Crystallographic Studies of Enzymes (Volume II)

In this Special Issue of Crystals, entitled "Crystallographic Studies of Enzymes (Volume II)", eleven research papers on key findings and methodologies of structure, function, and reaction mechanisms of enzymes are presented

Impact des conditions de culture in vitro et du saccharose exogène sur la régulation de l'expression génique et l'accumulation des protéines chez les plantules de tomate (Solanum lycopersicum)

La micropropagation est une technique efficace pour multiplier rapidement in vitro plusieurs espèces de végétaux. Cependant, les conditions de culture in vitro sont très différentes des conditions naturelles ce qui entraîne, lors du transfert ex vitro, la mortalité de plusieurs plantules. On sait que les conditions de culture in vitro et le saccharose exogène ont un effet majeur sur la photosynthèse et le succès lors de l'acclimatation. Dans cette thèse, nous avons étudié la réponse métabolique des plantules de tomate (Solanum lycopersicum) aux conditions de culture in vitro et à la présence de saccharose dans le milieu de culture. Dans un premier temps, nous avons observé que l'environnement in vitro, comparativement aux conditions ex vitro, entraîne la surexpression de gènes impliqués dans la photosynthèse et l'assimilation de l'azote, la sousexpression des gènes liés à la force des puits et l'induction d'une réponse de stress chez les plantules de tomates. Dans un deuxième temps, nous avons observé que le retrait du saccharose lors du transfert ex vitro stimule à court terme la biosynthèse de l'éthylène et initie une cascade signalétique causant une modification des propriétés de la paroi et une stimulation des gènes de défense. Dans un dernier temps, l'étude de l'impact à long terme du saccharose exogène sur le proteome des plantules à montrer un rôle central de ce facteur dans la régulation de la prolifération cellulaire, la photosynthèse et le mécanisme de défense contre les espèces réactives de l'oxygène. Globalement, la perturbation du métabolisme des espèces réactives de l'oxygène (ROS), de la paroi cellulaire, du système de défense, et du développement et de la division des cellules sont des réponses prédominantes chez les plantules en culture in vitro et lors de l'acclimatation. Ces données ont permis de mieux expliquer le phénotype des plantules in vitro et leur impact sur l'acclimatation devra inévitablement être mesuré dans le futur

Plant Physiology, Development and Metabolism

Water is one of the most important constituents of life. Chemically, water is the hydride of oxygen. Oxygen, being more electronegative, exerts a strong attractive pull on its electrons. This unequal attraction results in small positive charge on twohydrogenmoleculesandasmallnegativechargeontheoxygenmolecule.The two lone pairs of electrons of the oxygen molecule result in bending of water molecule. The partial charges on oxygen and hydrogen molecules result in high electric dipole moment and polarity of water molecule

Oxidative Stress in Plants

Plants are continuously exposed to different environmental stress conditions that have a huge impact on agriculture worldwide, consequently leading to massive economic losses. These adverse conditions alter the metabolism of reactive oxygen and nitrogen species (ROS and RNS). High concentrations of these reactive species—that exceed the capacity of antioxidant defense enzymes—disturb redox homeostasis, which can trigger damage to such macromolecules as membrane lipids, proteins, and nucleic acids, ultimately resulting in nitro-oxidative stress and plant cell death. Significant progress has been made to understand how plants persist in these stressful environments which could be vital to improving plant crop yield. This Special Issue “Oxidative Stress in Plants” includes both original research articles and detailed reviews that aim to better understand the nitro-oxidative stress networks in higher plants, and the addressed topics provide updated and new knowledge about ROS and RNS metabolism in plant responses to abiotic stress as well as the modulation of antioxidant systems in the control of ROS production and accumulation

ACARORUM CATALOGUS IX. Acariformes, Acaridida, Schizoglyphoidea (Schizoglyphidae), Histiostomatoidea (Histiostomatidae, Guanolichidae), Canestrinioidea (Canestriniidae, Chetochelacaridae, Lophonotacaridae, Heterocoptidae), Hemisarcoptoidea (Chaetodactylidae, Hyadesiidae, Algophagidae, Hemisarcoptidae, Carpoglyphidae, Winterschmidtiidae)

The 9th volume of the series Acarorum Catalogus contains lists of mites of 13 families, 225 genera and 1268 species of the superfamilies Schizoglyphoidea, Histiostomatoidea, Canestrinioidea and Hemisarcoptoidea. Most of these mites live on insects or other animals (as parasites, phoretic or commensals), some inhabit rotten plant material, dung or fungi. Mites of the families Chetochelacaridae and Lophonotacaridae are specialised to live with Myriapods (Diplopoda). The peculiar aquatic or intertidal mites of the families Hyadesidae and Algophagidae are also included.Publishe

BIOTEC’98: book of abstracts

IV Iberian Congress on Biotechnology; I Ibero-American Meeting on BiotechnologyFundação para a Ciência e a Tecnologia (FCT

Investigations into the chemical analysis and bioactivity of plant proanthocyanidins to support sustainable livestock farming

Proanthocyanidins (PA) in some forage legumes have been linked to contradictory effects in animal health and nutrition. Ruminants fed with PA-containing plants do not suffer from bloat and can also reduce gastrointestinal parasite infections, improve protein use efficiency and reduce greenhouse gas emissions. Plants have a wide range of PA contents and compositions. Therefore, screening tools are required to determine the optimal contents and types to exploit PA bioactivities on farms. This research initially focused on the identification and isolation of PAs with contrasting characteristics from various plant species. These samples were then used to develop novel methods such as UPLC-ESI-MS/MS and 13C HSQC NMR for extractable PAs and 13C CPMAS NMR for PAs within plants, and to probe structure-activity relationships. These PAs were also subjected to complementary analytical methods, which demonstrated that depolymerisation techniques can provide quantitative information on PA contents and compositions and mass spectrometric techniques on molecular distributions. These analyses revealed an enormous range of molecular profiles. This diversity, however, led to good but not excellent correlations between the degradation methods. It also affected mass spectrometric and liquid-state NMR responses. In particular, there were some discrepancies between thiolysis-HPLC and UPLC-ESI-MS/MS results of sainfoin PA extracts. For solid-state NMR, the PAs from model plants proved too homogeneous for the analysis of the highly complex PAs in sainfoin plants. Nevertheless, this method could rank accessions on the basis of PA composition and discriminated between plant organs via signature spectra. Therefore, final decisions on which of these methods to use will depend on the research objectives and sample numbers. Finally, anti-parasitic assays discovered that the in vitro exsheathement inhibition of the abomasal parasite, Haemonchus contortus was dependent on the average molecular size of purified PA mixtures. In addition, collaborative studies showed that prodelphinidins or PA size also affected some anti-parasitic and ruminal fermentation results