Metabolites of corticosteroids that contain the 21-oic acid moiety are found in human urine. The acids from neutral steroids and urinary pigments have been separated by passing the mixture through a column of polyethyleneimine cellulose. The acids adhering to the column are quantitatively eluted with dilute formic acid. The purified preparation is suitable for derivatization and chromatographic analysis. 相似文献
Proformica longiseta, an ant species endemic to certain high mountains, has been studied with regard to its tendency to nest underneath rocks. This behaviour led us to investigate whether a particular type of rock is selected, and, if so, the advantages to this species of the selection. This study was located at 2400 m above sea-level in the Sierra Nevada mountains (Granada, Spain). To determine the range of rock sizes available, in eight control plots the thicknesses were recorded and also the maximum and minimum diameters of all rocks with surface area of more than 6 cm2. A total of 1724 rocks were recorded, noting among the rock types available those that were used for nesting. Also as a preliminary estimate of the thermal characteristics of the rocks, we recorded the temperatures of the air, soil surface, soil under a rock covering an ant nest, and soil at 30 cm depth. The results indicate thatP. longiseta selects flat rocks with a surface area/thickness ratio of 2–5, the thickness being not less than 1.5 cm, the surface area being 50–250 cm2 and volume less than 1000 cm3. This type of rock offers the nests two beneficial but apparently contradictory effects: (1) protection against high temperatures on hot days, and (2) warmth on colder days by absorbing the diffusing solar heat more effectively than the air or soil around the nest. 相似文献
The geometric features of agricultural trees such as canopy area, tree height and crown volume provide useful information about plantation status and crop production. However, these variables are mostly estimated after a time-consuming and hard field work and applying equations that treat the trees as geometric solids, which produce inconsistent results. As an alternative, this work presents an innovative procedure for computing the 3-dimensional geometric features of individual trees and tree-rows by applying two consecutive phases: 1) generation of Digital Surface Models with Unmanned Aerial Vehicle (UAV) technology and 2) use of object-based image analysis techniques. Our UAV-based procedure produced successful results both in single-tree and in tree-row plantations, reporting up to 97% accuracy on area quantification and minimal deviations compared to in-field estimations of tree heights and crown volumes. The maps generated could be used to understand the linkages between tree grown and field-related factors or to optimize crop management operations in the context of precision agriculture with relevant agro-environmental implications. 相似文献
Studies of marine viromes (viral metagenomes) have revealed that DNA viruses are highly diverse and exhibit biogeographic patterns. However, little is known about the diversity of RNA viruses, which are mostly composed of eukaryotic viruses, and their biogeographic patterns in the oceans. A growth in global commerce and maritime traffic may accelerate spread of diverse and non-cosmopolitan DNA viruses and potentially RNA viruses from one part of the world to another. Here, we demonstrated through metagenomic analyses that failure to comply with mid-ocean ballast water exchange regulation could result in movement of viromes including both DNA viruses and RNA viruses (including potential viral pathogens) unique to geographic and environmental niches. Furthermore, our results showed that virus richness (known and unknown viruses) in ballast water is associated with distance between ballast water exchange location and its nearest shoreline as well as length of water storage time in ballast tanks (voyage duration). However, richness of only known viruses is governed by local environmental conditions and different viral groups have different responses to environmental variation. Overall, these results identified ballast water as a factor contributing to ocean virome transport and potentially increased exposure of the aquatic bioshpere to viral invasion. 相似文献
Genetic variation at 10 enzyme loci was analysed in Elysia timida sacoglossan mollusc samples, originating from both coastal lagoon and marine sites. The observed heterozygosity ranged from 0.390 (Los Urrutias) to 0.277 (Tabarca). Marine and coastal lagoon populations were characterised by exclusive alleles. 相似文献
We have analyzed 640 Spanish cystic fibrosis (CF) families for mutations in the CFTR gene by direct mutation analysis, microsatellite haplotypes, denaturing gradient gel electrophoresis, single-strand conformation
analysis and direct sequencing. Seventy-five mutations account for 90.2% of CF chromosomes. Among these we have detected seven
novel CFTR mutations, including four missense (G85V, T582R, R851L and F1074L), two nonsense (E692X and Q1281X) and one splice site mutation
(711+3A→T). Three variants, two in intronic regions (406-112A/T and 3850-129T/C) and one in the coding region (741C/T) were
also identified. Mutations G85V, T582R, R851L, E692X and Q1281X are severe, with lung and pancreatic involvement; 711+3A→T
could be responsible for a pancreatic sufficiency/insufficiency variable phenotype; and F1074L was associated with a mild
phenotype. These data demonstrate the highest molecular heterogeneity reported so far in CF, indicating that a wide mutation
screening is necessary to characterize 90% of the Spanish CF alleles.
Received: 3 July 1997 / Accepted: 20 August 1997 相似文献
Oral mucositis is an inflammation of the oral mucosa mainly resulting from the cytotoxic effect of 5-fluorouracil (5-FU). The literature shows anti-inflammatory action of l-cysteine (l-cys) involving hydrogen sulfide (H2S). In view of these properties, we investigate the effect of l-cys in oral mucositis induced by 5-FU in hamsters. The animals were divided into the following groups: saline 0.9%, mechanical trauma, 5-FU 60–40 mg/kg, l-cys 10/40 mg and NaHS 27 µg/kg. 5-FU was administered on days 1st to 2nd; 4th day excoriations were made on the mucosa; 5th–6th received l-cys and NaHS. For data analysis, histological analyses, mast cell count, inflammatory and antioxidants markers, and immunohistochemistry (cyclooxygenase-2(COX-2)/inducible nitric oxide synthase (iNOs)/H2S) were performed. Results showed that l-cys decreased levels of inflammatory markers, mast cells, levels of COX-2, iNOS and increased levels of antioxidants markers and H2S when compared to the group 5-FU (p < 0.005). It is suggested that l-cys increases the H2S production with anti-inflammatory action in the 5-FU lesion.