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31.
Bo Lönnerdal Barbara O. Schneeman Carl L. Keen Lucille S. Hurley 《Biological trace element research》1980,2(3):149-158
Rat bile and pancreatic fluid were examined for the presence of low molecular weight zinc complexes. Fluids were collected
separately by cannulation, and zinc distribution in collected samples was analyzed by gel filtration on Sephadex G-50. Most
of the zinc in bile was associated with low molecular weight zinc complexes; only a small amount of zinc was present in the
high molecular weight fraction. In contrast, pancreatic secretions did not contain low molecular weight zinc complexes, but
there were considerable amounts of zinc bound to high molecular weight compounds. The addition of zinc to bile resulted in
an increased amount of zinc in the low molecular weight fraction, while the addition of zinc to pancreatic fluid resulted
primarily in an increase in zinc bound to the high molecular weight components. Like pancreatic fluid, homogenates of pancreatic
tissue had no low molecular weight zinc complex. In rats whose bile and pancreatic fluid were removed and not returned into
the intestine, the amount of zinc bound to low molecular weight complexes in intestinal homogenates was reduced. This alteration
of the molecular distribution of zinc in intestinal homogenates by removal of bile and pancreatic fluid suggests the potential
importance of low molecular weight zinc complexes for zinc homeostasis. 相似文献
32.
Filaments of Fuchsia hybrida cv “Brilliant” double in length within 24 hr after bud opening. Filament growth characterized by fresh wt increase and cell elongation was significantly inhibited in vitro by l-aminocyclopropane-l-carboxylic acid (ACC) but was not promoted by any growth regulator tested. Ions of Co2+ blocked the inhibitive effects of ACC in vitro suggesting that ethylene produced from ACC is the growth inhibiting substance. Ethylene levels surrounding the filaments within the closed bud decreased during development, and premature opening of the sepals which released the ethylene into the atmosphere resulted in rapid filament growth. The ACC levels were found to be much higher in the anthers than the filaments. This suggests that ethylene produced from floral organs other than filaments regulates filament elongation in Fuchsia. This is the first report of filament growth which cannot be promoted by application of growth regulators but which is inhibited by ethylene. 相似文献
33.
Abad L Okabe S Shibayama M Kudo H Saiki S Aranilla C Relleve L de la Rosa A 《International journal of biological macromolecules》2008,42(1):55-61
The conformational associative properties of kappa-, iota-, and lambda-carrageenan and agar with irradiation dose were studied by dynamic light scattering. The random scission of the carrageenans and agar by gamma irradiation resulted in the formation of polydispersed lower molecular weight fragments. At high doses, the system moves towards uniformity. Conformational change from coil to helix was observed in all carrageenans and agar at doses up to 100 kGy. The conformational change in lambda-carrageenan may be due to the irregular and hybrid structure of this polysaccharide. Only agar and lambda-carrageenan still undergo conformational transition at a high dose of 200 kGy. Gelation is observed for kappa-, iota-carrageenan up to a dose of 50 kGy while gelation is still observed at 100 kGy for agar. Increase in the hydrodynamic radius with decreasing temperatures for the non-irradiated carrageenans follows this order: lambda-carrageenan>kappa-carrageenan>iota-carrageenan. Slight increases in hydrodynamic radius were observed with irradiation. 相似文献
34.
In a previous serological study, we compared 14 isolates of Actinomyces israelii serotype 2 with 13 serotype 1 cultures. The present study reports the morphological, physiological, and biochemical characteristics of these same 27 cultures. All of the isolates exhibited similar cellular morphology, and all but one produced the typical spider type microcolony on solid media. Twelve of 13 serotype 1 isolates produced the molar tooth type macrocolony, whereas only 2 of 14 serotype 2 cultures produced this type of rough colony. All of the serotype 1 isolates fermented arabinose with the production of acid; none of the serotype 2 cultures fermented this carbohydrate. All 27 cultures produced the greatest amount of growth when cultured under anaerobic conditions and grew poorly or not at all in air. Both groups of organisms produced similar reactions on other biochemical test media; these findings suggested that A. israelii serotype 2 should not be given a species designation. 相似文献
35.
