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901.
The object of this study was to evaluate different strategies for the production of secondary somatic embryos of cassava on
picloram-supplemented media. Embryogenically competent calli maintained on double-strength Murashige and Skoog (1962) (MS)
medium supplemented with 1 mg l−1 picloram were used as starting material. Secondary embryogenesis from this callus was tested using various basal salt media
in either the solid or the liquid state and containing two different concentrations of picloram. Some of the factors effecting
the conversion of the embryos into plantlets were also studied. A liquid Schenck and Hildebrand (1972) medium containing 60
g l−1 sucrose and 12 mg l−1 picloram favoured the continual production of a highly embryogenic nodular callus. The normal development of somatic embryos
from this tissue was dependant on the use of a picloram-free MS basal salt medium. The embryos were desiccated over a saturated
salt solution of K2SO4 (RH 97.5% at 25 °C) and allowed to develop into plantlets on a MS medium containing 0.1 mg l−1 BA. This procedure allowed for the normal elongation of the embryonic hypocotyl and formation of vigorous and viable shoots
and roots.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
902.
Qing-Yuan Sun Wei-Hua Wang Misa Hosoe Toshiaki Taniguchi Da-Yuan Chen Yasuo Shioya 《Development, growth & differentiation》1997,39(4):523-529
The effects of protein kinase C (PKC) activation on meiotic resumption and cortical granule (CG) exocytosis as well as its dependence on Ca2+ in porcine eggs matured in vitro were studied. Cortical granule release was judged by both confocal laser microscopy after the eggs were labeled with fluorescein isothiocyanate-peanut agglutinin (FITC-PNA) and electron microscopy. Meiotic resumption and pronuclear formation were observed after eggs were stained with acetic orcein. When eggs were treated with PKC activators, 1-oleyl-2-acetyl-glycerol (OAG) or phorbol 12-myristate 13-acetate (PMA), the pronuclear formation percentage was significantly lower than that of Ca2+ ionophore A23187-treated group, but not statistically different from that in negative control group (P > 0.05), and most of the eggs were still arrested at metaphase II stage, suggesting that PKC activation does not induce the resumption of meiosis and pronuclear formation. In contrast, PKC activation induced 89.1% to 100% of the eggs completely or partially released their CG in different groups, not statistically different from A23187-treated group, and this effect could be overcome by PKC inhibition. When the intracellular free Ca2+ was chelated with acetoxymethal ester form of 1,2-bis(0-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), and then treated with PMA or OAG in Ca2+ -free medium, the proportions of eggs with CG release were 90.9% and 78.1%, respectively, not statistically different from the above-treated groups, suggesting that CG exocytosis induced by PKC activation is independent of Ca2+ rise. The results indicate that different events of porcine egg activation may be uncoupled from one another. 相似文献
903.
Oleinikov AV Gray MD Zhao J Montgomery DD Ghindilis AL Dill K 《Journal of proteome research》2003,2(3):313-319
Protein arrays will greatly accelerate research and development in medical and biological sciences. We have used cell-free protein biosynthesis and a parallel immobilization strategy for producing protein biochips. We demonstrate a model two-protein microarray using luciferase and green fluorescent protein, both expressed in a cell-free system and specifically immobilized on CombiMatrix semiconductor oligonucleotide microarrays. This demonstration provides evidence for the appropriate folding, activity, robust presentation, and efficient flexible detection of proteins on the microscale. 相似文献
904.
