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91.
92.
Srinivas S Rodriguez T Clements M Smith JC Beddington RS 《Development (Cambridge, England)》2004,131(5):1157-1164
The anterior visceral endoderm (AVE) of the mouse embryo is a specialised extra-embryonic tissue that is essential for anterior patterning of the embryo. It is characterised by the expression of anterior markers such as Hex, Cerberus-like and Lhx1. At pre-gastrula stages, cells of the AVE are initially located at the distal tip of the embryo, but they then move unilaterally to the future anterior. This movement is essential for converting the existing proximodistal axis into an anteroposterior axis. To investigate this process, we developed a culture system capable of imaging embryos in real time with single cell resolution. Our results show that AVE cells continuously change shape and project filopodial processes in their direction of motion, suggesting that they are actively migrating. Their proximal movement stops abruptly at the junction of the epiblast and extra-embryonic ectoderm, whereupon they move laterally. Confocal microscope images show that AVE cells migrate as a single layer in direct contact with the epiblast, suggesting that this tissue might provide directional cues. Together, these results show that the anteroposterior axis is correctly positioned by the active movement of cells of the AVE in response to cues from their environment, and by a 'barrier' to their movement that provides an endpoint for this migration. 相似文献
93.
Regeneration of ethyl parathion antibodies for repeated use in immunosensor: a study on dissociation of antigens from antibodies 总被引:3,自引:0,他引:3
Kandimalla VB Neeta NS Karanth NG Thakur MS Roshini KR Rani BE Pasha A Karanth NG 《Biosensors & bioelectronics》2004,20(4):903-906
Reliable analysis using an immunosensor strongly depends on the specificity, activity, and sensitivity of the antibody. Immobilization of antibody on the solid matrix enables its repeated use, for which it is required to dissociate the antigens and antigen-enzyme conjugate from the immobilized antibody matrix after each use and while doing so, a maximum retention of activity and specificity are crucial requirements. In the present investigation, on the development of an immunosensor for the organophosphorus pesticide ethyl parathion (EP) using EP antibodies, different dissociating agents such as organic solvents, detergents and acidic buffers, that is, dimethyl sulphoxide (DMSO), Tween-20, cetyl trimethylammonium bromide (CTAB), methanol, chloroform, guanidium chloride (GdmCl), glycine-HCl (Gly-HCl) buffer in the pH range of 1.5-3.0, pierce buffer and combination of DMSO and methanol in phosphate buffer and Gly-HCl buffer and salts like NaCl and MgCl2 were used. Generally about 50-60% dissociation was obtained with some degree of denaturation of the antibody immobilized on the sepharose matrix. However, 1% DMSO in combination with 0.2 M Gly-HCl buffer at a pH of 2.3 showed 97% dissociation and the immobilized antibody retained sufficient activity to carry out 14 reproducible assays for EP. 相似文献
94.
Bioinformatics and cellular signaling 总被引:6,自引:0,他引:6
The understanding of cellular function requires an integrated analysis of context-specific, spatiotemporal data from diverse sources. Recent advances in describing the genomic and proteomic 'parts list' of the cell and deciphering the interrelationship of these parts are described, including genome-wide location analysis, standards for microarray data analysis, and two-hybrid and mass spectrometry approaches. This information is being collected and curated in databases such as the Alliance for Cellular Signaling (AfCS) Molecule Pages, which will serve as vital tools for the reconstruction and analysis of cellular signaling networks. 相似文献
95.
96.
van Niel EW Palmfeldt J Martin R Paese M Hahn-Hägerdal B 《Applied and environmental microbiology》2004,70(3):1843-1846
Lactococcal lactate dehydrogenases (LDHs) are coregulated at the substrate level by at least two mechanisms: the fructose-1,6-biphosphate/phosphate ratio and the NADH/NAD ratio. Among the Lactococcus lactis species, there are strains that are predominantly regulated by the first mechanism (e.g., strain 65.1) or by the second mechanism (e.g., strain NCDO 2118). A more complete model of the kinetics of the regulation of lactococcal LDH is discussed. 相似文献
97.
