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Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
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Danielle B Rodrigues Roger Chammas Natália V Malavasi Patrícia LN da Costa Rosa M Chura-Chambi Keli N Balduino Ligia Morganti 《BMC biotechnology》2010,10(1):19
Background
Theracyte is a polytetrafluoroethylene membrane macroencapsulation system designed to induce neovascularization at the tissue interface, protecting the cells from host's immune rejection, thereby circumventing the problem of limited half-life and variation in circulating levels. Endostatin is a potent inhibitor of angiogenesis and tumor growth. Continuous delivery of endostatin improves the efficacy and potency of the antitumoral therapy. The purpose of this study was to determine whether recombinant fibroblasts expressing endostatin encapsulated in Theracyte immunoisolation devices can be used for delivery of this therapeutic protein for treatment of mice bearing B16F10 melanoma and Ehrlich tumors. 相似文献3.
Leonova IN Dobrovol'skaia OB Kminskaia LN Adogina IG Koren' LV Khotyleva LV Salina EA 《Genetika》2005,41(9):1236-1243
Hexaploid triticale (x Triticosecale Wittmack) lines were examined using molecular markers and the hybridization in situ technique. Triticale lines were generated based on wheat varieties differing by the Vrn gene systems and the earing times. Molecular analysis was performed using Xgwm and Xrms microsatellite markers with the known chromosomal localization in the common wheat Triticum aestivum, and rye Secale cereale genomes. Comparative molecular analysis of triticale lines and their parental forms showed that all lines contained A and B genomes of common wheat and also rye homeologous chromosomes. In the three lines the presence of D genome markers, mapped to the chromosomes 2D and 7D, was demonstrated. This was probably the consequence of the translocations of homeologous chromosomes from wheat genomes, which took part during the process of triticale formation. The data obtained by use of genomic in situ hybridization supported the data of molecular genetic analysis. In none of the lines wheat--rye translocations or recombinations were observed. These findings suggest that the change of the period between the seedling appearance and earing time in triticale lines compared to the initial wheat lines, resulted from the inhibitory effect of rye genome on wheat vernalization genes. 相似文献
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Pamela Orjuela-Sánchez Nadira D Karunaweera Mônica da Silva-Nunes Natal S da Silva Kézia KG Scopel Raquel M Gonçalves Chanaki Amaratunga Juliana M Sá Duong Socheat Rick M Fairhust Sharmini Gunawardena Thuraisamy Thavakodirasah Gawrie LN Galapaththy Rabindra Abeysinghe Fumihiko Kawamoto Dyann F Wirth Marcelo U Ferreira 《BMC genetics》2010,11(1):65
Background
The ideal malaria parasite populations for initial mapping of genomic regions contributing to phenotypes such as drug resistance and virulence, through genome-wide association studies, are those with high genetic diversity, allowing for numerous informative markers, and rare meiotic recombination, allowing for strong linkage disequilibrium (LD) between markers and phenotype-determining loci. However, levels of genetic diversity and LD in field populations of the major human malaria parasite P. vivax remain little characterized.Results
We examined single-nucleotide polymorphisms (SNPs) and LD patterns across a 100-kb chromosome segment of P. vivax in 238 field isolates from areas of low to moderate malaria endemicity in South America and Asia, where LD tends to be more extensive than in holoendemic populations, and in two monkey-adapted strains (Salvador-I, from El Salvador, and Belem, from Brazil). We found varying levels of SNP diversity and LD across populations, with the highest diversity and strongest LD in the area of lowest malaria transmission. We found several clusters of contiguous markers with rare meiotic recombination and characterized a relatively conserved haplotype structure among populations, suggesting the existence of recombination hotspots in the genome region analyzed. Both silent and nonsynonymous SNPs revealed substantial between-population differentiation, which accounted for ~40% of the overall genetic diversity observed. Although parasites clustered according to their continental origin, we found evidence for substructure within the Brazilian population of P. vivax. We also explored between-population differentiation patterns revealed by loci putatively affected by natural selection and found marked geographic variation in frequencies of nucleotide substitutions at the pvmdr-1 locus, putatively associated with drug resistance.Conclusion
These findings support the feasibility of genome-wide association studies in carefully selected populations of P. vivax, using relatively low densities of markers, but underscore the risk of false positives caused by population structure at both local and regional levels.See commentary: http://www.biomedcentral.com/1741-7007/8/907.
Pauly M; Andersen LN; Kauppinen S; Kofod LV; York WS; Albersheim P; Darvill A 《Glycobiology》1999,9(1):93-100
A full-length c-DNA encoding a xyloglucan-specific endo -beta-1, 4-
glucanase (XEG) has been isolated from the filamentous fungus Aspergillus
aculeatus by expression cloning in yeast. The colonies expressing
functional XEG were identified on agar plates containing azurine-dyed
cross-linked xyloglucan. The cDNA encoding XEG was isolated, sequenced,
cloned into an Aspergillus expression vector, and transformed into
Aspergillus oryzae for heterologous expression. The recombinant enzyme was
purified to apparent homogeneity by anion- exchange and gel permeation
chromatography. The recombinant XEG has a molecular mass of 23,600, an
isoelectric point of 3.4, and is optimally stable at a pH of 3.4 and
temperature below 30 degreesC. The enzyme hydrolyzes structurally diverse
xyloglucans from various sources, but hydrolyzes no other cell wall
component and can therefore be considered a xyloglucan-specific endo
-beta-1, 4-glucanohydrolase. XEG hydrolyzes its substrates with retention
of the anomeric configuration. The Kmof the recombinant enzyme is 3.6
mg/ml, and its specific activity is 260 micromol/min per mg protein. The
enzyme was tested for its ability to solubilize xyloglucan oligosaccharides
from plant cell walls. It was shown that treatment of plant cell walls with
XEG yields only xyloglucan oligosaccharides, indicating that this enzyme
can be a powerful tool in the structural elucidation of xyloglucans.
相似文献
8.
Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4° C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample. 相似文献
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