Simulation of atrazine persistence in Spanish soils

The persistence of atrazine was monitored in three fields at different sites in Spain during two consecutive years (1990 and 1991). Laboratory assays for determining the influence of temperature and soil moisture content on the rate of herbicide degradation were carried out on soil samples from the same fields. The degradation constants derived from these assays, together with weather records for the period of the field experiments, were used in a computer program which simulated herbicide persistence in the field. Some adjustments were made to adapt the model to Spanish conditions. The model predicted with reasonable accuracy the persistence of the herbicide in two soils, although there was a tendency to overestimate the residues at early dates. Discrepancies between predicted and measured residues were greater in the third soil, due to rapid initial losses that were not predicted by the program. In this case, the agreement was improved if the program was run taking time zero to be one month after herbicide application. Possible reasons for these discrepancies are discussed.     

Phospholipase A2 and postharvest peel pitting in citrus fruit

The role of phospholipase A₂ (PLA₂) activity in development of postharvest peel pitting in mature ‘Fallglo’ tangerines [Bower citrus hybrid (Citrus reticulata Blanco × C. reticulata Blanco × C. paradisi Macf.) × Temple (C. reticulata Blanco × Citrus sinensis L.)] and ‘Navel’ oranges (Citrus sinensis L. Osbeck) was investigated. Changes in RH from 30% to 90% followed by fruit waxing increased electrolyte leakage and PLA₂ activity in flavedo, and induced pitting. Treatment with an aqueous dip of aristolochic acid (AT), a specific inhibitor of secretory phospholipase A₂ (sPLA₂) activity, immediately before transfer from 30% to 90% RH storage, markedly reduced peel pitting symptoms. Five genes encoding various phospholipase As isolated from citrus (three patatin-like and two sPLA₂-like sequences) differentially accumulated in healthy areas, areas with developing lesions and necrotic lesions of disordered fruit. Other PLA₂, phospholipase C, and phospholipase D inhibitors also reduced peel pitting; however, PLA₂ inhibitors were the most effective in preventing the disorder. In addition, phospholipase inhibitors promoted fruit decay, suggesting that innate resistance is impacted by phospholipase action. Together, the results provide evidence for involvement of phospholipase activity in development of postharvest peel pitting symptoms in citrus fruit.     

DEMAND FOR FISH IN THE PHILIPPINES: A DISAGGREGATED ANALYSIS

ABSTRACT

This paper sought to establish the fish consumption pattern of Filipino households and estimate the price and income elasticities of fish demand by species, as well as by income groups, i.e., low, middle, and high income. The study used the countrywide Family Income and Expenditure Survey (FIES) for year 2000 of the National Statistics Office, which includes over 39,000 households. A three-stage budgeting framework was used in the analysis, which estimated food and fish expenditure functions in the first and second stages, respectively. In the third stage, a system of demand equations for fish by species was estimated using a quadratic almost ideal demand system (QUAIDS) model. Parameter estimates of the model were corrected through the Heckman procedure to remove the possible bias brought about by zero consumption of certain fish species resulting from nonpreference or infrequent purchases. Results showed that estimated price and income elasticities of demand varied substantially across fish type and across income groups. All 11 fish types included in the study were found to have positive income elasticity for all income levels. Hence, fish in general can be considered normal goods, including processed fish. However, the high-priced fish types generated elasticity values greater than one, which rendered them as luxury food fish. Own-price elasticity, on the other hand, was found to be elastic in most species with values increasing as consumers climbed up the income ladder. This observation, however, was not true in the case of milkfish and tilapia (two most popular species in the country) where price responsiveness of demand was found to be higher among the lower-income groups.     

Bread Supplemented with Amaranth (<Emphasis Type="Italic">Amaranthus cruentus</Emphasis>): Effect of Phytates on <Emphasis Type="Italic">In Vitro</Emphasis> Iron Absorption

The objective of the present study was to evaluate the effect of the bread supplemented with whole amaranth flour (0, 20 and 40%) on iron bioavailability using Caco-2 cells model. The phytate and lower myo-inositol phosphates content in in vitro bread digests were measured by high pressure liquid chromatography. The breads made with amaranth showed significant increase of soluble phytates levels (up to 1.20 μmol/g in dry matter for the 40% of substitution) in comparison with controls, which have not detectable values. A negative correlation among phytate and Fe availability was found when increased levels of amaranth. Ferritin concentration was found 2.7- and 2.0-fold higher (P < 0.05) in cultures exposed to 20% and 40% of amaranth formulated bread samples, respectively, compared to control bread. The soluble phytate/Fe molar ratio explained the whole amaranth flour-mediated inhibitory effect associated to the limitation of available Fe; however, the use up to 20% of amaranth in bread formulation appears as a promising strategy to improve the nutritional value of bread, as indicated by the ferritin concentrations quantified in cell cultures. Higher proportion of amaranth flour increased Fe concentration although there was not detected any increase in Fe uptake.     

