Zaharah, A.R.; Sharifuddin, H.A.H.; Anular, R.; Bah, A.R.; Mwange, K.Nk.; Kathuli, P.; Juma, P.
Nitrogen fixation by Gliricidia sepium subjected to three pruning regimes (one, two or four cuts per year) was measured using the 15 N-dilution technique with Cassia siamea as the reference species. Over a 4-year period, estimates of the fraction of N derived from fixation, generally 2 fixer. Gliricidia sepium leaves were placed in litter-bags, buried in an ultisol and sampled at intervals over 70 days. The half-life for dry matter was 17 days, and about 60% of the N was lost within 10 days; K and Ca were the most rapidly released nutrients, with half-lives of only 1 and 3 days, respectively. The N contributions from G. sepium leaves and roots to alley-cropped sweet corn were quantified by the 15 N-dilution technique over three growing seasons. The application of leaves with roots resulted in increased N uptake and dry matter yield in corn. Below-ground competition between hedgerow and corn, assessed using 32 P with the third crop, occurred under conditions of low nutrient-availability. The data imply that there is no advantage of the cut-and-carry system over permanent hedgerows, provided that prunings are applied at the time of nutrient demand in the crop. (author)
Entwistle, G; ap Rees, T A
The aim of this work was to discover whether fructose-1,6-bisphosphatase (FBPase) is present in higher-plant cells that synthesize storage starch. The following were examined: suspension cultures of soybean (Glycine max), tubers of potato (Solanum tuberosum), florets of cauliflower (Brassica oleracea), developing endosperm of maize and of sweet corn (Zea mays), roots of pea (Pisum sativum), and the developing embryos of round and wrinkled varieties of pea. Unfractionated extracts of each tissue readily converted fructose 1,6-bisphosphate to fructose 6-phosphate in assays for both plastidic and cytosolic FBPase. These conversions were not inhibited by 20 microM-fructose 2,6-bisphosphate. Except in extracts of pea embryos and sweet-corn endosperm, treatment with affinity-purified antibodies to pyrophosphate: fructose-6-phosphate 1-phosphotransferase reduced the above fructose 6-phosphate production to the rate found with boiled extracts. The antibody-resistant activity from sweet corn was slight. In immunoblot analyses, antibody to plastidic FBPase did not react positively with any protein in extracts of soybean cells, potato tuber, cauliflower florets, maize endosperm and pea roots. Positive reactions were found for extracts of embryos of both round and wrinkled varieties of peas and endosperm of sweet corn. For pea embryos, but not for sweet-corn endosperm, the Mr of the recognized protein corresponded to that of plastidic FBPase. It is argued that soybean cells, potato tuber, cauliflower florets, maize (var. White Horse Tooth) endosperm and pea roots lack significant activity of plastidic FBPase, but that this enzyme is present in developing embryos of pea. The data for sweet corn (var. Golden Bantam) are not decisive. It is also argued that, where FBPase is absent, carbon for starch synthesis does not enter the amyloplast as triose phosphate. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:2173563
Guery, M J; Douillard, C; Marcelli-Tourvieille, S; Dobbelaere, D; Wemeau, J L; Vantyghem, M C
We present the case of a 17-year-old male who was diagnosed at birth with hereditary fructose intolerance (HFI). The patient complained of morning-time asthenia and post-prandial drowsiness despite a correct sleep pattern. The physical examination and biological check-up only showed severe vitamin C deficiency (supplementation in vitamin C was advised, with an increase in vegetable intake, principally avoiding carrots, onions, leaks and tinned sweet-corn. This case offers the opportunity for a review of this rare disease. Two kinds of fructose metabolism disorders (both autosomal recessive) are recognized: 1) essential fructosuria caused by a deficiency of fructokinase, which has no clinical consequence and requires no dietary treatment; 2) HFI, linked to three main mutations identified in aldolase B gene that may be confirmed by fructose breath test, intravenous fructose tolerance test, and genetic testing. In HFI, fructose ingestion generally induces gastro-intestinal (nausea and vomiting, abdominal pain, meteorism) and hypoglycemic symptoms. Fasting is well tolerated. If the condition remains undiagnosed, it leads to liver disease with hepatomegaly, proximal tubular dysfunction, and slow growth and weight gain. In conclusion, endocrinologists should be aware of this rare metabolic disease in order to provide careful follow-up, particularly important when the patient reaches adulthood. Moreover, hypoglycemia induced by fructose absorption, unexplained liver disease, irritable bowel syndrome or familial gout in an adult is suggestive of the diagnosis.
