Long‐term Effects of Pine Plantations on Soil Quality in Southern Spain

This work evaluated how pine plantations established on old fields and degraded lands influence soil properties in comparison with adjacent unplanted areas that undergo into secondary succession, and native forests, analysing the effects of abiotic variables and stand characteristics in the afforestation process. Thirty‐two paired sites (pine plantations versus unplanted areas) and 10 native forests were selected in the SE Spain. In total, 74 soil profiles were studied, and 222 composite soil samples were collected at three different depths. Soil organic carbon, cation exchange capacity, and C : N ratio showed significantly greater values in pine plantations in relation to the unplanted areas (0–5 cm), and the mean values of soil organic carbon, nitrogen (N), C : N ratio, and cation exchange capacity in these pine plantations were similar to those found under native forests. Only K⁺ concentrations were clearly higher in the native forests than in the other land uses for all depths analysed. Pine plantations in the drier and warmer areas showed lower soil quality in relation to the paired unplanted areas, as well as the younger and denser ones; it may be because under these situations, more time is needed to produce an improvement. In fact, the paired net variations increased with the stand age and/or tree size. In conclusion, pine plantations were in general more efficient in improving parameters related to soil quality, especially in locations with high soil water retention capacity, which in our study area were found at higher and cooler elevations. Copyright © 2016 John Wiley & Sons, Ltd.     

Agglomeration of Services in American Metropolitan Areas

The growth of many service industries among American metropolitan areas stem from an eclectic set of forces. These include market penetration effects of increasing importance of services throughout the economy, agglomeration effects in immature and deregulated industries, and institutional and infrastructure constraints. These diverse forces are interpreted as urbanization and localization economies. A cycle of centralization of 27 fast growing service industries is documented for MS As in the period 1977-84. The two agglomeration effects are tested directly, using a power function model that relates employment and establishment growth to MSA size and initial level of employment in a local industry. Localization economies rather than the general advantages of metropolitan size best explain the growth patterns. This result implies that service industrial complexes are rapidly emerging in American metropolitan areas.     

Field efficacy of imidacloprid and Steinernema carpocapsae in a chitosan formulation against the red palm weevil Rhynchophorus ferrugineus (Coleoptera: Curculionidae) in Phoenix canariensis

BACKGROUND: The invasive red palm weevil, Rhynchophorus ferrugineus (Olivier), has become the major pest of palms in the Mediterranean Basin. Chemical control against this species is difficult because of its cryptic habits and is mainly based on the repeated application of large quantities of synthetic insecticides. The aim of this work has been to evaluate in the field the efficacy of imidacloprid (Confidor^® 240 OD) and Steinernema carpocapsae Weiser with chitosan (Biorend R^® Palmeras) as soil and stipe treatments respectively, alone or in combination, against this pest. RESULTS: All treatments significantly reduced the mean number of immature stages of R. ferrugineus per palm. However, there were no significant differences among the different treatments considered. Efficacies ranged from 83.8 to 99.7% for the mean number of immature stages found in the palms and resulted in a significant increase in palm survival compared with the untreated control (75.0–90.0% versus 16.5% respectively). CONCLUSION: Both imidacloprid and S. carpocapsae in a chitosan formulation proved highly effective against R. ferrugineus in the field, and their efficacies did not significantly change when used in combination. Copyright © 2009 Society of Chemical Industry     

High Resolution Melt (HRM) analysis is an efficient tool to genotype EMS mutants in complex crop genomes

Background

Targeted Induced Loci Lesions IN Genomes (TILLING) is increasingly being used to generate and identify mutations in target genes of crop genomes. TILLING populations of several thousand lines have been generated in a number of crop species including Brassica rapa. Genetic analysis of mutants identified by TILLING requires an efficient, high-throughput and cost effective genotyping method to track the mutations through numerous generations. High resolution melt (HRM) analysis has been used in a number of systems to identify single nucleotide polymorphisms (SNPs) and insertion/deletions (IN/DELs) enabling the genotyping of different types of samples. HRM is ideally suited to high-throughput genotyping of multiple TILLING mutants in complex crop genomes. To date it has been used to identify mutants and genotype single mutations. The aim of this study was to determine if HRM can facilitate downstream analysis of multiple mutant lines identified by TILLING in order to characterise allelic series of EMS induced mutations in target genes across a number of generations in complex crop genomes.