Up to nine out of 10 male STR/ORT mice develop osteoarthritis (OA) of the medial tibial cartilage at an early age. This has now been shown to be related to changes in the activity and distribution of monoamine oxidase which is related to the metabolism of catecholamines. Treatment with diclofenac sodium tended to normalize this activity but there was no significant histological improvement. It was therefore postulated that two influences were involved in the development of OA: a cellular and an extracellular factor. The first was improved by diclofenac sodium; the second, namely oedema of the matrix, was improved by tribenoside. In very preliminary studies, feeding the two drugs simultaneously resulted in 7/9 mice having no sign of OA. 相似文献
36.
Nancy Burton-Wurster Hao Chen Rina Gendelman Michael L Jackson Lucille F Gagliardo Da Nian Gu Russell R Zelko George Lust James N MacLeod 《Matrix biology》2002,21(5):393-398
The population of fibronectins in adult mammalian cartilage includes high levels of a cartilage-specific (V+C)(-) isoform which lacks the V, III-15, and I-10 segments and thus contains a novel junction between protein segments III-14 and I-11. We report production of a monoclonal antibody specific for (V+C)(-) fibronectin without cross-recognition of V(+)C(+) and V(-)C(+) isoforms found in plasma and other tissues. Presentation of epitope to this antibody requires the III-14/I-11 junction, but the epitope itself extends beyond 14 amino acids immediately surrounding the junction site and involves a conformational change in III-14 and/or the N-terminal portion of I-11. The antibody, designated Mab 5D10 anti (V+C)(-), displays specificity for (V+C)(-) fibronectin from multiple mammalian species including humans and utility in immunoblots, immunohistochemistry, and ELISA. 相似文献
37.
The control of bacterial pathogens requires the development of tools allowing the precise identification of strains at the subspecies level. It is now widely accepted that these tools will need to be DNA-based assays (in contrast to identification at the species level, where biochemical based assays are still widely used, even though very powerful 16S DNA sequence databases exist). Typing assays need to be cheap and amenable to the designing of international databases. The success of such subspecies typing tools will eventually be measured by the size of the associated reference databases accessible over the internet. Three methods have shown some potential in this direction, the so-called spoligotyping assay (Mycobacterium tuberculosis, 40,000 entries database), Multiple Loci Sequence Typing (MLST; up to a few thousands entries for the more than 20 bacterial species), and more recently Multiple Loci VNTR Analysis (MLVA; up to a few hundred entries, assays available for more than 20 pathogens). In the present report we will review the current status of the tools and resources we have developed along the past seven years to help in the setting-up or the use of MLVA assays or lately for analysing Clustered Regularly Interspaced Short Palindromic Repeats called CRISPRs which are the basis for spoligotyping assays. 相似文献
38.
Carl L. Keen Bo Lönnerdal Theodore N. Stein Lucille S. Hurley 《Biological trace element research》1980,2(3):221-227
The presence of superoxide dismutase in bovine and human milk was investigated by ultrafiltration, gel filtration, and isoelectric
focusing. Conclusive evidence for the presence of this enzyme in both milks is presented. The molecular weight of the enzyme
was estimated by gel filtration on Sephadex G-100 to be 30,000, which is consistent with reported values for the copper, zinc
form of superoxide dismutase. In addition, enzyme activity was inhibited by cyanide, thus eliminating the possibility that
the enzyme was present in the manganese form. Several isoenzymes were detected by isoelectric focusing in polyacrylamide gel,
and the isoenzyme pattern in bovine milk was the same as that found for bovine plasma, suggesting that milk superoxide dismutase
originates from plasma. It may be that the presence of copper, zinc superoxide dismutase in milk is important for the maintenance
of its oxidative stability. 相似文献
39.
40.
G100R mutation within 4070A murine leukemia virus Env increases virus receptor binding,kinetics of entry,and viral transduction efficiency 下载免费PDF全文
Passage of 4070A murine leukemia virus (MuLV) in D17 cells resulted in a G-to-R change at position 100 within the VRA of the envelope protein (Env). Compared with 4070A MuLV, virus with the G100R Env displayed enhanced binding on target cells, internalized the virus more rapidly, and increased the overall viral titer in multiple cell types. This provides a direct correlation between binding strength and efficiency of viral entry. Deletion of a His residue at the SU N terminus eliminated the transduction efficiency by the G100R virus, suggesting that the G100R virus maintains the regulatory characteristics of 4070A viral entry. The improved transduction efficiency of G100R Env would be an asset for gene delivery systems. 相似文献