suppression and mRNA stabilization contributed to the production of a full-length p53 protein capable of activating p53-dependent genes, thereby specifically promoting high levels of apoptosis. This new-generation aminoglycoside thus outperforms the only clinically available readthrough inducer (gentamicin). These results have important implications for the development of personalised treatments of PTC-dependent diseases and for the development of new drugs modifying translation fidelity

A comparative kinetic study of non-canonical eukaryotic translation initiation with IRES structures by single molecule fluorescence microscopy

International audienc