Molecular Characterization of the USDA White Clover (Trifolium repens L.) Core Collection by RAPD Markers     

Fernanda Bortolini  Miguel Dall’Agnol  Maria Teresa Schifino-Wittmann 《Genetic Resources and Crop Evolution》2006,53(5):1081-1087

White clover is one of the most important forage legume species worldwide, playing an important role in Southern Brazil temperate cultivated pastures. This work was aimed to characterize the genetic variability of the USDA white clover core collection formed by 78 accessions representing 50 countries, together with two very well known cultivars (Huia and Ladino Regal), using RAPD (Random Amplified Polymorphic DNA) markers to produce genetic fingerprints. There were used DNA bulks formed by the extraction and mixture of 20 random individuals from each accession. Twenty four primers were used, which revealed from 3 to 29 bands, forming a total of 371 polymorphic bans and only one monomorphic, ranging from 50 to 3098 bp. The results showed a genetic similarity among the accessions, ranging from 0.18 to 0.58 (Jaccard’s index), with an average of 0.24, allowing the identification of each individual accession using just three primers. The results also showed a large genetic variability within the white clover core collection, probably due to its reproduction mode and ploidy level, which could be used in plant breeding program.  相似文献   

Microbial immobilisation and turnover of N labelled substrates in two arable soils under field and laboratory conditions     

Louisa Wessels Perelo  Miguel Jimenez  Jean Charles Munch 《Soil biology & biochemistry》2006,38(5):912-922

Microbial biomass N dynamics were studied under field and laboratory conditions in soils of high yield (HY) and low yield (LY) areas in an agricultural field. The objective of the study was to determine the size and activity of soil microbial biomass in the soils of the different yield areas and to compare these data obtained under field and laboratory conditions. Soils were amended with ¹⁵N labelled mustard (Sinapis alba) residues (both experiments) and labelled nitrate (laboratory only) at 30 μg N g⁻¹ dry soil. Soil microbial biomass (SMB) N, mineral N (N_min) and total N content was monitored both in the field and in the laboratory. N₂O efflux was additionally measured in laboratory treatments. Isotope ratios were determined for SMB in both experiments, for all other parameters only in the laboratory treatments. In the laboratory less amounts of added substrate N were immobilised by the SMB in HY soils compared to LY soils, whereas in the field immobilisation of added N by SMB was higher in HY soils initially and slightly lower after 40 days of incubation. Calculated turnover times in the laboratory nitrate, laboratory mustard and field mustard amendments were 0.18, 0.27 and 0.74 years (HY) and 0.22, 0.61 and 1.01 years (LY), respectively. The turnover times of added substrate N always showed the trend to be faster in HY soils compared to LY soils. A faster turnover of nutrients in the HY soils may involve a better nutrient supply of the plants, which coincides with the higher agricultural yield observed in these areas.  相似文献   

Illinois Soil Nitrogen Test Method Optimization for Analysis of Temperate Mineral Grassland Soils     

Noeleen T. McDonald  Miguel A. Dionisio Fernández  David P. Wall 《Communications in Soil Science and Plant Analysis》2016,47(22):112-121

ABSTRACT

A reliable and practical test that can provide timely measurements of the levels of mineralizable nitrogen (MN) in soil is critical for improving the accuracy of N fertilizer applications for grassland and crops. The Illinois soil N test (ISNT) is considered to be a good estimate of MN, once soils are grouped according to soil characteristics such as the drainage type and sampling depth. To date, development and evaluation of the ISNT method has been conducted using arable soils mainly in North America where, in general, soils have lower levels of soil organic matter (SOM) compared to temperate grassland soils. We evaluated the effects of two pre-treatment soil aggregate sizes of <1 mm and <2 mm on the yield and recovery of MN (1) across temperate grassland soil types, and (2) across a 6-h interval diffusion period. No significant difference existed in the concentrations of ISNT-N between the two soil aggregate sizes of each soil type. For both aggregate sample sizes, the recovery of spiked amino sugar-N glucosamine from a temperate grassland soil was generally linear until hour 5, after which the quantities of recovered N diminished. Although N recovery after 6 h of diffusion at 50°C (±1°C) was less than 100% in both aggregate size samples, the response models indicated that the standard ISNT protocol using a 5-h diffusion period is appropriate for temperate grassland soils. The incomplete recovery of N in these mineral soils suggested that the protocol could be further optimized for temperate soils with high organic matter content and additional evaluation of the temperature during diffusion within an enclosed environment may be required using N (spiked glucosamine-N) recovery studies.  相似文献   