Differential signalling potential of insulin- and IGF-1-receptor cytoplasmic domains. 总被引:14,自引:3,他引:14 下载免费PDF全文
The human receptors for insulin-like growth factor 1 (IGF-1) and insulin, and two chimeric receptors consisting of ligand-binding, extracellular insulin receptor and intracellular IGF-1 receptor structures, have been expressed in NIH-3T3 fibroblasts. All four receptor types were synthesized, processed and transported to the cell surface to form high-affinity binding sites. All normal and chimeric receptors had an active tyrosine kinase which was regulated by homologous or heterologous ligands respectively. In addition, cell surface receptors were internalized efficiently and subjected to accelerated degradation in the presence of ligand. While all four types of receptor stimulated glucose transport with similar efficiency, they displayed significant differences in their mitogenic signalling potentials. Receptors with an IGF-1 receptor cytoplasmic domain were 10 times more active in stimulating DNA synthesis than the insulin receptor. In NIH-3T3 cells overexpressing wild-type and chimeric receptors, maximal growth responses obtained with IGF-1 or insulin alone were equivalent to those obtained with 10% fetal calf serum. We conclude that in the cell system employed the receptors for IGF-1 and insulin mediate short-term responses similarly, but display distinct characteristics in their long-term mitogenic signalling potentials. 相似文献
905.
906.
An Approach to Integrating Occupational Safety and Health into Life Cycle Assessment: Development and Application of Work Environment Characterization Factors 下载免费PDF全文
Kelly A. Scanlon Shannon M. Lloyd George M. Gray Royce A. Francis Peter LaPuma 《Journal of Industrial Ecology》2015,19(1):27-37
Integrating occupational safety and health (OSH) into life cycle assessment (LCA) may provide decision makers with insights and opportunities to prevent burden shifting of human health impacts between the nonwork environment and the work environment. We propose an integration approach that uses industry‐level work environment characterization factors (WE‐CFs) to convert industry activity into damage to human health attributable to the work environment, assessed as disability‐adjusted life years (DALYs). WE‐CFs are ratios of work‐related fatal and nonfatal injuries and illnesses occurring in the U.S. worker population to the amount of physical output from U.S. industries; they represent workplace hazards and exposures and are compatible with the life cycle inventory (LCI) structure common to process‐based LCA. A proof of concept demonstrates application of the WE‐CFs in an LCA of municipal solid waste landfill and incineration systems. Results from the proof of concept indicate that estimates of DALYs attributable to the work environment are comparable in magnitude to DALYs attributable to environmental emissions. Construction and infrastructure‐related work processes contributed the most to the work environment DALYs. A sensitivity analysis revealed that uncertainty in the physical output from industries had the most effect on the WE‐CFs. The results encourage implementation of WE‐CFs in future LCA studies, additional refinement of LCI processes to accurately capture industry outputs, and inclusion of infrastructure‐related processes in LCAs that evaluate OSH impacts. 相似文献
907.
Marie-Line Peyot Joshua P. Gray Julien Lamontagne Peter J. S. Smith George G. Holz S. R. Murthy Madiraju Marc Prentki Emma Heart 《PloS one》2009,4(7)
Background
Glucagon like peptide-1 (GLP-1) and its analogue exendin-4 (Ex-4) enhance glucose stimulated insulin secretion (GSIS) and activate various signaling pathways in pancreatic β-cells, in particular cAMP, Ca2+ and protein kinase-B (PKB/Akt). In many cells these signals activate intermediary metabolism. However, it is not clear whether the acute amplification of GSIS by GLP-1 involves in part metabolic alterations and the production of metabolic coupling factors.Methodology/Prinicipal Findings
GLP-1 or Ex-4 at high glucose caused release (∼20%) of the total rat islet insulin content over 1 h. While both GLP-1 and Ex-4 markedly potentiated GSIS in isolated rat and mouse islets, neither had an effect on β-cell fuel and energy metabolism over a 5 min to 3 h time period. GLP-1 activated PKB without changing glucose usage and oxidation, fatty acid oxidation, lipolysis or esterification into various lipids in rat islets. Ex-4 caused a rise in [Ca2+]i and cAMP but did not enhance energy utilization, as neither oxygen consumption nor mitochondrial ATP levels were altered.Conclusions/Significance
The results indicate that GLP-1 barely affects β-cell intermediary metabolism and that metabolic signaling does not significantly contribute to GLP-1 potentiation of GSIS. The data also indicate that insulin secretion is a minor energy consuming process in the β-cell, and that the β-cell is different from most cell types in that its metabolic activation appears to be primarily governed by a “push” (fuel substrate driven) process, rather than a “pull” mechanism secondary to enhanced insulin release as well as to Ca2+, cAMP and PKB signaling. 相似文献908.