Expression of oestrogen and progesterone receptors in canine sebaceous gland tumours

Sebaceous gland oestrogen α (ERα) and progesterone (PR) receptor expression was examined immunohistochemically in 26 and 32 dogs respectively with sebaceous gland hyperplasia/adenomas, epitheliomas and carcinomas, and in the glands of 10 healthy controls. The mean percentage of ERα positive nuclei in control sebaceous glands was 21.31% compared with 11.5% in hyperplasia/adenoma‐type lesions, although these values were not statistically different. In sebaceous gland epitheliomas and carcinomas, positive basal cells represented 7.86% and 3.53% of neoplastic cells respectively and these mean percentages were significantly lower in epitheliomas (P < 0.024) and carcinomas (P < 0.015) than in controls. The mean percentage of PR‐positive nuclei in control sebaceous glands was 23.96%, similar to the 22.07% found in hyperplasia/adenoma‐type lesions. In sebaceous gland epitheliomas and carcinomas, positive cells were scarce and represented 13.5% and 4.06% of neoplastic cells respectively. Differences in the percentage of positive cells between normal and pathological glands reached statistical significance for carcinomas (P < 0.043). In the control group there was greater PR (P < 0.001) and ERα expression (P < 0.014) in sebaceous glands in female dogs. The PR and ERα immunoreactivity in each category of neoplastic lesions could not be analysed because sample size was too small but when all the sebaceous gland tumours were grouped and analysed, no sex difference was found. The results suggest that oestrogen and progesterone receptor expression is reduced in some canine sebaceous gland tumours. These changes may represent a contributing factor for tumour growth or simply be a consequence of tumour progression.     

Validation of an immunoturbidimetric method for determination of porcine serum C-reactive protein

Measurement of porcine C-reactive protein (CRP) in serum is an important tool for monitoring health and welfare in pigs. In this study, an immunoturbidimetric method from Olympus System Reagent (OSR 6147) used to measure human CRP in serum that employ a human traceable calibrator has been evaluated in porcine serum samples. Intra- and inter-assay imprecision were lower than that obtained with the porcine-specific commercially available ELISA. The expected difference in serum CRP between healthy and non-healthy pigs was detected. CRP values measured by the immunoturbidimetric method showed a good correlation with those obtained by ELISA, although differences in absolute CRP values were observed. When an in-house porcine standard was used a better agreement was obtained. In conclusion, the immunoturbidimetric method of Olympus can be used with porcine samples. The easier use of this method should facilitate the implementation of CRP serum determination for diagnostic and prognostic purposes in swine medicine. The results emphasize the need to establish species-specific standard and methods to decrease inter-laboratory discrepancies.     

Recovery of Serratia marcescens in Hemolymph of Macrobrachium rosenbergii from Experimentally Seeded Water

Seratia marcescens was used as an indicator to determine if different concentrations of bacteria in water relate to concentrations in the hemolymph of Macrobrachium rosenbergii . Prawns were exposed to high (10⁵ to 10⁶ cells/ml), low (10³ to 10⁴ cells/ml) and control (no S. marcescens ) treatments with S. marcescens inoculated in aquaria water. S. marcescens ranged from 10 to 9.9 ± 10³ cells/ml from the high concentration group; a single isolate and zero S. marcescens were recovered from the low and control groups, respectively.     

Determination of the effective dose of an experimental fasciolicide in naturally and experimentally infected cattle

The aim of the present study was to determine the effective dose of an experimental fasciolicide called compound alpha or 5-chloro-2-methylthio-6-(1-napthyloxy)1H-benzimidazole in experimentally and naturally infected cattle. In the first experiment, 24 fluke-free heifers were each infected with 800 metacercariae of Fasciola hepatica and re-infected on day 45 with other 600 cysts per animal. On day 75, when the animals had 4- and 10-week-old flukes respectively, they were divided into four groups (G) of six animals each according to fluke egg counts. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. G4 remained as an untreated control. Twenty days after treatment, the animals were sacrificed for the recovery of flukes. Efficacy was assessed as a percentage of egg or fluke reduction relative to the untreated control. In the second experiment (naturally infected cattle), 24-year-old steers positive to F. hepatica eggs were blocked into four groups of five animals each. Groups 1-3 received compound alpha at 10, 12 and 14 mg/kg/p.o., respectively. Group 4 served as a non-treated control. All procedures to determine efficacy were carried out as mentioned in the first experiment. The results in the first study showed a percentage on egg reduction of 97.3, 100 and 100 and overall fluke reduction of 94.3, 100 and 100 for Groups 1-3, respectively. In the second study, the percentage of egg reduction was of 87.5, 99.1 and 100 and overall efficacy regarding fluke reduction was of 84.2, 99.6, and 100 for Groups 1-3, respectively. It is concluded that the effective dose selected for compound alpha was of 12 mg/kg/p.o. in cattle having an induced or natural F. hepatica infection.     

The effect of target extent on the location of optimal protected areas networks in Canada

Various jurisdictions in Canada are currently undertaking, or have recently completed, planning exercises as part of implementation and expansion of representative reserve networks (networks of provincial parks, national parks, ecological reserves, etc.). These exercises have resulted in recommendations to governments about which areas of land should be set aside as protected areas, and different levels of government have been involved in the process of land acquisition. In some cases, planning exercises have included implementation of new protected areas to complement existing reserve networks. Many of these exercises have applied principles such as complementarity, using heuristic algorithms that are well-described in the literature. These planning exercises may be conducted within politically or ecologically bounded target regions of varying extents. Here, I develop candidate locations for representative reserve areas for disturbance-sensitive mammals across Canada. I use ecologically bounded regions (within the national boundaries of Canada) at three different levels of spatial hierarchy: mammal provinces, ecozones, and ecoregions. I show that the extent of the target region has an effect on the minimum number of protected areas required to achieve representation; a larger region requires fewer protected areas than the sum of the protected areas required to represent its component regions at a lower level of spatial hierarchy. The results illustrate that selection of sites for inclusion in a reserve network is highly scale-dependent, and different spatial extents in the target regions may introduce inefficiencies or redundancies in selecting representative protected areas.