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1.
Although the importance of the endosperm as a food store inmany angiosperm seeds is well known, its significance duringearly embryogenesis has been neglected. In many interspecifichybrids, and in some other situations, embryos do not developfully and abort. It has often been stated that this is causedby the endosperm failing to conduct sufficient nutrients tothe embryo, but seldom has it been suggested that the endospermactively controls most of the early stages of morphogenesisof the embryo. Information gleaned from a broad survey of theliterature, combined with additional evidence presented here,obtained fromSolanum incanumand interspecific hybrids, indicatethat the endosperm is dynamic and very active in regulatingearly embryo development. This requires highly integrated geneticcontrol of rapidly changing metabolism in the endosperm. Ininterspecific hybrids, lack of coordination may cause unbalancedproduction of growth regulating substances by the endospermand hence abortion of the embryo, or even unregulated productionof nucleases and proteases resulting firstly in autolysis ofthe endosperm and then digestion of the embryo. The endospermmay thus serve to detect inappropriate hybridization of speciesor ploidy levels and so prevent waste of resources by producingseeds that would result in sterile hybrids or unthrifty subsequentgenerations. This discriminatory function of the endosperm hasdiminished during evolution and domestication of the crop plantSolanummelongenaL.Copyright 1998 Annals of Botany Company Solanum, embryo morphogenesis, endosperm, hybrid, seed development. 相似文献
2.
Michele Rivkin-Flsh 《Medical anthropology quarterly》2000,14(1):119-120
Pragmatic Women and Body Politics. Margaret Lock and Patricia A. Kaufert. eds. Cambridge, UK: Cambridge University Press, 1998. xii +364 pp.
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp. 相似文献
Maternities and Modernities: Colonial and Postcolonial Experiences in Asia and the Pacific. Kalpana Ram and Margaret Jolly. eds. Cambridge, UK: Cambridge University Press, 1998. xiv. 305 pp. 相似文献
3.
4.
Hand JW 《Progress in biophysics and molecular biology》2007,93(1-3):192-194
The first and second sessions of the Workshop focussed on the basics of ultrasound and infrasound, their applications in both industry and medicine, and metrology and protection standards for ultrasound applications. 相似文献
5.
Höpfl G Ogunshola O Gassmann M 《American journal of physiology. Regulatory, integrative and comparative physiology》2004,286(4):R608-R623
For most organisms oxygen is essential fo life. When oxygen levels drop below those required to maintain the minimum physiological oxygen requirement of an organism or tissue it is termed hypoxia. To counter act possible deleterious effects of such a state, an immediate molecular response is initiated causing adaptation responses aimed at cell survival. This response is mediated by the hypoxia-inducible factor-1 (HIF-1), which is a heterodimer consisting of an alpha- and a beta-subunit. HIF-1 alpha protein is stabilized under hypoxic conditions and therefore confers selectivity to this response. Hypoxia is characteristic of tumors, mainly because of impaired blood supply resulting from abnormal growth. Over the past few years enormous progress has been made in the attempt to understand how the activation of the physiological response to hypoxia influences neoplastic growth. In this review some aspects of HIF-1 pathway activation in tumors and the consequences for pathophysiology and treatment of neoplasia are discussed. 相似文献
6.
Studies of human constitution and mental features are traditionally among the main concepts of anthropological research. In
this research, we attempted to discover connections between morphological and constitutional features and self-esteem in children
and adolescents. Such a connection was discovered in some studied age groups. The obtained results could serve as a basis
for further studies in this field. 相似文献
7.
Gonzalez-Reimers E Rodriguez-Moreno F Martinez-Riera A Mas-Pascual A Delgado-Ureta E Galindo-Martin L Arnay-de la Rosa M Santolaria-Fernandez F 《Biological trace element research》1999,68(1):41-49
To elucidate accumulation of minerals in human iliac arteries with aging, the content of minerals was analyzed by inductively
coupled plasma atomic emission spectrometry. Bilateral common, internal, and external iliac arteries of 16 men and 8 women,
ranging ages from 65 to 93 yr, were examined. It was found that an extremely high accumulation of calcium and phosphorus occurred
in the common iliac artery at old age, being higher than that of the internal and external iliac arteries. It should be noted
that the accumulation of calcium and phosphorus is the highest in the common iliac artery among the human arteries examined
to date.
Regarding sexual differences, the content of calcium and phosphorus in the common and internal iliac arteries was higher in
women than in men, whereas their content in the external iliac artery was lower in women than in men. 相似文献
8.
