In order to provide information on the state of hydration of broilers during marketing, 7-week-old Ross broilers of mixed sex were kept at 17 or 23 degrees C and deprived of food, or food and water, for 24 h. Measurements were made of live weight, carcass weight, muscle moisture, packed cell volume, plasma glucose, corticosterone, total protein, osmolality and sodium. There was a decrease in live weight, carcass weight, plasma glucose and plasma total protein, and an increase in packed cell volume and corticosterone, in birds deprived of food, or food and water. Muscle moisture increased in birds deprived of food and decreased in birds deprived of food and water. Osmolality decreased in birds deprived of food, the decrease being greater in birds at 23 degrees C. Plasma sodium levels were higher in birds kept at 23 degrees C and increased only in birds deprived of food and water at 23 degrees C.

In most publications concerning edible W/O/W-emulsions, the low-HLB emulsifier polyglycerol polyricinoleate (PGPR) is used to stabilize the W/O-interface in combination with a high-HLB emulsifier which stabilizes the O/W-interface. Therefore, PGPR was used as the reference low-HLB emulsifier and compared to two alternative low-HLB emulsifiers namely ammonium phosphatide (AMP) and low-HLB sucrose ester O-170. As high-HLB emulsifiers both random coil (sodium caseinate) and globular proteins (whey protein isolate) were used. Hereby, the use of WPI led to similar, high enclosed water volume fractions for all used low-HLB emulsifiers whereas the use of Na-Caseinate led to almost no enclosed water in the emulsions containing ammonium phosphatide. Finally, the influence of osmotic pressure gradients on the release of an enclosed compound was examined. Therefore, the W/O/W-emulsions were diluted in iso-, hypo- and hypertonic solutions after which the release of an enclosed marker compound was followed over time. Hereby, AMP- and O-170 stabilized W/O/W-emulsions released the enclosed marker due to swelling under hypotonic dilution whereas hyper- and isotonic dilution never led to release of the enclosed marker, regardless of the used low-HLB emulsifier.

This research paper presents the results of tests on the colligative properties of konjac gum chains in water solutions. For this purpose, the measurements of osmotic pressure and intrinsic viscosity of aqueous solutions, in the function of konjac gum concentration and temperature were carried out. The applied methods allowed for the determination of the second osmotic virial coefficients B2, which raised with the increase of temperature. It indicate that increase of temperature causes higher affinity of polysaccharide’s chains to water. It was determined, that the osmotic average molecular mass of the konjac gum in non-purified solutions increases with temperature (1.07×105–3.80×105g×mol−1). Values of the reduced viscosity linearly increased in range 18–29dL×g for all temperatures. Received values of the Huggins constant (0.81–1.72) lead that water is poor solvent for konjac gum. The theta (θ) conditions were extrapolated for non-purified solutions − 325K (52°C), and interpolated for purified solutions − 307K (34°C). Based on the results of tests using the dynamic light scattering, the values of two main relaxation times (fast − 0.4–1.8ms and slow components − 4300–5500ms) were determined (the Kohlrausch-Williams-Watts). The obtained autocorrelation functions were characteristic for sol type systems or these which indicate a gel-like structure.

Some hemipteran xylem and phloem-feeding insects have evolved specialized alimentary structures or filter chambers that rapidly transport water for excretion or osmoregulation. In the whitefly, Bemisia tabaci, mass movement of water through opposing alimentary tract tissues within the filter chamber is likely facilitated by an aquaporin protein. B. tabaci aquaporin-1 (BtAQP1) possesses characteristic aquaporin topology and conserved pore-forming residues found in water-specific aquaporins. As predicted for an integral transmembrane protein, recombinant BtAQP1 expressed in cultured insect cells localized within the plasma membrane. BtAQP1 is primarily expressed in early instar nymphs and adults, where in adults it is localized in the filter chamber and hindgut. Xenopus oocytes expressing BtAQP1 were water permeable and mercury-sensitive, both characteristics of classical water-specific aquaporins. These data support the hypothesis that BtAQP1 is a water transport protein within the specialized filter chamber of the alimentary tract and functions to translocate water across tissues for maintenance of osmotic pressure and/or excretion of excess dietary fluid.

