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71.
Sanchez CA Krieger RI Khandaker N Moore RC Holts KC Neidel LL 《Journal of agricultural and food chemistry》2005,53(13):5479-5486
The Colorado River is contaminated with perchlorate concentrations of 1.5-8 microg/L, an anion linked to thyroid dysfunction. Over 90% of the lettuce (Lactuca sativa L.) consumed during the winter months in the United States is produced in the Lower Colorado River region. Studies were conducted in this region to survey the potential for lettuce perchlorate accumulation and estimate potential human exposure to perchlorate from lettuce. Total uptake of perchlorate in the above-ground plant of iceberg lettuce was approximately 5 g/ha. Exposure estimates ranged from 0.45 to 1.8 microg/day depending on lettuce types and trimming. For all lettuce types, hypothetical exposures were less than 4% of the reference dose recommended by the National Academy of Sciences. Results show the relative iodide uptake inhibition potential because of lettuce nitrate was 2 orders of magnitude greater than that associated with the corresponding trace levels of perchlorate. These data support the conclusion that potential perchlorate exposures from lettuce irrigated with Colorado River water are negligible relative to acute or long-term harmful amounts. 相似文献
72.
Jose A Morales Ligbel Sanchez Harvi Velasquez Beatriz De Borrego Marlene De Nava Denis Portillo Yulixis Cano Angel Morillo Ana Albornoz Elsa Socorro 《Water, air, and soil pollution》2001,130(1-4):511-516
Nutrient content and pH of rain samples collected at nine sites during 1988-1996 were studied to determine the amounts of N, P and S added by precipitation over Maracaibo Lake basin. The basin is a wide depression occupied by Lake Maracaibo and extensive alluvial plains and delimited by a mountainous zone of variable physiolgraphic characteristics with different cattle ranching and industrial activities. Rain pHs averaged ≈ 4 to 6, individual samples occasionally reached as low as pH 3 in the south basin. NH4 + levels were significantly higher (up to 2.6 mg/l NH4-N) than NO3 ? plus NO2 ?. Phosphorus levels were low, ranging from undetectable to 1.5 mg/l. The amounts of inorganic N/ha/yr added ranged from ≈ 5.4 Kg in the north to ≈ 8 Kg in the south basin; around the lakeshore, it was estimated that ≈ 9.8–16.8 Kg TN/ha (≈ 55 % as organic-N) are annually deposited. The annual amounts of SO4-S/ha added range from ≈ 10 to 13 Kg. The contribution of precipitation to P in the ecosystem is very small; ≈ 0.02 – 0.8 Kg of PO4-P/ha/yr was added in basin. The results of this study show that precipitation represents a significant factor for the total nitrogen and sulfur loading to Maracaibo Lake Basin. 相似文献
73.
Maria Margarida Ribeiro Leopoldo Sanchez Carla Ribeiro Fátima Cunha José Araújo Nuno M. G. Borralho Cristina Marques 《Annals of Forest Science》2011,68(4):701-714
• Introduction
Tree genetic improvement programs usually lack, in general, pedigree information. Since molecular markers can be used to estimate the level of genetic similarity between individuals, we genotyped a sample of a Portuguese Eucalyptus globulus breeding population—a reference population of 125 individuals—with 16 microsatellites (SSR). 相似文献74.
Maldonado PD Rivero-Cruz I Mata R Pedraza-Chaverrí J 《Journal of agricultural and food chemistry》2005,53(6):1996-2001
Geranium niveum S. Watson (Geraniaceae) is a medicinal herb widely used by the Tarahumara Indians of Mexico. This species is rich in proanthocyanidins and other phenolics. Previous in vitro assays have demonstrated that proanthocyanidins exhibited antiinflammatory, antiviral, antibacterial, enzyme-inhibiting, antioxidant, and radical-scavenging properties. In view of its medicinal use and chemical composition, the aim of the present study was to determine the in vitro antioxidant activity of the extracts and two proanthocyanidins (geranins A and D) from the roots of G. niveum by using seven different assay systems, namely, 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide anion (O2*-), hydrogen peroxide (H2O2), hydroxyl radical (OH*), hypochlorous acid (HOCl), and singlet oxygen ((1)O2). Two known antioxidants, resveratrol and ascorbic acid, were used as positive controls. The results showed that geranins A and D and the extracts were able to scavenge ABTS, DPPH, O2*-, OH*, and HOCl. The scavenging ability of geranins A and D was similar to that of resveratrol and ascorbic acid in the following assays: ABTS, O2*-, and HOCl. The scavenging capacity of ascorbic acid for DPPH was higher than that of both geranins and resveratrol. On the other hand, the OH* scavenging action of both geranins and resveratrol was similar. The methanol-CHCl3 (1:1) extract had a higher ability to scavenge ABTS, DPPH, and O2*- radicals than the chloroform extract. In turn, the latter was more potent than the methanol-CHCl3 (1:1) extract as OH* or HOCl scavenger agent. Neither geranins A and D nor the extracts were able to scavenge H2O2 and (1)O2. In conclusion, G. niveum roots have proanthocyanidins with powerful radical scavenging in vitro activity. This property may partially explain the wide use of this plant in the Tarahumara indigenous system of medicine for the treatment of gastrointestinal illnesses (other than spasms), pain, and fevers associated with oxidative stress. 相似文献
75.