Results

We demonstrate that HRM can be used to genotype allelic series of mutations in two genes, BraA.CAX1a and BraA.MET1.a in Brassica rapa. We analysed 12 mutations in BraA.CAX1.a and five in BraA.MET1.a over two generations including a back-cross to the wild-type. Using a commercially available HRM kit and the Lightscanner? system we were able to detect mutations in heterozygous and homozygous states for both genes.

Conclusions

Using HRM genotyping on TILLING derived mutants, it is possible to generate an allelic series of mutations within multiple target genes rapidly. Lines suitable for phenotypic analysis can be isolated approximately 8-9 months (3 generations) from receiving M₃ seed of Brassica rapa from the RevGenUK TILLING service.     

Optimisation of the frequently sampled intravenous glucose tolerance test to reduce urinary glucose spilling in horses

Reasons for performing study: The frequently sampled i.v. glucose tolerance test (FSIGTT) is used to evaluate glucose and insulin dynamics in horses, but it has not been determined whether urinary glucose spilling (UGS) affects results. Hypothesis: UGS occurs in horses during the FSIGTT and this problem can be minimised by adjusting the dextrose and insulin dosages used. Methods: Six mature mares were included in this study. In the first phase, 6 FSIGTT procedures were performed in each horse to evaluate 6 different dextrose dosages. Six different insulin dosages were evaluated during the second phase of the study after administration of 300 mg/kg bwt dextrose. Area under the glucose (AUCg) and insulin (AUCi) curves were calculated and minimal model analyses performed. UGS was measured in the third and fourth phases of the study during the combined glucose insulin test and established FSIGTT. A new FSIGTT was developed and evaluated. Results: Positive linear effects of dextrose dosage on AUCg, AUCi and acute insulin response to glucose were detected, with AUCg reaching a plateau at doses 200 mg/kg bwt. Insulin dosage had an inverse linear effect on AUCg, but other values remained unaffected. UGS occurred during all 3 tests and was the highest for the established FSIGTT and the lowest for the new FSIGTT. The type of FSIGTT performed did not affect minimal model results. Conclusions: Results indicate that the dextrose dosage of 300 mg/kg bwt used in the established FSIGTT is too high. UGS can be reduced by lowering the dextrose dosage to 100 mg/kg bwt. Potential relevance: A new FSIGTT involving the administration of 100 mg/kg bwt dextrose followed by 20 mu/kg bwt insulin 20 min later is recommended for use in horses because this test provides adequate data for minimal model analysis while minimising UGS.     

Effects of endotoxaemia and carbohydrate overload on glucose and insulin dynamics and the development of laminitis in horses

Reasons for performing study: Insulin resistance (IR) is a risk factor for pasture‐associated laminitis in equids and alimentary carbohydrate overload may trigger laminitis. Whether glucose metabolism responses to carbohydrate overload are more pronounced in insulin‐resistant horses requires further study. Hypothesis: Horses pretreated with endotoxin to alter insulin sensitivity differ significantly in their glucose and insulin responses to carbohydrate overload. Methods: Horses (n = 24) were divided into 3 groups. A lipopolysaccharide (LPS; n = 8) group that received endotoxin as an 8 h 7.5 ng/kg bwt/h i.v. continuous rate infusion, an oligofructose (OF; n = 8) group that received an infusion of saline followed by 5 g/kg bwt OF via nasogastric intubation, and a LPS/OF (n = 8) group that received LPS followed 16 h later by OF. Glucose and insulin dynamics were evaluated at ‐24 h and 48 h using the frequently sampled i.v. glucose tolerance test and minimal model analysis. Physical examinations and haematology were performed and the severity of laminitis assessed. Results: Horses receiving LPS developed leucopenia and both LPS and OF induced clinical signs consistent with systemic inflammation. Insulin sensitivity significantly decreased (P<0.001) over time, but responses did not differ significantly among groups. Time (P<0.001) and treatment × time (P = 0.038) effects were detected for the acute insulin response to glucose, with mean values significantly increasing in LPS and LPS/OF groups, but not the OF group. Five horses in the LPS/OF group developed clinical laminitis compared with 0 and 2 horses in the LPS and OF groups, respectively. Conclusions: Endotoxaemia and carbohydrate overload reduce insulin sensitivity in horses. Endotoxin pretreatment does not affect the alterations in glucose metabolism induced by carbohydrate overload. Potential relevance: Insulin sensitivity decreases after carbohydrate overload in horses, which may be relevant to the development of pasture‐associated laminitis.     

