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41.
A. v. Degen 《Plant Systematics and Evolution》1888,38(7):230-232
Ohne Zusammenfassung 相似文献
42.
Francimary da Silva Carneiro Alexandre Magno Sebbenn Milton Kanashiro Bernd Degen 《Biotropica》2007,39(5):628-636
Six microsatellite loci were used to compare the mating system and gene flow in two consecutive years of a natural, unlogged population of Symphonia globulifera in a 500 ha experimental plot in the Brazilian Amazon (Flona Tapajós). The species had a low density of reproductive trees per hectare ( d = 0.46 trees/ha). We analyzed 205 trees and 261 and 487 open-pollinated seeds from 26 and 30 mother-trees in the years 2002 and 2003, respectively. A significant spatial genetic structure was detected for the adult trees for distances up to 100 m. We observed only small interannual differences in multilocus outcrossing rate ( , ), biparental inbreeding ( , ), and paternity correlation ( , ). The number of pollen donors contributing to mating of each tree in both years was estimated to be low ( ). Using TwoGener analysis to calculate the density of reproductive trees and the distance of pollen dispersal for normal and exponential models, the lowest error was detected for exponential model. For this model, the estimated density of reproductive trees was lower in 2002 ( trees/ha) than 2003 ( trees/ha), resulting in a higher distance of pollen dispersal in 2002 ( m) than 2003 ( m), although these changes did not affect the outcrossing and correlated mating rates. 相似文献
43.
44.
Ochratoxin A (OTA), a mycotoxin with nephrotoxic and carcinogenic properties, is an important contaminant of food and feed. Analysis of OTA in human biological fluids (blood, urine, or breast milk) has documented frequent exposure to this mycotoxin, yet at quite variable levels in different population groups across the world. Urine is the preferred matrix in biomonitoring since sample collection is non-invasive and better accepted by study participants. As only a small fraction of the ingested OTA is excreted in urine, determination of urinary OTA requires sensitive analytical techniques, and phase-II-metabolites should be also considered as biomarkers of exposure. Yet, data published so far on the presence of OTA-glucuronide/sulfate in human urine have been contradictory. In this study, urines (n = 38) from two groups of breastfed infants (German and Turkish) and from German adults were now analysed for the presence of OTA glucuronides or sulfates by an indirect method, i.e. by comparing the levels of OTA (aglycone) in urines without and after enzymatic hydrolysis with ß-glucuronidase/arylsulfatase. Additionally, ochratoxin A-8-β-glucuronide and open lactone ochratoxin A-8-β-glucuronide were synthesized to serve as reference materials for metabolite analysis. Attempts for definitive confirmation of glucuronides of OTA via direct identification in LC–MS/MS analysis were hampered by the lower ionizability of the conjugates compared to the parent compound. Considerable increases in OTA levels were found after enzymatic hydrolysis in several (not all) urine samples and provide clear evidence for the excretion of OTA-conjugates. The latter observation is of importance, since OTA phase-II-metabolites may escape detection when direct methods are applied for urinary biomarker analysis. In conclusion, enzymatic hydrolysis of urine samples is highly advisable in order to avoid an underestimation of the OTA-exposure. 相似文献
45.
Larval interspecific competition in two flea species parasitic on the same rodent host 总被引:1,自引:0,他引:1
Boris R. Krasnov Nadezhda V. Burdelova Irina S. Khokhlova Geogry I. Shenbrot Allan Degen 《Ecological Entomology》2005,30(2):146-155
Abstract. 1. The fleas Xenopsylla conformis and Xenopsylla ramesis exploit the same rodent host, Meriones crassus , and replace each other between two different habitats situated at the opposite sides of a steep precipitation gradient. It was hypothesised that the reason for this paratopic distribution is competition between larvae of the two species for food resources.
2. This hypothesis was tested by studying the performance of larvae of the two species in terms of their developmental success in mixed-species and single-species treatments under different air temperatures, relative humidities, substrate textures, and food abundance.