Fermin Rivera M. Rosario Sanchez Alfonso Lugo Pedro Ramirez Ricardo Ortiz Arturo Calderon 《Water, air, and soil pollution》1987,34(3):245-262
A protozoological survey was performed on a waste-stabilization pond to isolate, identify, and determine the incidence of ciliates present in these waters. The correlation between the species found and the physicochemical parameters was investigated. One hundred and eighty samples were analyzed from February 1983 to February 1984. Free-living ciliates isolated include:Carchesium polypinum Linnaeus,Vorticella microstoma Ehrenberg,Vorticella convallaria Linnaeus,Didinium balbiani Fabré-Domergue,Amphileptus claparedei Stein,Spathidium spathula Müller,Litonotus fasciola Ehrenberg,Paramecium caudatum Müller,Paramecium aurelia Ehrenberg,Tetrahymena vorax Kidder,Tetrahymena pyriformis Ehrenberg,Cyclidium glaucoma Müller,Aspidisca costata Ehrenberg, andStylonychia putrina Stokes. The performance of the pond was predominantly anaerobic. The temperature, total alkalinity, and nitrate concentration were the most variable parameters in the system studied. 相似文献
76.
K. M. Iftekharuddaula M. A. Newaz M. A. Salam H. U. Ahmed M. A. A. Mahbub E. M. Septiningsih B. C. Y. Collard D. L. Sanchez A. M. Pamplona D. J. Mackill 《Euphytica》2011,178(1):83-97
Flooding is one of the major hazards of rice production for the rainfed lowland rice ecosystem, and tolerant cultivars are
urgently needed to help protect farmers from submergence damage. A quick and efficient strategy was implemented to introgress
SUB1, a major QTL for submergence tolerance, into a rainfed lowland mega variety BR11 of Bangladesh by only two backcrosses and
one selfing generation. In marker-assisted backcrossing (MABC), one tightly-linked simple sequence repeat (SSR) and two gene-based
markers, four flanking SSR and 116 background SSR markers were used for foreground, recombinant and background selection,
respectively, in backcrosses between a SUB1 donor IR40931-33-1-3-2 and BR11. BR11-Sub1, identified in a BC2F2 plant, possessed BR11 type SSR alleles on all fragments analyzed except the SUB1 QTL. The introgression size in BR11-Sub1 was 800 Kb indicating approximately 99.8% identity to BR11. BR11-Sub1 along with
other introgression lines showed submergence tolerance similar to the tolerant parent. Yield, yield-component parameters and
grain physico-chemical properties showed successful recovery of the BR11 traits in BR11-Sub1, with yield potential ranging
from 5.2 to 5.6 t/ha, not significantly different from the recurrent parent mega variety BR11. Producing a large number (~1000)
of backcross F1 plants was considered essential to achieve recombination on both sides of the gene, limiting linkage drag with only two backcrosses.
A large number of background markers ensured proper recovery of the recurrent parent genome in the BC2F2 generation. The study demonstrates a rapid and highly precise strategy to introgress a major QTL by BC2F2 generation into a modern rice variety using an unadapted donor. The variety can replace BR11 on more than 2 million of ha
in Bangladesh and provide major increases in rice production. 相似文献
77.
Aida Z. Kebede Baldev S. Dhillon Wolfgang Schipprack Jose L. Araus Marianne Bänziger Kassa Semagn Gregorio Alvarado Albrecht E. Melchinger 《Euphytica》2011,180(2):219-226
For in vivo production of doubled haploid (DH) lines in maize, the rate of haploid induction is of crucial importance. Maternal
haploid induction depends primarily on the inducer used as a pollinator. However, the source germplasm used as a maternal
parent and the environmental conditions for induction may also influence haploid induction and these aspects have not been
examined in tropical maize so far. The objectives of our study were to (i) monitor the variation for haploid induction rate
(HIR) among diverse source germplasm in tropical maize, (ii) determine the relative importance of general (GCA) and specific
(SCA) combining abilities for HIR, and (iii) investigate the influence of summer and winter seasons and genotype × season
interactions on this trait. Ten inbreds were mated in a half diallel design. The resulting 45 F1 single crosses were pollinated with the haploid inducer hybrid RWS × UH400 during the summer 2008 and winter 2009 seasons
in a lowland tropical environment in Mexico. HIR of the single crosses averaged over seasons ranged from 2.90 to 9.66% with
an overall mean of 6.74%. Mean HIR was significantly (P < 0.01) higher during the winter (7.37%) than summer season (6.11%). Significant (P < 0.01) variation was observed due to GCA effects of parental inbreds of single crosses but not for SCA, GCA × season and
SCA × season interactions. Our study underpins that a higher HIR in tropical maize can be obtained by selecting appropriate
source germplasm and undertaking pollination under favorable environmental conditions. 相似文献
78.
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80.
Marta Crivos María Rosa Martínez María Lelia Pochettino Carolina Remorini Cynthia Saenz Anahí Sy 《Agriculture and Human Values》2004,21(2-3):111-125
Through the ethnographic record of the subsistence activities partially or completely performed in the domestic sphere in two Mbyá-Guaraní settlements in Misiones (Argentina), we outline factors important in describing the local natural environment. Data was collected through systematic observation and also through semi-structured interviews. Analysis indicates that the natural environment of the area is characterized by the indigenous community in several different ways. Thus, local people view the environment as made up of different “micro-environments,” and they consequently think of the elements that compose these “micro-environments” as having different, distinct characteristics. In the context of their daily activities, both these “micro-environments” and the elements that compose them are regarded as resources, in that they are viewed in terms of what is in them relevant to the subsistence of these groups in the rainforest. It is the intention of this study to initiate the systematic recording and processing of information on how these indigenous communities know and manage the natural resources available to them in their daily life. 相似文献