García-Prieto, Amalia; Lunar, Loreto; Rubio, Soledad; Pérez-Bendito, Dolores
Decanoic acid reverse micelle-based coacervates were proposed for the extraction of bisphenol A (BPA) from canned vegetables and fruits prior to its determination by liquid chromatography and fluorescence detection at lambda(exc) = 276 nm and lambda(em) = 306 nm. The procedure involved the extraction of minute quantities (300-700 mg) of homogenized food sample with an aqueous solution containing 10% of THF and 0.5% of decanoic acid, conditions under which the coacervate (around 340 microL) formed in situ and instantaneously. The overall sample treatment, which included extraction and centrifugation, took about 25-30 min, and several samples could be simultaneously treated using conventional lab equipment. No clean-up or solvent evaporation were required. Extraction efficiencies mainly depended on the decanoic acid and THF concentration in the aqueous solution and were not affected by the pH or the temperature in the ranges studied (1-4 and 20-60 degrees C, respectively). Recoveries in samples ranged between about 81 and 96%. The precision of the method, expressed as relative standard deviation, was about 3% and the quantitation limit was around 9 ng g(-1), which was far below the current specific migration limit (SML) set for BPA by the EU Commission (600 ng g(-1)). The method was successfully applied to the determination of BPA in the solid content of canned fruit salad, peaches in syrup, mango slices, red peppers, sweetcorn, green beans and peas. BPA was present at concentrations in the range from 7.8 to 24.4 ng g(-1) in canned fruits and from 55 to 103 ng g(-1) in canned vegetables.
Davies, Anna C; Nicol, Christine J; Persson, Mia E; Radford, Andrew N
In humans, more difficult decisions result in behavioural and physiological changes suggestive of increased arousal, but little is known about the effect of decision difficulty in other species. A difficult decision can have a number of characteristics; we aimed to monitor how finely balanced decisions, compared to unbalanced ones, affected the behaviour and physiology of chickens. An unbalanced decision was one in which the two options were of unequal net value (1 (Q1) vs. 6 (Q6) pieces of sweetcorn with no cost associated with either option); a finely balanced decision was one in which the options were of equal net value (i.e. hens were "indifferent" to both options). To identify hens' indifference, a titration procedure was used in which a cost (electromagnetic weight on an access door) was applied to the Q6 option, to find the individual point at which hens chose this option approximately equally to Q1 via a non-weighted door. We then compared behavioural and physiological indicators of arousal (head movements, latency to choose, heart-rate variability and surface body temperature) when chickens made decisions that were unbalanced or finely balanced. Significant physiological (heart-rate variability) and behavioural (latency to pen) differences were found between the finely balanced and balanced conditions, but these were likely to be artefacts of the greater time and effort required to push through the weighted doors. No other behavioural and physiological measures were significantly different between the decision categories. We suggest that more information is needed on when best to monitor likely changes in arousal during decision-making and that future studies should consider decisions defined as difficult in other ways.
Anna C Davies
Full Text Available In humans, more difficult decisions result in behavioural and physiological changes suggestive of increased arousal, but little is known about the effect of decision difficulty in other species. A difficult decision can have a number of characteristics; we aimed to monitor how finely balanced decisions, compared to unbalanced ones, affected the behaviour and physiology of chickens. An unbalanced decision was one in which the two options were of unequal net value (1 (Q1 vs. 6 (Q6 pieces of sweetcorn with no cost associated with either option; a finely balanced decision was one in which the options were of equal net value (i.e. hens were "indifferent" to both options. To identify hens' indifference, a titration procedure was used in which a cost (electromagnetic weight on an access door was applied to the Q6 option, to find the individual point at which hens chose this option approximately equally to Q1 via a non-weighted door. We then compared behavioural and physiological indicators of arousal (head movements, latency to choose, heart-rate variability and surface body temperature when chickens made decisions that were unbalanced or finely balanced. Significant physiological (heart-rate variability and behavioural (latency to pen differences were found between the finely balanced and balanced conditions, but these were likely to be artefacts of the greater time and effort required to push through the weighted doors. No other behavioural and physiological measures were significantly different between the decision categories. We suggest that more information is needed on when best to monitor likely changes in arousal during decision-making and that future studies should consider decisions defined as difficult in other ways.
