Inhibition of formaldehyde production in frozen-stored minced blue whiting (Micromesistius poutassou) muscle by cryostabilizers: an approach from the glassy state theory

Adding maltodextrins to minced blue whiting muscle inhibited formaldehyde production during storage at -10 and -20 degrees C. Sucrose, however, was effective only at -20 degrees C. These results were not proportional to the difference between the storage temperature and the ice-melting onset (T(m)'), and freeze-concentration had to be considered. In the face of serious limitations to do this, resource was made to the state diagram for the sucrose-water binary system and the percentage variation of the ice-melting endotherm area of the different samples. A higher T(m)' and a lower freeze-concentration would account for the inhibiting effects of maltodextrins, whereas sucrose, despite diminishing T(m)', had an effect nearly as great as maltodextrins at -20 degrees C but had hardly any at -10 degrees C. The reason for this seems to lie in a lower freeze-concentration of solutes in the unfrozen water phase. Similarly, the differences found between sucrose and maltodextrins, as well as among maltodextrins, were also explained in terms of T(m)' and freeze-concentration.     

Tyrosine phosphorylation is not a relevant mechanism to modulate aquaporin 2 activity in gestational queen endometrium and placenta

Aquaporins have been shown to be regulated by phosphorylation of serine residues, but the possible role of tyrosine residues phosphorylation has not been evaluated. Changes in the localization of aquaporin 2 (AQP2) in the queen endometrium have been related to serum progesterone levels. The aim of this study was to determine whether these AQP2-localization changes are mediated by variations in its tyrosine phosphorylation levels. Twelve queens were included in the study and divided into (a) non-macroscopically pregnant with low levels of progesterone; (b) non-macroscopically pregnant with high levels of progesterone; (c) 30 days of pregnancy; and (d) 60 days of pregnancy. Samples from endometrium and placental transference zone were obtained, immunoprecipitated and analysed by immunoblotting to determine the abundance of AQP2 and its relative levels of tyrosine phosphorylation. No significant differences in the tyrosine phosphorylation levels of immunoprecipated-AQP2 were observed between groups. We can thus conclude that changes in the localization of AQP2 in the queen endometrium are not modulated by tyrosine phosphorylation.     

The role of bromeliads in rural livelihoods: An experience in Oaxaca,Mexico

ABSTRACT

The aim of this article is to analyze the commercialization of bromeliad plants as an alternative for diversification in Mandimbo Village, Oaxaca, Mexico. We follow the livelihood assets approach to examine natural, social, physical, human, and financial capitals. This study was conducted using surveys of village households, working group sessions with heads of family, and in-depth interviews of participants in the bromeliad initiative. The results show that after 10 yr of work, the bromeliad initiative has not been consolidated. The village has developed abundant natural and social capital, but less human, physical, and financial capital. We conclude that for progress of the initiative to occur, the main objectives need to be clarified and agreements between different parties of interest—the villagers, regional nongovernmental organizations (NGOs), and research institutions—need to be established, as these can facilitate a successful financial strategy.     

Growth,biomass, carbon and nutrient pools in Gmelina arborea established in pure and mixed forest stand production systems in Mexico

New Forests - Melina (Gmelina arborea) is a fast-growing tree species that is widely used throughout the world for various purposes. The aims of this research were to evaluate the biomass...     

Modelling dominant height growth in plantations of Pseudotsuga menziesii (Mirb.) Franco in Spain

A model for predicting dominant height growth and site index of Pseudotsuga menziesii (Mirb.) Franco in Spain was constructed. Data from stem analysis of 117 site trees were used. Four dynamic equations using the algebraic difference approach (ADA) and its generalisation (GADA), which have provided good results in previous studies, were evaluated. The model parameters were estimated with the base?age?invariant method of dummy variables, which considers both global (common to all sites) and local parameters (specific to each site). A GADA equation based on the Bertalanffy–Richards base model yielded the best results. The model provides polymorphic curves with multiple asymptotes. A base age of 20 years is proposed to reference site index.     