The molecular diversity of the methanogenic community in a hypereutrophic freshwater lake determined by PCR-RFLP 总被引:1,自引:0,他引:1
Whitby C Earl J Lanyon C Gray S Robinson J Meadows J Edwards C 《Journal of applied microbiology》2004,97(5):973-984
AIMS: To combine database-held sequence information with a programme of experimental molecular ecology to define the methanogenic community of a hypereutrophic lake by a PCR-restriction fragment length polymorphism (RFLP) analysis. METHODS AND RESULTS: Methanogen diversity in a hypereutrophic freshwater lake was analysed using 16S rDNA PCR-RFLP. Database-held 16S rRNA gene sequences for 76 diverse methanogens were analysed for specific restriction sites that permitted unequivocal differentiation of methanogens. Restriction digestion and agarose gel electrophoresis of the 16S rDNA from selected methanogen pure cultures generated observed restriction profiles that corroborated the expected patterns. This method was then tested by analysing methanogen diversity in samples obtained over 1 year from sediment and water samples taken from the same sampling site. CONCLUSIONS: Restriction analysis of the 16S rRNA gene sequences from 157 methanogen clones generated from lakewater and sediment samples showed that over 50% were similar to Methanoculleus spp. Furthermore, a total of 16 RFLP types (1-16) were identified, eight of which contained no cultured representative archaeal 16S rRNA gene sequences. SIGNIFICANCE AND IMPACT OF THE STUDY: This RFLP strategy provides a robust and reliable means to rapidly identify methanogens in the environment. 相似文献
909.
High-resolution mapping of genotype-phenotype relationships in cri du chat syndrome using array comparative genomic hybridization 总被引:6,自引:0,他引:6 下载免费PDF全文
Zhang X Snijders A Segraves R Zhang X Niebuhr A Albertson D Yang H Gray J Niebuhr E Bolund L Pinkel D 《American journal of human genetics》2005,76(2):312-326
We have used array comparative genomic hybridization to map DNA copy-number changes in 94 patients with cri du chat syndrome who had been carefully evaluated for the presence of the characteristic cry, speech delay, facial dysmorphology, and level of mental retardation (MR). Most subjects had simple deletions involving 5p (67 terminal and 12 interstitial). Genotype-phenotype correlations localized the region associated with the cry to 1.5 Mb in distal 5p15.31, between bacterial artificial chromosomes (BACs) containing markers D5S2054 and D5S676; speech delay to 3.2 Mb in 5p15.32-15.33, between BACs containing D5S417 and D5S635; and the region associated with facial dysmorphology to 2.4 Mb in 5p15.2-15.31, between BACs containing D5S208 and D5S2887. These results overlap and refine those reported in previous publications. MR depended approximately on the 5p deletion size and location, but there were many cases in which the retardation was disproportionately severe, given the 5p deletion. All 15 of these cases, approximately two-thirds of the severely retarded patients, were found to have copy-number aberrations in addition to the 5p deletion. Restriction of consideration to patients with only 5p deletions clarified the effect of such deletions and suggested the presence of three regions, MRI-III, with differing effect on retardation. Deletions including MRI, a 1.2-Mb region overlapping the previously defined cri du chat critical region but not including MRII and MRIII, produced a moderate level of retardation. Deletions restricted to MRII, located just proximal to MRI, produced a milder level of retardation, whereas deletions restricted to the still-more proximal MRIII produced no discernible phenotype. However, MR increased as deletions that included MRI extended progressively into MRII and MRIII, and MR became profound when all three regions were deleted. 相似文献
910.