Astrocytes transport the monocarboxylate acetate, but synaptosomes do not. The reason for this is unknown, because both preparations express monocarboxylate transporters (MCT). The transport and metabolism of lactate, another monocarboxylate, was examined in these two preparations, and the results were compared to those for acetate. Lactate transport is more rapid in astrocytes than in synaptosomes, but of lower affinity (Kms of 17 and 4 mM, respectively). Lactate (0.2 mM) is metabolized to CO2 more rapidly in synaptosomes than in astrocytes (rates of 0.37 and 0.07 nmol x mg protein(-1) x min(-1), respectively). The reason for this is unclear, but cellular differences in lactate dehydrogenase isotype expression may be involved. Acetate is metabolized to CO2 more rapidly in astrocytes than in synaptosomes (rates of 0.43 and 0.02 nmol x mg protein(-1) x min(-1), respectively). This is likely due to cellular differences in the expression of monocarboxylate transporter subtypes. 相似文献
9.
Chohan ZH Pervez H Rauf A Khan KM Maharvi GM Supuran CT 《Journal of enzyme inhibition and medicinal chemistry》2004,19(2):161-168
A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/ antifungal against two or more species as compared to the uncomplexed Schiff-base ligands. 相似文献
10.
Pushkar Shejwalkar 《Inorganica chimica acta》2011,366(1):209-218
New sulfur derivatives of phosphoramidite ligands were synthesized and the impact of the sulfur unit on the spectroscopic properties of their rhodium and iridium complexes was investigated. The new ligands Bn2NPSCH2CH2Sa(P-Sa) (Bn = benzyl, 4), Bn2NPSCHCHSa(CH2)3CaH2(P-Sa)(Ca-Sa) (6) and Bn2NP(4-XC6H4OMe)2 (X = S, 7a; X = O, 7b) were converted to the rhodium and iridium complexes trans-[Rh(CO)Cl(L)2] (L = 4, 6, 7), [RhCl(COD)(L)] (L = 4, 6, 7), [IrCl(COD)(7a)] and [IrCl2Cp∗(6)]. For comparison, some phosphoramidite complexes of these formulations also were synthesized. The new metal complexes were spectroscopically analyzed. For the carbonyl complexes, the νCO IR stretching frequencies were lower than for the corresponding phosphite and phosphoramidite ligands. The 1JPRh coupling constants for the rhodium complexes with the new ligands were also smaller than for the respective phosphoramidite and phosphite complexes. Finally, the 1JPSe coupling constants of the selenides of the new ligands were lower than those of the phosphoramidite ligands but higher than for PPh3. The spectroscopic data reveal that the new thio ligands 4, 6 and 7a are more electron donating than phosphites and phosphoramidites but less electron donating than PPh3. 相似文献
11.
E Yunis O M De Caballero C Ramirez 《Folia primatologica; international journal of primatology》1977,27(3):165-177
Q- and G-banding studies of Aotus trivigatus trivirgatus and Aotus trivirgatus griseimembra are presented. After the analysis of 8 specimens, 2 A.t. trivirgatus and 6 A.t. griseimembra and the review of the literature on the field we state the existence of two different karyotypes, 2n = 54 and 2n = 50, for A.t. trivirgatus and three different karyotypes, 2n = 54, 2n = 52 and 2n = 50, for A.t. griseimembra. It was found that Robertsonian translocations were the mechanism involved in the numerical reduction of the chromosomes. The data presented include the statement of two natural hybrids and the cross-breedings which originated them. 相似文献
12.
Zahid H. Chohan Humayun Pervez A. Rauf Khalid M. Khan Ghulam M. Maharvi 《Journal of enzyme inhibition and medicinal chemistry》2013,28(2):161-168
A new series of antibacterial and antifungal triazine-derived mono- and di-substituted (symmetrical and unsymmetrical) Schiff-bases and their cobalt(II), copper(II), nickel(II) and zinc(II) metal complexes have been synthesized and characterized by their elemental analyses, molar conductances, magnetic moments and IR and electronic spectral measurements. IR spectra indicated the ligands to act as tridentate towards divalent metal ions via a trazine-N, the azomethine-N and, indole-NH and deprotonated-O of salicylaldehyde. The magnetic moments and electronic spectral data suggest octahedral geometry for the Co(II), Ni(II) and Zn(II)complexes and square-pyramid for Cu(II) complexes. NMR spectral data of the ligands and their diamagnetic zinc(II) complexes well-define their proposed structures/geometries. Elemental analyses data of the ligands and metal complexes agree with their proposed structures/geometries. The synthesized ligands, along with their metal complexes were screened for their antibacterial activity against Escherichia coli, Bacillus subtillis, Shigella flexneri, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi and for antifungal activity against Trichophyton longifusus, Candida albicans, Aspergillus flavus, Microsporum canis, Fusarium solani and Candida glaberata. The results of these studies show the metal complexes to be more antibacterial/antifungal against two or more species as compared to the uncomplexed Schiff-base ligands. 相似文献
13.