Physiological response to pruning severity in Eucalyptus regnans plantations

The photosynthetic response to pruning was measured in two Eucalyptus regnans stands, aged 2 and 3 years, located in areas of high productivity on the coast of the province of Arauco, Chile. Variables such as rates of CO₂ assimilation and stomatal conductance were measured in three ages of foliage on trees with different pruning severity treatments, which corresponded to the removal of 0 % (control), 30, 50 and 70 % of live crown length. The 2-year-old stand measurements were performed at the time of pruning and 6, 10, 14 and 18 weeks later, and the 3-year stand, 5, 9, 18 and 28 weeks after pruning. In both trials, significant differences were found between the foliage ages for all instances of measurement showing the mature foliage the highest values up to 30 % higher than old foliage. There were also significant differences between pruning severity treatments in both trials in which, in general, the highest values of CO₂ assimilation were observed among the highest pruning severity treatments with values up to 40 % higher than the unpruned trees.     

A taper function for Pseudotsuga menziesii plantations in Spain

Five stem taper models belonging to three different taper function categories were fitted to data corresponding to 282 Pseudotsuga menziesii trees. The trees were selected in the area surrounding 61 research plots installed in Galicia, Asturias and the Basque Country, northern Spain. The models were simultaneously fitted to observed values of diameter outside bark and inside bark. A third-order continuous-time autoregressive error structure was used to account for autocorrelation. Selection of the best model was based on both numerical (goodness-of-fit statistics) and graphical analysis (plots of residuals against position along the stem and against tree size). The three-segmented taper model finally selected has the advantage of being compatible with both a merchantable and a total stem volume equation.     

Seasonal and spatial mortality patterns of holm oak seedlings in a reforested soil infected with Phytophthora cinnamomi

The viability of 1-year-old holm oak (Quercus ilex) seedlings in a soil naturally infected with Phytophthora cinnamomi was studied during 2 consecutive years in a plot located in south-western Spain. In both years, total mortality during autumn and winter was not noticeable (<2.1%). In spring, mortality levels were higher (8.3–4.6%), especially the first year. A steep increase in total mortality occurred in summer, both in the first (11.4%) and second (24.2%) year, but mortality attributable to P. cinnamomi was 1.9 and 7.6%, respectively. Thus, 2 years after planting, total cumulative mortality was 43.4%, and that attributable to P. cinnamomi 9.6% (i.e. 22.1% of total mortality). Fungus-derived mortality followed a spatially aggregated pattern in the reforestation plot, suggesting a clustered distribution of the inoculum in the soil. Furthermore, mortality by P. cinnamomi was also associated with nearness of infected adult trees in the plot. Results obtained are discussed in the framework of seasonal water deficit, P. cinnamomi damage, weed competition and sanitation techniques to be used in declined holm oak stands in Spain.     

Modelling mortality of Scots pine (Pinus sylvestris L.) plantations in the northwest of Spain

Mortality is an important element of growth and yield models, especially if only low intensity silvicultural treatments are carried out. The objective of the present study was to develop a model for predicting tree number decline in planted even-aged stands of Scots pine (Pinus sylvestris L.) in Galicia (northwestern Spain). The model was constructed using data from two inventories of a trial network involving 68 permanent plots located in unthinned stands, or stands thinned lightly from below. Two alternatives were tested. In one alternative, a two-step modelling strategy was applied. First, a binary response function predicting the survival probability of all the trees in the stand was constructed, and an equation for reduction in tree number was developed, using only data where death had occurred over the period analyzed. Three different approaches were then used to compare the application of the above-mentioned functions together. In the other alternative, a mortality function for directly predicting the reduction in tree number was fitted, including all plots (with and without occurrence of mortality). Both alternatives provided similar results, showed logical behavior, and performed satisfactorily in evaluation tests. However, in choosing the best strategy for inclusion in a stand-level simulator, the use of the second alternative is recommended because it possesses the path invariance property required in a mortality model.