Changes in inorganic and organic solutes in citrus growing under saline stresses

Salinity is a key factor limiting cirrus production in many world areas. The two citrus genotypes sour orange (Citrus aurantium L) and macrophylla (Citrus macrophylla Wester), that differ in their ability to restrict sodium (Na) and chloride (Cl) transport to the shoot under salt stress, were studied to compare the contribution of both inorganic and organic solutes in osmotic adjustment. Plants of both citrus genotypes were grown in isosmotic (0.23 MPa) solutions of different ionic composition (Na, NaCl, Cl, and concentrated macronutrients), and leaf and root solutes were measured to determine their relative contribution to osmotic adjustment. Both leaf water and osmotic potentials decreased in response to imposed stress in the nutrient media, regardless of the isosmotic treatment. Growth reduction was more severe in macrophylla than in sour orange, except for macronutrient treatment. The major components associated with the osmotic adjustment were inorganic solutes (ranging from 65 to 85% of total solutes) and organic solutes (ranging from 15 to 35%, depending on the genotype and the isosmotic treatment). Among these, carbohydrates were the major organic components (6–24%), with glucose the main osmoregulating sugar in Cl‐containing treatments. The contribution of the organic acids and amino acids to the osmotic adjustment of plant under saline stress seemed to be less important in these citrus species.     

Light distribution in scattered-trees open woodlands in Western Spain

We have studied the percentage of radiation transmitted through the tree canopy to the underlying pasture and crops in dehesas of Southwest Spain by means of fish-eye photographs taken at different distances from the tree. Thirty-six trees were studied covering all the diametric classes (0.1–14 m canopy width) of two stands, with mean density of 19 mature trees ha⁻¹. Intercepted light decreased with distance following an logistic curve, indicating a rapid increase in the light availability with distance from the tree. For mature trees, radiation was constant beyond 20 m. Applying a multivariable regression light equation, distance, stem diameter and canopy width explained more than 88% of the light variability for each orientation studied. A simple model was built up from light equations, tree growth curves and allometric relationships. From this model, we have estimated that radiation available for crops and pasture decreased up to 21% due to the presence of trees in a standard dehesa with 24 mature trees ha⁻¹ and 13% of canopy cover. In addition, we have generated different radiation maps of virtual dehesas differing in tree age, density and arrangement, which could be useful to determine optimal tree planting schemes and consequent pruning and thinning regimes.     

Antioxidant activity of Rhizophora mangle bark

The antioxidant activity of Rhizophora mangle bark aqueous extract and its majoritary component and high molecular weight polyphenols' fraction were studied using deoxyribose assay. The total extract and its fraction showed scavenging activity of hydroxyl radicals and hability to chelate iron ions.     

Triacylglycerol-rich lipoproteins interact with human vascular cells in a lipid-dependent fashion.

Plasma triacylglycerol-rich lipoproteins (TRL) are being considered as a key lipid fraction in the pathogenesis of atherosclerotic cardiovascular disease. Here we compared the influence of two monounsaturated oils [virgin olive oil (VOO) and high-oleic sunflower oil (HOSO)] on the capability of postprandial TRL to interact with two human vascular cell lines [umbilical vein endothelial (HUVEC) and aorta smooth muscle (HASMC) cells]. A fluorescent probe was used for labeling TRL and to determine receptor activity of HUVEC and HASMC. The values for total cell-associated, bound, and internalized TRL were higher in HUVEC, and TRL from VOO was the better ligand recognized but at lower affinity than TRL from HOSO. There was a competitive effect of very low density lipoproteins (VLDL) for the uptake of TRL by cells, which was found to be dependent on the origin/lipid composition of the ligands and cell-type specific. We also conclude that the VLDL receptor (VLDLr) may contribute significantly to the HASMC binding capacity for postprandial TRL mediated by lipoprotein lipase (LPL) or LPL-binding molecules. Our findings are compatible with a selective role of the clustered O-linked sugar domain of the VLDLr in the catabolism of TRL by human vascular cells.     

Chemical restraint of African mole‐rats (Fukomys sp.) with a combination of ketamine and xylazine

ObjectiveTo establish an accurate anaesthetic dose for chemical restraint of African mole-rats using ketamine and xylazine.Study designProspective nonrandomized laboratory study.AnimalsSixteen adult Ansell’s mole-rats (Fukomys anselli) and eight giant mole-rats (F. mechowii).MethodsFukomys anselli of different ages, sexes and reproductive status were systematically anaesthetized starting with an intramuscular injection of ketamine (2.5 mg kg⁻¹) and increasing the doses in steps of 0.5 mg kg⁻¹ until loss of the righting reflex (LRR) was observed. Xylazine was added to a constant dose of ketamine, starting at 0.5 mg kg⁻¹ that was increased by 0.5 mg kg⁻¹ in further trials. Once an effective combination was established and evaluated in F. anselli, it was also tested in F. mechowii. Heart and respiratory rates and rectal temperatures were measured during anaesthesia. anova for repeated measures and Student’s t-test were used to compare means.ResultsChemical restraint was accomplished at a dose of 6 mg kg⁻¹ ketamine combined with 2.5 mg kg⁻¹ xylazine. LRR lasted on average mean 56 ± SD 19 minutes (F. anselli) and 140 ± 41 minutes (F. mechowii). Loss of pedal withdrawal reflex (LPR) lasted for 20 ± 15 minutes (F. anselli) and for 29 ± 2 minutes (F. mechowii), respectively. All animals recovered satisfactorily. Heart and respiratory rates were stable during anaesthesia, but rectal temperature fell significantly in F. mechowii after losing the righting reflex (LRR) from T1 (32.6 ± 0.6 °C) to T3 (30.4 ± 0.9 °C).Conclusions and Clinical relevanceAfrican mole-rats (Bathyergidae) live in closed burrow systems under particular conditions (hypercapnia, hypoxia, stable temperature, humidity, darkness) and show several physiological adaptations. Injectable anaesthetics in the dose rates used in other rodents are not appropriate for use in these subterranean species. Here, a reliable protocol for chemical restraint is provided.     