The aim of the study is to introduce the water stress into the modelling of lucerne production. In order to extend the model two contrasted environmental situations, the relationships between the canopy water status (defined as the mean leaf water potential of the upper part of the vegetation; Psif) and the incident solar radiation conversion into harvested production are analysed. For a fully irrigate crop, Gosse et al. showed that above ground biomass production is proportional to the cumulated intercepted radiation. We consider the yield of this conversion as a potential, and our aim is to compute reducing coefficients of the efficiency and the proportion of carbon allocated to the above ground parts. A field experiment shows that the same visible radiation interception laws may be used for values of predawn Psif from -0.3 down to -1.1 MPa. We establish for lucerne the classical relationship between the leaf photosynthesis and Psif. A threshold Psif appears around -1.1 MPa, independent of light intensity. This relationship describes the variations of an irrigated crop experiencing a rapid water stress fairly well. However we find an adaptation which consists in (1) no response to water status variations, and (2) not negligible photosynthetic activity fir low Psif values where irrigated plants would show no photosynthesis at all. A means of taking into account these two orders of variations is proposed. The effect of drought on the carbon repartition is analysed at the field level. Everything goes on as if the above ground growth limitation brought out the biomass redistribution towards the crowns and root system. With such hypotheses, we consider the repartition as the result of the limitation of carbon demand by leaves and stems. Agronomical experiments show that the most sensitive component of production is the stem weight and more particularly the internode length. An empirical relationship between the elongation rate and Psif is described. The analysis of the process strongly suggests that the relationship is indirect. Under certain conditions, the regulations involved would probably concern the wall extensibility rather than the internal tissue turgor. We suggest that such regulations might be interpreted according to the more general anticipation hypothesis from Piaget.The organization of the model is described. It presents the synthesis at the crop level of analytical and empirical relationships between the canopy water status (Psif) and some important biological process previously discussed. | L'objectif de l'étude est l'introduction de la contrainte hydrique dans la modélisation de la production de luzerne en fonction du climat, au niveau agronomique et dans le cas d'une repousse.Afin de pouvoir généraliser le modèle à des environnements divers, les relations entre l’état hydrique du couvert (défini par le potentiel hydrique foliaire moyen de la tranche supérieure de végétation Psif) et l’efficience de conversion de l’énergie solaire incidente en biomasse aérienne récoltable sont analysées. Pour une culture irriguée Gosse et al ont montré que la production e biomasse aérienne est proportionnelle à la somme de rayonnement visible intercepté. Nous considérerons le rendement de cette conversion comme un potentiel et notre but est de calculer des coefficients réducteurs de l’efficience et de la part de carbone allouée aux parties aériennes.Une expérimentation au champ nous a permis de monter que la même loi d’interception du rayonnement visible en fonction de l’indice foliaire peut s’appliquer pour des valeurs de Psif variant de -0.3 à -1.1MPa. Nous établissons pour la luzerne la relation classique entre photosynthèse de la feuille et son potentiel hydrique faisant apparaître un seuil de -1.1 Mpa, indépendant de l’éclairement. Cette relation décrit correctement le cas d’une culture irriguée subissant une sécheresse limitée dans le temps (Psif à l’aube >= -2.2 Mpa). Mais nous avons montré que l’adaptation se traduit sur la courbe de réponse de de la photosynthèse nette à l’éclairement par (1) une absence de sensibilité au Psif dans la gamme observée, (2) une réponse photosynthétique non négligeable à des potentiels pour lesquels la photosynthèse en irrigué serait nulle. Nous proposons une façon de tenir compte de ces deux ordres de variation dans le calcul de coefficient réducteur de l’efficience de conversion du rayonnement intercepté en biomasse. L’effet de la sécheresse sur la répartition du carbone assimilé par le couvert est analysé au champ. Tout se déroule comme si la limitation de la croissance des parties aériennes entrainait une redistribution de la biomasse entre parties récoltées et non récoltées. Sous cette hypothèse nous traitons la répartition comme le résultat de la diminution de la demande en carbone des tiges feuillées. Les expérimentations au niveau agronomique montrent que la composante du niveau de production la plus sensible est le poids de tiges, et plus particulièrement la longueur des entrenœuds. Une relation empirique entre la vitesse d’allongement des tiges et Psif est présentée à partir de résultats de la biliographie et de nos résultats expérimentaux (conditions contrôlées). L’analyse du phénomène grâce au modèle de Lokhart incite à penser que la relation entre l’état hydrique et la vitesse d’allongement serait indirecte. Dans certaines conditions, les mécanismes de régulation mis en œuvre concerneraient très probablement l’extensibilité plutôt que la pression hydraulique interne des tissus. Nous suggérons que ce type de régulation puisse s’interpréter en terme d’anticipation des conditions climatiques probables, selon l’hypothèse de Piaget.Le plan du modèle en cours de validation est décrit. Il présente la synthèse au niveau du peuplement végétal des relations empiriques et Psif et certains des processus biologiques.