3. The number of individuals of X. conformis that survived until emergence depended significantly on the presence of competing species, being, in general, lower in mixed-species compared with single-species treatments. The decrease in developmental success of X. conformis in mixed-species treatments was found mainly during food shortage. In contrast, presence of the competitor did not affect the number of X. ramesis that survived until emergence. No effect of the presence of the competitor on duration of development or sex ratio was found in either species.
4. The results of this study, together with the results of our previous studies, provide an explanation for the paratopic distribution of X. conformis and X. ramesis that exploit the same host species. 相似文献
2. This hypothesis was tested by studying the performance of larvae of the two species in terms of their developmental success in mixed-species and single-species treatments under different air temperatures, relative humidities, substrate textures, and food abundance.
3. The number of individuals of X. conformis that survived until emergence depended significantly on the presence of competing species, being, in general, lower in mixed-species compared with single-species treatments. The decrease in developmental success of X. conformis in mixed-species treatments was found mainly during food shortage. In contrast, presence of the competitor did not affect the number of X. ramesis that survived until emergence. No effect of the presence of the competitor on duration of development or sex ratio was found in either species.
4. The results of this study, together with the results of our previous studies, provide an explanation for the paratopic distribution of X. conformis and X. ramesis that exploit the same host species. 相似文献
46.
Astract The mycotoxin ochratoxin A (OTA) is a public health issue in many countries. Data on OTA concentrations in foods and in blood
are available for several European countries including the Balkan area, as well as for Canada and Japan. Yet, for developing
countries such data are scarce. In this study we determined OTA blood levels as biomarker of exposure in bladder cancer patients
and in healthy controls from Pakistan. OTA in blood was analyzed after extraction by HPLC with fluorescence detection (limit
of detection: <0.03 ng/mL) in 96 patients and in 31 controls. Over 92% of all blood samples (87 patients, 30 controls) contained
quantifiable amounts of OTA: The mean OTA concentrations were 0.33 ng/mL (SD 0.42; range: 0.03 to 3.41 ng/mL) in bladder cancer
patients, and 0.31 ng/mL (SD 0.29; range: 0.04 to 1.25 ng/mL) in healthy controls. These OTA concentrations are comparable
to those reported for the general population in the European Union.
Presented at the 27th Mykotoxin-Workshop, Dortmund Germany, done 13–15, 2005.
The IfADo is accredited as WHO Cellaporating Center for Occupational Health. 相似文献
47.
The extent and spatial pattern of genetic variation at polymorphic allozyme loci in a population of pedunculate oak Quercus robur from the Bashkir Transural region was investigated using autocorrelation analysis. In the plantation examined, statistically significant local concentration of most of the alleles in two-dimensional space was identified. The measures for protection of this small population located outside of the western border of the species range, in the mountain--steppe habitat, and characterized by specific gene pool, are suggested. 相似文献
48.
Hui-Yu Liu Jianmin Han Sophia Y. Cao Tao Hong Degen Zhuo Jianbo Shi Zhenqi Liu Wenhong Cao 《The Journal of biological chemistry》2009,284(45):31484-31492
49.
Richard GH Immink Isabella AN Tonaco Stefan de Folter Anna Shchennikova Aalt DJ van Dijk Jacqueline Busscher-Lange Jan W Borst Gerco C Angenent 《Genome biology》2009,10(2):R24-16
Background
Plant MADS box proteins play important roles in a plethora of developmental processes. In order to regulate specific sets of target genes, MADS box proteins dimerize and are thought to assemble into multimeric complexes. In this study a large-scale yeast three-hybrid screen is utilized to provide insight into the higher-order complex formation capacity of the Arabidopsis MADS box family. SEPALLATA3 (SEP3) has been shown to mediate complex formation and, therefore, special attention is paid to this factor in this study. 相似文献50.
JF Yuan SJ Zhang O Jafer RA Furlong OE Chausiaux CA Sargent GH Zhang NA Affara 《BMC microbiology》2009,9(1):246