ADVERSE EFFECTS OF HUMIC SUBSTANCES FROM DIFFERENT ORIGIN ON LUPIN AS RELATED TO IRON SOURCES

Humic substances improve the efficiency of different iron (Fe) sources overcoming Fe deficiency chlorosis of plants. However, applied at high rates, they can promote negative effects on plants. The main objective of this work was to study the potential adverse effect of three humic acids from different origin when they were applied with two effective Fe sources for plants: Fe- ethylenediaminedihydroxyphenylacetic acid (EDDHA) and Vivianite. To this end, an experiment with lupin (Lupinus albus L.) was performed involving two factors: (i) Fe source, and (ii) humic substances from three different origin (composted cork, leonardite, and compost obtained from a mixture of olive husk with cotton gin trash) applied at 0, 0.1, and 0.5 g organic carbon (C) kg^?1 of growing media. At the rates used, humic substances promoted adverse effects on plant development, chlorophyll meter readings, and Fe content in lupin grown in calcareous media. Overall, the effect on dry matter and Fe content in plants was more relevant when Fe was supplied with Vivianite, the effect on chlorophyll meter readings being more significant when Fe was applied as Fe-EDDHA. Differences were also observed depending on the source of humic substances, those from leonardite promoting the greatest decrease in dry matter in roots and shoots. These humic substances possessed the highest values of spectroscopy index for aromaticity (A₂₅₄ ). On the other hand, the application of humic substances from olive husk compost, which exhibited the lower aromaticity index, resulted in the smallest decrease in dry matter production and chlorophyll meter readings. Dry matter in roots decreased logarithmically with increased values of the estimates of the amounts of aromatic compounds accumulated in the growing media (R² = 0.92; P < 0.01) with Vivianite as Fe source. Thus, the effects decreasing dry matter production, particularly in roots, and chlorophyll meter readings can be ascribed at least partially to the presence of phytotoxic aromatic compounds in humic substances.     

Culture system and long-term storage of culture media in the in vitro production of bovine embryos

The optimum culture system for in vitro matured and fertilised oocytes still remains to be clarified. Culture media (CM) for mammalian embryos are routinely prepared fresh for use and preserved under refrigeration during one or two weeks. The purposes of this work were (1) to compare the efficiency of a synthetic oviduct fluid (SOF) with two different bovine serum albumin (BSA) concentrations (3 and 8 g/L) for the in vitro production of bovine blastocysts, (2) to test the effect of timing on adding fetal calf serum (FCS) to the SOF, and (3) to evaluate the effects on bovine embryo development of freezing and lyophilisation as procedures for preserving the SOF. Supplementation of SOF with 3 g/L BSA increased Day-7 blastocyst expansion rates (18.3 ± 1.6 vs. 14.4 ± 0.7; P < 0.05), although no differences in hatching rates were found. Addition of FCS to SOFaa (SOF with amino acids) medium supplemented with sodium citrate (SOFaaci) at 48 and at 72 h post-insemination (PI) allowed obtaining higher Day-6 embryo development rates than when FCS was added at 18 or 96 h PI (Day-6 morulae + blastocyst rate: 30.0 ± 1.1, 40.8 ± 1.1, 43.9 ± 2.3 and 39.3 ± 0.5 for FCS addition at 18, 48, 72 and 96 h, respectively). Hatching rates were significantly improved when serum was added at 72 h PI. Finally, both refrigeration and lyophilisation appeared as useful cryopreservation procedures for SOFaaci, although a significant loss of its ability to support embryo development, compared to the control fresh culture medium, was observed.     

Transpiration and forest structure in relation to soil waterlogging in a Hawaiian montane cloud forest

Transpiration, leaf characteristics and forest structure in Metrosideros polymorpha Gaud. stands growing in East Maui, Hawaii were investigated to assess physiological limitations associated with flooding as a mechanism of reduced canopy leaf area in waterlogged sites. Whole-tree sap flow, stomatal conductance, microclimate, soil oxidation-reduction potential, stand basal area and leaf area index (LAI) were measured on moderately sloped, drained sites with closed canopies (90%) and on level, waterlogged sites with open canopies (50-60%). The LAI was measured with a new technique based on enlarged photographs of individual tree crowns and allometric relationships. Sap flow was scaled to the stand level by multiplying basal area-normalized sap flow by stand basal area. Level sites had lower soil redox potentials, lower mean stand basal area, lower LAI, and a higher degree of soil avoidance by roots than sloped sites. Foliar nutrients and leaf mass per area (LMA) in M. polymorpha were similar between level and sloped sites. Stomatal conductance was similar for M. polymorpha saplings on both sites, but decreased with increasing tree height (r(2) = 0.72; P < 0.001). Stand transpiration estimates ranged from 79 to 89% of potential evapotranspiration (PET) for sloped sites and from 28 to 51% of PET for level sites. Stand transpiration estimates were strongly correlated with LAI (r(2) = 0.96; P < 0.001). Whole-tree transpiration was lower at level sites with waterlogged soils, but was similar or higher for trees on level sites when normalized by leaf area. Trees on level sites had a smaller leaf area per stem diameter than trees on sloped sites, suggesting that soil oxygen deficiency may reduce leaf area. However, transpiration per unit leaf area did not vary substantially, so leaf-level physiological behavior was conserved, regardless of differences in tree leaf area.     