Objective: It has recently been demonstrated that, in middle‐aged women, a wide hip circumference is a protective factor for a number of health endpoints in later years. The effect seems to be independent of both overweight and waist circumference. This paper aims to replicate this finding in another population‐based sample consisting of women and men. Research Methods and Procedures: This was a prospective observational study consisting of a random subset of adult Danes. A total of 2987 subjects born in 1922, 1932, 1942, or 1952 and 35, 45, 55, or 65 years of age (at examination in 1987 to 1988) participated in the Danish MONICA (MONItoring trends and determinants of CArdiovascular disease) project, with measurements of height, weight, and hip and waist circumference taken. Through personal identification numbers, incidence of coronary heart disease (CHD) and cardiovascular disease (CVD) until the end of 1998 and all causes of death until 2001 were retrieved from the National Registers of Hospital Discharge. There was an average of 10 years of follow‐up for incidence of CVD and CHD and 13 years of follow‐up for total mortality. Results: Large hip circumference, relative to body size and waist circumference, predicted less incidence of CVD, CHD, and total death in women. This was not the case in men; BMI and waist circumference were the strongest independent predictors. Discussion: A large hip circumference seems to have independent and positive effects on CVD and CHD morbidity and mortality in women, but no protective effect on cardiovascular health in men. However, a borderline significant protective effect on total mortality was observed. 相似文献
14.
Acid extracts of human pancreas and gastric corpus and antral mucosa and muscularis were investigated for the presence of met-enkephalin and leu-enkephalin by radioimmunoassay, Sephadex chromatography and radioreceptor assay. As the assays for leu-enkephalin crossreacted with those for met-enkephalin, only cyanogen bromide-treated samples were used for the determination of leu-enkephalin. Met-enkephalin immunoreactivity was destroyed by more than 94% when treated with cyanogen bromide. Serial extract dilutions displaced 125 I labelled met-enkephalin and 125 I leu-enkephalin in the respective enkephalin radioimmunoassay both roughly parallel to the standard curves. Sephadex chromatography of the extracts resulted in elution of met-enkephalin and leu-enkephalin immunoreactivity similar to the size of 3H-met-enkephalin, and these eluates displaced 3H-met-enkephalin from rat brain membranes in an opioid radioreceptor assay. The highest concentration of met-enkephalin and leu-enkephalin immunoreactivity in tissue obtained at surgery was in the mucosa of the body of the stomach. Met- and leu-enkephalin receptor bioreactivity concentrations exceeded immunoreactivity concentrations. These investigations provide evidence of the presence of met-enkephalin- and leu-enkephalin-like substances in human stomach and pancreas. 相似文献
15.
Henry H Q Heng Guo Liu Steven Bremer Karen J Ye Joshua Stevens Christine J Ye 《Génome》2006,49(3):195-204
The theoretical view that genome aberrations rather than gene mutations cause a majority of cancers has gained increasing support from recent experimental data. Genetic aberration at the chromosome level is a key aspect of genome aberration and the systematic definition of chromosomal aberrations with their impact on genome variation and cancer genome evolution is of great importance. However, traditionally, efforts have focused on recurrent clonal chromosome aberrations (CCAs). The significance of stochastic non-clonal chromosome aberrations (NCCAs) is discussed in this paper with emphasis on the simple types of NCCAs that have until recently been considered "non-significant background". Comparison of various subtypes of transitional and late-stage CCAs with simple and complex types of NCCAs has uncovered a dynamic relationship among NCCAs, CCAs, overall genomic instability, and karyotypic evolution, as well as the stochastic nature of cancer evolution. Here, we review concepts and methodologies to measure NCCAs and discuss the possible causative mechanism and consequences of NCCAs. This study raises challenging questions regarding the concept of cancer evolution driven by stochastic chromosomal aberration mediated genome irregularities that could have repercussions reaching far beyond cancer and organismal genomes. 相似文献
16.
J. Morley M.A. Bray R.W. Jones D.H. Nugteren D.A. van Dorp 《Prostaglandins & other lipid mediators》1979,17(5):729-736
The ability of partially purified human and guinea-pig haematogenous cell populations, when cultured in vitro, to metabolise arachidonic acid (AA) has been studied. Supernatants from 24 hour cell culture have been subjected to analysis for products of AA metabolism by gas chromatography with electron-capture detection.The cell types studied were human peripheral blood monocytes (both glass adherent and non-adherent), neutrophils, eosinophils and leukemic leucocytes; thoracic duct lymphocytes and lung alveolar macrophages. From the guinea-pig, induced and non-induced macrophage or neutrophil enriched peritoneal exudate populations, lymph node cells, peritoneal eosinophils and peripheral blood platelets were examined. Supernatants were assayed for the presence of PGE2, PGD2, PGF2α, TXB2 and 6-keto-PGF1α. In all types studied PGE2 and TXB2 were the major products formed. The identification of PGE2 and TXB2 was confirmed by GC/MS with multiple ion monitoring.The results have been compared with other reports and their possible significance discussed in relation to the proposed role of prostaglandins as mediators and modulators in immunopathology. 相似文献
17.
