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31.
After considering the need for quality control in NAA, the concept of quality in NAA procedures themselves is discussed, and
some important factors identified. Two approaches to improve quality are then described in more detail. The first concerns
the unique ability of NAA using different isotopic reactions and different modes (INAA/RNAA) to provide independent data sets
in the same laboratory, thus allowing internal validation or crosschecking. The second discusses the need for chemical yield
measurements in RNAA and the advantages of the radioisotopic tracer technique. Some recent advances and further possibilities
for this use of tracers are listed. 相似文献
32.
An existing radiochemical NAA procedure for Cd, Co, and Cu was improved to allow determination of individual radiochemical
yields by the radioisotopic tracer technique, thus eliminating errors owing to variable recovery.109Cd was used as tracer for Cd determination via115Cd/115mIn,57Co for Co via60Co, and potentially for Ni via58Co, whereas as a novelty67Cu, produced by reactor irradiation of ZnO of natural isotopic composition (by the67Zn [n,p]67Cu reaction) was used for Cu via the indicator nuclide64Cu. The simple production and purification of67Cu by anion exchange is described. Results for biological RMs are given and discussed. 相似文献
33.
Seed transmission of turnip yellow mosaic virus in winter turnip and winter oilseed rapes 总被引:1,自引:0,他引:1
This is the first record of seed transmission of turnip yellow mosaic virus (TYMV) in oilseed and turnip rapes. The seed transmission of TYMV in a naturally infected winter turnip rape (Brassica napus var. silvestris) cultivar Perko PVH was investigated. By ELISA 1.6%, 3.2% and 8.3% seed transmission of the virus was found in seed of plants from three localities. The proportion of infected seeds produced by artificially infected plants of winter oilseed rape (Brassica napus ssp. oleifera) and winter turnip rape cultivars was determined. The virus transmission rate, expressed as the proportion of virus-infected plants which germinated from the seed was for the oilseed rape cvs Jet Neuf 0.1%, Solida 0.4%, Silesia 0.8%, Darmor 1.2%, SL-507 0.2%, SL-509 0.0% and for the winter turnip rape cv. Perko 1.5%. ELISA cannot be used in direct tests on bulk seed lots to estimate proportion of infected seed, but must be used on germinated seedlings. 相似文献
34.
We have used a cell-free polysome-based in-vitro mRNA-degradation system to investigate the halflives of plant cell mRNAs. In order to establish the fidelity of the in-vitro system, we used cordycepin to determine the in-vivo half-lives of -tubulin and actin mRNAs in the primary leaves of 4-d-old etiolated oat (Avena sativa L.) seedlings. The in-vitro rank order of half-lives for phytochrome A (45 min), -tubulin (105 min), and actin (220 min) mRNAs mimicked the in-vivo rank order. A pulse of red light given to excised etiolated primary leaves caused an in-vivo reduction in the half-life of -tubulin mRNA. The selectivity of the polysome-based system was further demonstrated by the decrease in the half-life of -tubulin mRNA (from 105 min to 60 min) induced by a pulse of red light given to the etiolated oat seedlings prior to isolation of polysomes. Red light did not affect the apparent half-lives of phytochrome A or actin mRNAs.Abbreviations
cab
gene for chlorophyll-a/b-binding protein
- kb(p)
kilobase (pair)
-
phyA
gene for type-I phytochrome protein
-
rbcS
gene for ribulose-1,5-bisphosphate-carboxylase small-subunit
We thank Dr. Richard B. Meagher for the pSAc3 actin clone. We thank Dr. Cecil Stewart for the use of his density-gradient fractionator, and Dr. Virginia Crane for instruction in using the fractionator. We also appreciate the helpful comments provided by the other members of the laboratory during the course of this research: Dr. Isaac John, Dr. Iffat Rahim, Linda Barnes, Bruce Held, David Higgs, and Theresa Tirimanne. This work was supported by USDA grants CRGO 88-37261-4196 and 91-37304-6397, and the Iowa State University Biotechnology Program. 相似文献
35.
We have utilized the polymerase chain reaction (PCR) to amplify a transcribed Taq1 polymorphism in the ribonucleotide reductase M1 subunit (RRM1) gene at chromosome 11p15.5, to investigate whether this locus is subjected to imprinting in embryonal tumours. The polymorphism was amplified from cDNA from 6 Wilms' tumours, one hepatoblastoma and corresponding samples of adjacent kidney or liver from individuals who were constitutionally heterozygous for the polymorphism. Taq1 digestion of PCR products revealed that both alleles were transcribed in all samples where both were present at the genomic level, indicating that the RRM1 locus is not subjected to imprinting in Wilms' tumour or hepatoblastoma. 相似文献
36.