Maria Alice de Medeiros
Full Text Available Os predadores, em geral, apresentam hábitos generalistas e por isso podem ser usados em programas de controle biológico, em diferentes agroecossistemas. A sobrevivência dos predadores é afetada por diversos fatores, como, por exemplo, a presença de parasitóides. Este trabalho foi conduzido com os objetivos de identificar os parasitóides de crisopídeos, especialmente os parasitóides de ovos, e determinar o nível de parasitismo natural. As amostragens foram feitas na Embrapa Hortaliças, em campos de milho-doce, de setembro/1997 a fevereiro/1998. Os ovos de crisopídeos foram coletados semanalmente, sendo individualizados em cápsulas de gelatina até a emergência da larva e/ou do parasitóide. Foram coletados 800 ovos de crisopídeos, sendo que em 71% dos ovos, as larvas sobreviveram; 9% dos ovos foram considerados inviáveis e 20% foram parasitados por seis espécies de microhimenópteros. Destes, 57% foram parasitados por Telenomus sp. (Scelionidae, 32% por Trichogramma pretiosum (Trichogrammatidae, 6% por Oencyrtus chrysopae Crawford (Encyrtidae e 5% por Aprostocetus sp. (Eulophidae.Most predators, in general, have generalist habits and can be used as biological control agents in several crops. Predator survival is affected by several factors, such as occurrence of parasitoids. The main purpose of this research was to identify the parasitoids of chrysopids, especially egg parasitoids and their level of parasitism. The samples were taken in a sweet-corn field at Embrapa Hortaliças from September/1997 to February/1998. The chrysopids eggs were collected weekly and then individualized in gelatine capsules until larval or parasitoid emergency. A total of 800 eggs were collected. The predator emerged from 71% of the eggs, 9% were inviable eggs and the other 20% were parasitized by six species of microhymenopterans. Among these, 57% were parasitized by Telenomus sp. (Scelionidae, 32% were parasitized by Trichogramma pretiosum
Rollo, Megan E; Bucher, Tamara; Smith, Shamus P; Collins, Clare E
Accurate estimation of food portion size is a difficult task. Visual cues are important mediators of portion size and therefore technology-based aids may assist consumers when serving and estimating food portions. The current study evaluated the usability and impact on estimation error of standard food servings of a novel augmented reality food serving aid, ServAR. Participants were randomised into one of three groups: 1) no information/aid (control); 2) verbal information on standard serving sizes; or 3) ServAR, an aid which overlayed virtual food servings over a plate using a tablet computer. Participants were asked to estimate the standard serving sizes of nine foods (broccoli, carrots, cauliflower, green beans, kidney beans, potato, pasta, rice, and sweetcorn) using validated food replicas. Wilcoxon signed-rank tests compared median served weights of each food to reference standard serving size weights. Percentage error was used to compare the estimation of serving size accuracy between the three groups. All participants also performed a usability test using the ServAR tool to guide the serving of one randomly selected food. Ninety adults (78.9% female; a mean (95%CI) age 25.8 (24.9-26.7) years; BMI 24.2 (23.2-25.2) kg/m 2 ) completed the study. The median servings were significantly different to the reference portions for five foods in the ServAR group, compared to eight foods in the information only group and seven foods for the control group. The cumulative proportion of total estimations per group within ±10%, ±25% and ±50% of the reference portion was greater for those using ServAR (30.7, 65.2 and 90.7%; respectively), compared to the information only group (19.6, 47.4 and 77.4%) and control group (10.0, 33.7 and 68.9%). Participants generally found the ServAR tool easy to use and agreed that it showed potential to support optimal portion size selection. However, some refinements to the ServAR tool are required to improve the user experience. Use of the