The basal cut end of coppice shoot cuttings of Pongamia pinnata was treated for 24 h with 0 (water treated control) or 5.0 mmol/L of KMnO4, KCI, and KH2PO4 or 2.5 mmol/L of K2HPO4 and K2SO4. Inorganic salts of P, S, Cl and Mn significantly influenced IAA ionization and adventitious rhizogenesis. P and S salts had lower IAA ionization potential, but more pronounced effect on adventitious rhizogenesis than Cl and Mn salts. The linear regression analysis also established negative correlations between salt induced IAA ionization with various characteristics of adventitious rhizogenesis such as sprouting (r = -0.83, p < 0.05), rooting (r = -0.82, p < 0.05), root number (r = -0.95, p < 0.01), and root length (r = -0.80, p < 0.1). The implication of IAA ionization in adventitious rhizogenesis has been discussed and the possible role of inorganic salts therein suggested. 相似文献
98.
Lebsack AD Gunzner J Wang B Pracitto R Schaffhauser H Santini A Aiyar J Bezverkov R Munoz B Liu W Venkatraman S 《Bioorganic & medicinal chemistry letters》2004,14(10):2463-2467
We have identified and synthesized a series of [1,2,4]triazolo[3,4-a]phthalazine derivatives as high-affinity ligands to alpha 2 delta-1 subunit of voltage gated calcium channels. Structure-activity relationship studies directed toward improving the potency and physical properties of 2 lead to the discovery of 20 (IC(50)=15 nM) and (S)-22 (IC(50)=30 nM). A potent and selective radioligand, [(3)H]-(S)-22 was also synthesized to demonstrate that this ligand binds to the same site as gabapentin. 相似文献
99.
Maternal and perinatal morbidity and mortality rates are significantly higher in pregnancies complicated by preterm labor, pre-eclampsia and fetal growth restriction. Decades of research have not translated into a clear understanding of the underlying pathophysiologies or effective identification of women who are at high risk of developing these complications. Often the severity of these diseases does not correlate with the clinical symptoms, and current diagnostic methods are unable to accurately predict the conditions prior to clinical presentation. Though several potential markers have been proposed for each of these disorders, to date none have proven clinical utility. Emerging proteomic technology is only beginning to be employed in pregnancy research. A comprehensive analysis of gestational tissues can be expected to contribute to the elucidation of the complex molecular mechanisms of pregnancy and related complications. Comparison of the expression profiles of normal and pathogenic tissues and biofluids may also highlight novel candidate marker proteins that have so far remained undetected. More interestingly, rapidly evolving technologies using sophisticated bioinformatic tools are demonstrating their potential in disease diagnostics by using overall protein profiles to detect diseases. The clinical significance of these methodological advances is enormous. Early diagnosis together with improved understanding of underlying molecular mechanisms can enhance outcomes and increase effective management and therapeutic options. 相似文献
100.
Amit?K?Trivedi Sangeeta?Rani Vinod?KumarEmail author 《Reproductive biology and endocrinology : RB&E》2004,2(1):79
Little is known about how hormones interact in the photoperiodic induction of seasonal responses in birds. In this study,
two experiments determined if the treatment with melatonin altered inhibitory effects of prolactin on photoperiodic induction
of seasonal responses in the Palearctic-Indian migratory male redheaded bunting Emberiza bruniceps. Each experiment employed three groups (N = 6–7 each) of photosensitive birds that were held under 8 hours light: 16 hours
darkness (8L:16D) since early March. In the experiment 1, beginning in mid June 2001, birds were exposed to natural day lengths
(NDL) at 27 degree North (day length = ca.13.8 h, sunrise to sunset) for 23 days. In the experiment 2, beginning in early
April 2002, birds were exposed to 14L:10D for 22 days. Beginning on day 4 of NDL or day 1 of 14L:10D, they received 10 (experiment
1) or 13 (experiment 2) daily injections of both melatonin and prolactin (group 1) or prolactin alone (group 2) at a dose
of 20 microgram per bird per day in 200 microliter of vehicle. Controls (group 3) received similar volume of vehicle. Thereafter,
birds were left uninjected for the next 10 (experiment 1) or 9 days (experiment 2). All injections except those of melatonin
were made at the zeitgeber time 10 (ZT 0 = time of sunrise, experiment 1; time of lights on, experiment 2); melatonin was
injected at ZT 9.5 and thus 0.5 h before prolactin. Observations were recorded on changes in body mass, testicular growth
and feather regeneration. 相似文献