Phenotypic and genetic characterisation of bacteriocin-producing strains of Staphylococcus aureus involved in bovine mastitis

Fifty strains of Staphylococcus spp. isolated from bovine mastitis cases in several herds from different Argentinian provinces were screened for antimicrobial substances. Twelve strains exhibited a high antagonistic activity against the indicator strain (Corynebacterium fimi) and were chosen for further characterisation. The antimicrobial substances were sensitive to proteolytic enzymes suggesting that they might be bacteriocins (Bac). These strains were identified as S. aureus by the amplification of the femA gene. Plasmid profile analysis of these strains revealed the presence of at least one plasmid. Eleven strains carried a plasmid with a size similar to that of pRJ6 (8.0kb), which encodes aureocin A70, a bacteriocin produced by the Brazilian S. aureus strain A70 isolated from commercial milk. The other strain harboured a much larger plasmid. PCR experiments, using specific primers for amplification of the bacteriocin operon found in pRJ6, showed that all strains had the expected 525bp amplicon, suggesting that the bacteriocin produced may be related to aureocin A70. The genomic DNA of all Bac(+) strains was then analysed by pulsed-field gel electrophoresis (PFGE) in order to investigate clonal relationships amongst strains. Based on the results of PFGE experiments, 10 out of the 12 Bac(+) strains belonged to the same clone. The remaining two strains are possibly related to the prevalent clone. The aureocin A70 producer-strain belonged to a distinct clone.     

Effects of nauplial density, product concentration and product dosage on the survival of the nauplii and EFA incorporation during Artemia enrichment with liposomes

In order to determine an optimal enrichment protocol with krill phospholipid liposomes, three different experiments were carried out to evaluate the effects of nauplial density, the concentration of liposome, and the number of doses delivered to the nauplii on the survival and the essential fatty acid (EFA) bioencapsulation in Artemia nauplii. No survival differences were found between the different liposome treatments and the control nauplii enriched with a commercial emulsion. This result confirms that previously described mortalities during Artemia enrichment with liposomes can be minimized and controlled. On the other hand, the EFA incorporation obtained from the three experiments indicates that maximal bioencapsulation is achieved when incubations are carried out under nauplial densities of 300 nauplii ml^− 1, where liposomes are dispensed in a single dose at the beginning of the incubation yielding a concentration of 0.5 g l^− 1. These findings complete those obtained in two preliminary studies, and propose a well defined enrichment protocol with krill liposomes as an alternative complementary method to improve the nutritional value of the Artemia nauplii used as food for marine fish larvae.     

Agronomic evaluation of seedlings from crosses between the main Spanish olive cultivar ‘Picual’ and two wild olive trees

Summary

Until recently, olive breeding programmes have been based exclusively on cultivated olive germplasm (Olea europaea subsp. europaea var. europaea), in contrast to breeding in other fruit crops where the use of wild relatives has been widely reported. In this study, ten agronomic traits were evaluated in two progenies derived from controlled crosses between the Spanish olive cultivar ‘Picual’ (female) and two wild (O. europaea subsp. europaea var. sylvestris) genotypes (males). The results of this evaluation were compared with the progenies of crosses between ‘Picual’ (female) and the three cultivars, ‘Sikitita’, ‘Meski’, and ‘Zaity’ (male). The two ‘Picual’ × wild genotype progenies had the highest mean values for vigour traits (i.e., tree height and trunk diameter). Progenies from both ‘Picual’ × wild genotype crossess also showed the highest percentages of trees (53.8% and 37.5%) with a short juvenile period, compared to the progenies from crosses between ‘Picual’ and each of the three cultivars ‘Sikitita’, ‘Meski’, and ‘Zaity’ (0%, 5%, and 3.6%, respectively). Significant differences were also observed between progenies in fruit traits as well as in oil contents and fruit weights. Progenies from both crosses with wild olive showed lower values for the fruit traits evaluated than the cultivated olive progenies. However, significant improvements were achieved compared to fruit traits in the wild parents. The implications of these results for the future use of wild germplasm in olive breeding programmes are discussed.