Jennifer D. Watts Mary Farina John S. Kimball Luke D. Schiferl Zhihua Liu Kyle A. Arndt Donatella Zona Ashley Ballantyne Eugénie S. Euskirchen Frans-Jan W. Parmentier Manuel Helbig Oliver Sonnentag Torbern Tagesson Janne Rinne Hiroki Ikawa Masahito Ueyama Hideki Kobayashi Torsten Sachs Daniel F. Nadeau John Kochendorfer Marcin Jackowicz-Korczynski Anna Virkkala Mika Aurela Roisin Commane Brendan Byrne Leah Birch Matthew S. Johnson Nima Madani Brendan Rogers Jinyang Du Arthur Endsley Kathleen Savage Ben Poulter Zhen Zhang Lori M. Bruhwiler Charles E. Miller Scott Goetz Walter C. Oechel 《Global Change Biology》2023,29(7):1870-1889
Arctic-boreal landscapes are experiencing profound warming, along with changes in ecosystem moisture status and disturbance from fire. This region is of global importance in terms of carbon feedbacks to climate, yet the sign (sink or source) and magnitude of the Arctic-boreal carbon budget within recent years remains highly uncertain. Here, we provide new estimates of recent (2003–2015) vegetation gross primary productivity (GPP), ecosystem respiration (Reco), net ecosystem CO2 exchange (NEE; Reco − GPP), and terrestrial methane (CH4) emissions for the Arctic-boreal zone using a satellite data-driven process-model for northern ecosystems (TCFM-Arctic), calibrated and evaluated using measurements from >60 tower eddy covariance (EC) sites. We used TCFM-Arctic to obtain daily 1-km2 flux estimates and annual carbon budgets for the pan-Arctic-boreal region. Across the domain, the model indicated an overall average NEE sink of −850 Tg CO2-C year−1. Eurasian boreal zones, especially those in Siberia, contributed to a majority of the net sink. In contrast, the tundra biome was relatively carbon neutral (ranging from small sink to source). Regional CH4 emissions from tundra and boreal wetlands (not accounting for aquatic CH4) were estimated at 35 Tg CH4-C year−1. Accounting for additional emissions from open water aquatic bodies and from fire, using available estimates from the literature, reduced the total regional NEE sink by 21% and shifted many far northern tundra landscapes, and some boreal forests, to a net carbon source. This assessment, based on in situ observations and models, improves our understanding of the high-latitude carbon status and also indicates a continued need for integrated site-to-regional assessments to monitor the vulnerability of these ecosystems to climate change. 相似文献
37.
Alberto C. Q. Pinto David H. Byrne Suzanne M. Dethier Rogers 《In vitro cellular & developmental biology. Plant》1993,29(2):55-58
Summary Ovule perforation technique and media components (plant growth regulators andl-glutamine) were tested on in vitro growth of immature (<3 mm) embryos of “Springcrest” and “Earligrande” peaches. Ovule perforation
was 2 to 4 times more effective in promoting embryo growth than leaving ovules intact.l-Glutamine (400 mg·liter−1) promoted an increase in growth but could not be used with indole-acetic acid plus kinetin because an antagonistic effect
on embryo growth occurred. The use of these exogenous plant growth regulators did not increase embryo growth over in vivo
growth. 相似文献
38.
G. Vesey J.S. Slade M. Byrne K. Shepherd C.R. Fricker 《Journal of applied microbiology》1993,75(1):82-86
A novel method for the concentration of Cryptosporidium oocysts from water has been developed, based upon the precipitation of calcium carbonate. A 10 1 water sample is treated by adding solutions of calcium chloride and sodium bicarbonate and raising the pH value to 10 with sodium hydroxide. Crystals of calcium carbonate form and enmesh particles in the Cryptosporidium oocyst size range. The crystals are allowed to settle, the supernatant fluid is discarded and the calcium carbonate precipitate dissolved in sulphamic acid. The sample can be concentrated further by centrifugation. Recoveries of oocysts from seeded samples of deionized, tap and river water were in excess of 68%. 相似文献
39.
An integrated genetic linkage map for eucalypts using RFLP,RAPD and isozyme markers 总被引:19,自引:0,他引:19
M. Byrne J. C. Murrell B. Allen G. F. Moran 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1995,91(6-7):869-875
An integrated genetic linkage map for E. nitens was constructed in an outbred three-generation pedigree. Analysis of 210 RFLP, 125 RAPD and 4 isozyme loci resulted in 330 markers linked in 12 linkage groups covering 1462 cM (n=11 in eucalypts). The 12th linkage group is comprised of only 5 markers and will probably coalesce with another linkage group when further linked loci are located. Co-dominant RFLP loci segregating in both parents were used to integrate linkages identified in the male and female parents. Differences in recombination frequencies in the two parents were observed for a number of pairs of loci, and duplication of sequences was identified both within and between linkage groups. The markers were distributed randomly across the genome except for the RFLPs in linkage group 10 and for some loci showing segregation distortion, which were clustered into three regions of the map. The use of a large number of co-dominant RFLP loci in this map enables it to be used in other pedigrees of E. nitens and forms a basis for the detection and location of QTL in E. nitens and other eucalypt species. 相似文献
40.
Like many echinoderms, the seastar, Patiriella exigua has a wrinkled blastula rather than the smooth-walled blastula typical of most phyla. The cellular events of wrinkled blastula formation in P. exigua were documented using light, confocal and electron microscopy. Wrinkled blastulae have a highly infolded epithelium. Prior to wrinkling, the blastomeres are cuboidal with lipid droplets and yolk granules distributed throughout their cytoplasm. During wrinkling, the cells become columnar and the lipid and yolk reserves become redistributed to the basal and apical ends of the cells, respectively. Gastrulae have a tall columnar epithelium, with a basal accumulation of lipid. Interdigitation of numerous cell projections, including short lateral processes, basal lamellipodia and apical filopodia, assists in maintaining epithelial integrity during wrinkling. Apical filopodia have not been observed in other echinoderm embryos. Although 1 M urea caused elevation of the fertilization envelope, the embryos did not expand into the newly-created space. This is suggested to be due to the adhesive properties of the hyaline layer. Embryos removed from their envelope were enlarged with shallower and fewer wrinkles compared with controls. It appears that the integrity of the hyaline layer and fertilization envelope both influence the compact wrinkled profile of P. exigua blastulae. 相似文献