姜黄色素及其提制方法 总被引:20,自引:0,他引:20
来源于姜科姜黄属植物姜黄根茎的姜黄是国内外食品行业允许使用的重要天然色素之一,具有重要的开发利用价值。姜黄素的主要提取方法可分为有机溶剂提取法和水提取法;精制方法主要包括专一性溶剂法、酸碱法、酶水解法和柱层析法等。文中对各种方法进行了简要介绍和评述。 相似文献
18.
Sandra M. Vaz 《Archives of biochemistry and biophysics》2009,484(2):127-431
In spite of the many studies on protein modifications by reactive species, knowledge about the products resulting from the oxidation of protein-aromatic residues, including protein-derived radicals and their stable products, remains limited. Here, we compared the oxidative modifications promoted by peroxynitrite and myeloperoxidase/hydrogen peroxide/nitrite in two model proteins, ribonuclease (6Tyr) and lysozyme (3Tyr/6Trp). The formation of protein-derived radicals and products was higher at pH 5.4 and 7.4 for myeloperoxidase and peroxynitrite, respectively. The main product was 3-nitro-Tyr for both proteins and oxidants. Lysozyme rendered similar yields of nitro-Trp, particularly when oxidized by peroxynitrite. Hydroxylated and dimerized products of Trp and Tyr were also produced, but in lower yields. Localization of the main modified residues indicates that peroxynitrite decomposes to radicals within the proteins behaving less specifically than myeloperoxidase. Nitrogen dioxide is emphasized as an important protein modifier. 相似文献
19.
Zask A Kaplan J Du X MacEwan G Sandanayaka V Eudy N Levin J Jin G Xu J Cummons T Barone D Ayral-Kaloustian S Skotnicki J 《Bioorganic & medicinal chemistry letters》2005,15(6):1641-1645
Potent and selective TACE and MMP inhibitors utilizing the diazepine and thiazepine ring systems were synthesized and evaluated for biological activity in in vitro and in vivo models of TNF-alpha release. Oral activity in the mouse LPS model of TNF-alpha release was seen. Efficacy in the mouse collagen induced arthritis model was achieved with diazepine 20. 相似文献
20.
The conversion of arachidonic acid (20:4) to prostaglandins by vascular tissue is important in the adult because of the antithrombotic effect of prostacyclin and in the fetus because of the vasodilatory effect of prostaglandin (PG) E2 on the ductus arteriosus. We have shown that vascular tissue converts various polyunsaturated fatty acids to monohydroxy and trihydroxy metabolites derived from hydroperoxides, which may be involved in regulating prostaglandin synthesis. We have now measured the amounts of these hydroperoxide metabolites, as well as those of prostaglandins, released from slices of rat, rabbit and bovine aortae, as well as from fetal calf aorta and ductus arteriosus. The major oxygenated polyunsaturated fatty acid metabolite formed by rat and bovine blood vessels was 6-oxo-PGF1 alpha. Fetal calf aorta and ductus arteriosus produced about five times as much 6-oxo-PGF1 alpha as adult bovine aorta. Much smaller amounts of the cyclooxygenase products, PGE2, 12-hydroxy-5,8,10-heptadecatrienoic acid, 11-hydroxy-5,8,12,14-icosatetraenoic acid (11-hydroxy-20:4), and 15-hydroxy-20:4, were released by aortae. Small amounts of the lipoxygenase product, 12-hydroxy-20:4, were also detected. Substantial amounts of free and esterified monohydroxy and trihydroxy metabolites of linoleic acid (18:2) were detected, especially in rat and rabbit aortae. Rabbit aorta, which had low cyclooxygenase activity, formed more oxygenated 18:2 metabolites than 20:4 metabolites. Indomethacin did not inhibit the formation of the 18:2 metabolites, indicating that cyclooxygenase was not involved. Neither exogenous 13-hydroxy-18:2 nor trihydroxyoctadecenoic acid was incorporated to a large extent into lipids from vascular endothelial or smooth muscle cells, suggesting that the esterified 18:2 oxygenation products had arisen mainly via direct oxygenation of lipids. 相似文献