Effects of Annealing and Concentration of Calcium Salts on Thermal and Rheological Properties of Maize Starch During an Ecological Nixtamalization Process

The objective of the present work was to study the effect of annealing and concentration of Ca(OH)₂ (lime) and calcium salts on the thermal and rheological properties of maize starch during an ecological nixtamalization process. Thermal and rheological properties of maize starch changed during the ecological nixtamalization process because of three main causes: the annealing phenomenon, type of calcium salt, and calcium salt concentration. In all treatments thermal properties (T_o, T_p, and T_f) of nixtamal starch increased owing to the annealing process, whereas the type of salt or lime increased thermal properties and decreased pasting properties in this order: CaCl₂ > CaSO₄ > Ca(OH)₂ ≈ CaCO₃. This behavior was because of the dissociation of each salt or lime in water. Anions (OH⁻) can penetrate much more easily into the starch granule and start the gelatinization process by rupturing hydrogen bonds. Additionally, amylose‐lipid complexes were formed during the nixtamalization processes, as indicated by an increasing peak at 4.5 Å in X‐ray diffraction patterns.     

The industries of the future in Mexico: Local and non-local effects in the localization of “knowledge-intensive services”

The current characteristics in the global economy have defined “knowledge-intensive services” (KIS) as part of the so-called “industries of the future” due to the attributes of their employment and central function in the development processes in science, technology, art, and culture. This study outlines as a central hypothesis that the localization of KIS depends on different factors according to the type of knowledge being developed (analytical, synthetic, and symbolic). The main objective in this work is to explore the spatial economic factors associated with the localization and changes (positive and negative) when using KIS in the “national urban system” in México between 2004 and 2014. To do so, the services sector is defined according to the “intensity” and the “types” of knowledge that they develop. An analysis of spatial econometrics is carried out that distinguishes between the geographic (local) effect and the spatial (non-local) effect of the independent variables using data and microdata from the period 2004 to 2014. The results partly correspond with the central hypothesis of the study and offer possibilities of public policies to take advantage of and to promote the benefits of KIS, especially regarding cities in developing countries looking to become part of the 21st century economy.     

Attainment of Puberty in the European Mouflon (Ovis gmelini musimon) and the Domestic Manchega Ewe (Ovis aries)

The onset of puberty was assessed from plasma progesterone profiles for Mouflon (n = 8) and Manchega (n = 7) female lambs born in April. Four Mouflons exhibited their first ovulation at a mean date of 27 November ± 1.4 days, the mean age being 248.5 ± 3.9 days and the mean body weight 23.8 ± 0.6 kg. The remaining four Mouflons, which had a slower growth rate, attained puberty during the autumn of the following year. Five of seven Manchega lambs attained puberty in their first year at a mean date of 5 Oct ± 3.3, the mean age being 185.6 ± 2.6 days and the mean body weight 41.8 ± 2.0 kg. The mean live‐weight at the onset of puberty was 65.1 and 82% (p < 0.05) of adult body weights for Manchega and Mouflons, respectively. Overall, the results indicate that there is a threshold of body‐weight necessary for the attainment of puberty in the first breeding season for spring‐born lambs, which is very different between both Mouflon and Manchega. When body weight was below 23.8 ±0.6 and 41.8 ± 2.0 kg for Mouflon and Manchega lambs, respectively, first ovulation did not occur until the beginning of the next breeding season. The onset of puberty during the second year of life occurred within the specific reproductive seasons for Mouflon (October–April) and Manchega (July–March) ewes, despite minimal further growth.     

Seasonal and temporal changes in species use of the landscape: how do they impact the inferences from multi-scale habitat modeling?

Context

Multi-scale approaches to habitat modeling have been shown to provide more accurate understanding and predictions of species-habitat associations. It remains however unexplored how spatial and temporal variations in habitat use may affect multi-scale habitat modeling.

Objectives

We aimed at assessing how seasonal and temporal differences in species habitat use and distribution impact operational scales, variable influence, habitat suitability spatial patterns, and performance of multi-scale models.

Methods

We evaluated the environmental factors driving brown bear habitat relationships in the Cantabrian Range (Spain) based on species presence records (ground observations) for the period 2000–2010, LiDAR data on forest structure, and seasonal estimates of foraging resources. We separately developed multi-scale habitat models for (i) each season (spring, summer, fall and winter) (ii) two sub-periods with different population status: 2000–2004 (with brown bear distribution restricted to the main population nuclei) and 2005–2010 (with expanding bear population and range); and (iii) the entire 2000–2010 period.

Results

Scales of effect remained considerably stable across seasonal and temporal variations, but not the influence of certain environmental variables. The predictive ability of multi-scale models was lower in the seasons or periods in which populations used larger areas and a broader variety of environmental conditions. Seasonal estimates of foraging resources, together with LiDAR data, appeared to improve the performance of multi-scale habitat models.

Conclusions

We highlight that the understanding of multi-scale behavioral responses of species to spatial patterns that continually shift over time may be essential to unravel habitat relationships and produce reliable estimates of species distributions.