Analysis of water application costs with a centre pivot system for irrigation of crops in Spain

The aim of this study was to present a methodology to analyse the main factors that influence annual water application costs in centre pivot irrigation systems and to determine the most cost-effective centre pivot design, given the variables of machine length, lateral pipe diameter, sprinkler type (LEPA and fixed and rotating spray plate sprinklers (FSPS and RSPS)), system capacity, application efficiency, and water and energy costs for the irrigation of crops such as maize under conditions in Spain. Annual water application costs were calculated as the sum of the investment (Ca), energy (Ce), water (Cw), and equipment maintenance costs (Cm). Parameters used to assess the influences on pivot design were system capacity S _c = 1.25 L s^?1 ha^?1; application efficiency Ea = 80% for FSPS, Ea = 85% for RSPS, and Ea = 90% for LEPA; water price P _w = 0.06 € m^?3 (0.081 US dollars); energy price En_e = 0.10 € kWh^?1 (0.135 US dollars); net annual crop irrigation water requirement N _n = 7,000 m³ ha^?1 year^?1; and net daily peak crop water requirement N _nmax = 7.63 mm d^?1 for maize. Results indicate that for plots smaller than 30 ha, the recommended pipeline diameter is 127.0 mm (5 in); for 30–40 ha, 168.3 mm (6 5/8 in); for 40–75 ha, 219.1 mm (8 5/8 in); and for 75–100 ha, 254.0 mm (10 in). A multidiameter pipe solution only slightly reduced water application costs in most cases studied. It was also determined that water costs and irrigation efficiency have a major influence on the total annual cost of water application; however, system capacity and energy price did not strongly affect total cost. For this reason, water application uniformity is very important and can be accomplished using a proper nozzle package and regular maintenance. The paper helps farmers determine the most cost-effective centre pivot design and management.     

Financial feasibility of implementing regulated and sustained deficit irrigation in almond orchards

This study aims to assess the long-term economic viability of deficit irrigation (DI) strategies in almond trees (cv. Marta) grown in a semiarid area (southeast Spain). A discounted cash flow analysis (DCFA) was performed to determine the profitability of the different irrigation regimes. Four irrigation treatments were evaluated over the first 6 years of an almond plantation: (1) full irrigation (FI); (2) regulated deficit irrigation (RDI) receiving 40 % ETc during kernel-filling and 100 % ETc during the remainder of the growing season; (3) mild-to-moderate sustained deficit irrigation (SDI_mm), irrigated at 75 % ETc (first half of the experiment) and 60 % ETc (second half of the experiment) over the entire growing season; and (4) moderate-to-severe SDI (SDI_ms), irrigated at 60 % ETc (first half of the experiment) and 30 % ETc (second half of the experiment) over the whole growing season. Irrigation water profit was mainly determined by the annual volume of irrigation water applied (water costs are around 50 % of variable costs). DCFA indicates that RDI and SDI_mm are the most economically feasible treatments, whereas FI and SDI_ms presented a similar degree of profitability over the 6-year period. Simulation outputs derived for the whole useful life of the investment indicate that SDI_mm would be the most suitable irrigation treatment to be adopted by almond farmers in the study area. We conclude that in a context of water scarcity, DI is a financially feasible alternative to FI.     

Identification of Ensifer strains isolated from root nodules of Medicago hispida grown in association with Zea mays in the Quechua region of the Peruvian Andes

Peasants of the Quechua region of the Peruvian Andes use chacras to grow maize (Zea mays) in innate association with bur clover (Medicago hispida). From a total of 25 bacterial strains isolated from root nodules of bur clover grown in soils from chacras in Allpas (Acobamba, Peru) 7 clustered into 6 Repetitive extragenic palindromic-polymerase chain reactions (REP–PCR) groups. The nearly complete 16S rRNA gene sequence from the representative strains AP1, AP15, AP28, AP29, AP37, and AP70 showed they were closely related to members of the genus Ensifer of the Alphaproteobacteria. Sequencing of the housekeeping atpD, glnII, and recA and the symbiotic nodC genes from each of the six strains revealed they all were similar to those of strains included in Ensifer medicae. The remaining 18 strains were distributed into 8 REP–PCR groups and analyses of the 16S rRNA gene sequences showed that the isolates belong to several phylogenetic groups, being closely related to species of genera Kaistia, Pseudomonas, Achromobacter, Stenotrophomonas, Xanthomonas, Sphyngopyxis, Duganella, and Rheinheimera.     

Comparison of iron bioavailability from 15 rice genotypes: studies using an in vitro digestion/caco-2 cell culture model

An in vitro digestion/Caco-2 model was used to compare iron bioavailability from 15 selected Fe-dense and normal genotypes of unpolished rice from the International Rice Research Institute. Iron uptake was determined using Caco-2 cell ferritin formation in response to exposure to a digest of the cooked rice. Iron bioavailabilities from all rice genotypes were ranked as a percent relative to a control variety (Nishiki). Iron concentration in the rice samples ranged from 14 to 39 microg/g. No correlation was observed between Fe uptake and grain-Fe concentration. Furthermore, phytic acid levels were not correlated with Fe bioavailability. Genotypes with low Fe bioavailability (Tong Lan Mo Mi, Zuchein, Heibao, and Xua Bue Nuo) were noticeably more brown to purple in color. The results suggest that certain unknown compounds related to rice grain color may be a major factor limiting Fe bioavailability from unpolished rice.