Nutritional and physiological responses of young growing rats to diets containing raw cowpea seed meal,protein isolate (globulins), or starch     

Olivera L  Canul RR  Pereira-Pacheco F  Cockburn J  Soldani F  McKenzie NH  Duncan M  Olvera-Novoa MA  Grant G 《Journal of agricultural and food chemistry》2003,51(1):319-325

The nutritional and physiological effects of raw cowpea (Vigna unguiculata (L) Walp.) seed meal, protein isolate (globulins), or starch on the metabolism of young growing rats have been evaluated in 14-day trials. Wet and dry weight gain, feed conversion efficiency, and lipid and protein accretion were significantly reduced as a result of inclusion of seed meal, globulins, or starch in the diet, with growth retardation being most marked with the seed meal. The proportional weights of the small intestine and pancreas were increased by meal diets, and serum cholesterol levels were slightly reduced. The globulins and raw starch also increased relative small intestine weights but had no effect on the pancreas or serum constituents. The effects of cowpeas on rats appeared to be due primarily to the combined actions of globulins, resistant starches, protease inhibitors, and possibly fiber and non-starch polysaccharides on intestinal and systemic metabolism.  相似文献   

The cell and molecular basis of mechanical, cold, and inflammatory pain     

Abrahamsen B  Zhao J  Asante CO  Cendan CM  Marsh S  Martinez-Barbera JP  Nassar MA  Dickenson AH  Wood JN 《Science (New York, N.Y.)》2008,321(5889):702-705

Peripheral pain pathways are activated by a range of stimuli. We used diphtheria toxin to kill all mouse postmitotic sensory neurons expressing the sodium channel Nav1.8. Mice showed normal motor activity and low-threshold mechanical and acute noxious heat responses but did not respond to noxious mechanical pressure or cold. They also showed a loss of enhanced pain responses and spontaneous pain behavior upon treatment with inflammatory insults. In contrast, nerve injury led to heightened pain sensitivity to thermal and mechanical stimuli indistinguishable from that seen with normal littermates. Pain behavior correlates well with central input from sensory neurons measured electrophysiologically in vivo. These data demonstrate that Na(v)1.8-expressing neurons are essential for mechanical, cold, and inflammatory pain but not for neuropathic pain or heat sensing.  相似文献   

Requirement of Cks2 for the first metaphase/anaphase transition of mammalian meiosis     

Spruck CH  de Miguel MP  Smith AP  Ryan A  Stein P  Schultz RM  Lincoln AJ  Donovan PJ  Reed SI 《Science (New York, N.Y.)》2003,300(5619):647-650

We generated mice lacking Cks2, one of two mammalian homologs of the yeast Cdk1-binding proteins, Suc1 and Cks1, and found them to be viable but sterile in both sexes. Sterility is due to failure of both male and female germ cells to progress past the first meiotic metaphase. The chromosomal events up through the end of prophase I are normal in both CKS2-/- males and females, suggesting that the phenotype is due directly to failure to enter anaphase and not a consequence of a checkpoint-mediated metaphase I arrest.  相似文献   

Worldwide scientific publishing activity     

Perez-Iratxeta C  Andrade MA 《Science (New York, N.Y.)》2002,297(5581):519

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Infectious behavior in a parasitoid     

Varaldi J  Fouillet P  Ravallec M  López-Ferber M  Boulétreau M  Fleury F 《Science (New York, N.Y.)》2003,302(5652):1930

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Animal versus wind dispersal and the robustness of tree species to deforestation     

Montoya D  Zavala MA  Rodríguez MA  Purves DW 《Science (New York, N.Y.)》2008,320(5882):1502-1504

Studies suggest that populations of different species do not decline equally after habitat loss. However, empirical tests have been confined to fine spatiotemporal scales and have rarely included plants. Using data from 89,365 forest survey plots covering peninsular Spain, we explored, for each of 34 common tree species, the relationship between probability of occurrence and the local cover of remaining forest. Twenty-four species showed a significant negative response to forest loss, so that decreased forest cover had a negative effect on tree diversity, but the responses of individual species were highly variable. Animal-dispersed species were less vulnerable to forest loss, with six showing positive responses to decreased forest cover. The results imply that plant-animal interactions help prevent the collapse of forest communities that suffer habitat destruction.  相似文献   

Spain's Ramón y Cajal Program     

Axness C  Tornero P  Ricote J  Algueró M 《Science (New York, N.Y.)》2003,300(5616):52-53

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